mod_push: Add 'notify_on' option

If the new 'notify_on' option is set to 'messages', notifications are
only triggered by actual chat messages with a body (or encrypted
payload).  The default behavior remains to generate a notification on
any kind of stanzas.

Thanks to EISST International Ltd for sponsoring this work.

src/mod_push.erl

@@ -135,6 +135,8 @@ depends(_Host, _Opts) ->
     [].
 
 -spec mod_opt_type(atom()) -> econf:validator().
+mod_opt_type(notify_on) ->
+    econf:enum([messages, all]);
 mod_opt_type(include_sender) ->
     econf:bool();
 mod_opt_type(include_body) ->
@@ -154,7 +156,8 @@ mod_opt_type(cache_life_time) ->
 
 -spec mod_options(binary()) -> [{atom(), any()}].
 mod_options(Host) ->
-    [{include_sender, false},
+    [{notify_on, all},
+     {include_sender, false},
      {include_body, <<"New message">>},
      {db_type, ejabberd_config:default_db(Host, ?MODULE)},
      {use_cache, ejabberd_option:use_cache(Host)},
@@ -175,7 +178,16 @@ mod_doc() ->
              "notification delivery to the user's mobile device using "
              "platform-dependant backend services such as FCM or APNS."),
       opts =>
-          [{include_sender,
+          [{notify_on,
+            #{value => "messages | all",
+              desc =>
+                  ?T("If this option is set to 'messages', notifications are "
+                     "generated only for actual chat messages with a body text "
+                     "(or some encrypted payload). If it's set to 'all', any "
+                     "kind of XMPP stanza will trigger a notification. If "
+                     "unsure, it's strongly recommended to stick to 'all', "
+                     "which is the default value.")}},
+           {include_sender,
             #{value => "true | false",
               desc =>
                   ?T("If this option is set to 'true', the sender's JID "
@@ -510,7 +522,11 @@ notify(LUser, LServer, Clients, Pkt, Dir) ->
 notify(LServer, PushLJID, Node, XData, Pkt0, Dir, HandleResponse) ->
     Pkt = unwrap_message(Pkt0),
     From = jid:make(LServer),
-    Summary = make_summary(LServer, Pkt, Dir),
+    case {make_summary(LServer, Pkt, Dir), mod_push_opt:notify_on(LServer)} of
+	{undefined, messages} ->
+	    ?DEBUG("Suppressing notification for stanza without payload", []),
+	    ok;
+	{Summary, _NotifyOn} ->
 	    Item = #ps_item{sub_els = [#push_notification{xdata = Summary}]},
 	    PubSub = #pubsub{publish = #ps_publish{node = Node, items = [Item]},
 			     publish_options = XData},
@@ -519,7 +535,8 @@ notify(LServer, PushLJID, Node, XData, Pkt0, Dir, HandleResponse) ->
 		     to = jid:make(PushLJID),
 		     id = p1_rand:get_string(),
 		     sub_els = [PubSub]},
-    ejabberd_router:route_iq(IQ, HandleResponse).
+	    ejabberd_router:route_iq(IQ, HandleResponse)
+    end.
 
 %%--------------------------------------------------------------------
 %% Miscellaneous.

src/mod_push_opt.erl

@@ -9,6 +9,7 @@
 -export([db_type/1]).
 -export([include_body/1]).
 -export([include_sender/1]).
+-export([notify_on/1]).
 -export([use_cache/1]).
 
 -spec cache_life_time(gen_mod:opts() | global | binary()) -> 'infinity' | pos_integer().
@@ -47,6 +48,12 @@ include_sender(Opts) when is_map(Opts) ->
 include_sender(Host) ->
     gen_mod:get_module_opt(Host, mod_push, include_sender).
 
+-spec notify_on(gen_mod:opts() | global | binary()) -> 'all' | 'messages'.
+notify_on(Opts) when is_map(Opts) ->
+    gen_mod:get_opt(notify_on, Opts);
+notify_on(Host) ->
+    gen_mod:get_module_opt(Host, mod_push, notify_on).
+
 -spec use_cache(gen_mod:opts() | global | binary()) -> boolean().
 use_cache(Opts) when is_map(Opts) ->
     gen_mod:get_opt(use_cache, Opts);