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_SIP_SERVER_A),
 146                         htons(DHCPV6_OPT_AFTR_NAME),
 147                         htons(DHCPV6_OPT_PD_EXCLUDE),
 148                         htons(DHCPV6_OPT_PREFIX_CLASS),
 149         };
 150         odhcp6c_add_state(STATE_ORO, oro, sizeof(oro));
 151
 152
 153         // Configure IPv6-options
 154         int val = 1;
 155         setsockopt(sock, IPPROTO_IPV6, IPV6_V6ONLY, &val, sizeof(val));
 156         setsockopt(sock, SOL_SOCKET, SO_REUSEADDR, &val, sizeof(val));
 157         setsockopt(sock, SOL_SOCKET, SO_BINDTODEVICE, ifname, strlen(ifname));
 158
 159         struct sockaddr_in6 client_addr = { .sin6_family = AF_INET6,
 160                 .sin6_port = htons(DHCPV6_CLIENT_PORT), .sin6_flowinfo = 0 };
 161         if (bind(sock, (struct sockaddr*)&client_addr, sizeof(client_addr)))
 162                 return -1;
 163
 164         return 0;
 165 }
 166
 167
 168 void dhcpv6_set_ia_na_mode(enum odhcp6c_ia_mode mode)
 169 {
 170         na_mode = mode;
 171 }
 172
 173
 174 static void dhcpv6_send(enum dhcpv6_msg type, uint8_t trid[3], uint32_t ecs)
 175 {
 176         // Build FQDN
 177         char fqdn_buf[256];
 178         gethostname(fqdn_buf, sizeof(fqdn_buf));
 179         struct {
 180                 uint16_t type;
 181                 uint16_t len;
 182                 uint8_t flags;
 183                 uint8_t data[256];
 184         } fqdn;
 185         size_t fqdn_len = 5 + dn_comp(fqdn_buf, fqdn.data,
 186                         sizeof(fqdn.data), NULL, NULL);
 187         fqdn.type = htons(DHCPV6_OPT_FQDN);
 188         fqdn.len = htons(fqdn_len - 4);
 189         fqdn.flags = 0;
 190
 191
 192         // Build Client ID
 193         size_t cl_id_len;
 194         void *cl_id = odhcp6c_get_state(STATE_CLIENT_ID, &cl_id_len);
 195
 196         // Get Server ID
 197         size_t srv_id_len;
 198         void *srv_id = odhcp6c_get_state(STATE_SERVER_ID, &srv_id_len);
 199
 200         // Build IA_PDs
 201         size_t ia_pd_entries, ia_pd_len = 0;
 202         struct odhcp6c_entry *e = odhcp6c_get_state(STATE_IA_PD, &ia_pd_entries);
 203         ia_pd_entries /= sizeof(*e);
 204         struct dhcpv6_ia_hdr hdr_ia_pd = {
 205                 htons(DHCPV6_OPT_IA_PD),
 206                 htons(sizeof(hdr_ia_pd) - 4),
 207                 1, 0, 0
 208         };
 209
 210
 211         uint8_t *ia_pd = alloca(ia_pd_entries * (sizeof(struct dhcpv6_ia_prefix) + 10));
 212         for (size_t i = 0; i < ia_pd_entries; ++i) {
 213                 uint8_t ex_len = 0;
 214                 if (e[i].priority > 0)
 215                         ex_len = ((e[i].priority - e[i].length - 1) / 8) + 6;
 216
 217                 struct dhcpv6_ia_prefix p = {
 218                         .type = htons(DHCPV6_OPT_IA_PREFIX),
 219                         .len = htons(sizeof(p) - 4U + ex_len),
 220                         .prefix = e[i].length,
 221                         .addr = e[i].target
 222                 };
 223
 224                 memcpy(ia_pd + ia_pd_len, &p, sizeof(p));
 225                 ia_pd_len += sizeof(p);
 226
 227                 if (ex_len) {
 228                         ia_pd[ia_pd_len++] = 0;
 229                         ia_pd[ia_pd_len++] = DHCPV6_OPT_PD_EXCLUDE;
 230                         ia_pd[ia_pd_len++] = 0;
 231                         ia_pd[ia_pd_len++] = ex_len - 4;
 232                         ia_pd[ia_pd_len++] = e[i].priority;
 233
 234                         uint32_t excl = ntohl(e[i].router.s6_addr32[1]);
 235                         excl >>= (64 - e[i].priority);
 236                         excl <<= 8 - ((e[i].priority - e[i].length) % 8);
 237
 238                         for (size_t i = ex_len - 5; i > 0; --i, excl >>= 8)
 239                                 ia_pd[ia_pd_len + i] = excl & 0xff;
 240                         ia_pd_len += ex_len - 5;
 241                 }
 242         }
 243
 244         struct dhcpv6_ia_prefix pref = {
 245                 .type = htons(DHCPV6_OPT_IA_PREFIX),
 246                 .len = htons(25), .prefix = request_prefix
 247         };
 248         if (request_prefix > 0 && ia_pd_len == 0 &&
 249                         (type == DHCPV6_MSG_SOLICIT ||
 250                         type == DHCPV6_MSG_REQUEST)) {
 251                 ia_pd = (uint8_t*)&pref;
 252                 ia_pd_len = sizeof(pref);
 253         }
 254         hdr_ia_pd.len = htons(ntohs(hdr_ia_pd.len) + ia_pd_len);
 255
 256         // Build IA_NAs
 257         size_t ia_na_entries, ia_na_len = 0;
 258         void *ia_na = NULL;
 259         e = odhcp6c_get_state(STATE_IA_NA, &ia_na_entries);
 260         ia_na_entries /= sizeof(*e);
 261
 262         struct dhcpv6_ia_hdr hdr_ia_na = {
 263                 htons(DHCPV6_OPT_IA_NA),
 264                 htons(sizeof(hdr_ia_na) - 4),
 265                 1, 0, 0
 266         };
 267
 268         struct dhcpv6_ia_addr pa[ia_na_entries];
 269         for (size_t i = 0; i < ia_na_entries; ++i) {
 270                 pa[i].type = htons(DHCPV6_OPT_IA_ADDR);
 271                 pa[i].len = htons(sizeof(pa[i]) - 4U);
 272                 pa[i].addr = e[i].target;
 273                 pa[i].preferred = 0;
 274                 pa[i].valid = 0;
 275         }
 276
 277         ia_na = pa;
 278         ia_na_len = sizeof(pa);
 279         hdr_ia_na.len = htons(ntohs(hdr_ia_na.len) + ia_na_len);
 280
 281         // Reconfigure Accept
 282         struct {
 283                 uint16_t type;
 284                 uint16_t length;
 285         } reconf_accept = {htons(DHCPV6_OPT_RECONF_ACCEPT), 0};
 286
 287         // Request Information Refresh
 288         uint16_t oro_refresh = htons(DHCPV6_OPT_INFO_REFRESH);
 289
 290         // Prepare Header
 291         size_t oro_len;
 292         void *oro = odhcp6c_get_state(STATE_ORO, &oro_len);
 293         struct {
 294                 uint8_t type;
 295                 uint8_t trid[3];
 296                 uint16_t elapsed_type;
 297                 uint16_t elapsed_len;
 298                 uint16_t elapsed_value;
 299                 uint16_t oro_type;
 300                 uint16_t oro_len;
 301         } hdr = {
 302                 type, {trid[0], trid[1], trid[2]},
 303                 htons(DHCPV6_OPT_ELAPSED), htons(2),
 304                         htons((ecs > 0xffff) ? 0xffff : ecs),
 305                 htons(DHCPV6_OPT_ORO), htons(oro_len),
 306         };
 307
 308         struct iovec iov[] = {
 309                 {&hdr, sizeof(hdr)},
 310                 {oro, oro_len},
 311                 {&oro_refresh, 0},
 312                 {cl_id, cl_id_len},
 313                 {srv_id, srv_id_len},
 314                 {&reconf_accept, sizeof(reconf_accept)},
 315                 {&fqdn, fqdn_len},
 316                 {&hdr_ia_na, sizeof(hdr_ia_na)},
 317                 {ia_na, ia_na_len},
 318                 {&hdr_ia_pd, sizeof(hdr_ia_pd)},
 319                 {ia_pd, ia_pd_len},
 320         };
 321
 322         size_t cnt = ARRAY_SIZE(iov);
 323         if (type == DHCPV6_MSG_INFO_REQ) {
 324                 cnt = 5;
 325                 iov[2].iov_len = sizeof(oro_refresh);
 326                 hdr.oro_len = htons(oro_len + sizeof(oro_refresh));
 327         } else if (!request_prefix) {
 328                 cnt = 9;
 329         }
 330
 331         // Disable IAs if not used
 332         if (type != DHCPV6_MSG_REQUEST && type != DHCPV6_MSG_SOLICIT) {
 333                 iov[5].iov_len = 0;
 334                 if (ia_na_len == 0)
 335                         iov[7].iov_len = 0;
 336                 if (ia_pd_len == 0)
 337                         iov[9].iov_len = 0;
 338         }
 339
 340         if (na_mode == IA_MODE_NONE)
 341                 iov[7].iov_len = 0;
 342
 343         struct sockaddr_in6 srv = {AF_INET6, htons(DHCPV6_SERVER_PORT),
 344                 0, ALL_DHCPV6_RELAYS, ifindex};
 345         struct msghdr msg = {&srv, sizeof(srv), iov, cnt, NULL, 0, 0};
 346
 347         sendmsg(sock, &msg, 0);
 348 }
 349
 350
 351 static int64_t dhcpv6_rand_delay(int64_t time)
 352 {
 353         int random;
 354         odhcp6c_random(&random, sizeof(random));
 355         return (time * ((int64_t)random % 1000LL)) / 10000LL;
 356 }
 357
 358
 359 int dhcpv6_request(enum dhcpv6_msg type)
 360 {
 361         uint8_t buf[1536];
 362         uint64_t timeout = UINT32_MAX;
 363         struct dhcpv6_retx *retx = &dhcpv6_retx[type];
 364
 365         if (retx->delay) {
 366                 struct timespec ts = {0, 0};
 367                 ts.tv_nsec = dhcpv6_rand_delay(10 * DHCPV6_REQ_DELAY);
 368                 nanosleep(&ts, NULL);
 369         }
 370
 371         if (type == DHCPV6_MSG_RELEASE || type == DHCPV6_MSG_DECLINE)
 372                 timeout = 3;
 373         else if (type == DHCPV6_MSG_UNKNOWN)
 374                 timeout = t1;
 375         else if (type == DHCPV6_MSG_RENEW)
 376                 timeout = (t2 > t1) ? t2 - t1 : 0;
 377         else if (type == DHCPV6_MSG_REBIND)
 378                 timeout = (t3 > t2) ? t3 - t2 : 0;
 379
 380         if (timeout == 0)
 381                 return -1;
 382
 383         syslog(LOG_NOTICE, "Sending %s (timeout %us)", retx->name, (unsigned)timeout);
 384
 385         uint64_t start = odhcp6c_get_milli_time(), round_start = start, elapsed;
 386
 387         // Generate transaction ID
 388         uint8_t trid[3] = {0, 0, 0};
 389         if (type != DHCPV6_MSG_UNKNOWN)
 390                 odhcp6c_random(trid, sizeof(trid));
 391         ssize_t len = -1;
 392         int64_t rto = 0;
 393
 394         do {
 395                 rto = (rto == 0) ? (retx->init_timeo * 1000 +
 396                                 dhcpv6_rand_delay(retx->init_timeo * 1000)) :
 397                                 (2 * rto + dhcpv6_rand_delay(rto));
 398
 399                 if (rto >= retx->max_timeo * 1000)
 400                         rto = retx->max_timeo * 1000 +
 401                                 dhcpv6_rand_delay(retx->max_timeo * 1000);
 402
 403                 // Calculate end for this round and elapsed time
 404                 uint64_t round_end = round_start + rto;
 405                 elapsed = round_start - start;
 406
 407                 // Don't wait too long
 408                 if (round_end - start > timeout * 1000)
 409                         round_end = timeout * 1000 + start;
 410
 411                 // Built and send package
 412                 if (type != DHCPV6_MSG_UNKNOWN)
 413                         dhcpv6_send(type, trid, elapsed / 10);
 414
 415                 // Receive rounds
 416                 for (; len < 0 && round_start < round_end;
 417                                 round_start = odhcp6c_get_milli_time()) {
 418                         // Check for pending signal
 419                         if (odhcp6c_signal_process())
 420                                 return -1;
 421
 422                         // Set timeout for receiving
 423                         uint64_t t = round_end - round_start;
 424                         struct timeval timeout = {t / 1000, (t % 1000) * 1000};
 425                         setsockopt(sock, SOL_SOCKET, SO_RCVTIMEO,
 426                                         &timeout, sizeof(timeout));
 427
 428                         // Receive cycle
 429                         len = recv(sock, buf, sizeof(buf), 0);
 430
 431                         if (!dhcpv6_response_is_valid(buf, len, trid, type))
 432                                 len = -1;
 433
 434                         if (len > 0) {
 435                                 uint8_t *opt = &buf[4];
 436                                 uint8_t *opt_end = opt + len - 4;
 437
 438                                 round_start = odhcp6c_get_milli_time();
 439                                 elapsed = round_start - start;
 440                                 syslog(LOG_NOTICE, "Got a valid reply after "
 441                                                 "%ums", (unsigned)elapsed);
 442
 443                                 if (retx->handler_reply)
 444                                         len = retx->handler_reply(
 445                                                         type, opt, opt_end);
 446
 447                                 if (round_end - round_start > 1000)
 448                                         round_end = 1000 + round_start;
 449                         }
 450                 }
 451
 452                 // Allow
 453                 if (retx->handler_finish)
 454                         len = retx->handler_finish();
 455         } while (len < 0 && elapsed / 1000 < timeout);
 456
 457         return len;
 458 }
 459
 460
 461 static bool dhcpv6_response_is_valid(const void *buf, ssize_t len,
 462                 const uint8_t transaction[3], enum dhcpv6_msg type)
 463 {
 464         const struct dhcpv6_header *rep = buf;
 465         if (len < (ssize_t)sizeof(*rep) || memcmp(rep->tr_id,
 466                         transaction, sizeof(rep->tr_id)))
 467                 return false; // Invalid reply
 468
 469         if (type == DHCPV6_MSG_SOLICIT) {
 470                 if (rep->msg_type != DHCPV6_MSG_ADVERT &&
 471                                 rep->msg_type != DHCPV6_MSG_REPLY)
 472                         return false;
 473         } else if (type == DHCPV6_MSG_UNKNOWN) {
 474                 if (!accept_reconfig || rep->msg_type != DHCPV6_MSG_RECONF)
 475                         return false;
 476         } else if (rep->msg_type != DHCPV6_MSG_REPLY) {
 477                 return false;
 478         }
 479
 480         uint8_t *end = ((uint8_t*)buf) + len, *odata;
 481         uint16_t otype, olen;
 482         bool clientid_ok = false, serverid_ok = false, rcauth_ok = false;
 483
 484         size_t client_id_len, server_id_len;
 485         void *client_id = odhcp6c_get_state(STATE_CLIENT_ID, &client_id_len);
 486         void *server_id = odhcp6c_get_state(STATE_SERVER_ID, &server_id_len);
 487
 488         dhcpv6_for_each_option(&rep[1], end, otype, olen, odata) {
 489                 if (otype == DHCPV6_OPT_CLIENTID) {
 490                         clientid_ok = (olen + 4U == client_id_len) && !memcmp(
 491                                         &odata[-4], client_id, client_id_len);
 492                 } else if (otype == DHCPV6_OPT_SERVERID) {
 493                         serverid_ok = (olen + 4U == server_id_len) && !memcmp(
 494                                         &odata[-4], server_id, server_id_len);
 495                 } else if (otype == DHCPV6_OPT_AUTH && olen == -4 +
 496                                 sizeof(struct dhcpv6_auth_reconfigure)) {
 497                         struct dhcpv6_auth_reconfigure *r = (void*)&odata[-4];
 498                         if (r->protocol != 3 || r->algorithm != 1 || r->reconf_type != 2)
 499                                 continue;
 500
 501                         md5_state_t md5;
 502                         uint8_t serverhash[16], secretbytes[16], hash[16];
 503                         memcpy(serverhash, r->key, sizeof(serverhash));
 504                         memset(r->key, 0, sizeof(r->key));
 505                         memcpy(secretbytes, reconf_key, sizeof(secretbytes));
 506
 507                         for (size_t i = 0; i < sizeof(secretbytes); ++i)
 508                                 secretbytes[i] ^= 0x36;
 509
 510                         md5_init(&md5);
 511                         md5_append(&md5, secretbytes, sizeof(secretbytes));
 512                         md5_append(&md5, buf, len);
 513                         md5_finish(&md5, hash);
 514
 515                         for (size_t i = 0; i < sizeof(secretbytes); ++i) {
 516                                 secretbytes[i] ^= 0x36;
 517                                 secretbytes[i] ^= 0x5c;
 518                         }
 519
 520                         md5_init(&md5);
 521                         md5_append(&md5, secretbytes, sizeof(secretbytes));
 522                         md5_append(&md5, hash, 16);
 523                         md5_finish(&md5, hash);
 524
 525                         rcauth_ok = !memcmp(hash, serverhash, sizeof(hash));
 526                 }
 527         }
 528
 529         if (rep->msg_type == DHCPV6_MSG_RECONF && !rcauth_ok)
 530                 return false;
 531
 532         return clientid_ok && (serverid_ok || server_id_len == 0);
 533 }
 534
 535
 536 int dhcpv6_poll_reconfigure(void)
 537 {
 538         int ret = dhcpv6_request(DHCPV6_MSG_UNKNOWN);
 539         if (ret != -1)
 540                 ret = dhcpv6_request(ret);
 541
 542         return ret;
 543 }
 544
 545
 546 static int dhcpv6_handle_reconfigure(_unused enum dhcpv6_msg orig,
 547                 const void *opt, const void *end)
 548 {
 549         // TODO: should verify the reconfigure message
 550         uint16_t otype, olen;
 551         uint8_t *odata, msg = DHCPV6_MSG_RENEW;
 552         dhcpv6_for_each_option(opt, end, otype, olen, odata)
 553                 if (otype == DHCPV6_OPT_RECONF_MESSAGE && olen == 1 && (
 554                                 odata[0] == DHCPV6_MSG_RENEW ||
 555                                 odata[0] == DHCPV6_MSG_INFO_REQ))
 556                         msg = odata[0];
 557
 558         dhcpv6_handle_reply(DHCPV6_MSG_UNKNOWN, NULL, NULL);
 559         return msg;
 560 }
 561
 562
 563 // Collect all advertised servers
 564 static int dhcpv6_handle_advert(enum dhcpv6_msg orig,
 565                 const void *opt, const void *end)
 566 {
 567         uint16_t olen, otype;
 568         uint8_t *odata;
 569         struct dhcpv6_server_cand cand = {false, false, 0, 0, {0}, NULL, NULL, 0, 0};
 570
 571         dhcpv6_for_each_option(opt, end, otype, olen, odata) {
 572                 if (orig == DHCPV6_MSG_SOLICIT &&
 573                                 (otype == DHCPV6_OPT_IA_PD || otype == DHCPV6_OPT_IA_NA) &&
 574                                 olen > sizeof(struct dhcpv6_ia_hdr)) {
 575                         struct dhcpv6_ia_hdr *ia_hdr = (void*)(&odata[-4]);
 576                         dhcpv6_parse_ia(&ia_hdr[1], odata + olen);
 577                 }
 578
 579                 if (otype == DHCPV6_OPT_SERVERID && olen <= 130) {
 580                         memcpy(cand.duid, odata, olen);
 581                         cand.duid_len = olen;
 582                 } else if (otype == DHCPV6_OPT_STATUS && olen >= 2 && !odata[0]
 583                                 && odata[1] == DHCPV6_NoAddrsAvail) {
 584                         if (na_mode == IA_MODE_FORCE) {
 585                                 return -1;
 586                         } else {
 587                                 cand.has_noaddravail = true;
 588                                 cand.preference -= 1000;
 589                         }
 590                 } else if (otype == DHCPV6_OPT_STATUS && olen >= 2 && !odata[0]
 591                                 && odata[1] == DHCPV6_NoPrefixAvail) {
 592                         cand.preference -= 2000;
 593                 } else if (otype == DHCPV6_OPT_PREF && olen >= 1 &&
 594                                 cand.preference >= 0) {
 595                         cand.preference = odata[0];
 596                 } else if (otype == DHCPV6_OPT_RECONF_ACCEPT) {
 597                         cand.wants_reconfigure = true;
 598                 } else if (otype == DHCPV6_OPT_IA_PD && request_prefix) {
 599                         struct dhcpv6_ia_hdr *h = (struct dhcpv6_ia_hdr*)&odata[-4];
 600                         uint8_t *oend = odata + olen, *d;
 601                         dhcpv6_for_each_option(&h[1], oend, otype, olen, d) {
 602                                 if (otype == DHCPV6_OPT_IA_PREFIX)
 603                                         cand.preference += 2000;
 604                                 else if (otype == DHCPV6_OPT_STATUS &&
 605                                                 olen >= 2 && d[0] == 0 &&
 606                                                 d[1] == DHCPV6_NoPrefixAvail)
 607                                         cand.preference -= 2000;
 608                         }
 609                 }
 610         }
 611
 612         if (cand.duid_len > 0) {
 613                 cand.ia_na = odhcp6c_move_state(STATE_IA_NA, &cand.ia_na_len);
 614                 cand.ia_pd = odhcp6c_move_state(STATE_IA_PD, &cand.ia_pd_len);
 615                 odhcp6c_add_state(STATE_SERVER_CAND, &cand, sizeof(cand));
 616         }
 617
 618         if (orig == DHCPV6_MSG_SOLICIT) {
 619                 odhcp6c_clear_state(STATE_IA_NA);
 620                 odhcp6c_clear_state(STATE_IA_PD);
 621         }
 622
 623         return -1;
 624 }
 625
 626
 627 static int dhcpv6_commit_advert(void)
 628 {
 629         size_t cand_len;
 630         struct dhcpv6_server_cand *c = NULL, *cand =
 631                         odhcp6c_get_state(STATE_SERVER_CAND, &cand_len);
 632
 633         bool retry = false;
 634         for (size_t i = 0; i < cand_len / sizeof(*c); ++i) {
 635                 if (cand[i].has_noaddravail)
 636                         retry = true; // We want to try again
 637
 638                 if (!c || c->preference < cand[i].preference)
 639                         c = &cand[i];
 640         }
 641
 642         if (retry && na_mode == IA_MODE_TRY) {
 643                 // We give it a second try without the IA_NA
 644                 na_mode = IA_MODE_NONE;
 645                 return dhcpv6_request(DHCPV6_MSG_SOLICIT);
 646         }
 647
 648         if (c) {
 649                 uint16_t hdr[2] = {htons(DHCPV6_OPT_SERVERID),
 650                                 htons(c->duid_len)};
 651                 odhcp6c_add_state(STATE_SERVER_ID, hdr, sizeof(hdr));
 652                 odhcp6c_add_state(STATE_SERVER_ID, c->duid, c->duid_len);
 653                 accept_reconfig = c->wants_reconfigure;
 654                 odhcp6c_add_state(STATE_IA_NA, c->ia_na, c->ia_na_len);
 655                 odhcp6c_add_state(STATE_IA_PD, c->ia_pd, c->ia_pd_len);
 656         }
 657
 658         for (size_t i = 0; i < cand_len / sizeof(*c); ++i) {
 659                 free(cand[i].ia_na);
 660                 free(cand[i].ia_pd);
 661         }
 662         odhcp6c_clear_state(STATE_SERVER_CAND);
 663
 664         if (!c)
 665                 return -1;
 666         else if (request_prefix || na_mode != IA_MODE_NONE)
 667                 return DHCPV6_STATEFUL;
 668         else
 669                 return DHCPV6_STATELESS;
 670 }
 671
 672
 673 static int dhcpv6_handle_rebind_reply(enum dhcpv6_msg orig,
 674                 const void *opt, const void *end)
 675 {
 676         dhcpv6_handle_advert(orig, opt, end);
 677         if (dhcpv6_commit_advert() < 0) {
 678                 dhcpv6_handle_reply(DHCPV6_MSG_UNKNOWN, NULL, NULL);
 679                 return -1;
 680         }
 681
 682         return dhcpv6_handle_reply(orig, opt, end);
 683 }
 684
 685
 686 static int dhcpv6_handle_reply(enum dhcpv6_msg orig,
 687                 const void *opt, const void *end)
 688 {
 689         uint8_t *odata;
 690         uint16_t otype, olen;
 691
 692         odhcp6c_expire();
 693
 694         if (orig == DHCPV6_MSG_UNKNOWN) {
 695                 static time_t last_update = 0;
 696                 time_t now = odhcp6c_get_milli_time() / 1000;
 697
 698                 uint32_t elapsed = (last_update > 0) ? now - last_update : 0;
 699                 last_update = now;
 700
 701                 t1 -= elapsed;
 702                 t2 -= elapsed;
 703                 t3 -= elapsed;
 704
 705                 if (t1 < 0)
 706                         t1 = 0;
 707
 708                 if (t2 < 0)
 709                         t2 = 0;
 710
 711                 if (t3 < 0)
 712                         t3 = 0;
 713         } else {
 714                 t1 = t2 = t3 = UINT32_MAX;
 715         }
 716
 717         if (orig == DHCPV6_MSG_REQUEST) {
 718                 // Delete NA and PD we have in the state from the Advert
 719                 odhcp6c_clear_state(STATE_IA_NA);
 720                 odhcp6c_clear_state(STATE_IA_PD);
 721         }
 722
 723         if (opt) {
 724                 odhcp6c_clear_state(STATE_DNS);
 725                 odhcp6c_clear_state(STATE_SEARCH);
 726                 odhcp6c_clear_state(STATE_SNTP_IP);
 727                 odhcp6c_clear_state(STATE_SNTP_FQDN);
 728                 odhcp6c_clear_state(STATE_SIP_IP);
 729                 odhcp6c_clear_state(STATE_SIP_FQDN);
 730                 odhcp6c_clear_state(STATE_AFTR_NAME);
 731         }
 732
 733         // Parse and find all matching IAs
 734         dhcpv6_for_each_option(opt, end, otype, olen, odata) {
 735                 if ((otype == DHCPV6_OPT_IA_PD || otype == DHCPV6_OPT_IA_NA)
 736                                 && olen > sizeof(struct dhcpv6_ia_hdr)) {
 737                         struct dhcpv6_ia_hdr *ia_hdr = (void*)(&odata[-4]);
 738                         uint32_t l_t1 = ntohl(ia_hdr->t1);
 739                         uint32_t l_t2 = ntohl(ia_hdr->t2);
 740
 741                         // Test ID and T1-T2 validity
 742                         if (ia_hdr->iaid != 1 || l_t2 < l_t1)
 743                                 continue;
 744
 745                         bool error = false;
 746                         uint16_t stype, slen;
 747                         uint8_t *sdata;
 748                         // Test status and bail if error
 749                         dhcpv6_for_each_option(&ia_hdr[1], odata + olen,
 750                                         stype, slen, sdata)
 751                                 if (stype == DHCPV6_OPT_STATUS && slen >= 2 &&
 752                                                 (sdata[0] || sdata[1]))
 753                                         error = true;
 754
 755                         if (error)
 756                                 continue;
 757
 758                         uint32_t n = dhcpv6_parse_ia(&ia_hdr[1], odata + olen);
 759
 760                         if (!l_t1)
 761                                 l_t1 = 300;
 762
 763                         if (!l_t2)
 764                                 l_t2 = 600;
 765
 766                         if (n < t3)
 767                                 t3 = n;
 768
 769                         // Update times
 770                         if (l_t1 > 0 && t1 > l_t1)
 771                                 t1 = l_t1;
 772
 773                         if (l_t2 > 0 && t2 > l_t2)
 774                                 t2 = l_t2;
 775
 776                 } else if (otype == DHCPV6_OPT_DNS_SERVERS) {
 777                         if (olen % 16 == 0)
 778                                 odhcp6c_add_state(STATE_DNS, odata, olen);
 779                 } else if (otype == DHCPV6_OPT_DNS_DOMAIN) {
 780                         odhcp6c_add_state(STATE_SEARCH, odata, olen);
 781                 } else if (otype == DHCPV6_OPT_NTP_SERVER) {
 782                         uint16_t stype, slen;
 783                         uint8_t *sdata;
 784                         // Test status and bail if error
 785                         dhcpv6_for_each_option(odata, odata + olen,
 786                                         stype, slen, sdata) {
 787                                 if (slen == 16 && (stype == NTP_MC_ADDR ||
 788                                                 stype == NTP_SRV_ADDR))
 789                                         odhcp6c_add_state(STATE_SNTP_IP,
 790                                                         sdata, slen);
 791                                 else if (slen > 0 && stype == NTP_SRV_FQDN)
 792                                         odhcp6c_add_state(STATE_SNTP_FQDN,
 793                                                         sdata, slen);
 794                         }
 795                 } else if (otype == DHCPV6_OPT_SIP_SERVER_A) {
 796                         if (olen == 16)
 797                                 odhcp6c_add_state(STATE_SIP_IP, odata, olen);
 798                 } else if (otype == DHCPV6_OPT_SIP_SERVER_D) {
 799                         odhcp6c_add_state(STATE_SIP_FQDN, odata, olen);
 800                 } else if (otype == DHCPV6_OPT_INFO_REFRESH && olen >= 4) {
 801                         uint32_t refresh = ntohl(*((uint32_t*)odata));
 802                         if (refresh < (uint32_t)t1)
 803                                 t1 = refresh;
 804                 } else if (otype == DHCPV6_OPT_AUTH && olen == -4 +
 805                                 sizeof(struct dhcpv6_auth_reconfigure)) {
 806                         struct dhcpv6_auth_reconfigure *r = (void*)&odata[-4];
 807                         if (r->protocol == 3 && r->algorithm == 1 &&
 808                                         r->reconf_type == 1)
 809                                 memcpy(reconf_key, r->key, sizeof(r->key));
 810                 } else if (otype == DHCPV6_OPT_AFTR_NAME && olen > 3) {
 811                         size_t cur_len;
 812                         odhcp6c_get_state(STATE_AFTR_NAME, &cur_len);
 813                         if (cur_len == 0)
 814                                 odhcp6c_add_state(STATE_AFTR_NAME, odata, olen);
 815                 } else if (otype != DHCPV6_OPT_CLIENTID &&
 816                                 otype != DHCPV6_OPT_SERVERID) {
 817                         odhcp6c_add_state(STATE_CUSTOM_OPTS,
 818                                         &odata[-4], olen + 4);
 819                 }
 820         }
 821
 822         return true;
 823 }
 824
 825
 826 static uint32_t dhcpv6_parse_ia(void *opt, void *end)
 827 {
 828         uint32_t timeout = UINT32_MAX; // Minimum timeout
 829         uint16_t otype, olen;
 830         uint8_t *odata;
 831
 832         // Update address IA
 833         dhcpv6_for_each_option(opt, end, otype, olen, odata) {
 834           struct odhcp6c_entry entry = {IN6ADDR_ANY_INIT,
 835                                         0, 0, IN6ADDR_ANY_INIT, 0, 0, 0};
 836
 837                 if (otype == DHCPV6_OPT_IA_PREFIX) {
 838                         struct dhcpv6_ia_prefix *prefix = (void*)&odata[-4];
 839                         if (olen + 4U < sizeof(*prefix))
 840                                 continue;
 841
 842                         entry.valid = ntohl(prefix->valid);
 843                         entry.preferred = ntohl(prefix->preferred);
 844
 845                         if (entry.preferred > entry.valid)
 846                                 continue;
 847
 848                         entry.length = prefix->prefix;
 849                         entry.target = prefix->addr;
 850                         uint16_t stype, slen;
 851                         uint8_t *sdata;
 852
 853                         // Find prefix class, if any
 854                         dhcpv6_for_each_option(&prefix[1], odata + olen,
 855                                                stype, slen, sdata)
 856                           if (stype == DHCPV6_OPT_PREFIX_CLASS && slen == 2)
 857                             entry.prefix_class = ntohs(*((uint16_t*)sdata));
 858
 859                         // Parse PD-exclude
 860                         bool ok = true;
 861                         dhcpv6_for_each_option(odata + sizeof(*prefix) - 4U,
 862                                         odata + olen, stype, slen, sdata) {
 863                                 if (stype != DHCPV6_OPT_PD_EXCLUDE || slen < 2)
 864                                         continue;
 865
 866                                 uint8_t elen = sdata[0];
 867                                 if (elen > 64)
 868                                         elen = 64;
 869
 870                                 if (elen <= 32 || elen <= entry.length) {
 871                                         ok = false;
 872                                         continue;
 873                                 }
 874
 875
 876                                 uint8_t bytes = ((elen - entry.length - 1) / 8) + 1;
 877                                 if (slen <= bytes) {
 878                                         ok = false;
 879                                         continue;
 880                                 }
 881
 882                                 uint32_t exclude = 0;
 883                                 do {
 884                                         exclude = exclude << 8 | sdata[bytes];
 885                                 } while (--bytes);
 886
 887                                 exclude >>= 8 - ((elen - entry.length) % 8);
 888                                 exclude <<= 64 - elen;
 889
 890                                 // Abusing router & priority fields for exclusion
 891                                 entry.router = entry.target;
 892                                 entry.router.s6_addr32[1] |= htonl(exclude);
 893                                 entry.priority = elen;
 894                         }
 895
 896                         if (ok)
 897                                 odhcp6c_update_entry(STATE_IA_PD, &entry);
 898
 899                         entry.priority = 0;
 900                         memset(&entry.router, 0, sizeof(entry.router));
 901                 } else if (otype == DHCPV6_OPT_IA_ADDR) {
 902                         struct dhcpv6_ia_addr *addr = (void*)&odata[-4];
 903                         if (olen + 4U < sizeof(*addr))
 904                                 continue;
 905
 906                         entry.preferred = ntohl(addr->preferred);
 907                         entry.valid = ntohl(addr->valid);
 908
 909                         if (entry.preferred > entry.valid)
 910                                 continue;
 911
 912                         entry.length = 128;
 913                         entry.target = addr->addr;
 914
 915                         uint16_t stype, slen;
 916                         uint8_t *sdata;
 917
 918                         // Find prefix class, if any
 919                         dhcpv6_for_each_option(&addr[1], odata + olen,
 920                                                stype, slen, sdata)
 921                           if (stype == DHCPV6_OPT_PREFIX_CLASS && slen == 2)
 922                             entry.prefix_class = ntohs(*((uint16_t*)sdata));
 923
 924                         odhcp6c_update_entry(STATE_IA_NA, &entry);
 925                 }
 926
 927                 if (entry.valid > 0 && timeout > entry.valid)
 928                         timeout = entry.valid;
 929         }
 930
 931         return timeout;
 932 }