lib/route-table.c

   1 /*
   2  * Copyright (c) 2011 Nicira Networks.
   3  *
   4  * Licensed under the Apache License, Version 2.0 (the "License");
   5  * you may not use this file except in compliance with the License.
   6  * You may obtain a copy of the License at:
   7  *
   8  *     http://www.apache.org/licenses/LICENSE-2.0
   9  *
  10  * Unless required by applicable law or agreed to in writing, software
  11  * distributed under the License is distributed on an "AS IS" BASIS,
  12  * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
  13  * See the License for the specific language governing permissions and
  14  * limitations under the License.
  15  */
  16
  17 #include <config.h>
  18
  19 #include "route-table.h"
  20
  21 #include <assert.h>
  22 #include <arpa/inet.h>
  23 #include <sys/socket.h>
  24 #include <linux/rtnetlink.h>
  25 #include <net/if.h>
  26
  27 #include "hash.h"
  28 #include "hmap.h"
  29 #include "netlink.h"
  30 #include "netlink-socket.h"
  31 #include "ofpbuf.h"
  32 #include "rtnetlink.h"
  33 #include "rtnetlink-link.h"
  34 #include "vlog.h"
  35
  36 VLOG_DEFINE_THIS_MODULE(route_table);
  37
  38 struct route_data {
  39     /* Copied from struct rtmsg. */
  40     unsigned char rtm_dst_len;
  41
  42     /* Extracted from Netlink attributes. */
  43     uint32_t rta_dst; /* Destination in host byte order. 0 if missing. */
  44     int rta_oif;      /* Output interface index. */
  45 };
  46
  47 /* A digested version of a route message sent down by the kernel to indicate
  48  * that a route has changed. */
  49 struct route_table_msg {
  50     bool relevant;        /* Should this message be processed? */
  51     int nlmsg_type;       /* e.g. RTM_NEWROUTE, RTM_DELROUTE. */
  52     struct route_data rd; /* Data parsed from this message. */
  53 };
  54
  55 struct route_node {
  56     struct hmap_node node; /* Node in route_map. */
  57     struct route_data rd;  /* Data associated with this node. */
  58 };
  59
  60 struct name_node {
  61     struct hmap_node node; /* Node in name_map. */
  62     uint32_t ifi_index;    /* Kernel interface index. */
  63
  64     char ifname[IFNAMSIZ]; /* Interface name. */
  65 };
  66
  67 static struct vlog_rate_limit rl = VLOG_RATE_LIMIT_INIT(5, 20);
  68
  69 static unsigned int register_count = 0;
  70 static struct rtnetlink *rtn = NULL;
  71 static struct route_table_msg rtmsg;
  72 static struct rtnetlink_notifier route_notifier;
  73 static struct rtnetlink_notifier name_notifier;
  74
  75 static bool route_table_valid = false;
  76 static bool name_table_valid = false;
  77 static struct hmap route_map;
  78 static struct hmap name_map;
  79
  80 static int route_table_reset(void);
  81 static void route_table_handle_msg(const struct route_table_msg *);
  82 static bool route_table_parse(struct ofpbuf *, struct route_table_msg *);
  83 static void route_table_change(const struct route_table_msg *, void *);
  84 static struct route_node *route_node_lookup(const struct route_data *);
  85 static struct route_node *route_node_lookup_by_ip(uint32_t ip);
  86 static void route_map_clear(void);
  87 static uint32_t hash_route_data(const struct route_data *);
  88
  89 static void name_table_init(void);
  90 static void name_table_uninit(void);
  91 static int name_table_reset(void);
  92 static void name_table_change(const struct rtnetlink_link_change *, void *);
  93 static void name_map_clear(void);
  94 static struct name_node *name_node_lookup(int ifi_index);
  95
  96 /* Populates 'name' with the name of the interface traffic destined for 'ip'
  97  * is likely to egress out of (see route_table_get_ifindex).
  98  *
  99  * Returns true if successful, otherwise false. */
 100 bool
 101 route_table_get_name(ovs_be32 ip, char name[IFNAMSIZ])
 102 {
 103     int ifindex;
 104
 105     if (!name_table_valid) {
 106         name_table_reset();
 107     }
 108
 109     if (route_table_get_ifindex(ip, &ifindex)) {
 110         struct name_node *nn;
 111
 112         nn = name_node_lookup(ifindex);
 113         if (nn) {
 114             ovs_strlcpy(name, nn->ifname, IFNAMSIZ);
 115             return true;
 116         }
 117     }
 118
 119     return false;
 120 }
 121
 122 /* Populates 'ifindex' with the interface index traffic destined for 'ip' is
 123  * likely to egress.  There is no hard guarantee that traffic destined for 'ip'
 124  * will egress out the specified interface.  'ifindex' may refer to an
 125  * interface which is not physical (such as a bridge port).
 126  *
 127  * Returns true if successful, otherwise false. */
 128 bool
 129 route_table_get_ifindex(ovs_be32 ip_, int *ifindex)
 130 {
 131     struct route_node *rn;
 132     uint32_t ip = ntohl(ip_);
 133
 134     *ifindex = 0;
 135
 136     if (!route_table_valid) {
 137         route_table_reset();
 138     }
 139
 140     rn = route_node_lookup_by_ip(ip);
 141
 142     if (rn) {
 143         *ifindex = rn->rd.rta_oif;
 144         return true;
 145     }
 146
 147     /* Choose a default route. */
 148     HMAP_FOR_EACH(rn, node, &route_map) {
 149         if (rn->rd.rta_dst == 0 && rn->rd.rtm_dst_len == 0) {
 150             *ifindex = rn->rd.rta_oif;
 151             return true;
 152         }
 153     }
 154
 155     return false;
 156 }
 157
 158 /* Users of the route_table module should register themselves with this
 159  * function before making any other route_table function calls. */
 160 void
 161 route_table_register(void)
 162 {
 163     if (!register_count) {
 164         rtnetlink_parse_func *pf;
 165         rtnetlink_notify_func *nf;
 166
 167         assert(!rtn);
 168
 169         pf = (rtnetlink_parse_func *)  route_table_parse;
 170         nf = (rtnetlink_notify_func *) route_table_change;
 171
 172         rtn = rtnetlink_create(RTNLGRP_IPV4_ROUTE, pf, &rtmsg);
 173         rtnetlink_notifier_register(rtn, &route_notifier, nf, NULL);
 174
 175         hmap_init(&route_map);
 176         route_table_reset();
 177         name_table_init();
 178     }
 179
 180     register_count++;
 181 }
 182
 183 /* Users of the route_table module should unregister themselves with this
 184  * function when they will no longer be making any more route_table fuction
 185  * calls. */
 186 void
 187 route_table_unregister(void)
 188 {
 189     register_count--;
 190
 191     if (!register_count) {
 192         rtnetlink_destroy(rtn);
 193         rtn = NULL;
 194
 195         route_map_clear();
 196         hmap_destroy(&route_map);
 197         name_table_uninit();
 198     }
 199 }
 200
 201 /* Run periodically to update the locally maintained routing table. */
 202 void
 203 route_table_run(void)
 204 {
 205     if (rtn) {
 206         rtnetlink_link_notifier_run();
 207         rtnetlink_notifier_run(rtn);
 208     }
 209 }
 210
 211 /* Causes poll_block() to wake up when route_table updates are required. */
 212 void
 213 route_table_wait(void)
 214 {
 215     if (rtn) {
 216         rtnetlink_link_notifier_wait();
 217         rtnetlink_notifier_wait(rtn);
 218     }
 219 }
 220
 221 static int
 222 route_table_reset(void)
 223 {
 224     int error;
 225     struct nl_dump dump;
 226     struct rtgenmsg *rtmsg;
 227     struct ofpbuf request, reply;
 228     static struct nl_sock *rtnl_sock;
 229
 230     route_map_clear();
 231     route_table_valid = true;
 232
 233     error = nl_sock_create(NETLINK_ROUTE, &rtnl_sock);
 234     if (error) {
 235         VLOG_WARN_RL(&rl, "failed to reset routing table, "
 236                      "cannot create RTNETLINK_ROUTE socket");
 237         return error;
 238     }
 239
 240     ofpbuf_init(&request, 0);
 241
 242     nl_msg_put_nlmsghdr(&request, sizeof *rtmsg, RTM_GETROUTE, NLM_F_REQUEST);
 243
 244     rtmsg = ofpbuf_put_zeros(&request, sizeof *rtmsg);
 245     rtmsg->rtgen_family = AF_INET;
 246
 247     nl_dump_start(&dump, rtnl_sock, &request);
 248
 249     while (nl_dump_next(&dump, &reply)) {
 250         struct route_table_msg msg;
 251
 252         if (route_table_parse(&reply, &msg)) {
 253             route_table_handle_msg(&msg);
 254         }
 255     }
 256
 257     error = nl_dump_done(&dump);
 258     nl_sock_destroy(rtnl_sock);
 259
 260     return error;
 261 }
 262
 263
 264 static bool
 265 route_table_parse(struct ofpbuf *buf, struct route_table_msg *change)
 266 {
 267     bool parsed;
 268
 269     static const struct nl_policy policy[] = {
 270         [RTA_DST] = { .type = NL_A_U32, .optional = true  },
 271         [RTA_OIF] = { .type = NL_A_U32, .optional = false },
 272     };
 273
 274     static struct nlattr *attrs[ARRAY_SIZE(policy)];
 275
 276     parsed = nl_policy_parse(buf, NLMSG_HDRLEN + sizeof(struct rtmsg),
 277                              policy, attrs, ARRAY_SIZE(policy));
 278
 279     if (parsed) {
 280         const struct rtmsg *rtm;
 281         const struct nlmsghdr *nlmsg;
 282
 283         nlmsg = buf->data;
 284         rtm = (const struct rtmsg *) ((const char *) buf->data + NLMSG_HDRLEN);
 285
 286         if (rtm->rtm_family != AF_INET) {
 287             VLOG_DBG_RL(&rl, "received non AF_INET rtnetlink route message");
 288             return false;
 289         }
 290
 291         memset(change, 0, sizeof *change);
 292         change->relevant = true;
 293
 294         if (rtm->rtm_scope == RT_SCOPE_NOWHERE) {
 295             change->relevant = false;
 296         }
 297
 298         if (rtm->rtm_type != RTN_UNICAST &&
 299             rtm->rtm_type != RTN_LOCAL) {
 300             change->relevant = false;
 301         }
 302
 303         change->nlmsg_type     = nlmsg->nlmsg_type;
 304         change->rd.rtm_dst_len = rtm->rtm_dst_len;
 305         change->rd.rta_oif     = nl_attr_get_u32(attrs[RTA_OIF]);
 306
 307         if (attrs[RTA_DST]) {
 308             change->rd.rta_dst = ntohl(nl_attr_get_be32(attrs[RTA_DST]));
 309         }
 310
 311     } else {
 312         VLOG_DBG_RL(&rl, "received unparseable rtnetlink route message");
 313     }
 314
 315     return parsed;
 316 }
 317
 318 static void
 319 route_table_change(const struct route_table_msg *change OVS_UNUSED,
 320                    void *aux OVS_UNUSED)
 321 {
 322     route_table_valid = false;
 323 }
 324
 325 static void
 326 route_table_handle_msg(const struct route_table_msg *change)
 327 {
 328     if (change->relevant && change->nlmsg_type == RTM_NEWROUTE &&
 329         !route_node_lookup(&change->rd)) {
 330         struct route_node *rn;
 331
 332         rn = xzalloc(sizeof *rn);
 333         memcpy(&rn->rd, &change->rd, sizeof change->rd);
 334
 335         hmap_insert(&route_map, &rn->node, hash_route_data(&rn->rd));
 336     }
 337 }
 338
 339 static struct route_node *
 340 route_node_lookup(const struct route_data *rd)
 341 {
 342     struct route_node *rn;
 343
 344     HMAP_FOR_EACH_WITH_HASH(rn, node, hash_route_data(rd), &route_map) {
 345         if (!memcmp(&rn->rd, rd, sizeof *rd)) {
 346             return rn;
 347         }
 348     }
 349
 350     return NULL;
 351 }
 352
 353 static struct route_node *
 354 route_node_lookup_by_ip(uint32_t ip)
 355 {
 356     int dst_len;
 357     struct route_node *rn, *rn_ret;
 358
 359     dst_len = -1;
 360     rn_ret  = NULL;
 361
 362     HMAP_FOR_EACH(rn, node, &route_map) {
 363         uint32_t mask = 0xffffffff << (32 - rn->rd.rtm_dst_len);
 364
 365         if (rn->rd.rta_dst == 0 && rn->rd.rtm_dst_len == 0) {
 366             /* Default route. */
 367             continue;
 368         }
 369
 370         if (rn->rd.rtm_dst_len > dst_len &&
 371             (ip & mask) == (rn->rd.rta_dst & mask)) {
 372             rn_ret  = rn;
 373             dst_len = rn->rd.rtm_dst_len;
 374         }
 375     }
 376
 377     return rn_ret;
 378 }
 379
 380 static void
 381 route_map_clear(void)
 382 {
 383     struct route_node *rn, *rn_next;
 384
 385     HMAP_FOR_EACH_SAFE(rn, rn_next, node, &route_map) {
 386         hmap_remove(&route_map, &rn->node);
 387         free(rn);
 388     }
 389 }
 390
 391 static uint32_t
 392 hash_route_data(const struct route_data *rd)
 393 {
 394     return hash_bytes(rd, sizeof *rd, 0);
 395 }
 396 \f
 397 /* name_table . */
 398
 399 static void
 400 name_table_init(void)
 401 {
 402     hmap_init(&name_map);
 403     rtnetlink_link_notifier_register(&name_notifier, name_table_change, NULL);
 404     name_table_valid = false;
 405 }
 406
 407 static void
 408 name_table_uninit(void)
 409 {
 410     rtnetlink_link_notifier_unregister(&name_notifier);
 411     name_map_clear();
 412     hmap_destroy(&name_map);
 413 }
 414
 415 static int
 416 name_table_reset(void)
 417 {
 418     int error;
 419     struct nl_dump dump;
 420     struct rtgenmsg *rtmsg;
 421     struct ofpbuf request, reply;
 422     static struct nl_sock *rtnl_sock;
 423
 424     name_table_valid = true;
 425     name_map_clear();
 426     error = nl_sock_create(NETLINK_ROUTE, &rtnl_sock);
 427     if (error) {
 428         VLOG_WARN_RL(&rl, "failed to create NETLINK_ROUTE socket");
 429         return error;
 430     }
 431
 432     ofpbuf_init(&request, 0);
 433     nl_msg_put_nlmsghdr(&request, sizeof *rtmsg, RTM_GETLINK, NLM_F_REQUEST);
 434     rtmsg = ofpbuf_put_zeros(&request, sizeof *rtmsg);
 435     rtmsg->rtgen_family = AF_INET;
 436
 437     nl_dump_start(&dump, rtnl_sock, &request);
 438     while (nl_dump_next(&dump, &reply)) {
 439         struct rtnetlink_link_change change;
 440
 441         if (rtnetlink_link_parse(&reply, &change)
 442             && change.nlmsg_type == RTM_NEWLINK
 443             && !name_node_lookup(change.ifi_index)) {
 444             struct name_node *nn;
 445
 446             nn = xzalloc(sizeof *nn);
 447             nn->ifi_index = change.ifi_index;
 448             ovs_strlcpy(nn->ifname, change.ifname, IFNAMSIZ);
 449             hmap_insert(&name_map, &nn->node, hash_int(nn->ifi_index, 0));
 450         }
 451     }
 452     nl_sock_destroy(rtnl_sock);
 453     return nl_dump_done(&dump);
 454 }
 455
 456 static void
 457 name_table_change(const struct rtnetlink_link_change *change OVS_UNUSED,
 458                   void *aux OVS_UNUSED)
 459 {
 460     /* Changes to interface status can cause routing table changes that some
 461      * versions of the linux kernel do not advertise for some reason. */
 462     route_table_valid = false;
 463     name_table_valid = false;
 464 }
 465
 466 static struct name_node *
 467 name_node_lookup(int ifi_index)
 468 {
 469     struct name_node *nn;
 470
 471     HMAP_FOR_EACH_WITH_HASH(nn, node, hash_int(ifi_index, 0), &name_map) {
 472         if (nn->ifi_index == ifi_index) {
 473             return nn;
 474         }
 475     }
 476
 477     return NULL;
 478 }
 479
 480 static void
 481 name_map_clear(void)
 482 {
 483     struct name_node *nn, *nn_next;
 484
 485     HMAP_FOR_EACH_SAFE(nn, nn_next, node, &name_map) {
 486         hmap_remove(&name_map, &nn->node);
 487         free(nn);
 488     }
 489 }