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https://github.com/the-tcpdump-group/tcpdump.git
synced 2024-11-24 18:43:39 +08:00
83b356e177
If we have a routing header, instead of overwriting the packet's IPv6 destination address in the packet with the final destination, so that the next protocol's checksum routine can use it, we do as we do for IPv4, and, in the "next protocol checksum" routine, scan the headers looking for a routing header and, if we find one, copy the final destination from it. While we're at it, clean up a few things.
402 lines
10 KiB
C
402 lines
10 KiB
C
/*
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* Copyright (c) 1988, 1989, 1990, 1991, 1992, 1993, 1994
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* The Regents of the University of California. All rights reserved.
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*
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* Redistribution and use in source and binary forms, with or without
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* modification, are permitted provided that: (1) source code distributions
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* retain the above copyright notice and this paragraph in its entirety, (2)
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* distributions including binary code include the above copyright notice and
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* this paragraph in its entirety in the documentation or other materials
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* provided with the distribution, and (3) all advertising materials mentioning
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* features or use of this software display the following acknowledgement:
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* ``This product includes software developed by the University of California,
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* Lawrence Berkeley Laboratory and its contributors.'' Neither the name of
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* the University nor the names of its contributors may be used to endorse
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* or promote products derived from this software without specific prior
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* written permission.
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* THIS SOFTWARE IS PROVIDED ``AS IS'' AND WITHOUT ANY EXPRESS OR IMPLIED
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* WARRANTIES, INCLUDING, WITHOUT LIMITATION, THE IMPLIED WARRANTIES OF
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* MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE.
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*/
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#ifdef HAVE_CONFIG_H
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#include "config.h"
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#endif
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#include <netdissect-stdinc.h>
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#include <string.h>
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#include "netdissect.h"
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#include "addrtoname.h"
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#include "extract.h"
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#include "ip6.h"
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#include "ipproto.h"
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/*
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* If routing headers are presend and valid, set dst to the final destination.
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* Otherwise, set it to the IPv6 destination.
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*
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* This is used for UDP and TCP pseudo-header in the checksum
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* calculation.
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*/
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static void
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ip6_finddst(netdissect_options *ndo, struct in6_addr *dst,
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const struct ip6_hdr *ip6)
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{
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const u_char *cp;
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int advance;
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u_int nh;
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const struct in6_addr *dst_addr;
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const struct ip6_rthdr *dp;
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const struct ip6_rthdr0 *dp0;
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const struct in6_addr *addr;
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int i, len;
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cp = (const u_char *)ip6;
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advance = sizeof(struct ip6_hdr);
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nh = ip6->ip6_nxt;
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dst_addr = &ip6->ip6_dst;
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while (cp < ndo->ndo_snapend) {
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cp += advance;
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switch (nh) {
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case IPPROTO_HOPOPTS:
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case IPPROTO_DSTOPTS:
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case IPPROTO_MOBILITY_OLD:
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case IPPROTO_MOBILITY:
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/*
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* These have a header length byte, following
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* the next header byte, giving the length of
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* the header, in units of 8 octets, excluding
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* the first 8 octets.
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*/
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ND_TCHECK2(*cp, 2);
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advance = (int)((*(cp + 1) + 1) << 3);
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nh = *cp;
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break;
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case IPPROTO_FRAGMENT:
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/*
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* The byte following the next header byte is
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* marked as reserved, and the header is always
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* the same size.
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*/
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ND_TCHECK2(*cp, 1);
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advance = sizeof(struct ip6_frag);
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nh = *cp;
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break;
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case IPPROTO_ROUTING:
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/*
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* OK, we found it.
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*/
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dp = (const struct ip6_rthdr *)cp;
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ND_TCHECK(*dp);
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len = dp->ip6r_len;
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switch (dp->ip6r_type) {
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case IPV6_RTHDR_TYPE_0:
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case IPV6_RTHDR_TYPE_2: /* Mobile IPv6 ID-20 */
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dp0 = (const struct ip6_rthdr0 *)dp;
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if (len % 2 == 1)
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goto trunc;
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len >>= 1;
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addr = &dp0->ip6r0_addr[0];
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for (i = 0; i < len; i++) {
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if ((const u_char *)(addr + 1) > ndo->ndo_snapend)
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goto trunc;
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dst_addr = addr;
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addr++;
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}
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break;
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default:
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break;
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}
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/*
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* Only one routing header to a customer.
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*/
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goto done;
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case IPPROTO_AH:
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case IPPROTO_ESP:
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case IPPROTO_IPCOMP:
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default:
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/*
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* AH and ESP are, in the RFCs that describe them,
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* described as being "viewed as an end-to-end
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* payload" "in the IPv6 context, so that they
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* "should appear after hop-by-hop, routing, and
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* fragmentation extension headers". We assume
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* that's the case, and stop as soon as we see
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* one. (We can't handle an ESP header in
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* the general case anyway, as its length depends
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* on the encryption algorithm.)
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*
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* IPComp is also "viewed as an end-to-end
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* payload" "in the IPv6 context".
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*
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* All other protocols are assumed to be the final
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* protocol.
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*/
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goto done;
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}
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}
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done:
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trunc:
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UNALIGNED_MEMCPY(dst, dst_addr, sizeof(struct in6_addr));
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}
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/*
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* Compute a V6-style checksum by building a pseudoheader.
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*/
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int
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nextproto6_cksum(netdissect_options *ndo,
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const struct ip6_hdr *ip6, const uint8_t *data,
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u_int len, u_int covlen, u_int next_proto)
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{
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struct {
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struct in6_addr ph_src;
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struct in6_addr ph_dst;
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uint32_t ph_len;
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uint8_t ph_zero[3];
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uint8_t ph_nxt;
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} ph;
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struct cksum_vec vec[2];
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/* pseudo-header */
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memset(&ph, 0, sizeof(ph));
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UNALIGNED_MEMCPY(&ph.ph_src, &ip6->ip6_src, sizeof (struct in6_addr));
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switch (ip6->ip6_nxt) {
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case IPPROTO_HOPOPTS:
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case IPPROTO_DSTOPTS:
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case IPPROTO_MOBILITY_OLD:
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case IPPROTO_MOBILITY:
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case IPPROTO_FRAGMENT:
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case IPPROTO_ROUTING:
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/*
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* The next header is either a routing header or a header
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* after which there might be a routing header, so scan
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* for a routing header.
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*/
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ip6_finddst(ndo, &ph.ph_dst, ip6);
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break;
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default:
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UNALIGNED_MEMCPY(&ph.ph_dst, &ip6->ip6_dst, sizeof (struct in6_addr));
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break;
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}
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ph.ph_len = htonl(len);
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ph.ph_nxt = next_proto;
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vec[0].ptr = (const uint8_t *)(void *)&ph;
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vec[0].len = sizeof(ph);
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vec[1].ptr = data;
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vec[1].len = covlen;
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return in_cksum(vec, 2);
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}
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/*
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* print an IP6 datagram.
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*/
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void
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ip6_print(netdissect_options *ndo, const u_char *bp, u_int length)
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{
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register const struct ip6_hdr *ip6;
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register int advance;
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u_int len;
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const u_char *ipend;
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register const u_char *cp;
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register u_int payload_len;
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int nh;
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int fragmented = 0;
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u_int flow;
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ip6 = (const struct ip6_hdr *)bp;
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ND_TCHECK(*ip6);
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if (length < sizeof (struct ip6_hdr)) {
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ND_PRINT((ndo, "truncated-ip6 %u", length));
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return;
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}
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if (!ndo->ndo_eflag)
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ND_PRINT((ndo, "IP6 "));
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if (IP6_VERSION(ip6) != 6) {
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ND_PRINT((ndo,"version error: %u != 6", IP6_VERSION(ip6)));
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return;
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}
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payload_len = EXTRACT_16BITS(&ip6->ip6_plen);
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len = payload_len + sizeof(struct ip6_hdr);
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if (length < len)
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ND_PRINT((ndo, "truncated-ip6 - %u bytes missing!",
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len - length));
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if (ndo->ndo_vflag) {
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flow = EXTRACT_32BITS(&ip6->ip6_flow);
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ND_PRINT((ndo, "("));
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#if 0
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/* rfc1883 */
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if (flow & 0x0f000000)
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ND_PRINT((ndo, "pri 0x%02x, ", (flow & 0x0f000000) >> 24));
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if (flow & 0x00ffffff)
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ND_PRINT((ndo, "flowlabel 0x%06x, ", flow & 0x00ffffff));
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#else
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/* RFC 2460 */
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if (flow & 0x0ff00000)
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ND_PRINT((ndo, "class 0x%02x, ", (flow & 0x0ff00000) >> 20));
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if (flow & 0x000fffff)
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ND_PRINT((ndo, "flowlabel 0x%05x, ", flow & 0x000fffff));
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#endif
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ND_PRINT((ndo, "hlim %u, next-header %s (%u) payload length: %u) ",
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ip6->ip6_hlim,
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tok2str(ipproto_values,"unknown",ip6->ip6_nxt),
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ip6->ip6_nxt,
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payload_len));
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}
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/*
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* Cut off the snapshot length to the end of the IP payload.
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*/
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ipend = bp + len;
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if (ipend < ndo->ndo_snapend)
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ndo->ndo_snapend = ipend;
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cp = (const u_char *)ip6;
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advance = sizeof(struct ip6_hdr);
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nh = ip6->ip6_nxt;
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while (cp < ndo->ndo_snapend && advance > 0) {
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cp += advance;
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len -= advance;
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if (cp == (const u_char *)(ip6 + 1) &&
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nh != IPPROTO_TCP && nh != IPPROTO_UDP &&
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nh != IPPROTO_DCCP && nh != IPPROTO_SCTP) {
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ND_PRINT((ndo, "%s > %s: ", ip6addr_string(ndo, &ip6->ip6_src),
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ip6addr_string(ndo, &ip6->ip6_dst)));
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}
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switch (nh) {
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case IPPROTO_HOPOPTS:
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advance = hbhopt_print(ndo, cp);
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nh = *cp;
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break;
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case IPPROTO_DSTOPTS:
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advance = dstopt_print(ndo, cp);
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nh = *cp;
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break;
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case IPPROTO_FRAGMENT:
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advance = frag6_print(ndo, cp, (const u_char *)ip6);
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if (ndo->ndo_snapend <= cp + advance)
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return;
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nh = *cp;
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fragmented = 1;
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break;
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case IPPROTO_MOBILITY_OLD:
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case IPPROTO_MOBILITY:
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/*
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* XXX - we don't use "advance"; RFC 3775 says that
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* the next header field in a mobility header
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* should be IPPROTO_NONE, but speaks of
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* the possiblity of a future extension in
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* which payload can be piggybacked atop a
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* mobility header.
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*/
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advance = mobility_print(ndo, cp, (const u_char *)ip6);
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nh = *cp;
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return;
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case IPPROTO_ROUTING:
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advance = rt6_print(ndo, cp, (const u_char *)ip6);
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nh = *cp;
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break;
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case IPPROTO_SCTP:
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sctp_print(ndo, cp, (const u_char *)ip6, len);
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return;
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case IPPROTO_DCCP:
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dccp_print(ndo, cp, (const u_char *)ip6, len);
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return;
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case IPPROTO_TCP:
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tcp_print(ndo, cp, len, (const u_char *)ip6, fragmented);
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return;
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case IPPROTO_UDP:
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udp_print(ndo, cp, len, (const u_char *)ip6, fragmented);
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return;
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case IPPROTO_ICMPV6:
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icmp6_print(ndo, cp, len, (const u_char *)ip6, fragmented);
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return;
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case IPPROTO_AH:
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advance = ah_print(ndo, cp);
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nh = *cp;
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break;
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case IPPROTO_ESP:
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{
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int enh, padlen;
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advance = esp_print(ndo, cp, len, (const u_char *)ip6, &enh, &padlen);
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nh = enh & 0xff;
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len -= padlen;
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break;
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}
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case IPPROTO_IPCOMP:
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{
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int enh;
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advance = ipcomp_print(ndo, cp, &enh);
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nh = enh & 0xff;
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break;
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}
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case IPPROTO_PIM:
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pim_print(ndo, cp, len, (const u_char *)ip6);
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return;
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case IPPROTO_OSPF:
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ospf6_print(ndo, cp, len);
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return;
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case IPPROTO_IPV6:
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ip6_print(ndo, cp, len);
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return;
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case IPPROTO_IPV4:
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ip_print(ndo, cp, len);
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return;
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case IPPROTO_PGM:
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pgm_print(ndo, cp, len, (const u_char *)ip6);
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return;
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case IPPROTO_GRE:
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gre_print(ndo, cp, len);
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return;
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case IPPROTO_RSVP:
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rsvp_print(ndo, cp, len);
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return;
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case IPPROTO_NONE:
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ND_PRINT((ndo, "no next header"));
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return;
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default:
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ND_PRINT((ndo, "ip-proto-%d %d", nh, len));
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return;
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}
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}
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return;
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trunc:
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ND_PRINT((ndo, "[|ip6]"));
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}
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