Wireshark-bugs: [Wireshark-bugs] [Bug 11207] OpenFlow Match Experimenter Field uses supplied len
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From: bugzilla-daemon@xxxxxxxxxxxxx
Date: Mon, 18 May 2015 21:56:50 +0000

Comment # 1 on bug 11207 from 
I quoted the wrong sections of the OF spec and am now doubting whether this is
an issue with Wireshark or Ryu. It does look like the Length specifies the
length of the payload, but not the header, after all. However, the first four
bytes of the payload is the Experimenter ID, suggesting that the Length should
at least include those 4 bytes. The specification does say (7.2.3.2) that the
entire OXM field length (TLV) is the Length specified plus 4 bytes for any OXM
field, not just Experimenter fields:

"oxm_length is a positive integer describing the length of the OXM TLV payload
in bytes. The length of the OXM TLV, including the header, is exactly 4 +
oxm_length bytes."

In this case, the parsed values are still incorrect as the dissector assumes
the Length does not include the Experimenter ID and instead pulls Length bytes
after the Experimenter ID instead of (Length - 4).

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