summaryrefslogtreecommitdiff
path: root/bgpd/bgp_mpath.c
blob: d07830d14db7394c63843915e7be47d3ca91ce9d (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
/* $QuaggaId: Format:%an, %ai, %h$ $
 *
 * BGP Multipath
 * Copyright (C) 2010 Google Inc.
 *
 * This file is part of Quagga
 *
 * Quagga is free software; you can redistribute it and/or modify it
 * under the terms of the GNU General Public License as published by the
 * Free Software Foundation; either version 2, or (at your option) any
 * later version.
 *
 * Quagga is distributed in the hope that it will be useful, but
 * WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
 * General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with Quagga; see the file COPYING.  If not, write to the Free
 * Software Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA
 * 02111-1307, USA.
 */

#include <zebra.h>

#include "command.h"
#include "prefix.h"
#include "linklist.h"
#include "sockunion.h"
#include "memory.h"

#include "bgpd/bgpd.h"
#include "bgpd/bgp_table.h"
#include "bgpd/bgp_route.h"
#include "bgpd/bgp_attr.h"
#include "bgpd/bgp_debug.h"
#include "bgpd/bgp_aspath.h"
#include "bgpd/bgp_community.h"
#include "bgpd/bgp_ecommunity.h"
#include "bgpd/bgp_mpath.h"

/*
 * bgp_maximum_paths_set
 *
 * Record maximum-paths configuration for BGP instance
 */
int
bgp_maximum_paths_set (struct bgp *bgp, afi_t afi, safi_t safi,
                       int peertype, u_int16_t maxpaths)
{
  if (!bgp || (afi >= AFI_MAX) || (safi >= SAFI_MAX))
    return -1;

  switch (peertype)
    {
    case BGP_PEER_IBGP:
      bgp->maxpaths[afi][safi].maxpaths_ibgp = maxpaths;
      break;
    case BGP_PEER_EBGP:
      bgp->maxpaths[afi][safi].maxpaths_ebgp = maxpaths;
      break;
    default:
      return -1;
    }

  return 0;
}

/*
 * bgp_maximum_paths_unset
 *
 * Remove maximum-paths configuration from BGP instance
 */
int
bgp_maximum_paths_unset (struct bgp *bgp, afi_t afi, safi_t safi,
                         int peertype)
{
  if (!bgp || (afi >= AFI_MAX) || (safi >= SAFI_MAX))
    return -1;

  switch (peertype)
    {
    case BGP_PEER_IBGP:
      bgp->maxpaths[afi][safi].maxpaths_ibgp = BGP_DEFAULT_MAXPATHS;
      break;
    case BGP_PEER_EBGP:
      bgp->maxpaths[afi][safi].maxpaths_ebgp = BGP_DEFAULT_MAXPATHS;
      break;
    default:
      return -1;
    }

  return 0;
}

/*
 * bgp_info_nexthop_cmp
 *
 * Compare the nexthops of two paths. Return value is less than, equal to,
 * or greater than zero if bi1 is respectively less than, equal to,
 * or greater than bi2.
 */
static int
bgp_info_nexthop_cmp (struct bgp_info *bi1, struct bgp_info *bi2)
{
  struct attr_extra *ae1, *ae2;
  int compare;

  ae1 = bi1->attr->extra;
  ae2 = bi2->attr->extra;

  compare = IPV4_ADDR_CMP (&bi1->attr->nexthop, &bi2->attr->nexthop);

  if (!compare && ae1 && ae2 && (ae1->mp_nexthop_len == ae2->mp_nexthop_len))
    {
      switch (ae1->mp_nexthop_len)
        {
        case 4:
        case 12:
          compare = IPV4_ADDR_CMP (&ae1->mp_nexthop_global_in,
                                   &ae2->mp_nexthop_global_in);
          break;
#ifdef HAVE_IPV6
        case 16:
          compare = IPV6_ADDR_CMP (&ae1->mp_nexthop_global,
                                   &ae2->mp_nexthop_global);
          break;
        case 32:
          compare = IPV6_ADDR_CMP (&ae1->mp_nexthop_global,
                                   &ae2->mp_nexthop_global);
          if (!compare)
            compare = IPV6_ADDR_CMP (&ae1->mp_nexthop_local,
                                     &ae2->mp_nexthop_local);
          break;
#endif /* HAVE_IPV6 */
        }
    }

  return compare;
}

/*
 * bgp_info_mpath_cmp
 *
 * This function determines our multipath list ordering. By ordering
 * the list we can deterministically select which paths are included
 * in the multipath set. The ordering also helps in detecting changes
 * in the multipath selection so we can detect whether to send an
 * update to zebra.
 *
 * The order of paths is determined first by received nexthop, and then
 * by peer address if the nexthops are the same.
 */
static int
bgp_info_mpath_cmp (void *val1, void *val2)
{
  struct bgp_info *bi1, *bi2;
  int compare;

  bi1 = val1;
  bi2 = val2;

  compare = bgp_info_nexthop_cmp (bi1, bi2);

  if (!compare)
    compare = sockunion_cmp (bi1->peer->su_remote, bi2->peer->su_remote);

  return compare;
}

/*
 * bgp_mp_list_init
 *
 * Initialize the mp_list, which holds the list of multipaths
 * selected by bgp_best_selection
 */
void
bgp_mp_list_init (struct list *mp_list)
{
  assert (mp_list);
  memset (mp_list, 0, sizeof (struct list));
  mp_list->cmp = bgp_info_mpath_cmp;
}

/*
 * bgp_mp_list_clear
 *
 * Clears all entries out of the mp_list
 */
void
bgp_mp_list_clear (struct list *mp_list)
{
  assert (mp_list);
  list_delete_all_node (mp_list);
}

/*
 * bgp_mp_list_add
 *
 * Adds a multipath entry to the mp_list
 */
void
bgp_mp_list_add (struct list *mp_list, struct bgp_info *mpinfo)
{
  assert (mp_list && mpinfo);
  listnode_add_sort (mp_list, mpinfo);
}

/*
 * bgp_info_mpath_new
 *
 * Allocate and zero memory for a new bgp_info_mpath element
 */
static struct bgp_info_mpath *
bgp_info_mpath_new (void)
{
  struct bgp_info_mpath *new_mpath;
  new_mpath = XCALLOC (MTYPE_BGP_MPATH_INFO, sizeof (struct bgp_info_mpath));
  return new_mpath;
}

/*
 * bgp_info_mpath_free
 *
 * Release resources for a bgp_info_mpath element and zero out pointer
 */
void
bgp_info_mpath_free (struct bgp_info_mpath **mpath)
{
  if (mpath && *mpath)
    {
      if ((*mpath)->mp_attr)
        bgp_attr_unintern ((*mpath)->mp_attr);
      XFREE (MTYPE_BGP_MPATH_INFO, *mpath);
      *mpath = NULL;
    }
}

/*
 * bgp_info_mpath_get
 *
 * Fetch the mpath element for the given bgp_info. Used for
 * doing lazy allocation.
 */
static struct bgp_info_mpath *
bgp_info_mpath_get (struct bgp_info *binfo)
{
  struct bgp_info_mpath *mpath;
  if (!binfo->mpath)
    {
      mpath = bgp_info_mpath_new();
      if (!mpath)
        return NULL;
      binfo->mpath = mpath;
      mpath->mp_info = binfo;
    }
  return binfo->mpath;
}

/*
 * bgp_info_mpath_enqueue
 *
 * Enqueue a path onto the multipath list given the previous multipath
 * list entry
 */
static void
bgp_info_mpath_enqueue (struct bgp_info *prev_info, struct bgp_info *binfo)
{
  struct bgp_info_mpath *prev, *mpath;

  prev = bgp_info_mpath_get (prev_info);
  mpath = bgp_info_mpath_get (binfo);
  if (!prev || !mpath)
    return;

  mpath->mp_next = prev->mp_next;
  mpath->mp_prev = prev;
  if (prev->mp_next)
    prev->mp_next->mp_prev = mpath;
  prev->mp_next = mpath;

  SET_FLAG (binfo->flags, BGP_INFO_MULTIPATH);
}

/*
 * bgp_info_mpath_dequeue
 *
 * Remove a path from the multipath list
 */
void
bgp_info_mpath_dequeue (struct bgp_info *binfo)
{
  struct bgp_info_mpath *mpath = binfo->mpath;
  if (!mpath)
    return;
  if (mpath->mp_prev)
    mpath->mp_prev->mp_next = mpath->mp_next;
  if (mpath->mp_next)
    mpath->mp_next->mp_prev = mpath->mp_prev;
  mpath->mp_next = mpath->mp_prev = NULL;
  UNSET_FLAG (binfo->flags, BGP_INFO_MULTIPATH);
}

/*
 * bgp_info_mpath_next
 *
 * Given a bgp_info, return the next multipath entry
 */
struct bgp_info *
bgp_info_mpath_next (struct bgp_info *binfo)
{
  if (!binfo->mpath || !binfo->mpath->mp_next)
    return NULL;
  return binfo->mpath->mp_next->mp_info;
}

/*
 * bgp_info_mpath_first
 *
 * Given bestpath bgp_info, return the first multipath entry.
 */
struct bgp_info *
bgp_info_mpath_first (struct bgp_info *binfo)
{
  return bgp_info_mpath_next (binfo);
}

/*
 * bgp_info_mpath_count
 *
 * Given the bestpath bgp_info, return the number of multipath entries
 */
u_int32_t
bgp_info_mpath_count (struct bgp_info *binfo)
{
  if (!binfo->mpath)
    return 0;
  return binfo->mpath->mp_count;
}

/*
 * bgp_info_mpath_count_set
 *
 * Sets the count of multipaths into bestpath's mpath element
 */
static void
bgp_info_mpath_count_set (struct bgp_info *binfo, u_int32_t count)
{
  struct bgp_info_mpath *mpath;
  if (!count && !binfo->mpath)
    return;
  mpath = bgp_info_mpath_get (binfo);
  if (!mpath)
    return;
  mpath->mp_count = count;
}

/*
 * bgp_info_mpath_attr
 *
 * Given bestpath bgp_info, return aggregated attribute set used
 * for advertising the multipath route
 */
struct attr *
bgp_info_mpath_attr (struct bgp_info *binfo)
{
  if (!binfo->mpath)
    return NULL;
  return binfo->mpath->mp_attr;
}

/*
 * bgp_info_mpath_attr_set
 *
 * Sets the aggregated attribute into bestpath's mpath element
 */
static void
bgp_info_mpath_attr_set (struct bgp_info *binfo, struct attr *attr)
{
  struct bgp_info_mpath *mpath;
  if (!attr && !binfo->mpath)
    return;
  mpath = bgp_info_mpath_get (binfo);
  if (!mpath)
    return;
  mpath->mp_attr = attr;
}

/*
 * bgp_info_mpath_update
 *
 * Compare and sync up the multipath list with the mp_list generated by
 * bgp_best_selection
 */
void
bgp_info_mpath_update (struct bgp_node *rn, struct bgp_info *new_best,
                       struct bgp_info *old_best, struct list *mp_list,
                       struct bgp_maxpaths_cfg *mpath_cfg)
{
  u_int16_t maxpaths, mpath_count, old_mpath_count;
  struct listnode *mp_node, *mp_next_node;
  struct bgp_info *cur_mpath, *new_mpath, *next_mpath, *prev_mpath;
  int mpath_changed, debug;
  char pfx_buf[INET_ADDRSTRLEN], nh_buf[2][INET_ADDRSTRLEN];

  mpath_changed = 0;
  maxpaths = BGP_DEFAULT_MAXPATHS;
  mpath_count = 0;
  cur_mpath = NULL;
  old_mpath_count = 0;
  prev_mpath = new_best;
  mp_node = listhead (mp_list);
  debug = BGP_DEBUG (events, EVENTS);

  if (debug)
    prefix2str (&rn->p, pfx_buf, sizeof (pfx_buf));

  if (new_best)
    {
      mpath_count++;
      if (new_best != old_best)
        bgp_info_mpath_dequeue (new_best);
      maxpaths = (peer_sort (new_best->peer) == BGP_PEER_IBGP) ?
        mpath_cfg->maxpaths_ibgp : mpath_cfg->maxpaths_ebgp;
    }

  if (old_best)
    {
      cur_mpath = bgp_info_mpath_first (old_best);
      old_mpath_count = bgp_info_mpath_count (old_best);
      bgp_info_mpath_count_set (old_best, 0);
      bgp_info_mpath_dequeue (old_best);
    }

  /*
   * We perform an ordered walk through both lists in parallel.
   * The reason for the ordered walk is that if there are paths
   * that were previously multipaths and are still multipaths, the walk
   * should encounter them in both lists at the same time. Otherwise
   * there will be paths that are in one list or another, and we
   * will deal with these separately.
   *
   * Note that new_best might be somewhere in the mp_list, so we need
   * to skip over it
   */
  while (mp_node || cur_mpath)
    {
      /*
       * We can bail out of this loop if all existing paths on the
       * multipath list have been visited (for cleanup purposes) and
       * the maxpath requirement is fulfulled
       */
      if (!cur_mpath && (mpath_count >= maxpaths))
        break;

      mp_next_node = mp_node ? listnextnode (mp_node) : NULL;
      next_mpath = cur_mpath ? bgp_info_mpath_next (cur_mpath) : NULL;

      /*
       * If equal, the path was a multipath and is still a multipath.
       * Insert onto new multipath list if maxpaths allows.
       */
      if (mp_node && (listgetdata (mp_node) == cur_mpath))
        {
          list_delete_node (mp_list, mp_node);
          bgp_info_mpath_dequeue (cur_mpath);
          if ((mpath_count < maxpaths) &&
              bgp_info_nexthop_cmp (prev_mpath, cur_mpath))
            {
              bgp_info_mpath_enqueue (prev_mpath, cur_mpath);
              prev_mpath = cur_mpath;
              mpath_count++;
            }
          else
            {
              mpath_changed = 1;
              if (debug)
                zlog_debug ("%s remove mpath nexthop %s peer %s", pfx_buf,
                            inet_ntop (AF_INET, &cur_mpath->attr->nexthop,
                                       nh_buf[0], sizeof (nh_buf[0])),
                            sockunion2str (cur_mpath->peer->su_remote,
                                           nh_buf[1], sizeof (nh_buf[1])));
            }
          mp_node = mp_next_node;
          cur_mpath = next_mpath;
          continue;
        }

      if (cur_mpath && (!mp_node ||
                        (bgp_info_mpath_cmp (cur_mpath,
                                             listgetdata (mp_node)) < 0)))
        {
          /*
           * If here, we have an old multipath and either the mp_list
           * is finished or the next mp_node points to a later
           * multipath, so we need to purge this path from the
           * multipath list
           */
          bgp_info_mpath_dequeue (cur_mpath);
          mpath_changed = 1;
          if (debug)
            zlog_debug ("%s remove mpath nexthop %s peer %s", pfx_buf,
                        inet_ntop (AF_INET, &cur_mpath->attr->nexthop,
                                   nh_buf[0], sizeof (nh_buf[0])),
                        sockunion2str (cur_mpath->peer->su_remote,
                                       nh_buf[1], sizeof (nh_buf[1])));
          cur_mpath = next_mpath;
        }
      else
        {
          /*
           * If here, we have a path on the mp_list that was not previously
           * a multipath (due to non-equivalance or maxpaths exceeded),
           * or the matching multipath is sorted later in the multipath
           * list. Before we enqueue the path on the new multipath list,
           * make sure its not on the old_best multipath list or referenced
           * via next_mpath:
           * - If next_mpath points to this new path, update next_mpath to
           *   point to the multipath after this one
           * - Dequeue the path from the multipath list just to make sure
           */
          new_mpath = listgetdata (mp_node);
          list_delete_node (mp_list, mp_node);
          if ((mpath_count < maxpaths) && (new_mpath != new_best) &&
              bgp_info_nexthop_cmp (prev_mpath, new_mpath))
            {
              if (new_mpath == next_mpath)
                next_mpath = bgp_info_mpath_next (new_mpath);
              bgp_info_mpath_dequeue (new_mpath);

              bgp_info_mpath_enqueue (prev_mpath, new_mpath);
              prev_mpath = new_mpath;
              mpath_changed = 1;
              mpath_count++;
              if (debug)
                zlog_debug ("%s add mpath nexthop %s peer %s", pfx_buf,
                            inet_ntop (AF_INET, &new_mpath->attr->nexthop,
                                       nh_buf[0], sizeof (nh_buf[0])),
                            sockunion2str (new_mpath->peer->su_remote,
                                           nh_buf[1], sizeof (nh_buf[1])));
            }
          mp_node = mp_next_node;
        }
    }

  if (new_best)
    {
      bgp_info_mpath_count_set (new_best, mpath_count-1);
      if (mpath_changed || (bgp_info_mpath_count (new_best) != old_mpath_count))
        SET_FLAG (new_best->flags, BGP_INFO_MULTIPATH_CHG);
    }
}

/*
 * bgp_mp_dmed_deselect
 *
 * Clean up multipath information for BGP_INFO_DMED_SELECTED path that
 * is not selected as best path
 */
void
bgp_mp_dmed_deselect (struct bgp_info *dmed_best)
{
  struct bgp_info *mpinfo, *mpnext;

  if (!dmed_best)
    return;

  for (mpinfo = bgp_info_mpath_first (dmed_best); mpinfo; mpinfo = mpnext)
    {
      mpnext = bgp_info_mpath_next (mpinfo);
      bgp_info_mpath_dequeue (mpinfo);
    }

  bgp_info_mpath_count_set (dmed_best, 0);
  UNSET_FLAG (dmed_best->flags, BGP_INFO_MULTIPATH_CHG);
  assert (bgp_info_mpath_first (dmed_best) == 0);
}

/*
 * bgp_info_mpath_aggregate_update
 *
 * Set the multipath aggregate attribute. We need to see if the
 * aggregate has changed and then set the ATTR_CHANGED flag on the
 * bestpath info so that a peer update will be generated. The
 * change is detected by generating the current attribute,
 * interning it, and then comparing the interned pointer with the
 * current value. We can skip this generate/compare step if there
 * is no change in multipath selection and no attribute change in
 * any multipath.
 */
void
bgp_info_mpath_aggregate_update (struct bgp_info *new_best,
                                 struct bgp_info *old_best)
{
  struct bgp_info *mpinfo;
  struct aspath *aspath;
  struct aspath *asmerge;
  struct attr *new_attr, *old_attr;
  u_char origin, attr_chg;
  struct community *community, *commerge;
  struct ecommunity *ecomm, *ecommerge;
  struct attr_extra *ae;
  struct attr attr = { 0 };

  if (old_best && (old_best != new_best) &&
      (old_attr = bgp_info_mpath_attr (old_best)))
    {
      bgp_attr_unintern (old_attr);
      bgp_info_mpath_attr_set (old_best, NULL);
    }

  if (!new_best)
    return;

  if (!bgp_info_mpath_count (new_best))
    {
      if ((new_attr = bgp_info_mpath_attr (new_best)))
        {
          bgp_attr_unintern (new_attr);
          bgp_info_mpath_attr_set (new_best, NULL);
          SET_FLAG (new_best->flags, BGP_INFO_ATTR_CHANGED);
        }
      return;
    }

  /*
   * Bail out here if the following is true:
   * - MULTIPATH_CHG bit is not set on new_best, and
   * - No change in bestpath, and
   * - ATTR_CHANGED bit is not set on new_best or any of the multipaths
   */
  if (!CHECK_FLAG (new_best->flags, BGP_INFO_MULTIPATH_CHG) &&
      (old_best == new_best))
    {
      attr_chg = 0;

      if (CHECK_FLAG (new_best->flags, BGP_INFO_ATTR_CHANGED))
        attr_chg = 1;
      else
        for (mpinfo = bgp_info_mpath_first (new_best); mpinfo;
             mpinfo = bgp_info_mpath_next (mpinfo))
          {
            if (CHECK_FLAG (mpinfo->flags, BGP_INFO_ATTR_CHANGED))
              {
                attr_chg = 1;
                break;
              }
          }

      if (!attr_chg)
        {
          assert (bgp_info_mpath_attr (new_best));
          return;
        }
    }

  bgp_attr_dup (&attr, new_best->attr);

  /* aggregate attribute from multipath constituents */
  aspath = aspath_dup (attr.aspath);
  origin = attr.origin;
  community = attr.community ? community_dup (attr.community) : NULL;
  ae = attr.extra;
  ecomm = (ae && ae->ecommunity) ? ecommunity_dup (ae->ecommunity) : NULL;

  for (mpinfo = bgp_info_mpath_first (new_best); mpinfo;
       mpinfo = bgp_info_mpath_next (mpinfo))
    {
      asmerge = aspath_aggregate (aspath, mpinfo->attr->aspath);
      aspath_free (aspath);
      aspath = asmerge;

      if (origin < mpinfo->attr->origin)
        origin = mpinfo->attr->origin;

      if (mpinfo->attr->community)
        {
          if (community)
            {
              commerge = community_merge (community, mpinfo->attr->community);
              community = community_uniq_sort (commerge);
              community_free (commerge);
            }
          else
            community = community_dup (mpinfo->attr->community);
        }

      ae = mpinfo->attr->extra;
      if (ae && ae->ecommunity)
        {
          if (ecomm)
            {
              ecommerge = ecommunity_merge (ecomm, ae->ecommunity);
              ecomm = ecommunity_uniq_sort (ecommerge);
              ecommunity_free (ecommerge);
            }
          else
            ecomm = ecommunity_dup (ae->ecommunity);
        }
    }

  attr.aspath = aspath;
  attr.origin = origin;
  if (community)
    {
      attr.community = community;
      attr.flag |= ATTR_FLAG_BIT (BGP_ATTR_COMMUNITIES);
    }
  if (ecomm)
    {
      ae = bgp_attr_extra_get (&attr);
      ae->ecommunity = ecomm;
      attr.flag |= ATTR_FLAG_BIT (BGP_ATTR_EXT_COMMUNITIES);
    }

  /* Zap multipath attr nexthop so we set nexthop to self */
  attr.nexthop.s_addr = 0;
#ifdef HAVE_IPV6
  if (attr.extra)
    memset (&attr.extra->mp_nexthop_global, 0, sizeof (struct in6_addr));
#endif /* HAVE_IPV6 */

  /* TODO: should we set ATOMIC_AGGREGATE and AGGREGATOR? */

  new_attr = bgp_attr_intern (&attr);
  bgp_attr_extra_free (&attr);

  if (new_attr != bgp_info_mpath_attr (new_best))
    {
      if ((old_attr = bgp_info_mpath_attr (new_best)))
        bgp_attr_unintern (old_attr);
      bgp_info_mpath_attr_set (new_best, new_attr);
      SET_FLAG (new_best->flags, BGP_INFO_ATTR_CHANGED);
    }
  else
    bgp_attr_unintern (new_attr);
}