src/libsystemd-network/sd-lldp.c

   1 /* SPDX-License-Identifier: LGPL-2.1-or-later */
   2
   3 #include <arpa/inet.h>
   4 #include <linux/sockios.h>
   5 #include <sys/ioctl.h>
   6
   7 #include "sd-lldp.h"
   8
   9 #include "alloc-util.h"
  10 #include "ether-addr-util.h"
  11 #include "event-util.h"
  12 #include "fd-util.h"
  13 #include "lldp-internal.h"
  14 #include "lldp-neighbor.h"
  15 #include "lldp-network.h"
  16 #include "memory-util.h"
  17 #include "socket-util.h"
  18 #include "sort-util.h"
  19 #include "string-table.h"
  20
  21 #define LLDP_DEFAULT_NEIGHBORS_MAX 128U
  22
  23 static const char * const lldp_event_table[_SD_LLDP_EVENT_MAX] = {
  24         [SD_LLDP_EVENT_ADDED]     = "added",
  25         [SD_LLDP_EVENT_REMOVED]   = "removed",
  26         [SD_LLDP_EVENT_UPDATED]   = "updated",
  27         [SD_LLDP_EVENT_REFRESHED] = "refreshed",
  28 };
  29
  30 DEFINE_STRING_TABLE_LOOKUP(lldp_event, sd_lldp_event_t);
  31
  32 static void lldp_flush_neighbors(sd_lldp *lldp) {
  33         assert(lldp);
  34
  35         hashmap_clear(lldp->neighbor_by_id);
  36 }
  37
  38 static void lldp_callback(sd_lldp *lldp, sd_lldp_event_t event, sd_lldp_neighbor *n) {
  39         assert(lldp);
  40         assert(event >= 0 && event < _SD_LLDP_EVENT_MAX);
  41
  42         if (!lldp->callback) {
  43                 log_lldp("Received '%s' event.", lldp_event_to_string(event));
  44                 return;
  45         }
  46
  47         log_lldp("Invoking callback for '%s' event.", lldp_event_to_string(event));
  48         lldp->callback(lldp, event, n, lldp->userdata);
  49 }
  50
  51 static int lldp_make_space(sd_lldp *lldp, size_t extra) {
  52         usec_t t = USEC_INFINITY;
  53         bool changed = false;
  54
  55         assert(lldp);
  56
  57         /* Remove all entries that are past their TTL, and more until at least the specified number of extra entries
  58          * are free. */
  59
  60         for (;;) {
  61                 _cleanup_(sd_lldp_neighbor_unrefp) sd_lldp_neighbor *n = NULL;
  62
  63                 n = prioq_peek(lldp->neighbor_by_expiry);
  64                 if (!n)
  65                         break;
  66
  67                 sd_lldp_neighbor_ref(n);
  68
  69                 if (hashmap_size(lldp->neighbor_by_id) > LESS_BY(lldp->neighbors_max, extra))
  70                         goto remove_one;
  71
  72                 if (t == USEC_INFINITY)
  73                         t = now(clock_boottime_or_monotonic());
  74
  75                 if (n->until > t)
  76                         break;
  77
  78         remove_one:
  79                 lldp_neighbor_unlink(n);
  80                 lldp_callback(lldp, SD_LLDP_EVENT_REMOVED, n);
  81                 changed = true;
  82         }
  83
  84         return changed;
  85 }
  86
  87 static bool lldp_keep_neighbor(sd_lldp *lldp, sd_lldp_neighbor *n) {
  88         assert(lldp);
  89         assert(n);
  90
  91         /* Don't keep data with a zero TTL */
  92         if (n->ttl <= 0)
  93                 return false;
  94
  95         /* Filter out data from the filter address */
  96         if (!ether_addr_is_null(&lldp->filter_address) &&
  97             ether_addr_equal(&lldp->filter_address, &n->source_address))
  98                 return false;
  99
 100         /* Only add if the neighbor has a capability we are interested in. Note that we also store all neighbors with
 101          * no caps field set. */
 102         if (n->has_capabilities &&
 103             (n->enabled_capabilities & lldp->capability_mask) == 0)
 104                 return false;
 105
 106         /* Keep everything else */
 107         return true;
 108 }
 109
 110 static int lldp_start_timer(sd_lldp *lldp, sd_lldp_neighbor *neighbor);
 111
 112 static int lldp_add_neighbor(sd_lldp *lldp, sd_lldp_neighbor *n) {
 113         _cleanup_(sd_lldp_neighbor_unrefp) sd_lldp_neighbor *old = NULL;
 114         bool keep;
 115         int r;
 116
 117         assert(lldp);
 118         assert(n);
 119         assert(!n->lldp);
 120
 121         keep = lldp_keep_neighbor(lldp, n);
 122
 123         /* First retrieve the old entry for this MSAP */
 124         old = hashmap_get(lldp->neighbor_by_id, &n->id);
 125         if (old) {
 126                 sd_lldp_neighbor_ref(old);
 127
 128                 if (!keep) {
 129                         lldp_neighbor_unlink(old);
 130                         lldp_callback(lldp, SD_LLDP_EVENT_REMOVED, old);
 131                         return 0;
 132                 }
 133
 134                 if (lldp_neighbor_equal(n, old)) {
 135                         /* Is this equal, then restart the TTL counter, but don't do anything else. */
 136                         old->timestamp = n->timestamp;
 137                         lldp_start_timer(lldp, old);
 138                         lldp_callback(lldp, SD_LLDP_EVENT_REFRESHED, old);
 139                         return 0;
 140                 }
 141
 142                 /* Data changed, remove the old entry, and add a new one */
 143                 lldp_neighbor_unlink(old);
 144
 145         } else if (!keep)
 146                 return 0;
 147
 148         /* Then, make room for at least one new neighbor */
 149         lldp_make_space(lldp, 1);
 150
 151         r = hashmap_put(lldp->neighbor_by_id, &n->id, n);
 152         if (r < 0)
 153                 goto finish;
 154
 155         r = prioq_put(lldp->neighbor_by_expiry, n, &n->prioq_idx);
 156         if (r < 0) {
 157                 assert_se(hashmap_remove(lldp->neighbor_by_id, &n->id) == n);
 158                 goto finish;
 159         }
 160
 161         n->lldp = lldp;
 162
 163         lldp_start_timer(lldp, n);
 164         lldp_callback(lldp, old ? SD_LLDP_EVENT_UPDATED : SD_LLDP_EVENT_ADDED, n);
 165
 166         return 1;
 167
 168 finish:
 169         if (old)
 170                 lldp_callback(lldp, SD_LLDP_EVENT_REMOVED, old);
 171
 172         return r;
 173 }
 174
 175 static int lldp_handle_datagram(sd_lldp *lldp, sd_lldp_neighbor *n) {
 176         int r;
 177
 178         assert(lldp);
 179         assert(n);
 180
 181         r = lldp_neighbor_parse(n);
 182         if (r == -EBADMSG) /* Ignore bad messages */
 183                 return 0;
 184         if (r < 0)
 185                 return r;
 186
 187         r = lldp_add_neighbor(lldp, n);
 188         if (r < 0) {
 189                 log_lldp_errno(r, "Failed to add datagram. Ignoring.");
 190                 return 0;
 191         }
 192
 193         log_lldp("Successfully processed LLDP datagram.");
 194         return 0;
 195 }
 196
 197 static int lldp_receive_datagram(sd_event_source *s, int fd, uint32_t revents, void *userdata) {
 198         _cleanup_(sd_lldp_neighbor_unrefp) sd_lldp_neighbor *n = NULL;
 199         ssize_t space, length;
 200         sd_lldp *lldp = userdata;
 201         struct timespec ts;
 202
 203         assert(fd >= 0);
 204         assert(lldp);
 205
 206         space = next_datagram_size_fd(fd);
 207         if (space < 0)
 208                 return log_lldp_errno(space, "Failed to determine datagram size to read: %m");
 209
 210         n = lldp_neighbor_new(space);
 211         if (!n)
 212                 return -ENOMEM;
 213
 214         length = recv(fd, LLDP_NEIGHBOR_RAW(n), n->raw_size, MSG_DONTWAIT);
 215         if (length < 0) {
 216                 if (IN_SET(errno, EAGAIN, EINTR))
 217                         return 0;
 218
 219                 return log_lldp_errno(errno, "Failed to read LLDP datagram: %m");
 220         }
 221
 222         if ((size_t) length != n->raw_size) {
 223                 log_lldp("Packet size mismatch.");
 224                 return -EINVAL;
 225         }
 226
 227         /* Try to get the timestamp of this packet if it is known */
 228         if (ioctl(fd, SIOCGSTAMPNS, &ts) >= 0)
 229                 triple_timestamp_from_realtime(&n->timestamp, timespec_load(&ts));
 230         else
 231                 triple_timestamp_get(&n->timestamp);
 232
 233         return lldp_handle_datagram(lldp, n);
 234 }
 235
 236 static void lldp_reset(sd_lldp *lldp) {
 237         assert(lldp);
 238
 239         (void) event_source_disable(lldp->timer_event_source);
 240         lldp->io_event_source = sd_event_source_unref(lldp->io_event_source);
 241         lldp->fd = safe_close(lldp->fd);
 242 }
 243
 244 _public_ int sd_lldp_start(sd_lldp *lldp) {
 245         int r;
 246
 247         assert_return(lldp, -EINVAL);
 248         assert_return(lldp->event, -EINVAL);
 249         assert_return(lldp->ifindex > 0, -EINVAL);
 250
 251         if (lldp->fd >= 0)
 252                 return 0;
 253
 254         assert(!lldp->io_event_source);
 255
 256         lldp->fd = lldp_network_bind_raw_socket(lldp->ifindex);
 257         if (lldp->fd < 0)
 258                 return lldp->fd;
 259
 260         r = sd_event_add_io(lldp->event, &lldp->io_event_source, lldp->fd, EPOLLIN, lldp_receive_datagram, lldp);
 261         if (r < 0)
 262                 goto fail;
 263
 264         r = sd_event_source_set_priority(lldp->io_event_source, lldp->event_priority);
 265         if (r < 0)
 266                 goto fail;
 267
 268         (void) sd_event_source_set_description(lldp->io_event_source, "lldp-io");
 269
 270         log_lldp("Started LLDP client");
 271         return 1;
 272
 273 fail:
 274         lldp_reset(lldp);
 275         return r;
 276 }
 277
 278 _public_ int sd_lldp_stop(sd_lldp *lldp) {
 279         if (!lldp)
 280                 return 0;
 281
 282         if (lldp->fd < 0)
 283                 return 0;
 284
 285         log_lldp("Stopping LLDP client");
 286
 287         lldp_reset(lldp);
 288         lldp_flush_neighbors(lldp);
 289
 290         return 1;
 291 }
 292
 293 _public_ int sd_lldp_attach_event(sd_lldp *lldp, sd_event *event, int64_t priority) {
 294         int r;
 295
 296         assert_return(lldp, -EINVAL);
 297         assert_return(lldp->fd < 0, -EBUSY);
 298         assert_return(!lldp->event, -EBUSY);
 299
 300         if (event)
 301                 lldp->event = sd_event_ref(event);
 302         else {
 303                 r = sd_event_default(&lldp->event);
 304                 if (r < 0)
 305                         return r;
 306         }
 307
 308         lldp->event_priority = priority;
 309
 310         return 0;
 311 }
 312
 313 _public_ int sd_lldp_detach_event(sd_lldp *lldp) {
 314
 315         assert_return(lldp, -EINVAL);
 316         assert_return(lldp->fd < 0, -EBUSY);
 317
 318         lldp->event = sd_event_unref(lldp->event);
 319         return 0;
 320 }
 321
 322 _public_ sd_event* sd_lldp_get_event(sd_lldp *lldp) {
 323         assert_return(lldp, NULL);
 324
 325         return lldp->event;
 326 }
 327
 328 _public_ int sd_lldp_set_callback(sd_lldp *lldp, sd_lldp_callback_t cb, void *userdata) {
 329         assert_return(lldp, -EINVAL);
 330
 331         lldp->callback = cb;
 332         lldp->userdata = userdata;
 333
 334         return 0;
 335 }
 336
 337 _public_ int sd_lldp_set_ifindex(sd_lldp *lldp, int ifindex) {
 338         assert_return(lldp, -EINVAL);
 339         assert_return(ifindex > 0, -EINVAL);
 340         assert_return(lldp->fd < 0, -EBUSY);
 341
 342         lldp->ifindex = ifindex;
 343         return 0;
 344 }
 345
 346 static sd_lldp* lldp_free(sd_lldp *lldp) {
 347         assert(lldp);
 348
 349         lldp->timer_event_source = sd_event_source_unref(lldp->timer_event_source);
 350
 351         lldp_reset(lldp);
 352         sd_lldp_detach_event(lldp);
 353         lldp_flush_neighbors(lldp);
 354
 355         hashmap_free(lldp->neighbor_by_id);
 356         prioq_free(lldp->neighbor_by_expiry);
 357         return mfree(lldp);
 358 }
 359
 360 DEFINE_PUBLIC_TRIVIAL_REF_UNREF_FUNC(sd_lldp, sd_lldp, lldp_free);
 361
 362 _public_ int sd_lldp_new(sd_lldp **ret) {
 363         _cleanup_(sd_lldp_unrefp) sd_lldp *lldp = NULL;
 364         int r;
 365
 366         assert_return(ret, -EINVAL);
 367
 368         lldp = new(sd_lldp, 1);
 369         if (!lldp)
 370                 return -ENOMEM;
 371
 372         *lldp = (sd_lldp) {
 373                 .n_ref = 1,
 374                 .fd = -1,
 375                 .neighbors_max = LLDP_DEFAULT_NEIGHBORS_MAX,
 376                 .capability_mask = UINT16_MAX,
 377         };
 378
 379         lldp->neighbor_by_id = hashmap_new(&lldp_neighbor_hash_ops);
 380         if (!lldp->neighbor_by_id)
 381                 return -ENOMEM;
 382
 383         r = prioq_ensure_allocated(&lldp->neighbor_by_expiry, lldp_neighbor_prioq_compare_func);
 384         if (r < 0)
 385                 return r;
 386
 387         *ret = TAKE_PTR(lldp);
 388
 389         return 0;
 390 }
 391
 392 static int neighbor_compare_func(sd_lldp_neighbor * const *a, sd_lldp_neighbor * const *b) {
 393         return lldp_neighbor_id_compare_func(&(*a)->id, &(*b)->id);
 394 }
 395
 396 static int on_timer_event(sd_event_source *s, uint64_t usec, void *userdata) {
 397         sd_lldp *lldp = userdata;
 398         int r;
 399
 400         r = lldp_make_space(lldp, 0);
 401         if (r < 0)
 402                 return log_lldp_errno(r, "Failed to make space: %m");
 403
 404         r = lldp_start_timer(lldp, NULL);
 405         if (r < 0)
 406                 return log_lldp_errno(r, "Failed to restart timer: %m");
 407
 408         return 0;
 409 }
 410
 411 static int lldp_start_timer(sd_lldp *lldp, sd_lldp_neighbor *neighbor) {
 412         sd_lldp_neighbor *n;
 413
 414         assert(lldp);
 415
 416         if (neighbor)
 417                 lldp_neighbor_start_ttl(neighbor);
 418
 419         n = prioq_peek(lldp->neighbor_by_expiry);
 420         if (!n)
 421                 return event_source_disable(lldp->timer_event_source);
 422
 423         if (!lldp->event)
 424                 return 0;
 425
 426         return event_reset_time(lldp->event, &lldp->timer_event_source,
 427                                 clock_boottime_or_monotonic(),
 428                                 n->until, 0,
 429                                 on_timer_event, lldp,
 430                                 lldp->event_priority, "lldp-timer", true);
 431 }
 432
 433 _public_ int sd_lldp_get_neighbors(sd_lldp *lldp, sd_lldp_neighbor ***ret) {
 434         sd_lldp_neighbor **l = NULL, *n;
 435         int k = 0, r;
 436
 437         assert_return(lldp, -EINVAL);
 438         assert_return(ret, -EINVAL);
 439
 440         if (hashmap_isempty(lldp->neighbor_by_id)) { /* Special shortcut */
 441                 *ret = NULL;
 442                 return 0;
 443         }
 444
 445         l = new0(sd_lldp_neighbor*, hashmap_size(lldp->neighbor_by_id));
 446         if (!l)
 447                 return -ENOMEM;
 448
 449         r = lldp_start_timer(lldp, NULL);
 450         if (r < 0) {
 451                 free(l);
 452                 return r;
 453         }
 454
 455         HASHMAP_FOREACH(n, lldp->neighbor_by_id)
 456                 l[k++] = sd_lldp_neighbor_ref(n);
 457
 458         assert((size_t) k == hashmap_size(lldp->neighbor_by_id));
 459
 460         /* Return things in a stable order */
 461         typesafe_qsort(l, k, neighbor_compare_func);
 462         *ret = l;
 463
 464         return k;
 465 }
 466
 467 _public_ int sd_lldp_set_neighbors_max(sd_lldp *lldp, uint64_t m) {
 468         assert_return(lldp, -EINVAL);
 469         assert_return(m > 0, -EINVAL);
 470
 471         lldp->neighbors_max = m;
 472         lldp_make_space(lldp, 0);
 473
 474         return 0;
 475 }
 476
 477 _public_ int sd_lldp_match_capabilities(sd_lldp *lldp, uint16_t mask) {
 478         assert_return(lldp, -EINVAL);
 479         assert_return(mask != 0, -EINVAL);
 480
 481         lldp->capability_mask = mask;
 482
 483         return 0;
 484 }
 485
 486 _public_ int sd_lldp_set_filter_address(sd_lldp *lldp, const struct ether_addr *addr) {
 487         assert_return(lldp, -EINVAL);
 488
 489         /* In order to deal nicely with bridges that send back our own packets, allow one address to be filtered, so
 490          * that our own can be filtered out here. */
 491
 492         if (addr)
 493                 lldp->filter_address = *addr;
 494         else
 495                 zero(lldp->filter_address);
 496
 497         return 0;
 498 }