Deprecate 'route_subdomains' option

This option was introduced to fulfill requirement of RFC3920 10.3,
but in practice it was very inconvenient and many admins were
forced to change its value to 's2s' (i.e. to behaviour that
violates the RFC). Also, it seems like in RFC6120 this requirement
no longer presents.

Those admins who used this option to block s2s with their subdomains
can use 's2s_access' option for the same purpose.

src/ejabberd_config_transformer.erl

@@ -197,6 +197,9 @@ filter(_Host, Opt, Val, _) when Opt == outgoing_s2s_timeout;
 filter(_Host, captcha_host, _, _) ->
     warn_deprecated_option(captcha_host, captcha_url),
     true;
+filter(_Host, route_subdomains, _, _) ->
+    warn_removed_option(route_subdomains, s2s_access),
+    false;
 filter(Host, modules, ModOpts, State) ->
     NoDialbackHosts = maps:get(remove_s2s_dialback, State, []),
     ModOpts1 = lists:filter(

src/ejabberd_option.erl

@@ -111,7 +111,6 @@
 -export([riak_server/0]).
 -export([riak_start_interval/0]).
 -export([riak_username/0]).
--export([route_subdomains/0, route_subdomains/1]).
 -export([router_cache_life_time/0]).
 -export([router_cache_missed/0]).
 -export([router_cache_size/0]).
@@ -756,13 +755,6 @@ riak_start_interval() ->
 riak_username() ->
     ejabberd_config:get_option({riak_username, global}).
 
--spec route_subdomains() -> 'local' | 's2s'.
-route_subdomains() ->
-    route_subdomains(global).
--spec route_subdomains(global | binary()) -> 'local' | 's2s'.
-route_subdomains(Host) ->
-    ejabberd_config:get_option({route_subdomains, Host}).
-
 -spec router_cache_life_time() -> 'infinity' | pos_integer().
 router_cache_life_time() ->
     ejabberd_config:get_option({router_cache_life_time, global}).

src/ejabberd_options.erl

@@ -294,8 +294,6 @@ opt_type(riak_start_interval) ->
     econf:timeout(second);
 opt_type(riak_username) ->
     econf:string();
-opt_type(route_subdomains) ->
-    econf:enum([s2s, local]);
 opt_type(router_cache_life_time) ->
     econf:timeout(second, infinity);
 opt_type(router_cache_missed) ->
@@ -568,7 +566,6 @@ options() ->
      {riak_server, "127.0.0.1"},
      {riak_start_interval, timer:seconds(30)},
      {riak_username, nil},
-     {route_subdomains, local},
      {router_cache_life_time,
       fun(Host) -> ejabberd_config:get_option({cache_life_time, Host}) end},
      {router_cache_missed,

src/ejabberd_s2s.erl

@@ -361,10 +361,6 @@ do_route(Packet) ->
 	{error, Reason} ->
 	  Lang = xmpp:get_lang(Packet),
 	    Err = case Reason of
-		      policy_violation ->
-			  xmpp:err_policy_violation(
-			    ?T("Server connections to local "
-			       "subdomains are forbidden"), Lang);
 		      forbidden ->
 			  xmpp:err_forbidden(?T("Access denied by service policy"), Lang);
 		      internal_server_error ->
@@ -374,12 +370,12 @@ do_route(Packet) ->
     end.
 
 -spec start_connection(jid(), jid())
-      -> {ok, pid()} | {error, policy_violation | forbidden | internal_server_error}.
+      -> {ok, pid()} | {error, forbidden | internal_server_error}.
 start_connection(From, To) ->
     start_connection(From, To, []).
 
 -spec start_connection(jid(), jid(), [proplists:property()])
-      -> {ok, pid()} | {error, policy_violation | forbidden | internal_server_error}.
+      -> {ok, pid()} | {error, forbidden | internal_server_error}.
 start_connection(From, To, Opts) ->
     #jid{lserver = MyServer} = From,
     #jid{lserver = Server} = To,
@@ -395,10 +391,6 @@ start_connection(From, To, Opts) ->
 	  %% service and if the s2s host is not blacklisted or
 	  %% is in whitelist:
 	  LServer = ejabberd_router:host_of_route(MyServer),
-	  case is_service(From, To) of
-	    true ->
-		  {error, policy_violation};
-	      false ->
 	    case allow_host(LServer, Server) of
 		true ->
 		    NeededConnections = needed_connections_number(
@@ -411,7 +403,6 @@ start_connection(From, To, Opts) ->
 					     MaxS2SConnectionsNumberPerNode, Opts);
 		false ->
 		    {error, forbidden}
-		  end
 	    end;
       L when is_list(L) ->
 	  NeededConnections = needed_connections_number(L,
@@ -512,32 +503,6 @@ needed_connections_number(Ls, MaxS2SConnectionsNumber,
     lists:min([MaxS2SConnectionsNumber - length(Ls),
 	       MaxS2SConnectionsNumberPerNode - length(LocalLs)]).
 
-%%--------------------------------------------------------------------
-%% Function: is_service(From, To) -> true | false
-%% Description: Return true if the destination must be considered as a
-%% service.
-%% --------------------------------------------------------------------
--spec is_service(jid(), jid()) -> boolean().
-is_service(From, To) ->
-    LFromDomain = From#jid.lserver,
-    case ejabberd_option:route_subdomains(LFromDomain) of
-      s2s -> % bypass RFC 3920 10.3
-	  false;
-      local ->
-	  Hosts = ejabberd_option:hosts(),
-	  P = fun (ParentDomain) ->
-		      lists:member(ParentDomain, Hosts)
-	      end,
-	  lists:any(P, parent_domains(To#jid.lserver))
-    end.
-
-parent_domains(Domain) ->
-    lists:foldl(fun (Label, []) -> [Label];
-		    (Label, [Head | Tail]) ->
-			[<<Label/binary, ".", Head/binary>>, Head | Tail]
-		end,
-		[], lists:reverse(str:tokens(Domain, <<".">>))).
-
 %%%----------------------------------------------------------------------
 %%% ejabberd commands