Wireshark mailing list archives
Re: Byte ordering for dissectors
From: Guy Harris <guy () alum mit edu>
Date: Fri, 10 Jan 2014 12:04:11 -0800
On Jan 10, 2014, at 11:21 AM, Jakub Zawadzki <darkjames-ws () darkjames pl> wrote:
In packet-nflog.c I'm trying to guess endianess (nflog_tvb_byte_order())
Sadly, nflog doesn't have a fixed amount of fixed-format data that is in host byte order, with everything else in a standard byte order, so guessing the byte endianness is the best you can do. Guessing the byte endianness requires at least one field where the maximum value requires fewer bits than the field size, so that some bits are guaranteed to be zero, and where at least one of those bytes is guaranteed to be *non-zero* in a byte-swapped version of a valid value. For example, a value that won't be > 65535, in a 4-byte field that's never zero, would be sufficient. If there is no such field, and there's a fixed amount of fixed-format data in host byte order, you need to do the byte-swap-on-read that libpcap and libwiretap do. ___________________________________________________________________________ Sent via: Wireshark-dev mailing list <wireshark-dev () wireshark org> Archives: http://www.wireshark.org/lists/wireshark-dev Unsubscribe: https://wireshark.org/mailman/options/wireshark-dev mailto:wireshark-dev-request () wireshark org?subject=unsubscribe
Current thread:
- Byte ordering for dissectors Michal Labedzki (Jan 10)
- Re: Byte ordering for dissectors Evan Huus (Jan 10)
- Re: Byte ordering for dissectors Evan Huus (Jan 10)
- Re: Byte ordering for dissectors Jakub Zawadzki (Jan 10)
- Re: Byte ordering for dissectors Evan Huus (Jan 10)
- Re: Byte ordering for dissectors Guy Harris (Jan 10)
- Re: Byte ordering for dissectors Guy Harris (Jan 10)
- Re: Byte ordering for dissectors Evan Huus (Jan 10)
- Re: Byte ordering for dissectors Guy Harris (Jan 10)
- Re: Byte ordering for dissectors Evan Huus (Jan 10)