Re: [lwip-users] Releasing pcb after tcp_new()

[Jonathan Larmour]

Bill Auerbach wrote:
> In code fragments, I'm using:
>
>         pcb = tcp_new();
>         tcp_bind(pcb, ipAddr, port );
>         pcb = tcp_listen( pcb );
>         LWIP_ASSERT( " NULL pcb", pcb != NULL );
>         tcp_accept(pcb, accept_handler );
>
> The accept_handler does:
>
>         tcp_arg( pcb, an_arg );
>         tcp_sent( pcb, sent_handler );
>         tcp_recv( pcb, receive_handler );
>         tcp_poll( pcb, poll_handler, 4 );
>         tcp_err( pcb, error_handler );
>
> When the sent_handler has no more data to send, it closes the pcb and reruns
> the bind/listen code above to bind and listen to the port (80).  This way
> I'm always waiting for an HTTP requests and can send a status page back.

If that's what you want, then don't call tcp_new/tcp_new/tcp_listen again! 
That listening socket still exists. The pcb passed into the accept_handler 
 is not the listening PCB. It's a newly created pcb for the newly 
established connection.

If you really want to close the listening PCB then you have to store its 
value somewhere and then explicitly close it. But if you do that, there 
will be a brief window when you are no longer listening.

Jifl
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