Advertise MAM in disco info for account/room JID

As per XEP-0313 version 0.2 and newer, advertise the MAM feature in the
service discovery information for the bare account (or MUC room) JID.

Some clients check the server's discovery information instead, so we'll
continue to advertise the feature there as well.

src/mod_mam.erl

@@ -34,8 +34,8 @@
 -export([start/2, stop/1]).
 
 -export([user_send_packet/4, user_receive_packet/5,
-	 process_iq_v0_2/3, process_iq_v0_3/3, remove_user/2,
+	 process_iq_v0_2/3, process_iq_v0_3/3, disco_sm_features/5,
-	 remove_user/3, mod_opt_type/1, muc_process_iq/4,
+	 remove_user/2, remove_user/3, mod_opt_type/1, muc_process_iq/4,
 	 muc_filter_message/5]).
 
 -include_lib("stdlib/include/ms_transform.hrl").
@@ -88,6 +88,8 @@ start(Host, Opts) ->
 		       muc_filter_message, 50),
     ejabberd_hooks:add(muc_process_iq, Host, ?MODULE,
 		       muc_process_iq, 50),
+    ejabberd_hooks:add(disco_sm_features, Host, ?MODULE,
+		       disco_sm_features, 50),
     ejabberd_hooks:add(remove_user, Host, ?MODULE,
 		       remove_user, 50),
     ejabberd_hooks:add(anonymous_purge_hook, Host, ?MODULE,
@@ -130,6 +132,8 @@ stop(Host) ->
     gen_iq_handler:remove_iq_handler(ejabberd_sm, Host, ?NS_MAM_0),
     gen_iq_handler:remove_iq_handler(ejabberd_local, Host, ?NS_MAM_1),
     gen_iq_handler:remove_iq_handler(ejabberd_sm, Host, ?NS_MAM_1),
+    ejabberd_hooks:delete(disco_sm_features, Host, ?MODULE,
+			  disco_sm_features, 50),
     ejabberd_hooks:delete(remove_user, Host, ?MODULE,
 			  remove_user, 50),
     ejabberd_hooks:delete(anonymous_purge_hook, Host,
@@ -276,6 +280,15 @@ get_xdata_fields(SubEl) ->
 	    []
     end.
 
+disco_sm_features(empty, From, To, Node, Lang) ->
+    disco_sm_features({result, []}, From, To, Node, Lang);
+disco_sm_features({result, OtherFeatures},
+		  #jid{luser = U, lserver = S},
+		  #jid{luser = U, lserver = S}, <<>>, _Lang) ->
+    {result, [?NS_MAM_TMP, ?NS_MAM_0, ?NS_MAM_1 | OtherFeatures]};
+disco_sm_features(Acc, _From, _To, _Node, _Lang) ->
+    Acc.
+
 %%%===================================================================
 %%% Internal functions
 %%%===================================================================

src/mod_muc_room.erl

@@ -4144,6 +4144,13 @@ process_iq_disco_info(_From, get, Lang, StateData) ->
 			     <<"muc_moderated">>, <<"muc_unmoderated">>),
       ?CONFIG_OPT_TO_FEATURE((Config#config.password_protected),
 			     <<"muc_passwordprotected">>, <<"muc_unsecured">>)]
+       ++ case {gen_mod:is_loaded(StateData#state.server_host, mod_mam),
+		Config#config.mam} of
+	    {true, true} ->
+		[?FEATURE(?NS_MAM_0)];
+	    _ ->
+		[]
+	  end
        ++ iq_disco_info_extras(Lang, StateData),
      StateData}.