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                         iface->ra_sent = 0;
 180                         odhcpd_register(&iface->router_event);
 181                 } else {
 182                         uloop_timeout_cancel(&iface->timer_rs);
 183                         iface->timer_rs.cb = NULL;
 184
 185                         memset(&mreq, 0, sizeof(mreq));
 186                         mreq.ipv6mr_interface = iface->ifindex;
 187                         inet_pton(AF_INET6, ALL_IPV6_NODES, &mreq.ipv6mr_multiaddr);
 188                         setsockopt(iface->router_event.uloop.fd, IPPROTO_IPV6, IPV6_DROP_MEMBERSHIP,
 189                                    &mreq, sizeof(mreq));
 190
 191                         inet_pton(AF_INET6, ALL_IPV6_ROUTERS, &mreq.ipv6mr_multiaddr);
 192                         setsockopt(iface->router_event.uloop.fd, IPPROTO_IPV6, IPV6_DROP_MEMBERSHIP,
 193                                    &mreq, sizeof(mreq));
 194                 }
 195
 196                 memset(&mreq, 0, sizeof(mreq));
 197                 mreq.ipv6mr_interface = iface->ifindex;
 198                 inet_pton(AF_INET6, ALL_IPV6_ROUTERS, &mreq.ipv6mr_multiaddr);
 199
 200                 if (iface->ra == MODE_RELAY && iface->master) {
 201                         inet_pton(AF_INET6, ALL_IPV6_NODES, &mreq.ipv6mr_multiaddr);
 202                         forward_router_solicitation(iface);
 203                 } else if (iface->ra == MODE_SERVER) {
 204                         iface->timer_rs.cb = trigger_router_advert;
 205                         uloop_timeout_set(&iface->timer_rs, 1000);
 206                 }
 207
 208                 if (setsockopt(iface->router_event.uloop.fd, IPPROTO_IPV6,
 209                                         IPV6_ADD_MEMBERSHIP, &mreq, sizeof(mreq)) < 0) {
 210                         ret = -1;
 211                         syslog(LOG_ERR, "setsockopt(IPV6_ADD_MEMBERSHIP): %m");
 212                         goto out;
 213                 }
 214         }
 215 out:
 216         if (ret < 0 && iface->router_event.uloop.fd >= 0) {
 217                 if (iface->router_event.uloop.registered)
 218                         uloop_fd_delete(&iface->router_event.uloop);
 219
 220                 close(iface->router_event.uloop.fd);
 221                 iface->router_event.uloop.fd = -1;
 222         }
 223
 224         return ret;
 225 }
 226
 227
 228 static void router_netevent_cb(unsigned long event, struct netevent_handler_info *info)
 229 {
 230         struct interface *iface;
 231
 232         switch (event) {
 233         case NETEV_IFINDEX_CHANGE:
 234                 iface = info->iface;
 235                 if (iface && iface->router_event.uloop.fd >= 0) {
 236                         if (iface->router_event.uloop.registered)
 237                                 uloop_fd_delete(&iface->router_event.uloop);
 238
 239                         close(iface->router_event.uloop.fd);
 240                         iface->router_event.uloop.fd = -1;
 241                 }
 242                 break;
 243         case NETEV_ROUTE6_ADD:
 244         case NETEV_ROUTE6_DEL:
 245                 if (info->rt.dst_len)
 246                         break;
 247
 248                 avl_for_each_element(&interfaces, iface, avl) {
 249                         if (iface->ra == MODE_SERVER && !iface->master)
 250                                 uloop_timeout_set(&iface->timer_rs, 1000);
 251                 }
 252                 break;
 253         case NETEV_ADDR6LIST_CHANGE:
 254                 iface = info->iface;
 255                 if (iface && iface->ra == MODE_SERVER && !iface->master)
 256                         uloop_timeout_set(&iface->timer_rs, 1000);
 257                 break;
 258         default:
 259                 break;
 260         }
 261 }
 262
 263
 264 static bool router_icmpv6_valid(struct sockaddr_in6 *source, uint8_t *data, size_t len)
 265 {
 266         struct icmp6_hdr *hdr = (struct icmp6_hdr *)data;
 267         struct icmpv6_opt *opt, *end = (struct icmpv6_opt*)&data[len];
 268
 269         /* Hoplimit is already checked in odhcpd_receive_packets */
 270         if (len < sizeof(*hdr) || hdr->icmp6_code)
 271                 return false;
 272
 273         switch (hdr->icmp6_type) {
 274         case ND_ROUTER_ADVERT:
 275                 if (!IN6_IS_ADDR_LINKLOCAL(&source->sin6_addr))
 276                         return false;
 277
 278                 opt = (struct icmpv6_opt *)((struct nd_router_advert *)data + 1);
 279                 break;
 280
 281         case ND_ROUTER_SOLICIT:
 282                 opt = (struct icmpv6_opt *)((struct nd_router_solicit *)data + 1);
 283                 break;
 284
 285         default:
 286                 return false;
 287         }
 288
 289         icmpv6_for_each_option(opt, opt, end)
 290                 if (opt->type == ND_OPT_SOURCE_LINKADDR &&
 291                                 IN6_IS_ADDR_UNSPECIFIED(&source->sin6_addr) &&
 292                                 hdr->icmp6_type == ND_ROUTER_SOLICIT)
 293                         return false;
 294
 295         /* Check all options parsed successfully */
 296         return opt == end;
 297 }
 298
 299
 300 /* Detect whether a default route exists, also find the source prefixes */
 301 static bool parse_routes(struct odhcpd_ipaddr *n, ssize_t len)
 302 {
 303         struct odhcpd_ipaddr p = { .addr.in6 = IN6ADDR_ANY_INIT, .prefix = 0,
 304                                         .dprefix = 0, .preferred_lt = 0, .valid_lt = 0};
 305         bool found_default = false;
 306         char line[512], ifname[16];
 307
 308         rewind(fp_route);
 309
 310         while (fgets(line, sizeof(line), fp_route)) {
 311                 uint32_t rflags;
 312                 if (sscanf(line, "00000000000000000000000000000000 00 "
 313                                 "%*s %*s %*s %*s %*s %*s %*s %15s", ifname) &&
 314                                 strcmp(ifname, "lo")) {
 315                         found_default = true;
 316                 } else if (sscanf(line, "%8" SCNx32 "%8" SCNx32 "%*8" SCNx32 "%*8" SCNx32 " %hhx %*s "
 317                                 "%*s 00000000000000000000000000000000 %*s %*s %*s %" SCNx32 " lo",
 318                                 &p.addr.in6.s6_addr32[0], &p.addr.in6.s6_addr32[1], &p.prefix, &rflags) &&
 319                                 p.prefix > 0 && (rflags & RTF_NONEXTHOP) && (rflags & RTF_REJECT)) {
 320                         // Find source prefixes by scanning through unreachable-routes
 321                         p.addr.in6.s6_addr32[0] = htonl(p.addr.in6.s6_addr32[0]);
 322                         p.addr.in6.s6_addr32[1] = htonl(p.addr.in6.s6_addr32[1]);
 323
 324                         for (ssize_t i = 0; i < len; ++i) {
 325                                 if (n[i].prefix <= 64 && n[i].prefix >= p.prefix &&
 326                                                 !odhcpd_bmemcmp(&p.addr.in6, &n[i].addr.in6, p.prefix)) {
 327                                         n[i].dprefix = p.prefix;
 328                                         break;
 329                                 }
 330                         }
 331                 }
 332         }
 333
 334         return found_default;
 335 }
 336
 337 static int calc_adv_interval(struct interface *iface, uint32_t lowest_found_lifetime,
 338                                 uint32_t *maxival)
 339 {
 340         uint32_t minival = iface->ra_mininterval;
 341         int msecs;
 342
 343         *maxival = iface->ra_maxinterval;
 344
 345         /*
 346          * rfc4861#section-6.2.1 : AdvDefaultLifetime Default: 3 * MaxRtrAdvInterval
 347          * therefore max interval shall be no greater than 1/3 of the lowest valid
 348          * lease time of all known prefixes.
 349          */
 350         if (*maxival > lowest_found_lifetime/3)
 351                 *maxival = lowest_found_lifetime/3;
 352
 353         if (*maxival > MaxRtrAdvInterval)
 354                 *maxival = MaxRtrAdvInterval;
 355         else if (*maxival < 4)
 356                 *maxival = 4;
 357
 358         if (minival < MinRtrAdvInterval)
 359                 minival = MinRtrAdvInterval;
 360         else if (minival > (*maxival * 3)/4)
 361                 minival = (*maxival >= 9 ? *maxival/3 : *maxival);
 362
 363         odhcpd_urandom(&msecs, sizeof(msecs));
 364         msecs = (labs(msecs) % ((*maxival != minival) ? (*maxival - minival)*1000 : 500)) +
 365                         minival*1000;
 366
 367         /* RFC 2461 6.2.4 For the first MAX_INITIAL_RTR_ADVERTISEMENTS advertisements */
 368         /* if the timer is bigger than MAX_INITIAL_RTR_ADVERT_INTERVAL it should be   */
 369         /* set to MAX_INITIAL_RTR_ADVERT_INTERVAL                                     */
 370         /* Off by one as an initial interval timer has already expired                */
 371         if ((iface->ra_sent + 1) < MaxInitialRtAdvs && msecs > MaxInitialRtrAdvInterval*1000)
 372                 msecs = MaxInitialRtrAdvInterval*1000;
 373
 374         return msecs;
 375 }
 376
 377 static uint32_t calc_ra_lifetime(struct interface *iface, uint32_t maxival)
 378 {
 379         uint32_t lifetime = 3*maxival;
 380
 381         if (iface->ra_lifetime >= 0) {
 382                 lifetime = iface->ra_lifetime;
 383                 if (lifetime > 0 && lifetime < maxival)
 384                         lifetime = maxival;
 385                 else if (lifetime > 9000)
 386                         lifetime = 9000;
 387         }
 388
 389         return lifetime;
 390 }
 391
 392 enum {
 393         IOV_RA_ADV=0,
 394         IOV_RA_PFXS,
 395         IOV_RA_ROUTES,
 396         IOV_RA_DNS,
 397         IOV_RA_SEARCH,
 398         IOV_RA_PREF64,
 399         IOV_RA_ADV_INTERVAL,
 400         IOV_RA_TOTAL,
 401 };
 402
 403 struct adv_msg {
 404         struct nd_router_advert h;
 405         struct icmpv6_opt lladdr;
 406         struct nd_opt_mtu mtu;
 407 };
 408
 409 struct nd_opt_dns_server {
 410         uint8_t type;
 411         uint8_t len;
 412         uint8_t pad;
 413         uint8_t pad2;
 414         uint32_t lifetime;
 415         struct in6_addr addr[];
 416 };
 417
 418 struct nd_opt_search_list {
 419         uint8_t type;
 420         uint8_t len;
 421         uint8_t pad;
 422         uint8_t pad2;
 423         uint32_t lifetime;
 424         uint8_t name[];
 425 };
 426
 427 struct nd_opt_route_info {
 428         uint8_t type;
 429         uint8_t len;
 430         uint8_t prefix;
 431         uint8_t flags;
 432         uint32_t lifetime;
 433         uint32_t addr[4];
 434 };
 435
 436 struct nd_opt_pref64_info {
 437         uint8_t type;
 438         uint8_t len;
 439         uint16_t lifetime_plc;
 440         uint32_t addr[3];
 441 };
 442
 443 /* Router Advert server mode */
 444 static int send_router_advert(struct interface *iface, const struct in6_addr *from)
 445 {
 446         time_t now = odhcpd_time();
 447         struct odhcpd_ipaddr *addrs = NULL;
 448         struct adv_msg adv;
 449         struct nd_opt_prefix_info *pfxs = NULL;
 450         struct nd_opt_dns_server *dns = NULL;
 451         struct nd_opt_search_list *search = NULL;
 452         struct nd_opt_route_info *routes = NULL;
 453         struct nd_opt_pref64_info *pref64 = NULL;
 454         struct nd_opt_adv_interval adv_interval;
 455         struct iovec iov[IOV_RA_TOTAL];
 456         struct sockaddr_in6 dest;
 457         size_t dns_sz = 0, search_sz = 0, pref64_sz = 0;
 458         size_t pfxs_cnt = 0, routes_cnt = 0;
 459         ssize_t valid_addr_cnt = 0, invalid_addr_cnt = 0;
 460         /*
 461          * lowest_found_lifetime stores the lowest lifetime of all prefixes;
 462          * necessary to find shortest adv interval necessary
 463          * for shortest lived prefix
 464          */
 465         uint32_t lowest_found_lifetime = UINT32_MAX, maxival, lifetime;
 466         int msecs, mtu = iface->ra_mtu, hlim = iface->ra_hoplimit;
 467         bool default_route = false;
 468         bool valid_prefix = false;
 469         char buf[INET6_ADDRSTRLEN];
 470
 471         memset(&adv, 0, sizeof(adv));
 472         adv.h.nd_ra_type = ND_ROUTER_ADVERT;
 473
 474         if (hlim == 0)
 475                 hlim = odhcpd_get_interface_config(iface->ifname, "hop_limit");
 476
 477         if (hlim > 0)
 478                 adv.h.nd_ra_curhoplimit = hlim;
 479
 480         adv.h.nd_ra_flags_reserved = iface->ra_flags;
 481
 482         if (iface->route_preference < 0)
 483                 adv.h.nd_ra_flags_reserved |= ND_RA_PREF_LOW;
 484         else if (iface->route_preference > 0)
 485                 adv.h.nd_ra_flags_reserved |= ND_RA_PREF_HIGH;
 486
 487         adv.h.nd_ra_reachable = htonl(iface->ra_reachabletime);
 488         adv.h.nd_ra_retransmit = htonl(iface->ra_retranstime);
 489
 490         adv.lladdr.type = ND_OPT_SOURCE_LINKADDR;
 491         adv.lladdr.len = 1;
 492         odhcpd_get_mac(iface, adv.lladdr.data);
 493
 494         adv.mtu.nd_opt_mtu_type = ND_OPT_MTU;
 495         adv.mtu.nd_opt_mtu_len = 1;
 496
 497         if (mtu == 0)
 498                 mtu = odhcpd_get_interface_config(iface->ifname, "mtu");
 499
 500         if (mtu < 1280)
 501                 mtu = 1280;
 502
 503         adv.mtu.nd_opt_mtu_mtu = htonl(mtu);
 504
 505         iov[IOV_RA_ADV].iov_base = (char *)&adv;
 506         iov[IOV_RA_ADV].iov_len = sizeof(adv);
 507
 508         valid_addr_cnt = (iface->timer_rs.cb /* if not shutdown */ ? iface->addr6_len : 0);
 509         invalid_addr_cnt = iface->invalid_addr6_len;
 510
 511         // check ra_default
 512         if (iface->default_router) {
 513                 default_route = true;
 514
 515                 if (iface->default_router > 1)
 516                         valid_prefix = true;
 517         }
 518
 519         if (valid_addr_cnt + invalid_addr_cnt) {
 520                 addrs = alloca(sizeof(*addrs) * (valid_addr_cnt + invalid_addr_cnt));
 521
 522                 if (valid_addr_cnt) {
 523                         memcpy(addrs, iface->addr6, sizeof(*addrs) * valid_addr_cnt);
 524
 525                         /* Check default route */
 526                         if (!default_route && parse_routes(addrs, valid_addr_cnt))
 527                                 default_route = true;
 528                 }
 529
 530                 if (invalid_addr_cnt) {
 531                         size_t i = 0;
 532
 533                         memcpy(&addrs[valid_addr_cnt], iface->invalid_addr6, sizeof(*addrs) * invalid_addr_cnt);
 534
 535                         /* Remove invalid prefixes that were advertised 3 times */
 536                         while (i < iface->invalid_addr6_len) {
 537                                 if (++iface->invalid_addr6[i].invalid_advertisements >= 3) {
 538                                         if (i + 1 < iface->invalid_addr6_len)
 539                                                 memmove(&iface->invalid_addr6[i], &iface->invalid_addr6[i + 1], sizeof(*addrs) * (iface->invalid_addr6_len - i - 1));
 540
 541                                         iface->invalid_addr6_len--;
 542
 543                                         if (iface->invalid_addr6_len) {
 544                                                 struct odhcpd_ipaddr *new_invalid_addr6 = realloc(iface->invalid_addr6, sizeof(*addrs) * iface->invalid_addr6_len);
 545
 546                                                 if (new_invalid_addr6)
 547                                                         iface->invalid_addr6 = new_invalid_addr6;
 548                                         } else {
 549                                                 free(iface->invalid_addr6);
 550                                                 iface->invalid_addr6 = NULL;
 551                                         }
 552                                 } else
 553                                         ++i;
 554                         }
 555                 }
 556         }
 557
 558         /* Construct Prefix Information options */
 559         for (ssize_t i = 0; i < valid_addr_cnt + invalid_addr_cnt; ++i) {
 560                 struct odhcpd_ipaddr *addr = &addrs[i];
 561                 struct nd_opt_prefix_info *p = NULL;
 562                 uint32_t preferred_lt = 0;
 563                 uint32_t valid_lt = 0;
 564
 565                 if (addr->prefix > 96 || (i < valid_addr_cnt && addr->valid_lt <= (uint32_t)now)) {
 566                         syslog(LOG_INFO, "Address %s (prefix %d, valid-lifetime %u) not suitable as RA prefix on %s",
 567                                 inet_ntop(AF_INET6, &addr->addr.in6, buf, sizeof(buf)), addr->prefix,
 568                                 addr->valid_lt, iface->name);
 569                         continue;
 570                 }
 571
 572                 if (ADDR_MATCH_PIO_FILTER(addr, iface)) {
 573                         syslog(LOG_INFO, "Address %s filtered out as RA prefix on %s",
 574                                         inet_ntop(AF_INET6, &addr->addr.in6, buf, sizeof(buf)),
 575                                         iface->name);
 576                         continue; /* PIO filtered out of this RA */
 577                 }
 578
 579                 for (size_t i = 0; i < pfxs_cnt; ++i) {
 580                         if (addr->prefix == pfxs[i].nd_opt_pi_prefix_len &&
 581                                         !odhcpd_bmemcmp(&pfxs[i].nd_opt_pi_prefix,
 582                                         &addr->addr.in6, addr->prefix))
 583                                 p = &pfxs[i];
 584                 }
 585
 586                 if (!p) {
 587                         struct nd_opt_prefix_info *tmp;
 588
 589                         tmp = realloc(pfxs, sizeof(*pfxs) * (pfxs_cnt + 1));
 590                         if (!tmp) {
 591                                 syslog(LOG_ERR, "Realloc failed for RA prefix option on %s", iface->name);
 592                                 continue;
 593                         }
 594
 595                         pfxs = tmp;
 596                         p = &pfxs[pfxs_cnt++];
 597                         memset(p, 0, sizeof(*p));
 598                 }
 599
 600                 if (addr->preferred_lt > (uint32_t)now) {
 601                         preferred_lt = TIME_LEFT(addr->preferred_lt, now);
 602
 603                         if (preferred_lt > iface->preferred_lifetime) {
 604                                 /* set to possibly user mandated preferred_lt */
 605                                 preferred_lt = iface->preferred_lifetime;
 606                         }
 607                 }
 608
 609                 if (addr->valid_lt > (uint32_t)now) {
 610                         valid_lt = TIME_LEFT(addr->valid_lt, now);
 611
 612                         if (iface->ra_useleasetime && valid_lt > iface->dhcp_leasetime)
 613                                 valid_lt = iface->dhcp_leasetime;
 614                 }
 615
 616                 if (preferred_lt > valid_lt) {
 617                         /*
 618                          * RFC4861 § 6.2.1
 619                          * This value [AdvPreferredLifetime] MUST NOT be larger than
 620                          * AdvValidLifetime.
 621                          */
 622                         preferred_lt = valid_lt;
 623                 }
 624
 625                 if (lowest_found_lifetime > valid_lt)
 626                         lowest_found_lifetime = valid_lt;
 627
 628                 if ((!IN6_IS_ADDR_ULA(&addr->addr.in6) || iface->default_router) && valid_lt)
 629                         valid_prefix = true;
 630
 631                 odhcpd_bmemcpy(&p->nd_opt_pi_prefix, &addr->addr.in6,
 632                                 (iface->ra_advrouter) ? 128 : addr->prefix);
 633                 p->nd_opt_pi_type = ND_OPT_PREFIX_INFORMATION;
 634                 p->nd_opt_pi_len = 4;
 635                 p->nd_opt_pi_prefix_len = (addr->prefix < 64) ? 64 : addr->prefix;
 636                 p->nd_opt_pi_flags_reserved = 0;
 637                 if (!iface->ra_not_onlink)
 638                         p->nd_opt_pi_flags_reserved |= ND_OPT_PI_FLAG_ONLINK;
 639                 if (iface->ra_slaac && addr->prefix <= 64)
 640                         p->nd_opt_pi_flags_reserved |= ND_OPT_PI_FLAG_AUTO;
 641                 if (iface->ra_advrouter)
 642                         p->nd_opt_pi_flags_reserved |= ND_OPT_PI_FLAG_RADDR;
 643                 p->nd_opt_pi_preferred_time = htonl(preferred_lt);
 644                 p->nd_opt_pi_valid_time = htonl(valid_lt);
 645         }
 646
 647         iov[IOV_RA_PFXS].iov_base = (char *)pfxs;
 648         iov[IOV_RA_PFXS].iov_len = pfxs_cnt * sizeof(*pfxs);
 649
 650         /* Calculate periodic transmit */
 651         msecs = calc_adv_interval(iface, lowest_found_lifetime, &maxival);
 652         lifetime = calc_ra_lifetime(iface, maxival);
 653
 654         if (!iface->have_link_local) {
 655                 syslog(LOG_NOTICE, "Skip sending a RA on %s as no link local address is available", iface->name);
 656                 goto out;
 657         }
 658
 659         if (default_route && valid_prefix) {
 660                 adv.h.nd_ra_router_lifetime = htons(lifetime < UINT16_MAX ? lifetime : UINT16_MAX);
 661         } else {
 662                 adv.h.nd_ra_router_lifetime = 0;
 663
 664                 if (default_route) {
 665                         syslog(LOG_WARNING, "A default route is present but there is no public prefix "
 666                                                 "on %s thus we announce no default route by overriding ra_lifetime to 0!", iface->name);
 667                 } else {
 668                         syslog(LOG_WARNING, "No default route present, overriding ra_lifetime to 0!");
 669                 }
 670         }
 671
 672         syslog(LOG_DEBUG, "Using a RA lifetime of %d seconds on %s", ntohs(adv.h.nd_ra_router_lifetime), iface->name);
 673
 674         /* DNS options */
 675         if (iface->ra_dns) {
 676                 struct in6_addr dns_pref, *dns_addr = NULL;
 677                 size_t dns_cnt = 0, search_len = iface->search_len;
 678                 uint8_t *search_domain = iface->search;
 679                 uint8_t search_buf[256];
 680
 681                 /* DNS Recursive DNS aka RDNSS Type 25; RFC8106 */
 682                 if (iface->dns_cnt > 0) {
 683                         dns_addr = iface->dns;
 684                         dns_cnt = iface->dns_cnt;
 685                 } else if (!odhcpd_get_interface_dns_addr(iface, &dns_pref)) {
 686                         dns_addr = &dns_pref;
 687                         dns_cnt = 1;
 688                 }
 689
 690                 if (dns_cnt) {
 691                         dns_sz = sizeof(*dns) + sizeof(struct in6_addr)*dns_cnt;
 692
 693                         dns = alloca(dns_sz);
 694                         memset(dns, 0, dns_sz);
 695                         dns->type = ND_OPT_RECURSIVE_DNS;
 696                         dns->len = 1 + (2 * dns_cnt);
 697                         dns->lifetime = htonl(lifetime);
 698                         memcpy(dns->addr, dns_addr, sizeof(struct in6_addr)*dns_cnt);
 699                 }
 700
 701                 /* DNS Search options aka DNSSL Type 31; RFC8106 */
 702                 if (!search_domain && !res_init() && _res.dnsrch[0] && _res.dnsrch[0][0]) {
 703                         int len = dn_comp(_res.dnsrch[0], search_buf,
 704                                         sizeof(search_buf), NULL, NULL);
 705                         if (len > 0) {
 706                                 search_domain = search_buf;
 707                                 search_len = len;
 708                         }
 709                 }
 710
 711                 if (search_len > 0) {
 712                         size_t search_padded = ((search_len + 7) & (~7)) + 8;
 713
 714                         search_sz = sizeof(*search) + search_padded;
 715
 716                         search = alloca(search_sz);
 717                         memset(search, 0, search_sz);
 718                         search->type = ND_OPT_DNS_SEARCH;
 719                         search->len = search_len ? ((sizeof(*search) + search_padded) / 8) : 0;
 720                         search->lifetime = htonl(lifetime);
 721                         memcpy(search->name, search_domain, search_len);
 722                         memset(&search->name[search_len], 0, search_padded - search_len);
 723                 }
 724         }
 725
 726         iov[IOV_RA_DNS].iov_base = (char *)dns;
 727         iov[IOV_RA_DNS].iov_len = dns_sz;
 728         iov[IOV_RA_SEARCH].iov_base = (char *)search;
 729         iov[IOV_RA_SEARCH].iov_len = search_sz;
 730
 731         if (iface->pref64_length) {
 732                 /* RFC 8781 § 4.1 rounding up lifetime to multiple of 8 */
 733                 uint16_t pref64_lifetime = lifetime < (UINT16_MAX - 7) ? lifetime + 7 : UINT16_MAX;
 734                 uint8_t prefix_length_code;
 735                 uint32_t mask_a1, mask_a2;
 736
 737                 switch (iface->pref64_length) {
 738                 case 96:
 739                         prefix_length_code = 0;
 740                         mask_a1 = 0xffffffff;
 741                         mask_a2 = 0xffffffff;
 742                         break;
 743                 case 64:
 744                         prefix_length_code = 1;
 745                         mask_a1 = 0xffffffff;
 746                         mask_a2 = 0x00000000;
 747                         break;
 748                 case 56:
 749                         prefix_length_code = 2;
 750                         mask_a1 = 0xffffff00;
 751                         mask_a2 = 0x00000000;
 752                         break;
 753                 case 48:
 754                         prefix_length_code = 3;
 755                         mask_a1 = 0xffff0000;
 756                         mask_a2 = 0x00000000;
 757                         break;
 758                 case 40:
 759                         prefix_length_code = 4;
 760                         mask_a1 = 0xff000000;
 761                         mask_a2 = 0x00000000;
 762                         break;
 763                 case 32:
 764                         prefix_length_code = 5;
 765                         mask_a1 = 0x00000000;
 766                         mask_a2 = 0x00000000;
 767                         break;
 768                 default:
 769                         syslog(LOG_WARNING, "Invalid PREF64 prefix size (%d), "
 770                                         "ignoring ra_pref64 option!", iface->pref64_length);
 771                         goto pref64_out;
 772                         break;
 773                 }
 774
 775                 pref64_sz = sizeof(*pref64);
 776                 pref64 = alloca(pref64_sz);
 777                 memset(pref64, 0, pref64_sz);
 778                 pref64->type = ND_OPT_PREF64;
 779                 pref64->len = 2;
 780                 pref64->lifetime_plc = htons((0xfff8 & pref64_lifetime) |
 781                                                 (0x7 & prefix_length_code));
 782                 pref64->addr[0] = iface->pref64_addr.s6_addr32[0];
 783                 pref64->addr[1] = iface->pref64_addr.s6_addr32[1] & htonl(mask_a1);
 784                 pref64->addr[2] = iface->pref64_addr.s6_addr32[2] & htonl(mask_a2);
 785         }
 786 pref64_out:
 787         iov[IOV_RA_PREF64].iov_base = (char *)pref64;
 788         iov[IOV_RA_PREF64].iov_len = pref64_sz;
 789
 790         /*
 791          * RFC7084 § 4.3 :
 792          *    L-3:   An IPv6 CE router MUST advertise itself as a router for the
 793          *           delegated prefix(es) (and ULA prefix if configured to provide
 794          *           ULA addressing) using the "Route Information Option" specified
 795          *           in Section 2.3 of [RFC4191].  This advertisement is
 796          *           independent of having or not having IPv6 connectivity on the
 797          *           WAN interface.
 798          */
 799
 800         for (ssize_t i = 0; i < valid_addr_cnt; ++i) {
 801                 struct odhcpd_ipaddr *addr = &addrs[i];
 802                 struct nd_opt_route_info *tmp;
 803                 uint32_t valid_lt;
 804
 805                 if (addr->dprefix >= 64 || addr->dprefix == 0 || addr->valid_lt <= (uint32_t)now) {
 806                         syslog(LOG_INFO, "Address %s (dprefix %d, valid-lifetime %u) not suitable as RA route on %s",
 807                                 inet_ntop(AF_INET6, &addr->addr.in6, buf, sizeof(buf)),
 808                                 addr->dprefix, addr->valid_lt, iface->name);
 809
 810                         continue; /* Address not suitable */
 811                 }
 812
 813                 if (ADDR_MATCH_PIO_FILTER(addr, iface)) {
 814                         syslog(LOG_INFO, "Address %s filtered out as RA route on %s",
 815                                         inet_ntop(AF_INET6, &addr->addr.in6, buf, sizeof(buf)),
 816                                         iface->name);
 817                         continue; /* PIO filtered out of this RA */
 818                 }
 819
 820                 if (addr->dprefix > 32) {
 821                         addr->addr.in6.s6_addr32[1] &= htonl(~((1U << (64 - addr->dprefix)) - 1));
 822                 } else if (addr->dprefix <= 32) {
 823                         addr->addr.in6.s6_addr32[0] &= htonl(~((1U << (32 - addr->dprefix)) - 1));
 824                         addr->addr.in6.s6_addr32[1] = 0;
 825                 }
 826
 827                 tmp = realloc(routes, sizeof(*routes) * (routes_cnt + 1));
 828                 if (!tmp) {
 829                         syslog(LOG_ERR, "Realloc failed for RA route option on %s", iface->name);
 830                         continue;
 831                 }
 832
 833                 routes = tmp;
 834
 835                 memset(&routes[routes_cnt], 0, sizeof(*routes));
 836                 routes[routes_cnt].type = ND_OPT_ROUTE_INFO;
 837                 routes[routes_cnt].len = sizeof(*routes) / 8;
 838                 routes[routes_cnt].prefix = addr->dprefix;
 839                 routes[routes_cnt].flags = 0;
 840                 if (iface->route_preference < 0)
 841                         routes[routes_cnt].flags |= ND_RA_PREF_LOW;
 842                 else if (iface->route_preference > 0)
 843                         routes[routes_cnt].flags |= ND_RA_PREF_HIGH;
 844
 845                 valid_lt = TIME_LEFT(addr->valid_lt, now);
 846                 routes[routes_cnt].lifetime = htonl(valid_lt < lifetime ? valid_lt : lifetime);
 847                 routes[routes_cnt].addr[0] = addr->addr.in6.s6_addr32[0];
 848                 routes[routes_cnt].addr[1] = addr->addr.in6.s6_addr32[1];
 849                 routes[routes_cnt].addr[2] = 0;
 850                 routes[routes_cnt].addr[3] = 0;
 851
 852                 ++routes_cnt;
 853         }
 854
 855         iov[IOV_RA_ROUTES].iov_base = (char *)routes;
 856         iov[IOV_RA_ROUTES].iov_len = routes_cnt * sizeof(*routes);
 857
 858         memset(&adv_interval, 0, sizeof(adv_interval));
 859         adv_interval.nd_opt_adv_interval_type = ND_OPT_RTR_ADV_INTERVAL;
 860         adv_interval.nd_opt_adv_interval_len = 1;
 861         adv_interval.nd_opt_adv_interval_ival = htonl(maxival*1000);
 862
 863         iov[IOV_RA_ADV_INTERVAL].iov_base = (char *)&adv_interval;
 864         iov[IOV_RA_ADV_INTERVAL].iov_len = adv_interval.nd_opt_adv_interval_len * 8;
 865
 866         memset(&dest, 0, sizeof(dest));
 867         dest.sin6_family = AF_INET6;
 868
 869         if (from && !IN6_IS_ADDR_UNSPECIFIED(from))
 870                 dest.sin6_addr = *from;
 871         else
 872                 inet_pton(AF_INET6, ALL_IPV6_NODES, &dest.sin6_addr);
 873
 874         syslog(LOG_NOTICE, "Sending a RA on %s", iface->name);
 875
 876         if (odhcpd_send(iface->router_event.uloop.fd, &dest, iov, ARRAY_SIZE(iov), iface) > 0)
 877                 iface->ra_sent++;
 878
 879 out:
 880         free(pfxs);
 881         free(routes);
 882
 883         return msecs;
 884 }
 885
 886
 887 static void trigger_router_advert(struct uloop_timeout *event)
 888 {
 889         struct interface *iface = container_of(event, struct interface, timer_rs);
 890         int msecs = send_router_advert(iface, NULL);
 891
 892         /* Rearm timer if not shut down */
 893         if (event->cb)
 894                 uloop_timeout_set(event, msecs);
 895 }
 896
 897
 898 /* Event handler for incoming ICMPv6 packets */
 899 static void handle_icmpv6(void *addr, void *data, size_t len,
 900                 struct interface *iface, _unused void *dest)
 901 {
 902         struct icmp6_hdr *hdr = data;
 903         struct sockaddr_in6 *from = addr;
 904
 905         if (!router_icmpv6_valid(addr, data, len))
 906                 return;
 907
 908         if ((iface->ra == MODE_SERVER && !iface->master)) { /* Server mode */
 909                 if (hdr->icmp6_type == ND_ROUTER_SOLICIT)
 910                         send_router_advert(iface, &from->sin6_addr);
 911         } else if (iface->ra == MODE_RELAY) { /* Relay mode */
 912                 if (hdr->icmp6_type == ND_ROUTER_SOLICIT && !iface->master) {
 913                         struct interface *c;
 914
 915                         avl_for_each_element(&interfaces, c, avl) {
 916                                 if (!c->master || c->ra != MODE_RELAY)
 917                                         continue;
 918
 919                                 forward_router_solicitation(c);
 920                         }
 921                 } else if (hdr->icmp6_type == ND_ROUTER_ADVERT && iface->master)
 922                         forward_router_advertisement(iface, data, len);
 923         }
 924 }
 925
 926
 927 /* Forward router solicitation */
 928 static void forward_router_solicitation(const struct interface *iface)
 929 {
 930         struct icmp6_hdr rs = {ND_ROUTER_SOLICIT, 0, 0, {{0}}};
 931         struct iovec iov = {&rs, sizeof(rs)};
 932         struct sockaddr_in6 all_routers;
 933
 934         if (!iface)
 935                 return;
 936
 937         memset(&all_routers, 0, sizeof(all_routers));
 938         all_routers.sin6_family = AF_INET6;
 939         inet_pton(AF_INET6, ALL_IPV6_ROUTERS, &all_routers.sin6_addr);
 940         all_routers.sin6_scope_id = iface->ifindex;
 941
 942         syslog(LOG_NOTICE, "Sending RS to %s", iface->name);
 943         odhcpd_send(iface->router_event.uloop.fd, &all_routers, &iov, 1, iface);
 944 }
 945
 946
 947 /* Handler for incoming router solicitations on slave interfaces */
 948 static void forward_router_advertisement(const struct interface *iface, uint8_t *data, size_t len)
 949 {
 950         struct nd_router_advert *adv = (struct nd_router_advert *)data;
 951         struct sockaddr_in6 all_nodes;
 952         struct icmpv6_opt *opt;
 953         struct interface *c;
 954         struct iovec iov = { .iov_base = data, .iov_len = len };
 955         /* Rewrite options */
 956         uint8_t *end = data + len;
 957         uint8_t *mac_ptr = NULL;
 958         struct in6_addr *dns_ptr = NULL;
 959         size_t dns_count = 0;
 960
 961         icmpv6_for_each_option(opt, &adv[1], end) {
 962                 if (opt->type == ND_OPT_SOURCE_LINKADDR) {
 963                         /* Store address of source MAC-address */
 964                         mac_ptr = opt->data;
 965                 } else if (opt->type == ND_OPT_RECURSIVE_DNS && opt->len > 1) {
 966                         /* Check if we have to rewrite DNS */
 967                         dns_ptr = (struct in6_addr*)&opt->data[6];
 968                         dns_count = (opt->len - 1) / 2;
 969                 }
 970         }
 971
 972         syslog(LOG_NOTICE, "Got a RA on %s", iface->name);
 973
 974         /* Indicate a proxy, however we don't follow the rest of RFC 4389 yet */
 975         adv->nd_ra_flags_reserved |= ND_RA_FLAG_PROXY;
 976
 977         /* Forward advertisement to all slave interfaces */
 978         memset(&all_nodes, 0, sizeof(all_nodes));
 979         all_nodes.sin6_family = AF_INET6;
 980         inet_pton(AF_INET6, ALL_IPV6_NODES, &all_nodes.sin6_addr);
 981
 982         avl_for_each_element(&interfaces, c, avl) {
 983                 if (c->ra != MODE_RELAY || c->master)
 984                         continue;
 985
 986                 /* Fixup source hardware address option */
 987                 if (mac_ptr)
 988                         odhcpd_get_mac(c, mac_ptr);
 989
 990                 /* If we have to rewrite DNS entries */
 991                 if (c->always_rewrite_dns && dns_ptr && dns_count > 0) {
 992                         const struct in6_addr *rewrite = c->dns;
 993                         struct in6_addr addr;
 994                         size_t rewrite_cnt = c->dns_cnt;
 995
 996                         if (rewrite_cnt == 0) {
 997                                 if (odhcpd_get_interface_dns_addr(c, &addr))
 998                                         continue; /* Unable to comply */
 999
1000                                 rewrite = &addr;
1001                                 rewrite_cnt = 1;
1002                         }
1003
1004                         /* Copy over any other addresses */
1005                         for (size_t i = 0; i < dns_count; ++i) {
1006                                 size_t j = (i < rewrite_cnt) ? i : rewrite_cnt - 1;
1007                                 dns_ptr[i] = rewrite[j];
1008                         }
1009                 }
1010
1011                 syslog(LOG_NOTICE, "Forward a RA on %s", c->name);
1012
1013                 odhcpd_send(c->router_event.uloop.fd, &all_nodes, &iov, 1, c);
1014         }
1015 }