Prevent crash from trying to end a session in an invalid way.

This ensures that code that was only meant to be run on a reinvite failure
only runs on a reinvite failure.

(closes issue ASTERISK-22061)
reported by Rusty Newton



git-svn-id: https://origsvn.digium.com/svn/asterisk/trunk@394473 65c4cc65-6c06-0410-ace0-fbb531ad65f3

res/res_sip_session.c

@@ -1609,11 +1609,12 @@ static void session_inv_on_tsx_state_changed(pjsip_inv_session *inv, pjsip_trans
 				if (tsx->status_code == PJSIP_SC_REQUEST_PENDING) {
 					reschedule_reinvite(session, tsx->mod_data[session_module.id], tsx->last_tx);
 					return;
-				} else {
-					/* Other failures result in destroying the session. */
+				} else if (inv->state == PJSIP_INV_STATE_CONFIRMED) {
+					/* Other reinvite failures result in destroying the session. */
 					pjsip_tx_data *tdata;
-					pjsip_inv_end_session(inv, 500, NULL, &tdata);
-					ast_sip_session_send_request(session, tdata);
+					if (pjsip_inv_end_session(inv, 500, NULL, &tdata) == PJ_SUCCESS) {
+						ast_sip_session_send_request(session, tdata);
+					}
 				}
 			}
 		} else {