The Wireshark routine is based on the BSD in-kernel portable checksum
routine (thus BSD-licensed); it takes a vector of pointers and lengths
and checksums the concatenation of the buffers in question (just as the
BSD in-kernel routine checksums a chain of mbufs).
This simplifies the "with a pseudo-header" checksums; hopefully it'll
fix up the problems being seen on some big-endian platforms, which might
be due to hand-calculating some or all of the checksum and doing so
incorrectly. It also gets rid of some code that might be dereferencing
unaligned pointers.
Use the EXTRACT_ macros to extract multi-byte integral values from
packets, rather than just dereferencing pointers into the packet; there
is no guarantee that the packet data will be aligned on the right
boundary, and there is no guarantee that, if they're not, a direct
access will work correctly.
add support for variable-length checksum in DCCP, as per section 9 of RFC 4340.
remove duplicated code in dccp6_cksum (which just repeated the code of in_cksum
fix a bug in dccp.h -- the fields of CCVAL and CSCOV were swapped (see section 5.1 of RFC 4340)
fix a typo in the display of incorrect checksums
old output `cksum xDEAD (incorrect (-> xBEEF)',
new output `cksum xDEAD (incorrect -> xBEEF)'
variables in the middle of the block., and #if out dccp_hdr_data()
(which is unused, and defined in such a fashion that it doesn't work on
MSVC++, with the structure name and the function name the same).
