[置顶] 修正PJSIP挂不断电话的问题

A呼叫B的过程中，如果B已经接通了电话，但是200 ok还未回到A这方，但这时A挂断电话，会出现
一、A发送CANCEL到B。
二、A收到INVITE的200 ok，回复ACK，并将通话置为接通状态
三、B接收到CANCEL，回复200 ok，但接着不会发送487
（正常的CANCEL过程参考http://yeyingxian.blog.163.com/blog/static/344712420130238404943/）

A      Opensips      B

 =====> INVITE
               =====> INVITE
               <==== 100 Trying

               <===== 200 OK (INVITE)
  =====> CANCEL
               =====> CANCEL
<===== 200 OK (INVITE)
  =====> ACK
               <===== 200 OK (CANCEL)
<===== 200 OK (CANCEL)
               =====> ACK

        时序图

 

结果就是A想挂断电话，结果电话却是偷偷接通了。
修正方法，在A正在CANCEL的过程中，如果收到200 ok，则紧接着发送BYE来取消会话

sip_inv.c中的inv_set_state

 

        if (pjmedia_sdp_neg_get_state(inv->neg)!=PJMEDIA_SDP_NEG_STATE_DONE &&
            (tsx_inv_data && !tsx_inv_data->sdp_done) )
        {
            pjsip_tx_data *bye;

            PJ_LOG(4,(inv->obj_name, "SDP offer/answer incomplete, ending the "
                "session"));

            status = pjsip_inv_end_session(inv, PJSIP_SC_NOT_ACCEPTABLE, 
                NULL, &bye);
            if (status == PJ_SUCCESS && bye)
                status = pjsip_inv_send_msg(inv, bye);

            return;
        }

+        if (inv->cancelling)
+        {
+            pjsip_tx_data *bye;
+
+            PJ_LOG(4,(inv->obj_name, "End session, because cancellation is in progress"));
+
+            status = pjsip_inv_end_session(inv, PJSIP_SC_NOT_ACCEPTABLE, 
+                NULL, &bye);
+            if (status == PJ_SUCCESS && bye)
+                status = pjsip_inv_send_msg(inv, bye);
+
+            return;
+        }
    }

    /* Set state. */
    inv->state = state;