On Apr 7, 2009, at 4:20 PM, siri m wrote: > I have few questions with regards to eliminating the duplicate > fragments for a plugin written on top of UDP. > > Q1: I would like to know how we can obtain UDP CRC from within the > custom plugin written on top of UDP? I tried to get the checksum by > providing a negative offset(-2) to tvb_get_ntohs(tvb, offset), but > that doesn't work. Is there any other way to obtain the UDP CRC from > within my plugin?
No, there isn't. On the other hand, if you can't detect duplicate fragments any other way (as per my previous mail, presumably the process that's receiving the fragments has to be able to detect them), you could compute some form of hash yourself (UDP checksum - I wouldn't call it a "CRC" as it's not a cyclic redundancy check - MD5 hash, etc.) on the data plus the source and destination addresses and port numbers (which *are* available as pinfo->src, pinfo->dst, pinfo->srcport, and pinfo- >dstport) and use *that* to detect duplicates. (I don't know whether an Internet checksum would be sufficiently strong to avoid having too many "false positives" for duplicates.) ___________________________________________________________________________ Sent via: Wireshark-dev mailing list <[email protected]> Archives: http://www.wireshark.org/lists/wireshark-dev Unsubscribe: https://wireshark.org/mailman/options/wireshark-dev mailto:[email protected]?subject=unsubscribe
