Size of 802.11 packet

Question

Given the below declaration for pcap callback:

void my_callback(u_char *args, const struct pcap_pkthdr *header, const u_char *packet)

How to ascertain the total number of bytes present in the packet? I need that value so that I can pass it to crc32() function.

Maybe the `const struct pcap_pkthdr *header` has the information you need? — YePhIcK, Jul 17 '12 at 11:51

score 3 · Accepted Answer · answered Jul 17 '12 at 11:52

3

according to this reference the information about the size of the packet is in the pcap_pkthdr's structure

answered Jul 17 '12 at 11:52

YePhIcK

score 0 · Answer 2 · answered Jan 11 '16 at 15:04

The information is in the pcap_pkthdr variable.

Given your callback, the full packet size is given by

header->len

and the captured packet size (which might be smaller if you've set a snaplen that happens to be smaller than actual packet size) is given by

header->caplen

2 Answers2