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 (! sockunion2hostprefix (&peer->su, &p))
 119     return;
 120
 121   rn = bgp_node_get (peer->bgp->nexthop_cache_table[afi], &p);
 122
 123   if (!rn->info)
 124     return;
 125
 126   bnc = rn->info;
 127
 128   /* cleanup the peer reference */
 129   bnc->nht_info = NULL;
 130
 131   bgp_unlink_nexthop_check (bnc);
 132 }
 133
 134 int
 135 bgp_find_or_add_nexthop (struct bgp *bgp, afi_t afi, struct bgp_info *ri,
 136                          struct peer *peer, int connected)
 137 {
 138   struct bgp_node *rn;
 139   struct bgp_nexthop_cache *bnc;
 140   struct prefix p;
 141   int is_bgp_static_route = 0;
 142
 143   if (ri)
 144     {
 145       is_bgp_static_route = ((ri->type == ZEBRA_ROUTE_BGP) &&
 146                              (ri->sub_type == BGP_ROUTE_STATIC)) ? 1 : 0;
 147
 148       /* Since Extended Next-hop Encoding (RFC5549) support, we want to derive
 149          address-family from the next-hop. */
 150       if (!is_bgp_static_route)
 151         afi = BGP_ATTR_NEXTHOP_AFI_IP6(ri->attr) ? AFI_IP6 : AFI_IP;
 152
 153       /* This will return TRUE if the global IPv6 NH is a link local addr */
 154       if (make_prefix(afi, ri, &p) < 0)
 155         return 1;
 156     }
 157   else if (peer)
 158     {
 159       /* Don't register link local NH */
 160       if (afi == AFI_IP6 && IN6_IS_ADDR_LINKLOCAL (&peer->su.sin6.sin6_addr))
 161         return 1;
 162
 163       if (! sockunion2hostprefix (&peer->su, &p))
 164         {
 165           if (BGP_DEBUG(nht, NHT))
 166             {
 167               zlog_debug("%s: Attempting to register with unknown AFI %d (not %d or %d)",
 168                          __FUNCTION__, afi, AFI_IP, AFI_IP6);
 169             }
 170           return 0;
 171         }
 172     }
 173   else
 174     return 0;
 175
 176   if (is_bgp_static_route)
 177     rn = bgp_node_get (bgp->import_check_table[afi], &p);
 178   else
 179     rn = bgp_node_get (bgp->nexthop_cache_table[afi], &p);
 180
 181   if (!rn->info)
 182     {
 183       bnc = bnc_new();
 184       rn->info = bnc;
 185       bnc->node = rn;
 186       bnc->bgp = bgp;
 187       bgp_lock_node(rn);
 188       if (BGP_DEBUG(nht, NHT))
 189         {
 190           char buf[PREFIX2STR_BUFFER];
 191
 192            zlog_debug("Allocated bnc %s peer %p",
 193                      bnc_str(bnc, buf, PREFIX2STR_BUFFER), peer);
 194         }
 195     }
 196
 197   bnc = rn->info;
 198   bgp_unlock_node (rn);
 199
 200   if (is_bgp_static_route)
 201     {
 202       SET_FLAG(bnc->flags, BGP_STATIC_ROUTE);
 203
 204       /* If we're toggling the type, re-register */
 205       if ((bgp_flag_check(bgp, BGP_FLAG_IMPORT_CHECK)) &&
 206           !CHECK_FLAG(bnc->flags, BGP_STATIC_ROUTE_EXACT_MATCH))
 207         {
 208           SET_FLAG(bnc->flags, BGP_STATIC_ROUTE_EXACT_MATCH);
 209           UNSET_FLAG(bnc->flags, BGP_NEXTHOP_REGISTERED);
 210           UNSET_FLAG(bnc->flags, BGP_NEXTHOP_VALID);
 211         }
 212       else if ((!bgp_flag_check(bgp, BGP_FLAG_IMPORT_CHECK)) &&
 213                CHECK_FLAG(bnc->flags, BGP_STATIC_ROUTE_EXACT_MATCH))
 214         {
 215           UNSET_FLAG(bnc->flags, BGP_STATIC_ROUTE_EXACT_MATCH);
 216           UNSET_FLAG(bnc->flags, BGP_NEXTHOP_REGISTERED);
 217           UNSET_FLAG(bnc->flags, BGP_NEXTHOP_VALID);
 218         }
 219     }
 220   /* When nexthop is already known, but now requires 'connected' resolution,
 221    * re-register it. The reverse scenario where the nexthop currently requires
 222    * 'connected' resolution does not need a re-register (i.e., we treat
 223    * 'connected-required' as an override) except in the scenario where this
 224    * is actually a case of tracking a peer for connectivity (e.g., after
 225    * disable connected-check).
 226    * NOTE: We don't track the number of paths separately for 'connected-
 227    * required' vs 'connected-not-required' as this change is not a common
 228    * scenario.
 229    */
 230   else if (connected && ! CHECK_FLAG(bnc->flags, BGP_NEXTHOP_CONNECTED))
 231     {
 232       SET_FLAG(bnc->flags, BGP_NEXTHOP_CONNECTED);
 233       UNSET_FLAG(bnc->flags, BGP_NEXTHOP_REGISTERED);
 234       UNSET_FLAG(bnc->flags, BGP_NEXTHOP_VALID);
 235     }
 236   else if (peer && !connected && CHECK_FLAG(bnc->flags, BGP_NEXTHOP_CONNECTED))
 237     {
 238       UNSET_FLAG(bnc->flags, BGP_NEXTHOP_CONNECTED);
 239       UNSET_FLAG(bnc->flags, BGP_NEXTHOP_REGISTERED);
 240       UNSET_FLAG(bnc->flags, BGP_NEXTHOP_VALID);
 241     }
 242
 243   if (!CHECK_FLAG(bnc->flags, BGP_NEXTHOP_REGISTERED))
 244     register_zebra_rnh(bnc, is_bgp_static_route);
 245
 246   if (ri && ri->nexthop != bnc)
 247     {
 248       /* Unlink from existing nexthop cache, if any. This will also free
 249        * the nexthop cache entry, if appropriate.
 250        */
 251       bgp_unlink_nexthop (ri);
 252
 253       path_nh_map(ri, bnc, 1); /* updates NHT ri list reference */
 254
 255       if (CHECK_FLAG(bnc->flags, BGP_NEXTHOP_VALID) && bnc->metric)
 256         (bgp_info_extra_get(ri))->igpmetric = bnc->metric;
 257       else if (ri->extra)
 258         ri->extra->igpmetric = 0;
 259     }
 260   else if (peer)
 261     bnc->nht_info = (void *)peer; /* NHT peer reference */
 262
 263   return (bgp_isvalid_nexthop(bnc));
 264 }
 265
 266 void
 267 bgp_delete_connected_nexthop (afi_t afi, struct peer *peer)
 268 {
 269   struct bgp_node *rn;
 270   struct bgp_nexthop_cache *bnc;
 271   struct prefix p;
 272
 273   if (!peer)
 274     return;
 275
 276   /* We don't register link local address for NHT */
 277   if (afi == AFI_IP6 && IN6_IS_ADDR_LINKLOCAL (&peer->su.sin6.sin6_addr))
 278     return;
 279
 280   if (! sockunion2hostprefix (&peer->su, &p))
 281     return;
 282
 283   rn = bgp_node_lookup(peer->bgp->nexthop_cache_table[family2afi(p.family)], &p);
 284   if (!rn || !rn->info)
 285     {
 286       if (BGP_DEBUG(nht, NHT))
 287         zlog_debug("Cannot find connected NHT node for peer %s", peer->host);
 288       if (rn)
 289         bgp_unlock_node (rn);
 290       return;
 291     }
 292
 293   bnc = rn->info;
 294   bgp_unlock_node(rn);
 295
 296   if (bnc->nht_info != peer)
 297     {
 298       if (BGP_DEBUG(nht, NHT))
 299         zlog_debug("Connected NHT %p node for peer %s points to %p",
 300                     bnc, peer->host, bnc->nht_info);
 301       return;
 302     }
 303
 304   bnc->nht_info = NULL;
 305
 306   if (LIST_EMPTY(&(bnc->paths)))
 307     {
 308       if (BGP_DEBUG(nht, NHT))
 309         zlog_debug("Freeing connected NHT node %p for peer %s",
 310                     bnc,  peer->host);
 311       unregister_zebra_rnh(bnc, 0);
 312       bnc->node->info = NULL;
 313       bgp_unlock_node(bnc->node);
 314       bnc_free(bnc);
 315     }
 316 }
 317
 318 void
 319 bgp_parse_nexthop_update (int command, vrf_id_t vrf_id)
 320 {
 321   struct stream *s;
 322   struct bgp_node *rn = NULL;
 323   struct bgp_nexthop_cache *bnc;
 324   struct nexthop *nexthop;
 325   struct nexthop *oldnh;
 326   struct nexthop *nhlist_head = NULL;
 327   struct nexthop *nhlist_tail = NULL;
 328   uint32_t metric;
 329   u_char nexthop_num;
 330   struct prefix p;
 331   int i;
 332   struct bgp *bgp;
 333
 334   bgp = bgp_lookup_by_vrf_id (vrf_id);
 335   if (!bgp)
 336     {
 337       zlog_err("parse nexthop update: instance not found for vrf_id %d", vrf_id);
 338       return;
 339     }
 340
 341   s = zclient->ibuf;
 342
 343   memset(&p, 0, sizeof(struct prefix));
 344   p.family = stream_getw(s);
 345   p.prefixlen = stream_getc(s);
 346   switch (p.family)
 347     {
 348     case AF_INET:
 349       p.u.prefix4.s_addr = stream_get_ipv4 (s);
 350       break;
 351     case AF_INET6:
 352       stream_get(&p.u.prefix6, s, 16);
 353       break;
 354     default:
 355       break;
 356     }
 357
 358   if (command == ZEBRA_NEXTHOP_UPDATE)
 359     rn = bgp_node_lookup(bgp->nexthop_cache_table[family2afi(p.family)], &p);
 360   else if (command == ZEBRA_IMPORT_CHECK_UPDATE)
 361     rn = bgp_node_lookup(bgp->import_check_table[family2afi(p.family)], &p);
 362
 363   if (!rn || !rn->info)
 364     {
 365       if (BGP_DEBUG(nht, NHT))
 366         {
 367           char buf[PREFIX2STR_BUFFER];
 368           prefix2str(&p, buf, sizeof(buf));
 369           zlog_debug("parse nexthop update(%s): rn not found", buf);
 370         }
 371       if (rn)
 372         bgp_unlock_node (rn);
 373       return;
 374     }
 375
 376   bnc = rn->info;
 377   bgp_unlock_node (rn);
 378   bnc->last_update = bgp_clock();
 379   bnc->change_flags = 0;
 380   metric = stream_getl (s);
 381   nexthop_num = stream_getc (s);
 382
 383   /* debug print the input */
 384   if (BGP_DEBUG(nht, NHT))
 385     {
 386       char buf[PREFIX2STR_BUFFER];
 387       prefix2str(&p, buf, sizeof (buf));
 388       zlog_debug("%d: NH update for %s - metric %d (cur %d) #nhops %d (cur %d)",
 389                  vrf_id, buf, metric, bnc->metric, nexthop_num, bnc->nexthop_num);
 390     }
 391
 392   if (metric != bnc->metric)
 393     bnc->change_flags |= BGP_NEXTHOP_METRIC_CHANGED;
 394
 395   if(nexthop_num != bnc->nexthop_num)
 396     bnc->change_flags |= BGP_NEXTHOP_CHANGED;
 397
 398   if (nexthop_num)
 399     {
 400       /* notify bgp fsm if nbr ip goes from invalid->valid */
 401       if (!bnc->nexthop_num)
 402         UNSET_FLAG(bnc->flags, BGP_NEXTHOP_PEER_NOTIFIED);
 403
 404       bnc->flags |= BGP_NEXTHOP_VALID;
 405       bnc->metric = metric;
 406       bnc->nexthop_num = nexthop_num;
 407
 408       for (i = 0; i < nexthop_num; i++)
 409         {
 410           nexthop = nexthop_new();
 411           nexthop->type = stream_getc (s);
 412           switch (nexthop->type)
 413             {
 414             case NEXTHOP_TYPE_IPV4:
 415               nexthop->gate.ipv4.s_addr = stream_get_ipv4 (s);
 416               break;
 417             case NEXTHOP_TYPE_IFINDEX:
 418               nexthop->ifindex = stream_getl (s);
 419               break;
 420             case NEXTHOP_TYPE_IPV4_IFINDEX:
 421               nexthop->gate.ipv4.s_addr = stream_get_ipv4 (s);
 422               nexthop->ifindex = stream_getl (s);
 423               break;
 424             case NEXTHOP_TYPE_IPV6:
 425               stream_get (&nexthop->gate.ipv6, s, 16);
 426               break;
 427             case NEXTHOP_TYPE_IPV6_IFINDEX:
 428               stream_get (&nexthop->gate.ipv6, s, 16);
 429               nexthop->ifindex = stream_getl (s);
 430               break;
 431             default:
 432               /* do nothing */
 433               break;
 434             }
 435
 436           if (BGP_DEBUG(nht, NHT))
 437             {
 438               char buf[NEXTHOP_STRLEN];
 439               zlog_debug("    nhop via %s",
 440                          nexthop2str (nexthop, buf, sizeof (buf)));
 441             }
 442
 443           if (nhlist_tail)
 444             {
 445               nhlist_tail->next = nexthop;
 446               nhlist_tail = nexthop;
 447             }
 448           else
 449             {
 450               nhlist_tail = nexthop;
 451               nhlist_head = nexthop;
 452             }
 453
 454           /* No need to evaluate the nexthop if we have already determined
 455            * that there has been a change.
 456            */
 457           if (bnc->change_flags & BGP_NEXTHOP_CHANGED)
 458             continue;
 459
 460           for (oldnh = bnc->nexthop; oldnh; oldnh = oldnh->next)
 461               if (nexthop_same_no_recurse(oldnh, nexthop))
 462                   break;
 463
 464           if (!oldnh)
 465             bnc->change_flags |= BGP_NEXTHOP_CHANGED;
 466         }
 467       bnc_nexthop_free(bnc);
 468       bnc->nexthop = nhlist_head;
 469     }
 470   else
 471     {
 472       bnc->flags &= ~BGP_NEXTHOP_VALID;
 473       bnc->nexthop_num = nexthop_num;
 474
 475       /* notify bgp fsm if nbr ip goes from valid->invalid */
 476       UNSET_FLAG(bnc->flags, BGP_NEXTHOP_PEER_NOTIFIED);
 477
 478       bnc_nexthop_free(bnc);
 479       bnc->nexthop = NULL;
 480     }
 481
 482   evaluate_paths(bnc);
 483 }
 484
 485 /**
 486  * make_prefix - make a prefix structure from the path (essentially
 487  * path's node.
 488  */
 489 static int
 490 make_prefix (int afi, struct bgp_info *ri, struct prefix *p)
 491 {
 492
 493   int is_bgp_static = ((ri->type == ZEBRA_ROUTE_BGP) &&
 494                        (ri->sub_type == BGP_ROUTE_STATIC)) ? 1 : 0;
 495
 496   memset (p, 0, sizeof (struct prefix));
 497   switch (afi)
 498     {
 499     case AFI_IP:
 500       p->family = AF_INET;
 501       if (is_bgp_static)
 502         {
 503           p->u.prefix4 = ri->net->p.u.prefix4;
 504           p->prefixlen = ri->net->p.prefixlen;
 505         }
 506       else
 507         {
 508           p->u.prefix4 = ri->attr->nexthop;
 509           p->prefixlen = IPV4_MAX_BITLEN;
 510         }
 511       break;
 512 #ifdef HAVE_IPV6
 513     case AFI_IP6:
 514       /* We don't register link local NH */
 515       if (ri->attr->extra->mp_nexthop_len != BGP_ATTR_NHLEN_IPV6_GLOBAL
 516           || IN6_IS_ADDR_LINKLOCAL (&ri->attr->extra->mp_nexthop_global))
 517         return -1;
 518
 519       p->family = AF_INET6;
 520
 521       if (is_bgp_static)
 522         {
 523           p->u.prefix6 = ri->net->p.u.prefix6;
 524           p->prefixlen = ri->net->p.prefixlen;
 525         }
 526       else
 527         {
 528           p->u.prefix6 = ri->attr->extra->mp_nexthop_global;
 529           p->prefixlen = IPV6_MAX_BITLEN;
 530         }
 531       break;
 532 #endif
 533     default:
 534       if (BGP_DEBUG(nht, NHT))
 535         {
 536           zlog_debug("%s: Attempting to make prefix with unknown AFI %d (not %d or %d)",
 537                      __FUNCTION__, afi, AFI_IP, AFI_IP6);
 538         }
 539       break;
 540     }
 541   return 0;
 542 }
 543
 544 /**
 545  * sendmsg_zebra_rnh -- Format and send a nexthop register/Unregister
 546  *   command to Zebra.
 547  * ARGUMENTS:
 548  *   struct bgp_nexthop_cache *bnc -- the nexthop structure.
 549  *   int command -- command to send to zebra
 550  * RETURNS:
 551  *   void.
 552  */
 553 static void
 554 sendmsg_zebra_rnh (struct bgp_nexthop_cache *bnc, int command)
 555 {
 556   struct stream *s;
 557   struct prefix *p;
 558   int ret;
 559
 560   /* Check socket. */
 561   if (!zclient || zclient->sock < 0)
 562     return;
 563
 564   /* Don't try to register if Zebra doesn't know of this instance. */
 565   if (!IS_BGP_INST_KNOWN_TO_ZEBRA(bnc->bgp))
 566     return;
 567
 568   p = &(bnc->node->p);
 569   s = zclient->obuf;
 570   stream_reset (s);
 571   zclient_create_header (s, command, bnc->bgp->vrf_id);
 572   if (CHECK_FLAG(bnc->flags, BGP_NEXTHOP_CONNECTED) ||
 573       CHECK_FLAG(bnc->flags, BGP_STATIC_ROUTE_EXACT_MATCH))
 574     stream_putc(s, 1);
 575   else
 576     stream_putc(s, 0);
 577
 578   stream_putw(s, PREFIX_FAMILY(p));
 579   stream_putc(s, p->prefixlen);
 580   switch (PREFIX_FAMILY(p))
 581     {
 582     case AF_INET:
 583       stream_put_in_addr (s, &p->u.prefix4);
 584       break;
 585 #ifdef HAVE_IPV6
 586     case AF_INET6:
 587       stream_put(s, &(p->u.prefix6), 16);
 588       break;
 589 #endif
 590     default:
 591       break;
 592     }
 593   stream_putw_at (s, 0, stream_get_endp (s));
 594
 595   ret = zclient_send_message(zclient);
 596   /* TBD: handle the failure */
 597   if (ret < 0)
 598     zlog_warn("sendmsg_nexthop: zclient_send_message() failed");
 599
 600   if ((command == ZEBRA_NEXTHOP_REGISTER) ||
 601       (command == ZEBRA_IMPORT_ROUTE_REGISTER))
 602     SET_FLAG(bnc->flags, BGP_NEXTHOP_REGISTERED);
 603   else if ((command == ZEBRA_NEXTHOP_UNREGISTER) ||
 604            (command == ZEBRA_IMPORT_ROUTE_UNREGISTER))
 605     UNSET_FLAG(bnc->flags, BGP_NEXTHOP_REGISTERED);
 606   return;
 607 }
 608
 609 /**
 610  * register_zebra_rnh - register a NH/route with Zebra for notification
 611  *    when the route or the route to the nexthop changes.
 612  * ARGUMENTS:
 613  *   struct bgp_nexthop_cache *bnc
 614  * RETURNS:
 615  *   void.
 616  */
 617 static void
 618 register_zebra_rnh (struct bgp_nexthop_cache *bnc, int is_bgp_import_route)
 619 {
 620   /* Check if we have already registered */
 621   if (bnc->flags & BGP_NEXTHOP_REGISTERED)
 622     return;
 623   if (is_bgp_import_route)
 624     sendmsg_zebra_rnh(bnc, ZEBRA_IMPORT_ROUTE_REGISTER);
 625   else
 626     sendmsg_zebra_rnh(bnc, ZEBRA_NEXTHOP_REGISTER);
 627 }
 628
 629 /**
 630  * unregister_zebra_rnh -- Unregister the route/nexthop from Zebra.
 631  * ARGUMENTS:
 632  *   struct bgp_nexthop_cache *bnc
 633  * RETURNS:
 634  *   void.
 635  */
 636 static void
 637 unregister_zebra_rnh (struct bgp_nexthop_cache *bnc, int is_bgp_import_route)
 638 {
 639   /* Check if we have already registered */
 640   if (!CHECK_FLAG(bnc->flags, BGP_NEXTHOP_REGISTERED))
 641     return;
 642
 643   if (is_bgp_import_route)
 644     sendmsg_zebra_rnh(bnc, ZEBRA_IMPORT_ROUTE_UNREGISTER);
 645   else
 646     sendmsg_zebra_rnh(bnc, ZEBRA_NEXTHOP_UNREGISTER);
 647 }
 648
 649 /**
 650  * evaluate_paths - Evaluate the paths/nets associated with a nexthop.
 651  * ARGUMENTS:
 652  *   struct bgp_nexthop_cache *bnc -- the nexthop structure.
 653  * RETURNS:
 654  *   void.
 655  */
 656 static void
 657 evaluate_paths (struct bgp_nexthop_cache *bnc)
 658 {
 659   struct bgp_node *rn;
 660   struct bgp_info *path;
 661   struct bgp *bgp = bnc->bgp;
 662   int afi;
 663   struct peer *peer = (struct peer *)bnc->nht_info;
 664
 665   if (BGP_DEBUG(nht, NHT))
 666     {
 667       char buf[PREFIX2STR_BUFFER];
 668       bnc_str(bnc, buf, PREFIX2STR_BUFFER);
 669       zlog_debug("NH update for %s - flags 0x%x chgflags 0x%x - evaluate paths",
 670                  buf, bnc->flags, bnc->change_flags);
 671     }
 672
 673   LIST_FOREACH(path, &(bnc->paths), nh_thread)
 674     {
 675       if (!(path->type == ZEBRA_ROUTE_BGP &&
 676             ((path->sub_type == BGP_ROUTE_NORMAL) ||
 677              (path->sub_type == BGP_ROUTE_STATIC))))
 678         continue;
 679
 680       rn = path->net;
 681       afi = family2afi(rn->p.family);
 682
 683       /* Path becomes valid/invalid depending on whether the nexthop
 684        * reachable/unreachable.
 685        */
 686       if ((CHECK_FLAG(path->flags, BGP_INFO_VALID) ? 1 : 0) !=
 687           (bgp_isvalid_nexthop(bnc) ? 1 : 0))
 688         {
 689           if (CHECK_FLAG (path->flags, BGP_INFO_VALID))
 690             {
 691               bgp_aggregate_decrement (bgp, &rn->p, path,
 692                                        afi, SAFI_UNICAST);
 693               bgp_info_unset_flag (rn, path, BGP_INFO_VALID);
 694             }
 695           else
 696             {
 697               bgp_info_set_flag (rn, path, BGP_INFO_VALID);
 698               bgp_aggregate_increment (bgp, &rn->p, path,
 699                                        afi, SAFI_UNICAST);
 700             }
 701         }
 702
 703       /* Copy the metric to the path. Will be used for bestpath computation */
 704       if (bgp_isvalid_nexthop(bnc) && bnc->metric)
 705         (bgp_info_extra_get(path))->igpmetric = bnc->metric;
 706       else if (path->extra)
 707         path->extra->igpmetric = 0;
 708
 709       if (CHECK_FLAG(bnc->change_flags, BGP_NEXTHOP_METRIC_CHANGED) ||
 710           CHECK_FLAG(bnc->change_flags, BGP_NEXTHOP_CHANGED))
 711         SET_FLAG(path->flags, BGP_INFO_IGP_CHANGED);
 712
 713       bgp_process(bgp, rn, afi, SAFI_UNICAST);
 714     }
 715
 716   if (peer && !CHECK_FLAG(bnc->flags, BGP_NEXTHOP_PEER_NOTIFIED))
 717     {
 718       if (BGP_DEBUG(nht, NHT))
 719         zlog_debug("%s: Updating peer (%s) status with NHT", __FUNCTION__, peer->host);
 720       bgp_fsm_nht_update(peer, bgp_isvalid_nexthop(bnc));
 721       SET_FLAG(bnc->flags, BGP_NEXTHOP_PEER_NOTIFIED);
 722     }
 723
 724   RESET_FLAG(bnc->change_flags);
 725 }
 726
 727 /**
 728  * path_nh_map - make or break path-to-nexthop association.
 729  * ARGUMENTS:
 730  *   path - pointer to the path structure
 731  *   bnc - pointer to the nexthop structure
 732  *   make - if set, make the association. if unset, just break the existing
 733  *          association.
 734  */
 735 static void
 736 path_nh_map (struct bgp_info *path, struct bgp_nexthop_cache *bnc, int make)
 737 {
 738   if (path->nexthop)
 739     {
 740       LIST_REMOVE(path, nh_thread);
 741       path->nexthop->path_count--;
 742       path->nexthop = NULL;
 743     }
 744   if (make)
 745     {
 746       LIST_INSERT_HEAD(&(bnc->paths), path, nh_thread);
 747       path->nexthop = bnc;
 748       path->nexthop->path_count++;
 749     }
 750 }