From 0a9212583dd59535432a10e88aeaec097ae1bd0a Mon Sep 17 00:00:00 2001
From: Holger Weiss <holger@zedat.fu-berlin.de>
Date: Tue, 16 Sep 2014 22:42:34 +0200
Subject: [PATCH] XEP-0198: Support "resend_on_timeout: if_offline"

If "resend_on_timeout" is set to "if_offline", resend unacknowledged
stanzas only if no other resource is online when the session times out.
In other words, allow for sending them to offline storage, but nowhere
else.
---
 doc/guide.tex        | 10 +++++++---
 src/ejabberd_c2s.erl | 16 ++++++++++++++--
 2 files changed, 21 insertions(+), 5 deletions(-)

diff --git a/doc/guide.tex b/doc/guide.tex
index 27fcfc181..efebc2521 100644
--- a/doc/guide.tex
+++ b/doc/guide.tex
@@ -1022,7 +1022,7 @@ request_handlers:
   /"a"/"b": mod_foo
   /"http-bind": mod_http_bind
 \end{verbatim}
-  \titem{resend\_on\_timeout: true|false}
+  \titem{resend\_on\_timeout: true|false|if\_offline}
     If \term{stream\_management} is enabled and this option is set to
     \term{true}, any stanzas that weren't acknowledged by the client
     will be resent on session timeout. This behavior might often be
@@ -1030,8 +1030,12 @@ request_handlers:
     circumstances. For example, a message that was sent to two resources
     might get resent to one of them if the other one timed out.
     Therefore, the default value for this option is \term{false}, which
-    tells ejabberd to generate an error message instead. The option can
-    be specified for \term{ejabberd\_c2s} listeners.
+    tells ejabberd to generate an error message instead. As an
+    alternative, the option may be set to \term{if\_offline}. In this
+    case, unacknowledged stanzas are resent only if no other resource is
+    online when the session times out. Otherwise, error messages are
+    generated. The option can be specified for \term{ejabberd\_c2s}
+    listeners.
   \titem{resume\_timeout: Seconds}
     This option configures the number of seconds until a session times
     out if the connection is lost. During this period of time, a client
diff --git a/src/ejabberd_c2s.erl b/src/ejabberd_c2s.erl
index cb6f9e6d8..d0dfd2553 100644
--- a/src/ejabberd_c2s.erl
+++ b/src/ejabberd_c2s.erl
@@ -316,7 +316,11 @@ init([{SockMod, Socket}, Opts]) ->
 		      Timeout when is_integer(Timeout), Timeout >= 0 -> Timeout;
 		      _ -> 300
 		    end,
-    ResendOnTimeout = proplists:get_bool(resend_on_timeout, Opts),
+    ResendOnTimeout = case proplists:get_value(resend_on_timeout, Opts) of
+			Resend when is_boolean(Resend) -> Resend;
+			if_offline -> if_offline;
+			_ -> false
+		      end,
     IP = peerip(SockMod, Socket),
     Socket1 = if TLSEnabled andalso
 		 SockMod /= ejabberd_frontend_socket ->
@@ -2879,7 +2883,15 @@ handle_unacked_stanzas(_StateData, _F) ->
 handle_unacked_stanzas(StateData)
     when StateData#state.mgmt_state == active;
 	 StateData#state.mgmt_state == pending ->
-    ReRoute = case StateData#state.mgmt_resend of
+    ResendOnTimeout =
+	case StateData#state.mgmt_resend of
+	  Resend when is_boolean(Resend) ->
+	      Resend;
+	  if_offline ->
+	      ejabberd_sm:get_user_resources(StateData#state.user,
+					     StateData#state.server) == []
+	end,
+    ReRoute = case ResendOnTimeout of
 		true ->
 		    fun ejabberd_router:route/3;
 		false ->