Ethereal-users: Re: [Ethereal-users] H225-SETUP

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From: "Martin Regner" <martin.regner@xxxxxxxxx>
Date: Wed, 4 Feb 2004 08:00:07 +0100
Guy Harris wrote:
> On Feb 3, 2004, at 5:23 PM, Jonty Ray wrote:
>
> > here is the file i am trying to see the setup in ...Eth Version
> > 0.10.0...
> >
> >  After uncheking the H225 reassembly no luck...same result it this was
> > checked..
>
> The "Malformed Frame"s might really be malformed...
>
> ...or there might be a bug in the H.225 dissector.  It produces a bunch
> of
>
> Not decoded yet in packet : N  [unknown choice extension]
> Not decoded yet in packet : N  [10.9.3.8.1]
> Not decoded yet in packet : N  [unknown sequence extension]
>
> errors for a number of packets, at least some of which are the ones
> reported as malformed.
>

I made a quick look at some of the V76 stuff in packet-h245.c and compared
with the ASN.1 specification for
H.245 version 9 at Packetizer, but I couldn't find any abvious mistakes in
packet-h245.c.
http://www.packetizer.com/iptel/h245/h245_asn.html

But of course I may have missed something,

Do you know what version of the H.245 specification the implementation is
based on?
Could it be that some stuff is later than the version 9 specificion?

I will try to run the packets through some other tool I have later this week
and compare the results I get.

Below is an extract for from the ASN.1 specification :

=======================================

V76LogicalChannelParameters ::= SEQUENCE {
  hdlcParameters  V76HDLCParameters,
  suspendResume
    CHOICE {noSuspendResume         NULL,
            suspendResumewAddress   NULL,
            suspendResumewoAddress  NULL,
            ...},
  uIH             BOOLEAN,
  mode
    CHOICE {eRM
              SEQUENCE {windowSize  INTEGER(1..127),
                        recovery
                          CHOICE {rej    NULL,
                                  sREJ   NULL,
                                  mSREJ  NULL,
                                  ...},
                        ...},
            uNERM  NULL,
            ...},
  v75Parameters   V75Parameters,
  ...}


V76HDLCParameters ::= SEQUENCE {
  crcLength              CRCLength,
  n401                   INTEGER(1..4095),
  loopbackTestProcedure  BOOLEAN,
  ...}

CRCLength ::= CHOICE {crc8bit   NULL,
                      crc16bit  NULL,
                      crc32bit  NULL,
                      ...}

======================================