I'm using the pcap C library to read packets. Currently, I use the following to check and see whether a flag in the struct tcphdr
(this struct is defined in the netinet/tcp.h
library) is set:
struct tcphdr *tcp = ....
if(tcp->th_flags & TH_SYN) {
//SYN FLAG IS SET?
}
Will this always work for checking if a particular flag is set in the struct? Or is there a better way? Would greatly appreciate any advice/tips :)
That looks fine to me. TH_SYN
is a single bit, so that expression will be true (nonzero) if that bit is set in th_flags
.