mod_offline: Support discarding chat states

XEP-0160 says that standalone chat state notifications should not be
stored offline.  By default, mod_offline discards them now.

Closes #842.

src/jlib.erl

@@ -43,6 +43,7 @@
 	 get_iq_namespace/1, iq_query_info/1,
 	 iq_query_or_response_info/1, is_iq_request_type/1,
 	 iq_to_xml/1, parse_xdata_submit/1,
+	 is_standalone_chat_state/1,
 	 add_delay_info/3, add_delay_info/4,
 	 timestamp_to_iso/1, timestamp_to_iso/2,
 	 now_to_utc_string/1, now_to_local_string/1,
@@ -527,6 +528,26 @@ rsm_encode_count(Count, Arr) ->
 	    children = [{xmlcdata, i2l(Count)}]}
      | Arr].
 
+-spec is_standalone_chat_state(xmlel()) -> boolean().
+
+is_standalone_chat_state(#xmlel{name = <<"message">>} = El) ->
+    ChatStates = [<<"active">>, <<"inactive">>, <<"gone">>, <<"composing">>,
+		  <<"paused">>],
+    Stripped =
+	lists:foldl(fun(ChatState, AccEl) ->
+			    xml:remove_subtags(AccEl, ChatState,
+					       {<<"xmlns">>, ?NS_CHATSTATES})
+		    end, El, ChatStates),
+    case Stripped of
+      #xmlel{children = [#xmlel{name = <<"thread">>}]} ->
+	  true;
+      #xmlel{children = []} ->
+	  true;
+      _ ->
+	  false
+    end;
+is_standalone_chat_state(_El) -> false.
+
 -spec add_delay_info(xmlel(), jid() | ljid() | binary(), erlang:timestamp())
 		     -> xmlel().
 

src/mod_client_state.erl

@@ -91,22 +91,12 @@ filter_presence(_Action, #xmlel{name = <<"presence">>, attrs = Attrs}) ->
 filter_presence(Action, _Stanza) -> Action.
 
 filter_chat_states(_Action, #xmlel{name = <<"message">>} = Stanza) ->
-    %% All XEP-0085 chat states except for <gone/>:
-    ChatStates = [<<"active">>, <<"inactive">>, <<"composing">>, <<"paused">>],
-    Stripped =
-	lists:foldl(fun(ChatState, AccStanza) ->
-			    xml:remove_subtags(AccStanza, ChatState,
-					       {<<"xmlns">>, ?NS_CHATSTATES})
-		    end, Stanza, ChatStates),
-    case Stripped of
-      #xmlel{children = [#xmlel{name = <<"thread">>}]} ->
+    case jlib:is_standalone_chat_state(Stanza) of
+      true ->
 	  ?DEBUG("Got standalone chat state notification", []),
 	  {stop, drop};
-      #xmlel{children = []} ->
-	  ?DEBUG("Got standalone chat state notification", []),
-	  {stop, drop};
-      _ ->
-	  ?DEBUG("Got message with chat state notification", []),
+      false ->
+	  ?DEBUG("Got message stanza", []),
 	  {stop, send}
     end;
 filter_chat_states(Action, _Stanza) -> Action.

src/mod_offline.erl

@@ -286,10 +286,14 @@ need_to_store(LServer, Packet) ->
        and (Type /= <<"headline">>) ->
 	    case gen_mod:get_module_opt(
 		   LServer, ?MODULE, store_empty_body,
-		   fun(V) when is_boolean(V) -> V end,
-		   true) of
+		   fun(V) when is_boolean(V) -> V;
+		      (unless_chat_state) -> unless_chat_state
+		   end,
+		   unless_chat_state) of
 		false ->
 		    xml:get_subtag(Packet, <<"body">>) /= false;
+		unless_chat_state ->
+		    not jlib:is_standalone_chat_state(Packet);
 		true ->
 		    true
 	    end;
@@ -1129,6 +1133,8 @@ mod_opt_type(access_max_user_messages) ->
     fun (A) -> A end;
 mod_opt_type(db_type) -> fun gen_mod:v_db/1;
 mod_opt_type(store_empty_body) ->
-    fun (V) when is_boolean(V) -> V end;
+    fun (V) when is_boolean(V) -> V;
+        (unless_chat_state) -> unless_chat_state
+    end;
 mod_opt_type(_) ->
     [access_max_user_messages, db_type, store_empty_body].