res/ari: Register Stasis application on WebSocket attempt

Prior to this patch, when a WebSocket connection is made, ARI would not
be informed of the connection until after the WebSocket layer had
accepted the connection. This created a brief race condition where the
ARI client would be notified that it was connected, a channel would be
sent into the Stasis dialplan application, but ARI would not yet have
registered the Stasis application presented in the HTTP request that
established the WebSocket.

This patch resolves this issue by doing the following:
 * When a WebSocket attempt is made, a callback is made into the ARI
   application layer, which verifies and registers the apps presented in
   the HTTP request. Because we do not yet have a WebSocket, we cannot
   have an event session for the corresponding applications. Some
   defensive checks were thus added to make the application objects
   tolerant to a NULL event session.
 * When a WebSocket connection is made, the registered application is
   updated with the newly created event session that wraps the WebSocket
   connection.

ASTERISK-24988 #close
Reported by: Joshua Colp

Change-Id: Ia5dc60dc2b6bee76cd5aff0f69dd53b36e83f636

1 files changed, 2 insertions, 3 deletions

diff --git a/res/stasis/app.c b/res/stasis/app.c
index 5a1c5f8e2..b99e23205 100644
--- a/res/stasis/app.c
+++ b/res/stasis/app.c
@@ -871,8 +871,7 @@ struct stasis_app *app_create(const char *name, stasis_app_cb handler, void *dat
 
 	strncpy(app->name, name, size - sizeof(*app));
 	app->handler = handler;
-	ao2_ref(data, +1);
-	app->data = data;
+	app->data = ao2_bump(data);
 
 	ao2_ref(app, +1);
 	return app;
@@ -950,7 +949,7 @@ void app_update(struct stasis_app *app, stasis_app_cb handler, void *data)
 {
 	SCOPED_AO2LOCK(lock, app);
 
-	if (app->handler) {
+	if (app->handler && app->data) {
 		RAII_VAR(struct ast_json *, msg, NULL, ast_json_unref);
 
 		ast_verb(1, "Replacing Stasis app '%s'\n", app->name);