On 03/12/2013 10:22 PM, Jon Schipp wrote:
Earlier, I was looking for an ICMP checksum definition but noticed that it isn't in there. https://github.com/borkmann/netsniff-ng/blob/master/configs/stddef.h
Done.
I imagine that this is because it's not a static value and there's not a possible way of doing it unless the default Linux and Windows payload values are used in stddef.h. I was trying to think of a way so I could add it but couldn't come up with anything. I may just try and add the OS defaults for an ICMP Echo request. I believe they use the same string each time. if there isn't a better way? Thoughts? Anyways, using csumip() works because the calculation is the same, you just have to make the ending offset included the ICMP header and data too. e.g. /* ICMP Checksum (Same as IP, end includes ICMP bytes) */ csumip(14, 48),
I've added this by today into the code. csumicmp aliases now to csumip in the lexer script.
^Offset 14 (begin IP header) + 20 (end IP header) + 14 ICMP bytes (including ICMP header) = 48 data bytes for checksum calculation
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