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 = 0, .valid = 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 minvalid,
 338                              uint32_t *maxival)
 339 {
 340         uint32_t minival = iface->ra_mininterval;
 341         int msecs;
 342
 343         *maxival = iface->ra_maxinterval;
 344
 345         if (*maxival > minvalid/3)
 346                 *maxival = minvalid/3;
 347
 348         if (*maxival > MaxRtrAdvInterval)
 349                 *maxival = MaxRtrAdvInterval;
 350         else if (*maxival < 4)
 351                 *maxival = 4;
 352
 353         if (minival < MinRtrAdvInterval)
 354                 minival = MinRtrAdvInterval;
 355         else if (minival > (*maxival * 3)/4)
 356                 minival = (*maxival >= 9 ? *maxival/3 : *maxival);
 357
 358         odhcpd_urandom(&msecs, sizeof(msecs));
 359         msecs = (labs(msecs) % ((*maxival != minival) ? (*maxival - minival)*1000 : 500)) +
 360                         minival*1000;
 361
 362         /* RFC 2461 6.2.4 For the first MAX_INITIAL_RTR_ADVERTISEMENTS advertisements */
 363         /* if the timer is bigger than MAX_INITIAL_RTR_ADVERT_INTERVAL it should be   */
 364         /* set to MAX_INITIAL_RTR_ADVERT_INTERVAL                                     */
 365         /* Off by one as an initial interval timer has already expired                */
 366         if ((iface->ra_sent + 1) < MaxInitialRtAdvs && msecs > MaxInitialRtrAdvInterval*1000)
 367                 msecs = MaxInitialRtrAdvInterval*1000;
 368
 369         return msecs;
 370 }
 371
 372 static uint32_t calc_ra_lifetime(struct interface *iface, uint32_t maxival)
 373 {
 374         uint32_t lifetime = 3*maxival;
 375
 376         if (iface->ra_lifetime >= 0) {
 377                 lifetime = iface->ra_lifetime;
 378                 if (lifetime > 0 && lifetime < maxival)
 379                         lifetime = maxival;
 380                 else if (lifetime > 9000)
 381                         lifetime = 9000;
 382         }
 383
 384         return lifetime;
 385 }
 386
 387 enum {
 388         IOV_RA_ADV=0,
 389         IOV_RA_PFXS,
 390         IOV_RA_ROUTES,
 391         IOV_RA_DNS,
 392         IOV_RA_SEARCH,
 393         IOV_RA_ADV_INTERVAL,
 394         IOV_RA_TOTAL,
 395 };
 396
 397 struct adv_msg {
 398         struct nd_router_advert h;
 399         struct icmpv6_opt lladdr;
 400         struct nd_opt_mtu mtu;
 401 };
 402
 403 struct nd_opt_dns_server {
 404         uint8_t type;
 405         uint8_t len;
 406         uint8_t pad;
 407         uint8_t pad2;
 408         uint32_t lifetime;
 409         struct in6_addr addr[];
 410 };
 411
 412 struct nd_opt_search_list {
 413         uint8_t type;
 414         uint8_t len;
 415         uint8_t pad;
 416         uint8_t pad2;
 417         uint32_t lifetime;
 418         uint8_t name[];
 419 };
 420
 421 struct nd_opt_route_info {
 422         uint8_t type;
 423         uint8_t len;
 424         uint8_t prefix;
 425         uint8_t flags;
 426         uint32_t lifetime;
 427         uint32_t addr[4];
 428 };
 429
 430 /* Router Advert server mode */
 431 static int send_router_advert(struct interface *iface, const struct in6_addr *from)
 432 {
 433         time_t now = odhcpd_time();
 434         struct odhcpd_ipaddr *addrs = NULL;
 435         struct adv_msg adv;
 436         struct nd_opt_prefix_info *pfxs = NULL;
 437         struct nd_opt_dns_server *dns = NULL;
 438         struct nd_opt_search_list *search = NULL;
 439         struct nd_opt_route_info *routes = NULL;
 440         struct nd_opt_adv_interval adv_interval;
 441         struct iovec iov[IOV_RA_TOTAL];
 442         struct sockaddr_in6 dest;
 443         size_t dns_sz = 0, search_sz = 0, pfxs_cnt = 0, routes_cnt = 0;
 444         ssize_t addr_cnt = 0;
 445         uint32_t minvalid = UINT32_MAX, maxival, lifetime;
 446         int msecs, mtu = iface->ra_mtu, hlim = iface->ra_hoplimit;
 447         bool default_route = false;
 448         bool valid_prefix = false;
 449         char buf[INET6_ADDRSTRLEN];
 450
 451         memset(&adv, 0, sizeof(adv));
 452         adv.h.nd_ra_type = ND_ROUTER_ADVERT;
 453
 454         if (hlim == 0)
 455                 hlim = odhcpd_get_interface_config(iface->ifname, "hop_limit");
 456
 457         if (hlim > 0)
 458                 adv.h.nd_ra_curhoplimit = hlim;
 459
 460         adv.h.nd_ra_flags_reserved = iface->ra_flags;
 461
 462         if (iface->route_preference < 0)
 463                 adv.h.nd_ra_flags_reserved |= ND_RA_PREF_LOW;
 464         else if (iface->route_preference > 0)
 465                 adv.h.nd_ra_flags_reserved |= ND_RA_PREF_HIGH;
 466
 467         adv.h.nd_ra_reachable = htonl(iface->ra_reachabletime);
 468         adv.h.nd_ra_retransmit = htonl(iface->ra_retranstime);
 469
 470         adv.lladdr.type = ND_OPT_SOURCE_LINKADDR;
 471         adv.lladdr.len = 1;
 472         odhcpd_get_mac(iface, adv.lladdr.data);
 473
 474         adv.mtu.nd_opt_mtu_type = ND_OPT_MTU;
 475         adv.mtu.nd_opt_mtu_len = 1;
 476
 477         if (mtu == 0)
 478                 mtu = odhcpd_get_interface_config(iface->ifname, "mtu");
 479
 480         if (mtu < 1280)
 481                 mtu = 1280;
 482
 483         adv.mtu.nd_opt_mtu_mtu = htonl(mtu);
 484
 485         iov[IOV_RA_ADV].iov_base = (char *)&adv;
 486         iov[IOV_RA_ADV].iov_len = sizeof(adv);
 487
 488         /* If not shutdown */
 489         if (iface->timer_rs.cb) {
 490                 size_t size = sizeof(*addrs) * iface->addr6_len;
 491
 492                 addrs = alloca(size);
 493                 memcpy(addrs, iface->addr6, size);
 494
 495                 addr_cnt = iface->addr6_len;
 496
 497                 /* Check default route */
 498                 if (iface->default_router) {
 499                         default_route = true;
 500
 501                         if (iface->default_router > 1)
 502                                 valid_prefix = true;
 503                 } else if (parse_routes(addrs, addr_cnt))
 504                         default_route = true;
 505         }
 506
 507         /* Construct Prefix Information options */
 508         for (ssize_t i = 0; i < addr_cnt; ++i) {
 509                 struct odhcpd_ipaddr *addr = &addrs[i];
 510                 struct nd_opt_prefix_info *p = NULL;
 511                 uint32_t preferred = 0;
 512                 uint32_t valid = 0;
 513
 514                 if (addr->prefix > 96 || addr->valid <= (uint32_t)now) {
 515                         syslog(LOG_INFO, "Address %s (prefix %d, valid %u) not suitable as RA prefix on %s",
 516                                 inet_ntop(AF_INET6, &addr->addr.in6, buf, sizeof(buf)), addr->prefix,
 517                                 addr->valid, iface->name);
 518                         continue;
 519                 }
 520
 521                 if (odhcpd_bmemcmp(&addr->addr, &iface->pio_filter_addr,
 522                                    iface->pio_filter_length) != 0 ||
 523                     addr->prefix < iface->pio_filter_length) {
 524                         syslog(LOG_INFO, "Address %s filtered out as RA prefix on %s",
 525                                inet_ntop(AF_INET6, &addr->addr.in6, buf, sizeof(buf)),
 526                                iface->name);
 527                         continue; /* PIO filtered out of this RA */
 528                 }
 529
 530                 for (size_t i = 0; i < pfxs_cnt; ++i) {
 531                         if (addr->prefix == pfxs[i].nd_opt_pi_prefix_len &&
 532                                         !odhcpd_bmemcmp(&pfxs[i].nd_opt_pi_prefix,
 533                                         &addr->addr.in6, addr->prefix))
 534                                 p = &pfxs[i];
 535                 }
 536
 537                 if (!p) {
 538                         struct nd_opt_prefix_info *tmp;
 539
 540                         tmp = realloc(pfxs, sizeof(*pfxs) * (pfxs_cnt + 1));
 541                         if (!tmp) {
 542                                 syslog(LOG_ERR, "Realloc failed for RA prefix option on %s", iface->name);
 543                                 continue;
 544                         }
 545
 546                         pfxs = tmp;
 547                         p = &pfxs[pfxs_cnt++];
 548                         memset(p, 0, sizeof(*p));
 549                 }
 550
 551                 if (addr->preferred > (uint32_t)now) {
 552                         preferred = TIME_LEFT(addr->preferred, now);
 553
 554                         if (iface->ra_useleasetime &&
 555                             preferred > iface->dhcp_leasetime)
 556                                 preferred = iface->dhcp_leasetime;
 557                 }
 558
 559                 valid = TIME_LEFT(addr->valid, now);
 560                 if (iface->ra_useleasetime && valid > iface->dhcp_leasetime)
 561                         valid = iface->dhcp_leasetime;
 562
 563                 if (minvalid > valid)
 564                         minvalid = valid;
 565
 566                 if (!IN6_IS_ADDR_ULA(&addr->addr.in6) || iface->default_router)
 567                         valid_prefix = true;
 568
 569                 odhcpd_bmemcpy(&p->nd_opt_pi_prefix, &addr->addr.in6,
 570                                 (iface->ra_advrouter) ? 128 : addr->prefix);
 571                 p->nd_opt_pi_type = ND_OPT_PREFIX_INFORMATION;
 572                 p->nd_opt_pi_len = 4;
 573                 p->nd_opt_pi_prefix_len = (addr->prefix < 64) ? 64 : addr->prefix;
 574                 p->nd_opt_pi_flags_reserved = 0;
 575                 if (!iface->ra_not_onlink)
 576                         p->nd_opt_pi_flags_reserved |= ND_OPT_PI_FLAG_ONLINK;
 577                 if (iface->ra_slaac && addr->prefix <= 64)
 578                         p->nd_opt_pi_flags_reserved |= ND_OPT_PI_FLAG_AUTO;
 579                 if (iface->ra_advrouter)
 580                         p->nd_opt_pi_flags_reserved |= ND_OPT_PI_FLAG_RADDR;
 581                 p->nd_opt_pi_preferred_time = htonl(preferred);
 582                 p->nd_opt_pi_valid_time = htonl(valid);
 583         }
 584
 585         iov[IOV_RA_PFXS].iov_base = (char *)pfxs;
 586         iov[IOV_RA_PFXS].iov_len = pfxs_cnt * sizeof(*pfxs);
 587
 588         /* Calculate periodic transmit */
 589         msecs = calc_adv_interval(iface, minvalid, &maxival);
 590         lifetime = calc_ra_lifetime(iface, maxival);
 591
 592         if (default_route) {
 593                 if (!valid_prefix) {
 594                         syslog(LOG_WARNING, "A default route is present but there is no public prefix "
 595                                         "on %s thus we don't announce a default route!", iface->name);
 596                         adv.h.nd_ra_router_lifetime = 0;
 597                 } else
 598                         adv.h.nd_ra_router_lifetime = htons(lifetime < UINT16_MAX ? lifetime : UINT16_MAX);
 599
 600         } else
 601                 adv.h.nd_ra_router_lifetime = 0;
 602
 603         syslog(LOG_DEBUG, "Using a RA lifetime of %d seconds on %s", ntohs(adv.h.nd_ra_router_lifetime), iface->name);
 604
 605         /* DNS options */
 606         if (iface->ra_dns) {
 607                 struct in6_addr dns_pref, *dns_addr = NULL;
 608                 size_t dns_cnt = 0, search_len = iface->search_len;
 609                 uint8_t *search_domain = iface->search;
 610                 uint8_t search_buf[256];
 611
 612                 /* DNS Recursive DNS */
 613                 if (iface->dns_cnt > 0) {
 614                         dns_addr = iface->dns;
 615                         dns_cnt = iface->dns_cnt;
 616                 } else if (!odhcpd_get_interface_dns_addr(iface, &dns_pref)) {
 617                         dns_addr = &dns_pref;
 618                         dns_cnt = 1;
 619                 }
 620
 621                 if (dns_cnt) {
 622                         dns_sz = sizeof(*dns) + sizeof(struct in6_addr)*dns_cnt;
 623
 624                         dns = alloca(dns_sz);
 625                         memset(dns, 0, dns_sz);
 626                         dns->type = ND_OPT_RECURSIVE_DNS;
 627                         dns->len = 1 + (2 * dns_cnt);
 628                         dns->lifetime = htonl(lifetime);
 629                         memcpy(dns->addr, dns_addr, sizeof(struct in6_addr)*dns_cnt);
 630                 }
 631
 632                 /* DNS Search options */
 633                 if (!search_domain && !res_init() && _res.dnsrch[0] && _res.dnsrch[0][0]) {
 634                         int len = dn_comp(_res.dnsrch[0], search_buf,
 635                                         sizeof(search_buf), NULL, NULL);
 636                         if (len > 0) {
 637                                 search_domain = search_buf;
 638                                 search_len = len;
 639                         }
 640                 }
 641
 642                 if (search_len > 0) {
 643                         size_t search_padded = ((search_len + 7) & (~7)) + 8;
 644
 645                         search_sz = sizeof(*search) + search_padded;
 646
 647                         search = alloca(search_sz);
 648                         memset(search, 0, search_sz);
 649                         search->type = ND_OPT_DNS_SEARCH;
 650                         search->len = search_len ? ((sizeof(*search) + search_padded) / 8) : 0;
 651                         search->lifetime = htonl(lifetime);
 652                         memcpy(search->name, search_domain, search_len);
 653                         memset(&search->name[search_len], 0, search_padded - search_len);
 654                 }
 655         }
 656
 657         iov[IOV_RA_DNS].iov_base = (char *)dns;
 658         iov[IOV_RA_DNS].iov_len = dns_sz;
 659         iov[IOV_RA_SEARCH].iov_base = (char *)search;
 660         iov[IOV_RA_SEARCH].iov_len = search_sz;
 661
 662         /*
 663          * RFC7084 § 4.3 :
 664          *    L-3:   An IPv6 CE router MUST advertise itself as a router for the
 665          *           delegated prefix(es) (and ULA prefix if configured to provide
 666          *           ULA addressing) using the "Route Information Option" specified
 667          *           in Section 2.3 of [RFC4191].  This advertisement is
 668          *           independent of having or not having IPv6 connectivity on the
 669          *           WAN interface.
 670          */
 671
 672         for (ssize_t i = 0; i < addr_cnt; ++i) {
 673                 struct odhcpd_ipaddr *addr = &addrs[i];
 674                 struct nd_opt_route_info *tmp;
 675                 uint32_t valid;
 676
 677                 if (addr->dprefix >= 64 || addr->dprefix == 0 || addr->valid <= (uint32_t)now) {
 678                         syslog(LOG_INFO, "Address %s (dprefix %d, valid %u) not suitable as RA route on %s",
 679                                 inet_ntop(AF_INET6, &addr->addr.in6, buf, sizeof(buf)),
 680                                 addr->dprefix, addr->valid, iface->name);
 681
 682                         continue; /* Address not suitable */
 683                 }
 684
 685                 if (odhcpd_bmemcmp(&addr->addr, &iface->pio_filter_addr,
 686                                 iface->pio_filter_length) != 0 ||
 687                                 addr->prefix < iface->pio_filter_length) {
 688                         syslog(LOG_INFO, "Address %s filtered out as RA route on %s",
 689                                inet_ntop(AF_INET6, &addr->addr.in6, buf, sizeof(buf)),
 690                                iface->name);
 691                         continue; /* PIO filtered out of this RA */
 692                 }
 693
 694                 if (addr->dprefix > 32) {
 695                         addr->addr.in6.s6_addr32[1] &= htonl(~((1U << (64 - addr->dprefix)) - 1));
 696                 } else if (addr->dprefix <= 32) {
 697                         addr->addr.in6.s6_addr32[0] &= htonl(~((1U << (32 - addr->dprefix)) - 1));
 698                         addr->addr.in6.s6_addr32[1] = 0;
 699                 }
 700
 701                 tmp = realloc(routes, sizeof(*routes) * (routes_cnt + 1));
 702                 if (!tmp) {
 703                         syslog(LOG_ERR, "Realloc failed for RA route option on %s", iface->name);
 704                         continue;
 705                 }
 706
 707                 routes = tmp;
 708
 709                 memset(&routes[routes_cnt], 0, sizeof(*routes));
 710                 routes[routes_cnt].type = ND_OPT_ROUTE_INFO;
 711                 routes[routes_cnt].len = sizeof(*routes) / 8;
 712                 routes[routes_cnt].prefix = addr->dprefix;
 713                 routes[routes_cnt].flags = 0;
 714                 if (iface->route_preference < 0)
 715                         routes[routes_cnt].flags |= ND_RA_PREF_LOW;
 716                 else if (iface->route_preference > 0)
 717                         routes[routes_cnt].flags |= ND_RA_PREF_HIGH;
 718
 719                 valid = TIME_LEFT(addr->valid, now);
 720                 routes[routes_cnt].lifetime = htonl(valid < lifetime ? valid : lifetime);
 721                 routes[routes_cnt].addr[0] = addr->addr.in6.s6_addr32[0];
 722                 routes[routes_cnt].addr[1] = addr->addr.in6.s6_addr32[1];
 723                 routes[routes_cnt].addr[2] = 0;
 724                 routes[routes_cnt].addr[3] = 0;
 725
 726                 ++routes_cnt;
 727         }
 728
 729         iov[IOV_RA_ROUTES].iov_base = (char *)routes;
 730         iov[IOV_RA_ROUTES].iov_len = routes_cnt * sizeof(*routes);
 731
 732         memset(&adv_interval, 0, sizeof(adv_interval));
 733         adv_interval.nd_opt_adv_interval_type = ND_OPT_RTR_ADV_INTERVAL;
 734         adv_interval.nd_opt_adv_interval_len = 1;
 735         adv_interval.nd_opt_adv_interval_ival = htonl(maxival*1000);
 736
 737         iov[IOV_RA_ADV_INTERVAL].iov_base = (char *)&adv_interval;
 738         iov[IOV_RA_ADV_INTERVAL].iov_len = adv_interval.nd_opt_adv_interval_len * 8;
 739
 740         memset(&dest, 0, sizeof(dest));
 741         dest.sin6_family = AF_INET6;
 742
 743         if (from && !IN6_IS_ADDR_UNSPECIFIED(from))
 744                 dest.sin6_addr = *from;
 745         else
 746                 inet_pton(AF_INET6, ALL_IPV6_NODES, &dest.sin6_addr);
 747
 748         syslog(LOG_NOTICE, "Sending a RA on %s", iface->name);
 749
 750         if (odhcpd_send(iface->router_event.uloop.fd, &dest, iov, ARRAY_SIZE(iov), iface) > 0)
 751                 iface->ra_sent++;
 752
 753         free(pfxs);
 754         free(routes);
 755
 756         return msecs;
 757 }
 758
 759
 760 static void trigger_router_advert(struct uloop_timeout *event)
 761 {
 762         struct interface *iface = container_of(event, struct interface, timer_rs);
 763         int msecs = send_router_advert(iface, NULL);
 764
 765         /* Rearm timer if not shut down */
 766         if (event->cb)
 767                 uloop_timeout_set(event, msecs);
 768 }
 769
 770
 771 /* Event handler for incoming ICMPv6 packets */
 772 static void handle_icmpv6(void *addr, void *data, size_t len,
 773                 struct interface *iface, _unused void *dest)
 774 {
 775         struct icmp6_hdr *hdr = data;
 776         struct sockaddr_in6 *from = addr;
 777
 778         if (!router_icmpv6_valid(addr, data, len))
 779                 return;
 780
 781         if ((iface->ra == MODE_SERVER && !iface->master)) { /* Server mode */
 782                 if (hdr->icmp6_type == ND_ROUTER_SOLICIT)
 783                         send_router_advert(iface, &from->sin6_addr);
 784         } else if (iface->ra == MODE_RELAY) { /* Relay mode */
 785                 if (hdr->icmp6_type == ND_ROUTER_SOLICIT && !iface->master) {
 786                         struct interface *c;
 787
 788                         avl_for_each_element(&interfaces, c, avl) {
 789                                 if (!c->master || c->ra != MODE_RELAY)
 790                                         continue;
 791
 792                                 forward_router_solicitation(c);
 793                         }
 794                 } else if (hdr->icmp6_type == ND_ROUTER_ADVERT && iface->master)
 795                         forward_router_advertisement(iface, data, len);
 796         }
 797 }
 798
 799
 800 /* Forward router solicitation */
 801 static void forward_router_solicitation(const struct interface *iface)
 802 {
 803         struct icmp6_hdr rs = {ND_ROUTER_SOLICIT, 0, 0, {{0}}};
 804         struct iovec iov = {&rs, sizeof(rs)};
 805         struct sockaddr_in6 all_routers;
 806
 807         if (!iface)
 808                 return;
 809
 810         memset(&all_routers, 0, sizeof(all_routers));
 811         all_routers.sin6_family = AF_INET6;
 812         inet_pton(AF_INET6, ALL_IPV6_ROUTERS, &all_routers.sin6_addr);
 813         all_routers.sin6_scope_id = iface->ifindex;
 814
 815         syslog(LOG_NOTICE, "Sending RS to %s", iface->name);
 816         odhcpd_send(iface->router_event.uloop.fd, &all_routers, &iov, 1, iface);
 817 }
 818
 819
 820 /* Handler for incoming router solicitations on slave interfaces */
 821 static void forward_router_advertisement(const struct interface *iface, uint8_t *data, size_t len)
 822 {
 823         struct nd_router_advert *adv = (struct nd_router_advert *)data;
 824         struct sockaddr_in6 all_nodes;
 825         struct icmpv6_opt *opt;
 826         struct interface *c;
 827         struct iovec iov = { .iov_base = data, .iov_len = len };
 828         /* Rewrite options */
 829         uint8_t *end = data + len;
 830         uint8_t *mac_ptr = NULL;
 831         struct in6_addr *dns_ptr = NULL;
 832         size_t dns_count = 0;
 833
 834         icmpv6_for_each_option(opt, &adv[1], end) {
 835                 if (opt->type == ND_OPT_SOURCE_LINKADDR) {
 836                         /* Store address of source MAC-address */
 837                         mac_ptr = opt->data;
 838                 } else if (opt->type == ND_OPT_RECURSIVE_DNS && opt->len > 1) {
 839                         /* Check if we have to rewrite DNS */
 840                         dns_ptr = (struct in6_addr*)&opt->data[6];
 841                         dns_count = (opt->len - 1) / 2;
 842                 }
 843         }
 844
 845         syslog(LOG_NOTICE, "Got a RA on %s", iface->name);
 846
 847         /* Indicate a proxy, however we don't follow the rest of RFC 4389 yet */
 848         adv->nd_ra_flags_reserved |= ND_RA_FLAG_PROXY;
 849
 850         /* Forward advertisement to all slave interfaces */
 851         memset(&all_nodes, 0, sizeof(all_nodes));
 852         all_nodes.sin6_family = AF_INET6;
 853         inet_pton(AF_INET6, ALL_IPV6_NODES, &all_nodes.sin6_addr);
 854
 855         avl_for_each_element(&interfaces, c, avl) {
 856                 if (c->ra != MODE_RELAY || c->master)
 857                         continue;
 858
 859                 /* Fixup source hardware address option */
 860                 if (mac_ptr)
 861                         odhcpd_get_mac(c, mac_ptr);
 862
 863                 /* If we have to rewrite DNS entries */
 864                 if (c->always_rewrite_dns && dns_ptr && dns_count > 0) {
 865                         const struct in6_addr *rewrite = c->dns;
 866                         struct in6_addr addr;
 867                         size_t rewrite_cnt = c->dns_cnt;
 868
 869                         if (rewrite_cnt == 0) {
 870                                 if (odhcpd_get_interface_dns_addr(c, &addr))
 871                                         continue; /* Unable to comply */
 872
 873                                 rewrite = &addr;
 874                                 rewrite_cnt = 1;
 875                         }
 876
 877                         /* Copy over any other addresses */
 878                         for (size_t i = 0; i < dns_count; ++i) {
 879                                 size_t j = (i < rewrite_cnt) ? i : rewrite_cnt - 1;
 880                                 dns_ptr[i] = rewrite[j];
 881                         }
 882                 }
 883
 884                 syslog(LOG_NOTICE, "Forward a RA on %s", c->name);
 885
 886                 odhcpd_send(c->router_event.uloop.fd, &all_nodes, &iov, 1, c);
 887         }
 888 }