http://bugs.wireshark.org/bugzilla/show_bug.cgi?id=2241
Summary: L2CAP dissector doesn't understand retransmission mode
Product: Wireshark
Version: SVN
Platform: PC
OS/Version: Windows XP
Status: NEW
Severity: Major
Priority: Low
Component: Wireshark
AssignedTo: wireshark-bugs@xxxxxxxxxxxxx
ReportedBy: shane.kearns@xxxxxxxxxxx
Depends on: 2237,2239
Created an attachment (id=1432)
--> (http://bugs.wireshark.org/bugzilla/attachment.cgi?id=1432)
test case
Build Information:
wireshark 0.99.8-btsnoop-dev (SVN Rev 24241)
Copyright 1998-2008 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+ 2.12.6, with GLib 2.14.5, with WinPcap (version unknown),
with libz 1.2.3, with libpcre 6.4, with SMI 0.4.5, with ADNS, with Lua 5.1,
with
GnuTLS 1.6.1, with Gcrypt 1.2.3, with MIT Kerberos, with PortAudio PortAudio
V19-devel, with AirPcap.
Running on Windows XP Service Pack 2, build 2600, with WinPcap version 4.0.1
(packet.dll version 4.0.0.901), based on libpcap version 0.9.5, without
AirPcap.
Built using Microsoft Visual C++ 6.0
Press any key to exit
--
The L2CAP dissector assumes all packets on a connection oriented channel are
B-frames (basic mode, or v1.1 backwards compatibility).
Retransmission mode or flow control mode (introduced in v1.2 bluetooth spec)
use I-frames and S-frames, which are described in the current 2.1 spec here:
Volume 3 (core, host volume) - Part A (L2CAP) - 3.3 (CONNECTION-ORIENTED
CHANNEL IN RETRANSMISSION/FLOW CONTROL MODES)
Whether a given channel is using basic mode, retransmission mode or flow
control mode depends on the outcome of the configuration request/response
transaction. Note that it is possible for a different mode to be configured
for the receive and transmit direction.
The fix for bug 2239 is required in order to parse the configuration options
for retransmission mode at all.
The negotiated configuration needs to be stored somewhere (the
l2cap_psm_dissector_table?) and checked when decoding data packets. Where
duplicate packets are present at the L2CAP level (due to retransmissions), only
one should be passed up to the higher layer protocol.
The impact of this bug is that higher level protocols (currently SDP&RFCOMM)
will not be decodable when using retransmission or flow control modes.
Attached test case is a BTSNOOP file for sending a photo between two devices
which support retransmission mode. Opening this file requires bug 2237 patch
to be applied.
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