src/dhcpv6.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 <time.h>
  16 #include <fcntl.h>
  17 #include <errno.h>
  18 #include <stdlib.h>
  19 #include <signal.h>
  20 #include <limits.h>
  21 #include <resolv.h>
  22 #include <string.h>
  23 #include <unistd.h>
  24 #include <syslog.h>
  25 #include <stdbool.h>
  26 #include <sys/time.h>
  27 #include <sys/ioctl.h>
  28 #include <sys/socket.h>
  29 #include <netinet/in.h>
  30
  31 #include <net/if.h>
  32 #include <net/ethernet.h>
  33
  34 #include "odhcp6c.h"
  35 #include "md5.h"
  36
  37
  38 #define ALL_DHCPV6_RELAYS {{{0xff, 0x02, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,\
  39                 0x00, 0x00, 0x00, 0x00, 0x00, 0x01, 0x00, 0x02}}}
  40 #define DHCPV6_CLIENT_PORT 546
  41 #define DHCPV6_SERVER_PORT 547
  42 #define DHCPV6_DUID_LLADDR 3
  43 #define DHCPV6_REQ_DELAY 1
  44
  45
  46 static bool dhcpv6_response_is_valid(const void *buf, ssize_t len,
  47                 const uint8_t transaction[3], enum dhcpv6_msg type);
  48
  49 static uint32_t dhcpv6_parse_ia(void *opt, void *end);
  50
  51 static reply_handler dhcpv6_handle_reply;
  52 static reply_handler dhcpv6_handle_advert;
  53 static reply_handler dhcpv6_handle_rebind_reply;
  54 static reply_handler dhcpv6_handle_reconfigure;
  55 static int dhcpv6_commit_advert(void);
  56
  57
  58
  59 // RFC 3315 - 5.5 Timeout and Delay values
  60 static struct dhcpv6_retx dhcpv6_retx[_DHCPV6_MSG_MAX] = {
  61         [DHCPV6_MSG_UNKNOWN] = {false, 1, 120, "<POLL>",
  62                         dhcpv6_handle_reconfigure, NULL},
  63         [DHCPV6_MSG_SOLICIT] = {true, 1, 3600, "SOLICIT",
  64                         dhcpv6_handle_advert, dhcpv6_commit_advert},
  65         [DHCPV6_MSG_REQUEST] = {true, 30, 10, "REQUEST",
  66                         dhcpv6_handle_reply, NULL},
  67         [DHCPV6_MSG_RENEW] = {false, 10, 600, "RENEW",
  68                         dhcpv6_handle_reply, NULL},
  69         [DHCPV6_MSG_REBIND] = {false, 10, 600, "REBIND",
  70                         dhcpv6_handle_rebind_reply, NULL},
  71         [DHCPV6_MSG_RELEASE] = {false, 1, 600, "RELEASE", NULL, NULL},
  72         [DHCPV6_MSG_DECLINE] = {false, 1, 3, "DECLINE", NULL, NULL},
  73         [DHCPV6_MSG_INFO_REQ] = {true, 1, 120, "INFOREQ",
  74                         dhcpv6_handle_reply, NULL},
  75 };
  76
  77
  78 // Sockets
  79 static int sock = -1;
  80 static int ifindex = -1;
  81 static int64_t t1 = 0, t2 = 0, t3 = 0;
  82
  83 // IA states
  84 static int request_prefix = -1;
  85 static enum odhcp6c_ia_mode na_mode = IA_MODE_NONE;
  86 static bool accept_reconfig = false;
  87
  88 // Reconfigure key
  89 static uint8_t reconf_key[16];
  90
  91
  92
  93 int init_dhcpv6(const char *ifname, int request_pd)
  94 {
  95         request_prefix = request_pd;
  96
  97         sock = socket(AF_INET6, SOCK_DGRAM | SOCK_CLOEXEC, IPPROTO_UDP);
  98
  99         // Detect interface
 100         struct ifreq ifr;
 101         strncpy(ifr.ifr_name, ifname, sizeof(ifr.ifr_name));
 102         if (ioctl(sock, SIOCGIFINDEX, &ifr))
 103                 return -1;
 104         ifindex = ifr.ifr_ifindex;
 105
 106         // Create client DUID
 107         size_t client_id_len;
 108         odhcp6c_get_state(STATE_CLIENT_ID, &client_id_len);
 109         if (client_id_len == 0) {
 110                 ioctl(sock, SIOCGIFHWADDR, &ifr);
 111                 uint8_t duid[14] = {0, DHCPV6_OPT_CLIENTID, 0, 10, 0,
 112                                 DHCPV6_DUID_LLADDR, 0, 1};
 113                 memcpy(&duid[8], ifr.ifr_hwaddr.sa_data, ETHER_ADDR_LEN);
 114
 115                 uint8_t zero[ETHER_ADDR_LEN] = {0, 0, 0, 0, 0, 0};
 116                 struct ifreq ifs[100], *ifp, *ifend;
 117                 struct ifconf ifc;
 118                 ifc.ifc_req = ifs;
 119                 ifc.ifc_len = sizeof(ifs);
 120
 121                 if (!memcmp(&duid[8], zero, ETHER_ADDR_LEN) &&
 122                                 ioctl(sock, SIOCGIFCONF, &ifc) >= 0) {
 123                         // If our interface doesn't have an address...
 124                         ifend = ifs + (ifc.ifc_len / sizeof(struct ifreq));
 125                         for (ifp = ifc.ifc_req; ifp < ifend &&
 126                                         !memcmp(&duid[8], zero, 6); ifp++) {
 127                                 memcpy(ifr.ifr_name, ifp->ifr_name,
 128                                                 sizeof(ifr.ifr_name));
 129                                 ioctl(sock, SIOCGIFHWADDR, &ifr);
 130                                 memcpy(&duid[8], ifr.ifr_hwaddr.sa_data,
 131                                                 ETHER_ADDR_LEN);
 132                         }
 133                 }
 134
 135                 odhcp6c_add_state(STATE_CLIENT_ID, duid, sizeof(duid));
 136         }
 137
 138         // Create ORO
 139         uint16_t oro[] = {
 140                         htons(DHCPV6_OPT_SIP_SERVER_D),
 141                         htons(DHCPV6_OPT_SIP_SERVER_A),
 142                         htons(DHCPV6_OPT_DNS_SERVERS),
 143                         htons(DHCPV6_OPT_DNS_DOMAIN),
 144                         htons(DHCPV6_OPT_NTP_SERVER),
 145                         htons(DHCPV6_OPT_AFTR_NAME),
 146                         htons(DHCPV6_OPT_PD_EXCLUDE),
 147         };
 148         odhcp6c_add_state(STATE_ORO, oro, sizeof(oro));
 149
 150
 151         // Configure IPv6-options
 152         int val = 1;
 153         setsockopt(sock, IPPROTO_IPV6, IPV6_V6ONLY, &val, sizeof(val));
 154         setsockopt(sock, SOL_SOCKET, SO_REUSEADDR, &val, sizeof(val));
 155         setsockopt(sock, SOL_SOCKET, SO_BINDTODEVICE, ifname, strlen(ifname));
 156
 157         struct sockaddr_in6 client_addr = { .sin6_family = AF_INET6,
 158                 .sin6_port = htons(DHCPV6_CLIENT_PORT), .sin6_flowinfo = 0 };
 159         if (bind(sock, (struct sockaddr*)&client_addr, sizeof(client_addr)))
 160                 return -1;
 161
 162         return 0;
 163 }
 164
 165
 166 void dhcpv6_set_ia_na_mode(enum odhcp6c_ia_mode mode)
 167 {
 168         na_mode = mode;
 169 }
 170
 171
 172 static void dhcpv6_send(enum dhcpv6_msg type, uint8_t trid[3], uint32_t ecs)
 173 {
 174         // Build FQDN
 175         char fqdn_buf[256];
 176         gethostname(fqdn_buf, sizeof(fqdn_buf));
 177         struct {
 178                 uint16_t type;
 179                 uint16_t len;
 180                 uint8_t flags;
 181                 uint8_t data[256];
 182         } fqdn;
 183         size_t fqdn_len = 5 + dn_comp(fqdn_buf, fqdn.data,
 184                         sizeof(fqdn.data), NULL, NULL);
 185         fqdn.type = htons(DHCPV6_OPT_FQDN);
 186         fqdn.len = htons(fqdn_len - 4);
 187         fqdn.flags = 0;
 188
 189
 190         // Build Client ID
 191         size_t cl_id_len;
 192         void *cl_id = odhcp6c_get_state(STATE_CLIENT_ID, &cl_id_len);
 193
 194         // Get Server ID
 195         size_t srv_id_len;
 196         void *srv_id = odhcp6c_get_state(STATE_SERVER_ID, &srv_id_len);
 197
 198         // Build IA_PDs
 199         size_t ia_pd_entries, ia_pd_len = 0;
 200         struct odhcp6c_entry *e = odhcp6c_get_state(STATE_IA_PD, &ia_pd_entries);
 201         ia_pd_entries /= sizeof(*e);
 202         struct dhcpv6_ia_hdr hdr_ia_pd = {
 203                 htons(DHCPV6_OPT_IA_PD),
 204                 htons(sizeof(hdr_ia_pd) - 4),
 205                 1, 0, 0
 206         };
 207
 208
 209         uint8_t *ia_pd = alloca(ia_pd_entries * (sizeof(struct dhcpv6_ia_prefix) + 10));
 210         for (size_t i = 0; i < ia_pd_entries; ++i) {
 211                 uint8_t ex_len = 0;
 212                 if (e[i].priority > 0)
 213                         ex_len = ((e[i].priority - e[i].length - 1) / 8) + 6;
 214
 215                 struct dhcpv6_ia_prefix p = {
 216                         .type = htons(DHCPV6_OPT_IA_PREFIX),
 217                         .len = htons(sizeof(p) - 4U + ex_len),
 218                         .prefix = e[i].length,
 219                         .addr = e[i].target
 220                 };
 221
 222                 memcpy(ia_pd + ia_pd_len, &p, sizeof(p));
 223                 ia_pd_len += sizeof(p);
 224
 225                 if (ex_len) {
 226                         ia_pd[ia_pd_len++] = 0;
 227                         ia_pd[ia_pd_len++] = DHCPV6_OPT_PD_EXCLUDE;
 228                         ia_pd[ia_pd_len++] = 0;
 229                         ia_pd[ia_pd_len++] = ex_len - 4;
 230                         ia_pd[ia_pd_len++] = e[i].priority;
 231
 232                         uint32_t excl = ntohl(e[i].router.s6_addr32[1]);
 233                         excl >>= (64 - e[i].priority);
 234                         excl <<= 8 - ((e[i].priority - e[i].length) % 8);
 235
 236                         for (size_t i = ex_len - 5; i > 0; --i, excl >>= 8)
 237                                 ia_pd[ia_pd_len + i] = excl & 0xff;
 238                         ia_pd_len += ex_len - 5;
 239                 }
 240         }
 241
 242         struct dhcpv6_ia_prefix pref = {
 243                 .type = htons(DHCPV6_OPT_IA_PREFIX),
 244                 .len = htons(25), .prefix = request_prefix
 245         };
 246         if (request_prefix > 0 && ia_pd_len == 0 &&
 247                         (type == DHCPV6_MSG_SOLICIT ||
 248                         type == DHCPV6_MSG_REQUEST)) {
 249                 ia_pd = (uint8_t*)&pref;
 250                 ia_pd_len = sizeof(pref);
 251         }
 252         hdr_ia_pd.len = htons(ntohs(hdr_ia_pd.len) + ia_pd_len);
 253
 254         // Build IA_NAs
 255         size_t ia_na_entries, ia_na_len = 0;
 256         void *ia_na = NULL;
 257         e = odhcp6c_get_state(STATE_IA_NA, &ia_na_entries);
 258         ia_na_entries /= sizeof(*e);
 259
 260         struct dhcpv6_ia_hdr hdr_ia_na = {
 261                 htons(DHCPV6_OPT_IA_NA),
 262                 htons(sizeof(hdr_ia_na) - 4),
 263                 1, 0, 0
 264         };
 265
 266         struct dhcpv6_ia_addr pa[ia_na_entries];
 267         for (size_t i = 0; i < ia_na_entries; ++i) {
 268                 pa[i].type = htons(DHCPV6_OPT_IA_ADDR);
 269                 pa[i].len = htons(sizeof(pa[i]) - 4U);
 270                 pa[i].addr = e[i].target;
 271                 pa[i].preferred = 0;
 272                 pa[i].valid = 0;
 273         }
 274
 275         ia_na = pa;
 276         ia_na_len = sizeof(pa);
 277         hdr_ia_na.len = htons(ntohs(hdr_ia_na.len) + ia_na_len);
 278
 279         // Reconfigure Accept
 280         struct {
 281                 uint16_t type;
 282                 uint16_t length;
 283         } reconf_accept = {htons(DHCPV6_OPT_RECONF_ACCEPT), 0};
 284
 285         // Request Information Refresh
 286         uint16_t oro_refresh = htons(DHCPV6_OPT_INFO_REFRESH);
 287
 288         // Prepare Header
 289         size_t oro_len;
 290         void *oro = odhcp6c_get_state(STATE_ORO, &oro_len);
 291         struct {
 292                 uint8_t type;
 293                 uint8_t trid[3];
 294                 uint16_t elapsed_type;
 295                 uint16_t elapsed_len;
 296                 uint16_t elapsed_value;
 297                 uint16_t oro_type;
 298                 uint16_t oro_len;
 299         } hdr = {
 300                 type, {trid[0], trid[1], trid[2]},
 301                 htons(DHCPV6_OPT_ELAPSED), htons(2),
 302                         htons((ecs > 0xffff) ? 0xffff : ecs),
 303                 htons(DHCPV6_OPT_ORO), htons(oro_len),
 304         };
 305
 306         struct iovec iov[] = {
 307                 {&hdr, sizeof(hdr)},
 308                 {oro, oro_len},
 309                 {&oro_refresh, 0},
 310                 {cl_id, cl_id_len},
 311                 {srv_id, srv_id_len},
 312                 {&reconf_accept, sizeof(reconf_accept)},
 313                 {&fqdn, fqdn_len},
 314                 {&hdr_ia_na, sizeof(hdr_ia_na)},
 315                 {ia_na, ia_na_len},
 316                 {&hdr_ia_pd, sizeof(hdr_ia_pd)},
 317                 {ia_pd, ia_pd_len},
 318         };
 319
 320         size_t cnt = ARRAY_SIZE(iov);
 321         if (type == DHCPV6_MSG_INFO_REQ) {
 322                 cnt = 5;
 323                 iov[2].iov_len = sizeof(oro_refresh);
 324                 hdr.oro_len = htons(oro_len + sizeof(oro_refresh));
 325         } else if (!request_prefix) {
 326                 cnt = 9;
 327         }
 328
 329         // Disable IAs if not used
 330         if (type != DHCPV6_MSG_REQUEST && type != DHCPV6_MSG_SOLICIT) {
 331                 iov[5].iov_len = 0;
 332                 if (ia_na_len == 0)
 333                         iov[7].iov_len = 0;
 334                 if (ia_pd_len == 0)
 335                         iov[9].iov_len = 0;
 336         }
 337
 338         if (na_mode == IA_MODE_NONE)
 339                 iov[7].iov_len = 0;
 340
 341         struct sockaddr_in6 srv = {AF_INET6, htons(DHCPV6_SERVER_PORT),
 342                 0, ALL_DHCPV6_RELAYS, ifindex};
 343         struct msghdr msg = {&srv, sizeof(srv), iov, cnt, NULL, 0, 0};
 344
 345         sendmsg(sock, &msg, 0);
 346 }
 347
 348
 349 static int64_t dhcpv6_rand_delay(int64_t time)
 350 {
 351         int random;
 352         odhcp6c_random(&random, sizeof(random));
 353         return (time * ((int64_t)random % 1000LL)) / 10000LL;
 354 }
 355
 356
 357 int dhcpv6_request(enum dhcpv6_msg type)
 358 {
 359         uint8_t buf[1536];
 360         uint64_t timeout = UINT32_MAX;
 361         struct dhcpv6_retx *retx = &dhcpv6_retx[type];
 362
 363         if (retx->delay) {
 364                 struct timespec ts = {0, 0};
 365                 ts.tv_nsec = dhcpv6_rand_delay(10 * DHCPV6_REQ_DELAY);
 366                 nanosleep(&ts, NULL);
 367         }
 368
 369         if (type == DHCPV6_MSG_RELEASE || type == DHCPV6_MSG_DECLINE)
 370                 timeout = 3;
 371         else if (type == DHCPV6_MSG_UNKNOWN)
 372                 timeout = t1;
 373         else if (type == DHCPV6_MSG_RENEW)
 374                 timeout = (t2 > t1) ? t2 - t1 : 0;
 375         else if (type == DHCPV6_MSG_REBIND)
 376                 timeout = (t3 > t2) ? t3 - t2 : 0;
 377
 378         if (timeout == 0)
 379                 return -1;
 380
 381         syslog(LOG_NOTICE, "Sending %s (timeout %us)", retx->name, (unsigned)timeout);
 382
 383         uint64_t start = odhcp6c_get_milli_time(), round_start = start, elapsed;
 384
 385         // Generate transaction ID
 386         uint8_t trid[3] = {0, 0, 0};
 387         if (type != DHCPV6_MSG_UNKNOWN)
 388                 odhcp6c_random(trid, sizeof(trid));
 389         ssize_t len = -1;
 390         int64_t rto = 0;
 391
 392         do {
 393                 rto = (rto == 0) ? (retx->init_timeo * 1000 +
 394                                 dhcpv6_rand_delay(retx->init_timeo * 1000)) :
 395                                 (2 * rto + dhcpv6_rand_delay(rto));
 396
 397                 if (rto >= retx->max_timeo * 1000)
 398                         rto = retx->max_timeo * 1000 +
 399                                 dhcpv6_rand_delay(retx->max_timeo * 1000);
 400
 401                 // Calculate end for this round and elapsed time
 402                 uint64_t round_end = round_start + rto;
 403                 elapsed = round_start - start;
 404
 405                 // Don't wait too long
 406                 if (round_end - start > timeout * 1000)
 407                         round_end = timeout * 1000 + start;
 408
 409                 // Built and send package
 410                 if (type != DHCPV6_MSG_UNKNOWN)
 411                         dhcpv6_send(type, trid, elapsed / 10);
 412
 413                 // Receive rounds
 414                 for (; len < 0 && round_start < round_end;
 415                                 round_start = odhcp6c_get_milli_time()) {
 416                         // Check for pending signal
 417                         if (odhcp6c_signal_process())
 418                                 return -1;
 419
 420                         // Set timeout for receiving
 421                         uint64_t t = round_end - round_start;
 422                         struct timeval timeout = {t / 1000, (t % 1000) * 1000};
 423                         setsockopt(sock, SOL_SOCKET, SO_RCVTIMEO,
 424                                         &timeout, sizeof(timeout));
 425
 426                         // Receive cycle
 427                         len = recv(sock, buf, sizeof(buf), 0);
 428
 429                         if (!dhcpv6_response_is_valid(buf, len, trid, type))
 430                                 len = -1;
 431
 432                         if (len > 0) {
 433                                 uint8_t *opt = &buf[4];
 434                                 uint8_t *opt_end = opt + len - 4;
 435
 436                                 round_start = odhcp6c_get_milli_time();
 437                                 elapsed = round_start - start;
 438                                 syslog(LOG_NOTICE, "Got a valid reply after "
 439                                                 "%ums", (unsigned)elapsed);
 440
 441                                 if (retx->handler_reply)
 442                                         len = retx->handler_reply(
 443                                                         type, opt, opt_end);
 444
 445                                 if (round_end - round_start > 1000)
 446                                         round_end = 1000 + round_start;
 447                         }
 448                 }
 449
 450                 // Allow
 451                 if (retx->handler_finish)
 452                         len = retx->handler_finish();
 453         } while (len < 0 && elapsed / 1000 < timeout);
 454
 455         return len;
 456 }
 457
 458
 459 static bool dhcpv6_response_is_valid(const void *buf, ssize_t len,
 460                 const uint8_t transaction[3], enum dhcpv6_msg type)
 461 {
 462         const struct dhcpv6_header *rep = buf;
 463         if (len < (ssize_t)sizeof(*rep) || memcmp(rep->tr_id,
 464                         transaction, sizeof(rep->tr_id)))
 465                 return false; // Invalid reply
 466
 467         if (type == DHCPV6_MSG_SOLICIT) {
 468                 if (rep->msg_type != DHCPV6_MSG_ADVERT &&
 469                                 rep->msg_type != DHCPV6_MSG_REPLY)
 470                         return false;
 471         } else if (type == DHCPV6_MSG_UNKNOWN) {
 472                 if (!accept_reconfig || rep->msg_type != DHCPV6_MSG_RECONF)
 473                         return false;
 474         } else if (rep->msg_type != DHCPV6_MSG_REPLY) {
 475                 return false;
 476         }
 477
 478         uint8_t *end = ((uint8_t*)buf) + len, *odata;
 479         uint16_t otype, olen;
 480         bool clientid_ok = false, serverid_ok = false, rcauth_ok = false;
 481
 482         size_t client_id_len, server_id_len;
 483         void *client_id = odhcp6c_get_state(STATE_CLIENT_ID, &client_id_len);
 484         void *server_id = odhcp6c_get_state(STATE_SERVER_ID, &server_id_len);
 485
 486         dhcpv6_for_each_option(&rep[1], end, otype, olen, odata) {
 487                 if (otype == DHCPV6_OPT_CLIENTID) {
 488                         clientid_ok = (olen + 4U == client_id_len) && !memcmp(
 489                                         &odata[-4], client_id, client_id_len);
 490                 } else if (otype == DHCPV6_OPT_SERVERID) {
 491                         serverid_ok = (olen + 4U == server_id_len) && !memcmp(
 492                                         &odata[-4], server_id, server_id_len);
 493                 } else if (otype == DHCPV6_OPT_AUTH && olen == -4 +
 494                                 sizeof(struct dhcpv6_auth_reconfigure)) {
 495                         struct dhcpv6_auth_reconfigure *r = (void*)&odata[-4];
 496                         if (r->protocol != 3 || r->algorithm != 1 || r->reconf_type != 2)
 497                                 continue;
 498
 499                         md5_state_t md5;
 500                         uint8_t serverhash[16], secretbytes[16], hash[16];
 501                         memcpy(serverhash, r->key, sizeof(serverhash));
 502                         memset(r->key, 0, sizeof(r->key));
 503                         memcpy(secretbytes, reconf_key, sizeof(secretbytes));
 504
 505                         for (size_t i = 0; i < sizeof(secretbytes); ++i)
 506                                 secretbytes[i] ^= 0x36;
 507
 508                         md5_init(&md5);
 509                         md5_append(&md5, secretbytes, sizeof(secretbytes));
 510                         md5_append(&md5, buf, len);
 511                         md5_finish(&md5, hash);
 512
 513                         for (size_t i = 0; i < sizeof(secretbytes); ++i) {
 514                                 secretbytes[i] ^= 0x36;
 515                                 secretbytes[i] ^= 0x5c;
 516                         }
 517
 518                         md5_init(&md5);
 519                         md5_append(&md5, secretbytes, sizeof(secretbytes));
 520                         md5_append(&md5, hash, 16);
 521                         md5_finish(&md5, hash);
 522
 523                         rcauth_ok = !memcmp(hash, serverhash, sizeof(hash));
 524                 }
 525         }
 526
 527         if (rep->msg_type == DHCPV6_MSG_RECONF && !rcauth_ok)
 528                 return false;
 529
 530         return clientid_ok && (serverid_ok || server_id_len == 0);
 531 }
 532
 533
 534 int dhcpv6_poll_reconfigure(void)
 535 {
 536         int ret = dhcpv6_request(DHCPV6_MSG_UNKNOWN);
 537         if (ret != -1)
 538                 ret = dhcpv6_request(ret);
 539
 540         return ret;
 541 }
 542
 543
 544 static int dhcpv6_handle_reconfigure(_unused enum dhcpv6_msg orig,
 545                 const void *opt, const void *end)
 546 {
 547         // TODO: should verify the reconfigure message
 548         uint16_t otype, olen;
 549         uint8_t *odata, msg = DHCPV6_MSG_RENEW;
 550         dhcpv6_for_each_option(opt, end, otype, olen, odata)
 551                 if (otype == DHCPV6_OPT_RECONF_MESSAGE && olen == 1 && (
 552                                 odata[0] == DHCPV6_MSG_RENEW ||
 553                                 odata[0] == DHCPV6_MSG_INFO_REQ))
 554                         msg = odata[0];
 555
 556         dhcpv6_handle_reply(DHCPV6_MSG_UNKNOWN, NULL, NULL);
 557         return msg;
 558 }
 559
 560
 561 // Collect all advertised servers
 562 static int dhcpv6_handle_advert(enum dhcpv6_msg orig,
 563                 const void *opt, const void *end)
 564 {
 565         uint16_t olen, otype;
 566         uint8_t *odata;
 567         struct dhcpv6_server_cand cand = {false, false, 0, 0, {0}, NULL, NULL, 0, 0};
 568
 569         dhcpv6_for_each_option(opt, end, otype, olen, odata) {
 570                 if (otype == DHCPV6_OPT_SERVERID && olen <= 130) {
 571                         memcpy(cand.duid, odata, olen);
 572                         cand.duid_len = olen;
 573                 } else if (otype == DHCPV6_OPT_STATUS && olen >= 2 && !odata[0]
 574                                 && odata[1] == DHCPV6_NoAddrsAvail) {
 575                         if (na_mode == IA_MODE_FORCE) {
 576                                 return -1;
 577                         } else {
 578                                 cand.has_noaddravail = true;
 579                                 cand.preference -= 1000;
 580                         }
 581                 } else if (otype == DHCPV6_OPT_STATUS && olen >= 2 && !odata[0]
 582                                 && odata[1] == DHCPV6_NoPrefixAvail) {
 583                         cand.preference -= 2000;
 584                 } else if (otype == DHCPV6_OPT_PREF && olen >= 1 &&
 585                                 cand.preference >= 0) {
 586                         cand.preference = odata[0];
 587                 } else if (otype == DHCPV6_OPT_RECONF_ACCEPT) {
 588                         cand.wants_reconfigure = true;
 589                 } else if (otype == DHCPV6_OPT_IA_PD && request_prefix) {
 590                         struct dhcpv6_ia_hdr *h = (struct dhcpv6_ia_hdr*)&odata[-4];
 591                         uint8_t *oend = odata + olen, *d;
 592                         dhcpv6_for_each_option(&h[1], oend, otype, olen, d) {
 593                                 if (otype == DHCPV6_OPT_IA_PREFIX)
 594                                         cand.preference += 2000;
 595                                 else if (otype == DHCPV6_OPT_STATUS &&
 596                                                 olen >= 2 && d[0] == 0 &&
 597                                                 d[1] == DHCPV6_NoPrefixAvail)
 598                                         cand.preference -= 2000;
 599                         }
 600                 }
 601
 602                 if (orig == DHCPV6_MSG_SOLICIT &&
 603                                 (otype == DHCPV6_OPT_IA_PD || otype == DHCPV6_OPT_IA_NA) &&
 604                                 olen > sizeof(struct dhcpv6_ia_hdr)) {
 605                         struct dhcpv6_ia_hdr *ia_hdr = (void*)(&odata[-4]);
 606                         dhcpv6_parse_ia(&ia_hdr[1], odata + olen);
 607                 }
 608         }
 609
 610         if (cand.duid_len > 0) {
 611                 cand.ia_na = odhcp6c_move_state(STATE_IA_NA, &cand.ia_na_len);
 612                 cand.ia_pd = odhcp6c_move_state(STATE_IA_PD, &cand.ia_pd_len);
 613                 odhcp6c_add_state(STATE_SERVER_CAND, &cand, sizeof(cand));
 614         }
 615
 616         if (orig == DHCPV6_MSG_SOLICIT) {
 617                 odhcp6c_clear_state(STATE_IA_NA);
 618                 odhcp6c_clear_state(STATE_IA_PD);
 619         }
 620
 621         return -1;
 622 }
 623
 624
 625 static int dhcpv6_commit_advert(void)
 626 {
 627         size_t cand_len;
 628         struct dhcpv6_server_cand *c = NULL, *cand =
 629                         odhcp6c_get_state(STATE_SERVER_CAND, &cand_len);
 630
 631         bool retry = false;
 632         for (size_t i = 0; i < cand_len / sizeof(*c); ++i) {
 633                 if (cand[i].has_noaddravail)
 634                         retry = true; // We want to try again
 635
 636                 if (!c || c->preference < cand[i].preference)
 637                         c = &cand[i];
 638         }
 639
 640         if (retry && na_mode == IA_MODE_TRY) {
 641                 // We give it a second try without the IA_NA
 642                 na_mode = IA_MODE_NONE;
 643                 return dhcpv6_request(DHCPV6_MSG_SOLICIT);
 644         }
 645
 646         if (c) {
 647                 uint16_t hdr[2] = {htons(DHCPV6_OPT_SERVERID),
 648                                 htons(c->duid_len)};
 649                 odhcp6c_add_state(STATE_SERVER_ID, hdr, sizeof(hdr));
 650                 odhcp6c_add_state(STATE_SERVER_ID, c->duid, c->duid_len);
 651                 accept_reconfig = c->wants_reconfigure;
 652                 odhcp6c_add_state(STATE_IA_NA, c->ia_na, c->ia_na_len);
 653                 odhcp6c_add_state(STATE_IA_PD, c->ia_pd, c->ia_pd_len);
 654         }
 655
 656         for (size_t i = 0; i < cand_len / sizeof(*c); ++i) {
 657                 free(cand[i].ia_na);
 658                 free(cand[i].ia_pd);
 659         }
 660         odhcp6c_clear_state(STATE_SERVER_CAND);
 661
 662         if (!c)
 663                 return -1;
 664         else if (request_prefix || na_mode != IA_MODE_NONE)
 665                 return DHCPV6_STATEFUL;
 666         else
 667                 return DHCPV6_STATELESS;
 668 }
 669
 670
 671 static int dhcpv6_handle_rebind_reply(enum dhcpv6_msg orig,
 672                 const void *opt, const void *end)
 673 {
 674         dhcpv6_handle_advert(orig, opt, end);
 675         if (dhcpv6_commit_advert() < 0) {
 676                 dhcpv6_handle_reply(DHCPV6_MSG_UNKNOWN, NULL, NULL);
 677                 return -1;
 678         }
 679
 680         return dhcpv6_handle_reply(orig, opt, end);
 681 }
 682
 683
 684 static int dhcpv6_handle_reply(enum dhcpv6_msg orig,
 685                 const void *opt, const void *end)
 686 {
 687         uint8_t *odata;
 688         uint16_t otype, olen;
 689
 690         odhcp6c_expire();
 691
 692         if (orig == DHCPV6_MSG_UNKNOWN) {
 693                 static time_t last_update = 0;
 694                 time_t now = odhcp6c_get_milli_time() / 1000;
 695
 696                 uint32_t elapsed = (last_update > 0) ? now - last_update : 0;
 697                 last_update = now;
 698
 699                 t1 -= elapsed;
 700                 t2 -= elapsed;
 701                 t3 -= elapsed;
 702
 703                 if (t1 < 0)
 704                         t1 = 0;
 705
 706                 if (t2 < 0)
 707                         t2 = 0;
 708
 709                 if (t3 < 0)
 710                         t3 = 0;
 711         } else {
 712                 t1 = t2 = t3 = UINT32_MAX;
 713         }
 714
 715         if (orig == DHCPV6_MSG_REQUEST) {
 716                 // Delete NA and PD we have in the state from the Advert
 717                 odhcp6c_clear_state(STATE_IA_NA);
 718                 odhcp6c_clear_state(STATE_IA_PD);
 719         }
 720
 721         if (opt) {
 722                 odhcp6c_clear_state(STATE_DNS);
 723                 odhcp6c_clear_state(STATE_SEARCH);
 724                 odhcp6c_clear_state(STATE_SNTP_IP);
 725                 odhcp6c_clear_state(STATE_SNTP_FQDN);
 726                 odhcp6c_clear_state(STATE_SIP_IP);
 727                 odhcp6c_clear_state(STATE_SIP_FQDN);
 728                 odhcp6c_clear_state(STATE_AFTR_NAME);
 729         }
 730
 731         // Parse and find all matching IAs
 732         dhcpv6_for_each_option(opt, end, otype, olen, odata) {
 733                 if ((otype == DHCPV6_OPT_IA_PD || otype == DHCPV6_OPT_IA_NA)
 734                                 && olen > sizeof(struct dhcpv6_ia_hdr)) {
 735                         struct dhcpv6_ia_hdr *ia_hdr = (void*)(&odata[-4]);
 736                         uint32_t l_t1 = ntohl(ia_hdr->t1);
 737                         uint32_t l_t2 = ntohl(ia_hdr->t2);
 738
 739                         // Test ID and T1-T2 validity
 740                         if (ia_hdr->iaid != 1 || l_t2 < l_t1)
 741                                 continue;
 742
 743                         bool error = false;
 744                         uint16_t stype, slen;
 745                         uint8_t *sdata;
 746                         // Test status and bail if error
 747                         dhcpv6_for_each_option(&ia_hdr[1], odata + olen,
 748                                         stype, slen, sdata)
 749                                 if (stype == DHCPV6_OPT_STATUS && slen >= 2 &&
 750                                                 (sdata[0] || sdata[1]))
 751                                         error = true;
 752
 753                         if (error)
 754                                 continue;
 755
 756                         uint32_t n = dhcpv6_parse_ia(&ia_hdr[1], odata + olen);
 757
 758                         if (!l_t1)
 759                                 l_t1 = 300;
 760
 761                         if (!l_t2)
 762                                 l_t2 = 600;
 763
 764                         if (n < t3)
 765                                 t3 = n;
 766
 767                         // Update times
 768                         if (l_t1 > 0 && t1 > l_t1)
 769                                 t1 = l_t1;
 770
 771                         if (l_t2 > 0 && t2 > l_t2)
 772                                 t2 = l_t2;
 773
 774                 } else if (otype == DHCPV6_OPT_DNS_SERVERS) {
 775                         if (olen % 16 == 0)
 776                                 odhcp6c_add_state(STATE_DNS, odata, olen);
 777                 } else if (otype == DHCPV6_OPT_DNS_DOMAIN) {
 778                         odhcp6c_add_state(STATE_SEARCH, odata, olen);
 779                 } else if (otype == DHCPV6_OPT_NTP_SERVER) {
 780                         uint16_t stype, slen;
 781                         uint8_t *sdata;
 782                         // Test status and bail if error
 783                         dhcpv6_for_each_option(odata, odata + olen,
 784                                         stype, slen, sdata) {
 785                                 if (slen == 16 && (stype == NTP_MC_ADDR ||
 786                                                 stype == NTP_SRV_ADDR))
 787                                         odhcp6c_add_state(STATE_SNTP_IP,
 788                                                         sdata, slen);
 789                                 else if (slen > 0 && stype == NTP_SRV_FQDN)
 790                                         odhcp6c_add_state(STATE_SNTP_FQDN,
 791                                                         sdata, slen);
 792                         }
 793                 } else if (otype == DHCPV6_OPT_SIP_SERVER_A) {
 794                         if (olen == 16)
 795                                 odhcp6c_add_state(STATE_SIP_IP, odata, olen);
 796                 } else if (otype == DHCPV6_OPT_SIP_SERVER_D) {
 797                         odhcp6c_add_state(STATE_SIP_FQDN, odata, olen);
 798                 } else if (otype == DHCPV6_OPT_INFO_REFRESH && olen >= 4) {
 799                         uint32_t refresh = ntohl(*((uint32_t*)odata));
 800                         if (refresh < (uint32_t)t1)
 801                                 t1 = refresh;
 802                 } else if (otype == DHCPV6_OPT_AUTH && olen == -4 +
 803                                 sizeof(struct dhcpv6_auth_reconfigure)) {
 804                         struct dhcpv6_auth_reconfigure *r = (void*)&odata[-4];
 805                         if (r->protocol == 3 && r->algorithm == 1 &&
 806                                         r->reconf_type == 1)
 807                                 memcpy(reconf_key, r->key, sizeof(r->key));
 808                 } else if (otype == DHCPV6_OPT_AFTR_NAME && olen > 3) {
 809                         size_t cur_len;
 810                         odhcp6c_get_state(STATE_AFTR_NAME, &cur_len);
 811                         if (cur_len == 0)
 812                                 odhcp6c_add_state(STATE_AFTR_NAME, odata, olen);
 813                 } else if (otype != DHCPV6_OPT_CLIENTID &&
 814                                 otype != DHCPV6_OPT_SERVERID) {
 815                         odhcp6c_add_state(STATE_CUSTOM_OPTS,
 816                                         &odata[-4], olen + 4);
 817                 }
 818         }
 819
 820         return true;
 821 }
 822
 823
 824 static uint32_t dhcpv6_parse_ia(void *opt, void *end)
 825 {
 826         uint32_t timeout = UINT32_MAX; // Minimum timeout
 827         uint16_t otype, olen;
 828         uint8_t *odata;
 829
 830         struct odhcp6c_entry entry = {IN6ADDR_ANY_INIT,
 831                         0, 0, IN6ADDR_ANY_INIT, 0, 0};
 832
 833         // Update address IA
 834         dhcpv6_for_each_option(opt, end, otype, olen, odata) {
 835                 if (otype == DHCPV6_OPT_IA_PREFIX) {
 836                         struct dhcpv6_ia_prefix *prefix = (void*)&odata[-4];
 837                         if (olen + 4U < sizeof(*prefix))
 838                                 continue;
 839
 840                         entry.valid = ntohl(prefix->valid);
 841                         entry.preferred = ntohl(prefix->preferred);
 842
 843                         if (entry.preferred > entry.valid)
 844                                 continue;
 845
 846                         entry.length = prefix->prefix;
 847                         entry.target = prefix->addr;
 848
 849                         // Parse PD-exclude
 850                         bool ok = true;
 851                         uint16_t stype, slen;
 852                         uint8_t *sdata;
 853                         dhcpv6_for_each_option(odata + sizeof(*prefix) - 4U,
 854                                         odata + olen, stype, slen, sdata) {
 855                                 if (stype != DHCPV6_OPT_PD_EXCLUDE || slen < 2)
 856                                         continue;
 857
 858                                 uint8_t elen = sdata[0];
 859                                 if (elen > 64)
 860                                         elen = 64;
 861
 862                                 if (elen <= 32 || elen <= entry.length) {
 863                                         ok = false;
 864                                         continue;
 865                                 }
 866
 867
 868                                 uint8_t bytes = ((elen - entry.length - 1) / 8) + 1;
 869                                 if (slen <= bytes) {
 870                                         ok = false;
 871                                         continue;
 872                                 }
 873
 874                                 uint32_t exclude = 0;
 875                                 do {
 876                                         exclude = exclude << 8 | sdata[bytes];
 877                                 } while (--bytes);
 878
 879                                 exclude >>= 8 - ((elen - entry.length) % 8);
 880                                 exclude <<= 64 - elen;
 881
 882                                 // Abusing router & priority fields for exclusion
 883                                 entry.router = entry.target;
 884                                 entry.router.s6_addr32[1] |= htonl(exclude);
 885                                 entry.priority = elen;
 886                         }
 887
 888                         if (ok)
 889                                 odhcp6c_update_entry(STATE_IA_PD, &entry);
 890
 891                         entry.priority = 0;
 892                         memset(&entry.router, 0, sizeof(entry.router));
 893                 } else if (otype == DHCPV6_OPT_IA_ADDR) {
 894                         struct dhcpv6_ia_addr *addr = (void*)&odata[-4];
 895                         if (olen + 4U < sizeof(*addr))
 896                                 continue;
 897
 898                         entry.preferred = ntohl(addr->preferred);
 899                         entry.valid = ntohl(addr->valid);
 900
 901                         if (entry.preferred > entry.valid)
 902                                 continue;
 903
 904                         entry.length = 128;
 905                         entry.target = addr->addr;
 906
 907                         odhcp6c_update_entry(STATE_IA_NA, &entry);
 908                 }
 909
 910                 if (entry.valid > 0 && timeout > entry.valid)
 911                         timeout = entry.valid;
 912         }
 913
 914         return timeout;
 915 }