libplugin: support wildcard subscriptions.

Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>

plugins/libplugin.c

@@ -1607,7 +1607,8 @@ static void ld_command_handle(struct plugin *plugin,
 #endif
 		for (size_t i = 0; i < plugin->num_notif_subs; i++) {
 			if (streq(cmd->methodname,
-				  plugin->notif_subs[i].name)) {
+				  plugin->notif_subs[i].name)
+			    || streq(plugin->notif_subs[i].name, "*")) {
 				plugin->notif_subs[i].handle(cmd,
 							     plugin->buffer,
 							     paramstok);

plugins/libplugin.h

@@ -87,6 +87,7 @@ struct plugin_option {
 
 /* Create an array of these, one for each notification you subscribe to. */
 struct plugin_notification {
+	/* "*" means wildcard: notify me on everything (should be last!) */
 	const char *name;
 	/* The handler must eventually trigger a `notification_handled`
 	 * call.  */

tests/plugins/test_libplugin.c

@@ -101,6 +101,17 @@ static struct command_result *json_shutdown(struct command *cmd,
 	plugin_exit(cmd->plugin, 0);
 }
 
+static struct command_result *json_all_notifs(struct command *cmd,
+					      const char *buf,
+					      const jsmntok_t *params)
+{
+	plugin_log(cmd->plugin, LOG_DBG, "all: %s: %.*s",
+		   cmd->methodname,
+		   json_tok_full_len(params),
+		   json_tok_full(buf, params));
+	return notification_handled(cmd);
+}
+
 static struct command_result *testrpc_cb(struct command *cmd,
 					 const char *buf,
 					 const jsmntok_t *params,
@@ -209,6 +220,9 @@ static const struct plugin_notification notifs[] = { {
 	}, {
 		"shutdown",
 		json_shutdown
+	}, {
+		"*",
+		json_all_notifs
 	}
 };
 

tests/test_plugin.py

@@ -4252,11 +4252,14 @@ def test_plugin_persist_option(node_factory):
 
 def test_all_subscription(node_factory, directory):
     """Ensure that registering for all notifications works."""
-    plugin = os.path.join(os.getcwd(), 'tests/plugins/all_notifications.py')
+    plugin1 = os.path.join(os.getcwd(), 'tests/plugins/all_notifications.py')
+    plugin2 = os.path.join(os.getcwd(), "tests/plugins/test_libplugin")
 
-    l1, l2 = node_factory.line_graph(2, opts={"plugin": plugin})
+    l1, l2 = node_factory.line_graph(2, opts=[{"plugin": plugin1},
+                                              {"plugin": plugin2}])
 
     l1.stop()
+    l2.stop()
 
     # There will be a lot of these!
     for notstr in ("block_added: {'block_added': {'hash': ",
@@ -4265,3 +4268,12 @@ def test_all_subscription(node_factory, directory):
                    "channel_state_changed: {'channel_state_changed': {'peer_id': ",
                    "shutdown: {}"):
         assert l1.daemon.is_in_log(f".*plugin-all_notifications.py: notification {notstr}.*")
+
+    for notstr in ('block_added: ',
+                   'balance_snapshot: ',
+                   'channel_state_changed: {'):
+        assert l2.daemon.is_in_log(f'.*test_libplugin: all: {notstr}.*')
+
+    # shutdown and connect are subscribed before the wildcard, so is handled by that handler
+    assert not l2.daemon.is_in_log(f'.*test_libplugin: all: shutdown.*')
+    assert not l2.daemon.is_in_log(f'.*test_libplugin: all: connect.*')