src/router.c

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