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                 if (iface->router_event.uloop.registered)
 217                         uloop_fd_delete(&iface->router_event.uloop);
 218
 219                 close(iface->router_event.uloop.fd);
 220                 iface->router_event.uloop.fd = -1;
 221         }
 222
 223         return ret;
 224 }
 225
 226
 227 static void router_netevent_cb(unsigned long event, struct netevent_handler_info *info)
 228 {
 229         struct interface *iface;
 230
 231         switch (event) {
 232         case NETEV_ROUTE6_ADD:
 233         case NETEV_ROUTE6_DEL:
 234                 if (info->rt.dst_len)
 235                         break;
 236
 237                 avl_for_each_element(&interfaces, iface, avl) {
 238                         if (iface->ra == MODE_SERVER && !iface->master)
 239                                 uloop_timeout_set(&iface->timer_rs, 1000);
 240                 }
 241                 break;
 242         case NETEV_ADDR6LIST_CHANGE:
 243                 iface = info->iface;
 244                 if (iface && iface->ra == MODE_SERVER && !iface->master)
 245                         uloop_timeout_set(&iface->timer_rs, 1000);
 246                 break;
 247         default:
 248                 break;
 249         }
 250 }
 251
 252
 253 static bool router_icmpv6_valid(struct sockaddr_in6 *source, uint8_t *data, size_t len)
 254 {
 255         struct icmp6_hdr *hdr = (struct icmp6_hdr *)data;
 256         struct icmpv6_opt *opt, *end = (struct icmpv6_opt*)&data[len];
 257
 258         /* Hoplimit is already checked in odhcpd_receive_packets */
 259         if (len < sizeof(*hdr) || hdr->icmp6_code)
 260                 return false;
 261
 262         switch (hdr->icmp6_type) {
 263         case ND_ROUTER_ADVERT:
 264                 if (!IN6_IS_ADDR_LINKLOCAL(&source->sin6_addr))
 265                         return false;
 266
 267                 opt = (struct icmpv6_opt *)((struct nd_router_advert *)data + 1);
 268                 break;
 269
 270         case ND_ROUTER_SOLICIT:
 271                 opt = (struct icmpv6_opt *)((struct nd_router_solicit *)data + 1);
 272                 break;
 273
 274         default:
 275                 return false;
 276         }
 277
 278         icmpv6_for_each_option(opt, opt, end)
 279                 if (opt->type == ND_OPT_SOURCE_LINKADDR &&
 280                                 IN6_IS_ADDR_UNSPECIFIED(&source->sin6_addr) &&
 281                                 hdr->icmp6_type == ND_ROUTER_SOLICIT)
 282                         return false;
 283
 284         /* Check all options parsed successfully */
 285         return opt == end;
 286 }
 287
 288
 289 /* Detect whether a default route exists, also find the source prefixes */
 290 static bool parse_routes(struct odhcpd_ipaddr *n, ssize_t len)
 291 {
 292         struct odhcpd_ipaddr p = { .addr.in6 = IN6ADDR_ANY_INIT, .prefix = 0,
 293                                         .dprefix = 0, .preferred = 0, .valid = 0};
 294         bool found_default = false;
 295         char line[512], ifname[16];
 296
 297         rewind(fp_route);
 298
 299         while (fgets(line, sizeof(line), fp_route)) {
 300                 uint32_t rflags;
 301                 if (sscanf(line, "00000000000000000000000000000000 00 "
 302                                 "%*s %*s %*s %*s %*s %*s %*s %15s", ifname) &&
 303                                 strcmp(ifname, "lo")) {
 304                         found_default = true;
 305                 } else if (sscanf(line, "%8" SCNx32 "%8" SCNx32 "%*8" SCNx32 "%*8" SCNx32 " %hhx %*s "
 306                                 "%*s 00000000000000000000000000000000 %*s %*s %*s %" SCNx32 " lo",
 307                                 &p.addr.in6.s6_addr32[0], &p.addr.in6.s6_addr32[1], &p.prefix, &rflags) &&
 308                                 p.prefix > 0 && (rflags & RTF_NONEXTHOP) && (rflags & RTF_REJECT)) {
 309                         // Find source prefixes by scanning through unreachable-routes
 310                         p.addr.in6.s6_addr32[0] = htonl(p.addr.in6.s6_addr32[0]);
 311                         p.addr.in6.s6_addr32[1] = htonl(p.addr.in6.s6_addr32[1]);
 312
 313                         for (ssize_t i = 0; i < len; ++i) {
 314                                 if (n[i].prefix <= 64 && n[i].prefix >= p.prefix &&
 315                                                 !odhcpd_bmemcmp(&p.addr.in6, &n[i].addr.in6, p.prefix)) {
 316                                         n[i].dprefix = p.prefix;
 317                                         break;
 318                                 }
 319                         }
 320                 }
 321         }
 322
 323         return found_default;
 324 }
 325
 326 static int calc_adv_interval(struct interface *iface, uint32_t minvalid,
 327                              uint32_t *maxival)
 328 {
 329         uint32_t minival = iface->ra_mininterval;
 330         int msecs;
 331
 332         *maxival = iface->ra_maxinterval;
 333
 334         if (*maxival > minvalid/3)
 335                 *maxival = minvalid/3;
 336
 337         if (*maxival > MaxRtrAdvInterval)
 338                 *maxival = MaxRtrAdvInterval;
 339         else if (*maxival < 4)
 340                 *maxival = 4;
 341
 342         if (minival < MinRtrAdvInterval)
 343                 minival = MinRtrAdvInterval;
 344         else if (minival > (*maxival * 3)/4)
 345                 minival = (*maxival >= 9 ? *maxival/3 : *maxival);
 346
 347         odhcpd_urandom(&msecs, sizeof(msecs));
 348         msecs = (labs(msecs) % ((*maxival != minival) ? (*maxival - minival)*1000 : 500)) +
 349                         minival*1000;
 350
 351         return msecs;
 352 }
 353
 354 static uint32_t calc_ra_lifetime(struct interface *iface, uint32_t maxival)
 355 {
 356         uint32_t lifetime = 3*maxival;
 357
 358         if (iface->ra_lifetime >= 0) {
 359                 lifetime = iface->ra_lifetime;
 360                 if (lifetime > 0 && lifetime < maxival)
 361                         lifetime = maxival;
 362                 else if (lifetime > 9000)
 363                         lifetime = 9000;
 364         }
 365
 366         return lifetime;
 367 }
 368
 369 enum {
 370         IOV_RA_ADV=0,
 371         IOV_RA_PFXS,
 372         IOV_RA_ROUTES,
 373         IOV_RA_DNS,
 374         IOV_RA_SEARCH,
 375         IOV_RA_ADV_INTERVAL,
 376         IOV_RA_TOTAL,
 377 };
 378
 379 struct adv_msg {
 380         struct nd_router_advert h;
 381         struct icmpv6_opt lladdr;
 382         struct nd_opt_mtu mtu;
 383 };
 384
 385 struct nd_opt_dns_server {
 386         uint8_t type;
 387         uint8_t len;
 388         uint8_t pad;
 389         uint8_t pad2;
 390         uint32_t lifetime;
 391         struct in6_addr addr[];
 392 };
 393
 394 struct nd_opt_search_list {
 395         uint8_t type;
 396         uint8_t len;
 397         uint8_t pad;
 398         uint8_t pad2;
 399         uint32_t lifetime;
 400         uint8_t name[];
 401 };
 402
 403 struct nd_opt_route_info {
 404         uint8_t type;
 405         uint8_t len;
 406         uint8_t prefix;
 407         uint8_t flags;
 408         uint32_t lifetime;
 409         uint32_t addr[4];
 410 };
 411
 412 /* Router Advert server mode */
 413 static int send_router_advert(struct interface *iface, const struct in6_addr *from)
 414 {
 415         time_t now = odhcpd_time();
 416         struct odhcpd_ipaddr *addrs = NULL;
 417         struct adv_msg adv;
 418         struct nd_opt_prefix_info *pfxs = NULL;
 419         struct nd_opt_dns_server *dns = NULL;
 420         struct nd_opt_search_list *search = NULL;
 421         struct nd_opt_route_info *routes = NULL;
 422         struct nd_opt_adv_interval adv_interval;
 423         struct iovec iov[IOV_RA_TOTAL];
 424         struct sockaddr_in6 dest;
 425         size_t dns_sz = 0, search_sz = 0, pfxs_cnt = 0, routes_cnt = 0;
 426         ssize_t addr_cnt = 0;
 427         uint32_t minvalid = UINT32_MAX, maxival, lifetime;
 428         int msecs, mtu = iface->ra_mtu, hlim = iface->ra_hoplimit;
 429         bool default_route = false;
 430         bool valid_prefix = false;
 431         char buf[INET6_ADDRSTRLEN];
 432
 433         memset(&adv, 0, sizeof(adv));
 434         adv.h.nd_ra_type = ND_ROUTER_ADVERT;
 435
 436         if (hlim == 0)
 437                 hlim = odhcpd_get_interface_config(iface->ifname, "hop_limit");
 438
 439         if (hlim > 0)
 440                 adv.h.nd_ra_curhoplimit = hlim;
 441
 442         adv.h.nd_ra_flags_reserved = iface->ra_flags;
 443
 444         if (iface->route_preference < 0)
 445                 adv.h.nd_ra_flags_reserved |= ND_RA_PREF_LOW;
 446         else if (iface->route_preference > 0)
 447                 adv.h.nd_ra_flags_reserved |= ND_RA_PREF_HIGH;
 448
 449         adv.h.nd_ra_reachable = htonl(iface->ra_reachabletime);
 450         adv.h.nd_ra_retransmit = htonl(iface->ra_retranstime);
 451
 452         adv.lladdr.type = ND_OPT_SOURCE_LINKADDR;
 453         adv.lladdr.len = 1;
 454         odhcpd_get_mac(iface, adv.lladdr.data);
 455
 456         adv.mtu.nd_opt_mtu_type = ND_OPT_MTU;
 457         adv.mtu.nd_opt_mtu_len = 1;
 458
 459         if (mtu == 0)
 460                 mtu = odhcpd_get_interface_config(iface->ifname, "mtu");
 461
 462         if (mtu < 1280)
 463                 mtu = 1280;
 464
 465         adv.mtu.nd_opt_mtu_mtu = htonl(mtu);
 466
 467         iov[IOV_RA_ADV].iov_base = (char *)&adv;
 468         iov[IOV_RA_ADV].iov_len = sizeof(adv);
 469
 470         /* If not shutdown */
 471         if (iface->timer_rs.cb) {
 472                 size_t size = sizeof(*addrs) * iface->addr6_len;
 473
 474                 addrs = alloca(size);
 475                 memcpy(addrs, iface->addr6, size);
 476
 477                 addr_cnt = iface->addr6_len;
 478
 479                 /* Check default route */
 480                 if (iface->default_router) {
 481                         default_route = true;
 482
 483                         if (iface->default_router > 1)
 484                                 valid_prefix = true;
 485                 } else if (parse_routes(addrs, addr_cnt))
 486                         default_route = true;
 487         }
 488
 489         /* Construct Prefix Information options */
 490         for (ssize_t i = 0; i < addr_cnt; ++i) {
 491                 struct odhcpd_ipaddr *addr = &addrs[i];
 492                 struct nd_opt_prefix_info *p = NULL;
 493                 uint32_t preferred = 0;
 494                 uint32_t valid = 0;
 495
 496                 if (addr->prefix > 96 || addr->valid <= (uint32_t)now) {
 497                         syslog(LOG_INFO, "Address %s (prefix %d, valid %u) not suitable as RA prefix on %s",
 498                                 inet_ntop(AF_INET6, &addr->addr.in6, buf, sizeof(buf)), addr->prefix,
 499                                 addr->valid, iface->name);
 500                         continue;
 501                 }
 502
 503                 if (odhcpd_bmemcmp(&addr->addr, &iface->pio_filter_addr,
 504                                    iface->pio_filter_length) != 0 ||
 505                     addr->prefix < iface->pio_filter_length) {
 506                         syslog(LOG_INFO, "Address %s filtered out as RA prefix on %s",
 507                                inet_ntop(AF_INET6, &addr->addr.in6, buf, sizeof(buf)),
 508                                iface->name);
 509                         continue; /* PIO filtered out of this RA */
 510                 }
 511
 512                 for (size_t i = 0; i < pfxs_cnt; ++i) {
 513                         if (addr->prefix == pfxs[i].nd_opt_pi_prefix_len &&
 514                                         !odhcpd_bmemcmp(&pfxs[i].nd_opt_pi_prefix,
 515                                         &addr->addr.in6, addr->prefix))
 516                                 p = &pfxs[i];
 517                 }
 518
 519                 if (!p) {
 520                         struct nd_opt_prefix_info *tmp;
 521
 522                         tmp = realloc(pfxs, sizeof(*pfxs) * (pfxs_cnt + 1));
 523                         if (!tmp) {
 524                                 syslog(LOG_ERR, "Realloc failed for RA prefix option on %s", iface->name);
 525                                 continue;
 526                         }
 527
 528                         pfxs = tmp;
 529                         p = &pfxs[pfxs_cnt++];
 530                         memset(p, 0, sizeof(*p));
 531                 }
 532
 533                 if (addr->preferred > (uint32_t)now) {
 534                         preferred = TIME_LEFT(addr->preferred, now);
 535
 536                         if (iface->ra_useleasetime &&
 537                                         preferred > iface->dhcpv4_leasetime)
 538                                 preferred = iface->dhcpv4_leasetime;
 539                 }
 540
 541                 valid = TIME_LEFT(addr->valid, now);
 542                 if (iface->ra_useleasetime && valid > iface->dhcpv4_leasetime)
 543                         valid = iface->dhcpv4_leasetime;
 544
 545                 if (minvalid > valid)
 546                         minvalid = valid;
 547
 548                 if (!IN6_IS_ADDR_ULA(&addr->addr.in6) || iface->default_router)
 549                         valid_prefix = true;
 550
 551                 odhcpd_bmemcpy(&p->nd_opt_pi_prefix, &addr->addr.in6,
 552                                 (iface->ra_advrouter) ? 128 : addr->prefix);
 553                 p->nd_opt_pi_type = ND_OPT_PREFIX_INFORMATION;
 554                 p->nd_opt_pi_len = 4;
 555                 p->nd_opt_pi_prefix_len = (addr->prefix < 64) ? 64 : addr->prefix;
 556                 p->nd_opt_pi_flags_reserved = 0;
 557                 if (!iface->ra_not_onlink)
 558                         p->nd_opt_pi_flags_reserved |= ND_OPT_PI_FLAG_ONLINK;
 559                 if (iface->ra_slaac && addr->prefix <= 64)
 560                         p->nd_opt_pi_flags_reserved |= ND_OPT_PI_FLAG_AUTO;
 561                 if (iface->ra_advrouter)
 562                         p->nd_opt_pi_flags_reserved |= ND_OPT_PI_FLAG_RADDR;
 563                 p->nd_opt_pi_preferred_time = htonl(preferred);
 564                 p->nd_opt_pi_valid_time = htonl(valid);
 565         }
 566
 567         iov[IOV_RA_PFXS].iov_base = (char *)pfxs;
 568         iov[IOV_RA_PFXS].iov_len = pfxs_cnt * sizeof(*pfxs);
 569
 570         /* Calculate periodic transmit */
 571         msecs = calc_adv_interval(iface, minvalid, &maxival);
 572         lifetime = calc_ra_lifetime(iface, maxival);
 573
 574         if (default_route) {
 575                 if (!valid_prefix) {
 576                         syslog(LOG_WARNING, "A default route is present but there is no public prefix "
 577                                         "on %s thus we don't announce a default route!", iface->name);
 578                         adv.h.nd_ra_router_lifetime = 0;
 579                 } else
 580                         adv.h.nd_ra_router_lifetime = htons(lifetime < UINT16_MAX ? lifetime : UINT16_MAX);
 581
 582         } else
 583                 adv.h.nd_ra_router_lifetime = 0;
 584
 585         syslog(LOG_INFO, "Using a RA lifetime of %d seconds on %s", ntohs(adv.h.nd_ra_router_lifetime), iface->name);
 586
 587         /* DNS options */
 588         if (iface->ra_dns) {
 589                 struct in6_addr dns_pref, *dns_addr = NULL;
 590                 size_t dns_cnt = 0, search_len = iface->search_len;
 591                 uint8_t *search_domain = iface->search;
 592
 593                 /* DNS Recursive DNS */
 594                 if (iface->dns_cnt > 0) {
 595                         dns_addr = iface->dns;
 596                         dns_cnt = iface->dns_cnt;
 597                 } else if (!odhcpd_get_interface_dns_addr(iface, &dns_pref)) {
 598                         dns_addr = &dns_pref;
 599                         dns_cnt = 1;
 600                 }
 601
 602                 if (dns_cnt) {
 603                         dns_sz = sizeof(*dns) + sizeof(struct in6_addr)*dns_cnt;
 604
 605                         dns = alloca(dns_sz);
 606                         memset(dns, 0, dns_sz);
 607                         dns->type = ND_OPT_RECURSIVE_DNS;
 608                         dns->len = 1 + (2 * dns_cnt);
 609                         dns->lifetime = htonl(lifetime);
 610                         memcpy(dns->addr, dns_addr, sizeof(struct in6_addr)*dns_cnt);
 611                 }
 612
 613                 /* DNS Search options */
 614                 if (!search_domain && !res_init() && _res.dnsrch[0] && _res.dnsrch[0][0]) {
 615                         uint8_t search_buf[256];
 616
 617                         int len = dn_comp(_res.dnsrch[0], search_buf,
 618                                         sizeof(search_buf), NULL, NULL);
 619                         if (len > 0) {
 620                                 search_domain = search_buf;
 621                                 search_len = len;
 622                         }
 623                 }
 624
 625                 if (search_len > 0) {
 626                         size_t search_padded = ((search_len + 7) & (~7)) + 8;
 627
 628                         search_sz = sizeof(*search) + search_padded;
 629
 630                         search = alloca(search_sz);
 631                         memset(search, 0, search_sz);
 632                         search->type = ND_OPT_DNS_SEARCH;
 633                         search->len = search_len ? ((sizeof(*search) + search_padded) / 8) : 0;
 634                         search->lifetime = htonl(lifetime);
 635                         memcpy(search->name, search_domain, search_len);
 636                         memset(&search->name[search_len], 0, search_padded - search_len);
 637                 }
 638         }
 639
 640         iov[IOV_RA_DNS].iov_base = (char *)dns;
 641         iov[IOV_RA_DNS].iov_len = dns_sz;
 642         iov[IOV_RA_SEARCH].iov_base = (char *)search;
 643         iov[IOV_RA_SEARCH].iov_len = search_sz;
 644
 645         for (ssize_t i = 0; i < addr_cnt; ++i) {
 646                 struct odhcpd_ipaddr *addr = &addrs[i];
 647                 struct nd_opt_route_info *tmp;
 648                 uint32_t valid;
 649
 650                 if (addr->dprefix > 64 || addr->dprefix == 0 || addr->valid <= (uint32_t)now) {
 651                         syslog(LOG_INFO, "Address %s (dprefix %d, valid %u) not suitable as RA route on %s",
 652                                 inet_ntop(AF_INET6, &addr->addr.in6, buf, sizeof(buf)),
 653                                 addr->dprefix, addr->valid, iface->name);
 654
 655                         continue; /* Address not suitable */
 656                 }
 657
 658                 if (odhcpd_bmemcmp(&addr->addr, &iface->pio_filter_addr,
 659                                 iface->pio_filter_length) != 0 ||
 660                                 addr->prefix < iface->pio_filter_length) {
 661                         syslog(LOG_INFO, "Address %s filtered out as RA route on %s",
 662                                inet_ntop(AF_INET6, &addr->addr.in6, buf, sizeof(buf)),
 663                                iface->name);
 664                         continue; /* PIO filtered out of this RA */
 665                 }
 666
 667                 if (addr->dprefix > 32) {
 668                         addr->addr.in6.s6_addr32[1] &= htonl(~((1U << (64 - addr->dprefix)) - 1));
 669                 } else if (addr->dprefix <= 32) {
 670                         addr->addr.in6.s6_addr32[0] &= htonl(~((1U << (32 - addr->dprefix)) - 1));
 671                         addr->addr.in6.s6_addr32[1] = 0;
 672                 }
 673
 674                 tmp = realloc(routes, sizeof(*routes) * (routes_cnt + 1));
 675                 if (!tmp) {
 676                         syslog(LOG_ERR, "Realloc failed for RA route option on %s", iface->name);
 677                         continue;
 678                 }
 679
 680                 routes = tmp;
 681
 682                 memset(&routes[routes_cnt], 0, sizeof(*routes));
 683                 routes[routes_cnt].type = ND_OPT_ROUTE_INFO;
 684                 routes[routes_cnt].len = sizeof(*routes) / 8;
 685                 routes[routes_cnt].prefix = addr->dprefix;
 686                 routes[routes_cnt].flags = 0;
 687                 if (iface->route_preference < 0)
 688                         routes[routes_cnt].flags |= ND_RA_PREF_LOW;
 689                 else if (iface->route_preference > 0)
 690                         routes[routes_cnt].flags |= ND_RA_PREF_HIGH;
 691
 692                 valid = TIME_LEFT(addr->valid, now);
 693                 routes[routes_cnt].lifetime = htonl(valid < lifetime ? valid : lifetime);
 694                 routes[routes_cnt].addr[0] = addr->addr.in6.s6_addr32[0];
 695                 routes[routes_cnt].addr[1] = addr->addr.in6.s6_addr32[1];
 696                 routes[routes_cnt].addr[2] = 0;
 697                 routes[routes_cnt].addr[3] = 0;
 698
 699                 ++routes_cnt;
 700         }
 701
 702         iov[IOV_RA_ROUTES].iov_base = (char *)routes;
 703         iov[IOV_RA_ROUTES].iov_len = routes_cnt * sizeof(*routes);
 704
 705         memset(&adv_interval, 0, sizeof(adv_interval));
 706         adv_interval.nd_opt_adv_interval_type = ND_OPT_RTR_ADV_INTERVAL;
 707         adv_interval.nd_opt_adv_interval_len = 1;
 708         adv_interval.nd_opt_adv_interval_ival = htonl(maxival);
 709
 710         iov[IOV_RA_ADV_INTERVAL].iov_base = (char *)&adv_interval;
 711         iov[IOV_RA_ADV_INTERVAL].iov_len = adv_interval.nd_opt_adv_interval_len * 8;
 712
 713         memset(&dest, 0, sizeof(dest));
 714         dest.sin6_family = AF_INET6;
 715
 716         if (from && !IN6_IS_ADDR_UNSPECIFIED(from))
 717                 dest.sin6_addr = *from;
 718         else
 719                 inet_pton(AF_INET6, ALL_IPV6_NODES, &dest.sin6_addr);
 720
 721         syslog(LOG_NOTICE, "Sending a RA on %s", iface->name);
 722
 723         odhcpd_send(iface->router_event.uloop.fd, &dest, iov, ARRAY_SIZE(iov), iface);
 724
 725         free(pfxs);
 726         free(routes);
 727
 728         return msecs;
 729 }
 730
 731
 732 static void trigger_router_advert(struct uloop_timeout *event)
 733 {
 734         struct interface *iface = container_of(event, struct interface, timer_rs);
 735         int msecs = send_router_advert(iface, NULL);
 736
 737         /* Rearm timer if not shut down */
 738         if (event->cb)
 739                 uloop_timeout_set(event, msecs);
 740 }
 741
 742
 743 /* Event handler for incoming ICMPv6 packets */
 744 static void handle_icmpv6(void *addr, void *data, size_t len,
 745                 struct interface *iface, _unused void *dest)
 746 {
 747         struct icmp6_hdr *hdr = data;
 748         struct sockaddr_in6 *from = addr;
 749
 750         if (!router_icmpv6_valid(addr, data, len))
 751                 return;
 752
 753         if ((iface->ra == MODE_SERVER && !iface->master)) { /* Server mode */
 754                 if (hdr->icmp6_type == ND_ROUTER_SOLICIT)
 755                         send_router_advert(iface, &from->sin6_addr);
 756         } else if (iface->ra == MODE_RELAY) { /* Relay mode */
 757                 if (hdr->icmp6_type == ND_ROUTER_SOLICIT && !iface->master) {
 758                         struct interface *c;
 759
 760                         avl_for_each_element(&interfaces, c, avl) {
 761                                 if (!c->master || c->ra != MODE_RELAY)
 762                                         continue;
 763
 764                                 forward_router_solicitation(c);
 765                         }
 766                 } else if (hdr->icmp6_type == ND_ROUTER_ADVERT && iface->master)
 767                         forward_router_advertisement(iface, data, len);
 768         }
 769 }
 770
 771
 772 /* Forward router solicitation */
 773 static void forward_router_solicitation(const struct interface *iface)
 774 {
 775         struct icmp6_hdr rs = {ND_ROUTER_SOLICIT, 0, 0, {{0}}};
 776         struct iovec iov = {&rs, sizeof(rs)};
 777         struct sockaddr_in6 all_routers;
 778
 779         if (!iface)
 780                 return;
 781
 782         memset(&all_routers, 0, sizeof(all_routers));
 783         all_routers.sin6_family = AF_INET6;
 784         inet_pton(AF_INET6, ALL_IPV6_ROUTERS, &all_routers.sin6_addr);
 785         all_routers.sin6_scope_id = iface->ifindex;
 786
 787         syslog(LOG_NOTICE, "Sending RS to %s", iface->name);
 788         odhcpd_send(iface->router_event.uloop.fd, &all_routers, &iov, 1, iface);
 789 }
 790
 791
 792 /* Handler for incoming router solicitations on slave interfaces */
 793 static void forward_router_advertisement(const struct interface *iface, uint8_t *data, size_t len)
 794 {
 795         struct nd_router_advert *adv = (struct nd_router_advert *)data;
 796         struct sockaddr_in6 all_nodes;
 797         struct icmpv6_opt *opt;
 798         struct interface *c;
 799         struct iovec iov = { .iov_base = data, .iov_len = len };
 800         /* Rewrite options */
 801         uint8_t *end = data + len;
 802         uint8_t *mac_ptr = NULL;
 803         struct in6_addr *dns_ptr = NULL;
 804         size_t dns_count = 0;
 805
 806         icmpv6_for_each_option(opt, &adv[1], end) {
 807                 if (opt->type == ND_OPT_SOURCE_LINKADDR) {
 808                         /* Store address of source MAC-address */
 809                         mac_ptr = opt->data;
 810                 } else if (opt->type == ND_OPT_RECURSIVE_DNS && opt->len > 1) {
 811                         /* Check if we have to rewrite DNS */
 812                         dns_ptr = (struct in6_addr*)&opt->data[6];
 813                         dns_count = (opt->len - 1) / 2;
 814                 }
 815         }
 816
 817         syslog(LOG_NOTICE, "Got a RA on %s", iface->name);
 818
 819         /* Indicate a proxy, however we don't follow the rest of RFC 4389 yet */
 820         adv->nd_ra_flags_reserved |= ND_RA_FLAG_PROXY;
 821
 822         /* Forward advertisement to all slave interfaces */
 823         memset(&all_nodes, 0, sizeof(all_nodes));
 824         all_nodes.sin6_family = AF_INET6;
 825         inet_pton(AF_INET6, ALL_IPV6_NODES, &all_nodes.sin6_addr);
 826
 827         avl_for_each_element(&interfaces, c, avl) {
 828                 if (c->ra != MODE_RELAY || c->master)
 829                         continue;
 830
 831                 /* Fixup source hardware address option */
 832                 if (mac_ptr)
 833                         odhcpd_get_mac(c, mac_ptr);
 834
 835                 /* If we have to rewrite DNS entries */
 836                 if (c->always_rewrite_dns && dns_ptr && dns_count > 0) {
 837                         const struct in6_addr *rewrite = c->dns;
 838                         struct in6_addr addr;
 839                         size_t rewrite_cnt = c->dns_cnt;
 840
 841                         if (rewrite_cnt == 0) {
 842                                 if (odhcpd_get_interface_dns_addr(c, &addr))
 843                                         continue; /* Unable to comply */
 844
 845                                 rewrite = &addr;
 846                                 rewrite_cnt = 1;
 847                         }
 848
 849                         /* Copy over any other addresses */
 850                         for (size_t i = 0; i < dns_count; ++i) {
 851                                 size_t j = (i < rewrite_cnt) ? i : rewrite_cnt - 1;
 852                                 dns_ptr[i] = rewrite[j];
 853                         }
 854                 }
 855
 856                 syslog(LOG_NOTICE, "Forward a RA on %s", c->name);
 857
 858                 odhcpd_send(c->router_event.uloop.fd, &all_nodes, &iov, 1, c);
 859         }
 860 }