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 along
  17  * with this program; see the file COPYING; if not, write to the Free Software
  18  * Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA
  19  */
  20
  21 #include <zebra.h>
  22
  23 #include "command.h"
  24 #include "thread.h"
  25 #include "prefix.h"
  26 #include "zclient.h"
  27 #include "stream.h"
  28 #include "network.h"
  29 #include "log.h"
  30 #include "memory.h"
  31 #include "nexthop.h"
  32 #include "vrf.h"
  33 #include "filter.h"
  34
  35 #include "bgpd/bgpd.h"
  36 #include "bgpd/bgp_table.h"
  37 #include "bgpd/bgp_route.h"
  38 #include "bgpd/bgp_attr.h"
  39 #include "bgpd/bgp_nexthop.h"
  40 #include "bgpd/bgp_debug.h"
  41 #include "bgpd/bgp_nht.h"
  42 #include "bgpd/bgp_fsm.h"
  43 #include "bgpd/bgp_zebra.h"
  44
  45 extern struct zclient *zclient;
  46
  47 static void register_zebra_rnh(struct bgp_nexthop_cache *bnc,
  48                                int is_bgp_static_route);
  49 static void unregister_zebra_rnh(struct bgp_nexthop_cache *bnc,
  50                                  int is_bgp_static_route);
  51 static void evaluate_paths(struct bgp_nexthop_cache *bnc);
  52 static int make_prefix(int afi, struct bgp_info *ri, struct prefix *p);
  53 static void path_nh_map(struct bgp_info *path, struct bgp_nexthop_cache *bnc,
  54                         int keep);
  55
  56 static int bgp_isvalid_nexthop(struct bgp_nexthop_cache *bnc)
  57 {
  58         return (bgp_zebra_num_connects() == 0
  59                 || (bnc && CHECK_FLAG(bnc->flags, BGP_NEXTHOP_VALID)));
  60 }
  61
  62 int bgp_find_nexthop(struct bgp_info *path, int connected)
  63 {
  64         struct bgp_nexthop_cache *bnc = path->nexthop;
  65
  66         if (!bnc)
  67                 return 0;
  68
  69         /*
  70          * We are cheating here.  Views have no associated underlying
  71          * ability to detect nexthops.  So when we have a view
  72          * just tell everyone the nexthop is valid
  73          */
  74         if (path->peer && path->peer->bgp->inst_type == BGP_INSTANCE_TYPE_VIEW)
  75                 return 1;
  76
  77         if (connected && !(CHECK_FLAG(bnc->flags, BGP_NEXTHOP_CONNECTED)))
  78                 return 0;
  79
  80         return (bgp_isvalid_nexthop(bnc));
  81 }
  82
  83 static void bgp_unlink_nexthop_check(struct bgp_nexthop_cache *bnc)
  84 {
  85         if (LIST_EMPTY(&(bnc->paths)) && !bnc->nht_info) {
  86                 if (BGP_DEBUG(nht, NHT)) {
  87                         char buf[PREFIX2STR_BUFFER];
  88                         zlog_debug("bgp_unlink_nexthop: freeing bnc %s",
  89                                    bnc_str(bnc, buf, PREFIX2STR_BUFFER));
  90                 }
  91                 unregister_zebra_rnh(bnc,
  92                                      CHECK_FLAG(bnc->flags, BGP_STATIC_ROUTE));
  93                 bnc->node->info = NULL;
  94                 bgp_unlock_node(bnc->node);
  95                 bnc->node = NULL;
  96                 bnc_free(bnc);
  97         }
  98 }
  99
 100 void bgp_unlink_nexthop(struct bgp_info *path)
 101 {
 102         struct bgp_nexthop_cache *bnc = path->nexthop;
 103
 104         if (!bnc)
 105                 return;
 106
 107         path_nh_map(path, NULL, 0);
 108
 109         bgp_unlink_nexthop_check(bnc);
 110 }
 111
 112 void bgp_unlink_nexthop_by_peer(struct peer *peer)
 113 {
 114         struct prefix p;
 115         struct bgp_node *rn;
 116         struct bgp_nexthop_cache *bnc;
 117         afi_t afi = family2afi(peer->su.sa.sa_family);
 118
 119         if (!sockunion2hostprefix(&peer->su, &p))
 120                 return;
 121
 122         rn = bgp_node_get(peer->bgp->nexthop_cache_table[afi], &p);
 123
 124         if (!rn->info)
 125                 return;
 126
 127         bnc = rn->info;
 128
 129         /* cleanup the peer reference */
 130         bnc->nht_info = NULL;
 131
 132         bgp_unlink_nexthop_check(bnc);
 133 }
 134
 135 int 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                 is_bgp_static_route = ((ri->type == ZEBRA_ROUTE_BGP)
 145                                        && (ri->sub_type == BGP_ROUTE_STATIC))
 146                                               ? 1
 147                                               : 0;
 148
 149                 /* Since Extended Next-hop Encoding (RFC5549) support, we want
 150                    to derive
 151                    address-family from the next-hop. */
 152                 if (!is_bgp_static_route)
 153                         afi = BGP_ATTR_NEXTHOP_AFI_IP6(ri->attr) ? AFI_IP6
 154                                                                  : AFI_IP;
 155
 156                 /* This will return TRUE if the global IPv6 NH is a link local
 157                  * addr */
 158                 if (make_prefix(afi, ri, &p) < 0)
 159                         return 1;
 160         } else if (peer) {
 161                 /* Don't register link local NH */
 162                 if (afi == AFI_IP6
 163                     && IN6_IS_ADDR_LINKLOCAL(&peer->su.sin6.sin6_addr))
 164                         return 1;
 165
 166                 if (!sockunion2hostprefix(&peer->su, &p)) {
 167                         if (BGP_DEBUG(nht, NHT)) {
 168                                 zlog_debug(
 169                                         "%s: Attempting to register with unknown AFI %d (not %d or %d)",
 170                                         __FUNCTION__, afi, AFI_IP, AFI_IP6);
 171                         }
 172                         return 0;
 173                 }
 174         } else
 175                 return 0;
 176
 177         if (is_bgp_static_route)
 178                 rn = bgp_node_get(bgp->import_check_table[afi], &p);
 179         else
 180                 rn = bgp_node_get(bgp->nexthop_cache_table[afi], &p);
 181
 182         if (!rn->info) {
 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                         char buf[PREFIX2STR_BUFFER];
 190
 191                         zlog_debug("Allocated bnc %s peer %p",
 192                                    bnc_str(bnc, buf, PREFIX2STR_BUFFER), peer);
 193                 }
 194         }
 195
 196         bnc = rn->info;
 197         bgp_unlock_node(rn);
 198         if (is_bgp_static_route) {
 199                 SET_FLAG(bnc->flags, BGP_STATIC_ROUTE);
 200
 201                 /* If we're toggling the type, re-register */
 202                 if ((bgp_flag_check(bgp, BGP_FLAG_IMPORT_CHECK))
 203                     && !CHECK_FLAG(bnc->flags, BGP_STATIC_ROUTE_EXACT_MATCH)) {
 204                         SET_FLAG(bnc->flags, BGP_STATIC_ROUTE_EXACT_MATCH);
 205                         UNSET_FLAG(bnc->flags, BGP_NEXTHOP_REGISTERED);
 206                         UNSET_FLAG(bnc->flags, BGP_NEXTHOP_VALID);
 207                 } else if ((!bgp_flag_check(bgp, BGP_FLAG_IMPORT_CHECK))
 208                            && CHECK_FLAG(bnc->flags,
 209                                          BGP_STATIC_ROUTE_EXACT_MATCH)) {
 210                         UNSET_FLAG(bnc->flags, BGP_STATIC_ROUTE_EXACT_MATCH);
 211                         UNSET_FLAG(bnc->flags, BGP_NEXTHOP_REGISTERED);
 212                         UNSET_FLAG(bnc->flags, BGP_NEXTHOP_VALID);
 213                 }
 214         }
 215         /* When nexthop is already known, but now requires 'connected'
 216          * resolution,
 217          * re-register it. The reverse scenario where the nexthop currently
 218          * requires
 219          * 'connected' resolution does not need a re-register (i.e., we treat
 220          * 'connected-required' as an override) except in the scenario where
 221          * this
 222          * is actually a case of tracking a peer for connectivity (e.g., after
 223          * disable connected-check).
 224          * NOTE: We don't track the number of paths separately for 'connected-
 225          * required' vs 'connected-not-required' as this change is not a common
 226          * scenario.
 227          */
 228         else if (connected && !CHECK_FLAG(bnc->flags, BGP_NEXTHOP_CONNECTED)) {
 229                 SET_FLAG(bnc->flags, BGP_NEXTHOP_CONNECTED);
 230                 UNSET_FLAG(bnc->flags, BGP_NEXTHOP_REGISTERED);
 231                 UNSET_FLAG(bnc->flags, BGP_NEXTHOP_VALID);
 232         } else if (peer && !connected
 233                    && CHECK_FLAG(bnc->flags, BGP_NEXTHOP_CONNECTED)) {
 234                 UNSET_FLAG(bnc->flags, BGP_NEXTHOP_CONNECTED);
 235                 UNSET_FLAG(bnc->flags, BGP_NEXTHOP_REGISTERED);
 236                 UNSET_FLAG(bnc->flags, BGP_NEXTHOP_VALID);
 237         }
 238         if (bgp->inst_type == BGP_INSTANCE_TYPE_VIEW) {
 239                 bnc->flags |= BGP_NEXTHOP_REGISTERED;
 240                 bnc->flags |= BGP_NEXTHOP_VALID;
 241         } else if (!CHECK_FLAG(bnc->flags, BGP_NEXTHOP_REGISTERED))
 242                 register_zebra_rnh(bnc, is_bgp_static_route);
 243         if (ri && ri->nexthop != bnc) {
 244                 /* Unlink from existing nexthop cache, if any. This will also
 245                  * free
 246                  * the nexthop cache entry, if appropriate.
 247                  */
 248                 bgp_unlink_nexthop(ri);
 249
 250                 path_nh_map(ri, bnc, 1); /* updates NHT ri list reference */
 251
 252                 if (CHECK_FLAG(bnc->flags, BGP_NEXTHOP_VALID) && bnc->metric)
 253                         (bgp_info_extra_get(ri))->igpmetric = bnc->metric;
 254                 else if (ri->extra)
 255                         ri->extra->igpmetric = 0;
 256         } else if (peer)
 257                 bnc->nht_info = (void *)peer; /* NHT peer reference */
 258
 259         /*
 260          * We are cheating here.  Views have no associated underlying
 261          * ability to detect nexthops.  So when we have a view
 262          * just tell everyone the nexthop is valid
 263          */
 264         if (bgp->inst_type == BGP_INSTANCE_TYPE_VIEW)
 265                 return 1;
 266         else
 267                 return (bgp_isvalid_nexthop(bnc));
 268 }
 269
 270 void bgp_delete_connected_nexthop(afi_t afi, struct peer *peer)
 271 {
 272         struct bgp_node *rn;
 273         struct bgp_nexthop_cache *bnc;
 274         struct prefix p;
 275
 276         if (!peer)
 277                 return;
 278
 279         /* We don't register link local address for NHT */
 280         if (afi == AFI_IP6 && IN6_IS_ADDR_LINKLOCAL(&peer->su.sin6.sin6_addr))
 281                 return;
 282
 283         if (!sockunion2hostprefix(&peer->su, &p))
 284                 return;
 285
 286         rn = bgp_node_lookup(
 287                 peer->bgp->nexthop_cache_table[family2afi(p.family)], &p);
 288         if (!rn || !rn->info) {
 289                 if (BGP_DEBUG(nht, NHT))
 290                         zlog_debug("Cannot find connected NHT node for peer %s",
 291                                    peer->host);
 292                 if (rn)
 293                         bgp_unlock_node(rn);
 294                 return;
 295         }
 296
 297         bnc = rn->info;
 298         bgp_unlock_node(rn);
 299
 300         if (bnc->nht_info != peer) {
 301                 if (BGP_DEBUG(nht, NHT))
 302                         zlog_debug(
 303                                 "Connected NHT %p node for peer %s points to %p",
 304                                 bnc, peer->host, bnc->nht_info);
 305                 return;
 306         }
 307
 308         bnc->nht_info = NULL;
 309
 310         if (LIST_EMPTY(&(bnc->paths))) {
 311                 if (BGP_DEBUG(nht, NHT))
 312                         zlog_debug("Freeing connected NHT node %p for peer %s",
 313                                    bnc, peer->host);
 314                 unregister_zebra_rnh(bnc, 0);
 315                 bnc->node->info = NULL;
 316                 bgp_unlock_node(bnc->node);
 317                 bnc_free(bnc);
 318         }
 319 }
 320
 321 void bgp_parse_nexthop_update(int command, vrf_id_t vrf_id)
 322 {
 323         struct stream *s;
 324         struct bgp_node *rn = NULL;
 325         struct bgp_nexthop_cache *bnc;
 326         struct nexthop *nexthop;
 327         struct nexthop *oldnh;
 328         struct nexthop *nhlist_head = NULL;
 329         struct nexthop *nhlist_tail = NULL;
 330         uint32_t metric;
 331         u_char nexthop_num;
 332         struct prefix p;
 333         int i;
 334         struct bgp *bgp;
 335
 336         bgp = bgp_lookup_by_vrf_id(vrf_id);
 337         if (!bgp) {
 338                 zlog_err(
 339                         "parse nexthop update: instance not found for vrf_id %d",
 340                         vrf_id);
 341                 return;
 342         }
 343
 344         s = zclient->ibuf;
 345
 346         memset(&p, 0, sizeof(struct prefix));
 347         p.family = stream_getw(s);
 348         p.prefixlen = stream_getc(s);
 349         switch (p.family) {
 350         case AF_INET:
 351                 p.u.prefix4.s_addr = stream_get_ipv4(s);
 352                 break;
 353         case AF_INET6:
 354                 stream_get(&p.u.prefix6, s, 16);
 355                 break;
 356         default:
 357                 break;
 358         }
 359
 360         if (command == ZEBRA_NEXTHOP_UPDATE)
 361                 rn = bgp_node_lookup(
 362                         bgp->nexthop_cache_table[family2afi(p.family)], &p);
 363         else if (command == ZEBRA_IMPORT_CHECK_UPDATE)
 364                 rn = bgp_node_lookup(
 365                         bgp->import_check_table[family2afi(p.family)], &p);
 366
 367         if (!rn || !rn->info) {
 368                 if (BGP_DEBUG(nht, NHT)) {
 369                         char buf[PREFIX2STR_BUFFER];
 370                         prefix2str(&p, buf, sizeof(buf));
 371                         zlog_debug("parse nexthop update(%s): rn not found",
 372                                    buf);
 373                 }
 374                 if (rn)
 375                         bgp_unlock_node(rn);
 376                 return;
 377         }
 378
 379         bnc = rn->info;
 380         bgp_unlock_node(rn);
 381         bnc->last_update = bgp_clock();
 382         bnc->change_flags = 0;
 383         stream_getc(s); // Distance but not currently used
 384         metric = stream_getl(s);
 385         nexthop_num = stream_getc(s);
 386
 387         /* debug print the input */
 388         if (BGP_DEBUG(nht, NHT)) {
 389                 char buf[PREFIX2STR_BUFFER];
 390                 prefix2str(&p, buf, sizeof(buf));
 391                 zlog_debug(
 392                         "%d: Rcvd NH update %s - metric %d/%d #nhops %d/%d flags 0x%x",
 393                         vrf_id, buf, metric, bnc->metric, nexthop_num,
 394                         bnc->nexthop_num, bnc->flags);
 395         }
 396
 397         if (metric != bnc->metric)
 398                 bnc->change_flags |= BGP_NEXTHOP_METRIC_CHANGED;
 399
 400         if (nexthop_num != bnc->nexthop_num)
 401                 bnc->change_flags |= BGP_NEXTHOP_CHANGED;
 402
 403         if (nexthop_num) {
 404                 /* notify bgp fsm if nbr ip goes from invalid->valid */
 405                 if (!bnc->nexthop_num)
 406                         UNSET_FLAG(bnc->flags, BGP_NEXTHOP_PEER_NOTIFIED);
 407
 408                 bnc->flags |= BGP_NEXTHOP_VALID;
 409                 bnc->metric = metric;
 410                 bnc->nexthop_num = nexthop_num;
 411
 412                 for (i = 0; i < nexthop_num; i++) {
 413                         nexthop = nexthop_new();
 414                         nexthop->type = stream_getc(s);
 415                         switch (nexthop->type) {
 416                         case NEXTHOP_TYPE_IPV4:
 417                                 nexthop->gate.ipv4.s_addr = stream_get_ipv4(s);
 418                                 nexthop->ifindex = stream_getl(s);
 419                                 break;
 420                         case NEXTHOP_TYPE_IFINDEX:
 421                                 nexthop->ifindex = stream_getl(s);
 422                                 break;
 423                         case NEXTHOP_TYPE_IPV4_IFINDEX:
 424                                 nexthop->gate.ipv4.s_addr = stream_get_ipv4(s);
 425                                 nexthop->ifindex = stream_getl(s);
 426                                 break;
 427                         case NEXTHOP_TYPE_IPV6:
 428                                 stream_get(&nexthop->gate.ipv6, s, 16);
 429                                 nexthop->ifindex = stream_getl(s);
 430                                 break;
 431                         case NEXTHOP_TYPE_IPV6_IFINDEX:
 432                                 stream_get(&nexthop->gate.ipv6, s, 16);
 433                                 nexthop->ifindex = stream_getl(s);
 434                                 break;
 435                         default:
 436                                 /* do nothing */
 437                                 break;
 438                         }
 439
 440                         if (BGP_DEBUG(nht, NHT)) {
 441                                 char buf[NEXTHOP_STRLEN];
 442                                 zlog_debug(
 443                                         "    nhop via %s",
 444                                         nexthop2str(nexthop, buf, sizeof(buf)));
 445                         }
 446
 447                         if (nhlist_tail) {
 448                                 nhlist_tail->next = nexthop;
 449                                 nhlist_tail = nexthop;
 450                         } else {
 451                                 nhlist_tail = nexthop;
 452                                 nhlist_head = nexthop;
 453                         }
 454
 455                         /* No need to evaluate the nexthop if we have already
 456                          * determined
 457                          * that there has been a change.
 458                          */
 459                         if (bnc->change_flags & BGP_NEXTHOP_CHANGED)
 460                                 continue;
 461
 462                         for (oldnh = bnc->nexthop; oldnh; oldnh = oldnh->next)
 463                                 if (nexthop_same_no_recurse(oldnh, nexthop))
 464                                         break;
 465
 466                         if (!oldnh)
 467                                 bnc->change_flags |= BGP_NEXTHOP_CHANGED;
 468                 }
 469                 bnc_nexthop_free(bnc);
 470                 bnc->nexthop = nhlist_head;
 471         } else {
 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 make_prefix(int afi, struct bgp_info *ri, struct prefix *p)
 490 {
 491
 492         int is_bgp_static = ((ri->type == ZEBRA_ROUTE_BGP)
 493                              && (ri->sub_type == BGP_ROUTE_STATIC))
 494                                     ? 1
 495                                     : 0;
 496
 497         memset(p, 0, sizeof(struct prefix));
 498         switch (afi) {
 499         case AFI_IP:
 500                 p->family = AF_INET;
 501                 if (is_bgp_static) {
 502                         p->u.prefix4 = ri->net->p.u.prefix4;
 503                         p->prefixlen = ri->net->p.prefixlen;
 504                 } else {
 505                         p->u.prefix4 = ri->attr->nexthop;
 506                         p->prefixlen = IPV4_MAX_BITLEN;
 507                 }
 508                 break;
 509         case AFI_IP6:
 510                 /* We don't register link local NH */
 511                 if (ri->attr->mp_nexthop_len != BGP_ATTR_NHLEN_IPV6_GLOBAL
 512                     || IN6_IS_ADDR_LINKLOCAL(&ri->attr->mp_nexthop_global))
 513                         return -1;
 514
 515                 p->family = AF_INET6;
 516
 517                 if (is_bgp_static) {
 518                         p->u.prefix6 = ri->net->p.u.prefix6;
 519                         p->prefixlen = ri->net->p.prefixlen;
 520                 } else {
 521                         p->u.prefix6 = ri->attr->mp_nexthop_global;
 522                         p->prefixlen = IPV6_MAX_BITLEN;
 523                 }
 524                 break;
 525         default:
 526                 if (BGP_DEBUG(nht, NHT)) {
 527                         zlog_debug(
 528                                 "%s: Attempting to make prefix with unknown AFI %d (not %d or %d)",
 529                                 __FUNCTION__, afi, AFI_IP, AFI_IP6);
 530                 }
 531                 break;
 532         }
 533         return 0;
 534 }
 535
 536 /**
 537  * sendmsg_zebra_rnh -- Format and send a nexthop register/Unregister
 538  *   command to Zebra.
 539  * ARGUMENTS:
 540  *   struct bgp_nexthop_cache *bnc -- the nexthop structure.
 541  *   int command -- command to send to zebra
 542  * RETURNS:
 543  *   void.
 544  */
 545 static void sendmsg_zebra_rnh(struct bgp_nexthop_cache *bnc, int command)
 546 {
 547         struct stream *s;
 548         struct prefix *p;
 549         int ret;
 550
 551         /* Check socket. */
 552         if (!zclient || zclient->sock < 0)
 553                 return;
 554
 555         /* Don't try to register if Zebra doesn't know of this instance. */
 556         if (!IS_BGP_INST_KNOWN_TO_ZEBRA(bnc->bgp))
 557                 return;
 558
 559         p = &(bnc->node->p);
 560         s = zclient->obuf;
 561         stream_reset(s);
 562         zclient_create_header(s, command, bnc->bgp->vrf_id);
 563         if (CHECK_FLAG(bnc->flags, BGP_NEXTHOP_CONNECTED)
 564             || CHECK_FLAG(bnc->flags, BGP_STATIC_ROUTE_EXACT_MATCH))
 565                 stream_putc(s, 1);
 566         else
 567                 stream_putc(s, 0);
 568
 569         stream_putw(s, PREFIX_FAMILY(p));
 570         stream_putc(s, p->prefixlen);
 571         switch (PREFIX_FAMILY(p)) {
 572         case AF_INET:
 573                 stream_put_in_addr(s, &p->u.prefix4);
 574                 break;
 575         case AF_INET6:
 576                 stream_put(s, &(p->u.prefix6), 16);
 577                 break;
 578         default:
 579                 break;
 580         }
 581         stream_putw_at(s, 0, stream_get_endp(s));
 582
 583         ret = zclient_send_message(zclient);
 584         /* TBD: handle the failure */
 585         if (ret < 0)
 586                 zlog_warn("sendmsg_nexthop: zclient_send_message() failed");
 587
 588         if ((command == ZEBRA_NEXTHOP_REGISTER)
 589             || (command == ZEBRA_IMPORT_ROUTE_REGISTER))
 590                 SET_FLAG(bnc->flags, BGP_NEXTHOP_REGISTERED);
 591         else if ((command == ZEBRA_NEXTHOP_UNREGISTER)
 592                  || (command == ZEBRA_IMPORT_ROUTE_UNREGISTER))
 593                 UNSET_FLAG(bnc->flags, BGP_NEXTHOP_REGISTERED);
 594         return;
 595 }
 596
 597 /**
 598  * register_zebra_rnh - register a NH/route with Zebra for notification
 599  *    when the route or the route to the nexthop changes.
 600  * ARGUMENTS:
 601  *   struct bgp_nexthop_cache *bnc
 602  * RETURNS:
 603  *   void.
 604  */
 605 static void register_zebra_rnh(struct bgp_nexthop_cache *bnc,
 606                                int is_bgp_import_route)
 607 {
 608         /* Check if we have already registered */
 609         if (bnc->flags & BGP_NEXTHOP_REGISTERED)
 610                 return;
 611         if (is_bgp_import_route)
 612                 sendmsg_zebra_rnh(bnc, ZEBRA_IMPORT_ROUTE_REGISTER);
 613         else
 614                 sendmsg_zebra_rnh(bnc, ZEBRA_NEXTHOP_REGISTER);
 615 }
 616
 617 /**
 618  * unregister_zebra_rnh -- Unregister the route/nexthop from Zebra.
 619  * ARGUMENTS:
 620  *   struct bgp_nexthop_cache *bnc
 621  * RETURNS:
 622  *   void.
 623  */
 624 static void unregister_zebra_rnh(struct bgp_nexthop_cache *bnc,
 625                                  int is_bgp_import_route)
 626 {
 627         /* Check if we have already registered */
 628         if (!CHECK_FLAG(bnc->flags, BGP_NEXTHOP_REGISTERED))
 629                 return;
 630
 631         if (is_bgp_import_route)
 632                 sendmsg_zebra_rnh(bnc, ZEBRA_IMPORT_ROUTE_UNREGISTER);
 633         else
 634                 sendmsg_zebra_rnh(bnc, ZEBRA_NEXTHOP_UNREGISTER);
 635 }
 636
 637 /**
 638  * evaluate_paths - Evaluate the paths/nets associated with a nexthop.
 639  * ARGUMENTS:
 640  *   struct bgp_nexthop_cache *bnc -- the nexthop structure.
 641  * RETURNS:
 642  *   void.
 643  */
 644 static void evaluate_paths(struct bgp_nexthop_cache *bnc)
 645 {
 646         struct bgp_node *rn;
 647         struct bgp_info *path;
 648         struct bgp *bgp = bnc->bgp;
 649         int afi;
 650         struct peer *peer = (struct peer *)bnc->nht_info;
 651         struct bgp_table *table;
 652         safi_t safi;
 653
 654         if (BGP_DEBUG(nht, NHT)) {
 655                 char buf[PREFIX2STR_BUFFER];
 656                 bnc_str(bnc, buf, PREFIX2STR_BUFFER);
 657                 zlog_debug(
 658                         "NH update for %s - flags 0x%x chgflags 0x%x - evaluate paths",
 659                         buf, bnc->flags, bnc->change_flags);
 660         }
 661
 662         LIST_FOREACH(path, &(bnc->paths), nh_thread)
 663         {
 664                 if (!(path->type == ZEBRA_ROUTE_BGP
 665                       && ((path->sub_type == BGP_ROUTE_NORMAL)
 666                           || (path->sub_type == BGP_ROUTE_STATIC))))
 667                         continue;
 668
 669                 rn = path->net;
 670                 assert(rn && bgp_node_table(rn));
 671                 afi = family2afi(rn->p.family);
 672                 table = bgp_node_table(rn);
 673                 safi = table->safi;
 674
 675                 /* Path becomes valid/invalid depending on whether the nexthop
 676                  * reachable/unreachable.
 677                  */
 678                 if ((CHECK_FLAG(path->flags, BGP_INFO_VALID) ? 1 : 0)
 679                     != (bgp_isvalid_nexthop(bnc) ? 1 : 0)) {
 680                         if (CHECK_FLAG(path->flags, BGP_INFO_VALID)) {
 681                                 bgp_aggregate_decrement(bgp, &rn->p, path, afi,
 682                                                         safi);
 683                                 bgp_info_unset_flag(rn, path, BGP_INFO_VALID);
 684                         } else {
 685                                 bgp_info_set_flag(rn, path, BGP_INFO_VALID);
 686                                 bgp_aggregate_increment(bgp, &rn->p, path, afi,
 687                                                         safi);
 688                         }
 689                 }
 690
 691                 /* Copy the metric to the path. Will be used for bestpath
 692                  * computation */
 693                 if (bgp_isvalid_nexthop(bnc) && bnc->metric)
 694                         (bgp_info_extra_get(path))->igpmetric = bnc->metric;
 695                 else if (path->extra)
 696                         path->extra->igpmetric = 0;
 697
 698                 if (CHECK_FLAG(bnc->change_flags, BGP_NEXTHOP_METRIC_CHANGED)
 699                     || CHECK_FLAG(bnc->change_flags, BGP_NEXTHOP_CHANGED))
 700                         SET_FLAG(path->flags, BGP_INFO_IGP_CHANGED);
 701
 702                 bgp_process(bgp, rn, afi, safi);
 703         }
 704
 705         if (peer && !CHECK_FLAG(bnc->flags, BGP_NEXTHOP_PEER_NOTIFIED)) {
 706                 if (BGP_DEBUG(nht, NHT))
 707                         zlog_debug("%s: Updating peer (%s) status with NHT",
 708                                    __FUNCTION__, peer->host);
 709                 bgp_fsm_nht_update(peer, bgp_isvalid_nexthop(bnc));
 710                 SET_FLAG(bnc->flags, BGP_NEXTHOP_PEER_NOTIFIED);
 711         }
 712
 713         RESET_FLAG(bnc->change_flags);
 714 }
 715
 716 /**
 717  * path_nh_map - make or break path-to-nexthop association.
 718  * ARGUMENTS:
 719  *   path - pointer to the path structure
 720  *   bnc - pointer to the nexthop structure
 721  *   make - if set, make the association. if unset, just break the existing
 722  *          association.
 723  */
 724 static void path_nh_map(struct bgp_info *path, struct bgp_nexthop_cache *bnc,
 725                         int make)
 726 {
 727         if (path->nexthop) {
 728                 LIST_REMOVE(path, nh_thread);
 729                 path->nexthop->path_count--;
 730                 path->nexthop = NULL;
 731         }
 732         if (make) {
 733                 LIST_INSERT_HEAD(&(bnc->paths), path, nh_thread);
 734                 path->nexthop = bnc;
 735                 path->nexthop->path_count++;
 736         }
 737 }