Merge branch 'raimo/IPV6_V6ONLY/OTP-8928'

* raimo/IPV6_V6ONLY/OTP-8928:
  kernel: Document socket option ipv6_v6only
  kernel: Add test cases for socket option ipv6_v6only
  erts,kernel: Implement socket option ipv6_v6only in erlang code
  erts: Implement socket option IPV6_V6ONLY
  erts: Add configure test for IPV6_V6ONLY

11 files changed, 307 insertions, 13 deletions

diff --git a/erts/configure.in b/erts/configure.in
index 6ad1951a4e..3256b0cb59 100644
--- a/erts/configure.in
+++ b/erts/configure.in
@@ -2000,8 +2000,12 @@ case "$erts_cv_have_in6addr_loopback" in
              [Define to 1 if you have the variable in6addr_loopback declared.])
 esac
 
-AC_CHECK_DECLS([IN6ADDR_ANY_INIT, IN6ADDR_LOOPBACK_INIT], [], [],
-	       [#include <netinet/in.h>])
+AC_CHECK_DECLS([IN6ADDR_ANY_INIT, IN6ADDR_LOOPBACK_INIT, IPV6_V6ONLY], [], [],
+	       [
+		#include <sys/types.h>
+		#include <sys/socket.h>
+		#include <netinet/in.h>
+	       ])
 
 dnl ----------------------------------------------------------------------
 dnl Checks for features/quirks in the system that affects Erlang.
diff --git a/erts/emulator/drivers/common/inet_drv.c b/erts/emulator/drivers/common/inet_drv.c
index 80f504a361..3210ffa92a 100644
--- a/erts/emulator/drivers/common/inet_drv.c
+++ b/erts/emulator/drivers/common/inet_drv.c
@@ -660,6 +660,7 @@ static int my_strncasecmp(const char *s1, const char *s2, size_t n)
 #define UDP_OPT_MULTICAST_LOOP 13 /* set/get IP multicast loopback */
 #define UDP_OPT_ADD_MEMBERSHIP 14 /* add an IP group membership */
 #define UDP_OPT_DROP_MEMBERSHIP 15 /* drop an IP group membership */
+#define INET_OPT_IPV6_V6ONLY 16 /* IPv6 only socket, no mapped v4 addrs */
 /* LOPT is local options */
 #define INET_LOPT_BUFFER      20  /* min buffer size hint */
 #define INET_LOPT_HEADER      21  /* list header size */
@@ -1167,6 +1168,7 @@ static ErlDrvTermData am_reuseaddr;
 static ErlDrvTermData am_dontroute;
 static ErlDrvTermData am_priority;
 static ErlDrvTermData am_tos;
+static ErlDrvTermData am_ipv6_v6only;
 #endif
 
 /* speical errors for bad ports and sequences */
@@ -3486,6 +3488,7 @@ static void inet_init_sctp(void) {
     INIT_ATOM(dontroute);
     INIT_ATOM(priority);
     INIT_ATOM(tos);
+    INIT_ATOM(ipv6_v6only);
     
     /* Option names */
     INIT_ATOM(sctp_rtoinfo);
@@ -5618,6 +5621,23 @@ static int inet_set_opts(inet_descriptor* desc, char* ptr, int len)
 
 #endif /* HAVE_MULTICAST_SUPPORT */
 
+	case INET_OPT_IPV6_V6ONLY:
+#if HAVE_DECL_IPV6_V6ONLY
+	    proto = IPPROTO_IPV6;
+	    type = IPV6_V6ONLY;
+	    propagate = 1;
+	    DEBUGF(("inet_set_opts(%ld): s=%d, IPV6_V6ONLY=%d\r\n",
+		    (long)desc->port, desc->s, ival));
+	    break;
+#elif defined(__WIN32__) && defined(HAVE_IN6) && defined(AF_INET6)
+	    /* Fake a'la OpenBSD; set to 'true' is fine but 'false' invalid. */
+	    if (ival != 0) continue;
+	    else return -1;
+	    break;
+#else
+	    continue;
+#endif
+
 	case INET_OPT_RAW:
 	    if (len < 8) {
 		return -1;
@@ -5947,6 +5967,22 @@ static int sctp_set_opts(inet_descriptor* desc, char* ptr, int len)
 	    continue; /* Option not supported -- ignore it */
 #	endif
 
+	case INET_OPT_IPV6_V6ONLY:
+#       if HAVE_DECL_IPV6_V6ONLY
+	{
+	    arg.ival= get_int32 (curr);   curr += 4;
+	    proto   = IPPROTO_IPV6;
+	    type    = IPV6_V6ONLY;
+	    arg_ptr = (char*) (&arg.ival);
+	    arg_sz  = sizeof  ( arg.ival);
+	    break;
+	}
+#       elif defined(__WIN32__) && defined(HAVE_IN6) && defined(AF_INET6)
+#           error Here is a fix for Win IPv6 SCTP missing
+#       else
+	    continue; /* Option not supported -- ignore it */
+#       endif
+
 	case SCTP_OPT_AUTOCLOSE:
 	{
 	    arg.ival= get_int32 (curr);	  curr += 4;
@@ -6435,6 +6471,22 @@ static ErlDrvSSizeT inet_fill_opts(inet_descriptor* desc,
 	    break;
 #endif /* HAVE_MULTICAST_SUPPORT */
 
+	case INET_OPT_IPV6_V6ONLY:
+#if HAVE_DECL_IPV6_V6ONLY
+	    proto = IPPROTO_IPV6;
+	    type = IPV6_V6ONLY;
+	    break;
+#elif defined(__WIN32__) && defined(HAVE_IN6) && defined(AF_INET6)
+	    /* Fake reading 'true' */
+	    *ptr++ = opt;
+	    put_int32(1, ptr);
+	    ptr += 4;
+	    continue;
+#else
+	    TRUNCATE_TO(0,ptr);
+	    continue; /* skip - no result */
+#endif
+
 	case INET_OPT_RAW:
 	    {
 		int data_provided;
@@ -6739,6 +6791,7 @@ static ErlDrvSSizeT sctp_fill_opts(inet_descriptor* desc,
 	case INET_OPT_DONTROUTE:
 	case INET_OPT_PRIORITY :
 	case INET_OPT_TOS      :
+	case INET_OPT_IPV6_V6ONLY:
 	case SCTP_OPT_AUTOCLOSE:
 	case SCTP_OPT_MAXSEG   :
 	/* The following options return true or false:	       */
@@ -6811,6 +6864,20 @@ static ErlDrvSSizeT sctp_fill_opts(inet_descriptor* desc,
 		continue;
 #	    endif
 	    }
+	    case INET_OPT_IPV6_V6ONLY:
+#           if HAVE_DECL_IPV6_V6ONLY
+	    {
+		proto  = IPPROTO_IPV6;
+		type   = IPV6_V6ONLY;
+		tag    = am_ipv6_v6only;
+		break;
+	    }
+#           elif defined(__WIN32__) && defined(HAVE_IN6) && defined(AF_INET6)
+#               error Here is a fix for Win IPv6 SCTP needed
+#           else
+		/* Not supported -- ignore */
+		continue;
+#           endif
 	    case SCTP_OPT_AUTOCLOSE:
 	    {
 		proto  = IPPROTO_SCTP;
diff --git a/erts/preloaded/ebin/prim_inet.beam b/erts/preloaded/ebin/prim_inet.beam
index 5409cf2dfc..b2d224e560 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 b639b1efdd..b9800a05da 100644
--- a/erts/preloaded/src/prim_inet.erl
+++ b/erts/preloaded/src/prim_inet.erl
@@ -1062,6 +1062,7 @@ enc_opt(multicast_ttl)   -> ?UDP_OPT_MULTICAST_TTL;
 enc_opt(multicast_loop)  -> ?UDP_OPT_MULTICAST_LOOP;
 enc_opt(add_membership)  -> ?UDP_OPT_ADD_MEMBERSHIP;
 enc_opt(drop_membership) -> ?UDP_OPT_DROP_MEMBERSHIP;
+enc_opt(ipv6_v6only)     -> ?INET_OPT_IPV6_V6ONLY;
 enc_opt(buffer)          -> ?INET_LOPT_BUFFER;
 enc_opt(header)          -> ?INET_LOPT_HEADER;
 enc_opt(active)          -> ?INET_LOPT_ACTIVE;
@@ -1115,6 +1116,7 @@ dec_opt(?UDP_OPT_MULTICAST_TTL)   -> multicast_ttl;
 dec_opt(?UDP_OPT_MULTICAST_LOOP)  -> multicast_loop;
 dec_opt(?UDP_OPT_ADD_MEMBERSHIP)  -> add_membership;
 dec_opt(?UDP_OPT_DROP_MEMBERSHIP) -> drop_membership;
+dec_opt(?INET_OPT_IPV6_V6ONLY)    -> ipv6_v6only;
 dec_opt(?INET_LOPT_BUFFER)        -> buffer;
 dec_opt(?INET_LOPT_HEADER)        -> header;
 dec_opt(?INET_LOPT_ACTIVE)        -> active;
@@ -1178,6 +1180,7 @@ type_opt_1(recbuf)          -> int;
 type_opt_1(priority)        -> int;
 type_opt_1(tos)             -> int;
 type_opt_1(nodelay)         -> bool;
+type_opt_1(ipv6_v6only)     -> bool;
 %% multicast
 type_opt_1(multicast_ttl)   -> int;
 type_opt_1(multicast_loop)  -> bool;
diff --git a/lib/kernel/doc/src/inet.xml b/lib/kernel/doc/src/inet.xml
index 32b4a429dd..d0ed26a18d 100644
--- a/lib/kernel/doc/src/inet.xml
+++ b/lib/kernel/doc/src/inet.xml
@@ -520,6 +520,68 @@ fe80::204:acff:fe17:bf38
 			  </p>
 		  </item>
 
+	  <tag><c>{ipv6_v6only, Boolean}</c></tag>
+	  <item>
+	    <p>
+	      Restricts the socket to only use IPv6, prohibiting any
+	      IPv4 connections. This only applicable for
+	      IPv6 sockets (option <c>inet6</c>).
+	    </p>
+	    <p>
+	      On most platforms this option has to be set on the socket
+	      before associating it to an address. Therefore it is only
+	      reasonable to give it when creating the socket and not
+	      to use it when calling the function
+	      (<seealso marker="#setopts/2">setopts/2</seealso>)
+	      containing this description.
+	    </p>
+	    <p>
+	      The behaviour of a socket with this socket option set to
+	      <c>true</c> is becoming the only portable one. The original
+	      idea when IPv6 was new of using IPv6 for all traffic
+	      is now not recommended by FreeBSD (you can use
+	      <c>{ipv6_v6only,false}</c> to override the recommended
+	      system default value),
+	      forbidden by OpenBSD (the supported GENERIC kernel)
+	      and impossible on Windows (that has separate
+	      IPv4 and IPv6 protocol stacks). Most Linux distros
+	      still have a system default value of <c>false</c>.
+	      This policy shift among operating systems towards
+	      separating IPv6 from IPv4 traffic has evolved since
+	      it gradually proved hard and complicated to get
+	      a dual stack implementation correct and secure.
+	    </p>
+	    <p>
+	      On some platforms the only allowed value for this option
+	      is <c>true</c>, e.g. OpenBSD and Windows. Trying to set
+	      this option to <c>false</c> when creating the socket
+	      will in this case fail.
+	    </p>
+	    <p>
+	      Setting this option on platforms where it does not exist
+	      is ignored and getting this option with
+	      <seealso marker="#getopts/2">getopts/2</seealso>
+	      returns no value. On Windows the option acually does
+	      not exist but it is emulated as being a read-only option
+	      with the value <c>true</c>.
+	    </p>
+	    <p>
+	      So it boils down to that setting this option to <c>true</c>
+	      when creating a socket will never fail except possibly
+	      (at the time of this writing) on a platform where you
+	      have customized the kernel to only allow <c>false</c>,
+	      which might be doable (but weird) on e.g. OpenBSD.
+	    </p>
+	    <p>
+	      If you read back the option value using
+	      <seealso marker="#getopts/2">getopts/2</seealso>
+	      and get no value the option does not exist in the host OS
+	      and all bets are off regarding the behaviour of both
+	      an IPv6 and an IPv4 socket listening on the same port
+	      as well as for an IPv6 socket getting IPv4 traffic.
+	    </p>
+	  </item>
+
           <tag><c>{keepalive, Boolean}</c>(TCP/IP sockets)</tag>
           <item>
             <p>Enables/disables periodic transmission on a connected
diff --git a/lib/kernel/src/gen_sctp.erl b/lib/kernel/src/gen_sctp.erl
index 8fa963ec78..74ad192802 100644
--- a/lib/kernel/src/gen_sctp.erl
+++ b/lib/kernel/src/gen_sctp.erl
@@ -44,6 +44,7 @@
         {priority, non_neg_integer()} |
         {recbuf, non_neg_integer()} |
         {reuseaddr, boolean()} |
+	{ipv6_v6only, boolean()} |
         {sctp_adaptation_layer, #sctp_setadaptation{}} |
         {sctp_associnfo, #sctp_assocparams{}} |
         {sctp_autoclose, non_neg_integer()} |
@@ -72,6 +73,7 @@
         priority |
         recbuf |
         reuseaddr |
+	ipv6_v6only |
         sctp_adaptation_layer |
         sctp_associnfo |
         sctp_autoclose |
diff --git a/lib/kernel/src/gen_tcp.erl b/lib/kernel/src/gen_tcp.erl
index e6dfdadb03..22e6aa5bc8 100644
--- a/lib/kernel/src/gen_tcp.erl
+++ b/lib/kernel/src/gen_tcp.erl
@@ -57,7 +57,8 @@
         {send_timeout,    non_neg_integer() | infinity} |
         {send_timeout_close, boolean()} |
         {sndbuf,          non_neg_integer()} |
-        {tos,             non_neg_integer()}.
+        {tos,             non_neg_integer()} |
+	{ipv6_v6only,     boolean()}.
 -type option_name() ::
         active |
         buffer |
@@ -85,7 +86,8 @@
         send_timeout |
         send_timeout_close |
         sndbuf |
-        tos.
+        tos |
+	ipv6_v6only.
 -type connect_option() ::
         {ip, inet:ip_address()} |
         {fd, Fd :: non_neg_integer()} |
diff --git a/lib/kernel/src/gen_udp.erl b/lib/kernel/src/gen_udp.erl
index 830ca61b3c..c5a1173575 100644
--- a/lib/kernel/src/gen_udp.erl
+++ b/lib/kernel/src/gen_udp.erl
@@ -47,7 +47,8 @@
         {recbuf,          non_neg_integer()} |
         {reuseaddr,       boolean()} |
         {sndbuf,          non_neg_integer()} |
-        {tos,             non_neg_integer()}.
+        {tos,             non_neg_integer()} |
+	{ipv6_v6only,     boolean()}.
 -type option_name() ::
         active |
         broadcast |
@@ -69,7 +70,8 @@
         recbuf |
         reuseaddr |
         sndbuf |
-        tos.
+        tos |
+	ipv6_v6only.
 -type socket() :: port().
 
 -export_type([option/0, option_name/0]).
diff --git a/lib/kernel/src/inet.erl b/lib/kernel/src/inet.erl
index b4ebb1500c..92c1802a86 100644
--- a/lib/kernel/src/inet.erl
+++ b/lib/kernel/src/inet.erl
@@ -531,7 +531,7 @@ getservbyname(Name, Protocol) when is_atom(Name) ->
 options() ->
     [
      tos, priority, reuseaddr, keepalive, dontroute, linger,
-     broadcast, sndbuf, recbuf, nodelay,
+     broadcast, sndbuf, recbuf, nodelay, ipv6_v6only,
      buffer, header, active, packet, deliver, mode,
      multicast_if, multicast_ttl, multicast_loop,
      exit_on_close, high_watermark, low_watermark,
@@ -607,7 +607,7 @@ con_add(Name, Val, R, Opts, AllOpts) ->
 %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
 listen_options() ->
     [tos, priority, reuseaddr, keepalive, linger, sndbuf, recbuf, nodelay,
-     header, active, packet, buffer, mode, deliver, backlog,
+     header, active, packet, buffer, mode, deliver, backlog, ipv6_v6only,
      exit_on_close, high_watermark, low_watermark, send_timeout,
      send_timeout_close, delay_send, packet_size,raw].
 
@@ -664,7 +664,7 @@ list_add(Name, Val, R, Opts, As) ->
 %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
 udp_options() ->
     [tos, priority, reuseaddr, sndbuf, recbuf, header, active, buffer, mode, 
-     deliver,
+     deliver, ipv6_v6only,
      broadcast, dontroute, multicast_if, multicast_ttl, multicast_loop,
      add_membership, drop_membership, read_packets,raw].
 
@@ -720,7 +720,7 @@ udp_add(Name, Val, R, Opts, As) ->
 sctp_options() ->
 [   % The following are generic inet options supported for SCTP sockets:
     mode, active, buffer, tos, priority, dontroute, reuseaddr, linger, sndbuf,
-    recbuf,
+    recbuf, ipv6_v6only,
 
     % Other options are SCTP-specific (though they may be similar to their
     % TCP and UDP counter-parts):
diff --git a/lib/kernel/src/inet_int.hrl b/lib/kernel/src/inet_int.hrl
index 467c4d5065..6d808b54cd 100644
--- a/lib/kernel/src/inet_int.hrl
+++ b/lib/kernel/src/inet_int.hrl
@@ -1,7 +1,7 @@
 %%
 %% %CopyrightBegin%
 %% 
-%% Copyright Ericsson AB 1997-2011. All Rights Reserved.
+%% Copyright Ericsson AB 1997-2012. All Rights Reserved.
 %% 
 %% The contents of this file are subject to the Erlang Public License,
 %% Version 1.1, (the "License"); you may not use this file except in
@@ -124,6 +124,7 @@
 -define(UDP_OPT_MULTICAST_LOOP,  13).
 -define(UDP_OPT_ADD_MEMBERSHIP,  14).
 -define(UDP_OPT_DROP_MEMBERSHIP, 15).
+-define(INET_OPT_IPV6_V6ONLY,    16).
 % "Local" options: codes start from 20:
 -define(INET_LOPT_BUFFER,        20).
 -define(INET_LOPT_HEADER,        21).
diff --git a/lib/kernel/test/inet_sockopt_SUITE.erl b/lib/kernel/test/inet_sockopt_SUITE.erl
index 087ae6055b..75496ce745 100644
--- a/lib/kernel/test/inet_sockopt_SUITE.erl
+++ b/lib/kernel/test/inet_sockopt_SUITE.erl
@@ -1,7 +1,7 @@
 %%
 %% %CopyrightBegin%
 %% 
-%% Copyright Ericsson AB 2007-2011. All Rights Reserved.
+%% Copyright Ericsson AB 2007-2012. All Rights Reserved.
 %% 
 %% The contents of this file are subject to the Erlang Public License,
 %% Version 1.1, (the "License"); you may not use this file except in
@@ -53,6 +53,8 @@
 	 simple/1, loop_all/1, simple_raw/1, simple_raw_getbin/1, 
 	 doc_examples_raw/1,doc_examples_raw_getbin/1,
 	 large_raw/1,large_raw_getbin/1,combined/1,combined_getbin/1,
+	 ipv6_v6only_udp/1, ipv6_v6only_tcp/1, ipv6_v6only_sctp/1,
+	 use_ipv6_v6only_udp/1,
 	 type_errors/1]).
 
 -export([init_per_testcase/2, end_per_testcase/2]).
@@ -64,6 +66,8 @@ all() ->
     [simple, loop_all, simple_raw, simple_raw_getbin,
      doc_examples_raw, doc_examples_raw_getbin, large_raw,
      large_raw_getbin, combined, combined_getbin,
+     ipv6_v6only_udp, ipv6_v6only_tcp, ipv6_v6only_sctp,
+     use_ipv6_v6only_udp,
      type_errors].
 
 groups() -> 
@@ -127,7 +131,7 @@ loop_all(Config) when is_list(Config) ->
 				   io_lib:format("Non mandatory failed:~w",
 						 [Failed]))}
 	  end.
-			
+
 
 
 simple_raw(suite) -> [];
@@ -461,6 +465,153 @@ do_combined(Config,Binary) when is_list(Config) ->
 	    ok
     end.
 
+
+
+ipv6_v6only_udp(suite) -> [];
+ipv6_v6only_udp(doc) -> "Test socket option ipv6_v6only for UDP";
+ipv6_v6only_udp(Config) when is_list(Config) ->
+    ipv6_v6only(Config, gen_udp).
+
+ipv6_v6only_tcp(suite) -> [];
+ipv6_v6only_tcp(doc) -> "Test socket option ipv6_v6only for TCP";
+ipv6_v6only_tcp(Config) when is_list(Config) ->
+    ipv6_v6only(Config, gen_tcp).
+
+ipv6_v6only_sctp(suite) -> [];
+ipv6_v6only_sctp(doc) -> "Test socket option ipv6_v6only for SCTP";
+ipv6_v6only_sctp(Config) when is_list(Config) ->
+    ipv6_v6only(Config, gen_sctp).
+
+ipv6_v6only(Config, Module) when is_list(Config) ->
+    ?line case ipv6_v6only_open(Module, []) of
+	      {ok,S1} ->
+		  ?line case inet:getopts(S1, [ipv6_v6only]) of
+			    {ok,[{ipv6_v6only,Default}]}
+			      when is_boolean(Default) ->
+				?line ok =
+				    ipv6_v6only_close(Module, S1),
+				?line ipv6_v6only(Config, Module, Default);
+			    {ok,[]} ->
+				?line io:format("Not implemented.~n", []),
+				%% This list of OS:es where the option is
+				%% supposed to be not implemented is just
+				%% a guess, and may grow with time.
+				?line case {os:type(),os:version()} of
+					  {{unix,linux},{2,M,_}}
+					  when M =< 4 -> ok
+				      end,
+				%% At least this should work
+				?line {ok,S2} =
+				    ipv6_v6only_open(
+				      Module,
+				      [{ipv6_v6only,true}]),
+				?line ok =
+				    ipv6_v6only_close(Module, S2)
+			end;
+	      {error,_} ->
+		  {skipped,"Socket type not supported"}
+	  end.
+
+ipv6_v6only(Config, Module, Default) when is_list(Config) ->
+    ?line io:format("Default ~w.~n", [Default]),
+    ?line {ok,S1} =
+	ipv6_v6only_open(Module, [{ipv6_v6only,Default}]),
+    ?line {ok,[{ipv6_v6only,Default}]} =
+	inet:getopts(S1, [ipv6_v6only]),
+    ?line ok =
+	ipv6_v6only_close(Module, S1),
+    ?line NotDefault = not Default,
+    ?line case ipv6_v6only_open(Module, [{ipv6_v6only,NotDefault}]) of
+	      {ok,S2} ->
+		  ?line io:format("Read-write.~n", []),
+		  ?line {ok,[{ipv6_v6only,NotDefault}]} =
+		      inet:getopts(S2, [ipv6_v6only]),
+		  ok;
+	      {error,einval} ->
+		  ?line io:format("Read-only.~n", []),
+		  %% This option is known to be read-only and true
+		  %% on Windows and OpenBSD
+		  ?line case os:type() of
+			    {unix,openbsd} when Default =:= true -> ok;
+			    {win32,_} when Default =:= true -> ok
+			end
+	  end.
+
+ipv6_v6only_open(Module, Opts) ->
+    Module:case Module of
+	       gen_tcp -> listen;
+	       _ -> open
+	   end(0, [inet6|Opts]).
+
+ipv6_v6only_close(Module, Socket) ->
+    Module:close(Socket).
+
+
+use_ipv6_v6only_udp(suite) -> [];
+use_ipv6_v6only_udp(doc) -> "Test using socket option ipv6_v6only for UDP";
+use_ipv6_v6only_udp(Config) when is_list(Config) ->
+    ?line case gen_udp:open(0, [inet6,{ipv6_v6only,true}]) of
+	      {ok,S6} ->
+		  ?line case inet:getopts(S6, [ipv6_v6only]) of
+			    {ok,[{ipv6_v6only,true}]} ->
+				use_ipv6_v6only_udp(Config, S6);
+			    {ok,Other} ->
+				{skipped,{getopts,Other}}
+			end;
+	      {error,_} ->
+		  {skipped,"Socket type not supported"}
+	  end.
+
+use_ipv6_v6only_udp(_Config, S6) ->
+    ?line {ok,Port} = inet:port(S6),
+    ?line {ok,S4} = gen_udp:open(Port, [inet]),
+    ?line E6 = " IPv6-echo.",
+    ?line E4 = " IPv4-echo.",
+    ?line Sender =
+	spawn_link(fun () -> use_ipv6_v6only_udp_sender(Port, E6, E4) end),
+    ?line use_ipv6_v6only_udp_listener(
+	    S6, S4, E6, E4, monitor(process, Sender)).
+
+use_ipv6_v6only_udp_listener(S6, S4, E6, E4, Mref) ->
+    ?line receive
+	      {udp,S6,IP,P,Data} ->
+		  ?line ok = gen_udp:send(S6, IP, P, [Data|E6]),
+		  ?line use_ipv6_v6only_udp_listener(S6, S4, E6, E4, Mref);
+	      {udp,S4,IP,P,Data} ->
+		  ?line ok = gen_udp:send(S4, IP, P, [Data|E4]),
+		  ?line use_ipv6_v6only_udp_listener(S6, S4, E6, E4, Mref);
+	      {'DOWN',Mref,_,_,normal} ->
+		  ok;
+	      {'DOWN',Mref,_,_,Result} ->
+		  %% Since we are linked we will never arrive here
+		  Result;
+	      Other ->
+		  ?line exit({failed,{listener_unexpected,Other}})
+	  end.
+
+use_ipv6_v6only_udp_sender(Port, E6, E4) ->
+    D6 = "IPv6-send.",
+    D4 = "IPv4-send.",
+    R6 = D6 ++ E6,
+    R4 = D4 ++ E4,
+    R6 = sndrcv({0,0,0,0,0,0,0,1}, Port, [inet6], D6),
+    R4 = sndrcv({127,0,0,1}, Port, [inet], D4),
+    ok.
+
+sndrcv(Ip, Port, Opts, Data) ->
+    {ok,S} = gen_udp:open(0, Opts),
+    io:format("[~w:~w] ! ~s~n", [Ip,Port,Data]),
+    ok = gen_udp:send(S, Ip, Port, Data),
+    receive
+	{udp,S,Ip,Port,RecData} ->
+	    io:format("[~w:~w] : ~s~n", [Ip,Port,RecData]),
+	    RecData;
+	Other ->
+	    exit({failed,{sndrcv_unexpectec,Other}})
+    end.
+
+
+
 type_errors(suite) ->
     [];
 type_errors(doc) ->