Re: [lwip-users] Sequence bug in core/tcp.c

[Valery Ushakov]

Joe Gorse <address@hidden> wrote:

> Around line 524 of core/tcp.c, in tcp_listen_with_backlog(struct tcp_pcb
> *pcb, u8_t backlog):
> 
>  LWIP_ERROR("tcp_listen: pcb already connected", pcb->state == CLOSED,
> return NULL);
> 
>  /* already listening? */
>  if (pcb->state == LISTEN) {
>    return pcb;
>  }
> 
> A pcb->state == LISTEN never makes it past the LWIP_ERROR. Put the check
> for the LISTEN state above the LWIP_ERROR.
> 
> I am surprised anyone gets tcp_listen() to work at all for the raw
> API with this bug.

You are not supposed to call tcp_listen twice on the same pcb, so
everyone "get it to work at all" by not doing that :)

-uwe