Wireshark-bugs: [Wireshark-bugs] [Bug 3630] New: IPv6 Router Advertisement flags and lifetime ar
https://bugs.wireshark.org/bugzilla/show_bug.cgi?id=3630
Summary: IPv6 Router Advertisement flags and lifetime are mis-
parsed
Product: Wireshark
Version: 1.2.0
Platform: Other
OS/Version: All
Status: NEW
Severity: Major
Priority: Low
Component: Wireshark
AssignedTo: wireshark-bugs@xxxxxxxxxxxxx
ReportedBy: derekmorr@xxxxxxx
Created an attachment (id=3226)
--> (https://bugs.wireshark.org/bugzilla/attachment.cgi?id=3226)
ICMPv6 capture with O flag set to off.
Build Information:
Version 1.2.0 (SVN Rev 28753)
Copyright 1998-2009 Gerald Combs <gerald@xxxxxxxxxxxxx> 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 with GTK+ 2.12.9, with GLib 2.16.3, with libpcap 0.9.5, with libz
1.2.3, without POSIX capabilities, with libpcre 7.8, with SMI 0.4.8, without
c-ares, without ADNS, without Lua, with GnuTLS 2.6.2, with Gcrypt 1.4.3, with
MIT Kerberos, without GeoIP, with PortAudio V19-devel (built Nov 14 2008),
without AirPcap.
Running on Darwin 9.7.0, with libpcap version 0.9.5, GnuTLS 2.6.2, Gcrypt
1.4.3.
Built using gcc 4.0.1 (Apple Inc. build 5488).
--
WireShark 1.2.0 uses the wrong offsets to parse the Router Advertisement (RA)
flags and lifetime fields. This is a regression against 1.0.x, which displays
the correct values.
For example, on one of my LANs, my RAs do not have the O flag set, yet
WireShark 1.2.0 says that it is set.
This bug appears to have been introduced in SVN Rev 27967 in
epan/dissectors/packet-icmpv6, lines 1868-1870, which define byte offsets into
the ICMPv6 packet for various fields. It looks like ND_RA_FLAGS_RESERVED_OFFSET
should be 5 rather than 4, and ND_RA_ROUTER_LIFETIME_OFFSET should be 6. As a
result, WS 1.2.0 is using the hop limit for the flags field.
I've attached a sample capture showing several RAs. The router is not setting
the O flag. WS 1.0.8 correctly displays this. WS 1.2.0 does not. WS 1.2.0 uses
byte 0x3A for flags; it should use byte 0x3B. It uses bytes 0x3B and 0x3C for
the router lifetime; it should use bytes 0x3C and 0x3D.
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