Date: Tue, 06 Aug 2002 15:55:42 +0430 From: "soheil h" <soheil_h_y@hotmail.com> To: freebsd-net@FreeBSD.ORG Message-ID: <F268jQ8vjqueolj8Jec0000d5e0@hotmail.com>
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Hi list
which of these cast is true for accessing the tcphdr outof the 'struct mbuf'
in the ip_input function of ip_input.c ?
struct mbuf m;
struct ip * ip = mtod(m, ip);
int iphlen;
struct tcpShdr* th; /* it is a copy of the tcphdr struct i made the
definition is type at the bottom*/
hlen = IP_VHL_HL(ip->ip_vhl) < 2;
1. th = (struct tcpShdr *)(ip + 1);
2. th = (struct tcpShdr *)((caddr_t)ip + hlen);
PLEASE HELP ME
I THINK THE SECOND ONE IS TRUE BUT IT DOESN' Work .
struct tcpShdr {
u_short th_sport; /* source port */
u_short th_dport; /* destination port */
tcpS_seq th_seq; /* sequence number */
tcpS_seq th_ack; /* acknowledgement number */
u_short th_soheil;
u_short th_win; /* window */
u_short th_sum; /* checksum */
u_short th_urp; /* urgent pointer */
};
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