Wireshark-bugs: [Wireshark-bugs] [Bug 10426] New: 6LoWPAN multicast address decompression proble
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From: bugzilla-daemon@xxxxxxxxxxxxx
Date: Wed, 27 Aug 2014 11:05:32 +0000
Bug ID 10426
Summary 6LoWPAN multicast address decompression problems
Product Wireshark
Version Git
Hardware All
OS All
Status UNCONFIRMED
Severity Major
Priority Low
Component Dissection engine (libwireshark)
Assignee bugzilla-admin@wireshark.org
Reporter kevin.bracey@arm.com 

Build Information:
Version 1.9.0-Gridmerge-47653 (SVNRev 47653 from /trunk)

Copyright 1998-2013 Gerald Combs <gerald@wireshark.org> and contributors.
This is free software; see the source for copying conditions. There is NO
warranty; not even for MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.

Compiled (32-bit) with GTK+ 2.24.14, with Cairo 1.10.2, with Pango 1.30.1, with
GLib 2.34.1, with WinPcap (4_1_2), with libz 1.2.5, without POSIX capabilities,
without libnl, with SMI 0.4.8, with c-ares 1.7.1, with Lua 5.1, without Python,
with GnuTLS 2.12.18, with Gcrypt 1.4.6, with MIT Kerberos, with GeoIP, with
PortAudio V19-devel (built Feb 14 2013), with AirPcap.

Running on 64-bit Windows 7 Service Pack 1, build 7601, with WinPcap version
4.1.2 (packet.dll version 4.1.0.2001), based on libpcap version 1.0 branch
1_0_rel0b (20091008), GnuTLS 2.12.18, Gcrypt 1.4.6, without AirPcap.
Intel(R) Core(TM) i7-4800MQ CPU @ 2.70GHz, with 16068MB of physical memory.
--
Wireshark does not decode 6LoWPAN IPHC stateful multicast addresses (section
3.2.4 of RFC 6282).

The problem was observed in 1.9.0, but checking the sources shows that the
error remains in the current Git tree.

The error comes from LOWPAN_IPHC_MCAST_STATEFUL_48BIT being incorrectly defined
as "1". It should be "0" - the DAM (Destination Address Mode) bits for this
compression are 00.

I think the error arises from earlier drafts, where this mode did have DAM=01.
It was changed in draft-ietf-6lowpan-hc-06, along with most of the other
multicast modes. (Although Figure 10 had an out-of-date "DAM = 01" all the way
up to draft-ietf-6lowpan-hc-13).

Also, for display of the DAM bits themselves, "lowpan_iphc_mcast_modes" is
missing an "Inline" entry, so it says "Destination address mode: Reserved
(0x0000)" for "M=1,DAC=0,DAM=00" (128-bit inline), despite otherwise decoding
correctly. And there should presumably be a separate
"lowpan_iphc_mcast_stateful_modes" table for "M=1,DAC=1", where DAM bits have
totally different meanings.

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