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