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

Submitter:  Simon Goldschmidt <goldsimon>
Submitted:  Sun 01 Nov 2009 05:20:41 PM UTC
   
 
Category:  TCP Severity:  3 - Normal
Item Group:  Change Request Status:  Fixed
Privacy:  Public Assigned to:  goldsimon
Open/Closed:  Closed Planned 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>
Group administrator
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>
Group administrator
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>
Group Member
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>
Group administrator

 

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    Follow 4 latest changes.

    Date Changed by Updated Field Previous Value => Replaced by
    2009-11-22 goldsimon Open/ClosedOpen Closed
        Assigned toNone goldsimon
        StatusNeed Info Fixed
    2009-11-01 goldsimon SummaryFIN isn\'t combined with data sent FIN isn't combined with data on unsent

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