Pluggable distribution socket implementation for EI

20 files changed, 2259 insertions, 760 deletions

diff --git a/lib/erl_interface/configure.in b/lib/erl_interface/configure.in
index a155ceef7e..747750c1fb 100644
--- a/lib/erl_interface/configure.in
+++ b/lib/erl_interface/configure.in
@@ -82,6 +82,15 @@ AC_ARG_ENABLE(threads,
   esac ],
 [ threads_disabled=maybe ])
 
+AC_ARG_ENABLE(mask-real-errno,
+[  --disable-mask-real-errno do not mask real 'errno'],
+[ case "$enableval" in
+    no) mask_real_errno=no ;;
+    *)  mask_real_errno=yes ;;
+  esac ],
+[ mask_real_errno=yes ])
+
+
 dnl ----------------------------------------------------------------------
 dnl Checks for programs
 dnl ----------------------------------------------------------------------
@@ -100,6 +109,10 @@ AC_CHECK_SIZEOF(long)
 AC_CHECK_SIZEOF(void *)
 AC_CHECK_SIZEOF(long long)
 
+if test $mask_real_errno = yes; then
+   AC_DEFINE(EI_HIDE_REAL_ERRNO, 1, [Define if 'errno' should not be exposed as is in 'erl_errno'])
+fi
+
 dnl We set EI_64BIT mode when long is 8 bytes, this makes things
 dnl work on windows and unix correctly
 if test $ac_cv_sizeof_long = 8; then
@@ -158,7 +171,7 @@ AC_CHECK_LIB([socket], [getpeername])
 # Checks for header files.
 AC_HEADER_STDC
 AC_HEADER_SYS_WAIT
-AC_CHECK_HEADERS([arpa/inet.h fcntl.h limits.h malloc.h netdb.h netinet/in.h stddef.h stdlib.h string.h sys/param.h sys/socket.h sys/select.h sys/time.h unistd.h sys/types.h])
+AC_CHECK_HEADERS([arpa/inet.h fcntl.h limits.h malloc.h netdb.h netinet/in.h stddef.h stdlib.h string.h sys/param.h sys/socket.h sys/select.h sys/time.h unistd.h sys/types.h sys/uio.h])
 
 # Checks for typedefs, structures, and compiler characteristics.
 # fixme AC_C_CONST & AC_C_VOLATILE needed for Windows?
@@ -193,7 +206,7 @@ AC_CHECK_FUNCS([dup2 gethostbyaddr gethostbyname \
 	gethostbyaddr_r \
 	gethostbyname_r gethostname writev \
 	gethrtime gettimeofday inet_ntoa memchr memmove memset select \
-	socket strchr strerror strrchr strstr uname])
+	socket strchr strerror strrchr strstr uname sysconf])
 AC_CHECK_FUNC(res_gethostbyname, [],
     AC_CHECK_LIB(resolv, res_gethostbyname)
 )
@@ -255,6 +268,7 @@ AC_SUBST(EI_THREADS)
 case "$threads_disabled" in
     no|maybe)
 	LM_CHECK_THR_LIB
+        ETHR_CHK_GCC_ATOMIC_OPS([])
 
 	case "$THR_LIB_NAME" in
 	    "")
@@ -268,7 +282,7 @@ case "$threads_disabled" in
 		EI_THREADS="true"	
 		THR_DEFS="$THR_DEFS -D_WIN32_WINNT=0x0600 -DWINVER=0x0600"
 		;;
-	    pthread)	
+	    pthread)
 		EI_THREADS="true"
 		;;
 	    *)
diff --git a/lib/erl_interface/doc/src/ei_connect.xml b/lib/erl_interface/doc/src/ei_connect.xml
index 607a7cbff4..af838e065a 100644
--- a/lib/erl_interface/doc/src/ei_connect.xml
+++ b/lib/erl_interface/doc/src/ei_connect.xml
@@ -85,6 +85,271 @@
       the <c>_tmo</c> suffix.</p>
   </section>
 
+  <section>
+    <marker id="ussi"/>
+    <title>User Supplied Socket Implementation</title>
+    <p>By default <c>ei</c> supplies a TCP/IPv4 socket interface
+    that is used when communicating. The user can however plug in
+    his/her own IPv4 socket implementation. This, for example, in order
+    to communicate over TLS. A user supplied socket implementation
+    is plugged in by passing a
+    <seealso marker="#ei_socket_callbacks">callback structure</seealso>
+    to either
+    <seealso marker="#ei_connect_init"><c>ei_connect_init_ussi()</c></seealso>
+    or
+    <seealso marker="#ei_connect_init"><c>ei_connect_xinit_ussi()</c></seealso>.</p>
+    
+    <p>All callbacks in the <c>ei_socket_callbacks</c> structure
+    <em>should</em> return zero on success; and a posix error
+    code on failure.</p>
+    
+    <p>The <c>addr</c> argument of the <c>listen</c>, <c>accept</c>,
+    and <c>connect</c> callbacks refer to appropriate address
+    structure for currently used protocol. Currently <c>ei</c>
+    only supports IPv4. That is, at this time <c>addr</c> always
+    points to a <c>struct sockaddr_in</c> structure.</p>
+
+    <p>The <c>ei_socket_callbacks</c> structure may be enlarged in
+    the future. All fields not set, <em>needs</em> to be zeroed out.</p>
+
+    <marker id="ei_socket_callbacks"/>
+    <code type="none"><![CDATA[
+typedef struct {
+    int flags;
+    int (*socket)(void **ctx, void *setup_ctx);
+    int	(*close)(void *ctx);
+    int (*listen)(void *ctx, void *addr, int *len, int backlog);
+    int (*accept)(void **ctx, void *addr, int *len, unsigned tmo);
+    int (*connect)(void *ctx, void *addr, int len, unsigned tmo);
+    int (*writev)(void *ctx, const void *iov, int iovcnt, ssize_t *len, unsigned tmo);
+    int (*write)(void *ctx, const char *buf, ssize_t *len, unsigned tmo);
+    int (*read)(void *ctx, char *buf, ssize_t *len, unsigned tmo);
+    int (*handshake_packet_header_size)(void *ctx, int *sz);
+    int (*connect_handshake_complete)(void *ctx);
+    int (*accept_handshake_complete)(void *ctx);
+    int (*get_fd)(void *ctx, int *fd);
+} ei_socket_callbacks;
+        ]]></code>
+
+    <taglist>
+      <tag><c>flags</c></tag>
+      <item>
+	<p>Flags informing <c>ei</c> about the behaviour of the
+	callbacks. Flags should be bitwise or:ed together. If no flag,
+	is set, the <c>flags</c> field should contain <c>0</c>. Currently,
+	supported flags:</p>
+	<taglist>
+	  <tag><c>EI_SCLBK_FLG_FULL_IMPL</c></tag>
+	  <item>
+	    <p>
+	      If set, the <c>accept()</c>, <c>connect()</c>,
+	      <c>writev()</c>, <c>write()</c>, and <c>read()</c> callbacks
+	      implements timeouts. The timeout is passed in the <c>tmo</c>
+	      argument and is given in milli seconds. Note that the
+	      <c>tmo</c> argument to these callbacks differ from the
+	      timeout arguments in the <c>ei</c> API. Zero means a zero
+	      timeout. That is, poll and timeout immediately unless the
+	      operation is successful. <c>EI_SCLBK_INF_TMO</c>
+	      (max <c>unsigned</c>) means infinite timeout. The file
+	      descriptor is in blocking mode when a callback is called,
+	      and it must be in blocking mode when the callback returns.
+	    </p>
+	    <p>
+	      If not set, <c>ei</c> will implement the timeout using
+	      <c>select()</c> in order to determine when to call the
+	      callbacks and when to time out. The <c>tmo</c> arguments
+	      of the <c>accept()</c>, <c>connect()</c>, <c>writev()</c>,
+	      <c>write()</c>, and <c>read()</c> callbacks should be
+	      ignored. The callbacks may be called in non-blocking mode.
+	      The callbacks are not allowed to change between blocking
+	      and non-blocking mode. In order for this to work,
+	      <c>select()</c> needs to interact with the socket primitives
+	      used the same way as it interacts with the ordinary socket
+	      primitives. If this is not the case, the callbacks
+	      <em>need</em> to implement timeouts and this flag should
+	      be set.
+	    </p>
+	  </item>
+	</taglist>
+	<p>More flags may be introduced in the future.</p>
+      </item>
+      <tag><c>int (*socket)(void **ctx, void *setup_ctx)</c></tag>
+      <item>
+	<p>Create a socket and a context for the socket.</p>
+	
+	<p>On success it should set <c>*ctx</c> to point to a context for
+	the created socket. This context will be passed to all other
+	socket callbacks. This function will be passed the same
+	<c>setup_context</c> as passed to the preceeding
+	<seealso marker="#ei_connect_init"><c>ei_connect_init_ussi()</c></seealso>
+	or
+	<seealso marker="#ei_connect_init"><c>ei_connect_xinit_ussi()</c></seealso>
+	call.</p>
+	
+	<note><p>During the lifetime of a socket, the pointer <c>*ctx</c>
+	<em>has</em> to remain the same. That is, it cannot later be
+	relocated.</p></note>
+	
+	<p>This callback is mandatory.</p>
+      </item>
+      
+      <tag><c>int (*close)(void *ctx)</c></tag>
+      <item>
+	<p>Close the socket identified by <c>ctx</c> and destroy the context.</p>
+	
+	<p>This callback is mandatory.</p>
+      </item>
+      
+      <tag><c>int (*listen)(void *ctx, void *addr, int *len, int backlog)</c></tag>
+      <item>
+	<p>Bind the socket identified by <c>ctx</c> to a local interface
+	and then listen on it.</p>
+	
+	<p>The <c>addr</c> and <c>len</c> arguments are both input and output
+	arguments. When called <c>addr</c> points to an address structure of
+	lenght <c>*len</c> containing information on how to bind the socket.
+	Uppon return this callback should have updated the structure referred
+	by <c>addr</c> with information on how the socket actually was bound.
+	<c>*len</c> should be updated to reflect the size of <c>*addr</c>
+	updated. <c>backlog</c> identifies the size of the backlog for the
+	listen socket.</p>
+	
+	<p>This callback is mandatory.</p>
+      </item>
+      
+      <tag><c>int (*accept)(void **ctx, void *addr, int *len, unsigned tmo)</c></tag>
+      <item>
+	<p>Accept connections on the listen socket identified by
+	<c>*ctx</c>.</p>
+
+	<p>When a connection is accepted, a new context for the accepted
+	connection should be created and <c>*ctx</c> should be updated
+	to point to the new context for the accepted connection. When
+	called <c>addr</c> points to an uninitialized address structure
+	of lenght <c>*len</c>. Uppon return this callback should have
+	updated this structure with information about the client address.
+	<c>*len</c> should be updated to reflect the size of <c>*addr</c>
+	updated.
+	</p>
+
+	<p>If the <c>EI_SCLBK_FLG_FULL_IMPL</c> flag has been set,
+	<c>tmo</c> contains timeout time in milliseconds.</p>
+
+	<note><p>During the lifetime of a socket, the pointer <c>*ctx</c>
+	<em>has</em> to remain the same. That is, it cannot later be
+	relocated.</p></note>
+
+	<p>This callback is mandatory.</p>
+      </item>
+      
+      <tag><c>int (*connect)(void *ctx, void *addr, int len, unsigned tmo)</c></tag>
+      <item>
+	<p>Connect the socket identified by <c>ctx</c> to the address
+	identified by <c>addr</c>.</p>
+
+	<p>When called <c>addr</c> points to an address structure of
+	lenght <c>len</c> containing information on where to connect.</p>
+
+	<p>If the <c>EI_SCLBK_FLG_FULL_IMPL</c> flag has been set,
+	<c>tmo</c> contains timeout time in milliseconds.</p>
+	
+	<p>This callback is mandatory.</p>
+      </item>
+      
+      <tag><c>int (*writev)(void *ctx, const void *iov, long iovcnt, ssize_t *len, unsigned tmo)</c></tag>
+      <item>
+	<p>Write data on the connected socket identified by <c>ctx</c>.</p>
+
+	<p><c>iov</c> points to an array of <c>struct iovec</c> structures of
+	length <c>iovcnt</c> containing data to write to the socket. On success,
+	this callback should set <c>*len</c> to the amount of bytes successfully
+	written on the socket.</p>
+	
+	<p>If the <c>EI_SCLBK_FLG_FULL_IMPL</c> flag has been set,
+	<c>tmo</c> contains timeout time in milliseconds.</p>
+	
+	<p>This callback is optional. Set the <c>writev</c> field
+	in the the <c>ei_socket_callbacks</c> structure to <c>NULL</c> if not
+	implemented.</p>
+      </item>
+      
+      <tag><c>int (*write)(void *ctx, const char *buf, ssize_t *len, unsigned tmo)</c></tag>
+      <item>
+	<p>Write data on the connected socket identified by <c>ctx</c>.</p>
+	
+	<p>When called <c>buf</c> points to a buffer of length <c>*len</c>
+	containing the data to write on the socket. On success, this callback
+	should set <c>*len</c> to the amount of bytes successfully written on
+	the socket.</p>
+
+	<p>If the <c>EI_SCLBK_FLG_FULL_IMPL</c> flag has been set,
+	<c>tmo</c> contains timeout time in milliseconds.</p>
+	
+	<p>This callback is mandatory.</p>
+      </item>
+      
+      <tag><c>int (*read)(void *ctx, char *buf, ssize_t *len, unsigned tmo)</c></tag>
+      <item>
+	<p>Read data on the connected socket identified by <c>ctx</c>.</p>
+	
+	<p><c>buf</c> points to a buffer of length <c>*len</c> where the
+	read data should be placed. On success, this callback should update
+	<c>*len</c> to the amount of bytes successfully read on the socket.</p>
+	
+	<p>If the <c>EI_SCLBK_FLG_FULL_IMPL</c> flag has been set,
+	<c>tmo</c> contains timeout time in milliseconds.</p>
+	
+	<p>This callback is mandatory.</p>
+      </item>
+      
+      <tag><c>int (*handshake_packet_header_size)(void *ctx, int *sz)</c></tag>
+      <item>
+	<p>Inform about handshake packet header size to use during the Erlang
+	distribution handshake.</p>
+
+	<p>On success, <c>*sz</c> should be set to the handshake packet header
+	size to use. Valid values are <c>2</c> and <c>4</c>. Erlang TCP
+	distribution use a handshake packet size of <c>2</c> and Erlang TLS
+	distribution use a handshake packet size of <c>4</c>.</p>
+
+	<p>This callback is mandatory.</p>
+      </item>
+      
+      <tag><c>int (*connect_handshake_complete)(void *ctx)</c></tag>
+      <item>
+	<p>Called when a locally started handshake has completed successfully.</p>
+	
+	<p>This callback is optional. Set the <c>connect_handshake_complete</c> field
+	in the <c>ei_socket_callbacks</c> structure to <c>NULL</c> if not implemented.</p>	
+      </item>
+      
+      <tag><c>int (*accept_handshake_complete)(void *ctx)</c></tag>
+      <item>
+	<p>Called when a remotely started handshake has completed successfully.</p>
+
+	<p>This callback is optional. Set the <c>accept_handshake_complete</c> field in
+	the <c>ei_socket_callbacks</c> structure to <c>NULL</c> if not implemented.</p>
+      </item>
+      
+      <tag><c>int (*get_fd)(void *ctx, int *fd)</c></tag>
+      <item>
+	<p>Inform about file descriptor used by the socket which is identified
+	by <c>ctx</c>.</p>
+
+	<note><p>During the lifetime of a socket, the file descriptor
+	<em>has</em> to remain the same. That is, repeated calls to this
+	callback with the same context <c>should</c> always report the same
+	file descriptor.</p>
+	<p>The file descriptor <em>has</em> to be a real file descriptor.
+	That is, no other operation should be able to get the same file
+	descriptor until it has been released by the <c>close()</c>
+	callback.</p>
+	</note>
+
+	<p>This callback is mandatory.</p>
+      </item>
+    </taglist>
+  </section>
   <funcs>
     <func>
       <name><ret>struct hostent</ret><nametext>*ei_gethostbyaddr(const char *addr, int len, int type)</nametext></name>
@@ -96,6 +361,7 @@
         <p>Convenience functions for some common name lookup functions.</p>
       </desc>
     </func>
+    
 
     <func>
       <name><ret>int</ret><nametext>ei_accept(ei_cnode *ec, int listensock, ErlConnect *conp)</nametext></name>
@@ -141,6 +407,14 @@ typedef struct {
     </func>
 
     <func>
+      <name><ret>int</ret><nametext>ei_close_connection(int fd)</nametext></name>
+      <fsummary>Close a connection.</fsummary>
+      <desc>
+        <p>Closes a previously opened connection or listen socket.</p>
+      </desc>
+    </func>
+
+    <func>
       <name><ret>int</ret><nametext>ei_connect(ei_cnode* ec, char *nodename)</nametext></name>
       <name><ret>int</ret><nametext>ei_xconnect(ei_cnode* ec, Erl_IpAddr adr, char *alivename)</nametext></name>
       <fsummary>Establish a connection to an Erlang node.</fsummary>
@@ -193,7 +467,9 @@ fd = ei_xconnect(&ec, &addr, ALIVE);
 
     <func>
       <name><ret>int</ret><nametext>ei_connect_init(ei_cnode* ec, const char* this_node_name, const char *cookie, short creation)</nametext></name>
+      <name><ret>int</ret><nametext>ei_connect_init_ussi(ei_cnode* ec, const char* this_node_name, const char *cookie, short creation, ei_socket_callbacks *cbs, int cbs_sz, void *setup_context)</nametext></name>
       <name><ret>int</ret><nametext>ei_connect_xinit(ei_cnode* ec, const char *thishostname, const char *thisalivename, const char *thisnodename, Erl_IpAddr thisipaddr, const char *cookie, short creation)</nametext></name>
+      <name><ret>int</ret><nametext>ei_connect_xinit_ussi(ei_cnode* ec, const char *thishostname, const char *thisalivename, const char *thisnodename, Erl_IpAddr thisipaddr, const char *cookie, short creation, ei_socket_callbacks *cbs, int cbs_sz, void *setup_context)</nametext></name>
       <fsummary>Initialize for a connection.</fsummary>
       <desc>
         <p>Initializes the <c>ec</c> structure, to
@@ -236,6 +512,21 @@ fd = ei_xconnect(&ec, &addr, ALIVE);
           <item>
             <p><c>thispaddr</c> if the IP address of the host.</p>
           </item>
+	  <item>
+	    <p><c>cbs</c> is a pointer to a
+	    <seealso marker="#ei_socket_callbacks">callback structure</seealso>
+	    implementing and alternative socket interface.</p>
+	  </item>
+	  <item>
+	    <p><c>cbs_sz</c> is the size of the structure
+	    pointed to by <c>cbs</c>.</p>
+	  </item>
+	  <item>
+	    <p><c>setup_context</c> is a pointer to a structure that
+	    will be passed as second argument to the <c>socket</c> callback
+	    in the <c>cbs</c> structure.</p>
+	  </item>
+
         </list>
         <p>A C-node acting as a server is assigned a creation
           number when it calls <c>ei_publish()</c>.</p>
@@ -299,6 +590,45 @@ if (ei_connect_init(&ec, "madonna", "cookie...", n++) < 0) {
     </func>
 
     <func>
+      <name><ret>int</ret><nametext>ei_listen(ei_cnode *ec, int *port, int backlog)</nametext></name>
+      <name><ret>int</ret><nametext>ei_xlisten(ei_cnode *ec, Erl_IpAddr adr, int *port, int backlog)</nametext></name>
+      <fsummary>Create a listen socket.</fsummary>
+      <desc>
+        <p>Used by a server process to setup a listen socket which
+	later can be used for accepting connections from client processes.
+	</p>
+        <list type="bulleted">
+          <item>
+            <p><c>ec</c> is the C-node structure.</p>
+          </item>
+	  <item>
+	    <p><c>adr</c> is local interface to bind to.</p>
+	  </item>
+          <item>
+            <p><c>port</c> is a pointer to an integer containing the
+	    port number to bind to. If <c>*port</c> equals <c>0</c>
+	    when calling <c>ei_listen()</c>, the socket will be bound to
+	    an ephemeral port. On success, <c>ei_listen()</c> will update
+	    the value of <c>*port</c> to the port actually bound to.
+	    </p>
+          </item>
+          <item>
+            <p><c>backlog</c> is maximum backlog of pending connections.</p>
+          </item>
+        </list>
+	<p><c>ei_listen</c> will create a socket, bind to a port on the
+	local interface identified by <c>adr</c> (or all local interfaces if
+	<c>ei_listen()</c> is called), and mark the socket as a passive socket
+	(that is, a socket that will be used for accepting incoming connections).
+	</p>
+	<p>
+	  On success, a file descriptor is returned which can be used in a call to
+	  <c>ei_accept()</c>. On failure, <c>ERL_ERROR</c> is returned and
+        <c>erl_errno</c> is set to <c>EIO</c>.</p>
+      </desc>
+    </func>
+
+    <func>
       <name><ret>int</ret><nametext>ei_publish(ei_cnode *ec, int port)</nametext></name>
       <fsummary>Publish a node name.</fsummary>
       <desc>
diff --git a/lib/erl_interface/include/ei.h b/lib/erl_interface/include/ei.h
index 948f89be85..92674571e2 100644
--- a/lib/erl_interface/include/ei.h
+++ b/lib/erl_interface/include/ei.h
@@ -35,6 +35,7 @@
 #include <winsock2.h>
 #include <windows.h>
 #include <winbase.h>
+typedef LONG_PTR ssize_t; /* Sigh... */
 #endif
 
 #include <stdio.h>		/* Need type FILE */
@@ -286,6 +287,31 @@ typedef struct {
   char nodename[MAXNODELEN+1];
 } ErlConnect;
 
+#define EI_SCLBK_INF_TMO (~((unsigned) 0))
+
+#define EI_SCLBK_FLG_FULL_IMPL (1 << 0)
+
+typedef struct {
+    int flags;
+
+    int (*socket)(void **ctx, void *setup_ctx);
+    int	(*close)(void *ctx);
+    int (*listen)(void *ctx, void *addr, int *len, int backlog);
+    int (*accept)(void **ctx, void *addr, int *len, unsigned tmo);
+    int (*connect)(void *ctx, void *addr, int len, unsigned tmo);
+    int (*writev)(void *ctx, const void *iov, int iovcnt, ssize_t *len, unsigned tmo);
+    int (*write)(void *ctx, const char *buf, ssize_t *len, unsigned tmo);
+    int (*read)(void *ctx, char *buf, ssize_t *len, unsigned tmo);
+
+    int (*handshake_packet_header_size)(void *ctx, int *sz);
+    int (*connect_handshake_complete)(void *ctx);
+    int (*accept_handshake_complete)(void *ctx);
+    int (*get_fd)(void *ctx, int *fd);
+
+    /* end of version 1 */
+    
+} ei_socket_callbacks;
+
 typedef struct ei_cnode_s {
     char thishostname[EI_MAXHOSTNAMELEN+1];
     char thisnodename[MAXNODELEN+1];
@@ -295,6 +321,8 @@ typedef struct ei_cnode_s {
     char ei_connect_cookie[EI_MAX_COOKIE_SIZE+1];
     short creation;
     erlang_pid self;
+    ei_socket_callbacks *cbs;
+    void *setup_context;
 } ei_cnode;
 
 typedef struct in_addr *Erl_IpAddr; 
@@ -308,7 +336,6 @@ typedef struct ei_x_buff_TAG {
     int index;
 } ei_x_buff;
 
-
 /* -------------------------------------------------------------------- */
 /*    Function definitions (listed in same order as documentation)      */
 /* -------------------------------------------------------------------- */
@@ -322,6 +349,16 @@ int ei_connect_xinit (ei_cnode* ec, const char *thishostname,
 		      Erl_IpAddr thisipaddr, const char *cookie,
 		      const short creation);
 
+int ei_connect_init_ussi(ei_cnode* ec, const char* this_node_name,
+                         const char *cookie, short creation,
+                         ei_socket_callbacks *cbs, int cbs_sz,
+                         void *setup_context);
+int ei_connect_xinit_ussi(ei_cnode* ec, const char *thishostname,
+                          const char *thisalivename, const char *thisnodename,
+                          Erl_IpAddr thisipaddr, const char *cookie,
+                          const short creation, ei_socket_callbacks *cbs,
+                          int cbs_sz, void *setup_context);
+
 int ei_connect(ei_cnode* ec, char *nodename);
 int ei_connect_tmo(ei_cnode* ec, char *nodename, unsigned ms);
 int ei_xconnect(ei_cnode* ec, Erl_IpAddr adr, char *alivename);
@@ -348,11 +385,15 @@ int ei_rpc_from(ei_cnode* ec, int fd, int timeout, erlang_msg* msg,
 
 int ei_publish(ei_cnode* ec, int port);
 int ei_publish_tmo(ei_cnode* ec, int port, unsigned ms);
+int ei_listen(ei_cnode *ec, int *port, int backlog);
+int ei_xlisten(ei_cnode *ec, Erl_IpAddr adr, int *port, int backlog);    
 int ei_accept(ei_cnode* ec, int lfd, ErlConnect *conp);
 int ei_accept_tmo(ei_cnode* ec, int lfd, ErlConnect *conp, unsigned ms);
 int ei_unpublish(ei_cnode* ec);
 int ei_unpublish_tmo(const char *alive, unsigned ms);
 
+int ei_close_connection(int fd);
+
 const char *ei_thisnodename(const ei_cnode* ec);
 const char *ei_thishostname(const ei_cnode* ec);
 const char *ei_thisalivename(const ei_cnode* ec);
diff --git a/lib/erl_interface/src/connect/ei_connect.c b/lib/erl_interface/src/connect/ei_connect.c
index 9df4fa3b6c..1132c9fc23 100644
--- a/lib/erl_interface/src/connect/ei_connect.c
+++ b/lib/erl_interface/src/connect/ei_connect.c
@@ -21,8 +21,6 @@
  * Purpose: Connect to any node at any host. (EI version)
  */
 
-#include "eidef.h"
-
 #include <stdlib.h>
 #include <sys/types.h>
 #include <fcntl.h>
@@ -84,7 +82,9 @@
 #include <string.h>
 #include <errno.h>
 #include <ctype.h>
+#include <stddef.h>
 
+#include "eidef.h"
 #include "eiext.h"
 #include "ei_portio.h"
 #include "ei_internal.h"
@@ -103,6 +103,10 @@ int ei_tracelevel = 0;
 #define COOKIE_FILE "/.erlang.cookie"
 #define EI_MAX_HOME_PATH 1024
 
+#define EI_SOCKET_CALLBACKS_SZ_V1                       \
+    (offsetof(ei_socket_callbacks, get_fd)              \
+     + sizeof(int (*)(void *)))
+
 /* FIXME why not macro? */
 static char *null_cookie = "";
 
@@ -113,35 +117,51 @@ static int get_home(char *buf, int size);
 static unsigned gen_challenge(void);
 static void gen_digest(unsigned challenge, char cookie[], 
 		       unsigned char digest[16]);
-static int send_status(int fd, char *status, unsigned ms);
-static int recv_status(int fd, unsigned ms);
-static int send_challenge(int fd, char *nodename, 
-			  unsigned challenge, unsigned version, unsigned ms);
-static int recv_challenge(int fd, unsigned *challenge, 
-			  unsigned *version,
-			  unsigned *flags, ErlConnect *namebuf, unsigned ms);
-static int send_challenge_reply(int fd, unsigned char digest[16], 
+static int send_status(ei_socket_callbacks *cbs, void *ctx,
+                       int pkt_sz, char *status, unsigned ms);
+static int recv_status(ei_socket_callbacks *cbs, void *ctx,
+                       int pkt_sz, unsigned ms);
+static int send_challenge(ei_socket_callbacks *cbs, void *ctx, int pkt_sz,
+                          char *nodename, unsigned challenge,
+                          unsigned version, unsigned ms);
+static int recv_challenge(ei_socket_callbacks *cbs, void *ctx, int pkt_sz,
+                          unsigned *challenge, unsigned *version,
+			  unsigned *flags, char *namebuf, unsigned ms);
+static int send_challenge_reply(ei_socket_callbacks *cbs, void *ctx,
+                                int pkt_sz, unsigned char digest[16], 
 				unsigned challenge, unsigned ms);
-static int recv_challenge_reply(int fd, 
-				unsigned our_challenge,
+static int recv_challenge_reply(ei_socket_callbacks *cbs, void *ctx,
+                                int pkt_sz, unsigned our_challenge,
 				char cookie[], 
 				unsigned *her_challenge, unsigned ms);
-static int send_challenge_ack(int fd, unsigned char digest[16], unsigned ms);
-static int recv_challenge_ack(int fd, 
-			      unsigned our_challenge,
+static int send_challenge_ack(ei_socket_callbacks *cbs, void *ctx,
+                              int pkt_sz, unsigned char digest[16],
+                              unsigned ms);
+static int recv_challenge_ack(ei_socket_callbacks *cbs, void *ctx, 
+			      int pkt_sz, unsigned our_challenge,
 			      char cookie[], unsigned ms);
-static int send_name(int fd, char *nodename, 
-		     unsigned version, unsigned ms); 
+static int send_name(ei_socket_callbacks *cbs, void *ctx, int pkt_sz,
+                     char *nodename, unsigned version, unsigned ms); 
 
-/* Common for both handshake types */
-static int recv_name(int fd, 
-		     unsigned *version,
-		     unsigned *flags, ErlConnect *namebuf, unsigned ms);
+static int recv_name(ei_socket_callbacks *cbs, void *ctx, int pkt_sz,
+                     unsigned *version, unsigned *flags, char *namebuf,
+                     unsigned ms);
 
 static struct hostent*
 dyn_gethostbyname_r(const char *name, struct hostent *hostp, char **buffer_p,
                     int buflen, int *h_errnop);
 
+static void abort_connection(ei_socket_callbacks *cbs, void *ctx);
+static int close_connection(ei_socket_callbacks *cbs, void *ctx, int fd);
+
+static char *
+estr(int e)
+{
+    char *str = strerror(e);
+    if (!str)
+        return "unknown error";
+    return str;
+}
 
 
 /***************************************************************************
@@ -154,25 +174,206 @@ dyn_gethostbyname_r(const char *name, struct hostent *hostp, char **buffer_p,
 
 typedef struct ei_socket_info_s {
     int socket;
+    ei_socket_callbacks *cbs;
+    void *ctx;
     int dist_version;
     ei_cnode cnode;	/* A copy, not a pointer. We don't know when freed */
     char cookie[EI_MAX_COOKIE_SIZE+1];
 } ei_socket_info;
 
+/***************************************************************************
+ *
+ *  XXX
+ *
+ ***************************************************************************/
+
+#ifndef ETHR_HAVE___atomic_compare_exchange_n
+#  define ETHR_HAVE___atomic_compare_exchange_n 0
+#endif
+#ifndef ETHR_HAVE___atomic_load_n
+#  define ETHR_HAVE___atomic_load_n 0
+#endif
+#ifndef ETHR_HAVE___atomic_store_n
+#  define ETHR_HAVE___atomic_store_n 0
+#endif
+
+#if defined(_REENTRANT)                                                 \
+    && (!(ETHR_HAVE___atomic_compare_exchange_n & SIZEOF_VOID_P)        \
+        || !(ETHR_HAVE___atomic_load_n & SIZEOF_VOID_P)                 \
+        || !(ETHR_HAVE___atomic_store_n & SIZEOF_VOID_P))
+#  undef EI_DISABLE_SEQ_SOCKET_INFO
+#  define EI_DISABLE_SEQ_SOCKET_INFO
+#endif
+
+#ifdef __WIN32__
+#  undef EI_DISABLE_SEQ_SOCKET_INFO
+#  define EI_DISABLE_SEQ_SOCKET_INFO
+#endif
+
+#ifndef EI_DISABLE_SEQ_SOCKET_INFO
+
+#ifdef _REENTRANT
+
+#define EI_ATOMIC_CMPXCHG_ACQ_REL(VARP, XCHGP, NEW) \
+    __atomic_compare_exchange_n((VARP), (XCHGP), (NEW), 0, \
+                                __ATOMIC_ACQ_REL, __ATOMIC_ACQUIRE)
+#define EI_ATOMIC_LOAD_ACQ(VARP) \
+    __atomic_load_n((VARP), __ATOMIC_ACQUIRE)
+#define EI_ATOMIC_STORE_REL(VARP, NEW) \
+    __atomic_store_n((VARP), (NEW), __ATOMIC_RELEASE)
+
+#else /* ! _REENTRANT */
+
+#define EI_ATOMIC_CMPXCHG_ACQ_REL(VARP, XCHGP, NEW)    \
+    (*(VARP) == *(XCHGP)                               \
+     ? ((*(VARP) = (NEW)), !0)                         \
+     : ((*(XCHGP) = *(VARP)), 0))
+#define EI_ATOMIC_LOAD_ACQ(VARP) (*(VARP))
+#define EI_ATOMIC_STORE_REL(VARP, NEW) (*(VARP) = (NEW))
+
+#endif /* ! _REENTRANT */
+
+#define EI_SOCKET_INFO_SEG_BITS 5
+#define EI_SOCKET_INFO_SEG_SIZE (1 << EI_SOCKET_INFO_SEG_BITS)
+#define EI_SOCKET_INFO_SEG_MASK (EI_SOCKET_INFO_SEG_SIZE - 1)
+
+typedef struct {
+    int max_fds;
+    ei_socket_info *segments[1]; /* Larger in reality... */
+} ei_socket_info_data__;
+
+static ei_socket_info_data__ *socket_info_data = NULL;
+
+static int init_socket_info(void)
+{
+    int max_fds;
+    int i;
+    size_t segments_len;
+    ei_socket_info_data__ *info_data, *xchg;
+
+    if (EI_ATOMIC_LOAD_ACQ(&socket_info_data) != NULL)
+        return !0; /* Already initialized... */
+    
+#if defined(HAVE_SYSCONF) && defined(_SC_OPEN_MAX)
+    max_fds = sysconf(_SC_OPEN_MAX);
+#else
+    max_fds = 1024;
+#endif
+
+    if (max_fds < 0)
+        return 0;
+
+    segments_len = ((max_fds-1)/EI_SOCKET_INFO_SEG_SIZE + 1);
+    
+    info_data = malloc(sizeof(ei_socket_info_data__)
+                       + (sizeof(ei_socket_info *)*(segments_len-1)));
+    if (!info_data)
+        return 0;
+
+    info_data->max_fds = max_fds;
+    for (i = 0; i < segments_len; i++)
+        info_data->segments[i] = NULL;
+
+    xchg = NULL;
+    if (!EI_ATOMIC_CMPXCHG_ACQ_REL(&socket_info_data, &xchg, info_data))
+        free(info_data); /* Already initialized... */
+
+    return !0;
+}
+
+static int put_ei_socket_info(int fd, int dist_version, char* cookie, ei_cnode *ec,
+                              ei_socket_callbacks *cbs, void *ctx)
+{
+    int six;
+    ei_socket_info *seg, *si;
+    int socket;
+
+    if (fd < 0 || socket_info_data->max_fds <= fd)
+        return -1;
+
+    socket = fd;
+    six = fd >> EI_SOCKET_INFO_SEG_BITS;
+    seg = EI_ATOMIC_LOAD_ACQ(&socket_info_data->segments[six]);
+    
+    if (!seg) {
+        ei_socket_info *xchg;
+        int i;
+        seg = malloc(sizeof(ei_socket_info)*EI_SOCKET_INFO_SEG_SIZE);
+        if (!seg)
+            return -1;
+        for (i = 0; i < EI_SOCKET_INFO_SEG_SIZE; i++) {
+            seg[i].socket = -1;
+        }
+
+        xchg = NULL;
+        if (!EI_ATOMIC_CMPXCHG_ACQ_REL(&socket_info_data->segments[six], &xchg, seg)) {
+            free(seg);
+            seg = xchg;
+        }
+    }
+
+    si = &seg[fd & EI_SOCKET_INFO_SEG_MASK];
+
+    if (dist_version < 0) {
+        socket = -1;
+        si->cbs = NULL;
+        si->ctx = NULL;
+    }
+    else {
+        si->dist_version = dist_version;
+        si->cnode = *ec;
+        si->cbs = cbs;
+        si->ctx = ctx;
+        strcpy(si->cookie, cookie);
+    }
+
+    EI_ATOMIC_STORE_REL(&si->socket, socket);
+
+    return 0;
+}
+
+static ei_socket_info* get_ei_socket_info(int fd)
+{
+    int six, socket;
+    ei_socket_info *seg, *si;
+    
+    if (fd < 0 || socket_info_data->max_fds <= fd)
+        return NULL;
+    
+    six = fd >> EI_SOCKET_INFO_SEG_BITS;
+    seg = EI_ATOMIC_LOAD_ACQ(&socket_info_data->segments[six]);
+
+    if (!seg)
+        return NULL;
+    
+    si = &seg[fd & EI_SOCKET_INFO_SEG_MASK];
+    socket = EI_ATOMIC_LOAD_ACQ(&si->socket);
+    if (socket != fd)
+        return NULL;
+    return si;
+}
+    
+#else /* EI_DISABLE_SEQ_SOCKET_INFO */
+
 int ei_n_sockets = 0, ei_sz_sockets = 0;
 ei_socket_info *ei_sockets = NULL;
+
 #ifdef _REENTRANT
 ei_mutex_t* ei_sockets_lock = NULL;
 #endif /* _REENTRANT */
 
+static int init_socket_info(void)
+{
+#ifdef _REENTRANT
+    if (ei_sockets_lock == NULL) {
+	ei_sockets_lock = ei_mutex_create();
+    }
+#endif /* _REENTRANT */
+    return !0;
+}
 
-/***************************************************************************
- *
- *  XXX
- *
- ***************************************************************************/
-
-static int put_ei_socket_info(int fd, int dist_version, char* cookie, ei_cnode *ec)
+static int put_ei_socket_info(int fd, int dist_version, char* cookie, ei_cnode *ec,
+                              ei_socket_callbacks *cbs, void *ctx)
 {
     int i;
 
@@ -182,11 +383,13 @@ static int put_ei_socket_info(int fd, int dist_version, char* cookie, ei_cnode *
     for (i = 0; i < ei_n_sockets; ++i) {
 	if (ei_sockets[i].socket == fd) {
 	    if (dist_version == -1) {
-		memmove(&ei_sockets[i], &ei_sockets[i+1],
+                memmove(&ei_sockets[i], &ei_sockets[i+1],
 			sizeof(ei_sockets[0])*(ei_n_sockets-i-1));
 	    } else {
 		ei_sockets[i].dist_version = dist_version;
 		/* Copy the content, see ei_socket_info */
+                ei_sockets[i].cbs = cbs;
+                ei_sockets[i].ctx = ctx;
 		ei_sockets[i].cnode = *ec;
 		strcpy(ei_sockets[i].cookie, cookie);
 	    }
@@ -209,7 +412,9 @@ static int put_ei_socket_info(int fd, int dist_version, char* cookie, ei_cnode *
 	}
 	ei_sockets[ei_n_sockets].socket = fd;
 	ei_sockets[ei_n_sockets].dist_version = dist_version;
-	ei_sockets[i].cnode = *ec;
+	ei_sockets[ei_n_sockets].cnode = *ec;
+        ei_sockets[ei_n_sockets].cbs = cbs;
+        ei_sockets[ei_n_sockets].ctx = ctx;
 	strcpy(ei_sockets[ei_n_sockets].cookie, cookie);
 	++ei_n_sockets;
     }
@@ -219,14 +424,6 @@ static int put_ei_socket_info(int fd, int dist_version, char* cookie, ei_cnode *
     return 0;
 }
 
-#if 0
-/* FIXME not used ?! */
-static int remove_ei_socket_info(int fd, int dist_version, char* cookie)
-{
-    return put_ei_socket_info(fd, -1, NULL);
-}
-#endif
-
 static ei_socket_info* get_ei_socket_info(int fd)
 {
     int i;
@@ -248,6 +445,13 @@ static ei_socket_info* get_ei_socket_info(int fd)
     return NULL;
 }
 
+#endif /* EI_DISABLE_SEQ_SOCKET_INFO */
+
+static int remove_ei_socket_info(int fd)
+{
+    return put_ei_socket_info(fd, -1, NULL, NULL, NULL, NULL);
+}
+
 ei_cnode *ei_fd_to_cnode(int fd)
 {
     ei_socket_info *sockinfo = get_ei_socket_info(fd);
@@ -255,6 +459,19 @@ ei_cnode *ei_fd_to_cnode(int fd)
     return &sockinfo->cnode;
 }
 
+int ei_get_cbs_ctx__(ei_socket_callbacks **cbs, void **ctx, int fd)
+{
+    ei_socket_info *sockinfo = get_ei_socket_info(fd);
+    if (sockinfo) {
+        *cbs = sockinfo->cbs;
+        *ctx = sockinfo->ctx;
+        return 0;
+    }
+
+    *cbs = NULL;
+    *ctx = NULL;
+    return EBADF;
+}
 
 /***************************************************************************
  *  Get/Set tracelevel
@@ -333,21 +550,6 @@ const char *ei_getfdcookie(int fd)
     return r;
 }
 
-/* call with cookie to set value to use on descriptor fd,
-* or specify NULL to use default
-*/
-/* FIXME why defined but not used? */
-#if 0
-static int ei_setfdcookie(ei_cnode* ec, int fd, char *cookie)
-{
-    int dist_version = ei_distversion(fd);
-
-    if (cookie == NULL)
-	cookie = ec->ei_connect_cookie;
-    return put_ei_socket_info(fd, dist_version, cookie);
-}
-#endif
-
 static int get_int32(unsigned char *s)
 {
     return ((s[0] << 24) | (s[1] << 16) | (s[2] << 8) | (s[3] ));
@@ -405,12 +607,16 @@ static int initWinSock(void)
 * Initailize by setting:
 * thishostname, thisalivename, thisnodename and thisipaddr
 */
-int ei_connect_xinit(ei_cnode* ec, const char *thishostname,
-		     const char *thisalivename, const char *thisnodename,
-		     Erl_IpAddr thisipaddr, const char *cookie,
-		     const short creation)
+int ei_connect_xinit_ussi(ei_cnode* ec, const char *thishostname,
+                          const char *thisalivename, const char *thisnodename,
+                          Erl_IpAddr thisipaddr, const char *cookie,
+                          const short creation, ei_socket_callbacks *cbs,
+                          int cbs_sz, void *setup_context)
 {
     char *dbglevel;
+
+    if (cbs != &ei_default_socket_callbacks)
+        EI_SET_HAVE_PLUGIN_SOCKET_IMPL__;
     
 /* FIXME this code was enabled for 'erl'_connect_xinit(), why not here? */
 #if 0    
@@ -422,12 +628,16 @@ int ei_connect_xinit(ei_cnode* ec, const char *thishostname,
 #endif
 #endif
 
-#ifdef _REENTRANT
-    if (ei_sockets_lock == NULL) {
-	ei_sockets_lock = ei_mutex_create();
+    if (!init_socket_info()) {
+	EI_TRACE_ERR0("ei_connect_xinit","can't initiate socket info");
+	return ERL_ERROR;
     }
-#endif /* _REENTRANT */
 
+    if (cbs_sz < EI_SOCKET_CALLBACKS_SZ_V1) {
+	EI_TRACE_ERR0("ei_connect_xinit","invalid size of ei_socket_callbacks struct");
+        return ERL_ERROR;
+    }
+    
     ec->creation = creation & 0x3; /* 2 bits */
     
     if (cookie) {
@@ -469,6 +679,9 @@ int ei_connect_xinit(ei_cnode* ec, const char *thishostname,
     ec->self.serial = 0;
     ec->self.creation = creation & 0x3; /* 2 bits */
 
+    ec->cbs = cbs;
+    ec->setup_context = setup_context;
+
     if ((dbglevel = getenv("EI_TRACELEVEL")) != NULL ||
 	(dbglevel = getenv("ERL_DEBUG_DIST")) != NULL)
 	ei_tracelevel = atoi(dbglevel);
@@ -476,14 +689,27 @@ int ei_connect_xinit(ei_cnode* ec, const char *thishostname,
     return 0;
 }
 
+int ei_connect_xinit(ei_cnode* ec, const char *thishostname,
+                     const char *thisalivename, const char *thisnodename,
+                     Erl_IpAddr thisipaddr, const char *cookie,
+                     const short creation)
+{
+    return ei_connect_xinit_ussi(ec, thishostname, thisalivename, thisnodename,
+                                 thisipaddr, cookie, creation,
+                                 &ei_default_socket_callbacks,
+                                 sizeof(ei_default_socket_callbacks),
+                                 NULL);
+}
 
 /*
 * Initialize by set: thishostname, thisalivename, 
 * thisnodename and thisipaddr. At success return 0,
 * otherwise return -1.
 */
-int ei_connect_init(ei_cnode* ec, const char* this_node_name,
-		    const char *cookie, short creation)
+int ei_connect_init_ussi(ei_cnode* ec, const char* this_node_name,
+                         const char *cookie, short creation,
+                         ei_socket_callbacks *cbs, int cbs_sz,
+                         void *setup_context)
 {
     char thishostname[EI_MAXHOSTNAMELEN+1];
     char thisnodename[MAXNODELEN+1];
@@ -500,12 +726,7 @@ int ei_connect_init(ei_cnode* ec, const char* this_node_name,
 	return ERL_ERROR;
     }
 #endif /* win32 */
-#ifdef _REENTRANT
-    if (ei_sockets_lock == NULL) {
-	ei_sockets_lock = ei_mutex_create();
-    }
-#endif /* _REENTRANT */
-    
+
     /* gethostname requires len to be max(hostname) + 1 */
     if (gethostname(thishostname, EI_MAXHOSTNAMELEN+1) == -1) {
 #ifdef __WIN32__
@@ -561,43 +782,22 @@ int ei_connect_init(ei_cnode* ec, const char* this_node_name,
 	    sprintf(thisnodename, "%s@%s", this_node_name, hp->h_name);
 	}
     }
-    res = ei_connect_xinit(ec, thishostname, thisalivename, thisnodename,
-                           (struct in_addr *)*hp->h_addr_list, cookie, creation);
+    res = ei_connect_xinit_ussi(ec, thishostname, thisalivename, thisnodename,
+                                (struct in_addr *)*hp->h_addr_list, cookie, creation,
+                                cbs, cbs_sz, setup_context);
     if (buf != buffer)
         free(buf);
     return res;
 }
 
-
-/* connects to port at ip-address ip_addr 
-* and returns fd to socket 
-* port has to be in host byte order 
-*/
-static int cnct(uint16 port, struct in_addr *ip_addr, int addr_len, unsigned ms)
+int ei_connect_init(ei_cnode* ec, const char* this_node_name,
+                    const char *cookie, short creation)
 {
-    int s, res;
-    struct sockaddr_in iserv_addr;
-    
-    if ((s = socket(AF_INET, SOCK_STREAM, 0)) < 0) {
-	erl_errno = errno;
-	return ERL_ERROR;
-    }
-    
-    memset((char*)&iserv_addr, 0, sizeof(struct sockaddr_in));
-    memcpy((char*)&iserv_addr.sin_addr, (char*)ip_addr, addr_len);
-    iserv_addr.sin_family = AF_INET;
-    iserv_addr.sin_port = htons(port);
-    
-    if ((res = ei_connect_t(s, (struct sockaddr*)&iserv_addr, 
-		      sizeof(iserv_addr),ms)) < 0) {
-	erl_errno = (res == -2) ? ETIMEDOUT : EIO;
-	closesocket(s);
-	return ERL_ERROR;
-    }
-    
-    return s;
-} /* cnct */
-
+    return ei_connect_init_ussi(ec, this_node_name, cookie, creation,
+                                &ei_default_socket_callbacks,
+                                sizeof(ei_default_socket_callbacks),
+                                NULL);
+}
 
 /*
  * Same as ei_gethostbyname_r, but also handles ERANGE error
@@ -758,91 +958,218 @@ int ei_connect(ei_cnode* ec, char *nodename)
   *  the node through epmd at that host 
   *
 */
-int ei_xconnect_tmo(ei_cnode* ec, Erl_IpAddr adr, char *alivename, unsigned ms)
+int ei_xconnect_tmo(ei_cnode* ec, Erl_IpAddr ip_addr, char *alivename, unsigned ms)
 {
-    struct in_addr *ip_addr=(struct in_addr *) adr;
+    ei_socket_callbacks *cbs = ec->cbs;
+    void *ctx;
     int rport = 0; /*uint16 rport = 0;*/
     int sockd;
-    int one = 1;
     int dist = 0;
-    ErlConnect her_name;
     unsigned her_flags, her_version;
-
+    unsigned our_challenge, her_challenge;
+    unsigned char our_digest[16];
+    int err;
+    int pkt_sz;
+    struct sockaddr_in addr;
+    unsigned tmo = ms == 0 ? EI_SCLBK_INF_TMO : ms;
+    
     erl_errno = EIO;		/* Default error code */
     
     EI_TRACE_CONN1("ei_xconnect","-> CONNECT attempt to connect to %s",
 		   alivename);
     
-    if ((rport = ei_epmd_port_tmo(ip_addr,alivename,&dist, ms)) < 0) {
+    if ((rport = ei_epmd_port_tmo(ip_addr,alivename,&dist, tmo)) < 0) {
 	EI_TRACE_ERR0("ei_xconnect","-> CONNECT can't get remote port");
 	/* ei_epmd_port_tmo() has set erl_errno */
 	return ERL_NO_PORT;
     }
-    
-    /* we now have port number to enode, try to connect */
-    if((sockd = cnct((uint16)rport, ip_addr, sizeof(struct in_addr),ms)) < 0) {
-	EI_TRACE_ERR0("ei_xconnect","-> CONNECT socket connect failed");
-	/* cnct() has set erl_errno */
-	return ERL_CONNECT_FAIL;
-    }
-    
-    EI_TRACE_CONN0("ei_xconnect","-> CONNECT connected to remote");
 
-    /* FIXME why connect before checking 'dist' output from ei_epmd_port() ?! */
     if (dist <= 4) {
 	EI_TRACE_ERR0("ei_xconnect","-> CONNECT remote version not compatible");
-	goto error;
+	return ERL_ERROR;
     }
-    else {
-	unsigned our_challenge, her_challenge;
-	unsigned char our_digest[16];
-	
-	if (send_name(sockd, ec->thisnodename, (unsigned) dist, ms))
-	    goto error;
-	if (recv_status(sockd, ms))
-	    goto error;
-	if (recv_challenge(sockd, &her_challenge, &her_version,
-	    &her_flags, &her_name, ms))
-	    goto error;
-	our_challenge = gen_challenge();
-	gen_digest(her_challenge, ec->ei_connect_cookie, our_digest);
-	if (send_challenge_reply(sockd, our_digest, our_challenge, ms))
-	    goto error;
-	if (recv_challenge_ack(sockd, our_challenge, 
-	    ec->ei_connect_cookie, ms))
-	    goto error;
-	put_ei_socket_info(sockd, dist, null_cookie, ec); /* FIXME check == 0 */
+
+    err = ei_socket_ctx__(cbs, &ctx, ec->setup_context);
+    if (err) {
+        EI_TRACE_ERR2("ei_xconnect","-> SOCKET failed: %s (%d)",
+                      estr(err), err);
+        erl_errno = err;
+        return ERL_CONNECT_FAIL;
+    }
+
+    memset((void *) &addr, 0, sizeof(struct sockaddr_in));
+    memcpy((void *) &addr.sin_addr, (void *) ip_addr, sizeof(addr.sin_addr));
+    addr.sin_family = AF_INET;
+    addr.sin_port = htons(rport);
+
+    err = ei_connect_ctx_t__(cbs, ctx, (void *) &addr, sizeof(addr), tmo);
+    if (err) {
+        EI_TRACE_ERR2("ei_xconnect","-> CONNECT socket connect failed: %s (%d)",
+                      estr(err), err);
+        abort_connection(cbs, ctx);
+        erl_errno = err;
+        return ERL_CONNECT_FAIL;
     }
     
-    setsockopt(sockd, IPPROTO_TCP, TCP_NODELAY, (char *)&one, sizeof(one));
-    setsockopt(sockd, SOL_SOCKET, SO_KEEPALIVE, (char *)&one, sizeof(one));
+    EI_TRACE_CONN0("ei_xconnect","-> CONNECT connected to remote");
 
-    EI_TRACE_CONN1("ei_xconnect","-> CONNECT (ok) remote = %s",alivename);
+    err = EI_GET_FD__(cbs, ctx, &sockd);
+    if (err) {
+        EI_CONN_SAVE_ERRNO__(err);
+        goto error;
+    }
+
+    err = cbs->handshake_packet_header_size(ctx, &pkt_sz);
+    if (err) {
+        EI_CONN_SAVE_ERRNO__(err);
+        goto error;
+    }
+        
+    if (send_name(cbs, ctx, pkt_sz, ec->thisnodename, (unsigned) dist, tmo))
+        goto error;
+    if (recv_status(cbs, ctx, pkt_sz, tmo))
+        goto error;
+    if (recv_challenge(cbs, ctx, pkt_sz, &her_challenge,
+                       &her_version, &her_flags, NULL, tmo))
+        goto error;
+    our_challenge = gen_challenge();
+    gen_digest(her_challenge, ec->ei_connect_cookie, our_digest);
+    if (send_challenge_reply(cbs, ctx, pkt_sz, our_digest, our_challenge, tmo))
+        goto error;
+    if (recv_challenge_ack(cbs, ctx, pkt_sz, our_challenge, 
+                           ec->ei_connect_cookie, tmo))
+        goto error;
+    if (put_ei_socket_info(sockd, dist, null_cookie, ec, cbs, ctx) != 0)
+        goto error;
+
+    if (cbs->connect_handshake_complete) {
+        err = cbs->connect_handshake_complete(ctx);
+        if (err) {
+            EI_TRACE_ERR2("ei_xconnect","-> CONNECT failed: %s (%d)",
+                          estr(err), err);
+            close_connection(cbs, ctx, sockd);
+            EI_CONN_SAVE_ERRNO__(err);
+            return ERL_ERROR;
+        }
+    }    
     
+    EI_TRACE_CONN1("ei_xconnect","-> CONNECT (ok) remote = %s",alivename);
+
     erl_errno = 0;
     return sockd;
     
 error:
     EI_TRACE_ERR0("ei_xconnect","-> CONNECT failed");
-    closesocket(sockd);
+    abort_connection(cbs, ctx);
     return ERL_ERROR;
 } /* ei_xconnect */
 
-int ei_xconnect(ei_cnode* ec, Erl_IpAddr adr, char *alivename)
+int ei_xconnect(ei_cnode* ec, Erl_IpAddr ip_addr, char *alivename)
 {
-    return ei_xconnect_tmo(ec, adr, alivename, 0);
+    return ei_xconnect_tmo(ec, ip_addr, alivename, 0);
 }
 
+int ei_listen(ei_cnode *ec, int *port, int backlog)
+{
+    struct in_addr ip_addr;
+    ip_addr.s_addr = htonl(INADDR_ANY);
+    return ei_xlisten(ec, &ip_addr, port, backlog);
+}
+
+int ei_xlisten(ei_cnode *ec, struct in_addr *ip_addr, int *port, int backlog)
+{
+    ei_socket_callbacks *cbs = ec->cbs;
+    struct sockaddr_in sock_addr;
+    void *ctx;
+    int fd, err, len;
+
+    err = ei_socket_ctx__(cbs, &ctx, ec->setup_context);
+    if (err) {
+        EI_TRACE_ERR2("ei_xlisten","-> SOCKET failed: %s (%d)",
+                      estr(err), err);
+        erl_errno = err;
+        return ERL_ERROR;
+    }
+
+    memset((void *) &sock_addr, 0, sizeof(struct sockaddr_in));
+    memcpy((void *) &sock_addr.sin_addr, (void *) ip_addr, sizeof(*ip_addr));
+    sock_addr.sin_family = AF_INET;
+    sock_addr.sin_port = htons((short) *port);
+
+    len = sizeof(sock_addr);
+    err = ei_listen_ctx__(cbs, ctx, (void *) &sock_addr, &len, backlog);
+    if (err) {
+        EI_TRACE_ERR2("ei_xlisten","-> listen failed: %s (%d)",
+                      estr(err), err);
+        erl_errno = err;
+        goto error;
+    }
+
+    if (len != sizeof(sock_addr)) {
+        if (len < offsetof(struct sockaddr_in, sin_addr) + sizeof(sock_addr.sin_addr)
+            || len < offsetof(struct sockaddr_in, sin_port) + sizeof(sock_addr.sin_port)) {
+            erl_errno = EIO;
+            EI_TRACE_ERR0("ei_xlisten","-> get info failed");
+            goto error;
+        }
+    }
+
+    memcpy((void *) ip_addr, (void *) &sock_addr.sin_addr, sizeof(*ip_addr));
+    *port = (int) ntohs(sock_addr.sin_port);
+    
+    err = EI_GET_FD__(cbs, ctx, &fd);
+    if (err) {
+        erl_errno = err;
+        goto error;
+    }
+
+    if (put_ei_socket_info(fd, 0, null_cookie, ec, cbs, ctx) != 0) {
+        EI_TRACE_ERR0("ei_xlisten","-> save socket info failed");
+        erl_errno = EIO;
+        goto error;
+    }
+    
+    erl_errno = 0;
+
+    return fd;
+    
+error:
+    abort_connection(cbs, ctx);
+    return ERL_ERROR;
+}
+    
+static int close_connection(ei_socket_callbacks *cbs, void *ctx, int fd)
+{
+    int err;
+    remove_ei_socket_info(fd);
+    err = ei_close_ctx__(cbs, ctx);
+    if (err) {
+        erl_errno = err;
+        return ERL_ERROR;
+    }
+    return 0;
+}
 
-  /* 
-  * For symmetry reasons
-*/
-#if 0
 int ei_close_connection(int fd)
 {
-    return closesocket(fd);
+    ei_socket_callbacks *cbs;
+    void *ctx;
+    int err = EI_GET_CBS_CTX__(&cbs, &ctx, fd);
+    if (err)
+        erl_errno = err;
+    else {
+        if (close_connection(cbs, ctx, fd) == 0)
+            return 0;
+    }
+    EI_TRACE_ERR2("ei_close_connection","<- CLOSE socket close failed: %s (%d)",
+                  estr(erl_errno), erl_errno);
+    return ERL_ERROR;
 } /* ei_close_connection */
-#endif
+
+static void abort_connection(ei_socket_callbacks *cbs, void *ctx)
+{
+    (void) ei_close_ctx__(cbs, ctx);
+}
 
   /*
   * Accept and initiate a connection from another
@@ -857,25 +1184,71 @@ int ei_accept(ei_cnode* ec, int lfd, ErlConnect *conp)
 int ei_accept_tmo(ei_cnode* ec, int lfd, ErlConnect *conp, unsigned ms)
 {
     int fd;
-    struct sockaddr_in cli_addr;
-    int cli_addr_len=sizeof(struct sockaddr_in);
     unsigned her_version, her_flags;
-    ErlConnect her_name;
+    char tmp_nodename[MAXNODELEN+1];
+    char *her_name;
+    int pkt_sz, err;
+    struct sockaddr_in addr;
+    int addr_len = sizeof(struct sockaddr_in);
+    ei_socket_callbacks *cbs;
+    void *ctx;
+    unsigned tmo = ms == 0 ? EI_SCLBK_INF_TMO : ms;
 
     erl_errno = EIO;		/* Default error code */
+    
+    err = EI_GET_CBS_CTX__(&cbs, &ctx, lfd);
+    if (err) {
+        EI_CONN_SAVE_ERRNO__(err);
+        return ERL_ERROR;
+    }
+
 
     EI_TRACE_CONN0("ei_accept","<- ACCEPT waiting for connection");
+
+    if (conp) {
+        her_name = &conp->nodename[0];
+    }
+    else {
+        her_name = &tmp_nodename[0];
+    }
     
-    if ((fd = ei_accept_t(lfd, (struct sockaddr*) &cli_addr, 
-	&cli_addr_len, ms )) < 0) {
-	EI_TRACE_ERR0("ei_accept","<- ACCEPT socket accept failed");
-	erl_errno = (fd == -2) ? ETIMEDOUT : EIO;
-	goto error;
+    /*
+     * ei_accept_ctx_t__() replaces the pointer to the listen context
+     * with a pointer to the accepted connection context on success.
+     */
+    err = ei_accept_ctx_t__(cbs, &ctx, (void *) &addr, &addr_len, tmo);
+    if (err) {
+	EI_TRACE_ERR2("ei_accept","<- ACCEPT socket accept failed: %s (%d)",
+                      estr(err), err);
+        EI_CONN_SAVE_ERRNO__(err);
+        return ERL_ERROR;
+    }
+
+    err = EI_GET_FD__(cbs, ctx, &fd);
+    if (err) {
+	EI_TRACE_ERR2("ei_accept","<- ACCEPT get fd failed: %s (%d)",
+                      estr(err), err);
+        EI_CONN_SAVE_ERRNO__(err);
+    }
+
+    if (addr_len != sizeof(struct sockaddr_in)) {
+        if (addr_len < (offsetof(struct sockaddr_in, sin_addr)
+                        + sizeof(addr.sin_addr))) {
+            EI_TRACE_ERR0("ei_accept","<- ACCEPT get addr failed");
+            goto error;
+        }
+    }
+
+    err = cbs->handshake_packet_header_size(ctx, &pkt_sz);
+    if (err) {
+	EI_TRACE_ERR2("ei_accept","<- ACCEPT get packet size failed: %s (%d)",
+                      estr(err), err);
+        EI_CONN_SAVE_ERRNO__(err);
     }
     
     EI_TRACE_CONN0("ei_accept","<- ACCEPT connected to remote");
     
-    if (recv_name(fd, &her_version, &her_flags, &her_name, ms)) {
+    if (recv_name(cbs, ctx, pkt_sz, &her_version, &her_flags, her_name, tmo)) {
 	EI_TRACE_ERR0("ei_accept","<- ACCEPT initial ident failed");
 	goto error;
     }
@@ -888,34 +1261,46 @@ int ei_accept_tmo(ei_cnode* ec, int lfd, ErlConnect *conp, unsigned ms)
 	unsigned our_challenge;
 	unsigned her_challenge;
 	unsigned char our_digest[16];
-	
-	if (send_status(fd,"ok", ms))
+        
+	if (send_status(cbs, ctx, pkt_sz, "ok", tmo))
 	    goto error;
 	our_challenge = gen_challenge();
-	if (send_challenge(fd, ec->thisnodename, 
-	    our_challenge, her_version, ms))
+	if (send_challenge(cbs, ctx, pkt_sz, ec->thisnodename, 
+                           our_challenge, her_version, tmo))
 	    goto error;
-	if (recv_challenge_reply(fd, our_challenge, 
-	    ec->ei_connect_cookie, 
-	    &her_challenge, ms))
+	if (recv_challenge_reply(cbs, ctx, pkt_sz, our_challenge, 
+                                 ec->ei_connect_cookie, &her_challenge, tmo))
 	    goto error;
 	gen_digest(her_challenge, ec->ei_connect_cookie, our_digest);
-	if (send_challenge_ack(fd, our_digest, ms))
+	if (send_challenge_ack(cbs, ctx, pkt_sz, our_digest, tmo))
 	    goto error;
-	put_ei_socket_info(fd, her_version, null_cookie, ec);
+	if (put_ei_socket_info(fd, her_version, null_cookie, ec, cbs, ctx) != 0)
+            goto error;
+    }
+    if (conp) {
+        memcpy((void *) conp->ipadr, (void *) &addr.sin_addr, sizeof(conp->ipadr));
+	strcpy(&conp->nodename[0], her_name);
+    }
+
+    if (cbs->accept_handshake_complete) {
+        err = cbs->accept_handshake_complete(ctx);
+        if (err) {
+            EI_TRACE_ERR2("ei_xconnect","-> ACCEPT handshake failed: %s (%d)",
+                          estr(err), err);
+            close_connection(cbs, ctx, fd);
+            EI_CONN_SAVE_ERRNO__(err);
+            return ERL_ERROR;
+        }
     }
-    if (conp) 
-	*conp = her_name;
     
-    EI_TRACE_CONN1("ei_accept","<- ACCEPT (ok) remote = %s",her_name.nodename);
+    EI_TRACE_CONN1("ei_accept","<- ACCEPT (ok) remote = %s",her_name);
 
     erl_errno = 0;		/* No error */
     return fd;
     
 error:
     EI_TRACE_ERR0("ei_accept","<- ACCEPT failed");
-    if (fd>=0)
-      closesocket(fd);
+    abort_connection(cbs, ctx);
     return ERL_ERROR;
 } /* ei_accept */
 
@@ -927,36 +1312,57 @@ error:
  */
 int ei_receive_tmo(int fd, unsigned char *bufp, int bufsize, unsigned ms) 
 {
-    int len;
+    ssize_t len;
     unsigned char fourbyte[4]={0,0,0,0};
-    int res;
- 
-    if ((res = ei_read_fill_t(fd, (char *) bufp, 4, ms))  != 4) {
-	erl_errno = (res == -2) ? ETIMEDOUT : EIO;
+    int err;
+    ei_socket_callbacks *cbs;
+    void *ctx;
+    unsigned tmo = ms == 0 ? EI_SCLBK_INF_TMO : ms;
+
+    err = EI_GET_CBS_CTX__(&cbs, &ctx, fd);
+    if (err) {
+        EI_CONN_SAVE_ERRNO__(err);
+        return ERL_ERROR;
+    }
+
+    len = (ssize_t) 4;
+    err = ei_read_fill_ctx_t__(cbs, ctx, (char *) bufp, &len, tmo);
+    if (!err && len != (ssize_t) 4)
+        err = EIO;
+    if (err) {
+        EI_CONN_SAVE_ERRNO__(err);
 	return ERL_ERROR;
     }
     
     /* Tick handling */
-    if ((len = get_int32(bufp)) == ERL_TICK) 
-    {
-	ei_write_fill_t(fd, (char *) fourbyte, 4, ms);
+    len = get_int32(bufp);
+    if (len == ERL_TICK) {
+        len = 4;
+	ei_write_fill_ctx_t__(cbs, ctx, (char *) fourbyte, &len, tmo);
 	/* FIXME ok to ignore error or timeout? */
 	erl_errno = EAGAIN;
 	return ERL_TICK;
     }
-    else if (len > bufsize) 
-    {
+    
+    if (len > bufsize) {
 	/* FIXME: We should drain the message. */
 	erl_errno = EMSGSIZE;
 	return ERL_ERROR;
     }
-    else if ((res = ei_read_fill_t(fd, (char *) bufp, len, ms)) != len)
-    {
-	erl_errno = (res == -2) ? ETIMEDOUT : EIO;
-	return ERL_ERROR;
+    else {
+        ssize_t need = len;
+        err = ei_read_fill_ctx_t__(cbs, ctx, (char *) bufp, &len, tmo);
+        if (err) {
+            EI_CONN_SAVE_ERRNO__(err);
+            return ERL_ERROR;
+        }
+        if (len != need) {
+            erl_errno = EIO;
+            return ERL_ERROR;
+        }
     }
     
-    return len;
+    return (int) len;
     
 }
 
@@ -1112,36 +1518,11 @@ int ei_rpc_to(ei_cnode *ec, int fd, char *mod, char *fun,
 int ei_rpc_from(ei_cnode *ec, int fd, int timeout, erlang_msg *msg,
 		ei_x_buff *x) 
 {
-    fd_set readmask;
-    struct timeval tv;
-    struct timeval *t = NULL;
-    
-    if (timeout >= 0) {
-	tv.tv_sec = timeout / 1000;
-	tv.tv_usec = (timeout % 1000) * 1000;
-	t = &tv;
-    }
-    
-    FD_ZERO(&readmask);
-    FD_SET(fd,&readmask);
-    
-    switch (select(fd+1, &readmask, NULL, NULL, t)) {
-    case -1: 
-	erl_errno = EIO;
-	return ERL_ERROR;
-	
-    case 0:
-	erl_errno = ETIMEDOUT;
-	return ERL_TIMEOUT;
-	
-    default:
-	if (FD_ISSET(fd, &readmask)) {
-	    return ei_xreceive_msg(fd, msg, x);
-	} else {
-	    erl_errno = EIO;
-	    return ERL_ERROR;
-	}
-    }
+    unsigned tmo = timeout < 0 ? EI_SCLBK_INF_TMO : (unsigned) timeout;
+    int res = ei_xreceive_msg_tmo(fd, msg, x, tmo);
+    if (res < 0 && erl_errno == ETIMEDOUT)
+        return ERL_TIMEOUT;
+    return res;
 } /* rpc_from */
 
   /*
@@ -1295,19 +1676,34 @@ static char *hex(char digest[16], char buff[33])
     return buff;
 }
 
-static int read_2byte_package(int fd, char **buf, int *buflen, 
-			      int *is_static, unsigned ms)
+static int read_hs_package(ei_socket_callbacks *cbs, void *ctx,
+                           int pkt_sz, char **buf, int *buflen, 
+                           int *is_static, unsigned ms)
 {
-    unsigned char nbuf[2];
+    unsigned char nbuf[4];
     unsigned char *x = nbuf;
-    unsigned len;
-    int res;
-    
-    if((res = ei_read_fill_t(fd, (char *)nbuf, 2, ms)) != 2) {
-	erl_errno = (res == -2) ? ETIMEDOUT : EIO;
+    ssize_t len, need;
+    int err;
+
+    len = (ssize_t) pkt_sz;
+    err = ei_read_fill_ctx_t__(cbs, ctx, (char *)nbuf, &len, ms);
+    if (!err && len != (ssize_t) pkt_sz)
+        err = EIO;
+    if (err) {
+        EI_CONN_SAVE_ERRNO__(err);
 	return -1;
     }
-    len = get16be(x);
+    
+    switch (pkt_sz) {
+    case 2:
+        len = get16be(x);
+        break;
+    case 4:
+        len = get32be(x);
+        break;
+    default:
+        return -1;
+    }
     
     if (len > *buflen) {
 	if (*is_static) {
@@ -1329,20 +1725,26 @@ static int read_2byte_package(int fd, char **buf, int *buflen,
 	    *buflen = len;
 	}
     }
-    if ((res = ei_read_fill_t(fd, *buf, len, ms)) != len) {
-	erl_errno = (res == -2) ? ETIMEDOUT : EIO;
+    need = len;
+    err = ei_read_fill_ctx_t__(cbs, ctx, *buf, &len, ms);
+    if (!err && len != need)
+        err = EIO;
+    if (err) {
+        EI_CONN_SAVE_ERRNO__(err);
 	return -1;
     }
     return len;
 }
 
 
-static int send_status(int fd, char *status, unsigned ms)
+static int send_status(ei_socket_callbacks *cbs, void *ctx,
+                       int pkt_sz, char *status, unsigned ms)
 {
     char *buf, *s;
     char dbuf[DEFBUF_SIZ];
-    int siz = strlen(status) + 1 + 2;
-    int res;
+    int siz = strlen(status) + 1 + pkt_sz;
+    int err;
+    ssize_t len;
 
     buf = (siz > DEFBUF_SIZ) ? malloc(siz) : dbuf;
     if (!buf) {
@@ -1350,14 +1752,28 @@ static int send_status(int fd, char *status, unsigned ms)
 	return -1;
     }
     s = buf;
-    put16be(s,siz - 2);
+    switch (pkt_sz) {
+    case 2:
+        put16be(s,siz - 2);
+        break;
+    case 4:
+        put32be(s,siz - 4);
+        break;
+    default:
+        return -1;
+    }
     put8(s, 's');
     memcpy(s, status, strlen(status));
-    if ((res = ei_write_fill_t(fd, buf, siz, ms)) != siz) {
-	EI_TRACE_ERR0("send_status","-> SEND_STATUS socket write failed");
+    len = (ssize_t) siz;
+    err = ei_write_fill_ctx_t__(cbs, ctx, buf, &len, ms);
+    if (!err && len != (ssize_t) siz)
+        err = EIO;
+    if (err) {
+	EI_TRACE_ERR2("send_status","-> SEND_STATUS socket write failed: %s (%d)",
+                      estr(err), err);
 	if (buf != dbuf)
-	    free(buf);
-	erl_errno = (res == -2) ? ETIMEDOUT : EIO;
+	    free(buf);        
+        EI_CONN_SAVE_ERRNO__(err);
 	return -1;
     }
     EI_TRACE_CONN1("send_status","-> SEND_STATUS (%s)",status);
@@ -1367,7 +1783,8 @@ static int send_status(int fd, char *status, unsigned ms)
     return 0;
 }
 
-static int recv_status(int fd, unsigned ms)
+static int recv_status(ei_socket_callbacks *cbs, void *ctx,
+                       int pkt_sz, unsigned ms)
 {
     char dbuf[DEFBUF_SIZ];
     char *buf = dbuf;
@@ -1375,7 +1792,8 @@ static int recv_status(int fd, unsigned ms)
     int buflen = DEFBUF_SIZ;
     int rlen;
     
-    if ((rlen = read_2byte_package(fd, &buf, &buflen, &is_static, ms)) <= 0) {
+    if ((rlen = read_hs_package(cbs, ctx, pkt_sz,
+                                &buf, &buflen, &is_static, ms)) <= 0) {
 	EI_TRACE_ERR1("recv_status",
 		      "<- RECV_STATUS socket read failed (%d)", rlen);
 	goto error;
@@ -1396,7 +1814,10 @@ error:
     return -1;
 }
 
-static int send_name_or_challenge(int fd, char *nodename,
+static int send_name_or_challenge(ei_socket_callbacks *cbs,
+                                  void *ctx,
+                                  int pkt_sz,
+                                  char *nodename,
 				  int f_chall,
 				  unsigned challenge,
 				  unsigned version,
@@ -1405,9 +1826,10 @@ static int send_name_or_challenge(int fd, char *nodename,
     char *buf;
     unsigned char *s;
     char dbuf[DEFBUF_SIZ];
-    int siz = 2 + 1 + 2 + 4 + strlen(nodename);
+    int siz = pkt_sz + 1 + 2 + 4 + strlen(nodename);
     const char* function[] = {"SEND_NAME", "SEND_CHALLENGE"};
-    int res;
+    int err;
+    ssize_t len;
 
     if (f_chall)
 	siz += 4;
@@ -1417,7 +1839,16 @@ static int send_name_or_challenge(int fd, char *nodename,
 	return -1;
     }
     s = (unsigned char *)buf;
-    put16be(s,siz - 2);
+    switch (pkt_sz) {
+    case 2:
+        put16be(s,siz - 2);
+        break;
+    case 4:
+        put32be(s,siz - 4);
+        break;
+    default:
+        return -1;
+    }
     put8(s, 'n');
     put16be(s, version);
     put32be(s, (DFLAG_EXTENDED_REFERENCES
@@ -1433,13 +1864,16 @@ static int send_name_or_challenge(int fd, char *nodename,
     if (f_chall)
 	put32be(s, challenge);
     memcpy(s, nodename, strlen(nodename));
-    
-    if ((res = ei_write_fill_t(fd, buf, siz, ms)) != siz) {
+    len = (ssize_t) siz;
+    err = ei_write_fill_ctx_t__(cbs, ctx, buf, &len, ms);
+    if (!err && len != (ssize_t) siz)
+        err = EIO;
+    if (err) {
 	EI_TRACE_ERR1("send_name_or_challenge",
 		      "-> %s socket write failed", function[f_chall]);
 	if (buf != dbuf)
 	    free(buf);
-	erl_errno = (res == -2) ? ETIMEDOUT : EIO;
+        EI_CONN_SAVE_ERRNO__(err);
 	return -1;
     }
     
@@ -1448,9 +1882,9 @@ static int send_name_or_challenge(int fd, char *nodename,
     return 0;
 }
 
-static int recv_challenge(int fd, unsigned *challenge, 
-			  unsigned *version,
-			  unsigned *flags, ErlConnect *namebuf, unsigned ms)
+static int recv_challenge(ei_socket_callbacks *cbs, void *ctx,
+                          int pkt_sz, unsigned *challenge, unsigned *version,
+			  unsigned *flags, char *namebuf, unsigned ms)
 {
     char dbuf[DEFBUF_SIZ];
     char *buf = dbuf;
@@ -1458,13 +1892,13 @@ static int recv_challenge(int fd, unsigned *challenge,
     int buflen = DEFBUF_SIZ;
     int rlen;
     char *s;
-    struct sockaddr_in sin;
-    socklen_t sin_len = sizeof(sin);
     char tag;
-    
+    char tmp_nodename[MAXNODELEN+1];
+
     erl_errno = EIO;		/* Default */
 
-    if ((rlen = read_2byte_package(fd, &buf, &buflen, &is_static, ms)) <= 0) {
+    if ((rlen = read_hs_package(cbs, ctx, pkt_sz, &buf, &buflen,
+                                &is_static, ms)) <= 0) {
 	EI_TRACE_ERR1("recv_challenge",
 		      "<- RECV_CHALLENGE socket read failed (%d)",rlen);
 	goto error;
@@ -1505,22 +1939,19 @@ static int recv_challenge(int fd, unsigned *challenge,
 	goto error;
     }
 
-    if (getpeername(fd, (struct sockaddr *) &sin, &sin_len) < 0) {
-	EI_TRACE_ERR0("recv_challenge","<- RECV_CHALLENGE can't get peername");
-	erl_errno = errno;
-	goto error;
-    }
-    memcpy(namebuf->ipadr, &(sin.sin_addr.s_addr), 
-	sizeof(sin.sin_addr.s_addr));
-    memcpy(namebuf->nodename, s, rlen - 11);
-    namebuf->nodename[rlen - 11] = '\0';
+    if (!namebuf)
+        namebuf = &tmp_nodename[0];
+    
+    memcpy(namebuf, s, rlen - 11);
+    namebuf[rlen - 11] = '\0';
+    
     if (!is_static)
 	free(buf);
     EI_TRACE_CONN4("recv_challenge","<- RECV_CHALLENGE (ok) node = %s, "
 	    "version = %u, "
 	    "flags = %u, "
 	    "challenge = %d",
-	    namebuf->nodename,
+	    namebuf,
 	    *version,
 	    *flags,
 	    *challenge
@@ -1533,24 +1964,40 @@ error:
     return -1;
 }
 
-static int send_challenge_reply(int fd, unsigned char digest[16], 
+static int send_challenge_reply(ei_socket_callbacks *cbs, void *ctx,
+                                int pkt_sz, unsigned char digest[16], 
 				unsigned challenge, unsigned ms) 
 {
     char *s;
     char buf[DEFBUF_SIZ];
-    int siz = 2 + 1 + 4 + 16;
-    int res;
+    int siz = pkt_sz + 1 + 4 + 16;
+    int err;
+    ssize_t len;
 
     s = buf;
-    put16be(s,siz - 2);
+    switch (pkt_sz) {
+    case 2:
+        put16be(s,siz - 2);
+        break;
+    case 4:
+        put32be(s,siz - 4);
+        break;
+    default:
+        return -1;
+    }
     put8(s, 'r');
     put32be(s, challenge);
     memcpy(s, digest, 16);
-    
-    if ((res = ei_write_fill_t(fd, buf, siz, ms)) != siz) {
-	EI_TRACE_ERR0("send_challenge_reply",
-		      "-> SEND_CHALLENGE_REPLY socket write failed");
-	erl_errno = (res == -2) ? ETIMEDOUT : EIO;
+
+    len = (ssize_t) siz;
+    err = ei_write_fill_ctx_t__(cbs, ctx, buf, &len, ms);
+    if (!err && len != (ssize_t) siz)
+        err = EIO;
+    if (err) {
+	EI_TRACE_ERR2("send_challenge_reply",
+		      "-> SEND_CHALLENGE_REPLY socket write failed: %s (%d)",
+                      estr(err), err);
+        EI_CONN_SAVE_ERRNO__(err);
 	return -1;
     }
     
@@ -1563,11 +2010,13 @@ static int send_challenge_reply(int fd, unsigned char digest[16],
     return 0;
 }
 
-static int recv_challenge_reply (int fd, 
-				 unsigned our_challenge,
-				 char cookie[], 
-				 unsigned *her_challenge,
-				 unsigned ms)
+static int recv_challenge_reply(ei_socket_callbacks *cbs,
+                                void *ctx,
+                                int pkt_sz,
+                                unsigned our_challenge,
+                                char cookie[], 
+                                unsigned *her_challenge,
+                                unsigned ms)
 {
     char dbuf[DEFBUF_SIZ];
     char *buf = dbuf;
@@ -1580,7 +2029,7 @@ static int recv_challenge_reply (int fd,
     
     erl_errno = EIO;		/* Default */
 
-    if ((rlen = read_2byte_package(fd, &buf, &buflen, &is_static, ms)) != 21) {
+    if ((rlen = read_hs_package(cbs, ctx, pkt_sz, &buf, &buflen, &is_static, ms)) != 21) {
 	EI_TRACE_ERR1("recv_challenge_reply",
 		      "<- RECV_CHALLENGE_REPLY socket read failed (%d)",rlen);
 	goto error;
@@ -1620,23 +2069,38 @@ error:
     return -1;
 }
 
-static int send_challenge_ack(int fd, unsigned char digest[16], unsigned ms) 
+static int send_challenge_ack(ei_socket_callbacks *cbs, void *ctx, int pkt_sz,
+                              unsigned char digest[16], unsigned ms) 
 {
     char *s;
     char buf[DEFBUF_SIZ];
-    int siz = 2 + 1 + 16;
-    int res;
+    int siz = pkt_sz + 1 + 16;
+    int err;
+    ssize_t len;
 
     s = buf;
-    
-    put16be(s,siz - 2);
+    switch (pkt_sz) {
+    case 2:
+        put16be(s,siz - 2);
+        break;
+    case 4:
+        put32be(s,siz - 4);
+        break;
+    default:
+        return -1;
+    }
     put8(s, 'a');
     memcpy(s, digest, 16);
 
-    if ((res = ei_write_fill_t(fd, buf, siz, ms)) != siz) {
-	EI_TRACE_ERR0("recv_challenge_reply",
-		      "-> SEND_CHALLENGE_ACK socket write failed");
-	erl_errno = (res == -2) ? ETIMEDOUT : EIO;
+    len = (ssize_t) siz;
+    err = ei_write_fill_ctx_t__(cbs, ctx, buf, &len, ms);
+    if (!err && len != (ssize_t) siz)
+        err = EIO;
+    if (err) {
+	EI_TRACE_ERR2("recv_challenge_reply",
+		      "-> SEND_CHALLENGE_ACK socket write failed: %s (%d)",
+                      estr(err), err);
+        EI_CONN_SAVE_ERRNO__(err);
 	return -1;
     }
     
@@ -1649,8 +2113,8 @@ static int send_challenge_ack(int fd, unsigned char digest[16], unsigned ms)
     return 0;
 }
 
-static int recv_challenge_ack(int fd, 
-			      unsigned our_challenge,
+static int recv_challenge_ack(ei_socket_callbacks *cbs, void *ctx,
+			      int pkt_sz, unsigned our_challenge,
 			      char cookie[], unsigned ms)
 {
     char dbuf[DEFBUF_SIZ];
@@ -1664,7 +2128,7 @@ static int recv_challenge_ack(int fd,
     
     erl_errno = EIO;		/* Default */
 
-    if ((rlen = read_2byte_package(fd, &buf, &buflen, &is_static, ms)) != 17) {
+    if ((rlen = read_hs_package(cbs, ctx, pkt_sz, &buf, &buflen, &is_static, ms)) != 17) {
 	EI_TRACE_ERR1("recv_challenge_ack",
 		      "<- RECV_CHALLENGE_ACK socket read failed (%d)",rlen);
 	goto error;
@@ -1701,20 +2165,24 @@ error:
     return -1;
 }
 
-static int send_name(int fd, char *nodename, unsigned version, unsigned ms) 
+static int send_name(ei_socket_callbacks *cbs, void *ctx, int pkt_sz,
+                     char *nodename, unsigned version, unsigned ms) 
 {
-    return send_name_or_challenge(fd, nodename, 0, 0, version, ms);
+    return send_name_or_challenge(cbs, ctx, pkt_sz, nodename, 0,
+                                  0, version, ms);
 }
 
-static int send_challenge(int fd, char *nodename, 
-			  unsigned challenge, unsigned version, unsigned ms)
+static int send_challenge(ei_socket_callbacks *cbs, void *ctx, int pkt_sz,
+                          char *nodename, unsigned challenge, unsigned version,
+                          unsigned ms)
 {
-    return send_name_or_challenge(fd, nodename, 1, challenge, version, ms);
+    return send_name_or_challenge(cbs, ctx, pkt_sz, nodename, 1,
+                                  challenge, version, ms);
 }
 
-static int recv_name(int fd, 
-		     unsigned *version,
-		     unsigned *flags, ErlConnect *namebuf, unsigned ms)
+static int recv_name(ei_socket_callbacks *cbs, void *ctx,
+                     int pkt_sz, unsigned *version,
+		     unsigned *flags, char *namebuf, unsigned ms)
 {
     char dbuf[DEFBUF_SIZ];
     char *buf = dbuf;
@@ -1722,13 +2190,13 @@ static int recv_name(int fd,
     int buflen = DEFBUF_SIZ;
     int rlen;
     char *s;
-    struct sockaddr_in sin;
-    socklen_t sin_len = sizeof(sin);
+    char tmp_nodename[MAXNODELEN+1];
     char tag;
     
     erl_errno = EIO;		/* Default */
 
-    if ((rlen = read_2byte_package(fd, &buf, &buflen, &is_static, ms)) <= 0) {
+    if ((rlen = read_hs_package(cbs, ctx, pkt_sz, &buf, &buflen,
+                                &is_static, ms)) <= 0) {
 	EI_TRACE_ERR1("recv_name","<- RECV_NAME socket read failed (%d)",rlen);
 	goto error;
     }
@@ -1759,21 +2227,18 @@ static int recv_name(int fd,
 	erl_errno = EIO;
 	goto error;
     }
-	  
-    if (getpeername(fd, (struct sockaddr *) &sin, &sin_len) < 0) {
-	EI_TRACE_ERR0("recv_name","<- RECV_NAME can't get peername");
-	erl_errno = errno;
-	goto error;
-    }
-    memcpy(namebuf->ipadr, &(sin.sin_addr.s_addr), 
-	sizeof(sin.sin_addr.s_addr));
-    memcpy(namebuf->nodename, s, rlen - 7);
-    namebuf->nodename[rlen - 7] = '\0';
+
+    if (!namebuf)
+        namebuf = &tmp_nodename[0];
+    
+    memcpy(namebuf, s, rlen - 7);
+    namebuf[rlen - 7] = '\0';
+
     if (!is_static)
 	free(buf);
     EI_TRACE_CONN3("recv_name",
 		   "<- RECV_NAME (ok) node = %s, version = %u, flags = %u",
-		   namebuf->nodename,*version,*flags);
+		   namebuf,*version,*flags);
     erl_errno = 0;
     return 0;
     
@@ -1867,3 +2332,4 @@ static int get_cookie(char *buf, int bufsize)
 
     return 1;			/* Success! */
 }
+
diff --git a/lib/erl_interface/src/connect/eirecv.c b/lib/erl_interface/src/connect/eirecv.c
index 7b9dbfc387..47eea06ced 100644
--- a/lib/erl_interface/src/connect/eirecv.c
+++ b/lib/erl_interface/src/connect/eirecv.c
@@ -60,22 +60,36 @@ ei_recv_internal (int fd,
   int arity;
   int version;
   int index = 0;
-  int i = 0;
-  int res;
+  int err;
   int show_this_msg = 0;
+  ei_socket_callbacks *cbs;
+  void *ctx;
+  ssize_t rlen;
+  unsigned tmo = ms == 0 ? EI_SCLBK_INF_TMO : ms;
+
+  err = EI_GET_CBS_CTX__(&cbs, &ctx, fd);
+  if (err) {
+      EI_CONN_SAVE_ERRNO__(err);
+      return -1;
+  }
 
   /* get length field */
-  if ((res = ei_read_fill_t(fd, header, 4, ms)) != 4) 
-  {
-      erl_errno = (res == -2) ? ETIMEDOUT : EIO;
+  rlen = 4;
+  err = ei_read_fill_ctx_t__(cbs, ctx, header, &rlen, tmo);
+  if (!err && rlen != 4)
+      err = EIO;
+  if (err) {
+      EI_CONN_SAVE_ERRNO__(err);
       return -1;
   }
+  
   len = get32be(s);
 
   /* got tick - respond and return */
   if (!len) {
     char tock[] = {0,0,0,0};
-    ei_write_fill_t(fd, tock, sizeof(tock), ms); /* Failure no problem */
+    ssize_t wlen = sizeof(tock);
+    ei_write_fill_ctx_t__(cbs, ctx, tock, &wlen, tmo); /* Failure no problem */
     *msglenp = 0;
     return 0;			/* maybe flag ERL_EAGAIN [sverkerw] */
   }
@@ -86,9 +100,12 @@ ei_recv_internal (int fd,
   ei_trace(-1,NULL);
   
   /* read enough to get at least entire header */
-  bytesread = (len > EIRECVBUF ? EIRECVBUF : len); 
-  if ((i = ei_read_fill_t(fd,header,bytesread,ms)) != bytesread) {
-      erl_errno = (i == -2) ? ETIMEDOUT : EIO;
+  rlen = bytesread = (len > EIRECVBUF ? EIRECVBUF : len);
+  err = ei_read_fill_ctx_t__(cbs, ctx, header, &rlen, tmo);
+  if (!err && rlen != bytesread)
+      err = EIO;
+  if (err) {
+      EI_CONN_SAVE_ERRNO__(err);
       return -1;
   }
 
@@ -212,12 +229,17 @@ ei_recv_internal (int fd,
    */
   if (msglen > *bufsz) {
     if (staticbufp) {
-      int sz = EIRECVBUF;
       /* flush in rest of packet */
       while (remain > 0) {
-	if (remain < sz) sz = remain;
-	if ((i=ei_read_fill_t(fd,header,sz,ms)) <= 0) break;
-	remain -= i;
+          rlen = remain > EIRECVBUF ? EIRECVBUF : remain;
+          err = ei_read_fill_ctx_t__(cbs, ctx, header, &rlen, tmo);
+          if (err) {
+              EI_CONN_SAVE_ERRNO__(err);
+              return -1;
+          }
+          if (rlen == 0)
+              break;
+          remain -= rlen;
       }
       erl_errno = EMSGSIZE;
       return -1;
@@ -247,11 +269,15 @@ ei_recv_internal (int fd,
 
   /* read the rest of the message into callers buffer */
   if (remain > 0) {
-    if ((i = ei_read_fill_t(fd,mbuf+bytesread-index,remain,ms)) != remain) {
-      *msglenp = bytesread-index+1; /* actual bytes in users buffer */
-      erl_errno = (i == -2) ? ETIMEDOUT : EIO;
-      return -1;
-    }
+      rlen = remain;
+      err = ei_read_fill_ctx_t__(cbs, ctx, mbuf+bytesread-index, &rlen, tmo);
+      if (!err && rlen != remain)
+          err = EIO;
+      if (err) {
+          *msglenp = bytesread-index+1; /* actual bytes in users buffer */
+          EI_CONN_SAVE_ERRNO__(err);
+          return -1;
+      }
   }
 
   if (show_this_msg)
diff --git a/lib/erl_interface/src/connect/send.c b/lib/erl_interface/src/connect/send.c
index 37d7db6d68..d97532d123 100644
--- a/lib/erl_interface/src/connect/send.c
+++ b/lib/erl_interface/src/connect/send.c
@@ -58,10 +58,17 @@ int ei_send_encoded_tmo(int fd, const erlang_pid *to,
     char *s, header[1200]; /* see size calculation below */
     erlang_trace *token = NULL;
     int index = 5; /* reserve 5 bytes for control message */
-    int res;
-#ifdef HAVE_WRITEV
-    struct iovec v[2];
-#endif
+    int err;
+    ei_socket_callbacks *cbs;
+    void *ctx;
+    ssize_t len, tot_len;
+    unsigned tmo = ms == 0 ? EI_SCLBK_INF_TMO : ms;
+
+    err = EI_GET_CBS_CTX__(&cbs, &ctx, fd);
+    if (err) {
+        EI_CONN_SAVE_ERRNO__(err);
+        return ERL_ERROR;
+    }
 
     /* are we tracing? */
     /* check that he can receive trace tokens first */
@@ -91,30 +98,47 @@ int ei_send_encoded_tmo(int fd, const erlang_pid *to,
     if (ei_tracelevel >= 4)
 	ei_show_sendmsg(stderr,header,msg);
 
-#ifdef HAVE_WRITEV
-    
-    v[0].iov_base = (char *)header;
-    v[0].iov_len = index;
-    v[1].iov_base = (char *)msg;
-    v[1].iov_len = msglen;
-    
-    if ((res = ei_writev_fill_t(fd,v,2,ms)) != index+msglen) {
-	erl_errno = (res == -2) ? ETIMEDOUT : EIO;
-	return -1;
-    }
-  
-#else  /* !HAVE_WRITEV */
-  
-    if ((res = ei_write_fill_t(fd,header,index,ms)) != index) { 
-	erl_errno = (res == -2) ? ETIMEDOUT : EIO;
-	return -1;
+
+#ifdef EI_HAVE_STRUCT_IOVEC__
+    if (ei_socket_callbacks_have_writev__(cbs)) {
+        struct iovec v[2];
+
+        v[0].iov_base = (char *)header;
+        v[0].iov_len = index;
+        v[1].iov_base = (char *)msg;
+        v[1].iov_len = msglen;
+
+        len = tot_len = (ssize_t) index+msglen;
+        err = ei_writev_fill_ctx_t__(cbs, ctx, v, 2, &len, tmo);
+        if (!err && len != tot_len)
+            err = EIO;
+        if (err) {
+            EI_CONN_SAVE_ERRNO__(err);
+            return -1;
+        }
+
+        return 0;
     }
-    if ((res = ei_write_fill_t(fd,msg,msglen,ms)) != msglen) { 
-	erl_errno = (res == -2) ? ETIMEDOUT : EIO;
-	return -1;
+#endif /* EI_HAVE_STRUCT_IOVEC__ */
+
+    /* no writev() */
+    len = tot_len = (ssize_t) index;
+    err = ei_write_fill_ctx_t__(cbs, ctx, header, &len, tmo);
+    if (!err && len != tot_len)
+        err = EIO;
+    if (err) {
+        EI_CONN_SAVE_ERRNO__(err);
+        return -1;
     }
 
-#endif  /* !HAVE_WRITEV */
+    len = tot_len = (ssize_t) msglen;
+    err = ei_write_fill_ctx_t__(cbs, ctx, msg, &len, tmo);
+    if (!err && len != tot_len)
+        err = EIO;
+    if (err) {
+        EI_CONN_SAVE_ERRNO__(err);
+        return -1;
+    }
 
     return 0;
 }
diff --git a/lib/erl_interface/src/connect/send_exit.c b/lib/erl_interface/src/connect/send_exit.c
index 2e298e3221..b4f7e14c7f 100644
--- a/lib/erl_interface/src/connect/send_exit.c
+++ b/lib/erl_interface/src/connect/send_exit.c
@@ -55,6 +55,17 @@ int ei_send_exit_tmo(int fd, const erlang_pid *from, const erlang_pid *to,
   char *s;
   int index = 0;
   int len = strlen(reason) + 1080; /* see below */
+  ei_socket_callbacks *cbs;
+  void *ctx;
+  int err;
+  ssize_t wlen;
+  unsigned tmo = ms == 0 ? EI_SCLBK_INF_TMO : ms;
+  
+  err = EI_GET_CBS_CTX__(&cbs, &ctx, fd);
+  if (err) {
+      EI_CONN_SAVE_ERRNO__(err);
+      return ERL_ERROR;
+  }
 
   if (len > EISMALLBUF)
     if (!(dbuf = malloc(len)))
@@ -92,10 +103,16 @@ int ei_send_exit_tmo(int fd, const erlang_pid *from, const erlang_pid *to,
   if (ei_tracelevel >= 4)
       ei_show_sendmsg(stderr,msgbuf,NULL);
 
-  ei_write_fill_t(fd,msgbuf,index,ms); 
-  /* FIXME ignore timeout etc? erl_errno?! */
-
-  if (dbuf) free(dbuf);
+  wlen = (ssize_t) index;
+  err = ei_write_fill_ctx_t__(cbs, ctx, msgbuf, &wlen, tmo);
+  if (!err && wlen != (ssize_t) index)
+      err = EIO;
+  if (dbuf)
+      free(dbuf);
+  if (err) {
+      EI_CONN_SAVE_ERRNO__(err);
+      return ERL_ERROR;
+  }
   return 0;
 }
 
diff --git a/lib/erl_interface/src/connect/send_reg.c b/lib/erl_interface/src/connect/send_reg.c
index 62478f042d..80d61e57b5 100644
--- a/lib/erl_interface/src/connect/send_reg.c
+++ b/lib/erl_interface/src/connect/send_reg.c
@@ -51,11 +51,17 @@ int ei_send_reg_encoded_tmo(int fd, const erlang_pid *from,
     char *s, header[1400]; /* see size calculation below */
     erlang_trace *token = NULL;
     int index = 5; /* reserve 5 bytes for control message */
-    int res;
+    int err;
+    ei_socket_callbacks *cbs;
+    void *ctx;
+    ssize_t len, tot_len;
+    unsigned tmo = ms == 0 ? EI_SCLBK_INF_TMO : ms;
 
-#ifdef HAVE_WRITEV
-    struct iovec v[2];
-#endif
+    err = EI_GET_CBS_CTX__(&cbs, &ctx, fd);
+    if (err) {
+        EI_CONN_SAVE_ERRNO__(err);
+        return ERL_ERROR;
+    }
     
     /* are we tracing? */
     /* check that he can receive trace tokens first */
@@ -86,29 +92,45 @@ int ei_send_reg_encoded_tmo(int fd, const erlang_pid *from,
     if (ei_tracelevel >= 4) 
 	ei_show_sendmsg(stderr,header,msg);
 
-#ifdef HAVE_WRITEV
+#ifdef EI_HAVE_STRUCT_IOVEC__
+    if (ei_socket_callbacks_have_writev__(cbs)) {
+        struct iovec v[2];
 
-    v[0].iov_base = (char *)header;
-    v[0].iov_len = index;
-    v[1].iov_base = (char *)msg;
-    v[1].iov_len = msglen;
+        v[0].iov_base = (char *)header;
+        v[0].iov_len = index;
+        v[1].iov_base = (char *)msg;
+        v[1].iov_len = msglen;
     
-    if ((res = ei_writev_fill_t(fd,v,2,ms)) != index+msglen) {
-	erl_errno = (res == -2) ? ETIMEDOUT : EIO;
-	return -1;
+        len = tot_len = (ssize_t) index+msglen;
+        err = ei_writev_fill_ctx_t__(cbs, ctx, v, 2, &len, tmo);
+        if (!err && len != tot_len)
+            err = EIO;
+        if (err) {
+            EI_CONN_SAVE_ERRNO__(err);
+            return -1;
+        }
+        return 0;
     }
-#else
-    
+#endif /* EI_HAVE_STRUCT_IOVEC__ */
+
     /* no writev() */
-    if ((res = ei_write_fill_t(fd,header,index,ms)) != index) {
-	erl_errno = (res == -2) ? ETIMEDOUT : EIO;
-	return -1;
+    len = tot_len = (ssize_t) index;
+    err = ei_write_fill_ctx_t__(cbs, ctx, header, &len, tmo);
+    if (!err && len != tot_len)
+        err = EIO;
+    if (err) {
+        EI_CONN_SAVE_ERRNO__(err);
+        return -1;
     }
-    if ((res = ei_write_fill_t(fd,msg,msglen,ms)) != msglen) {
-	erl_errno = (res == -2) ? ETIMEDOUT : EIO;
-	return -1;
+
+    len = tot_len = (ssize_t) msglen;
+    err = ei_write_fill_ctx_t__(cbs, ctx, msg, &len, tmo);
+    if (!err && len != tot_len)
+        err = EIO;
+    if (err) {
+        EI_CONN_SAVE_ERRNO__(err);
+        return -1;
     }
-#endif
     
     return 0;
 }
diff --git a/lib/erl_interface/src/epmd/epmd_port.c b/lib/erl_interface/src/epmd/epmd_port.c
index 2ec418b24a..492c3fb3aa 100644
--- a/lib/erl_interface/src/epmd/epmd_port.c
+++ b/lib/erl_interface/src/epmd/epmd_port.c
@@ -62,31 +62,38 @@
 int ei_epmd_connect_tmo(struct in_addr *inaddr, unsigned ms)
 {
   static unsigned int epmd_port = 0;
-  struct sockaddr_in saddr;
-  int sd;
-  int res;
+  int port, sd, err;
+  struct in_addr ip_addr;
+  struct sockaddr_in addr;
+  unsigned tmo = ms == 0 ? EI_SCLBK_INF_TMO : ms;
+
+  err = ei_socket__(&sd);
+  if (err) {
+      erl_errno = err;
+      return -1;
+  }
 
   if (epmd_port == 0) {
       char* port_str = getenv("ERL_EPMD_PORT");
       epmd_port = (port_str != NULL) ? atoi(port_str) : EPMD_PORT;
   }
-  memset(&saddr, 0, sizeof(saddr)); 
-  saddr.sin_port = htons(epmd_port);
-  saddr.sin_family = AF_INET;
 
-  if (!inaddr) saddr.sin_addr.s_addr = htonl(INADDR_LOOPBACK);
-  else memmove(&saddr.sin_addr,inaddr,sizeof(saddr.sin_addr));
+  port = (int) epmd_port;
 
-  if (((sd = socket(PF_INET, SOCK_STREAM, 0)) < 0))
-  {
-      erl_errno = errno;
-      return -1;
+  if (!inaddr) {      
+      ip_addr.s_addr = htonl(INADDR_LOOPBACK);
+      inaddr = &ip_addr;
   }
+  
+  memset((void *) &addr, 0, sizeof(struct sockaddr_in));
+  memcpy((void *) &addr.sin_addr, (void *) inaddr, sizeof(addr.sin_addr));
+  addr.sin_family = AF_INET;
+  addr.sin_port = htons(port);
 
-  if ((res = ei_connect_t(sd,(struct sockaddr *)&saddr,sizeof(saddr),ms)) < 0) 
-  {
-      erl_errno = (res == -2) ? ETIMEDOUT : errno;
-      closesocket(sd);
+  err = ei_connect_t__(sd, (void *) &addr, sizeof(addr), tmo);
+  if (err) {
+      erl_errno = err;
+      ei_close__(sd);
       return -1;
   }
 
@@ -104,6 +111,9 @@ static int ei_epmd_r4_port (struct in_addr *addr, const char *alive,
   int port;
   int dist_high, dist_low, proto;
   int res;
+  int err;
+  ssize_t dlen;
+  unsigned tmo = ms == 0 ? EI_SCLBK_INF_TMO : ms;
 #if defined(VXWORKS)
   char ntoabuf[32];
 #endif
@@ -124,10 +134,14 @@ static int ei_epmd_r4_port (struct in_addr *addr, const char *alive,
       return -1;
   }
 
-  if ((res = ei_write_fill_t(fd, buf, len+2, ms)) != len+2) {
-    closesocket(fd);
-    erl_errno = (res == -2) ? ETIMEDOUT : EIO;
-    return -1;
+  dlen = len + 2;
+  err = ei_write_fill_t__(fd, buf, &dlen, tmo);
+  if (!err && dlen != (ssize_t) len + 2)
+      erl_errno = EIO;
+  if (err) {
+      ei_close__(fd);
+      EI_CONN_SAVE_ERRNO__(err);
+      return -1;
   }
 
 #ifdef VXWORKS
@@ -142,12 +156,15 @@ static int ei_epmd_r4_port (struct in_addr *addr, const char *alive,
 		 "-> PORT2_REQ alive=%s ip=%s",alive,inet_ntoa(*addr));
 #endif
 
-  /* read first two bytes (response type, response) */
-  if ((res = ei_read_fill_t(fd, buf, 2, ms)) != 2) {
-    EI_TRACE_ERR0("ei_epmd_r4_port","<- CLOSE");
-    erl_errno = (res == -2) ? ETIMEDOUT : EIO;
-    closesocket(fd);
-    return -2;			/* version mismatch */
+  dlen = (ssize_t) 2;
+  err = ei_read_fill_t__(fd, buf, &dlen, tmo);
+  if (!err && dlen != (ssize_t) 2)
+      erl_errno = EIO;
+  if (err) {
+      EI_TRACE_ERR0("ei_epmd_r4_port","<- CLOSE");
+      ei_close__(fd);
+      EI_CONN_SAVE_ERRNO__(err);
+      return -2;
   }
 
   s = buf;
@@ -156,7 +173,7 @@ static int ei_epmd_r4_port (struct in_addr *addr, const char *alive,
   if (res != EI_EPMD_PORT2_RESP) { /* response type */
     EI_TRACE_ERR1("ei_epmd_r4_port","<- unknown (%d)",res);
     EI_TRACE_ERR0("ei_epmd_r4_port","-> CLOSE");
-    closesocket(fd);
+    ei_close__(fd);
     erl_errno = EIO;
     return -1;
   }
@@ -167,7 +184,7 @@ static int ei_epmd_r4_port (struct in_addr *addr, const char *alive,
   if ((res = get8(s))) {
     /* got negative response */
     EI_TRACE_ERR1("ei_epmd_r4_port","<- PORT2_RESP result=%d (failure)",res);
-    closesocket(fd);
+    ei_close__(fd);
     erl_errno = EIO;
     return -1;
   }
@@ -175,14 +192,18 @@ static int ei_epmd_r4_port (struct in_addr *addr, const char *alive,
   EI_TRACE_CONN1("ei_epmd_r4_port","<- PORT2_RESP result=%d (ok)",res);
 
   /* expecting remaining 8 bytes */
-  if ((res = ei_read_fill_t(fd,buf,8,ms)) != 8) {
+  dlen = (ssize_t) 8;
+  err = ei_read_fill_t__(fd, buf, &dlen, tmo);
+  if (!err && dlen != (ssize_t) 8)
+      err = EIO;
+  if (err) {
     EI_TRACE_ERR0("ei_epmd_r4_port","<- CLOSE");
-    erl_errno = (res == -2) ? ETIMEDOUT : EIO;
-    closesocket(fd);
+    ei_close__(fd);
+    EI_CONN_SAVE_ERRNO__(err);
     return -1;
   }
   
-  closesocket(fd);
+  ei_close__(fd);
   s = buf;
 
   port = get16be(s);
diff --git a/lib/erl_interface/src/epmd/epmd_publish.c b/lib/erl_interface/src/epmd/epmd_publish.c
index 47d68a6db0..20b8e867e8 100644
--- a/lib/erl_interface/src/epmd/epmd_publish.c
+++ b/lib/erl_interface/src/epmd/epmd_publish.c
@@ -68,8 +68,10 @@ static int ei_epmd_r4_publish (int port, const char *alive, unsigned ms)
   int nlen = strlen(alive);
   int len = elen + nlen + 13; /* hard coded: be careful! */
   int n;
-  int res, creation;
-  
+  int err, res, creation;
+  ssize_t dlen;
+  unsigned tmo = ms == 0 ? EI_SCLBK_INF_TMO : ms;
+
   if (len > sizeof(buf)-2)
   {
     erl_errno = ERANGE;
@@ -93,29 +95,39 @@ static int ei_epmd_r4_publish (int port, const char *alive, unsigned ms)
 
   if ((fd = ei_epmd_connect_tmo(NULL,ms)) < 0) return fd;
 
-  if ((res = ei_write_fill_t(fd, buf, len+2, ms)) != len+2) {
-    closesocket(fd);
-    erl_errno = (res == -2) ? ETIMEDOUT : EIO;
-    return -1;
+  dlen = (ssize_t) len+2;
+  err = ei_write_fill_t__(fd, buf, &dlen, tmo);
+  if (!err && dlen != (ssize_t) len + 2)
+      erl_errno = EIO;
+  if (err) {
+      ei_close__(fd);
+      EI_CONN_SAVE_ERRNO__(err);
+      return -1;
   }
 
   EI_TRACE_CONN6("ei_epmd_r4_publish",
 		 "-> ALIVE2_REQ alive=%s port=%d ntype=%d "
 		 "proto=%d dist-high=%d dist-low=%d",
 		 alive,port,'H',EI_MYPROTO,EI_DIST_HIGH,EI_DIST_LOW);
-  
-  if ((n = ei_read_fill_t(fd, buf, 4, ms)) != 4) {
+
+  dlen = (ssize_t) 4;
+  err = ei_read_fill_t__(fd, buf, &dlen, tmo);
+  n = (int) dlen;
+  if (!err && n != 4)
+      err = EIO;
+  if (err) {
     EI_TRACE_ERR0("ei_epmd_r4_publish","<- CLOSE");
-    closesocket(fd);
-    erl_errno = (n == -2) ? ETIMEDOUT : EIO;
+    ei_close__(fd);
+    EI_CONN_SAVE_ERRNO__(err);
     return -2;			/* version mismatch */
   }
+
   /* Don't close fd here! It keeps us registered with epmd */
   s = buf;
   if (((res=get8(s)) != EI_EPMD_ALIVE2_RESP)) {  /* response */
     EI_TRACE_ERR1("ei_epmd_r4_publish","<- unknown (%d)",res);
     EI_TRACE_ERR0("ei_epmd_r4_publish","-> CLOSE");
-    closesocket(fd);
+    ei_close__(fd);
     erl_errno = EIO;
     return -1;
   }
@@ -124,7 +136,7 @@ static int ei_epmd_r4_publish (int port, const char *alive, unsigned ms)
 
   if (((res=get8(s)) != 0)) {           /* 0 == success */
       EI_TRACE_ERR1("ei_epmd_r4_publish"," result=%d (fail)",res);
-    closesocket(fd);
+    ei_close__(fd);
     erl_errno = EIO;
     return -1;
   }
diff --git a/lib/erl_interface/src/epmd/epmd_unpublish.c b/lib/erl_interface/src/epmd/epmd_unpublish.c
index 255d0ffb59..c112f74147 100644
--- a/lib/erl_interface/src/epmd/epmd_unpublish.c
+++ b/lib/erl_interface/src/epmd/epmd_unpublish.c
@@ -58,7 +58,9 @@ int ei_unpublish_tmo(const char *alive, unsigned ms)
     char buf[EPMDBUF];
     char *s = (char*)buf;
     int len = 1 + strlen(alive);
-    int fd, res;
+    int fd, err;
+    ssize_t dlen;
+    unsigned tmo = ms == 0 ? EI_SCLBK_INF_TMO : ms;
 
     if (len > sizeof(buf)-3) {
 	erl_errno = ERANGE;
@@ -72,20 +74,29 @@ int ei_unpublish_tmo(const char *alive, unsigned ms)
     /* FIXME can't connect, return success?! At least commen whats up */
     if ((fd = ei_epmd_connect_tmo(NULL,ms)) < 0) return fd;
 
-    if ((res = ei_write_fill_t(fd, buf, len+2,ms)) != len+2) {
-	closesocket(fd);
-	erl_errno = (res == -2) ? ETIMEDOUT : EIO;
-	return -1;
+    dlen = (ssize_t) len+2;
+    err = ei_write_fill_t__(fd, buf, &dlen, tmo);
+    if (!err && dlen != (ssize_t) len + 2)
+        erl_errno = EIO;
+    if (err) {
+        ei_close__(fd);
+        EI_CONN_SAVE_ERRNO__(err);
+        return -1;
     }
 
     EI_TRACE_CONN1("ei_unpublish_tmo","-> STOP %s",alive);
-  
-    if ((res = ei_read_fill_t(fd, buf, 7, ms)) != 7) {
-	closesocket(fd);
-	erl_errno = (res == -2) ? ETIMEDOUT : EIO;
-	return -1; 
+
+    dlen = (ssize_t) 7;
+    err = ei_read_fill_t__(fd, buf, &dlen, tmo);
+    if (!err && dlen != (ssize_t) 7)
+        erl_errno = EIO;
+    if (err) {
+        ei_close__(fd);
+        EI_CONN_SAVE_ERRNO__(err);
+        return -1;
     }
-    closesocket(fd);
+    
+    ei_close__(fd);
     buf[7]=(char)0;		/* terminate the string */
   
     if (!strcmp("STOPPED",(char *)buf)) {
diff --git a/lib/erl_interface/src/legacy/erl_connect.c b/lib/erl_interface/src/legacy/erl_connect.c
index 7ffd545d3e..e2fd4611c0 100644
--- a/lib/erl_interface/src/legacy/erl_connect.c
+++ b/lib/erl_interface/src/legacy/erl_connect.c
@@ -179,15 +179,13 @@ int erl_xconnect(Erl_IpAddr addr, char *alivename)
  *
  *  API: erl_close_connection()
  *
- *  Close a connection. FIXME call ei_close_connection() later. 
- *
  *  Returns 0 on success and -1 on failure.
  *
  ***************************************************************************/
 
 int erl_close_connection(int fd)
 {
-    return closesocket(fd);
+    return ei_close_connection(fd);
 }
 
 /*
@@ -220,7 +218,10 @@ int erl_reg_send(int fd, char *server_name, ETERM *msg)
     ei_x_buff x;
     int r;
 
-    ei_x_new_with_version(&x);
+    if (ei_x_new_with_version(&x) < 0) {
+        erl_errno = ENOMEM;
+        return 0;
+    }
     if (ei_x_encode_term(&x, msg) < 0) {
 	erl_errno = EINVAL;
 	r = 0;
diff --git a/lib/erl_interface/src/misc/ei_internal.h b/lib/erl_interface/src/misc/ei_internal.h
index aa6aacd703..0c58245c0a 100644
--- a/lib/erl_interface/src/misc/ei_internal.h
+++ b/lib/erl_interface/src/misc/ei_internal.h
@@ -22,19 +22,20 @@
 #ifndef _EI_INTERNAL_H
 #define _EI_INTERNAL_H
 
+#ifdef EI_HIDE_REAL_ERRNO
+#  define EI_CONN_SAVE_ERRNO__(E) \
+    ((E) == ETIMEDOUT ? (erl_errno = ETIMEDOUT) : (erl_errno = EIO))
+#else
+#  define EI_CONN_SAVE_ERRNO__(E) \
+    (erl_errno = (E))
+#endif
+
 /* 
  * Some useful stuff not to be exported to users.
  */
 
 #ifdef __WIN32__
 #define MAXPATHLEN 256
-#define writesocket(sock,buf,nbyte) send(sock,buf,nbyte,0)
-#define  readsocket(sock,buf,nbyte) recv(sock,buf,nbyte,0)
-#else /* not __WIN32__ */
-#define writesocket write
-#define readsocket  read
-#define closesocket close
-#define ioctlsocket ioctl
 #endif
 
 /* 
@@ -155,4 +156,7 @@ extern int ei_tracelevel;
 void ei_trace_printf(const char *name, int level, const char *format, ...);
 
 int ei_internal_use_r9_pids_ports(void);
+
+int ei_get_cbs_ctx__(ei_socket_callbacks **cbs, void **ctx, int fd);
+
 #endif /* _EI_INTERNAL_H */
diff --git a/lib/erl_interface/src/misc/ei_portio.c b/lib/erl_interface/src/misc/ei_portio.c
index 8cd35bf2e5..726b1af82d 100644
--- a/lib/erl_interface/src/misc/ei_portio.c
+++ b/lib/erl_interface/src/misc/ei_portio.c
@@ -22,6 +22,7 @@
 #ifdef __WIN32__
 #include <winsock2.h>
 #include <windows.h>
+#include <winbase.h>
 #include <process.h>
 #include <stdio.h>
 #include <stdlib.h>
@@ -35,10 +36,6 @@ static unsigned long param_one = 1;
 #define SET_BLOCKING(Sock) ioctlsocket((Sock),FIONBIO,&param_zero)
 #define SET_NONBLOCKING(Sock) ioctlsocket((Sock),FIONBIO,&param_one)
 
-#define ERROR_WOULDBLOCK WSAEWOULDBLOCK
-#define ERROR_TIMEDOUT WSAETIMEDOUT 
-#define ERROR_INPROGRESS WSAEINPROGRESS
-#define GET_SOCKET_ERROR() WSAGetLastError()
 #define MEANS_SOCKET_ERROR(Ret) ((Ret == SOCKET_ERROR))
 #define IS_INVALID_SOCKET(Sock) ((Sock) == INVALID_SOCKET)
 
@@ -53,15 +50,16 @@ static unsigned long param_one = 1;
 #include <sys/types.h>
 #include <ioLib.h>
 #include <unistd.h>
+#include <sys/types.h>
+#include <sys/socket.h>
+#include <netinet/in.h>
+#include <netinet/tcp.h> 
+#include <timers.h>
 
 static unsigned long param_zero = 0;
 static unsigned long param_one = 1;
 #define SET_BLOCKING(Sock) ioctl((Sock),FIONBIO,(int)&param_zero)
 #define SET_NONBLOCKING(Sock) ioctl((Sock),FIONBIO,(int)&param_one)
-#define ERROR_WOULDBLOCK EWOULDBLOCK
-#define ERROR_TIMEDOUT ETIMEDOUT 
-#define ERROR_INPROGRESS EINPROGRESS
-#define GET_SOCKET_ERROR() (errno)
 #define MEANS_SOCKET_ERROR(Ret) ((Ret) == ERROR)
 #define IS_INVALID_SOCKET(Sock) ((Sock) < 0)
 
@@ -69,106 +67,394 @@ static unsigned long param_one = 1;
 #include <stdlib.h>
 #include <sys/types.h>
 #include <sys/socket.h>
-#include <sys/uio.h>
 #include <unistd.h>
 #include <fcntl.h>
 #include <errno.h>
+#include <netinet/in.h>
+#include <netinet/tcp.h> 
+#include <arpa/inet.h>
+#include <netdb.h>
 
-#ifndef EWOULDBLOCK
-#define ERROR_WOULDBLOCK EAGAIN
-#else
-#define ERROR_WOULDBLOCK EWOULDBLOCK
-#endif
 #define SET_BLOCKING(fd)  fcntl((fd), F_SETFL, \
 				fcntl((fd), F_GETFL, 0) & ~O_NONBLOCK)
 #define SET_NONBLOCKING(fd) fcntl((fd), F_SETFL, \
 				  fcntl((fd), F_GETFL, 0) | O_NONBLOCK)
-#define ERROR_TIMEDOUT ETIMEDOUT 
-#define ERROR_INPROGRESS EINPROGRESS
-#define GET_SOCKET_ERROR() (errno)
 #define MEANS_SOCKET_ERROR(Ret) ((Ret) < 0)
 #define IS_INVALID_SOCKET(Sock) ((Sock) < 0)
 
 #endif
 
 /* common includes */
-#include "eidef.h"
 
 #include <stdio.h> 
 #include <stdlib.h>
 #include <string.h>
-#include "ei_portio.h"
-#include "ei_internal.h"
-
 #ifdef HAVE_SYS_TIME_H
 #include <sys/time.h>
 #else
 #include <time.h>
 #endif
+#include "eidef.h"
+#include "ei_portio.h"
+#include "ei_internal.h"
+
+#ifdef __WIN32__
+
+#define writesocket(sock,buf,nbyte) send(sock,buf,nbyte,0)
+#define readsocket(sock,buf,nbyte) recv(sock,buf,nbyte,0)
 
-#ifdef HAVE_WRITEV
-static int ei_writev_t(int fd,  struct  iovec  *iov,  int iovcnt, unsigned ms)
+static int get_error(void)
 {
-    int res;
-    if (ms != 0) {
-	fd_set writemask;
-	struct timeval tv;
-	tv.tv_sec = (time_t) (ms / 1000U);
-	ms %= 1000U;
-	tv.tv_usec = (time_t) (ms * 1000U);
-	FD_ZERO(&writemask);
-	FD_SET(fd,&writemask);
-	switch (select(fd+1, NULL, &writemask, NULL, &tv)) {
-	case -1 : 
-	    return -1; /* i/o error */
-	case 0:
-	    return -2; /* timeout */
-	default:
-	    if (!FD_ISSET(fd, &writemask)) {
-		return -1; /* Other error */
-	    }
-	}
+    switch (WSAGetLastError()) {
+    case WSAEWOULDBLOCK: return EWOULDBLOCK;
+    case WSAETIMEDOUT: return ETIMEDOUT;
+    case WSAEINPROGRESS: return EINPROGRESS;
+    case WSA_NOT_ENOUGH_MEMORY: return ENOMEM;
+    case WSA_INVALID_PARAMETER: return EINVAL;
+    case WSAEBADF: return EBADF;
+    case WSAEINVAL: return EINVAL;
+    case WSAEADDRINUSE: return EADDRINUSE;
+    case WSAENETUNREACH: return ENETUNREACH;
+    case WSAECONNABORTED: return ECONNABORTED;
+    case WSAECONNRESET: return ECONNRESET;
+    case WSAECONNREFUSED: return ECONNREFUSED;
+    case WSAEHOSTUNREACH: return EHOSTUNREACH;
+    case WSAEMFILE: return EMFILE;
+    case WSAEALREADY: return EALREADY;
+    default: return EIO;
     }
+}
+
+#else /* not __WIN32__ */
+
+#define writesocket write
+#define readsocket  read
+#define closesocket close
+#define ioctlsocket ioctl
+
+static int get_error(void)
+{
+    int err = errno;
+    if (err == 0)
+        return EIO; /* Make sure never to return 0 as error code... */
+    return err;
+}
+
+#endif
+
+int ei_plugin_socket_impl__ = 0;
+
+/*
+ * Callbacks for communication over TCP/IPv4
+ */
+
+static int tcp_get_fd(void *ctx, int *fd)
+{
+    return EI_DFLT_CTX_TO_FD__(ctx, fd);
+}
+
+static int tcp_hs_packet_header_size(void *ctx, int *sz)
+{
+    int fd;
+    *sz = 2;
+    return EI_DFLT_CTX_TO_FD__(ctx, &fd);
+}
+
+static int tcp_handshake_complete(void *ctx)
+{
+    int res, fd, one = 1;
+
+    res = EI_DFLT_CTX_TO_FD__(ctx, &fd);
+    if (res)
+        return res;
+
+    res = setsockopt(fd, IPPROTO_TCP, TCP_NODELAY, (char *)&one, sizeof(one));
+    if (MEANS_SOCKET_ERROR(res))
+        return get_error();
+    
+    res = setsockopt(fd, SOL_SOCKET, SO_KEEPALIVE, (char *)&one, sizeof(one));
+    if (MEANS_SOCKET_ERROR(res))
+        return get_error();
+
+    return 0;
+}
+
+static int tcp_socket(void **ctx, void *setup_ctx)
+{
+    int fd = socket(AF_INET, SOCK_STREAM, 0);
+    if (MEANS_SOCKET_ERROR(fd))
+        return get_error();
+
+    *ctx = EI_FD_AS_CTX__(fd);
+    return 0;
+}
+
+static int tcp_close(void *ctx)
+{
+    int fd, res;
+
+    res = EI_DFLT_CTX_TO_FD__(ctx, &fd);
+    if (res)
+        return res;
+
+    res = closesocket(fd);
+    if (MEANS_SOCKET_ERROR(res))
+        return get_error();
+
+    return 0;
+}
+
+static int tcp_listen(void *ctx, void *addr, int *len, int backlog)
+{
+    int res, fd;
+    socklen_t sz = (socklen_t) *len;
+    int on = 1;
+
+    res = EI_DFLT_CTX_TO_FD__(ctx, &fd);
+    if (res)
+        return res;
+
+    res = setsockopt(fd, SOL_SOCKET, SO_REUSEADDR, (char *) &on, sizeof(on));
+    if (MEANS_SOCKET_ERROR(res))
+        return get_error();
+
+    res = bind(fd, (struct sockaddr *) addr, sz);
+    if (MEANS_SOCKET_ERROR(res))
+        return get_error();
+
+    res = getsockname(fd, (struct sockaddr *) addr, (socklen_t *) &sz);
+    if (MEANS_SOCKET_ERROR(res))
+        return get_error();
+    *len = (int) sz;
+    
+    res = listen(fd, backlog);
+    if (MEANS_SOCKET_ERROR(res))
+        return get_error();
+
+    return 0;
+}
+
+static int tcp_accept(void **ctx, void *addr, int *len, unsigned unused)
+{
+    int fd, res;
+    socklen_t addr_len = (socklen_t) *len;
+
+    if (!ctx)
+        return EINVAL;
+
+    res = EI_DFLT_CTX_TO_FD__(*ctx, &fd);
+    if (res)
+        return res;
+    
+    res = accept(fd, (struct sockaddr*) &addr, &addr_len);
+    if (MEANS_SOCKET_ERROR(res))
+        return get_error();
+
+    *len = (int) addr_len;
+
+    *ctx = EI_FD_AS_CTX__(res);
+    return 0;
+}
+
+static int tcp_connect(void *ctx, void *addr, int len, unsigned unused)
+{
+    int res, fd;
+
+    res = EI_DFLT_CTX_TO_FD__(ctx, &fd);
+    if (res)
+        return res;
+
+    res = connect(fd, (struct sockaddr *) addr, len);
+    if (MEANS_SOCKET_ERROR(res))
+        return get_error();
+    
+    return 0;
+}
+
+#if defined(EI_HAVE_STRUCT_IOVEC__) && defined(HAVE_WRITEV)
+
+static int tcp_writev(void *ctx, const void *viov, int iovcnt, ssize_t *len, unsigned unused)
+{
+    const struct iovec *iov = (const struct iovec *) viov;
+    int fd, error;
+    ssize_t res;
+
+    error = EI_DFLT_CTX_TO_FD__(ctx, &fd);
+    if (error)
+        return error;
+
     res = writev(fd, iov, iovcnt);
-    return (res < 0) ? -1 : res;
+    if (MEANS_SOCKET_ERROR(res))
+        return get_error();
+    *len = res;
+    return 0;
+}
+
+#endif
+
+static int tcp_write(void *ctx, const char* buf, ssize_t *len, unsigned unused)
+{
+    int error, fd;
+    ssize_t res;
+
+    error = EI_DFLT_CTX_TO_FD__(ctx, &fd);
+    if (error)
+        return error;
+
+    res = writesocket(fd, buf, *len);
+    if (MEANS_SOCKET_ERROR(res))
+        return get_error();
+    *len = res;
+    return 0;
 }
 
-int ei_writev_fill_t(int fd,  const  struct  iovec  *iov,  int iovcnt, unsigned ms)
+static int tcp_read(void *ctx, char* buf, ssize_t *len, unsigned unused)
 {
-    int i;
-    int done;
+    int error, fd;
+    ssize_t res;
+
+    error = EI_DFLT_CTX_TO_FD__(ctx, &fd);
+    if (error)
+        return error;
+
+    res = readsocket(fd, buf, *len);
+    if (MEANS_SOCKET_ERROR(res))
+        return get_error();
+    *len = res;
+    return 0;
+}
+
+ei_socket_callbacks ei_default_socket_callbacks = {
+    0, /* flags */
+    tcp_socket,
+    tcp_close,
+    tcp_listen,
+    tcp_accept,
+    tcp_connect,
+#if defined(EI_HAVE_STRUCT_IOVEC__) && defined(HAVE_WRITEV)
+    tcp_writev,
+#else
+    NULL,
+#endif
+    tcp_write,
+    tcp_read,
+
+    tcp_hs_packet_header_size,
+    tcp_handshake_complete,
+    tcp_handshake_complete,
+    tcp_get_fd
+
+};
+
+
+/*
+ *
+ */
+
+#if defined(EI_HAVE_STRUCT_IOVEC__)
+
+int ei_socket_callbacks_have_writev__(ei_socket_callbacks *cbs)
+{
+    return !!cbs->writev;
+}
+
+static int writev_ctx_t__(ei_socket_callbacks *cbs, void *ctx,
+                          const struct iovec *iov, int iovcnt,
+                          ssize_t *len,
+                          unsigned ms)
+{
+    int error;
+
+    if (!(cbs->flags & EI_SCLBK_FLG_FULL_IMPL) && ms != EI_SCLBK_INF_TMO) {
+        int fd;
+
+        error = EI_GET_FD__(cbs, ctx, &fd);
+        if (error)
+            return error;
+
+        do {
+            fd_set writemask;
+            struct timeval tv;
+            
+            tv.tv_sec = (time_t) (ms / 1000U);
+            ms %= 1000U;
+            tv.tv_usec = (time_t) (ms * 1000U);
+            FD_ZERO(&writemask);
+            FD_SET(fd,&writemask);
+            switch (select(fd+1, NULL, &writemask, NULL, &tv)) {
+            case -1 : 
+                error = get_error();
+                if (error != EINTR)
+                    return error;
+                break;
+            case 0:
+                return ETIMEDOUT; /* timeout */
+            default:
+                if (!FD_ISSET(fd, &writemask)) {
+                    return EIO; /* Other error */
+                }
+                error = 0;
+                break;
+            }
+        } while (error == EINTR);
+    }
+    do {
+        error = cbs->writev(ctx, (const void *) iov, iovcnt, len, ms);
+    } while (error == EINTR);
+    return error;
+}
+
+int ei_writev_fill_ctx_t__(ei_socket_callbacks *cbs, void *ctx,
+                           const struct iovec *iov, int iovcnt,
+                           ssize_t *len,
+                           unsigned ms)
+{
+    ssize_t i, done, sum;
     struct iovec *iov_base = NULL;
     struct iovec *current_iov;
     int current_iovcnt;
-    int sum;
+    int fd, error;
+    int basic;
+
+    if (!cbs->writev)
+        return ENOTSUP;
+    
+    error = EI_GET_FD__(cbs, ctx, &fd);
+    if (error)
+        return error;
 
+    basic = !(cbs->flags & EI_SCLBK_FLG_FULL_IMPL);
+    
     for (sum = 0, i = 0; i < iovcnt; ++i) {
 	sum += iov[i].iov_len;
     }
-    if (ms != 0U) {
+    if (basic && ms != 0U) {
 	SET_NONBLOCKING(fd);
     } 
     current_iovcnt = iovcnt;
     current_iov = (struct iovec *) iov;
     done = 0;
     for (;;) {
-	i = ei_writev_t(fd, current_iov, current_iovcnt, ms);
-	if (i <= 0) { /* ei_writev_t should always return at least 1 */ 
+        
+	error = writev_ctx_t__(cbs, ctx, current_iov, current_iovcnt, &i, ms);
+        if (error) {
+            *len = done;
 	    if (ms != 0U) {
 		SET_BLOCKING(fd);
 	    }    
 	    if (iov_base != NULL) {
 		free(iov_base);
 	    }
-	    return (i);
-	}
+	    return error;
+        }
 	done += i;
 
 	if (done < sum) {
 	    if (iov_base == NULL) {
 		iov_base = malloc(sizeof(struct iovec) * iovcnt);
 		if (iov_base == NULL) {
-		return -1;
+                    *len = done;
+                    return ENOMEM;
 		}
 		memcpy(iov_base, iov, sizeof(struct iovec) * iovcnt);
 		current_iov = iov_base;
@@ -189,195 +475,383 @@ int ei_writev_fill_t(int fd,  const  struct  iovec  *iov,  int iovcnt, unsigned
 	    break;
 	}
     } 
-    if (ms != 0U) {
+    if (basic && ms != 0U) {
 	SET_BLOCKING(fd);
     }
     if (iov_base != NULL) {
 	free(iov_base);
     }
-    return (sum);
+    *len = done;
+    return 0;
 }
 
+#endif /* defined(EI_HAVE_STRUCT_IOVEC__) */
 
-#endif
-
-int ei_connect_t(int fd, void *sinp, int sin_siz, unsigned ms)
+int ei_socket_ctx__(ei_socket_callbacks *cbs, void **ctx, void *setup_ctx)
 {
     int res;
-    int error;
-    int s_res;
-    struct timeval tv;
-    fd_set writefds;
-    fd_set exceptfds;
-
-    if (ms == 0) {
-	res = connect(fd, sinp, sin_siz);
-	return (res < 0) ? -1 : res;
-    } else {
-	SET_NONBLOCKING(fd);
-	res = connect(fd, sinp, sin_siz);
-	error = GET_SOCKET_ERROR();
-	SET_BLOCKING(fd);
-	if (!MEANS_SOCKET_ERROR(res)) {
-	    return (res < 0) ? -1 : res;
-	} else {
-	    if (error != ERROR_WOULDBLOCK && 
-		error != ERROR_INPROGRESS) {
-		return -1;
-	    } else {
-		tv.tv_sec = (long) (ms/1000U);
-		ms %= 1000U;
-		tv.tv_usec = (long) (ms * 1000U);
-		FD_ZERO(&writefds);
-		FD_SET(fd,&writefds);
-		FD_ZERO(&exceptfds);
-		FD_SET(fd,&exceptfds);
-		s_res = select(fd + 1, NULL, &writefds, &exceptfds, &tv);
-		switch (s_res) {
-		case 0:
-		    return -2;
-		case 1:
-		    if (FD_ISSET(fd, &exceptfds)) {
-			return  -1;
-		    } else {
-			return 0; /* Connect completed */
-		    }
-		default:
-		    return -1;
-		}
-	    }
-	} 
-    }
+
+    do {
+        res = cbs->socket(ctx, setup_ctx);
+    } while (res == EINTR);
+
+    return res;
 }
 
-int ei_accept_t(int fd, void  *addr,   void  *addrlen, unsigned ms)
+int ei_close_ctx__(ei_socket_callbacks *cbs, void *ctx)
 {
-    int res;
-    if (ms != 0) {
-	fd_set readmask;
-	struct timeval tv;
-	tv.tv_sec = (time_t) (ms / 1000U);
-	ms %= 1000U;
-	tv.tv_usec = (time_t) (ms * 1000U);
-	FD_ZERO(&readmask);
-	FD_SET(fd,&readmask);
-	switch (select(fd+1, &readmask, NULL, NULL, &tv)) {
-	case -1 : 
-	    return -1; /* i/o error */
-	case 0:
-	    return -2; /* timeout */
-	default:
-	    if (!FD_ISSET(fd, &readmask)) {
-		return -1; /* Other error */
-	    }
-	}
-    }
-    res = (int) accept(fd,addr,addrlen);
-    return (res < 0) ? -1 : res;
+    return cbs->close(ctx);
 }
+
+int ei_connect_ctx_t__(ei_socket_callbacks *cbs, void *ctx,
+                       void *addr, int len, unsigned ms)
+{
+    int res, fd;
+
+    if ((cbs->flags & EI_SCLBK_FLG_FULL_IMPL) || ms == EI_SCLBK_INF_TMO) {
+        do {
+            res = cbs->connect(ctx, addr, len, ms);
+        } while (res == EINTR);
+        return res;
+    }
+
+    res = EI_GET_FD__(cbs, ctx, &fd);
+    if (res)
+        return res;
     
+    SET_NONBLOCKING(fd);
+    do {
+        res = cbs->connect(ctx, addr, len, 0);
+    } while (res == EINTR);
+    SET_BLOCKING(fd);
+
+    switch (res) {
+    case EINPROGRESS:
+    case EAGAIN:
+#ifdef EWOULDBLOCK
+#if EWOULDBLOCK != EAGAIN
+    case EWOULDBLOCK:
+#endif
+#endif
+        break;
+    default:
+        return res;
+    }
 
+    while (1) {
+        struct timeval tv;
+        fd_set writefds;
+        fd_set exceptfds;
+        
+        tv.tv_sec = (long) (ms/1000U);
+        ms %= 1000U;
+        tv.tv_usec = (long) (ms * 1000U);
+        FD_ZERO(&writefds);
+        FD_SET(fd,&writefds);
+        FD_ZERO(&exceptfds);
+        FD_SET(fd,&exceptfds);
+        res = select(fd + 1, NULL, &writefds, &exceptfds, &tv);
+        switch (res) {
+        case -1:
+            res = get_error();
+            if (res != EINTR)
+                return res;
+            break;
+        case 0:
+            return ETIMEDOUT;
+        case 1:
+            if (!FD_ISSET(fd, &exceptfds))
+                return 0; /* Connect completed */
+            /* fall through... */
+        default:
+            return EIO;
+        }
+    }
+}
 
-static int ei_read_t(int fd, char* buf, int len, unsigned  ms)
+int ei_listen_ctx__(ei_socket_callbacks *cbs, void *ctx,
+                    void *adr, int *len, int backlog)
 {
     int res;
-    if (ms != 0) {
-	fd_set readmask;
-	struct timeval tv;
-	tv.tv_sec = (time_t) (ms / 1000U);
-	ms %= 1000U;
-	tv.tv_usec = (time_t) (ms * 1000U);
-	FD_ZERO(&readmask);
-	FD_SET(fd,&readmask);
-	switch (select(fd+1, &readmask, NULL, NULL, &tv)) {
-	case -1 : 
-	    return -1; /* i/o error */
-	case 0:
-	    return -2; /* timeout */
-	default:
-	    if (!FD_ISSET(fd, &readmask)) {
-		return -1; /* Other error */
-	    }
-	}
+
+    do {
+        res = cbs->listen(ctx, adr, len, backlog);
+    } while (res == EINTR);
+    return res;
+}
+
+int ei_accept_ctx_t__(ei_socket_callbacks *cbs, void **ctx,
+                      void *addr, int *len, unsigned ms)
+{
+    int error;
+
+    if (!(cbs->flags & EI_SCLBK_FLG_FULL_IMPL) && ms != EI_SCLBK_INF_TMO) {
+        int fd;
+
+        error = EI_GET_FD__(cbs, *ctx, &fd);
+        if (error)
+            return error;
+
+        do {
+            fd_set readmask;
+            struct timeval tv;
+            
+            tv.tv_sec = (time_t) (ms / 1000U);
+            ms %= 1000U;
+            tv.tv_usec = (time_t) (ms * 1000U);
+            FD_ZERO(&readmask);
+            FD_SET(fd,&readmask);
+            switch (select(fd+1, &readmask, NULL, NULL, &tv)) {
+            case -1 : 
+                error = get_error();
+                if (error != EINTR)
+                    return error;
+                break;
+            case 0:
+                return ETIMEDOUT; /* timeout */
+            default:
+                if (!FD_ISSET(fd, &readmask)) {
+                    return EIO; /* Other error */
+                }
+                error = 0;
+                break;
+            }
+        } while (error == EINTR);
     }
-    res = readsocket(fd, buf, len);
-    return (res < 0) ? -1 : res;
+    do {
+        error = cbs->accept(ctx, addr, len, ms);
+    } while (error == EINTR);
+    return error;
 }
 
-static int ei_write_t(int fd, const char* buf, int len, unsigned  ms)
+static int read_ctx_t__(ei_socket_callbacks *cbs, void *ctx,
+                        char* buf, ssize_t *len, unsigned  ms)
 {
-    int res;
-    if (ms != 0) {
-	fd_set writemask;
-	struct timeval tv;
-	tv.tv_sec = (time_t) (ms / 1000U);
-	ms %= 1000U;
-	tv.tv_usec = (time_t) (ms * 1000U);
-	FD_ZERO(&writemask);
-	FD_SET(fd,&writemask);
-	switch (select(fd+1, NULL, &writemask, NULL, &tv)) {
-	case -1 : 
-	    return -1; /* i/o error */
-	case 0:
-	    return -2; /* timeout */
-	default:
-	    if (!FD_ISSET(fd, &writemask)) {
-		return -1; /* Other error */
-	    }
-	}
+    int error;
+
+    if (!(cbs->flags & EI_SCLBK_FLG_FULL_IMPL) && ms != EI_SCLBK_INF_TMO) {
+        int fd;
+
+        error = EI_GET_FD__(cbs, ctx, &fd);
+        if (error)
+            return error;
+        
+        do {
+            fd_set readmask;
+            struct timeval tv;
+            
+            tv.tv_sec = (time_t) (ms / 1000U);
+            ms %= 1000U;
+            tv.tv_usec = (time_t) (ms * 1000U);
+            FD_ZERO(&readmask);
+            FD_SET(fd,&readmask);
+            switch (select(fd+1, &readmask, NULL, NULL, &tv)) {
+            case -1 :
+                error = get_error();
+                if (error != EINTR)
+                    return error;
+                break;
+            case 0:
+                return ETIMEDOUT; /* timeout */
+            default:
+                if (!FD_ISSET(fd, &readmask)) {
+                    return EIO; /* Other error */
+                }
+                error = 0;
+                break;
+            }
+        } while (error == EINTR);
+    }
+    do {
+        error = cbs->read(ctx, buf, len, ms);
+    } while (error == EINTR);
+    return error;
+}
+
+static int write_ctx_t__(ei_socket_callbacks *cbs, void *ctx, const char* buf, ssize_t *len, unsigned  ms)
+{
+    int error;
+    
+    if (!(cbs->flags & EI_SCLBK_FLG_FULL_IMPL) && ms != EI_SCLBK_INF_TMO) {
+        int fd;
+
+        error = EI_GET_FD__(cbs, ctx, &fd);
+        if (error)
+            return error;
+
+        do {
+            fd_set writemask;
+            struct timeval tv;
+            
+            tv.tv_sec = (time_t) (ms / 1000U);
+            ms %= 1000U;
+            tv.tv_usec = (time_t) (ms * 1000U);
+            FD_ZERO(&writemask);
+            FD_SET(fd,&writemask);
+            switch (select(fd+1, NULL, &writemask, NULL, &tv)) {
+            case -1 : 
+                error = get_error();
+                if (error != EINTR)
+                    return error;
+                break;
+            case 0:
+                return ETIMEDOUT; /* timeout */
+            default:
+                if (!FD_ISSET(fd, &writemask)) {
+                    return EIO; /* Other error */
+                }
+                error = 0;
+                break;
+            }
+        } while (error == EINTR);
     }
-    res =  writesocket(fd, buf, len);
-    return (res < 0) ? -1 : res;
+    do {
+        error = cbs->write(ctx, buf, len, ms);
+    } while (error == EINTR);
+    return error;
 }
 	
 /* 
  * Fill buffer, return buffer length, 0 for EOF, < 0 (and sets errno)
  * for error.  */
-int ei_read_fill_t(int fd, char* buf, int len, unsigned  ms)
+int ei_read_fill_ctx_t__(ei_socket_callbacks *cbs, void *ctx, char* buf, ssize_t *len, unsigned  ms)
 {
-    int i,got=0;
+    ssize_t got = 0;
+    ssize_t want = *len;
 
     do {
-	i = ei_read_t(fd, buf+got, len-got, ms);
-	if (i <= 0)
-	    return (i);
-	got += i;
-    } while (got < len);
-    return (len);
-    
+        ssize_t read_len = want-got;
+        int error;
+
+        do {
+            error = read_ctx_t__(cbs, ctx, buf+got, &read_len, ms);
+        } while (error == EINTR);
+        if (error)
+            return error;
+        if (read_len == 0) {
+            *len = got;
+            return 0;
+        }
+	got += read_len;
+    } while (got < want);
+
+    *len = got;
+    return 0;
 } /* read_fill */
 
-int ei_read_fill(int fd, char* buf, int len)
+int ei_read_fill_ctx__(ei_socket_callbacks *cbs, void *ctx, char* buf, ssize_t *len)
 {
-    return ei_read_fill_t(fd, buf, len, 0);
+    return ei_read_fill_ctx_t__(cbs, ctx, buf, len, 0);
 }
 
 /* write entire buffer on fd  or fail (setting errno)
  */
-int ei_write_fill_t(int fd, const char *buf, int len, unsigned ms)
+int ei_write_fill_ctx_t__(ei_socket_callbacks *cbs, void *ctx, const char *buf, ssize_t *len, unsigned ms)
 {
-    int i,done=0;
-    if (ms != 0U) {
+    ssize_t tot = *len, done = 0;
+    int error, fd = -1, basic = !(cbs->flags & EI_SCLBK_FLG_FULL_IMPL);
+    
+    if (basic && ms != 0U) {
+        error = EI_GET_FD__(cbs, ctx, &fd);
+        if (error)
+            return error;
 	SET_NONBLOCKING(fd);
     }    
     do {
-	i = ei_write_t(fd, buf+done, len-done, ms);
-	if (i <= 0) {
-	    if (ms != 0U) {
+        ssize_t write_len = tot-done;
+	error = write_ctx_t__(cbs, ctx, buf+done, &write_len, ms);
+        if (error) {
+            *len = done;
+	    if (basic && ms != 0U) {
 		SET_BLOCKING(fd);
 	    }    
-	    return (i);
+	    return error;
 	}
-	done += i;
-    } while (done < len);
-    if (ms != 0U) {
+	done += write_len;
+    } while (done < tot);
+    if (basic && ms != 0U) {
 	SET_BLOCKING(fd);
     }
-    return (len);
+    *len = done;
+    return 0;
+}
+
+int ei_write_fill_ctx__(ei_socket_callbacks *cbs, void *ctx, const char *buf, ssize_t *len) 
+{
+    return ei_write_fill_ctx_t__(cbs, ctx, buf, len, 0);
+}
+
+/*
+ * Internal API for TCP/IPv4
+ */
+
+int ei_connect_t__(int fd, void *addr, int len, unsigned ms)
+{
+    return ei_connect_ctx_t__(&ei_default_socket_callbacks, EI_FD_AS_CTX__(fd),
+                              addr, len, ms);
 }
 
-int ei_write_fill(int fd, const char *buf, int len) 
+int ei_socket__(int *fd)
 {
-    return ei_write_fill_t(fd, buf, len, 0);
+    void *ctx;
+    int error = ei_socket_ctx__(&ei_default_socket_callbacks, &ctx, NULL);
+    if (error)
+        return error;
+    return EI_GET_FD__(&ei_default_socket_callbacks, ctx, fd);
 }
 
+int ei_close__(int fd)
+{
+    return ei_close_ctx__(&ei_default_socket_callbacks, EI_FD_AS_CTX__(fd));
+}
+
+int ei_listen__(int fd, void *adr, int *len, int backlog)
+{
+    return ei_listen_ctx__(&ei_default_socket_callbacks, EI_FD_AS_CTX__(fd),
+                           adr, len, backlog);
+}
+
+int ei_accept_t__(int *fd, void *addr, int *len, unsigned ms)
+{
+    void *ctx = EI_FD_AS_CTX__(*fd);
+    int error = ei_accept_ctx_t__(&ei_default_socket_callbacks, &ctx,
+                                  addr, len, ms);
+    if (error)
+        return error;
+    return EI_GET_FD__(&ei_default_socket_callbacks, ctx, fd);
+}
+
+int ei_read_fill_t__(int fd, char* buf, ssize_t *len, unsigned  ms)
+{
+    return ei_read_fill_ctx_t__(&ei_default_socket_callbacks, EI_FD_AS_CTX__(fd),
+                                buf, len, ms);
+}
+
+int ei_read_fill__(int fd, char* buf, ssize_t *len)
+{
+    return ei_read_fill_ctx_t__(&ei_default_socket_callbacks, EI_FD_AS_CTX__(fd),
+                                buf, len, 0);
+}
+
+int ei_write_fill_t__(int fd, const char *buf, ssize_t *len, unsigned ms)
+{
+    return ei_write_fill_ctx_t__(&ei_default_socket_callbacks, EI_FD_AS_CTX__(fd),
+                                 buf, len, ms);
+}
+
+int ei_write_fill__(int fd, const char *buf, ssize_t *len) 
+{
+    return ei_write_fill_ctx_t__(&ei_default_socket_callbacks, EI_FD_AS_CTX__(fd),
+                                 buf, len, 0);
+}
+
+#if defined(EI_HAVE_STRUCT_IOVEC__) && defined(HAVE_WRITEV)
+
+int ei_writev_fill_t__(int fd, const struct iovec  *iov,  int iovcnt, ssize_t *len, unsigned ms)
+{
+    return ei_writev_fill_ctx_t__(&ei_default_socket_callbacks, EI_FD_AS_CTX__(fd),
+                                  iov, iovcnt, len, ms);
+}
+
+#endif
+
diff --git a/lib/erl_interface/src/misc/ei_portio.h b/lib/erl_interface/src/misc/ei_portio.h
index bded811a35..a84b5ca09c 100644
--- a/lib/erl_interface/src/misc/ei_portio.h
+++ b/lib/erl_interface/src/misc/ei_portio.h
@@ -21,21 +21,94 @@
  */
 #ifndef _EI_PORTIO_H
 #define _EI_PORTIO_H
-#if !defined(__WIN32__) && !defined(VXWORKS)
-#ifdef HAVE_WRITEV
+
+#undef EI_HAVE_STRUCT_IOVEC__
+#if !defined(__WIN32__) && !defined(VXWORKS) && defined(HAVE_SYS_UIO_H)
 /* Declaration of struct iovec *iov should be visible in this scope. */
-#include <sys/uio.h>
+#  include <sys/uio.h>
+#  define EI_HAVE_STRUCT_IOVEC__
 #endif
+
+/*
+ * Internal API. Should not be used outside of the erl_interface application...
+ */
+
+int ei_socket_ctx__(ei_socket_callbacks *cbs, void **ctx, void *setup);
+int ei_close_ctx__(ei_socket_callbacks *cbs, void *ctx);
+int ei_listen_ctx__(ei_socket_callbacks *cbs, void *ctx, void *adr, int *len, int backlog);
+int ei_accept_ctx_t__(ei_socket_callbacks *cbs, void **ctx, void *addr, int *len, unsigned ms);
+int ei_connect_ctx_t__(ei_socket_callbacks *cbs, void *ctx, void *addr, int len, unsigned ms);
+int ei_read_fill_ctx__(ei_socket_callbacks *cbs, void *ctx, char* buf, ssize_t *len);
+int ei_write_fill_ctx__(ei_socket_callbacks *cbs, void *ctx, const char *buf, ssize_t *len);
+int ei_read_fill_ctx_t__(ei_socket_callbacks *cbs, void *ctx, char* buf, ssize_t *len, unsigned  ms);
+int ei_write_fill_ctx_t__(ei_socket_callbacks *cbs, void *ctx, const char *buf, ssize_t *len, unsigned ms);
+#if defined(EI_HAVE_STRUCT_IOVEC__)
+int ei_writev_fill_ctx_t__(ei_socket_callbacks *cbs, void *ctx, const struct iovec *iov, int iovcnt, ssize_t *len, unsigned ms);
+int ei_socket_callbacks_have_writev__(ei_socket_callbacks *cbs);
 #endif
 
-int ei_accept_t(int fd, void   *addr,   void  *addrlen, unsigned ms);
-int ei_connect_t(int fd, void *sinp, int sin_siz, unsigned ms);
-int ei_read_fill(int fd, char* buf, int len);
-int ei_write_fill(int fd, const char *buf, int len);
-int ei_read_fill_t(int fd, char* buf, int len, unsigned ms);
-int ei_write_fill_t(int fd, const char *buf, int len, unsigned ms);
-#ifdef HAVE_WRITEV
-int ei_writev_fill_t(int fd,  const  struct  iovec  *iov,  int iovcnt, unsigned ms);
+ei_socket_callbacks ei_default_socket_callbacks;
+
+#define EI_FD_AS_CTX__(FD)                                              \
+    ((void *) (long) (FD))
+
+#define EI_DFLT_CTX_TO_FD__(CTX, FD)                                    \
+    ((int) (long) (CTX) < 0                                             \
+     ? EBADF                                                            \
+     : (*(FD) = (int) (long) (CTX), 0))
+
+#define EI_GET_FD__(CBS, CTX, FD)                                       \
+    ((CBS) == &ei_default_socket_callbacks                              \
+     ? EI_DFLT_CTX_TO_FD__((CTX), FD)                                   \
+     : (CBS)->get_fd((CTX), (FD)))
+
+extern int ei_plugin_socket_impl__;
+
+#if !defined(_REENTRANT)
+
+#define EI_HAVE_PLUGIN_SOCKET_IMPL__                                    \
+    ei_plugin_socket_impl__
+#define EI_SET_HAVE_PLUGIN_SOCKET_IMPL__                                \
+    ei_plugin_socket_impl__ = 1
+
+#elif ((ETHR_HAVE___atomic_load_n & SIZEOF_INT)                         \
+       && (ETHR_HAVE___atomic_store_n & SIZEOF_INT))
+
+#define EI_HAVE_PLUGIN_SOCKET_IMPL__                                    \
+    __atomic_load_n(&ei_plugin_socket_impl__, __ATOMIC_ACQUIRE)
+#define EI_SET_HAVE_PLUGIN_SOCKET_IMPL__                                \
+    __atomic_store_n(&ei_plugin_socket_impl__, 1, __ATOMIC_RELEASE)
+
+#else
+
+/* No gcc atomics; always lookup using ei_get_cbs_ctx()... */
+#define EI_HAVE_PLUGIN_SOCKET_IMPL__ 0
+#define EI_SET_HAVE_PLUGIN_SOCKET_IMPL__ (void) 0
+
+#endif
+
+#define EI_GET_CBS_CTX__(CBS, CTX, FD)                                  \
+    (EI_HAVE_PLUGIN_SOCKET_IMPL__                                       \
+     ? ei_get_cbs_ctx__((CBS), (CTX), (FD))                             \
+     : ((FD) < 0                                                        \
+        ? EBADF                                                         \
+        : (*(CBS) = &ei_default_socket_callbacks,                       \
+           *(CTX) = EI_FD_AS_CTX__((FD)),                               \
+           0)))
+/*      
+ * The following uses our own TCP/IPv4 socket implementation...
+ */
+int ei_socket__(int *fd);
+int ei_close__(int fd);
+int ei_listen__(int fd, void *adr, int *len, int backlog);
+int ei_accept_t__(int *fd, void *addr, int *len, unsigned ms);
+int ei_connect_t__(int fd, void *addr, int len, unsigned ms);
+int ei_read_fill__(int fd, char* buf, ssize_t *len);
+int ei_write_fill__(int fd, const char *buf, ssize_t *len);
+int ei_read_fill_t__(int fd, char* buf, ssize_t *len, unsigned ms);
+int ei_write_fill_t__(int fd, const char *buf, ssize_t *len, unsigned ms);
+#if defined(EI_HAVE_STRUCT_IOVEC__) && defined(HAVE_WRITEV)
+int ei_writev_fill_t__(int fd, const struct iovec *iov, int iovcnt, ssize_t *len, unsigned ms);
 #endif
 
 #endif /* _EI_PORTIO_H */
diff --git a/lib/erl_interface/src/not_used/send_link.c b/lib/erl_interface/src/not_used/send_link.c
index 7be476fd93..38fae27df4 100644
--- a/lib/erl_interface/src/not_used/send_link.c
+++ b/lib/erl_interface/src/not_used/send_link.c
@@ -50,6 +50,7 @@ static int link_unlink(int fd, const erlang_pid *from, const erlang_pid *to,
   char *s;
   int index = 0;
   int n;
+  unsigned tmo = ms == 0 ? EI_SCLBK_INF_TMO : ms;
 
   index = 5;                                     /* max sizes: */
   ei_encode_version(msgbuf,&index);                     /*   1 */
@@ -69,7 +70,7 @@ static int link_unlink(int fd, const erlang_pid *from, const erlang_pid *to,
   if (ei_trace_distribution > 1) ei_show_sendmsg(stderr,msgbuf,NULL);
 #endif
 
-  n = ei_write_fill_t(fd,msgbuf,index,ms); 
+  n = ei_write_fill_t__(fd,msgbuf,index,tmo); 
 
   return (n==index ? 0 : -1);
 }
diff --git a/lib/erl_interface/test/ei_accept_SUITE.erl b/lib/erl_interface/test/ei_accept_SUITE.erl
index 78a433d21b..9c9c3f86b6 100644
--- a/lib/erl_interface/test/ei_accept_SUITE.erl
+++ b/lib/erl_interface/test/ei_accept_SUITE.erl
@@ -81,12 +81,10 @@ ei_accept(Config) when is_list(Config) ->
 
 ei_threaded_accept(Config) when is_list(Config) ->
     Einode = filename:join(proplists:get_value(data_dir, Config), "eiaccnode"),
-    N = 1, % 3,
+    N = 3,
     Host = atom_to_list(node()),
-    Port = 6767,
-    start_einode(Einode, N, Host, Port),
+    start_einode(Einode, N, Host),
     io:format("started eiaccnode"),
-    %%spawn_link(fun() -> start_einode(Einode, N, Host, Port) end),
     TestServerPid = self(),
     [spawn_link(fun() -> send_rec_einode(I, TestServerPid) end) || I <- lists:seq(0, N-1)],
     [receive I -> ok end || I <- lists:seq(0, N-1) ],
@@ -159,10 +157,9 @@ send_rec_einode(N, TestServerPid) ->
               ct:fail(EINode)
     end.
 
-start_einode(Einode, N, Host, Port) ->
+start_einode(Einode, N, Host) ->
     Einodecmd = Einode ++ " " ++ atom_to_list(erlang:get_cookie())
-    ++ " " ++ integer_to_list(N) ++ " " ++ Host ++ " "
-    ++ integer_to_list(Port) ++ " nothreads",
+    ++ " " ++ integer_to_list(N) ++ " " ++ Host,
     io:format("Einodecmd  ~p ~n", [Einodecmd]),      
     open_port({spawn, Einodecmd}, []),
     ok.
diff --git a/lib/erl_interface/test/ei_accept_SUITE_data/ei_accept_test.c b/lib/erl_interface/test/ei_accept_SUITE_data/ei_accept_test.c
index 50df848b69..f41d741609 100644
--- a/lib/erl_interface/test/ei_accept_SUITE_data/ei_accept_test.c
+++ b/lib/erl_interface/test/ei_accept_SUITE_data/ei_accept_test.c
@@ -125,45 +125,26 @@ static void cmd_ei_connect_init(char* buf, int len)
     ei_x_free(&res);
 }
 
-static int my_listen(int port)
-{
-    int listen_fd;
-    struct sockaddr_in addr;
-    const char *on = "1";
-    
-    if ((listen_fd = socket(AF_INET, SOCK_STREAM, 0)) < 0)
-	return -1;
-    
-    setsockopt(listen_fd, SOL_SOCKET, SO_REUSEADDR, on, sizeof(on));
-    
-    memset((void*) &addr, 0, (size_t) sizeof(addr));
-    addr.sin_family = AF_INET;
-    addr.sin_port = htons(port);
-    addr.sin_addr.s_addr = htonl(INADDR_ANY);
-    
-    if (bind(listen_fd, (struct sockaddr*) &addr, sizeof(addr)) < 0)
-	return -1;
-
-    listen(listen_fd, 5);
-    return listen_fd;
-}
-
 static void cmd_ei_publish(char* buf, int len)
 {
     int index = 0;
-    int listen, r;
-    long port;
+    int iport, lfd, r;
+    long lport;
     ei_x_buff x;
     int i;
 
     /* get port */
-    if (ei_decode_long(buf, &index, &port) < 0)
+    if (ei_decode_long(buf, &index, &lport) < 0)
 	fail("expected int (port)");
     /* Make a listen socket */
-    if ((listen = my_listen(port)) <= 0)
+
+    iport = (int) lport;
+    lfd = ei_listen(&ec, &iport, 5);
+    if (lfd < 0)
 	fail("listen");
+    lport = (long) iport;
     
-    if ((i = ei_publish(&ec, port)) == -1)
+    if ((i = ei_publish(&ec, lport)) == -1)
 	fail("ei_publish");
 #ifdef VXWORKS
     save_fd(i);
@@ -171,7 +152,7 @@ static void cmd_ei_publish(char* buf, int len)
     /* send listen-fd, result and errno */
     ei_x_new_with_version(&x);
     ei_x_encode_tuple_header(&x, 3);
-    ei_x_encode_long(&x, listen);
+    ei_x_encode_long(&x, (long) lfd);
     ei_x_encode_long(&x, i);
     ei_x_encode_long(&x, erl_errno);
     send_bin_term(&x);
diff --git a/lib/erl_interface/test/ei_accept_SUITE_data/eiaccnode.c b/lib/erl_interface/test/ei_accept_SUITE_data/eiaccnode.c
index 308f843530..c850d20f3c 100644
--- a/lib/erl_interface/test/ei_accept_SUITE_data/eiaccnode.c
+++ b/lib/erl_interface/test/ei_accept_SUITE_data/eiaccnode.c
@@ -47,8 +47,6 @@
 #define MAIN main
 #endif
 
-static int my_listen(int port);
-
 /*
    A small einode.
    To be called from the test case ei_accept_SUITE:multi_thread
@@ -64,7 +62,6 @@ static int my_listen(int port);
 */
 
 static const char* cookie, * desthost;
-static int port; /* actually base port */
 
 #ifndef SD_SEND
 #ifdef SHUTWR
@@ -74,10 +71,6 @@ static int port; /* actually base port */
 #endif
 #endif
 
-#ifndef __WIN32__
-#define closesocket(fd) close(fd)
-#endif
-
 #ifdef __WIN32__
 static DWORD WINAPI
 #else
@@ -86,26 +79,32 @@ static void*
     einode_thread(void* num)
 {
     int n = (int)num;
+    int port;
     ei_cnode ec;
-    char myname[100], destname[100];
+    char myname[100], destname[100], filename[100];
     int r, fd, listen;
     ErlConnect conn;
     erlang_msg msg;
-/*    FILE* f;*/
+    FILE* file;
 
-    sprintf(myname, "eiacc%d", n);
-    printf("thread %d (%s) listening\n", n, myname, destname);
+    sprintf(filename, "eiacc%d_trace.txt", n);
+    file = fopen(filename, "w");
+
+    sprintf(myname, "eiacc%d", n); fflush(file);
     r = ei_connect_init(&ec, myname, cookie, 0);
-    if ((listen = my_listen(port+n)) <= 0) {
-	printf("listen err\n");
+    port = 0;
+    listen = ei_listen(&ec, &port, 5);
+    if (listen <= 0) {
+	fprintf(file, "listen err\n"); fflush(file);
 	exit(7);
     }
-    if (ei_publish(&ec, port + n) == -1) {
-	printf("ei_publish port %d\n", port+n);
+    fprintf(file, "thread %d (%s:%s) listening on port %d\n", n, myname, destname, port);
+    if (ei_publish(&ec, port) == -1) {
+	fprintf(file, "ei_publish port %d\n", port+n); fflush(file);
 	exit(8);
     }
     fd = ei_accept(&ec, listen, &conn);
-    printf("ei_accept %d\n", fd);
+    fprintf(file, "ei_accept %d\n", fd); fflush(file);
     if (fd >= 0) {
 	ei_x_buff x, xs;
 	int index, version;
@@ -117,37 +116,38 @@ static void*
 	    if (got == ERL_TICK)
 		continue;
 	    if (got == ERL_ERROR) {
-		printf("receive error %d\n", n);
+		fprintf(file, "receive error %d\n", n); fflush(file);
 		return 0;
 	    }
-	    printf("received %d\n", got);
+	    fprintf(file, "received %d\n", got); fflush(file);
 	    break;
 	}
 	index = 0;
 	if (ei_decode_version(x.buff, &index, &version) != 0) {
-	    printf("ei_decode_version %d\n", n);
+	    fprintf(file, "ei_decode_version %d\n", n); fflush(file);
 	    return 0;
 	}
 	if (ei_decode_pid(x.buff, &index, &pid) != 0) {
-	    printf("ei_decode_pid %d\n", n);
+	    fprintf(file, "ei_decode_pid %d\n", n); fflush(file);
 	    return 0;
 	}
-/*	fprintf(f, "got pid from %s \n", pid.node);*/
+	fprintf(file, "got pid from %s \n", pid.node); fflush(file);
 	ei_x_new_with_version(&xs);
 	ei_x_encode_tuple_header(&xs, 2);
 	ei_x_encode_long(&xs, n);
 	ei_x_encode_pid(&xs, &pid);
 	r = ei_send(fd, &pid, xs.buff, xs.index);
-/*	fprintf(f, "sent %d bytes %d\n", xs.index, r);*/
+	fprintf(file, "sent %d bytes %d\n", xs.index, r); fflush(file);
 	shutdown(fd, SD_SEND);
-	closesocket(fd);
+        ei_close_connection(fd);
 	ei_x_free(&x);
 	ei_x_free(&xs);
     } else {
-	printf("coudn't connect fd %d r %d\n", fd, r);
+	fprintf(file, "coudn't connect fd %d r %d\n", fd, r); fflush(file);
     }
-    printf("done thread %d\n", n);
-/*    fclose(f);*/
+    ei_close_connection(listen);
+    fprintf(file, "done thread %d\n", n);
+    fclose(file);
     return 0;
 }
 
@@ -170,12 +170,14 @@ MAIN(int argc, char *argv[])
     if (n > 100)
 	exit(2);
     desthost = argv[3];
-    port = atoi(argv[4]);
-#ifndef VXWORKS	   
-    no_threads = argv[5] != NULL && strcmp(argv[5], "nothreads") == 0;
-#else
+    if (argc == 3)
+        no_threads = 0;
+    else
+        no_threads = argv[4] != NULL && strcmp(argv[4], "nothreads") == 0;
+#ifdef VXWORKS
     no_threads = 1;
 #endif
+
     for (i = 0; i < n; ++i) {
 	if (!no_threads) {
 #ifndef VXWORKS
@@ -209,27 +211,3 @@ MAIN(int argc, char *argv[])
     printf("ok\n");
     return 0;
 }
-
-static int my_listen(int port)
-{
-    int listen_fd;
-    struct sockaddr_in addr;
-    const char *on = "1";
-    
-    if ((listen_fd = socket(AF_INET, SOCK_STREAM, 0)) < 0)
-	return -1;
-    
-    setsockopt(listen_fd, SOL_SOCKET, SO_REUSEADDR, on, sizeof(on));
-    
-    memset((void*) &addr, 0, (size_t) sizeof(addr));
-    addr.sin_family = AF_INET;
-    addr.sin_port = htons(port);
-    addr.sin_addr.s_addr = htonl(INADDR_ANY);
-    
-    if (bind(listen_fd, (struct sockaddr*) &addr, sizeof(addr)) < 0)
-	return -1;
-
-    listen(listen_fd, 5);
-    return listen_fd;
-}
-
diff --git a/lib/erl_interface/test/erl_eterm_SUITE_data/cnode.c b/lib/erl_interface/test/erl_eterm_SUITE_data/cnode.c
index bead0f8413..b87feb9dfc 100644
--- a/lib/erl_interface/test/erl_eterm_SUITE_data/cnode.c
+++ b/lib/erl_interface/test/erl_eterm_SUITE_data/cnode.c
@@ -20,7 +20,7 @@
 
 #include <stdlib.h>
 #include <stdio.h>
-
+#include <string.h>
 #include "ei.h"
 #include "erl_interface.h"
 
@@ -68,6 +68,7 @@ MAIN(int argc, char **argv)
     char host[80];
     int number;
     ETERM *ref, *ref1, *ref2;
+    FILE *dfile = fopen("cnode_debug_printout", "w");
 
     erl_init(NULL, 0);
 
@@ -80,28 +81,30 @@ MAIN(int argc, char **argv)
     gethostname(host, sizeof(host));
     sprintf(node, "c%d@%s", number, host);
 
-    printf("s = %d\n", s);
+    fprintf(dfile, "s = %d\n", s); fflush(dfile);
 
     sprintf(server, "test_server@%s", host);
     fd = erl_connect(server);
-    printf("fd = %d\n", fd);
+    fprintf(dfile, "fd = %d\n", fd);
 
-/*    printf("dist = %d\n", erl_distversion(fd)); */
+/*    fprintf(dfile, "dist = %d\n", erl_distversion(fd)); */
 
 #if 1
     ref = erl_mk_long_ref(node, 4711, 113, 98, 0);
 #else
     ref = erl_mk_ref(node, 4711, 0);
 #endif
-    printf("ref = %d\n", ref);
+    fprintf(dfile, "ref = %p\n", ref); fflush(dfile);
 
     s = erl_reg_send(fd, "mip", ref);
-    printf("s = %d\n", s);
+    fprintf(dfile, "s = %d\n", s); fflush(dfile);
 
     {
       ETERM* emsg;
       emsg = SELF(fd);
-      erl_reg_send(fd,"mip",emsg);
+      fprintf(dfile, "pid = %p\n", emsg); fflush(dfile);
+      s = erl_reg_send(fd,"mip",emsg);
+      fprintf(dfile, "s2 = %d\n", s); fflush(dfile);
       erl_free_term(emsg);
     }
 
@@ -116,28 +119,29 @@ MAIN(int argc, char **argv)
 #endif
 	switch (s) {
 	  case ERL_TICK:
-	    printf("tick\n");
+	    fprintf(dfile, "tick\n");
 	    break;
 	  case ERL_ERROR:
-	    printf("error\n");
+            fprintf(dfile, "error: %s (%d)\n", strerror(erl_errno), erl_errno);
 	    break;
 	  case ERL_MSG:
-	    printf("msg %d\n", msgsize);
+	    fprintf(dfile, "msg %d\n", msgsize);
 	    break;
 	  default:
-	    printf("unknown result %d\n", s);
+	    fprintf(dfile, "unknown result %d\n", s);
 	    break;
 	}
+        fflush(dfile);
     } while (s == ERL_TICK);
 
     s = erl_reg_send(fd, "mip", msg.msg);
-    printf("s = %d\n", s);
+    fprintf(dfile, "s = %d\n", s); fflush(dfile);
     s = erl_reg_send(fd, "mip", msg.to);
-    printf("s = %d\n", s);
+    fprintf(dfile, "s = %d\n", s); fflush(dfile);
 #if 0
     /* from = NULL! */
     s = erl_reg_send(fd, "mip", msg.from);
-    printf("s = %d\n", s);
+    fprintf(dfile, "s = %d\n", s); fflush(dfile);
 #endif
 
 #if 0
@@ -150,17 +154,19 @@ MAIN(int argc, char **argv)
     ref1 = erl_mk_long_ref(node, 4711, 113, 98, 0);
     ref2 = erl_mk_ref(node, 4711, 0);
     s = erl_encode(ref1, buf1);
-    printf("enc1 s = %d\n", s);
+    fprintf(dfile, "enc1 s = %d\n", s); fflush(dfile);
     s = erl_encode(ref2, buf2);
-    printf("enc2 s = %d\n", s);
+    fprintf(dfile, "enc2 s = %d\n", s); fflush(dfile);
     s = erl_compare_ext(buf1, buf2);
-    printf("comp s = %d\n", s);
+    fprintf(dfile, "comp s = %d\n", s); fflush(dfile);
     
     /* Compare, in another way */
     s = erl_match(ref1, ref2);
-    printf("match s = %d\n", s);
+    fprintf(dfile, "match s = %d\n", s); fflush(dfile);
 #endif
 
+    fclose(dfile);
+
     erl_close_connection(fd);
 
     return 0;