transport management: Register thread with PJProject.

The scheduler thread that kills idle TCP connections was not registering
with PJProject properly and causing assertions if PJProject was built in
debug mode.

This change registers the thread with PJProject the first time that the
scheduler callback executes.

AST-2016-005

Change-Id: I5f7a37e2c80726a99afe9dc2a4a69bdedf661283

res/res_pjsip_transport_management.c

@@ -101,11 +101,29 @@ static void *keepalive_transport_thread(void *data)
 	return NULL;
 }
 
+AST_THREADSTORAGE(desc_storage);
+
 static int idle_sched_cb(const void *data)
 {
 	struct monitored_transport *keepalive = (struct monitored_transport *) data;
 	int sip_received = ast_atomic_fetchadd_int(&keepalive->sip_received, 0);
 
+	if (!pj_thread_is_registered()) {
+		pj_thread_t *thread;
+		pj_thread_desc *desc;
+
+		desc = ast_threadstorage_get(&desc_storage, sizeof(pj_thread_desc));
+		if (!desc) {
+			ast_log(LOG_ERROR, "Could not get thread desc from thread-local storage.\n");
+			ao2_ref(keepalive, -1);
+			return 0;
+		}
+
+		pj_bzero(*desc, sizeof(*desc));
+
+		pj_thread_register("Transport Monitor", *desc, &thread);
+	}
+
 	if (!sip_received) {
 		ast_log(LOG_NOTICE, "Shutting down transport '%s' since no request was received in %d seconds\n",
 				keepalive->transport->info, IDLE_TIMEOUT);