Merge branch 'tab/fix-sctp-multihoming-IPv6/OTP-10217' into maint

* tab/fix-sctp-multihoming-IPv6/OTP-10217:
  Allow mixed IPv4 and IPv6 addresses to sctp_bindx
  Add checks for in6addr_any and in6addr_loopback
  Fix SCTP multihoming
  inet_drv.c: Set sockaddr lengths in inet_set_[f]address

6 files changed, 343 insertions, 34 deletions

diff --git a/erts/configure.in b/erts/configure.in
index e576bd7755..281f61f86e 100644
--- a/erts/configure.in
+++ b/erts/configure.in
@@ -1944,6 +1944,64 @@ AC_CHECK_FUNCS([openpty])
 AC_CHECK_HEADERS(net/if_dl.h ifaddrs.h netpacket/packet.h)
 AC_CHECK_FUNCS([getifaddrs])
 
+dnl Checks for variables in6addr_any and in6addr_loopback,
+dnl
+dnl They normally declared by netinet/in.h, according to POSIX,
+dnl but not on Windows 7 (Windows SDK 7.1).  I would have liked
+dnl to just write AC_CHECK_DECL([in6addr_any], ...) but if doing so,
+dnl the configure check fails erroneously on Linux with the error
+dnl "cannot convert to a pointer type", on a line looking like
+dnl "char *p = (char *) in6addr_any;", so work around that
+dnl with some more code. 
+AC_CACHE_CHECK(
+    [whether in6addr_any is declared],
+    [erts_cv_have_in6addr_any],
+    [AC_LINK_IFELSE(
+	[AC_LANG_PROGRAM(
+	    [[
+		#include <sys/types.h>
+		#include <sys/socket.h>
+		#include <netinet/in.h>
+	    ]],
+	    [[printf("%d", in6addr_any.s6_addr[16]);]]
+	)],
+	[erts_cv_have_in6addr_any=yes],
+	[erts_cv_have_in6addr_any=no]
+    )]
+)
+
+case "$erts_cv_have_in6addr_any" in
+ yes)
+   AC_DEFINE([HAVE_IN6ADDR_ANY], [1],
+             [Define to 1 if you have the variable in6addr_any declared.])
+esac
+
+AC_CACHE_CHECK(
+    [whether in6addr_loopback is declared],
+    [erts_cv_have_in6addr_loopback],
+    [AC_LINK_IFELSE(
+	[AC_LANG_PROGRAM(
+	    [[
+		#include <sys/types.h>
+		#include <sys/socket.h>
+		#include <netinet/in.h>
+	    ]],
+	    [[printf("%d", in6addr_loopback.s6_addr[16]);]]
+	)],
+	[erts_cv_have_in6addr_loopback=yes],
+	[erts_cv_have_in6addr_loopback=no]
+    )]
+)
+
+case "$erts_cv_have_in6addr_loopback" in
+ yes)
+   AC_DEFINE([HAVE_IN6ADDR_LOOPBACK], [1],
+             [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>])
+
 dnl ----------------------------------------------------------------------
 dnl Checks for features/quirks in the system that affects Erlang.
 dnl ----------------------------------------------------------------------
diff --git a/erts/emulator/drivers/common/inet_drv.c b/erts/emulator/drivers/common/inet_drv.c
index 76a9b55179..8f4fff0f40 100644
--- a/erts/emulator/drivers/common/inet_drv.c
+++ b/erts/emulator/drivers/common/inet_drv.c
@@ -1228,6 +1228,27 @@ struct erl_drv_entry inet_driver_entry =
     NULL,
 };
 
+#if HAVE_IN6
+#  if ! defined(HAVE_IN6ADDR_ANY) || ! HAVE_IN6ADDR_ANY
+#    if HAVE_DECL_IN6ADDR_ANY_INIT
+static const struct in6_addr in6addr_any = { { IN6ADDR_ANY_INIT } };
+#    else
+static const struct in6_addr in6addr_any =
+    { { { 0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0 } } };
+#    endif /* HAVE_IN6ADDR_ANY_INIT */
+#  endif /* ! HAVE_DECL_IN6ADDR_ANY */
+
+#  if ! defined(HAVE_IN6ADDR_LOOPBACK) || ! HAVE_IN6ADDR_LOOPBACK
+#    if HAVE_DECL_IN6ADDR_LOOPBACK_INIT
+static const struct in6_addr in6addr_loopback =
+    { { IN6ADDR_LOOPBACK_INIT } };
+#    else
+static const struct in6_addr in6addr_loopback =
+    { { { 0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,1 } } };
+#    endif /* HAVE_IN6ADDR_LOOPBACk_INIT */
+#  endif /* ! HAVE_DECL_IN6ADDR_LOOPBACK */
+#endif /* HAVE_IN6 */
+
 /* XXX: is this a driver interface function ??? */
 void erl_exit(int n, char*, ...);
 
@@ -3706,6 +3727,9 @@ static char* inet_set_address(int family, inet_address* dst,
     if ((family == AF_INET) && (*len >= 2+4)) {
 	sys_memzero((char*)dst, sizeof(struct sockaddr_in));
 	port = get_int16(src);
+#ifndef NO_SA_LEN
+	dst->sai.sin_len    = sizeof(struct sockaddr_in);
+#endif
 	dst->sai.sin_family = family;
 	dst->sai.sin_port   = sock_htons(port);
 	sys_memcpy(&dst->sai.sin_addr, src+2, 4);
@@ -3716,6 +3740,9 @@ static char* inet_set_address(int family, inet_address* dst,
     else if ((family == AF_INET6) && (*len >= 2+16)) {
 	sys_memzero((char*)dst, sizeof(struct sockaddr_in6));
 	port = get_int16(src);
+#ifndef NO_SA_LEN
+	dst->sai6.sin6_len    = sizeof(struct sockaddr_in6);
+#endif
 	dst->sai6.sin6_family = family;
 	dst->sai6.sin6_port   = sock_htons(port);
 	dst->sai6.sin6_flowinfo = 0;   /* XXX this may be set as well ?? */
@@ -3726,7 +3753,7 @@ static char* inet_set_address(int family, inet_address* dst,
 #endif
     return NULL;
 }
-#ifdef HAVE_SCTP
+
 /*
 ** Set an inaddr structure, address family comes from source data,
 ** or from argument if source data specifies constant address.
@@ -3770,6 +3797,9 @@ static char *inet_set_faddress(int family, inet_address* dst,
 		return NULL;
 	    }
 	    sys_memzero((char*)dst, sizeof(struct sockaddr_in));
+#ifndef NO_SA_LEN
+	    dst->sai.sin_len         = sizeof(struct sockaddr_in6);
+#endif
 	    dst->sai.sin_family      = family;
 	    dst->sai.sin_port        = sock_htons(port);
 	    dst->sai.sin_addr.s_addr = addr.s_addr;
@@ -3789,6 +3819,9 @@ static char *inet_set_faddress(int family, inet_address* dst,
 		return NULL;
 	    }
 	    sys_memzero((char*)dst, sizeof(struct sockaddr_in6));
+#ifndef NO_SA_LEN
+	    dst->sai6.sin6_len    = sizeof(struct sockaddr_in6);
+#endif
 	    dst->sai6.sin6_family = family;
 	    dst->sai6.sin6_port   = sock_htons(port);
 	    dst->sai6.sin6_flowinfo = 0;   /* XXX this may be set as well ?? */
@@ -3806,7 +3839,7 @@ static char *inet_set_faddress(int family, inet_address* dst,
     }
     return inet_set_address(family, dst, src, len);
 }
-#endif /* HAVE_SCTP */
+
 
 /* Get a inaddr structure
 ** src = inaddr structure
@@ -7771,7 +7804,7 @@ static ErlDrvSSizeT inet_ctl(inet_descriptor* desc, int cmd, char* buf,
 	if (desc->state != INET_STATE_OPEN)
 	    return ctl_xerror(EXBADPORT, rbuf, rsize);
 
-	if (inet_set_address(desc->sfamily, &local, buf, &len) == NULL)
+	if (inet_set_faddress(desc->sfamily, &local, buf, &len) == NULL)
 	    return ctl_error(EINVAL, rbuf, rsize);
 
 	if (IS_SOCKET_ERROR(sock_bind(desc->s,(struct sockaddr*) &local, len)))
@@ -10136,12 +10169,13 @@ static ErlDrvSSizeT packet_inet_ctl(ErlDrvData e, unsigned int cmd, char* buf,
 
     case SCTP_REQ_BINDX:
 	{   /* Multi-homing bind for SCTP: */
-	    /* Construct the list of addresses we bind to. The curr limit is
-	       256 addrs. Buff structure: Flags(1), ListItem,...:
+	    /* Add additional addresses by calling sctp_bindx with one address
+	       at a time, since this is what some OSes promise will work.
+	       Buff structure: Flags(1), ListItem,...:
 	    */
-	    struct sockaddr addrs[256];
+	    inet_address addr;
 	    char* curr;
-	    int   add_flag, n, rflag;
+	    int   add_flag, rflag;
 	    
 	    if (!IS_SCTP(desc))
 		return ctl_xerror(EXBADPORT, rbuf, rsize);
@@ -10150,27 +10184,22 @@ static ErlDrvSSizeT packet_inet_ctl(ErlDrvData e, unsigned int cmd, char* buf,
 	    add_flag = get_int8(curr);
 	    curr++;
 
-	    for(n=0; n < 256 && curr < buf+len; n++)
+	    /* Make the real flags: */
+	    rflag = add_flag ? SCTP_BINDX_ADD_ADDR : SCTP_BINDX_REM_ADDR;
+
+	    while (curr < buf+len)
 		{
-		    /* List item format: Port(2), IP(4|16) -- compatible with
-		       "inet_set_address": */
-		    inet_address tmp;
+		    /* List item format: see "inet_set_faddress": */
 		    ErlDrvSizeT alen  = buf + len - curr;
-		    curr = inet_set_address(desc->sfamily, &tmp, curr, &alen);
+		    curr = inet_set_faddress(desc->sfamily, &addr, curr, &alen);
 		    if (curr == NULL)
 			return ctl_error(EINVAL, rbuf, rsize);
 
-		    /* Now: we need to squeeze "tmp" into the size of "sockaddr",
-		       which is smaller than "tmp" for IPv6 (extra IN6 info will
-		       be cut off): */
-		    memcpy(addrs + n, &tmp, sizeof(struct sockaddr));
+		    /* Invoke the call: */
+		    if (p_sctp_bindx(desc->s, (struct sockaddr *)&addr, 1,
+				     rflag) < 0)
+			return ctl_error(sock_errno(), rbuf, rsize);
 		}
-	    /* Make the real flags: */
-	    rflag = add_flag ? SCTP_BINDX_ADD_ADDR : SCTP_BINDX_REM_ADDR;
-
-	    /* Invoke the call: */
-	    if (p_sctp_bindx(desc->s, addrs, n, rflag) < 0)
-		return ctl_error(sock_errno(), rbuf, rsize);
 
 	    desc->state = INET_STATE_BOUND;
 
diff --git a/erts/preloaded/ebin/prim_inet.beam b/erts/preloaded/ebin/prim_inet.beam
index b2f3ab6c5b..ad49f5e892 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 846ae97ed2..91fcd3ac82 100644
--- a/erts/preloaded/src/prim_inet.erl
+++ b/erts/preloaded/src/prim_inet.erl
@@ -184,7 +184,7 @@ close_pend_loop(S, N) ->
 %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
 
 bind(S,IP,Port) when is_port(S), is_integer(Port), Port >= 0, Port =< 65535 ->
-    case ctl_cmd(S,?INET_REQ_BIND,[?int16(Port),ip_to_bytes(IP)]) of
+    case ctl_cmd(S,?INET_REQ_BIND,enc_value(set, addr, {IP,Port})) of
 	{ok, [P1,P0]} -> {ok, ?u16(P1, P0)};
 	{error,_}=Error -> Error
     end;
@@ -206,10 +206,10 @@ bindx(S, AddFlag, Addrs) ->
     case getprotocol(S) of
 	sctp ->
 	    %% Really multi-homed "bindx". Stringified args:
-	    %% [AddFlag, (Port, IP)+]:
+	    %% [AddFlag, (AddrBytes see enc_value_2(addr,X))+]:
 	    Args =
 		[?int8(AddFlag)|
-		 [[?int16(Port)|ip_to_bytes(IP)] ||
+		 [enc_value(set, addr, {IP,Port}) ||
 		     {IP, Port} <- Addrs]],
 	    case ctl_cmd(S, ?SCTP_REQ_BINDX, Args) of
 		{ok,_} -> {ok, S};
diff --git a/lib/kernel/src/inet.erl b/lib/kernel/src/inet.erl
index 0bb5444dbb..1a03424f88 100644
--- a/lib/kernel/src/inet.erl
+++ b/lib/kernel/src/inet.erl
@@ -763,8 +763,12 @@ sctp_opt([Opt|Opts], Mod, R, As) ->
 	{Name,Val}	-> sctp_opt (Opts, Mod, R, As, Name, Val);
 	_ -> {error,badarg}
     end;
-sctp_opt([], _Mod, R, _SockOpts) ->
-    {ok, R}.
+sctp_opt([], _Mod, #sctp_opts{ifaddr=IfAddr}=R, _SockOpts) ->
+    if is_list(IfAddr) ->
+	    {ok, R#sctp_opts{ifaddr=lists:reverse(IfAddr)}};
+       true ->
+	    {ok, R}
+    end.
 
 sctp_opt(Opts, Mod, R, As, Name, Val) ->
     case add_opt(Name, Val, R#sctp_opts.opts, As) of
@@ -1015,11 +1019,7 @@ open(Fd, Addr, Port, Opts, Protocol, Family, Type, Module) when Fd < 0 ->
 	    case prim_inet:setopts(S, Opts) of
 		ok ->
 		    case if is_list(Addr) ->
-				 prim_inet:bind(S, add,
-						[case A of
-						     {_,_} -> A;
-						     _     -> {A,Port}
-						 end || A <- Addr]);
+				 bindx(S, Addr, Port);
 			    true ->
 				 prim_inet:bind(S, Addr, Port)
 			 end of
@@ -1040,6 +1040,34 @@ open(Fd, Addr, Port, Opts, Protocol, Family, Type, Module) when Fd < 0 ->
 open(Fd, _Addr, _Port, Opts, Protocol, Family, Type, Module) ->
     fdopen(Fd, Opts, Protocol, Family, Type, Module).
 
+bindx(S, [Addr], Port0) ->
+    {IP, Port} = set_bindx_port(Addr, Port0),
+    prim_inet:bind(S, IP, Port);
+bindx(S, Addrs, Port0) ->
+    [{IP, Port} | Rest] = [set_bindx_port(Addr, Port0) || Addr <- Addrs],
+    case prim_inet:bind(S, IP, Port) of
+	{ok, AssignedPort} when Port =:= 0 ->
+	    %% On newer Linux kernels, Solaris and FreeBSD, calling
+	    %% bindx with port 0 is ok, but on SuSE 10, it results in einval
+	    Rest2 = [change_bindx_0_port(Addr, AssignedPort) || Addr <- Rest],
+	    prim_inet:bind(S, add, Rest2);
+	{ok, _} ->
+	    prim_inet:bind(S, add, Rest);
+	Error ->
+	    Error
+    end.
+
+set_bindx_port({_IP, _Port}=Addr, _OtherPort) ->
+    Addr;
+set_bindx_port(IP, Port) ->
+    {IP, Port}.
+
+change_bindx_0_port({IP, 0}, AssignedPort) ->
+    {IP, AssignedPort};
+change_bindx_0_port({_IP, _Port}=Addr, _AssignedPort) ->
+    Addr.
+
+
 -spec fdopen(Fd :: non_neg_integer(),
 	     Opts :: [socket_setopt()],
 	     Protocol :: socket_protocol(),
diff --git a/lib/kernel/test/gen_sctp_SUITE.erl b/lib/kernel/test/gen_sctp_SUITE.erl
index 8f490b6643..f4bf6e719e 100644
--- a/lib/kernel/test/gen_sctp_SUITE.erl
+++ b/lib/kernel/test/gen_sctp_SUITE.erl
@@ -31,14 +31,22 @@
    [basic/1,
     api_open_close/1,api_listen/1,api_connect_init/1,api_opts/1,
     xfer_min/1,xfer_active/1,def_sndrcvinfo/1,implicit_inet6/1,
-    basic_stream/1, xfer_stream_min/1, peeloff/1, buffers/1]).
+    basic_stream/1, xfer_stream_min/1, peeloff/1, buffers/1,
+    open_multihoming_ipv4_socket/1,
+    open_unihoming_ipv6_socket/1,
+    open_multihoming_ipv6_socket/1,
+    open_multihoming_ipv4_and_ipv6_socket/1]).
 
 suite() -> [{ct_hooks,[ts_install_cth]}].
 
 all() -> 
     [basic, api_open_close, api_listen, api_connect_init,
      api_opts, xfer_min, xfer_active, def_sndrcvinfo, implicit_inet6,
-     basic_stream, xfer_stream_min, peeloff, buffers].
+     basic_stream, xfer_stream_min, peeloff, buffers,
+     open_multihoming_ipv4_socket,
+     open_unihoming_ipv6_socket,
+     open_multihoming_ipv6_socket,
+     open_multihoming_ipv4_and_ipv6_socket].
 
 groups() -> 
     [].
@@ -1105,6 +1113,192 @@ mk_data(N, Bytes, Bin) when N < Bytes ->
 mk_data(_, _, Bin) ->
     Bin.
 
+
+
+open_multihoming_ipv4_socket(doc) ->
+    "Test opening a multihoming ipv4 socket";
+open_multihoming_ipv4_socket(suite) ->
+    [];
+open_multihoming_ipv4_socket(Config) when is_list(Config) ->
+    ?line case get_addrs_by_family(inet, 2) of
+	      {ok, [Addr1, Addr2]} ->
+		  ?line do_open_and_connect([Addr1, Addr2], Addr1);
+	      {error, Reason} ->
+		  {skip, Reason}
+	  end.
+
+open_unihoming_ipv6_socket(doc) ->
+    %% This test is mostly aimed to indicate
+    %% whether host has a non-working ipv6 setup
+    "Test opening a unihoming (non-multihoming) ipv6 socket";
+open_unihoming_ipv6_socket(suite) ->
+    [];
+open_unihoming_ipv6_socket(Config) when is_list(Config) ->
+    ?line case get_addrs_by_family(inet6, 1) of
+	      {ok, [Addr]} ->
+		  ?line do_open_and_connect([Addr], Addr);
+	      {error, Reason} ->
+		  {skip, Reason}
+	  end.
+
+
+open_multihoming_ipv6_socket(doc) ->
+    "Test opening a multihoming ipv6 socket";
+open_multihoming_ipv6_socket(suite) ->
+    [];
+open_multihoming_ipv6_socket(Config) when is_list(Config) ->
+    ?line case get_addrs_by_family(inet6, 2) of
+	      {ok, [Addr1, Addr2]} ->
+		  ?line do_open_and_connect([Addr1, Addr2], Addr1);
+	      {error, Reason} ->
+		  {skip, Reason}
+	  end.
+
+open_multihoming_ipv4_and_ipv6_socket(doc) ->
+    "Test opening a multihoming ipv6 socket with ipv4 and ipv6 addresses";
+open_multihoming_ipv4_and_ipv6_socket(suite) ->
+    [];
+open_multihoming_ipv4_and_ipv6_socket(Config) when is_list(Config) ->
+    ?line case get_addrs_by_family(inet_and_inet6, 2) of
+	      {ok, [[InetAddr1, InetAddr2], [Inet6Addr1, Inet6Addr2]]} ->
+		  %% Connect to the first address to test bind
+		  ?line do_open_and_connect([InetAddr1, Inet6Addr1, InetAddr2],
+					    InetAddr1),
+		  ?line do_open_and_connect([Inet6Addr1, InetAddr1],
+					    Inet6Addr1),
+
+		  %% Connect an address, not the first,
+		  %% to test sctp_bindx
+		  ?line do_open_and_connect([Inet6Addr1, Inet6Addr2, InetAddr1],
+					    Inet6Addr2),
+		  ?line do_open_and_connect([Inet6Addr1, Inet6Addr2, InetAddr1],
+					    InetAddr1);
+	      {error, Reason} ->
+		  {skip, Reason}
+	  end.
+
+
+get_addrs_by_family(Family, NumAddrs) ->
+    case os:type() of
+	{unix,linux} ->
+	    get_addrs_by_family_aux(Family, NumAddrs);
+	{unix,freebsd} ->
+	    get_addrs_by_family_aux(Family, NumAddrs);
+	{unix,sunos} ->
+	    case get_addrs_by_family_aux(Family, NumAddrs) of
+		{ok, [InetAddrs, Inet6Addrs]} when Family =:= inet_and_inet6 ->
+		    %% Man page for sctp_bindx on Solaris says: "If sock is an
+		    %% Internet Protocol Version 6 (IPv6) socket, addrs should
+		    %% be an array of sockaddr_in6 structures containing IPv6
+		    %% or IPv4-mapped IPv6 addresses."
+		    {ok, [ipv4_map_addrs(InetAddrs), Inet6Addrs]};
+		{ok, Addrs} ->
+		    {ok, Addrs};
+		{error, Reason} ->
+		    {error, Reason}
+	    end;
+	Os ->
+	    Reason = if Family =:= inet_and_inet6 ->
+			     f("Mixing ipv4 and ipv6 addresses for multihoming "
+			       " has not been verified on ~p", [Os]);
+			true ->
+			     f("Multihoming for ~p has not been verified on ~p",
+			       [Family, Os])
+		     end,
+	    {error, Reason}
+    end.
+
+get_addrs_by_family_aux(Family, NumAddrs) when Family =:= inet;
+					       Family =:= inet6 ->
+    ?line
+	case inet:getaddr(localhost, Family) of
+	    {error,eafnosupport} ->
+		{skip, f("No support for ~p", Family)};
+	    {ok, _} ->
+		?line IfAddrs = ok(inet:getifaddrs()),
+		?line case filter_addrs_by_family(IfAddrs, Family) of
+			  Addrs when length(Addrs) >= NumAddrs ->
+			      {ok, lists:sublist(Addrs, NumAddrs)};
+			  [] ->
+			      {error, f("Need ~p ~p address(es) found none~n",
+					[NumAddrs, Family])};
+			  Addrs ->
+			      {error,
+			       f("Need ~p ~p address(es) found only ~p: ~p~n",
+				 [NumAddrs, Family, length(Addrs), Addrs])}
+		      end
+	end;
+get_addrs_by_family_aux(inet_and_inet6, NumAddrs) ->
+    ?line catch {ok, [case get_addrs_by_family_aux(Family, NumAddrs) of
+			  {ok, Addrs}     -> Addrs;
+			  {error, Reason} -> throw({error, Reason})
+		      end || Family <- [inet, inet6]]}.
+
+filter_addrs_by_family(IfAddrs, Family) ->
+    lists:flatten([[Addr || {addr, Addr} <- Info,
+			    is_good_addr(Addr, Family)]
+		   || {_IfName, Info} <- IfAddrs]).
+
+is_good_addr(Addr, inet) when tuple_size(Addr) =:= 4 ->
+    true;
+is_good_addr({0,0,0,0,0,16#ffff,_,_}, inet6) ->
+    false; %% ipv4 mapped
+is_good_addr({16#fe80,_,_,_,_,_,_,_}, inet6) ->
+    false; %% link-local
+is_good_addr(Addr, inet6) when tuple_size(Addr) =:= 8 ->
+    true;
+is_good_addr(_Addr, _Family) ->
+    false.
+
+ipv4_map_addrs(InetAddrs) ->
+    [begin
+	 <<AB:16>> = <<A,B>>,
+	 <<CD:16>> = <<C,D>>,
+	 {0, 0, 0, 0, 0, 16#ffff, AB, CD}
+     end || {A,B,C,D} <- InetAddrs].
+
+f(F, A) ->
+    lists:flatten(io_lib:format(F, A)).
+
+do_open_and_connect(ServerAddresses, AddressToConnectTo) ->
+    ?line ServerFamily = get_family_by_addrs(ServerAddresses),
+    ?line io:format("Serving ~p addresses: ~p~n",
+		    [ServerFamily, ServerAddresses]),
+    ?line S1 = ok(gen_sctp:open(0, [{ip,Addr} || Addr <- ServerAddresses] ++
+				    [ServerFamily])),
+    ?line ok = gen_sctp:listen(S1, true),
+    ?line P1 = ok(inet:port(S1)),
+    ?line ClientFamily = get_family_by_addr(AddressToConnectTo),
+    ?line io:format("Connecting to ~p ~p~n",
+		    [ClientFamily, AddressToConnectTo]),
+    ?line S2 = ok(gen_sctp:open(0, [ClientFamily])),
+    %% Verify client can connect
+    ?line #sctp_assoc_change{state=comm_up} =
+	ok(gen_sctp:connect(S2, AddressToConnectTo, P1, [])),
+    %% verify server side also receives comm_up from client
+    ?line recv_comm_up_eventually(S1),
+    ?line ok = gen_sctp:close(S2),
+    ?line ok = gen_sctp:close(S1).
+
+%% If at least one of the addresses is an ipv6 address, return inet6, else inet.
+get_family_by_addrs(Addresses) ->
+    ?line case lists:usort([get_family_by_addr(Addr) || Addr <- Addresses]) of
+	      [inet, inet6] -> inet6;
+	      [inet]        -> inet;
+	      [inet6]       -> inet6
+	  end.
+
+get_family_by_addr(Addr) when tuple_size(Addr) =:= 4 -> inet;
+get_family_by_addr(Addr) when tuple_size(Addr) =:= 8 -> inet6.
+
+recv_comm_up_eventually(S) ->
+    ?line case ok(gen_sctp:recv(S)) of
+	      {_Addr, _Port, _Info, #sctp_assoc_change{state=comm_up}} ->
+		  ok;
+	      {_Addr, _Port, _Info, _OtherSctpMsg} ->
+		  ?line recv_comm_up_eventually(S)
+	  end.
+
 %%% %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
 %%% socket gen_server ultra light