Wireshark mailing list archives
Re: how to extract "IP.len" (IP_total length) to my local variable in my dissector?
From: Jaap Keuter <jaap.keuter () xs4all nl>
Date: Fri, 24 Jun 2011 09:33:15 +0200
On 06/24/2011 09:13 AM, John x wrote:
Hi, folks, I am developing a dissector, my tasks are: 1. to get the “ip.len” (the total length in IP header), 2. using the ip.len to know how long the packet would be and extract the last byte to my local variable. *Could you guys please tell me how to get the IP’s total length from IP header? * *How to extract the last byte of my packet? * Any suggestions or advices would be appreciated. Thanks for your help John
So your dissector sits on top of the IP dissector. It gets a TVB (Testy, Virtual Buffer) with the IP packet data. Then you can use all the wonderful functions in epan/tvbuff.h to get access to that (meta-)data. Like tvb_length() and tvb_reported_length(). Two things: Never go into the TVB data directly, always find the proper access function. Be aware that captured packets can be cut short, so the length you have (tvb_length) might be smaller than the original (tvb_reported_length). Thanks, Jaap ___________________________________________________________________________ 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:
- how to extract "IP.len" (IP_total length) to my local variable in my dissector? John x (Jun 24)
- Re: how to extract "IP.len" (IP_total length) to my local variable in my dissector? Jaap Keuter (Jun 24)
- Re: how to extract "IP.len" (IP_total length) to my local variable in my dissector? John x (Jun 24)
- Re: how to extract "IP.len" (IP_total length) to my local variable in my dissector? Guy Harris (Jun 24)
- Re: how to extract "IP.len" (IP_total length) to my local variable in my dissector? John x (Jun 24)
- Re: how to extract "IP.len" (IP_total length) to my local variable in my dissector? Guy Harris (Jun 24)
- Re: how to extract "IP.len" (IP_total length) to my local variable in my dissector? John x (Jun 24)
- Re: how to extract "IP.len" (IP_total length) to my local variable in my dissector? John x (Jun 24)
- Re: how to extract "IP.len" (IP_total length) to my local variable in my dissector? Jaap Keuter (Jun 24)