Implement C2S redirection

- The feature is based on <see-other-host/> stream error, see RFC6120, 4.9.3.19
- To enable the feature you must set {redirect, true} in C2S listener section and set global "hostname" option on all nodes in cluster. The hostname must be string in the form as described in the RFC, for example: "foo.org", "foo.org:5222", "1.2.3.4", "[2001:41D0:1:A49b::1]:9222" and so on

src/ejabberd_c2s.erl

@@ -231,6 +231,12 @@ init([{SockMod, Socket}, Opts, FSMLimitOpts]) ->
 			(_) -> false
 		     end, Opts),
     TLSOpts = [verify_none | TLSOpts1],
+    Redirect = case lists:keysearch(redirect, 1, Opts) of
+                   {value, {_, true}} ->
+                       true;
+                   _ ->
+                       false
+               end,
     IP = case lists:keysearch(frontend_ip, 1, Opts) of
 	     {value, {_, IP1}} ->
 		 IP1;
@@ -265,6 +271,7 @@ init([{SockMod, Socket}, Opts, FSMLimitOpts]) ->
 			       access         = Access,
 			       shaper         = Shaper,
 			       ip             = IP,
+                               redirect       = Redirect,
 			       fsm_limit_opts = FSMLimitOpts},
 	    {ok, wait_for_stream, StateData, ?C2S_OPEN_TIMEOUT}
     end;
@@ -585,15 +592,20 @@ wait_for_auth({xmlstreamelement, El}, StateData) ->
 			       "(~w) Accepted legacy authentication for ~s by ~p",
 			       [StateData#state.socket,
 				jlib:jid_to_string(JID), AuthModule]),
+                            case need_redirect(StateData#state{user = U}) of
+                                {true, Host} ->
+                                    ?INFO_MSG("(~w) Redirecting ~s to ~s",
+                                              [StateData#state.socket,
+                                               jlib:jid_to_string(JID), Host]),
+                                    send_element(StateData, ?SERR_SEE_OTHER_HOST(Host)),
+                                    send_trailer(StateData),
+                                    {stop, normal, StateData};
+                                false ->
                                     SID = {now(), self()},
                                     Conn = get_conn_type(StateData),
-			    %% Info = [{ip, StateData#state.ip}, {conn, Conn},
-			    %% 	    {auth_module, AuthModule}],
                                     Res1 = jlib:make_result_iq_reply(El),
                                     Res = setelement(4, Res1, []),
                                     send_element(StateData, Res),
-			    %% ejabberd_sm:open_session(
-			    %%   SID, U, StateData#state.server, R, Info),
                                     change_shaper(StateData, JID),
                                     {Fs, Ts} = ejabberd_hooks:run_fold(
                                                  roster_get_subscription_lists,
@@ -606,10 +618,12 @@ wait_for_auth({xmlstreamelement, El}, StateData) ->
                                     Ts1 = [LJID | Ts],
                                     PrivList =
                                         ejabberd_hooks:run_fold(
-				  privacy_get_user_list, StateData#state.server,
+                                          privacy_get_user_list,
+                                          StateData#state.server,
                                           #userlist{},
                                           [U, StateData#state.server]),
-			    NewStateData = StateData#state{
+                                    NewStateData =
+                                        StateData#state{
                                           user = U,
                                           resource = R,
                                           jid = JID,
@@ -619,11 +633,14 @@ wait_for_auth({xmlstreamelement, El}, StateData) ->
                                           pres_f = ?SETS:from_list(Fs1),
                                           pres_t = ?SETS:from_list(Ts1),
                                           privacy_list = PrivList},
-			    DebugFlag = ejabberd_hooks:run_fold(c2s_debug_start_hook,
+                                    DebugFlag = ejabberd_hooks:run_fold(
+                                                  c2s_debug_start_hook,
                                                   NewStateData#state.server,
                                                   false,
                                                   [self(), NewStateData]),
-			    maybe_migrate(session_established, NewStateData#state{debug=DebugFlag});
+                                    maybe_migrate(session_established,
+                                                  NewStateData#state{debug=DebugFlag})
+                            end;
 			_ ->
 			    ?INFO_MSG(
 			       "(~w) Failed legacy authentication for ~s",
@@ -717,19 +734,28 @@ wait_for_feature_request({xmlstreamelement, El}, StateData) ->
 		{ok, Props} ->
                     catch (StateData#state.sockmod):reset_stream(
                             StateData#state.socket),
-		    send_element(StateData,
-				 {xmlelement, "success",
-				  [{"xmlns", ?NS_SASL}], []}),
                     U = xml:get_attr_s(username, Props),
                     AuthModule = xml:get_attr_s(auth_module, Props),
                     ?INFO_MSG("(~w) Accepted authentication for ~s by ~p",
                               [StateData#state.socket, U, AuthModule]),
+                    case need_redirect(StateData#state{user = U}) of
+                        {true, Host} ->
+                            ?INFO_MSG("(~w) Redirecting ~s to ~s",
+                                      [StateData#state.socket, U, Host]),
+                            send_element(StateData, ?SERR_SEE_OTHER_HOST(Host)),
+                            send_trailer(StateData),
+                            {stop, normal, StateData};
+                        false ->
+                            send_element(StateData,
+                                         {xmlelement, "success",
+                                          [{"xmlns", ?NS_SASL}], []}),
                             fsm_next_state(wait_for_stream,
                                            StateData#state{
                                              streamid = new_id(),
                                              authenticated = true,
                                              auth_module = AuthModule,
-				     user = U });
+                                             user = U })
+                    end;
 		{continue, ServerOut, NewSASLState} ->
 		    send_element(StateData,
 				 {xmlelement, "challenge",
@@ -870,19 +896,28 @@ wait_for_sasl_response({xmlstreamelement, El}, StateData) ->
 		{ok, Props} ->
 		    catch (StateData#state.sockmod):reset_stream(
                             StateData#state.socket),
-		    send_element(StateData,
-				 {xmlelement, "success",
-				  [{"xmlns", ?NS_SASL}], []}),
 		    U = xml:get_attr_s(username, Props),
 		    AuthModule = xml:get_attr_s(auth_module, Props),
 		    ?INFO_MSG("(~w) Accepted authentication for ~s by ~p",
 			      [StateData#state.socket, U, AuthModule]),
+                    case need_redirect(StateData#state{user = U}) of
+                        {true, Host} ->
+                            ?INFO_MSG("(~w) Redirecting ~s to ~s",
+                                      [StateData#state.socket, U, Host]),
+                            send_element(StateData, ?SERR_SEE_OTHER_HOST(Host)),
+                            send_trailer(StateData),
+                            {stop, normal, StateData};
+                        false ->
+                            send_element(StateData,
+                                         {xmlelement, "success",
+                                          [{"xmlns", ?NS_SASL}], []}),
                             fsm_next_state(wait_for_stream,
                                            StateData#state{
                                              streamid = new_id(),
                                              authenticated = true,
                                              auth_module = AuthModule,
-				     user = U});
+                                             user = U})
+                    end;
 		{continue, ServerOut, NewSASLState} ->
 		    send_element(StateData,
 				 {xmlelement, "challenge",
@@ -3394,3 +3429,21 @@ flash_policy_string() ->
 	++ ToPortsString ++
 	"\"/>\n"
 	"</cross-domain-policy>\n\0".
+
+need_redirect(#state{redirect = true, user = User, server = Server}) ->
+    LUser = jlib:nodeprep(User),
+    LServer = jlib:nameprep(Server),
+    case ejabberd_cluster:get_node({LUser, LServer}) of
+        Node when node() == Node ->
+            false;
+        Node ->
+            case rpc:call(Node, ejabberd_config,
+                          get_local_option, [hostname], 5000) of
+                Host when is_list(Host) ->
+                    {true, Host};
+                _ ->
+                    false
+            end
+    end;
+need_redirect(_) ->
+    false.

src/ejabberd_c2s.hrl

@@ -57,6 +57,7 @@
 		conn = unknown,
 		auth_module = unknown,
 		ip,
+                redirect = false,
                 aux_fields = [],
 		fsm_limit_opts,
 		lang,

src/ejabberd_config.erl

@@ -440,6 +440,8 @@ process_term(Term, State) ->
 	    State;
 	{max_fsm_queue, N} ->
 	    add_option(max_fsm_queue, N, State);
+        {hostname, Host} ->
+            add_option(hostname, Host, State);
 	{_Opt, _Val} ->
 	    lists:foldl(fun(Host, S) -> process_host_term(Term, Host, S) end,
 			State, State#state.hosts)

src/jlib.hrl

@@ -206,117 +206,117 @@
 	?ERRT_CONFLICT(Lang, "Resource conflict")).
 
 
--define(STREAM_ERROR(Condition),
+-define(STREAM_ERROR(Condition, Cdata),
 	{xmlelement, "stream:error",
 	 [],
-	 [{xmlelement, Condition, [{"xmlns", ?NS_STREAMS}], []}]}).
+	 [{xmlelement, Condition, [{"xmlns", ?NS_STREAMS}],
+           [{xmlcdata, Cdata}]}]}).
 
 -define(SERR_BAD_FORMAT,
-	?STREAM_ERROR("bad-format")).
+	?STREAM_ERROR("bad-format", "")).
 -define(SERR_BAD_NAMESPACE_PREFIX,
-	?STREAM_ERROR("bad-namespace-prefix")).
+	?STREAM_ERROR("bad-namespace-prefix", "")).
 -define(SERR_CONFLICT,
-	?STREAM_ERROR("conflict")).
+	?STREAM_ERROR("conflict", "")).
 -define(SERR_CONNECTION_TIMEOUT,
-	?STREAM_ERROR("connection-timeout")).
+	?STREAM_ERROR("connection-timeout", "")).
 -define(SERR_HOST_GONE,
-	?STREAM_ERROR("host-gone")).
+	?STREAM_ERROR("host-gone", "")).
 -define(SERR_HOST_UNKNOWN,
-	?STREAM_ERROR("host-unknown")).
+	?STREAM_ERROR("host-unknown", "")).
 -define(SERR_IMPROPER_ADDRESSING,
-	?STREAM_ERROR("improper-addressing")).
+	?STREAM_ERROR("improper-addressing", "")).
 -define(SERR_INTERNAL_SERVER_ERROR,
-	?STREAM_ERROR("internal-server-error")).
+	?STREAM_ERROR("internal-server-error", "")).
 -define(SERR_INVALID_FROM,
-	?STREAM_ERROR("invalid-from")).
+	?STREAM_ERROR("invalid-from", "")).
 -define(SERR_INVALID_ID,
-	?STREAM_ERROR("invalid-id")).
+	?STREAM_ERROR("invalid-id", "")).
 -define(SERR_INVALID_NAMESPACE,
-	?STREAM_ERROR("invalid-namespace")).
+	?STREAM_ERROR("invalid-namespace", "")).
 -define(SERR_INVALID_XML,
-	?STREAM_ERROR("invalid-xml")).
+	?STREAM_ERROR("invalid-xml", "")).
 -define(SERR_NOT_AUTHORIZED,
-	?STREAM_ERROR("not-authorized")).
+	?STREAM_ERROR("not-authorized", "")).
 -define(SERR_POLICY_VIOLATION,
-	?STREAM_ERROR("policy-violation")).
+	?STREAM_ERROR("policy-violation", "")).
 -define(SERR_REMOTE_CONNECTION_FAILED,
-	?STREAM_ERROR("remote-connection-failed")).
+	?STREAM_ERROR("remote-connection-failed", "")).
 -define(SERR_RESOURSE_CONSTRAINT,
-	?STREAM_ERROR("resource-constraint")).
+	?STREAM_ERROR("resource-constraint", "")).
 -define(SERR_RESTRICTED_XML,
-	?STREAM_ERROR("restricted-xml")).
+	?STREAM_ERROR("restricted-xml", "")).
-% TODO: include hostname or IP
+-define(SERR_SEE_OTHER_HOST(Host),
--define(SERR_SEE_OTHER_HOST,
+	?STREAM_ERROR("see-other-host", Host)).
-	?STREAM_ERROR("see-other-host")).
 -define(SERR_SYSTEM_SHUTDOWN,
-	?STREAM_ERROR("system-shutdown")).
+	?STREAM_ERROR("system-shutdown", "")).
 -define(SERR_UNSUPPORTED_ENCODING,
-	?STREAM_ERROR("unsupported-encoding")).
+	?STREAM_ERROR("unsupported-encoding", "")).
 -define(SERR_UNSUPPORTED_STANZA_TYPE,
-	?STREAM_ERROR("unsupported-stanza-type")).
+	?STREAM_ERROR("unsupported-stanza-type", "")).
 -define(SERR_UNSUPPORTED_VERSION,
-	?STREAM_ERROR("unsupported-version")).
+	?STREAM_ERROR("unsupported-version", "")).
 -define(SERR_XML_NOT_WELL_FORMED,
-	?STREAM_ERROR("xml-not-well-formed")).
+	?STREAM_ERROR("xml-not-well-formed", "")).
 %-define(SERR_,
-%	?STREAM_ERROR("")).
+%	?STREAM_ERROR("", "")).
 
--define(STREAM_ERRORT(Condition, Lang, Text),
+-define(STREAM_ERRORT(Condition, Cdata, Lang, Text),
 	{xmlelement, "stream:error",
 	 [],
-	 [{xmlelement, Condition, [{"xmlns", ?NS_STREAMS}], []},
+	 [{xmlelement, Condition, [{"xmlns", ?NS_STREAMS}],
+           [{xmlcdata, Cdata}]},
 	  {xmlelement, "text", [{"xml:lang", Lang}, {"xmlns", ?NS_STREAMS}],
 	   [{xmlcdata, translate:translate(Lang, Text)}]}]}).
 
 -define(SERRT_BAD_FORMAT(Lang, Text),
-	?STREAM_ERRORT("bad-format", Lang, Text)).
+	?STREAM_ERRORT("bad-format", "", Lang, Text)).
 -define(SERRT_BAD_NAMESPACE_PREFIX(Lang, Text),
-	?STREAM_ERRORT("bad-namespace-prefix", Lang, Text)).
+	?STREAM_ERRORT("bad-namespace-prefix", "", Lang, Text)).
 -define(SERRT_CONFLICT(Lang, Text),
-	?STREAM_ERRORT("conflict", Lang, Text)).
+	?STREAM_ERRORT("conflict", "", Lang, Text)).
 -define(SERRT_CONNECTION_TIMEOUT(Lang, Text),
-	?STREAM_ERRORT("connection-timeout", Lang, Text)).
+	?STREAM_ERRORT("connection-timeout", "", Lang, Text)).
 -define(SERRT_HOST_GONE(Lang, Text),
-	?STREAM_ERRORT("host-gone", Lang, Text)).
+	?STREAM_ERRORT("host-gone", "", Lang, Text)).
 -define(SERRT_HOST_UNKNOWN(Lang, Text),
-	?STREAM_ERRORT("host-unknown", Lang, Text)).
+	?STREAM_ERRORT("host-unknown", "", Lang, Text)).
 -define(SERRT_IMPROPER_ADDRESSING(Lang, Text),
-	?STREAM_ERRORT("improper-addressing", Lang, Text)).
+	?STREAM_ERRORT("improper-addressing", "", Lang, Text)).
 -define(SERRT_INTERNAL_SERVER_ERROR(Lang, Text),
-	?STREAM_ERRORT("internal-server-error", Lang, Text)).
+	?STREAM_ERRORT("internal-server-error", "", Lang, Text)).
 -define(SERRT_INVALID_FROM(Lang, Text),
-	?STREAM_ERRORT("invalid-from", Lang, Text)).
+	?STREAM_ERRORT("invalid-from", "", Lang, Text)).
 -define(SERRT_INVALID_ID(Lang, Text),
-	?STREAM_ERRORT("invalid-id", Lang, Text)).
+	?STREAM_ERRORT("invalid-id", "", Lang, Text)).
 -define(SERRT_INVALID_NAMESPACE(Lang, Text),
-	?STREAM_ERRORT("invalid-namespace", Lang, Text)).
+	?STREAM_ERRORT("invalid-namespace", "", Lang, Text)).
 -define(SERRT_INVALID_XML(Lang, Text),
-	?STREAM_ERRORT("invalid-xml", Lang, Text)).
+	?STREAM_ERRORT("invalid-xml", "", Lang, Text)).
 -define(SERRT_NOT_AUTHORIZED(Lang, Text),
-	?STREAM_ERRORT("not-authorized", Lang, Text)).
+	?STREAM_ERRORT("not-authorized", "", Lang, Text)).
 -define(SERRT_POLICY_VIOLATION(Lang, Text),
-	?STREAM_ERRORT("policy-violation", Lang, Text)).
+	?STREAM_ERRORT("policy-violation", "", Lang, Text)).
 -define(SERRT_REMOTE_CONNECTION_FAILED(Lang, Text),
-	?STREAM_ERRORT("remote-connection-failed", Lang, Text)).
+	?STREAM_ERRORT("remote-connection-failed", "", Lang, Text)).
 -define(SERRT_RESOURSE_CONSTRAINT(Lang, Text),
-	?STREAM_ERRORT("resource-constraint", Lang, Text)).
+	?STREAM_ERRORT("resource-constraint", "", Lang, Text)).
 -define(SERRT_RESTRICTED_XML(Lang, Text),
-	?STREAM_ERRORT("restricted-xml", Lang, Text)).
+	?STREAM_ERRORT("restricted-xml", "", Lang, Text)).
-% TODO: include hostname or IP
+-define(SERRT_SEE_OTHER_HOST(Host, Lang, Text),
--define(SERRT_SEE_OTHER_HOST(Lang, Text),
+	?STREAM_ERRORT("see-other-host", Host, Lang, Text)).
-	?STREAM_ERRORT("see-other-host", Lang, Text)).
 -define(SERRT_SYSTEM_SHUTDOWN(Lang, Text),
-	?STREAM_ERRORT("system-shutdown", Lang, Text)).
+	?STREAM_ERRORT("system-shutdown", "", Lang, Text)).
 -define(SERRT_UNSUPPORTED_ENCODING(Lang, Text),
-	?STREAM_ERRORT("unsupported-encoding", Lang, Text)).
+	?STREAM_ERRORT("unsupported-encoding", "", Lang, Text)).
 -define(SERRT_UNSUPPORTED_STANZA_TYPE(Lang, Text),
-	?STREAM_ERRORT("unsupported-stanza-type", Lang, Text)).
+	?STREAM_ERRORT("unsupported-stanza-type", "", Lang, Text)).
 -define(SERRT_UNSUPPORTED_VERSION(Lang, Text),
-	?STREAM_ERRORT("unsupported-version", Lang, Text)).
+	?STREAM_ERRORT("unsupported-version", "", Lang, Text)).
 -define(SERRT_XML_NOT_WELL_FORMED(Lang, Text),
-	?STREAM_ERRORT("xml-not-well-formed", Lang, Text)).
+	?STREAM_ERRORT("xml-not-well-formed", "", Lang, Text)).
 %-define(SERRT_(Lang, Text),
-%	?STREAM_ERRORT("", Lang, Text)).
+%	?STREAM_ERRORT("", "", Lang, Text)).
 
 
 -record(jid, {user, server, resource,