1 /*
2 * ip6.c
3 *
4 * Copyright (c) 2002 Dug Song <dugsong@monkey.org>
5 *
6 * $Id$
7 */
8
9 #include "config.h"
10
11 #include "dnet.h"
12
13 #define IP6_IS_EXT(n) \
14 ((n) == IP_PROTO_HOPOPTS || (n) == IP_PROTO_DSTOPTS || \
15 (n) == IP_PROTO_ROUTING || (n) == IP_PROTO_FRAGMENT)
16
17 void
ip6_checksum(void * buf,size_t len)18 ip6_checksum(void *buf, size_t len)
19 {
20 struct ip6_hdr *ip6 = (struct ip6_hdr *)buf;
21 struct ip6_ext_hdr *ext;
22 u_char *p, nxt;
23 int i, sum;
24
25 nxt = ip6->ip6_nxt;
26
27 for (i = IP6_HDR_LEN; IP6_IS_EXT(nxt); i += (ext->ext_len + 1) << 3) {
28 if (i >= (int)len) return;
29 ext = (struct ip6_ext_hdr *)((u_char *)buf + i);
30 nxt = ext->ext_nxt;
31 }
32 p = (u_char *)buf + i;
33 len -= i;
34
35 if (nxt == IP_PROTO_TCP) {
36 struct tcp_hdr *tcp = (struct tcp_hdr *)p;
37
38 if (len >= TCP_HDR_LEN) {
39 tcp->th_sum = 0;
40 sum = ip_cksum_add(tcp, len, 0) + htons(nxt + len);
41 sum = ip_cksum_add(&ip6->ip6_src, 32, sum);
42 tcp->th_sum = ip_cksum_carry(sum);
43 }
44 } else if (nxt == IP_PROTO_UDP) {
45 struct udp_hdr *udp = (struct udp_hdr *)p;
46
47 if (len >= UDP_HDR_LEN) {
48 udp->uh_sum = 0;
49 sum = ip_cksum_add(udp, len, 0) + htons(nxt + len);
50 sum = ip_cksum_add(&ip6->ip6_src, 32, sum);
51 if ((udp->uh_sum = ip_cksum_carry(sum)) == 0)
52 udp->uh_sum = 0xffff;
53 }
54 } else if (nxt == IP_PROTO_ICMPV6) {
55 struct icmp_hdr *icmp = (struct icmp_hdr *)p;
56
57 if (len >= ICMP_HDR_LEN) {
58 icmp->icmp_cksum = 0;
59 sum = ip_cksum_add(icmp, len, 0) + htons(nxt + len);
60 sum = ip_cksum_add(&ip6->ip6_src, 32, sum);
61 icmp->icmp_cksum = ip_cksum_carry(sum);
62 }
63 } else if (nxt == IP_PROTO_ICMP || nxt == IP_PROTO_IGMP) {
64 struct icmp_hdr *icmp = (struct icmp_hdr *)p;
65
66 if (len >= ICMP_HDR_LEN) {
67 icmp->icmp_cksum = 0;
68 sum = ip_cksum_add(icmp, len, 0);
69 icmp->icmp_cksum = ip_cksum_carry(sum);
70 }
71 }
72 }
73