res_pjsip_session: Release media resources on session end quicker.

A change was made long ago where the session was kept around
until the underlying INVITE session had been destroyed. This
had the side effect of also keeping the underlying media resources
around for this time as well.

This change ensures that when we know the session is ending we
release the media resources immediately.

ASTERISK-27110

Change-Id: I3c6a82fe7d2c50b9dc9197cb12ef22f20d337501

channels/chan_pjsip.c

@@ -2273,7 +2273,6 @@ static struct hangup_data *hangup_data_alloc(int cause, struct ast_channel *chan
 static void clear_session_and_channel(struct ast_sip_session *session, struct ast_channel *ast)
 {
 	session->channel = NULL;
-	set_channel_on_rtp_instance(session, "");
 	ast_channel_tech_pvt_set(ast, NULL);
 }
 

res/res_pjsip_session.c

@@ -1872,8 +1872,12 @@ static void session_destructor(void *obj)
 
 	ast_taskprocessor_unreference(session->serializer);
 	ao2_cleanup(session->datastores);
-	ast_sip_session_media_state_free(session->active_media_state);
-	ast_sip_session_media_state_free(session->pending_media_state);
+	if (session->active_media_state) {
+		ast_sip_session_media_state_free(session->active_media_state);
+	}
+	if (session->pending_media_state) {
+		ast_sip_session_media_state_free(session->pending_media_state);
+	}
 
 	AST_LIST_HEAD_DESTROY(&session->supplements);
 	while ((delay = AST_LIST_REMOVE_HEAD(&session->delayed_requests, next))) {
@@ -3134,6 +3138,13 @@ static int session_end(void *vsession)
 			iter->session_end(session);
 		}
 	}
+
+	/* Release any media resources. */
+	ast_sip_session_media_state_free(session->active_media_state);
+	session->active_media_state = NULL;
+	ast_sip_session_media_state_free(session->pending_media_state);
+	session->pending_media_state = NULL;
+
 	return 0;
 }