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Wireshark-users: Re: [Wireshark-users] MMS decoding problem

From: Sam Roberts <vieuxtech@xxxxxxxxx>
Date: Sat, 7 Jan 2012 13:32:11 -0800
On Fri, Jan 6, 2012 at 7:27 AM, Salman Malik <salmanmk@xxxxxxxx> wrote:
> I know this is not directly related to wireshark but I expect that most of
> you will be able to help me on this one. I am using asn1c Compiler to decode
> MMS protocol (transported over TPKT, COTP,Session, Presentation, ACSE
> layers). The problem that I am having is the asn1c compiler complains of
> unexpected tag when I decode the MMS layer packets. I suspect that this is

Which tag, in which message?

Its sounds more like a context dependent tag (tags are just numbers
defining data types, but there are standard ones, app dependent ones,
and context dependent ones), nothing to do with context from the
wrapping protocols. Is it possible you didn't find all the reference
ASN and feed it to your asn compiler? Maybe you can find an ASN.1
verifier, that can tell you whether you provided all referenced ASN
types and definitions?

I've never used an ASN.1 compiler, we always hand encode and decoded
messages for code space efficiency reasons.

Cheers,
Sam