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         if (!fp_route) {
  78                 ret = -1;
  79                 goto out;
  80         }
  81
  82
  83         if ((!enable || iface->ra == MODE_DISABLED) && iface->router_event.uloop.fd >= 0) {
  84                 if (!iface->master) {
  85                         uloop_timeout_cancel(&iface->timer_rs);
  86                         iface->timer_rs.cb = NULL;
  87
  88                         trigger_router_advert(&iface->timer_rs);
  89                 }
  90
  91                 uloop_fd_delete(&iface->router_event.uloop);
  92                 close(iface->router_event.uloop.fd);
  93                 iface->router_event.uloop.fd = -1;
  94         } else if (enable && iface->ra != MODE_DISABLED) {
  95                 struct icmp6_filter filt;
  96                 struct ipv6_mreq mreq;
  97                 int val = 2;
  98
  99                 if (iface->router_event.uloop.fd < 0) {
 100                         /* Open ICMPv6 socket */
 101                         iface->router_event.uloop.fd = socket(AF_INET6, SOCK_RAW | SOCK_CLOEXEC,
 102                                                               IPPROTO_ICMPV6);
 103                         if (iface->router_event.uloop.fd < 0) {
 104                                 syslog(LOG_ERR, "socket(AF_INET6): %m");
 105                                 ret = -1;
 106                                 goto out;
 107                         }
 108
 109                         if (setsockopt(iface->router_event.uloop.fd, SOL_SOCKET, SO_BINDTODEVICE,
 110                                        iface->ifname, strlen(iface->ifname)) < 0) {
 111                                 syslog(LOG_ERR, "setsockopt(SO_BINDTODEVICE): %m");
 112                                 ret = -1;
 113                                 goto out;
 114                         }
 115
 116                         /* Let the kernel compute our checksums */
 117                         if (setsockopt(iface->router_event.uloop.fd, IPPROTO_RAW, IPV6_CHECKSUM,
 118                                        &val, sizeof(val)) < 0) {
 119                                 syslog(LOG_ERR, "setsockopt(IPV6_CHECKSUM): %m");
 120                                 ret = -1;
 121                                 goto out;
 122                         }
 123
 124                         /* This is required by RFC 4861 */
 125                         val = 255;
 126                         if (setsockopt(iface->router_event.uloop.fd, IPPROTO_IPV6, IPV6_MULTICAST_HOPS,
 127                                        &val, sizeof(val)) < 0) {
 128                                 syslog(LOG_ERR, "setsockopt(IPV6_MULTICAST_HOPS): %m");
 129                                 ret = -1;
 130                                 goto out;
 131                         }
 132
 133                         if (setsockopt(iface->router_event.uloop.fd, IPPROTO_IPV6, IPV6_UNICAST_HOPS,
 134                                        &val, sizeof(val)) < 0) {
 135                                 syslog(LOG_ERR, "setsockopt(IPV6_UNICAST_HOPS): %m");
 136                                 ret = -1;
 137                                 goto out;
 138                         }
 139
 140                         /* We need to know the source interface */
 141                         val = 1;
 142                         if (setsockopt(iface->router_event.uloop.fd, IPPROTO_IPV6, IPV6_RECVPKTINFO,
 143                                        &val, sizeof(val)) < 0) {
 144                                 syslog(LOG_ERR, "setsockopt(IPV6_RECVPKTINFO): %m");
 145                                 ret = -1;
 146                                 goto out;
 147                         }
 148
 149                         if (setsockopt(iface->router_event.uloop.fd, IPPROTO_IPV6, IPV6_RECVHOPLIMIT,
 150                                        &val, sizeof(val)) < 0) {
 151                                 syslog(LOG_ERR, "setsockopt(IPV6_RECVHOPLIMIT): %m");
 152                                 ret = -1;
 153                                 goto out;
 154                         }
 155
 156                         /* Don't loop back */
 157                         val = 0;
 158                         if (setsockopt(iface->router_event.uloop.fd, IPPROTO_IPV6, IPV6_MULTICAST_LOOP,
 159                                        &val, sizeof(val)) < 0) {
 160                                 syslog(LOG_ERR, "setsockopt(IPV6_MULTICAST_LOOP): %m");
 161                                 ret = -1;
 162                                 goto out;
 163                         }
 164
 165                         /* Filter ICMPv6 package types */
 166                         ICMP6_FILTER_SETBLOCKALL(&filt);
 167                         ICMP6_FILTER_SETPASS(ND_ROUTER_ADVERT, &filt);
 168                         ICMP6_FILTER_SETPASS(ND_ROUTER_SOLICIT, &filt);
 169                         if (setsockopt(iface->router_event.uloop.fd, IPPROTO_ICMPV6, ICMP6_FILTER,
 170                                        &filt, sizeof(filt)) < 0) {
 171                                 syslog(LOG_ERR, "setsockopt(ICMP6_FILTER): %m");
 172                                 ret = -1;
 173                                 goto out;
 174                         }
 175
 176                         iface->router_event.handle_dgram = handle_icmpv6;
 177                         odhcpd_register(&iface->router_event);
 178                 } else {
 179                         uloop_timeout_cancel(&iface->timer_rs);
 180                         iface->timer_rs.cb = NULL;
 181
 182                         memset(&mreq, 0, sizeof(mreq));
 183                         mreq.ipv6mr_interface = iface->ifindex;
 184                         inet_pton(AF_INET6, ALL_IPV6_NODES, &mreq.ipv6mr_multiaddr);
 185                         setsockopt(iface->router_event.uloop.fd, IPPROTO_IPV6, IPV6_DROP_MEMBERSHIP,
 186                                    &mreq, sizeof(mreq));
 187
 188                         inet_pton(AF_INET6, ALL_IPV6_ROUTERS, &mreq.ipv6mr_multiaddr);
 189                         setsockopt(iface->router_event.uloop.fd, IPPROTO_IPV6, IPV6_DROP_MEMBERSHIP,
 190                                    &mreq, sizeof(mreq));
 191                 }
 192
 193                 memset(&mreq, 0, sizeof(mreq));
 194                 mreq.ipv6mr_interface = iface->ifindex;
 195                 inet_pton(AF_INET6, ALL_IPV6_ROUTERS, &mreq.ipv6mr_multiaddr);
 196
 197                 if (iface->ra == MODE_RELAY && iface->master) {
 198                         inet_pton(AF_INET6, ALL_IPV6_NODES, &mreq.ipv6mr_multiaddr);
 199                         forward_router_solicitation(iface);
 200                 } else if (iface->ra == MODE_SERVER) {
 201                         iface->timer_rs.cb = trigger_router_advert;
 202                         uloop_timeout_set(&iface->timer_rs, 1000);
 203                 }
 204
 205                 if (setsockopt(iface->router_event.uloop.fd, IPPROTO_IPV6,
 206                                IPV6_ADD_MEMBERSHIP, &mreq, sizeof(mreq)) < 0) {
 207                         ret = -1;
 208                         syslog(LOG_ERR, "setsockopt(IPV6_ADD_MEMBERSHIP): %m");
 209                         goto out;
 210                 }
 211         }
 212 out:
 213         if (ret < 0 && iface->router_event.uloop.fd >= 0) {
 214                 close(iface->router_event.uloop.fd);
 215                 iface->router_event.uloop.fd = -1;
 216         }
 217
 218         return ret;
 219 }
 220
 221
 222 static void router_netevent_cb(unsigned long event, struct netevent_handler_info *info)
 223 {
 224         struct interface *iface;
 225
 226         switch (event) {
 227         case NETEV_ROUTE6_ADD:
 228         case NETEV_ROUTE6_DEL:
 229                 if (info->rt.dst_len)
 230                         break;
 231
 232                 avl_for_each_element(&interfaces, iface, avl) {
 233                         if (iface->ra == MODE_SERVER && !iface->master)
 234                                 uloop_timeout_set(&iface->timer_rs, 1000);
 235                 }
 236                 break;
 237         case NETEV_ADDR6LIST_CHANGE:
 238                 iface = info->iface;
 239                 if (iface && iface->ra == MODE_SERVER && !iface->master)
 240                         uloop_timeout_set(&iface->timer_rs, 1000);
 241                 break;
 242         default:
 243                 break;
 244         }
 245 }
 246
 247
 248 static bool router_icmpv6_valid(struct sockaddr_in6 *source, uint8_t *data, size_t len)
 249 {
 250         struct icmp6_hdr *hdr = (struct icmp6_hdr *)data;
 251         struct icmpv6_opt *opt, *end = (struct icmpv6_opt*)&data[len];
 252
 253         /* Hoplimit is already checked in odhcpd_receive_packets */
 254         if (len < sizeof(*hdr) || hdr->icmp6_code)
 255                 return false;
 256
 257         switch (hdr->icmp6_type) {
 258         case ND_ROUTER_ADVERT:
 259                 if (!IN6_IS_ADDR_LINKLOCAL(&source->sin6_addr))
 260                         return false;
 261
 262                 opt = (struct icmpv6_opt *)((struct nd_router_advert *)data + 1);
 263                 break;
 264
 265         case ND_ROUTER_SOLICIT:
 266                 opt = (struct icmpv6_opt *)((struct nd_router_solicit *)data + 1);
 267                 break;
 268
 269         default:
 270                 return false;
 271         }
 272
 273         icmpv6_for_each_option(opt, opt, end)
 274                 if (opt->type == ND_OPT_SOURCE_LINKADDR &&
 275                                 IN6_IS_ADDR_UNSPECIFIED(&source->sin6_addr) &&
 276                                 hdr->icmp6_type == ND_ROUTER_SOLICIT)
 277                         return false;
 278
 279         /* Check all options parsed successfully */
 280         return opt == end;
 281 }
 282
 283
 284 /* Detect whether a default route exists, also find the source prefixes */
 285 static bool parse_routes(struct odhcpd_ipaddr *n, ssize_t len)
 286 {
 287         rewind(fp_route);
 288
 289         char line[512], ifname[16];
 290         bool found_default = false;
 291         struct odhcpd_ipaddr p = { .addr.in6 = IN6ADDR_ANY_INIT, .prefix = 0,
 292                                         .dprefix = 0, .preferred = 0, .valid = 0};
 293
 294         while (fgets(line, sizeof(line), fp_route)) {
 295                 uint32_t rflags;
 296                 if (sscanf(line, "00000000000000000000000000000000 00 "
 297                                 "%*s %*s %*s %*s %*s %*s %*s %15s", ifname) &&
 298                                 strcmp(ifname, "lo")) {
 299                         found_default = true;
 300                 } else if (sscanf(line, "%8" SCNx32 "%8" SCNx32 "%*8" SCNx32 "%*8" SCNx32 " %hhx %*s "
 301                                 "%*s 00000000000000000000000000000000 %*s %*s %*s %" SCNx32 " lo",
 302                                 &p.addr.in6.s6_addr32[0], &p.addr.in6.s6_addr32[1], &p.prefix, &rflags) &&
 303                                 p.prefix > 0 && (rflags & RTF_NONEXTHOP) && (rflags & RTF_REJECT)) {
 304                         // Find source prefixes by scanning through unreachable-routes
 305                         p.addr.in6.s6_addr32[0] = htonl(p.addr.in6.s6_addr32[0]);
 306                         p.addr.in6.s6_addr32[1] = htonl(p.addr.in6.s6_addr32[1]);
 307
 308                         for (ssize_t i = 0; i < len; ++i) {
 309                                 if (n[i].prefix <= 64 && n[i].prefix >= p.prefix &&
 310                                                 !odhcpd_bmemcmp(&p.addr.in6, &n[i].addr.in6, p.prefix)) {
 311                                         n[i].dprefix = p.prefix;
 312                                         break;
 313                                 }
 314                         }
 315                 }
 316         }
 317
 318         return found_default;
 319 }
 320
 321 static int calc_adv_interval(struct interface *iface, uint32_t minvalid,
 322                 uint32_t *maxival)
 323 {
 324         uint32_t minival = iface->ra_mininterval;
 325         int msecs;
 326
 327         *maxival = iface->ra_maxinterval;
 328
 329         if (*maxival > minvalid/3)
 330                 *maxival = minvalid/3;
 331
 332         if (*maxival > MaxRtrAdvInterval)
 333                 *maxival = MaxRtrAdvInterval;
 334         else if (*maxival < 4)
 335                 *maxival = 4;
 336
 337         if (minival < MinRtrAdvInterval)
 338                 minival = MinRtrAdvInterval;
 339         else if (minival > (*maxival * 3)/4)
 340                 minival = (*maxival >= 9 ? *maxival/3 : *maxival);
 341
 342         odhcpd_urandom(&msecs, sizeof(msecs));
 343         msecs = (labs(msecs) % ((*maxival != minival) ? (*maxival - minival)*1000 : 500)) +
 344                         minival*1000;
 345
 346         return msecs;
 347 }
 348
 349 static uint16_t calc_ra_lifetime(struct interface *iface, uint32_t maxival)
 350 {
 351         uint16_t lifetime = 3*maxival;
 352
 353         if (iface->ra_lifetime >= 0) {
 354                 lifetime = iface->ra_lifetime;
 355                 if (lifetime < maxival)
 356                         lifetime = maxival;
 357                 else if (lifetime > 9000)
 358                         lifetime = 9000;
 359         }
 360
 361         return lifetime;
 362 }
 363
 364 enum {
 365         IOV_RA_ADV=0,
 366         IOV_RA_PFXS,
 367         IOV_RA_ROUTES,
 368         IOV_RA_DNS,
 369         IOV_RA_DNS_ADDR,
 370         IOV_RA_SEARCH,
 371         IOV_RA_ADV_INTERVAL,
 372         IOV_RA_TOTAL,
 373 };
 374
 375 /* Router Advert server mode */
 376 static uint64_t send_router_advert(struct interface *iface, const struct in6_addr *from)
 377 {
 378         time_t now = odhcpd_time();
 379         int mtu = iface->ra_mtu;
 380         int hlim = iface->ra_hoplimit;
 381         char buf[INET6_ADDRSTRLEN];
 382
 383         if (mtu == 0)
 384                 mtu = odhcpd_get_interface_config(iface->ifname, "mtu");
 385
 386         if (mtu < 1280)
 387                 mtu = 1280;
 388
 389         if (hlim == 0)
 390                 hlim = odhcpd_get_interface_config(iface->ifname, "hop_limit");
 391
 392         struct {
 393                 struct nd_router_advert h;
 394                 struct icmpv6_opt lladdr;
 395                 struct nd_opt_mtu mtu;
 396         } adv = {
 397                 .h = {{.icmp6_type = ND_ROUTER_ADVERT, .icmp6_code = 0}, 0, 0},
 398                 .lladdr = {ND_OPT_SOURCE_LINKADDR, 1, {0}},
 399                 .mtu = {ND_OPT_MTU, 1, 0, htonl(mtu)},
 400         };
 401
 402         if (hlim > 0)
 403                 adv.h.nd_ra_curhoplimit = hlim;
 404
 405         if (iface->dhcpv6) {
 406                 adv.h.nd_ra_flags_reserved = ND_RA_FLAG_OTHER;
 407
 408                 if (iface->ra_managed >= RA_MANAGED_MFLAG)
 409                         adv.h.nd_ra_flags_reserved |= ND_RA_FLAG_MANAGED;
 410         }
 411
 412         if (iface->route_preference < 0)
 413                 adv.h.nd_ra_flags_reserved |= ND_RA_PREF_LOW;
 414         else if (iface->route_preference > 0)
 415                 adv.h.nd_ra_flags_reserved |= ND_RA_PREF_HIGH;
 416
 417         adv.h.nd_ra_reachable = htonl(iface->ra_reachabletime);
 418         adv.h.nd_ra_retransmit = htonl(iface->ra_retranstime);
 419
 420         odhcpd_get_mac(iface, adv.lladdr.data);
 421
 422         /* If not currently shutting down */
 423         struct odhcpd_ipaddr *addrs = NULL;
 424         ssize_t ipcnt = 0;
 425         uint32_t minvalid = UINT32_MAX;
 426         bool default_route = false;
 427         bool valid_prefix = false;
 428
 429         /* If not shutdown */
 430         if (iface->timer_rs.cb) {
 431                 size_t size = sizeof(*addrs) * iface->addr6_len;
 432                 addrs = alloca(size);
 433                 memcpy(addrs, iface->addr6, size);
 434
 435                 ipcnt = iface->addr6_len;
 436
 437                 /* Check default route */
 438                 if (iface->default_router) {
 439                         default_route = true;
 440
 441                         if (iface->default_router > 1)
 442                                 valid_prefix = true;
 443                 } else if (parse_routes(addrs, ipcnt))
 444                         default_route = true;
 445         }
 446
 447         /* DNS Recursive DNS */
 448         struct in6_addr dns_pref, *dns_addr = NULL;
 449         size_t dns_cnt = 0;
 450
 451         if (iface->ra_dns) {
 452                 if (iface->dns_cnt > 0) {
 453                         dns_addr = iface->dns;
 454                         dns_cnt = iface->dns_cnt;
 455                 } else if (!odhcpd_get_interface_dns_addr(iface, &dns_pref)) {
 456                         dns_addr = &dns_pref;
 457                         dns_cnt = 1;
 458                 }
 459         }
 460
 461         /* Construct Prefix Information options */
 462         size_t pfxs_cnt = 0;
 463         struct nd_opt_prefix_info *pfxs = NULL;
 464
 465         for (ssize_t i = 0; i < ipcnt; ++i) {
 466                 struct odhcpd_ipaddr *addr = &addrs[i];
 467                 uint32_t preferred = 0;
 468                 uint32_t valid = 0;
 469
 470                 if (addr->prefix > 96 || addr->valid <= (uint32_t)now) {
 471                         syslog(LOG_INFO, "Address %s (prefix %d, valid %u) not suitable as RA prefix on %s",
 472                                 inet_ntop(AF_INET6, &addr->addr.in6, buf, sizeof(buf)), addr->prefix,
 473                                 addr->valid, iface->name);
 474                         continue;
 475                 }
 476
 477                 if (odhcpd_bmemcmp(&addr->addr, &iface->pio_filter_addr,
 478                                    iface->pio_filter_length) != 0 ||
 479                     addr->prefix < iface->pio_filter_length) {
 480                         syslog(LOG_INFO, "Address %s filtered out as RA prefix on %s",
 481                                inet_ntop(AF_INET6, &addr->addr.in6, buf, sizeof(buf)),
 482                                iface->name);
 483                         continue; /* PIO filtered out of this RA */
 484                 }
 485
 486                 struct nd_opt_prefix_info *p = NULL;
 487                 for (size_t i = 0; i < pfxs_cnt; ++i) {
 488                         if (addr->prefix == pfxs[i].nd_opt_pi_prefix_len &&
 489                                         !odhcpd_bmemcmp(&pfxs[i].nd_opt_pi_prefix,
 490                                         &addr->addr.in6, addr->prefix))
 491                                 p = &pfxs[i];
 492                 }
 493
 494                 if (!p) {
 495                         struct nd_opt_prefix_info *tmp;
 496
 497                         tmp = realloc(pfxs, sizeof(*pfxs) * (pfxs_cnt + 1));
 498                         if (!tmp) {
 499                                 syslog(LOG_ERR, "Realloc failed for RA prefix option on %s", iface->name);
 500                                 continue;
 501                         }
 502
 503                         pfxs = tmp;
 504                         p = &pfxs[pfxs_cnt++];
 505                         memset(p, 0, sizeof(*p));
 506                 }
 507
 508                 if (addr->preferred > (uint32_t)now) {
 509                         preferred = TIME_LEFT(addr->preferred, now);
 510
 511                         if (iface->ra_useleasetime &&
 512                                         preferred > iface->dhcpv4_leasetime)
 513                                 preferred = iface->dhcpv4_leasetime;
 514                 }
 515
 516                 valid = TIME_LEFT(addr->valid, now);
 517                 if (iface->ra_useleasetime && valid > iface->dhcpv4_leasetime)
 518                         valid = iface->dhcpv4_leasetime;
 519
 520                 if (minvalid > valid)
 521                         minvalid = valid;
 522
 523                 if (!IN6_IS_ADDR_ULA(&addr->addr.in6) || iface->default_router)
 524                         valid_prefix = true;
 525
 526                 odhcpd_bmemcpy(&p->nd_opt_pi_prefix, &addr->addr.in6,
 527                                 (iface->ra_advrouter) ? 128 : addr->prefix);
 528                 p->nd_opt_pi_type = ND_OPT_PREFIX_INFORMATION;
 529                 p->nd_opt_pi_len = 4;
 530                 p->nd_opt_pi_prefix_len = (addr->prefix < 64) ? 64 : addr->prefix;
 531                 p->nd_opt_pi_flags_reserved = 0;
 532                 if (!iface->ra_not_onlink)
 533                         p->nd_opt_pi_flags_reserved |= ND_OPT_PI_FLAG_ONLINK;
 534                 if (iface->ra_managed < RA_MANAGED_NO_AFLAG && addr->prefix <= 64)
 535                         p->nd_opt_pi_flags_reserved |= ND_OPT_PI_FLAG_AUTO;
 536                 if (iface->ra_advrouter)
 537                         p->nd_opt_pi_flags_reserved |= ND_OPT_PI_FLAG_RADDR;
 538                 p->nd_opt_pi_preferred_time = htonl(preferred);
 539                 p->nd_opt_pi_valid_time = htonl(valid);
 540         }
 541
 542         /* Calculate periodic transmit */
 543         uint32_t maxival;
 544         int msecs = calc_adv_interval(iface, minvalid, &maxival);
 545
 546         if (default_route) {
 547                 if (!valid_prefix) {
 548                         syslog(LOG_WARNING, "A default route is present but there is no public prefix "
 549                                         "on %s thus we don't announce a default route!", iface->name);
 550                         adv.h.nd_ra_router_lifetime = 0;
 551                 } else
 552                         adv.h.nd_ra_router_lifetime = htons(calc_ra_lifetime(iface, maxival));
 553
 554         } else
 555                 adv.h.nd_ra_router_lifetime = 0;
 556
 557         syslog(LOG_INFO, "Using a RA lifetime of %d seconds on %s", ntohs(adv.h.nd_ra_router_lifetime), iface->name);
 558
 559         struct {
 560                 uint8_t type;
 561                 uint8_t len;
 562                 uint8_t pad;
 563                 uint8_t pad2;
 564                 uint32_t lifetime;
 565         } dns = {ND_OPT_RECURSIVE_DNS, (1 + (2 * dns_cnt)), 0, 0, 0};
 566
 567         /* DNS Search options */
 568         uint8_t *search_domain = NULL;
 569         size_t search_len = 0, search_padded = 0;
 570
 571         if (iface->ra_dns) {
 572                 search_len = iface->search_len;
 573                 search_domain = iface->search;
 574
 575                 if (!search_domain && !res_init() && _res.dnsrch[0] && _res.dnsrch[0][0]) {
 576                         uint8_t search_buf[256];
 577
 578                         int len = dn_comp(_res.dnsrch[0], search_buf,
 579                                         sizeof(search_buf), NULL, NULL);
 580                         if (len > 0) {
 581                                 search_domain = search_buf;
 582                                 search_len = len;
 583                         }
 584                 }
 585         }
 586
 587         if (search_len > 0)
 588                 search_padded = ((search_len + 7) & (~7)) + 8;
 589
 590         struct {
 591                 uint8_t type;
 592                 uint8_t len;
 593                 uint8_t pad;
 594                 uint8_t pad2;
 595                 uint32_t lifetime;
 596                 uint8_t name[];
 597         } *search = alloca(sizeof(*search) + search_padded);
 598
 599         search->type = ND_OPT_DNS_SEARCH;
 600         search->len = search_len ? ((sizeof(*search) + search_padded) / 8) : 0;
 601         search->pad = 0;
 602         search->pad2 = 0;
 603
 604         if (search_len > 0) {
 605                 memcpy(search->name, search_domain, search_len);
 606                 memset(&search->name[search_len], 0, search_padded - search_len);
 607         }
 608
 609         size_t routes_cnt = 0;
 610         struct {
 611                 uint8_t type;
 612                 uint8_t len;
 613                 uint8_t prefix;
 614                 uint8_t flags;
 615                 uint32_t lifetime;
 616                 uint32_t addr[4];
 617         } *tmp, *routes = NULL;
 618
 619         for (ssize_t i = 0; i < ipcnt; ++i) {
 620                 struct odhcpd_ipaddr *addr = &addrs[i];
 621                 if (addr->dprefix > 64 || addr->dprefix == 0 || addr->valid <= (uint32_t)now) {
 622                         syslog(LOG_INFO, "Address %s (dprefix %d, valid %u) not suitable as RA route on %s",
 623                                 inet_ntop(AF_INET6, &addr->addr.in6, buf, sizeof(buf)),
 624                                 addr->dprefix, addr->valid, iface->name);
 625
 626                         continue; /* Address not suitable */
 627                 }
 628
 629                 if (odhcpd_bmemcmp(&addr->addr, &iface->pio_filter_addr,
 630                                 iface->pio_filter_length) != 0 ||
 631                                 addr->prefix < iface->pio_filter_length) {
 632                         syslog(LOG_INFO, "Address %s filtered out as RA route on %s",
 633                                inet_ntop(AF_INET6, &addr->addr.in6, buf, sizeof(buf)),
 634                                iface->name);
 635                         continue; /* PIO filtered out of this RA */
 636                 }
 637
 638                 if (addr->dprefix > 32) {
 639                         addr->addr.in6.s6_addr32[1] &= htonl(~((1U << (64 - addr->dprefix)) - 1));
 640                 } else if (addr->dprefix <= 32) {
 641                         addr->addr.in6.s6_addr32[0] &= htonl(~((1U << (32 - addr->dprefix)) - 1));
 642                         addr->addr.in6.s6_addr32[1] = 0;
 643                 }
 644
 645                 tmp = realloc(routes, sizeof(*routes) * (routes_cnt + 1));
 646                 if (!tmp) {
 647                         syslog(LOG_ERR, "Realloc failed for RA route option on %s", iface->name);
 648                         continue;
 649                 }
 650
 651                 routes = tmp;
 652
 653                 memset(&routes[routes_cnt], 0, sizeof(*routes));
 654                 routes[routes_cnt].type = ND_OPT_ROUTE_INFO;
 655                 routes[routes_cnt].len = sizeof(*routes) / 8;
 656                 routes[routes_cnt].prefix = addr->dprefix;
 657                 routes[routes_cnt].flags = 0;
 658                 if (iface->route_preference < 0)
 659                         routes[routes_cnt].flags |= ND_RA_PREF_LOW;
 660                 else if (iface->route_preference > 0)
 661                         routes[routes_cnt].flags |= ND_RA_PREF_HIGH;
 662                 routes[routes_cnt].lifetime = htonl(TIME_LEFT(addr->valid, now));
 663                 routes[routes_cnt].addr[0] = addr->addr.in6.s6_addr32[0];
 664                 routes[routes_cnt].addr[1] = addr->addr.in6.s6_addr32[1];
 665                 routes[routes_cnt].addr[2] = 0;
 666                 routes[routes_cnt].addr[3] = 0;
 667
 668                 ++routes_cnt;
 669         }
 670
 671         search->lifetime = htonl(maxival*10);
 672         dns.lifetime = search->lifetime;
 673
 674         struct icmpv6_opt adv_interval = {
 675                 .type = ND_OPT_RTR_ADV_INTERVAL,
 676                 .len = 1,
 677                 .data = {0, 0, (maxival*1000) >> 24, (maxival*1000) >> 16, (maxival*1000) >> 8, maxival*1000}
 678         };
 679
 680         struct iovec iov[IOV_RA_TOTAL] = {
 681                         [IOV_RA_ADV] = {&adv, sizeof(adv)},
 682                         [IOV_RA_PFXS] = {pfxs, pfxs_cnt * sizeof(*pfxs)},
 683                         [IOV_RA_ROUTES] = {routes, routes_cnt * sizeof(*routes)},
 684                         [IOV_RA_DNS] = {&dns, (dns_cnt) ? sizeof(dns) : 0},
 685                         [IOV_RA_DNS_ADDR] = {dns_addr, dns_cnt * sizeof(*dns_addr)},
 686                         [IOV_RA_SEARCH] = {search, search->len * 8},
 687                         [IOV_RA_ADV_INTERVAL] = {&adv_interval, adv_interval.len * 8}};
 688         struct sockaddr_in6 dest;
 689
 690         memset(&dest, 0, sizeof(dest));
 691         dest.sin6_family = AF_INET6;
 692
 693         if (from && !IN6_IS_ADDR_UNSPECIFIED(from))
 694                 dest.sin6_addr = *from;
 695         else
 696                 inet_pton(AF_INET6, ALL_IPV6_NODES, &dest.sin6_addr);
 697
 698         syslog(LOG_NOTICE, "Sending a RA on %s", iface->name);
 699
 700         odhcpd_send(iface->router_event.uloop.fd, &dest, iov, ARRAY_SIZE(iov), iface);
 701
 702         free(pfxs);
 703         free(routes);
 704
 705         return msecs;
 706 }
 707
 708
 709 static void trigger_router_advert(struct uloop_timeout *event)
 710 {
 711         struct interface *iface = container_of(event, struct interface, timer_rs);
 712         int msecs = send_router_advert(iface, NULL);
 713
 714         /* Rearm timer if not shut down */
 715         if (event->cb)
 716                 uloop_timeout_set(event, msecs);
 717 }
 718
 719
 720 /* Event handler for incoming ICMPv6 packets */
 721 static void handle_icmpv6(void *addr, void *data, size_t len,
 722                 struct interface *iface, _unused void *dest)
 723 {
 724         struct icmp6_hdr *hdr = data;
 725         struct sockaddr_in6 *from = addr;
 726
 727         if (!router_icmpv6_valid(addr, data, len))
 728                 return;
 729
 730         if ((iface->ra == MODE_SERVER && !iface->master)) { /* Server mode */
 731                 if (hdr->icmp6_type == ND_ROUTER_SOLICIT)
 732                         send_router_advert(iface, &from->sin6_addr);
 733         } else if (iface->ra == MODE_RELAY) { /* Relay mode */
 734                 if (hdr->icmp6_type == ND_ROUTER_SOLICIT && !iface->master) {
 735                         struct interface *c;
 736
 737                         avl_for_each_element(&interfaces, c, avl) {
 738                                 if (!c->master || c->ra != MODE_RELAY)
 739                                         continue;
 740
 741                                 forward_router_solicitation(c);
 742                         }
 743                 } else if (hdr->icmp6_type == ND_ROUTER_ADVERT && iface->master)
 744                         forward_router_advertisement(iface, data, len);
 745         }
 746 }
 747
 748
 749 /* Forward router solicitation */
 750 static void forward_router_solicitation(const struct interface *iface)
 751 {
 752         struct icmp6_hdr rs = {ND_ROUTER_SOLICIT, 0, 0, {{0}}};
 753         struct iovec iov = {&rs, sizeof(rs)};
 754         struct sockaddr_in6 all_routers;
 755
 756         if (!iface)
 757                 return;
 758
 759         memset(&all_routers, 0, sizeof(all_routers));
 760         all_routers.sin6_family = AF_INET6;
 761         inet_pton(AF_INET6, ALL_IPV6_ROUTERS, &all_routers.sin6_addr);
 762         all_routers.sin6_scope_id = iface->ifindex;
 763
 764         syslog(LOG_NOTICE, "Sending RS to %s", iface->name);
 765         odhcpd_send(iface->router_event.uloop.fd, &all_routers, &iov, 1, iface);
 766 }
 767
 768
 769 /* Handler for incoming router solicitations on slave interfaces */
 770 static void forward_router_advertisement(const struct interface *iface, uint8_t *data, size_t len)
 771 {
 772         struct nd_router_advert *adv = (struct nd_router_advert *)data;
 773         struct sockaddr_in6 all_nodes;
 774         struct icmpv6_opt *opt;
 775         struct interface *c;
 776         struct iovec iov = { .iov_base = data, .iov_len = len };
 777         /* Rewrite options */
 778         uint8_t *end = data + len;
 779         uint8_t *mac_ptr = NULL;
 780         struct in6_addr *dns_ptr = NULL;
 781         size_t dns_count = 0;
 782
 783         icmpv6_for_each_option(opt, &adv[1], end) {
 784                 if (opt->type == ND_OPT_SOURCE_LINKADDR) {
 785                         /* Store address of source MAC-address */
 786                         mac_ptr = opt->data;
 787                 } else if (opt->type == ND_OPT_RECURSIVE_DNS && opt->len > 1) {
 788                         /* Check if we have to rewrite DNS */
 789                         dns_ptr = (struct in6_addr*)&opt->data[6];
 790                         dns_count = (opt->len - 1) / 2;
 791                 }
 792         }
 793
 794         syslog(LOG_NOTICE, "Got a RA on %s", iface->name);
 795
 796         /* Indicate a proxy, however we don't follow the rest of RFC 4389 yet */
 797         adv->nd_ra_flags_reserved |= ND_RA_FLAG_PROXY;
 798
 799         /* Forward advertisement to all slave interfaces */
 800         memset(&all_nodes, 0, sizeof(all_nodes));
 801         all_nodes.sin6_family = AF_INET6;
 802         inet_pton(AF_INET6, ALL_IPV6_NODES, &all_nodes.sin6_addr);
 803
 804         avl_for_each_element(&interfaces, c, avl) {
 805                 if (c->ra != MODE_RELAY || c->master)
 806                         continue;
 807
 808                 /* Fixup source hardware address option */
 809                 if (mac_ptr)
 810                         odhcpd_get_mac(c, mac_ptr);
 811
 812                 /* If we have to rewrite DNS entries */
 813                 if (c->always_rewrite_dns && dns_ptr && dns_count > 0) {
 814                         const struct in6_addr *rewrite = c->dns;
 815                         struct in6_addr addr;
 816                         size_t rewrite_cnt = c->dns_cnt;
 817
 818                         if (rewrite_cnt == 0) {
 819                                 if (odhcpd_get_interface_dns_addr(c, &addr))
 820                                         continue; /* Unable to comply */
 821
 822                                 rewrite = &addr;
 823                                 rewrite_cnt = 1;
 824                         }
 825
 826                         /* Copy over any other addresses */
 827                         for (size_t i = 0; i < dns_count; ++i) {
 828                                 size_t j = (i < rewrite_cnt) ? i : rewrite_cnt - 1;
 829                                 dns_ptr[i] = rewrite[j];
 830                         }
 831                 }
 832
 833                 syslog(LOG_NOTICE, "Forward a RA on %s", c->name);
 834
 835                 odhcpd_send(c->router_event.uloop.fd, &all_nodes, &iov, 1, c);
 836         }
 837 }