tcpdump  4.99.1
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print-ip6.c
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1 /*
2  * Copyright (c) 1988, 1989, 1990, 1991, 1992, 1993, 1994
3  * The Regents of the University of California. All rights reserved.
4  *
5  * Redistribution and use in source and binary forms, with or without
6  * modification, are permitted provided that: (1) source code distributions
7  * retain the above copyright notice and this paragraph in its entirety, (2)
8  * distributions including binary code include the above copyright notice and
9  * this paragraph in its entirety in the documentation or other materials
10  * provided with the distribution, and (3) all advertising materials mentioning
11  * features or use of this software display the following acknowledgement:
12  * ``This product includes software developed by the University of California,
13  * Lawrence Berkeley Laboratory and its contributors.'' Neither the name of
14  * the University nor the names of its contributors may be used to endorse
15  * or promote products derived from this software without specific prior
16  * written permission.
17  * THIS SOFTWARE IS PROVIDED ``AS IS'' AND WITHOUT ANY EXPRESS OR IMPLIED
18  * WARRANTIES, INCLUDING, WITHOUT LIMITATION, THE IMPLIED WARRANTIES OF
19  * MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE.
20  */
21 
22 /* \summary: IPv6 printer */
23 
24 #ifdef HAVE_CONFIG_H
25 #include <config.h>
26 #endif
27 
28 #include "netdissect-stdinc.h"
29 
30 #include <string.h>
31 
32 #include "netdissect.h"
33 #include "addrtoname.h"
34 #include "extract.h"
35 
36 #include "ip6.h"
37 #include "ipproto.h"
38 
39 /*
40  * If routing headers are presend and valid, set dst to the final destination.
41  * Otherwise, set it to the IPv6 destination.
42  *
43  * This is used for UDP and TCP pseudo-header in the checksum
44  * calculation.
45  */
46 static void
48  const struct ip6_hdr *ip6)
49 {
50  const u_char *cp;
51  u_int advance;
52  u_int nh;
53  const void *dst_addr;
54  const struct ip6_rthdr *dp;
55  const struct ip6_rthdr0 *dp0;
56  const struct ip6_srh *srh;
57  const u_char *p;
58  int i, len;
59 
60  cp = (const u_char *)ip6;
61  advance = sizeof(struct ip6_hdr);
62  nh = GET_U_1(ip6->ip6_nxt);
63  dst_addr = (const void *)ip6->ip6_dst;
64 
65  while (cp < ndo->ndo_snapend) {
66  cp += advance;
67 
68  switch (nh) {
69 
70  case IPPROTO_HOPOPTS:
71  case IPPROTO_DSTOPTS:
73  case IPPROTO_MOBILITY:
74  /*
75  * These have a header length byte, following
76  * the next header byte, giving the length of
77  * the header, in units of 8 octets, excluding
78  * the first 8 octets.
79  */
80  advance = (GET_U_1(cp + 1) + 1) << 3;
81  nh = GET_U_1(cp);
82  break;
83 
84  case IPPROTO_FRAGMENT:
85  /*
86  * The byte following the next header byte is
87  * marked as reserved, and the header is always
88  * the same size.
89  */
90  advance = sizeof(struct ip6_frag);
91  nh = GET_U_1(cp);
92  break;
93 
94  case IPPROTO_ROUTING:
95  /*
96  * OK, we found it.
97  */
98  dp = (const struct ip6_rthdr *)cp;
99  ND_TCHECK_SIZE(dp);
100  len = GET_U_1(dp->ip6r_len);
101  switch (GET_U_1(dp->ip6r_type)) {
102 
103  case IPV6_RTHDR_TYPE_0:
104  case IPV6_RTHDR_TYPE_2: /* Mobile IPv6 ID-20 */
105  dp0 = (const struct ip6_rthdr0 *)dp;
106  if (len % 2 == 1)
107  goto trunc;
108  len >>= 1;
109  p = (const u_char *) dp0->ip6r0_addr;
110  for (i = 0; i < len; i++) {
111  ND_TCHECK_16(p);
112  dst_addr = (const void *)p;
113  p += 16;
114  }
115  break;
116  case IPV6_RTHDR_TYPE_4:
117  /* IPv6 Segment Routing Header (SRH) */
118  srh = (const struct ip6_srh *)dp;
119  if (len % 2 == 1)
120  goto trunc;
121  p = (const u_char *) srh->srh_segments;
122  /*
123  * The list of segments are encoded in the reverse order.
124  * Accordingly, the final DA is encoded in srh_segments[0]
125  */
126  ND_TCHECK_16(p);
127  dst_addr = (const void *)p;
128  break;
129 
130  default:
131  break;
132  }
133 
134  /*
135  * Only one routing header to a customer.
136  */
137  goto done;
138 
139  case IPPROTO_AH:
140  case IPPROTO_ESP:
141  case IPPROTO_IPCOMP:
142  default:
143  /*
144  * AH and ESP are, in the RFCs that describe them,
145  * described as being "viewed as an end-to-end
146  * payload" "in the IPv6 context, so that they
147  * "should appear after hop-by-hop, routing, and
148  * fragmentation extension headers". We assume
149  * that's the case, and stop as soon as we see
150  * one. (We can't handle an ESP header in
151  * the general case anyway, as its length depends
152  * on the encryption algorithm.)
153  *
154  * IPComp is also "viewed as an end-to-end
155  * payload" "in the IPv6 context".
156  *
157  * All other protocols are assumed to be the final
158  * protocol.
159  */
160  goto done;
161  }
162  }
163 
164 done:
165 trunc:
166  GET_CPY_BYTES(dst, dst_addr, sizeof(nd_ipv6));
167 }
168 
169 /*
170  * Compute a V6-style checksum by building a pseudoheader.
171  */
172 uint16_t
174  const struct ip6_hdr *ip6, const uint8_t *data,
175  u_int len, u_int covlen, uint8_t next_proto)
176 {
177  struct {
178  nd_ipv6 ph_src;
179  nd_ipv6 ph_dst;
180  uint32_t ph_len;
181  uint8_t ph_zero[3];
182  uint8_t ph_nxt;
183  } ph;
184  struct cksum_vec vec[2];
185  u_int nh;
186 
187  /* pseudo-header */
188  memset(&ph, 0, sizeof(ph));
189  GET_CPY_BYTES(&ph.ph_src, ip6->ip6_src, sizeof(nd_ipv6));
190  nh = GET_U_1(ip6->ip6_nxt);
191  switch (nh) {
192 
193  case IPPROTO_HOPOPTS:
194  case IPPROTO_DSTOPTS:
196  case IPPROTO_MOBILITY:
197  case IPPROTO_FRAGMENT:
198  case IPPROTO_ROUTING:
199  /*
200  * The next header is either a routing header or a header
201  * after which there might be a routing header, so scan
202  * for a routing header.
203  */
204  ip6_finddst(ndo, &ph.ph_dst, ip6);
205  break;
206 
207  default:
208  GET_CPY_BYTES(&ph.ph_dst, ip6->ip6_dst, sizeof(nd_ipv6));
209  break;
210  }
211  ph.ph_len = htonl(len);
212  ph.ph_nxt = next_proto;
213 
214  vec[0].ptr = (const uint8_t *)(void *)&ph;
215  vec[0].len = sizeof(ph);
216  vec[1].ptr = data;
217  vec[1].len = covlen;
218 
219  return in_cksum(vec, 2);
220 }
221 
222 /*
223  * print an IP6 datagram.
224  */
225 void
226 ip6_print(netdissect_options *ndo, const u_char *bp, u_int length)
227 {
228  const struct ip6_hdr *ip6;
229  int advance;
230  u_int len;
231  u_int total_advance;
232  const u_char *cp;
233  uint32_t payload_len;
234  uint8_t nh;
235  int fragmented = 0;
236  u_int flow;
237  int found_extension_header;
238  int found_jumbo;
239 
240  ndo->ndo_protocol = "ip6";
241  ip6 = (const struct ip6_hdr *)bp;
242 
243  ND_TCHECK_SIZE(ip6);
244  if (length < sizeof (struct ip6_hdr)) {
245  ND_PRINT("truncated-ip6 %u", length);
246  return;
247  }
248 
249  if (!ndo->ndo_eflag)
250  ND_PRINT("IP6 ");
251 
252  if (IP6_VERSION(ip6) != 6) {
253  ND_PRINT("version error: %u != 6", IP6_VERSION(ip6));
254  return;
255  }
256 
257  payload_len = GET_BE_U_2(ip6->ip6_plen);
258  /*
259  * RFC 1883 says:
260  *
261  * The Payload Length field in the IPv6 header must be set to zero
262  * in every packet that carries the Jumbo Payload option. If a
263  * packet is received with a valid Jumbo Payload option present and
264  * a non-zero IPv6 Payload Length field, an ICMP Parameter Problem
265  * message, Code 0, should be sent to the packet's source, pointing
266  * to the Option Type field of the Jumbo Payload option.
267  *
268  * Later versions of the IPv6 spec don't discuss the Jumbo Payload
269  * option.
270  *
271  * If the payload length is 0, we temporarily just set the total
272  * length to the remaining data in the packet (which, for Ethernet,
273  * could include frame padding, but if it's a Jumbo Payload frame,
274  * it shouldn't even be sendable over Ethernet, so we don't worry
275  * about that), so we can process the extension headers in order
276  * to *find* a Jumbo Payload hop-by-hop option and, when we've
277  * processed all the extension headers, check whether we found
278  * a Jumbo Payload option, and fail if we haven't.
279  */
280  if (payload_len != 0) {
281  len = payload_len + sizeof(struct ip6_hdr);
282  if (length < len)
283  ND_PRINT("truncated-ip6 - %u bytes missing!",
284  len - length);
285  } else
286  len = length + sizeof(struct ip6_hdr);
287 
288  nh = GET_U_1(ip6->ip6_nxt);
289  if (ndo->ndo_vflag) {
290  flow = GET_BE_U_4(ip6->ip6_flow);
291  ND_PRINT("(");
292 #if 0
293  /* rfc1883 */
294  if (flow & 0x0f000000)
295  ND_PRINT("pri 0x%02x, ", (flow & 0x0f000000) >> 24);
296  if (flow & 0x00ffffff)
297  ND_PRINT("flowlabel 0x%06x, ", flow & 0x00ffffff);
298 #else
299  /* RFC 2460 */
300  if (flow & 0x0ff00000)
301  ND_PRINT("class 0x%02x, ", (flow & 0x0ff00000) >> 20);
302  if (flow & 0x000fffff)
303  ND_PRINT("flowlabel 0x%05x, ", flow & 0x000fffff);
304 #endif
305 
306  ND_PRINT("hlim %u, next-header %s (%u) payload length: %u) ",
307  GET_U_1(ip6->ip6_hlim),
308  tok2str(ipproto_values,"unknown",nh),
309  nh,
310  payload_len);
311  }
312 
313  /*
314  * Cut off the snapshot length to the end of the IP payload.
315  */
316  nd_push_snapend(ndo, bp + len);
317 
318  cp = (const u_char *)ip6;
319  advance = sizeof(struct ip6_hdr);
320  total_advance = 0;
321  /* Process extension headers */
322  found_extension_header = 0;
323  found_jumbo = 0;
324  while (cp < ndo->ndo_snapend && advance > 0) {
325  if (len < (u_int)advance)
326  goto trunc;
327  cp += advance;
328  len -= advance;
329  total_advance += advance;
330 
331  if (cp == (const u_char *)(ip6 + 1) &&
332  nh != IPPROTO_TCP && nh != IPPROTO_UDP &&
333  nh != IPPROTO_DCCP && nh != IPPROTO_SCTP) {
334  ND_PRINT("%s > %s: ", GET_IP6ADDR_STRING(ip6->ip6_src),
336  }
337 
338  switch (nh) {
339 
340  case IPPROTO_HOPOPTS:
341  advance = hbhopt_process(ndo, cp, &found_jumbo, &payload_len);
342  if (advance < 0) {
343  nd_pop_packet_info(ndo);
344  return;
345  }
346  found_extension_header = 1;
347  nh = GET_U_1(cp);
348  break;
349 
350  case IPPROTO_DSTOPTS:
351  advance = dstopt_process(ndo, cp);
352  if (advance < 0) {
353  nd_pop_packet_info(ndo);
354  return;
355  }
356  found_extension_header = 1;
357  nh = GET_U_1(cp);
358  break;
359 
360  case IPPROTO_FRAGMENT:
361  advance = frag6_print(ndo, cp, (const u_char *)ip6);
362  if (advance < 0 || ndo->ndo_snapend <= cp + advance) {
363  nd_pop_packet_info(ndo);
364  return;
365  }
366  found_extension_header = 1;
367  nh = GET_U_1(cp);
368  fragmented = 1;
369  break;
370 
372  case IPPROTO_MOBILITY:
373  /*
374  * XXX - we don't use "advance"; RFC 3775 says that
375  * the next header field in a mobility header
376  * should be IPPROTO_NONE, but speaks of
377  * the possibility of a future extension in
378  * which payload can be piggybacked atop a
379  * mobility header.
380  */
381  advance = mobility_print(ndo, cp, (const u_char *)ip6);
382  if (advance < 0) {
383  nd_pop_packet_info(ndo);
384  return;
385  }
386  found_extension_header = 1;
387  nh = GET_U_1(cp);
388  nd_pop_packet_info(ndo);
389  return;
390 
391  case IPPROTO_ROUTING:
392  ND_TCHECK_1(cp);
393  advance = rt6_print(ndo, cp, (const u_char *)ip6);
394  if (advance < 0) {
395  nd_pop_packet_info(ndo);
396  return;
397  }
398  found_extension_header = 1;
399  nh = GET_U_1(cp);
400  break;
401 
402  default:
403  /*
404  * Not an extension header; hand off to the
405  * IP protocol demuxer.
406  */
407  if (found_jumbo) {
408  /*
409  * We saw a Jumbo Payload option.
410  * Set the length to the payload length
411  * plus the IPv6 header length, and
412  * change the snapshot length accordingly.
413  *
414  * But make sure it's not shorter than
415  * the total number of bytes we've
416  * processed so far.
417  */
418  len = payload_len + sizeof(struct ip6_hdr);
419  if (len < total_advance)
420  goto trunc;
421  if (length < len)
422  ND_PRINT("truncated-ip6 - %u bytes missing!",
423  len - length);
424  nd_change_snapend(ndo, bp + len);
425 
426  /*
427  * Now subtract the length of the IPv6
428  * header plus extension headers to get
429  * the payload length.
430  */
431  len -= total_advance;
432  } else {
433  /*
434  * We didn't see a Jumbo Payload option;
435  * was the payload length zero?
436  */
437  if (payload_len == 0) {
438  /*
439  * Yes. If we found an extension
440  * header, treat that as a truncated
441  * packet header, as there was
442  * no payload to contain an
443  * extension header.
444  */
445  if (found_extension_header)
446  goto trunc;
447 
448  /*
449  * OK, we didn't see any extnesion
450  * header, but that means we have
451  * no payload, so set the length
452  * to the IPv6 header length,
453  * and change the snapshot length
454  * accordingly.
455  */
456  len = sizeof(struct ip6_hdr);
457  nd_change_snapend(ndo, bp + len);
458 
459  /*
460  * Now subtract the length of
461  * the IPv6 header plus extension
462  * headers (there weren't any, so
463  * that's just the IPv6 header
464  * length) to get the payload length.
465  */
466  len -= total_advance;
467  }
468  }
469  ip_demux_print(ndo, cp, len, 6, fragmented,
470  GET_U_1(ip6->ip6_hlim), nh, bp);
471  nd_pop_packet_info(ndo);
472  return;
473  }
474 
475  /* ndo_protocol reassignment after xxx_print() calls */
476  ndo->ndo_protocol = "ip6";
477  }
478 
479  nd_pop_packet_info(ndo);
480  return;
481 trunc:
482  nd_print_trunc(ndo);
483 }
#define GET_IP6ADDR_STRING(p)
Definition: addrtoname.h:121
#define GET_BE_U_4(p)
Definition: extract.h:877
#define GET_BE_U_2(p)
Definition: extract.h:875
#define GET_U_1(p)
Definition: extract.h:872
#define GET_CPY_BYTES(dst, p, len)
Definition: extract.h:913
#define ND_TCHECK_16(p)
Definition: extract.h:576
#define ND_TCHECK_1(p)
Definition: extract.h:552
uint16_t in_cksum(const struct cksum_vec *vec, int veclen)
Definition: in_cksum.c:57
#define IPV6_RTHDR_TYPE_0
Definition: ip6.h:170
#define IPV6_RTHDR_TYPE_4
Definition: ip6.h:172
#define IP6_VERSION(ip6_hdr)
Definition: ip6.h:91
#define IPV6_RTHDR_TYPE_2
Definition: ip6.h:171
const struct tok ipproto_values[]
Definition: ipproto.c:25
#define IPPROTO_IPCOMP
Definition: ipproto.h:129
#define IPPROTO_ESP
Definition: ipproto.h:87
#define IPPROTO_AH
Definition: ipproto.h:90
#define IPPROTO_MOBILITY_OLD
Definition: ipproto.h:114
#define IPPROTO_TCP
Definition: ipproto.h:57
#define IPPROTO_DSTOPTS
Definition: ipproto.h:102
#define IPPROTO_MOBILITY
Definition: ipproto.h:141
#define IPPROTO_FRAGMENT
Definition: ipproto.h:78
#define IPPROTO_UDP
Definition: ipproto.h:66
#define IPPROTO_DCCP
Definition: ipproto.h:69
#define IPPROTO_ROUTING
Definition: ipproto.h:75
#define IPPROTO_SCTP
Definition: ipproto.h:138
#define IPPROTO_HOPOPTS
Definition: ipproto.h:45
int nd_push_snapend(netdissect_options *ndo, const u_char *new_snapend)
Definition: netdissect.c:176
void nd_change_snapend(netdissect_options *ndo, const u_char *new_snapend)
Definition: netdissect.c:203
void nd_pop_packet_info(netdissect_options *ndo)
Definition: netdissect.c:218
void ip_demux_print(netdissect_options *, const u_char *, u_int, u_int, int, u_int, uint8_t, const u_char *)
int hbhopt_process(netdissect_options *, const u_char *, int *, uint32_t *)
int dstopt_process(netdissect_options *, const u_char *)
const char * tok2str(const struct tok *, const char *, u_int)
Definition: util-print.c:485
int mobility_print(netdissect_options *, const u_char *, const u_char *)
#define ND_TCHECK_SIZE(p)
Definition: netdissect.h:372
void nd_print_trunc(netdissect_options *)
Definition: util-print.c:409
int frag6_print(netdissect_options *, const u_char *, const u_char *)
Definition: print-frag6.c:36
#define ND_PRINT(...)
Definition: netdissect.h:385
unsigned char nd_ipv6[16]
Definition: netdissect.h:97
int rt6_print(netdissect_options *, const u_char *, const u_char *)
Definition: print-rt6.c:37
void ip6_print(netdissect_options *ndo, const u_char *bp, u_int length)
Definition: print-ip6.c:226
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)
Definition: print-ip6.c:173
static void ip6_finddst(netdissect_options *ndo, nd_ipv6 *dst, const struct ip6_hdr *ip6)
Definition: print-ip6.c:47
const uint8_t * ptr
Definition: netdissect.h:722
Definition: ip6.h:201
Definition: ip6.h:76
nd_ipv6 ip6_dst
Definition: ip6.h:87
nd_ipv6 ip6_src
Definition: ip6.h:86
nd_ipv6 ip6r0_addr[1]
Definition: ip6.h:182
Definition: ip6.h:162
nd_uint8_t ip6r_type
Definition: ip6.h:165
nd_uint8_t ip6r_len
Definition: ip6.h:164
Definition: ip6.h:189
nd_ipv6 srh_segments[1]
Definition: ip6.h:197
const char * ndo_protocol
Definition: netdissect.h:218