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77 lines
1.8 KiB
C
77 lines
1.8 KiB
C
/*
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* ip6.c
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*
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* Copyright (c) 2002 Dug Song <dugsong@monkey.org>
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*
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* $Id: ip6.c 539 2005-01-23 07:36:54Z dugsong $
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*/
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#ifdef _WIN32
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#include "dnet_winconfig.h"
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#else
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#include "config.h"
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#endif
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#include "dnet.h"
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#define IP6_IS_EXT(n) \
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((n) == IP_PROTO_HOPOPTS || (n) == IP_PROTO_DSTOPTS || \
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(n) == IP_PROTO_ROUTING || (n) == IP_PROTO_FRAGMENT)
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void
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ip6_checksum(void *buf, size_t len)
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{
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struct ip6_hdr *ip6 = (struct ip6_hdr *)buf;
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struct ip6_ext_hdr *ext;
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u_char *p, nxt;
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int i, sum;
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nxt = ip6->ip6_nxt;
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for (i = IP6_HDR_LEN; IP6_IS_EXT(nxt); i += (ext->ext_len + 1) << 3) {
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if (i >= (int)len) return;
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ext = (struct ip6_ext_hdr *)((u_char *)buf + i);
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nxt = ext->ext_nxt;
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}
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p = (u_char *)buf + i;
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len -= i;
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if (nxt == IP_PROTO_TCP) {
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struct tcp_hdr *tcp = (struct tcp_hdr *)p;
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if (len >= TCP_HDR_LEN) {
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tcp->th_sum = 0;
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sum = ip_cksum_add(tcp, len, 0) + htons(nxt + (u_short)len);
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sum = ip_cksum_add(&ip6->ip6_src, 32, sum);
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tcp->th_sum = ip_cksum_carry(sum);
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}
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} else if (nxt == IP_PROTO_UDP) {
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struct udp_hdr *udp = (struct udp_hdr *)p;
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if (len >= UDP_HDR_LEN) {
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udp->uh_sum = 0;
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sum = ip_cksum_add(udp, len, 0) + htons(nxt + (u_short)len);
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sum = ip_cksum_add(&ip6->ip6_src, 32, sum);
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if ((udp->uh_sum = ip_cksum_carry(sum)) == 0)
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udp->uh_sum = 0xffff;
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}
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} else if (nxt == IP_PROTO_ICMPV6) {
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struct icmp_hdr *icmp = (struct icmp_hdr *)p;
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if (len >= ICMP_HDR_LEN) {
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icmp->icmp_cksum = 0;
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sum = ip_cksum_add(icmp, len, 0) + htons(nxt + (u_short)len);
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sum = ip_cksum_add(&ip6->ip6_src, 32, sum);
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icmp->icmp_cksum = ip_cksum_carry(sum);
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}
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} else if (nxt == IP_PROTO_ICMP || nxt == IP_PROTO_IGMP) {
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struct icmp_hdr *icmp = (struct icmp_hdr *)p;
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if (len >= ICMP_HDR_LEN) {
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icmp->icmp_cksum = 0;
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sum = ip_cksum_add(icmp, len, 0);
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icmp->icmp_cksum = ip_cksum_carry(sum);
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}
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}
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}
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