src/router.c

   1 /**
   2  * Copyright (C) 2012-2013 Steven Barth <steven@midlink.org>
   3  * Copyright (C) 2018 Hans Dedecker <dedeckeh@gmail.com>
   4  *
   5  * This program is free software; you can redistribute it and/or modify
   6  * it under the terms of the GNU General Public License v2 as published by
   7  * the Free Software Foundation.
   8  *
   9  * This program is distributed in the hope that it will be useful,
  10  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  11  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  12  * GNU General Public License for more details.
  13  *
  14  */
  15
  16 #include <errno.h>
  17 #include <fcntl.h>
  18 #include <signal.h>
  19 #include <resolv.h>
  20 #include <stdio.h>
  21 #include <stdlib.h>
  22 #include <unistd.h>
  23 #include <stdbool.h>
  24 #include <arpa/inet.h>
  25 #include <net/route.h>
  26
  27 #include <libubox/utils.h>
  28
  29 #include "router.h"
  30 #include "odhcpd.h"
  31
  32
  33 static void forward_router_solicitation(const struct interface *iface);
  34 static void forward_router_advertisement(const struct interface *iface, uint8_t *data, size_t len);
  35
  36 static void handle_icmpv6(void *addr, void *data, size_t len,
  37                 struct interface *iface, void *dest);
  38 static void trigger_router_advert(struct uloop_timeout *event);
  39 static void router_netevent_cb(unsigned long event, struct netevent_handler_info *info);
  40
  41 static struct netevent_handler router_netevent_handler = { .cb = router_netevent_cb, };
  42
  43 static FILE *fp_route = NULL;
  44
  45
  46 #define TIME_LEFT(t1, now) ((t1) != UINT32_MAX ? (t1) - (now) : UINT32_MAX)
  47
  48 int router_init(void)
  49 {
  50         int ret = 0;
  51
  52         if (!(fp_route = fopen("/proc/net/ipv6_route", "r"))) {
  53                 syslog(LOG_ERR, "fopen(/proc/net/ipv6_route): %m");
  54                 ret = -1;
  55                 goto out;
  56         }
  57
  58         if (netlink_add_netevent_handler(&router_netevent_handler) < 0) {
  59                 syslog(LOG_ERR, "Failed to add netevent handler");
  60                 ret = -1;
  61         }
  62
  63 out:
  64         if (ret < 0 && fp_route) {
  65                 fclose(fp_route);
  66                 fp_route = NULL;
  67         }
  68
  69         return ret;
  70 }
  71
  72
  73 int router_setup_interface(struct interface *iface, bool enable)
  74 {
  75         int ret = 0;
  76
  77         enable = enable && (iface->ra != MODE_DISABLED);
  78
  79         if (!fp_route) {
  80                 ret = -1;
  81                 goto out;
  82         }
  83
  84
  85         if (!enable && iface->router_event.uloop.fd >= 0) {
  86                 if (!iface->master) {
  87                         uloop_timeout_cancel(&iface->timer_rs);
  88                         iface->timer_rs.cb = NULL;
  89
  90                         trigger_router_advert(&iface->timer_rs);
  91                 }
  92
  93                 uloop_fd_delete(&iface->router_event.uloop);
  94                 close(iface->router_event.uloop.fd);
  95                 iface->router_event.uloop.fd = -1;
  96         } else if (enable) {
  97                 struct icmp6_filter filt;
  98                 struct ipv6_mreq mreq;
  99                 int val = 2;
 100
 101                 if (iface->router_event.uloop.fd < 0) {
 102                         /* Open ICMPv6 socket */
 103                         iface->router_event.uloop.fd = socket(AF_INET6, SOCK_RAW | SOCK_CLOEXEC,
 104                                                               IPPROTO_ICMPV6);
 105                         if (iface->router_event.uloop.fd < 0) {
 106                                 syslog(LOG_ERR, "socket(AF_INET6): %m");
 107                                 ret = -1;
 108                                 goto out;
 109                         }
 110
 111                         if (setsockopt(iface->router_event.uloop.fd, SOL_SOCKET, SO_BINDTODEVICE,
 112                                        iface->ifname, strlen(iface->ifname)) < 0) {
 113                                 syslog(LOG_ERR, "setsockopt(SO_BINDTODEVICE): %m");
 114                                 ret = -1;
 115                                 goto out;
 116                         }
 117
 118                         /* Let the kernel compute our checksums */
 119                         if (setsockopt(iface->router_event.uloop.fd, IPPROTO_RAW, IPV6_CHECKSUM,
 120                                        &val, sizeof(val)) < 0) {
 121                                 syslog(LOG_ERR, "setsockopt(IPV6_CHECKSUM): %m");
 122                                 ret = -1;
 123                                 goto out;
 124                         }
 125
 126                         /* This is required by RFC 4861 */
 127                         val = 255;
 128                         if (setsockopt(iface->router_event.uloop.fd, IPPROTO_IPV6, IPV6_MULTICAST_HOPS,
 129                                        &val, sizeof(val)) < 0) {
 130                                 syslog(LOG_ERR, "setsockopt(IPV6_MULTICAST_HOPS): %m");
 131                                 ret = -1;
 132                                 goto out;
 133                         }
 134
 135                         if (setsockopt(iface->router_event.uloop.fd, IPPROTO_IPV6, IPV6_UNICAST_HOPS,
 136                                        &val, sizeof(val)) < 0) {
 137                                 syslog(LOG_ERR, "setsockopt(IPV6_UNICAST_HOPS): %m");
 138                                 ret = -1;
 139                                 goto out;
 140                         }
 141
 142                         /* We need to know the source interface */
 143                         val = 1;
 144                         if (setsockopt(iface->router_event.uloop.fd, IPPROTO_IPV6, IPV6_RECVPKTINFO,
 145                                        &val, sizeof(val)) < 0) {
 146                                 syslog(LOG_ERR, "setsockopt(IPV6_RECVPKTINFO): %m");
 147                                 ret = -1;
 148                                 goto out;
 149                         }
 150
 151                         if (setsockopt(iface->router_event.uloop.fd, IPPROTO_IPV6, IPV6_RECVHOPLIMIT,
 152                                        &val, sizeof(val)) < 0) {
 153                                 syslog(LOG_ERR, "setsockopt(IPV6_RECVHOPLIMIT): %m");
 154                                 ret = -1;
 155                                 goto out;
 156                         }
 157
 158                         /* Don't loop back */
 159                         val = 0;
 160                         if (setsockopt(iface->router_event.uloop.fd, IPPROTO_IPV6, IPV6_MULTICAST_LOOP,
 161                                        &val, sizeof(val)) < 0) {
 162                                 syslog(LOG_ERR, "setsockopt(IPV6_MULTICAST_LOOP): %m");
 163                                 ret = -1;
 164                                 goto out;
 165                         }
 166
 167                         /* Filter ICMPv6 package types */
 168                         ICMP6_FILTER_SETBLOCKALL(&filt);
 169                         ICMP6_FILTER_SETPASS(ND_ROUTER_ADVERT, &filt);
 170                         ICMP6_FILTER_SETPASS(ND_ROUTER_SOLICIT, &filt);
 171                         if (setsockopt(iface->router_event.uloop.fd, IPPROTO_ICMPV6, ICMP6_FILTER,
 172                                        &filt, sizeof(filt)) < 0) {
 173                                 syslog(LOG_ERR, "setsockopt(ICMP6_FILTER): %m");
 174                                 ret = -1;
 175                                 goto out;
 176                         }
 177
 178                         iface->router_event.handle_dgram = handle_icmpv6;
 179                         odhcpd_register(&iface->router_event);
 180                 } else {
 181                         uloop_timeout_cancel(&iface->timer_rs);
 182                         iface->timer_rs.cb = NULL;
 183
 184                         memset(&mreq, 0, sizeof(mreq));
 185                         mreq.ipv6mr_interface = iface->ifindex;
 186                         inet_pton(AF_INET6, ALL_IPV6_NODES, &mreq.ipv6mr_multiaddr);
 187                         setsockopt(iface->router_event.uloop.fd, IPPROTO_IPV6, IPV6_DROP_MEMBERSHIP,
 188                                    &mreq, sizeof(mreq));
 189
 190                         inet_pton(AF_INET6, ALL_IPV6_ROUTERS, &mreq.ipv6mr_multiaddr);
 191                         setsockopt(iface->router_event.uloop.fd, IPPROTO_IPV6, IPV6_DROP_MEMBERSHIP,
 192                                    &mreq, sizeof(mreq));
 193                 }
 194
 195                 memset(&mreq, 0, sizeof(mreq));
 196                 mreq.ipv6mr_interface = iface->ifindex;
 197                 inet_pton(AF_INET6, ALL_IPV6_ROUTERS, &mreq.ipv6mr_multiaddr);
 198
 199                 if (iface->ra == MODE_RELAY && iface->master) {
 200                         inet_pton(AF_INET6, ALL_IPV6_NODES, &mreq.ipv6mr_multiaddr);
 201                         forward_router_solicitation(iface);
 202                 } else if (iface->ra == MODE_SERVER) {
 203                         iface->timer_rs.cb = trigger_router_advert;
 204                         uloop_timeout_set(&iface->timer_rs, 1000);
 205                 }
 206
 207                 if (setsockopt(iface->router_event.uloop.fd, IPPROTO_IPV6,
 208                                IPV6_ADD_MEMBERSHIP, &mreq, sizeof(mreq)) < 0) {
 209                         ret = -1;
 210                         syslog(LOG_ERR, "setsockopt(IPV6_ADD_MEMBERSHIP): %m");
 211                         goto out;
 212                 }
 213         }
 214 out:
 215         if (ret < 0 && iface->router_event.uloop.fd >= 0) {
 216                 close(iface->router_event.uloop.fd);
 217                 iface->router_event.uloop.fd = -1;
 218         }
 219
 220         return ret;
 221 }
 222
 223
 224 static void router_netevent_cb(unsigned long event, struct netevent_handler_info *info)
 225 {
 226         struct interface *iface;
 227
 228         switch (event) {
 229         case NETEV_ROUTE6_ADD:
 230         case NETEV_ROUTE6_DEL:
 231                 if (info->rt.dst_len)
 232                         break;
 233
 234                 avl_for_each_element(&interfaces, iface, avl) {
 235                         if (iface->ra == MODE_SERVER && !iface->master)
 236                                 uloop_timeout_set(&iface->timer_rs, 1000);
 237                 }
 238                 break;
 239         case NETEV_ADDR6LIST_CHANGE:
 240                 iface = info->iface;
 241                 if (iface && iface->ra == MODE_SERVER && !iface->master)
 242                         uloop_timeout_set(&iface->timer_rs, 1000);
 243                 break;
 244         default:
 245                 break;
 246         }
 247 }
 248
 249
 250 static bool router_icmpv6_valid(struct sockaddr_in6 *source, uint8_t *data, size_t len)
 251 {
 252         struct icmp6_hdr *hdr = (struct icmp6_hdr *)data;
 253         struct icmpv6_opt *opt, *end = (struct icmpv6_opt*)&data[len];
 254
 255         /* Hoplimit is already checked in odhcpd_receive_packets */
 256         if (len < sizeof(*hdr) || hdr->icmp6_code)
 257                 return false;
 258
 259         switch (hdr->icmp6_type) {
 260         case ND_ROUTER_ADVERT:
 261                 if (!IN6_IS_ADDR_LINKLOCAL(&source->sin6_addr))
 262                         return false;
 263
 264                 opt = (struct icmpv6_opt *)((struct nd_router_advert *)data + 1);
 265                 break;
 266
 267         case ND_ROUTER_SOLICIT:
 268                 opt = (struct icmpv6_opt *)((struct nd_router_solicit *)data + 1);
 269                 break;
 270
 271         default:
 272                 return false;
 273         }
 274
 275         icmpv6_for_each_option(opt, opt, end)
 276                 if (opt->type == ND_OPT_SOURCE_LINKADDR &&
 277                                 IN6_IS_ADDR_UNSPECIFIED(&source->sin6_addr) &&
 278                                 hdr->icmp6_type == ND_ROUTER_SOLICIT)
 279                         return false;
 280
 281         /* Check all options parsed successfully */
 282         return opt == end;
 283 }
 284
 285
 286 /* Detect whether a default route exists, also find the source prefixes */
 287 static bool parse_routes(struct odhcpd_ipaddr *n, ssize_t len)
 288 {
 289         struct odhcpd_ipaddr p = { .addr.in6 = IN6ADDR_ANY_INIT, .prefix = 0,
 290                                         .dprefix = 0, .preferred = 0, .valid = 0};
 291         bool found_default = false;
 292         char line[512], ifname[16];
 293
 294         rewind(fp_route);
 295
 296         while (fgets(line, sizeof(line), fp_route)) {
 297                 uint32_t rflags;
 298                 if (sscanf(line, "00000000000000000000000000000000 00 "
 299                                 "%*s %*s %*s %*s %*s %*s %*s %15s", ifname) &&
 300                                 strcmp(ifname, "lo")) {
 301                         found_default = true;
 302                 } else if (sscanf(line, "%8" SCNx32 "%8" SCNx32 "%*8" SCNx32 "%*8" SCNx32 " %hhx %*s "
 303                                 "%*s 00000000000000000000000000000000 %*s %*s %*s %" SCNx32 " lo",
 304                                 &p.addr.in6.s6_addr32[0], &p.addr.in6.s6_addr32[1], &p.prefix, &rflags) &&
 305                                 p.prefix > 0 && (rflags & RTF_NONEXTHOP) && (rflags & RTF_REJECT)) {
 306                         // Find source prefixes by scanning through unreachable-routes
 307                         p.addr.in6.s6_addr32[0] = htonl(p.addr.in6.s6_addr32[0]);
 308                         p.addr.in6.s6_addr32[1] = htonl(p.addr.in6.s6_addr32[1]);
 309
 310                         for (ssize_t i = 0; i < len; ++i) {
 311                                 if (n[i].prefix <= 64 && n[i].prefix >= p.prefix &&
 312                                                 !odhcpd_bmemcmp(&p.addr.in6, &n[i].addr.in6, p.prefix)) {
 313                                         n[i].dprefix = p.prefix;
 314                                         break;
 315                                 }
 316                         }
 317                 }
 318         }
 319
 320         return found_default;
 321 }
 322
 323 static int calc_adv_interval(struct interface *iface, uint32_t minvalid,
 324                              uint32_t *maxival)
 325 {
 326         uint32_t minival = iface->ra_mininterval;
 327         int msecs;
 328
 329         *maxival = iface->ra_maxinterval;
 330
 331         if (*maxival > minvalid/3)
 332                 *maxival = minvalid/3;
 333
 334         if (*maxival > MaxRtrAdvInterval)
 335                 *maxival = MaxRtrAdvInterval;
 336         else if (*maxival < 4)
 337                 *maxival = 4;
 338
 339         if (minival < MinRtrAdvInterval)
 340                 minival = MinRtrAdvInterval;
 341         else if (minival > (*maxival * 3)/4)
 342                 minival = (*maxival >= 9 ? *maxival/3 : *maxival);
 343
 344         odhcpd_urandom(&msecs, sizeof(msecs));
 345         msecs = (labs(msecs) % ((*maxival != minival) ? (*maxival - minival)*1000 : 500)) +
 346                         minival*1000;
 347
 348         return msecs;
 349 }
 350
 351 static uint32_t calc_ra_lifetime(struct interface *iface, uint32_t maxival)
 352 {
 353         uint32_t lifetime = 3*maxival;
 354
 355         if (iface->ra_lifetime >= 0) {
 356                 lifetime = iface->ra_lifetime;
 357                 if (lifetime < maxival)
 358                         lifetime = maxival;
 359                 else if (lifetime > 9000)
 360                         lifetime = 9000;
 361         }
 362
 363         return lifetime;
 364 }
 365
 366 enum {
 367         IOV_RA_ADV=0,
 368         IOV_RA_PFXS,
 369         IOV_RA_ROUTES,
 370         IOV_RA_DNS,
 371         IOV_RA_SEARCH,
 372         IOV_RA_ADV_INTERVAL,
 373         IOV_RA_TOTAL,
 374 };
 375
 376 struct adv_msg {
 377         struct nd_router_advert h;
 378         struct icmpv6_opt lladdr;
 379         struct nd_opt_mtu mtu;
 380 };
 381
 382 struct nd_opt_dns_server {
 383         uint8_t type;
 384         uint8_t len;
 385         uint8_t pad;
 386         uint8_t pad2;
 387         uint32_t lifetime;
 388         struct in6_addr addr[];
 389 };
 390
 391 struct nd_opt_search_list {
 392         uint8_t type;
 393         uint8_t len;
 394         uint8_t pad;
 395         uint8_t pad2;
 396         uint32_t lifetime;
 397         uint8_t name[];
 398 };
 399
 400 struct nd_opt_route_info {
 401         uint8_t type;
 402         uint8_t len;
 403         uint8_t prefix;
 404         uint8_t flags;
 405         uint32_t lifetime;
 406         uint32_t addr[4];
 407 };
 408
 409 /* Router Advert server mode */
 410 static int send_router_advert(struct interface *iface, const struct in6_addr *from)
 411 {
 412         time_t now = odhcpd_time();
 413         struct odhcpd_ipaddr *addrs = NULL;
 414         struct adv_msg adv;
 415         struct nd_opt_prefix_info *pfxs = NULL;
 416         struct nd_opt_dns_server *dns = NULL;
 417         struct nd_opt_search_list *search = NULL;
 418         struct nd_opt_route_info *routes = NULL;
 419         struct nd_opt_adv_interval adv_interval;
 420         struct iovec iov[IOV_RA_TOTAL];
 421         struct sockaddr_in6 dest;
 422         size_t dns_sz = 0, search_sz = 0, pfxs_cnt = 0, routes_cnt = 0;
 423         ssize_t addr_cnt = 0;
 424         uint32_t minvalid = UINT32_MAX, maxival, lifetime;
 425         int msecs, mtu = iface->ra_mtu, hlim = iface->ra_hoplimit;
 426         bool default_route = false;
 427         bool valid_prefix = false;
 428         char buf[INET6_ADDRSTRLEN];
 429
 430         memset(&adv, 0, sizeof(adv));
 431         adv.h.nd_ra_type = ND_ROUTER_ADVERT;
 432
 433         if (hlim == 0)
 434                 hlim = odhcpd_get_interface_config(iface->ifname, "hop_limit");
 435
 436         if (hlim > 0)
 437                 adv.h.nd_ra_curhoplimit = hlim;
 438
 439         if (iface->dhcpv6 != MODE_DISABLED) {
 440                 adv.h.nd_ra_flags_reserved = ND_RA_FLAG_OTHER;
 441
 442                 if (iface->ra_managed >= RA_MANAGED_MFLAG)
 443                         adv.h.nd_ra_flags_reserved |= ND_RA_FLAG_MANAGED;
 444         }
 445
 446         if (iface->route_preference < 0)
 447                 adv.h.nd_ra_flags_reserved |= ND_RA_PREF_LOW;
 448         else if (iface->route_preference > 0)
 449                 adv.h.nd_ra_flags_reserved |= ND_RA_PREF_HIGH;
 450
 451         adv.h.nd_ra_reachable = htonl(iface->ra_reachabletime);
 452         adv.h.nd_ra_retransmit = htonl(iface->ra_retranstime);
 453
 454         adv.lladdr.type = ND_OPT_SOURCE_LINKADDR;
 455         adv.lladdr.len = 1;
 456         odhcpd_get_mac(iface, adv.lladdr.data);
 457
 458         adv.mtu.nd_opt_mtu_type = ND_OPT_MTU;
 459         adv.mtu.nd_opt_mtu_len = 1;
 460
 461         if (mtu == 0)
 462                 mtu = odhcpd_get_interface_config(iface->ifname, "mtu");
 463
 464         if (mtu < 1280)
 465                 mtu = 1280;
 466
 467         adv.mtu.nd_opt_mtu_mtu = htonl(mtu);
 468
 469         iov[IOV_RA_ADV].iov_base = (char *)&adv;
 470         iov[IOV_RA_ADV].iov_len = sizeof(adv);
 471
 472         /* If not shutdown */
 473         if (iface->timer_rs.cb) {
 474                 size_t size = sizeof(*addrs) * iface->addr6_len;
 475
 476                 addrs = alloca(size);
 477                 memcpy(addrs, iface->addr6, size);
 478
 479                 addr_cnt = iface->addr6_len;
 480
 481                 /* Check default route */
 482                 if (iface->default_router) {
 483                         default_route = true;
 484
 485                         if (iface->default_router > 1)
 486                                 valid_prefix = true;
 487                 } else if (parse_routes(addrs, addr_cnt))
 488                         default_route = true;
 489         }
 490
 491         /* Construct Prefix Information options */
 492         for (ssize_t i = 0; i < addr_cnt; ++i) {
 493                 struct odhcpd_ipaddr *addr = &addrs[i];
 494                 struct nd_opt_prefix_info *p = NULL;
 495                 uint32_t preferred = 0;
 496                 uint32_t valid = 0;
 497
 498                 if (addr->prefix > 96 || addr->valid <= (uint32_t)now) {
 499                         syslog(LOG_INFO, "Address %s (prefix %d, valid %u) not suitable as RA prefix on %s",
 500                                 inet_ntop(AF_INET6, &addr->addr.in6, buf, sizeof(buf)), addr->prefix,
 501                                 addr->valid, iface->name);
 502                         continue;
 503                 }
 504
 505                 if (odhcpd_bmemcmp(&addr->addr, &iface->pio_filter_addr,
 506                                    iface->pio_filter_length) != 0 ||
 507                     addr->prefix < iface->pio_filter_length) {
 508                         syslog(LOG_INFO, "Address %s filtered out as RA prefix on %s",
 509                                inet_ntop(AF_INET6, &addr->addr.in6, buf, sizeof(buf)),
 510                                iface->name);
 511                         continue; /* PIO filtered out of this RA */
 512                 }
 513
 514                 for (size_t i = 0; i < pfxs_cnt; ++i) {
 515                         if (addr->prefix == pfxs[i].nd_opt_pi_prefix_len &&
 516                                         !odhcpd_bmemcmp(&pfxs[i].nd_opt_pi_prefix,
 517                                         &addr->addr.in6, addr->prefix))
 518                                 p = &pfxs[i];
 519                 }
 520
 521                 if (!p) {
 522                         struct nd_opt_prefix_info *tmp;
 523
 524                         tmp = realloc(pfxs, sizeof(*pfxs) * (pfxs_cnt + 1));
 525                         if (!tmp) {
 526                                 syslog(LOG_ERR, "Realloc failed for RA prefix option on %s", iface->name);
 527                                 continue;
 528                         }
 529
 530                         pfxs = tmp;
 531                         p = &pfxs[pfxs_cnt++];
 532                         memset(p, 0, sizeof(*p));
 533                 }
 534
 535                 if (addr->preferred > (uint32_t)now) {
 536                         preferred = TIME_LEFT(addr->preferred, now);
 537
 538                         if (iface->ra_useleasetime &&
 539                                         preferred > iface->dhcpv4_leasetime)
 540                                 preferred = iface->dhcpv4_leasetime;
 541                 }
 542
 543                 valid = TIME_LEFT(addr->valid, now);
 544                 if (iface->ra_useleasetime && valid > iface->dhcpv4_leasetime)
 545                         valid = iface->dhcpv4_leasetime;
 546
 547                 if (minvalid > valid)
 548                         minvalid = valid;
 549
 550                 if (!IN6_IS_ADDR_ULA(&addr->addr.in6) || iface->default_router)
 551                         valid_prefix = true;
 552
 553                 odhcpd_bmemcpy(&p->nd_opt_pi_prefix, &addr->addr.in6,
 554                                 (iface->ra_advrouter) ? 128 : addr->prefix);
 555                 p->nd_opt_pi_type = ND_OPT_PREFIX_INFORMATION;
 556                 p->nd_opt_pi_len = 4;
 557                 p->nd_opt_pi_prefix_len = (addr->prefix < 64) ? 64 : addr->prefix;
 558                 p->nd_opt_pi_flags_reserved = 0;
 559                 if (!iface->ra_not_onlink)
 560                         p->nd_opt_pi_flags_reserved |= ND_OPT_PI_FLAG_ONLINK;
 561                 if (iface->ra_managed < RA_MANAGED_NO_AFLAG && addr->prefix <= 64)
 562                         p->nd_opt_pi_flags_reserved |= ND_OPT_PI_FLAG_AUTO;
 563                 if (iface->ra_advrouter)
 564                         p->nd_opt_pi_flags_reserved |= ND_OPT_PI_FLAG_RADDR;
 565                 p->nd_opt_pi_preferred_time = htonl(preferred);
 566                 p->nd_opt_pi_valid_time = htonl(valid);
 567         }
 568
 569         iov[IOV_RA_PFXS].iov_base = (char *)pfxs;
 570         iov[IOV_RA_PFXS].iov_len = pfxs_cnt * sizeof(*pfxs);
 571
 572         /* Calculate periodic transmit */
 573         msecs = calc_adv_interval(iface, minvalid, &maxival);
 574         lifetime = calc_ra_lifetime(iface, maxival);
 575
 576         if (default_route) {
 577                 if (!valid_prefix) {
 578                         syslog(LOG_WARNING, "A default route is present but there is no public prefix "
 579                                         "on %s thus we don't announce a default route!", iface->name);
 580                         adv.h.nd_ra_router_lifetime = 0;
 581                 } else
 582                         adv.h.nd_ra_router_lifetime = htons(lifetime < UINT16_MAX ? lifetime : UINT16_MAX);
 583
 584         } else
 585                 adv.h.nd_ra_router_lifetime = 0;
 586
 587         syslog(LOG_INFO, "Using a RA lifetime of %d seconds on %s", ntohs(adv.h.nd_ra_router_lifetime), iface->name);
 588
 589         /* DNS options */
 590         if (iface->ra_dns) {
 591                 struct in6_addr dns_pref, *dns_addr = NULL;
 592                 size_t dns_cnt = 0, search_len = iface->search_len;
 593                 uint8_t *search_domain = iface->search;
 594
 595                 /* DNS Recursive DNS */
 596                 if (iface->dns_cnt > 0) {
 597                         dns_addr = iface->dns;
 598                         dns_cnt = iface->dns_cnt;
 599                 } else if (!odhcpd_get_interface_dns_addr(iface, &dns_pref)) {
 600                         dns_addr = &dns_pref;
 601                         dns_cnt = 1;
 602                 }
 603
 604                 if (dns_cnt) {
 605                         dns_sz = sizeof(*dns) + sizeof(struct in6_addr)*dns_cnt;
 606
 607                         dns = alloca(dns_sz);
 608                         memset(dns, 0, dns_sz);
 609                         dns->type = ND_OPT_RECURSIVE_DNS;
 610                         dns->len = 1 + (2 * dns_cnt);
 611                         dns->lifetime = htonl(lifetime);
 612                         memcpy(dns->addr, dns_addr, sizeof(struct in6_addr)*dns_cnt);
 613                 }
 614
 615                 /* DNS Search options */
 616                 if (!search_domain && !res_init() && _res.dnsrch[0] && _res.dnsrch[0][0]) {
 617                         uint8_t search_buf[256];
 618
 619                         int len = dn_comp(_res.dnsrch[0], search_buf,
 620                                         sizeof(search_buf), NULL, NULL);
 621                         if (len > 0) {
 622                                 search_domain = search_buf;
 623                                 search_len = len;
 624                         }
 625                 }
 626
 627                 if (search_len > 0) {
 628                         size_t search_padded = ((search_len + 7) & (~7)) + 8;
 629
 630                         search_sz = sizeof(*search) + search_padded;
 631
 632                         search = alloca(search_sz);
 633                         memset(search, 0, search_sz);
 634                         search->type = ND_OPT_DNS_SEARCH;
 635                         search->len = search_len ? ((sizeof(*search) + search_padded) / 8) : 0;
 636                         search->lifetime = htonl(lifetime);
 637                         memcpy(search->name, search_domain, search_len);
 638                         memset(&search->name[search_len], 0, search_padded - search_len);
 639                 }
 640         }
 641
 642         iov[IOV_RA_DNS].iov_base = (char *)dns;
 643         iov[IOV_RA_DNS].iov_len = dns_sz;
 644         iov[IOV_RA_SEARCH].iov_base = (char *)search;
 645         iov[IOV_RA_SEARCH].iov_len = search_sz;
 646
 647         for (ssize_t i = 0; i < addr_cnt; ++i) {
 648                 struct odhcpd_ipaddr *addr = &addrs[i];
 649                 struct nd_opt_route_info *tmp;
 650                 uint32_t valid;
 651
 652                 if (addr->dprefix > 64 || addr->dprefix == 0 || addr->valid <= (uint32_t)now) {
 653                         syslog(LOG_INFO, "Address %s (dprefix %d, valid %u) not suitable as RA route on %s",
 654                                 inet_ntop(AF_INET6, &addr->addr.in6, buf, sizeof(buf)),
 655                                 addr->dprefix, addr->valid, iface->name);
 656
 657                         continue; /* Address not suitable */
 658                 }
 659
 660                 if (odhcpd_bmemcmp(&addr->addr, &iface->pio_filter_addr,
 661                                 iface->pio_filter_length) != 0 ||
 662                                 addr->prefix < iface->pio_filter_length) {
 663                         syslog(LOG_INFO, "Address %s filtered out as RA route on %s",
 664                                inet_ntop(AF_INET6, &addr->addr.in6, buf, sizeof(buf)),
 665                                iface->name);
 666                         continue; /* PIO filtered out of this RA */
 667                 }
 668
 669                 if (addr->dprefix > 32) {
 670                         addr->addr.in6.s6_addr32[1] &= htonl(~((1U << (64 - addr->dprefix)) - 1));
 671                 } else if (addr->dprefix <= 32) {
 672                         addr->addr.in6.s6_addr32[0] &= htonl(~((1U << (32 - addr->dprefix)) - 1));
 673                         addr->addr.in6.s6_addr32[1] = 0;
 674                 }
 675
 676                 tmp = realloc(routes, sizeof(*routes) * (routes_cnt + 1));
 677                 if (!tmp) {
 678                         syslog(LOG_ERR, "Realloc failed for RA route option on %s", iface->name);
 679                         continue;
 680                 }
 681
 682                 routes = tmp;
 683
 684                 memset(&routes[routes_cnt], 0, sizeof(*routes));
 685                 routes[routes_cnt].type = ND_OPT_ROUTE_INFO;
 686                 routes[routes_cnt].len = sizeof(*routes) / 8;
 687                 routes[routes_cnt].prefix = addr->dprefix;
 688                 routes[routes_cnt].flags = 0;
 689                 if (iface->route_preference < 0)
 690                         routes[routes_cnt].flags |= ND_RA_PREF_LOW;
 691                 else if (iface->route_preference > 0)
 692                         routes[routes_cnt].flags |= ND_RA_PREF_HIGH;
 693
 694                 valid = TIME_LEFT(addr->valid, now);
 695                 routes[routes_cnt].lifetime = htonl(valid < lifetime ? valid : lifetime);
 696                 routes[routes_cnt].addr[0] = addr->addr.in6.s6_addr32[0];
 697                 routes[routes_cnt].addr[1] = addr->addr.in6.s6_addr32[1];
 698                 routes[routes_cnt].addr[2] = 0;
 699                 routes[routes_cnt].addr[3] = 0;
 700
 701                 ++routes_cnt;
 702         }
 703
 704         iov[IOV_RA_ROUTES].iov_base = (char *)routes;
 705         iov[IOV_RA_ROUTES].iov_len = routes_cnt * sizeof(*routes);
 706
 707         memset(&adv_interval, 0, sizeof(adv_interval));
 708         adv_interval.nd_opt_adv_interval_type = ND_OPT_RTR_ADV_INTERVAL;
 709         adv_interval.nd_opt_adv_interval_len = 1;
 710         adv_interval.nd_opt_adv_interval_ival = htonl(maxival);
 711
 712         iov[IOV_RA_ADV_INTERVAL].iov_base = (char *)&adv_interval;
 713         iov[IOV_RA_ADV_INTERVAL].iov_len = adv_interval.nd_opt_adv_interval_len * 8;
 714
 715         memset(&dest, 0, sizeof(dest));
 716         dest.sin6_family = AF_INET6;
 717
 718         if (from && !IN6_IS_ADDR_UNSPECIFIED(from))
 719                 dest.sin6_addr = *from;
 720         else
 721                 inet_pton(AF_INET6, ALL_IPV6_NODES, &dest.sin6_addr);
 722
 723         syslog(LOG_NOTICE, "Sending a RA on %s", iface->name);
 724
 725         odhcpd_send(iface->router_event.uloop.fd, &dest, iov, ARRAY_SIZE(iov), iface);
 726
 727         free(pfxs);
 728         free(routes);
 729
 730         return msecs;
 731 }
 732
 733
 734 static void trigger_router_advert(struct uloop_timeout *event)
 735 {
 736         struct interface *iface = container_of(event, struct interface, timer_rs);
 737         int msecs = send_router_advert(iface, NULL);
 738
 739         /* Rearm timer if not shut down */
 740         if (event->cb)
 741                 uloop_timeout_set(event, msecs);
 742 }
 743
 744
 745 /* Event handler for incoming ICMPv6 packets */
 746 static void handle_icmpv6(void *addr, void *data, size_t len,
 747                 struct interface *iface, _unused void *dest)
 748 {
 749         struct icmp6_hdr *hdr = data;
 750         struct sockaddr_in6 *from = addr;
 751
 752         if (!router_icmpv6_valid(addr, data, len))
 753                 return;
 754
 755         if ((iface->ra == MODE_SERVER && !iface->master)) { /* Server mode */
 756                 if (hdr->icmp6_type == ND_ROUTER_SOLICIT)
 757                         send_router_advert(iface, &from->sin6_addr);
 758         } else if (iface->ra == MODE_RELAY) { /* Relay mode */
 759                 if (hdr->icmp6_type == ND_ROUTER_SOLICIT && !iface->master) {
 760                         struct interface *c;
 761
 762                         avl_for_each_element(&interfaces, c, avl) {
 763                                 if (!c->master || c->ra != MODE_RELAY)
 764                                         continue;
 765
 766                                 forward_router_solicitation(c);
 767                         }
 768                 } else if (hdr->icmp6_type == ND_ROUTER_ADVERT && iface->master)
 769                         forward_router_advertisement(iface, data, len);
 770         }
 771 }
 772
 773
 774 /* Forward router solicitation */
 775 static void forward_router_solicitation(const struct interface *iface)
 776 {
 777         struct icmp6_hdr rs = {ND_ROUTER_SOLICIT, 0, 0, {{0}}};
 778         struct iovec iov = {&rs, sizeof(rs)};
 779         struct sockaddr_in6 all_routers;
 780
 781         if (!iface)
 782                 return;
 783
 784         memset(&all_routers, 0, sizeof(all_routers));
 785         all_routers.sin6_family = AF_INET6;
 786         inet_pton(AF_INET6, ALL_IPV6_ROUTERS, &all_routers.sin6_addr);
 787         all_routers.sin6_scope_id = iface->ifindex;
 788
 789         syslog(LOG_NOTICE, "Sending RS to %s", iface->name);
 790         odhcpd_send(iface->router_event.uloop.fd, &all_routers, &iov, 1, iface);
 791 }
 792
 793
 794 /* Handler for incoming router solicitations on slave interfaces */
 795 static void forward_router_advertisement(const struct interface *iface, uint8_t *data, size_t len)
 796 {
 797         struct nd_router_advert *adv = (struct nd_router_advert *)data;
 798         struct sockaddr_in6 all_nodes;
 799         struct icmpv6_opt *opt;
 800         struct interface *c;
 801         struct iovec iov = { .iov_base = data, .iov_len = len };
 802         /* Rewrite options */
 803         uint8_t *end = data + len;
 804         uint8_t *mac_ptr = NULL;
 805         struct in6_addr *dns_ptr = NULL;
 806         size_t dns_count = 0;
 807
 808         icmpv6_for_each_option(opt, &adv[1], end) {
 809                 if (opt->type == ND_OPT_SOURCE_LINKADDR) {
 810                         /* Store address of source MAC-address */
 811                         mac_ptr = opt->data;
 812                 } else if (opt->type == ND_OPT_RECURSIVE_DNS && opt->len > 1) {
 813                         /* Check if we have to rewrite DNS */
 814                         dns_ptr = (struct in6_addr*)&opt->data[6];
 815                         dns_count = (opt->len - 1) / 2;
 816                 }
 817         }
 818
 819         syslog(LOG_NOTICE, "Got a RA on %s", iface->name);
 820
 821         /* Indicate a proxy, however we don't follow the rest of RFC 4389 yet */
 822         adv->nd_ra_flags_reserved |= ND_RA_FLAG_PROXY;
 823
 824         /* Forward advertisement to all slave interfaces */
 825         memset(&all_nodes, 0, sizeof(all_nodes));
 826         all_nodes.sin6_family = AF_INET6;
 827         inet_pton(AF_INET6, ALL_IPV6_NODES, &all_nodes.sin6_addr);
 828
 829         avl_for_each_element(&interfaces, c, avl) {
 830                 if (c->ra != MODE_RELAY || c->master)
 831                         continue;
 832
 833                 /* Fixup source hardware address option */
 834                 if (mac_ptr)
 835                         odhcpd_get_mac(c, mac_ptr);
 836
 837                 /* If we have to rewrite DNS entries */
 838                 if (c->always_rewrite_dns && dns_ptr && dns_count > 0) {
 839                         const struct in6_addr *rewrite = c->dns;
 840                         struct in6_addr addr;
 841                         size_t rewrite_cnt = c->dns_cnt;
 842
 843                         if (rewrite_cnt == 0) {
 844                                 if (odhcpd_get_interface_dns_addr(c, &addr))
 845                                         continue; /* Unable to comply */
 846
 847                                 rewrite = &addr;
 848                                 rewrite_cnt = 1;
 849                         }
 850
 851                         /* Copy over any other addresses */
 852                         for (size_t i = 0; i < dns_count; ++i) {
 853                                 size_t j = (i < rewrite_cnt) ? i : rewrite_cnt - 1;
 854                                 dns_ptr[i] = rewrite[j];
 855                         }
 856                 }
 857
 858                 syslog(LOG_NOTICE, "Forward a RA on %s", c->name);
 859
 860                 odhcpd_send(c->router_event.uloop.fd, &all_nodes, &iov, 1, c);
 861         }
 862 }