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 odhcpd_event router_event = {.uloop = {.fd = -1}, .handle_dgram = handle_icmpv6, };
  42 static struct netevent_handler router_netevent_handler = { .cb = router_netevent_cb, };
  43
  44 static FILE *fp_route = NULL;
  45
  46
  47 #define TIME_LEFT(t1, now) ((t1) != UINT32_MAX ? (t1) - (now) : UINT32_MAX)
  48
  49 int router_init(void)
  50 {
  51         struct icmp6_filter filt;
  52         int ret = 0;
  53
  54         /* Open ICMPv6 socket */
  55         router_event.uloop.fd = socket(AF_INET6, SOCK_RAW | SOCK_CLOEXEC, IPPROTO_ICMPV6);
  56         if (router_event.uloop.fd < 0) {
  57                 syslog(LOG_ERR, "socket(AF_INET6): %m");
  58                 ret = -1;
  59                 goto out;
  60         }
  61
  62         /* Let the kernel compute our checksums */
  63         int val = 2;
  64         if (setsockopt(router_event.uloop.fd, IPPROTO_RAW, IPV6_CHECKSUM,
  65                                 &val, sizeof(val)) < 0) {
  66                 syslog(LOG_ERR, "setsockopt(IPV6_CHECKSUM): %m");
  67                 ret = -1;
  68                 goto out;
  69         }
  70
  71         /* This is required by RFC 4861 */
  72         val = 255;
  73         if (setsockopt(router_event.uloop.fd, IPPROTO_IPV6, IPV6_MULTICAST_HOPS,
  74                                 &val, sizeof(val)) < 0) {
  75                 syslog(LOG_ERR, "setsockopt(IPV6_MULTICAST_HOPS): %m");
  76                 ret = -1;
  77                 goto out;
  78         }
  79
  80         if (setsockopt(router_event.uloop.fd, IPPROTO_IPV6, IPV6_UNICAST_HOPS,
  81                                 &val, sizeof(val)) < 0) {
  82                 syslog(LOG_ERR, "setsockopt(IPV6_UNICAST_HOPS): %m");
  83                 ret = -1;
  84                 goto out;
  85         }
  86
  87         /* We need to know the source interface */
  88         val = 1;
  89         if (setsockopt(router_event.uloop.fd, IPPROTO_IPV6, IPV6_RECVPKTINFO,
  90                                 &val, sizeof(val)) < 0) {
  91                 syslog(LOG_ERR, "setsockopt(IPV6_RECVPKTINFO): %m");
  92                 ret = -1;
  93                 goto out;
  94         }
  95
  96         if (setsockopt(router_event.uloop.fd, IPPROTO_IPV6, IPV6_RECVHOPLIMIT,
  97                                 &val, sizeof(val)) < 0) {
  98                 syslog(LOG_ERR, "setsockopt(IPV6_RECVHOPLIMIT): %m");
  99                 ret = -1;
 100                 goto out;
 101         }
 102
 103         /* Don't loop back */
 104         val = 0;
 105         if (setsockopt(router_event.uloop.fd, IPPROTO_IPV6, IPV6_MULTICAST_LOOP,
 106                                 &val, sizeof(val)) < 0) {
 107                 syslog(LOG_ERR, "setsockopt(IPV6_MULTICAST_LOOP): %m");
 108                 ret = -1;
 109                 goto out;
 110         }
 111
 112         /* Filter ICMPv6 package types */
 113         ICMP6_FILTER_SETBLOCKALL(&filt);
 114         ICMP6_FILTER_SETPASS(ND_ROUTER_ADVERT, &filt);
 115         ICMP6_FILTER_SETPASS(ND_ROUTER_SOLICIT, &filt);
 116         if (setsockopt(router_event.uloop.fd, IPPROTO_ICMPV6, ICMP6_FILTER,
 117                                 &filt, sizeof(filt)) < 0) {
 118                 syslog(LOG_ERR, "setsockopt(ICMP6_FILTER): %m");
 119                 ret = -1;
 120                 goto out;
 121         }
 122
 123         if (!(fp_route = fopen("/proc/net/ipv6_route", "r"))) {
 124                 syslog(LOG_ERR, "fopen(/proc/net/ipv6_route): %m");
 125                 ret = -1;
 126                 goto out;
 127         }
 128
 129         if (netlink_add_netevent_handler(&router_netevent_handler) < 0) {
 130                 syslog(LOG_ERR, "Failed to add netevent handler");
 131                 ret = -1;
 132                 goto out;
 133         }
 134
 135         /* Register socket */
 136         odhcpd_register(&router_event);
 137 out:
 138         if (ret < 0) {
 139                 if (router_event.uloop.fd > 0) {
 140                         close(router_event.uloop.fd);
 141                         router_event.uloop.fd = -1;
 142                 }
 143
 144                 if (fp_route) {
 145                         fclose(fp_route);
 146                         fp_route = NULL;
 147                 }
 148         }
 149
 150         return ret;
 151 }
 152
 153
 154 int router_setup_interface(struct interface *iface, bool enable)
 155 {
 156         struct ipv6_mreq mreq;
 157         int ret = 0;
 158
 159         if (!fp_route || router_event.uloop.fd < 0) {
 160                 ret = -1;
 161                 goto out;
 162         }
 163
 164         uloop_timeout_cancel(&iface->timer_rs);
 165         iface->timer_rs.cb = NULL;
 166
 167         memset(&mreq, 0, sizeof(mreq));
 168         mreq.ipv6mr_interface = iface->ifindex;
 169         inet_pton(AF_INET6, ALL_IPV6_NODES, &mreq.ipv6mr_multiaddr);
 170         setsockopt(router_event.uloop.fd, IPPROTO_IPV6, IPV6_DROP_MEMBERSHIP,
 171                         &mreq, sizeof(mreq));
 172
 173         inet_pton(AF_INET6, ALL_IPV6_ROUTERS, &mreq.ipv6mr_multiaddr);
 174         setsockopt(router_event.uloop.fd, IPPROTO_IPV6, IPV6_DROP_MEMBERSHIP,
 175                         &mreq, sizeof(mreq));
 176
 177         if (!enable) {
 178                 if (iface->ra == MODE_SERVER || (iface->ra == MODE_RELAY && !iface->master))
 179                         trigger_router_advert(&iface->timer_rs);
 180         } else {
 181                 if (iface->ra == MODE_RELAY && iface->master) {
 182                         inet_pton(AF_INET6, ALL_IPV6_NODES, &mreq.ipv6mr_multiaddr);
 183                         forward_router_solicitation(iface);
 184                 } else if (iface->ra == MODE_SERVER && !iface->master) {
 185                         iface->timer_rs.cb = trigger_router_advert;
 186                         uloop_timeout_set(&iface->timer_rs, 1000);
 187                 }
 188
 189                 if (iface->ra == MODE_RELAY || (iface->ra == MODE_SERVER && !iface->master)) {
 190                         if (setsockopt(router_event.uloop.fd, IPPROTO_IPV6,
 191                                         IPV6_ADD_MEMBERSHIP, &mreq, sizeof(mreq)) < 0) {
 192                                 ret = -1;
 193                                 syslog(LOG_ERR, "setsockopt(IPV6_ADD_MEMBERSHIP): %m");
 194                         }
 195                 }
 196         }
 197 out:
 198         return ret;
 199 }
 200
 201
 202 static void router_netevent_cb(unsigned long event, struct netevent_handler_info *info)
 203 {
 204         struct interface *iface;
 205
 206         switch (event) {
 207         case NETEV_ROUTE6_ADD:
 208         case NETEV_ROUTE6_DEL:
 209                 if (info->rt.dst_len)
 210                         break;
 211
 212                 avl_for_each_element(&interfaces, iface, avl) {
 213                         if (iface->ra == MODE_SERVER && !iface->master)
 214                                 uloop_timeout_set(&iface->timer_rs, 1000);
 215                 }
 216                 break;
 217         case NETEV_ADDR6LIST_CHANGE:
 218                 iface = info->iface;
 219                 if (iface && iface->ra == MODE_SERVER && !iface->master)
 220                         uloop_timeout_set(&iface->timer_rs, 1000);
 221                 break;
 222         default:
 223                 break;
 224         }
 225 }
 226
 227
 228 static bool router_icmpv6_valid(struct sockaddr_in6 *source, uint8_t *data, size_t len)
 229 {
 230         struct icmp6_hdr *hdr = (struct icmp6_hdr *)data;
 231         struct icmpv6_opt *opt, *end = (struct icmpv6_opt*)&data[len];
 232
 233         /* Hoplimit is already checked in odhcpd_receive_packets */
 234         if (len < sizeof(*hdr) || hdr->icmp6_code)
 235                 return false;
 236
 237         switch (hdr->icmp6_type) {
 238         case ND_ROUTER_ADVERT:
 239                 if (!IN6_IS_ADDR_LINKLOCAL(&source->sin6_addr))
 240                         return false;
 241
 242                 opt = (struct icmpv6_opt *)((struct nd_router_advert *)data + 1);
 243                 break;
 244
 245         case ND_ROUTER_SOLICIT:
 246                 opt = (struct icmpv6_opt *)((struct nd_router_solicit *)data + 1);
 247                 break;
 248
 249         default:
 250                 return false;
 251         }
 252
 253         icmpv6_for_each_option(opt, opt, end)
 254                 if (opt->type == ND_OPT_SOURCE_LINKADDR &&
 255                                 IN6_IS_ADDR_UNSPECIFIED(&source->sin6_addr) &&
 256                                 hdr->icmp6_type == ND_ROUTER_SOLICIT)
 257                         return false;
 258
 259         /* Check all options parsed successfully */
 260         return opt == end;
 261 }
 262
 263
 264 /* Detect whether a default route exists, also find the source prefixes */
 265 static bool parse_routes(struct odhcpd_ipaddr *n, ssize_t len)
 266 {
 267         rewind(fp_route);
 268
 269         char line[512], ifname[16];
 270         bool found_default = false;
 271         struct odhcpd_ipaddr p = { .addr.in6 = IN6ADDR_ANY_INIT, .prefix = 0,
 272                                         .dprefix = 0, .preferred = 0, .valid = 0};
 273
 274         while (fgets(line, sizeof(line), fp_route)) {
 275                 uint32_t rflags;
 276                 if (sscanf(line, "00000000000000000000000000000000 00 "
 277                                 "%*s %*s %*s %*s %*s %*s %*s %15s", ifname) &&
 278                                 strcmp(ifname, "lo")) {
 279                         found_default = true;
 280                 } else if (sscanf(line, "%8" SCNx32 "%8" SCNx32 "%*8" SCNx32 "%*8" SCNx32 " %hhx %*s "
 281                                 "%*s 00000000000000000000000000000000 %*s %*s %*s %" SCNx32 " lo",
 282                                 &p.addr.in6.s6_addr32[0], &p.addr.in6.s6_addr32[1], &p.prefix, &rflags) &&
 283                                 p.prefix > 0 && (rflags & RTF_NONEXTHOP) && (rflags & RTF_REJECT)) {
 284                         // Find source prefixes by scanning through unreachable-routes
 285                         p.addr.in6.s6_addr32[0] = htonl(p.addr.in6.s6_addr32[0]);
 286                         p.addr.in6.s6_addr32[1] = htonl(p.addr.in6.s6_addr32[1]);
 287
 288                         for (ssize_t i = 0; i < len; ++i) {
 289                                 if (n[i].prefix <= 64 && n[i].prefix >= p.prefix &&
 290                                                 !odhcpd_bmemcmp(&p.addr.in6, &n[i].addr.in6, p.prefix)) {
 291                                         n[i].dprefix = p.prefix;
 292                                         break;
 293                                 }
 294                         }
 295                 }
 296         }
 297
 298         return found_default;
 299 }
 300
 301 static int calc_adv_interval(struct interface *iface, uint32_t minvalid,
 302                 uint32_t *maxival)
 303 {
 304         uint32_t minival = iface->ra_mininterval;
 305         int msecs;
 306
 307         *maxival = iface->ra_maxinterval;
 308
 309         if (*maxival > minvalid/3)
 310                 *maxival = minvalid/3;
 311
 312         if (*maxival > MaxRtrAdvInterval)
 313                 *maxival = MaxRtrAdvInterval;
 314         else if (*maxival < 4)
 315                 *maxival = 4;
 316
 317         if (minival < MinRtrAdvInterval)
 318                 minival = MinRtrAdvInterval;
 319         else if (minival > (*maxival * 3)/4)
 320                 minival = (*maxival >= 9 ? *maxival/3 : *maxival);
 321
 322         odhcpd_urandom(&msecs, sizeof(msecs));
 323         msecs = (labs(msecs) % ((*maxival != minival) ? (*maxival - minival)*1000 : 500)) +
 324                         minival*1000;
 325
 326         return msecs;
 327 }
 328
 329 static uint16_t calc_ra_lifetime(struct interface *iface, uint32_t maxival)
 330 {
 331         uint16_t lifetime = 3*maxival;
 332
 333         if (iface->ra_lifetime >= 0) {
 334                 lifetime = iface->ra_lifetime;
 335                 if (lifetime < maxival)
 336                         lifetime = maxival;
 337                 else if (lifetime > 9000)
 338                         lifetime = 9000;
 339         }
 340
 341         return lifetime;
 342 }
 343
 344 enum {
 345         IOV_RA_ADV=0,
 346         IOV_RA_PFXS,
 347         IOV_RA_ROUTES,
 348         IOV_RA_DNS,
 349         IOV_RA_DNS_ADDR,
 350         IOV_RA_SEARCH,
 351         IOV_RA_ADV_INTERVAL,
 352         IOV_RA_TOTAL,
 353 };
 354
 355 /* Router Advert server mode */
 356 static uint64_t send_router_advert(struct interface *iface, const struct in6_addr *from)
 357 {
 358         time_t now = odhcpd_time();
 359         int mtu = iface->ra_mtu;
 360         int hlim = iface->ra_hoplimit;
 361         char buf[INET6_ADDRSTRLEN];
 362
 363         if (mtu == 0)
 364                 mtu = odhcpd_get_interface_config(iface->ifname, "mtu");
 365
 366         if (mtu < 1280)
 367                 mtu = 1280;
 368
 369         if (hlim == 0)
 370                 hlim = odhcpd_get_interface_config(iface->ifname, "hop_limit");
 371
 372         struct {
 373                 struct nd_router_advert h;
 374                 struct icmpv6_opt lladdr;
 375                 struct nd_opt_mtu mtu;
 376         } adv = {
 377                 .h = {{.icmp6_type = ND_ROUTER_ADVERT, .icmp6_code = 0}, 0, 0},
 378                 .lladdr = {ND_OPT_SOURCE_LINKADDR, 1, {0}},
 379                 .mtu = {ND_OPT_MTU, 1, 0, htonl(mtu)},
 380         };
 381
 382         if (hlim > 0)
 383                 adv.h.nd_ra_curhoplimit = hlim;
 384
 385         if (iface->dhcpv6) {
 386                 adv.h.nd_ra_flags_reserved = ND_RA_FLAG_OTHER;
 387
 388                 if (iface->ra_managed >= RA_MANAGED_MFLAG)
 389                         adv.h.nd_ra_flags_reserved |= ND_RA_FLAG_MANAGED;
 390         }
 391
 392         if (iface->route_preference < 0)
 393                 adv.h.nd_ra_flags_reserved |= ND_RA_PREF_LOW;
 394         else if (iface->route_preference > 0)
 395                 adv.h.nd_ra_flags_reserved |= ND_RA_PREF_HIGH;
 396
 397         adv.h.nd_ra_reachable = htonl(iface->ra_reachabletime);
 398         adv.h.nd_ra_retransmit = htonl(iface->ra_retranstime);
 399
 400         odhcpd_get_mac(iface, adv.lladdr.data);
 401
 402         /* If not currently shutting down */
 403         struct odhcpd_ipaddr *addrs = NULL;
 404         ssize_t ipcnt = 0;
 405         uint32_t minvalid = UINT32_MAX;
 406         bool default_route = false;
 407         bool valid_prefix = false;
 408
 409         /* If not shutdown */
 410         if (iface->timer_rs.cb) {
 411                 size_t size = sizeof(*addrs) * iface->addr6_len;
 412                 addrs = alloca(size);
 413                 memcpy(addrs, iface->addr6, size);
 414
 415                 ipcnt = iface->addr6_len;
 416
 417                 /* Check default route */
 418                 if (iface->default_router) {
 419                         default_route = true;
 420
 421                         if (iface->default_router > 1)
 422                                 valid_prefix = true;
 423                 } else if (parse_routes(addrs, ipcnt))
 424                         default_route = true;
 425         }
 426
 427         /* DNS Recursive DNS */
 428         struct in6_addr dns_pref, *dns_addr = NULL;
 429         size_t dns_cnt = 0;
 430
 431         if (iface->ra_dns) {
 432                 if (iface->dns_cnt > 0) {
 433                         dns_addr = iface->dns;
 434                         dns_cnt = iface->dns_cnt;
 435                 } else if (!odhcpd_get_interface_dns_addr(iface, &dns_pref)) {
 436                         dns_addr = &dns_pref;
 437                         dns_cnt = 1;
 438                 }
 439         }
 440
 441         /* Construct Prefix Information options */
 442         size_t pfxs_cnt = 0;
 443         struct nd_opt_prefix_info *pfxs = NULL;
 444
 445         for (ssize_t i = 0; i < ipcnt; ++i) {
 446                 struct odhcpd_ipaddr *addr = &addrs[i];
 447                 uint32_t preferred = 0;
 448                 uint32_t valid = 0;
 449
 450                 if (addr->prefix > 96 || addr->valid <= (uint32_t)now) {
 451                         syslog(LOG_INFO, "Address %s (prefix %d, valid %u) not suitable as RA prefix on %s",
 452                                 inet_ntop(AF_INET6, &addr->addr.in6, buf, sizeof(buf)), addr->prefix,
 453                                 addr->valid, iface->name);
 454                         continue;
 455                 }
 456
 457                 if (odhcpd_bmemcmp(&addr->addr, &iface->pio_filter_addr,
 458                                    iface->pio_filter_length) != 0 ||
 459                     addr->prefix < iface->pio_filter_length) {
 460                         syslog(LOG_INFO, "Address %s filtered out as RA prefix on %s",
 461                                inet_ntop(AF_INET6, &addr->addr.in6, buf, sizeof(buf)),
 462                                iface->name);
 463                         continue; /* PIO filtered out of this RA */
 464                 }
 465
 466                 struct nd_opt_prefix_info *p = NULL;
 467                 for (size_t i = 0; i < pfxs_cnt; ++i) {
 468                         if (addr->prefix == pfxs[i].nd_opt_pi_prefix_len &&
 469                                         !odhcpd_bmemcmp(&pfxs[i].nd_opt_pi_prefix,
 470                                         &addr->addr.in6, addr->prefix))
 471                                 p = &pfxs[i];
 472                 }
 473
 474                 if (!p) {
 475                         struct nd_opt_prefix_info *tmp;
 476
 477                         tmp = realloc(pfxs, sizeof(*pfxs) * (pfxs_cnt + 1));
 478                         if (!tmp) {
 479                                 syslog(LOG_ERR, "Realloc failed for RA prefix option on %s", iface->name);
 480                                 continue;
 481                         }
 482
 483                         pfxs = tmp;
 484                         p = &pfxs[pfxs_cnt++];
 485                         memset(p, 0, sizeof(*p));
 486                 }
 487
 488                 if (addr->preferred > (uint32_t)now) {
 489                         preferred = TIME_LEFT(addr->preferred, now);
 490
 491                         if (iface->ra_useleasetime &&
 492                                         preferred > iface->dhcpv4_leasetime)
 493                                 preferred = iface->dhcpv4_leasetime;
 494                 }
 495
 496                 valid = TIME_LEFT(addr->valid, now);
 497                 if (iface->ra_useleasetime && valid > iface->dhcpv4_leasetime)
 498                         valid = iface->dhcpv4_leasetime;
 499
 500                 if (minvalid > valid)
 501                         minvalid = valid;
 502
 503                 if (!IN6_IS_ADDR_ULA(&addr->addr.in6) || iface->default_router)
 504                         valid_prefix = true;
 505
 506                 odhcpd_bmemcpy(&p->nd_opt_pi_prefix, &addr->addr.in6,
 507                                 (iface->ra_advrouter) ? 128 : addr->prefix);
 508                 p->nd_opt_pi_type = ND_OPT_PREFIX_INFORMATION;
 509                 p->nd_opt_pi_len = 4;
 510                 p->nd_opt_pi_prefix_len = (addr->prefix < 64) ? 64 : addr->prefix;
 511                 p->nd_opt_pi_flags_reserved = 0;
 512                 if (!iface->ra_not_onlink)
 513                         p->nd_opt_pi_flags_reserved |= ND_OPT_PI_FLAG_ONLINK;
 514                 if (iface->ra_managed < RA_MANAGED_NO_AFLAG && addr->prefix <= 64)
 515                         p->nd_opt_pi_flags_reserved |= ND_OPT_PI_FLAG_AUTO;
 516                 if (iface->ra_advrouter)
 517                         p->nd_opt_pi_flags_reserved |= ND_OPT_PI_FLAG_RADDR;
 518                 p->nd_opt_pi_preferred_time = htonl(preferred);
 519                 p->nd_opt_pi_valid_time = htonl(valid);
 520         }
 521
 522         /* Calculate periodic transmit */
 523         uint32_t maxival;
 524         int msecs = calc_adv_interval(iface, minvalid, &maxival);
 525
 526         if (default_route) {
 527                 if (!valid_prefix) {
 528                         syslog(LOG_WARNING, "A default route is present but there is no public prefix "
 529                                         "on %s thus we don't announce a default route!", iface->name);
 530                         adv.h.nd_ra_router_lifetime = 0;
 531                 } else
 532                         adv.h.nd_ra_router_lifetime = htons(calc_ra_lifetime(iface, maxival));
 533
 534         } else
 535                 adv.h.nd_ra_router_lifetime = 0;
 536
 537         syslog(LOG_INFO, "Using a RA lifetime of %d seconds on %s", ntohs(adv.h.nd_ra_router_lifetime), iface->name);
 538
 539         struct {
 540                 uint8_t type;
 541                 uint8_t len;
 542                 uint8_t pad;
 543                 uint8_t pad2;
 544                 uint32_t lifetime;
 545         } dns = {ND_OPT_RECURSIVE_DNS, (1 + (2 * dns_cnt)), 0, 0, 0};
 546
 547         /* DNS Search options */
 548         uint8_t *search_domain = NULL;
 549         size_t search_len = 0, search_padded = 0;
 550
 551         if (iface->ra_dns) {
 552                 search_len = iface->search_len;
 553                 search_domain = iface->search;
 554
 555                 if (!search_domain && !res_init() && _res.dnsrch[0] && _res.dnsrch[0][0]) {
 556                         uint8_t search_buf[256];
 557
 558                         int len = dn_comp(_res.dnsrch[0], search_buf,
 559                                         sizeof(search_buf), NULL, NULL);
 560                         if (len > 0) {
 561                                 search_domain = search_buf;
 562                                 search_len = len;
 563                         }
 564                 }
 565         }
 566
 567         if (search_len > 0)
 568                 search_padded = ((search_len + 7) & (~7)) + 8;
 569
 570         struct {
 571                 uint8_t type;
 572                 uint8_t len;
 573                 uint8_t pad;
 574                 uint8_t pad2;
 575                 uint32_t lifetime;
 576                 uint8_t name[];
 577         } *search = alloca(sizeof(*search) + search_padded);
 578
 579         search->type = ND_OPT_DNS_SEARCH;
 580         search->len = search_len ? ((sizeof(*search) + search_padded) / 8) : 0;
 581         search->pad = 0;
 582         search->pad2 = 0;
 583
 584         if (search_len > 0) {
 585                 memcpy(search->name, search_domain, search_len);
 586                 memset(&search->name[search_len], 0, search_padded - search_len);
 587         }
 588
 589         size_t routes_cnt = 0;
 590         struct {
 591                 uint8_t type;
 592                 uint8_t len;
 593                 uint8_t prefix;
 594                 uint8_t flags;
 595                 uint32_t lifetime;
 596                 uint32_t addr[4];
 597         } *tmp, *routes = NULL;
 598
 599         for (ssize_t i = 0; i < ipcnt; ++i) {
 600                 struct odhcpd_ipaddr *addr = &addrs[i];
 601                 if (addr->dprefix > 64 || addr->dprefix == 0 || addr->valid <= (uint32_t)now) {
 602                         syslog(LOG_INFO, "Address %s (dprefix %d, valid %u) not suitable as RA route on %s",
 603                                 inet_ntop(AF_INET6, &addr->addr.in6, buf, sizeof(buf)),
 604                                 addr->dprefix, addr->valid, iface->name);
 605
 606                         continue; /* Address not suitable */
 607                 }
 608
 609                 if (odhcpd_bmemcmp(&addr->addr, &iface->pio_filter_addr,
 610                                 iface->pio_filter_length) != 0 ||
 611                                 addr->prefix < iface->pio_filter_length) {
 612                         syslog(LOG_INFO, "Address %s filtered out as RA route on %s",
 613                                inet_ntop(AF_INET6, &addr->addr.in6, buf, sizeof(buf)),
 614                                iface->name);
 615                         continue; /* PIO filtered out of this RA */
 616                 }
 617
 618                 if (addr->dprefix > 32) {
 619                         addr->addr.in6.s6_addr32[1] &= htonl(~((1U << (64 - addr->dprefix)) - 1));
 620                 } else if (addr->dprefix <= 32) {
 621                         addr->addr.in6.s6_addr32[0] &= htonl(~((1U << (32 - addr->dprefix)) - 1));
 622                         addr->addr.in6.s6_addr32[1] = 0;
 623                 }
 624
 625                 tmp = realloc(routes, sizeof(*routes) * (routes_cnt + 1));
 626                 if (!tmp) {
 627                         syslog(LOG_ERR, "Realloc failed for RA route option on %s", iface->name);
 628                         continue;
 629                 }
 630
 631                 routes = tmp;
 632
 633                 memset(&routes[routes_cnt], 0, sizeof(*routes));
 634                 routes[routes_cnt].type = ND_OPT_ROUTE_INFO;
 635                 routes[routes_cnt].len = sizeof(*routes) / 8;
 636                 routes[routes_cnt].prefix = addr->dprefix;
 637                 routes[routes_cnt].flags = 0;
 638                 if (iface->route_preference < 0)
 639                         routes[routes_cnt].flags |= ND_RA_PREF_LOW;
 640                 else if (iface->route_preference > 0)
 641                         routes[routes_cnt].flags |= ND_RA_PREF_HIGH;
 642                 routes[routes_cnt].lifetime = htonl(TIME_LEFT(addr->valid, now));
 643                 routes[routes_cnt].addr[0] = addr->addr.in6.s6_addr32[0];
 644                 routes[routes_cnt].addr[1] = addr->addr.in6.s6_addr32[1];
 645                 routes[routes_cnt].addr[2] = 0;
 646                 routes[routes_cnt].addr[3] = 0;
 647
 648                 ++routes_cnt;
 649         }
 650
 651         search->lifetime = htonl(maxival*10);
 652         dns.lifetime = search->lifetime;
 653
 654         struct icmpv6_opt adv_interval = {
 655                 .type = ND_OPT_RTR_ADV_INTERVAL,
 656                 .len = 1,
 657                 .data = {0, 0, (maxival*1000) >> 24, (maxival*1000) >> 16, (maxival*1000) >> 8, maxival*1000}
 658         };
 659
 660         struct iovec iov[IOV_RA_TOTAL] = {
 661                         [IOV_RA_ADV] = {&adv, sizeof(adv)},
 662                         [IOV_RA_PFXS] = {pfxs, pfxs_cnt * sizeof(*pfxs)},
 663                         [IOV_RA_ROUTES] = {routes, routes_cnt * sizeof(*routes)},
 664                         [IOV_RA_DNS] = {&dns, (dns_cnt) ? sizeof(dns) : 0},
 665                         [IOV_RA_DNS_ADDR] = {dns_addr, dns_cnt * sizeof(*dns_addr)},
 666                         [IOV_RA_SEARCH] = {search, search->len * 8},
 667                         [IOV_RA_ADV_INTERVAL] = {&adv_interval, adv_interval.len * 8}};
 668         struct sockaddr_in6 dest;
 669
 670         memset(&dest, 0, sizeof(dest));
 671         dest.sin6_family = AF_INET6;
 672
 673         if (from && !IN6_IS_ADDR_UNSPECIFIED(from))
 674                 dest.sin6_addr = *from;
 675         else
 676                 inet_pton(AF_INET6, ALL_IPV6_NODES, &dest.sin6_addr);
 677
 678         syslog(LOG_INFO, "Sending a RA on %s", iface->name);
 679
 680         odhcpd_send(router_event.uloop.fd,
 681                         &dest, iov, ARRAY_SIZE(iov), iface);
 682
 683         free(pfxs);
 684         free(routes);
 685
 686         return msecs;
 687 }
 688
 689
 690 static void trigger_router_advert(struct uloop_timeout *event)
 691 {
 692         struct interface *iface = container_of(event, struct interface, timer_rs);
 693         int msecs = send_router_advert(iface, NULL);
 694
 695         /* Rearm timer if not shut down */
 696         if (event->cb)
 697                 uloop_timeout_set(event, msecs);
 698 }
 699
 700
 701 /* Event handler for incoming ICMPv6 packets */
 702 static void handle_icmpv6(void *addr, void *data, size_t len,
 703                 struct interface *iface, _unused void *dest)
 704 {
 705         struct icmp6_hdr *hdr = data;
 706         struct sockaddr_in6 *from = addr;
 707
 708         if (!router_icmpv6_valid(addr, data, len))
 709                 return;
 710
 711         if ((iface->ra == MODE_SERVER && !iface->master)) { /* Server mode */
 712                 if (hdr->icmp6_type == ND_ROUTER_SOLICIT)
 713                         send_router_advert(iface, &from->sin6_addr);
 714         } else if (iface->ra == MODE_RELAY) { /* Relay mode */
 715                 if (hdr->icmp6_type == ND_ROUTER_SOLICIT && !iface->master) {
 716                         struct interface *c;
 717
 718                         avl_for_each_element(&interfaces, c, avl) {
 719                                 if (!c->master || c->ra != MODE_RELAY)
 720                                         continue;
 721
 722                                 forward_router_solicitation(c);
 723                         }
 724                 } else if (hdr->icmp6_type == ND_ROUTER_ADVERT && iface->master)
 725                         forward_router_advertisement(iface, data, len);
 726         }
 727 }
 728
 729
 730 /* Forward router solicitation */
 731 static void forward_router_solicitation(const struct interface *iface)
 732 {
 733         struct icmp6_hdr rs = {ND_ROUTER_SOLICIT, 0, 0, {{0}}};
 734         struct iovec iov = {&rs, sizeof(rs)};
 735         struct sockaddr_in6 all_routers;
 736
 737         if (!iface)
 738                 return;
 739
 740         memset(&all_routers, 0, sizeof(all_routers));
 741         all_routers.sin6_family = AF_INET6;
 742         inet_pton(AF_INET6, ALL_IPV6_ROUTERS, &all_routers.sin6_addr);
 743         all_routers.sin6_scope_id = iface->ifindex;
 744
 745         syslog(LOG_NOTICE, "Sending RS to %s", iface->name);
 746         odhcpd_send(router_event.uloop.fd, &all_routers, &iov, 1, iface);
 747 }
 748
 749
 750 /* Handler for incoming router solicitations on slave interfaces */
 751 static void forward_router_advertisement(const struct interface *iface, uint8_t *data, size_t len)
 752 {
 753         struct nd_router_advert *adv = (struct nd_router_advert *)data;
 754         struct sockaddr_in6 all_nodes;
 755         struct icmpv6_opt *opt;
 756         struct interface *c;
 757         struct iovec iov = { .iov_base = data, .iov_len = len };
 758         /* Rewrite options */
 759         uint8_t *end = data + len;
 760         uint8_t *mac_ptr = NULL;
 761         struct in6_addr *dns_ptr = NULL;
 762         size_t dns_count = 0;
 763
 764         icmpv6_for_each_option(opt, &adv[1], end) {
 765                 if (opt->type == ND_OPT_SOURCE_LINKADDR) {
 766                         /* Store address of source MAC-address */
 767                         mac_ptr = opt->data;
 768                 } else if (opt->type == ND_OPT_RECURSIVE_DNS && opt->len > 1) {
 769                         /* Check if we have to rewrite DNS */
 770                         dns_ptr = (struct in6_addr*)&opt->data[6];
 771                         dns_count = (opt->len - 1) / 2;
 772                 }
 773         }
 774
 775         syslog(LOG_NOTICE, "Got a RA on %s", iface->name);
 776
 777         /* Indicate a proxy, however we don't follow the rest of RFC 4389 yet */
 778         adv->nd_ra_flags_reserved |= ND_RA_FLAG_PROXY;
 779
 780         /* Forward advertisement to all slave interfaces */
 781         memset(&all_nodes, 0, sizeof(all_nodes));
 782         all_nodes.sin6_family = AF_INET6;
 783         inet_pton(AF_INET6, ALL_IPV6_NODES, &all_nodes.sin6_addr);
 784
 785         avl_for_each_element(&interfaces, c, avl) {
 786                 if (c->ra != MODE_RELAY || c->master)
 787                         continue;
 788
 789                 /* Fixup source hardware address option */
 790                 if (mac_ptr)
 791                         odhcpd_get_mac(c, mac_ptr);
 792
 793                 /* If we have to rewrite DNS entries */
 794                 if (c->always_rewrite_dns && dns_ptr && dns_count > 0) {
 795                         const struct in6_addr *rewrite = c->dns;
 796                         struct in6_addr addr;
 797                         size_t rewrite_cnt = c->dns_cnt;
 798
 799                         if (rewrite_cnt == 0) {
 800                                 if (odhcpd_get_interface_dns_addr(c, &addr))
 801                                         continue; /* Unable to comply */
 802
 803                                 rewrite = &addr;
 804                                 rewrite_cnt = 1;
 805                         }
 806
 807                         /* Copy over any other addresses */
 808                         for (size_t i = 0; i < dns_count; ++i) {
 809                                 size_t j = (i < rewrite_cnt) ? i : rewrite_cnt - 1;
 810                                 dns_ptr[i] = rewrite[j];
 811                         }
 812                 }
 813
 814                 syslog(LOG_NOTICE, "Forward a RA on %s", c->name);
 815
 816                 odhcpd_send(router_event.uloop.fd, &all_nodes, &iov, 1, c);
 817         }
 818 }