Merge branch 'raimo/uds-support/OTP-13643'

* raimo/uds-support/OTP-13643:
  Document the local (unix) address family
  Remove internal state BOUND from inet_drv

12 files changed, 207 insertions, 104 deletions

diff --git a/erts/emulator/drivers/common/inet_drv.c b/erts/emulator/drivers/common/inet_drv.c
index 06dfb2dd10..93ea9f5dcb 100644
--- a/erts/emulator/drivers/common/inet_drv.c
+++ b/erts/emulator/drivers/common/inet_drv.c
@@ -627,6 +627,7 @@ static int is_nonzero(const char *s, size_t n)
 */
 
 /* general address encode/decode tag */
+#define INET_AF_UNSPEC      0
 #define INET_AF_INET        1
 #define INET_AF_INET6       2
 #define INET_AF_ANY         3 /* INADDR_ANY or IN6ADDR_ANY_INIT */
@@ -655,7 +656,7 @@ static int is_nonzero(const char *s, size_t n)
 
 /* INET_REQ_GETSTATUS enumeration */
 #define INET_F_OPEN         0x0001
-#define INET_F_BOUND        0x0002
+/* INET_F_BOUND removed - renumber when there comes a bigger rewrite */
 #define INET_F_ACTIVE       0x0004
 #define INET_F_LISTEN       0x0008
 #define INET_F_CON          0x0010
@@ -853,19 +854,15 @@ static int is_nonzero(const char *s, size_t n)
 
 #define INET_STATE_CLOSED          (0)
 #define INET_STATE_OPEN            (INET_F_OPEN)
-#define INET_STATE_BOUND           (INET_STATE_OPEN | INET_F_BOUND)
-#define INET_STATE_CONNECTED       (INET_STATE_BOUND | INET_F_ACTIVE)
-#define INET_STATE_LISTENING       (INET_STATE_BOUND | INET_F_LISTEN)
-#define INET_STATE_CONNECTING      (INET_STATE_BOUND | INET_F_CON)
+#define INET_STATE_CONNECTED       (INET_STATE_OPEN | INET_F_ACTIVE)
+#define INET_STATE_LISTENING       (INET_STATE_OPEN | INET_F_LISTEN)
+#define INET_STATE_CONNECTING      (INET_STATE_OPEN | INET_F_CON)
 #define INET_STATE_ACCEPTING       (INET_STATE_LISTENING | INET_F_ACC)
 #define INET_STATE_MULTI_ACCEPTING (INET_STATE_ACCEPTING | INET_F_MULTI_CLIENT)
 
 #define IS_OPEN(d) \
  (((d)->state & INET_F_OPEN) == INET_F_OPEN)
 
-#define IS_BOUND(d) \
- (((d)->state & INET_F_BOUND) == INET_F_BOUND)
-
 #define IS_CONNECTED(d) \
   (((d)->state & INET_STATE_CONNECTED) == INET_STATE_CONNECTED)
 
@@ -1287,6 +1284,7 @@ static int async_ref = 0;          /* async reference id generator */
 
 static ErlDrvTermData am_ok;
 static ErlDrvTermData am_undefined;
+static ErlDrvTermData am_unspec;
 static ErlDrvTermData am_tcp;
 static ErlDrvTermData am_error;
 static ErlDrvTermData am_einval;
@@ -1553,10 +1551,18 @@ static int load_address(ErlDrvTermData* spec, int i, char* buf)
 	break;
     }
 #endif
-    default: { /* INET_AF_UNDEFINED */
-        i = LOAD_ATOM(spec, i, am_undefined);
+    case INET_AF_UNSPEC: {
+        i = LOAD_ATOM(spec, i, am_unspec);
+	i = LOAD_BUF2BINARY(spec, i, buf, 0);
+	spec[i++] = ERL_DRV_TUPLE;
+	spec[i++] = 2;
 	spec[i++] = ERL_DRV_INT;
 	spec[i++] = 0;
+	break;
+    }
+    default: { /* INET_AF_UNDEFINED */
+        i = LOAD_ATOM(spec, i, am_undefined);
+	i = LOAD_BUF2BINARY(spec, i, buf, 0);
 	spec[i++] = ERL_DRV_TUPLE;
 	spec[i++] = 2;
 	spec[i++] = ERL_DRV_INT;
@@ -3823,6 +3829,7 @@ static int inet_init()
 
     INIT_ATOM(ok);
     INIT_ATOM(undefined);
+    INIT_ATOM(unspec);
     INIT_ATOM(tcp);
 #ifdef HAVE_UDP
     INIT_ATOM(udp);
@@ -4149,6 +4156,10 @@ static int inet_get_address(char* dst, inet_address* src, unsigned int* len)
         return 0;
       }
 #endif
+    else if (family == AF_UNSPEC) {
+        dst[0] = INET_AF_UNSPEC;
+	*len = 1;
+    }
     else {
         dst[0] = INET_AF_UNDEFINED;
 	*len = 1;
@@ -4419,10 +4430,12 @@ static ErlDrvSSizeT inet_ctl_fdopen(inet_descriptor* desc, int domain, int type,
                                     char** rbuf, ErlDrvSizeT rsize)
 {
     inet_address name;
-    unsigned int sz = sizeof(name);
+    unsigned int sz;
 
     if (bound) {
         /* check that it is a socket and that the socket is bound */
+        sz = sizeof(name);
+	sys_memzero((char *) &name, sz);
         if (IS_SOCKET_ERROR(sock_name(s, (struct sockaddr*) &name, &sz)))
             return ctl_error(sock_errno(), rbuf, rsize);
         if (name.sa.sa_family != domain)
@@ -4437,10 +4450,7 @@ static ErlDrvSSizeT inet_ctl_fdopen(inet_descriptor* desc, int domain, int type,
     driver_select(desc->port, desc->event, ERL_DRV_READ, 1);
 #endif
 
-    if (bound)
-        desc->state = INET_STATE_BOUND;
-    else
-        desc->state = INET_STATE_OPEN;
+    desc->state = INET_STATE_OPEN;
 
     if (type == SOCK_STREAM) { /* check if connected */
 	sz = sizeof(name);
@@ -8448,7 +8458,6 @@ static ErlDrvSSizeT inet_ctl(inet_descriptor* desc, int cmd, char* buf,
 	if (len != 4) return ctl_error(EINVAL, rbuf, rsize);
 
 	if (! IS_OPEN(desc)) return ctl_xerror(EXBADPORT, rbuf, rsize);
-	if (! IS_BOUND(desc)) return ctl_xerror(EXBADSEQ, rbuf, rsize);
 
 #ifdef HAVE_SCTP
 	if (IS_SCTP(desc) && p_sctp_getpaddrs) {
@@ -8524,7 +8533,6 @@ static ErlDrvSSizeT inet_ctl(inet_descriptor* desc, int cmd, char* buf,
 	if (len != 4) return ctl_error(EINVAL, rbuf, rsize);
 
 	if (! IS_OPEN(desc)) return ctl_xerror(EXBADPORT, rbuf, rsize);
-	if (! IS_BOUND(desc)) return ctl_xerror(EXBADSEQ, rbuf, rsize);
 
 #ifdef HAVE_SCTP
 	if (IS_SCTP(desc) && p_sctp_getladdrs) {
@@ -8546,6 +8554,7 @@ static ErlDrvSSizeT inet_ctl(inet_descriptor* desc, int cmd, char* buf,
 	    int i;
 
 	    sz = sizeof(addr);
+	    sys_memzero((char *) &addr, sz);
 	    i = sock_name(desc->s, (struct sockaddr *) &addr, &sz);
 	    return reply_inet_addrs(i >= 0 ? 1 : i, &addr, rbuf, rsize, sz);
 	}
@@ -8559,15 +8568,13 @@ static ErlDrvSSizeT inet_ctl(inet_descriptor* desc, int cmd, char* buf,
 
 	DEBUGF(("inet_ctl(%ld): NAME\r\n", (long)desc->port)); 
 
-	if (!IS_BOUND(desc))
-	    return ctl_error(EINVAL, rbuf, rsize); /* address is not valid */
-
 	if ((ptr = desc->name_ptr) != NULL) {
 	    sz = desc->name_addr_len;
 	}
 	else {
 	    ptr = &name;
 	    sz = sizeof(name);
+	    sys_memzero((char *) &name, sz);
 	    if (IS_SOCKET_ERROR
 		(sock_name(desc->s, (struct sockaddr*)ptr, &sz)))
 		return ctl_error(sock_errno(), rbuf, rsize);
@@ -8612,11 +8619,12 @@ static ErlDrvSSizeT inet_ctl(inet_descriptor* desc, int cmd, char* buf,
 	if (IS_SOCKET_ERROR(sock_bind(desc->s,(struct sockaddr*) &local, len)))
 	    return ctl_error(sock_errno(), rbuf, rsize);
 
-	desc->state = INET_STATE_BOUND;
+	desc->state = INET_STATE_OPEN;
 
 	port = inet_address_port(&local);
 	if (port == 0) {
 	    SOCKLEN_T adrlen = sizeof(local);
+	    sys_memzero((char *) &local, adrlen);
 	    sock_name(desc->s, &local.sa, &adrlen);
 	    port = inet_address_port(&local);
 	}
@@ -9136,8 +9144,6 @@ static ErlDrvSSizeT tcp_inet_ctl(ErlDrvData e, unsigned int cmd,
 	    return ctl_xerror(EXBADPORT, rbuf, rsize);
 	if (!IS_OPEN(INETP(desc)))
 	    return ctl_xerror(EXBADPORT, rbuf, rsize);
-	if (!IS_BOUND(INETP(desc)))
-	    return ctl_xerror(EXBADSEQ, rbuf, rsize);
 	if (len != 2)
 	    return ctl_error(EINVAL, rbuf, rsize);
 	backlog = get_int16(buf);
@@ -9160,8 +9166,6 @@ static ErlDrvSSizeT tcp_inet_ctl(ErlDrvData e, unsigned int cmd,
 	    return ctl_xerror(EXBADPORT, rbuf, rsize);
 	if (IS_CONNECTED(INETP(desc)))
 	    return ctl_error(EISCONN, rbuf, rsize);
-	if (!IS_BOUND(INETP(desc)))
-	    return ctl_xerror(EXBADSEQ, rbuf, rsize);
 	if (IS_CONNECTING(INETP(desc)))
 	    return ctl_error(EINVAL, rbuf, rsize);
 	if (len < 6)
@@ -9262,6 +9266,7 @@ static ErlDrvSSizeT tcp_inet_ctl(ErlDrvData e, unsigned int cmd,
 	    return ctl_reply(INET_REP_OK, tbuf, 2, rbuf, rsize);
  	} else {
 	    n = sizeof(desc->inet.remote);
+	    sys_memzero((char *) &remote, n);
 	    s = sock_accept(desc->inet.s, (struct sockaddr*) &remote, &n);
 	    if (s == INVALID_SOCKET) {
 		if (sock_errno() == ERRNO_BLOCK) {
@@ -10147,6 +10152,7 @@ static int tcp_inet_input(tcp_descriptor* desc, HANDLE event)
 	inet_async_op *this_op = desc->inet.opt;
 
 	len = sizeof(desc->inet.remote);
+	sys_memzero((char *) &remote, len);
 	s = sock_accept(desc->inet.s, (struct sockaddr*) &remote, &len);
 	if (s == INVALID_SOCKET && sock_errno() == ERRNO_BLOCK) {
 	    /* Just try again, no real error, just a ghost trigger from poll, 
@@ -10213,6 +10219,7 @@ static int tcp_inet_input(tcp_descriptor* desc, HANDLE event)
 
 	while (desc->inet.state == INET_STATE_MULTI_ACCEPTING) {
 	    len = sizeof(desc->inet.remote);
+	    sys_memzero((char *) &remote, len);
 	    s = sock_accept(desc->inet.s, (struct sockaddr*) &remote, &len);
 	    if (s == INVALID_SOCKET && sock_errno() == ERRNO_BLOCK) {
 		/* Just try again, no real error, keep the last return code */
@@ -10653,7 +10660,7 @@ static int tcp_inet_output(tcp_descriptor* desc, HANDLE event)
 				 (struct sockaddr*) &desc->inet.remote, &sz);
 
 	    if (IS_SOCKET_ERROR(code)) {
-		desc->inet.state = INET_STATE_BOUND;  /* restore state */
+		desc->inet.state = INET_STATE_OPEN;  /* restore state */
 		ret =  async_error(INETP(desc), sock_errno());
 		goto done;
 	    }
@@ -10666,7 +10673,7 @@ static int tcp_inet_output(tcp_descriptor* desc, HANDLE event)
 				   (void *)&error, &sz);
 
 	    if ((code < 0) || error) {
-		desc->inet.state = INET_STATE_BOUND;  /* restore state */
+		desc->inet.state = INET_STATE_OPEN;  /* restore state */
 		ret = async_error(INETP(desc), error);
 		goto done;
 	    }
@@ -11075,8 +11082,6 @@ static ErlDrvSSizeT packet_inet_ctl(ErlDrvData e, unsigned int cmd, char* buf,
 	if (!IS_OPEN(desc))
 	    return ctl_xerror(EXBADPORT, rbuf, rsize);
 
-	if (!IS_BOUND(desc))
-	    return ctl_xerror(EXBADSEQ,  rbuf, rsize);
 #ifdef HAVE_SCTP
 	if (IS_SCTP(desc)) { 
 	    inet_address remote;
@@ -11163,8 +11168,6 @@ static ErlDrvSSizeT packet_inet_ctl(ErlDrvData e, unsigned int cmd, char* buf,
 		return ctl_xerror(EXBADPORT, rbuf, rsize);
 	    if (!IS_OPEN(desc))
 		return ctl_xerror(EXBADPORT, rbuf, rsize);
-	    if (!IS_BOUND(desc))
-		return ctl_xerror(EXBADSEQ, rbuf, rsize);
 
 	    if (len != 2)
 		return ctl_error(EINVAL, rbuf, rsize);
@@ -11211,7 +11214,7 @@ static ErlDrvSSizeT packet_inet_ctl(ErlDrvData e, unsigned int cmd, char* buf,
 			return ctl_error(sock_errno(), rbuf, rsize);
 		}
 
-	    desc->state = INET_STATE_BOUND;
+	    desc->state = INET_STATE_OPEN;
 
 	    return ctl_reply(INET_REP_OK, NULL, 0, rbuf, rsize);
 	}
@@ -11228,8 +11231,6 @@ static ErlDrvSSizeT packet_inet_ctl(ErlDrvData e, unsigned int cmd, char* buf,
 		return ctl_xerror(EXBADPORT, rbuf, rsize);
 	    if (!IS_OPEN(desc))
 		return ctl_xerror(EXBADPORT, rbuf, rsize);
-	    if (!IS_BOUND(desc))
-		return ctl_xerror(EXBADSEQ, rbuf, rsize);
 	    if (! p_sctp_peeloff)
 		return ctl_error(ENOTSUP, rbuf, rsize);
 
@@ -11270,8 +11271,6 @@ static ErlDrvSSizeT packet_inet_ctl(ErlDrvData e, unsigned int cmd, char* buf,
 	    /* INPUT: Timeout(4), Length(4) */
 	    if (!IS_OPEN(desc))
 		return ctl_xerror(EXBADPORT, rbuf, rsize);
-	    if (!IS_BOUND(desc))
-		return ctl_error(EINVAL, rbuf, rsize);
 	    if (desc->active || (len != 8))
 		return ctl_error(EINVAL, rbuf, rsize);
 	    timeout = get_int32(buf);
@@ -11336,10 +11335,6 @@ static void packet_inet_command(ErlDrvData e, char* buf, ErlDrvSizeT len)
 	inet_reply_error(desc, EINVAL);
 	return;
     }
-    if (!IS_BOUND(desc)) {
-	inet_reply_error(desc, EINVAL);
-	return;
-    }
 
 #ifdef HAVE_SCTP
     if (IS_SCTP(desc))
@@ -11470,6 +11465,8 @@ static int packet_inet_input(udp_descriptor* udesc, HANDLE event)
     while(packet_count--) {
 	unsigned int len = sizeof(other);
 
+	sys_memzero((char *) &other, sizeof(other));
+
 	/* udesc->i_buf is only kept between SCTP fragments */
 	if (udesc->i_buf == NULL) {
 	    udesc->i_bufsz = desc->bufsz + len;
@@ -11665,7 +11662,7 @@ static int packet_inet_output(udp_descriptor* udesc, HANDLE event)
 				 (struct sockaddr*) &desc->remote, &sz);
 
 	    if (IS_SOCKET_ERROR(code)) {
-		desc->state = INET_STATE_BOUND;  /* restore state */
+		desc->state = INET_STATE_OPEN;  /* restore state */
 		ret =  async_error(desc, sock_errno());
 		goto done;
 	    }
@@ -11678,7 +11675,7 @@ static int packet_inet_output(udp_descriptor* udesc, HANDLE event)
 				   (void *)&error, &sz);
 
 	    if ((code < 0) || error) {
-		desc->state = INET_STATE_BOUND;  /* restore state */
+		desc->state = INET_STATE_OPEN;  /* restore state */
 		ret = async_error(desc, error);
 		goto done;
 	    }
diff --git a/erts/preloaded/ebin/prim_inet.beam b/erts/preloaded/ebin/prim_inet.beam
index edb86d35a6..fdf8bbf4e2 100644
--- a/erts/preloaded/ebin/prim_inet.beam
+++ b/erts/preloaded/ebin/prim_inet.beam
diff --git a/erts/preloaded/src/prim_inet.erl b/erts/preloaded/src/prim_inet.erl
index 71dbfbd0a7..560810d222 100644
--- a/erts/preloaded/src/prim_inet.erl
+++ b/erts/preloaded/src/prim_inet.erl
@@ -1746,8 +1746,8 @@ enc_value_2(addr, {inet6,{IP,Port}}) ->
     [?INET_AF_INET6,?int16(Port)|ip6_to_bytes(IP)];
 enc_value_2(addr, {local,Addr}) ->
     %% A binary is passed as is, but anything else will be
-    %% regarded as a filename and therefore UTF-8 encoded
-    %% if the system filename encoding flag so dictates.
+    %% regarded as a filename and therefore encoded according to
+    %% the current system filename encoding mode.
     Bin =
 	if
 	    is_binary(Addr) ->
diff --git a/lib/kernel/doc/src/gen_tcp.xml b/lib/kernel/doc/src/gen_tcp.xml
index b75d42d198..88135ea43d 100644
--- a/lib/kernel/doc/src/gen_tcp.xml
+++ b/lib/kernel/doc/src/gen_tcp.xml
@@ -153,17 +153,17 @@ do_recv(Sock, Bs) ->
           <c><anno>Address</anno></c> can be a hostname or an IP address.</p>
         <p>The following options are available:</p>
         <taglist>
-          <tag><c>{ip, ip_address()}</c></tag>
+          <tag><c>{ip, Address}</c></tag>
           <item><p>If the host has many network interfaces, this option
             specifies which one to use.</p></item>
-          <tag><c>{ifaddr, ip_address()}</c></tag>
-          <item><p>Same as <c>{ip, ip_address()}</c>. If the host has many
+          <tag><c>{ifaddr, Address}</c></tag>
+          <item><p>Same as <c>{ip, Address}</c>. If the host has many
             network interfaces, this option specifies which one to use.</p>
           </item>
           <tag><c>{fd, integer() >= 0}</c></tag>
           <item><p>If a socket has somehow been connected without using
             <c>gen_tcp</c>, use this option to pass the file descriptor
-            for it. If <c>{ip, ip_address()}</c> and/or
+            for it. If <c>{ip, Address}</c> and/or
             <c>{port, port_number()}</c> is combined with this option,  the
             <c>fd</c> is bound to the specified interface and port before
             connecting. If these options are not specified, it is assumed that
@@ -175,9 +175,10 @@ do_recv(Sock, Bs) ->
 	  <tag><c>local</c></tag>
 	  <item>
             <p>
-	      Sets up the socket for local address family. This option is only
-              valid together with <c>{fd, integer()}</c> when the file descriptor
-              is of local address family (e.g. a Unix Domain Socket)
+	      Sets up a Unix Domain Socket. See
+	      <seealso marker="inet#type-local_address">
+		<c>inet:local_address()</c>
+	      </seealso>
 	    </p>
           </item>
           <tag><c>{port, Port}</c></tag>
@@ -254,7 +255,7 @@ do_recv(Sock, Bs) ->
           <item><p><c>B</c> is an integer &gt;= <c>0</c>. The backlog value
             defines the maximum length that the queue of pending connections
             can grow to. Defaults to <c>5</c>.</p></item>
-          <tag><c>{ip, ip_address()}</c></tag>
+          <tag><c>{ip, Address}</c></tag>
           <item><p>If the host has many network interfaces, this option
             specifies which one to listen on.</p></item>
           <tag><c>{port, Port}</c></tag>
@@ -263,8 +264,8 @@ do_recv(Sock, Bs) ->
           <item><p>If a socket has somehow been connected without using
             <c>gen_tcp</c>, use this option to pass the file
             descriptor for it.</p></item>
-          <tag><c>{ifaddr, ip_address()}</c></tag>
-          <item><p>Same as <c>{ip, ip_address()}</c>. If the host has many
+          <tag><c>{ifaddr, Address}</c></tag>
+          <item><p>Same as <c>{ip, Address}</c>. If the host has many
             network interfaces, this option specifies which one to use.</p>
           </item>
           <tag><c>inet6</c></tag>
diff --git a/lib/kernel/doc/src/gen_udp.xml b/lib/kernel/doc/src/gen_udp.xml
index ca9d9c978c..3f88a0272d 100644
--- a/lib/kernel/doc/src/gen_udp.xml
+++ b/lib/kernel/doc/src/gen_udp.xml
@@ -85,11 +85,11 @@
           <item><p>Received <c>Packet</c> is delivered as a list.</p></item>
           <tag><c>binary</c></tag>
           <item><p>Received <c>Packet</c> is delivered as a binary.</p></item>
-          <tag><c>{ip, ip_address()}</c></tag>
+          <tag><c>{ip, Address}</c></tag>
           <item><p>If the host has many network interfaces, this option
             specifies which one to use.</p></item>
-          <tag><c>{ifaddr, ip_address()}</c></tag>
-          <item><p>Same as <c>{ip, ip_address()}</c>. If the host has many
+          <tag><c>{ifaddr, Address}</c></tag>
+          <item><p>Same as <c>{ip, Address}</c>. If the host has many
             network interfaces, this option specifies which one to
             use.</p></item>
           <tag><c>{fd, integer() >= 0}</c></tag>
@@ -107,9 +107,10 @@
 	  <tag><c>local</c></tag>
 	  <item>
             <p>
-	      Sets up the socket for local address family. This option is only
-              valid together with <c>{fd, integer()}</c> when the file descriptor
-              is of local address family (e.g. a Unix Domain Socket)
+	      Sets up a Unix Domain Socket. See
+	      <seealso marker="inet#type-local_address">
+		<c>inet:local_address()</c>
+	      </seealso>
 	    </p>
           </item>
           <tag><c>{udp_module, module()}</c></tag>
@@ -184,8 +185,10 @@
       <name name="send" arity="4"/>
       <fsummary>Send a packet.</fsummary>
       <desc>
-        <p>Sends a packet to the specified address and port. Argument
-          <c><anno>Address</anno></c> can be a hostname or an IP address.</p>
+        <p>
+	  Sends a packet to the specified address and port. Argument
+          <c><anno>Address</anno></c> can be a hostname or a socket address.
+	</p>
       </desc>
     </func>
   </funcs>
diff --git a/lib/kernel/doc/src/inet.xml b/lib/kernel/doc/src/inet.xml
index 5ff167bcb3..c0dce2f50c 100644
--- a/lib/kernel/doc/src/inet.xml
+++ b/lib/kernel/doc/src/inet.xml
@@ -118,6 +118,59 @@ fe80::204:acff:fe17:bf38
       <name name="port_number"/>
     </datatype>
     <datatype>
+      <name name="local_address"/>
+      <desc>
+	<p>
+	  This address family only works on Unix-like systems.
+	</p>
+	<p>
+	  <c><anno>File</anno></c> is normally a file pathname
+	  in a local filesystem.  It is limited in length by the
+	  operating system, traditionally to 108 bytes.
+	</p>
+	<p>
+	  A <c>binary()</c> is passed as is to the operating system,
+	  but a <c>string()</c> is encoded according to the
+	  <seealso marker="file#native_name_encoding/0">
+	    system filename encoding mode.
+	  </seealso>
+	</p>
+	<p>
+	  Other addresses are possible, for example Linux implements
+	  "Abstract Addresses".  See the documentation for
+	  Unix Domain Sockets on your system,
+	  normally <c>unix</c> in manual section 7.
+	</p>
+	<p>
+	  In most API functions where you can use
+	  this address family the port number must be <c>0</c>.
+	</p>
+      </desc>
+    </datatype>
+    <datatype>
+      <name name="socket_address"/>
+    </datatype>
+    <datatype>
+      <name name="returned_non_ip_address"/>
+      <desc>
+	<p>
+	  Addresses besides
+	  <seealso marker="#type-ip_address">
+	    <c>ip_address()</c>
+	  </seealso>
+	  ones that are returned from socket API functions.
+	  See in particular
+	  <seealso marker="#type-local_address">
+	    <c>local_address()</c>.
+	  </seealso>
+	  The <c>unspec</c> family corresponds to AF_UNSPEC and can
+	  occur if the other side has no socket address.
+	  The <c>undefined</c> family can only occur in the unlikely
+	  event of an address family that the VM does not recognize.
+	</p>
+      </desc>
+    </datatype>
+    <datatype>
       <name name="posix"/>
       <desc>
         <p>An atom that is named from the POSIX error codes used in Unix,
diff --git a/lib/kernel/src/gen_tcp.erl b/lib/kernel/src/gen_tcp.erl
index 2b3afcd44c..1a21541b7c 100644
--- a/lib/kernel/src/gen_tcp.erl
+++ b/lib/kernel/src/gen_tcp.erl
@@ -96,17 +96,17 @@
         tos |
 	ipv6_v6only.
 -type connect_option() ::
-        {ip, inet:ip_address()} |
+        {ip, inet:socket_address()} |
         {fd, Fd :: non_neg_integer()} |
-        {ifaddr, inet:ip_address()} |
+        {ifaddr, inet:socket_address()} |
         inet:address_family() |
         {port, inet:port_number()} |
         {tcp_module, module()} |
         option().
 -type listen_option() ::
-        {ip, inet:ip_address()} |
+        {ip, inet:socket_address()} |
         {fd, Fd :: non_neg_integer()} |
-        {ifaddr, inet:ip_address()} |
+        {ifaddr, inet:socket_address()} |
         inet:address_family() |
         {port, inet:port_number()} |
         {backlog, B :: non_neg_integer()} |
@@ -122,7 +122,7 @@
 %%
 
 -spec connect(Address, Port, Options) -> {ok, Socket} | {error, Reason} when
-      Address :: inet:ip_address() | inet:hostname(),
+      Address :: inet:socket_address() | inet:hostname(),
       Port :: inet:port_number(),
       Options :: [connect_option()],
       Socket :: socket(),
@@ -133,7 +133,7 @@ connect(Address, Port, Opts) ->
 
 -spec connect(Address, Port, Options, Timeout) ->
                      {ok, Socket} | {error, Reason} when
-      Address :: inet:ip_address() | inet:hostname(),
+      Address :: inet:socket_address() | inet:hostname(),
       Port :: inet:port_number(),
       Options :: [connect_option()],
       Timeout :: timeout(),
diff --git a/lib/kernel/src/gen_udp.erl b/lib/kernel/src/gen_udp.erl
index 2227bb3562..98d2f0bcfb 100644
--- a/lib/kernel/src/gen_udp.erl
+++ b/lib/kernel/src/gen_udp.erl
@@ -92,9 +92,9 @@ open(Port) ->
 -spec open(Port, Opts) -> {ok, Socket} | {error, Reason} when
       Port :: inet:port_number(),
       Opts :: [Option],
-      Option :: {ip, inet:ip_address()}
+      Option :: {ip, inet:socket_address()}
               | {fd, non_neg_integer()}
-              | {ifaddr, inet:ip_address()}
+              | {ifaddr, inet:socket_address()}
               | inet:address_family()
               | {port, inet:port_number()}
               | option(),
@@ -114,7 +114,7 @@ close(S) ->
 
 -spec send(Socket, Address, Port, Packet) -> ok | {error, Reason} when
       Socket :: socket(),
-      Address :: inet:ip_address() | inet:hostname(),
+      Address :: inet:socket_address() | inet:hostname(),
       Port :: inet:port_number(),
       Packet :: iodata(),
       Reason :: not_owner | inet:posix().
@@ -148,7 +148,7 @@ send(S, Packet) when is_port(S) ->
                   {ok, {Address, Port, Packet}} | {error, Reason} when
       Socket :: socket(),
       Length :: non_neg_integer(),
-      Address :: inet:ip_address(),
+      Address :: inet:ip_address() | inet:returned_non_ip_address(),
       Port :: inet:port_number(),
       Packet :: string() | binary(),
       Reason :: not_owner | inet:posix().
@@ -166,7 +166,7 @@ recv(S,Len) when is_port(S), is_integer(Len) ->
       Socket :: socket(),
       Length :: non_neg_integer(),
       Timeout :: timeout(),
-      Address :: inet:ip_address(),
+      Address :: inet:ip_address() | inet:returned_non_ip_address(),
       Port :: inet:port_number(),
       Packet :: string() | binary(),
       Reason :: not_owner | inet:posix().
diff --git a/lib/kernel/src/inet.erl b/lib/kernel/src/inet.erl
index de43ea792b..20c64a39ca 100644
--- a/lib/kernel/src/inet.erl
+++ b/lib/kernel/src/inet.erl
@@ -73,8 +73,9 @@
 -export([start_timer/1, timeout/1, timeout/2, stop_timer/1]).
 
 -export_type([address_family/0, hostent/0, hostname/0, ip4_address/0,
-              ip6_address/0, ip_address/0, posix/0, socket/0,
-              port_number/0]).
+              ip6_address/0, ip_address/0, port_number/0,
+	      local_address/0, socket_address/0, returned_non_ip_address/0,
+	      posix/0, socket/0]).
 
 %% imports
 -import(lists, [append/1, duplicate/2, filter/2, foldl/3]).
@@ -98,6 +99,11 @@
 			0..65535,0..65535,0..65535,0..65535}.
 -type ip_address() :: ip4_address() | ip6_address().
 -type port_number() :: 0..65535.
+-type local_address() :: {local, File :: binary() | string()}.
+-type returned_non_ip_address() ::
+	{local, binary()} |
+	{unspec, <<>>} |
+	{undefined, any()}.
 -type posix() :: exbadport | exbadseq | file:posix().
 -type socket() :: port().
 
@@ -138,7 +144,7 @@
 -type socket_protocol() :: 'tcp' | 'udp' | 'sctp'.
 -type socket_type() :: 'stream' | 'dgram' | 'seqpacket'.
 -type socket_address() ::
-	ip_address() | {address_family(), any()} | 'any' | 'loopback'.
+	ip_address() | 'any' | 'loopback' | local_address().
 -type stat_option() :: 
 	'recv_cnt' | 'recv_max' | 'recv_avg' | 'recv_oct' | 'recv_dvi' |
 	'send_cnt' | 'send_max' | 'send_avg' | 'send_oct' | 'send_pend'.
@@ -163,26 +169,33 @@ close(Socket) ->
     end.
 
 
--spec peername(Socket) ->  {ok, {Address, Port}} | {error, posix()} when
-      Socket :: socket(),
-      Address :: ip_address(),
-      Port :: non_neg_integer().
+-spec peername(Socket :: socket()) ->
+		      {ok,
+		       {ip_address(), port_number()} |
+		       returned_non_ip_address()} |
+		      {error, posix()}.
 
 peername(Socket) -> 
     prim_inet:peername(Socket).
 
--spec setpeername(Socket :: socket(), Address :: {ip_address(), port_number()}) ->
-	'ok' | {'error', any()}.
+-spec setpeername(
+	Socket :: socket(),
+	Address ::
+	  {ip_address() | 'any' | 'loopback',
+	   port_number()} |
+	  socket_address()) ->
+			 'ok' | {'error', any()}.
 
 setpeername(Socket, {IP,Port}) ->
     prim_inet:setpeername(Socket, {IP,Port});
 setpeername(Socket, undefined) ->
     prim_inet:setpeername(Socket, undefined).
 
--spec peernames(Socket) -> {ok, [{Address, Port}]} | {error, posix()} when
-      Socket :: socket(),
-      Address :: ip_address(),
-      Port :: non_neg_integer().
+-spec peernames(Socket :: socket()) ->
+		       {ok,
+			[{ip_address(), port_number()} |
+			 returned_non_ip_address()]} |
+		       {error, posix()}.
 
 peernames(Socket) ->
     prim_inet:peernames(Socket).
@@ -198,15 +211,21 @@ peernames(Socket, Assoc) ->
     prim_inet:peernames(Socket, Assoc).
 
 
--spec sockname(Socket) -> {ok, {Address, Port}} | {error, posix()} when
-      Socket :: socket(),
-      Address :: ip_address(),
-      Port :: non_neg_integer().
+-spec sockname(Socket :: socket()) ->
+		      {ok,
+		       {ip_address(), port_number()} |
+		       returned_non_ip_address()} |
+		      {error, posix()}.
 
 sockname(Socket) -> 
     prim_inet:sockname(Socket).
 
--spec setsockname(Socket :: socket(), Address :: {ip_address(), port_number()}) ->
+-spec setsockname(
+	Socket :: socket(),
+	Address ::
+	  {ip_address() | 'any' | 'loopback',
+	   port_number()} |
+	  socket_address()) ->
 	'ok' | {'error', any()}.
 
 setsockname(Socket, {IP,Port}) -> 
@@ -214,10 +233,11 @@ setsockname(Socket, {IP,Port}) ->
 setsockname(Socket, undefined) ->
     prim_inet:setsockname(Socket, undefined).
 
--spec socknames(Socket) -> {ok, [{Address, Port}]} | {error, posix()} when
-      Socket :: socket(),
-      Address :: ip_address(),
-      Port :: non_neg_integer().
+-spec socknames(Socket :: socket()) ->
+		       {ok,
+			[{ip_address(), port_number()} |
+			 returned_non_ip_address()]} |
+		       {error, posix()}.
 
 socknames(Socket) ->
     prim_inet:socknames(Socket).
@@ -1296,7 +1316,17 @@ gethostbyaddr_tm_native(Addr, Timer, Opts) ->
     end.
 
 -spec open(Fd_or_OpenOpts :: integer() | list(),
-	   Addr :: socket_address(),
+	   Addr ::
+	     socket_address() |
+	     {ip_address() | 'any' | 'loopback', % Unofficial
+	      port_number()} |
+	     {inet, % Unofficial
+	      {ip4_address() | 'any' | 'loopback',
+	       port_number()}} |
+	     {inet6, % Unofficial
+	      {ip6_address() | 'any' | 'loopback',
+	       port_number()}} |
+	     undefined, % Internal - no bind()
 	   Port :: port_number(),
 	   Opts :: [socket_setopt()],
 	   Protocol :: socket_protocol(),
@@ -1316,11 +1346,16 @@ open(FdO, Addr, Port, Opts, Protocol, Family, Type, Module)
 	{ok,S} ->
 	    case prim_inet:setopts(S, Opts) of
 		ok ->
-		    case if is_list(Addr) ->
-				 bindx(S, Addr, Port);
-			    true ->
-				 prim_inet:bind(S, Addr, Port)
-			 end of
+		    case
+			case Addr of
+			    undefined ->
+				{ok, undefined};
+			    _ when is_list(Addr) ->
+				bindx(S, Addr, Port);
+			    _ ->
+				prim_inet:bind(S, Addr, Port)
+			end
+		    of
 			{ok, _} -> 
 			    inet_db:register_socket(S, Module),
 			    {ok,S};
diff --git a/lib/kernel/src/inet_int.hrl b/lib/kernel/src/inet_int.hrl
index 32d09fb63c..c8a8962e78 100644
--- a/lib/kernel/src/inet_int.hrl
+++ b/lib/kernel/src/inet_int.hrl
@@ -25,6 +25,7 @@
 %% 
 
 %% family codes to open
+-define(INET_AF_UNSPEC,       0).
 -define(INET_AF_INET,         1).
 -define(INET_AF_INET6,        2).
 -define(INET_AF_ANY,          3). % Fake for ANY in any address family
diff --git a/lib/kernel/src/local_tcp.erl b/lib/kernel/src/local_tcp.erl
index 64085ec42e..e3c67dfbb7 100644
--- a/lib/kernel/src/local_tcp.erl
+++ b/lib/kernel/src/local_tcp.erl
@@ -107,8 +107,14 @@ do_connect(Addr = {?FAMILY, _}, 0, Opts, Time) ->
 	when tuple_size(BAddr) =:= 2, element(1, BAddr) =:= ?FAMILY;
 	     BAddr =:= any ->
 	    case inet:open(
-		   Fd, BAddr, 0, SockOpts,
-		   ?PROTO, ?FAMILY, ?TYPE, ?MODULE) of
+		   Fd,
+		   case BAddr of
+		       any ->
+			   undefined;
+		       _ ->
+			   BAddr
+		   end,
+		   0, SockOpts, ?PROTO, ?FAMILY, ?TYPE, ?MODULE) of
 		{ok, S} ->
 		    case prim_inet:connect(S, Addr, 0, Time) of
 			ok -> {ok,S};
diff --git a/lib/kernel/src/local_udp.erl b/lib/kernel/src/local_udp.erl
index ebb4d2b33f..481a8c4910 100644
--- a/lib/kernel/src/local_udp.erl
+++ b/lib/kernel/src/local_udp.erl
@@ -59,7 +59,14 @@ open(0, Opts) ->
 	when tuple_size(BAddr) =:= 2, element(1, BAddr) =:= ?FAMILY;
 	     BAddr =:= any ->
 	    inet:open(
-	      Fd, BAddr, 0, SockOpts, ?PROTO, ?FAMILY, ?TYPE, ?MODULE);
+	      Fd,
+	      case BAddr of
+		  any ->
+		      undefined;
+		  _ ->
+		      BAddr
+	      end,
+	      0, SockOpts, ?PROTO, ?FAMILY, ?TYPE, ?MODULE);
 	{ok, _} -> exit(badarg)
     end.