Re: [lwip-users] Timeout in LAST-ACK state

[Mitani Hiroshi]

Hi Leon,

I observed lwip stalling at passive-close. TCP state was LAST-ACK.
Maybe ack-packet was lost. It is not so often, but possible.
I want lwip to close connection after 2MSL timer expired.

Here is a patch(just cut&paste from other timeouts).

*** tcp.c.orig  Tue Dec 20 09:40:52 2005
--- tcp.c       Tue Dec 20 09:43:55 2005
***************
*** 561,566 ****
--- 561,573 ----
        }
      }

+     /* Check if this PCB has stayed too long in LAST-ACK */
+     if (pcb->state == LAST_ACK) {
+       if ((u32_t)(tcp_ticks - pcb->tmr) > 2 * TCP_MSL / TCP_SLOW_INTERVAL) {
+         ++pcb_remove;
+         LWIP_DEBUGF(TCP_DEBUG, ("tcp_slowtmr: removing pcb stuck in 
LAST-ACK\n"));
+       }
+     }

      /* If the PCB should be removed, do it. */
      if (pcb_remove) {

Is this meaningless?

Leon Woestenberg wrote:
> Hello Mitrani Hiroshi,
> 
> Mitani Hiroshi wrote:
> 
>>Hi,
>>
>>In 1.1.0, the lwip waits ack forever in LAST-ACK state.
>>Isn't 2-MSL timer necessary to move to CLOSE state?
>>  
>>
> Please explain more thoroughly what is the problem and what is the fix?
> (Sorry, my knowledge of TCP is not in-detail).
> 
> Regards,
> 
> Leon.
> 
> 
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