ssh: Create doc for the ssh_daemon_channel behaviour

8 files changed, 210 insertions, 27 deletions

diff --git a/lib/ssh/doc/src/Makefile b/lib/ssh/doc/src/Makefile
index 0063484f72..f47a1bfb40 100644
--- a/lib/ssh/doc/src/Makefile
+++ b/lib/ssh/doc/src/Makefile
@@ -40,6 +40,7 @@ RELSYSDIR = $(RELEASE_PATH)/lib/$(APPLICATION)-$(VSN)
 XML_APPLICATION_FILES = ref_man.xml
 XML_REF3_FILES = ssh.xml \
 	ssh_channel.xml \
+	ssh_daemon_channel.xml \
 	ssh_connection.xml \
 	ssh_client_key_api.xml \
 	ssh_server_key_api.xml \
diff --git a/lib/ssh/doc/src/ref_man.xml b/lib/ssh/doc/src/ref_man.xml
index 140ebd8c76..1e1cff9119 100644
--- a/lib/ssh/doc/src/ref_man.xml
+++ b/lib/ssh/doc/src/ref_man.xml
@@ -36,6 +36,7 @@
   <xi:include href="ssh_app.xml"/>
   <xi:include href="ssh.xml"/>
   <xi:include href="ssh_channel.xml"/>
+  <xi:include href="ssh_daemon_channel.xml"/>
   <xi:include href="ssh_connection.xml"/>
   <xi:include href="ssh_client_key_api.xml"/>
   <xi:include href="ssh_server_key_api.xml"/>
diff --git a/lib/ssh/doc/src/specs.xml b/lib/ssh/doc/src/specs.xml
index 3ab4f43aec..f7837f9c5c 100644
--- a/lib/ssh/doc/src/specs.xml
+++ b/lib/ssh/doc/src/specs.xml
@@ -1,6 +1,7 @@
 <?xml version="1.0" encoding="utf-8" ?>
 <specs xmlns:xi="http://www.w3.org/2001/XInclude">
   <xi:include href="../specs/specs_ssh_channel.xml"/>
+  <xi:include href="../specs/specs_ssh_daemon_channel.xml"/>
   <xi:include href="../specs/specs_ssh_client_key_api.xml"/>
   <xi:include href="../specs/specs_ssh_connection.xml"/>
   <xi:include href="../specs/specs_ssh_server_key_api.xml"/>
diff --git a/lib/ssh/doc/src/ssh.xml b/lib/ssh/doc/src/ssh.xml
index 03078cfd83..c403989ba9 100644
--- a/lib/ssh/doc/src/ssh.xml
+++ b/lib/ssh/doc/src/ssh.xml
@@ -68,8 +68,8 @@
     <seealso marker="ssh_sftp#start_channel/1">ssh_sftp:start_channel/1,2,3</seealso>.
     </p>
     <p>To write your own client channel handler, use the behaviour 
-    <seealso marker="ssh_channel">ssh_channel</seealso>. For own server channel handlers use the ssh_daemon_channel
-    behaviour: see the <seealso marker="ssh_channel#ssh_daemon_channel">note in ssh_channel</seealso>.
+    <seealso marker="ssh_channel">ssh_channel</seealso>. and server channel handlers use 
+    <seealso marker="ssh_daemon_channel">ssh_daemon_channel</seealso> behaviour.
     </p>
     <p>Both clients and daemons accepts options that controls the exact behaviour. Some options are common to both.
     The three sets are called 
@@ -378,7 +378,8 @@
 	<p>The <c>subsystem_name</c> is the name that a client requests to start with for example
 	<seealso marker="ssh_connection#subsystem/4">ssh_connection:subsystem/4</seealso>.
 	</p>
-	<p>The <c>channel_callback</c> is the module that implements the <c>ssh_daemon_channel</c>
+	<p>The <c>channel_callback</c> is the module that implements the
+	<seealso marker="ssh_daemon_channel">ssh_daemon_channel</seealso>
 	behaviour in the daemon. See the section 
 	<seealso marker="using_ssh#usersguide_creating_a_subsystem">Creating a Subsystem</seealso>
 	in the User's Guide for more information and an example.
diff --git a/lib/ssh/doc/src/ssh_channel.xml b/lib/ssh/doc/src/ssh_channel.xml
index 0355f7bf52..2ee6ab566b 100644
--- a/lib/ssh/doc/src/ssh_channel.xml
+++ b/lib/ssh/doc/src/ssh_channel.xml
@@ -37,7 +37,7 @@
     that are multiplexed over an SSH connection and communicates over
     the <url href="http://www.ietf.org/rfc/rfc4254.txt"> SSH
     Connection Protocol</url>. This module provides a callback API
-    that takes care of generic channel aspects, such as flow control
+    that takes care of generic channel aspects for clients, such as flow control
     and close messages. It lets the callback functions take care of
     the service (application) specific parts. This behavior also ensures
     that the channel process honors the principal of an OTP-process so
@@ -46,14 +46,17 @@
     the <c>ssh</c> applications supervisor tree.
     </p>
 
-    <marker id="ssh_daemon_channel"/>
-    <note><p>When implementing an <c>ssh</c> subsystem, use
-    <c>-behaviour(ssh_daemon_channel)</c> instead of <c>-behaviour(ssh_channel)</c>.
-    The reason is that the only relevant callback functions for subsystems are
-    <c>init/1</c>, <c>handle_ssh_msg/2</c>, <c>handle_msg/2</c>, and <c>terminate/2</c>.
-    So, the <c>ssh_daemon_channel</c> behaviour is a limited version of the
-    <c>ssh_channel</c> behaviour.
-    </p></note>
+    <note><p>When implementing a <c>ssh</c> subsystem for daemons, use
+    <seealso marker="ssh_daemon_channel">-behaviour(ssh_daemon_channel)</seealso> instead.
+    </p>
+    </note>
+
+    <dont>
+      <p>Functions in this module are not supposed to be called outside a module implementing this
+      behaviour!
+      </p>
+    </dont>
+
   </description>
 
   <funcs>
@@ -100,7 +103,7 @@
       </desc>
     </func>
 
-       <func>
+    <func>
       <name>enter_loop(State) -> _ </name>
       <fsummary>Makes an existing process an ssh_channel process.</fsummary>
       <type>
@@ -217,13 +220,19 @@
   </funcs>
   
   <section>
-    <marker id="cb_timeouts"></marker>
-    <title>CALLBACK TIME-OUTS</title>
-
-    <p>The time-out values that can be returned by the callback functions
-    have the same semantics as in a <seealso marker="stdlib:gen_server">gen_server</seealso>.
-    If the time-out occurs, <seealso marker="#Module:handle_msg-2">handle_msg/2</seealso>
-    is called as <c>handle_msg(timeout, State)</c>.</p>
+    <title>Callback Functions</title>
+    <p>
+      The following functions are to be exported from a
+      <c>ssh_daemon_channel</c> callback module.
+    </p>
+    <section>
+      <marker id="cb_timeouts"></marker>
+      <title>Callback timeouts</title>
+      <p>The timeout values that can be returned by the callback functions
+      have the same semantics as in a <seealso marker="stdlib:gen_server">gen_server</seealso>.
+      If the time-out occurs, <seealso marker="#Module:handle_msg-2">handle_msg/2</seealso>
+      is called as <c>handle_msg(timeout, State)</c>.</p>
+    </section>
   </section>
 
   <funcs>
@@ -286,7 +295,7 @@
 	state if the initializations succeed.
 	</p>
 	<p>For more detailed information on time-outs, see Section
-	<seealso marker="#cb_timeouts">CALLBACK TIME-OUTS</seealso>. </p>
+	<seealso marker="#cb_timeouts">Callback timeouts</seealso>. </p>
       </desc>
     </func>
    
@@ -313,7 +322,7 @@
 	<seealso marker="#call-2">call/[2,3]</seealso>
 	</p>
 	<p>For more detailed information on time-outs,, see Section
-	<seealso marker="#cb_timeouts">CALLBACK TIME-OUTS</seealso>.</p>
+	<seealso marker="#cb_timeouts">Callback timeouts</seealso>.</p>
       </desc>
     </func>
 
@@ -334,7 +343,7 @@
 	<c>cast/2</c>.
 	</p>
 	<p>For more detailed information on time-outs, see Section
-	<seealso marker="#cb_timeouts">CALLBACK TIME-OUTS</seealso>.</p>
+	<seealso marker="#cb_timeouts">Callback timeouts</seealso>.</p>
       </desc>
     </func>
  
diff --git a/lib/ssh/doc/src/ssh_daemon_channel.xml b/lib/ssh/doc/src/ssh_daemon_channel.xml
new file mode 100644
index 0000000000..8b0ff93f5f
--- /dev/null
+++ b/lib/ssh/doc/src/ssh_daemon_channel.xml
@@ -0,0 +1,169 @@
+<?xml version="1.0" encoding="utf-8" ?>
+<!DOCTYPE erlref SYSTEM "erlref.dtd">
+
+<erlref>
+  <header>
+    <copyright>
+      <year>2009</year>
+      <year>2016</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.
+
+      The Initial Developer of the Original Code is Ericsson AB.
+    </legalnotice>
+    <title>ssh_daemon_channel</title>
+    <prepared></prepared>
+    <docno></docno>
+    <date></date>
+    <rev></rev>
+  </header>
+  <module>ssh_daemon_channel</module>
+  <modulesummary>-behaviour(ssh_daemon_channel).
+  </modulesummary>
+  <description>
+    <p>SSH services (clients and servers) are implemented as channels
+    that are multiplexed over an SSH connection and communicates over
+    the <url href="http://www.ietf.org/rfc/rfc4254.txt"> SSH
+    Connection Protocol</url>. This module provides a callback API
+    that takes care of generic channel aspects for daemons, such as flow control
+    and close messages. It lets the callback functions take care of
+    the service (application) specific parts. This behavior also ensures
+    that the channel process honors the principal of an OTP-process so
+    that it can be part of a supervisor tree. This is a requirement of
+    channel processes implementing a subsystem that will be added to
+    the <c>ssh</c> applications supervisor tree.
+    </p>
+
+    <note><p>When implementing a client subsystem handler, use
+    <seealso marker="ssh_channel">-behaviour(ssh_channel)</seealso> instead.
+    </p>
+    </note>
+
+  </description>
+
+  <section>
+    <title>Callback Functions</title>
+    <p>
+      The following functions are to be exported from a
+      <c>ssh_daemon_channel</c> callback module.
+    </p>
+  </section>
+
+  <funcs>
+    <func>
+      <name>Module:init(Args) -> {ok, State} | {ok, State, timeout()} |
+      {stop, Reason}</name>
+      <fsummary>Makes necessary initializations and returns the
+      initial channel state if the initializations succeed.</fsummary>
+      <type>
+	<v>Args = term()</v>
+	<d>Last argument to <c>start_link/4</c>.</d>
+	<v>State = term()</v>
+	<v>Reason = term()</v>
+      </type>
+      <desc>
+	<p>Makes necessary initializations and returns the initial channel
+	state if the initializations succeed.
+	</p>
+	<p>The time-out values that can be returned
+	have the same semantics as in a <seealso marker="stdlib:gen_server">gen_server</seealso>.
+	If the time-out occurs, <seealso marker="#Module:handle_msg-2">handle_msg/2</seealso>
+	is called as <c>handle_msg(timeout, State)</c>.
+	</p>
+      </desc>
+    </func>
+   
+    <func>
+      <name>Module:handle_msg(Msg, State) -> {ok, State} |
+      {stop, ChannelId, State}</name>
+
+      <fsummary>Handles other messages than SSH connection protocol,
+      call, or cast messages sent to the channel.</fsummary>
+      <type>
+	<v>Msg = timeout | term()</v>
+	<v>ChannelId = <seealso marker="ssh#type-channel_id">ssh:channel_id()</seealso></v>
+	<v>State = term() </v>
+      </type>
+      <desc>
+	<p>Handles other messages than SSH Connection Protocol, call, or
+	cast messages sent to the channel. 
+	</p>
+
+	<p>Possible Erlang 'EXIT' messages is to be handled by this
+	function and all channels are to handle the following message.</p>
+	
+	<taglist>
+	  <tag><c>{ssh_channel_up, ssh:channel_id(), ssh:connection_ref()}</c></tag>
+	  <item><p>This is the first message that the channel receives.
+	  This is especially useful if the
+	  server wants to send a message to the client without first
+	  receiving a message from it. If the message is not
+	  useful for your particular scenario, ignore it by
+	  immediately returning <c>{ok, State}</c>.
+	  </p></item>
+	</taglist>
+      </desc>
+    </func>
+
+    <func>
+      <name>Module:handle_ssh_msg(Msg, State) -> {ok, State} | {stop,
+      ChannelId, State}</name>
+      <fsummary>Handles <c>ssh</c> connection protocol messages.</fsummary>
+      <type>
+	<v>Msg = ssh_connection:event()</v>
+	<v>ChannelId = <seealso marker="ssh#type-channel_id">ssh:channel_id()</seealso></v>
+	<v>State = term()</v>
+      </type>
+      <desc>
+	<p>Handles SSH Connection Protocol messages that may need
+	service-specific attention. For details,
+	see <seealso marker="ssh_connection"> ssh_connection:event()</seealso>.
+	</p>
+	
+	<p>The following message is taken care of by the
+	<c>ssh_daemon_channel</c> behavior.</p>
+	
+	<taglist>
+	  <tag><c>{closed, ssh:channel_id()}</c></tag>
+	  <item><p>The channel behavior sends a close message to the
+	  other side, if such a message has not already been sent.
+	  Then it terminates the channel with reason <c>normal</c>.</p></item>
+	</taglist>
+      </desc>
+    </func>
+
+    <func>
+      <name>Module:terminate(Reason, State) -> _</name>
+      <fsummary>Does cleaning up before channel process termination.
+      </fsummary>
+      <type>
+	<v>Reason = term()</v>
+	<v>State = term()</v>
+      </type>
+      <desc>
+	<p>This function is called by a channel process when it is
+	about to terminate. Before this function is called, <seealso
+	marker="ssh_connection#close-2"> ssh_connection:close/2
+	</seealso> is called, if it has not been called earlier.
+	This function does any necessary cleaning
+	up. When it returns, the channel process terminates with
+	reason <c>Reason</c>. The return value is ignored.
+	</p>
+      </desc>
+    </func>
+    
+  </funcs>
+  
+</erlref>
diff --git a/lib/ssh/doc/src/ssh_protocol.xml b/lib/ssh/doc/src/ssh_protocol.xml
index a0032ab449..21c755b48e 100644
--- a/lib/ssh/doc/src/ssh_protocol.xml
+++ b/lib/ssh/doc/src/ssh_protocol.xml
@@ -87,8 +87,10 @@
       connection, and all channels are flow-controlled.  Typically an
       SSH client will open a channel, send data/commands, receive
       data/"control information" and when it is done close the
-      channel. The <seealso
-      marker="ssh_channel">ssh_channel</seealso> behaviour makes it easy to
+      channel. The 
+      <seealso marker="ssh_channel">ssh_channel</seealso> / 
+      <seealso marker="ssh_daemon_channel">ssh_daemon_channel</seealso>
+      behaviours makes it easy to
       write your own SSH client/server processes that use flow
       control. It handles generic parts of SSH channel management and
       lets you focus on the application logic.
diff --git a/lib/ssh/doc/src/ssh_sftpd.xml b/lib/ssh/doc/src/ssh_sftpd.xml
index 1be29b3b29..4c599a7fb9 100644
--- a/lib/ssh/doc/src/ssh_sftpd.xml
+++ b/lib/ssh/doc/src/ssh_sftpd.xml
@@ -44,8 +44,7 @@
       <item><p><c>"sftp"</c></p></item>
       <tag><c>channel_callback() =</c></tag>
       <item><p><c>atom()</c> - Name of the Erlang module implementing the subsystem using the
-      <c>ssh_channel</c> behavior, see the
-      <seealso marker="ssh_channel">ssh_channel(3)</seealso> manual page.</p></item>
+      <seealso marker="ssh_daemon_channel">ssh_daemon_channel</seealso> behaviour.</p></item>
       <tag><c>channel_init_args() =</c></tag>
       <item><p><c>list()</c> - The one given as argument to function <c>subsystem_spec/1</c>.</p></item>
     </taglist>