main.c

   1 /*
   2  *   Copyright (C) 2010 Felix Fietkau <nbd@openwrt.org>
   3  *
   4  *   This program is free software; you can redistribute it and/or modify
   5  *   it under the terms of the GNU General Public License v2 as published by
   6  *   the Free Software Foundation.
   7  *
   8  *   This program is distributed in the hope that it will be useful,
   9  *   but WITHOUT ANY WARRANTY; without even the implied warranty of
  10  *   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  11  *   GNU General Public License for more details.
  12  *
  13  *   You should have received a copy of the GNU General Public License
  14  *   along with this program; if not, write to the Free Software
  15  *   Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307, USA.
  16  *
  17  */
  18 #include <sys/ioctl.h>
  19 #include <sys/socket.h>
  20
  21 #include <stdio.h>
  22 #include <unistd.h>
  23 #include <fcntl.h>
  24 #include <stddef.h>
  25 #include <stdlib.h>
  26 #include <stdint.h>
  27 #include <stdbool.h>
  28 #include <errno.h>
  29 #include <signal.h>
  30 #include <string.h>
  31
  32 #include "relayd.h"
  33
  34 LIST_HEAD(interfaces);
  35 int debug;
  36
  37 static int host_timeout;
  38 static int inet_sock;
  39 static int forward_bcast;
  40 static int forward_dhcp;
  41
  42 static struct relayd_host *find_host_by_ipaddr(struct relayd_interface *rif, const uint8_t *ipaddr)
  43 {
  44         struct relayd_host *host;
  45
  46         if (!rif) {
  47                 list_for_each_entry(rif, &interfaces, list) {
  48                         host = find_host_by_ipaddr(rif, ipaddr);
  49                         if (!host)
  50                                 continue;
  51
  52                         return host;
  53                 }
  54                 return NULL;
  55         }
  56
  57         list_for_each_entry(host, &rif->hosts, list) {
  58                 if (memcmp(ipaddr, host->ipaddr, sizeof(host->ipaddr)) != 0)
  59                         continue;
  60
  61                 return host;
  62         }
  63         return NULL;
  64 }
  65
  66 static void add_arp(struct relayd_host *host)
  67 {
  68         struct sockaddr_in *sin;
  69         struct arpreq arp;
  70
  71         strncpy(arp.arp_dev, host->rif->ifname, sizeof(arp.arp_dev));
  72         arp.arp_flags = ATF_COM;
  73
  74         arp.arp_ha.sa_family = ARPHRD_ETHER;
  75         memcpy(arp.arp_ha.sa_data, host->lladdr, ETH_ALEN);
  76
  77         sin = (struct sockaddr_in *) &arp.arp_pa;
  78         sin->sin_family = AF_INET;
  79         memcpy(&sin->sin_addr, host->ipaddr, sizeof(host->ipaddr));
  80
  81         ioctl(inet_sock, SIOCSARP, &arp);
  82 }
  83
  84 static void del_host(struct relayd_host *host)
  85 {
  86         DPRINTF(1, "%s: deleting host "IP_FMT" ("MAC_FMT")\n", host->rif->ifname,
  87                 IP_BUF(host->ipaddr), MAC_BUF(host->lladdr));
  88
  89         if (host->rif->managed)
  90                 relayd_del_route(host);
  91         uloop_timeout_cancel(&host->timeout);
  92         list_del(&host->list);
  93         free(host);
  94 }
  95
  96 static void fill_arp_request(struct arp_packet *pkt, struct relayd_interface *rif,
  97                              uint8_t spa[4], uint8_t tpa[4])
  98 {
  99         memset(pkt, 0, sizeof(*pkt));
 100
 101         pkt->eth.ether_type = htons(ETHERTYPE_ARP);
 102         memcpy(pkt->eth.ether_shost, rif->sll.sll_addr, ETH_ALEN);
 103
 104         memcpy(pkt->arp.arp_sha, rif->sll.sll_addr, ETH_ALEN);
 105         memcpy(pkt->arp.arp_spa, spa, 4);
 106         memcpy(pkt->arp.arp_tpa, tpa, 4);
 107
 108         pkt->arp.arp_hrd = htons(ARPHRD_ETHER);
 109         pkt->arp.arp_pro = htons(ETH_P_IP);
 110         pkt->arp.arp_hln = ETH_ALEN;
 111         pkt->arp.arp_pln = 4;
 112 }
 113
 114 static void send_arp_request(struct relayd_host *host)
 115 {
 116         struct relayd_interface *rif = host->rif;
 117         struct arp_packet pkt;
 118
 119         fill_arp_request(&pkt, host->rif, host->rif->src_ip, host->ipaddr);
 120
 121         pkt.arp.arp_op = htons(ARPOP_REQUEST);
 122         memcpy(pkt.arp.arp_spa, rif->src_ip, ETH_ALEN);
 123         memset(pkt.arp.arp_tha, 0, ETH_ALEN);
 124         memset(pkt.eth.ether_dhost, 0xff, ETH_ALEN);
 125
 126         DPRINTF(2, "%s: sending ARP who-has "IP_FMT", tell "IP_FMT" ("MAC_FMT")\n",
 127                 rif->ifname, IP_BUF(pkt.arp.arp_tpa),
 128                 IP_BUF(pkt.arp.arp_spa), MAC_BUF(pkt.eth.ether_shost));
 129
 130         sendto(rif->fd.fd, &pkt, sizeof(pkt), 0,
 131                 (struct sockaddr *) &rif->sll, sizeof(rif->sll));
 132 }
 133
 134 static void send_arp_reply(struct relayd_interface *rif, uint8_t spa[4],
 135                            uint8_t tha[ETH_ALEN], uint8_t tpa[4])
 136 {
 137         struct arp_packet pkt;
 138
 139         fill_arp_request(&pkt, rif, spa, tpa);
 140
 141         pkt.arp.arp_op = htons(ARPOP_REPLY);
 142         memcpy(pkt.eth.ether_dhost, tha, ETH_ALEN);
 143         memcpy(pkt.arp.arp_tha, tha, ETH_ALEN);
 144
 145         DPRINTF(2, "%s: sending ARP reply to "IP_FMT", "IP_FMT" is at ("MAC_FMT")\n",
 146                 rif->ifname, IP_BUF(pkt.arp.arp_tpa),
 147                 IP_BUF(pkt.arp.arp_spa), MAC_BUF(pkt.eth.ether_shost));
 148
 149         sendto(rif->fd.fd, &pkt, sizeof(pkt), 0,
 150                 (struct sockaddr *) &rif->sll, sizeof(rif->sll));
 151 }
 152
 153 static void host_entry_timeout(struct uloop_timeout *timeout)
 154 {
 155         struct relayd_host *host = container_of(timeout, struct relayd_host, timeout);
 156
 157         /*
 158          * When a host is behind a managed interface, we must not expire its host
 159          * entry prematurely, as this will cause routes to the node to expire,
 160          * leading to loss of connectivity from the other side.
 161          * When the timeout is reached, try pinging the host a few times before
 162          * giving up on it.
 163          */
 164         if (host->rif->managed && host->cleanup_pending < 2) {
 165                 send_arp_request(host);
 166                 host->cleanup_pending++;
 167                 uloop_timeout_set(&host->timeout, 1000);
 168                 return;
 169         }
 170         del_host(host);
 171 }
 172
 173 static struct relayd_host *add_host(struct relayd_interface *rif, const uint8_t *lladdr, const uint8_t *ipaddr)
 174 {
 175         struct relayd_host *host;
 176
 177         DPRINTF(1, "%s: adding host "IP_FMT" ("MAC_FMT")\n", rif->ifname,
 178                         IP_BUF(ipaddr), MAC_BUF(lladdr));
 179
 180         host = calloc(1, sizeof(*host));
 181         host->rif = rif;
 182         memcpy(host->ipaddr, ipaddr, sizeof(host->ipaddr));
 183         memcpy(host->lladdr, lladdr, sizeof(host->lladdr));
 184         list_add(&host->list, &rif->hosts);
 185         host->timeout.cb = host_entry_timeout;
 186         uloop_timeout_set(&host->timeout, host_timeout * 1000);
 187
 188         add_arp(host);
 189         if (rif->managed)
 190                 relayd_add_route(host);
 191
 192         return host;
 193 }
 194
 195 struct relayd_host *relayd_refresh_host(struct relayd_interface *rif, const uint8_t *lladdr, const uint8_t *ipaddr)
 196 {
 197         struct relayd_host *host;
 198
 199         host = find_host_by_ipaddr(rif, ipaddr);
 200         if (!host) {
 201                 host = find_host_by_ipaddr(NULL, ipaddr);
 202
 203                 /*
 204                  * When we suddenly see the host appearing on a different interface,
 205                  * reduce the timeout to make the old entry expire faster, in case the
 206                  * host has moved.
 207                  * If the old entry is behind a managed interface, it will be pinged
 208                  * before we expire it
 209                  */
 210                 if (host && !host->cleanup_pending)
 211                         uloop_timeout_set(&host->timeout, 1);
 212
 213                 host = add_host(rif, lladdr, ipaddr);
 214         } else {
 215                 host->cleanup_pending = false;
 216                 uloop_timeout_set(&host->timeout, host_timeout * 1000);
 217         }
 218
 219         return host;
 220 }
 221
 222 static void relay_arp_request(struct relayd_interface *from_rif, struct arp_packet *pkt)
 223 {
 224         struct relayd_interface *rif;
 225         struct arp_packet reqpkt;
 226
 227         memcpy(&reqpkt, pkt, sizeof(reqpkt));
 228         list_for_each_entry(rif, &interfaces, list) {
 229                 if (rif == from_rif)
 230                         continue;
 231
 232                 memcpy(reqpkt.eth.ether_shost, rif->sll.sll_addr, ETH_ALEN);
 233                 memcpy(reqpkt.arp.arp_sha, rif->sll.sll_addr, ETH_ALEN);
 234
 235                 DPRINTF(2, "%s: sending ARP who-has "IP_FMT", tell "IP_FMT" ("MAC_FMT")\n",
 236                         rif->ifname, IP_BUF(reqpkt.arp.arp_tpa),
 237                         IP_BUF(reqpkt.arp.arp_spa), MAC_BUF(reqpkt.eth.ether_shost));
 238
 239                 sendto(rif->fd.fd, &reqpkt, sizeof(reqpkt), 0,
 240                         (struct sockaddr *) &rif->sll, sizeof(rif->sll));
 241         }
 242 }
 243
 244 static void recv_arp_request(struct relayd_interface *rif, struct arp_packet *pkt)
 245 {
 246         struct relayd_host *host;
 247
 248         DPRINTF(2, "%s: ARP who-has "IP_FMT", tell "IP_FMT" ("MAC_FMT")\n",
 249                 rif->ifname,
 250                 IP_BUF(pkt->arp.arp_tpa),
 251                 IP_BUF(pkt->arp.arp_spa),
 252                 MAC_BUF(pkt->eth.ether_shost));
 253
 254         if (!memcmp(pkt->arp.arp_spa, "\x00\x00\x00\x00", 4))
 255                 return;
 256
 257         relayd_refresh_host(rif, pkt->eth.ether_shost, pkt->arp.arp_spa);
 258
 259         host = find_host_by_ipaddr(NULL, pkt->arp.arp_tpa);
 260
 261         /*
 262          * If a host is being pinged because of a timeout, do not use the cached
 263          * entry here. That way we can avoid giving out stale data in case the node
 264          * has moved. We shouldn't relay requests here either, as we might miss our
 265          * chance to create a host route.
 266          */
 267         if (host && host->cleanup_pending)
 268                 return;
 269
 270         relay_arp_request(rif, pkt);
 271 }
 272
 273
 274 static void recv_arp_reply(struct relayd_interface *rif, struct arp_packet *pkt)
 275 {
 276         struct relayd_host *host;
 277
 278         DPRINTF(2, "%s: received ARP reply for "IP_FMT" from "MAC_FMT", deliver to "IP_FMT"\n",
 279                 rif->ifname,
 280                 IP_BUF(pkt->arp.arp_spa),
 281                 MAC_BUF(pkt->eth.ether_shost),
 282                 IP_BUF(pkt->arp.arp_tpa));
 283
 284         relayd_refresh_host(rif, pkt->arp.arp_sha, pkt->arp.arp_spa);
 285
 286         if (!memcmp(pkt->arp.arp_tpa, rif->src_ip, 4))
 287                 return;
 288
 289         host = find_host_by_ipaddr(NULL, pkt->arp.arp_tpa);
 290         if (!host)
 291                 return;
 292
 293         if (host->rif == rif)
 294                 return;
 295
 296         send_arp_reply(host->rif, pkt->arp.arp_spa, host->lladdr, host->ipaddr);
 297 }
 298
 299 static void recv_packet(struct uloop_fd *fd, unsigned int events)
 300 {
 301         struct relayd_interface *rif = container_of(fd, struct relayd_interface, fd);
 302         struct arp_packet *pkt;
 303         static char pktbuf[4096];
 304         int pktlen;
 305
 306         do {
 307                 if (rif->fd.error)
 308                         uloop_end();
 309
 310                 pktlen = recv(rif->fd.fd, pktbuf, sizeof(pktbuf), 0);
 311                 if (pktlen < 0) {
 312                         if (errno == EINTR)
 313                                 continue;
 314
 315                         break;
 316                 }
 317
 318                 if (!pktlen)
 319                         break;
 320
 321                 pkt = (void *)pktbuf;
 322                 if (pkt->arp.arp_op == htons(ARPOP_REPLY))
 323                         recv_arp_reply(rif, pkt);
 324                 else if (pkt->arp.arp_op == htons(ARPOP_REQUEST))
 325                         recv_arp_request(rif, pkt);
 326                 else
 327                         DPRINTF(1, "received unknown packet type: %04x\n", ntohs(pkt->arp.arp_op));
 328
 329         } while (1);
 330 }
 331
 332 void relayd_forward_bcast_packet(struct relayd_interface *from_rif, void *packet, int len)
 333 {
 334         struct relayd_interface *rif;
 335         struct ether_header *eth = packet;
 336
 337         list_for_each_entry(rif, &interfaces, list) {
 338                 if (rif == from_rif)
 339                         continue;
 340
 341                 DPRINTF(3, "%s: forwarding broadcast packet to %s\n", from_rif->ifname, rif->ifname);
 342                 memcpy(eth->ether_shost, rif->sll.sll_addr, ETH_ALEN);
 343                 send(rif->bcast_fd.fd, packet, len, 0);
 344         }
 345 }
 346
 347 static void recv_bcast_packet(struct uloop_fd *fd, unsigned int events)
 348 {
 349         struct relayd_interface *rif = container_of(fd, struct relayd_interface, bcast_fd);
 350         static char pktbuf[4096];
 351         int pktlen;
 352
 353         do {
 354                 if (rif->fd.error)
 355                         uloop_end();
 356
 357                 pktlen = recv(rif->bcast_fd.fd, pktbuf, sizeof(pktbuf), 0);
 358                 if (pktlen < 0) {
 359                         if (errno == EINTR)
 360                                 continue;
 361
 362                         break;
 363                 }
 364
 365                 if (!pktlen)
 366                         break;
 367
 368                 if (!forward_bcast && !forward_dhcp)
 369                         continue;
 370
 371                 if (relayd_handle_dhcp_packet(rif, pktbuf, pktlen, forward_dhcp))
 372                         continue;
 373
 374                 if (forward_bcast)
 375                         relayd_forward_bcast_packet(rif, pktbuf, pktlen);
 376         } while (1);
 377 }
 378
 379
 380 static int init_interface(struct relayd_interface *rif)
 381 {
 382         struct sockaddr_ll *sll = &rif->sll;
 383         struct sockaddr_in *sin;
 384         struct ifreq ifr;
 385         int fd = rif->fd.fd;
 386 #ifdef PACKET_RECV_TYPE
 387         unsigned int pkt_type;
 388 #endif
 389
 390         fd = socket(AF_PACKET, SOCK_RAW, htons(ETH_P_ARP));
 391         if (fd < 0)
 392                 return -1;
 393
 394         rif->fd.fd = fd;
 395
 396         memset(&ifr, 0, sizeof(ifr));
 397         strcpy(ifr.ifr_name, rif->ifname);
 398
 399         if (ioctl(fd, SIOCGIFHWADDR, &ifr) < 0) {
 400                 perror("ioctl(SIOCGIFHWADDR)");
 401                 return -1;
 402         }
 403
 404         memcpy(sll->sll_addr, ifr.ifr_hwaddr.sa_data, ETH_ALEN);
 405         sll->sll_family = AF_PACKET;
 406         sll->sll_protocol = htons(ETH_P_ARP);
 407         sll->sll_pkttype = PACKET_BROADCAST;
 408         sll->sll_hatype = ARPHRD_ETHER;
 409         sll->sll_halen = ETH_ALEN;
 410
 411         if (ioctl(fd, SIOCGIFINDEX, &ifr) < 0) {
 412                 perror("ioctl(SIOCGIFINDEX)");
 413                 return -1;
 414         }
 415
 416         sll->sll_ifindex = ifr.ifr_ifindex;
 417
 418         if (ioctl(fd, SIOCGIFADDR, &ifr) < 0) {
 419                 memcpy(rif->src_ip, DUMMY_IP, sizeof(rif->src_ip));
 420         } else {
 421                 sin = (struct sockaddr_in *) &ifr.ifr_addr;
 422                 memcpy(rif->src_ip, &sin->sin_addr.s_addr, sizeof(rif->src_ip));
 423         }
 424
 425         if (bind(fd, (struct sockaddr *)sll, sizeof(struct sockaddr_ll)) < 0) {
 426                 perror("bind(ETH_P_ARP)");
 427                 return -1;
 428         }
 429
 430         rif->fd.cb = recv_packet;
 431         uloop_fd_add(&rif->fd, ULOOP_READ | ULOOP_EDGE_TRIGGER);
 432
 433         if (!forward_bcast && !forward_dhcp)
 434                 return 0;
 435
 436         fd = socket(AF_PACKET, SOCK_RAW, htons(ETH_P_IP));
 437         if (fd < 0)
 438                 return 0;
 439
 440         rif->bcast_fd.fd = fd;
 441         rif->bcast_fd.cb = recv_bcast_packet;
 442
 443         memcpy(&rif->bcast_sll, &rif->sll, sizeof(rif->bcast_sll));
 444         sll = &rif->bcast_sll;
 445         sll->sll_protocol = htons(ETH_P_IP);
 446
 447         if (bind(fd, (struct sockaddr *)sll, sizeof(struct sockaddr_ll)) < 0) {
 448                 perror("bind(ETH_P_IP)");
 449                 return 0;
 450         }
 451
 452 #ifdef PACKET_RECV_TYPE
 453         pkt_type = (1 << PACKET_BROADCAST);
 454         setsockopt(fd, SOL_PACKET, PACKET_RECV_TYPE, &pkt_type, sizeof(pkt_type));
 455 #endif
 456
 457         uloop_fd_add(&rif->bcast_fd, ULOOP_READ | ULOOP_EDGE_TRIGGER);
 458         relayd_add_interface_routes(rif);
 459         return 0;
 460 }
 461
 462 static int init_interfaces(void)
 463 {
 464         struct relayd_interface *rif;
 465         int ret;
 466
 467         list_for_each_entry(rif, &interfaces, list) {
 468                 ret = init_interface(rif);
 469                 if (ret < 0)
 470                         return ret;
 471         }
 472
 473         return 0;
 474 }
 475
 476 static void cleanup_hosts(void)
 477 {
 478         struct relayd_interface *rif;
 479         struct relayd_host *host, *tmp;
 480
 481         list_for_each_entry(rif, &interfaces, list) {
 482                 list_for_each_entry_safe(host, tmp, &rif->hosts, list) {
 483                         del_host(host);
 484                 }
 485         }
 486 }
 487
 488 static void free_interfaces(void)
 489 {
 490         struct relayd_interface *rif, *rtmp;
 491
 492         list_for_each_entry_safe(rif, rtmp, &interfaces, list) {
 493                 relayd_del_interface_routes(rif);
 494                 list_del(&rif->list);
 495                 free(rif);
 496         }
 497 }
 498
 499 static int alloc_interface(const char *ifname, bool managed)
 500 {
 501         struct relayd_interface *rif;
 502
 503         if (strlen(ifname) >= IFNAMSIZ)
 504                 return -1;
 505
 506         rif = calloc(1, sizeof(*rif));
 507         if (!rif)
 508                 return -1;
 509
 510         INIT_LIST_HEAD(&rif->list);
 511         INIT_LIST_HEAD(&rif->hosts);
 512         strcpy(rif->ifname, ifname);
 513         list_add(&rif->list, &interfaces);
 514         rif->managed = managed;
 515
 516         return 0;
 517 }
 518
 519 static void die(int signo)
 520 {
 521         /*
 522          * When we hit SIGTERM, clean up interfaces directly, so that we
 523          * won't leave our routing in an invalid state.
 524          */
 525         cleanup_hosts();
 526         free_interfaces();
 527         exit(1);
 528 }
 529
 530 static int usage(const char *progname)
 531 {
 532         fprintf(stderr, "Usage: %s <options>\n"
 533                         "\n"
 534                         "Options:\n"
 535                         "       -d              Enable debug messages\n"
 536                         "       -i <ifname>     Add an interface for relaying\n"
 537                         "       -I <ifname>     Same as -i, except with ARP cache and host route management\n"
 538                         "                       You need to specify at least two interfaces\n"
 539                         "       -t <timeout>    Host entry expiry timeout\n"
 540                         "       -T <table>      Set routing table number for automatically added routes\n"
 541                         "       -B              Enable broadcast forwarding\n"
 542                         "       -D              Enable DHCP forwarding\n"
 543                         "\n",
 544                 progname);
 545         return -1;
 546 }
 547
 548 int main(int argc, char **argv)
 549 {
 550         bool managed;
 551         int ifnum = 0;
 552         int ch;
 553
 554         debug = 0;
 555         inet_sock = socket(AF_INET, SOCK_DGRAM, 0);
 556         if (inet_sock < 0) {
 557                 perror("socket(AF_INET)");
 558                 return 1;
 559         }
 560
 561         host_timeout = 60;
 562         forward_bcast = 0;
 563         uloop_init();
 564
 565         while ((ch = getopt(argc, argv, "I:i:t:BDdT:")) != -1) {
 566                 switch(ch) {
 567                 case 'I':
 568                         managed = true;
 569                         /* fall through */
 570                 case 'i':
 571                         ifnum++;
 572                         if (alloc_interface(optarg, managed) < 0)
 573                                 return 1;
 574
 575                         managed = false;
 576                         break;
 577                 case 't':
 578                         host_timeout = atoi(optarg);
 579                         if (host_timeout <= 0)
 580                                 return usage(argv[0]);
 581                         break;
 582                 case 'd':
 583                         debug++;
 584                         break;
 585                 case 'B':
 586                         forward_bcast = 1;
 587                         break;
 588                 case 'D':
 589                         forward_dhcp = 1;
 590                         break;
 591                 case 'T':
 592                         route_table = atoi(optarg);
 593                         if (route_table <= 0)
 594                                 return usage(argv[0]);
 595                         break;
 596                 case '?':
 597                 default:
 598                         return usage(argv[0]);
 599                 }
 600         }
 601
 602         if (list_empty(&interfaces))
 603                 return usage(argv[0]);
 604
 605         if (ifnum < 2) {
 606                 fprintf(stderr, "ERROR: Need at least 2 interfaces for relaying\n");
 607                 return -1;
 608         }
 609
 610         argc -= optind;
 611         argv += optind;
 612
 613         signal(SIGTERM, die);
 614         signal(SIGHUP, die);
 615         signal(SIGUSR1, die);
 616         signal(SIGUSR2, die);
 617
 618         if (relayd_rtnl_init() < 0)
 619                 return 1;
 620
 621         if (init_interfaces() < 0)
 622                 return 1;
 623
 624         uloop_run();
 625         uloop_done();
 626
 627         cleanup_hosts();
 628         free_interfaces();
 629         relayd_rtnl_done();
 630         close(inet_sock);
 631
 632         return 0;
 633 }