[lwip-users] lwip recv callback questions

[Mike He]

Hello,

I am a new user to lwip with some questions on behavior of the callback 
function that receives data, i.e. the one specified by calling tcp_recv. 
I have tried looking on the wiki but was not able to find answers to my 
question specifically.

1. What do the different error codes that the recv callback can return 
mean, and how does lwip respond to them? For example, in my code I 
return ERR_ARG for a malformed request, but lwip repeatedly calls my 
callback with the same packet, seemingly forever. If I return ERR_OK, 
then the callback is only called once. On the Wiki, it seems to indicate 
that my callback should only be called a limited number of times if 
there is an error. (http://lwip.wikia.com/wiki/Raw/native_API). More 
generally, an explanation of when to use each ERR return and how to 
expect lwip to respond would be greatly appreciated.

2. pbuf_free(p) should be called on received packet only when we are 
happy with it and return ERR_OK, right?

3. Are we supposed to call tcp_accepted? The wiki states that it should 
be called from the tcp_accept callback to indicate that the connection 
is accepted, but I am working from example code provided by Texas 
Instruments using lwip, and they do not call the function anywhere. Is 
this a mistake on their part?

Thanks,
Mike