inets,tftp: Break out TFTP from inets

- Create directory structure
- Move code, tests, documentation from inets
- Add inets_tftp_wrapper
- Add tftp app to run-dialyzer script

Change-Id: I6a142ae66cecb9a1821cbf9ea6a45f66a836763d

35 files changed, 6094 insertions, 0 deletions

diff --git a/lib/tftp/Makefile b/lib/tftp/Makefile
new file mode 100644
index 0000000000..5c3ed52b28
--- /dev/null
+++ b/lib/tftp/Makefile
@@ -0,0 +1,78 @@
+#
+# %CopyrightBegin%
+#
+# Copyright Ericsson AB 1996-2016. All Rights Reserved.
+#
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at
+#
+#     http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
+#
+# %CopyrightEnd%
+#
+#
+include $(ERL_TOP)/make/target.mk
+include $(ERL_TOP)/make/$(TARGET)/otp.mk
+
+# ----------------------------------------------------
+# Macros
+# ----------------------------------------------------
+
+SUB_DIRECTORIES = src doc/src 
+
+include vsn.mk
+VSN = $(TFTP_VSN)
+
+SPECIAL_TARGETS = 
+
+DIA_PLT      = ./priv/plt/$(APPLICATION).plt
+DIA_ANALYSIS = $(basename $(DIA_PLT)).dialyzer_analysis
+
+
+# ----------------------------------------------------
+# Default Subdir Targets
+# ----------------------------------------------------
+include $(ERL_TOP)/make/otp_subdir.mk
+
+.PHONY: info gclean dialyzer dialyzer_plt dclean
+
+info:
+	@echo "OS:        $(OS)"
+	@echo "DOCB:      $(DOCB)"
+	@echo ""
+	@echo "TFTP_VSN:   $(TFTP_VSN)"
+	@echo "APP_VSN:   $(APP_VSN)"
+	@echo ""
+	@echo "DIA_PLT:      $(DIA_PLT)"
+	@echo "DIA_ANALYSIS: $(DIA_ANALYSIS)"
+	@echo ""
+
+gclean: 
+	git clean -fXd
+
+dclean:
+	rm -f $(DIA_PLT)
+	rm -f $(DIA_ANALYSIS)
+
+dialyzer_plt: $(DIA_PLT)
+
+$(DIA_PLT): 
+	@echo "Building $(APPLICATION) plt file"
+	@dialyzer --build_plt \
+                  --output_plt $@ \
+                  -r ../$(APPLICATION)/ebin \
+                  --output $(DIA_ANALYSIS) \
+                  --verbose
+
+dialyzer: $(DIA_PLT)
+	@echo "Running dialyzer on $(APPLICATION)"
+	@dialyzer --plt $< \
+                  ../$(APPLICATION)/ebin \
+                  --verbose
diff --git a/lib/tftp/doc/html/.gitignore b/lib/tftp/doc/html/.gitignore
new file mode 100644
index 0000000000..e69de29bb2
--- /dev/null
+++ b/lib/tftp/doc/html/.gitignore
diff --git a/lib/tftp/doc/man3/.gitignore b/lib/tftp/doc/man3/.gitignore
new file mode 100644
index 0000000000..e69de29bb2
--- /dev/null
+++ b/lib/tftp/doc/man3/.gitignore
diff --git a/lib/tftp/doc/man6/.gitignore b/lib/tftp/doc/man6/.gitignore
new file mode 100644
index 0000000000..e69de29bb2
--- /dev/null
+++ b/lib/tftp/doc/man6/.gitignore
diff --git a/lib/tftp/doc/pdf/.gitignore b/lib/tftp/doc/pdf/.gitignore
new file mode 100644
index 0000000000..e69de29bb2
--- /dev/null
+++ b/lib/tftp/doc/pdf/.gitignore
diff --git a/lib/tftp/doc/src/Makefile b/lib/tftp/doc/src/Makefile
new file mode 100644
index 0000000000..cd97bdf7ff
--- /dev/null
+++ b/lib/tftp/doc/src/Makefile
@@ -0,0 +1,153 @@
+#
+# %CopyrightBegin%
+#
+# Copyright Ericsson AB 1997-2018. All Rights Reserved.
+#
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at
+#
+#     http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
+#
+# %CopyrightEnd%
+#
+#
+include $(ERL_TOP)/make/target.mk
+include $(ERL_TOP)/make/$(TARGET)/otp.mk
+
+# ----------------------------------------------------
+# Application version
+# ----------------------------------------------------
+include ../../vsn.mk
+VSN=$(TFTP_VSN)
+
+# ----------------------------------------------------
+# Release directory specification
+# ----------------------------------------------------
+RELSYSDIR = $(RELEASE_PATH)/lib/$(APPLICATION)-$(VSN)
+
+
+# ----------------------------------------------------
+# Target Specs
+# ----------------------------------------------------
+XML_APPLICATION_FILES = ref_man.xml
+
+XML_CHAPTER_FILES = \
+	introduction.xml \
+	notes.xml
+
+XML_REF3_FILES = \
+	tftp.xml
+
+XML_PART_FILES = \
+	part.xml
+
+BOOK_FILES = book.xml
+
+XML_FILES = \
+	$(BOOK_FILES)        \
+	$(XML_CHAPTER_FILES) \
+	$(XML_PART_FILES)    \
+	$(XML_REF6_FILES)    \
+	$(XML_REF3_FILES)    \
+	$(XML_APPLICATION_FILES)
+
+# GIF_FILES = tftp.gif
+
+
+# ----------------------------------------------------
+
+HTML_FILES = \
+	$(XML_APPLICATION_FILES:%.xml=$(HTMLDIR)/%.html) \
+	$(XML_PART_FILES:%.xml=$(HTMLDIR)/%.html)
+
+INFO_FILE = ../../info
+EXTRA_FILES = \
+	$(XML_REF3_FILES:%.xml=$(HTMLDIR)/%.html) \
+	$(XML_REF6_FILES:%.xml=$(HTMLDIR)/%.html) \
+	$(XML_CHAPTER_FILES:%.xml=$(HTMLDIR)/%.html)
+
+MAN3_FILES = $(XML_REF3_FILES:%.xml=$(MAN3DIR)/%.3)
+
+HTML_REF_MAN_FILE = $(HTMLDIR)/index.html
+
+TOP_PDF_FILE = $(PDFDIR)/$(APPLICATION)-$(VSN).pdf
+
+# ----------------------------------------------------
+# FLAGS
+# ----------------------------------------------------
+XML_FLAGS +=
+DVIPS_FLAGS +=
+
+# ----------------------------------------------------
+# Targets
+# ----------------------------------------------------
+$(HTMLDIR)/%.gif: %.gif
+	$(INSTALL_DATA) $< $@
+
+docs: pdf html man
+
+ldocs: local_docs
+
+$(TOP_PDF_FILE): $(XML_FILES)
+
+pdf: $(TOP_PDF_FILE)
+
+html: gifs $(HTML_REF_MAN_FILE)
+
+clean clean_docs: clean_html clean_man clean_pdf
+	rm -f errs core *~
+
+man: $(MAN3_FILES)
+
+gifs: $(GIF_FILES:%=$(HTMLDIR)/%)
+
+debug opt:
+
+clean_pdf:
+	rm -f $(TOP_PDF_FILE) $(TOP_PDF_FILE:%.pdf=%.fo)
+
+clean_html:
+	rm -rf $(TOP_HTML_FILES) $(HTMLDIR)/*
+
+clean_man:
+	rm -f $(MAN3_FILES)
+
+
+# ----------------------------------------------------
+# Release Target
+# ----------------------------------------------------
+include $(ERL_TOP)/make/otp_release_targets.mk
+
+release_docs_spec: docs
+	$(INSTALL_DIR) "$(RELSYSDIR)/doc/pdf"
+	$(INSTALL_DATA) $(TOP_PDF_FILE) "$(RELSYSDIR)/doc/pdf"
+	$(INSTALL_DIR) "$(RELSYSDIR)/doc/html"
+	$(INSTALL_DATA) $(HTMLDIR)/* "$(RELSYSDIR)/doc/html"
+	$(INSTALL_DATA) $(INFO_FILE) "$(RELSYSDIR)"
+	$(INSTALL_DIR) "$(RELEASE_PATH)/man/man3"
+	$(INSTALL_DATA) $(MAN3DIR)/* "$(RELEASE_PATH)/man/man3"
+
+release_spec:
+
+info:
+	@echo "GIF_FILES:\n$(GIF_FILES)"
+	@echo ""
+	@echo "EXTRA_FILES:\n$(EXTRA_FILES)"
+	@echo ""
+	@echo "HTML_FILES:\n$(HTML_FILES)"
+	@echo ""
+	@echo "TOP_HTML_FILES:\n$(TOP_HTML_FILES)"
+	@echo ""
+	@echo "XML_REF3_FILES:\n$(XML_REF3_FILES)"
+	@echo ""
+	@echo "XML_REF6_FILES:\n$(XML_REF6_FILES)"
+	@echo ""
+	@echo "XML_CHAPTER_FILES:\n$(XML_CHAPTER_FILES)"
+	@echo ""
diff --git a/lib/tftp/doc/src/book.xml b/lib/tftp/doc/src/book.xml
new file mode 100644
index 0000000000..cf8032a4e9
--- /dev/null
+++ b/lib/tftp/doc/src/book.xml
@@ -0,0 +1,49 @@
+<?xml version="1.0" encoding="utf-8" ?>
+<!DOCTYPE book SYSTEM "book.dtd">
+
+<book xmlns:xi="http://www.w3.org/2001/XInclude">
+  <header titlestyle="normal">
+    <copyright>
+      <year>1997</year><year>2018</year>
+      <holder>Ericsson AB. All Rights Reserved.</holder>
+    </copyright>
+    <legalnotice>
+      Licensed under the Apache License, Version 2.0 (the "License");
+      you may not use this file except in compliance with the License.
+      You may obtain a copy of the License at
+ 
+          http://www.apache.org/licenses/LICENSE-2.0
+
+      Unless required by applicable law or agreed to in writing, software
+      distributed under the License is distributed on an "AS IS" BASIS,
+      WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+      See the License for the specific language governing permissions and
+      limitations under the License.
+    
+    </legalnotice>
+
+    <title>TFTP</title>
+    <prepared>Péter Dimitrov</prepared>
+    <docno></docno>
+    <date>2018-03-22</date>
+    <rev>1.0</rev>
+    <file>book.sgml</file>
+  </header>
+  <insidecover>
+  </insidecover>
+  <pagetext>TFTP</pagetext>
+  <preamble>
+    <contents level="2"></contents>
+  </preamble>
+  <parts lift="no">
+    <xi:include href="part.xml"/>
+  </parts>
+  <applications>
+    <xi:include href="ref_man.xml"/>
+  </applications>
+  <releasenotes>
+    <xi:include href="notes.xml"/>
+  </releasenotes>
+  <listofterms></listofterms>
+  <index></index>
+</book>
diff --git a/lib/tftp/doc/src/introduction.xml b/lib/tftp/doc/src/introduction.xml
new file mode 100644
index 0000000000..949438ae92
--- /dev/null
+++ b/lib/tftp/doc/src/introduction.xml
@@ -0,0 +1,46 @@
+<?xml version="1.0" encoding="utf-8" ?>
+<!DOCTYPE chapter SYSTEM "chapter.dtd">
+
+<chapter>
+  <header>
+    <copyright>
+      <year>1997</year><year>2018</year>
+      <holder>Ericsson AB. All Rights Reserved.</holder>
+    </copyright>
+    <legalnotice>
+      The contents of this file are subject to the Erlang Public License,
+      Version 1.1, (the "License"); you may not use this file except in
+      compliance with the License. You should have received a copy of the
+      Erlang Public License along with this software. If not, it can be
+      retrieved online at http://www.erlang.org/.
+    
+      Software distributed under the License is distributed on an "AS IS"
+      basis, WITHOUT WARRANTY OF ANY KIND, either express or implied. See
+      the License for the specific language governing rights and limitations
+      under the License.
+    
+    </legalnotice>
+
+    <title>Introduction</title>
+    <prepared>Péter Dimitrov</prepared>
+    <responsible></responsible>
+    <docno></docno>
+    <approved></approved>
+    <checked></checked>
+    <date>2018-03-22</date>
+    <rev>A</rev>
+    <file>introduction.xml</file>
+  </header>
+
+  <section>
+    <title>Purpose</title>
+    <p>A <c>TFTP</c> client and server.</p>
+  </section>
+
+  <section>
+    <title>Prerequisites</title>
+    <p>It is assumed that the reader is familiar with the Erlang
+      programming language, concepts of OTP, and has a basic
+      understanding of the TFTP protocol.</p>
+  </section>
+</chapter>
diff --git a/lib/tftp/doc/src/notes.xml b/lib/tftp/doc/src/notes.xml
new file mode 100644
index 0000000000..f7525c8f3e
--- /dev/null
+++ b/lib/tftp/doc/src/notes.xml
@@ -0,0 +1,53 @@
+<?xml version="1.0" encoding="utf-8" ?>
+<!DOCTYPE chapter SYSTEM "chapter.dtd">
+
+<chapter>
+  <header>
+    <copyright>
+      <year>2002</year><year>2018</year>
+      <holder>Ericsson AB. All Rights Reserved.</holder>
+    </copyright>
+    <legalnotice>
+      Licensed under the Apache License, Version 2.0 (the "License");
+      you may not use this file except in compliance with the License.
+      You may obtain a copy of the License at
+ 
+          http://www.apache.org/licenses/LICENSE-2.0
+
+      Unless required by applicable law or agreed to in writing, software
+      distributed under the License is distributed on an "AS IS" BASIS,
+      WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+      See the License for the specific language governing permissions and
+      limitations under the License.
+      
+    </legalnotice>
+    
+    <title>TFTP Release Notes</title>
+    <prepared></prepared>
+    <responsible></responsible>
+    <docno></docno>
+    <approved></approved>
+    <checked></checked>
+    <date>2018-03-22</date>
+    <rev>A</rev>
+    <file>notes.xml</file>
+  </header>
+  
+  <section><title>TFTP 1.0.0</title>
+
+    <section><title>First released version</title>
+      <list>
+        <item>
+          <p>
+	    Inets application was split into multiple smaller protocol specific applications.
+	    The TFTP application is a standalone TFTP client and server with the same functionality as
+	    TFTP in Inets.</p>
+          <p>
+	    Own Id: OTP-14113</p>
+        </item>
+      </list>
+    </section>
+
+</section>
+
+</chapter>
diff --git a/lib/tftp/doc/src/part.xml b/lib/tftp/doc/src/part.xml
new file mode 100644
index 0000000000..abbe0edcbf
--- /dev/null
+++ b/lib/tftp/doc/src/part.xml
@@ -0,0 +1,36 @@
+<?xml version="1.0" encoding="utf-8" ?>
+<!DOCTYPE part SYSTEM "part.dtd">
+
+<part xmlns:xi="http://www.w3.org/2001/XInclude">
+  <header>
+    <copyright>
+      <year>2004</year><year>2018</year>
+      <holder>Ericsson AB. All Rights Reserved.</holder>
+    </copyright>
+    <legalnotice>
+      Licensed under the Apache License, Version 2.0 (the "License");
+      you may not use this file except in compliance with the License.
+      You may obtain a copy of the License at
+ 
+          http://www.apache.org/licenses/LICENSE-2.0
+
+      Unless required by applicable law or agreed to in writing, software
+      distributed under the License is distributed on an "AS IS" BASIS,
+      WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+      See the License for the specific language governing permissions and
+      limitations under the License.
+    
+    </legalnotice>
+
+    <title>TFTP User's Guide</title>
+    <prepared>Péter Dimitrov</prepared>
+    <docno></docno>
+    <date>2018-03-22</date>
+    <rev>A</rev>
+    <file>part.sgml</file>
+  </header>
+  <description>
+    <p>The <c>TFTP</c> application provides a TFTP client and server.</p>
+  </description>
+  <xi:include href="introduction.xml"/>
+</part>
diff --git a/lib/tftp/doc/src/ref_man.xml b/lib/tftp/doc/src/ref_man.xml
new file mode 100644
index 0000000000..41a6cc6d52
--- /dev/null
+++ b/lib/tftp/doc/src/ref_man.xml
@@ -0,0 +1,36 @@
+<?xml version="1.0" encoding="utf-8" ?>
+<!DOCTYPE application SYSTEM "application.dtd">
+
+<application xmlns:xi="http://www.w3.org/2001/XInclude">
+  <header>
+    <copyright>
+      <year>1997</year><year>2018</year>
+      <holder>Ericsson AB. All Rights Reserved.</holder>
+    </copyright>
+    <legalnotice>
+      Licensed under the Apache License, Version 2.0 (the "License");
+      you may not use this file except in compliance with the License.
+      You may obtain a copy of the License at
+ 
+          http://www.apache.org/licenses/LICENSE-2.0
+
+      Unless required by applicable law or agreed to in writing, software
+      distributed under the License is distributed on an "AS IS" BASIS,
+      WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+      See the License for the specific language governing permissions and
+      limitations under the License.
+
+    </legalnotice>
+
+    <title>TFTP Reference Manual</title>
+    <prepared>Péter Dimitrov</prepared>
+    <docno></docno>
+    <date>2018-03-22</date>
+    <rev>1.0</rev>
+    <file>ref_man.xml</file>
+  </header>
+  <description>
+    <p>The <c>TFTP</c> application.</p>
+  </description>
+  <xi:include href="tftp.xml"/>
+</application>
diff --git a/lib/tftp/doc/src/tftp.xml b/lib/tftp/doc/src/tftp.xml
new file mode 100644
index 0000000000..c4d6a4e6d0
--- /dev/null
+++ b/lib/tftp/doc/src/tftp.xml
@@ -0,0 +1,643 @@
+<?xml version="1.0" encoding="utf-8" ?>
+<!DOCTYPE erlref SYSTEM "erlref.dtd">
+
+<erlref>
+  <header>
+    <copyright>
+      <year>2006</year><year>2018</year>
+      <holder>Ericsson AB. All Rights Reserved.</holder>
+    </copyright>
+    <legalnotice>
+      Licensed under the Apache License, Version 2.0 (the "License");
+      you may not use this file except in compliance with the License.
+      You may obtain a copy of the License at
+ 
+          http://www.apache.org/licenses/LICENSE-2.0
+
+      Unless required by applicable law or agreed to in writing, software
+      distributed under the License is distributed on an "AS IS" BASIS,
+      WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+      See the License for the specific language governing permissions and
+      limitations under the License.
+    
+    </legalnotice>
+
+    <title>tftp</title>
+    <prepared></prepared>
+    <docno></docno>
+    <date></date>
+    <rev></rev>
+  </header>
+  <module>tftp</module>
+  <modulesummary>Trivial FTP.</modulesummary>
+  <description>
+    <p>This is a complete implementation of the following IETF standards:</p>
+    <list type="bulleted">
+      <item>RFC 1350, The TFTP Protocol (revision 2)</item>
+      <item>RFC 2347, TFTP Option Extension</item>
+      <item>RFC 2348, TFTP Blocksize Option</item>
+      <item>RFC 2349, TFTP Timeout Interval and Transfer Size Options</item>
+    </list>
+    <p>The only feature that not is implemented is
+      the "netascii" transfer mode.</p>
+    <p>The <seealso marker="#start/1">start/1</seealso> function starts
+      a daemon process listening for UDP packets on a port. When it
+      receives a request for read or write, it spawns a temporary server
+      process handling the transfer.</p>
+    <p>On the client side,
+      function <seealso marker="#read_file/3">read_file/3</seealso>
+      and <seealso marker="#write_file/3">write_file/3</seealso>
+      spawn a temporary client process establishing
+      contact with a TFTP daemon and perform the file transfer.</p>
+    <p><c>tftp</c> uses a callback module to handle the file
+      transfer. Two such callback modules are provided,
+      <c>tftp_binary</c> and <c>tftp_file</c>. See
+      <seealso marker="#read_file/3">read_file/3</seealso> and
+      <seealso marker="#write_file/3">write_file/3</seealso> for details.
+      You can also implement your own callback modules, see 
+      <seealso marker="#tftp_callback">CALLBACK FUNCTIONS</seealso>. 
+      A callback module provided by
+      the user is registered using option <c>callback</c>, see
+      <seealso marker="#options">DATA TYPES</seealso>.</p>
+  </description>
+  
+ <section>
+    <title>TFTP SERVER SERVICE START/STOP</title>
+    
+    <p>A TFTP server can be started dynamically
+      (when <c>tftp</c> is already started) by calling the <c>tftp</c> application 
+      API <c>tftp:start(ServiceConfig)</c>.
+      The <c>ServiceConfig</c> for TFTP is described in
+      the <seealso marker="#options">DATA TYPES</seealso>
+      section.</p>
+    
+    <p>The TFTP server can be stopped using <c>tftp:stop_service(Pid)</c>.</p>
+
+    <p>The TPFT client is of such a temporary nature that it is not
+      handled as a service in the <c>tftp</c> service framework.</p>
+    
+  </section>
+  
+  <section>
+    <marker id="options"></marker>
+    <title>DATA TYPES</title>
+    <p><c>ServiceConfig = Options</c></p>
+    <p><c>Options = [option()]</c></p>
+    <p>Most of the options are common for both the client and the server
+      side, but some of them differs a little. 
+      The available <c>option()</c>s are as follows:</p>
+    <taglist>
+      <tag><c>{debug, Level}</c></tag>
+      <item>
+        <p><c>Level = none | error | warning | brief | normal | verbose | all</c></p>
+        <p>Controls the level of debug printouts. 
+	Default is <c>none</c>.</p>
+      </item>
+      <tag><c>{host, Host}</c></tag>
+      <item>
+        <p><c>Host = hostname()</c>, see
+          <seealso marker="kernel:inet">inet(3)</seealso>.</p>
+        <p>The name or IP address of the host where the TFTP daemon
+          resides. This option is only used by the client.</p>
+      </item>
+      <tag><c>{port, Port}</c></tag>
+      <item>
+        <p><c>Port = int()</c></p>
+        <p>The TFTP port where the daemon listens. Defaults is
+          the standardized number 69. On the server side, it can
+          sometimes make sense to set it to 0, meaning that
+          the daemon just picks a free port (which one is
+          returned by function <c>info/1</c>).</p>
+        <p>If a socket is connected already, option
+          <c>{udp, [{fd, integer()}]}</c> can be used to pass the
+          open file descriptor to <c>gen_udp</c>. This can be automated
+          by using a command-line argument stating the
+          prebound file descriptor number. For example, if the
+          port is 69 and file descriptor 22 is opened by
+          <c>setuid_socket_wrap</c>, the command-line argument
+          "-tftpd_69 22" triggers the prebound file
+          descriptor 22 to be used instead of opening port 69.
+          The UDP option <c>{udp, [{fd, 22}]}</c> is automatically added.
+          See <c>init:get_argument/</c> about command-line arguments and
+          <c>gen_udp:open/2</c> about UDP options.</p>
+      </item>
+      <tag><c>{port_policy, Policy}</c></tag>
+      <item>
+        <p><c>Policy = random | Port | {range, MinPort, MaxPort}</c></p>
+	<p><c>Port = MinPort = MaxPort = int()</c></p>
+        <p>Policy for the selection of the temporary port that is used
+          by the server/client during the file transfer. Default is
+          <c>random</c>, which is the standardized policy. With this
+          policy a randomized free port is used. A single port or a range
+          of ports can be useful if the protocol passes through a
+          firewall.</p>
+      </item>
+      <tag><c>{udp, Options}</c></tag>
+      <item>
+        <p><c>Options = [Opt]</c>, see
+          <seealso marker="kernel:gen_udp#open/1">gen_udp:open/2</seealso>.</p>
+      </item>
+      <tag><c>{use_tsize, Bool}</c></tag>
+      <item>
+        <p><c>Bool = bool()</c></p>
+        <p>Flag for automated use of option <c>tsize</c>. With
+          this set to <c>true</c>, the <c>write_file/3</c> client
+          determines the filesize and sends it to the server as
+          the standardized <c>tsize</c> option. A <c>read_file/3</c>
+          client acquires only a filesize from the server by sending
+          a zero <c>tsize</c>.</p>
+      </item>
+      <tag><c>{max_tsize, MaxTsize}</c></tag>
+      <item>
+        <p><c>MaxTsize = int() | infinity</c></p>
+        <p>Threshold for the maximal filesize in bytes. The transfer
+          is aborted if the limit is exceeded. 
+	  Default is <c>infinity</c>.</p>
+      </item>
+      <tag><c>{max_conn, MaxConn}</c></tag>
+      <item>
+        <p><c>MaxConn = int() | infinity</c></p>
+        <p>Threshold for the maximal number of active connections.
+          The daemon rejects the setup of new connections if
+          the limit is exceeded. Default is <c>infinity</c>.</p>
+      </item>
+      <tag><c>{TftpKey, TftpVal}</c></tag>
+      <item>
+        <p><c>TftpKey = string()</c>          <br></br>
+<c>TftpVal = string()</c></p>
+        <p>Name and value of a TFTP option.</p>
+      </item>
+      <tag><c>{reject, Feature}</c></tag>
+      <item>
+        <p><c>Feature = Mode | TftpKey</c>          <br></br>
+<c>&nbsp;Mode = read | write</c>          <br></br>
+<c>&nbsp;TftpKey = string()</c></p>
+        <p>Controls which features to reject. This is
+          mostly useful for the server as it can restrict the use
+	  of certain TFTP options or read/write access.</p>
+      </item>
+      <tag><c>{callback, {RegExp, Module, State}}</c></tag>
+      <item>
+        <p><c>RegExp = string()</c>          <br></br>
+<c>Module = atom()</c>          <br></br>
+<c>State = term()</c></p>
+        <p>Registration of a callback module. When a file is to be
+          transferred, its local filename is matched to the regular
+          expressions of the registered callbacks. The first matching
+          callback is used during the transfer. See
+          <seealso marker="#read_file/3">read_file/3</seealso> and
+          <seealso marker="#write_file/3">write_file/3</seealso>.
+          </p>
+        <p>The callback module must implement the <c>tftp</c> behavior, see
+          <seealso marker="#tftp_callback">CALLBACK FUNCTIONS</seealso>.</p>
+      </item>
+
+   <tag><c>{logger, Module}</c></tag>
+      <item>
+        <p><c>Module = module()()</c></p>
+
+        <p>Callback module for customized logging of errors, warnings, and
+	  info messages. The callback module must implement the
+	  <c>tftp_logger</c> behavior, see
+          <seealso marker="#tftp_logger">LOGGER FUNCTIONS</seealso>.
+          The default module is <c>tftp_logger</c>.</p>
+      </item>
+
+      <tag><c>{max_retries, MaxRetries}</c></tag>
+      <item>
+        <p><c>MaxRetries = int()</c></p>
+
+        <p>Threshold for the maximal number of retries. By default
+	  the server/client tries to resend a message up to
+	  five times when the time-out expires.</p>
+      </item>
+    </taglist>
+  </section>
+
+  <funcs>
+    <func>
+      <name>change_config(daemons, Options) -> [{Pid, Result}]</name>
+      <fsummary>Changes configuration for all daemons.
+      </fsummary>
+      <type>
+        <v>Options = [option()]</v>
+        <v>Pid = pid()</v>
+        <v>Result = ok | {error, Reason}</v>
+        <v>Reason = term()</v>
+      </type>
+      <desc>
+        <p>Changes configuration for all TFTP daemon processes. </p>
+      </desc>
+    </func>
+
+    <func>
+      <name>change_config(servers, Options) -> [{Pid, Result}]</name>
+      <fsummary>Changes configuration for all servers.
+      </fsummary>
+      <type>
+        <v>Options = [option()]</v>
+        <v>Pid = pid()</v>
+        <v>Result = ok | {error, Reason}</v>
+        <v>Reason = term()</v>
+      </type>
+      <desc>
+        <p>Changes configuration for all TFTP server processes.</p>
+      </desc>
+    </func>
+
+    <func>
+      <name>change_config(Pid, Options) -> Result</name>
+      <fsummary>Changes configuration for a TFTP daemon, server, 
+      or client process.</fsummary>
+      <type>
+        <v>Pid = pid()</v>
+        <v>Options = [option()]</v>
+        <v>Result = ok | {error, Reason}</v>
+        <v>Reason = term()</v>
+      </type>
+      <desc>
+        <p>Changes configuration for a TFTP daemon, server, or client process.</p>
+      </desc>
+    </func>
+    
+    <func>
+      <name>info(daemons) -> [{Pid, Options}]</name>
+      <fsummary>Returns information about all daemons.</fsummary>
+      <type>
+        <v>Pid = [pid()()]</v>
+        <v>Options = [option()]</v>
+        <v>Reason = term()</v>
+      </type>
+      <desc>
+        <p>Returns information about all TFTP daemon processes.</p>
+      </desc>
+    </func>
+
+    <func>
+      <name>info(servers) -> [{Pid, Options}]</name>
+      <fsummary>Returns information about all servers.</fsummary>
+      <type>
+        <v>Pid = [pid()()]</v>
+        <v>Options = [option()]</v>
+        <v>Reason = term()</v>
+      </type>
+      <desc>
+        <p>Returns information about all TFTP server processes. </p>
+      </desc>
+    </func>
+
+    <func>
+      <name>info(Pid) -> {ok, Options} | {error, Reason}</name>
+      <fsummary>Returns information about a daemon, server, or client process.</fsummary>
+      <type>
+        <v>Options = [option()]</v>
+        <v>Reason = term()</v>
+      </type>
+      <desc>
+        <p>Returns information about a TFTP daemon, server, or client process.</p>
+      </desc>
+    </func>
+       
+    <func>
+      <name>read_file(RemoteFilename, LocalFilename, Options) -> {ok, LastCallbackState} | {error, Reason}</name>
+      <fsummary>Reads a (virtual) file from a TFTP server.</fsummary>
+      <type>
+        <v>RemoteFilename = string()</v>
+        <v>LocalFilename = binary | string()</v>
+        <v>Options = [option()]</v>
+        <v>LastCallbackState = term()</v>
+        <v>Reason = term()</v>
+      </type>
+      <desc>
+        <p>Reads a (virtual) file <c>RemoteFilename</c> from a TFTP
+	server.</p>
+	<p>If <c>LocalFilename</c> is the atom <c>binary</c>,
+	<c>tftp_binary</c> is used as callback module. It concatenates
+	all transferred blocks and returns them as one single binary
+	in <c>LastCallbackState</c>.</p>
+	<p>If <c>LocalFilename</c> is a string and there are no
+	registered callback modules, <c>tftp_file</c> is used as
+	callback module. It writes each transferred block to the file
+	named <c>LocalFilename</c> and returns the number of
+	transferred bytes in <c>LastCallbackState</c>.</p>
+	<p>If <c>LocalFilename</c> is a string and there are registered
+	callback modules, <c>LocalFilename</c> is tested against
+	the regexps of these and the callback module corresponding to
+	the first match is used, or an error tuple is returned if no
+	matching regexp is found.</p>
+      </desc>	
+    </func>
+    
+    <func>
+       <name>start(Options) -> {ok, Pid} | {error, Reason}</name>
+      <fsummary>Starts a daemon process.</fsummary>
+      <type>
+        <v>Options = [option()]</v>
+        <v>Pid = pid()</v>
+        <v>Reason = term()</v>
+      </type>
+      <desc>
+        <p>Starts a daemon process listening for UDP packets on a
+	port. When it receives a request for read or write, it spawns
+	a temporary server process handling the actual transfer
+	of the (virtual) file.</p>
+      </desc>
+    </func>
+
+    <func>
+      <name>write_file(RemoteFilename, LocalFilename, Options) -> {ok, LastCallbackState} | {error, Reason}</name>
+      <fsummary>Writes a (virtual) file to a TFTP server.</fsummary>
+      <type>
+        <v>RemoteFilename = string()</v>
+        <v>LocalFilename = binary() | string()</v>
+        <v>Options = [option()]</v>
+        <v>LastCallbackState = term()</v>
+        <v>Reason = term()</v>
+      </type>
+      <desc>
+        <p>Writes a (virtual) file <c>RemoteFilename</c> to a TFTP
+          server.</p>
+        <p>If <c>LocalFilename</c> is a binary, <c>tftp_binary</c> is
+          used as callback module. The binary is transferred block by
+          block and the number of transferred bytes is returned in
+          <c>LastCallbackState</c>.</p>
+        <p>If <c>LocalFilename</c> is a string and there are no
+          registered callback modules, <c>tftp_file</c> is used as
+          callback module. It reads the file named <c>LocalFilename</c>
+          block by block and returns the number of transferred bytes
+          in <c>LastCallbackState</c>.</p>
+        <p>If <c>LocalFilename</c> is a string and there are registered
+	callback modules, <c>LocalFilename</c> is tested against
+	the regexps of these and the callback module corresponding to
+	the first match is used, or an error tuple is returned if no
+	matching regexp is found.</p>
+      </desc>
+    </func>
+  </funcs>
+
+  <section>
+    <marker id="tftp_callback"></marker>
+    <title>CALLBACK FUNCTIONS</title>
+    <p>A <c>tftp</c> callback module is to be implemented as a
+      <c>tftp</c> behavior and export the functions listed
+      in the following.</p>
+    <p>On the server side, the callback interaction starts with a call to
+      <c>open/5</c> with the registered initial callback state.
+      <c>open/5</c> is expected to open the (virtual) file. Then either
+      function <c>read/1</c> or <c>write/2</c> is invoked
+      repeatedly, once per transferred block. At each function call,
+      the state returned from the previous call is obtained. When
+      the last block is encountered, function <c>read/1</c> or
+      <c>write/2</c> is expected to close the (virtual) file
+      and return its last state. Function <c>abort/3</c> is only
+      used in error situations. Function <c>prepare/5</c> is not used on
+      the server side.</p>
+    <p>On the client side, the callback interaction is the same, but it
+      starts and ends a bit differently. It starts with a call to
+      <c>prepare/5</c> with the same arguments as <c>open/5</c> takes.
+      <c>prepare/5</c> is expected to validate the TFTP options
+      suggested by the user and to return the subset of them that it
+      accepts. Then the options are sent to the server, which performs
+      the same TFTP option negotiation procedure. The options that are
+      accepted by the server are forwarded to function <c>open/5</c>
+      on the client side. On the client side, function <c>open/5</c>
+      must accept all option as-is or reject the transfer. Then
+      the callback interaction follows the same pattern as described
+      for the server side. When the last block is encountered in
+      <c>read/1</c> or <c>write/2</c>, the returned state is forwarded to
+      the user and returned from <c>read_file</c>/3 or
+      <c>write_file/3</c>.</p>
+
+    <p> If a callback (performing the file access
+    in the TFTP server) takes too long time (more than
+    the double TFTP time-out), the server aborts the
+    connection and sends an error reply to the client.
+    This implies that the server releases resources
+    attached to the connection faster than before. The
+    server simply assumes that the client has given
+    up.</p>
+
+    <p>If the TFTP server receives yet another request from
+    the same client (same host and port) while it
+    already has an active connection to the client, it
+    ignores the new request if the request is
+    equal to the first one (same filename and options).
+    This implies that the (new) client will be served
+    by the already ongoing connection on the server
+    side. By not setting up yet another connection, in
+    parallel with the ongoing one, the server
+    consumes less resources.</p>
+    
+    <marker id="prepare"></marker>
+  </section>
+
+  <funcs>
+     <func>
+      <name>Module:abort(Code, Text, State) -> ok</name>
+      <fsummary>Aborts the file transfer.</fsummary>
+      <type>
+        <v>Code = undef | enoent | eacces | enospc</v>
+        <v>&nbsp;&nbsp;| badop | eexist | baduser | badopt</v>
+        <v>&nbsp;&nbsp;| int()</v>
+        <v>Text = string()</v>
+        <v>State = term()</v>
+      </type>
+      <desc>
+        <p>Invoked when the file transfer is aborted.</p>
+        <p>The callback function is expected to clean
+	up its used resources after the aborted file
+	transfer, such as closing open file
+	descriptors and so on. The function is not
+	invoked if any of the other callback
+	functions returns an error, as it is
+	expected that they already have cleaned up
+	the necessary resources. However, it is
+	invoked if the functions fail (crash).</p>
+      </desc>
+    </func>
+    
+      <func>
+      <name>Module:open(Peer, Access, Filename, Mode, SuggestedOptions, State) -> {ok, AcceptedOptions, NewState} | {error, {Code, Text}}</name>
+      <fsummary>Opens a file for read or write access.</fsummary>
+      <type>
+        <v>Peer = {PeerType, PeerHost, PeerPort}</v>
+        <v>PeerType = inet | inet6</v>
+        <v>PeerHost = ip_address()</v>
+        <v>PeerPort = integer()</v>
+        <v>Access = read | write</v>
+        <v>Filename = string()</v>
+        <v>Mode = string()</v>
+        <v>SuggestedOptions = AcceptedOptions = [{Key, Value}]</v>
+        <v>&nbsp;Key = Value = string()</v>
+        <v>State = InitialState | term()</v>
+        <v>&nbsp;InitialState = [] | [{root_dir, string()}]</v>
+        <v>NewState = term()</v>
+        <v>Code = undef | enoent | eacces | enospc</v>
+        <v>&nbsp;&nbsp;| badop | eexist | baduser | badopt</v>
+        <v>&nbsp;&nbsp;| int()</v>
+        <v>Text = string()</v>
+      </type>
+      <desc>
+        <p>Opens a file for read or write access.</p>
+        <p>On the client side, where the <c>open/5</c> call has been
+	preceded by a call to <c>prepare/5</c>, all options must be
+	accepted or rejected.</p>
+	<p>On the server side, where there is no preceding
+	<c>prepare/5</c> call, no new options can be added, but
+	those present in <c>SuggestedOptions</c> can be
+	omitted or replaced with new values in <c>AcceptedOptions</c>.</p>
+    
+	<marker id="read"></marker>
+      </desc>
+    </func>
+    
+    <func>
+      <name>Module:prepare(Peer, Access, Filename, Mode, SuggestedOptions, InitialState) -> {ok, AcceptedOptions, NewState} | {error, {Code, Text}}</name>
+      <fsummary>Prepares to open a file on the client side.</fsummary>
+      <type>
+        <v>Peer = {PeerType, PeerHost, PeerPort}</v>
+        <v>PeerType = inet | inet6</v>
+        <v>PeerHost = ip_address()</v>
+        <v>PeerPort = integer()</v>
+        <v>Access = read | write</v>
+        <v>Filename = string()</v>
+        <v>Mode = string()</v>
+        <v>SuggestedOptions = AcceptedOptions = [{Key, Value}]</v>
+        <v>&nbsp;Key = Value = string()</v>
+        <v>InitialState = [] | [{root_dir, string()}]</v>
+        <v>NewState = term()</v>
+        <v>Code = undef | enoent | eacces | enospc</v>
+        <v>&nbsp;&nbsp;| badop | eexist | baduser | badopt</v>
+        <v>&nbsp;&nbsp;| int()</v>
+        <v>Text = string()</v>
+      </type>
+      <desc>
+	<p>Prepares to open a file on the client side.</p>
+	<p>No new options can be added, but those present in
+	<c>SuggestedOptions</c> can be omitted or replaced with new
+	values in <c>AcceptedOptions</c>.</p>
+	<p>This is followed by a call to <c>open/4</c> before any
+	read/write access is performed. <c>AcceptedOptions</c> is
+	sent to the server, which replies with the options that it
+	accepts. These are then forwarded to <c>open/4</c> as
+	<c>SuggestedOptions</c>.</p>
+    
+	<marker id="open"></marker>
+      </desc>
+    </func>
+
+    <func>
+      <name>Module:read(State) -> {more, Bin, NewState} | {last, Bin, FileSize} | {error, {Code, Text}}</name>
+      <fsummary>Reads a chunk from the file.</fsummary>
+      <type>
+        <v>State = NewState = term()</v>
+        <v>Bin = binary()</v>
+        <v>FileSize = int()</v>
+        <v>Code = undef | enoent | eacces | enospc</v>
+        <v>&nbsp;&nbsp;| badop | eexist | baduser | badopt</v>
+        <v>&nbsp;&nbsp;| int()</v>
+        <v>Text = string()</v>
+      </type>
+      <desc>
+        <p>Reads a chunk from the file.</p>
+        <p>The callback function is expected to close
+	the file when the last file chunk is
+	encountered. When an error is encountered,
+	the callback function is expected to clean
+	up after the aborted file transfer, such as
+	closing open file descriptors, and so on. In both
+	cases there will be no more calls to any of
+	the callback functions.</p>
+    
+	<marker id="write"></marker>
+      </desc>
+    </func>
+
+    <func>
+      <name>Module:write(Bin, State) -> {more, NewState} | {last, FileSize} | {error, {Code, Text}}</name>
+      <fsummary>Writes a chunk to the file.</fsummary>
+      <type>
+        <v>Bin = binary()</v>
+        <v>State = NewState = term()</v>
+        <v>FileSize = int()</v>
+        <v>Code = undef | enoent | eacces | enospc</v>
+        <v>&nbsp;&nbsp;| badop | eexist | baduser | badopt</v>
+        <v>&nbsp;&nbsp;| int()</v>
+        <v>Text = string()</v>
+      </type>
+      <desc>
+        <p>Writes a chunk to the file.</p>
+        <p>The callback function is expected to close
+	the file when the last file chunk is
+	encountered. When an error is encountered,
+	the callback function is expected to clean
+	up after the aborted file transfer, such as
+	closing open file descriptors, and so on. In both
+	cases there will be no more calls to any of
+	the callback functions.</p>
+    
+	<marker id="abort"></marker>
+      </desc>
+    </func>
+  </funcs>
+  
+  <section>
+    <marker id="tftp_logger"></marker>
+    <title>LOGGER FUNCTIONS</title>
+    
+    <p>A <c>tftp_logger</c> callback module is to be implemented as a
+    <c>tftp_logger</c> behavior and export the following functions:</p>
+    
+    <marker id="error_msg"></marker>
+    </section>
+
+  <funcs>
+    <func>
+      <name>Logger:error_msg(Format, Data) -> ok | exit(Reason)</name>
+      <fsummary>Logs an error message.</fsummary>
+      <type>
+        <v>Format = string()</v>
+        <v>Data = [term()]</v>
+        <v>Reason = term()</v>
+      </type>
+      <desc>
+	<p>Logs an error message. 
+	See <c>error_logger:error_msg/2</c> for details.</p>
+	
+	<marker id="warning_msg"></marker>
+      </desc>
+    </func>
+
+    <func>
+      <name>Logger:info_msg(Format, Data) -> ok | exit(Reason)</name>
+      <fsummary>Logs an info message.</fsummary>
+      <type>
+        <v>Format = string()</v>
+        <v>Data = [term()]</v>
+        <v>Reason = term()</v>
+      </type>
+      <desc>
+        <p>Logs an info message. 
+	See <c>error_logger:info_msg/2</c>  for details.</p>
+      </desc>
+    </func>
+    
+    <func>
+      <name>Logger:warning_msg(Format, Data) -> ok | exit(Reason)</name>
+      <fsummary>Logs a warning message.</fsummary>
+      <type>
+        <v>Format = string()</v>
+        <v>Data = [term()]</v>
+        <v>Reason = term()</v>
+      </type>
+      <desc>
+        <p>Logs a warning message. 
+	See <c>error_logger:warning_msg/2</c> for details.</p>
+	
+	<marker id="info_msg"></marker>
+      </desc>
+    </func>
+  </funcs>
+</erlref>
+
+
diff --git a/lib/tftp/ebin/.gitignore b/lib/tftp/ebin/.gitignore
new file mode 100644
index 0000000000..e69de29bb2
--- /dev/null
+++ b/lib/tftp/ebin/.gitignore
diff --git a/lib/tftp/info b/lib/tftp/info
new file mode 100644
index 0000000000..1220454351
--- /dev/null
+++ b/lib/tftp/info
@@ -0,0 +1,2 @@
+group: comm
+short: TFTP application
diff --git a/lib/tftp/src/Makefile b/lib/tftp/src/Makefile
new file mode 100644
index 0000000000..ed1551ba04
--- /dev/null
+++ b/lib/tftp/src/Makefile
@@ -0,0 +1,110 @@
+#
+# %CopyrightBegin%
+#
+# Copyright Ericsson AB 2005-2016. All Rights Reserved.
+#
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at
+#
+#     http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
+#
+# %CopyrightEnd%
+#
+#
+
+include $(ERL_TOP)/make/target.mk
+include $(ERL_TOP)/make/$(TARGET)/otp.mk
+
+# ----------------------------------------------------
+# Application version
+# ----------------------------------------------------
+include ../vsn.mk
+VSN = $(TFTP_VSN)
+
+# ----------------------------------------------------
+# Release directory specification
+# ----------------------------------------------------
+RELSYSDIR = $(RELEASE_PATH)/lib/$(APPLICATION)-$(VSN)
+
+# ----------------------------------------------------
+# Target Specs
+# ----------------------------------------------------
+BEHAVIOUR_MODULES=
+
+MODULES = \
+	tftp \
+	tftp_app \
+	tftp_binary \
+	tftp_engine \
+	tftp_file \
+	tftp_lib \
+	tftp_logger \
+	tftp_sup 
+
+HRL_FILES = tftp.hrl
+
+ERL_FILES= \
+	$(MODULES:%=%.erl) \
+	$(BEHAVIOUR_MODULES:%=%.erl)
+
+TARGET_FILES= $(MODULES:%=$(EBIN)/%.$(EMULATOR))
+
+BEHAVIOUR_TARGET_FILES= $(BEHAVIOUR_MODULES:%=$(EBIN)/%.$(EMULATOR))
+
+APP_FILE= tftp.app
+APPUP_FILE= tftp.appup
+
+APP_SRC= $(APP_FILE).src
+APP_TARGET= $(EBIN)/$(APP_FILE)
+APPUP_SRC= $(APPUP_FILE).src
+APPUP_TARGET= $(EBIN)/$(APPUP_FILE)
+
+# ----------------------------------------------------
+# FLAGS
+# ----------------------------------------------------
+
+
+# ----------------------------------------------------
+# Targets
+# ----------------------------------------------------
+
+$(TARGET_FILES): $(BEHAVIOUR_TARGET_FILES)
+
+debug opt: $(TARGET_FILES) $(APP_TARGET) $(APPUP_TARGET)
+
+clean:
+	rm -f $(TARGET_FILES) $(APP_TARGET) $(APPUP_TARGET) $(BEHAVIOUR_TARGET_FILES)
+	rm -f core
+
+$(APP_TARGET): $(APP_SRC) ../vsn.mk
+	$(vsn_verbose)sed -e 's;%VSN%;$(VSN);' $< > $@
+
+$(APPUP_TARGET): $(APPUP_SRC) ../vsn.mk
+	$(vsn_verbose)sed -e 's;%VSN%;$(VSN);' $< > $@
+
+docs:
+
+# ----------------------------------------------------
+# Release Target
+# ---------------------------------------------------- 
+include $(ERL_TOP)/make/otp_release_targets.mk
+
+release_spec: opt
+	$(INSTALL_DIR) "$(RELSYSDIR)/src"
+	$(INSTALL_DATA) $(ERL_FILES) $(HRL_FILES) "$(RELSYSDIR)/src"
+	$(INSTALL_DIR) "$(RELSYSDIR)/ebin"
+	$(INSTALL_DATA) $(BEHAVIOUR_TARGET_FILES) $(TARGET_FILES) $(APP_TARGET) \
+	$(APPUP_TARGET) "$(RELSYSDIR)/ebin"
+
+release_docs_spec:
+
+info:
+	@echo "APPLICATION       = $(APPLICATION)"
+	@echo "ERL_COMPILE_FLAGS = $(ERL_COMPILE_FLAGS)"
diff --git a/lib/tftp/src/tftp.app.src b/lib/tftp/src/tftp.app.src
new file mode 100644
index 0000000000..3f008573e8
--- /dev/null
+++ b/lib/tftp/src/tftp.app.src
@@ -0,0 +1,22 @@
+{application, tftp,
+ [{description, "TFTP application"},
+  {vsn, "1.0.0"},
+  {registered, []},
+  {mod, { tftp_app, []}},
+  {applications,
+   [kernel,
+    stdlib
+   ]},
+  {env,[]},
+  {modules, [
+             tftp,
+             tftp_app,
+             tftp_binary,
+             tftp_engine,
+             tftp_file,
+             tftp_lib,
+             tftp_logger,
+             tftp_sup
+            ]},
+  {runtime_dependencies, ["stdlib-3.5","kernel-6.0"]}
+ ]}.
diff --git a/lib/tftp/src/tftp.appup.src b/lib/tftp/src/tftp.appup.src
new file mode 100644
index 0000000000..06a0f0f9dc
--- /dev/null
+++ b/lib/tftp/src/tftp.appup.src
@@ -0,0 +1,26 @@
+%% -*- erlang -*-
+%% %CopyrightBegin%
+%%
+%% Copyright Ericsson AB 1999-2018. All Rights Reserved.
+%%
+%% Licensed under the Apache License, Version 2.0 (the "License");
+%% you may not use this file except in compliance with the License.
+%% You may obtain a copy of the License at
+%%
+%%     http://www.apache.org/licenses/LICENSE-2.0
+%%
+%% Unless required by applicable law or agreed to in writing, software
+%% distributed under the License is distributed on an "AS IS" BASIS,
+%% WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+%% See the License for the specific language governing permissions and
+%% limitations under the License.
+%%
+%% %CopyrightEnd%
+{"%VSN%",
+ [
+  {<<".*">>,[{restart_application, tftp}]}
+ ],
+ [
+  {<<".*">>,[{restart_application, tftp}]}
+ ]
+}.
diff --git a/lib/tftp/src/tftp.erl b/lib/tftp/src/tftp.erl
new file mode 100644
index 0000000000..27ed13694b
--- /dev/null
+++ b/lib/tftp/src/tftp.erl
@@ -0,0 +1,409 @@
+%%
+%% %CopyrightBegin%
+%% 
+%% Copyright Ericsson AB 2005-2016. All Rights Reserved.
+%% 
+%% Licensed under the Apache License, Version 2.0 (the "License");
+%% you may not use this file except in compliance with the License.
+%% You may obtain a copy of the License at
+%%
+%%     http://www.apache.org/licenses/LICENSE-2.0
+%%
+%% Unless required by applicable law or agreed to in writing, software
+%% distributed under the License is distributed on an "AS IS" BASIS,
+%% WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+%% See the License for the specific language governing permissions and
+%% limitations under the License.
+%% 
+%% %CopyrightEnd%
+%%
+%%
+
+%%%-------------------------------------------------------------------
+%%% File    : tftp.erl
+%%% Author  : Hakan Mattsson <[email protected]>
+%%% Description : Trivial FTP
+%%% Created : 18 May 2004 by Hakan Mattsson <[email protected]>
+%%%-------------------------------------------------------------------
+%%% 
+%%% This is a complete implementation of the following IETF standards:
+%%%
+%%%    RFC 1350, The TFTP Protocol (revision 2).
+%%%    RFC 2347, TFTP Option Extension.
+%%%    RFC 2348, TFTP Blocksize Option.
+%%%    RFC 2349, TFTP Timeout Interval and Transfer Size Options.
+%%%
+%%% The only feature that not is implemented in this release is
+%%% the "netascii" transfer mode.
+%%%
+%%% The start/1 function starts a daemon process which, listens for
+%%% UDP packets on a port. When it receives a request for read or
+%%% write it spawns a temporary server process which handles the
+%%% actual transfer of the file. On the client side the read_file/3
+%%% and write_file/3 functions spawns a temporary client process which
+%%% establishes contact with a TFTP daemon and performs the actual
+%%% transfer of the file.
+%%%
+%%% Most of the options are common for both the client and the server
+%%% side, but some of them differs a little. Here are the available
+%%% options:
+%%%     
+%%%   {debug, Level}
+%%%
+%%%     Level = none | error | warning brief | normal | verbose | all
+%%%     
+%%%     Controls the level of debug printouts. The default is none.
+%%%     
+%%%   {host, Host}
+%%%
+%%%     The name or IP address of the host where the TFTP daemon
+%%%     resides. This option is only used by the client. See
+%%%     'inet' about valid host names.
+%%%     
+%%%   {port, Port}
+%%%
+%%%     Port = integer()
+%%%     
+%%%     The TFTP port where the daemon listens. It defaults to the
+%%%     standardized number 69. On the server side it may sometimes
+%%%     make sense to set it to 0, which means that the daemon just
+%%%     will pick a free port (which is returned by the start/1
+%%%     function).
+%%%     
+%%%     If a socket has somehow already has been connected, the
+%%%     {udp, [{fd, integer()}]} option can be used to pass the
+%%%     open file descriptor to gen_udp. This can be automated
+%%%     a bit by using a command line argument stating the
+%%%     prebound file descriptor number. For example, if the
+%%%     Port is 69 and the file descriptor 22 has been opened by
+%%%     setuid_socket_wrap. Then the command line argument
+%%%     "-tftpd_69 22" will trigger the prebound file
+%%%     descriptor 22 to be used instead of opening port 69.
+%%%     The UDP option {udp, [{fd, 22}]} autmatically be added.
+%%%     See init:get_argument/ about command line arguments and
+%%%     gen_udp:open/2 about UDP options.
+%%%
+%%%   {port_policy, Policy}
+%%%
+%%%     Policy = random | Port | {range, MinPort, MaxPort}
+%%%     Port = MinPort = MaxPort = integer()
+%%%     
+%%%     Policy for the selection of the temporary port which is used
+%%%     by the server/client during the file transfer. It defaults to
+%%%     'random' which is the standardized policy. With this policy a
+%%%     randomized free port used. A single port or a range of ports
+%%%     can be useful if the protocol should pass thru a firewall.
+%%%   
+%%%   {prebound_fd, InitArgFlag}
+%%%
+%%%     InitArgFlag = atom()
+%%%
+%%%     If a socket has somehow already has been connected, the
+%%%     {udp, [{fd, integer()}]} option can be used to pass the
+%%%     open file descriptor to gen_udp.
+%%%
+%%%     The prebound_fd option makes it possible to pass give the
+%%%     file descriptor as a command line argument. The typical
+%%%     usage is when used in conjunction with setuid_socket_wrap
+%%%     to be able to open privileged sockets. For example if the
+%%%     file descriptor 22 has been opened by setuid_socket_wrap
+%%%     and you have choosen my_tftp_fd as init argument, the
+%%%     command line should like this "erl -my_tftp_fd 22" and 
+%%%     FileDesc should be set to my_tftpd_fd. This would 
+%%%     automatically imply {fd, 22} to be set as UDP option.
+%%%   
+%%%   {udp, UdpOptions}
+%%%
+%%%      Options to gen_udp:open/2.
+%%%
+%%%   {use_tsize, Bool}
+%%%
+%%%     Bool = boolean()
+%%%     
+%%%     Flag for automated usage of the "tsize" option. With this set
+%%%     to true, the write_file/3 client will determine the filesize
+%%%     and send it to the server as the standardized "tsize" option.
+%%%     A read_file/3 client will just acquire filesize from the
+%%%     server by sending a zero "tsize".
+%%%     
+%%%   {max_tsize, MaxTsize}
+%%%
+%%%     MaxTsize = integer() | infinity
+%%%     
+%%%     Threshold for the maximal filesize in bytes. The transfer will
+%%%     be aborted if the limit is exceeded. It defaults to
+%%%     'infinity'.
+%%%
+%%%   {max_conn, MaxConn}
+%%%   
+%%%     MaxConn = integer() | infinity
+%%%     
+%%%     Threshold for the maximal number of active connections. The
+%%%     daemon will reject the setup of new connections if the limit
+%%%     is exceeded. It defaults to 'infinity'.
+%%%     
+%%%   {TftpKey, TftpVal}
+%%%
+%%%      TftpKey = string()
+%%%      TftpVal = string()
+%%%
+%%%      The name and value of a TFTP option.
+%%%      
+%%%   {reject, Feature}
+%%%   
+%%%      Feature = Mode | TftpKey
+%%%      Mode    = read | write
+%%%      TftpKey = string()
+%%%      
+%%%      Control which features that should be rejected.
+%%%      This is mostly useful for the server as it may restrict
+%%%      usage of certain TFTP options or read/write access.
+%%%
+%%%   {callback, {RegExp, Module, State}}
+%%%
+%%%    	 RegExp = string()
+%%%    	 Module = atom()
+%%%    	 State  = term()
+%%%    	 
+%%%      Registration of a callback module. When a file is to be
+%%%      transferred, its local filename will be matched to the
+%%%      regular expressions of the registered callbacks. The first
+%%%      matching callback will be used the during the transfer.The
+%%%      callback module must implement the 'tftp' behaviour.
+%%%
+%%%      On the server side the callback interaction starts with a
+%%%      call to open/5 with the registered initial callback
+%%%      state. open/5 is expected to open the (virtual) file. Then
+%%%      either the read/1 or write/2 functions are invoked
+%%%      repeatedly, once per transfererred block. At each function
+%%%      call the state returned from the previous call is
+%%%      obtained. When the last block has been encountered the read/1
+%%%      or write/2 functions is expected to close the (virtual)
+%%%      file.and return its last state. The abort/3 function is only
+%%%      used in error situations. prepare/5 is not used on the server
+%%%      side.
+%%%      
+%%%      On the client side the callback interaction is the same, but
+%%%      it starts and ends a bit differently. It starts with a call
+%%%      to prepare/5 with the same arguments as open/5
+%%%      takes. prepare/5 is expected to validate the TFTP options,
+%%%      suggested by the user and return the subset of them that it
+%%%      accepts. Then the options is sent to the server which will
+%%%      perform the same TFTP option negotiation procedure. The
+%%%      options that are accepted by the server is forwarded to the
+%%%      open/5 function on the client side. On the client side the
+%%%      open/5 function must accept all option as is or reject the
+%%%      transfer. Then the callback interaction follows the same
+%%%      pattern as described above for the server side. When the last
+%%%      block is encountered in read/1 or write/2 the returned stated
+%%%      is forwarded to the user and returned from read_file/3 or
+%%%      write_file/3.
+%%%-------------------------------------------------------------------
+
+-module(tftp).
+
+%%-------------------------------------------------------------------
+%% Interface
+%%-------------------------------------------------------------------
+
+%% Public functions
+-export([
+	 read_file/3,
+	 write_file/3,
+	 start/1,
+	 info/1,
+	 change_config/2,
+	 start/0,
+         stop/0
+	]).
+
+%% Application local functions
+-export([
+	 start_standalone/1,
+	 start_service/1,
+	 stop_service/1, 
+	 services/0,
+	 service_info/1
+	]).
+
+
+-type peer() :: {PeerType :: inet | inet6,
+		 PeerHost :: inet:ip_address(),
+		 PeerPort :: port()}.
+
+-type access() :: read | write.
+
+-type options() :: [{Key :: string(), Value :: string()}].
+
+-type error_code() :: undef | enoent | eacces | enospc |
+		      badop | eexist | baduser | badopt |
+		      integer().
+
+-callback prepare(Peer :: peer(),
+		  Access :: access(),
+		  Filename :: file:name(),
+		  Mode :: string(),
+		  SuggestedOptions :: options(),
+		  InitialState :: [] | [{root_dir, string()}]) ->
+    {ok, AcceptedOptions :: options(), NewState :: term()} |
+    {error, {Code :: error_code(), string()}}.
+
+-callback open(Peer :: peer(),
+	       Access :: access(),
+	       Filename :: file:name(),
+	       Mode :: string(),
+	       SuggestedOptions :: options(),
+	       State :: [] | [{root_dir, string()}] | term()) ->
+    {ok, AcceptedOptions :: options(), NewState :: term()} |
+    {error, {Code :: error_code(), string()}}.
+
+-callback read(State :: term()) -> {more, binary(), NewState :: term()} |
+				   {last, binary(), integer()} |
+				   {error, {Code :: error_code(), string()}}.
+
+-callback write(binary(), State :: term()) ->
+    {more, NewState :: term()} |
+    {last, FileSize :: integer()} |
+    {error, {Code :: error_code(), string()}}.
+
+-callback abort(Code :: error_code(), string(), State :: term()) -> 'ok'.
+
+-include("tftp.hrl").
+
+
+%%-------------------------------------------------------------------
+%% read_file(RemoteFilename, LocalFilename, Options) ->
+%%   {ok, LastCallbackState} | {error, Reason}
+%%
+%% RemoteFilename     = string()
+%% LocalFilename      = binary | string()
+%% Options            = [option()]
+%% LastCallbackState  = term()
+%% Reason             = term()
+%%
+%% Reads a (virtual) file from a TFTP server
+%%
+%% If LocalFilename is the atom 'binary', tftp_binary will be used as
+%% callback module. It will concatenate all transferred blocks and
+%% return them as one single binary in the CallbackState.
+%%
+%% When LocalFilename is a string, it will be matched to the
+%% registered callback modules and hopefully one of them will be
+%% selected. By default, tftp_file will be used as callback module. It
+%% will write each transferred block to the file named
+%% LocalFilename. The number of transferred bytes will be returned as
+%% LastCallbackState.
+%%-------------------------------------------------------------------
+
+read_file(RemoteFilename, LocalFilename, Options) ->
+    tftp_engine:client_start(read, RemoteFilename, LocalFilename, Options).
+    
+%%-------------------------------------------------------------------
+%% write(RemoteFilename, LocalFilename, Options) ->
+%%   {ok, LastCallbackState} | {error, Reason}
+%%
+%% RemoteFilename    = string()
+%% LocalFilename     = binary() | string()
+%% Options           = [option()]
+%% LastCallbackState = term()
+%% Reason            = term()
+%%
+%% Writes a (virtual) file to a TFTP server
+%% 
+%% If LocalFilename is a binary, tftp_binary will be used as callback
+%% module. The binary will be transferred block by block and the number
+%% of transferred bytes will be returned as LastCallbackState.
+%%
+%% When LocalFilename is a string, it will be matched to the
+%% registered callback modules and hopefully one of them will be
+%% selected. By default, tftp_file will be used as callback module. It
+%% will read the file named LocalFilename block by block. The number
+%% of transferred bytes will be returned as LastCallbackState.
+%%-------------------------------------------------------------------
+
+write_file(RemoteFilename, LocalFilename, Options) ->
+    tftp_engine:client_start(write, RemoteFilename, LocalFilename, Options).
+
+%%-------------------------------------------------------------------
+%% start(Options) -> {ok, Pid} | {error, Reason}
+%% 
+%% Options = [option()]
+%% Pid     = pid()
+%% Reason  = term()
+%%
+%% Starts a daemon process which listens for udp packets on a
+%% port. When it receives a request for read or write it spawns
+%% a temporary server process which handles the actual transfer
+%% of the (virtual) file.
+%%-------------------------------------------------------------------
+
+start(Options) ->
+    tftp_engine:daemon_start(Options).
+
+%%-------------------------------------------------------------------
+%% info(Pid) -> {ok, Options} | {error, Reason}
+%% 
+%% Options = [option()]
+%% Reason  = term()
+%%
+%% Returns info about a tftp daemon, server or client process
+%%-------------------------------------------------------------------
+
+info(Pid) ->
+    tftp_engine:info(Pid).
+
+%%-------------------------------------------------------------------
+%% change_config(Pid, Options) -> ok | {error, Reason}
+%% 
+%% Options = [option()]
+%% Reason  = term()
+%%
+%% Changes config for a tftp daemon, server or client process
+%% Must be used with care.
+%%-------------------------------------------------------------------
+
+change_config(Pid, Options) ->
+    tftp_engine:change_config(Pid, Options).
+
+%%-------------------------------------------------------------------
+%% start() -> ok | {error, Reason}
+%% 
+%% Reason = term()
+%%
+%% Start the application
+%%-------------------------------------------------------------------
+
+start() ->
+    application:start(tftp).
+
+%%-------------------------------------------------------------------
+%% stop() -> ok | {error, Reason}
+%% 
+%% Reason = term()
+%%
+%% Stop the application
+%%-------------------------------------------------------------------
+stop() ->
+    application:stop(tftp).
+
+%%-------------------------------------------------------------------
+%% Inets service behavior
+%%-------------------------------------------------------------------
+
+start_standalone(Options) ->
+    start(Options).
+
+start_service(Options) ->
+    tftp_sup:start_child(Options).
+
+stop_service(Pid) ->
+    tftp_sup:stop_child(Pid).
+
+services() ->
+    tftp_sup:which_children().
+
+service_info(Pid) ->
+    info(Pid).
+	     
+	     
+       
diff --git a/lib/tftp/src/tftp.hrl b/lib/tftp/src/tftp.hrl
new file mode 100644
index 0000000000..25543e0b9e
--- /dev/null
+++ b/lib/tftp/src/tftp.hrl
@@ -0,0 +1,69 @@
+%%
+%% %CopyrightBegin%
+%% 
+%% Copyright Ericsson AB 2005-2016. All Rights Reserved.
+%% 
+%% Licensed under the Apache License, Version 2.0 (the "License");
+%% you may not use this file except in compliance with the License.
+%% You may obtain a copy of the License at
+%%
+%%     http://www.apache.org/licenses/LICENSE-2.0
+%%
+%% Unless required by applicable law or agreed to in writing, software
+%% distributed under the License is distributed on an "AS IS" BASIS,
+%% WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+%% See the License for the specific language governing permissions and
+%% limitations under the License.
+%% 
+%% %CopyrightEnd%
+%%
+%%
+
+%%%-------------------------------------------------------------------
+%%% Defines
+%%%-------------------------------------------------------------------
+
+-define(TFTP_DEFAULT_PORT,  69).% Default server port
+
+-define(TFTP_OPCODE_RRQ,    1). % Read request
+-define(TFTP_OPCODE_WRQ,    2). % Write request
+-define(TFTP_OPCODE_DATA,   3). % Data
+-define(TFTP_OPCODE_ACK,    4). % Acknowledgement
+-define(TFTP_OPCODE_ERROR,  5). % Error
+-define(TFTP_OPCODE_OACK,   6). % Option acknowledgment
+
+-define(TFTP_ERROR_UNDEF,   0). % Not defined, see error message (if any)
+-define(TFTP_ERROR_ENOENT,  1). % File not found.
+-define(TFTP_ERROR_EACCES,  2). % Access violation.
+-define(TFTP_ERROR_ENOSPC,  3). % Disk full or allocation exceeded.
+-define(TFTP_ERROR_BADOP,   4). % Illegal TFTP operation.
+-define(TFTP_ERROR_BADBLK,  5). % Unknown transfer ID.
+-define(TFTP_ERROR_EEXIST,  6). % File already exists.
+-define(TFTP_ERROR_BADUSER, 7). % No such user.
+-define(TFTP_ERROR_BADOPT,  8). % Unrequested or illegal option.
+
+-record(tftp_msg_req,     {access, filename, mode, options, local_filename}).
+-record(tftp_msg_data,    {block_no, data}).
+-record(tftp_msg_ack,     {block_no}).
+-record(tftp_msg_error,   {code, text, details}).
+-record(tftp_msg_oack,    {options}).
+
+-record(config, {parent_pid   = self(),
+		 udp_socket,
+		 udp_options  = [binary, {reuseaddr, true}, {active, once}],
+		 udp_host     = "localhost",
+		 udp_port     = ?TFTP_DEFAULT_PORT,
+		 port_policy  = random,
+		 use_tsize    = false,
+		 max_tsize    = infinity, % Filesize
+		 max_conn     = infinity,
+		 rejected     = [],
+		 polite_ack   = false,
+		 debug_level  = none,
+		 timeout,
+		 user_options = [],
+		 callbacks    = [],
+		 logger       = tftp_logger,
+		 max_retries  = 5}).
+
+-record(callback, {regexp, internal, module, state, block_no, count}).
diff --git a/lib/tftp/src/tftp_app.erl b/lib/tftp/src/tftp_app.erl
new file mode 100644
index 0000000000..bbcd107e30
--- /dev/null
+++ b/lib/tftp/src/tftp_app.erl
@@ -0,0 +1,47 @@
+%%
+%% %CopyrightBegin%
+%% 
+%% Copyright Ericsson AB 2002-2018. All Rights Reserved.
+%% 
+%% Licensed under the Apache License, Version 2.0 (the "License");
+%% you may not use this file except in compliance with the License.
+%% You may obtain a copy of the License at
+%%
+%%     http://www.apache.org/licenses/LICENSE-2.0
+%%
+%% Unless required by applicable law or agreed to in writing, software
+%% distributed under the License is distributed on an "AS IS" BASIS,
+%% WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+%% See the License for the specific language governing permissions and
+%% limitations under the License.
+%% 
+%% %CopyrightEnd%
+%%
+%%
+
+%%%-------------------------------------------------------------------
+%% @doc ftp public API
+%% @end
+%%%-------------------------------------------------------------------
+
+-module(tftp_app).
+
+-behaviour(application).
+
+%% Application callbacks
+-export([start/2, stop/1]).
+
+%%====================================================================
+%% API
+%%====================================================================
+
+start(_StartType, _StartArgs) ->
+    tftp_sup:start_link([]).
+
+%%--------------------------------------------------------------------
+stop(_State) ->
+    ok.
+
+%%====================================================================
+%% Internal functions
+%%====================================================================
diff --git a/lib/tftp/src/tftp_binary.erl b/lib/tftp/src/tftp_binary.erl
new file mode 100644
index 0000000000..09adcfc41f
--- /dev/null
+++ b/lib/tftp/src/tftp_binary.erl
@@ -0,0 +1,239 @@
+%%
+%% %CopyrightBegin%
+%% 
+%% Copyright Ericsson AB 2005-2016. All Rights Reserved.
+%% 
+%% Licensed under the Apache License, Version 2.0 (the "License");
+%% you may not use this file except in compliance with the License.
+%% You may obtain a copy of the License at
+%%
+%%     http://www.apache.org/licenses/LICENSE-2.0
+%%
+%% Unless required by applicable law or agreed to in writing, software
+%% distributed under the License is distributed on an "AS IS" BASIS,
+%% WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+%% See the License for the specific language governing permissions and
+%% limitations under the License.
+%% 
+%% %CopyrightEnd%
+%%
+%%
+
+%%%-------------------------------------------------------------------
+%%% File    : tft_binary.erl
+%%% Author  : Hakan Mattsson <[email protected]>
+%%% Description : 
+%%%
+%%% Created : 24 May 2004 by Hakan Mattsson <[email protected]>
+%%%-------------------------------------------------------------------
+
+-module(tftp_binary).
+
+%%%-------------------------------------------------------------------
+%%% Interface
+%%%-------------------------------------------------------------------
+
+-behaviour(tftp).
+
+-export([prepare/6, open/6, read/1, write/2, abort/3]).
+
+-record(read_state,  {options, blksize, bin,  is_native_ascii, is_network_ascii, count}).
+-record(write_state, {options, blksize, list, is_native_ascii, is_network_ascii}).
+
+%%-------------------------------------------------------------------
+%% Prepare
+%%-------------------------------------------------------------------
+
+prepare(_Peer, Access, Filename, Mode, SuggestedOptions, Initial) when is_list(Initial) ->
+    %% Client side
+    IsNativeAscii = is_native_ascii(Initial),
+    case catch handle_options(Access, Filename, Mode, SuggestedOptions, IsNativeAscii) of
+	{ok, IsNetworkAscii, AcceptedOptions} when Access =:= read, is_binary(Filename) ->
+	    State = #read_state{options  	 = AcceptedOptions,
+				blksize  	 = lookup_blksize(AcceptedOptions),
+				bin      	 = Filename,
+				is_network_ascii = IsNetworkAscii,
+			        count            = size(Filename),
+				is_native_ascii  = IsNativeAscii},
+	    {ok, AcceptedOptions, State};
+	{ok, IsNetworkAscii, AcceptedOptions} when Access =:= write, Filename =:= binary ->
+	    State = #write_state{options  	  = AcceptedOptions,
+				 blksize  	  = lookup_blksize(AcceptedOptions),
+				 list     	  = [],
+				 is_network_ascii = IsNetworkAscii,
+				 is_native_ascii  = IsNativeAscii},
+	    {ok, AcceptedOptions, State};
+	{ok, _, _} ->
+	    {error, {undef, "Illegal callback usage. Mode and filename is incompatible."}};
+	{error, {Code, Text}} ->
+	    {error, {Code, Text}}
+    end;
+prepare(_Peer, _Access, _Bin, _Mode, _SuggestedOptions, _Initial) ->
+    {error, {undef, "Illegal callback options."}}.
+
+%%-------------------------------------------------------------------
+%% Open
+%%-------------------------------------------------------------------
+
+open(Peer, Access, Filename, Mode, SuggestedOptions, Initial) when is_list(Initial) ->
+    %% Server side
+    case prepare(Peer, Access, Filename, Mode, SuggestedOptions, Initial) of
+	{ok, AcceptedOptions, State} ->
+	    open(Peer, Access, Filename, Mode, AcceptedOptions, State);
+	{error, {Code, Text}} ->
+	    {error, {Code, Text}}
+    end;
+open(_Peer, Access, Filename, Mode, NegotiatedOptions, State) when is_record(State, read_state) ->
+    %% Both sides
+    case catch handle_options(Access, Filename, Mode, NegotiatedOptions, State#read_state.is_native_ascii) of
+	{ok, IsNetworkAscii, Options}
+	when Options =:= NegotiatedOptions,
+	     IsNetworkAscii =:= State#read_state.is_network_ascii ->
+	    {ok, NegotiatedOptions, State};
+	{error, {Code, Text}} ->
+	    {error, {Code, Text}}
+    end;
+open(_Peer, Access, Filename, Mode, NegotiatedOptions, State) when is_record(State, write_state) ->
+    %% Both sides
+    case catch handle_options(Access, Filename, Mode, NegotiatedOptions, State#write_state.is_native_ascii) of
+	{ok, IsNetworkAscii, Options}
+	when Options =:= NegotiatedOptions,
+	     IsNetworkAscii =:= State#write_state.is_network_ascii ->
+	    {ok, NegotiatedOptions, State};
+	{error, {Code, Text}} ->
+	    {error, {Code, Text}}
+    end;
+open(Peer, Access, Filename, Mode, NegotiatedOptions, State) -> 
+    %% Handle upgrade from old releases. Please, remove this clause in next release.
+    State2 = upgrade_state(State),
+    open(Peer, Access, Filename, Mode, NegotiatedOptions, State2).
+
+%%-------------------------------------------------------------------
+%% Read
+%%-------------------------------------------------------------------
+
+read(#read_state{bin = Bin} = State) when is_binary(Bin) ->
+    BlkSize = State#read_state.blksize,
+    if
+	size(Bin) >= BlkSize ->
+	    <<Block:BlkSize/binary, Bin2/binary>> = Bin,
+	    State2 = State#read_state{bin = Bin2},
+	    {more, Block, State2};
+	size(Bin) < BlkSize ->
+	    {last, Bin, State#read_state.count}
+    end;
+read(State) ->
+    %% Handle upgrade from old releases. Please, remove this clause in next release.
+    State2 = upgrade_state(State),
+    read(State2).
+
+%%-------------------------------------------------------------------
+%% Write
+%%-------------------------------------------------------------------
+
+write(Bin, #write_state{list = List} = State) when is_binary(Bin), is_list(List) ->
+    Size = size(Bin),
+    BlkSize = State#write_state.blksize,
+    if
+	Size =:= BlkSize ->
+	    {more, State#write_state{list = [Bin | List]}};
+	Size < BlkSize ->
+	    Bin2 = list_to_binary(lists:reverse([Bin | List])),
+	    {last, Bin2}
+    end;
+write(Bin, State) ->
+    %% Handle upgrade from old releases. Please, remove this clause in next release.
+    State2 = upgrade_state(State),
+    write(Bin, State2).
+
+%%-------------------------------------------------------------------
+%% Abort
+%%-------------------------------------------------------------------
+
+abort(_Code, _Text, #read_state{bin = Bin} = State) 
+  when is_record(State, read_state), is_binary(Bin) ->
+    ok;
+abort(_Code, _Text, #write_state{list = List} = State)
+  when is_record(State, write_state), is_list(List) ->
+    ok;
+abort(Code, Text, State) ->
+    %% Handle upgrade from old releases. Please, remove this clause in next release.
+    State2 = upgrade_state(State),
+    abort(Code, Text, State2).
+
+%%-------------------------------------------------------------------
+%% Process options
+%%-------------------------------------------------------------------
+
+handle_options(Access, Bin, Mode, Options, IsNativeAscii) ->
+    IsNetworkAscii = handle_mode(Mode, IsNativeAscii),
+    Options2 = do_handle_options(Access, Bin, Options),
+    {ok, IsNetworkAscii, Options2}.
+
+handle_mode(Mode, IsNativeAscii) ->
+    case Mode of
+	"netascii" when IsNativeAscii =:= true -> true;
+	"octet" -> false;
+	_ -> throw({error, {badop, "Illegal mode " ++ Mode}})
+    end.
+
+do_handle_options(Access, Bin, [{Key, Val} | T]) ->
+    case Key of
+	"tsize" ->
+	    case Access of
+		read when Val =:= "0", is_binary(Bin) ->
+		    Tsize = integer_to_list(size(Bin)),
+		    [{Key, Tsize} | do_handle_options(Access, Bin, T)];
+		_ ->
+		    handle_integer(Access, Bin, Key, Val, T, 0, infinity)
+	    end;
+	"blksize" ->
+	    handle_integer(Access, Bin, Key, Val, T, 8, 65464);
+	"timeout" ->
+	    handle_integer(Access, Bin, Key, Val, T, 1, 255);
+	_ ->
+	    do_handle_options(Access, Bin, T)
+    end;
+do_handle_options(_Access, _Bin, []) ->
+    [].
+
+
+handle_integer(Access, Bin, Key, Val, Options, Min, Max) ->
+    case catch list_to_integer(Val) of
+	{'EXIT', _} ->
+	    do_handle_options(Access, Bin, Options);
+	Int when Int >= Min, Int =< Max ->
+	    [{Key, Val} | do_handle_options(Access, Bin, Options)];
+	Int when Int >= Min, Max =:= infinity ->
+	    [{Key, Val} | do_handle_options(Access, Bin, Options)];
+	_Int ->
+	    throw({error, {badopt, "Illegal " ++ Key ++ " value " ++ Val}})
+    end.
+
+lookup_blksize(Options) ->
+    case lists:keysearch("blksize", 1, Options) of
+	{value, {_, Val}} ->
+	    list_to_integer(Val);
+	false ->
+	    512
+    end.
+
+is_native_ascii([]) ->
+    is_native_ascii();
+is_native_ascii([{native_ascii, Bool}]) ->
+    case Bool of
+	true  -> true;
+	false -> false
+    end.
+
+is_native_ascii() ->
+    case os:type() of
+	{win32, _} -> true;
+	_          -> false
+    end.
+    
+%% Handle upgrade from old releases. Please, remove this function in next release.
+upgrade_state({read_state,  Options, Blksize, Bin, IsNetworkAscii, Count}) ->
+    {read_state,  Options, Blksize, Bin, false, IsNetworkAscii, Count};
+upgrade_state({write_state, Options, Blksize, List, IsNetworkAscii}) ->
+    {write_state, Options, Blksize, List, false, IsNetworkAscii}.
diff --git a/lib/tftp/src/tftp_engine.erl b/lib/tftp/src/tftp_engine.erl
new file mode 100644
index 0000000000..fb2c9749e5
--- /dev/null
+++ b/lib/tftp/src/tftp_engine.erl
@@ -0,0 +1,1422 @@
+%%
+%% %CopyrightBegin%
+%% 
+%% Copyright Ericsson AB 2005-2016. All Rights Reserved.
+%% 
+%% Licensed under the Apache License, Version 2.0 (the "License");
+%% you may not use this file except in compliance with the License.
+%% You may obtain a copy of the License at
+%%
+%%     http://www.apache.org/licenses/LICENSE-2.0
+%%
+%% Unless required by applicable law or agreed to in writing, software
+%% distributed under the License is distributed on an "AS IS" BASIS,
+%% WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+%% See the License for the specific language governing permissions and
+%% limitations under the License.
+%% 
+%% %CopyrightEnd%
+%% 
+%%-------------------------------------------------------------------
+%% Protocol engine for trivial FTP
+%%-------------------------------------------------------------------
+
+-module(tftp_engine).
+
+%%%-------------------------------------------------------------------
+%%% Interface
+%%%-------------------------------------------------------------------
+
+%% application internal functions
+-export([
+         daemon_start/1,
+         daemon_loop/1,
+         daemon_loop/3,    %% Handle upgrade from old releases. Please, remove this function in next release.
+         client_start/4,
+         common_loop/6,
+         info/1,
+         change_config/2
+        ]).
+
+%% module internal
+-export([
+         daemon_init/1, 
+         server_init/2, 
+         client_init/2,
+         wait_for_msg/3,
+         callback/4
+        ]).
+
+%% sys callback functions
+-export([
+         system_continue/3,
+         system_terminate/4,
+         system_code_change/4
+        ]).
+
+-include("tftp.hrl").
+
+-type prep_status() :: 'error' | 'last' | 'more' | 'terminate'.
+
+-record(daemon_state, {config, n_servers, server_tab, file_tab}).
+-record(server_info, {pid, req, peer}).
+-record(file_info, {peer_req, pid}).
+-record(sys_misc, {module, function, arguments}).
+-record(error, {where, code, text, filename}).
+-record(prepared, {status :: prep_status() | 'undefined',
+                   result, block_no, next_data, prev_data}).
+-record(transfer_res, {status, decoded_msg, prepared}).
+-define(ERROR(Where, Code, Text, Filename),
+        #error{where = Where, code = Code, text = Text, filename = Filename}).
+
+%%%-------------------------------------------------------------------
+%%% Info
+%%%-------------------------------------------------------------------
+
+info(daemons) ->
+    Daemons = supervisor:which_children(tftp_sup),
+    [{Pid, info(Pid)} || {_, Pid, _, _} <- Daemons];
+info(servers) ->
+    [{Pid, info(Pid)} || {_, {ok, DeamonInfo}} <- info(daemons),
+                         {server, Pid}   <- DeamonInfo];
+info(ToPid) when is_pid(ToPid) ->
+    call(info, ToPid, timer:seconds(10)).
+
+change_config(daemons, Options) ->
+    Daemons = supervisor:which_children(tftp_sup),
+    [{Pid, change_config(Pid, Options)} || {_, Pid, _, _} <- Daemons];
+change_config(servers, Options) ->
+    [{Pid, change_config(Pid, Options)} || {_, {ok, DeamonInfo}} <- info(daemons),
+                                           {server, Pid}   <- DeamonInfo];
+change_config(ToPid, Options) when is_pid(ToPid) ->
+    BadKeys = [host, port, udp],
+    BadOptions = [{Key, Val} || {Key, Val} <- Options,
+                                BadKey <- BadKeys,
+                                Key =:= BadKey],
+    case BadOptions of
+        [] ->
+            call({change_config, Options}, ToPid, timer:seconds(10));
+        [{Key, Val} | _] ->
+            {error, {badarg, {Key, Val}}}
+    end.
+
+call(Req, ToPid, Timeout) when is_pid(ToPid) ->
+    Type = process,
+    Ref = erlang:monitor(Type, ToPid),
+    ToPid ! {Req, Ref, self()},
+    receive
+        {Reply, Ref, FromPid} when FromPid =:= ToPid ->
+            erlang:demonitor(Ref, [flush]),
+            Reply;
+        {'DOWN', Ref, Type, FromPid, _Reason} when FromPid =:= ToPid ->
+            {error, timeout}
+    after Timeout ->
+            {error, timeout}
+    end.
+
+reply(Reply, Ref, ToPid) ->
+    ToPid ! {Reply, Ref, self()}.
+
+%%%-------------------------------------------------------------------
+%%% Daemon
+%%%-------------------------------------------------------------------
+
+%% Returns {ok, Port}
+daemon_start(Options) when is_list(Options) ->
+    Config = tftp_lib:parse_config(Options),
+    proc_lib:start_link(?MODULE, daemon_init, [Config], infinity).
+
+daemon_init(Config) when is_record(Config, config), 
+                         is_pid(Config#config.parent_pid) ->
+    process_flag(trap_exit, true),
+    {Port, UdpOptions} = prepare_daemon_udp(Config),
+    case catch gen_udp:open(Port, UdpOptions) of
+        {ok, Socket} ->
+            {ok, ActualPort} = inet:port(Socket),
+            proc_lib:init_ack({ok, self()}),
+            Config2 = Config#config{udp_socket = Socket,
+                                    udp_port   = ActualPort},
+            print_debug_info(Config2, daemon, open, #tftp_msg_req{filename = ""}),
+            ServerTab = ets:new(tftp_daemon_servers, [{keypos, 2}]),
+            FileTab = ets:new(tftp_daemon_files, [{keypos, 2}]),
+            State = #daemon_state{config = Config2,
+                                  n_servers = 0,
+                                  server_tab = ServerTab,
+                                  file_tab = FileTab},
+            daemon_loop(State);
+        {error, Reason} ->
+            Text = lists:flatten(io_lib:format("UDP open ~p -> ~p", [UdpOptions, Reason])),
+            print_debug_info(Config, daemon, open, ?ERROR(open, undef, Text, "")),
+            exit({gen_udp_open, UdpOptions, Reason});
+        Reason ->
+            Text = lists:flatten(io_lib:format("UDP open ~p -> ~p", [UdpOptions, Reason])),
+            print_debug_info(Config, daemon, open, ?ERROR(open, undef, Text, "")),
+            exit({gen_udp_open, UdpOptions, Reason})
+    end.
+
+prepare_daemon_udp(#config{udp_port = Port, udp_options = UdpOptions} = Config) ->
+    case lists:keymember(fd, 1, UdpOptions) of
+        true ->
+            %% Use explicit fd
+            {Port, UdpOptions};
+        false ->
+            %% Use fd from setuid_socket_wrap, such as -tftpd_69
+            InitArg = list_to_atom("tftpd_" ++ integer_to_list(Port)),
+            case init:get_argument(InitArg) of
+                {ok, [[FdStr]] = Badarg} when is_list(FdStr) ->
+                    case catch list_to_integer(FdStr) of
+                        Fd when is_integer(Fd) ->
+                            {0, [{fd, Fd} | lists:keydelete(ip, 1, UdpOptions)]};
+                        {'EXIT', _} ->
+                            Text = lists:flatten(io_lib:format("Illegal prebound fd ~p: ~p", [InitArg, Badarg])),
+                            print_debug_info(Config, daemon, open, ?ERROR(open, undef, Text, "")),
+                            exit({badarg, {prebound_fd, InitArg, Badarg}})
+                    end;
+                {ok, Badarg} ->
+                    Text = lists:flatten(io_lib:format("Illegal prebound fd ~p: ~p", [InitArg, Badarg])),
+                    print_debug_info(Config, daemon, open, ?ERROR(open, undef, Text, "")),
+                    exit({badarg, {prebound_fd, InitArg, Badarg}});
+                error ->
+                    {Port, UdpOptions}
+            end
+    end.
+
+daemon_loop(DaemonConfig, N, Servers) when is_list(Servers) ->
+    %% Handle upgrade from old releases. Please, remove this function in next release.
+    ServerTab = ets:new(tftp_daemon_servers, [{keypos, 2}]),
+    FileTab = ets:new(tftp_daemon_files, [{keypos, 2}]),
+    State = #daemon_state{config = DaemonConfig,
+                          n_servers = N,
+                          server_tab = ServerTab,
+                          file_tab = FileTab},
+    Req = #tftp_msg_req{filename = dummy},
+    [ets:insert(ServerTab, #server_info{pid = Pid, req = Req, peer = dummy}) || Pid <- Servers],
+    daemon_loop(State).
+
+daemon_loop(#daemon_state{config = DaemonConfig,
+                          n_servers = N,
+                          server_tab = ServerTab,
+                          file_tab = FileTab} = State) when is_record(DaemonConfig, config) ->
+    %% info_msg(DaemonConfig, "=====> TFTP: Daemon #~p\n", [N]), %% XXX
+    receive
+        {info, Ref, FromPid} when is_pid(FromPid) ->
+            Fun = fun(#server_info{pid = Pid}, Acc) -> [{server, Pid} | Acc] end,
+            ServerInfo = ets:foldl(Fun, [], ServerTab),
+            Info = internal_info(DaemonConfig, daemon) ++ [{n_conn, N}] ++ ServerInfo,
+            reply({ok, Info}, Ref, FromPid),
+            ?MODULE:daemon_loop(State);
+        {{change_config, Options}, Ref, FromPid} when is_pid(FromPid) ->
+            case catch tftp_lib:parse_config(Options, DaemonConfig) of
+                {'EXIT', Reason} ->
+                    reply({error, Reason}, Ref, FromPid),
+                    ?MODULE:daemon_loop(State);
+                DaemonConfig2 when is_record(DaemonConfig2, config) ->
+                    reply(ok, Ref, FromPid),
+                    ?MODULE:daemon_loop(State#daemon_state{config = DaemonConfig2})
+            end;
+        {udp, Socket, RemoteHost, RemotePort, Bin} when is_binary(Bin) ->
+            inet:setopts(Socket, [{active, once}]),
+            ServerConfig = DaemonConfig#config{parent_pid = self(),
+                                               udp_host   = RemoteHost,
+                                               udp_port   = RemotePort},
+            Msg = (catch tftp_lib:decode_msg(Bin)),
+            print_debug_info(ServerConfig, daemon, recv, Msg),
+            case Msg of
+                Req when is_record(Req, tftp_msg_req), 
+                N =< DaemonConfig#config.max_conn ->
+                    Peer = peer_info(ServerConfig),
+                    PeerReq = {Peer, Req},
+                    PeerInfo = lists:flatten(io_lib:format("~p", [Peer])),
+                    case ets:lookup(FileTab, PeerReq) of
+                        [] ->
+                            Args = [ServerConfig, Req],
+                            Pid = proc_lib:spawn_link(?MODULE, server_init, Args),
+                            ets:insert(ServerTab, #server_info{pid = Pid, req = Req, peer = Peer}),
+                            ets:insert(FileTab, #file_info{peer_req = PeerReq, pid = Pid}),
+                            ?MODULE:daemon_loop(State#daemon_state{n_servers = N + 1});
+                        [#file_info{pid = Pid}] ->
+                            %% Yet another request of the file from same peer
+                            warning_msg(DaemonConfig, "~p Reuse connection for ~s\n\t~p\n",
+                                        [Pid, PeerInfo, Req#tftp_msg_req.filename]),
+                            ?MODULE:daemon_loop(State)
+                    end;
+                Req when is_record(Req, tftp_msg_req) ->
+                    Reply = #tftp_msg_error{code = enospc, text = "Too many connections"},
+                    Peer = peer_info(ServerConfig),
+                    PeerInfo = lists:flatten(io_lib:format("~p", [Peer])),
+                    warning_msg(DaemonConfig, 
+				"Daemon has too many connections (~p)."
+				"\n\tRejecting request from ~s\n",
+				[N, PeerInfo]),
+                    send_msg(ServerConfig, daemon, Reply),
+                    ?MODULE:daemon_loop(State);
+                {'EXIT', Reply} when is_record(Reply, tftp_msg_error) ->
+                    send_msg(ServerConfig, daemon, Reply),
+                    ?MODULE:daemon_loop(State);
+                Req  ->
+                    Reply = #tftp_msg_error{code = badop,
+                                            text = "Illegal TFTP operation"},
+                    warning_msg(DaemonConfig, "Daemon received: ~p.\n\tfrom ~p:~p", 
+                                [Req, RemoteHost, RemotePort]),
+                    send_msg(ServerConfig, daemon, Reply),
+                    ?MODULE:daemon_loop(State)
+            end;
+        {system, From, Msg} ->
+            Misc = #sys_misc{module = ?MODULE, function = daemon_loop, arguments = [State]},
+            sys:handle_system_msg(Msg, From, DaemonConfig#config.parent_pid, ?MODULE, [], Misc);
+        {'EXIT', Pid, Reason} when DaemonConfig#config.parent_pid =:= Pid ->
+            close_port(DaemonConfig, daemon, #tftp_msg_req{filename = ""}),
+            exit(Reason);
+        {'EXIT', Pid, _Reason} = Info ->
+            case ets:lookup(ServerTab, Pid) of
+                [] ->
+                    warning_msg(DaemonConfig, "Daemon received: ~p", [Info]),
+                    ?MODULE:daemon_loop(State);
+                [#server_info{req = Req, peer = Peer}] ->
+                    PeerReq = {Peer, Req},
+                    ets:delete(FileTab, PeerReq),
+                    ets:delete(ServerTab, Pid),
+                    ?MODULE:daemon_loop(State#daemon_state{n_servers = N - 1})
+            end;
+        Info ->
+            warning_msg(DaemonConfig, "Daemon received: ~p", [Info]),
+            ?MODULE:daemon_loop(State)
+    end;
+daemon_loop(#daemon_state{config = Config} = State) ->
+    %% Handle upgrade from old releases. Please, remove this clause in next release.
+    Config2 = upgrade_config(Config),
+    daemon_loop(State#daemon_state{config = Config2}).
+
+upgrade_config({config, ParentPid, UdpSocket, UdpOptions, UdpHost, UdpPort, PortPolicy,
+                UseTsize, MaxTsize, MaxConn, Rejected, PoliteAck, DebugLevel,
+                Timeout, UserOptions, Callbacks}) ->
+    Callbacks2  = tftp_lib:add_default_callbacks(Callbacks),
+    Logger = tftp_logger,
+    MaxRetries = 5,
+    {config, ParentPid, UdpSocket, UdpOptions, UdpHost, UdpPort, PortPolicy,
+     UseTsize, MaxTsize, MaxConn, Rejected, PoliteAck, DebugLevel,
+     Timeout, UserOptions, Callbacks2, Logger, MaxRetries}.
+
+%%%-------------------------------------------------------------------
+%%% Server
+%%%-------------------------------------------------------------------
+
+server_init(Config, Req) when is_record(Config, config),
+                              is_pid(Config#config.parent_pid),
+                              is_record(Req, tftp_msg_req) ->
+    process_flag(trap_exit, true),
+    %% Config = 
+    %%     case os:getenv("TFTPDEBUG") of
+    %%         false ->
+    %%             Config0;
+    %%         DebugLevel ->
+    %%             Config0#config{debug_level = list_to_atom(DebugLevel)}
+    %%     end,
+    SuggestedOptions = Req#tftp_msg_req.options,
+    UdpOptions = Config#config.udp_options,
+    UdpOptions2 = lists:keydelete(fd, 1, UdpOptions),
+    Config1 = Config#config{udp_options = UdpOptions2},
+    Config2 = tftp_lib:parse_config(SuggestedOptions, Config1),
+    SuggestedOptions2 = Config2#config.user_options,
+    Req2 = Req#tftp_msg_req{options = SuggestedOptions2},
+    case open_free_port(Config2, server, Req2) of
+        {ok, Config3} ->
+            Filename = Req#tftp_msg_req.filename,
+            case match_callback(Filename, Config3#config.callbacks) of
+                {ok, Callback} ->
+                    print_debug_info(Config3, server, match, Callback),
+                    case pre_verify_options(Config3, Req2) of
+                        ok ->
+                            case callback({open, server_open}, Config3, Callback, Req2) of
+                                {Callback2, {ok, AcceptedOptions}} ->
+                                    {LocalAccess,  _} = local_file_access(Req2),
+                                    OptText = "Internal error. Not allowed to add new options.",
+                                    case post_verify_options(Config3, Req2, AcceptedOptions, OptText) of
+                                        {ok, Config4, Req3} when AcceptedOptions =/= [] ->
+                                            Reply = #tftp_msg_oack{options = AcceptedOptions},
+                                            BlockNo =
+                                                case LocalAccess of
+                                                    read  -> 0;
+                                                    write -> 1
+                                                end,
+                                            {Config5, Callback3, TransferRes} = 
+                                                transfer(Config4, Callback2, Req3, Reply, LocalAccess, BlockNo, #prepared{}),
+                                            common_loop(Config5, Callback3, Req3, TransferRes, LocalAccess, BlockNo);
+                                        {ok, Config4, Req3} when LocalAccess =:= write ->
+                                            BlockNo = 0,
+                                            common_ack(Config4, Callback2, Req3, LocalAccess, BlockNo, #prepared{});
+                                        {ok, Config4, Req3} when LocalAccess =:= read ->
+                                            BlockNo = 0,
+                                            common_read(Config4, Callback2, Req3, LocalAccess, BlockNo, BlockNo, #prepared{});
+                                        {error, {Code, Text}} ->
+                                            {undefined, Error} =
+                                                callback({abort, {Code, Text}}, Config3, Callback2, Req2),
+                                            send_msg(Config3, Req, Error),
+                                            terminate(Config3, Req2, ?ERROR(post_verify_options, Code, Text, Req2#tftp_msg_req.filename))
+                                    end;
+                                {undefined, #tftp_msg_error{code = Code, text = Text} = Error} ->
+                                    send_msg(Config3, Req, Error),
+                                    terminate(Config3, Req, ?ERROR(server_open, Code, Text, Req2#tftp_msg_req.filename))
+                            end;
+                        {error, {Code, Text}} ->
+                            {undefined, Error} =
+                                callback({abort, {Code, Text}}, Config2, Callback, Req2),
+                            send_msg(Config2, Req, Error),
+                            terminate(Config2, Req2, ?ERROR(pre_verify_options, Code, Text, Req2#tftp_msg_req.filename))
+                    end;
+                {error, #tftp_msg_error{code = Code, text = Text} = Error} ->
+                    send_msg(Config3, Req, Error),
+                    terminate(Config3, Req, ?ERROR(match_callback, Code, Text, Req2#tftp_msg_req.filename))
+            end;
+        #error{} = Error ->
+            terminate(Config2, Req, Error)
+    end;
+server_init(Config, Req) when is_record(Req, tftp_msg_req) ->
+    Config2 = upgrade_config(Config),
+    server_init(Config2, Req).
+
+%%%-------------------------------------------------------------------
+%%% Client
+%%%-------------------------------------------------------------------
+
+%% LocalFilename = filename() | 'binary' | binary()
+%% Returns {ok, LastCallbackState} | {error, Reason}
+client_start(Access, RemoteFilename, LocalFilename, Options) ->
+    Config = tftp_lib:parse_config(Options),
+    Config2 = Config#config{parent_pid      = self(),
+                            udp_socket      = undefined},
+    Req = #tftp_msg_req{access         = Access, 
+                        filename       = RemoteFilename, 
+                        mode           = lookup_mode(Config2#config.user_options),
+                        options        = Config2#config.user_options,
+                        local_filename = LocalFilename},
+    Args = [Config2, Req],
+    case proc_lib:start_link(?MODULE, client_init, Args, infinity) of
+        {ok, LastCallbackState} ->
+            {ok, LastCallbackState};
+        {error, Error} ->
+            {error, Error}
+    end.
+
+client_init(Config, Req) when is_record(Config, config),
+                              is_pid(Config#config.parent_pid),
+                              is_record(Req, tftp_msg_req) ->
+    process_flag(trap_exit, true),
+    %% Config = 
+    %%  case os:getenv("TFTPDEBUG") of
+    %%      false ->
+    %%          Config0;
+    %%      "none" ->
+    %%          Config0;
+    %%      DebugLevel ->
+    %%          info_msg(Config, "TFTPDEBUG: ~s\n", [DebugLevel]),
+    %%          Config0#config{debug_level = list_to_atom(DebugLevel)}
+    %%  end,
+    case open_free_port(Config, client, Req) of
+        {ok, Config2} ->
+            Req2 =
+                case Config2#config.use_tsize of
+                    true ->
+                        SuggestedOptions = Req#tftp_msg_req.options,
+                        SuggestedOptions2 = tftp_lib:replace_val("tsize", "0", SuggestedOptions),
+                        Req#tftp_msg_req{options = SuggestedOptions2};
+                    false ->
+                        Req
+                end,
+            LocalFilename = Req2#tftp_msg_req.local_filename,
+            case match_callback(LocalFilename, Config2#config.callbacks) of
+                {ok, Callback} ->
+                    print_debug_info(Config2, client, match, Callback),
+                    client_prepare(Config2, Callback, Req2);                
+                {error, #tftp_msg_error{code = Code, text = Text}} ->
+                    terminate(Config, Req, ?ERROR(match, Code, Text, Req#tftp_msg_req.filename))
+            end;
+        #error{} = Error ->
+            terminate(Config, Req, Error)
+    end.
+
+client_prepare(Config, Callback, Req) when is_record(Req, tftp_msg_req) ->
+    case pre_verify_options(Config, Req) of
+        ok ->
+            case callback({open, client_prepare}, Config, Callback, Req) of
+                {Callback2, {ok, AcceptedOptions}} ->
+                    OptText = "Internal error. Not allowed to add new options.",
+                    case post_verify_options(Config, Req, AcceptedOptions, OptText) of
+                        {ok, Config2, Req2} ->
+                            {LocalAccess, _} = local_file_access(Req2),
+                            BlockNo = 0,
+                            {Config3, Callback3, TransferRes} =
+                                transfer(Config2, Callback2, Req2, Req2, LocalAccess, BlockNo, #prepared{}),
+                            client_open(Config3, Callback3, Req2, BlockNo, TransferRes);
+                        {error, {Code, Text}} ->
+                            callback({abort, {Code, Text}}, Config, Callback2, Req),
+                            terminate(Config, Req, ?ERROR(post_verify_options, Code, Text, Req#tftp_msg_req.filename))
+                    end;
+                {undefined, #tftp_msg_error{code = Code, text = Text}} ->
+                    terminate(Config, Req, ?ERROR(client_prepare, Code, Text, Req#tftp_msg_req.filename))
+            end;
+        {error, {Code, Text}} ->
+            callback({abort, {Code, Text}}, Config, Callback, Req),
+            terminate(Config, Req, ?ERROR(pre_verify_options, Code, Text, Req#tftp_msg_req.filename))
+    end.
+
+client_open(Config, Callback, Req, BlockNo, #transfer_res{status = Status, decoded_msg = DecodedMsg, prepared = Prepared}) ->
+    {LocalAccess, _} = local_file_access(Req),
+    case Status of
+        ok when is_record(Prepared, prepared) ->
+            case DecodedMsg of
+                Msg when is_record(Msg, tftp_msg_oack) ->
+                    ServerOptions = Msg#tftp_msg_oack.options,
+                    OptText = "Protocol violation. Server is not allowed new options",
+                    case post_verify_options(Config, Req, ServerOptions, OptText) of
+                        {ok, Config2, Req2} ->              
+                            {Config3, Callback2, Req3} =
+                                do_client_open(Config2, Callback, Req2),
+                            case LocalAccess of
+                                read ->
+                                    common_read(Config3, Callback2, Req3, LocalAccess, BlockNo, BlockNo, Prepared);
+                                write ->
+                                    common_ack(Config3, Callback2, Req3, LocalAccess, BlockNo, Prepared)
+                            end;
+                        {error, {Code, Text}} ->
+                            {undefined, Error} =
+                                callback({abort, {Code, Text}}, Config, Callback, Req),
+                            send_msg(Config, Req, Error),
+                            terminate(Config, Req, ?ERROR(verify_server_options, Code, Text, Req#tftp_msg_req.filename))
+                    end;
+                #tftp_msg_ack{block_no = ActualBlockNo} when LocalAccess =:= read ->
+                    Req2 = Req#tftp_msg_req{options = []},
+                    {Config2, Callback2, Req2} = do_client_open(Config, Callback, Req2),
+                    ExpectedBlockNo = 0,
+                    common_read(Config2, Callback2, Req2, LocalAccess, ExpectedBlockNo, ActualBlockNo, Prepared);
+                #tftp_msg_data{block_no = ActualBlockNo, data = Data} when LocalAccess =:= write ->
+                    Req2 = Req#tftp_msg_req{options = []},
+                    {Config2, Callback2, Req2} = do_client_open(Config, Callback, Req2),
+                    ExpectedBlockNo = 1,
+                    common_write(Config2, Callback2, Req2, LocalAccess, ExpectedBlockNo, ActualBlockNo, Data, Prepared);
+                %% #tftp_msg_error{code = Code, text = Text} when Req#tftp_msg_req.options =/= [] ->
+                %%     %% Retry without options
+                %%     callback({abort, {Code, Text}}, Config, Callback, Req),
+                %%     Req2 = Req#tftp_msg_req{options = []},
+                %%     client_prepare(Config, Callback, Req2);
+                #tftp_msg_error{code = Code, text = Text} ->
+                    callback({abort, {Code, Text}}, Config, Callback, Req),
+                    terminate(Config, Req, ?ERROR(client_open, Code, Text, Req#tftp_msg_req.filename));
+                {'EXIT', #tftp_msg_error{code = Code, text = Text}} ->
+                    callback({abort, {Code, Text}}, Config, Callback, Req),
+                    terminate(Config, Req, ?ERROR(client_open, Code, Text, Req#tftp_msg_req.filename));
+                Msg when is_tuple(Msg) ->
+                    Code = badop,
+                    Text = "Illegal TFTP operation",
+                    {undefined, Error} =
+                        callback({abort, {Code, Text}}, Config, Callback, Req),
+                    send_msg(Config, Req, Error),
+                    Text2 = lists:flatten([Text, ". ", io_lib:format("~p", [element(1, Msg)])]),
+                    terminate(Config, Req, ?ERROR(client_open, Code, Text2, Req#tftp_msg_req.filename))
+            end;
+        error when is_record(Prepared, tftp_msg_error) ->
+            #tftp_msg_error{code = Code, text = Text} = Prepared,
+            callback({abort, {Code, Text}}, Config, Callback, Req),
+            terminate(Config, Req, ?ERROR(client_open, Code, Text, Req#tftp_msg_req.filename))
+    end.
+
+do_client_open(Config, Callback, Req) ->
+    case callback({open, client_open}, Config, Callback, Req) of
+        {Callback2, {ok, FinalOptions}} ->
+            OptText = "Internal error. Not allowed to change options.",
+            case post_verify_options(Config, Req, FinalOptions, OptText) of
+                {ok, Config2, Req2} ->
+                    {Config2, Callback2, Req2};
+                {error, {Code, Text}} ->
+                    {undefined, Error} =
+                        callback({abort, {Code, Text}}, Config, Callback2, Req),
+                    send_msg(Config, Req, Error),
+                    terminate(Config, Req, ?ERROR(post_verify_options, Code, Text, Req#tftp_msg_req.filename))
+            end;
+        {undefined, #tftp_msg_error{code = Code, text = Text} = Error} ->
+            send_msg(Config, Req, Error),
+            terminate(Config, Req, ?ERROR(client_open, Code, Text, Req#tftp_msg_req.filename))
+    end.
+
+%%%-------------------------------------------------------------------
+%%% Common loop for both client and server
+%%%-------------------------------------------------------------------
+
+common_loop(Config, Callback, Req, #transfer_res{status = Status, decoded_msg = DecodedMsg, prepared = Prepared}, LocalAccess, ExpectedBlockNo) 
+  when is_record(Config, config)->
+    %%    Config =
+    %%  case os:getenv("TFTPMAX") of
+    %%      false -> 
+    %%          Config0;
+    %%      MaxBlockNoStr when Config0#config.debug_level =/= none ->
+    %%          case list_to_integer(MaxBlockNoStr) of
+    %%              MaxBlockNo when ExpectedBlockNo > MaxBlockNo ->
+    %%                  info_msg(Config, "TFTPMAX: ~p\n", [MaxBlockNo]),
+    %%                  info_msg(Config, "TFTPDEBUG: none\n", []),
+    %%                  Config0#config{debug_level = none};
+    %%              _ ->
+    %%                  Config0
+    %%          end;
+    %%      _MaxBlockNoStr ->
+    %%          Config0 
+    %%  end,
+    case Status of
+        ok when is_record(Prepared, prepared) ->
+            case DecodedMsg of
+                #tftp_msg_ack{block_no = ActualBlockNo} when LocalAccess =:= read ->
+                    common_read(Config, Callback, Req, LocalAccess, ExpectedBlockNo, ActualBlockNo, Prepared);
+                #tftp_msg_data{block_no = ActualBlockNo, data = Data} when LocalAccess =:= write ->
+                    common_write(Config, Callback, Req, LocalAccess, ExpectedBlockNo, ActualBlockNo, Data, Prepared);
+                #tftp_msg_error{code = Code, text = Text} ->
+                    callback({abort, {Code, Text}}, Config, Callback, Req),
+                    terminate(Config, Req, ?ERROR(common_loop, Code, Text, Req#tftp_msg_req.filename));
+                {'EXIT', #tftp_msg_error{code = Code, text = Text} = Error} ->
+                    callback({abort, {Code, Text}}, Config, Callback, Req),
+                    send_msg(Config, Req, Error),
+                    terminate(Config, Req, ?ERROR(common_loop, Code, Text, Req#tftp_msg_req.filename));
+                Msg when is_tuple(Msg) ->
+                    Code = badop,
+                    Text = "Illegal TFTP operation",
+                    {undefined, Error} =
+                        callback({abort, {Code, Text}}, Config, Callback, Req),
+                    send_msg(Config, Req, Error),
+                    Text2 = lists:flatten([Text, ". ", io_lib:format("~p", [element(1, Msg)])]),
+                    terminate(Config, Req, ?ERROR(common_loop, Code, Text2, Req#tftp_msg_req.filename))
+            end;
+        error when is_record(Prepared, tftp_msg_error) ->
+            #tftp_msg_error{code = Code, text = Text} = Prepared,
+            send_msg(Config, Req, Prepared),
+            terminate(Config, Req, ?ERROR(transfer, Code, Text, Req#tftp_msg_req.filename))
+    end;
+common_loop(Config, Callback, Req, TransferRes, LocalAccess, ExpectedBlockNo) ->
+    %% Handle upgrade from old releases. Please, remove this clause in next release.
+    Config2 = upgrade_config(Config),
+    common_loop(Config2, Callback, Req, TransferRes, LocalAccess, ExpectedBlockNo).
+
+-spec common_read(#config{}, #callback{}, _, 'read', _, _, #prepared{}) -> no_return().
+
+common_read(Config, _, Req, _, _, _, #prepared{status = terminate, result = Result}) ->
+    terminate(Config, Req, {ok, Result});
+common_read(Config, Callback, Req, LocalAccess, ExpectedBlockNo, ActualBlockNo, Prepared)
+  when ActualBlockNo =:= ExpectedBlockNo, is_record(Prepared, prepared) ->
+    case early_read(Config, Callback, Req, LocalAccess, ActualBlockNo, Prepared) of
+        {Callback2,  #prepared{status = more, next_data = Data} = Prepared2} when is_binary(Data) ->
+            Prepared3 = Prepared2#prepared{prev_data = Data, next_data = undefined},
+            do_common_read(Config, Callback2, Req, LocalAccess, ActualBlockNo, Data, Prepared3);
+        {undefined, #prepared{status = last, next_data = Data} = Prepared2} when is_binary(Data) ->
+            Prepared3 = Prepared2#prepared{status = terminate},
+            do_common_read(Config, undefined, Req, LocalAccess, ActualBlockNo, Data, Prepared3);
+        {undefined, #prepared{status = error, result = Error}} ->
+            #tftp_msg_error{code = Code, text = Text} = Error,
+            send_msg(Config, Req, Error),
+            terminate(Config, Req, ?ERROR(read, Code, Text, Req#tftp_msg_req.filename))
+    end;
+common_read(Config, Callback, Req, LocalAccess, ExpectedBlockNo, ActualBlockNo, Prepared) 
+  when ActualBlockNo =:= (ExpectedBlockNo - 1), is_record(Prepared, prepared) ->
+    case Prepared of
+        #prepared{status = more, prev_data = Data} when is_binary(Data) ->
+            do_common_read(Config, Callback, Req, LocalAccess, ActualBlockNo, Data, Prepared);
+        #prepared{status = last, prev_data = Data} when is_binary(Data) ->
+            do_common_read(Config, Callback, Req, LocalAccess, ActualBlockNo, Data, Prepared);
+        #prepared{status = error, result = Error} ->
+            #tftp_msg_error{code = Code, text = Text} = Error,
+            send_msg(Config, Req, Error),
+            terminate(Config, Req, ?ERROR(read, Code, Text, Req#tftp_msg_req.filename))
+    end;
+common_read(Config, Callback, Req, LocalAccess, ExpectedBlockNo, ActualBlockNo, Prepared) 
+  when ActualBlockNo =< ExpectedBlockNo, is_record(Prepared, prepared) ->
+    %% error_logger:error_msg("TFTP READ ~s: Expected block ~p but got block ~p - IGNORED\n",
+    %%                     [Req#tftp_msg_req.filename, ExpectedBlockNo, ActualBlockNo]),
+    case Prepared of
+        #prepared{status = more, prev_data = Data} when is_binary(Data) ->
+            Reply = #tftp_msg_data{block_no = ExpectedBlockNo, data = Data},
+            {Config2, Callback2, TransferRes} =
+                wait_for_msg_and_handle_timeout(Config, Callback, Req, Reply, LocalAccess, ExpectedBlockNo, Prepared),
+            ?MODULE:common_loop(Config2, Callback2, Req, TransferRes, LocalAccess, ExpectedBlockNo);
+        #prepared{status = last, prev_data = Data} when is_binary(Data) ->
+            Reply = #tftp_msg_data{block_no = ExpectedBlockNo, data = Data},
+            {Config2, Callback2, TransferRes} =
+                wait_for_msg_and_handle_timeout(Config, Callback, Req, Reply, LocalAccess, ExpectedBlockNo, Prepared),
+            ?MODULE:common_loop(Config2, Callback2, Req, TransferRes, LocalAccess, ExpectedBlockNo);
+        #prepared{status = error, result = Error} ->
+            #tftp_msg_error{code = Code, text = Text} = Error,
+            send_msg(Config, Req, Error),
+            terminate(Config, Req, ?ERROR(read, Code, Text, Req#tftp_msg_req.filename))
+    end;
+common_read(Config, Callback, Req, _LocalAccess, ExpectedBlockNo, ActualBlockNo, Prepared)
+  when is_record(Prepared, prepared) ->
+    Code = badblk,
+    Text = "Unknown transfer ID = " ++ 
+        integer_to_list(ActualBlockNo) ++ " (" ++ integer_to_list(ExpectedBlockNo) ++ ")", 
+    {undefined, Error} =
+        callback({abort, {Code, Text}}, Config, Callback, Req),
+    send_msg(Config, Req, Error),
+    terminate(Config, Req, ?ERROR(read, Code, Text, Req#tftp_msg_req.filename)).
+
+-spec do_common_read(#config{}, #callback{} | undefined, _, 'read', integer(), binary(), #prepared{}) -> no_return().
+
+do_common_read(Config, Callback, Req, LocalAccess, BlockNo, Data, Prepared)
+  when is_binary(Data), is_record(Prepared, prepared) ->
+    NextBlockNo = (BlockNo + 1) rem 65536,
+    Reply = #tftp_msg_data{block_no = NextBlockNo, data = Data},
+    {Config2, Callback2, TransferRes} =
+        transfer(Config, Callback, Req, Reply, LocalAccess, NextBlockNo, Prepared),
+    ?MODULE:common_loop(Config2, Callback2, Req, TransferRes, LocalAccess, NextBlockNo).
+
+-spec common_write(#config{}, #callback{}, _, 'write', integer(), integer(), _, #prepared{}) -> no_return().
+
+common_write(Config, _, Req, _, _, _, _, #prepared{status = terminate, result = Result}) ->
+    terminate(Config, Req, {ok, Result});
+common_write(Config, Callback, Req, LocalAccess, ExpectedBlockNo, ActualBlockNo, Data, Prepared)
+  when ActualBlockNo =:= ExpectedBlockNo, is_binary(Data), is_record(Prepared, prepared) ->
+    case callback({write, Data}, Config, Callback, Req) of
+        {Callback2, #prepared{status = more} = Prepared2} ->
+            common_ack(Config, Callback2, Req, LocalAccess, ActualBlockNo, Prepared2);
+        {undefined, #prepared{status = last, result = Result} = Prepared2} ->
+            Config2 = pre_terminate(Config, Req, {ok, Result}),
+            Prepared3 = Prepared2#prepared{status = terminate},
+            common_ack(Config2, undefined, Req, LocalAccess, ActualBlockNo, Prepared3);
+        {undefined, #prepared{status = error, result = Error}} ->
+            #tftp_msg_error{code = Code, text = Text} = Error,
+            send_msg(Config, Req, Error),
+            terminate(Config, Req, ?ERROR(write, Code, Text, Req#tftp_msg_req.filename))
+    end;
+common_write(Config, Callback, Req, LocalAccess, ExpectedBlockNo, ActualBlockNo, Data, Prepared)
+  when ActualBlockNo =:= (ExpectedBlockNo - 1), is_binary(Data), is_record(Prepared, prepared) ->
+    common_ack(Config, Callback, Req, LocalAccess, ExpectedBlockNo - 1, Prepared);
+common_write(Config, Callback, Req, LocalAccess, ExpectedBlockNo, ActualBlockNo, Data, Prepared)
+  when ActualBlockNo =< ExpectedBlockNo, is_binary(Data), is_record(Prepared, prepared) ->
+    %% error_logger:error_msg("TFTP WRITE ~s: Expected block ~p but got block ~p - IGNORED\n",
+    %% [Req#tftp_msg_req.filename, ExpectedBlockNo, ActualBlockNo]),
+    Reply = #tftp_msg_ack{block_no = ExpectedBlockNo},
+    {Config2, Callback2, TransferRes} = 
+        wait_for_msg_and_handle_timeout(Config, Callback, Req, Reply, LocalAccess, ExpectedBlockNo, Prepared),
+    ?MODULE:common_loop(Config2, Callback2, Req, TransferRes, LocalAccess, ExpectedBlockNo);
+common_write(Config, Callback, Req, _, ExpectedBlockNo, ActualBlockNo, Data, Prepared)
+  when is_binary(Data), is_record(Prepared, prepared) ->
+    Code = badblk,
+    Text = "Unknown transfer ID = " ++ 
+        integer_to_list(ActualBlockNo) ++ " (" ++ integer_to_list(ExpectedBlockNo) ++ ")", 
+    {undefined, Error} =
+        callback({abort, {Code, Text}}, Config, Callback, Req),
+    send_msg(Config, Req, Error),
+    terminate(Config, Req, ?ERROR(write, Code, Text, Req#tftp_msg_req.filename)).
+
+common_ack(Config, Callback, Req, LocalAccess, BlockNo, Prepared) 
+  when is_record(Prepared, prepared) ->
+    Reply = #tftp_msg_ack{block_no = BlockNo},
+    NextBlockNo = (BlockNo + 1) rem 65536,
+    {Config2, Callback2, TransferRes} = 
+        transfer(Config, Callback, Req, Reply, LocalAccess, NextBlockNo, Prepared),
+    ?MODULE:common_loop(Config2, Callback2, Req, TransferRes, LocalAccess, NextBlockNo).
+
+pre_terminate(Config, Req, Result) ->
+    if
+        Req#tftp_msg_req.local_filename =/= undefined,
+        Config#config.parent_pid =/= undefined ->
+            proc_lib:init_ack(Result),
+            unlink(Config#config.parent_pid),
+            Config#config{parent_pid = undefined, polite_ack = true};
+        true ->
+            Config#config{polite_ack = true}
+    end.
+
+-spec terminate(#config{}, #tftp_msg_req{}, {'ok', _} | #error{}) -> no_return().
+
+terminate(Config, Req, Result) ->
+    Result2 =
+        case Result of
+            {ok, _} ->
+                Result;
+            #error{where = Where, code = Code, text = Text} = Error ->
+                print_debug_info(Config, Req, Where, Error#error{filename = Req#tftp_msg_req.filename}),
+                {error, {Where, Code, Text}}
+        end,  
+    if
+        Config#config.parent_pid =:= undefined ->
+            close_port(Config, client, Req),
+            exit(normal);
+        Req#tftp_msg_req.local_filename =/= undefined  ->
+            %% Client
+            close_port(Config, client, Req),
+            proc_lib:init_ack(Result2),
+            unlink(Config#config.parent_pid),
+            exit(normal);
+        true ->
+            %% Server
+            close_port(Config, server, Req),
+            exit(shutdown)                  
+    end.
+
+close_port(Config, Who, Req) when is_record(Req, tftp_msg_req) ->
+    case Config#config.udp_socket of
+        undefined -> 
+            ignore;
+        Socket    -> 
+            print_debug_info(Config, Who, close, Req),
+            gen_udp:close(Socket)
+    end.
+
+open_free_port(Config, Who, Req) when is_record(Config, config), is_record(Req, tftp_msg_req) ->
+    UdpOptions = Config#config.udp_options,
+    case Config#config.port_policy of
+        random ->
+            %% BUGBUG: Should be a random port
+            case catch gen_udp:open(0, UdpOptions) of
+                {ok, Socket} ->
+                    Config2 = Config#config{udp_socket = Socket},
+                    print_debug_info(Config2, Who, open, Req),
+                    {ok, Config2};
+                {error, Reason} ->
+                    Text = lists:flatten(io_lib:format("UDP open ~p -> ~p", [[0 | UdpOptions], Reason])),
+                    ?ERROR(open, undef, Text, Req#tftp_msg_req.filename);
+                {'EXIT', _} = Reason ->
+                    Text = lists:flatten(io_lib:format("UDP open ~p -> ~p", [[0 | UdpOptions], Reason])),
+                    ?ERROR(open, undef, Text, Req#tftp_msg_req.filename)
+            end;
+        {range, Port, Max} when Port =< Max ->
+            case catch gen_udp:open(Port, UdpOptions) of
+                {ok, Socket} ->
+                    Config2 = Config#config{udp_socket = Socket},
+                    print_debug_info(Config2, Who, open, Req),
+                    {ok, Config2};
+                {error, eaddrinuse} ->
+                    PortPolicy = {range, Port + 1, Max},
+                    Config2 = Config#config{port_policy = PortPolicy},
+                    open_free_port(Config2, Who, Req);
+                {error, Reason} ->
+                    Text = lists:flatten(io_lib:format("UDP open ~p -> ~p", [[Port | UdpOptions], Reason])),
+                    ?ERROR(open, undef, Text, Req#tftp_msg_req.filename);
+                {'EXIT', _} = Reason->
+                    Text = lists:flatten(io_lib:format("UDP open ~p -> ~p", [[Port | UdpOptions], Reason])),
+                    ?ERROR(open, undef, Text, Req#tftp_msg_req.filename)
+            end;
+        {range, Port, _Max} ->
+            Reason = "Port range exhausted",
+            Text = lists:flatten(io_lib:format("UDP open ~p -> ~p", [[Port | UdpOptions], Reason])),
+            ?ERROR(Who, undef, Text, Req#tftp_msg_req.filename)
+    end.
+
+%%-------------------------------------------------------------------
+%% Transfer
+%%-------------------------------------------------------------------
+
+%% Returns {Config, Callback, #transfer_res{}}
+transfer(Config, Callback, Req, Msg, LocalAccess, NextBlockNo, Prepared) 
+  when is_record(Prepared, prepared) ->
+    IoList = tftp_lib:encode_msg(Msg),
+    Retries = Config#config.max_retries + 1,
+    do_transfer(Config, Callback, Req, Msg, IoList, LocalAccess, NextBlockNo, Prepared, Retries).
+
+do_transfer(Config, Callback, Req, Msg, IoList, LocalAccess, NextBlockNo, Prepared, Retries)
+  when is_record(Prepared, prepared), is_integer(Retries), Retries >= 0 ->
+    case do_send_msg(Config, Req, Msg, IoList) of
+        ok ->
+            {Callback2, Prepared2} = 
+                early_read(Config, Callback, Req, LocalAccess, NextBlockNo, Prepared),
+            do_wait_for_msg_and_handle_timeout(Config, Callback2, Req, Msg, IoList, LocalAccess, NextBlockNo, Prepared2, Retries);
+        {error, _Reason} when Retries > 0 ->
+            Retries2 = 0, % Just retry once when send fails
+            do_transfer(Config, Callback, Req, Msg, IoList, LocalAccess, NextBlockNo, Prepared, Retries2);
+        {error, Reason} ->
+            Code = undef,
+            Text = lists:flatten(io_lib:format("Transfer failed - giving up -> ~p", [Reason])),
+            Error = #tftp_msg_error{code = Code, text = Text},
+            {Config, Callback, #transfer_res{status = error, prepared = Error}}
+    end.
+
+wait_for_msg_and_handle_timeout(Config, Callback, Req, Msg, LocalAccess, NextBlockNo, Prepared) ->
+    IoList = tftp_lib:encode_msg(Msg),
+    Retries = Config#config.max_retries + 1,
+    do_wait_for_msg_and_handle_timeout(Config, Callback, Req, Msg, IoList, LocalAccess, NextBlockNo, Prepared, Retries).
+
+do_wait_for_msg_and_handle_timeout(Config, Callback, Req, Msg, IoList, LocalAccess, NextBlockNo, Prepared, Retries) ->
+    Code = undef,
+    Text = "Transfer timed out.",
+    case wait_for_msg(Config, Callback, Req) of
+        timeout when Config#config.polite_ack =:= true ->
+            do_send_msg(Config, Req, Msg, IoList),
+            case Prepared of
+                #prepared{status = terminate, result = Result} ->
+                    terminate(Config, Req, {ok, Result});
+                #prepared{} ->
+                    terminate(Config, Req, ?ERROR(transfer, Code, Text, Req#tftp_msg_req.filename))
+            end;
+        timeout when Retries > 0 ->
+            Retries2 = Retries - 1,
+            do_transfer(Config, Callback, Req, Msg, IoList, LocalAccess, NextBlockNo, Prepared, Retries2);
+        timeout ->
+            Error = #tftp_msg_error{code = Code, text = Text},
+            {Config, Callback, #transfer_res{status = error, prepared = Error}};
+        {Config2, DecodedMsg} ->
+            {Config2, Callback, #transfer_res{status = ok, decoded_msg = DecodedMsg, prepared = Prepared}}
+    end.
+
+send_msg(Config, Req, Msg) ->
+    case catch tftp_lib:encode_msg(Msg) of
+        {'EXIT', Reason} ->
+            Code = undef,
+            Text = "Internal error. Encode failed",
+            Msg2 = #tftp_msg_error{code = Code, text = Text, details = Reason},
+            send_msg(Config, Req, Msg2);
+        IoList ->
+            do_send_msg(Config, Req, Msg, IoList)
+    end.
+
+do_send_msg(#config{udp_socket = Socket, udp_host = RemoteHost, udp_port = RemotePort} = Config, Req, Msg, IoList) ->
+    %% {ok, LocalPort} = inet:port(Socket),
+    %% if
+    %%     LocalPort =/= ?TFTP_DEFAULT_PORT ->
+    %%         ok;
+    %%     true  ->
+    %%         print_debug_info(Config#config{debug_level = all}, Req, send, Msg),
+    %%         error(Config, 
+    %%               "Daemon replies from the default port (~p)\n\t to ~p:~p\n\t¨~p\n",
+    %%               [LocalPort, RemoteHost, RemotePort, Msg])
+    %% end,
+
+    print_debug_info(Config, Req, send, Msg),
+
+    %% case os:getenv("TFTPDUMP") of
+    %%  false     ->
+    %%      ignore;
+    %%  DumpPath  ->
+    %%      trace_udp_send(Req, Msg, IoList, DumpPath)
+    %% end,
+    Res = gen_udp:send(Socket, RemoteHost, RemotePort, IoList),
+    case Res of
+        ok ->
+            ok;
+        {error, einval = Reason} ->
+            error_msg(Config,
+                      "Stacktrace; ~p\n gen_udp:send(~p, ~p, ~p, ~p) -> ~p\n", 
+                      [erlang:get_stacktrace(), Socket, RemoteHost, RemotePort, IoList, {error, Reason}]);
+        {error, Reason} ->
+            {error, Reason} 
+    end.
+
+%% trace_udp_send(#tftp_msg_req{filename = [$/ | RelFile]} = Req, Msg, IoList, DumpPath) ->
+%%     trace_udp_send(Req#tftp_msg_req{filename = RelFile}, Msg, IoList, DumpPath);
+%% trace_udp_send(#tftp_msg_req{filename = RelFile},
+%%             #tftp_msg_data{block_no = BlockNo, data = Data},
+%%             _IoList,
+%%             DumpPath) ->
+%%     File = filename:join([DumpPath, RelFile, "block" ++ string:right(integer_to_list(BlockNo), 5, $0)  ++ ".dump"]),
+%%     if
+%%      (BlockNo rem 1000) =:= 1 -> 
+%%          info_msg(Config, "TFTPDUMP: Data    ~s\n", [File]);
+%%      true ->
+%%          ignore
+%%     end,
+%%     ok = filelib:ensure_dir(File),
+%%     ok = file:write_file(File, Data);
+%% trace_udp_send(#tftp_msg_req{filename = RelFile}, Msg, _IoList, _DumpPath) ->
+%%     info_msg(Config, "TFTPDUMP: No data  ~s -> ~p\n", [RelFile, element(1, Msg)]).
+
+wait_for_msg(Config, Callback, Req) ->
+    receive
+        {udp, Socket, RemoteHost, RemotePort, Bin}
+        when is_binary(Bin), Callback#callback.block_no =:= undefined ->
+            %% Client prepare
+            inet:setopts(Socket, [{active, once}]),
+            Config2 = Config#config{udp_host = RemoteHost,
+                                    udp_port = RemotePort},
+            DecodedMsg = (catch tftp_lib:decode_msg(Bin)),
+            print_debug_info(Config2, Req, recv, DecodedMsg),
+            {Config2, DecodedMsg};
+        {udp, Socket, Host, Port, Bin} when is_binary(Bin),
+                                            Config#config.udp_host =:= Host,
+                                            Config#config.udp_port =:= Port ->
+            inet:setopts(Socket, [{active, once}]),
+            DecodedMsg = (catch tftp_lib:decode_msg(Bin)),
+            print_debug_info(Config, Req, recv, DecodedMsg),
+            {Config, DecodedMsg};
+        {info, Ref, FromPid} when is_pid(FromPid) ->
+            Type =
+                case Req#tftp_msg_req.local_filename =/= undefined of
+                    true  -> client;
+                    false -> server
+                end,
+            Info = internal_info(Config, Type),
+            reply({ok, Info}, Ref, FromPid),
+            wait_for_msg(Config, Callback, Req);
+        {{change_config, Options}, Ref, FromPid} when is_pid(FromPid) ->
+            case catch tftp_lib:parse_config(Options, Config) of
+                {'EXIT', Reason} ->
+                    reply({error, Reason}, Ref, FromPid),
+                    wait_for_msg(Config, Callback, Req);
+                Config2 when is_record(Config2, config) ->
+                    reply(ok, Ref, FromPid),
+                    wait_for_msg(Config2, Callback, Req)
+            end;
+        {system, From, Msg} ->
+            Misc = #sys_misc{module = ?MODULE, function = wait_for_msg, arguments = [Config, Callback, Req]},
+            sys:handle_system_msg(Msg, From, Config#config.parent_pid, ?MODULE, [], Misc);
+        {'EXIT', Pid, _Reason} when Config#config.parent_pid =:= Pid ->
+            Code = undef,
+            Text = "Parent exited.",
+            terminate(Config, Req, ?ERROR(wait_for_msg, Code, Text, Req#tftp_msg_req.filename));
+        Msg when Req#tftp_msg_req.local_filename =/= undefined ->
+            warning_msg(Config, "Client received : ~p", [Msg]),
+            wait_for_msg(Config, Callback, Req);
+        Msg when Req#tftp_msg_req.local_filename =:= undefined ->
+            warning_msg(Config, "Server received : ~p", [Msg]),
+            wait_for_msg(Config, Callback, Req)
+    after Config#config.timeout * 1000 ->
+            print_debug_info(Config, Req, recv, timeout),
+            timeout
+    end.
+
+early_read(Config, Callback, Req, LocalAccess, _NextBlockNo,
+           #prepared{status = Status, next_data = NextData, prev_data = PrevData} = Prepared) ->
+    if
+        Status =/= terminate,
+        LocalAccess =:= read,
+        Callback#callback.block_no =/= undefined,
+        NextData =:= undefined ->
+            case callback(read, Config, Callback, Req) of
+                {undefined, Error} when is_record(Error, tftp_msg_error) ->
+                    {undefined, Error};
+                {Callback2, Prepared2} when is_record(Prepared2, prepared)->
+                    {Callback2, Prepared2#prepared{prev_data = PrevData}}
+            end;
+        true ->
+            {Callback, Prepared}
+    end.
+
+%%-------------------------------------------------------------------
+%% Callback
+%%-------------------------------------------------------------------
+
+callback(Access, Config, Callback, Req) ->
+    {Callback2, Result} =
+        do_callback(Access, Config, Callback, Req),
+    print_debug_info(Config, Req, call, {Callback2, Result}),
+    {Callback2, Result}.
+
+do_callback(read = Fun, Config, Callback, Req) 
+  when is_record(Config, config),
+       is_record(Callback, callback),
+       is_record(Req, tftp_msg_req) ->
+    Args =  [Callback#callback.state],
+    NextBlockNo = Callback#callback.block_no + 1,
+    case catch safe_apply(Callback#callback.module, Fun, Args) of
+        {more, Bin, NewState} when is_binary(Bin) ->
+            Count = Callback#callback.count + size(Bin),
+            Callback2 = Callback#callback{state    = NewState, 
+                                          block_no = NextBlockNo,
+                                          count    = Count},
+            Prepared = #prepared{status    = more,
+                                 result    = undefined,
+                                 block_no  = NextBlockNo,
+                                 next_data = Bin},
+            verify_count(Config, Callback2, Req, Prepared);
+        {last, Bin, Result} when is_binary(Bin) ->
+            Prepared = #prepared{status    = last,
+                                 result    = Result,
+                                 block_no  = NextBlockNo,
+                                 next_data = Bin},
+            {undefined, Prepared};
+        {error, {Code, Text}} ->
+            Error = #tftp_msg_error{code = Code, text = Text},
+            Prepared = #prepared{status = error,
+                                 result = Error},
+            {undefined, Prepared};
+        Illegal ->
+            Code = undef,
+            Text = "Internal error. File handler error.",
+            callback({abort, {Code, Text, Illegal}}, Config, Callback, Req)
+    end;
+do_callback({write = Fun, Bin}, Config, Callback, Req)
+  when is_record(Config, config),
+       is_record(Callback, callback),
+       is_record(Req, tftp_msg_req),
+       is_binary(Bin) ->
+    Args =  [Bin, Callback#callback.state],
+    NextBlockNo = Callback#callback.block_no + 1,
+    case catch safe_apply(Callback#callback.module, Fun, Args) of
+        {more, NewState} ->
+            Count = Callback#callback.count + size(Bin),
+            Callback2 = Callback#callback{state    = NewState, 
+                                          block_no = NextBlockNo,
+                                          count    = Count},
+            Prepared = #prepared{status    = more,
+                                 block_no  = NextBlockNo},          
+            verify_count(Config, Callback2, Req, Prepared);
+        {last, Result} ->
+            Prepared = #prepared{status   = last,
+                                 result   = Result,
+                                 block_no = NextBlockNo},          
+            {undefined, Prepared};
+        {error, {Code, Text}} ->
+            Error = #tftp_msg_error{code = Code, text = Text},
+            Prepared = #prepared{status = error,
+                                 result = Error},
+            {undefined, Prepared};      
+        Illegal ->
+            Code = undef,
+            Text = "Internal error. File handler error.",
+            callback({abort, {Code, Text, Illegal}}, Config, Callback, Req)
+    end;
+do_callback({open, Type}, Config, Callback, Req)
+  when is_record(Config, config),
+       is_record(Callback, callback),
+       is_record(Req, tftp_msg_req) ->
+    {Access, Filename} = local_file_access(Req),
+    {Fun, BlockNo} =
+        case Type of
+            client_prepare -> {prepare, undefined};
+            client_open    -> {open, 0};
+            server_open    -> {open, 0}
+        end,
+    Mod = Callback#callback.module,
+    Args = [Access,
+            Filename,
+            Req#tftp_msg_req.mode,
+            Req#tftp_msg_req.options,
+            Callback#callback.state],
+    PeerInfo = peer_info(Config),
+    fast_ensure_loaded(Mod),
+    Args2 =
+        case erlang:function_exported(Mod, Fun, length(Args)) of
+            true  -> Args;
+            false -> [PeerInfo | Args]
+        end,
+    case catch safe_apply(Mod, Fun, Args2) of
+        {ok, AcceptedOptions, NewState} ->
+            Callback2 = Callback#callback{state    = NewState, 
+                                          block_no = BlockNo, 
+                                          count    = 0}, 
+            {Callback2, {ok, AcceptedOptions}};
+        {error, {Code, Text}} ->
+            {undefined, #tftp_msg_error{code = Code, text = Text}};
+        Illegal ->
+            Code = undef,
+            Text = "Internal error. File handler error.",
+            callback({abort, {Code, Text, Illegal}}, Config, Callback, Req)
+    end;
+do_callback({abort, {Code, Text}}, Config, Callback, Req) ->
+    Error = #tftp_msg_error{code = Code, text = Text},
+    do_callback({abort, Error}, Config, Callback, Req);
+do_callback({abort, {Code, Text, Details}}, Config, Callback, Req) ->
+    Error = #tftp_msg_error{code = Code, text = Text, details = Details},
+    do_callback({abort, Error}, Config, Callback, Req);
+do_callback({abort = Fun, #tftp_msg_error{code = Code, text = Text} = Error}, Config, Callback, Req)
+  when is_record(Config, config),
+       is_record(Callback, callback), 
+       is_record(Req, tftp_msg_req) ->
+    Args =  [Code, Text, Callback#callback.state],
+    catch safe_apply(Callback#callback.module, Fun, Args),
+    {undefined, Error};
+do_callback({abort, Error}, _Config, undefined, _Req) when is_record(Error, tftp_msg_error) ->
+    {undefined, Error}.
+
+peer_info(#config{udp_host = Host, udp_port = Port}) ->
+    if
+        is_tuple(Host), size(Host) =:= 4 ->
+            {inet, tftp_lib:host_to_string(Host), Port};
+        is_tuple(Host), size(Host) =:= 8 ->
+            {inet6, tftp_lib:host_to_string(Host), Port};
+        true ->
+            {undefined, Host, Port}
+    end.
+
+match_callback(Filename, Callbacks) ->
+    if
+        Filename =:= binary ->
+            lookup_callback_mod(tftp_binary, Callbacks);
+        is_binary(Filename) ->
+            lookup_callback_mod(tftp_binary, Callbacks);
+        true ->
+            do_match_callback(Filename, Callbacks)
+    end.
+
+do_match_callback(Filename, [C | Tail]) when is_record(C, callback) ->
+    case catch re:run(Filename, C#callback.internal, [{capture, none}]) of
+        match ->
+            {ok, C};
+        nomatch ->
+            do_match_callback(Filename, Tail);
+        Details ->
+            Code = baduser,
+            Text = "Internal error. File handler not found",
+            {error, #tftp_msg_error{code = Code, text = Text, details = Details}}
+    end;
+do_match_callback(Filename, []) ->
+    Code = baduser,
+    Text = "Internal error. File handler not found",
+    {error, #tftp_msg_error{code = Code, text = Text, details = Filename}}.
+
+lookup_callback_mod(Mod, Callbacks) ->
+    {value, C} = lists:keysearch(Mod, #callback.module, Callbacks),
+    {ok, C}.
+
+verify_count(Config, Callback, Req, Result) ->
+    case Config#config.max_tsize of
+        infinity ->
+            {Callback, Result};
+        Max when Callback#callback.count =< Max ->
+            {Callback, Result};
+        _Max ->
+            Code = enospc,
+            Text = "Too large file.",
+            callback({abort, {Code, Text}}, Config, Callback, Req)
+    end.
+
+%%-------------------------------------------------------------------
+%% Miscellaneous
+%%-------------------------------------------------------------------
+
+internal_info(Config, Type) when is_record(Config, config) ->
+    {ok, ActualPort} = inet:port(Config#config.udp_socket),
+    [
+     {type, Type},
+     {host, tftp_lib:host_to_string(Config#config.udp_host)},
+     {port, Config#config.udp_port},
+     {local_port, ActualPort},
+     {port_policy, Config#config.port_policy},
+     {udp, Config#config.udp_options},
+     {use_tsize, Config#config.use_tsize},
+     {max_tsize, Config#config.max_tsize},
+     {max_conn, Config#config.max_conn},
+     {rejected, Config#config.rejected},
+     {timeout, Config#config.timeout},
+     {polite_ack, Config#config.polite_ack},
+     {debug, Config#config.debug_level},
+     {parent_pid, Config#config.parent_pid}
+    ] ++ Config#config.user_options ++ Config#config.callbacks.
+
+local_file_access(#tftp_msg_req{access = Access, 
+                                local_filename = Local, 
+                                filename = Filename}) ->
+    case Local =:= undefined of
+        true ->
+            %% Server side
+            {Access, Filename};
+        false ->
+            %% Client side
+            case Access of
+                read  -> {write, Local};
+                write -> {read, Local}
+            end
+    end.
+
+pre_verify_options(Config, Req) ->
+    Options = Req#tftp_msg_req.options,
+    case catch verify_reject(Config, Req, Options) of
+        ok ->
+            case verify_integer("tsize", 0, Config#config.max_tsize, Options) of
+                true ->
+                    case verify_integer("blksize", 0, 65464, Options) of
+                        true ->
+                            ok;
+                        false ->
+                            {error, {badopt, "Too large blksize"}}
+                    end;
+                false ->
+                    {error, {badopt, "Too large tsize"}}
+            end;
+        {error, Reason} ->
+            {error, Reason}
+    end.
+    
+post_verify_options(Config, Req, NewOptions, Text) ->
+    OldOptions = Req#tftp_msg_req.options,
+    BadOptions  = 
+        [Key || {Key, _Val} <- NewOptions, 
+                not lists:keymember(Key, 1, OldOptions)],
+    case BadOptions =:= [] of
+        true ->
+            Config2 = Config#config{timeout = lookup_timeout(NewOptions)},
+            Req2 = Req#tftp_msg_req{options = NewOptions},
+            {ok, Config2, Req2};
+        false ->
+            {error, {badopt, Text}}
+    end.
+
+verify_reject(Config, Req, Options) ->
+    Access = Req#tftp_msg_req.access,
+    Rejected = Config#config.rejected,
+    case lists:member(Access, Rejected) of
+        true ->
+            {error, {eacces, atom_to_list(Access) ++ " mode not allowed"}};
+        false ->
+            [throw({error, {badopt, Key ++ " not allowed"}}) ||
+                {Key, _} <- Options, lists:member(Key, Rejected)],
+            ok
+    end.
+
+lookup_timeout(Options) ->
+    case lists:keysearch("timeout", 1, Options) of
+        {value, {_, Val}} ->
+            list_to_integer(Val);
+        false ->
+            3
+    end.
+
+lookup_mode(Options) ->
+    case lists:keysearch("mode", 1, Options) of
+        {value, {_, Val}} ->
+            Val;
+        false ->
+            "octet"
+    end.
+
+verify_integer(Key, Min, Max, Options) ->
+    case lists:keysearch(Key, 1, Options) of
+        {value, {_, Val}} when is_list(Val) ->
+            case catch list_to_integer(Val) of
+                {'EXIT', _} ->
+                    false;
+                Int when Int >= Min, is_integer(Min),
+                         Max =:= infinity ->
+                    true;
+                Int when Int >= Min, is_integer(Min),
+                         Int =< Max, is_integer(Max) ->
+                    true;
+                _ ->
+                    false
+            end;
+        false ->
+            true
+    end.
+
+error_msg(#config{logger = Logger, debug_level = _Level}, F, A) ->
+    safe_apply(Logger, error_msg, [F, A]).
+
+warning_msg(#config{logger = Logger, debug_level = Level}, F, A) ->
+    case Level of
+        none  -> ok;
+        error -> ok;
+        _     -> safe_apply(Logger, warning_msg, [F, A])
+    end.
+
+info_msg(#config{logger = Logger}, F, A) ->
+    safe_apply(Logger, info_msg, [F, A]).
+
+safe_apply(Mod, Fun, Args) ->
+    fast_ensure_loaded(Mod),
+    apply(Mod, Fun, Args).
+
+fast_ensure_loaded(Mod) ->
+    case erlang:function_exported(Mod, module_info, 0) of
+        true  ->
+            ok;
+        false ->
+            Res = code:load_file(Mod),
+            %% io:format("tftp: code:load_file(~p) -> ~p\n", [Mod, Res]), %% XXX
+            Res
+    end.
+    
+print_debug_info(#config{debug_level = Level} = Config, Who, Where, Data) ->
+    if
+        Level =:= none ->
+            ok;
+        is_record(Data, error) ->
+            do_print_debug_info(Config, Who, Where, Data);
+        Level =:= warning ->
+            ok;
+        Level =:= error ->
+            ok; 
+        Level =:= all ->
+            do_print_debug_info(Config, Who, Where, Data);
+        Where =:= open ->
+            do_print_debug_info(Config, Who, Where, Data);
+        Where =:= close ->
+            do_print_debug_info(Config, Who, Where, Data);
+        Level =:= brief ->
+            ok; 
+        Where =/= recv, Where =/= send ->
+            ok;
+        is_record(Data, tftp_msg_data), Level =:= normal ->
+            ok;  
+        is_record(Data, tftp_msg_ack), Level =:= normal ->
+            ok;
+        true ->
+            do_print_debug_info(Config, Who, Where, Data)
+    end.
+
+do_print_debug_info(Config, Who, Where, #tftp_msg_data{data = Bin} = Msg) when is_binary(Bin) ->
+    Msg2 = Msg#tftp_msg_data{data = {bytes, size(Bin)}},
+    do_print_debug_info(Config, Who, Where, Msg2);
+do_print_debug_info(Config, Who, Where, #tftp_msg_req{local_filename = Filename} = Msg) when is_binary(Filename) ->
+    Msg2 = Msg#tftp_msg_req{local_filename = binary},
+    do_print_debug_info(Config, Who, Where, Msg2);
+do_print_debug_info(Config, Who, Where, Data) ->
+    Local = 
+        case catch inet:port(Config#config.udp_socket) of
+            {'EXIT', _Reason} ->
+                0;
+            {ok, Port} ->
+                Port
+        end,
+    %% Remote = Config#config.udp_port,
+    PeerInfo = lists:flatten(io_lib:format("~p", [peer_info(Config)])),
+    Side = 
+        if
+            is_record(Who, tftp_msg_req),
+            Who#tftp_msg_req.local_filename =/= undefined ->
+                client;
+            is_record(Who, tftp_msg_req),
+            Who#tftp_msg_req.local_filename =:= undefined ->
+                server;
+            is_atom(Who) ->
+                Who
+        end,
+    case {Where, Data} of
+        {_, #error{where = Where, code = Code, text = Text, filename = Filename}} -> 
+            do_format(Config, Side, Local, "error ~s ->\n\t~p ~p\n\t~p ~p: ~s\n",
+                      [PeerInfo, self(), Filename, Where, Code, Text]);
+        {open, #tftp_msg_req{filename = Filename}} ->
+            do_format(Config, Side, Local, "open  ~s ->\n\t~p ~p\n",
+                      [PeerInfo, self(), Filename]);
+        {close, #tftp_msg_req{filename = Filename}} ->
+            do_format(Config, Side, Local, "close ~s ->\n\t~p ~p\n",
+                      [PeerInfo, self(), Filename]);
+        {recv, _} ->
+            do_format(Config, Side, Local, "recv  ~s <-\n\t~p\n",
+                      [PeerInfo, Data]);
+        {send, _} ->
+            do_format(Config, Side, Local, "send  ~s ->\n\t~p\n",
+                      [PeerInfo, Data]);
+        {match, _} when is_record(Data, callback) ->
+            Mod = Data#callback.module,
+            State = Data#callback.state,
+            do_format(Config, Side, Local, "match ~s ~p =>\n\t~p\n",
+                      [PeerInfo, Mod, State]);
+        {call, _} ->
+            case Data of
+                {Callback, _Result} when is_record(Callback, callback) ->
+                    Mod   = Callback#callback.module,
+                    State = Callback#callback.state,
+                    do_format(Config, Side, Local, "call ~s ~p =>\n\t~p\n",
+                              [PeerInfo, Mod, State]);
+                {undefined, Result}  ->
+                    do_format(Config, Side, Local, "call ~s result =>\n\t~p\n",
+                              [PeerInfo, Result])
+            end
+    end.
+
+do_format(Config, Side, Local, Format, Args) ->
+    info_msg(Config, "~p(~p): " ++ Format, [Side, Local | Args]).
+
+%%-------------------------------------------------------------------
+%% System upgrade
+%%-------------------------------------------------------------------
+
+system_continue(_Parent, _Debug, #sys_misc{module = Mod, function = Fun, arguments = Args}) ->
+    apply(Mod, Fun, Args);
+system_continue(Parent, Debug, {Fun, Args}) ->
+    %% Handle upgrade from old releases. Please, remove this clause in next release.
+    system_continue(Parent, Debug, #sys_misc{module = ?MODULE, function = Fun, arguments = Args}).
+
+-spec system_terminate(_, _, _, #sys_misc{} | {_, _}) -> no_return().
+
+system_terminate(Reason, _Parent, _Debug, #sys_misc{}) ->
+    exit(Reason);
+system_terminate(Reason, Parent, Debug, {Fun, Args}) ->
+    %% Handle upgrade from old releases. Please, remove this clause in next release.
+    system_terminate(Reason, Parent, Debug, #sys_misc{module = ?MODULE, function = Fun, arguments = Args}).
+
+system_code_change({Fun, Args}, _Module, _OldVsn, _Extra) ->
+    {ok, {Fun, Args}}.
diff --git a/lib/tftp/src/tftp_file.erl b/lib/tftp/src/tftp_file.erl
new file mode 100644
index 0000000000..7664324808
--- /dev/null
+++ b/lib/tftp/src/tftp_file.erl
@@ -0,0 +1,390 @@
+%%
+%% %CopyrightBegin%
+%% 
+%% Copyright Ericsson AB 2005-2016. All Rights Reserved.
+%% 
+%% Licensed under the Apache License, Version 2.0 (the "License");
+%% you may not use this file except in compliance with the License.
+%% You may obtain a copy of the License at
+%%
+%%     http://www.apache.org/licenses/LICENSE-2.0
+%%
+%% Unless required by applicable law or agreed to in writing, software
+%% distributed under the License is distributed on an "AS IS" BASIS,
+%% WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+%% See the License for the specific language governing permissions and
+%% limitations under the License.
+%% 
+%% %CopyrightEnd%
+%%
+%%
+
+%%%-------------------------------------------------------------------
+%%% File    : tft_file.erl
+%%% Author  : Hakan Mattsson <[email protected]>
+%%% Description : 
+%%%
+%%% Created : 24 May 2004 by Hakan Mattsson <[email protected]>
+%%%-------------------------------------------------------------------
+
+-module(tftp_file).
+
+%%%-------------------------------------------------------------------
+%%% Interface
+%%%-------------------------------------------------------------------
+
+-behaviour(tftp).
+
+-export([prepare/6, open/6, read/1, write/2, abort/3]).
+
+%%%-------------------------------------------------------------------
+%%% Defines
+%%%-------------------------------------------------------------------
+
+-include_lib("kernel/include/file.hrl").
+
+-record(initial,
+	{filename,
+	 is_native_ascii}).
+
+-record(state,
+	{access,
+	 filename,
+	 is_native_ascii,
+	 is_network_ascii,
+	 root_dir,
+	 options,
+	 blksize,
+	 fd,
+	 count,
+	 buffer}).
+
+%%-------------------------------------------------------------------
+%% prepare(Peer, Access, Filename, Mode, SuggestedOptions, InitialState) -> 
+%%    {ok, AcceptedOptions, NewState} | {error, Code, Text}
+%%
+%% Peer             = {PeerType, PeerHost, PeerPort}
+%% PeerType         = inet | inet6
+%% PeerHost         = ip_address()
+%% PeerPort         = integer()
+%% Acess            = read | write
+%% Filename         = string()
+%% Mode             = string()
+%% SuggestedOptions = [{Key, Value}]
+%% AcceptedOptions  = [{Key, Value}]
+%% Key              = string()
+%% Value            = string()
+%% InitialState     = [] | [{root_dir, string()}]
+%% NewState         = term()
+%% Code             = undef | enoent | eacces | enospc |
+%%                    badop | eexist | baduser | badopt |
+%%                    integer()
+%% Text             = string()
+%%
+%% Prepares open of a file on the client side.
+%% 
+%% Will be followed by a call to open/4 before any read/write access
+%% is performed. The AcceptedOptions will be sent to the server which
+%% will reply with those options that it accepts. The options that are
+%% accepted by the server will be forwarded to open/4 as SuggestedOptions.
+%%
+%% No new options may be added, but the ones that are present as
+%% SuggestedOptions may be omitted or replaced with new values
+%% in the AcceptedOptions.
+%%-------------------------------------------------------------------
+
+prepare(_Peer, Access, Filename, Mode, SuggestedOptions, Initial) when is_list(Initial) ->
+    %% Client side
+    case catch handle_options(Access, Filename, Mode, SuggestedOptions, Initial) of
+	{ok, Filename2, IsNativeAscii, IsNetworkAscii, AcceptedOptions} ->
+	    State = #state{access           = Access,
+			   filename         = Filename2,
+			   is_native_ascii  = IsNativeAscii,
+			   is_network_ascii = IsNetworkAscii,
+			   options  	    = AcceptedOptions,
+			   blksize  	    = lookup_blksize(AcceptedOptions),
+			   count    	    = 0,
+			   buffer   	   =  []},
+	    {ok, AcceptedOptions, State};
+	{error, {Code, Text}} ->
+	    {error, {Code, Text}}
+    end.
+
+%% ---------------------------------------------------------
+%% open(Peer, Access, Filename, Mode, SuggestedOptions, State) -> 
+%%    {ok, AcceptedOptions, NewState} | {error, Code, Text}
+%%
+%% Peer             = {PeerType, PeerHost, PeerPort}
+%% PeerType         = inet | inet6
+%% PeerHost         = ip_address()
+%% PeerPort         = integer()
+%% Acess            = read | write
+%% Filename         = string()
+%% Mode             = string()
+%% SuggestedOptions = [{Key, Value}]
+%% AcceptedOptions  = [{Key, Value}]
+%% Key              = string()
+%% Value            = string()
+%% State            = InitialState | #state{}
+%% InitialState     = [] | [{root_dir, string()}]
+%% NewState         = term()
+%% Code             = undef | enoent | eacces  | enospc |
+%%                    badop | eexist | baduser | badopt |
+%%                    integer()
+%% Text             = string()
+%%
+%% Opens a file for read or write access.
+%% 
+%% On the client side where the open/4 call has been preceeded by a
+%% call to prepare/4, all options must be accepted or rejected.
+%% On the server side, where there are no preceeding prepare/4 call,
+%% noo new options may be added, but the ones that are present as
+%% SuggestedOptions may be omitted or replaced with new values
+%% in the AcceptedOptions.
+%%-------------------------------------------------------------------
+
+open(Peer, Access, Filename, Mode, SuggestedOptions, Initial) when is_list(Initial) ->
+    %% Server side
+    case prepare(Peer, Access, Filename, Mode, SuggestedOptions, Initial) of
+	{ok, AcceptedOptions, State} ->
+	    open(Peer, Access, Filename, Mode, AcceptedOptions, State);
+	{error, {Code, Text}} ->
+	    {error, {Code, Text}}
+    end;
+open(_Peer, Access, Filename, Mode, NegotiatedOptions, State) when is_record(State, state) ->
+    %% Both sides
+    case catch handle_options(Access, Filename, Mode, NegotiatedOptions, State) of
+	{ok, _Filename2, _IsNativeAscii, _IsNetworkAscii, Options} 
+	   when Options =:= NegotiatedOptions ->
+	    do_open(State);
+	{error, {Code, Text}} ->
+	    {error, {Code, Text}}
+    end;
+open(Peer, Access, Filename, Mode, NegotiatedOptions, State) ->
+    %% Handle upgrade from old releases. Please, remove this clause in next release.
+    State2 = upgrade_state(State),
+    open(Peer, Access, Filename, Mode, NegotiatedOptions, State2).
+
+do_open(State) when is_record(State, state) ->
+    case file:open(State#state.filename, file_options(State)) of
+	{ok, Fd} ->
+	    {ok, State#state.options, State#state{fd = Fd}};
+	{error, Reason} when is_atom(Reason) ->
+	    {error, file_error(Reason)}
+    end.
+	
+file_options(State) ->
+    case State#state.access of
+	read  -> [read, read_ahead, raw, binary];
+	write -> [write, delayed_write, raw, binary]
+    end.
+
+file_error(Reason) when is_atom(Reason) ->
+    Details = file:format_error(Reason),
+    case Reason of
+	eexist -> {Reason, Details};
+	enoent -> {Reason, Details};
+	eacces -> {Reason, Details};
+	eperm  -> {eacces, Details};
+	enospc -> {Reason, Details};
+	_      -> {undef,  Details ++ " (" ++ atom_to_list(Reason) ++ ")"}
+    end.
+
+%%-------------------------------------------------------------------
+%% read(State) ->
+%%   {more, Bin, NewState} | {last, Bin, FileSize} | {error, {Code, Text}}
+%%
+%% State    = term()
+%% NewState = term()
+%% Bin      = binary()
+%% FileSize = integer()
+%% Code     = undef | enoent | eacces  | enospc |
+%%            badop | eexist | baduser | badopt |
+%%            integer()
+%% Text     = string()
+%%
+%% Reads a chunk from the file
+%% 
+%% The file is automatically closed when the last chunk is read.
+%%-------------------------------------------------------------------
+
+read(#state{access = read} = State) ->
+    BlkSize = State#state.blksize,
+    case file:read(State#state.fd, BlkSize) of
+	{ok, Bin} when is_binary(Bin), size(Bin) =:= BlkSize ->
+	    Count = State#state.count + size(Bin),
+	    {more, Bin, State#state{count = Count}};
+	{ok, Bin} when is_binary(Bin), size(Bin) < BlkSize ->
+	    file:close(State#state.fd),
+	    Count = State#state.count + size(Bin),
+	    {last, Bin, Count};
+	eof ->
+	    {last, <<>>, State#state.count};
+	{error, Reason} ->
+	    file:close(State#state.fd),
+	    {error, file_error(Reason)}
+    end;
+read(State) ->
+    %% Handle upgrade from old releases. Please, remove this clause in next release.
+    State2 = upgrade_state(State),
+    read(State2).
+
+%%-------------------------------------------------------------------
+%% write(Bin, State) ->
+%%   {more, NewState} | {last, FileSize} | {error, {Code, Text}}
+%%
+%% State    = term()
+%% NewState = term()
+%% Bin      = binary()
+%% FileSize = integer()
+%% Code     = undef | enoent | eacces  | enospc |
+%%            badop | eexist | baduser | badopt |
+%%            integer()
+%% Text     = string()
+%%
+%% Writes a chunk to the file
+%%
+%% The file is automatically closed when the last chunk is written
+%%-------------------------------------------------------------------
+
+write(Bin, #state{access = write} = State) when is_binary(Bin) ->
+    Size = size(Bin),
+    BlkSize = State#state.blksize,
+    case file:write(State#state.fd, Bin) of
+	ok when Size =:= BlkSize->
+	    Count = State#state.count + Size,
+	    {more, State#state{count = Count}};
+	ok when Size < BlkSize->
+	    file:close(State#state.fd),
+	    Count = State#state.count + Size,
+	    {last, Count};
+	{error, Reason}  ->
+	    file:close(State#state.fd),
+	    file:delete(State#state.filename),
+	    {error, file_error(Reason)}
+    end;
+write(Bin, State) ->
+    %% Handle upgrade from old releases. Please, remove this clause in next release.
+    State2 = upgrade_state(State),
+    write(Bin, State2).
+
+%%-------------------------------------------------------------------
+%% abort(Code, Text, State) -> ok
+%% 
+%% State    = term()
+%% Code     = undef  | enoent | eacces  | enospc |
+%%            badop  | eexist | baduser | badopt |
+%%            badblk | integer()
+%% Text     = string()
+%%
+%% Aborts the file transfer
+%%-------------------------------------------------------------------
+
+abort(_Code, _Text, #state{fd = Fd, access = Access} = State) ->
+    file:close(Fd),
+    case Access of
+	write ->
+	    ok = file:delete(State#state.filename);
+	read ->
+	    ok
+    end.
+
+%%-------------------------------------------------------------------
+%% Process options
+%%-------------------------------------------------------------------
+
+handle_options(Access, Filename, Mode, Options, Initial) ->
+    I = #initial{filename = Filename, is_native_ascii = is_native_ascii()},
+    {Filename2, IsNativeAscii} = handle_initial(Initial, I),
+    IsNetworkAscii = handle_mode(Mode, IsNativeAscii),
+    Options2 = do_handle_options(Access, Filename2, Options),
+    {ok, Filename2, IsNativeAscii, IsNetworkAscii, Options2}.
+
+handle_mode(Mode, IsNativeAscii) ->
+    case Mode of
+	"netascii" when IsNativeAscii =:= true -> true;
+	"octet" -> false;
+	_ -> throw({error, {badop, "Illegal mode " ++ Mode}})
+    end.
+
+handle_initial([{root_dir, Dir} | Initial], I) ->
+    case catch filename_join(Dir, I#initial.filename) of
+	{'EXIT', _} ->
+	    throw({error, {badop, "Internal error. root_dir is not a string"}});
+	Filename2 ->
+	    handle_initial(Initial, I#initial{filename = Filename2})
+    end;
+handle_initial([{native_ascii, Bool} | Initial], I) ->
+    case Bool of
+	true  -> handle_initial(Initial, I#initial{is_native_ascii = true});
+	false -> handle_initial(Initial, I#initial{is_native_ascii = false})
+    end;
+handle_initial([], I) when is_record(I, initial) ->
+    {I#initial.filename, I#initial.is_native_ascii};
+handle_initial(State, _) when is_record(State, state) ->
+    {State#state.filename, State#state.is_native_ascii}.
+
+filename_join(Dir, Filename) ->
+    case filename:pathtype(Filename) of
+	absolute ->
+	    [_ | RelFilename] = filename:split(Filename),
+	    filename:join([Dir, RelFilename]);
+	_ ->
+	    filename:join([Dir, Filename])
+    end.
+
+do_handle_options(Access, Filename, [{Key, Val} | T]) ->
+    case Key of
+	"tsize" ->
+	    case Access of
+		read when Val =:= "0" ->
+		    case file:read_file_info(Filename) of
+			{ok, FI} ->
+			    Tsize = integer_to_list(FI#file_info.size),
+			    [{Key, Tsize} | do_handle_options(Access, Filename, T)];
+			{error, _} ->
+			    do_handle_options(Access, Filename, T)
+		    end;
+		_ ->
+		    handle_integer(Access, Filename, Key, Val, T, 0, infinity)
+	    end;
+	"blksize" ->
+	    handle_integer(Access, Filename, Key, Val, T, 8, 65464);
+	"timeout" ->
+	    handle_integer(Access, Filename, Key, Val, T, 1, 255);
+	_ ->
+	    do_handle_options(Access, Filename, T)
+    end;
+do_handle_options(_Access, _Filename, []) ->
+    [].
+
+
+handle_integer(Access, Filename, Key, Val, Options, Min, Max) ->
+    case catch list_to_integer(Val) of
+	{'EXIT', _} ->
+	    do_handle_options(Access, Filename, Options);
+	Int when Int >= Min, Int =< Max ->
+	    [{Key, Val} | do_handle_options(Access, Filename, Options)];
+	Int when Int >= Min, Max =:= infinity ->
+	    [{Key, Val} | do_handle_options(Access, Filename, Options)];
+	_Int ->
+	    throw({error, {badopt, "Illegal " ++ Key ++ " value " ++ Val}})
+    end.
+
+lookup_blksize(Options) ->
+    case lists:keysearch("blksize", 1, Options) of
+	{value, {_, Val}} ->
+	    list_to_integer(Val);
+	false ->
+	    512
+    end.
+
+is_native_ascii() ->
+    case os:type() of
+	{win32, _} -> true;
+	_          -> false
+    end.
+
+%% Handle upgrade from old releases. Please, remove this function in next release.
+upgrade_state({state, Access, Filename, RootDir, Options, BlkSize, Fd, Count, Buffer}) ->
+    {state, Access, Filename, false, false, RootDir, Options, BlkSize, Fd, Count, Buffer}.
diff --git a/lib/tftp/src/tftp_lib.erl b/lib/tftp/src/tftp_lib.erl
new file mode 100644
index 0000000000..454754f0a3
--- /dev/null
+++ b/lib/tftp/src/tftp_lib.erl
@@ -0,0 +1,474 @@
+%%
+%% %CopyrightBegin%
+%% 
+%% Copyright Ericsson AB 2005-2016. All Rights Reserved.
+%% 
+%% Licensed under the Apache License, Version 2.0 (the "License");
+%% you may not use this file except in compliance with the License.
+%% You may obtain a copy of the License at
+%%
+%%     http://www.apache.org/licenses/LICENSE-2.0
+%%
+%% Unless required by applicable law or agreed to in writing, software
+%% distributed under the License is distributed on an "AS IS" BASIS,
+%% WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+%% See the License for the specific language governing permissions and
+%% limitations under the License.
+%% 
+%% %CopyrightEnd%
+%%
+%%
+
+%%%-------------------------------------------------------------------
+%%% File    : tftp_lib.erl
+%%% Author  : Hakan Mattsson <[email protected]>
+%%% Description : Option parsing, decode, encode etc.
+%%%
+%%% Created : 18 May 2004 by Hakan Mattsson <[email protected]>
+%%%-------------------------------------------------------------------
+
+-module(tftp_lib).
+
+%%-------------------------------------------------------------------
+%% Interface
+%%-------------------------------------------------------------------
+
+%% application internal functions
+-export([
+         parse_config/1,
+         parse_config/2,
+         decode_msg/1,
+         encode_msg/1,
+         replace_val/3,
+         to_lower/1,
+         host_to_string/1,
+	 add_default_callbacks/1
+        ]).
+
+%%-------------------------------------------------------------------
+%% Defines
+%%-------------------------------------------------------------------
+
+-include("tftp.hrl").
+
+-define(LOWER(Char),
+        if
+            Char >= $A, Char =< $Z ->
+                Char - ($A - $a);
+            true ->
+                Char
+        end).
+
+%%-------------------------------------------------------------------
+%% Config
+%%-------------------------------------------------------------------
+
+parse_config(Options) ->
+    parse_config(Options, #config{}).
+
+parse_config(Options, Config) ->
+    do_parse_config(Options, Config).
+
+do_parse_config([{Key, Val} | Tail], Config) when is_record(Config, config) ->
+    case Key of
+        debug ->
+            if
+                Val =:= 0; Val =:= none ->
+                    do_parse_config(Tail, Config#config{debug_level = none});
+                Val =:= 1; Val =:= error ->
+                    do_parse_config(Tail, Config#config{debug_level = error});
+                Val =:= 2; Val =:= warning ->
+                    do_parse_config(Tail, Config#config{debug_level = warning});
+                Val =:= 3; Val =:= brief ->
+                    do_parse_config(Tail, Config#config{debug_level = brief});
+                Val =:= 4; Val =:= normal ->
+                    do_parse_config(Tail, Config#config{debug_level = normal});
+                Val =:= 5; Val =:= verbose ->
+                    do_parse_config(Tail, Config#config{debug_level = verbose});
+                Val =:= 6; Val =:= all ->
+                    do_parse_config(Tail, Config#config{debug_level = all});
+                true ->
+                    exit({badarg, {Key, Val}})
+            end;
+        host ->
+            if
+                is_list(Val) ->
+                    do_parse_config(Tail, Config#config{udp_host = Val});
+                is_tuple(Val), size(Val) =:= 4 ->
+                    do_parse_config(Tail, Config#config{udp_host = Val});
+                is_tuple(Val), size(Val) =:= 8 ->
+                    do_parse_config(Tail, Config#config{udp_host = Val});
+                true ->
+                    exit({badarg, {Key, Val}})
+            end;
+        port ->
+            if
+                is_integer(Val), Val >= 0 ->
+                    Config2 = Config#config{udp_port = Val, udp_options = Config#config.udp_options},
+                    do_parse_config(Tail, Config2);
+                true ->
+                    exit({badarg, {Key, Val}})
+            end;
+        port_policy ->
+            case Val of
+                random ->
+                    do_parse_config(Tail, Config#config{port_policy = Val});
+                0 ->
+                    do_parse_config(Tail, Config#config{port_policy = random});
+                MinMax when is_integer(MinMax), MinMax > 0 ->
+                    do_parse_config(Tail, Config#config{port_policy = {range, MinMax, MinMax}});
+                {range, Min, Max} when Max >= Min, 
+                is_integer(Min), Min > 0,
+                is_integer(Max), Max > 0 ->
+                    do_parse_config(Tail, Config#config{port_policy = Val});
+                true ->
+                    exit({badarg, {Key, Val}})
+            end;
+        udp when is_list(Val) ->
+            Fun =  
+                fun({K, V}, List) when K /= active -> 
+                        replace_val(K, V, List);
+                   (V, List) when V /= list, V /= binary ->
+                        List ++ [V];
+                   (V, _List) ->
+                        exit({badarg, {udp, [V]}})
+                end,
+            UdpOptions = lists:foldl(Fun, Config#config.udp_options, Val),
+            do_parse_config(Tail, Config#config{udp_options = UdpOptions});
+        use_tsize ->
+            case Val of
+                true ->
+                    do_parse_config(Tail, Config#config{use_tsize = Val});
+                false ->
+                    do_parse_config(Tail, Config#config{use_tsize = Val});
+                _ ->
+                    exit({badarg, {Key, Val}})
+            end;
+        max_tsize ->
+            if
+                Val =:= infinity ->
+                    do_parse_config(Tail, Config#config{max_tsize = Val});
+                is_integer(Val), Val >= 0 ->
+                    do_parse_config(Tail, Config#config{max_tsize = Val});
+                true ->
+                    exit({badarg, {Key, Val}})
+            end;
+        max_conn ->
+            if
+                Val =:= infinity ->
+                    do_parse_config(Tail, Config#config{max_conn = Val});
+                is_integer(Val), Val > 0 ->
+                    do_parse_config(Tail, Config#config{max_conn = Val});
+                true ->
+                    exit({badarg, {Key, Val}})
+            end;
+        _ when is_list(Key), is_list(Val) ->
+            Key2 = to_lower(Key),
+            Val2 = to_lower(Val),
+            TftpOptions = replace_val(Key2, Val2, Config#config.user_options),
+            do_parse_config(Tail, Config#config{user_options = TftpOptions});
+        reject ->
+            case Val of
+                read ->
+                    Rejected = [Val | Config#config.rejected],
+                    do_parse_config(Tail, Config#config{rejected = Rejected});
+                write ->
+                    Rejected = [Val | Config#config.rejected],
+                    do_parse_config(Tail, Config#config{rejected = Rejected});
+                _ when is_list(Val) ->
+                    Rejected = [Val | Config#config.rejected],
+                    do_parse_config(Tail, Config#config{rejected = Rejected});
+                _ ->
+                    exit({badarg, {Key, Val}})
+            end;
+        callback ->
+            case Val of
+                {RegExp, Mod, State} when is_list(RegExp), is_atom(Mod) ->
+                    case re:compile(RegExp) of
+                        {ok, Internal} ->
+                            Callback = #callback{regexp   = RegExp,
+                                                 internal = Internal,
+                                                 module   = Mod,
+                                                 state    = State},
+                            Callbacks = Config#config.callbacks ++ [Callback],
+                            do_parse_config(Tail, Config#config{callbacks = Callbacks});
+                        {error, Reason} ->
+                            exit({badarg, {Key, Val}, Reason})
+                    end;
+                _ ->
+                    exit({badarg, {Key, Val}})
+            end;
+        logger ->
+            if
+                is_atom(Val) ->
+                    do_parse_config(Tail, Config#config{logger = Val});
+                true ->
+                    exit({badarg, {Key, Val}})
+            end;
+        max_retries ->
+            if
+                is_integer(Val), Val > 0 ->
+                    do_parse_config(Tail, Config#config{max_retries = Val});
+                true ->
+                    exit({badarg, {Key, Val}})
+            end;
+        _ ->
+            exit({badarg, {Key, Val}})
+    end;
+do_parse_config([], #config{udp_host     = Host,
+                            udp_options  = UdpOptions,
+                            user_options = UserOptions,
+                            callbacks    = Callbacks} = Config) ->
+    IsInet6 = lists:member(inet6, UdpOptions),
+    IsInet  = lists:member(inet, UdpOptions),
+    Host2 = 
+        if
+            (IsInet and not IsInet6); (not IsInet and not IsInet6) -> 
+                case inet:getaddr(Host, inet) of
+                    {ok, Addr} ->
+                        Addr;
+                    {error, Reason} ->
+                        exit({badarg, {host, Reason}})
+                end;
+            (IsInet6 and not IsInet)  ->
+                case inet:getaddr(Host, inet6) of
+                    {ok, Addr} ->
+                        Addr;
+                    {error, Reason} ->
+                        exit({badarg, {host, Reason}})
+                end;
+            true ->
+                %% Conflicting options
+                exit({badarg, {udp, [inet]}})
+        end,
+    UdpOptions2 = lists:reverse(UdpOptions),
+    TftpOptions = lists:reverse(UserOptions),
+    Callbacks2  = add_default_callbacks(Callbacks),
+    Config#config{udp_host     = Host2,
+                  udp_options  = UdpOptions2,
+                  user_options = TftpOptions,
+                  callbacks    = Callbacks2};
+do_parse_config(Options, Config) when is_record(Config, config) ->
+    exit({badarg, Options}).
+
+add_default_callbacks(Callbacks) ->
+    RegExp = "",
+    {ok, Internal} = re:compile(RegExp),
+    File = #callback{regexp   = RegExp,
+		     internal = Internal,
+		     module   = tftp_file,
+		     state    = []},
+    Bin = #callback{regexp   = RegExp,
+		    internal = Internal,
+		    module   = tftp_binary,
+		    state    = []},
+    Callbacks ++ [File, Bin].
+
+host_to_string(Host) ->
+    case Host of
+        String when is_list(String) ->
+            String;
+        {A1, A2, A3, A4} -> % inet
+            lists:concat([A1, ".", A2, ".", A3, ".",A4]);
+        {A1, A2, A3, A4, A5, A6, A7, A8} -> % inet6
+            lists:concat([
+                          int16_to_hex(A1), "::",
+                          int16_to_hex(A2), "::",
+                          int16_to_hex(A3), "::",
+                          int16_to_hex(A4), "::",
+                          int16_to_hex(A5), "::",
+                          int16_to_hex(A6), "::",
+                          int16_to_hex(A7), "::",
+                          int16_to_hex(A8)
+                         ])
+    end.
+
+int16_to_hex(0) ->
+    [$0];
+int16_to_hex(I) ->
+    N1 = ((I bsr 8) band 16#ff),
+    N2 = (I band 16#ff),
+    [code_character(N1 div 16), code_character(N1 rem 16),
+     code_character(N2 div 16), code_character(N2 rem 16)].
+
+code_character(N) when N < 10 ->
+    $0 + N;
+code_character(N) ->
+    $A + (N - 10).
+
+%%-------------------------------------------------------------------
+%% Decode
+%%-------------------------------------------------------------------
+
+decode_msg(Bin) when is_binary(Bin) ->
+    case Bin of
+        <<?TFTP_OPCODE_RRQ:16/integer, Tail/binary>> ->
+            case decode_strings(Tail, [keep_case, lower_case]) of
+                [Filename, Mode | Strings] ->
+                    Options = decode_options(Strings),
+                    #tftp_msg_req{access = read,
+                                  filename = Filename,
+                                  mode = to_lower(Mode),
+                                  options = Options};
+                [_Filename | _Strings] ->
+                    exit(#tftp_msg_error{code = undef,
+                                         text = "Missing mode"});
+                _ ->
+                    exit(#tftp_msg_error{code = undef,
+                                         text = "Missing filename"})
+            end;
+        <<?TFTP_OPCODE_WRQ:16/integer, Tail/binary>> ->
+            case decode_strings(Tail, [keep_case, lower_case]) of
+                [Filename, Mode | Strings] ->
+                    Options = decode_options(Strings),
+                    #tftp_msg_req{access = write,
+                                  filename = Filename,
+                                  mode = to_lower(Mode),
+                                  options = Options};
+                [_Filename | _Strings] ->
+                    exit(#tftp_msg_error{code = undef,
+                                         text = "Missing mode"});
+                _ ->
+                    exit(#tftp_msg_error{code = undef,
+                                         text = "Missing filename"})
+            end;
+        <<?TFTP_OPCODE_DATA:16/integer, SeqNo:16/integer, Data/binary>> ->
+            #tftp_msg_data{block_no = SeqNo, data = Data};
+        <<?TFTP_OPCODE_ACK:16/integer, SeqNo:16/integer>> ->
+            #tftp_msg_ack{block_no = SeqNo};
+        <<?TFTP_OPCODE_ERROR:16/integer, ErrorCode:16/integer, Tail/binary>> ->
+            case decode_strings(Tail, [keep_case]) of
+                [ErrorText] ->
+                    ErrorCode2 = decode_error_code(ErrorCode),
+                    #tftp_msg_error{code = ErrorCode2,
+                                    text = ErrorText};
+                _ ->
+                    exit(#tftp_msg_error{code = undef,
+                                         text = "Trailing garbage"})
+            end;
+        <<?TFTP_OPCODE_OACK:16/integer, Tail/binary>> ->
+            Strings = decode_strings(Tail, [lower_case]),
+            Options = decode_options(Strings),
+            #tftp_msg_oack{options = Options};
+        _ ->
+            exit(#tftp_msg_error{code = undef,
+                                 text = "Invalid syntax"})
+    end.
+
+decode_strings(Bin, Cases) when is_binary(Bin), is_list(Cases) ->
+    do_decode_strings(Bin, Cases, []).
+
+do_decode_strings(<<>>, _Cases, Strings) ->
+    lists:reverse(Strings);
+do_decode_strings(Bin, [Case | Cases], Strings) ->
+    {String, Tail} = decode_string(Bin, Case, []),
+    if
+        Cases =:= [] ->
+            do_decode_strings(Tail, [Case], [String | Strings]);
+        true ->
+            do_decode_strings(Tail, Cases,  [String | Strings])
+    end.
+
+decode_string(<<Char:8/integer, Tail/binary>>, Case, String) ->
+    if
+        Char =:= 0 ->
+            {lists:reverse(String), Tail};
+        Case =:= keep_case ->
+            decode_string(Tail, Case, [Char | String]);
+        Case =:= lower_case ->
+            Char2 = ?LOWER(Char),
+            decode_string(Tail, Case, [Char2 | String])
+    end;
+decode_string(<<>>, _Case, _String) ->
+    exit(#tftp_msg_error{code = undef, text = "Trailing null missing"}).
+
+decode_options([Key, Value | Strings]) ->
+    [{to_lower(Key), Value} | decode_options(Strings)];
+decode_options([]) ->
+    [].
+
+decode_error_code(Int) ->
+    case Int of
+        ?TFTP_ERROR_UNDEF   -> undef;
+        ?TFTP_ERROR_ENOENT  -> enoent;
+        ?TFTP_ERROR_EACCES  -> eacces;
+        ?TFTP_ERROR_ENOSPC  -> enospc;
+        ?TFTP_ERROR_BADOP   -> badop;
+        ?TFTP_ERROR_BADBLK  -> badblk;
+        ?TFTP_ERROR_EEXIST  -> eexist;
+        ?TFTP_ERROR_BADUSER -> baduser;
+        ?TFTP_ERROR_BADOPT  -> badopt;
+        Int when is_integer(Int), Int >= 0, Int =< 65535 -> Int;
+        _ -> exit(#tftp_msg_error{code = undef, text = "Error code outside range."})
+    end.
+
+%%-------------------------------------------------------------------
+%% Encode
+%%-------------------------------------------------------------------
+
+encode_msg(#tftp_msg_req{access = Access,
+                         filename = Filename,
+                         mode = Mode, 
+                         options = Options}) ->
+    OpCode = case Access of
+                 read  -> ?TFTP_OPCODE_RRQ;
+                 write -> ?TFTP_OPCODE_WRQ
+             end,
+    [
+     <<OpCode:16/integer>>,
+     Filename, 
+     0, 
+     Mode, 
+     0,
+     [[Key, 0, Val, 0] || {Key, Val} <- Options]
+    ];
+encode_msg(#tftp_msg_data{block_no = BlockNo, data = Data}) when BlockNo =< 65535 ->
+    [
+     <<?TFTP_OPCODE_DATA:16/integer, BlockNo:16/integer>>,
+     Data
+    ];
+encode_msg(#tftp_msg_ack{block_no = BlockNo}) when BlockNo =< 65535 ->
+    <<?TFTP_OPCODE_ACK:16/integer, BlockNo:16/integer>>;
+encode_msg(#tftp_msg_error{code = Code, text = Text}) ->
+    IntCode = encode_error_code(Code),
+    [
+     <<?TFTP_OPCODE_ERROR:16/integer, IntCode:16/integer>>, 
+     Text,
+     0
+    ];
+encode_msg(#tftp_msg_oack{options = Options}) ->
+    [
+     <<?TFTP_OPCODE_OACK:16/integer>>,
+     [[Key, 0, Val, 0] || {Key, Val} <- Options]
+    ].
+
+encode_error_code(Code) ->
+    case Code of
+        undef   -> ?TFTP_ERROR_UNDEF;
+        enoent  -> ?TFTP_ERROR_ENOENT;
+        eacces  -> ?TFTP_ERROR_EACCES;
+        enospc  -> ?TFTP_ERROR_ENOSPC;
+        badop   -> ?TFTP_ERROR_BADOP;
+        badblk  -> ?TFTP_ERROR_BADBLK;
+        eexist  -> ?TFTP_ERROR_EEXIST;
+        baduser -> ?TFTP_ERROR_BADUSER;
+        badopt  -> ?TFTP_ERROR_BADOPT;
+        Int when is_integer(Int), Int >= 0, Int =< 65535 -> Int
+    end.
+
+%%-------------------------------------------------------------------
+%% Miscellaneous
+%%-------------------------------------------------------------------
+
+replace_val(Key, Val, List) ->
+    case lists:keysearch(Key, 1, List) of
+        false ->
+            List ++ [{Key, Val}];
+        {value, {_, OldVal}} when OldVal =:= Val ->
+            List;
+        {value, {_, _}} ->
+            lists:keyreplace(Key, 1, List, {Key, Val})
+    end.
+
+to_lower(Chars) ->
+    [?LOWER(Char) || Char <- Chars].
diff --git a/lib/tftp/src/tftp_logger.erl b/lib/tftp/src/tftp_logger.erl
new file mode 100644
index 0000000000..a869958484
--- /dev/null
+++ b/lib/tftp/src/tftp_logger.erl
@@ -0,0 +1,99 @@
+%%
+%% %CopyrightBegin%
+%% 
+%% Copyright Ericsson AB 2008-2016. All Rights Reserved.
+%% 
+%% Licensed under the Apache License, Version 2.0 (the "License");
+%% you may not use this file except in compliance with the License.
+%% You may obtain a copy of the License at
+%%
+%%     http://www.apache.org/licenses/LICENSE-2.0
+%%
+%% Unless required by applicable law or agreed to in writing, software
+%% distributed under the License is distributed on an "AS IS" BASIS,
+%% WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+%% See the License for the specific language governing permissions and
+%% limitations under the License.
+%% 
+%% %CopyrightEnd%
+%%
+%%
+-module(tftp_logger).
+
+%%-------------------------------------------------------------------
+%% Interface
+%%-------------------------------------------------------------------
+
+%% public functions
+-export([
+	 error_msg/2,
+	 warning_msg/2,
+	 info_msg/2
+	]).
+
+-export([behaviour_info/1]).
+
+behaviour_info(callbacks) ->
+    [{error_msg, 2}, {warning_msg, 2}, {info_msg, 2}];
+behaviour_info(_) ->
+    undefined.
+
+%%-------------------------------------------------------------------
+%% error_msg(Format, Data) -> ok | exit(Reason)
+%% 
+%% Format = string()
+%% Data = [term()]
+%% Reason = term()
+%%
+%% Log an error message
+%%-------------------------------------------------------------------
+
+error_msg(Format, Data) ->
+    {Format2, Data2} = add_timestamp(Format, Data),
+    error_logger:error_msg(Format2, Data2).
+
+%%-------------------------------------------------------------------
+%% warning_msg(Format, Data) -> ok | exit(Reason)
+%% 
+%% Format = string()
+%% Data = [term()]
+%% Reason = term()
+%%
+%% Log a warning message
+%%-------------------------------------------------------------------
+
+warning_msg(Format, Data) ->
+    {Format2, Data2} = add_timestamp(Format, Data),
+    error_logger:warning_msg(Format2, Data2).
+
+%%-------------------------------------------------------------------
+%% info_msg(Format, Data) -> ok | exit(Reason)
+%% 
+%% Format = string()
+%% Data = [term()]
+%% Reason = term()
+%%
+%% Log an info message
+%%-------------------------------------------------------------------
+
+info_msg(Format, Data) ->
+    {Format2, Data2} = add_timestamp(Format, Data),
+    io:format(Format2, Data2).
+
+%%-------------------------------------------------------------------
+%% Add timestamp to log message
+%%-------------------------------------------------------------------
+
+add_timestamp(Format, Data) ->
+    Time = erlang:timestamp(),
+    {{_Y, _Mo, _D}, {H, Mi, S}} = calendar:now_to_universal_time(Time),
+    %% {"~p-~s-~sT~s:~s:~sZ,~6.6.0w tftp: " ++ Format ++ "\n", 
+    %%  [Y, t(Mo), t(D), t(H), t(Mi), t(S), MicroSecs | Data]}.
+    {"~s:~s:~s tftp: " ++ Format, [t(H), t(Mi), t(S) | Data]}.
+
+%% Convert 9 to "09".
+t(Int) ->
+    case integer_to_list(Int) of
+	[Single] -> [$0, Single];
+        Multi    -> Multi
+    end.
diff --git a/lib/tftp/src/tftp_sup.erl b/lib/tftp/src/tftp_sup.erl
new file mode 100644
index 0000000000..0475e53e42
--- /dev/null
+++ b/lib/tftp/src/tftp_sup.erl
@@ -0,0 +1,111 @@
+%%
+%% %CopyrightBegin%
+%% 
+%% Copyright Ericsson AB 2005-2016. All Rights Reserved.
+%% 
+%% Licensed under the Apache License, Version 2.0 (the "License");
+%% you may not use this file except in compliance with the License.
+%% You may obtain a copy of the License at
+%%
+%%     http://www.apache.org/licenses/LICENSE-2.0
+%%
+%% Unless required by applicable law or agreed to in writing, software
+%% distributed under the License is distributed on an "AS IS" BASIS,
+%% WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+%% See the License for the specific language governing permissions and
+%% limitations under the License.
+%% 
+%% %CopyrightEnd%
+%%
+%%
+%%----------------------------------------------------------------------
+%% Purpose: The top supervisor for tftp
+%%----------------------------------------------------------------------
+
+-module(tftp_sup).
+
+-behaviour(supervisor).
+
+%% API
+-export([start_link/1,
+	 start_child/1,
+	 stop_child/1,
+	 which_children/0]).
+
+%% Supervisor callback
+-export([init/1]).
+
+%%%=========================================================================
+%%%  API
+%%%=========================================================================
+
+start_link(TftpServices) ->
+    supervisor:start_link({local, ?MODULE}, ?MODULE, [TftpServices]).
+
+start_child(Options) ->
+    KillAfter = default_kill_after(),
+    ChildSpec = worker_spec(KillAfter, Options),
+    supervisor:start_child(?MODULE, ChildSpec).
+
+stop_child(Pid) when is_pid(Pid) ->
+    Children = supervisor:which_children(?MODULE),
+    case [Id || {Id, P, _Type, _Modules} <- Children, P =:= Pid] of
+	[] ->
+	    {error, not_found};
+	[Id] ->
+	    case supervisor:terminate_child(?MODULE, Id) of
+		ok ->
+		    supervisor:delete_child(?MODULE, Id);
+		{error, not_found} ->
+		    supervisor:delete_child(?MODULE, Id);
+		{error, Reason} ->
+		    {error, Reason}
+	    end
+    end.
+
+which_children() ->
+    Children = supervisor:which_children(?MODULE),
+    [{tftpd, Pid} || {_Id, Pid, _Type, _Modules} <- Children, Pid =/= undefined].
+    
+%%%=========================================================================
+%%%  Supervisor callback
+%%%=========================================================================
+
+init([Services]) when is_list(Services) ->
+    RestartStrategy = one_for_one,
+    MaxR = 10,
+    MaxT = 3600,
+    KillAfter = default_kill_after(),
+    Children = [worker_spec(KillAfter, Options) || {tftpd, Options} <- Services],
+    {ok, {{RestartStrategy, MaxR, MaxT}, Children}}.
+
+%%%=========================================================================
+%%%  Internal functions
+%%%=========================================================================
+
+worker_spec(KillAfter, Options) ->
+    Modules = [proc_lib, tftp, tftp_engine],
+    KA = supervisor_timeout(KillAfter),
+    Name = unique_name(Options),
+    {Name, {tftp, start, [Options]}, permanent, KA, worker, Modules}.
+
+unique_name(Options) ->
+    case lists:keysearch(port, 1, Options) of
+	{value, {_, Port}} when is_integer(Port), Port > 0 -> 
+	    {tftpd, Port};
+	_ ->
+	    {tftpd, erlang:unique_integer([positive])}
+    end.
+
+default_kill_after() ->
+    timer:seconds(3).
+
+%% supervisor_spec(Name) ->
+%%     {Name, {Name, start, []}, permanent, infinity, supervisor,
+%%      [Name, supervisor]}.
+    
+-ifdef(debug_shutdown).
+supervisor_timeout(_KillAfter) -> timer:hours(24).
+-else.
+supervisor_timeout(KillAfter) -> KillAfter.
+-endif.    
diff --git a/lib/tftp/test/Makefile b/lib/tftp/test/Makefile
new file mode 100644
index 0000000000..99f36256b0
--- /dev/null
+++ b/lib/tftp/test/Makefile
@@ -0,0 +1,250 @@
+#
+# %CopyrightBegin%
+#
+# Copyright Ericsson AB 1997-2018. All Rights Reserved.
+#
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at
+#
+#     http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
+#
+# %CopyrightEnd%
+#
+#
+# For an outline of how this all_SUITE_data stuff works, see the
+# make file ../../ssl/test/Makefile.
+#
+include $(ERL_TOP)/make/target.mk
+include $(ERL_TOP)/make/$(TARGET)/otp.mk
+
+# ----------------------------------------------------
+# Application version
+# ----------------------------------------------------
+include ../vsn.mk
+VSN = $(TFTP_VSN)
+
+
+# ----------------------------------------------------
+# Release directory specification
+# ----------------------------------------------------
+RELSYSDIR = $(RELEASE_PATH)/lib/$(APPLICATION)-$(VSN)
+
+
+# ----------------------------------------------------
+# Target Specs
+# ----------------------------------------------------
+INCLUDES = -I. \
+	-I$(ERL_TOP)/lib/tftp/src
+
+CP = cp
+
+ifeq ($(TESTROOT_DIR),)
+TESTROOT_DIR = /ldisk/tests/$(USER)/tftp
+endif
+
+ifeq ($(TFTP_DATA_DIR),)
+TFTP_DATA_DIR = $(TESTROOT_DIR)/data_dir
+endif
+
+ifeq ($(TFTP_PRIV_DIR),)
+TFTP_PRIV_DIR = $(TESTROOT_DIR)/priv_dir
+endif
+
+TFTP_FLAGS = -Dtftp__data_dir='"$(TFTP_DATA_DIR)"'       \
+              -Dtftp_priv_dir='"$(TFTP_PRIV_DIR)"'
+
+
+### 
+### test suite debug flags
+### 
+ifeq ($(TFTP_DEBUG_CLIENT),)
+  TFTP_DEBUG_CLIENT = y
+endif
+
+ifeq ($(TFTP_DEBUG_CLIENT),)
+  TFTP_FLAGS += -Dtftp_debug_client
+endif
+
+ifeq ($(TFTP_TRACE_CLIENT),)
+  TFTP_DEBUG_CLIENT = y
+endif
+
+ifeq ($(TFTP_TRACE_CLIENT),y)
+  TFTP_FLAGS += -Dtftp_trace_client
+endif
+
+ifneq ($(TFTP_DEBUG),)
+  TFTP_DEBUG = s
+endif
+
+ifeq ($(TFTP_DEBUG),l)
+  TFTP_FLAGS += -Dtftp_log
+endif
+
+ifeq ($(TFTP_DEBUG),d)
+  TFTP_FLAGS += -Dtftp_debug -Dtftp_log
+endif
+
+
+TFTP_FLAGS += -pa ../tftp/ebin
+
+TFTP_ROOT = ../tftp
+
+MODULES =                 		\
+	tftp_SUITE 	  		\
+	tftp_test_lib
+
+
+EBIN = .
+
+HRL_FILES = \
+	../src/tftp.hrl \
+	tftp_test_lib.hrl
+
+ERL_FILES = $(MODULES:%=%.erl)
+
+SOURCE = $(ERL_FILES) $(HRL_FILES) 
+
+TARGET_FILES = $(MODULES:%=$(EBIN)/%.$(EMULATOR))
+
+TFTP_SPECS = tftp.spec tftp_bench.spec
+COVER_FILE = tftp.cover
+TFTP_FILES = tftp.config $(TFTP_SPECS)
+
+
+TFTP_DATADIRS   = tftp_SUITE_data  
+
+DATADIRS     = $(TFTP_DATADIRS)
+
+EMAKEFILE  = Emakefile
+MAKE_EMAKE = $(wildcard $(ERL_TOP)/make/make_emakefile)
+
+ifeq ($(MAKE_EMAKE),)
+BUILDTARGET   = $(TARGET_FILES)
+RELTEST_FILES = $(COVER_FILE) $(TFTP_SPECS) $(SOURCE)
+else
+BUILDTARGET   = emakebuild
+RELTEST_FILES = $(EMAKEFILE) $(COVER_FILE) $(TFTP_SPECS) $(SOURCE)
+endif
+
+
+# ----------------------------------------------------
+# Release directory specification
+# ----------------------------------------------------
+
+RELTESTSYSDIR        = "$(RELEASE_PATH)/tftp_test"
+RELTESTSYSALLDATADIR = $(RELTESTSYSDIR)/all_SUITE_data
+RELTESTSYSBINDIR     = $(RELTESTSYSALLDATADIR)/bin
+
+
+# ----------------------------------------------------
+# FLAGS
+# The path to the test_server ebin dir is needed when 
+# running the target "targets".
+# ----------------------------------------------------
+ERL_COMPILE_FLAGS += \
+	$(INCLUDES) \
+	$(TFTP_FLAGS)
+
+# ----------------------------------------------------
+# Targets
+# erl -sname kalle -pa ../ebin
+# If you intend to run the test suite locally (private), then
+# there is some requirements:
+# 1) TFTP_PRIV_DIR must be created
+# ----------------------------------------------------
+
+tests debug opt: $(BUILDTARGET) 
+
+targets: $(TARGET_FILES)
+
+.PHONY: emakebuild
+
+emakebuild: $(EMAKEFILE)
+
+$(EMAKEFILE): 
+	$(MAKE_EMAKE) $(ERL_COMPILE_FLAGS) -o$(EBIN) '*_SUITE_make' | grep -v Warning > $(EMAKEFILE)
+	$(MAKE_EMAKE) $(ERL_COMPILE_FLAGS) -o$(EBIN) $(MODULES) | grep -v Warning >> $(EMAKEFILE)
+
+clean:
+	rm -f $(EMAKEFILE)
+	rm -f $(TARGET_FILES)
+	rm -f core *~
+
+docs:
+
+
+# ----------------------------------------------------
+# Release Target
+# ---------------------------------------------------- 
+include $(ERL_TOP)/make/otp_release_targets.mk
+
+release_spec: opt
+	$(INSTALL_DIR)  "$(RELSYSDIR)/test"
+	$(INSTALL_DATA) $(HRL_FILES)   $(ERL_FILES) "$(RELSYSDIR)/test"
+	$(INSTALL_DATA) $(TFTP_FILES) "$(RELSYSDIR)/test"
+	@for d in $(DATADIRS); do \
+            echo "installing data dir $$d"; \
+            if test -f $$d/TAR.exclude; then \
+                echo $$d/TAR.exclude2 > $$d/TAR.exclude2; \
+                cat $$d/TAR.exclude >> $$d/TAR.exclude2; \
+                find $$d -name '*.contrib*'     >> $$d/TAR.exclude2; \
+                find $$d -name '*.keep*'        >> $$d/TAR.exclude2; \
+                find $$d -name '*.mkelem*'      >> $$d/TAR.exclude2; \
+                find $$d -name '*~'             >> $$d/TAR.exclude2; \
+                find $$d -name 'erl_crash.dump' >> $$d/TAR.exclude2; \
+                find $$d -name 'core'           >> $$d/TAR.exclude2; \
+                find $$d -name '.cmake.state'   >> $$d/TAR.exclude2; \
+                tar cfX - $$d/TAR.exclude2 $$d | (cd "$(RELSYSDIR)/test"; tar xf -); \
+            else \
+                tar cf - $$d | (cd "$(RELSYSDIR)/test"; tar xf -); \
+            fi; \
+        done
+
+release_tests_spec: opt
+	$(INSTALL_DIR) $(RELTESTSYSDIR)
+	$(INSTALL_DATA) $(RELTEST_FILES) $(RELTESTSYSDIR)
+	chmod -R u+w $(RELTESTSYSDIR)
+	tar chf - $(DATADIRS) | (cd $(RELTESTSYSDIR); tar xf -)
+	$(INSTALL_DIR) $(RELTESTSYSALLDATADIR)
+	$(INSTALL_DIR) $(RELTESTSYSBINDIR)
+	chmod -R +x $(RELTESTSYSBINDIR)
+	$(INSTALL_DIR) $(RELTESTSYSALLDATADIR)/win32/lib	
+
+release_docs_spec:
+
+info:
+	@echo "MAKE_EMAKE        = $(MAKE_EMAKE)"
+	@echo "EMAKEFILE         = $(EMAKEFILE)"
+	@echo "BUILDTARGET       = $(BUILDTARGET)"
+	@echo ""
+	@echo "MODULES           = $(MODULES)"
+	@echo "ERL_FILES         = $(ERL_FILES)"
+	@echo "SOURCE            = $(SOURCE)"
+	@echo "TARGET_FILES      = $(TARGET_FILES)"
+	@echo ""
+	@echo "TFTP_SPECS       = $(TFTP_SPECS)"
+	@echo "TFTP_FILES       = $(TFTP_FILES)"
+	@echo ""
+	@echo "RELEASE_PATH      = "$(RELEASE_PATH)""
+	@echo "RELSYSDIR         = "$(RELSYSDIR)""
+	@echo "RELTESTSYSDIR     = $(RELTESTSYSDIR)"
+	@echo "RELTESTSYSALLDATADIR = $(RELTESTSYSALLDATADIR)"
+	@echo "RELTESTSYSBINDIR     = $(RELTESTSYSBINDIR)"
+	@echo ""
+	@echo "DATADIRS          = $(DATADIRS)"
+	@echo "REL_DATADIRS      = $(REL_DATADIRS)"
+	@echo ""
+	@echo "TFTP_DATA_DIR    = $(TFTP_DATA_DIR)"
+	@echo "TFTP_PRIV_DIR    = $(TFTP_PRIV_DIR)"
+	@echo "TFTP_ROOT        = $(TFTP_ROOT)"
+	@echo "TFTP_FLAGS       = $(TFTP_FLAGS)"
+
+
diff --git a/lib/tftp/test/tftp.config b/lib/tftp/test/tftp.config
new file mode 100644
index 0000000000..2600237da9
--- /dev/null
+++ b/lib/tftp/test/tftp.config
@@ -0,0 +1 @@
+[].
\ No newline at end of file
diff --git a/lib/tftp/test/tftp.cover b/lib/tftp/test/tftp.cover
new file mode 100644
index 0000000000..22ef5d0dda
--- /dev/null
+++ b/lib/tftp/test/tftp.cover
@@ -0,0 +1,2 @@
+{incl_app,tftp,details}.
+
diff --git a/lib/tftp/test/tftp.spec b/lib/tftp/test/tftp.spec
new file mode 100644
index 0000000000..f3537bc652
--- /dev/null
+++ b/lib/tftp/test/tftp.spec
@@ -0,0 +1 @@
+{suites,"../tftp_test", all}.
diff --git a/lib/tftp/test/tftp_SUITE.erl b/lib/tftp/test/tftp_SUITE.erl
new file mode 100644
index 0000000000..a43fd51153
--- /dev/null
+++ b/lib/tftp/test/tftp_SUITE.erl
@@ -0,0 +1,949 @@
+%%
+%% %CopyrightBegin%
+%% 
+%% Copyright Ericsson AB 2006-2016. All Rights Reserved.
+%% 
+%% Licensed under the Apache License, Version 2.0 (the "License");
+%% you may not use this file except in compliance with the License.
+%% You may obtain a copy of the License at
+%%
+%%     http://www.apache.org/licenses/LICENSE-2.0
+%%
+%% Unless required by applicable law or agreed to in writing, software
+%% distributed under the License is distributed on an "AS IS" BASIS,
+%% WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+%% See the License for the specific language governing permissions and
+%% limitations under the License.
+%% 
+%% %CopyrightEnd%
+%%
+
+-module(tftp_SUITE).
+
+-compile(export_all).
+
+%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
+%% Includes and defines
+%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
+
+-include("tftp_test_lib.hrl").
+
+-define(START_DAEMON(Port, Options),
+        begin
+            {ok, Pid} = ?VERIFY({ok, _Pid}, tftp:start([{port, Port} | Options])),
+            if
+                Port == 0 ->
+                    {ok, ActualOptions} = ?IGNORE(tftp:info(Pid)),
+                    {value, {port, ActualPort}} =
+                        lists:keysearch(port, 1, ActualOptions),
+                    {ActualPort, Pid};
+                true ->
+                    {Port, Pid}
+            end
+        end).
+
+%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
+%% API
+%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
+
+t() -> 
+    tftp_test_lib:t([{?MODULE, all}]).
+
+t(Cases) ->
+    tftp_test_lib:t(Cases, default_config()).
+
+t(Cases, Config) ->
+    tftp_test_lib:t(Cases, Config).
+
+default_config() ->
+    [].
+
+%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
+%% Test server callbacks
+%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
+
+init_per_testcase(Case, Config) ->
+    tftp_test_lib:init_per_testcase(Case, Config).
+
+end_per_testcase(Case, Config) when is_list(Config) ->
+    tftp_test_lib:end_per_testcase(Case, Config).
+
+%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
+%% Top test case
+%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
+
+suite() -> [{ct_hooks,[ts_install_cth]}].
+
+all() -> 
+    [simple, extra, reuse_connection, resend_client,
+     resend_server, large_file].
+
+groups() -> 
+    [].
+
+init_per_suite(Config) ->
+    Config.
+
+end_per_suite(_Config) ->
+    ok.
+
+init_per_group(_GroupName, Config) ->
+    Config.
+
+end_per_group(_GroupName, Config) ->
+    Config.
+
+
+%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
+%% Simple
+%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
+
+simple(doc) ->
+    ["Start the daemon and perform simple a read and write."];
+simple(suite) ->
+    [];
+simple(Config) when is_list(Config) ->
+    ?VERIFY(ok, application:start(tftp)),
+
+    {Port, DaemonPid} = ?IGNORE(?START_DAEMON(0, [{debug, brief}])),
+
+    %% Read fail
+    RemoteFilename = "tftp_temporary_remote_test_file.txt",
+    LocalFilename = "tftp_temporary_local_test_file.txt",
+    Blob = list_to_binary(lists:duplicate(2000, $1)),
+    %% Blob = <<"Some file contents\n">>,
+    Size = size(Blob),
+    ?IGNORE(file:delete(RemoteFilename)),
+    ?VERIFY({error, {client_open, enoent, _}},
+            tftp:read_file(RemoteFilename, binary, [{port, Port}])),
+    
+    %% Write and read
+    ?VERIFY({ok, Size}, tftp:write_file(RemoteFilename, Blob, [{port, Port}])),
+    ?VERIFY({ok, Blob}, tftp:read_file(RemoteFilename, binary, [{port, Port}])),
+    ?IGNORE(file:delete(LocalFilename)),
+    ?VERIFY({ok, Size}, tftp:read_file(RemoteFilename, LocalFilename, [{port, Port}])),
+
+    %% Cleanup
+    unlink(DaemonPid),
+    exit(DaemonPid, kill),
+    ?VERIFY(ok, file:delete(LocalFilename)),
+    ?VERIFY(ok, file:delete(RemoteFilename)),
+    ?VERIFY(ok, application:stop(tftp)),
+    ok.
+
+%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
+%% Extra
+%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
+
+extra(doc) ->
+    ["Verify new stuff for IS 1.2."];
+extra(suite) ->
+    [];
+extra(Config) when is_list(Config) ->
+    ?VERIFY({'EXIT', {badarg,{fake_key, fake_flag}}},
+            tftp:start([{port, 0}, {fake_key, fake_flag}])),
+
+    {Port, DaemonPid} = ?IGNORE(?START_DAEMON(0, [{debug, brief}])),
+    
+    RemoteFilename = "tftp_extra_temporary_remote_test_file.txt",
+    LocalFilename = "tftp_extra_temporary_local_test_file.txt",
+    Blob = <<"Some file contents\n">>,
+    Size = size(Blob),
+    Host = "127.0.0.1",
+    Peer = {inet, Host, Port},
+    Generic =
+        [
+         {state,   []},
+         {prepare, fun extra_prepare/6},
+         {open,    fun extra_open/6},
+         {read,    fun extra_read/1},
+         {write,   fun extra_write/2},
+         {abort,   fun extra_abort/3 }
+        ],
+    Options = [{host, Host},
+               {port, Port},
+               %%{ debug,all},
+               {callback, {".*", tftp_test_lib, Generic}}],
+    ?VERIFY(ok, file:write_file(LocalFilename, Blob)),
+    ?VERIFY({ok, [{count, Size}, Peer]},
+            tftp:write_file(RemoteFilename, LocalFilename, Options)),
+    ?VERIFY(ok, file:delete(LocalFilename)),
+    
+    ?VERIFY({ok,[{bin, Blob}, Peer]}, 
+            tftp:read_file(RemoteFilename, LocalFilename, Options)),
+
+    %% Cleanup
+    unlink(DaemonPid),
+    exit(DaemonPid, kill),
+    ?VERIFY(ok, file:delete(LocalFilename)),
+    ?VERIFY(ok, file:delete(RemoteFilename)),
+    ok.
+
+-record(extra_state,  {file, blksize, count, acc, peer}).
+
+%%-------------------------------------------------------------------
+%% Prepare
+%%-------------------------------------------------------------------
+
+extra_prepare(Peer, Access, LocalFilename, Mode, SuggestedOptions, []) ->
+    %% Client side
+    BlkSize = list_to_integer(tftp_test_lib:lookup_option("blksize", "512", SuggestedOptions)),
+    State = #extra_state{blksize = BlkSize, peer = Peer},
+    extra_open(Peer, Access, LocalFilename, Mode, SuggestedOptions, State),
+    {ok, SuggestedOptions, State};
+extra_prepare(_Peer, _Access, _Bin, _Mode, _SuggestedOptions, _Initial) ->
+    {error, {undef, "Illegal callback options."}}.
+
+%%-------------------------------------------------------------------
+%% Open
+%%-------------------------------------------------------------------
+
+extra_open(Peer, Access, LocalFilename, Mode, SuggestedOptions, []) ->
+    %% Server side
+    case extra_prepare(Peer, Access, LocalFilename, Mode, SuggestedOptions, []) of
+        {ok, AcceptedOptions, []} ->
+            BlkSize = list_to_integer(tftp_test_lib:lookup_option("blksize", "512", AcceptedOptions)),
+            State = #extra_state{blksize = BlkSize, peer = Peer},
+            extra_open(Peer, Access, LocalFilename, Mode, AcceptedOptions, State);
+        {error, {Code, Text}} ->
+            {error, {Code, Text}}
+    end;
+extra_open(_Peer, Access, LocalFilename, _Mode, NegotiatedOptions, #extra_state{} = State) ->
+    {File, Acc} =
+        case Access of
+            read ->
+                if
+                    is_binary(LocalFilename) ->
+                        {undefined, LocalFilename};
+                    is_list(LocalFilename) ->
+                        {ok, Bin} = file:read_file(LocalFilename),
+                        {LocalFilename, Bin}
+            end;
+            write -> 
+                {LocalFilename, []}
+        end,
+    %% Both sides
+    State2 = State#extra_state{file = File, acc = Acc, count = 0},
+    {ok, NegotiatedOptions, State2}.
+
+%%-------------------------------------------------------------------
+%% Read
+%%-------------------------------------------------------------------
+
+extra_read(#extra_state{acc = Bin} = State) when is_binary(Bin) ->
+    BlkSize = State#extra_state.blksize,
+    Count = State#extra_state.count + size(Bin),
+    if
+        size(Bin) >= BlkSize ->
+            <<Block:BlkSize/binary, Bin2/binary>> = Bin,
+            State2 = State#extra_state{acc = Bin2, count = Count},
+            {more, Block, State2};
+        size(Bin) < BlkSize ->
+            Res = [{count, Count}, State#extra_state.peer],
+            {last, Bin, Res}
+    end.
+
+%%-------------------------------------------------------------------
+%% Write
+%%-------------------------------------------------------------------
+
+extra_write(Bin, #extra_state{acc = List} = State) when is_binary(Bin), is_list(List) ->
+    Size = size(Bin),
+    BlkSize = State#extra_state.blksize,
+    if
+        Size == BlkSize ->
+            {more, State#extra_state{acc = [Bin | List]}};
+        Size < BlkSize ->
+            Bin2 = list_to_binary(lists:reverse([Bin | List])),
+            Res = [{bin,  Bin2}, State#extra_state.peer],
+            file:write_file(State#extra_state.file, Bin2),
+            {last, Res}
+    end.
+
+%%-------------------------------------------------------------------
+%% Abort
+%%-------------------------------------------------------------------
+
+extra_abort(_Code, _Text, #extra_state{}) ->
+    ok.
+
+%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
+%% Re-send client
+%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
+
+resend_client(doc) ->
+    ["Verify that the server behaves correctly when the client re-sends packets."];
+resend_client(suite) ->
+    [];
+resend_client(Config) when is_list(Config) ->
+    Host = {127, 0, 0, 1},
+    {Port, DaemonPid} = ?IGNORE(?START_DAEMON(0, [{debug, all}])),
+
+    ?VERIFY(ok, resend_read_client(Host, Port, 10)),
+    ?VERIFY(ok, resend_read_client(Host, Port, 512)),
+    ?VERIFY(ok, resend_read_client(Host, Port, 1025)),
+
+    ?VERIFY(ok, resend_write_client(Host, Port, 10)),
+    ?VERIFY(ok, resend_write_client(Host, Port, 512)),
+    ?VERIFY(ok, resend_write_client(Host, Port, 1025)),
+    
+    %% Cleanup
+    unlink(DaemonPid),
+    exit(DaemonPid, kill),
+    ok.
+
+resend_read_client(Host, Port, BlkSize) ->
+    RemoteFilename = "tftp_resend_read_client.tmp",
+    Block1 = lists:duplicate(BlkSize, $1),
+    Block2 = lists:duplicate(BlkSize, $2),
+    Block3 = lists:duplicate(BlkSize, $3),
+    Block4 = lists:duplicate(BlkSize, $4),
+    Block5 = lists:duplicate(BlkSize, $5),
+    Blocks = [Block1, Block2, Block3, Block4, Block5],
+    Blob = list_to_binary(Blocks),
+    ?VERIFY(ok, file:write_file(RemoteFilename, Blob)),
+
+    Timeout = timer:seconds(3),
+    ?VERIFY(timeout, recv(0)),
+
+    %% Open socket
+    {ok, Socket} = ?VERIFY({ok, _}, gen_udp:open(0, [binary, {reuseaddr, true}, {active, true}])),
+
+    ReadList = [0, 1, RemoteFilename, 0, "octet", 0],
+    Data1Bin = list_to_binary([0, 3, 0, 1 | Block1]),
+    NewPort =
+        if
+            BlkSize =:= 512 ->
+                %% Send READ
+                ReadBin = list_to_binary(ReadList),
+                ?VERIFY(ok, gen_udp:send(Socket, Host, Port, ReadBin)),
+
+                %% Sleep a while in order to provoke the server to re-send the packet
+                timer:sleep(Timeout + timer:seconds(1)),
+
+                %% Recv DATA #1 (the packet that the server think that we have lost)
+                {udp, _, _, NewPort0, _} = ?VERIFY({udp, Socket, Host, _, Data1Bin}, recv(Timeout)),
+                NewPort0;
+            true ->
+                %% Send READ
+                BlkSizeList = integer_to_list(BlkSize),
+                Options = ["blksize", 0, BlkSizeList, 0],
+                ReadBin = list_to_binary([ReadList | Options]),
+                ?VERIFY(ok, gen_udp:send(Socket, Host, Port, ReadBin)),
+
+                %% Recv OACK
+                OptionAckBin = list_to_binary([0, 6 | Options]),
+                {udp, _, _, NewPort0, _} = ?VERIFY({udp, Socket, Host, _, OptionAckBin}, recv(Timeout)),
+
+                %% Send ACK #0
+                Ack0Bin = <<0, 4, 0, 0>>,
+                ?VERIFY(ok, gen_udp:send(Socket, Host, NewPort0, Ack0Bin)),
+
+                %% Send ACK #0 AGAIN (pretend that we timed out)
+                timer:sleep(timer:seconds(1)),
+                ?VERIFY(ok, gen_udp:send(Socket, Host, NewPort0, Ack0Bin)),
+
+                %% Recv DATA #1 (the packet that the server think that we have lost)
+                ?VERIFY({udp, Socket, Host, NewPort0, Data1Bin}, recv(Timeout)),
+                NewPort0
+        end,
+
+    %% Recv DATA #1 AGAIN (the re-sent package)
+    ?VERIFY({udp, Socket, Host, NewPort, Data1Bin}, recv(Timeout)),
+
+    %% Send ACK #1
+    Ack1Bin = <<0, 4, 0, 1>>,
+    ?VERIFY(ok, gen_udp:send(Socket, Host, NewPort, Ack1Bin)),
+
+    %% Recv DATA #2
+    Data2Bin = list_to_binary([0, 3, 0, 2 | Block2]),
+    ?VERIFY({udp, Socket, Host, NewPort, Data2Bin}, recv(Timeout)),
+
+    %% Send ACK #2
+    Ack2Bin = <<0, 4, 0, 2>>,
+    ?VERIFY(ok, gen_udp:send(Socket, Host, NewPort, Ack2Bin)),
+
+    %% Recv DATA #3
+    Data3Bin = list_to_binary([0, 3, 0, 3 | Block3]),
+    ?VERIFY({udp, Socket, Host, NewPort, Data3Bin}, recv(Timeout)),
+
+    %% Send ACK #3
+    Ack3Bin = <<0, 4, 0, 3>>,
+    ?VERIFY(ok, gen_udp:send(Socket, Host, NewPort, Ack3Bin)),
+
+    %% Send ACK #3 AGAIN (pretend that we timed out)
+    timer:sleep(timer:seconds(1)),
+    ?VERIFY(ok, gen_udp:send(Socket, Host, NewPort, Ack3Bin)),
+
+    %% Recv DATA #4 (the packet that the server think that we have lost)
+    Data4Bin = list_to_binary([0, 3, 0, 4 | Block4]),
+    ?VERIFY({udp, Socket, Host, NewPort, Data4Bin}, recv(Timeout)),
+
+    %% Recv DATA #4 AGAIN (the re-sent package)
+    ?VERIFY({udp, Socket, Host, NewPort, Data4Bin}, recv(Timeout)),
+
+    %% Send ACK #2 which is out of range
+    ?VERIFY(ok, gen_udp:send(Socket, Host, NewPort, Ack2Bin)),
+
+    %% Send ACK #4
+    Ack4Bin = <<0, 4, 0, 4>>,
+    ?VERIFY(ok, gen_udp:send(Socket, Host, NewPort, Ack4Bin)),
+
+    %% Recv DATA #5
+    Data5Bin = list_to_binary([0, 3, 0, 5 | Block5]),
+    ?VERIFY({udp, Socket, Host, NewPort, Data5Bin}, recv(Timeout)),
+
+    %% Send ACK #5
+    Ack5Bin = <<0, 4, 0, 5>>,
+    ?VERIFY(ok, gen_udp:send(Socket, Host, NewPort, Ack5Bin)),
+
+    %% Close socket
+    ?VERIFY(ok, gen_udp:close(Socket)),
+
+    ?VERIFY(timeout, recv(Timeout)),
+    ?VERIFY(ok, file:delete(RemoteFilename)),
+    ok.
+
+resend_write_client(Host, Port, BlkSize) ->
+    RemoteFilename = "tftp_resend_write_client.tmp",
+    Block1 = lists:duplicate(BlkSize, $1),
+    Block2 = lists:duplicate(BlkSize, $2),
+    Block3 = lists:duplicate(BlkSize, $3),
+    Block4 = lists:duplicate(BlkSize, $4),
+    Block5 = lists:duplicate(BlkSize, $5),
+    Blocks = [Block1, Block2, Block3, Block4, Block5],
+    Blob = list_to_binary(Blocks),
+    ?IGNORE(file:delete(RemoteFilename)),
+    ?VERIFY({error, enoent}, file:read_file(RemoteFilename)),
+
+    Timeout = timer:seconds(3),
+    ?VERIFY(timeout, recv(0)),
+
+    %% Open socket
+    {ok, Socket} = ?VERIFY({ok, _}, gen_udp:open(0, [binary, {reuseaddr, true}, {active, true}])),
+
+    WriteList = [0, 2, RemoteFilename, 0, "octet", 0],
+    NewPort =
+        if
+            BlkSize =:= 512 ->
+                %% Send WRITE
+                WriteBin = list_to_binary(WriteList),
+                ?VERIFY(ok,  gen_udp:send(Socket, Host, Port, WriteBin)),
+
+                %% Sleep a while in order to provoke the server to re-send the packet
+                timer:sleep(Timeout + timer:seconds(1)),
+
+                %% Recv ACK #0 (the packet that the server think that we have lost)
+                Ack0Bin = <<0, 4, 0, 0>>,
+                ?VERIFY({udp, Socket, Host, _, Ack0Bin}, recv(Timeout)),
+
+                %% Recv ACK #0  AGAIN (the re-sent package)
+                {udp, _, _, NewPort0, _} = ?VERIFY({udp, Socket, Host, _, Ack0Bin}, recv(Timeout)),
+                NewPort0;
+            true ->
+                %% Send WRITE
+                BlkSizeList = integer_to_list(BlkSize),
+                WriteBin = list_to_binary([WriteList, "blksize", 0, BlkSizeList, 0]),
+                ?VERIFY(ok,  gen_udp:send(Socket, Host, Port, WriteBin)),
+
+                %% Sleep a while in order to provoke the server to re-send the packet
+                timer:sleep(timer:seconds(1)),
+
+                %% Recv OACK (the packet that the server think that we have lost)
+                OptionAckBin = list_to_binary([0, 6, "blksize",0, BlkSizeList, 0]),
+                ?VERIFY({udp, Socket, Host, _, OptionAckBin}, recv(Timeout)),
+                
+                %% Recv OACK AGAIN (the re-sent package)
+                {udp, _, _, NewPort0, _} = ?VERIFY({udp, Socket, Host, _, OptionAckBin}, recv(Timeout)),
+                NewPort0
+        end,
+
+    %% Send DATA #1
+    Data1Bin = list_to_binary([0, 3, 0, 1 | Block1]),
+    ?VERIFY(ok, gen_udp:send(Socket, Host, NewPort, Data1Bin)),
+
+    %% Recv ACK #1 
+    Ack1Bin = <<0, 4, 0, 1>>,
+    ?VERIFY({udp, Socket, Host, NewPort, Ack1Bin}, recv(Timeout)),
+
+    %% Send DATA #2
+    Data2Bin = list_to_binary([0, 3, 0, 2 | Block2]),
+    ?VERIFY(ok, gen_udp:send(Socket, Host, NewPort, Data2Bin)),
+
+    %% Recv ACK #2
+    Ack2Bin = <<0, 4, 0, 2>>,
+    ?VERIFY({udp, Socket, Host, NewPort, Ack2Bin}, recv(Timeout)),
+
+    %% Send DATA #3
+    Data3Bin = list_to_binary([0, 3, 0, 3 | Block3]),
+    ?VERIFY(ok, gen_udp:send(Socket, Host, NewPort, Data3Bin)),
+
+    %% Recv ACK #3
+    Ack3Bin = <<0, 4, 0, 3>>,
+    ?VERIFY({udp, Socket, Host, NewPort, Ack3Bin}, recv(Timeout)),
+
+    %% Send DATA #3 AGAIN (pretend that we timed out)
+    timer:sleep(timer:seconds(1)),
+    ?VERIFY(ok, gen_udp:send(Socket, Host, NewPort, Data3Bin)),
+
+    %% Recv ACK #3 AGAIN (the packet that the server think that we have lost)
+    ?VERIFY({udp, Socket, Host, NewPort, Ack3Bin}, recv(Timeout)),
+
+    %% Send DATA #2 which is out of range
+    ?VERIFY(ok, gen_udp:send(Socket, Host, NewPort, Data2Bin)),
+
+    %% Send DATA #4
+    Data4Bin = list_to_binary([0, 3, 0, 4 | Block4]),
+    ?VERIFY(ok, gen_udp:send(Socket, Host, NewPort, Data4Bin)),
+
+    %% Recv ACK #4
+    Ack4Bin = <<0, 4, 0, 4>>,
+    ?VERIFY({udp, Socket, Host, NewPort, Ack4Bin}, recv(Timeout)),
+
+    %% Send DATA #5
+    Data5Bin = list_to_binary([0, 3, 0, 5 | Block5]),
+    ?VERIFY(ok, gen_udp:send(Socket, Host, NewPort, Data5Bin)),
+
+    %% Recv ACK #5
+    Ack5Bin = <<0, 4, 0, 5>>,
+    ?VERIFY({udp, Socket, Host, NewPort, Ack5Bin}, recv(Timeout)),
+
+    %% Close socket
+    ?VERIFY(ok, gen_udp:close(Socket)),
+
+    ?VERIFY(timeout, recv(Timeout)),
+    ?VERIFY({ok, Blob}, file:read_file(RemoteFilename)),
+    ?VERIFY(ok, file:delete(RemoteFilename)),
+    ok.
+
+%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
+%% Re-send server
+%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
+
+resend_server(doc) ->
+    ["Verify that the server behaves correctly when the server re-sends packets."];
+resend_server(suite) ->
+    [];
+resend_server(Config) when is_list(Config) ->
+    Host = {127, 0, 0, 1},
+
+    ?VERIFY(ok, resend_read_server(Host, 10)),
+    ?VERIFY(ok, resend_read_server(Host, 512)),
+    ?VERIFY(ok, resend_read_server(Host, 1025)),
+    
+    ?VERIFY(ok, resend_write_server(Host, 10)),
+    ?VERIFY(ok, resend_write_server(Host, 512)),
+    ?VERIFY(ok, resend_write_server(Host, 1025)),
+    ok.
+
+resend_read_server(Host, BlkSize) ->
+    RemoteFilename = "tftp_resend_read_server.tmp",
+    Block1 = lists:duplicate(BlkSize, $1),
+    Block2 = lists:duplicate(BlkSize, $2),
+    Block3 = lists:duplicate(BlkSize, $3),
+    Block4 = lists:duplicate(BlkSize, $4),
+    Block5 = lists:duplicate(BlkSize, $5),
+    Block6 = [],
+    Blocks = [Block1, Block2, Block3, Block4, Block5, Block6],
+    Blob = list_to_binary(Blocks),
+
+    Timeout = timer:seconds(3),
+    ?VERIFY(timeout, recv(0)),
+
+    %% Open daemon socket
+    {ok, DaemonSocket} = ?VERIFY({ok, _}, gen_udp:open(0, [binary, {reuseaddr, true}, {active, true}])),
+    {ok, DaemonPort} = ?IGNORE(inet:port(DaemonSocket)),
+
+    %% Open server socket
+    {ok, ServerSocket} = ?VERIFY({ok, _}, gen_udp:open(0, [binary, {reuseaddr, true}, {active, true}])),
+    ?IGNORE(inet:port(ServerSocket)),
+
+    %% Prepare client process
+    ReplyTo = self(),
+    ClientFun =
+        fun(Extra) ->
+                Options = [{port, DaemonPort}, {debug, brief}] ++ Extra,
+                Res = ?VERIFY({ok, Blob}, tftp:read_file(RemoteFilename, binary, Options)),
+                ReplyTo ! {self(), {tftp_client_reply, Res}},
+                exit(normal)
+        end,
+
+    ReadList = [0, 1, RemoteFilename, 0, "octet", 0],
+    Data1Bin = list_to_binary([0, 3, 0, 1 | Block1]),
+    Ack1Bin = <<0, 4, 0, 1>>,
+    {ClientPort, ClientPid} =
+        if
+            BlkSize =:= 512 ->
+                %% Start client process
+                ClientPid0 = spawn_link(fun() -> ClientFun([]) end),
+
+                %% Recv READ
+                ReadBin = list_to_binary(ReadList),
+                {udp, _, _, ClientPort0, _} = ?VERIFY({udp, DaemonSocket, Host, _, ReadBin}, recv(Timeout)),
+
+                %% Send DATA #1
+                ?VERIFY(ok,  gen_udp:send(ServerSocket, Host, ClientPort0, Data1Bin)),
+
+                %% Sleep a while in order to provoke the client to re-send the packet
+                timer:sleep(Timeout + timer:seconds(1)),
+
+                %% Recv ACK #1 (the packet that the server think that we have lost)
+                ?VERIFY({udp, ServerSocket, Host, ClientPort0, Ack1Bin}, recv(Timeout)),
+
+                %% Recv ACK #1 AGAIN (the re-sent package)
+                ?VERIFY({udp, ServerSocket, Host, _, Ack1Bin}, recv(Timeout)),
+                {ClientPort0, ClientPid0};
+            true ->
+                %% Start client process
+                BlkSizeList = integer_to_list(BlkSize),
+                ClientPid0 = spawn_link(fun() -> ClientFun([{"blksize", BlkSizeList}]) end),
+                
+                %% Recv READ
+                Options = ["blksize", 0, BlkSizeList, 0],
+                ReadBin = list_to_binary([ReadList | Options]),
+                {udp, _, _, ClientPort0, _} = ?VERIFY({udp, DaemonSocket, Host, _, ReadBin}, recv(Timeout)),
+
+                %% Send OACK
+                BlkSizeList = integer_to_list(BlkSize),
+                OptionAckBin = list_to_binary([0, 6, "blksize",0, BlkSizeList, 0]),
+                ?VERIFY(ok, gen_udp:send(ServerSocket, Host, ClientPort0, OptionAckBin)),
+
+                %% Sleep a while in order to provoke the client to re-send the packet
+                timer:sleep(Timeout + timer:seconds(1)),
+
+                %% Recv ACK #0 (the packet that the server think that we have lost)
+                Ack0Bin = <<0, 4, 0, 0>>,
+                ?VERIFY({udp, ServerSocket, Host, ClientPort0, Ack0Bin}, recv(Timeout)),
+
+                %% Recv ACK #0 AGAIN (the re-sent package)
+                ?VERIFY({udp, ServerSocket, Host, ClientPort0, Ack0Bin}, recv(Timeout)),
+
+                %% Send DATA #1
+                ?VERIFY(ok, gen_udp:send(ServerSocket, Host, ClientPort0, Data1Bin)),
+
+                %% Recv ACK #1
+                ?VERIFY({udp, ServerSocket, Host, _, Ack1Bin}, recv(Timeout)),
+                {ClientPort0, ClientPid0}
+        end,
+
+    %% Send DATA #2
+    Data2Bin = list_to_binary([0, 3, 0, 2 | Block2]),
+    ?VERIFY(ok, gen_udp:send(ServerSocket, Host, ClientPort, Data2Bin)),
+
+    %% Recv ACK #2
+    Ack2Bin = <<0, 4, 0, 2>>,
+    ?VERIFY({udp, ServerSocket, Host, ClientPort, Ack2Bin}, recv(Timeout)),
+
+    %% Send DATA #3
+    Data3Bin = list_to_binary([0, 3, 0, 3 | Block3]),
+    ?VERIFY(ok, gen_udp:send(ServerSocket, Host, ClientPort, Data3Bin)),
+
+    %% Recv ACK #3
+    Ack3Bin = <<0, 4, 0, 3>>,
+    ?VERIFY({udp, ServerSocket, Host, ClientPort, Ack3Bin}, recv(Timeout)),
+
+    %% Send DATA #3 AGAIN (pretend that we timed out)
+    timer:sleep(timer:seconds(1)),
+    ?VERIFY(ok, gen_udp:send(ServerSocket, Host, ClientPort, Data3Bin)),
+
+    %% Recv ACK #3 AGAIN (the packet that the server think that we have lost)
+    ?VERIFY({udp, ServerSocket, Host, ClientPort, Ack3Bin}, recv(Timeout)),
+
+    %% Send DATA #4
+    Data4Bin = list_to_binary([0, 3, 0, 4 | Block4]),
+    ?VERIFY(ok, gen_udp:send(ServerSocket, Host, ClientPort, Data4Bin)),
+
+    %% Recv ACK #4
+    Ack4Bin = <<0, 4, 0, 4>>,
+    ?VERIFY({udp, ServerSocket, Host, ClientPort, Ack4Bin}, recv(Timeout)),
+
+    %% Send DATA #3 which is out of range
+    ?VERIFY(ok, gen_udp:send(ServerSocket, Host, ClientPort, Data3Bin)),
+
+    %% Send DATA #5
+    Data5Bin = list_to_binary([0, 3, 0, 5 | Block5]),
+    ?VERIFY(ok, gen_udp:send(ServerSocket, Host, ClientPort, Data5Bin)),
+
+    %% Recv ACK #5
+    Ack5Bin = <<0, 4, 0, 5>>,
+    ?VERIFY({udp, ServerSocket, Host, ClientPort, Ack5Bin}, recv(Timeout)),
+
+    %% Send DATA #6
+    Data6Bin = list_to_binary([0, 3, 0, 6 | Block6]),
+    ?VERIFY(ok, gen_udp:send(ServerSocket, Host, ClientPort, Data6Bin)),
+
+    %% Close daemon and server sockets
+    ?VERIFY(ok, gen_udp:close(ServerSocket)),
+    ?VERIFY(ok, gen_udp:close(DaemonSocket)),
+
+    ?VERIFY({ClientPid, {tftp_client_reply, {ok, Blob}}}, recv(Timeout)),
+
+    ?VERIFY(timeout, recv(Timeout)),
+    ok.
+
+resend_write_server(Host, BlkSize) ->
+    RemoteFilename = "tftp_resend_write_server.tmp",
+    Block1 = lists:duplicate(BlkSize, $1),
+    Block2 = lists:duplicate(BlkSize, $2),
+    Block3 = lists:duplicate(BlkSize, $3),
+    Block4 = lists:duplicate(BlkSize, $4),
+    Block5 = lists:duplicate(BlkSize, $5),
+    Block6 = [],
+    Blocks = [Block1, Block2, Block3, Block4, Block5, Block6],
+    Blob = list_to_binary(Blocks),
+    Size = size(Blob),
+
+    Timeout = timer:seconds(3),
+    ?VERIFY(timeout, recv(0)),
+
+    %% Open daemon socket
+    {ok, DaemonSocket} = ?VERIFY({ok, _}, gen_udp:open(0, [binary, {reuseaddr, true}, {active, true}])),
+    {ok, DaemonPort} = ?IGNORE(inet:port(DaemonSocket)),
+
+    %% Open server socket
+    {ok, ServerSocket} = ?VERIFY({ok, _}, gen_udp:open(0, [binary, {reuseaddr, true}, {active, true}])),
+    ?IGNORE(inet:port(ServerSocket)),
+
+    %% Prepare client process
+    ReplyTo = self(),
+    ClientFun =
+        fun(Extra) ->
+                Options = [{port, DaemonPort}, {debug, brief}] ++ Extra,
+                Res = ?VERIFY({ok, Size}, tftp:write_file(RemoteFilename, Blob, Options)),
+                ReplyTo ! {self(), {tftp_client_reply, Res}},
+                exit(normal)
+        end,
+
+    WriteList = [0, 2, RemoteFilename, 0, "octet", 0],
+    Data1Bin = list_to_binary([0, 3, 0, 1 | Block1]),
+    {ClientPort, ClientPid} =
+        if
+            BlkSize =:= 512 ->
+                %% Start client process
+                ClientPid0 = spawn_link(fun() -> ClientFun([]) end),
+
+                %% Recv WRITE
+                WriteBin = list_to_binary(WriteList),
+                io:format("WriteBin ~p\n", [WriteBin]),
+                {udp, _, _, ClientPort0, _} = ?VERIFY({udp, DaemonSocket, Host, _, WriteBin}, recv(Timeout)),
+
+                %% Send ACK #1
+                Ack0Bin = <<0, 4, 0, 0>>,
+                ?VERIFY(ok,  gen_udp:send(ServerSocket, Host, ClientPort0, Ack0Bin)),
+
+                %% Sleep a while in order to provoke the client to re-send the packet
+                timer:sleep(Timeout + timer:seconds(1)),
+
+                %% Recv DATA #1 (the packet that the server think that we have lost)
+                ?VERIFY({udp, ServerSocket, Host, ClientPort0, Data1Bin}, recv(Timeout)),
+
+                %% Recv DATA #1 AGAIN (the re-sent package)
+                ?VERIFY({udp, ServerSocket, Host, _, Data1Bin}, recv(Timeout)),
+                {ClientPort0, ClientPid0};
+            true ->
+                %% Start client process
+                BlkSizeList = integer_to_list(BlkSize),
+                ClientPid0 = spawn_link(fun() -> ClientFun([{"blksize", BlkSizeList}]) end),
+                
+                %% Recv WRITE
+                Options = ["blksize", 0, BlkSizeList, 0],
+                WriteBin = list_to_binary([WriteList | Options]),
+                {udp, _, _, ClientPort0, _} = ?VERIFY({udp, DaemonSocket, Host, _, WriteBin}, recv(Timeout)),
+
+                %% Send OACK
+                BlkSizeList = integer_to_list(BlkSize),
+                OptionAckBin = list_to_binary([0, 6, "blksize",0, BlkSizeList, 0]),
+                ?VERIFY(ok, gen_udp:send(ServerSocket, Host, ClientPort0, OptionAckBin)),
+
+                %% Sleep a while in order to provoke the client to re-send the packet
+                timer:sleep(Timeout + timer:seconds(1)),
+
+                %% Recv DATA #1 (the packet that the server think that we have lost)
+                ?VERIFY({udp, ServerSocket, Host, ClientPort0, Data1Bin}, recv(Timeout)),
+
+                %% Recv DATA #1 AGAIN (the re-sent package)
+                ?VERIFY({udp, ServerSocket, Host, ClientPort0, Data1Bin}, recv(Timeout)),
+                {ClientPort0, ClientPid0}
+        end,
+
+    %% Send ACK #1
+    Ack1Bin = <<0, 4, 0, 1>>,
+    ?VERIFY(ok, gen_udp:send(ServerSocket, Host, ClientPort, Ack1Bin)),
+
+    %% Recv DATA #2
+    Data2Bin = list_to_binary([0, 3, 0, 2 | Block2]),
+    ?VERIFY({udp, ServerSocket, Host, ClientPort, Data2Bin}, recv(Timeout)),
+
+    %% Send ACK #2
+    Ack2Bin = <<0, 4, 0, 2>>,
+    ?VERIFY(ok, gen_udp:send(ServerSocket, Host, ClientPort, Ack2Bin)),
+
+    %% Recv DATA #3
+    Data3Bin = list_to_binary([0, 3, 0, 3 | Block3]),
+    ?VERIFY({udp, ServerSocket, Host, ClientPort, Data3Bin}, recv(Timeout)),
+
+    %% Send ACK #3
+    Ack3Bin = <<0, 4, 0, 3>>,
+    ?VERIFY(ok, gen_udp:send(ServerSocket, Host, ClientPort, Ack3Bin)),
+
+    %% Send ACK #3 AGAIN (pretend that we timed out)
+    timer:sleep(timer:seconds(1)),
+    ?VERIFY(ok, gen_udp:send(ServerSocket, Host, ClientPort, Ack3Bin)),
+
+    %% Recv DATA #4 (the packet that the server think that we have lost)
+    Data4Bin = list_to_binary([0, 3, 0, 4 | Block4]),
+    ?VERIFY({udp, ServerSocket, Host, ClientPort, Data4Bin}, recv(Timeout)),
+
+    %% Recv DATA #4 AGAIN (the re-sent package)
+    ?VERIFY({udp, ServerSocket, Host, ClientPort, Data4Bin}, recv(Timeout)),
+
+    %% Send ACK #4
+    Ack4Bin = <<0, 4, 0, 4>>,
+    ?VERIFY(ok, gen_udp:send(ServerSocket, Host, ClientPort, Ack4Bin)),
+
+    %% Recv DATA #5
+    Data5Bin = list_to_binary([0, 3, 0, 5 | Block5]),
+    ?VERIFY({udp, ServerSocket, Host, ClientPort, Data5Bin}, recv(Timeout)),
+
+    %% Send ACK #3 which is out of range
+    ?VERIFY(ok, gen_udp:send(ServerSocket, Host, ClientPort, Ack3Bin)),
+
+    %% Send ACK #5
+    Ack5Bin = <<0, 4, 0, 5>>,
+    ?VERIFY(ok, gen_udp:send(ServerSocket, Host, ClientPort, Ack5Bin)),
+
+    %% Recv DATA #6
+    Data6Bin = list_to_binary([0, 3, 0, 6 | Block6]),
+    ?VERIFY({udp, ServerSocket, Host, ClientPort, Data6Bin}, recv(Timeout)),
+
+    %% Send ACK #6
+    Ack6Bin = <<0, 4, 0, 6>>,
+    ?VERIFY(ok, gen_udp:send(ServerSocket, Host, ClientPort, Ack6Bin)),
+
+    %% Close daemon and server sockets
+    ?VERIFY(ok, gen_udp:close(ServerSocket)),
+    ?VERIFY(ok, gen_udp:close(DaemonSocket)),
+
+    ?VERIFY({ClientPid, {tftp_client_reply, {ok, Size}}}, recv(Timeout)),
+
+    ?VERIFY(timeout, recv(Timeout)),
+    ok.
+
+%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
+%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
+
+reuse_connection(doc) ->
+    ["Verify that the server can reuse an ongiong connection when same client resends request."];
+reuse_connection(suite) ->
+    [];
+reuse_connection(Config) when is_list(Config) ->
+    Host = {127, 0, 0, 1},
+    {Port, DaemonPid} = ?IGNORE(?START_DAEMON(0, [{debug, all}])),
+
+    RemoteFilename = "reuse_connection.tmp",
+    BlkSize = 512,
+    Block1 = lists:duplicate(BlkSize, $1),
+    Block2 = lists:duplicate(BlkSize div 2, $2),
+    Blocks = [Block1, Block2],
+    Blob = list_to_binary(Blocks),
+    ?VERIFY(ok, file:write_file(RemoteFilename, Blob)),
+    
+    Seconds = 3,
+    Timeout = timer:seconds(Seconds),
+    ?VERIFY(timeout, recv(0)),
+    
+    %% Open socket
+    {ok, Socket} = ?VERIFY({ok, _}, gen_udp:open(0, [binary, {reuseaddr, true}, {active, true}])),
+    
+    ReadList = [0, 1, RemoteFilename, 0, "octet", 0],
+    Data1Bin = list_to_binary([0, 3, 0, 1 | Block1]),
+    
+    %% Send READ
+    TimeoutList = integer_to_list(Seconds),
+    Options = ["timeout", 0, TimeoutList, 0],
+    ReadBin = list_to_binary([ReadList | Options]),
+    ?VERIFY(ok, gen_udp:send(Socket, Host, Port, ReadBin)),
+
+    %% Send yet another READ for same file
+    ?VERIFY(ok, gen_udp:send(Socket, Host, Port, ReadBin)),
+
+    %% Recv OACK
+    OptionAckBin = list_to_binary([0, 6 | Options]),
+    {udp, _, _, NewPort, _} = ?VERIFY({udp, Socket, Host, _, OptionAckBin}, recv(Timeout)),
+
+    %% Send ACK #0
+    Ack0Bin = <<0, 4, 0, 0>>,
+    ?VERIFY(ok, gen_udp:send(Socket, Host, NewPort, Ack0Bin)),
+
+    %% Recv DATA #1
+    ?VERIFY({udp, Socket, Host, NewPort, Data1Bin}, recv(Timeout)),
+
+    %% Send ACK #1
+    Ack1Bin = <<0, 4, 0, 1>>,
+    ?VERIFY(ok, gen_udp:send(Socket, Host, NewPort, Ack1Bin)),
+
+    %% Recv DATA #2
+    Data2Bin = list_to_binary([0, 3, 0, 2 | Block2]),
+    ?VERIFY({udp, Socket, Host, NewPort, Data2Bin}, recv(Timeout)),
+
+    %% Send ACK #2
+    Ack2Bin = <<0, 4, 0, 2>>,
+    ?VERIFY(ok, gen_udp:send(Socket, Host, NewPort, Ack2Bin)),
+
+    %% Close socket
+    ?VERIFY(ok, gen_udp:close(Socket)),
+
+    ?VERIFY(timeout, recv(Timeout)),
+    ?VERIFY(ok, file:delete(RemoteFilename)),
+
+    %% Cleanup
+    unlink(DaemonPid),
+    exit(DaemonPid, kill),
+    ok.
+
+%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
+%% Large file: transfer > 65535 blocks
+%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
+
+large_file(doc) ->
+    ["Start the daemon and test transfer of files greater than 32M."];
+large_file(suite) ->
+    [];
+large_file(Config) when is_list(Config) ->
+    ?VERIFY(ok, application:start(tftp)),
+
+    {Port, DaemonPid} = ?IGNORE(?START_DAEMON(0, [{debug, brief}])),
+
+    %% Read fail
+    RemoteFilename = "tftp_temporary_large_file_remote_test_file.txt",
+    LocalFilename = "tftp_temporary_large_file_local_test_file.txt",
+
+    {ok, FH} = file:open(LocalFilename, [write,exclusive]),
+    {ok, Size} = file:position(FH, {eof, 2*512*65535}),
+    ok = file:truncate(FH),
+    ?IGNORE(file:close(FH)),
+
+    %% Write and read
+    ?VERIFY({ok, Size}, tftp:write_file(RemoteFilename, LocalFilename, [{port, Port}])),
+    ?IGNORE(file:delete(LocalFilename)),
+    ?VERIFY({ok, Size}, tftp:read_file(RemoteFilename, LocalFilename, [{port, Port}])),
+
+    %% Cleanup
+    unlink(DaemonPid),
+    exit(DaemonPid, kill),
+    ?VERIFY(ok, file:delete(LocalFilename)),
+    ?VERIFY(ok, file:delete(RemoteFilename)),
+    ?VERIFY(ok, application:stop(tftp)),
+    ok.
+
+%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
+%% Goodies
+%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
+
+recv(Timeout) ->
+    receive
+        Msg ->
+            Msg
+    after Timeout ->
+            timeout
+    end.
diff --git a/lib/tftp/test/tftp_bench.spec b/lib/tftp/test/tftp_bench.spec
new file mode 100644
index 0000000000..43fa385c85
--- /dev/null
+++ b/lib/tftp/test/tftp_bench.spec
@@ -0,0 +1 @@
+{suites,"../tftp_test",[]}.
diff --git a/lib/tftp/test/tftp_test_lib.erl b/lib/tftp/test/tftp_test_lib.erl
new file mode 100644
index 0000000000..45386389cb
--- /dev/null
+++ b/lib/tftp/test/tftp_test_lib.erl
@@ -0,0 +1,308 @@
+%%
+%% %CopyrightBegin%
+%% 
+%% Copyright Ericsson AB 2007-2016. All Rights Reserved.
+%% 
+%% Licensed under the Apache License, Version 2.0 (the "License");
+%% you may not use this file except in compliance with the License.
+%% You may obtain a copy of the License at
+%%
+%%     http://www.apache.org/licenses/LICENSE-2.0
+%%
+%% Unless required by applicable law or agreed to in writing, software
+%% distributed under the License is distributed on an "AS IS" BASIS,
+%% WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+%% See the License for the specific language governing permissions and
+%% limitations under the License.
+%% 
+%% %CopyrightEnd%
+%%
+
+-module(tftp_test_lib).
+
+-compile(export_all).
+
+-include("tftp_test_lib.hrl").
+
+%%
+%% -----
+%%
+
+init_per_testcase(_Case, Config) when is_list(Config) ->
+    io:format("\n ", []),
+    ?IGNORE(application:stop(tftp)),   
+    Config.
+
+end_per_testcase(_Case, Config) when is_list(Config) ->
+    ?IGNORE(application:stop(tftp)),   
+    Config.
+
+%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
+%% Infrastructure for test suite
+%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
+
+error(Actual, Mod, Line) ->
+    (catch global:send(tftp_global_logger, {failed, Mod, Line})),
+    log("<ERROR> Bad result: ~p\n", [Actual], Mod, Line),
+    Label = lists:concat([Mod, "(", Line, ") unexpected result"]),
+    et:report_event(60, Mod, Mod, Label,
+			[{line, Mod, Line}, {error, Actual}]),
+    case global:whereis_name(tftp_test_case_sup) of
+	undefined -> 
+	    ignore;
+	Pid -> 
+	    Fail = #'REASON'{mod = Mod, line = Line, desc = Actual},
+	    Pid ! {fail, self(), Fail}
+    end,
+    Actual.
+
+log(Format, Args, Mod, Line) ->
+    case global:whereis_name(tftp_global_logger) of
+	undefined ->
+	    io:format(user, "~p(~p): " ++ Format, 
+		      [Mod, Line] ++ Args);
+	Pid ->
+	    io:format(Pid, "~p(~p): " ++ Format, 
+		      [Mod, Line] ++ Args)
+    end.
+
+default_config() ->
+    [].
+
+t() -> 
+    t([{?MODULE, all}]).
+
+t(Cases) ->
+    t(Cases, default_config()).
+
+t(Cases, Config) ->
+    process_flag(trap_exit, true),
+    Res = lists:flatten(do_test(Cases, Config)),
+    io:format("Res: ~p\n", [Res]),
+    display_result(Res),
+    Res.
+
+do_test({Mod, Fun}, Config) when is_atom(Mod), is_atom(Fun) ->
+    case catch apply(Mod, Fun, [suite]) of
+	[] ->
+	    io:format("Eval:   ~p:", [{Mod, Fun}]),
+	    Res = eval(Mod, Fun, Config),
+	    {R, _, _} = Res,
+	    io:format(" ~p\n", [R]),
+	    Res;
+
+	Cases when is_list(Cases) ->
+	    io:format("Expand: ~p ...\n", [{Mod, Fun}]),
+	    Map = fun(Case) when is_atom(Case)-> {Mod, Case};
+		     (Case) -> Case
+		  end,
+	    do_test(lists:map(Map, Cases), Config);
+
+        {req, _, {conf, Init, Cases, Finish}} ->
+	    case (catch apply(Mod, Init, [Config])) of
+		Conf when is_list(Conf) ->
+		    io:format("Expand: ~p ...\n", [{Mod, Fun}]),
+		    Map = fun(Case) when is_atom(Case)-> {Mod, Case};
+			     (Case) -> Case
+			  end,
+		    Res = do_test(lists:map(Map, Cases), Conf),
+		    (catch apply(Mod, Finish, [Conf])),
+		    Res;
+		    
+		{'EXIT', {skipped, Reason}} ->
+		    io:format(" => skipping: ~p\n", [Reason]),
+		    [{skipped, {Mod, Fun}, Reason}];
+		    
+		Error ->
+		    io:format(" => failed: ~p\n", [Error]),
+		    [{failed, {Mod, Fun}, Error}]
+	    end;
+		    
+        {'EXIT', {undef, _}} ->
+	    io:format("Undefined:   ~p\n", [{Mod, Fun}]),
+	    [{nyi, {Mod, Fun}, ok}];
+		    
+        Error ->
+	    io:format("Ignoring:   ~p: ~p\n", [{Mod, Fun}, Error]),
+	    [{failed, {Mod, Fun}, Error}]
+    end;
+do_test(Mod, Config) when is_atom(Mod) ->
+    Res = do_test({Mod, all}, Config),
+    Res;
+do_test(Cases, Config) when is_list(Cases) ->
+    [do_test(Case, Config) || Case <- Cases];
+do_test(Bad, _Config) ->
+    [{badarg, Bad, ok}].
+
+eval(Mod, Fun, Config) ->
+    TestCase = {?MODULE, Mod, Fun},
+    Label = lists:concat(["TEST CASE: ", Fun]),
+    et:report_event(40, ?MODULE, Mod, Label ++ " started",
+			[TestCase, Config]),
+    global:register_name(tftp_test_case_sup, self()),
+    Flag = process_flag(trap_exit, true),
+    Config2 = Mod:init_per_testcase(Fun, Config),
+    Pid = spawn_link(?MODULE, do_eval, [self(), Mod, Fun, Config2]),
+    R = wait_for_evaluator(Pid, Mod, Fun, Config2, []),
+    Mod:end_per_testcase(Fun, Config2),
+    global:unregister_name(tftp_test_case_sup),
+    process_flag(trap_exit, Flag),
+    R.
+
+wait_for_evaluator(Pid, Mod, Fun, Config, Errors) ->
+    TestCase = {?MODULE, Mod, Fun},
+    Label = lists:concat(["TEST CASE: ", Fun]),
+    receive
+	{done, Pid, ok} when Errors == [] ->
+	    et:report_event(40, Mod, ?MODULE, Label ++ " ok",
+				[TestCase, Config]),
+	    {ok, {Mod, Fun}, Errors};
+	{done, Pid, {ok, _}} when Errors == [] ->
+	    et:report_event(40, Mod, ?MODULE, Label ++ " ok",
+				[TestCase, Config]),
+	    {ok, {Mod, Fun}, Errors};
+	{done, Pid, Fail} ->
+	    et:report_event(20, Mod, ?MODULE, Label ++ " failed",
+				[TestCase, Config, {return, Fail}, Errors]),
+	    {failed, {Mod,Fun}, Fail};
+	{'EXIT', Pid, {skipped, Reason}} -> 
+	    et:report_event(20, Mod, ?MODULE, Label ++ " skipped",
+				[TestCase, Config, {skipped, Reason}]),
+	    {skipped, {Mod, Fun}, Errors};
+	{'EXIT', Pid, Reason} -> 
+	    et:report_event(20, Mod, ?MODULE, Label ++ " crashed",
+				[TestCase, Config, {'EXIT', Reason}]),
+	    {crashed, {Mod, Fun}, [{'EXIT', Reason} | Errors]};
+	{fail, Pid, Reason} ->
+	    wait_for_evaluator(Pid, Mod, Fun, Config, Errors ++ [Reason])
+    end.
+
+do_eval(ReplyTo, Mod, Fun, Config) ->
+    case (catch apply(Mod, Fun, [Config])) of
+	{'EXIT', {skipped, Reason}} ->
+	    ReplyTo ! {'EXIT', self(), {skipped, Reason}};
+	Other ->
+	    ReplyTo ! {done, self(), Other}
+    end,
+    unlink(ReplyTo),
+    exit(shutdown).
+
+display_result([]) ->    
+    io:format("OK\n", []);
+display_result(Res) when is_list(Res) ->
+    Ok      = [MF || {ok, MF, _}  <- Res],
+    Nyi     = [MF || {nyi, MF, _} <- Res],
+    Skipped = [{MF, Reason} || {skipped, MF, Reason} <- Res],
+    Failed  = [{MF, Reason} || {failed, MF, Reason} <- Res],
+    Crashed = [{MF, Reason} || {crashed, MF, Reason} <- Res],
+    display_summary(Ok, Nyi, Skipped, Failed, Crashed),
+    display_skipped(Skipped),
+    display_failed(Failed),
+    display_crashed(Crashed).
+
+display_summary(Ok, Nyi, Skipped, Failed, Crashed) ->
+    io:format("\nTest case summary:\n", []),
+    display_summary(Ok,      "successful"),
+    display_summary(Nyi,     "not yet implemented"),
+    display_summary(Skipped, "skipped"),
+    display_summary(Failed,  "failed"),
+    display_summary(Crashed, "crashed"),
+    io:format("\n", []).
+   
+display_summary(Res, Info) ->
+    io:format("  ~w test cases ~s\n", [length(Res), Info]).
+    
+display_skipped([]) ->
+    ok;
+display_skipped(Skipped) ->
+    io:format("Skipped test cases:\n", []),
+    F = fun({MF, Reason}) -> io:format("  ~p => ~p\n", [MF, Reason]) end,
+    lists:foreach(F, Skipped),
+    io:format("\n", []).
+    
+
+display_failed([]) ->
+    ok;
+display_failed(Failed) ->
+    io:format("Failed test cases:\n", []),
+    F = fun({MF, Reason}) -> io:format("  ~p => ~p\n", [MF, Reason]) end,
+    lists:foreach(F, Failed),
+    io:format("\n", []).
+
+display_crashed([]) ->
+    ok;
+display_crashed(Crashed) ->
+    io:format("Crashed test cases:\n", []),
+    F = fun({MF, Reason}) -> io:format("  ~p => ~p\n", [MF, Reason]) end,
+    lists:foreach(F, Crashed),
+    io:format("\n", []).
+
+%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
+%% generic callback
+%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
+
+-record(generic_state, {state, prepare, open, read, write, abort}).
+
+prepare(Peer, Access, LocalFilename, Mode, SuggestedOptions, Initial) when is_list(Initial) ->
+    State   = lookup_option(state,   mandatory, Initial),
+    Prepare = lookup_option(prepare, mandatory, Initial),
+    Open    = lookup_option(open,    mandatory, Initial),
+    Read    = lookup_option(read,    mandatory, Initial),
+    Write   = lookup_option(write,   mandatory, Initial),
+    Abort   = lookup_option(abort,   mandatory, Initial),
+    case Prepare(Peer, Access, LocalFilename, Mode, SuggestedOptions, State) of
+	{ok, AcceptedOptions, NewState} ->
+	    {ok,
+	     AcceptedOptions,
+	     #generic_state{state   = NewState,
+			    prepare = Prepare,
+			    open    = Open,
+			    read    = Read,
+			    write   = Write,
+			    abort   = Abort}};
+	Other ->
+	    Other
+    end.
+
+open(Peer, Access, LocalFilename, Mode, SuggestedOptions, Initial) when is_list(Initial) ->
+    case prepare(Peer, Access, LocalFilename, Mode, SuggestedOptions, Initial) of
+ 	{ok, SuggestedOptions2, GenericState} ->
+	    open(Peer, Access, LocalFilename, Mode, SuggestedOptions2, GenericState);
+	Other ->
+	    Other
+    end;
+open(Peer, Access, LocalFilename, Mode, SuggestedOptions, #generic_state{state = State, open = Open} = GenericState) ->
+    case Open(Peer, Access, LocalFilename, Mode, SuggestedOptions, State) of
+	{ok, SuggestedOptions2, NewState} ->
+	    {ok, SuggestedOptions2, GenericState#generic_state{state = NewState}};
+	Other ->
+	    Other
+    end.
+
+read(#generic_state{state = State, read = Read} = GenericState) ->
+    case Read(State) of
+	{more, DataBlock, NewState} ->
+	    {more, DataBlock, GenericState#generic_state{state = NewState}};
+	Other ->
+	    Other
+    end.
+
+write(DataBlock, #generic_state{state = State, write = Write} = GenericState) ->
+    case Write(DataBlock, State) of
+	{more, NewState} ->
+	    {more, GenericState#generic_state{state = NewState}};
+	Other ->
+	    Other
+    end.
+
+abort(Code, Text, #generic_state{state = State, abort = Abort}) ->
+    Abort(Code, Text, State).
+
+lookup_option(Key, Default, Options) ->
+    case lists:keysearch(Key, 1, Options) of
+	{value, {_, Val}} ->
+	    Val;
+	false ->
+	    Default
+    end.
+
diff --git a/lib/tftp/test/tftp_test_lib.hrl b/lib/tftp/test/tftp_test_lib.hrl
new file mode 100644
index 0000000000..e7a5a37d2c
--- /dev/null
+++ b/lib/tftp/test/tftp_test_lib.hrl
@@ -0,0 +1,44 @@
+%%
+%% %CopyrightBegin%
+%% 
+%% Copyright Ericsson AB 2007-2016. All Rights Reserved.
+%% 
+%% Licensed under the Apache License, Version 2.0 (the "License");
+%% you may not use this file except in compliance with the License.
+%% You may obtain a copy of the License at
+%%
+%%     http://www.apache.org/licenses/LICENSE-2.0
+%%
+%% Unless required by applicable law or agreed to in writing, software
+%% distributed under the License is distributed on an "AS IS" BASIS,
+%% WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+%% See the License for the specific language governing permissions and
+%% limitations under the License.
+%% 
+%% %CopyrightEnd%
+%%
+
+-record('REASON', {mod, line, desc}).
+
+-define(LOG(Format, Args),
+	tftp_test_lib:log(Format, Args, ?MODULE, ?LINE)).
+
+-define(ERROR(Reason),
+	tftp_test_lib:error(Reason, ?MODULE, ?LINE)).
+
+-define(VERIFY(Expected, Expr),
+	fun() ->
+		AcTuAlReS = (catch (Expr)),
+		case AcTuAlReS of
+		    Expected -> ?LOG("Ok, ~p\n", [AcTuAlReS]);
+		    _        ->	?ERROR(AcTuAlReS)
+	       end,
+		AcTuAlReS
+	end()).
+
+-define(IGNORE(Expr), 
+	fun() ->
+		AcTuAlReS = (catch (Expr)),
+		?LOG("Ok, ~p\n", [AcTuAlReS]),
+		AcTuAlReS
+	end()).
diff --git a/lib/tftp/vsn.mk b/lib/tftp/vsn.mk
new file mode 100644
index 0000000000..c4a6e749e7
--- /dev/null
+++ b/lib/tftp/vsn.mk
@@ -0,0 +1,24 @@
+#-*-makefile-*-   ; force emacs to enter makefile-mode
+
+# %CopyrightBegin%
+# 
+# Copyright Ericsson AB 2001-2018. All Rights Reserved.
+# 
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at
+#
+#     http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
+# 
+# %CopyrightEnd%
+
+APPLICATION = tftp
+TFTP_VSN   = 1.0.0
+PRE_VSN     =
+APP_VSN     = "$(APPLICATION)-$(TFTP_VSN)$(PRE_VSN)"