buglwIP - A Lightweight TCP/IP stack - Bugs: bug #1713, Out-of-sequence TCP segments...

 
 

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bug #1713: Out-of-sequence TCP segments should be timed out

Submitted by:  Adam Dunkels <adamdunkels>
Submitted on:  Fri 15 Nov 2002 09:37:25 AM UTC  
 
Category: TCPSeverity: 1 - Wish
Item Group: Faulty BehaviourStatus: None
Privacy: PublicAssigned to: None
Open/Closed: ClosedPlanned Release: None
lwIP version: None

Mon 26 Mar 2007 11:49:26 AM UTC, comment #2:

Closing, thanks for spotting this fix.

Kieran Mansley <kieranm>
Project Administrator
Fri 23 Mar 2007 02:43:52 PM UTC, comment #1:

Noticed that this bug is still in the list... but browsing the code, it appears that a patch has already been applied to address this (see below). Perhaps this bug just needs a status update and closed? (I didn't go back and browse the history to see when this was added... but it was in at least by 0.7.2 I think).

in tcp_slowtmr():
-----------------------------------------------------------

/* If this PCB has queued out of sequence data, but has been
inactive for too long, will drop the data (it will eventually
be retransmitted). */
#if TCP_QUEUE_OOSEQ
if (pcb->ooseq != NULL &&
(u32_t)tcp_ticks - pcb->tmr >=
pcb->rto * TCP_OOSEQ_TIMEOUT) {
tcp_segs_free(pcb->ooseq);
pcb->ooseq = NULL;
LWIP_DEBUGF(TCP_CWND_DEBUG, ("tcp_slowtmr: dropping OOSEQ queued data\n"))
}
#endif /* TCP_QUEUE_OOSEQ */

------------------------------------------------------------

Jim Pettinato <jim_pettinato>
Project Member
Fri 15 Nov 2002 09:37:25 AM UTC, original submission:

When TCP receives out-of-sequence segments, those are queued on the tcp_pcb. Those segments use up pbufs from the pbuf pool until in-sequence segments arrives to fill the gap. The problem is that when all pbufs from the pool are tied up in out-of-sequence queues, no new segments can be received.

The best way to deal with this is probably to add a timeout in tcp_slowtmr() which kills all out-of-sequence segments after four round-trip times (tcp_pcb->rto). During this time, new segments should have arrived.

Nothing will break when killing out-of-sequence segments, since they will eventually be retransmitted.

Adam Dunkels <adamdunkels>
Project Member

 

No files currently attached

 

Depends on the following items: None found

Items that depend on this one: None found

 

Carbon-Copy List
  • -unavailable- added by kieranm (Posted a comment)
  • -unavailable- added by jim_pettinato (Posted a comment)
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    Follow 3 latest changes.

    Date Changed By Updated Field Previous Value => Replaced By
    Mon 26 Mar 2007 11:49:26 AM UTCkieranmOpen/ClosedOpen=>Closed
    Wed 07 May 2003 08:47:12 PM UTClikewiseCategoryNone=>(Error - Not Found)
      Item GroupNone=>(Error - Not Found)

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