buglwIP - A Lightweight TCP/IP stack - Bugs: bug #27905, FIN isn't combined with data on...

 
 

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bug #27905: FIN isn't combined with data on unsent

Submitted by:  Simon Goldschmidt <goldsimon>
Submitted on:  Sun 01 Nov 2009 05:20:41 PM UTC  
 
Category: TCPSeverity: 3 - Normal
Item Group: Change RequestStatus: Fixed
Privacy: PublicAssigned to: Simon Goldschmidt <goldsimon>
Open/Closed: ClosedPlanned Release: None
lwIP version: CVS Head

Sun 22 Nov 2009 05:58:58 PM UTC, comment #3:

Fixed since the code change is rather small and the code size doesn't change much, too.

Simon Goldschmidt <goldsimon>
Project AdministratorIn charge of this item.
Mon 02 Nov 2009 10:33:53 AM UTC, comment #2:

I spotted this while working on the raw api httpd: with HTTP/1.1, the server currently sends "Connection: close" because it closes the connection after each request/response. However, since the actual FIN needs a while, it happens often that the FINs are sent at the same time, resulting in duplicate FINs and ACKs.

This is of course not really wrong behaviour, but it would be nicer to prevent duplicate ACKs if we can. I'll test how much code change it would be...

Simon Goldschmidt <goldsimon>
Project AdministratorIn charge of this item.
Mon 02 Nov 2009 09:10:46 AM UTC, comment #1:

It was probably just simpler that way. I don't think this is a big deal. Whichever results in smaller code is best.

Kieran Mansley <kieranm>
Project Administrator
Sun 01 Nov 2009 05:20:41 PM UTC, original submission:

In tcp_enqueue, we currently don't combine FIN segments to the last unsent. Does anybody know why? I would have thought that this would be a good idea to keep the number of segments sent low.

I.e. the httpd closes a connection right after all data is enqueued successfully. Although the enqueued segments are still on unsent (tcp_output hasn't been called, yet), FIN always results in a new segment.

Simon Goldschmidt <goldsimon>
Project AdministratorIn charge of this item.

 

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  • -unavailable- added by kieranm (Posted a comment)
  • -unavailable- added by goldsimon (Submitted the item)
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    Follow 4 latest changes.

    Date Changed By Updated Field Previous Value => Replaced By
    Sun 22 Nov 2009 05:58:58 PM UTCgoldsimonOpen/ClosedOpen=>Closed
      Assigned toNone=>goldsimon
      StatusNeed Info=>Fixed
    Sun 01 Nov 2009 05:33:00 PM UTCgoldsimonSummaryFIN isn\'t combined with data sent=>FIN isn't combined with data on unsent

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