bgpd/bgp_nht.c

   1 /* BGP Nexthop tracking
   2  * Copyright (C) 2013 Cumulus Networks, Inc.
   3  *
   4  * This file is part of GNU Zebra.
   5  *
   6  * GNU Zebra is free software; you can redistribute it and/or modify it
   7  * under the terms of the GNU General Public License as published by the
   8  * Free Software Foundation; either version 2, or (at your option) any
   9  * later version.
  10  *
  11  * GNU Zebra is distributed in the hope that it will be useful, but
  12  * WITHOUT ANY WARRANTY; without even the implied warranty of
  13  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  14  * General Public License for more details.
  15  *
  16  * You should have received a copy of the GNU General Public License
  17  * along with GNU Zebra; see the file COPYING.  If not, write to the Free
  18  * Software Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA
  19  * 02111-1307, USA.
  20  */
  21
  22 #include <zebra.h>
  23
  24 #include "command.h"
  25 #include "thread.h"
  26 #include "prefix.h"
  27 #include "zclient.h"
  28 #include "stream.h"
  29 #include "network.h"
  30 #include "log.h"
  31 #include "memory.h"
  32 #include "nexthop.h"
  33 #include "vrf.h"
  34 #include "filter.h"
  35
  36 #include "bgpd/bgpd.h"
  37 #include "bgpd/bgp_table.h"
  38 #include "bgpd/bgp_route.h"
  39 #include "bgpd/bgp_attr.h"
  40 #include "bgpd/bgp_nexthop.h"
  41 #include "bgpd/bgp_debug.h"
  42 #include "bgpd/bgp_nht.h"
  43 #include "bgpd/bgp_fsm.h"
  44 #include "bgpd/bgp_zebra.h"
  45
  46 extern struct zclient *zclient;
  47
  48 static void register_zebra_rnh(struct bgp_nexthop_cache *bnc,
  49                            int is_bgp_static_route);
  50 static void unregister_zebra_rnh(struct bgp_nexthop_cache *bnc,
  51                                  int is_bgp_static_route);
  52 static void evaluate_paths(struct bgp_nexthop_cache *bnc);
  53 static int make_prefix(int afi, struct bgp_info *ri, struct prefix *p);
  54 static void path_nh_map(struct bgp_info *path, struct bgp_nexthop_cache *bnc,
  55                         int keep);
  56
  57 static int
  58 bgp_isvalid_nexthop (struct bgp_nexthop_cache *bnc)
  59 {
  60   return (bgp_zebra_num_connects() == 0 ||
  61           (bnc && CHECK_FLAG(bnc->flags, BGP_NEXTHOP_VALID)));
  62 }
  63
  64 int
  65 bgp_find_nexthop (struct bgp_info *path, int connected)
  66 {
  67   struct bgp_nexthop_cache *bnc = path->nexthop;
  68
  69   if (!bnc)
  70     return 0;
  71
  72   if (connected && !(CHECK_FLAG(bnc->flags, BGP_NEXTHOP_CONNECTED)))
  73     return 0;
  74
  75   return (bgp_isvalid_nexthop(bnc));
  76 }
  77
  78 static void
  79 bgp_unlink_nexthop_check (struct bgp_nexthop_cache *bnc)
  80 {
  81   if (LIST_EMPTY(&(bnc->paths)) && !bnc->nht_info)
  82     {
  83       if (BGP_DEBUG(nht, NHT))
  84         {
  85           char buf[PREFIX2STR_BUFFER];
  86           zlog_debug("bgp_unlink_nexthop: freeing bnc %s",
  87                      bnc_str(bnc, buf, PREFIX2STR_BUFFER));
  88         }
  89       unregister_zebra_rnh(bnc, CHECK_FLAG(bnc->flags, BGP_STATIC_ROUTE));
  90       bnc->node->info = NULL;
  91       bgp_unlock_node(bnc->node);
  92       bnc->node = NULL;
  93       bnc_free(bnc);
  94     }
  95 }
  96
  97 void
  98 bgp_unlink_nexthop (struct bgp_info *path)
  99 {
 100   struct bgp_nexthop_cache *bnc = path->nexthop;
 101
 102   if (!bnc)
 103     return;
 104
 105   path_nh_map(path, NULL, 0);
 106
 107   bgp_unlink_nexthop_check (bnc);
 108 }
 109
 110 void
 111 bgp_unlink_nexthop_by_peer (struct peer *peer)
 112 {
 113   struct prefix p;
 114   struct bgp_node *rn;
 115   struct bgp_nexthop_cache *bnc;
 116   afi_t afi = family2afi(peer->su.sa.sa_family);
 117
 118   if (afi == AFI_IP)
 119     {
 120       p.family = AF_INET;
 121       p.prefixlen = IPV4_MAX_BITLEN;
 122       p.u.prefix4 = peer->su.sin.sin_addr;
 123     }
 124   else if (afi == AFI_IP6)
 125     {
 126       p.family = AF_INET6;
 127       p.prefixlen = IPV6_MAX_BITLEN;
 128       p.u.prefix6 = peer->su.sin6.sin6_addr;
 129     }
 130   else
 131     return;
 132
 133   rn = bgp_node_get (peer->bgp->nexthop_cache_table[afi], &p);
 134
 135   if (!rn->info)
 136     return;
 137
 138   bnc = rn->info;
 139
 140   /* cleanup the peer reference */
 141   bnc->nht_info = NULL;
 142
 143   bgp_unlink_nexthop_check (bnc);
 144 }
 145
 146 int
 147 bgp_find_or_add_nexthop (struct bgp *bgp, afi_t afi, struct bgp_info *ri,
 148                          struct peer *peer, int connected)
 149 {
 150   struct bgp_node *rn;
 151   struct bgp_nexthop_cache *bnc;
 152   struct prefix p;
 153   int is_bgp_static_route = 0;
 154
 155   if (ri)
 156     {
 157       is_bgp_static_route = ((ri->type == ZEBRA_ROUTE_BGP) &&
 158                              (ri->sub_type == BGP_ROUTE_STATIC)) ? 1 : 0;
 159
 160       /* Since Extended Next-hop Encoding (RFC5549) support, we want to derive
 161          address-family from the next-hop. */
 162       if (!is_bgp_static_route)
 163         afi = BGP_ATTR_NEXTHOP_AFI_IP6(ri->attr) ? AFI_IP6 : AFI_IP;
 164
 165       /* This will return TRUE if the global IPv6 NH is a link local addr */
 166       if (make_prefix(afi, ri, &p) < 0)
 167         return 1;
 168     }
 169   else if (peer)
 170     {
 171       if (afi == AFI_IP)
 172         {
 173           p.family = AF_INET;
 174           p.prefixlen = IPV4_MAX_BITLEN;
 175           p.u.prefix4 = peer->su.sin.sin_addr;
 176         }
 177       else if (afi == AFI_IP6)
 178         {
 179           p.family = AF_INET6;
 180           p.prefixlen = IPV6_MAX_BITLEN;
 181           p.u.prefix6 = peer->su.sin6.sin6_addr;
 182
 183           /* Don't register link local NH */
 184           if (IN6_IS_ADDR_LINKLOCAL(&p.u.prefix6))
 185             return 1;
 186         }
 187       else
 188         {
 189           if (BGP_DEBUG(nht, NHT))
 190             {
 191               zlog_debug("%s: Attempting to register with unknown AFI %d (not %d or %d)",
 192                          __FUNCTION__, afi, AFI_IP, AFI_IP6);
 193             }
 194           return 0;
 195         }
 196     }
 197   else
 198     return 0;
 199
 200   if (is_bgp_static_route)
 201     rn = bgp_node_get (bgp->import_check_table[afi], &p);
 202   else
 203     rn = bgp_node_get (bgp->nexthop_cache_table[afi], &p);
 204
 205   if (!rn->info)
 206     {
 207       bnc = bnc_new();
 208       rn->info = bnc;
 209       bnc->node = rn;
 210       bnc->bgp = bgp;
 211       bgp_lock_node(rn);
 212       if (BGP_DEBUG(nht, NHT))
 213         {
 214           char buf[PREFIX2STR_BUFFER];
 215
 216            zlog_debug("Allocated bnc %s peer %p",
 217                      bnc_str(bnc, buf, PREFIX2STR_BUFFER), peer);
 218         }
 219     }
 220
 221   bnc = rn->info;
 222   bgp_unlock_node (rn);
 223
 224   if (is_bgp_static_route)
 225     {
 226       SET_FLAG(bnc->flags, BGP_STATIC_ROUTE);
 227
 228       /* If we're toggling the type, re-register */
 229       if ((bgp_flag_check(bgp, BGP_FLAG_IMPORT_CHECK)) &&
 230           !CHECK_FLAG(bnc->flags, BGP_STATIC_ROUTE_EXACT_MATCH))
 231         {
 232           SET_FLAG(bnc->flags, BGP_STATIC_ROUTE_EXACT_MATCH);
 233           UNSET_FLAG(bnc->flags, BGP_NEXTHOP_REGISTERED);
 234           UNSET_FLAG(bnc->flags, BGP_NEXTHOP_VALID);
 235         }
 236       else if ((!bgp_flag_check(bgp, BGP_FLAG_IMPORT_CHECK)) &&
 237                CHECK_FLAG(bnc->flags, BGP_STATIC_ROUTE_EXACT_MATCH))
 238         {
 239           UNSET_FLAG(bnc->flags, BGP_STATIC_ROUTE_EXACT_MATCH);
 240           UNSET_FLAG(bnc->flags, BGP_NEXTHOP_REGISTERED);
 241           UNSET_FLAG(bnc->flags, BGP_NEXTHOP_VALID);
 242         }
 243     }
 244   /* When nexthop is already known, but now requires 'connected' resolution,
 245    * re-register it. The reverse scenario where the nexthop currently requires
 246    * 'connected' resolution does not need a re-register (i.e., we treat
 247    * 'connected-required' as an override) except in the scenario where this
 248    * is actually a case of tracking a peer for connectivity (e.g., after
 249    * disable connected-check).
 250    * NOTE: We don't track the number of paths separately for 'connected-
 251    * required' vs 'connected-not-required' as this change is not a common
 252    * scenario.
 253    */
 254   else if (connected && ! CHECK_FLAG(bnc->flags, BGP_NEXTHOP_CONNECTED))
 255     {
 256       SET_FLAG(bnc->flags, BGP_NEXTHOP_CONNECTED);
 257       UNSET_FLAG(bnc->flags, BGP_NEXTHOP_REGISTERED);
 258       UNSET_FLAG(bnc->flags, BGP_NEXTHOP_VALID);
 259     }
 260   else if (peer && !connected && CHECK_FLAG(bnc->flags, BGP_NEXTHOP_CONNECTED))
 261     {
 262       UNSET_FLAG(bnc->flags, BGP_NEXTHOP_CONNECTED);
 263       UNSET_FLAG(bnc->flags, BGP_NEXTHOP_REGISTERED);
 264       UNSET_FLAG(bnc->flags, BGP_NEXTHOP_VALID);
 265     }
 266
 267   if (!CHECK_FLAG(bnc->flags, BGP_NEXTHOP_REGISTERED))
 268     register_zebra_rnh(bnc, is_bgp_static_route);
 269
 270   if (ri && ri->nexthop != bnc)
 271     {
 272       /* Unlink from existing nexthop cache, if any. This will also free
 273        * the nexthop cache entry, if appropriate.
 274        */
 275       bgp_unlink_nexthop (ri);
 276
 277       path_nh_map(ri, bnc, 1); /* updates NHT ri list reference */
 278
 279       if (CHECK_FLAG(bnc->flags, BGP_NEXTHOP_VALID) && bnc->metric)
 280         (bgp_info_extra_get(ri))->igpmetric = bnc->metric;
 281       else if (ri->extra)
 282         ri->extra->igpmetric = 0;
 283     }
 284   else if (peer)
 285     bnc->nht_info = (void *)peer; /* NHT peer reference */
 286
 287   return (bgp_isvalid_nexthop(bnc));
 288 }
 289
 290 void
 291 bgp_delete_connected_nexthop (afi_t afi, struct peer *peer)
 292 {
 293   struct bgp_node *rn;
 294   struct bgp_nexthop_cache *bnc;
 295   struct prefix p;
 296
 297   if (!peer)
 298     return;
 299
 300   if (afi == AFI_IP)
 301     {
 302       p.family = AF_INET;
 303       p.prefixlen = IPV4_MAX_BITLEN;
 304       p.u.prefix4 = peer->su.sin.sin_addr;
 305     }
 306   else if (afi == AFI_IP6)
 307     {
 308       p.family = AF_INET6;
 309       p.prefixlen = IPV6_MAX_BITLEN;
 310       p.u.prefix6 = peer->su.sin6.sin6_addr;
 311
 312       /* We don't register link local address for NHT */
 313       if (IN6_IS_ADDR_LINKLOCAL(&p.u.prefix6))
 314         return;
 315     }
 316   else
 317     return;
 318
 319   rn = bgp_node_lookup(peer->bgp->nexthop_cache_table[family2afi(p.family)], &p);
 320   if (!rn || !rn->info)
 321     {
 322       if (BGP_DEBUG(nht, NHT))
 323         zlog_debug("Cannot find connected NHT node for peer %s", peer->host);
 324       if (rn)
 325         bgp_unlock_node (rn);
 326       return;
 327     }
 328
 329   bnc = rn->info;
 330   bgp_unlock_node(rn);
 331
 332   if (bnc->nht_info != peer)
 333     {
 334       if (BGP_DEBUG(nht, NHT))
 335         zlog_debug("Connected NHT %p node for peer %s points to %p",
 336                     bnc, peer->host, bnc->nht_info);
 337       return;
 338     }
 339
 340   bnc->nht_info = NULL;
 341
 342   if (LIST_EMPTY(&(bnc->paths)))
 343     {
 344       if (BGP_DEBUG(nht, NHT))
 345         zlog_debug("Freeing connected NHT node %p for peer %s",
 346                     bnc,  peer->host);
 347       unregister_zebra_rnh(bnc, 0);
 348       bnc->node->info = NULL;
 349       bgp_unlock_node(bnc->node);
 350       bnc_free(bnc);
 351     }
 352 }
 353
 354 void
 355 bgp_parse_nexthop_update (int command, vrf_id_t vrf_id)
 356 {
 357   struct stream *s;
 358   struct bgp_node *rn = NULL;
 359   struct bgp_nexthop_cache *bnc;
 360   struct nexthop *nexthop;
 361   struct nexthop *oldnh;
 362   struct nexthop *nhlist_head = NULL;
 363   struct nexthop *nhlist_tail = NULL;
 364   uint32_t metric;
 365   u_char nexthop_num;
 366   struct prefix p;
 367   int i;
 368   struct bgp *bgp;
 369
 370   bgp = bgp_lookup_by_vrf_id (vrf_id);
 371   if (!bgp)
 372     {
 373       zlog_err("parse nexthop update: instance not found for vrf_id %d", vrf_id);
 374       return;
 375     }
 376
 377   s = zclient->ibuf;
 378
 379   memset(&p, 0, sizeof(struct prefix));
 380   p.family = stream_getw(s);
 381   p.prefixlen = stream_getc(s);
 382   switch (p.family)
 383     {
 384     case AF_INET:
 385       p.u.prefix4.s_addr = stream_get_ipv4 (s);
 386       break;
 387     case AF_INET6:
 388       stream_get(&p.u.prefix6, s, 16);
 389       break;
 390     default:
 391       break;
 392     }
 393
 394   if (command == ZEBRA_NEXTHOP_UPDATE)
 395     rn = bgp_node_lookup(bgp->nexthop_cache_table[family2afi(p.family)], &p);
 396   else if (command == ZEBRA_IMPORT_CHECK_UPDATE)
 397     rn = bgp_node_lookup(bgp->import_check_table[family2afi(p.family)], &p);
 398
 399   if (!rn || !rn->info)
 400     {
 401       if (BGP_DEBUG(nht, NHT))
 402         {
 403           char buf[PREFIX2STR_BUFFER];
 404           prefix2str(&p, buf, sizeof(buf));
 405           zlog_debug("parse nexthop update(%s): rn not found", buf);
 406         }
 407       if (rn)
 408         bgp_unlock_node (rn);
 409       return;
 410     }
 411
 412   bnc = rn->info;
 413   bgp_unlock_node (rn);
 414   bnc->last_update = bgp_clock();
 415   bnc->change_flags = 0;
 416   metric = stream_getl (s);
 417   nexthop_num = stream_getc (s);
 418
 419   /* debug print the input */
 420   if (BGP_DEBUG(nht, NHT))
 421     {
 422       char buf[PREFIX2STR_BUFFER];
 423       prefix2str(&p, buf, sizeof (buf));
 424       zlog_debug("%d: NH update for %s - metric %d (cur %d) #nhops %d (cur %d)",
 425                  vrf_id, buf, metric, bnc->metric, nexthop_num, bnc->nexthop_num);
 426     }
 427
 428   if (metric != bnc->metric)
 429     bnc->change_flags |= BGP_NEXTHOP_METRIC_CHANGED;
 430
 431   if(nexthop_num != bnc->nexthop_num)
 432     bnc->change_flags |= BGP_NEXTHOP_CHANGED;
 433
 434   if (nexthop_num)
 435     {
 436       /* notify bgp fsm if nbr ip goes from invalid->valid */
 437       if (!bnc->nexthop_num)
 438         UNSET_FLAG(bnc->flags, BGP_NEXTHOP_PEER_NOTIFIED);
 439
 440       bnc->flags |= BGP_NEXTHOP_VALID;
 441       bnc->metric = metric;
 442       bnc->nexthop_num = nexthop_num;
 443
 444       for (i = 0; i < nexthop_num; i++)
 445         {
 446           nexthop = nexthop_new();
 447           nexthop->type = stream_getc (s);
 448           switch (nexthop->type)
 449             {
 450             case NEXTHOP_TYPE_IPV4:
 451               nexthop->gate.ipv4.s_addr = stream_get_ipv4 (s);
 452               break;
 453             case NEXTHOP_TYPE_IFINDEX:
 454               nexthop->ifindex = stream_getl (s);
 455               break;
 456             case NEXTHOP_TYPE_IPV4_IFINDEX:
 457               nexthop->gate.ipv4.s_addr = stream_get_ipv4 (s);
 458               nexthop->ifindex = stream_getl (s);
 459               break;
 460             case NEXTHOP_TYPE_IPV6:
 461               stream_get (&nexthop->gate.ipv6, s, 16);
 462               break;
 463             case NEXTHOP_TYPE_IPV6_IFINDEX:
 464               stream_get (&nexthop->gate.ipv6, s, 16);
 465               nexthop->ifindex = stream_getl (s);
 466               break;
 467             default:
 468               /* do nothing */
 469               break;
 470             }
 471
 472           if (BGP_DEBUG(nht, NHT))
 473             {
 474               char buf[NEXTHOP_STRLEN];
 475               zlog_debug("    nhop via %s",
 476                          nexthop2str (nexthop, buf, sizeof (buf)));
 477             }
 478
 479           if (nhlist_tail)
 480             {
 481               nhlist_tail->next = nexthop;
 482               nhlist_tail = nexthop;
 483             }
 484           else
 485             {
 486               nhlist_tail = nexthop;
 487               nhlist_head = nexthop;
 488             }
 489
 490           /* No need to evaluate the nexthop if we have already determined
 491            * that there has been a change.
 492            */
 493           if (bnc->change_flags & BGP_NEXTHOP_CHANGED)
 494             continue;
 495
 496           for (oldnh = bnc->nexthop; oldnh; oldnh = oldnh->next)
 497               if (nexthop_same_no_recurse(oldnh, nexthop))
 498                   break;
 499
 500           if (!oldnh)
 501             bnc->change_flags |= BGP_NEXTHOP_CHANGED;
 502         }
 503       bnc_nexthop_free(bnc);
 504       bnc->nexthop = nhlist_head;
 505     }
 506   else
 507     {
 508       bnc->flags &= ~BGP_NEXTHOP_VALID;
 509       bnc->nexthop_num = nexthop_num;
 510
 511       /* notify bgp fsm if nbr ip goes from valid->invalid */
 512       UNSET_FLAG(bnc->flags, BGP_NEXTHOP_PEER_NOTIFIED);
 513
 514       bnc_nexthop_free(bnc);
 515       bnc->nexthop = NULL;
 516     }
 517
 518   evaluate_paths(bnc);
 519 }
 520
 521 /**
 522  * make_prefix - make a prefix structure from the path (essentially
 523  * path's node.
 524  */
 525 static int
 526 make_prefix (int afi, struct bgp_info *ri, struct prefix *p)
 527 {
 528
 529   int is_bgp_static = ((ri->type == ZEBRA_ROUTE_BGP) &&
 530                        (ri->sub_type == BGP_ROUTE_STATIC)) ? 1 : 0;
 531
 532   memset (p, 0, sizeof (struct prefix));
 533   switch (afi)
 534     {
 535     case AFI_IP:
 536       p->family = AF_INET;
 537       if (is_bgp_static)
 538         {
 539           p->u.prefix4 = ri->net->p.u.prefix4;
 540           p->prefixlen = ri->net->p.prefixlen;
 541         }
 542       else
 543         {
 544           p->u.prefix4 = ri->attr->nexthop;
 545           p->prefixlen = IPV4_MAX_BITLEN;
 546         }
 547       break;
 548 #ifdef HAVE_IPV6
 549     case AFI_IP6:
 550       /* We don't register link local NH */
 551       if (ri->attr->extra->mp_nexthop_len != BGP_ATTR_NHLEN_IPV6_GLOBAL
 552           || IN6_IS_ADDR_LINKLOCAL (&ri->attr->extra->mp_nexthop_global))
 553         return -1;
 554
 555       p->family = AF_INET6;
 556
 557       if (is_bgp_static)
 558         {
 559           p->u.prefix6 = ri->net->p.u.prefix6;
 560           p->prefixlen = ri->net->p.prefixlen;
 561         }
 562       else
 563         {
 564           p->u.prefix6 = ri->attr->extra->mp_nexthop_global;
 565           p->prefixlen = IPV6_MAX_BITLEN;
 566         }
 567       break;
 568 #endif
 569     default:
 570       if (BGP_DEBUG(nht, NHT))
 571         {
 572           zlog_debug("%s: Attempting to make prefix with unknown AFI %d (not %d or %d)",
 573                      __FUNCTION__, afi, AFI_IP, AFI_IP6);
 574         }
 575       break;
 576     }
 577   return 0;
 578 }
 579
 580 /**
 581  * sendmsg_zebra_rnh -- Format and send a nexthop register/Unregister
 582  *   command to Zebra.
 583  * ARGUMENTS:
 584  *   struct bgp_nexthop_cache *bnc -- the nexthop structure.
 585  *   int command -- command to send to zebra
 586  * RETURNS:
 587  *   void.
 588  */
 589 static void
 590 sendmsg_zebra_rnh (struct bgp_nexthop_cache *bnc, int command)
 591 {
 592   struct stream *s;
 593   struct prefix *p;
 594   int ret;
 595
 596   /* Check socket. */
 597   if (!zclient || zclient->sock < 0)
 598     return;
 599
 600   /* Don't try to register if Zebra doesn't know of this instance. */
 601   if (!IS_BGP_INST_KNOWN_TO_ZEBRA(bnc->bgp))
 602     return;
 603
 604   p = &(bnc->node->p);
 605   s = zclient->obuf;
 606   stream_reset (s);
 607   zclient_create_header (s, command, bnc->bgp->vrf_id);
 608   if (CHECK_FLAG(bnc->flags, BGP_NEXTHOP_CONNECTED) ||
 609       CHECK_FLAG(bnc->flags, BGP_STATIC_ROUTE_EXACT_MATCH))
 610     stream_putc(s, 1);
 611   else
 612     stream_putc(s, 0);
 613
 614   stream_putw(s, PREFIX_FAMILY(p));
 615   stream_putc(s, p->prefixlen);
 616   switch (PREFIX_FAMILY(p))
 617     {
 618     case AF_INET:
 619       stream_put_in_addr (s, &p->u.prefix4);
 620       break;
 621 #ifdef HAVE_IPV6
 622     case AF_INET6:
 623       stream_put(s, &(p->u.prefix6), 16);
 624       break;
 625 #endif
 626     default:
 627       break;
 628     }
 629   stream_putw_at (s, 0, stream_get_endp (s));
 630
 631   ret = zclient_send_message(zclient);
 632   /* TBD: handle the failure */
 633   if (ret < 0)
 634     zlog_warn("sendmsg_nexthop: zclient_send_message() failed");
 635
 636   if ((command == ZEBRA_NEXTHOP_REGISTER) ||
 637       (command == ZEBRA_IMPORT_ROUTE_REGISTER))
 638     SET_FLAG(bnc->flags, BGP_NEXTHOP_REGISTERED);
 639   else if ((command == ZEBRA_NEXTHOP_UNREGISTER) ||
 640            (command == ZEBRA_IMPORT_ROUTE_UNREGISTER))
 641     UNSET_FLAG(bnc->flags, BGP_NEXTHOP_REGISTERED);
 642   return;
 643 }
 644
 645 /**
 646  * register_zebra_rnh - register a NH/route with Zebra for notification
 647  *    when the route or the route to the nexthop changes.
 648  * ARGUMENTS:
 649  *   struct bgp_nexthop_cache *bnc
 650  * RETURNS:
 651  *   void.
 652  */
 653 static void
 654 register_zebra_rnh (struct bgp_nexthop_cache *bnc, int is_bgp_import_route)
 655 {
 656   /* Check if we have already registered */
 657   if (bnc->flags & BGP_NEXTHOP_REGISTERED)
 658     return;
 659   if (is_bgp_import_route)
 660     sendmsg_zebra_rnh(bnc, ZEBRA_IMPORT_ROUTE_REGISTER);
 661   else
 662     sendmsg_zebra_rnh(bnc, ZEBRA_NEXTHOP_REGISTER);
 663 }
 664
 665 /**
 666  * unregister_zebra_rnh -- Unregister the route/nexthop from Zebra.
 667  * ARGUMENTS:
 668  *   struct bgp_nexthop_cache *bnc
 669  * RETURNS:
 670  *   void.
 671  */
 672 static void
 673 unregister_zebra_rnh (struct bgp_nexthop_cache *bnc, int is_bgp_import_route)
 674 {
 675   /* Check if we have already registered */
 676   if (!CHECK_FLAG(bnc->flags, BGP_NEXTHOP_REGISTERED))
 677     return;
 678
 679   if (is_bgp_import_route)
 680     sendmsg_zebra_rnh(bnc, ZEBRA_IMPORT_ROUTE_UNREGISTER);
 681   else
 682     sendmsg_zebra_rnh(bnc, ZEBRA_NEXTHOP_UNREGISTER);
 683 }
 684
 685 /**
 686  * evaluate_paths - Evaluate the paths/nets associated with a nexthop.
 687  * ARGUMENTS:
 688  *   struct bgp_nexthop_cache *bnc -- the nexthop structure.
 689  * RETURNS:
 690  *   void.
 691  */
 692 static void
 693 evaluate_paths (struct bgp_nexthop_cache *bnc)
 694 {
 695   struct bgp_node *rn;
 696   struct bgp_info *path;
 697   struct bgp *bgp = bnc->bgp;
 698   int afi;
 699   struct peer *peer = (struct peer *)bnc->nht_info;
 700
 701   if (BGP_DEBUG(nht, NHT))
 702     {
 703       char buf[PREFIX2STR_BUFFER];
 704       bnc_str(bnc, buf, PREFIX2STR_BUFFER);
 705       zlog_debug("NH update for %s - flags 0x%x chgflags 0x%x - evaluate paths",
 706                  buf, bnc->flags, bnc->change_flags);
 707     }
 708
 709   LIST_FOREACH(path, &(bnc->paths), nh_thread)
 710     {
 711       if (!(path->type == ZEBRA_ROUTE_BGP &&
 712             ((path->sub_type == BGP_ROUTE_NORMAL) ||
 713              (path->sub_type == BGP_ROUTE_STATIC))))
 714         continue;
 715
 716       rn = path->net;
 717       afi = family2afi(rn->p.family);
 718
 719       /* Path becomes valid/invalid depending on whether the nexthop
 720        * reachable/unreachable.
 721        */
 722       if ((CHECK_FLAG(path->flags, BGP_INFO_VALID) ? 1 : 0) !=
 723           (bgp_isvalid_nexthop(bnc) ? 1 : 0))
 724         {
 725           if (CHECK_FLAG (path->flags, BGP_INFO_VALID))
 726             {
 727               bgp_aggregate_decrement (bgp, &rn->p, path,
 728                                        afi, SAFI_UNICAST);
 729               bgp_info_unset_flag (rn, path, BGP_INFO_VALID);
 730             }
 731           else
 732             {
 733               bgp_info_set_flag (rn, path, BGP_INFO_VALID);
 734               bgp_aggregate_increment (bgp, &rn->p, path,
 735                                        afi, SAFI_UNICAST);
 736             }
 737         }
 738
 739       /* Copy the metric to the path. Will be used for bestpath computation */
 740       if (bgp_isvalid_nexthop(bnc) && bnc->metric)
 741         (bgp_info_extra_get(path))->igpmetric = bnc->metric;
 742       else if (path->extra)
 743         path->extra->igpmetric = 0;
 744
 745       if (CHECK_FLAG(bnc->change_flags, BGP_NEXTHOP_METRIC_CHANGED) ||
 746           CHECK_FLAG(bnc->change_flags, BGP_NEXTHOP_CHANGED))
 747         SET_FLAG(path->flags, BGP_INFO_IGP_CHANGED);
 748
 749       bgp_process(bgp, rn, afi, SAFI_UNICAST);
 750     }
 751
 752   if (peer && !CHECK_FLAG(bnc->flags, BGP_NEXTHOP_PEER_NOTIFIED))
 753     {
 754       if (BGP_DEBUG(nht, NHT))
 755         zlog_debug("%s: Updating peer (%s) status with NHT", __FUNCTION__, peer->host);
 756       bgp_fsm_nht_update(peer, bgp_isvalid_nexthop(bnc));
 757       SET_FLAG(bnc->flags, BGP_NEXTHOP_PEER_NOTIFIED);
 758     }
 759
 760   RESET_FLAG(bnc->change_flags);
 761 }
 762
 763 /**
 764  * path_nh_map - make or break path-to-nexthop association.
 765  * ARGUMENTS:
 766  *   path - pointer to the path structure
 767  *   bnc - pointer to the nexthop structure
 768  *   make - if set, make the association. if unset, just break the existing
 769  *          association.
 770  */
 771 static void
 772 path_nh_map (struct bgp_info *path, struct bgp_nexthop_cache *bnc, int make)
 773 {
 774   if (path->nexthop)
 775     {
 776       LIST_REMOVE(path, nh_thread);
 777       path->nexthop->path_count--;
 778       path->nexthop = NULL;
 779     }
 780   if (make)
 781     {
 782       LIST_INSERT_HEAD(&(bnc->paths), path, nh_thread);
 783       path->nexthop = bnc;
 784       path->nexthop->path_count++;
 785     }
 786 }