XEP-0198: Handle timeouts during stream resumption

If session resumption failed because requesting the #state from the old
c2s process took too long, the new c2s process will usually receive the
response.  Let the new process handle that case gracefully.

diff --git a/src/ejabberd_c2s.erl b/src/ejabberd_c2s.erl
index d69599485abe75518b3cb26b73ed12bb70585866..74b78512ac869ad2c64835163acdbe44545ab6d0 100644 (file)
--- a/src/ejabberd_c2s.erl
+++ b/src/ejabberd_c2s.erl
@@ -1318,7 +1318,7 @@ handle_sync_event({resume_session, Time}, _From, _StateName,
                              StateData#state.user,
                              StateData#state.server,
                              StateData#state.resource),
-    {stop, normal, {ok, StateData}, StateData#state{mgmt_state = resumed}};
+    {stop, normal, {resume, StateData}, StateData#state{mgmt_state = resumed}};
 handle_sync_event({resume_session, _Time}, _From, StateName,
                  StateData) ->
     {reply, {error, <<"Previous session not found">>}, StateName, StateData};
@@ -1745,6 +1745,13 @@ handle_info({broadcast, Type, From, Packet}, StateName, StateData) ->
     fsm_next_state(StateName, StateData);
 handle_info(dont_ask_offline, StateName, StateData) ->
     fsm_next_state(StateName, StateData#state{ask_offline = false});
+handle_info({_Ref, {resume, OldStateData}}, StateName, StateData) ->
+    %% This happens if the resume_session/1 request timed out; the new session
+    %% now receives the late response.
+    ?DEBUG("Received old session state for ~s after failed resumption",
+          [jid:to_string(OldStateData#state.jid)]),
+    handle_unacked_stanzas(OldStateData#state{mgmt_resend = false}),
+    fsm_next_state(StateName, StateData);
 handle_info(Info, StateName, StateData) ->
     ?ERROR_MSG("Unexpected info: ~p", [Info]),
     fsm_next_state(StateName, StateData).
@@ -3017,7 +3024,7 @@ inherit_session_state(#state{user = U, server = S} = StateData, ResumeID) ->
            OldPID ->
                OldSID = {Time, OldPID},
                case catch resume_session(OldSID) of
-                 {ok, OldStateData} ->
+                 {resume, OldStateData} ->
                      NewSID = {Time, self()}, % Old time, new PID
                      Priority = case OldStateData#state.pres_last of
                                   undefined ->