Wireshark-bugs: [Wireshark-bugs] [Bug 1136] New: TCP checksum validation

From: bugzilla-daemon@xxxxxxxxxxxxx
Date: Sun, 1 Oct 2006 09:56:07 +0000 (GMT)

http://bugs.wireshark.org/bugzilla/show_bug.cgi?id=1136

           Summary: TCP checksum validation
           Product: Wireshark
           Version: 0.99.3
          Platform: PC
        OS/Version: Windows XP
            Status: NEW
          Severity: Minor
          Priority: Low
         Component: Wireshark
        AssignedTo: wireshark-bugs@xxxxxxxxxxxxx
        ReportedBy: nishikawa.shun@xxxxxxxxxxxxxx


Build Information:
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Rireshark/Ethreal cannot checkout TCP checksum error.

When correct TCP checksum is 0x0000, and sender miss-caluculated
checksum as 0xffff, Wireshark show this packet as Checksum [correct].

In fact, TCP packet never has checksum=0xffff.
(In case UDP, if computed_cksum==0 then udp set cksum to 0xffff,
and cksum field zero means cksum disabled)

IMHO, epan/dissectors/packet-tcp.c should check `if (th_sum == 0xffff)' at
first.
Can somebody correct this. (I don't know about other protocol)


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