[lwip-users] tcpi connection break

[Fabian Cenedese]

Hi

I've had now some success with lwip and tcp, exchanging
some frames. But I have some problems that I don't
understand yet.

I try to read data from an external device, sending simple
commands and receiving some data, always less than
20 bytes.

To send data lwip has to do an ARP request first. Sometimes
it happens that the reply comes back (I check for it in the
received frames directly), the frame is given to lwip but still
the ARP cache is not updated. The entry for this address
is still on 00... But that happens very seldom.

More serious is this case: After calling lwip_connect the
connection gets established and the tcpip_thread ist handling
the connection. Sometimes it happens that lwip_read will
not return, lwip has seemingly not received any data. But
it will not return with an error. Even if I unplug the other device
lwip just continues without any error and my thread doesn't
return from read.

Log:
...
tcp_slowtmr: processing active pcb
tcp_slowtmr: processing active pcb
tcp_slowtmr: processing active pcb
tcp_slowtmr: processing active pcb
tcp_slowtmr: polling application
tcp_output: nothing to send (0x0)
tcp_output: snd_wnd 2047, cwnd 3072, wnd 2047, seg == NULL, ack 6522
tcp_slowtmr: processing active pcb
tcp_slowtmr: processing active pcb
tcp_slowtmr: processing active pcb
tcp_slowtmr: processing active pcb
tcp_slowtmr: polling application
tcp_output: nothing to send (0x0)
tcp_output: snd_wnd 2047, cwnd 3072, wnd 2047, seg == NULL, ack 6522
...

Where should the breakup/timeout be handled?

Thanks

bye  Fabi