[PATCH]: [DCCP]: support for variable-length checksums

[Gerrit Renker <gerrit () erg abdn ac uk>]

This introduces support for variable-length checksum in 
DCCP, as it is specified in section 9 of RFC 4340. 

Previously tcpdump was only able to validate full-coverage
checksums, this patch verifies checksums in accordance with
the CsCov header field (sec. 5.3). 

The patch has been tested and verified on DCCPv4 and DCCPv6
connections, checksums were manually validated, and traces
can be supplied.  



In addition, the patch also
        * removes reduplicated code in dccp6_cksum (which 
          just repeated the code of in_cksum)
        * fixes a bug in dccp.h -- the fields of CCVAL and
          CSCOV were swapped (cf. section 5.1 of RFC 4340)
        * fixes a typo in the display of incorrect checksums
          (these were printed as `cksum xDEAD (incorrect (->  xBEEF)',
           it now will print  `cksum xDEAD (incorrect -> xBEEF)'

I would like to see this merged as a Linux kernel patch already
exists for DCCP partial checksum coverage support.

Regards
Gerrit Renker


 dccp.h       |    4 ++--
 print-dccp.c |   34 ++++++++++++++++------------------
 2 files changed, 18 insertions(+), 20 deletions(-)

Attachment: tcpdump-partial-csum.patch
Description:

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