nhrpd/nhrp_shortcut.c

   1 /* NHRP shortcut related functions
   2  * Copyright (c) 2014-2015 Timo Teräs
   3  *
   4  * This file is free software: you may copy, redistribute and/or modify
   5  * it under the terms of the GNU General Public License as published by
   6  * the Free Software Foundation, either version 2 of the License, or
   7  * (at your option) any later version.
   8  */
   9
  10 #ifdef HAVE_CONFIG_H
  11 #include "config.h"
  12 #endif
  13
  14 #include "nhrpd.h"
  15 #include "table.h"
  16 #include "memory.h"
  17 #include "thread.h"
  18 #include "log.h"
  19 #include "nhrp_protocol.h"
  20
  21 DEFINE_MTYPE_STATIC(NHRPD, NHRP_SHORTCUT, "NHRP shortcut");
  22
  23 static struct route_table *shortcut_rib[AFI_MAX];
  24
  25 static void nhrp_shortcut_do_purge(struct thread *t);
  26 static void nhrp_shortcut_delete(struct nhrp_shortcut *s);
  27 static void nhrp_shortcut_send_resolution_req(struct nhrp_shortcut *s);
  28
  29 static void nhrp_shortcut_check_use(struct nhrp_shortcut *s)
  30 {
  31         if (s->expiring && s->cache && s->cache->used) {
  32                 debugf(NHRP_DEBUG_ROUTE, "Shortcut %pFX used and expiring",
  33                        s->p);
  34                 nhrp_shortcut_send_resolution_req(s);
  35         }
  36 }
  37
  38 static void nhrp_shortcut_do_expire(struct thread *t)
  39 {
  40         struct nhrp_shortcut *s = THREAD_ARG(t);
  41
  42         thread_add_timer(master, nhrp_shortcut_do_purge, s, s->holding_time / 3,
  43                          &s->t_timer);
  44         s->expiring = 1;
  45         nhrp_shortcut_check_use(s);
  46 }
  47
  48 static void nhrp_shortcut_cache_notify(struct notifier_block *n,
  49                                        unsigned long cmd)
  50 {
  51         char buf2[PREFIX_STRLEN];
  52
  53         struct nhrp_shortcut *s =
  54                 container_of(n, struct nhrp_shortcut, cache_notifier);
  55         struct nhrp_cache *c = s->cache;
  56
  57         if (c)
  58                 sockunion2str(&c->remote_addr, buf2, sizeof(buf2));
  59         else
  60                 snprintf(buf2, sizeof(buf2), "(unspec)");
  61         switch (cmd) {
  62         case NOTIFY_CACHE_UP:
  63                 if (!s->route_installed) {
  64                         debugf(NHRP_DEBUG_ROUTE,
  65                                "Shortcut: route install %pFX nh %s dev %s",
  66                                s->p, buf2, c && c->ifp ?
  67                                c->ifp->name : "<unk>");
  68
  69                         nhrp_route_announce(1, s->type, s->p, c ? c->ifp : NULL,
  70                                             c ? &c->remote_addr : NULL, 0);
  71                         s->route_installed = 1;
  72                 }
  73                 break;
  74         case NOTIFY_CACHE_USED:
  75                 nhrp_shortcut_check_use(s);
  76                 break;
  77         case NOTIFY_CACHE_DOWN:
  78         case NOTIFY_CACHE_DELETE:
  79                 if (s->route_installed) {
  80                         nhrp_route_announce(0, NHRP_CACHE_INVALID, s->p, NULL,
  81                                             NULL, 0);
  82                         s->route_installed = 0;
  83                 }
  84                 if (cmd == NOTIFY_CACHE_DELETE)
  85                         nhrp_shortcut_delete(s);
  86                 break;
  87         }
  88 }
  89
  90 static void nhrp_shortcut_update_binding(struct nhrp_shortcut *s,
  91                                          enum nhrp_cache_type type,
  92                                          struct nhrp_cache *c, int holding_time)
  93 {
  94         s->type = type;
  95         if (c != s->cache) {
  96                 if (s->cache) {
  97                         nhrp_cache_notify_del(s->cache, &s->cache_notifier);
  98                         s->cache = NULL;
  99                 }
 100                 s->cache = c;
 101                 if (s->cache) {
 102                         nhrp_cache_notify_add(s->cache, &s->cache_notifier,
 103                                               nhrp_shortcut_cache_notify);
 104                         if (s->cache->route_installed) {
 105                                 /* Force renewal of Zebra announce on prefix
 106                                  * change */
 107                                 s->route_installed = 0;
 108                                 debugf(NHRP_DEBUG_ROUTE,
 109                                        "Shortcut: forcing renewal of zebra announce on prefix change peer %pSU ht %u cur nbma %pSU dev %s",
 110                                        &s->cache->remote_addr, holding_time,
 111                                        &s->cache->cur.remote_nbma_natoa,
 112                                        s->cache->ifp->name);
 113                                 nhrp_shortcut_cache_notify(&s->cache_notifier,
 114                                                            NOTIFY_CACHE_UP);
 115                         }
 116                 }
 117                 if (!s->cache || !s->cache->route_installed) {
 118                         debugf(NHRP_DEBUG_ROUTE,
 119                                "Shortcut: notify cache down because cache?%s or ri?%s",
 120                                s->cache ? "yes" : "no",
 121                                s->cache ? (s->cache->route_installed ? "yes"
 122                                                                      : "no")
 123                                         : "n/a");
 124                         nhrp_shortcut_cache_notify(&s->cache_notifier,
 125                                                    NOTIFY_CACHE_DOWN);
 126                 }
 127         }
 128         if (s->type == NHRP_CACHE_NEGATIVE && !s->route_installed) {
 129                 nhrp_route_announce(1, s->type, s->p, NULL, NULL, 0);
 130                 s->route_installed = 1;
 131         } else if (s->type == NHRP_CACHE_INVALID && s->route_installed) {
 132                 nhrp_route_announce(0, NHRP_CACHE_INVALID, s->p, NULL, NULL, 0);
 133                 s->route_installed = 0;
 134         }
 135
 136         THREAD_OFF(s->t_timer);
 137         if (holding_time) {
 138                 s->expiring = 0;
 139                 s->holding_time = holding_time;
 140                 thread_add_timer(master, nhrp_shortcut_do_expire, s,
 141                                  2 * holding_time / 3, &s->t_timer);
 142         }
 143 }
 144
 145 static void nhrp_shortcut_delete(struct nhrp_shortcut *s)
 146 {
 147         struct route_node *rn;
 148         afi_t afi = family2afi(PREFIX_FAMILY(s->p));
 149
 150         THREAD_OFF(s->t_timer);
 151         nhrp_reqid_free(&nhrp_packet_reqid, &s->reqid);
 152
 153         debugf(NHRP_DEBUG_ROUTE, "Shortcut %pFX purged", s->p);
 154
 155         nhrp_shortcut_update_binding(s, NHRP_CACHE_INVALID, NULL, 0);
 156
 157         /* Delete node */
 158         rn = route_node_lookup(shortcut_rib[afi], s->p);
 159         if (rn) {
 160                 XFREE(MTYPE_NHRP_SHORTCUT, rn->info);
 161                 rn->info = NULL;
 162                 route_unlock_node(rn);
 163                 route_unlock_node(rn);
 164         }
 165 }
 166
 167 static void nhrp_shortcut_do_purge(struct thread *t)
 168 {
 169         struct nhrp_shortcut *s = THREAD_ARG(t);
 170         s->t_timer = NULL;
 171         nhrp_shortcut_delete(s);
 172 }
 173
 174 static struct nhrp_shortcut *nhrp_shortcut_get(struct prefix *p)
 175 {
 176         struct nhrp_shortcut *s;
 177         struct route_node *rn;
 178         afi_t afi = family2afi(PREFIX_FAMILY(p));
 179
 180         if (!shortcut_rib[afi])
 181                 return 0;
 182
 183         rn = route_node_get(shortcut_rib[afi], p);
 184         if (!rn->info) {
 185                 s = rn->info = XCALLOC(MTYPE_NHRP_SHORTCUT,
 186                                        sizeof(struct nhrp_shortcut));
 187                 s->type = NHRP_CACHE_INVALID;
 188                 s->p = &rn->p;
 189
 190                 debugf(NHRP_DEBUG_ROUTE, "Shortcut %pFX created", s->p);
 191         } else {
 192                 s = rn->info;
 193                 route_unlock_node(rn);
 194         }
 195         return s;
 196 }
 197
 198 static void nhrp_shortcut_recv_resolution_rep(struct nhrp_reqid *reqid,
 199                                               void *arg)
 200 {
 201         struct nhrp_packet_parser *pp = arg;
 202         struct interface *ifp = pp->ifp;
 203         struct nhrp_interface *nifp = ifp->info;
 204         struct nhrp_shortcut *s =
 205                 container_of(reqid, struct nhrp_shortcut, reqid);
 206         struct nhrp_shortcut *ps;
 207         struct nhrp_extension_header *ext;
 208         struct nhrp_cie_header *cie;
 209         struct nhrp_cache *c = NULL;
 210         struct nhrp_cache *c_dst = NULL;
 211         union sockunion *proto, cie_proto, *nbma, cie_nbma, nat_nbma;
 212         struct prefix prefix, route_prefix;
 213         struct zbuf extpl;
 214         int holding_time = pp->if_ad->holdtime;
 215
 216         nhrp_reqid_free(&nhrp_packet_reqid, &s->reqid);
 217         THREAD_OFF(s->t_timer);
 218         thread_add_timer(master, nhrp_shortcut_do_purge, s, 1, &s->t_timer);
 219
 220         if (pp->hdr->type != NHRP_PACKET_RESOLUTION_REPLY) {
 221                 if (pp->hdr->type == NHRP_PACKET_ERROR_INDICATION
 222                     && pp->hdr->u.error.code
 223                                == NHRP_ERROR_PROTOCOL_ADDRESS_UNREACHABLE) {
 224                         debugf(NHRP_DEBUG_COMMON,
 225                                "Shortcut: Resolution: Protocol address unreachable");
 226                         nhrp_shortcut_update_binding(s, NHRP_CACHE_NEGATIVE,
 227                                                      NULL, holding_time);
 228                 } else {
 229                         debugf(NHRP_DEBUG_COMMON,
 230                                "Shortcut: Resolution failed");
 231                 }
 232                 return;
 233         }
 234
 235         /* Minor sanity check */
 236         prefix2sockunion(s->p, &cie_proto);
 237         if (!sockunion_same(&cie_proto, &pp->dst_proto)) {
 238                 debugf(NHRP_DEBUG_COMMON,
 239                        "Shortcut: Warning dst_proto altered from %pSU to %pSU",
 240                        &cie_proto, &pp->dst_proto);
 241                 ;
 242         }
 243
 244         /* One or more CIEs should be given as reply, we support only one */
 245         cie = nhrp_cie_pull(&pp->payload, pp->hdr, &cie_nbma, &cie_proto);
 246         if (!cie || cie->code != NHRP_CODE_SUCCESS) {
 247                 debugf(NHRP_DEBUG_COMMON, "Shortcut: CIE code %d",
 248                        cie ? cie->code : -1);
 249                 return;
 250         }
 251
 252         proto = sockunion_family(&cie_proto) != AF_UNSPEC ? &cie_proto
 253                                                           : &pp->dst_proto;
 254         if (cie->holding_time)
 255                 holding_time = htons(cie->holding_time);
 256
 257         prefix = *s->p;
 258         prefix.prefixlen = cie->prefix_length;
 259
 260         /* Sanity check prefix length */
 261         if (prefix.prefixlen >= 8 * prefix_blen(&prefix)
 262             || prefix.prefixlen == 0) {
 263                 prefix.prefixlen = 8 * prefix_blen(&prefix);
 264         } else if (nhrp_route_address(NULL, &pp->dst_proto, &route_prefix, NULL)
 265                    == NHRP_ROUTE_NBMA_NEXTHOP) {
 266                 if (prefix.prefixlen < route_prefix.prefixlen)
 267                         prefix.prefixlen = route_prefix.prefixlen;
 268         }
 269
 270         /* Parse extensions */
 271         memset(&nat_nbma, 0, sizeof(nat_nbma));
 272         while ((ext = nhrp_ext_pull(&pp->extensions, &extpl)) != NULL) {
 273                 switch (htons(ext->type) & ~NHRP_EXTENSION_FLAG_COMPULSORY) {
 274                 case NHRP_EXTENSION_NAT_ADDRESS: {
 275                         struct nhrp_cie_header *cie_nat;
 276
 277                         do {
 278                                 union sockunion cie_nat_proto, cie_nat_nbma;
 279
 280                                 sockunion_family(&cie_nat_proto) = AF_UNSPEC;
 281                                 sockunion_family(&cie_nat_nbma) = AF_UNSPEC;
 282                                 cie_nat = nhrp_cie_pull(&extpl, pp->hdr,
 283                                                         &cie_nat_nbma,
 284                                                         &cie_nat_proto);
 285                                 /* We are interested only in peer CIE */
 286                                 if (cie_nat
 287                                     && sockunion_same(&cie_nat_proto, proto)) {
 288                                         nat_nbma = cie_nat_nbma;
 289                                 }
 290                         } while (cie_nat);
 291                 } break;
 292                 default:
 293                         break;
 294                 }
 295         }
 296
 297         /* Update cache entry for the protocol to nbma binding */
 298         if (sockunion_family(&nat_nbma) != AF_UNSPEC) {
 299                 debugf(NHRP_DEBUG_COMMON,
 300                        "Shortcut: NAT detected (NAT extension) proto %pSU NBMA %pSU claimed-NBMA %pSU",
 301                        proto, &nat_nbma, &cie_nbma);
 302                 nbma = &nat_nbma;
 303         }
 304         /* For NHRP resolution reply the cie_nbma in mandatory part is the
 305          * address of the actual address of the sender
 306          */
 307         else if (!sockunion_same(&cie_nbma, &pp->peer->vc->remote.nbma)
 308                  && !nhrp_nhs_match_ip(&pp->peer->vc->remote.nbma, nifp)) {
 309                 debugf(NHRP_DEBUG_COMMON,
 310                        "Shortcut: NAT detected (no NAT Extension) proto %pSU NBMA %pSU claimed-NBMA %pSU",
 311                        proto, &pp->peer->vc->remote.nbma, &cie_nbma);
 312                 nbma = &pp->peer->vc->remote.nbma;
 313                 nat_nbma = *nbma;
 314         } else {
 315                 nbma = &cie_nbma;
 316         }
 317
 318         debugf(NHRP_DEBUG_COMMON,
 319                "Shortcut: %pFX is at proto %pSU dst_proto %pSU NBMA %pSU cie-holdtime %d",
 320                &prefix, proto, &pp->dst_proto, nbma,
 321                htons(cie->holding_time));
 322
 323         if (sockunion_family(nbma)) {
 324                 c = nhrp_cache_get(pp->ifp, proto, 1);
 325                 if (c) {
 326                         debugf(NHRP_DEBUG_COMMON,
 327                                "Shortcut: cache found, update binding");
 328                         nhrp_cache_update_binding(c, NHRP_CACHE_DYNAMIC,
 329                                                   holding_time,
 330                                                   nhrp_peer_get(pp->ifp, nbma),
 331                                                   htons(cie->mtu),
 332                                                   nbma,
 333                                                   &cie_nbma);
 334                 } else {
 335                         debugf(NHRP_DEBUG_COMMON,
 336                                "Shortcut: no cache for proto %pSU", proto);
 337                 }
 338
 339                 /* Update cache binding for dst_proto as well */
 340                 if (sockunion_cmp(proto, &pp->dst_proto)) {
 341                         c_dst = nhrp_cache_get(pp->ifp, &pp->dst_proto, 1);
 342                         if (c_dst) {
 343                                 debugf(NHRP_DEBUG_COMMON,
 344                                        "Shortcut: cache found, update binding");
 345                                 nhrp_cache_update_binding(c_dst,
 346                                                   NHRP_CACHE_DYNAMIC,
 347                                                   holding_time,
 348                                                   nhrp_peer_get(pp->ifp, nbma),
 349                                                   htons(cie->mtu),
 350                                                   nbma,
 351                                                   &cie_nbma);
 352                         } else {
 353                                 debugf(NHRP_DEBUG_COMMON,
 354                                        "Shortcut: no cache for proto %pSU",
 355                                        &pp->dst_proto);
 356                         }
 357                 }
 358         }
 359
 360         /* Update shortcut entry for subnet to protocol gw binding */
 361         if (c) {
 362                 ps = nhrp_shortcut_get(&prefix);
 363                 if (ps) {
 364                         ps->addr = s->addr;
 365                         debugf(NHRP_DEBUG_COMMON,
 366                                "Shortcut: calling update_binding");
 367                         nhrp_shortcut_update_binding(ps, NHRP_CACHE_DYNAMIC, c,
 368                                                      holding_time);
 369                 } else {
 370                         debugf(NHRP_DEBUG_COMMON,
 371                                "Shortcut: proto diff but no ps");
 372                 }
 373         } else {
 374                 debugf(NHRP_DEBUG_COMMON,
 375                        "NO Shortcut because c NULL?%s or same proto?%s",
 376                        c ? "no" : "yes",
 377                        proto && pp && sockunion_same(proto, &pp->dst_proto)
 378                                ? "yes"
 379                                : "no");
 380         }
 381
 382         debugf(NHRP_DEBUG_COMMON, "Shortcut: Resolution reply handled");
 383 }
 384
 385 static void nhrp_shortcut_send_resolution_req(struct nhrp_shortcut *s)
 386 {
 387         struct zbuf *zb;
 388         struct nhrp_packet_header *hdr;
 389         struct interface *ifp;
 390         struct nhrp_interface *nifp;
 391         struct nhrp_afi_data *if_ad;
 392         struct nhrp_peer *peer;
 393         struct nhrp_cie_header *cie;
 394         struct nhrp_extension_header *ext;
 395
 396         if (nhrp_route_address(NULL, &s->addr, NULL, &peer)
 397             != NHRP_ROUTE_NBMA_NEXTHOP)
 398                 return;
 399
 400         if (s->type == NHRP_CACHE_INVALID || s->type == NHRP_CACHE_NEGATIVE)
 401                 s->type = NHRP_CACHE_INCOMPLETE;
 402
 403         ifp = peer->ifp;
 404         nifp = ifp->info;
 405
 406         /* Create request */
 407         zb = zbuf_alloc(1500);
 408         hdr = nhrp_packet_push(
 409                 zb, NHRP_PACKET_RESOLUTION_REQUEST, &nifp->nbma,
 410                 &nifp->afi[family2afi(sockunion_family(&s->addr))].addr,
 411                 &s->addr);
 412         hdr->u.request_id =
 413                 htonl(nhrp_reqid_alloc(&nhrp_packet_reqid, &s->reqid,
 414                                        nhrp_shortcut_recv_resolution_rep));
 415         hdr->flags = htons(NHRP_FLAG_RESOLUTION_SOURCE_IS_ROUTER
 416                            | NHRP_FLAG_RESOLUTION_AUTHORATIVE
 417                            | NHRP_FLAG_RESOLUTION_SOURCE_STABLE);
 418
 419         /* RFC2332 - One or zero CIEs, if CIE is present contains:
 420          *  - Prefix length: widest acceptable prefix we accept (if U set, 0xff)
 421          *  - MTU: MTU of the source station
 422          *  - Holding Time: Max time to cache the source information
 423          * */
 424         /* FIXME: push CIE for each local protocol address */
 425         cie = nhrp_cie_push(zb, NHRP_CODE_SUCCESS, NULL, NULL);
 426         if_ad = &nifp->afi[family2afi(sockunion_family(&s->addr))];
 427         cie->prefix_length = (if_ad->flags & NHRP_IFF_REG_NO_UNIQUE)
 428                                 ? 8 * sockunion_get_addrlen(&s->addr)
 429                                 : 0xff;
 430         cie->holding_time = htons(if_ad->holdtime);
 431         cie->mtu = htons(if_ad->mtu);
 432         debugf(NHRP_DEBUG_COMMON,
 433                "Shortcut res_req: set cie ht to %u and mtu to %u. shortcut ht is %u",
 434                ntohs(cie->holding_time), ntohs(cie->mtu), s->holding_time);
 435
 436         nhrp_ext_request(zb, hdr, ifp);
 437
 438         /* Cisco NAT detection extension */
 439         hdr->flags |= htons(NHRP_FLAG_RESOLUTION_NAT);
 440         ext = nhrp_ext_push(zb, hdr, NHRP_EXTENSION_NAT_ADDRESS);
 441         if (sockunion_family(&nifp->nat_nbma) != AF_UNSPEC) {
 442                 cie = nhrp_cie_push(zb, NHRP_CODE_SUCCESS, &nifp->nat_nbma,
 443                                     &if_ad->addr);
 444                 cie->prefix_length = 8 * sockunion_get_addrlen(&if_ad->addr);
 445                 cie->mtu = htons(if_ad->mtu);
 446                 nhrp_ext_complete(zb, ext);
 447         }
 448
 449         nhrp_packet_complete(zb, hdr);
 450
 451         nhrp_peer_send(peer, zb);
 452         nhrp_peer_unref(peer);
 453         zbuf_free(zb);
 454 }
 455
 456 void nhrp_shortcut_initiate(union sockunion *addr)
 457 {
 458         struct prefix p;
 459         struct nhrp_shortcut *s;
 460
 461         if (!sockunion2hostprefix(addr, &p))
 462                 return;
 463
 464         s = nhrp_shortcut_get(&p);
 465         if (s && s->type != NHRP_CACHE_INCOMPLETE) {
 466                 s->addr = *addr;
 467                 THREAD_OFF(s->t_timer);
 468                 thread_add_timer(master, nhrp_shortcut_do_purge, s, 30,
 469                                  &s->t_timer);
 470                 nhrp_shortcut_send_resolution_req(s);
 471         }
 472 }
 473
 474 void nhrp_shortcut_init(void)
 475 {
 476         shortcut_rib[AFI_IP] = route_table_init();
 477         shortcut_rib[AFI_IP6] = route_table_init();
 478 }
 479
 480 void nhrp_shortcut_terminate(void)
 481 {
 482         route_table_finish(shortcut_rib[AFI_IP]);
 483         route_table_finish(shortcut_rib[AFI_IP6]);
 484 }
 485
 486 void nhrp_shortcut_foreach(afi_t afi,
 487                            void (*cb)(struct nhrp_shortcut *, void *),
 488                            void *ctx)
 489 {
 490         struct route_table *rt = shortcut_rib[afi];
 491         struct route_node *rn;
 492         route_table_iter_t iter;
 493
 494         if (!rt)
 495                 return;
 496
 497         route_table_iter_init(&iter, rt);
 498         while ((rn = route_table_iter_next(&iter)) != NULL) {
 499                 if (rn->info)
 500                         cb(rn->info, ctx);
 501         }
 502         route_table_iter_cleanup(&iter);
 503 }
 504
 505 struct purge_ctx {
 506         const struct prefix *p;
 507         int deleted;
 508 };
 509
 510 void nhrp_shortcut_purge(struct nhrp_shortcut *s, int force)
 511 {
 512         THREAD_OFF(s->t_timer);
 513         nhrp_reqid_free(&nhrp_packet_reqid, &s->reqid);
 514
 515         if (force) {
 516                 /* Immediate purge on route with draw or pending shortcut */
 517                 thread_add_timer_msec(master, nhrp_shortcut_do_purge, s, 5,
 518                                       &s->t_timer);
 519         } else {
 520                 /* Soft expire - force immediate renewal, but purge
 521                  * in few seconds to make sure stale route is not
 522                  * used too long. In practice most purges are caused
 523                  * by hub bgp change, but target usually stays same.
 524                  * This allows to keep nhrp route up, and to not
 525                  * cause temporary rerouting via hubs causing latency
 526                  * jitter. */
 527                 thread_add_timer_msec(master, nhrp_shortcut_do_purge, s, 3000,
 528                                       &s->t_timer);
 529                 s->expiring = 1;
 530                 nhrp_shortcut_check_use(s);
 531         }
 532 }
 533
 534 static void nhrp_shortcut_purge_prefix(struct nhrp_shortcut *s, void *ctx)
 535 {
 536         struct purge_ctx *pctx = ctx;
 537
 538         if (prefix_match(pctx->p, s->p))
 539                 nhrp_shortcut_purge(s, pctx->deleted || !s->cache);
 540 }
 541
 542 void nhrp_shortcut_prefix_change(const struct prefix *p, int deleted)
 543 {
 544         struct purge_ctx pctx = {
 545                 .p = p, .deleted = deleted,
 546         };
 547         nhrp_shortcut_foreach(family2afi(PREFIX_FAMILY(p)),
 548                               nhrp_shortcut_purge_prefix, &pctx);
 549 }