Ticket #917: ticket917.patch

pjsip/src/pjsip/sip_util.c

@@ -572 +572 @@
 }
 
 
+/* 
+ * Add hidden Route header to the CANCEL and non-2xx ACK requests so that 
+ * the request is sent to the exact same address as the original INVITE.
+ * According to RFC 3263:
+ *  - CANCEL must be sent to the same server as INVITE. If we don't do 
+ *    this, we will do DNS SRV for it again (since it's different 
+ *    transaction) and it may end up being sent to a different server.
+ *  - same for non-2xx ACK
+ */
+static void route_ack_cancel(const pjsip_tx_data *inv_tdata,
+                             pjsip_tx_data *tdata)
+{
+    if (inv_tdata->tp_info.transport && 
+        pj_sockaddr_has_addr(&inv_tdata->tp_info.dst_addr))
+    {
+        const pj_str_t str_hide = {"hidden", 6};
+        pjsip_route_hdr *r;
+        pjsip_sip_uri *uri;
+        pjsip_param *p;
+
+        /* Create the Route header */
+        r = pjsip_route_hdr_create(tdata->pool);
+
+        /* Init the Route URI */
+        uri = pjsip_sip_uri_create(tdata->pool, PJ_FALSE);
+        r->name_addr.uri = (pjsip_uri*)uri;
+        pj_strdup2(tdata->pool, &uri->host, 
+                   inv_tdata->tp_info.dst_name);
+        uri->port = inv_tdata->tp_info.dst_port;
+        uri->lr_param = PJ_TRUE;
+        pj_strdup2(tdata->pool, &uri->transport_param,
+                   inv_tdata->tp_info.transport->type_name);
+        
+        /* Add "hide" parameter */
+        p = PJ_POOL_ZALLOC_T(tdata->pool, pjsip_param);
+        p->name = str_hide;
+        pj_list_push_back(&uri->other_param, p);
+
+        /* Add the header */
+        pjsip_msg_insert_first_hdr(tdata->msg, (pjsip_hdr*)r);
+    }
+}
+
 /*
  * Construct ACK for 3xx-6xx final response (according to chapter 17.1.1 of
  * RFC3261). Note that the generation of ACK for 2xx response is different,
@@ -659 +702 @@
         hdr = (pjsip_hdr*) pjsip_msg_find_hdr( invite_msg, PJSIP_H_ROUTE, hdr);
     }
 
+    /* ACK (for non-2xx response) must be sent to the same server according
+     * to RFC 3263, just like CANCEL. Though normally this code below is not
+     * required since the transaction should still have the transport 
+     * instance, there are cases when this is not the case (e.g. when TCP
+     * connection is prematurely closed), so doing this wouldn't hurt.
+     */
+    route_ack_cancel(tdata, ack);
+
     /* We're done.
      * "tdata" parameter now contains the ACK message.
      */
@@ -753 +804 @@
             break;
     }
 
+    /* Add hidden Route header in the request. According to RFC 3263, CANCEL
+     * must be sent to the same server as INVITE. If we don't do this, we
+     * will do DNS SRV for it again (since it's different transaction) and
+     * it may end up being sent to a different server.
+     */
+    route_ack_cancel(req_tdata, cancel_tdata);
+
     /* Done.
      * Return the transmit buffer containing the CANCEL request.
      */