Offer CSI stream feature only if configured

Don't offer the CSI stream feature when mod_client_state isn't actually
configured to filter stanzas.  This makes sure clients won't send CSI
tags that end up being ignored.

src/ejabberd_c2s.erl

@@ -479,10 +479,6 @@ wait_for_stream({xmlstreamstart, _Name, Attrs}, StateData) ->
 					      false ->
 						  []
 					    end,
-					ClientStateFeature =
-					    [#xmlel{name = <<"csi">>,
-						    attrs = [{<<"xmlns">>, ?NS_CLIENT_STATE}],
-						    children = []}],
 					StreamFeatures = [#xmlel{name = <<"bind">>,
 								attrs = [{<<"xmlns">>, ?NS_BIND}],
 								children = []},
@@ -492,7 +488,6 @@ wait_for_stream({xmlstreamstart, _Name, Attrs}, StateData) ->
 							    ++
 							    RosterVersioningFeature ++
 							    StreamManagementFeature ++
-							    ClientStateFeature ++
 							    ejabberd_hooks:run_fold(c2s_post_auth_features,
 								Server, [], [Server]) ++
 							    ejabberd_hooks:run_fold(c2s_stream_features,

src/mod_client_state.erl

@@ -28,7 +28,8 @@
 
 -behavior(gen_mod).
 
--export([start/2, stop/1, filter_presence/2, filter_chat_states/2]).
+-export([start/2, stop/1, add_stream_feature/2, filter_presence/2,
+	 filter_chat_states/2]).
 
 -include("ejabberd.hrl").
 -include("logger.hrl").
@@ -39,6 +40,9 @@ start(Host, Opts) ->
 				    fun(true) -> true end, false),
     DropChatStates = gen_mod:get_opt(drop_chat_states, Opts,
 				     fun(true) -> true end, false),
+    if QueuePresence; DropChatStates ->
+	   ejabberd_hooks:add(c2s_post_auth_features, Host, ?MODULE,
+			      add_stream_feature, 50),
 	   if QueuePresence ->
 		  ejabberd_hooks:add(csi_filter_stanza, Host, ?MODULE,
 				     filter_presence, 50);
@@ -48,6 +52,8 @@ start(Host, Opts) ->
 		  ejabberd_hooks:add(csi_filter_stanza, Host, ?MODULE,
 				     filter_chat_states, 50);
 	      true -> ok
+	   end;
+       true -> ok
     end,
     ok.
 
@@ -56,8 +62,16 @@ stop(Host) ->
 			  filter_presence, 50),
     ejabberd_hooks:delete(csi_filter_stanza, Host, ?MODULE,
 			  filter_chat_states, 50),
+    ejabberd_hooks:delete(c2s_post_auth_features, Host, ?MODULE,
+			  add_stream_feature, 50),
     ok.
 
+add_stream_feature(Features, _Host) ->
+    Feature = #xmlel{name = <<"csi">>,
+		     attrs = [{<<"xmlns">>, ?NS_CLIENT_STATE}],
+		     children = []},
+    [Feature | Features].
+
 filter_presence(_Action, #xmlel{name = <<"presence">>, attrs = Attrs}) ->
     case xml:get_attr(<<"type">>, Attrs) of
       {value, Type} when Type /= <<"unavailable">> ->