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 int 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 int nhrp_shortcut_do_expire(struct thread *t)
  39 {
  40         struct nhrp_shortcut *s = THREAD_ARG(t);
  41
  42         s->t_timer = NULL;
  43         thread_add_timer(master, nhrp_shortcut_do_purge, s, s->holding_time / 3,
  44                          &s->t_timer);
  45         s->expiring = 1;
  46         nhrp_shortcut_check_use(s);
  47
  48         return 0;
  49 }
  50
  51 static void nhrp_shortcut_cache_notify(struct notifier_block *n,
  52                                        unsigned long cmd)
  53 {
  54         char buf2[PREFIX_STRLEN];
  55
  56         struct nhrp_shortcut *s =
  57                 container_of(n, struct nhrp_shortcut, cache_notifier);
  58         struct nhrp_cache *c = s->cache;
  59
  60         if (c)
  61                 sockunion2str(&c->remote_addr, buf2, sizeof(buf2));
  62         else
  63                 snprintf(buf2, sizeof(buf2), "(unspec)");
  64         switch (cmd) {
  65         case NOTIFY_CACHE_UP:
  66                 if (!s->route_installed) {
  67                         debugf(NHRP_DEBUG_ROUTE,
  68                                "Shortcut: route install %pFX nh %s dev %s",
  69                                s->p, buf2, c && c->ifp ?
  70                                c->ifp->name : "<unk>");
  71
  72                         nhrp_route_announce(1, s->type, s->p, c ? c->ifp : NULL,
  73                                             c ? &c->remote_addr : NULL, 0);
  74                         s->route_installed = 1;
  75                 }
  76                 break;
  77         case NOTIFY_CACHE_USED:
  78                 nhrp_shortcut_check_use(s);
  79                 break;
  80         case NOTIFY_CACHE_DOWN:
  81         case NOTIFY_CACHE_DELETE:
  82                 if (s->route_installed) {
  83                         nhrp_route_announce(0, NHRP_CACHE_INVALID, s->p, NULL,
  84                                             NULL, 0);
  85                         s->route_installed = 0;
  86                 }
  87                 if (cmd == NOTIFY_CACHE_DELETE)
  88                         nhrp_shortcut_delete(s);
  89                 break;
  90         }
  91 }
  92
  93 static void nhrp_shortcut_update_binding(struct nhrp_shortcut *s,
  94                                          enum nhrp_cache_type type,
  95                                          struct nhrp_cache *c, int holding_time)
  96 {
  97         s->type = type;
  98         if (c != s->cache) {
  99                 if (s->cache) {
 100                         nhrp_cache_notify_del(s->cache, &s->cache_notifier);
 101                         s->cache = NULL;
 102                 }
 103                 s->cache = c;
 104                 if (s->cache) {
 105                         nhrp_cache_notify_add(s->cache, &s->cache_notifier,
 106                                               nhrp_shortcut_cache_notify);
 107                         if (s->cache->route_installed) {
 108                                 /* Force renewal of Zebra announce on prefix
 109                                  * change */
 110                                 s->route_installed = 0;
 111                                 debugf(NHRP_DEBUG_ROUTE,
 112                                        "Shortcut: forcing renewal of zebra announce on prefix change peer %pSU ht %u cur nbma %pSU dev %s",
 113                                        &s->cache->remote_addr, holding_time,
 114                                        &s->cache->cur.remote_nbma_natoa,
 115                                        s->cache->ifp->name);
 116                                 nhrp_shortcut_cache_notify(&s->cache_notifier,
 117                                                            NOTIFY_CACHE_UP);
 118                         }
 119                 }
 120                 if (!s->cache || !s->cache->route_installed) {
 121                         debugf(NHRP_DEBUG_ROUTE,
 122                                "Shortcut: notify cache down because cache?%s or ri?%s",
 123                                s->cache ? "yes" : "no",
 124                                s->cache ? (s->cache->route_installed ? "yes"
 125                                                                      : "no")
 126                                         : "n/a");
 127                         nhrp_shortcut_cache_notify(&s->cache_notifier,
 128                                                    NOTIFY_CACHE_DOWN);
 129                 }
 130         }
 131         if (s->type == NHRP_CACHE_NEGATIVE && !s->route_installed) {
 132                 nhrp_route_announce(1, s->type, s->p, NULL, NULL, 0);
 133                 s->route_installed = 1;
 134         } else if (s->type == NHRP_CACHE_INVALID && s->route_installed) {
 135                 nhrp_route_announce(0, NHRP_CACHE_INVALID, s->p, NULL, NULL, 0);
 136                 s->route_installed = 0;
 137         }
 138
 139         THREAD_OFF(s->t_timer);
 140         if (holding_time) {
 141                 s->expiring = 0;
 142                 s->holding_time = holding_time;
 143                 thread_add_timer(master, nhrp_shortcut_do_expire, s,
 144                                  2 * holding_time / 3, &s->t_timer);
 145         }
 146 }
 147
 148 static void nhrp_shortcut_delete(struct nhrp_shortcut *s)
 149 {
 150         struct route_node *rn;
 151         afi_t afi = family2afi(PREFIX_FAMILY(s->p));
 152
 153         THREAD_OFF(s->t_timer);
 154         nhrp_reqid_free(&nhrp_packet_reqid, &s->reqid);
 155
 156         debugf(NHRP_DEBUG_ROUTE, "Shortcut %pFX purged", s->p);
 157
 158         nhrp_shortcut_update_binding(s, NHRP_CACHE_INVALID, NULL, 0);
 159
 160         /* Delete node */
 161         rn = route_node_lookup(shortcut_rib[afi], s->p);
 162         if (rn) {
 163                 XFREE(MTYPE_NHRP_SHORTCUT, rn->info);
 164                 rn->info = NULL;
 165                 route_unlock_node(rn);
 166                 route_unlock_node(rn);
 167         }
 168 }
 169
 170 static int nhrp_shortcut_do_purge(struct thread *t)
 171 {
 172         struct nhrp_shortcut *s = THREAD_ARG(t);
 173         s->t_timer = NULL;
 174         nhrp_shortcut_delete(s);
 175         return 0;
 176 }
 177
 178 static struct nhrp_shortcut *nhrp_shortcut_get(struct prefix *p)
 179 {
 180         struct nhrp_shortcut *s;
 181         struct route_node *rn;
 182         afi_t afi = family2afi(PREFIX_FAMILY(p));
 183
 184         if (!shortcut_rib[afi])
 185                 return 0;
 186
 187         rn = route_node_get(shortcut_rib[afi], p);
 188         if (!rn->info) {
 189                 s = rn->info = XCALLOC(MTYPE_NHRP_SHORTCUT,
 190                                        sizeof(struct nhrp_shortcut));
 191                 s->type = NHRP_CACHE_INVALID;
 192                 s->p = &rn->p;
 193
 194                 debugf(NHRP_DEBUG_ROUTE, "Shortcut %pFX created", s->p);
 195         } else {
 196                 s = rn->info;
 197                 route_unlock_node(rn);
 198         }
 199         return s;
 200 }
 201
 202 static void nhrp_shortcut_recv_resolution_rep(struct nhrp_reqid *reqid,
 203                                               void *arg)
 204 {
 205         struct nhrp_packet_parser *pp = arg;
 206         struct interface *ifp = pp->ifp;
 207         struct nhrp_interface *nifp = ifp->info;
 208         struct nhrp_shortcut *s =
 209                 container_of(reqid, struct nhrp_shortcut, reqid);
 210         struct nhrp_shortcut *ps;
 211         struct nhrp_extension_header *ext;
 212         struct nhrp_cie_header *cie;
 213         struct nhrp_cache *c = NULL;
 214         struct nhrp_cache *c_dst = NULL;
 215         union sockunion *proto, cie_proto, *nbma, cie_nbma, nat_nbma;
 216         struct prefix prefix, route_prefix;
 217         struct zbuf extpl;
 218         int holding_time = pp->if_ad->holdtime;
 219
 220         nhrp_reqid_free(&nhrp_packet_reqid, &s->reqid);
 221         THREAD_OFF(s->t_timer);
 222         thread_add_timer(master, nhrp_shortcut_do_purge, s, 1, &s->t_timer);
 223
 224         if (pp->hdr->type != NHRP_PACKET_RESOLUTION_REPLY) {
 225                 if (pp->hdr->type == NHRP_PACKET_ERROR_INDICATION
 226                     && pp->hdr->u.error.code
 227                                == NHRP_ERROR_PROTOCOL_ADDRESS_UNREACHABLE) {
 228                         debugf(NHRP_DEBUG_COMMON,
 229                                "Shortcut: Resolution: Protocol address unreachable");
 230                         nhrp_shortcut_update_binding(s, NHRP_CACHE_NEGATIVE,
 231                                                      NULL, holding_time);
 232                 } else {
 233                         debugf(NHRP_DEBUG_COMMON,
 234                                "Shortcut: Resolution failed");
 235                 }
 236                 return;
 237         }
 238
 239         /* Minor sanity check */
 240         prefix2sockunion(s->p, &cie_proto);
 241         if (!sockunion_same(&cie_proto, &pp->dst_proto)) {
 242                 debugf(NHRP_DEBUG_COMMON,
 243                        "Shortcut: Warning dst_proto altered from %pSU to %pSU",
 244                        &cie_proto, &pp->dst_proto);
 245                 ;
 246         }
 247
 248         /* One or more CIEs should be given as reply, we support only one */
 249         cie = nhrp_cie_pull(&pp->payload, pp->hdr, &cie_nbma, &cie_proto);
 250         if (!cie || cie->code != NHRP_CODE_SUCCESS) {
 251                 debugf(NHRP_DEBUG_COMMON, "Shortcut: CIE code %d",
 252                        cie ? cie->code : -1);
 253                 return;
 254         }
 255
 256         proto = sockunion_family(&cie_proto) != AF_UNSPEC ? &cie_proto
 257                                                           : &pp->dst_proto;
 258         if (cie->holding_time)
 259                 holding_time = htons(cie->holding_time);
 260
 261         prefix = *s->p;
 262         prefix.prefixlen = cie->prefix_length;
 263
 264         /* Sanity check prefix length */
 265         if (prefix.prefixlen >= 8 * prefix_blen(&prefix)
 266             || prefix.prefixlen == 0) {
 267                 prefix.prefixlen = 8 * prefix_blen(&prefix);
 268         } else if (nhrp_route_address(NULL, &pp->dst_proto, &route_prefix, NULL)
 269                    == NHRP_ROUTE_NBMA_NEXTHOP) {
 270                 if (prefix.prefixlen < route_prefix.prefixlen)
 271                         prefix.prefixlen = route_prefix.prefixlen;
 272         }
 273
 274         /* Parse extensions */
 275         memset(&nat_nbma, 0, sizeof(nat_nbma));
 276         while ((ext = nhrp_ext_pull(&pp->extensions, &extpl)) != NULL) {
 277                 switch (htons(ext->type) & ~NHRP_EXTENSION_FLAG_COMPULSORY) {
 278                 case NHRP_EXTENSION_NAT_ADDRESS: {
 279                         struct nhrp_cie_header *cie_nat;
 280
 281                         do {
 282                                 union sockunion cie_nat_proto, cie_nat_nbma;
 283
 284                                 sockunion_family(&cie_nat_proto) = AF_UNSPEC;
 285                                 sockunion_family(&cie_nat_nbma) = AF_UNSPEC;
 286                                 cie_nat = nhrp_cie_pull(&extpl, pp->hdr,
 287                                                         &cie_nat_nbma,
 288                                                         &cie_nat_proto);
 289                                 /* We are interested only in peer CIE */
 290                                 if (cie_nat
 291                                     && sockunion_same(&cie_nat_proto, proto)) {
 292                                         nat_nbma = cie_nat_nbma;
 293                                 }
 294                         } while (cie_nat);
 295                 } break;
 296                 default:
 297                         break;
 298                 }
 299         }
 300
 301         /* Update cache entry for the protocol to nbma binding */
 302         if (sockunion_family(&nat_nbma) != AF_UNSPEC) {
 303                 debugf(NHRP_DEBUG_COMMON,
 304                        "Shortcut: NAT detected (NAT extension) proto %pSU NBMA %pSU claimed-NBMA %pSU",
 305                        proto, &nat_nbma, &cie_nbma);
 306                 nbma = &nat_nbma;
 307         }
 308         /* For NHRP resolution reply the cie_nbma in mandatory part is the
 309          * address of the actual address of the sender
 310          */
 311         else if (!sockunion_same(&cie_nbma, &pp->peer->vc->remote.nbma)
 312                  && !nhrp_nhs_match_ip(&pp->peer->vc->remote.nbma, nifp)) {
 313                 debugf(NHRP_DEBUG_COMMON,
 314                        "Shortcut: NAT detected (no NAT Extension) proto %pSU NBMA %pSU claimed-NBMA %pSU",
 315                        proto, &pp->peer->vc->remote.nbma, &cie_nbma);
 316                 nbma = &pp->peer->vc->remote.nbma;
 317                 nat_nbma = *nbma;
 318         } else {
 319                 nbma = &cie_nbma;
 320         }
 321
 322         debugf(NHRP_DEBUG_COMMON,
 323                "Shortcut: %pFX is at proto %pSU dst_proto %pSU NBMA %pSU cie-holdtime %d",
 324                &prefix, proto, &pp->dst_proto, nbma,
 325                htons(cie->holding_time));
 326
 327         if (sockunion_family(nbma)) {
 328                 c = nhrp_cache_get(pp->ifp, proto, 1);
 329                 if (c) {
 330                         debugf(NHRP_DEBUG_COMMON,
 331                                "Shortcut: cache found, update binding");
 332                         nhrp_cache_update_binding(c, NHRP_CACHE_DYNAMIC,
 333                                                   holding_time,
 334                                                   nhrp_peer_get(pp->ifp, nbma),
 335                                                   htons(cie->mtu),
 336                                                   nbma,
 337                                                   &cie_nbma);
 338                 } else {
 339                         debugf(NHRP_DEBUG_COMMON,
 340                                "Shortcut: no cache for proto %pSU", proto);
 341                 }
 342
 343                 /* Update cache binding for dst_proto as well */
 344                 if (sockunion_cmp(proto, &pp->dst_proto)) {
 345                         c_dst = nhrp_cache_get(pp->ifp, &pp->dst_proto, 1);
 346                         if (c_dst) {
 347                                 debugf(NHRP_DEBUG_COMMON,
 348                                        "Shortcut: cache found, update binding");
 349                                 nhrp_cache_update_binding(c_dst,
 350                                                   NHRP_CACHE_DYNAMIC,
 351                                                   holding_time,
 352                                                   nhrp_peer_get(pp->ifp, nbma),
 353                                                   htons(cie->mtu),
 354                                                   nbma,
 355                                                   &cie_nbma);
 356                         } else {
 357                                 debugf(NHRP_DEBUG_COMMON,
 358                                        "Shortcut: no cache for proto %pSU",
 359                                        &pp->dst_proto);
 360                         }
 361                 }
 362         }
 363
 364         /* Update shortcut entry for subnet to protocol gw binding */
 365         if (c) {
 366                 ps = nhrp_shortcut_get(&prefix);
 367                 if (ps) {
 368                         ps->addr = s->addr;
 369                         debugf(NHRP_DEBUG_COMMON,
 370                                "Shortcut: calling update_binding");
 371                         nhrp_shortcut_update_binding(ps, NHRP_CACHE_DYNAMIC, c,
 372                                                      holding_time);
 373                 } else {
 374                         debugf(NHRP_DEBUG_COMMON,
 375                                "Shortcut: proto diff but no ps");
 376                 }
 377         } else {
 378                 debugf(NHRP_DEBUG_COMMON,
 379                        "NO Shortcut because c NULL?%s or same proto?%s",
 380                        c ? "no" : "yes",
 381                        proto && pp && sockunion_same(proto, &pp->dst_proto)
 382                                ? "yes"
 383                                : "no");
 384         }
 385
 386         debugf(NHRP_DEBUG_COMMON, "Shortcut: Resolution reply handled");
 387 }
 388
 389 static void nhrp_shortcut_send_resolution_req(struct nhrp_shortcut *s)
 390 {
 391         struct zbuf *zb;
 392         struct nhrp_packet_header *hdr;
 393         struct interface *ifp;
 394         struct nhrp_interface *nifp;
 395         struct nhrp_afi_data *if_ad;
 396         struct nhrp_peer *peer;
 397         struct nhrp_cie_header *cie;
 398         struct nhrp_extension_header *ext;
 399
 400         if (nhrp_route_address(NULL, &s->addr, NULL, &peer)
 401             != NHRP_ROUTE_NBMA_NEXTHOP)
 402                 return;
 403
 404         if (s->type == NHRP_CACHE_INVALID || s->type == NHRP_CACHE_NEGATIVE)
 405                 s->type = NHRP_CACHE_INCOMPLETE;
 406
 407         ifp = peer->ifp;
 408         nifp = ifp->info;
 409
 410         /* Create request */
 411         zb = zbuf_alloc(1500);
 412         hdr = nhrp_packet_push(
 413                 zb, NHRP_PACKET_RESOLUTION_REQUEST, &nifp->nbma,
 414                 &nifp->afi[family2afi(sockunion_family(&s->addr))].addr,
 415                 &s->addr);
 416         hdr->u.request_id =
 417                 htonl(nhrp_reqid_alloc(&nhrp_packet_reqid, &s->reqid,
 418                                        nhrp_shortcut_recv_resolution_rep));
 419         hdr->flags = htons(NHRP_FLAG_RESOLUTION_SOURCE_IS_ROUTER
 420                            | NHRP_FLAG_RESOLUTION_AUTHORATIVE
 421                            | NHRP_FLAG_RESOLUTION_SOURCE_STABLE);
 422
 423         /* RFC2332 - One or zero CIEs, if CIE is present contains:
 424          *  - Prefix length: widest acceptable prefix we accept (if U set, 0xff)
 425          *  - MTU: MTU of the source station
 426          *  - Holding Time: Max time to cache the source information
 427          * */
 428         /* FIXME: push CIE for each local protocol address */
 429         cie = nhrp_cie_push(zb, NHRP_CODE_SUCCESS, NULL, NULL);
 430         cie->prefix_length = 0xff;
 431         if_ad = &nifp->afi[family2afi(sockunion_family(&s->addr))];
 432         cie->holding_time = htons(if_ad->holdtime);
 433         cie->mtu = htons(if_ad->mtu);
 434         debugf(NHRP_DEBUG_COMMON,
 435                "Shortcut res_req: set cie ht to %u and mtu to %u. shortcut ht is %u",
 436                ntohs(cie->holding_time), ntohs(cie->mtu), s->holding_time);
 437
 438         nhrp_ext_request(zb, hdr, ifp);
 439
 440         /* Cisco NAT detection extension */
 441         hdr->flags |= htons(NHRP_FLAG_RESOLUTION_NAT);
 442         ext = nhrp_ext_push(zb, hdr, NHRP_EXTENSION_NAT_ADDRESS);
 443         if (sockunion_family(&nifp->nat_nbma) != AF_UNSPEC) {
 444                 cie = nhrp_cie_push(zb, NHRP_CODE_SUCCESS, &nifp->nat_nbma,
 445                                     &if_ad->addr);
 446                 cie->prefix_length = 8 * sockunion_get_addrlen(&if_ad->addr);
 447                 cie->mtu = htons(if_ad->mtu);
 448                 nhrp_ext_complete(zb, ext);
 449         }
 450
 451         nhrp_packet_complete(zb, hdr);
 452
 453         nhrp_peer_send(peer, zb);
 454         nhrp_peer_unref(peer);
 455         zbuf_free(zb);
 456 }
 457
 458 void nhrp_shortcut_initiate(union sockunion *addr)
 459 {
 460         struct prefix p;
 461         struct nhrp_shortcut *s;
 462
 463         if (!sockunion2hostprefix(addr, &p))
 464                 return;
 465
 466         s = nhrp_shortcut_get(&p);
 467         if (s && s->type != NHRP_CACHE_INCOMPLETE) {
 468                 s->addr = *addr;
 469                 THREAD_OFF(s->t_timer);
 470                 thread_add_timer(master, nhrp_shortcut_do_purge, s, 30,
 471                                  &s->t_timer);
 472                 nhrp_shortcut_send_resolution_req(s);
 473         }
 474 }
 475
 476 void nhrp_shortcut_init(void)
 477 {
 478         shortcut_rib[AFI_IP] = route_table_init();
 479         shortcut_rib[AFI_IP6] = route_table_init();
 480 }
 481
 482 void nhrp_shortcut_terminate(void)
 483 {
 484         route_table_finish(shortcut_rib[AFI_IP]);
 485         route_table_finish(shortcut_rib[AFI_IP6]);
 486 }
 487
 488 void nhrp_shortcut_foreach(afi_t afi,
 489                            void (*cb)(struct nhrp_shortcut *, void *),
 490                            void *ctx)
 491 {
 492         struct route_table *rt = shortcut_rib[afi];
 493         struct route_node *rn;
 494         route_table_iter_t iter;
 495
 496         if (!rt)
 497                 return;
 498
 499         route_table_iter_init(&iter, rt);
 500         while ((rn = route_table_iter_next(&iter)) != NULL) {
 501                 if (rn->info)
 502                         cb(rn->info, ctx);
 503         }
 504         route_table_iter_cleanup(&iter);
 505 }
 506
 507 struct purge_ctx {
 508         const struct prefix *p;
 509         int deleted;
 510 };
 511
 512 void nhrp_shortcut_purge(struct nhrp_shortcut *s, int force)
 513 {
 514         THREAD_OFF(s->t_timer);
 515         nhrp_reqid_free(&nhrp_packet_reqid, &s->reqid);
 516
 517         if (force) {
 518                 /* Immediate purge on route with draw or pending shortcut */
 519                 thread_add_timer_msec(master, nhrp_shortcut_do_purge, s, 5,
 520                                       &s->t_timer);
 521         } else {
 522                 /* Soft expire - force immediate renewal, but purge
 523                  * in few seconds to make sure stale route is not
 524                  * used too long. In practice most purges are caused
 525                  * by hub bgp change, but target usually stays same.
 526                  * This allows to keep nhrp route up, and to not
 527                  * cause temporary rerouting via hubs causing latency
 528                  * jitter. */
 529                 thread_add_timer_msec(master, nhrp_shortcut_do_purge, s, 3000,
 530                                       &s->t_timer);
 531                 s->expiring = 1;
 532                 nhrp_shortcut_check_use(s);
 533         }
 534 }
 535
 536 static void nhrp_shortcut_purge_prefix(struct nhrp_shortcut *s, void *ctx)
 537 {
 538         struct purge_ctx *pctx = ctx;
 539
 540         if (prefix_match(pctx->p, s->p))
 541                 nhrp_shortcut_purge(s, pctx->deleted || !s->cache);
 542 }
 543
 544 void nhrp_shortcut_prefix_change(const struct prefix *p, int deleted)
 545 {
 546         struct purge_ctx pctx = {
 547                 .p = p, .deleted = deleted,
 548         };
 549         nhrp_shortcut_foreach(family2afi(PREFIX_FAMILY(p)),
 550                               nhrp_shortcut_purge_prefix, &pctx);
 551 }