src/router.c

   1 /**
   2  * Copyright (C) 2012-2013 Steven Barth <steven@midlink.org>
   3  *
   4  * This program is free software; you can redistribute it and/or modify
   5  * it under the terms of the GNU General Public License v2 as published by
   6  * the Free Software Foundation.
   7  *
   8  * This program is distributed in the hope that it will be useful,
   9  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  10  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  11  * GNU General Public License for more details.
  12  *
  13  */
  14
  15 #include <errno.h>
  16 #include <fcntl.h>
  17 #include <signal.h>
  18 #include <resolv.h>
  19 #include <stdio.h>
  20 #include <stdlib.h>
  21 #include <unistd.h>
  22 #include <stdbool.h>
  23 #include <arpa/inet.h>
  24 #include <net/route.h>
  25
  26 #include "router.h"
  27 #include "odhcpd.h"
  28
  29
  30 static void forward_router_solicitation(const struct interface *iface);
  31 static void forward_router_advertisement(uint8_t *data, size_t len);
  32
  33 static void handle_icmpv6(void *addr, void *data, size_t len,
  34                 struct interface *iface, void *dest);
  35 static void trigger_router_advert(struct uloop_timeout *event);
  36 static void router_netevent_cb(unsigned long event, struct netevent_handler_info *info);
  37
  38 static struct odhcpd_event router_event = {.uloop = {.fd = -1}, .handle_dgram = handle_icmpv6, };
  39 static struct netevent_handler router_netevent_handler = { .cb = router_netevent_cb, };
  40
  41 static FILE *fp_route = NULL;
  42
  43
  44 #define TIME_LEFT(t1, now) ((t1) != UINT32_MAX ? (t1) - (now) : UINT32_MAX)
  45
  46 int router_init(void)
  47 {
  48         // Open ICMPv6 socket
  49         int sock = socket(AF_INET6, SOCK_RAW | SOCK_CLOEXEC, IPPROTO_ICMPV6);
  50         if (sock < 0 && errno != EAFNOSUPPORT) {
  51                 syslog(LOG_ERR, "Failed to open RAW-socket: %m");
  52                 return -1;
  53         }
  54
  55         // Let the kernel compute our checksums
  56         int val = 2;
  57         setsockopt(sock, IPPROTO_RAW, IPV6_CHECKSUM, &val, sizeof(val));
  58
  59         // This is required by RFC 4861
  60         val = 255;
  61         setsockopt(sock, IPPROTO_IPV6, IPV6_MULTICAST_HOPS, &val, sizeof(val));
  62         setsockopt(sock, IPPROTO_IPV6, IPV6_UNICAST_HOPS, &val, sizeof(val));
  63
  64         // We need to know the source interface
  65         val = 1;
  66         setsockopt(sock, IPPROTO_IPV6, IPV6_RECVPKTINFO, &val, sizeof(val));
  67         setsockopt(sock, IPPROTO_IPV6, IPV6_RECVHOPLIMIT, &val, sizeof(val));
  68
  69         // Don't loop back
  70         val = 0;
  71         setsockopt(sock, IPPROTO_IPV6, IPV6_MULTICAST_LOOP, &val, sizeof(val));
  72
  73         // Filter ICMPv6 package types
  74         struct icmp6_filter filt;
  75         ICMP6_FILTER_SETBLOCKALL(&filt);
  76         ICMP6_FILTER_SETPASS(ND_ROUTER_ADVERT, &filt);
  77         ICMP6_FILTER_SETPASS(ND_ROUTER_SOLICIT, &filt);
  78         setsockopt(sock, IPPROTO_ICMPV6, ICMP6_FILTER, &filt, sizeof(filt));
  79
  80         // Register socket
  81         router_event.uloop.fd = sock;
  82         odhcpd_register(&router_event);
  83
  84         if (!(fp_route = fopen("/proc/net/ipv6_route", "r")))
  85                 syslog(LOG_ERR, "Failed to open routing table: %m");
  86
  87         netlink_add_netevent_handler(&router_netevent_handler);
  88
  89         return 0;
  90 }
  91
  92
  93 int router_setup_interface(struct interface *iface, bool enable)
  94 {
  95         if (!fp_route || router_event.uloop.fd < 0)
  96                 return -1;
  97
  98         struct ipv6_mreq all_nodes = {ALL_IPV6_NODES, iface->ifindex};
  99         struct ipv6_mreq all_routers = {ALL_IPV6_ROUTERS, iface->ifindex};
 100
 101         uloop_timeout_cancel(&iface->timer_rs);
 102         iface->timer_rs.cb = NULL;
 103
 104         if (iface->ifindex <= 0)
 105                 return -1;
 106
 107         setsockopt(router_event.uloop.fd, IPPROTO_IPV6, IPV6_DROP_MEMBERSHIP,
 108                         &all_nodes, sizeof(all_nodes));
 109         setsockopt(router_event.uloop.fd, IPPROTO_IPV6, IPV6_DROP_MEMBERSHIP,
 110                         &all_routers, sizeof(all_routers));
 111
 112         if (!enable) {
 113                 if (iface->ra)
 114                         trigger_router_advert(&iface->timer_rs);
 115         } else {
 116                 void *mreq = &all_routers;
 117
 118                 if (iface->ra == MODE_RELAY && iface->master) {
 119                         mreq = &all_nodes;
 120                         forward_router_solicitation(iface);
 121                 } else if (iface->ra == MODE_SERVER && !iface->master) {
 122                         iface->timer_rs.cb = trigger_router_advert;
 123                         uloop_timeout_set(&iface->timer_rs, 1000);
 124                 }
 125
 126                 if (iface->ra == MODE_RELAY || (iface->ra == MODE_SERVER && !iface->master))
 127                         setsockopt(router_event.uloop.fd, IPPROTO_IPV6,
 128                                         IPV6_ADD_MEMBERSHIP, mreq, sizeof(all_nodes));
 129         }
 130         return 0;
 131 }
 132
 133
 134 static void router_netevent_cb(unsigned long event, struct netevent_handler_info *info)
 135 {
 136         struct interface *iface;
 137
 138         switch (event) {
 139         case NETEV_ROUTE6_ADD:
 140         case NETEV_ROUTE6_DEL:
 141                 if (info->rt.dst_len)
 142                         break;
 143
 144                 list_for_each_entry(iface, &interfaces, head) {
 145                         if (iface->ra == MODE_SERVER && !iface->master)
 146                                 uloop_timeout_set(&iface->timer_rs, 1000);
 147                 }
 148                 break;
 149         case NETEV_ADDR6LIST_CHANGE:
 150                 iface = info->iface;
 151                 if (iface && iface->ra == MODE_SERVER && !iface->master)
 152                         uloop_timeout_set(&iface->timer_rs, 1000);
 153                 break;
 154         default:
 155                 break;
 156         }
 157 }
 158
 159
 160 static bool router_icmpv6_valid(struct sockaddr_in6 *source, uint8_t *data, size_t len)
 161 {
 162         struct icmp6_hdr *hdr = (struct icmp6_hdr *)data;
 163         struct icmpv6_opt *opt, *end = (struct icmpv6_opt*)&data[len];
 164
 165         /* Hoplimit is already checked in odhcpd_receive_packets */
 166         if (len < sizeof(*hdr) || hdr->icmp6_code)
 167                 return false;
 168
 169         switch (hdr->icmp6_type) {
 170         case ND_ROUTER_ADVERT:
 171                 if (!IN6_IS_ADDR_LINKLOCAL(&source->sin6_addr))
 172                         return false;
 173
 174                 opt = (struct icmpv6_opt *)((struct nd_router_advert *)data + 1);
 175                 break;
 176
 177         case ND_ROUTER_SOLICIT:
 178                 opt = (struct icmpv6_opt *)((struct nd_router_solicit *)data + 1);
 179                 break;
 180
 181         default:
 182                 return false;
 183         }
 184
 185         icmpv6_for_each_option(opt, opt, end)
 186                 if (opt->type == ND_OPT_SOURCE_LINKADDR &&
 187                                 IN6_IS_ADDR_UNSPECIFIED(&source->sin6_addr) &&
 188                                 hdr->icmp6_type == ND_ROUTER_SOLICIT)
 189                         return false;
 190
 191         // Check all options parsed successfully
 192         return opt == end;
 193 }
 194
 195
 196 // Detect whether a default route exists, also find the source prefixes
 197 static bool parse_routes(struct odhcpd_ipaddr *n, ssize_t len)
 198 {
 199         rewind(fp_route);
 200
 201         char line[512], ifname[16];
 202         bool found_default = false;
 203         struct odhcpd_ipaddr p = { .addr.in6 = IN6ADDR_ANY_INIT, .prefix = 0,
 204                                         .dprefix = 0, .preferred = 0, .valid = 0};
 205
 206         while (fgets(line, sizeof(line), fp_route)) {
 207                 uint32_t rflags;
 208                 if (sscanf(line, "00000000000000000000000000000000 00 "
 209                                 "%*s %*s %*s %*s %*s %*s %*s %15s", ifname) &&
 210                                 strcmp(ifname, "lo")) {
 211                         found_default = true;
 212                 } else if (sscanf(line, "%8" SCNx32 "%8" SCNx32 "%*8" SCNx32 "%*8" SCNx32 " %hhx %*s "
 213                                 "%*s 00000000000000000000000000000000 %*s %*s %*s %" SCNx32 " lo",
 214                                 &p.addr.in6.s6_addr32[0], &p.addr.in6.s6_addr32[1], &p.prefix, &rflags) &&
 215                                 p.prefix > 0 && (rflags & RTF_NONEXTHOP) && (rflags & RTF_REJECT)) {
 216                         // Find source prefixes by scanning through unreachable-routes
 217                         p.addr.in6.s6_addr32[0] = htonl(p.addr.in6.s6_addr32[0]);
 218                         p.addr.in6.s6_addr32[1] = htonl(p.addr.in6.s6_addr32[1]);
 219
 220                         for (ssize_t i = 0; i < len; ++i) {
 221                                 if (n[i].prefix <= 64 && n[i].prefix >= p.prefix &&
 222                                                 !odhcpd_bmemcmp(&p.addr.in6, &n[i].addr.in6, p.prefix)) {
 223                                         n[i].dprefix = p.prefix;
 224                                         break;
 225                                 }
 226                         }
 227
 228                 }
 229         }
 230
 231         return found_default;
 232 }
 233
 234 static int calc_adv_interval(struct interface *iface, uint32_t minvalid,
 235                 uint32_t *maxival)
 236 {
 237         uint32_t minival = iface->ra_mininterval;
 238         int msecs;
 239
 240         *maxival = iface->ra_maxinterval;
 241
 242         if (*maxival > minvalid/3)
 243                 *maxival = minvalid/3;
 244
 245         if (*maxival > MaxRtrAdvInterval)
 246                 *maxival = MaxRtrAdvInterval;
 247         else if (*maxival < 4)
 248                 *maxival = 4;
 249
 250         if (minival < MinRtrAdvInterval)
 251                 minival = MinRtrAdvInterval;
 252         else if (minival > (*maxival * 3)/4)
 253                 minival = (*maxival >= 9 ? *maxival/3 : *maxival);
 254
 255         odhcpd_urandom(&msecs, sizeof(msecs));
 256         msecs = (labs(msecs) % ((*maxival != minival) ? (*maxival - minival)*1000 : 500)) +
 257                         minival*1000;
 258
 259         return msecs;
 260 }
 261
 262 static uint16_t calc_ra_lifetime(struct interface *iface, uint32_t maxival)
 263 {
 264         uint16_t lifetime = 3*maxival;
 265
 266         if (iface->ra_lifetime >= 0) {
 267                 lifetime = iface->ra_lifetime;
 268                 if (lifetime < maxival)
 269                         lifetime = maxival;
 270                 else if (lifetime > 9000)
 271                         lifetime = 9000;
 272         }
 273
 274         return lifetime;
 275 }
 276
 277 enum {
 278         IOV_RA_ADV=0,
 279         IOV_RA_PFXS,
 280         IOV_RA_ROUTES,
 281         IOV_RA_DNS,
 282         IOV_RA_DNS_ADDR,
 283         IOV_RA_SEARCH,
 284         IOV_RA_ADV_INTERVAL,
 285         IOV_RA_TOTAL,
 286 };
 287
 288 // Router Advert server mode
 289 static uint64_t send_router_advert(struct interface *iface, const struct in6_addr *from)
 290 {
 291         time_t now = odhcpd_time();
 292         int mtu = iface->ra_mtu;
 293         int hlim = iface->ra_hoplimit;
 294
 295         if (mtu == 0)
 296                 mtu = odhcpd_get_interface_config(iface->ifname, "mtu");
 297
 298         if (mtu < 1280)
 299                 mtu = 1280;
 300
 301         if (hlim == 0)
 302                 hlim = odhcpd_get_interface_config(iface->ifname, "hop_limit");
 303
 304         struct {
 305                 struct nd_router_advert h;
 306                 struct icmpv6_opt lladdr;
 307                 struct nd_opt_mtu mtu;
 308         } adv = {
 309                 .h = {{.icmp6_type = ND_ROUTER_ADVERT, .icmp6_code = 0}, 0, 0},
 310                 .lladdr = {ND_OPT_SOURCE_LINKADDR, 1, {0}},
 311                 .mtu = {ND_OPT_MTU, 1, 0, htonl(mtu)},
 312         };
 313
 314         if (hlim > 0)
 315                 adv.h.nd_ra_curhoplimit = hlim;
 316
 317         if (iface->dhcpv6)
 318                 adv.h.nd_ra_flags_reserved = ND_RA_FLAG_OTHER;
 319
 320         if (iface->ra_managed >= RA_MANAGED_MFLAG)
 321                 adv.h.nd_ra_flags_reserved |= ND_RA_FLAG_MANAGED;
 322
 323         if (iface->route_preference < 0)
 324                 adv.h.nd_ra_flags_reserved |= ND_RA_PREF_LOW;
 325         else if (iface->route_preference > 0)
 326                 adv.h.nd_ra_flags_reserved |= ND_RA_PREF_HIGH;
 327
 328         adv.h.nd_ra_reachable = htonl(iface->ra_reachabletime);
 329         adv.h.nd_ra_retransmit = htonl(iface->ra_retranstime);
 330
 331         odhcpd_get_mac(iface, adv.lladdr.data);
 332
 333         // If not currently shutting down
 334         struct odhcpd_ipaddr *addrs = NULL;
 335         ssize_t ipcnt = 0;
 336         uint32_t minvalid = UINT32_MAX;
 337         bool default_route = false;
 338         bool valid_prefix = false;
 339
 340         // If not shutdown
 341         if (iface->timer_rs.cb) {
 342                 size_t size = sizeof(*addrs) * iface->addr6_len;
 343                 addrs = alloca(size);
 344                 memcpy(addrs, iface->addr6, size);
 345
 346                 ipcnt = iface->addr6_len;
 347
 348                 // Check default route
 349                 if (iface->default_router) {
 350                         default_route = true;
 351
 352                         if (iface->default_router > 1)
 353                                 valid_prefix = true;
 354                 } else if (parse_routes(addrs, ipcnt))
 355                         default_route = true;
 356         }
 357
 358
 359         struct in6_addr dns_pref, *dns_addr = &dns_pref;
 360         size_t dns_cnt = 1;
 361
 362         odhcpd_get_interface_dns_addr(iface, &dns_pref);
 363
 364         // Construct Prefix Information options
 365         size_t pfxs_cnt = 0;
 366         struct nd_opt_prefix_info *pfxs = NULL;
 367
 368         for (ssize_t i = 0; i < ipcnt; ++i) {
 369                 struct odhcpd_ipaddr *addr = &addrs[i];
 370                 uint32_t preferred = 0;
 371                 uint32_t valid = 0;
 372
 373                 if (addr->prefix > 96 || addr->valid <= (uint32_t)now) {
 374                         char namebuf[INET6_ADDRSTRLEN];
 375
 376                         inet_ntop(AF_INET6, &addr->addr.in6, namebuf, sizeof(namebuf));
 377                         syslog(LOG_INFO, "Address %s (prefix %d, valid %u) not suitable as RA prefix on %s",
 378                                         namebuf, addr->prefix, addr->valid, iface->ifname);
 379                         continue;
 380                 }
 381
 382                 if (odhcpd_bmemcmp(&addr->addr, &iface->pio_filter_addr,
 383                                 iface->pio_filter_length) != 0 ||
 384                                 addr->prefix < iface->pio_filter_length)
 385                         continue; // PIO filtered out of this RA
 386
 387                 struct nd_opt_prefix_info *p = NULL;
 388                 for (size_t i = 0; i < pfxs_cnt; ++i) {
 389                         if (addr->prefix == pfxs[i].nd_opt_pi_prefix_len &&
 390                                         !odhcpd_bmemcmp(&pfxs[i].nd_opt_pi_prefix,
 391                                         &addr->addr.in6, addr->prefix))
 392                                 p = &pfxs[i];
 393                 }
 394
 395                 if (!p) {
 396                         struct nd_opt_prefix_info *tmp;
 397
 398                         tmp = realloc(pfxs, sizeof(*pfxs) * (pfxs_cnt + 1));
 399                         if (!tmp) {
 400                                 syslog(LOG_ERR, "Realloc failed for RA prefix option on interface %s", iface->ifname);
 401                                 continue;
 402                         }
 403
 404                         pfxs = tmp;
 405                         p = &pfxs[pfxs_cnt++];
 406                         memset(p, 0, sizeof(*p));
 407                 }
 408
 409                 if (addr->preferred > (uint32_t)now) {
 410                         preferred = TIME_LEFT(addr->preferred, now);
 411
 412                         if (iface->ra_useleasetime &&
 413                                         preferred > iface->dhcpv4_leasetime)
 414                                 preferred = iface->dhcpv4_leasetime;
 415                 }
 416
 417                 valid = TIME_LEFT(addr->valid, now);
 418                 if (iface->ra_useleasetime && valid > iface->dhcpv4_leasetime)
 419                         valid = iface->dhcpv4_leasetime;
 420
 421                 if (minvalid > valid)
 422                         minvalid = valid;
 423
 424                 if (!IN6_IS_ADDR_ULA(&addr->addr.in6) || iface->default_router)
 425                         valid_prefix = true;
 426
 427                 odhcpd_bmemcpy(&p->nd_opt_pi_prefix, &addr->addr.in6,
 428                                 (iface->ra_advrouter) ? 128 : addr->prefix);
 429                 p->nd_opt_pi_type = ND_OPT_PREFIX_INFORMATION;
 430                 p->nd_opt_pi_len = 4;
 431                 p->nd_opt_pi_prefix_len = (addr->prefix < 64) ? 64 : addr->prefix;
 432                 p->nd_opt_pi_flags_reserved = 0;
 433                 if (!iface->ra_not_onlink)
 434                         p->nd_opt_pi_flags_reserved |= ND_OPT_PI_FLAG_ONLINK;
 435                 if (iface->ra_managed < RA_MANAGED_NO_AFLAG && addr->prefix <= 64)
 436                         p->nd_opt_pi_flags_reserved |= ND_OPT_PI_FLAG_AUTO;
 437                 if (iface->ra_advrouter)
 438                         p->nd_opt_pi_flags_reserved |= ND_OPT_PI_FLAG_RADDR;
 439                 p->nd_opt_pi_preferred_time = htonl(preferred);
 440                 p->nd_opt_pi_valid_time = htonl(valid);
 441         }
 442
 443         // Calculate periodic transmit
 444         uint32_t maxival;
 445         int msecs = calc_adv_interval(iface, minvalid, &maxival);
 446
 447         if (default_route) {
 448                 if (!valid_prefix) {
 449                         syslog(LOG_WARNING, "A default route is present but there is no public prefix "
 450                                         "on %s thus we don't announce a default route!", iface->ifname);
 451                         adv.h.nd_ra_router_lifetime = 0;
 452                 } else
 453                         adv.h.nd_ra_router_lifetime = htons(calc_ra_lifetime(iface, maxival));
 454
 455         } else
 456                 adv.h.nd_ra_router_lifetime = 0;
 457
 458         syslog(LOG_INFO, "Using a RA lifetime of %d seconds on %s", ntohs(adv.h.nd_ra_router_lifetime), iface->ifname);
 459
 460         // DNS Recursive DNS
 461         if (iface->dns_cnt > 0) {
 462                 dns_addr = iface->dns;
 463                 dns_cnt = iface->dns_cnt;
 464         }
 465
 466         if (!dns_addr || IN6_IS_ADDR_UNSPECIFIED(dns_addr))
 467                 dns_cnt = 0;
 468
 469         struct {
 470                 uint8_t type;
 471                 uint8_t len;
 472                 uint8_t pad;
 473                 uint8_t pad2;
 474                 uint32_t lifetime;
 475         } dns = {ND_OPT_RECURSIVE_DNS, (1 + (2 * dns_cnt)), 0, 0, 0};
 476
 477         // DNS Search options
 478         uint8_t search_buf[256], *search_domain = iface->search;
 479         size_t search_len = iface->search_len, search_padded = 0;
 480
 481         if (!search_domain && !res_init() && _res.dnsrch[0] && _res.dnsrch[0][0]) {
 482                 int len = dn_comp(_res.dnsrch[0], search_buf,
 483                                 sizeof(search_buf), NULL, NULL);
 484                 if (len > 0) {
 485                         search_domain = search_buf;
 486                         search_len = len;
 487                 }
 488         }
 489
 490         if (search_len > 0)
 491                 search_padded = ((search_len + 7) & (~7)) + 8;
 492
 493         struct {
 494                 uint8_t type;
 495                 uint8_t len;
 496                 uint8_t pad;
 497                 uint8_t pad2;
 498                 uint32_t lifetime;
 499                 uint8_t name[];
 500         } *search = alloca(sizeof(*search) + search_padded);
 501
 502         search->type = ND_OPT_DNS_SEARCH;
 503         search->len = search_len ? ((sizeof(*search) + search_padded) / 8) : 0;
 504         search->pad = 0;
 505         search->pad2 = 0;
 506         memcpy(search->name, search_domain, search_len);
 507         memset(&search->name[search_len], 0, search_padded - search_len);
 508
 509
 510         size_t routes_cnt = 0;
 511         struct {
 512                 uint8_t type;
 513                 uint8_t len;
 514                 uint8_t prefix;
 515                 uint8_t flags;
 516                 uint32_t lifetime;
 517                 uint32_t addr[4];
 518         } *tmp, *routes = NULL;
 519
 520         for (ssize_t i = 0; i < ipcnt; ++i) {
 521                 struct odhcpd_ipaddr *addr = &addrs[i];
 522                 if (addr->dprefix > 64 || addr->dprefix == 0 || addr->valid <= (uint32_t)now ||
 523                                 (addr->dprefix == 64 && addr->prefix == 64)) {
 524                         continue; // Address not suitable
 525                 } else if (addr->dprefix > 32) {
 526                         addr->addr.in6.s6_addr32[1] &= htonl(~((1U << (64 - addr->dprefix)) - 1));
 527                 } else if (addr->dprefix <= 32) {
 528                         addr->addr.in6.s6_addr32[0] &= htonl(~((1U << (32 - addr->dprefix)) - 1));
 529                         addr->addr.in6.s6_addr32[1] = 0;
 530                 }
 531
 532                 tmp = realloc(routes, sizeof(*routes) * (routes_cnt + 1));
 533                 if (!tmp) {
 534                         syslog(LOG_ERR, "Realloc failed for RA route option on interface %s", iface->ifname);
 535                         continue;
 536                 }
 537
 538                 routes = tmp;
 539
 540                 memset(&routes[routes_cnt], 0, sizeof(*routes));
 541                 routes[routes_cnt].type = ND_OPT_ROUTE_INFO;
 542                 routes[routes_cnt].len = sizeof(*routes) / 8;
 543                 routes[routes_cnt].prefix = addr->dprefix;
 544                 routes[routes_cnt].flags = 0;
 545                 if (iface->route_preference < 0)
 546                         routes[routes_cnt].flags |= ND_RA_PREF_LOW;
 547                 else if (iface->route_preference > 0)
 548                         routes[routes_cnt].flags |= ND_RA_PREF_HIGH;
 549                 routes[routes_cnt].lifetime = htonl(TIME_LEFT(addr->valid, now));
 550                 routes[routes_cnt].addr[0] = addr->addr.in6.s6_addr32[0];
 551                 routes[routes_cnt].addr[1] = addr->addr.in6.s6_addr32[1];
 552                 routes[routes_cnt].addr[2] = 0;
 553                 routes[routes_cnt].addr[3] = 0;
 554
 555                 ++routes_cnt;
 556         }
 557
 558         search->lifetime = htonl(maxival*10);
 559         dns.lifetime = search->lifetime;
 560
 561         struct icmpv6_opt adv_interval = {
 562                 .type = ND_OPT_RTR_ADV_INTERVAL,
 563                 .len = 1,
 564                 .data = {0, 0, (maxival*1000) >> 24, (maxival*1000) >> 16, (maxival*1000) >> 8, maxival*1000}
 565         };
 566
 567         struct iovec iov[IOV_RA_TOTAL] = {
 568                         [IOV_RA_ADV] = {&adv, sizeof(adv)},
 569                         [IOV_RA_PFXS] = {pfxs, pfxs_cnt * sizeof(*pfxs)},
 570                         [IOV_RA_ROUTES] = {routes, routes_cnt * sizeof(*routes)},
 571                         [IOV_RA_DNS] = {&dns, (dns_cnt) ? sizeof(dns) : 0},
 572                         [IOV_RA_DNS_ADDR] = {dns_addr, dns_cnt * sizeof(*dns_addr)},
 573                         [IOV_RA_SEARCH] = {search, search->len * 8},
 574                         [IOV_RA_ADV_INTERVAL] = {&adv_interval, adv_interval.len * 8}};
 575         struct sockaddr_in6 dest = {AF_INET6, 0, 0, ALL_IPV6_NODES, 0};
 576
 577         if (from && !IN6_IS_ADDR_UNSPECIFIED(from))
 578                 dest.sin6_addr = *from;
 579
 580         odhcpd_send(router_event.uloop.fd,
 581                         &dest, iov, ARRAY_SIZE(iov), iface);
 582
 583         free(pfxs);
 584         free(routes);
 585
 586         return msecs;
 587 }
 588
 589
 590 static void trigger_router_advert(struct uloop_timeout *event)
 591 {
 592         struct interface *iface = container_of(event, struct interface, timer_rs);
 593         int msecs = send_router_advert(iface, NULL);
 594
 595         // Rearm timer if not shut down
 596         if (event->cb)
 597                 uloop_timeout_set(event, msecs);
 598 }
 599
 600
 601 // Event handler for incoming ICMPv6 packets
 602 static void handle_icmpv6(void *addr, void *data, size_t len,
 603                 struct interface *iface, _unused void *dest)
 604 {
 605         struct icmp6_hdr *hdr = data;
 606         struct sockaddr_in6 *from = addr;
 607
 608         if (!router_icmpv6_valid(addr, data, len))
 609                 return;
 610
 611         if ((iface->ra == MODE_SERVER && !iface->master)) { // Server mode
 612                 if (hdr->icmp6_type == ND_ROUTER_SOLICIT)
 613                         send_router_advert(iface, &from->sin6_addr);
 614         } else if (iface->ra == MODE_RELAY) { // Relay mode
 615                 if (hdr->icmp6_type == ND_ROUTER_ADVERT && iface->master)
 616                         forward_router_advertisement(data, len);
 617                 else if (hdr->icmp6_type == ND_ROUTER_SOLICIT && !iface->master)
 618                         forward_router_solicitation(odhcpd_get_master_interface());
 619         }
 620 }
 621
 622
 623 // Forward router solicitation
 624 static void forward_router_solicitation(const struct interface *iface)
 625 {
 626         if (!iface)
 627                 return;
 628
 629         struct icmp6_hdr rs = {ND_ROUTER_SOLICIT, 0, 0, {{0}}};
 630         struct iovec iov = {&rs, sizeof(rs)};
 631         struct sockaddr_in6 all_routers =
 632                 {AF_INET6, 0, 0, ALL_IPV6_ROUTERS, iface->ifindex};
 633
 634         syslog(LOG_NOTICE, "Sending RS to %s", iface->ifname);
 635         odhcpd_send(router_event.uloop.fd, &all_routers, &iov, 1, iface);
 636 }
 637
 638
 639 // Handler for incoming router solicitations on slave interfaces
 640 static void forward_router_advertisement(uint8_t *data, size_t len)
 641 {
 642         struct nd_router_advert *adv = (struct nd_router_advert *)data;
 643
 644         // Rewrite options
 645         uint8_t *end = data + len;
 646         uint8_t *mac_ptr = NULL;
 647         struct in6_addr *dns_ptr = NULL;
 648         size_t dns_count = 0;
 649
 650         struct icmpv6_opt *opt;
 651         icmpv6_for_each_option(opt, &adv[1], end) {
 652                 if (opt->type == ND_OPT_SOURCE_LINKADDR) {
 653                         // Store address of source MAC-address
 654                         mac_ptr = opt->data;
 655                 } else if (opt->type == ND_OPT_RECURSIVE_DNS && opt->len > 1) {
 656                         // Check if we have to rewrite DNS
 657                         dns_ptr = (struct in6_addr*)&opt->data[6];
 658                         dns_count = (opt->len - 1) / 2;
 659                 }
 660         }
 661
 662         syslog(LOG_NOTICE, "Got a RA");
 663
 664         // Indicate a proxy, however we don't follow the rest of RFC 4389 yet
 665         adv->nd_ra_flags_reserved |= ND_RA_FLAG_PROXY;
 666
 667         // Forward advertisement to all slave interfaces
 668         struct sockaddr_in6 all_nodes = {AF_INET6, 0, 0, ALL_IPV6_NODES, 0};
 669         struct iovec iov = {data, len};
 670
 671         struct interface *iface;
 672         list_for_each_entry(iface, &interfaces, head) {
 673                 if (iface->ra != MODE_RELAY || iface->master)
 674                         continue;
 675
 676                 // Fixup source hardware address option
 677                 if (mac_ptr)
 678                         odhcpd_get_mac(iface, mac_ptr);
 679
 680                 // If we have to rewrite DNS entries
 681                 if (iface->always_rewrite_dns && dns_ptr && dns_count > 0) {
 682                         const struct in6_addr *rewrite = iface->dns;
 683                         struct in6_addr addr;
 684                         size_t rewrite_cnt = iface->dns_cnt;
 685
 686                         if (rewrite_cnt == 0) {
 687                                 if (odhcpd_get_interface_dns_addr(iface, &addr))
 688                                         continue; // Unable to comply
 689
 690                                 rewrite = &addr;
 691                                 rewrite_cnt = 1;
 692                         }
 693
 694                         // Copy over any other addresses
 695                         for (size_t i = 0; i < dns_count; ++i) {
 696                                 size_t j = (i < rewrite_cnt) ? i : rewrite_cnt - 1;
 697                                 dns_ptr[i] = rewrite[j];
 698                         }
 699                 }
 700
 701                 odhcpd_send(router_event.uloop.fd, &all_nodes, &iov, 1, iface);
 702         }
 703 }