assertion when the ACK response is recognized as a merged request (pjsip#4203)

Author: LeonidGoltsblat

pjsip/src/pjsua-lib/pjsua_core.c

@@ -667,15 +667,31 @@ static pj_bool_t mod_pjsua_on_rx_request(pjsip_rx_data *rdata)
     pj_bool_t processed = PJ_FALSE;
 
 #if PJSUA_DETECT_MERGED_REQUESTS
-    if (pjsip_tsx_detect_merged_requests(rdata)) {
-        PJ_LOG(4, (THIS_FILE, "Merged request detected"));
+    pjsip_transaction *tsx;
+    if ((tsx = pjsip_tsx_detect_merged_requests(rdata)) != NULL) {
 
-        /* Respond with 482 (Loop Detected) */
-        pjsip_endpt_respond(pjsua_var.endpt, NULL, rdata,
-                            PJSIP_SC_LOOP_DETECTED, NULL,
-                            NULL, NULL, NULL);
+        pjsip_dialog *dlg = pjsip_tsx_get_dlg(tsx);
 
-        return PJ_TRUE;
+        PJ_LOG(4, (THIS_FILE, "Merged request detected (%s) (%s): %s from %s:%d",
+                              dlg ? dlg->obj_name : "-no-dlg-",
+                              tsx->obj_name,
+                              pjsip_rx_data_get_info(rdata),
+                              rdata->pkt_info.src_name,
+                              rdata->pkt_info.src_port));
+
+        /* Don't respond to ACK, even if it looks like a merged request 
+         * Let it be "dropped/unhandled by any modules"
+         */
+        if (pjsip_method_cmp(&rdata->msg_info.msg->line.req.method,
+                             &pjsip_ack_method) == 0) {
+            return PJ_FALSE;
+        } else {
+            /* Respond with 482 (Loop Detected) */
+            pjsip_endpt_respond(pjsua_var.endpt, NULL, rdata,
+                                PJSIP_SC_LOOP_DETECTED, NULL,
+                                NULL, NULL, NULL);
+            return PJ_TRUE;
+        }
     }
 #endif