Re: [lwip-users] flow of lwip as a stream client

[address@hidden]

mat henshall wrote:
> I think you will also want to return ERR_MEM from your callback, if I 
> understand the code correctly, the stack will buffer the data for you 
> and then will try again on the next fasttmr will try delivering the 
> data again to your application.
>
> This way, when your circular buffer is full, the stack will buffer up 
> the data, and the server will stop sending data until you have cleared 
> your circular buffer and the window is updated.

That should be a fallback only, because until you accept that packet, 
all other packets received from the remote host (including possible 
retransmissions) will neither get ACKed nor buffered, which results in 
unnecessary traffic.

If you design your buffer size and TCP_WND correctly and call 
tcp_recved() when you actually process/free pbufs (not enqueue them in 
your buffer), there's no need to return ERR_MEM from the recv callback.

Simon