Let an 8-tuple given as ip_address() for gen_tcp/gen_udp/gen_sctp imply 'inet6'

Currently an 8-tuple representing an IPv6 address is not accepted by
gen_tcp:listen/2, gen_tcp:connect/3,4, gen_udp:open/2, or
gen_sctp:open/1,2, unless the 'inet6' option is also given. This means
that an application that has obtained the address, e.g. from
configuration that allows for either IPv4 or IPv6, must always check the
type of the address before passing it to these functions. Letting the
functions infer 'inet6' from the 8-tuple, in case other options do not
override this choice, improves usability.

1 files changed, 23 insertions, 13 deletions

diff --git a/lib/kernel/src/gen_tcp.erl b/lib/kernel/src/gen_tcp.erl
index 7401b06a64..16a87d71b6 100644
--- a/lib/kernel/src/gen_tcp.erl
+++ b/lib/kernel/src/gen_tcp.erl
@@ -1,7 +1,7 @@
 %%
 %% %CopyrightBegin%
 %% 
-%% Copyright Ericsson AB 1997-2009. All Rights Reserved.
+%% Copyright Ericsson AB 1997-2010. 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
@@ -46,7 +46,7 @@ connect(Address, Port, Opts, Time) ->
     end.
 
 connect1(Address,Port,Opts,Timer) ->
-    Mod = mod(Opts),
+    Mod = mod(Opts, Address),
     case Mod:getaddrs(Address,Timer) of
 	{ok,IPs} ->
 	    case Mod:getserv(Port) of
@@ -73,7 +73,7 @@ try_connect([], _Port, _Opts, _Timer, _Mod, Err) ->
 %% Listen on a tcp port
 %%
 listen(Port, Opts) ->
-    Mod = mod(Opts),
+    Mod = mod(Opts, undefined),
     case Mod:getserv(Port) of
 	{ok,TP} ->
 	    Mod:listen(TP, Opts);
@@ -173,20 +173,30 @@ controlling_process(S, NewOwner) ->
 %% Create a port/socket from a file descriptor 
 %%
 fdopen(Fd, Opts) ->
-    Mod = mod(Opts),
+    Mod = mod(Opts, undefined),
     Mod:fdopen(Fd, Opts).
 
-%% Get the tcp_module
-mod() -> inet_db:tcp_module().
+%% Get the tcp_module, but IPv6 address overrides default IPv4
+mod(Address) ->
+    case inet_db:tcp_module() of
+	inet_tcp when tuple_size(Address) =:= 8 ->
+	    inet6_tcp;
+	Mod ->
+	    Mod
+    end.
 
 %% Get the tcp_module, but option tcp_module|inet|inet6 overrides
-mod([{tcp_module,Mod}|_]) ->
+mod([{tcp_module,Mod}|_], _Address) ->
     Mod;
-mod([inet|_]) ->
+mod([inet|_], _Address) ->
     inet_tcp;
-mod([inet6|_]) ->
+mod([inet6|_], _Address) ->
     inet6_tcp;
-mod([_|Opts]) ->
-    mod(Opts);
-mod([]) ->
-    mod().
+mod([{ip, Address}|Opts], _) ->
+    mod(Opts, Address);
+mod([{ifaddr, Address}|Opts], _) ->
+    mod(Opts, Address);
+mod([_|Opts], Address) ->
+    mod(Opts, Address);
+mod([], Address) ->
+    mod(Address).