Wireshark-bugs: [Wireshark-bugs] [Bug 3654] New: ANSI ISUP Cause indicators with coding standard

Date: Fri, 3 Jul 2009 09:41:58 -0700 (PDT)
https://bugs.wireshark.org/bugzilla/show_bug.cgi?id=3654

           Summary: ANSI ISUP Cause indicators with coding standard=ANSI
                    fail to dissect.
           Product: Wireshark
           Version: 1.2.0
          Platform: Other
        OS/Version: All
            Status: NEW
          Severity: Normal
          Priority: Low
         Component: Wireshark
        AssignedTo: wireshark-bugs@xxxxxxxxxxxxx
        ReportedBy: mlashley@xxxxxxxxx


Created an attachment (id=3246)
 --> (https://bugs.wireshark.org/bugzilla/attachment.cgi?id=3246)
REL with ANSI coding standard (fails to decode)

Build Information:
aragorn ~ # wireshark -v
wireshark 1.2.0

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+ 2.14.7, with GLib 2.20.2, with libpcap 1.0.0, with libz
1.2.3, with POSIX capabilities (Linux), with libpcre 7.8, with SMI 0.4.8,
without c-ares, without ADNS, with Lua 5.1, without GnuTLS, without Gcrypt,
with
MIT Kerberos, without GeoIP, without PortAudio, without AirPcap.

Running on Linux 2.6.28-gentoo-r2, with libpcap version 1.0.0.

Built using gcc 4.3.3.

--
ISUP dissector - When decoding cause indicators parameter for ANSI - and the
coding standard is 0x2 (ANSI) and not 0x0 (CCITT) - the current code steps
forward an octet too far before extracting the cause value - causing the
dissector to fail.

In dissect_ansi_isup_cause_indicators_parameter()

The case 0: and case 2: can be seen to differ whereby the line that extracts
the cause value appears respectively before and after an offset++; length--.

In each case - the cause_value=tvb_get_guint8(parameter_tvb, offset)&0x7f;
should appear before offset++.

Attaching example packets (set MTP3 preference to ANSI) for the CCITT and ANSI
coding standard case - the latter fails to decode due to the above.


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