On May 5, 2013, at 3:49 PM, Stephen Donnelly <stephen.donne...@emulex.com> wrote:
> In 2007 in libpcap afbb1ce7 you committed some code (possibly from Florent > Drouin) adding the LT_FCS_DATALINK_EXT mechanism to record whether the > capture includes information about captured FCS length, and if so what length > it is. Yes, that was from a thread with the subject "Request for a new DLT for MTP2 with FCS" from 2007, in which Florent, you, and I were the participants. > I believe that currently only the DAG capture code supports this, and as > implemented the LT_FCS_LENGTH is in units of 16-bits, e.g. 16-bit FCS returns > 1, and 32-bit FCS returns 2? Units of bits won't work, as the field is only 4 bits long, so it can't even handle 16 bits. As units of 16 bits is already being used, we might as well go with it. > I don't think Wireshark's pcap wiretap code currently uses this mechanism to > check for FCS length, does it make sense to add it? Yes, it does. If you have libpcap 1.0 or later, you have pcap_datalink_ext(), so tcpdump could use it as well. _______________________________________________ tcpdump-workers mailing list tcpdump-workers@lists.tcpdump.org https://lists.sandelman.ca/mailman/listinfo/tcpdump-workers
