ejabberd_stun: Set a default 'turn_ip'

Try to resolve the local hostname, use the result as the default
'turn_ip', and only log a warning if that fails.  Using the local
hostname's address by default is analogous to mod_proxy65's behavior.

src/ejabberd_stun.erl

@@ -85,11 +85,13 @@ prepare_turn_opts(Opts, _UseTurn = false) ->
     set_certfile(Opts);
 prepare_turn_opts(Opts, _UseTurn = true) ->
     NumberOfMyHosts = length(ejabberd_option:hosts()),
-    case proplists:get_value(turn_ip, Opts) of
-	undefined ->
-	    ?WARNING_MSG("Option 'turn_ip' is undefined, "
-			 "most likely the TURN relay won't be working "
-			 "properly", []);
+    case {proplists:get_value(turn_ip, Opts),
+	  proplists:get_value(turn_ip, listen_options())} of
+	{undefined, {127, _, _, _}} ->
+	    ?WARNING_MSG("Option 'turn_ip' is undefined and the server's "
+			 "hostname doesn't resolve to a public IPv4 address, "
+			 "most likely the TURN relay won't be working properly",
+			 []);
 	_ ->
 	    ok
     end,
@@ -158,7 +160,7 @@ listen_opt_type(certfile) ->
 listen_options() ->
     [{shaper, none},
      {use_turn, false},
-     {turn_ip, undefined},
+     {turn_ip, misc:get_my_ip()},
      {auth_type, user},
      {auth_realm, undefined},
      {tls, false},

src/misc.erl

@@ -40,8 +40,8 @@
 	 read_css/1, read_img/1, read_js/1, read_lua/1, try_url/1,
 	 intersection/2, format_val/1, cancel_timer/1, unique_timestamp/0,
 	 is_mucsub_message/1, best_match/2, pmap/2, peach/2, format_exception/4,
-	 parse_ip_mask/1, match_ip_mask/3, format_hosts_list/1, format_cycle/1,
-	 delete_dir/1]).
+	 get_my_ip/0, parse_ip_mask/1, match_ip_mask/3, format_hosts_list/1,
+	 format_cycle/1, delete_dir/1]).
 
 %% Deprecated functions
 -export([decode_base64/1, encode_base64/1]).
@@ -509,6 +509,14 @@ format_exception(Level, Class, Reason, Stacktrace) ->
       end).
 -endif.
 
+-spec get_my_ip() -> inet:ip_address().
+get_my_ip() ->
+    {ok, MyHostName} = inet:gethostname(),
+    case inet:getaddr(MyHostName, inet) of
+	{ok, Addr} -> Addr;
+	{error, _} -> {127, 0, 0, 1}
+    end.
+
 -spec parse_ip_mask(binary()) -> {ok, {inet:ip4_address(), 0..32}} |
 				 {ok, {inet:ip6_address(), 0..128}} |
 				 error.

src/mod_proxy65_service.erl

@@ -266,19 +266,11 @@ get_streamhost(Host, ServerHost) ->
 get_endpoint(Host) ->
     Port = mod_proxy65_opt:port(Host),
     IP = case mod_proxy65_opt:ip(Host) of
-	     undefined -> get_my_ip();
+	     undefined -> misc:get_my_ip();
 	     Addr -> Addr
 	 end,
     {Port, IP, tcp}.
 
--spec get_my_ip() -> inet:ip_address().
-get_my_ip() ->
-    {ok, MyHostName} = inet:gethostname(),
-    case inet:getaddr(MyHostName, inet) of
-      {ok, Addr} -> Addr;
-      {error, _} -> {127, 0, 0, 1}
-    end.
-
 max_connections(ServerHost) ->
     mod_proxy65_opt:max_connections(ServerHost).