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-rw-r--r--print-ip6.c502
1 files changed, 502 insertions, 0 deletions
diff --git a/print-ip6.c b/print-ip6.c
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--- /dev/null
+++ b/print-ip6.c
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+/*
+ * Copyright (c) 1988, 1989, 1990, 1991, 1992, 1993, 1994
+ * The Regents of the University of California. All rights reserved.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that: (1) source code distributions
+ * retain the above copyright notice and this paragraph in its entirety, (2)
+ * distributions including binary code include the above copyright notice and
+ * this paragraph in its entirety in the documentation or other materials
+ * provided with the distribution, and (3) all advertising materials mentioning
+ * features or use of this software display the following acknowledgement:
+ * ``This product includes software developed by the University of California,
+ * Lawrence Berkeley Laboratory and its contributors.'' Neither the name of
+ * the University nor the names of its contributors may be used to endorse
+ * or promote products derived from this software without specific prior
+ * written permission.
+ * THIS SOFTWARE IS PROVIDED ``AS IS'' AND WITHOUT ANY EXPRESS OR IMPLIED
+ * WARRANTIES, INCLUDING, WITHOUT LIMITATION, THE IMPLIED WARRANTIES OF
+ * MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE.
+ */
+
+/* \summary: IPv6 printer */
+
+#ifdef HAVE_CONFIG_H
+#include <config.h>
+#endif
+
+#include "netdissect-stdinc.h"
+
+#include <string.h>
+
+#include "netdissect.h"
+#include "addrtoname.h"
+#include "extract.h"
+
+#include "ip6.h"
+#include "ipproto.h"
+
+/*
+ * If routing headers are presend and valid, set dst to the final destination.
+ * Otherwise, set it to the IPv6 destination.
+ *
+ * This is used for UDP and TCP pseudo-header in the checksum
+ * calculation.
+ */
+static void
+ip6_finddst(netdissect_options *ndo, nd_ipv6 *dst,
+ const struct ip6_hdr *ip6)
+{
+ const u_char *cp;
+ u_int advance;
+ u_int nh;
+ const void *dst_addr;
+ const struct ip6_rthdr *dp;
+ const struct ip6_rthdr0 *dp0;
+ const struct ip6_srh *srh;
+ const u_char *p;
+ int i, len;
+
+ cp = (const u_char *)ip6;
+ advance = sizeof(struct ip6_hdr);
+ nh = GET_U_1(ip6->ip6_nxt);
+ dst_addr = (const void *)ip6->ip6_dst;
+
+ while (cp < ndo->ndo_snapend) {
+ cp += advance;
+
+ switch (nh) {
+
+ case IPPROTO_HOPOPTS:
+ case IPPROTO_DSTOPTS:
+ case IPPROTO_MOBILITY_OLD:
+ case IPPROTO_MOBILITY:
+ /*
+ * These have a header length byte, following
+ * the next header byte, giving the length of
+ * the header, in units of 8 octets, excluding
+ * the first 8 octets.
+ */
+ advance = (GET_U_1(cp + 1) + 1) << 3;
+ nh = GET_U_1(cp);
+ break;
+
+ case IPPROTO_FRAGMENT:
+ /*
+ * The byte following the next header byte is
+ * marked as reserved, and the header is always
+ * the same size.
+ */
+ advance = sizeof(struct ip6_frag);
+ nh = GET_U_1(cp);
+ break;
+
+ case IPPROTO_ROUTING:
+ /*
+ * OK, we found it.
+ */
+ dp = (const struct ip6_rthdr *)cp;
+ ND_TCHECK_SIZE(dp);
+ len = GET_U_1(dp->ip6r_len);
+ switch (GET_U_1(dp->ip6r_type)) {
+
+ case IPV6_RTHDR_TYPE_0:
+ case IPV6_RTHDR_TYPE_2: /* Mobile IPv6 ID-20 */
+ dp0 = (const struct ip6_rthdr0 *)dp;
+ if (len % 2 == 1)
+ goto trunc;
+ len >>= 1;
+ p = (const u_char *) dp0->ip6r0_addr;
+ for (i = 0; i < len; i++) {
+ ND_TCHECK_16(p);
+ dst_addr = (const void *)p;
+ p += 16;
+ }
+ break;
+ case IPV6_RTHDR_TYPE_4:
+ /* IPv6 Segment Routing Header (SRH) */
+ srh = (const struct ip6_srh *)dp;
+ if (len % 2 == 1)
+ goto trunc;
+ p = (const u_char *) srh->srh_segments;
+ /*
+ * The list of segments are encoded in the reverse order.
+ * Accordingly, the final DA is encoded in srh_segments[0]
+ */
+ ND_TCHECK_16(p);
+ dst_addr = (const void *)p;
+ break;
+
+ default:
+ break;
+ }
+
+ /*
+ * Only one routing header to a customer.
+ */
+ goto done;
+
+ case IPPROTO_AH:
+ case IPPROTO_ESP:
+ case IPPROTO_IPCOMP:
+ default:
+ /*
+ * AH and ESP are, in the RFCs that describe them,
+ * described as being "viewed as an end-to-end
+ * payload" "in the IPv6 context, so that they
+ * "should appear after hop-by-hop, routing, and
+ * fragmentation extension headers". We assume
+ * that's the case, and stop as soon as we see
+ * one. (We can't handle an ESP header in
+ * the general case anyway, as its length depends
+ * on the encryption algorithm.)
+ *
+ * IPComp is also "viewed as an end-to-end
+ * payload" "in the IPv6 context".
+ *
+ * All other protocols are assumed to be the final
+ * protocol.
+ */
+ goto done;
+ }
+ }
+
+done:
+trunc:
+ GET_CPY_BYTES(dst, dst_addr, sizeof(nd_ipv6));
+}
+
+/*
+ * Compute a V6-style checksum by building a pseudoheader.
+ */
+uint16_t
+nextproto6_cksum(netdissect_options *ndo,
+ const struct ip6_hdr *ip6, const uint8_t *data,
+ u_int len, u_int covlen, uint8_t next_proto)
+{
+ struct {
+ nd_ipv6 ph_src;
+ nd_ipv6 ph_dst;
+ uint32_t ph_len;
+ uint8_t ph_zero[3];
+ uint8_t ph_nxt;
+ } ph;
+ struct cksum_vec vec[2];
+ u_int nh;
+
+ /* pseudo-header */
+ memset(&ph, 0, sizeof(ph));
+ GET_CPY_BYTES(&ph.ph_src, ip6->ip6_src, sizeof(nd_ipv6));
+ nh = GET_U_1(ip6->ip6_nxt);
+ switch (nh) {
+
+ case IPPROTO_HOPOPTS:
+ case IPPROTO_DSTOPTS:
+ case IPPROTO_MOBILITY_OLD:
+ case IPPROTO_MOBILITY:
+ case IPPROTO_FRAGMENT:
+ case IPPROTO_ROUTING:
+ /*
+ * The next header is either a routing header or a header
+ * after which there might be a routing header, so scan
+ * for a routing header.
+ */
+ ip6_finddst(ndo, &ph.ph_dst, ip6);
+ break;
+
+ default:
+ GET_CPY_BYTES(&ph.ph_dst, ip6->ip6_dst, sizeof(nd_ipv6));
+ break;
+ }
+ ph.ph_len = htonl(len);
+ ph.ph_nxt = next_proto;
+
+ vec[0].ptr = (const uint8_t *)(void *)&ph;
+ vec[0].len = sizeof(ph);
+ vec[1].ptr = data;
+ vec[1].len = covlen;
+
+ return in_cksum(vec, 2);
+}
+
+/*
+ * print an IP6 datagram.
+ */
+void
+ip6_print(netdissect_options *ndo, const u_char *bp, u_int length)
+{
+ const struct ip6_hdr *ip6;
+ int advance;
+ u_int len;
+ u_int total_advance;
+ const u_char *cp;
+ uint32_t payload_len;
+ uint8_t ph, nh;
+ int fragmented = 0;
+ u_int flow;
+ int found_extension_header;
+ int found_jumbo;
+ int found_hbh;
+
+ ndo->ndo_protocol = "ip6";
+ ip6 = (const struct ip6_hdr *)bp;
+
+ ND_TCHECK_SIZE(ip6);
+ if (length < sizeof (struct ip6_hdr)) {
+ ND_PRINT("truncated-ip6 %u", length);
+ return;
+ }
+
+ if (!ndo->ndo_eflag)
+ ND_PRINT("IP6 ");
+
+ if (IP6_VERSION(ip6) != 6) {
+ ND_PRINT("version error: %u != 6", IP6_VERSION(ip6));
+ return;
+ }
+
+ payload_len = GET_BE_U_2(ip6->ip6_plen);
+ /*
+ * RFC 1883 says:
+ *
+ * The Payload Length field in the IPv6 header must be set to zero
+ * in every packet that carries the Jumbo Payload option. If a
+ * packet is received with a valid Jumbo Payload option present and
+ * a non-zero IPv6 Payload Length field, an ICMP Parameter Problem
+ * message, Code 0, should be sent to the packet's source, pointing
+ * to the Option Type field of the Jumbo Payload option.
+ *
+ * Later versions of the IPv6 spec don't discuss the Jumbo Payload
+ * option.
+ *
+ * If the payload length is 0, we temporarily just set the total
+ * length to the remaining data in the packet (which, for Ethernet,
+ * could include frame padding, but if it's a Jumbo Payload frame,
+ * it shouldn't even be sendable over Ethernet, so we don't worry
+ * about that), so we can process the extension headers in order
+ * to *find* a Jumbo Payload hop-by-hop option and, when we've
+ * processed all the extension headers, check whether we found
+ * a Jumbo Payload option, and fail if we haven't.
+ */
+ if (payload_len != 0) {
+ len = payload_len + sizeof(struct ip6_hdr);
+ if (length < len)
+ ND_PRINT("truncated-ip6 - %u bytes missing!",
+ len - length);
+ } else
+ len = length + sizeof(struct ip6_hdr);
+
+ ph = 255;
+ nh = GET_U_1(ip6->ip6_nxt);
+ if (ndo->ndo_vflag) {
+ flow = GET_BE_U_4(ip6->ip6_flow);
+ ND_PRINT("(");
+ /* RFC 2460 */
+ if (flow & 0x0ff00000)
+ ND_PRINT("class 0x%02x, ", (flow & 0x0ff00000) >> 20);
+ if (flow & 0x000fffff)
+ ND_PRINT("flowlabel 0x%05x, ", flow & 0x000fffff);
+
+ ND_PRINT("hlim %u, next-header %s (%u) payload length: %u) ",
+ GET_U_1(ip6->ip6_hlim),
+ tok2str(ipproto_values,"unknown",nh),
+ nh,
+ payload_len);
+ }
+
+ /*
+ * Cut off the snapshot length to the end of the IP payload.
+ */
+ if (!nd_push_snaplen(ndo, bp, len)) {
+ (*ndo->ndo_error)(ndo, S_ERR_ND_MEM_ALLOC,
+ "%s: can't push snaplen on buffer stack", __func__);
+ }
+
+ cp = (const u_char *)ip6;
+ advance = sizeof(struct ip6_hdr);
+ total_advance = 0;
+ /* Process extension headers */
+ found_extension_header = 0;
+ found_jumbo = 0;
+ found_hbh = 0;
+ while (cp < ndo->ndo_snapend && advance > 0) {
+ if (len < (u_int)advance)
+ goto trunc;
+ cp += advance;
+ len -= advance;
+ total_advance += advance;
+
+ if (cp == (const u_char *)(ip6 + 1) &&
+ nh != IPPROTO_TCP && nh != IPPROTO_UDP &&
+ nh != IPPROTO_DCCP && nh != IPPROTO_SCTP) {
+ ND_PRINT("%s > %s: ", GET_IP6ADDR_STRING(ip6->ip6_src),
+ GET_IP6ADDR_STRING(ip6->ip6_dst));
+ }
+
+ switch (nh) {
+
+ case IPPROTO_HOPOPTS:
+ /*
+ * The Hop-by-Hop Options header, when present,
+ * must immediately follow the IPv6 header (RFC 8200)
+ */
+ if (found_hbh == 1) {
+ ND_PRINT("[The Hop-by-Hop Options header was already found]");
+ nd_print_invalid(ndo);
+ return;
+ }
+ if (ph != 255) {
+ ND_PRINT("[The Hop-by-Hop Options header don't follow the IPv6 header]");
+ nd_print_invalid(ndo);
+ return;
+ }
+ advance = hbhopt_process(ndo, cp, &found_jumbo, &payload_len);
+ if (payload_len == 0 && found_jumbo == 0) {
+ ND_PRINT("[No valid Jumbo Payload Hop-by-Hop option found]");
+ nd_print_invalid(ndo);
+ return;
+ }
+ if (advance < 0) {
+ nd_pop_packet_info(ndo);
+ return;
+ }
+ found_extension_header = 1;
+ found_hbh = 1;
+ nh = GET_U_1(cp);
+ break;
+
+ case IPPROTO_DSTOPTS:
+ advance = dstopt_process(ndo, cp);
+ if (advance < 0) {
+ nd_pop_packet_info(ndo);
+ return;
+ }
+ found_extension_header = 1;
+ nh = GET_U_1(cp);
+ break;
+
+ case IPPROTO_FRAGMENT:
+ advance = frag6_print(ndo, cp, (const u_char *)ip6);
+ if (advance < 0 || ndo->ndo_snapend <= cp + advance) {
+ nd_pop_packet_info(ndo);
+ return;
+ }
+ found_extension_header = 1;
+ nh = GET_U_1(cp);
+ fragmented = 1;
+ break;
+
+ case IPPROTO_MOBILITY_OLD:
+ case IPPROTO_MOBILITY:
+ /*
+ * XXX - we don't use "advance"; RFC 3775 says that
+ * the next header field in a mobility header
+ * should be IPPROTO_NONE, but speaks of
+ * the possibility of a future extension in
+ * which payload can be piggybacked atop a
+ * mobility header.
+ */
+ advance = mobility_print(ndo, cp, (const u_char *)ip6);
+ if (advance < 0) {
+ nd_pop_packet_info(ndo);
+ return;
+ }
+ found_extension_header = 1;
+ nh = GET_U_1(cp);
+ nd_pop_packet_info(ndo);
+ return;
+
+ case IPPROTO_ROUTING:
+ ND_TCHECK_1(cp);
+ advance = rt6_print(ndo, cp, (const u_char *)ip6);
+ if (advance < 0) {
+ nd_pop_packet_info(ndo);
+ return;
+ }
+ found_extension_header = 1;
+ nh = GET_U_1(cp);
+ break;
+
+ default:
+ /*
+ * Not an extension header; hand off to the
+ * IP protocol demuxer.
+ */
+ if (found_jumbo) {
+ /*
+ * We saw a Jumbo Payload option.
+ * Set the length to the payload length
+ * plus the IPv6 header length, and
+ * change the snapshot length accordingly.
+ *
+ * But make sure it's not shorter than
+ * the total number of bytes we've
+ * processed so far.
+ */
+ len = payload_len + sizeof(struct ip6_hdr);
+ if (len < total_advance)
+ goto trunc;
+ if (length < len)
+ ND_PRINT("truncated-ip6 - %u bytes missing!",
+ len - length);
+ nd_change_snaplen(ndo, bp, len);
+
+ /*
+ * Now subtract the length of the IPv6
+ * header plus extension headers to get
+ * the payload length.
+ */
+ len -= total_advance;
+ } else {
+ /*
+ * We didn't see a Jumbo Payload option;
+ * was the payload length zero?
+ */
+ if (payload_len == 0) {
+ /*
+ * Yes. If we found an extension
+ * header, treat that as a truncated
+ * packet header, as there was
+ * no payload to contain an
+ * extension header.
+ */
+ if (found_extension_header)
+ goto trunc;
+
+ /*
+ * OK, we didn't see any extension
+ * header, but that means we have
+ * no payload, so set the length
+ * to the IPv6 header length,
+ * and change the snapshot length
+ * accordingly.
+ */
+ len = sizeof(struct ip6_hdr);
+ nd_change_snaplen(ndo, bp, len);
+
+ /*
+ * Now subtract the length of
+ * the IPv6 header plus extension
+ * headers (there weren't any, so
+ * that's just the IPv6 header
+ * length) to get the payload length.
+ */
+ len -= total_advance;
+ }
+ }
+ ip_demux_print(ndo, cp, len, 6, fragmented,
+ GET_U_1(ip6->ip6_hlim), nh, bp);
+ nd_pop_packet_info(ndo);
+ return;
+ }
+ ph = nh;
+
+ /* ndo_protocol reassignment after xxx_print() calls */
+ ndo->ndo_protocol = "ip6";
+ }
+
+ nd_pop_packet_info(ndo);
+ return;
+trunc:
+ nd_print_trunc(ndo);
+}
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