summaryrefslogtreecommitdiffstats
path: root/src/vnet/ip/ip6_packet.h
blob: fecec7cdf5b2f461f55efe2fa4aabe824f8a5341 (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
352
353
354
355
356
357
358
359
360
361
362
363
364
365
366
367
368
369
370
371
372
373
374
375
376
377
378
379
380
381
382
383
384
385
386
387
388
389
390
391
392
393
394
395
396
397
398
399
400
401
402
403
404
405
406
407
408
409
410
411
412
413
414
415
416
417
418
419
420
421
422
423
424
425
426
427
428
429
430
431
432
433
434
435
436
437
438
439
440
441
442
443
444
445
446
447
448
449
450
451
452
453
454
455
456
457
458
459
460
461
462
463
464
465
466
467
468
469
470
471
472
473
474
475
476
477
478
479
480
481
482
483
484
485
486
487
488
489
490
491
492
493
494
495
496
497
498
499
500
501
502
503
504
505
506
507
508
509
510
511
512
513
514
515
516
517
518
519
520
521
522
523
524
525
526
527
528
529
530
531
532
533
534
535
536
537
538
539
540
541
542
543
544
545
546
547
548
549
550
551
552
553
554
555
556
557
558
559
560
561
562
563
564
565
566
567
568
569
570
571
572
573
574
575
576
577
578
579
580
581
582
583
584
585
586
587
588
589
590
591
592
593
594
595
596
597
598
599
600
601
602
603
604
605
606
607
608
609
610
611
612
613
614
615
616
617
618
619
620
621
622
623
624
625
626
627
628
629
630
631
632
633
634
635
636
637
638
639
640
641
642
643
644
645
646
647
648
649
650
651
652
653
654
655
656
657
658
659
660
661
662
663
664
665
666
667
668
669
670
671
672
673
674
675
676
677
678
679
680
681
682
683
684
685
686
687
688
689
690
691
692
693
694
695
696
697
698
699
700
701
702
703
704
705
706
707
708
709
710
711
712
713
714
715
716
717
718
719
720
721
722
723
724
725
726
727
728
729
730
731
732
733
734
735
736
737
738
739
740
741
742
743
744
745
746
747
748
749
750
751
752
753
/*
 * Copyright (c) 2015 Cisco and/or its affiliates.
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at:
 *
 *     http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */
/*
 * ip6/packet.h: ip6 packet format
 *
 * Copyright (c) 2008 Eliot Dresselhaus
 *
 * Permission is hereby granted, free of charge, to any person obtaining
 * a copy of this software and associated documentation files (the
 * "Software"), to deal in the Software without restriction, including
 * without limitation the rights to use, copy, modify, merge, publish,
 * distribute, sublicense, and/or sell copies of the Software, and to
 * permit persons to whom the Software is furnished to do so, subject to
 * the following conditions:
 *
 * The above copyright notice and this permission notice shall be
 * included in all copies or substantial portions of the Software.
 *
 *  THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
 *  EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
 *  MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
 *  NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE
 *  LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION
 *  OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION
 *  WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
 */

#ifndef included_ip6_packet_h
#define included_ip6_packet_h

#include <vnet/tcp/tcp_packet.h>
#include <vnet/ip/ip4_packet.h>
#include <stdbool.h>

typedef union
{
  u8 as_u8[16];
  u16 as_u16[8];
  u32 as_u32[4];
  u64 as_u64[2];
  u64x2 as_u128;
  uword as_uword[16 / sizeof (uword)];
}
__clib_packed ip6_address_t;

STATIC_ASSERT_SIZEOF (ip6_address_t, 16);

typedef struct
{
  ip6_address_t addr, mask;
} ip6_address_and_mask_t;

/* Packed so that the mhash key doesn't include uninitialized pad bytes */
typedef CLIB_PACKED (struct {
  /* IP address must be first for ip_interface_address_get_address() to work */
  ip6_address_t ip6_addr;
  u32 fib_index;
}) ip6_address_fib_t;

always_inline void
ip6_addr_fib_init (ip6_address_fib_t * addr_fib,
		   const ip6_address_t * address, u32 fib_index)
{
  addr_fib->ip6_addr = *address;
  addr_fib->fib_index = fib_index;
}

/* Special addresses:
   unspecified		::/128
   loopback		::1/128
   global unicast       2000::/3
   unique local unicast fc00::/7
   link local unicast	fe80::/10
   multicast		ff00::/8
   ietf reserved	everything else. */

#define foreach_ip6_multicast_address_scope	\
  _ (loopback, 0x1)				\
  _ (link_local, 0x2)				\
  _ (admin_local, 0x4)				\
  _ (site_local, 0x5)				\
  _ (organization_local, 0x8)			\
  _ (global, 0xe)

#define foreach_ip6_multicast_link_local_group_id	\
  _ (all_hosts, 0x1)					\
  _ (all_routers, 0x2)					\
  _ (rip_routers, 0x9)					\
  _ (eigrp_routers, 0xa)				\
  _ (pim_routers, 0xd)                            \
 _ (mldv2_routers, 0x16)

typedef enum
{
#define _(f,n) IP6_MULTICAST_SCOPE_##f = n,
  foreach_ip6_multicast_address_scope
#undef _
} ip6_multicast_address_scope_t;

typedef enum
{
#define _(f,n) IP6_MULTICAST_GROUP_ID_##f = n,
  foreach_ip6_multicast_link_local_group_id
#undef _
} ip6_multicast_link_local_group_id_t;

always_inline uword
ip6_address_is_multicast (const ip6_address_t * a)
{
  return a->as_u8[0] == 0xff;
}

always_inline void
ip6_address_copy (ip6_address_t * dst, const ip6_address_t * src)
{
  dst->as_u64[0] = src->as_u64[0];
  dst->as_u64[1] = src->as_u64[1];
}

always_inline void
ip6_set_reserved_multicast_address (ip6_address_t * a,
				    ip6_multicast_address_scope_t scope,
				    u16 id)
{
  a->as_u64[0] = a->as_u64[1] = 0;
  a->as_u16[0] = clib_host_to_net_u16 (0xff00 | scope);
  a->as_u16[7] = clib_host_to_net_u16 (id);
}

always_inline void
ip6_set_solicited_node_multicast_address (ip6_address_t * a, u32 id)
{
  /* 0xff02::1:ffXX:XXXX. */
  a->as_u64[0] = a->as_u64[1] = 0;
  a->as_u16[0] = clib_host_to_net_u16 (0xff02);
  a->as_u8[11] = 1;
  ASSERT ((id >> 24) == 0);
  id |= 0xff << 24;
  a->as_u32[3] = clib_host_to_net_u32 (id);
}

always_inline void
ip6_multicast_ethernet_address (u8 * ethernet_address, u32 group_id)
{
  ethernet_address[0] = 0x33;
  ethernet_address[1] = 0x33;
  ethernet_address[2] = ((group_id >> 24) & 0xff);
  ethernet_address[3] = ((group_id >> 16) & 0xff);
  ethernet_address[4] = ((group_id >> 8) & 0xff);
  ethernet_address[5] = ((group_id >> 0) & 0xff);
}

always_inline uword
ip6_address_is_equal (const ip6_address_t * a, const ip6_address_t * b)
{
  int i;
  for (i = 0; i < ARRAY_LEN (a->as_uword); i++)
    if (a->as_uword[i] != b->as_uword[i])
      return 0;
  return 1;
}

always_inline uword
ip6_address_is_equal_masked (const ip6_address_t * a,
			     const ip6_address_t * b,
			     const ip6_address_t * mask)
{
  int i;
  for (i = 0; i < ARRAY_LEN (a->as_uword); i++)
    {
      uword a_masked, b_masked;
      a_masked = a->as_uword[i] & mask->as_uword[i];
      b_masked = b->as_uword[i] & mask->as_uword[i];

      if (a_masked != b_masked)
	return 0;
    }
  return 1;
}

always_inline void
ip6_address_mask (ip6_address_t * a, const ip6_address_t * mask)
{
  int i;
  for (i = 0; i < ARRAY_LEN (a->as_uword); i++)
    a->as_uword[i] &= mask->as_uword[i];
}

always_inline void
ip6_address_set_zero (ip6_address_t * a)
{
  int i;
  for (i = 0; i < ARRAY_LEN (a->as_uword); i++)
    a->as_uword[i] = 0;
}

always_inline void
ip6_address_mask_from_width (ip6_address_t * a, u32 width)
{
  int i, byte, bit, bitnum;
  ASSERT (width <= 128);
  clib_memset (a, 0, sizeof (a[0]));
  for (i = 0; i < width; i++)
    {
      bitnum = (7 - (i & 7));
      byte = i / 8;
      bit = 1 << bitnum;
      a->as_u8[byte] |= bit;
    }
}

always_inline uword
ip6_address_is_zero (const ip6_address_t * a)
{
  int i;
  for (i = 0; i < ARRAY_LEN (a->as_uword); i++)
    if (a->as_uword[i] != 0)
      return 0;
  return 1;
}

/* Check for unspecified address ::0 */
always_inline uword
ip6_address_is_unspecified (const ip6_address_t * a)
{
  return ip6_address_is_zero (a);
}

/* Check for loopback address ::1 */
always_inline uword
ip6_address_is_loopback (const ip6_address_t * a)
{
  return (a->as_u64[0] == 0 &&
	  a->as_u32[2] == 0 &&
	  a->as_u16[6] == 0 && a->as_u8[14] == 0 && a->as_u8[15] == 1);
}

/* Check for link local unicast fe80::/10. */
always_inline uword
ip6_address_is_link_local_unicast (const ip6_address_t * a)
{
  return a->as_u8[0] == 0xfe && (a->as_u8[1] & 0xc0) == 0x80;
}

/* Check for unique local unicast fc00::/7. */
always_inline uword
ip6_address_is_local_unicast (const ip6_address_t * a)
{
  return (a->as_u8[0] & 0xfe) == 0xfc;
}

/* Check for unique global unicast 2000::/3. */
always_inline uword
ip6_address_is_global_unicast (const ip6_address_t * a)
{
  return (a->as_u8[0] & 0xe0) == 0x20;
}

/* Check for solicited node multicast 0xff02::1:ff00:0/104 */
always_inline uword
ip6_is_solicited_node_multicast_address (const ip6_address_t * a)
{
  return (a->as_u32[0] == clib_host_to_net_u32 (0xff020000)
	  && a->as_u32[1] == 0
	  && a->as_u32[2] == clib_host_to_net_u32 (1)
	  && a->as_u8[12] == 0xff);
}

always_inline u32
ip6_address_hash_to_u32 (const ip6_address_t * a)
{
  return (a->as_u32[0] ^ a->as_u32[1] ^ a->as_u32[2] ^ a->as_u32[3]);
}

always_inline u64
ip6_address_hash_to_u64 (const ip6_address_t * a)
{
  return (a->as_u64[0] ^ a->as_u64[1]);
}

typedef struct
{
  /* 4 bit version, 8 bit traffic class and 20 bit flow label. */
  u32 ip_version_traffic_class_and_flow_label;

  /* Total packet length not including this header (but including
     any extension headers if present). */
  u16 payload_length;

  /* Protocol for next header. */
  u8 protocol;

  /* Hop limit decremented by router at each hop. */
  u8 hop_limit;

  /* Source and destination address. */
  ip6_address_t src_address, dst_address;
} ip6_header_t;

#define IP6_PACKET_TC_MASK 0x0FF00000
#define IP6_PACKET_DSCP_MASK 0x0FC00000
#define IP6_PACKET_ECN_MASK 0x00300000
#define IP6_PACKET_FL_MASK   0x000FFFFF

always_inline ip_dscp_t
ip6_traffic_class (const ip6_header_t * i)
{
  return (i->ip_version_traffic_class_and_flow_label & IP6_PACKET_TC_MASK) >>
    20;
}

static_always_inline ip_dscp_t
ip6_traffic_class_network_order (const ip6_header_t * ip6)
{
  return (clib_net_to_host_u32 (ip6->ip_version_traffic_class_and_flow_label)
	  & IP6_PACKET_TC_MASK) >> 20;
}

static_always_inline ip_dscp_t
ip6_dscp_network_order (const ip6_header_t * ip6)
{
  return (clib_net_to_host_u32 (ip6->ip_version_traffic_class_and_flow_label)
	  & IP6_PACKET_DSCP_MASK) >> 22;
}

static_always_inline ip_ecn_t
ip6_ecn_network_order (const ip6_header_t * ip6)
{
  return (clib_net_to_host_u32 (ip6->ip_version_traffic_class_and_flow_label)
	  & IP6_PACKET_ECN_MASK) >> 20;
}

static_always_inline void
ip6_set_traffic_class_network_order (ip6_header_t * ip6, ip_dscp_t dscp)
{
  u32 tmp =
    clib_net_to_host_u32 (ip6->ip_version_traffic_class_and_flow_label);
  tmp &= 0xf00fffff;
  tmp |= (dscp << 20);
  ip6->ip_version_traffic_class_and_flow_label = clib_host_to_net_u32 (tmp);
}

static_always_inline void
ip6_set_dscp_network_order (ip6_header_t * ip6, ip_dscp_t dscp)
{
  u32 tmp =
    clib_net_to_host_u32 (ip6->ip_version_traffic_class_and_flow_label);
  tmp &= 0xf03fffff;
  tmp |= (dscp << 22);
  ip6->ip_version_traffic_class_and_flow_label = clib_host_to_net_u32 (tmp);
}

static_always_inline void
ip6_set_ecn_network_order (ip6_header_t * ip6, ip_ecn_t ecn)
{
  u32 tmp =
    clib_net_to_host_u32 (ip6->ip_version_traffic_class_and_flow_label);
  tmp &= 0xffcfffff;
  tmp |= ((0x3 & ecn) << 20);
  ip6->ip_version_traffic_class_and_flow_label = clib_host_to_net_u32 (tmp);
}

static_always_inline u32
ip6_flow_label_network_order (const ip6_header_t *ip6)
{
  u32 tmp =
    clib_net_to_host_u32 (ip6->ip_version_traffic_class_and_flow_label);
  return (tmp & 0xfffff);
}

static_always_inline void
ip6_set_flow_label_network_order (ip6_header_t *ip6, u32 flow_label)
{
  u32 tmp =
    clib_net_to_host_u32 (ip6->ip_version_traffic_class_and_flow_label);
  tmp &= 0xfff00000;
  tmp |= flow_label & 0x000fffff;
  ip6->ip_version_traffic_class_and_flow_label = clib_host_to_net_u32 (tmp);
}

static_always_inline u32
ip6_hop_limit_network_order (const ip6_header_t *ip6)
{
  return (ip6->hop_limit);
}

static_always_inline void
ip6_set_hop_limit_network_order (ip6_header_t *ip6, u8 hop_limit)
{
  ip6->hop_limit = hop_limit;
}

always_inline void *
ip6_next_header (ip6_header_t * i)
{
  return (void *) (i + 1);
}

always_inline void
ip6_copy_header (ip6_header_t * dst, const ip6_header_t * src)
{
  dst->ip_version_traffic_class_and_flow_label =
    src->ip_version_traffic_class_and_flow_label;
  dst->payload_length = src->payload_length;
  dst->protocol = src->protocol;
  dst->hop_limit = src->hop_limit;

  dst->src_address.as_uword[0] = src->src_address.as_uword[0];
  dst->src_address.as_uword[1] = src->src_address.as_uword[1];
  dst->dst_address.as_uword[0] = src->dst_address.as_uword[0];
  dst->dst_address.as_uword[1] = src->dst_address.as_uword[1];
}

always_inline void
ip6_tcp_reply_x1 (ip6_header_t * ip0, tcp_header_t * tcp0)
{
  {
    ip6_address_t src0, dst0;

    src0 = ip0->src_address;
    dst0 = ip0->dst_address;
    ip0->src_address = dst0;
    ip0->dst_address = src0;
  }

  {
    u16 src0, dst0;

    src0 = tcp0->src;
    dst0 = tcp0->dst;
    tcp0->src = dst0;
    tcp0->dst = src0;
  }
}

always_inline void
ip6_tcp_reply_x2 (ip6_header_t * ip0, ip6_header_t * ip1,
		  tcp_header_t * tcp0, tcp_header_t * tcp1)
{
  {
    ip6_address_t src0, dst0, src1, dst1;

    src0 = ip0->src_address;
    src1 = ip1->src_address;
    dst0 = ip0->dst_address;
    dst1 = ip1->dst_address;
    ip0->src_address = dst0;
    ip1->src_address = dst1;
    ip0->dst_address = src0;
    ip1->dst_address = src1;
  }

  {
    u16 src0, dst0, src1, dst1;

    src0 = tcp0->src;
    src1 = tcp1->src;
    dst0 = tcp0->dst;
    dst1 = tcp1->dst;
    tcp0->src = dst0;
    tcp1->src = dst1;
    tcp0->dst = src0;
    tcp1->dst = src1;
  }
}

typedef CLIB_PACKED (struct {
  u8 data;
}) ip6_pad1_option_t;

typedef CLIB_PACKED (struct {
  u8 type;
  u8 len;
  u8 data[0];
}) ip6_padN_option_t;

typedef CLIB_PACKED (struct {
#define IP6_MLDP_ALERT_TYPE  0x5
  u8 type;
  u8 len;
  u16 value;
}) ip6_router_alert_option_t;

typedef CLIB_PACKED (struct {
  u8 next_hdr;
  /* Length of this header plus option data in 8 byte units. */
  u8 n_data_u64s;
}) ip6_ext_header_t;

#define foreach_ext_hdr_type \
  _(IP6_HOP_BY_HOP_OPTIONS) \
  _(IPV6_ROUTE) \
  _(IP6_DESTINATION_OPTIONS) \
  _(MOBILITY) \
  _(HIP) \
  _(SHIM6)

always_inline u8
ip6_ext_hdr (u8 nexthdr)
{
#ifdef CLIB_HAVE_VEC128
  static const u8x16 ext_hdr_types = {
#define _(x) IP_PROTOCOL_##x,
    foreach_ext_hdr_type
#undef _
  };

  return !u8x16_is_all_zero (ext_hdr_types == u8x16_splat (nexthdr));
#else
  /*
   * find out if nexthdr is an extension header or a protocol
   */
  return 0
#define _(x) || (nexthdr == IP_PROTOCOL_##x)
    foreach_ext_hdr_type;
#undef _
#endif
}

typedef CLIB_PACKED (struct {
  u8 next_hdr;
  /* Length of this header plus option data in 8 byte units. */
  u8 n_data_u64s;
  u8 data[0];
}) ip6_hop_by_hop_ext_t;

typedef CLIB_PACKED (struct {
  u8 next_hdr;
  u8 rsv;
  u16 fragment_offset_and_more;
  u32 identification;
}) ip6_frag_hdr_t;

#define ip6_frag_hdr_offset(hdr)                                              \
  (clib_net_to_host_u16 ((hdr)->fragment_offset_and_more) >> 3)

#define ip6_frag_hdr_offset_bytes(hdr) (8 * ip6_frag_hdr_offset (hdr))

#define ip6_frag_hdr_more(hdr)                                                \
  (clib_net_to_host_u16 ((hdr)->fragment_offset_and_more) & 0x1)

#define ip6_frag_hdr_offset_and_more(offset, more)                            \
  clib_host_to_net_u16 (((offset) << 3) + !!(more))

#define ip6_ext_header_len(p)  ((((ip6_ext_header_t *)(p))->n_data_u64s+1) << 3)
#define ip6_ext_authhdr_len(p) ((((ip6_ext_header_t *)(p))->n_data_u64s+2) << 2)

static inline int
ip6_ext_header_len_s (ip_protocol_t nh, void *p)
{
  if (ip6_ext_hdr (nh))
    return ip6_ext_header_len (p);
  switch (nh)
    {
    case IP_PROTOCOL_IPSEC_AH:
      return ip6_ext_authhdr_len (p);
    case IP_PROTOCOL_IPV6_FRAGMENTATION:
      return sizeof (ip6_frag_hdr_t);
    case IP_PROTOCOL_ICMP6:
      return 4;
    case IP_PROTOCOL_UDP:
      return 8;
    case IP_PROTOCOL_TCP:
      return 20;
    default: /* Caller is responsible for validating the length of terminating
	     protocols */
	     ;
    }
  return 0;
}

always_inline void *
ip6_ext_next_header (ip6_ext_header_t * ext_hdr)
{
  return (void *) ((u8 *) ext_hdr + ip6_ext_header_len (ext_hdr));
}

always_inline void *
ip6_ext_next_header_offset (void *hdr, u16 offset)
{
  return (hdr + offset);
}

always_inline int
vlib_object_within_buffer_data (vlib_main_t * vm, vlib_buffer_t * b,
				void *obj, size_t len)
{
  u8 *o = obj;
  if (o < b->data ||
      o + len > b->data + vlib_buffer_get_default_data_size (vm))
    return 0;
  return 1;
}

/* Returns the number of bytes left in buffer from p. */
static inline u32
vlib_bytes_left_in_buffer (vlib_buffer_t *b, void *obj)
{
  return b->current_length - (((u8 *) obj - b->data) - b->current_data);
}

always_inline void *
ip6_ext_next_header_s (ip_protocol_t cur_nh, void *hdr, u32 max_offset,
		       u32 *offset, int *res_nh, bool *last)
{
  u16 hdrlen = 0;
  int new_nh = -1;
  void *res = 0;
  if (ip6_ext_hdr (cur_nh))
    {
      hdrlen = ip6_ext_header_len (hdr);
      new_nh = ((ip6_ext_header_t *) hdr)->next_hdr;
      res = hdr + hdrlen;
    }
  else if (cur_nh == IP_PROTOCOL_IPV6_FRAGMENTATION)
    {
      ip6_frag_hdr_t *frag_hdr = (ip6_frag_hdr_t *) hdr;
      if (ip6_frag_hdr_offset (frag_hdr) > 0)
	*last = true;
      new_nh = frag_hdr->next_hdr;
      hdrlen = sizeof (ip6_frag_hdr_t);
      res = hdr + hdrlen;
    }
  else if (cur_nh == IP_PROTOCOL_IPSEC_AH)
    {
      new_nh = ((ip6_ext_header_t *) hdr)->next_hdr;
      hdrlen = ip6_ext_authhdr_len (hdr);
      res = hdr + hdrlen;
    }
  else
    {
      ;
    }

  if (res && (*offset + hdrlen) >= max_offset)
    {
      return 0;
    }
  *res_nh = new_nh;
  *offset += hdrlen;
  return res;
}

#define IP6_EXT_HDR_MAX	      (4)   /* Maximum number of headers */
#define IP6_EXT_HDR_MAX_DEPTH (256) /* Maximum header depth */
typedef struct
{
  int length;
  struct
  {
    u16 protocol;
    u16 offset;
  } eh[IP6_EXT_HDR_MAX];
} ip6_ext_hdr_chain_t;

/*
 * Find ipv6 extension header within ipv6 header within
 * whichever is smallest of buffer or IP6_EXT_HDR_MAX_DEPTH.
 * The complete header chain must be in first buffer.
 *
 * The complete header chain (up to the terminating header) is
 * returned in res.
 * Returns the index of the find_hdr_type if > 0. Otherwise
 * it returns the index of the last header.
 */
always_inline int
ip6_ext_header_walk (vlib_buffer_t *b, ip6_header_t *ip, int find_hdr_type,
		     ip6_ext_hdr_chain_t *res)
{
  int i = 0;
  int found = -1;
  void *next_header = ip6_next_header (ip);
  int next_proto = ip->protocol;
  res->length = 0;
  u32 n_bytes_this_buffer =
    clib_min (vlib_bytes_left_in_buffer (b, ip), IP6_EXT_HDR_MAX_DEPTH);
  u32 max_offset = clib_min (n_bytes_this_buffer,
			     sizeof (ip6_header_t) +
			       clib_net_to_host_u16 (ip->payload_length));
  u32 offset = sizeof (ip6_header_t);
  if ((ip6_ext_header_len_s (ip->protocol, next_header) + offset) > max_offset)
    {
      return -1;
    }
  bool last = false;
  while (next_header)
    {
      /* Move on to next header */
      res->eh[i].offset = offset;
      res->eh[i].protocol = next_proto;
      if (next_proto == find_hdr_type)
	found = i;
      i++;
      if (last)
	break;
      if (i > IP6_EXT_HDR_MAX)
	break;
      next_header = ip6_ext_next_header_s (next_proto, next_header, max_offset,
					   &offset, &next_proto, &last);
    }
  res->length = i;
  if (find_hdr_type < 0)
    return i - 1;
  return found != -1 ? found : i - 1;
}

always_inline void *
ip6_ext_header_find (vlib_main_t *vm, vlib_buffer_t *b, ip6_header_t *ip,
		     int find_hdr_type, ip6_ext_header_t **prev_ext_header)
{
  ip6_ext_hdr_chain_t hdr_chain;
  int res = ip6_ext_header_walk (b, ip, find_hdr_type, &hdr_chain);
  if (res < 0)
    return 0;

  if (prev_ext_header)
    {
      if (res > 0)
	{
	  *prev_ext_header =
	    ip6_ext_next_header_offset (ip, hdr_chain.eh[res - 1].offset);
	}
      else
	{
	  *prev_ext_header = 0;
	}
    }
  if (find_hdr_type == hdr_chain.eh[res].protocol)
    return ip6_ext_next_header_offset (ip, hdr_chain.eh[res].offset);
  return 0;
}

#endif /* included_ip6_packet_h */

/*
 * fd.io coding-style-patch-verification: ON
 *
 * Local Variables:
 * eval: (c-set-style "gnu")
 * End:
 */