Re: [lwip-devel] One question about codes of tcp_input in tcp_in.c

[Kieran Mansley]

On Sun, 2005-10-23 at 14:43 +0800, mud dog wrote:
> Hi all:
> When reading the tcp codes of lwIP, I made a question.
> After calling the tcp_process in tcp_input, we determine
> the return status and flags of tcp_process, when err != ERR_ABRT 
> and recv_flags' TF_RESET,TF_CLOSED is not set, call the
> tcp_output(pcb)
> to send what? why do this?

I haven't looked at the code in detail to answer this, but my guess is
that it is to try to send any data that were queued because, for
example, there was no available TCP window space to send them.  After
receiving and processing a packet, it is likely that the acknowledgement
contained within it will allow more data to be sent, and so
tcp_output(pcb) is called.

Kieran