[Haskell-cafe] Re: sendfile leaking descriptors on Linux?

[Brandon S. Allbery KF8NH]

On Mar 25, 2010, at 15:03 , Bardur Arantsson wrote:
> On 2010-02-24 20:50, Brandon S. Allbery KF8NH wrote:
>> tcpdump 'host ps3 and tcp[tcpflags] & 0x27 != 0'
>
> The only striking thing I can see about the dump is that there are  
> 22 (conspicuously close to 16) sequences like:
>
> 19:45:30.135291 IP 192.168.0.115.64931 > gwendolyn.9000: Flags [R],  
> seq 2112225068, win 0, length 0
> 19:45:30.135295 IP 192.168.0.115.64931 > gwendolyn.9000: Flags [R],  
> seq 2112225068, win 0, length 0
> 19:45:30.135299 IP 192.168.0.115.64931 > gwendolyn.9000: Flags [R],  
> seq 2112225068, win 0, length 0
> 19:45:30.135302 IP 192.168.0.115.64931 > gwendolyn.9000: Flags [R],  
> seq 2112225068, win 0, length 0

The above is a single socket:  the source and destination ports are  
the same for all 4 traces.

More useful, from the dump, is:

> 19:44:41.774161 IP 192.168.0.115.65265 > gwendolyn.9000: Flags [F.],  
> seq 231, ack 1073301, win 41124, options [nop,nop,TS val 0 ecr  
> 95041042], length 0


which is where the PS/3 sent a FIN telling gwendolyn to close the  
socket.  It then follows that with a bunch of RST packets, the first  
of which is in sequence with the above FIN (suggesting the PS/3  
responded to the continued attempt to send by dropping the socket on  
the floor instead of by resending the FIN) and the rest are "this port  
is closed" RSTs, presumably due to 22 attempts to continue sending  
data.  This is somewhat poor on the part of the PS/3, but  
understandable given that it's essentially an embedded device.

It would be interesting to see what the data around there was, but  
that's not easy to do without recording all of it.

-- 
brandon s. allbery [solaris,freebsd,perl,pugs,haskell] allbery at kf8nh.com
system administrator [openafs,heimdal,too many hats] allbery at ece.cmu.edu
electrical and computer engineering, carnegie mellon university    KF8NH


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