Wireshark mailing list archives

Re: [Wireshark-commits] rev 33048: /trunk/ /trunk/epan/dissectors/: packet-ber.c packet-pres.c /trunk/asn1/pres/: pres.cnf

From: Graeme Lunt <graeme () lunt uk com>
Date: Tue, 29 Jun 2010 15:11:29 +0100

Stig,

I have looked a both the captures and I think that they show problems with
their associated dissectors.

The patch added better/more rigorous handling of constructed ASN.1 types
that are IMPLICITLY tagged, and consequently you can get away with less.

In your capture file, the IMPLICIT CONTEXT [0] tag was marked as
constructed. The Wireshark ASN.1 file expected to decode this as OCTET
STRING:

ISO8823-PRESENTATION.asn:
CHOICE {single-ASN1-type   [0] IMPLICIT OCTET STRING,

So wireshark expects to find a constructed OCTET STRING - but it doesn't
find an internal OCTET STRING tag and so you see the error in wireshark you
do.

However, I believe this is because ISO8823-PRESENTATION.asn should say:

CHOICE {single-ASN1-type   [0] ANY,

This much better aligns with the original ASN.1.

The ANY you provided in your example capture was indeed constructed.

Attached is a simple patch. If you concur, then I will apply it.

As for Jeff's problem, I suspect it is something similar, but I will have to
do a bit more digging yet as I am not as familiar with that protocol.

Graeme






2010/6/29 Stig Bjørlykke <stig () bjorlykke org>

2010/6/29 Stig Bjørlykke <stig () bjorlykke org>:

I'm also having problem with this patch.  Have a look at this packet
which is marked as "[Unreassembled Packet]", while it used to display
fine with a "single-ASN1-type" in PRES.


Ok, and now with the example packet.


--
Stig Bjørlykke

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Current thread:

Re: [Wireshark-commits] rev 33048: /trunk/ /trunk/epan/dissectors/: packet-ber.c packet-pres.c /trunk/asn1/pres/: pres.cnf Jeff Morriss (Jun 08)
- Re: [Wireshark-commits] rev 33048: /trunk/ /trunk/epan/dissectors/: packet-ber.c packet-pres.c /trunk/asn1/pres/: pres.cnf Stig Bjørlykke (Jun 29)
  - Re: [Wireshark-commits] rev 33048: /trunk/ /trunk/epan/dissectors/: packet-ber.c packet-pres.c /trunk/asn1/pres/: pres.cnf Stig Bjørlykke (Jun 29)
    - Re: [Wireshark-commits] rev 33048: /trunk/ /trunk/epan/dissectors/: packet-ber.c packet-pres.c /trunk/asn1/pres/: pres.cnf Graeme Lunt (Jun 29)
    - Re: [Wireshark-commits] rev 33048: /trunk/ /trunk/epan/dissectors/: packet-ber.c packet-pres.c /trunk/asn1/pres/: pres.cnf Graeme Lunt (Jun 29)
    - Re: [Wireshark-commits] rev 33048: /trunk/ /trunk/epan/dissectors/: packet-ber.c packet-pres.c /trunk/asn1/pres/: pres.cnf Stig Bjørlykke (Jun 29)
- Re: [Wireshark-commits] rev 33048: /trunk/ /trunk/epan/dissectors/: packet-ber.c packet-pres.c /trunk/asn1/pres/: pres.cnf Graeme Lunt (Jun 29)
  - Re: [Wireshark-commits] rev 33048: /trunk/ /trunk/epan/dissectors/: packet-ber.c packet-pres.c /trunk/asn1/pres/: pres.cnf Jeff Morriss (Jun 29)