res_pjsip: Add missing NULL checks when using pjsip_inv_end_session().

pjsip_inv_end_session() is documented as being able to return the
passed in tdata parameter set to NULL on success.

Change-Id: I09d53725c49b7183c41bfa1be3ff225f3a8d3047

channels/chan_pjsip.c

@@ -1417,7 +1417,8 @@ static void transfer_redirect(struct ast_sip_session *session, const char *targe
 	pjsip_contact_hdr *contact;
 	pj_str_t tmp;
 
-	if (pjsip_inv_end_session(session->inv_session, 302, NULL, &packet) != PJ_SUCCESS) {
+	if (pjsip_inv_end_session(session->inv_session, 302, NULL, &packet) != PJ_SUCCESS
+		|| !packet) {
 		ast_log(LOG_WARNING, "Failed to redirect PJSIP session for channel %s\n",
 			ast_channel_name(session->channel));
 		message = AST_TRANSFER_FAILED;
@@ -2182,7 +2183,8 @@ static int chan_pjsip_incoming_request(struct ast_sip_session *session, struct p
 	ast_sip_session_add_datastore(session, datastore);
 
 	if (!(session->channel = chan_pjsip_new(session, AST_STATE_RING, session->exten, NULL, NULL, NULL, NULL))) {
-		if (pjsip_inv_end_session(session->inv_session, 503, NULL, &packet) == PJ_SUCCESS) {
+		if (pjsip_inv_end_session(session->inv_session, 503, NULL, &packet) == PJ_SUCCESS
+			&& packet) {
 			ast_sip_session_send_response(session, packet);
 		}
 

res/res_pjsip_refer.c

@@ -969,7 +969,8 @@ inv_replace_failed:
 		session->defer_terminate = 1;
 		ast_hangup(session->channel);
 
-		if (pjsip_inv_end_session(session->inv_session, response, NULL, &packet) == PJ_SUCCESS) {
+		if (pjsip_inv_end_session(session->inv_session, response, NULL, &packet) == PJ_SUCCESS
+			&& packet) {
 			ast_sip_session_send_response(session, packet);
 		}
 	} else {

res/res_pjsip_session.c

@@ -2619,7 +2619,8 @@ static void session_inv_on_tsx_state_changed(pjsip_inv_session *inv, pjsip_trans
 						}
 						if (tsx->status_code != 488) {
 							/* Other reinvite failures (except 488) result in destroying the session. */
-							if (pjsip_inv_end_session(inv, 500, NULL, &tdata) == PJ_SUCCESS) {
+							if (pjsip_inv_end_session(inv, 500, NULL, &tdata) == PJ_SUCCESS
+								&& tdata) {
 								ast_sip_session_send_request(session, tdata);
 							}
 						}
@@ -2632,7 +2633,8 @@ static void session_inv_on_tsx_state_changed(pjsip_inv_session *inv, pjsip_trans
 						 * a cancelled call. Our role is to immediately send a BYE to end the
 						 * dialog.
 						 */
-						if (pjsip_inv_end_session(inv, 500, NULL, &tdata) == PJ_SUCCESS) {
+						if (pjsip_inv_end_session(inv, 500, NULL, &tdata) == PJ_SUCCESS
+							&& tdata) {
 							ast_sip_session_send_request(session, tdata);
 						}
 					}