Wireshark mailing list archives
Re: ASN.1 bit string alignment
From: "Neil Piercy" <Neil.Piercy () ipaccess com>
Date: Mon, 29 Mar 2010 13:14:14 +0100
Looking at the changes in packet-per.c, it looks like the changes were deliberate to remove leading pads and return a tvb which had trailing bits padded - which sounds reasonable to me: I suspect the tvb bit-offset code assumes no leading bit pads: correct? If so, it becomes just a display problem. Given that the bit string is of arbitrary length, and not necessarily interpreted as an integer, how would we _want_ the example below to be displayed? I think the basic problem is the attempt to display a bit string in hex - would it be better to display it in binary (if say <=32 bits) and have its (unpadded) integer value (hex or dec?) included too if small enough - e.g. dl-HFN: 0000000000000000000000100 (0x4) [bit length 25] Neil
-----Original Message----- From: wireshark-dev-bounces () wireshark org [mailto:wireshark-dev- bounces () wireshark org] On Behalf Of Anders Broman Sent: 26 March 2010 20:53 To: Developer support list for Wireshark Subject: Re: [Wireshark-dev] ASN.1 bit string alignment Looks like a bug, please make a bug report and attach a sample trace. Regards Anders -----Original Message----- From: wireshark-dev-bounces () wireshark org [mailto:wireshark-dev- bounces () wireshark org] On Behalf Of Neil Piercy Sent: den 22 mars 2010 19:31 To: Developer support list for Wireshark Subject: [Wireshark-dev] ASN.1 bit string alignment In 1.0.x PER ASN.1 bit strings used to be padded in the MSBs, (e.g. extract from an RRC message): dl-HFN: 00000004 [bit length 25] Since 1.2.x they appear to be padded in the LSBs (e.g. the same extract): dl-HFN: 00000200 [bit length 25] The value carried in both cases above is meant to be 4. Is this a deliberate change? I know bit strings are of arbitrary length, therefore a "natural" representation is challenging, but I find the above counter-intuitive. Neil This message contains confidential information and may be privileged. If you are not the intended recipient, please notify the sender and delete the message immediately. ip.access Ltd, registration number 3400157, Building 2020, Cambourne Business Park, Cambourne, Cambridge CB23 6DW, United Kingdom
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Current thread:
- ASN.1 bit string alignment Neil Piercy (Mar 22)
- Re: ASN.1 bit string alignment Anders Broman (Mar 26)
- Re: ASN.1 bit string alignment Neil Piercy (Mar 29)
- Re: ASN.1 bit string alignment Anders Broman (Mar 26)