aboutsummaryrefslogtreecommitdiffstats
path: root/src/vnet/mpls/mpls_tunnel.c
blob: a142edf3f0a160f5d34b7f65538507b4849155e5 (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
754
755
756
757
758
759
760
761
762
763
764
765
766
767
768
769
770
771
772
773
774
775
776
777
778
779
780
781
782
783
784
785
786
787
788
789
790
791
792
793
794
795
796
797
798
799
800
801
802
803
804
805
806
807
808
809
810
811
812
813
814
815
816
817
818
819
820
821
822
823
824
825
826
827
828
829
830
831
832
833
834
835
836
837
838
839
840
841
842
843
844
845
846
847
848
849
850
851
852
853
854
855
856
857
858
859
860
861
862
863
864
865
866
867
868
869
870
871
872
873
874
875
876
877
878
879
880
881
882
883
884
885
886
887
888
889
890
891
892
893
894
895
896
897
898
899
900
901
902
903
904
905
906
907
908
909
910
911
912
913
914
915
916
917
918
919
920
921
922
923
924
925
926
927
928
929
930
931
932
933
934
935
936
937
938
939
940
941
942
943
944
945
946
947
948
949
950
951
952
953
954
955
956
957
958
959
960
961
962
963
964
965
966
967
968
969
970
971
972
973
974
975
976
977
978
979
980
981
982
983
984
985
986
987
988
989
990
991
992
993
994
995
996
997
998
999
1000
1001
1002
1003
1004
1005
1006
1007
1008
1009
1010
1011
1012
1013
1014
1015
1016
1017
1018
1019
1020
1021
1022
1023
1024
1025
1026
1027
1028
1029
1030
1031
/*
 * mpls_tunnel.c: MPLS tunnel interfaces (i.e. for RSVP-TE)
 *
 * Copyright (c) 2012 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.
 */

#include <vnet/vnet.h>
#include <vnet/pg/pg.h>
#include <vnet/mpls/mpls_tunnel.h>
#include <vnet/mpls/mpls_types.h>
#include <vnet/ip/ip.h>
#include <vnet/fib/fib_path_list.h>
#include <vnet/adj/adj_midchain.h>
#include <vnet/adj/adj_mcast.h>
#include <vnet/dpo/replicate_dpo.h>
#include <vnet/fib/mpls_fib.h>

/**
 * @brief pool of tunnel instances
 */
static mpls_tunnel_t *mpls_tunnel_pool;

/**
 * @brief Pool of free tunnel SW indices - i.e. recycled indices
 */
static u32 * mpls_tunnel_free_hw_if_indices;

/**
 * @brief DB of SW index to tunnel index
 */
static u32 *mpls_tunnel_db;

/**
 * @brief MPLS tunnel flags strings
 */
static const char *mpls_tunnel_attribute_names[] = MPLS_TUNNEL_ATTRIBUTES;

/**
 * @brief Get a tunnel object from a SW interface index
 */
static mpls_tunnel_t*
mpls_tunnel_get_from_sw_if_index (u32 sw_if_index)
{
    if ((vec_len(mpls_tunnel_db) < sw_if_index) ||
        (~0 == mpls_tunnel_db[sw_if_index]))
        return (NULL);

    return (pool_elt_at_index(mpls_tunnel_pool,
                              mpls_tunnel_db[sw_if_index]));
}

/**
 * @brief Build a rewrite string for the MPLS tunnel.
 */
static u8*
mpls_tunnel_build_rewrite_i (void)
{
    /*
     * passing the adj code a NULL rewirte means 'i don't have one cos
     * t'other end is unresolved'. That's not the case here. For the mpls
     * tunnel there are just no bytes of encap to apply in the adj. We'll impose
     * the label stack once we choose a path. So return a zero length rewrite.
     */
    u8 *rewrite = NULL;

    vec_validate(rewrite, 0);
    vec_reset_length(rewrite);

    return (rewrite);
}

/**
 * @brief Build a rewrite string for the MPLS tunnel.
 */
static u8*
mpls_tunnel_build_rewrite (vnet_main_t * vnm,
                           u32 sw_if_index,
                           vnet_link_t link_type,
                           const void *dst_address)
{
    return (mpls_tunnel_build_rewrite_i());
}

typedef struct mpls_tunnel_collect_forwarding_ctx_t_
{
    load_balance_path_t * next_hops;
    const mpls_tunnel_t *mt;
    fib_forward_chain_type_t fct;
} mpls_tunnel_collect_forwarding_ctx_t;

static fib_path_list_walk_rc_t
mpls_tunnel_collect_forwarding (fib_node_index_t pl_index,
                                fib_node_index_t path_index,
                                void *arg)
{
    mpls_tunnel_collect_forwarding_ctx_t *ctx;
    fib_path_ext_t *path_ext;

    ctx = arg;

    /*
     * if the path is not resolved, don't include it.
     */
    if (!fib_path_is_resolved(path_index))
    {
        return (FIB_PATH_LIST_WALK_CONTINUE);
    }

    /*
     * get the matching path-extension for the path being visited.
     */
    path_ext = fib_path_ext_list_find_by_path_index(&ctx->mt->mt_path_exts,
                                                    path_index);

    /*
     * we don't want IP TTL decrements for packets hitting the MPLS labels
     * we stack on, since the IP TTL decrement is done by the adj
     */
    path_ext->fpe_mpls_flags |= FIB_PATH_EXT_MPLS_FLAG_NO_IP_TTL_DECR;

    /*
     * found a matching extension. stack it to obtain the forwarding
     * info for this path.
     */
    ctx->next_hops = fib_path_ext_stack(path_ext,
                                        ctx->fct,
                                        ctx->fct,
                                        ctx->next_hops);

    return (FIB_PATH_LIST_WALK_CONTINUE);
}

static void
mpls_tunnel_mk_lb (mpls_tunnel_t *mt,
                   vnet_link_t linkt,
                   fib_forward_chain_type_t fct,
                   dpo_id_t *dpo_lb)
{
    dpo_proto_t lb_proto;

    /*
     * If the entry has path extensions then we construct a load-balance
     * by stacking the extensions on the forwarding chains of the paths.
     * Otherwise we use the load-balance of the path-list
     */
    mpls_tunnel_collect_forwarding_ctx_t ctx = {
        .mt = mt,
        .next_hops = NULL,
        .fct = fct,
    };

    /*
     * As an optimisation we allocate the vector of next-hops to be sized
     * equal to the maximum nuber of paths we will need, which is also the
     * most likely number we will need, since in most cases the paths are 'up'.
     */
    vec_validate(ctx.next_hops, fib_path_list_get_n_paths(mt->mt_path_list));
    vec_reset_length(ctx.next_hops);

    lb_proto = fib_forw_chain_type_to_dpo_proto(fct);

    fib_path_list_walk(mt->mt_path_list,
                       mpls_tunnel_collect_forwarding,
                       &ctx);

    if (!dpo_id_is_valid(dpo_lb))
    {
        /*
         * first time create
         */
        if (mt->mt_flags & MPLS_TUNNEL_FLAG_MCAST)
        {
            dpo_set(dpo_lb,
                    DPO_REPLICATE,
                    lb_proto,
                    replicate_create(0, lb_proto));
        }
        else
        {
            flow_hash_config_t fhc;

            switch (linkt)
            {
            case VNET_LINK_MPLS:
                fhc = MPLS_FLOW_HASH_DEFAULT;
                break;
            case VNET_LINK_IP4:
            case VNET_LINK_IP6:
                fhc = IP_FLOW_HASH_DEFAULT;
                break;
            default:
                fhc = 0;
                break;
            }

            dpo_set(dpo_lb,
                    DPO_LOAD_BALANCE,
                    lb_proto,
                    load_balance_create(0, lb_proto, fhc));
        }
    }

    if (mt->mt_flags & MPLS_TUNNEL_FLAG_MCAST)
    {
        /*
         * MPLS multicast
         */
        replicate_multipath_update(dpo_lb, ctx.next_hops);
    }
    else
    {
        load_balance_multipath_update(dpo_lb,
                                      ctx.next_hops,
                                      LOAD_BALANCE_FLAG_NONE);
        vec_free(ctx.next_hops);
    }
}

/**
 * mpls_tunnel_stack
 *
 * 'stack' (resolve the recursion for) the tunnel's midchain adjacency
 */
static void
mpls_tunnel_stack (adj_index_t ai)
{
    ip_adjacency_t *adj;
    mpls_tunnel_t *mt;
    u32 sw_if_index;

    adj = adj_get(ai);
    sw_if_index = adj->rewrite_header.sw_if_index;

    mt = mpls_tunnel_get_from_sw_if_index(sw_if_index);

    if (NULL == mt)
        return;

    /*
     * while we're stacking the adj, remove the tunnel from the child list
     * of the path list. this breaks a circular dependency of walk updates
     * where the create of adjacencies in the children can lead to walks
     * that get back here.
     */
    fib_path_list_lock(mt->mt_path_list);

    fib_path_list_child_remove(mt->mt_path_list,
                               mt->mt_sibling_index);

    /*
     * Construct the DPO (load-balance or replicate) that we can stack
     * the tunnel's midchain on
     */
    if (vnet_hw_interface_get_flags(vnet_get_main(),
                                    mt->mt_hw_if_index) &
        VNET_HW_INTERFACE_FLAG_LINK_UP)
    {
        dpo_id_t dpo = DPO_INVALID;

        mpls_tunnel_mk_lb(mt,
                          adj->ia_link,
                          fib_forw_chain_type_from_link_type(
                              adj_get_link_type(ai)),
                          &dpo);

        adj_nbr_midchain_stack(ai, &dpo);
        dpo_reset(&dpo);
    }
    else
    {
        adj_nbr_midchain_unstack(ai);
    }

    mt->mt_sibling_index = fib_path_list_child_add(mt->mt_path_list,
                                                   FIB_NODE_TYPE_MPLS_TUNNEL,
                                                   mt - mpls_tunnel_pool);

    fib_path_list_unlock(mt->mt_path_list);
}

/**
 * @brief Call back when restacking all adjacencies on a MPLS interface
 */
static adj_walk_rc_t
mpls_adj_walk_cb (adj_index_t ai,
                 void *ctx)
{
    mpls_tunnel_stack(ai);

    return (ADJ_WALK_RC_CONTINUE);
}

static void
mpls_tunnel_restack (mpls_tunnel_t *mt)
{
    fib_protocol_t proto;

    /*
     * walk all the adjacencies on the MPLS interface and restack them
     */
    if (mt->mt_flags & MPLS_TUNNEL_FLAG_L2)
    {
        /*
         * Stack a load-balance that drops, whilst we have no paths
         */
        vnet_hw_interface_t * hi;
        dpo_id_t dpo = DPO_INVALID;

        mpls_tunnel_mk_lb(mt,
                          VNET_LINK_MPLS,
                          FIB_FORW_CHAIN_TYPE_ETHERNET,
                          &dpo);

        hi = vnet_get_hw_interface(vnet_get_main(), mt->mt_hw_if_index);
        dpo_stack_from_node(hi->tx_node_index,
                            &mt->mt_l2_lb,
                            &dpo);
        dpo_reset(&dpo);
    }
    else
    {
        FOR_EACH_FIB_PROTOCOL(proto)
        {
            adj_nbr_walk(mt->mt_sw_if_index,
                         proto,
                         mpls_adj_walk_cb,
                         NULL);
        }
    }
}

static clib_error_t *
mpls_tunnel_admin_up_down (vnet_main_t * vnm,
                           u32 hw_if_index,
                           u32 flags)
{
    vnet_hw_interface_t * hi;
    mpls_tunnel_t *mt;

    hi = vnet_get_hw_interface (vnm, hw_if_index);

    mt = mpls_tunnel_get_from_sw_if_index(hi->sw_if_index);

    if (NULL == mt)
        return (NULL);

    if (flags & VNET_SW_INTERFACE_FLAG_ADMIN_UP)
        vnet_hw_interface_set_flags (vnm, hw_if_index,
                                     VNET_HW_INTERFACE_FLAG_LINK_UP);
    else
        vnet_hw_interface_set_flags (vnm, hw_if_index, 0 /* down */);

    mpls_tunnel_restack(mt);

    return (NULL);
}

/**
 * @brief Fixup the adj rewrite post encap. This is a no-op since the
 * rewrite is a stack of labels.
 */
static void
mpls_tunnel_fixup (vlib_main_t *vm,
                   ip_adjacency_t *adj,
                   vlib_buffer_t *b0,
                   const void*data)
{
    /*
     * A no-op w.r.t. the header. but reset the 'have we pushed any
     * MPLS labels onto the packet' flag. That way when we enter the
     * tunnel we'll get a TTL set to 255
     */
    vnet_buffer(b0)->mpls.first = 0;
}

static void
mpls_tunnel_update_adj (vnet_main_t * vnm,
                        u32 sw_if_index,
                        adj_index_t ai)
{
    ip_adjacency_t *adj;

    ASSERT(ADJ_INDEX_INVALID != ai);

    adj = adj_get(ai);

    switch (adj->lookup_next_index)
    {
    case IP_LOOKUP_NEXT_ARP:
    case IP_LOOKUP_NEXT_GLEAN:
        adj_nbr_midchain_update_rewrite(ai, mpls_tunnel_fixup,
                                        NULL,
                                        ADJ_FLAG_NONE,
                                        mpls_tunnel_build_rewrite_i());
        break;
    case IP_LOOKUP_NEXT_MCAST:
        /*
         * Construct a partial rewrite from the known ethernet mcast dest MAC
         * There's no MAC fixup, so the last 2 parameters are 0
         */
        adj_mcast_midchain_update_rewrite(ai, mpls_tunnel_fixup,
                                          NULL,
                                          ADJ_FLAG_NONE,
                                          mpls_tunnel_build_rewrite_i(),
                                          0, 0);
        break;

    case IP_LOOKUP_NEXT_DROP:
    case IP_LOOKUP_NEXT_PUNT:
    case IP_LOOKUP_NEXT_LOCAL:
    case IP_LOOKUP_NEXT_REWRITE:
    case IP_LOOKUP_NEXT_MIDCHAIN:
    case IP_LOOKUP_NEXT_MCAST_MIDCHAIN:
    case IP_LOOKUP_NEXT_ICMP_ERROR:
    case IP_LOOKUP_N_NEXT:
      ASSERT (0);
      break;
    }

    mpls_tunnel_stack(ai);
}

static u8 *
format_mpls_tunnel_name (u8 * s, va_list * args)
{
  u32 dev_instance = va_arg (*args, u32);
  return format (s, "mpls-tunnel%d", dev_instance);
}

static u8 *
format_mpls_tunnel_device (u8 * s, va_list * args)
{
  u32 dev_instance = va_arg (*args, u32);
  CLIB_UNUSED (int verbose) = va_arg (*args, int);

  return (format (s, "MPLS-tunnel: id %d\n", dev_instance));
}

/**
 * @brief Packet trace structure
 */
typedef struct mpls_tunnel_trace_t_
{
    /**
   * Tunnel-id / index in tunnel vector
   */
  u32 tunnel_id;
} mpls_tunnel_trace_t;

static u8 *
format_mpls_tunnel_tx_trace (u8 * s,
                             va_list * args)
{
  CLIB_UNUSED (vlib_main_t * vm) = va_arg (*args, vlib_main_t *);
  CLIB_UNUSED (vlib_node_t * node) = va_arg (*args, vlib_node_t *);
  mpls_tunnel_trace_t * t = va_arg (*args, mpls_tunnel_trace_t *);

  s = format (s, "MPLS: tunnel %d", t->tunnel_id);
  return s;
}

/**
 * @brief TX function. Only called L2. L3 traffic uses the adj-midchains
 */
static uword
mpls_tunnel_tx (vlib_main_t * vm,
                vlib_node_runtime_t * node,
                vlib_frame_t * frame)
{
  u32 next_index;
  u32 * from, * to_next, n_left_from, n_left_to_next;
  vnet_interface_output_runtime_t * rd = (void *) node->runtime_data;
  const mpls_tunnel_t *mt;

  mt = pool_elt_at_index(mpls_tunnel_pool, rd->dev_instance);

  /* Vector of buffer / pkt indices we're supposed to process */
  from = vlib_frame_vector_args (frame);

  /* Number of buffers / pkts */
  n_left_from = frame->n_vectors;

  /* Speculatively send the first buffer to the last disposition we used */
  next_index = node->cached_next_index;

  while (n_left_from > 0)
    {
      /* set up to enqueue to our disposition with index = next_index */
      vlib_get_next_frame (vm, node, next_index, to_next, n_left_to_next);

      /*
       * FIXME DUAL LOOP
       */
      while (n_left_from > 0 && n_left_to_next > 0)
        {
          vlib_buffer_t * b0;
          u32 bi0;

          bi0 = from[0];
          to_next[0] = bi0;
          from += 1;
          to_next += 1;
          n_left_from -= 1;
          n_left_to_next -= 1;

          b0 = vlib_get_buffer(vm, bi0);

          vnet_buffer(b0)->ip.adj_index[VLIB_TX] = mt->mt_l2_lb.dpoi_index;
          /* since we are coming out of the L2 world, where the vlib_buffer
           * union is used for other things, make sure it is clean for
           * MPLS from now on.
           */
          vnet_buffer(b0)->mpls.first = 0;

          if (PREDICT_FALSE(b0->flags & VLIB_BUFFER_IS_TRACED))
            {
              mpls_tunnel_trace_t *tr = vlib_add_trace (vm, node,
                                                   b0, sizeof (*tr));
              tr->tunnel_id = rd->dev_instance;
            }

          vlib_validate_buffer_enqueue_x1 (vm, node, next_index,
                                           to_next, n_left_to_next,
                                           bi0, mt->mt_l2_lb.dpoi_next_node);
        }

      vlib_put_next_frame (vm, node, next_index, n_left_to_next);
    }

  return frame->n_vectors;
}

VNET_DEVICE_CLASS (mpls_tunnel_class) = {
    .name = "MPLS tunnel device",
    .format_device_name = format_mpls_tunnel_name,
    .format_device = format_mpls_tunnel_device,
    .format_tx_trace = format_mpls_tunnel_tx_trace,
    .tx_function = mpls_tunnel_tx,
    .admin_up_down_function = mpls_tunnel_admin_up_down,
};

VNET_HW_INTERFACE_CLASS (mpls_tunnel_hw_interface_class) = {
  .name = "MPLS-Tunnel",
  .update_adjacency = mpls_tunnel_update_adj,
  .build_rewrite = mpls_tunnel_build_rewrite,
  .flags = VNET_HW_INTERFACE_CLASS_FLAG_P2P,
};

const mpls_tunnel_t *
mpls_tunnel_get (u32 mti)
{
    return (pool_elt_at_index(mpls_tunnel_pool, mti));
}

/**
 * @brief Walk all the MPLS tunnels
 */
void
mpls_tunnel_walk (mpls_tunnel_walk_cb_t cb,
                  void *ctx)
{
    u32 mti;

    pool_foreach_index(mti, mpls_tunnel_pool,
    ({
        cb(mti, ctx);
    }));
}

void
vnet_mpls_tunnel_del (u32 sw_if_index)
{
    mpls_tunnel_t *mt;

    mt = mpls_tunnel_get_from_sw_if_index(sw_if_index);

    if (NULL == mt)
        return;

    if (FIB_NODE_INDEX_INVALID != mt->mt_path_list)
        fib_path_list_child_remove(mt->mt_path_list,
                                   mt->mt_sibling_index);
    dpo_reset(&mt->mt_l2_lb);

    vec_add1 (mpls_tunnel_free_hw_if_indices, mt->mt_hw_if_index);
    pool_put(mpls_tunnel_pool, mt);
    mpls_tunnel_db[sw_if_index] = ~0;
}

u32
vnet_mpls_tunnel_create (u8 l2_only,
                         u8 is_multicast)
{
    vnet_hw_interface_t * hi;
    mpls_tunnel_t *mt;
    vnet_main_t * vnm;
    u32 mti;

    vnm = vnet_get_main();
    pool_get(mpls_tunnel_pool, mt);
    memset (mt, 0, sizeof (*mt));
    mti = mt - mpls_tunnel_pool;
    fib_node_init(&mt->mt_node, FIB_NODE_TYPE_MPLS_TUNNEL);
    mt->mt_path_list = FIB_NODE_INDEX_INVALID;
    mt->mt_sibling_index = FIB_NODE_INDEX_INVALID;

    if (is_multicast)
        mt->mt_flags |= MPLS_TUNNEL_FLAG_MCAST;
    if (l2_only)
        mt->mt_flags |= MPLS_TUNNEL_FLAG_L2;

    /*
     * Create a new, or re=use and old, tunnel HW interface
     */
    if (vec_len (mpls_tunnel_free_hw_if_indices) > 0)
    {
        mt->mt_hw_if_index =
            mpls_tunnel_free_hw_if_indices[vec_len(mpls_tunnel_free_hw_if_indices)-1];
        _vec_len (mpls_tunnel_free_hw_if_indices) -= 1;
        hi = vnet_get_hw_interface (vnm, mt->mt_hw_if_index);
        hi->hw_instance = mti;
        hi->dev_instance = mti;
    }
    else
    {
        mt->mt_hw_if_index = vnet_register_interface(
                                 vnm,
                                 mpls_tunnel_class.index,
                                 mti,
                                 mpls_tunnel_hw_interface_class.index,
                                 mti);
        hi = vnet_get_hw_interface (vnm, mt->mt_hw_if_index);
    }

    /* Standard default MPLS tunnel MTU. */
    vnet_sw_interface_set_mtu (vnm, hi->sw_if_index, 9000);

    /*
     * Add the new tunnel to the tunnel DB - key:SW if index
     */
    mt->mt_sw_if_index = hi->sw_if_index;
    vec_validate_init_empty(mpls_tunnel_db, mt->mt_sw_if_index, ~0);
    mpls_tunnel_db[mt->mt_sw_if_index] = mti;

    return (mt->mt_sw_if_index);
}

void
vnet_mpls_tunnel_path_add (u32 sw_if_index,
                           fib_route_path_t *rpaths)
{
    mpls_tunnel_t *mt;
    u32 mti;

    mt = mpls_tunnel_get_from_sw_if_index(sw_if_index);

    if (NULL == mt)
        return;

    mti = mt - mpls_tunnel_pool;

    /*
     * construct a path-list from the path provided
     */
    if (FIB_NODE_INDEX_INVALID == mt->mt_path_list)
    {
        mt->mt_path_list = fib_path_list_create(FIB_PATH_LIST_FLAG_SHARED, rpaths);
        mt->mt_sibling_index = fib_path_list_child_add(mt->mt_path_list,
                                                       FIB_NODE_TYPE_MPLS_TUNNEL,
                                                       mti);
    }
    else
    {
        fib_node_index_t old_pl_index;

        old_pl_index = mt->mt_path_list;

        mt->mt_path_list =
            fib_path_list_copy_and_path_add(old_pl_index,
                                            FIB_PATH_LIST_FLAG_SHARED,
                                            rpaths);

        fib_path_list_child_remove(old_pl_index,
                                   mt->mt_sibling_index);
        mt->mt_sibling_index = fib_path_list_child_add(mt->mt_path_list,
                                                       FIB_NODE_TYPE_MPLS_TUNNEL,
                                                       mti);
        /*
         * re-resolve all the path-extensions with the new path-list
         */
        fib_path_ext_list_resolve(&mt->mt_path_exts, mt->mt_path_list);
    }
    fib_path_ext_list_insert(&mt->mt_path_exts,
                             mt->mt_path_list,
                             FIB_PATH_EXT_MPLS,
                             rpaths);
    mpls_tunnel_restack(mt);
}

int
vnet_mpls_tunnel_path_remove (u32 sw_if_index,
                              fib_route_path_t *rpaths)
{
    mpls_tunnel_t *mt;
    u32 mti;

    mt = mpls_tunnel_get_from_sw_if_index(sw_if_index);

    if (NULL == mt)
        return (0);

    mti = mt - mpls_tunnel_pool;

    /*
     * construct a path-list from the path provided
     */
    if (FIB_NODE_INDEX_INVALID == mt->mt_path_list)
    {
        /* can't remove a path if we have onoe */
        return (0);
    }
    else
    {
        fib_node_index_t old_pl_index;

        old_pl_index = mt->mt_path_list;

        mt->mt_path_list =
            fib_path_list_copy_and_path_remove(old_pl_index,
                                               FIB_PATH_LIST_FLAG_SHARED,
                                               rpaths);

        fib_path_list_child_remove(old_pl_index,
                                   mt->mt_sibling_index);

        if (FIB_NODE_INDEX_INVALID == mt->mt_path_list)
        {
            /* no paths left */
            return (0);
        }
        else
        {
            mt->mt_sibling_index =
                fib_path_list_child_add(mt->mt_path_list,
                                        FIB_NODE_TYPE_MPLS_TUNNEL,
                                        mti);
        }
        /*
         * find the matching path extension and remove it
         */
        fib_path_ext_list_remove(&mt->mt_path_exts,
                                  FIB_PATH_EXT_MPLS,
                                  rpaths);

        /*
         * re-resolve all the path-extensions with the new path-list
         */
        fib_path_ext_list_resolve(&mt->mt_path_exts,
                                  mt->mt_path_list);

        mpls_tunnel_restack(mt);
   }

    return (fib_path_list_get_n_paths(mt->mt_path_list));
}


static clib_error_t *
vnet_create_mpls_tunnel_command_fn (vlib_main_t * vm,
                                    unformat_input_t * input,
                                    vlib_cli_command_t * cmd)
{
    unformat_input_t _line_input, * line_input = &_line_input;
    vnet_main_t * vnm = vnet_get_main();
    u8 is_del = 0, l2_only = 0, is_multicast =0;
    fib_route_path_t rpath, *rpaths = NULL;
    u32 sw_if_index = ~0, payload_proto;
    clib_error_t *error = NULL;

    memset(&rpath, 0, sizeof(rpath));
    payload_proto = DPO_PROTO_MPLS;

    /* Get a line of input. */
    if (! unformat_user (input, unformat_line_input, line_input))
        return 0;

    while (unformat_check_input (line_input) != UNFORMAT_END_OF_INPUT)
    {
        if (unformat (line_input, "del %U",
                      unformat_vnet_sw_interface, vnm,
                      &sw_if_index))
            is_del = 1;
        else if (unformat (line_input, "add %U",
                           unformat_vnet_sw_interface, vnm,
                           &sw_if_index))
            is_del = 0;
        else if (unformat (line_input, "add"))
            is_del = 0;
        else if (unformat (line_input, "l2-only"))
            l2_only = 1;
        else if (unformat (line_input, "multicast"))
            is_multicast = 1;
        else if (unformat (line_input, "via %U",
                           unformat_fib_route_path,
                           &rpath, &payload_proto))
            vec_add1(rpaths, rpath);
        else
        {
            error = clib_error_return (0, "unknown input '%U'",
                                       format_unformat_error, line_input);
            goto done;
        }
    }

    if (is_del)
    {
        if (!vnet_mpls_tunnel_path_remove(sw_if_index, rpaths))
        {
            vnet_mpls_tunnel_del(sw_if_index);
        }
    }
    else
    {
        if (0 == vec_len(rpath.frp_label_stack))
        {
            error = clib_error_return (0, "No Output Labels '%U'",
                                       format_unformat_error, line_input);
            goto done;
        }

        if (~0 == sw_if_index)
        {
            sw_if_index = vnet_mpls_tunnel_create(l2_only, is_multicast);
        }
        vnet_mpls_tunnel_path_add(sw_if_index, rpaths);
    }

done:
    vec_free(rpaths);
    unformat_free (line_input);

    return error;
}

/*?
 * This command create a uni-directional MPLS tunnel
 *
 * @cliexpar
 * @cliexstart{create mpls tunnel}
 *  create mpls tunnel via 10.0.0.1 GigEthernet0/8/0 out-label 33 out-label 34
 * @cliexend
 ?*/
VLIB_CLI_COMMAND (create_mpls_tunnel_command, static) = {
  .path = "mpls tunnel",
  .short_help =
  "mpls tunnel [multicast] [l2-only] via [next-hop-address] [next-hop-interface] [next-hop-table <value>] [weight <value>] [preference <value>] [udp-encap-id <value>] [ip4-lookup-in-table <value>] [ip6-lookup-in-table <value>] [mpls-lookup-in-table <value>] [resolve-via-host] [resolve-via-connected] [rx-ip4 <interface>] [out-labels <value value value>]",
  .function = vnet_create_mpls_tunnel_command_fn,
};

static u8 *
format_mpls_tunnel (u8 * s, va_list * args)
{
    mpls_tunnel_t *mt = va_arg (*args, mpls_tunnel_t *);
    mpls_tunnel_attribute_t attr;

    s = format(s, "mpls_tunnel%d: sw_if_index:%d hw_if_index:%d",
               mt - mpls_tunnel_pool,
               mt->mt_sw_if_index,
               mt->mt_hw_if_index);
    if (MPLS_TUNNEL_FLAG_NONE != mt->mt_flags) {
        s = format(s, " \n flags:");
        FOR_EACH_MPLS_TUNNEL_ATTRIBUTE(attr) {
            if ((1<<attr) & mt->mt_flags) {
                s = format (s, "%s,", mpls_tunnel_attribute_names[attr]);
            }
        }
    }
    s = format(s, "\n via:\n");
    s = fib_path_list_format(mt->mt_path_list, s);
    s = format(s, "%U", format_fib_path_ext_list, &mt->mt_path_exts);
    s = format(s, "\n");

    if (mt->mt_flags & MPLS_TUNNEL_FLAG_L2)
    {
        s = format(s, " forwarding: %U\n",
                   format_fib_forw_chain_type,
                   FIB_FORW_CHAIN_TYPE_ETHERNET);
        s = format(s, " %U\n", format_dpo_id, &mt->mt_l2_lb, 2);
    }

    return (s);
}

static clib_error_t *
show_mpls_tunnel_command_fn (vlib_main_t * vm,
                             unformat_input_t * input,
                             vlib_cli_command_t * cmd)
{
    mpls_tunnel_t * mt;
    u32 mti = ~0;

    if (pool_elts (mpls_tunnel_pool) == 0)
        vlib_cli_output (vm, "No MPLS tunnels configured...");

    while (unformat_check_input (input) != UNFORMAT_END_OF_INPUT)
    {
        if (unformat (input, "%d", &mti))
            ;
        else
            break;
    }

    if (~0 == mti)
    {
        pool_foreach (mt, mpls_tunnel_pool,
        ({
            vlib_cli_output (vm, "[@%d] %U",
                             mt - mpls_tunnel_pool,
                             format_mpls_tunnel, mt);
        }));
    }
    else
    {
        if (pool_is_free_index(mpls_tunnel_pool, mti))
            return clib_error_return (0, "Not atunnel index %d", mti);

        mt = pool_elt_at_index(mpls_tunnel_pool, mti);

        vlib_cli_output (vm, "[@%d] %U",
                         mt - mpls_tunnel_pool,
                         format_mpls_tunnel, mt);
    }

    return 0;
}

/*?
 * This command to show MPLS tunnels
 *
 * @cliexpar
 * @cliexstart{sh mpls tunnel 2}
 * [@2] mpls_tunnel2: sw_if_index:5 hw_if_index:5
 *  label-stack:
 *    3,
 *  via:
 *   index:26 locks:1 proto:ipv4 uPRF-list:26 len:1 itfs:[2, ]
 *     index:26 pl-index:26 ipv4 weight=1 attached-nexthop:  oper-flags:resolved,
 *      10.0.0.2 loop0
 *         [@0]: ipv4 via 10.0.0.2 loop0: IP4: de:ad:00:00:00:00 -> 00:00:11:aa:bb:cc
 * @cliexend
 ?*/
VLIB_CLI_COMMAND (show_mpls_tunnel_command, static) = {
    .path = "show mpls tunnel",
    .function = show_mpls_tunnel_command_fn,
};

static mpls_tunnel_t *
mpls_tunnel_from_fib_node (fib_node_t *node)
{
    ASSERT(FIB_NODE_TYPE_MPLS_TUNNEL == node->fn_type);
    return ((mpls_tunnel_t*) (((char*)node) -
                             STRUCT_OFFSET_OF(mpls_tunnel_t, mt_node)));
}

/**
 * Function definition to backwalk a FIB node
 */
static fib_node_back_walk_rc_t
mpls_tunnel_back_walk (fib_node_t *node,
                      fib_node_back_walk_ctx_t *ctx)
{
    mpls_tunnel_restack(mpls_tunnel_from_fib_node(node));

    return (FIB_NODE_BACK_WALK_CONTINUE);
}

/**
 * Function definition to get a FIB node from its index
 */
static fib_node_t*
mpls_tunnel_fib_node_get (fib_node_index_t index)
{
    mpls_tunnel_t * mt;

    mt = pool_elt_at_index(mpls_tunnel_pool, index);

    return (&mt->mt_node);
}

/**
 * Function definition to inform the FIB node that its last lock has gone.
 */
static void
mpls_tunnel_last_lock_gone (fib_node_t *node)
{
    /*
     * The MPLS MPLS tunnel is a root of the graph. As such
     * it never has children and thus is never locked.
     */
    ASSERT(0);
}

/*
 * Virtual function table registered by MPLS MPLS tunnels
 * for participation in the FIB object graph.
 */
const static fib_node_vft_t mpls_vft = {
    .fnv_get = mpls_tunnel_fib_node_get,
    .fnv_last_lock = mpls_tunnel_last_lock_gone,
    .fnv_back_walk = mpls_tunnel_back_walk,
};

static clib_error_t *
mpls_tunnel_init (vlib_main_t *vm)
{
  fib_node_register_type(FIB_NODE_TYPE_MPLS_TUNNEL, &mpls_vft);

  return 0;
}
VLIB_INIT_FUNCTION(mpls_tunnel_init);