[lwip-users] question about netconn_write

[yueyue papa]

Hi All,

 

I am using lwIP 1.3+ PPP working in GPRS environment.

I meet following case

 

There is TCP connection between A,B.

A:                    B:

     ------------- -->

     <---------------

     ------------- -->

     <---------------

     ------------- -->

     <---------------

 

Some time the flow could work correct, some time A is waiting, and B is waiting. I put in the LAN environment, every thing is ok. The problem is only in GPRS environment. Anther side in out of my control I unable to run wireshark to monitor what happened.

 

After I read the code, I have this guess. May this thing possible that netconn_write return, but the data is not send out.

 

netconn_write return  means

 

1> Data in the TCP/IP stack

 

Wether it comes out depend the task schedule, if the data is lost in the line, the netconn_write already returned.

 

If it is true, is the any API could i flush the data in the send buffer, force the data send out, and make sure the data has been ACK by remote.

 

Lee