src/dhcpv4.c

   1 /**
   2  * Copyright (C) 2012-2013 Steven Barth <steven@midlink.org>
   3  * Copyright (C) 2016 Hans Dedecker <dedeckeh@gmail.com>
   4  *
   5  * This program is free software; you can redistribute it and/or modify
   6  * it under the terms of the GNU General Public License v2 as published by
   7  * the Free Software Foundation.
   8  *
   9  * This program is distributed in the hope that it will be useful,
  10  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  11  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  12  * GNU General Public License for more details.
  13  *
  14  *
  15  */
  16
  17 #include <time.h>
  18 #include <errno.h>
  19 #include <fcntl.h>
  20 #include <unistd.h>
  21 #include <stddef.h>
  22 #include <stdlib.h>
  23 #include <resolv.h>
  24 #include <limits.h>
  25 #include <net/if.h>
  26 #include <net/if_arp.h>
  27 #include <netinet/ip.h>
  28 #include <sys/ioctl.h>
  29 #include <sys/timerfd.h>
  30 #include <arpa/inet.h>
  31
  32 #include <libubox/md5.h>
  33
  34 #include "odhcpd.h"
  35 #include "dhcpv4.h"
  36 #include "dhcpv6.h"
  37
  38 static void dhcpv4_netevent_cb(unsigned long event, struct netevent_handler_info *info);
  39 static int setup_dhcpv4_addresses(struct interface *iface);
  40 static void update_static_assignments(struct interface *iface);
  41 static bool addr_is_fr_ip(struct interface *iface, struct in_addr *addr);
  42 static void valid_until_cb(struct uloop_timeout *event);
  43 static void handle_addrlist_change(struct interface *iface);
  44 static void free_dhcpv4_assignment(struct dhcpv4_assignment *a);
  45 static void dhcpv4_fr_start(struct dhcpv4_assignment *a);
  46 static void dhcpv4_fr_rand_delay(struct dhcpv4_assignment *a);
  47 static void dhcpv4_fr_stop(struct dhcpv4_assignment *a);
  48 static void handle_dhcpv4(void *addr, void *data, size_t len,
  49                 struct interface *iface, void *dest_addr);
  50 static struct dhcpv4_assignment* dhcpv4_lease(struct interface *iface,
  51                 enum dhcpv4_msg msg, const uint8_t *mac, const uint32_t reqaddr,
  52                 uint32_t *leasetime, const char *hostname, const size_t hostname_len,
  53                 const bool accept_fr_nonce, bool *incl_fr_opt, uint32_t *fr_serverid);
  54
  55 static struct netevent_handler dhcpv4_netevent_handler = { .cb = dhcpv4_netevent_cb, };
  56 static struct uloop_timeout valid_until_timeout = {.cb = valid_until_cb};
  57 static uint32_t serial = 0;
  58
  59 struct odhcpd_ref_ip {
  60         struct list_head head;
  61         int ref_cnt;
  62         struct odhcpd_ipaddr addr;
  63 };
  64
  65 /* Create socket and register events */
  66 int dhcpv4_init(void)
  67 {
  68         uloop_timeout_set(&valid_until_timeout, 1000);
  69         netlink_add_netevent_handler(&dhcpv4_netevent_handler);
  70
  71         return 0;
  72 }
  73
  74 int dhcpv4_setup_interface(struct interface *iface, bool enable)
  75 {
  76         int ret = 0;
  77
  78         if (iface->dhcpv4_event.uloop.fd > 0) {
  79                 uloop_fd_delete(&iface->dhcpv4_event.uloop);
  80                 close(iface->dhcpv4_event.uloop.fd);
  81                 iface->dhcpv4_event.uloop.fd = -1;
  82         }
  83
  84         if (iface->dhcpv4 && enable) {
  85                 struct sockaddr_in bind_addr = {AF_INET, htons(DHCPV4_SERVER_PORT),
  86                                         {INADDR_ANY}, {0}};
  87                 int val = 1;
  88
  89                 if (!iface->dhcpv4_assignments.next)
  90                         INIT_LIST_HEAD(&iface->dhcpv4_assignments);
  91
  92                 if (!iface->dhcpv4_fr_ips.next)
  93                         INIT_LIST_HEAD(&iface->dhcpv4_fr_ips);
  94
  95                 iface->dhcpv4_event.uloop.fd = socket(AF_INET, SOCK_DGRAM | SOCK_CLOEXEC, IPPROTO_UDP);
  96                 if (iface->dhcpv4_event.uloop.fd < 0) {
  97                         syslog(LOG_ERR, "socket(AF_INET): %m");
  98                         ret = -1;
  99                         goto out;
 100                 }
 101
 102                 /* Basic IPv4 configuration */
 103                 if (setsockopt(iface->dhcpv4_event.uloop.fd, SOL_SOCKET, SO_REUSEADDR,
 104                                         &val, sizeof(val)) < 0) {
 105                         syslog(LOG_ERR, "setsockopt(SO_REUSEADDR): %m");
 106                         ret = -1;
 107                         goto out;
 108                 }
 109
 110                 if (setsockopt(iface->dhcpv4_event.uloop.fd, SOL_SOCKET, SO_BROADCAST,
 111                                         &val, sizeof(val)) < 0) {
 112                         syslog(LOG_ERR, "setsockopt(SO_BROADCAST): %m");
 113                         ret = -1;
 114                         goto out;
 115                 }
 116
 117                 if (setsockopt(iface->dhcpv4_event.uloop.fd, IPPROTO_IP, IP_PKTINFO,
 118                                         &val, sizeof(val)) < 0) {
 119                         syslog(LOG_ERR, "setsockopt(IP_PKTINFO): %m");
 120                         ret = -1;
 121                         goto out;
 122                 }
 123
 124                 val = IPTOS_PREC_INTERNETCONTROL;
 125                 if (setsockopt(iface->dhcpv4_event.uloop.fd, IPPROTO_IP, IP_TOS,
 126                                         &val, sizeof(val)) < 0) {
 127                         syslog(LOG_ERR, "setsockopt(IP_TOS): %m");
 128                         ret = -1;
 129                         goto out;
 130                 }
 131
 132                 val = IP_PMTUDISC_DONT;
 133                 if (setsockopt(iface->dhcpv4_event.uloop.fd, IPPROTO_IP, IP_MTU_DISCOVER,
 134                                         &val, sizeof(val)) < 0) {
 135                         syslog(LOG_ERR, "setsockopt(IP_MTU_DISCOVER): %m");
 136                         ret = -1;
 137                         goto out;
 138                 }
 139
 140                 if (setsockopt(iface->dhcpv4_event.uloop.fd, SOL_SOCKET, SO_BINDTODEVICE,
 141                                         iface->ifname, strlen(iface->ifname)) < 0) {
 142                         syslog(LOG_ERR, "setsockopt(SO_BINDTODEVICE): %m");
 143                         ret = -1;
 144                         goto out;
 145                 }
 146
 147                 if (bind(iface->dhcpv4_event.uloop.fd, (struct sockaddr*)&bind_addr,
 148                                         sizeof(bind_addr)) < 0) {
 149                         syslog(LOG_ERR, "bind(): %m");
 150                         ret = -1;
 151                         goto out;
 152                 }
 153
 154                 if (setup_dhcpv4_addresses(iface) < 0) {
 155                         ret = -1;
 156                         goto out;
 157                 }
 158
 159                 iface->dhcpv4_event.handle_dgram = handle_dhcpv4;
 160                 odhcpd_register(&iface->dhcpv4_event);
 161
 162                 update_static_assignments(iface);
 163         } else if (iface->dhcpv4_assignments.next) {
 164                 while (!list_empty(&iface->dhcpv4_assignments))
 165                         free_dhcpv4_assignment(list_first_entry(&iface->dhcpv4_assignments,
 166                                                         struct dhcpv4_assignment, head));
 167         }
 168
 169 out:
 170         if (ret < 0 && iface->dhcpv4_event.uloop.fd > 0) {
 171                 close(iface->dhcpv4_event.uloop.fd);
 172                 iface->dhcpv4_event.uloop.fd = -1;
 173         }
 174
 175         return ret;
 176 }
 177
 178
 179 static void dhcpv4_netevent_cb(unsigned long event, struct netevent_handler_info *info)
 180 {
 181         struct interface *iface = info->iface;
 182
 183         if (!iface || iface->dhcpv4 == MODE_DISABLED)
 184                 return;
 185
 186         switch (event) {
 187         case NETEV_IFINDEX_CHANGE:
 188                 dhcpv4_setup_interface(iface, true);
 189                 break;
 190         case NETEV_ADDRLIST_CHANGE:
 191                 handle_addrlist_change(iface);
 192                 break;
 193         default:
 194                 break;
 195         }
 196 }
 197
 198 static struct dhcpv4_assignment *find_assignment_by_hwaddr(struct interface *iface, const uint8_t *hwaddr)
 199 {
 200         struct dhcpv4_assignment *a;
 201
 202         list_for_each_entry(a, &iface->dhcpv4_assignments, head)
 203                 if (!memcmp(a->hwaddr, hwaddr, 6))
 204                         return a;
 205
 206         return NULL;
 207 }
 208
 209 static struct dhcpv4_assignment *find_assignment_by_addr(struct interface *iface, const uint32_t addr)
 210 {
 211         struct dhcpv4_assignment *a;
 212
 213         list_for_each_entry(a, &iface->dhcpv4_assignments, head)
 214                 if (a->addr == addr)
 215                         return a;
 216
 217         return NULL;
 218 }
 219
 220 static int setup_dhcpv4_addresses(struct interface *iface)
 221 {
 222         iface->dhcpv4_start_ip.s_addr = INADDR_ANY;
 223         iface->dhcpv4_end_ip.s_addr = INADDR_ANY;
 224         iface->dhcpv4_local.s_addr = INADDR_ANY;
 225         iface->dhcpv4_bcast.s_addr = INADDR_ANY;
 226         iface->dhcpv4_mask.s_addr = INADDR_ANY;
 227
 228         /* Sanity checks */
 229         if (iface->dhcpv4_start.s_addr & htonl(0xffff0000) ||
 230             iface->dhcpv4_end.s_addr & htonl(0xffff0000) ||
 231             ntohl(iface->dhcpv4_start.s_addr) > ntohl(iface->dhcpv4_end.s_addr)) {
 232                 syslog(LOG_ERR, "invalid DHCP range for %s", iface->name);
 233                 return -1;
 234         }
 235
 236         if (!iface->addr4_len) {
 237                 syslog(LOG_WARNING, "no network(s) available on %s", iface->name);
 238                 return -1;
 239         }
 240
 241         uint32_t start = ntohl(iface->dhcpv4_start.s_addr);
 242         uint32_t end = ntohl(iface->dhcpv4_end.s_addr);
 243
 244         for (size_t i = 0; i < iface->addr4_len && start && end; i++) {
 245                 struct in_addr *addr = &iface->addr4[i].addr.in;
 246                 struct in_addr mask;
 247
 248                 if (addr_is_fr_ip(iface, addr))
 249                         continue;
 250
 251                 odhcpd_bitlen2netmask(false, iface->addr4[i].prefix, &mask);
 252                 if ((start & ntohl(~mask.s_addr)) == start &&
 253                             (end & ntohl(~mask.s_addr)) == end) {
 254                         iface->dhcpv4_start_ip.s_addr = htonl(start) |
 255                                                         (addr->s_addr & mask.s_addr);
 256                         iface->dhcpv4_end_ip.s_addr = htonl(end) |
 257                                                         (addr->s_addr & mask.s_addr);
 258                         iface->dhcpv4_local = *addr;
 259                         iface->dhcpv4_bcast = iface->addr4[i].broadcast;
 260                         iface->dhcpv4_mask = mask;
 261                         return 0;
 262                 }
 263         }
 264
 265         /* Don't allocate IP range for subnets bigger than 28 */
 266         if (iface->addr4[0].prefix > 28) {
 267                 syslog(LOG_WARNING, "auto allocation of DHCP range fails on %s", iface->name);
 268                 return -1;
 269         }
 270
 271         iface->dhcpv4_local = iface->addr4[0].addr.in;
 272         iface->dhcpv4_bcast = iface->addr4[0].broadcast;
 273         odhcpd_bitlen2netmask(false, iface->addr4[0].prefix, &iface->dhcpv4_mask);
 274         end = start = iface->dhcpv4_local.s_addr & iface->dhcpv4_mask.s_addr;
 275
 276         /* Auto allocate ranges */
 277         if (ntohl(iface->dhcpv4_mask.s_addr) <= 0xffffff00) {
 278                 iface->dhcpv4_start_ip.s_addr = start | htonl(100);
 279                 iface->dhcpv4_end_ip.s_addr = end | htonl(250);
 280         } else if (ntohl(iface->dhcpv4_mask.s_addr) <= 0xffffffc0) {
 281                 iface->dhcpv4_start_ip.s_addr = start | htonl(10);
 282                 iface->dhcpv4_end_ip.s_addr = end | htonl(60);
 283         } else if (ntohl(iface->dhcpv4_mask.s_addr) <= 0xffffffe0) {
 284                 iface->dhcpv4_start_ip.s_addr = start | htonl(10);
 285                 iface->dhcpv4_end_ip.s_addr = end | htonl(30);
 286         } else {
 287                 iface->dhcpv4_start_ip.s_addr = start | htonl(3);
 288                 iface->dhcpv4_end_ip.s_addr = end | htonl(12);
 289         }
 290
 291         return 0;
 292 }
 293
 294 static void update_static_assignments(struct interface *iface)
 295 {
 296         struct dhcpv4_assignment *a, *c;
 297
 298         /* Cleanup static entries not belonging to the network */
 299         list_for_each_entry_safe(a, c, &iface->dhcpv4_assignments, head) {
 300                 if ((a->flags & OAF_STATIC) &&
 301                                 ((a->addr & iface->dhcpv4_mask.s_addr) !=
 302                                  (iface->dhcpv4_start.s_addr & iface->dhcpv4_mask.s_addr)))
 303                         free_dhcpv4_assignment(a);
 304         }
 305
 306         /* Parse static entries */
 307         struct lease *lease;
 308         list_for_each_entry(lease, &leases, head) {
 309                 if ((iface->dhcpv4_start_ip.s_addr & iface->dhcpv4_mask.s_addr) !=
 310                                 (lease->ipaddr.s_addr & iface->dhcpv4_mask.s_addr)) {
 311                         continue;
 312                 }
 313
 314                 a = find_assignment_by_hwaddr(iface, lease->mac.ether_addr_octet);
 315
 316                 if (!a) {
 317                         /* Check if there's an assignment with the specified IP address */
 318                         if (find_assignment_by_addr(iface, lease->ipaddr.s_addr))
 319                                 continue;
 320
 321                         /* Construct entry */
 322                         a = calloc(1, sizeof(*a));
 323                         if (!a) {
 324                                 syslog(LOG_ERR, "Calloc failed for static lease on interface %s",
 325                                         iface->ifname);
 326                                 continue;
 327                         }
 328                         memcpy(a->hwaddr, lease->mac.ether_addr_octet, sizeof(a->hwaddr));
 329                 }
 330
 331                 a->leasetime = lease->dhcpv4_leasetime;
 332
 333                 a->addr = lease->ipaddr.s_addr;
 334                 /* Static assignment */
 335                 a->flags |= OAF_STATIC;
 336                 /* Infinite valid */
 337                 a->valid_until = 0;
 338                 a->iface = iface;
 339                 if (lease->hostname[0]) {
 340                         free(a->hostname);
 341                         a->hostname = strdup(lease->hostname);
 342                 }
 343
 344                 /* Assign to all interfaces */
 345                 list_for_each_entry(c, &iface->dhcpv4_assignments, head) {
 346                         if (ntohl(c->addr) > ntohl(a->addr)) {
 347                                 list_add_tail(&a->head, &c->head);
 348                                 break;
 349                         }
 350                 }
 351
 352                 if (&c->head == &iface->dhcpv4_assignments)
 353                         list_add(&a->head, &iface->dhcpv4_assignments);
 354         }
 355 }
 356
 357 static void inc_ref_cnt_ip(struct odhcpd_ref_ip **ptr, struct odhcpd_ref_ip *ip)
 358 {
 359         *ptr = ip;
 360         ip->ref_cnt++;
 361 }
 362
 363 static void decr_ref_cnt_ip(struct odhcpd_ref_ip **ptr, struct interface *iface)
 364 {
 365         struct odhcpd_ref_ip *ip = *ptr;
 366
 367         if (--ip->ref_cnt == 0) {
 368                 netlink_setup_addr(&ip->addr, iface->ifindex, false, false);
 369
 370                 list_del(&ip->head);
 371                 free(ip);
 372         }
 373
 374         *ptr = NULL;
 375 }
 376
 377 static bool addr_is_fr_ip(struct interface *iface, struct in_addr *addr)
 378 {
 379         struct odhcpd_ref_ip *p;
 380
 381         list_for_each_entry(p, &iface->dhcpv4_fr_ips, head) {
 382                 if (addr->s_addr == p->addr.addr.in.s_addr)
 383                         return true;
 384         }
 385
 386         return false;
 387 }
 388
 389 static bool leases_require_fr(struct interface *iface, struct odhcpd_ipaddr *addr,
 390                                 uint32_t mask)
 391 {
 392         struct dhcpv4_assignment *a = NULL;
 393         struct odhcpd_ref_ip *fr_ip = NULL;
 394
 395         list_for_each_entry(a, &iface->dhcpv4_assignments, head) {
 396                 if ((a->accept_fr_nonce || iface->dhcpv4_forcereconf) &&
 397                     !a->fr_ip &&
 398                     ((a->addr & mask) == (addr->addr.in.s_addr & mask))) {
 399                         if (!fr_ip) {
 400                                 fr_ip = calloc(1, sizeof(*fr_ip));
 401                                 if (!fr_ip)
 402                                         break;
 403
 404                                 list_add(&fr_ip->head, &iface->dhcpv4_fr_ips);
 405                                 fr_ip->addr = *addr;
 406                         }
 407                         inc_ref_cnt_ip(&a->fr_ip, fr_ip);
 408                 }
 409         }
 410
 411         return fr_ip ? true : false;
 412 }
 413
 414 static void valid_until_cb(struct uloop_timeout *event)
 415 {
 416         time_t now = odhcpd_time();
 417         struct interface *iface;
 418         list_for_each_entry(iface, &interfaces, head) {
 419                 if (iface->dhcpv4 != MODE_SERVER || iface->dhcpv4_assignments.next == NULL)
 420                         continue;
 421
 422                 struct dhcpv4_assignment *a, *n;
 423                 list_for_each_entry_safe(a, n, &iface->dhcpv4_assignments, head) {
 424                         if (!INFINITE_VALID(a->valid_until) && a->valid_until < now)
 425                                 free_dhcpv4_assignment(a);
 426                 }
 427         }
 428         uloop_timeout_set(event, 1000);
 429 }
 430
 431 static void handle_addrlist_change(struct interface *iface)
 432 {
 433         struct odhcpd_ipaddr ip;
 434         struct odhcpd_ref_ip *a;
 435         struct dhcpv4_assignment *c;
 436         uint32_t mask = iface->dhcpv4_mask.s_addr;
 437
 438         memset(&ip, 0, sizeof(ip));
 439         ip.addr.in = iface->dhcpv4_local;
 440         ip.prefix = odhcpd_netmask2bitlen(false, &iface->dhcpv4_mask);
 441         ip.broadcast = iface->dhcpv4_bcast;
 442
 443         setup_dhcpv4_addresses(iface);
 444
 445         if ((ip.addr.in.s_addr & mask) ==
 446             (iface->dhcpv4_local.s_addr & iface->dhcpv4_mask.s_addr))
 447                 return;
 448
 449         if (ip.addr.in.s_addr && !leases_require_fr(iface, &ip, mask))
 450                 return;
 451
 452         if (iface->dhcpv4_local.s_addr == INADDR_ANY || list_empty(&iface->dhcpv4_fr_ips))
 453                 return;
 454
 455         a = list_first_entry(&iface->dhcpv4_fr_ips, struct odhcpd_ref_ip, head);
 456
 457         if (netlink_setup_addr(&a->addr, iface->ifindex, false, true)) {
 458                 syslog(LOG_ERR, "Failed to add ip address");
 459                 return;
 460         }
 461
 462         list_for_each_entry(c, &iface->dhcpv4_assignments, head) {
 463                 if ((c->flags & OAF_BOUND) && c->fr_ip && !c->fr_cnt) {
 464                         if (c->accept_fr_nonce || iface->dhcpv4_forcereconf)
 465                                 dhcpv4_fr_rand_delay(c);
 466                         else
 467                                 dhcpv4_fr_stop(c);
 468                 }
 469         }
 470 }
 471
 472 static char *dhcpv4_msg_to_string(uint8_t reqmsg)
 473 {
 474         switch (reqmsg) {
 475         case (DHCPV4_MSG_DISCOVER):
 476                 return "DHCPV4_MSG_DISCOVER";
 477         case (DHCPV4_MSG_OFFER):
 478                 return "DHCPV4_MSG_OFFER";
 479         case (DHCPV4_MSG_REQUEST):
 480                 return "DHCPV4_MSG_REQUEST";
 481         case (DHCPV4_MSG_DECLINE):
 482                 return "DHCPV4_MSG_DECLINE";
 483         case (DHCPV4_MSG_ACK):
 484                 return "DHCPV4_MSG_ACK";
 485         case (DHCPV4_MSG_NAK):
 486                 return "DHCPV4_MSG_NAK";
 487         case (DHCPV4_MSG_RELEASE):
 488                 return "DHCPV4_MSG_RELEASE";
 489         case (DHCPV4_MSG_INFORM):
 490                 return "DHCPV4_MSG_INFORM";
 491         case (DHCPV4_MSG_FORCERENEW):
 492                 return "DHCPV4_MSG_FORCERENEW";
 493         default:
 494                 return "UNKNOWN";
 495         }
 496 }
 497
 498 static void free_dhcpv4_assignment(struct dhcpv4_assignment *a)
 499 {
 500         if (a->head.next)
 501                 list_del(&a->head);
 502
 503         if (a->fr_ip)
 504                 dhcpv4_fr_stop(a);
 505
 506         free(a->hostname);
 507         free(a);
 508 }
 509
 510 static void dhcpv4_put(struct dhcpv4_message *msg, uint8_t **cookie,
 511                 uint8_t type, uint8_t len, const void *data)
 512 {
 513         uint8_t *c = *cookie;
 514         uint8_t *end = (uint8_t *)msg + sizeof(*msg);
 515
 516         if (*cookie + 2 + len > end)
 517                 return;
 518
 519         *c++ = type;
 520         *c++ = len;
 521         memcpy(c, data, len);
 522
 523         *cookie = c + len;
 524 }
 525
 526 static void dhcpv4_fr_send(struct dhcpv4_assignment *a)
 527 {
 528         struct dhcpv4_message fr_msg = {
 529                 .op = DHCPV4_BOOTREPLY,
 530                 .htype = 1,
 531                 .hlen = 6,
 532                 .hops = 0,
 533                 .secs = 0,
 534                 .flags = 0,
 535                 .ciaddr = {INADDR_ANY},
 536                 .yiaddr = {INADDR_ANY},
 537                 .siaddr = {INADDR_ANY},
 538                 .giaddr = {INADDR_ANY},
 539                 .chaddr = {0},
 540                 .sname = {0},
 541                 .file = {0},
 542         };
 543         struct dhcpv4_auth_forcerenew *auth_o, auth = {
 544                 .protocol = 3,
 545                 .algorithm = 1,
 546                 .rdm = 0,
 547                 .replay = {htonl(time(NULL)), htonl(++serial)},
 548                 .type = 2,
 549                 .key = {0},
 550         };
 551         struct interface *iface = a->iface;
 552
 553         odhcpd_urandom(&fr_msg.xid, sizeof(fr_msg.xid));
 554         memcpy(fr_msg.chaddr, a->hwaddr, fr_msg.hlen);
 555
 556         fr_msg.options[0] = 0x63;
 557         fr_msg.options[1] = 0x82;
 558         fr_msg.options[2] = 0x53;
 559         fr_msg.options[3] = 0x63;
 560
 561         uint8_t *cookie = &fr_msg.options[4];
 562         uint8_t msg = DHCPV4_MSG_FORCERENEW;
 563
 564         dhcpv4_put(&fr_msg, &cookie, DHCPV4_OPT_MESSAGE, 1, &msg);
 565         if (a->accept_fr_nonce) {
 566                 dhcpv4_put(&fr_msg, &cookie, DHCPV4_OPT_AUTHENTICATION, sizeof(auth), &auth);
 567                 auth_o = (struct dhcpv4_auth_forcerenew *)(cookie - sizeof(auth));
 568                 dhcpv4_put(&fr_msg, &cookie, DHCPV4_OPT_END, 0, NULL);
 569
 570                 md5_ctx_t md5;
 571                 uint8_t secretbytes[64];
 572                 memset(secretbytes, 0, sizeof(secretbytes));
 573                 memcpy(secretbytes, a->key, sizeof(a->key));
 574
 575                 for (size_t i = 0; i < sizeof(secretbytes); ++i)
 576                         secretbytes[i] ^= 0x36;
 577
 578                 md5_begin(&md5);
 579                 md5_hash(secretbytes, sizeof(secretbytes), &md5);
 580                 md5_hash(&fr_msg, sizeof(fr_msg), &md5);
 581                 md5_end(auth_o->key, &md5);
 582
 583                 for (size_t i = 0; i < sizeof(secretbytes); ++i) {
 584                         secretbytes[i] ^= 0x36;
 585                         secretbytes[i] ^= 0x5c;
 586                 }
 587
 588                 md5_begin(&md5);
 589                 md5_hash(secretbytes, sizeof(secretbytes), &md5);
 590                 md5_hash(auth_o->key, sizeof(auth_o->key), &md5);
 591                 md5_end(auth_o->key, &md5);
 592         } else {
 593                 dhcpv4_put(&fr_msg, &cookie, DHCPV4_OPT_SERVERID, 4,
 594                                 &a->fr_ip->addr.addr.in.s_addr);
 595                 dhcpv4_put(&fr_msg, &cookie, DHCPV4_OPT_END, 0, NULL);
 596         }
 597
 598         struct sockaddr_in dest;
 599         memset(&dest, 0, sizeof(dest));
 600         dest.sin_family = AF_INET;
 601         dest.sin_port = htons(DHCPV4_CLIENT_PORT);
 602         dest.sin_addr.s_addr = a->addr;
 603
 604         if (sendto(iface->dhcpv4_event.uloop.fd, &fr_msg, sizeof(fr_msg),
 605                         MSG_DONTWAIT, (struct sockaddr*)&dest, sizeof(dest)) < 0)
 606                 syslog(LOG_ERR, "Failed to send %s to %s - %s: %m", dhcpv4_msg_to_string(msg),
 607                         odhcpd_print_mac(a->hwaddr, sizeof(a->hwaddr)), inet_ntoa(dest.sin_addr));
 608         else
 609                 syslog(LOG_WARNING, "Sent %s to %s - %s", dhcpv4_msg_to_string(msg),
 610                         odhcpd_print_mac(a->hwaddr, sizeof(a->hwaddr)), inet_ntoa(dest.sin_addr));
 611 }
 612
 613 static void dhcpv4_fr_timer(struct uloop_timeout *event)
 614 {
 615         struct dhcpv4_assignment *a = container_of(event, struct dhcpv4_assignment, fr_timer);
 616
 617         if (a->fr_cnt > 0 && a->fr_cnt < 8) {
 618                 dhcpv4_fr_send(a);
 619                 uloop_timeout_set(&a->fr_timer, 1000 << a->fr_cnt);
 620                 a->fr_cnt++;
 621         } else
 622                 dhcpv4_fr_stop(a);
 623 }
 624
 625 static void dhcpv4_fr_start(struct dhcpv4_assignment *a)
 626 {
 627         uloop_timeout_set(&a->fr_timer, 1000 << a->fr_cnt);
 628         a->fr_timer.cb = dhcpv4_fr_timer;
 629         a->fr_cnt++;
 630
 631         dhcpv4_fr_send(a);
 632 }
 633
 634 static void dhcpv4_fr_delay_timer(struct uloop_timeout *event)
 635 {
 636         struct dhcpv4_assignment *a = container_of(event, struct dhcpv4_assignment, fr_timer);
 637         struct interface *iface = a->iface;
 638
 639         (iface->dhcpv4_event.uloop.fd == -1 ? dhcpv4_fr_rand_delay(a) : dhcpv4_fr_start(a));
 640 }
 641
 642 static void dhcpv4_fr_rand_delay(struct dhcpv4_assignment *a)
 643 {
 644 #define MIN_DELAY   500
 645 #define MAX_FUZZ    500
 646         int msecs;
 647
 648         odhcpd_urandom(&msecs, sizeof(msecs));
 649
 650         msecs = labs(msecs)%MAX_FUZZ + MIN_DELAY;
 651
 652         uloop_timeout_set(&a->fr_timer, msecs);
 653         a->fr_timer.cb = dhcpv4_fr_delay_timer;
 654 }
 655
 656 static void dhcpv4_fr_stop(struct dhcpv4_assignment *a)
 657 {
 658         uloop_timeout_cancel(&a->fr_timer);
 659         decr_ref_cnt_ip(&a->fr_ip, a->iface);
 660         a->fr_cnt = 0;
 661         a->fr_timer.cb = NULL;
 662 }
 663
 664 /* Handler for DHCPv4 messages */
 665 static void handle_dhcpv4(void *addr, void *data, size_t len,
 666                 struct interface *iface, _unused void *dest_addr)
 667 {
 668         if (!iface->dhcpv4)
 669                 return;
 670
 671         struct dhcpv4_message *req = data;
 672         if (len < offsetof(struct dhcpv4_message, options) + 4 ||
 673                         req->op != DHCPV4_BOOTREQUEST || req->hlen != 6)
 674                 return;
 675
 676
 677         syslog(LOG_NOTICE, "Got DHCPv4 request");
 678
 679         if (!iface->dhcpv4_start_ip.s_addr && !iface->dhcpv4_end_ip.s_addr) {
 680                 syslog(LOG_WARNING, "No DHCP range available on %s", iface->name);
 681                 return;
 682         }
 683
 684         int sock = iface->dhcpv4_event.uloop.fd;
 685
 686         struct dhcpv4_message reply = {
 687                 .op = DHCPV4_BOOTREPLY,
 688                 .htype = req->htype,
 689                 .hlen = req->hlen,
 690                 .hops = 0,
 691                 .xid = req->xid,
 692                 .secs = 0,
 693                 .flags = req->flags,
 694                 .ciaddr = {INADDR_ANY},
 695                 .giaddr = req->giaddr,
 696                 .siaddr = iface->dhcpv4_local,
 697         };
 698         memcpy(reply.chaddr, req->chaddr, sizeof(reply.chaddr));
 699
 700         reply.options[0] = 0x63;
 701         reply.options[1] = 0x82;
 702         reply.options[2] = 0x53;
 703         reply.options[3] = 0x63;
 704
 705         uint8_t *cookie = &reply.options[4];
 706         uint8_t reqmsg = DHCPV4_MSG_REQUEST;
 707         uint8_t msg = DHCPV4_MSG_ACK;
 708
 709         uint32_t reqaddr = INADDR_ANY;
 710         uint32_t leasetime = 0;
 711         size_t hostname_len = 0;
 712         char hostname[256];
 713         bool accept_fr_nonce = false;
 714         bool incl_fr_opt = false;
 715
 716         uint8_t *start = &req->options[4];
 717         uint8_t *end = ((uint8_t*)data) + len;
 718         struct dhcpv4_option *opt;
 719         dhcpv4_for_each_option(start, end, opt) {
 720                 if (opt->type == DHCPV4_OPT_MESSAGE && opt->len == 1)
 721                         reqmsg = opt->data[0];
 722                 else if (opt->type == DHCPV4_OPT_HOSTNAME && opt->len > 0) {
 723                         hostname_len = opt->len;
 724                         memcpy(hostname, opt->data, hostname_len);
 725                         hostname[hostname_len] = 0;
 726                 } else if (opt->type == DHCPV4_OPT_IPADDRESS && opt->len == 4)
 727                         memcpy(&reqaddr, opt->data, 4);
 728                 else if (opt->type == DHCPV4_OPT_SERVERID && opt->len == 4) {
 729                         if (memcmp(opt->data, &iface->dhcpv4_local, 4))
 730                                 return;
 731                 } else if (iface->filter_class && opt->type == DHCPV4_OPT_USER_CLASS) {
 732                         uint8_t *c = opt->data, *cend = &opt->data[opt->len];
 733                         for (; c < cend && &c[*c] < cend; c = &c[1 + *c]) {
 734                                 size_t elen = strlen(iface->filter_class);
 735                                 if (*c == elen && !memcmp(&c[1], iface->filter_class, elen))
 736                                         return; // Ignore from homenet
 737                         }
 738                 } else if (opt->type == DHCPV4_OPT_LEASETIME && opt->len == 4)
 739                         memcpy(&leasetime, opt->data, 4);
 740                 else if (opt->type == DHCPV4_OPT_FORCERENEW_NONCE_CAPABLE && opt->len > 0) {
 741                         for (uint8_t i = 0; i < opt->len; i++) {
 742                                 if (opt->data[i] == 1) {
 743                                         accept_fr_nonce = true;
 744                                         break;
 745                                 }
 746                         }
 747
 748                 }
 749         }
 750
 751         if (reqmsg != DHCPV4_MSG_DISCOVER && reqmsg != DHCPV4_MSG_REQUEST &&
 752                         reqmsg != DHCPV4_MSG_INFORM && reqmsg != DHCPV4_MSG_DECLINE &&
 753                         reqmsg != DHCPV4_MSG_RELEASE)
 754                 return;
 755
 756         struct dhcpv4_assignment *lease = NULL;
 757         uint32_t serverid = iface->dhcpv4_local.s_addr;
 758         uint32_t fr_serverid = INADDR_ANY;
 759
 760         if (reqmsg != DHCPV4_MSG_INFORM)
 761                 lease = dhcpv4_lease(iface, reqmsg, req->chaddr, reqaddr,
 762                                         &leasetime, hostname, hostname_len,
 763                                         accept_fr_nonce, &incl_fr_opt, &fr_serverid);
 764
 765         if (!lease) {
 766                 if (reqmsg == DHCPV4_MSG_REQUEST)
 767                         msg = DHCPV4_MSG_NAK;
 768                 else if (reqmsg == DHCPV4_MSG_DISCOVER)
 769                         return;
 770         } else if (reqmsg == DHCPV4_MSG_DISCOVER)
 771                 msg = DHCPV4_MSG_OFFER;
 772         else if (reqmsg == DHCPV4_MSG_REQUEST &&
 773                         ((reqaddr && reqaddr != lease->addr) ||
 774                          (req->ciaddr.s_addr && req->ciaddr.s_addr != lease->addr))) {
 775                 msg = DHCPV4_MSG_NAK;
 776                 /*
 777                  * DHCP client requested an IP which we can't offer to him. Probably the
 778                  * client changed the network or the network has been changed. The reply
 779                  * type is set to DHCPV4_MSG_NAK, because the client should not use that IP.
 780                  *
 781                  * For modern devices we build an answer that includes a valid IP, like
 782                  * a DHCPV4_MSG_ACK. The client will use that IP and doesn't need to
 783                  * perform additional DHCP round trips.
 784                  *
 785                  */
 786
 787                 /*
 788                  *
 789                  * Buggy clients do serverid checking in nack messages; therefore set the
 790                  * serverid in nack messages triggered by a previous force renew equal to
 791                  * the server id in use at that time by the server
 792                  *
 793                  */
 794                 if (fr_serverid)
 795                         serverid = fr_serverid;
 796
 797                 if (req->ciaddr.s_addr &&
 798                                 ((iface->dhcpv4_start_ip.s_addr & iface->dhcpv4_mask.s_addr) !=
 799                                  (req->ciaddr.s_addr & iface->dhcpv4_mask.s_addr)))
 800                         req->ciaddr.s_addr = INADDR_ANY;
 801         }
 802
 803         syslog(LOG_WARNING, "received %s from %s", dhcpv4_msg_to_string(reqmsg),
 804                         odhcpd_print_mac(req->chaddr, req->hlen));
 805
 806 #ifdef WITH_UBUS
 807         if (reqmsg == DHCPV4_MSG_RELEASE)
 808                 ubus_bcast_dhcp_event("dhcp.release", req->chaddr, req->hlen,
 809                                         &req->ciaddr, hostname, iface->ifname);
 810 #endif
 811         if (reqmsg == DHCPV4_MSG_DECLINE || reqmsg == DHCPV4_MSG_RELEASE)
 812                 return;
 813
 814         dhcpv4_put(&reply, &cookie, DHCPV4_OPT_MESSAGE, 1, &msg);
 815         dhcpv4_put(&reply, &cookie, DHCPV4_OPT_SERVERID, 4, &serverid);
 816
 817         if (lease) {
 818                 uint32_t val;
 819
 820                 reply.yiaddr.s_addr = lease->addr;
 821
 822                 val = htonl(leasetime);
 823                 dhcpv4_put(&reply, &cookie, DHCPV4_OPT_LEASETIME, 4, &val);
 824
 825                 if (leasetime != UINT32_MAX) {
 826                         val = htonl(500 * leasetime / 1000);
 827                         dhcpv4_put(&reply, &cookie, DHCPV4_OPT_RENEW, 4, &val);
 828
 829                         val = htonl(875 * leasetime / 1000);
 830                         dhcpv4_put(&reply, &cookie, DHCPV4_OPT_REBIND, 4, &val);
 831                 }
 832
 833                 dhcpv4_put(&reply, &cookie, DHCPV4_OPT_NETMASK, 4,
 834                                 &iface->dhcpv4_mask.s_addr);
 835
 836                 if (lease->hostname)
 837                         dhcpv4_put(&reply, &cookie, DHCPV4_OPT_HOSTNAME,
 838                                         strlen(lease->hostname), lease->hostname);
 839
 840                 if (iface->dhcpv4_bcast.s_addr != INADDR_ANY)
 841                         dhcpv4_put(&reply, &cookie, DHCPV4_OPT_BROADCAST, 4, &iface->dhcpv4_bcast);
 842
 843                 if (incl_fr_opt) {
 844                         if (reqmsg == DHCPV4_MSG_REQUEST) {
 845                                 struct dhcpv4_auth_forcerenew auth = {
 846                                         .protocol = 3,
 847                                         .algorithm = 1,
 848                                         .rdm = 0,
 849                                         .replay = {htonl(time(NULL)), htonl(++serial)},
 850                                         .type = 1,
 851                                         .key = {0},
 852                                 };
 853
 854                                 memcpy(auth.key, lease->key, sizeof(auth.key));
 855                                 dhcpv4_put(&reply, &cookie, DHCPV4_OPT_AUTHENTICATION, sizeof(auth), &auth);
 856                         } else {
 857                                 uint8_t one = 1;
 858                                 dhcpv4_put(&reply, &cookie, DHCPV4_OPT_FORCERENEW_NONCE_CAPABLE,
 859                                         sizeof(one), &one);
 860                         }
 861                 }
 862         }
 863
 864         struct ifreq ifr;
 865
 866         memset(&ifr, 0, sizeof(ifr));
 867         strncpy(ifr.ifr_name, iface->ifname, sizeof(ifr.ifr_name) - 1);
 868
 869         if (!ioctl(sock, SIOCGIFMTU, &ifr)) {
 870                 uint16_t mtu = htons(ifr.ifr_mtu);
 871                 dhcpv4_put(&reply, &cookie, DHCPV4_OPT_MTU, 2, &mtu);
 872         }
 873
 874         if (iface->search && iface->search_len <= 255)
 875                 dhcpv4_put(&reply, &cookie, DHCPV4_OPT_SEARCH_DOMAIN,
 876                                 iface->search_len, iface->search);
 877         else if (!res_init() && _res.dnsrch[0] && _res.dnsrch[0][0]) {
 878                 uint8_t search_buf[256];
 879                 int len = dn_comp(_res.dnsrch[0], search_buf,
 880                                                 sizeof(search_buf), NULL, NULL);
 881                 if (len > 0)
 882                         dhcpv4_put(&reply, &cookie, DHCPV4_OPT_SEARCH_DOMAIN,
 883                                         len, search_buf);
 884         }
 885
 886         if (iface->dhcpv4_router_cnt == 0)
 887                 dhcpv4_put(&reply, &cookie, DHCPV4_OPT_ROUTER, 4, &iface->dhcpv4_local);
 888         else
 889                 dhcpv4_put(&reply, &cookie, DHCPV4_OPT_ROUTER,
 890                                 4 * iface->dhcpv4_router_cnt, iface->dhcpv4_router);
 891
 892
 893         if (iface->dhcpv4_dns_cnt == 0)
 894                 dhcpv4_put(&reply, &cookie, DHCPV4_OPT_DNSSERVER, 4, &iface->dhcpv4_local);
 895         else
 896                 dhcpv4_put(&reply, &cookie, DHCPV4_OPT_DNSSERVER,
 897                                 4 * iface->dhcpv4_dns_cnt, iface->dhcpv4_dns);
 898
 899
 900         dhcpv4_put(&reply, &cookie, DHCPV4_OPT_END, 0, NULL);
 901
 902         struct sockaddr_in dest = *((struct sockaddr_in*)addr);
 903         if (req->giaddr.s_addr) {
 904                 /*
 905                  * relay agent is configured, send reply to the agent
 906                  */
 907                 dest.sin_addr = req->giaddr;
 908                 dest.sin_port = htons(DHCPV4_SERVER_PORT);
 909         } else if (req->ciaddr.s_addr && req->ciaddr.s_addr != dest.sin_addr.s_addr) {
 910                 /*
 911                  * client has existing configuration (ciaddr is set) AND this address is
 912                  * not the address it used for the dhcp message
 913                  */
 914                 dest.sin_addr = req->ciaddr;
 915                 dest.sin_port = htons(DHCPV4_CLIENT_PORT);
 916         } else if ((ntohs(req->flags) & DHCPV4_FLAG_BROADCAST) ||
 917                         req->hlen != reply.hlen || !reply.yiaddr.s_addr) {
 918                 /*
 919                  * client requests a broadcast reply OR we can't offer an IP
 920                  */
 921                 dest.sin_addr.s_addr = INADDR_BROADCAST;
 922                 dest.sin_port = htons(DHCPV4_CLIENT_PORT);
 923         } else if (!req->ciaddr.s_addr && msg == DHCPV4_MSG_NAK) {
 924                 /*
 925                  * client has no previous configuration -> no IP, so we need to reply
 926                  * with a broadcast packet
 927                  */
 928                 dest.sin_addr.s_addr = INADDR_BROADCAST;
 929                 dest.sin_port = htons(DHCPV4_CLIENT_PORT);
 930         } else {
 931                 struct arpreq arp = {.arp_flags = ATF_COM};
 932
 933                 /*
 934                  * send reply to the newly (in this proccess) allocated IP
 935                  */
 936                 dest.sin_addr = reply.yiaddr;
 937                 dest.sin_port = htons(DHCPV4_CLIENT_PORT);
 938
 939                 memcpy(arp.arp_ha.sa_data, req->chaddr, 6);
 940                 memcpy(&arp.arp_pa, &dest, sizeof(arp.arp_pa));
 941                 memcpy(arp.arp_dev, iface->ifname, sizeof(arp.arp_dev));
 942
 943                 if (ioctl(sock, SIOCSARP, &arp) < 0)
 944                         syslog(LOG_ERR, "ioctl(SIOCSARP): %m");
 945         }
 946
 947         if (sendto(sock, &reply, sizeof(reply), MSG_DONTWAIT,
 948                         (struct sockaddr*)&dest, sizeof(dest)) < 0)
 949                 syslog(LOG_ERR, "Failed to send %s to %s - %s: %m",
 950                         dhcpv4_msg_to_string(msg),
 951                         dest.sin_addr.s_addr == INADDR_BROADCAST ?
 952                         "ff:ff:ff:ff:ff:ff": odhcpd_print_mac(req->chaddr, req->hlen),
 953                         inet_ntoa(dest.sin_addr));
 954         else
 955                 syslog(LOG_ERR, "Sent %s to %s - %s",
 956                         dhcpv4_msg_to_string(msg),
 957                         dest.sin_addr.s_addr == INADDR_BROADCAST ?
 958                         "ff:ff:ff:ff:ff:ff": odhcpd_print_mac(req->chaddr, req->hlen),
 959                         inet_ntoa(dest.sin_addr));
 960
 961
 962 #ifdef WITH_UBUS
 963         if (msg == DHCPV4_MSG_ACK)
 964                 ubus_bcast_dhcp_event("dhcp.ack", req->chaddr, req->hlen, &reply.yiaddr,
 965                                         hostname, iface->ifname);
 966 #endif
 967 }
 968
 969 static bool dhcpv4_assign(struct interface *iface,
 970                 struct dhcpv4_assignment *assign, uint32_t raddr)
 971 {
 972         uint32_t start = ntohl(iface->dhcpv4_start_ip.s_addr);
 973         uint32_t end = ntohl(iface->dhcpv4_end_ip.s_addr);
 974         uint32_t count = end - start + 1;
 975
 976         /* try to assign the IP the client asked for */
 977         if (start <= ntohl(raddr) && ntohl(raddr) <= end &&
 978                         !find_assignment_by_addr(iface, raddr)) {
 979                 assign->addr = raddr;
 980                 syslog(LOG_INFO, "assigning the IP the client asked for: %u.%u.%u.%u",
 981                                 ((uint8_t *)&assign->addr)[0],
 982                                 ((uint8_t *)&assign->addr)[1],
 983                                 ((uint8_t *)&assign->addr)[2],
 984                                 ((uint8_t *)&assign->addr)[3]);
 985                 return true;
 986         }
 987
 988         /* Seed RNG with checksum of hwaddress */
 989         uint32_t seed = 0;
 990         for (size_t i = 0; i < sizeof(assign->hwaddr); ++i) {
 991                 /* Knuth's multiplicative method */
 992                 uint8_t o = assign->hwaddr[i];
 993                 seed += (o*2654435761) % UINT32_MAX;
 994         }
 995
 996         srand(seed);
 997
 998         uint32_t try = (((uint32_t)rand()) % count) + start;
 999
1000         if (list_empty(&iface->dhcpv4_assignments)) {
1001                 assign->addr = htonl(try);
1002                 syslog(LOG_INFO, "assigning mapped IP (empty list): %u.%u.%u.%u",
1003                                 ((uint8_t *)&assign->addr)[0],
1004                                 ((uint8_t *)&assign->addr)[1],
1005                                 ((uint8_t *)&assign->addr)[2],
1006                                 ((uint8_t *)&assign->addr)[3]);
1007                 return true;
1008         }
1009
1010         for (uint32_t i = 0; i < count; ++i) {
1011                 if (!find_assignment_by_addr(iface, htonl(try))) {
1012                         /* test was successful: IP address is not assigned, assign it */
1013                         assign->addr = htonl(try);
1014                         syslog(LOG_DEBUG, "assigning mapped IP: %u.%u.%u.%u (try %u of %u)",
1015                                         ((uint8_t *)&assign->addr)[0],
1016                                         ((uint8_t *)&assign->addr)[1],
1017                                         ((uint8_t *)&assign->addr)[2],
1018                                         ((uint8_t *)&assign->addr)[3],
1019                                         i, count);
1020                         return true;
1021                 }
1022                 try = (((try - start) + 1) % count) + start;
1023         }
1024
1025         syslog(LOG_WARNING, "can't assign any IP address -> address space is full");
1026         return false;
1027 }
1028
1029
1030 static struct dhcpv4_assignment* dhcpv4_lease(struct interface *iface,
1031                 enum dhcpv4_msg msg, const uint8_t *mac, const uint32_t reqaddr,
1032                 uint32_t *leasetime, const char *hostname, const size_t hostname_len,
1033                 const bool accept_fr_nonce, bool *incl_fr_opt, uint32_t *fr_serverid)
1034 {
1035         struct dhcpv4_assignment *a = find_assignment_by_hwaddr(iface, mac);
1036         struct dhcpv4_assignment *lease = NULL;
1037         time_t now = odhcpd_time();
1038
1039         if (a && (a->flags & OAF_BOUND) && a->fr_ip) {
1040                 *fr_serverid = a->fr_ip->addr.addr.in.s_addr;
1041                 dhcpv4_fr_stop(a);
1042         }
1043
1044         if (msg == DHCPV4_MSG_DISCOVER || msg == DHCPV4_MSG_REQUEST) {
1045                 bool assigned = !!a;
1046
1047                 if (!a) {
1048                         if (!iface->no_dynamic_dhcp) {
1049                                 /* Create new binding */
1050                                 a = calloc(1, sizeof(*a));
1051                                 if (!a) {
1052                                         syslog(LOG_ERR, "Failed to calloc binding on interface %s",
1053                                                         iface->ifname);
1054                                         return NULL;
1055                                 }
1056                                 memcpy(a->hwaddr, mac, sizeof(a->hwaddr));
1057                                 /* Don't consider new assignment as infinite */
1058                                 a->valid_until = now;
1059
1060                                 assigned = dhcpv4_assign(iface, a, reqaddr);
1061                                 if (assigned) {
1062                                         a->iface = iface;
1063                                         list_add(&a->head, &iface->dhcpv4_assignments);
1064                                 }
1065                         }
1066                 } else if ((a->addr & iface->dhcpv4_mask.s_addr) !=
1067                                 (iface->dhcpv4_start_ip.s_addr & iface->dhcpv4_mask.s_addr)) {
1068                         list_del(&a->head);
1069
1070                         assigned = dhcpv4_assign(iface, a, reqaddr);
1071                         if (assigned)
1072                                 list_add(&a->head, &iface->dhcpv4_assignments);
1073                 }
1074
1075                 if (assigned) {
1076                         uint32_t my_leasetime;
1077
1078                         if (a->leasetime)
1079                                 my_leasetime = a->leasetime;
1080                         else
1081                                 my_leasetime = iface->dhcpv4_leasetime;
1082
1083                         if ((*leasetime == 0) || (my_leasetime < *leasetime))
1084                                 *leasetime = my_leasetime;
1085
1086                         if (msg == DHCPV4_MSG_DISCOVER) {
1087                                 a->flags &= ~OAF_BOUND;
1088
1089                                 *incl_fr_opt = accept_fr_nonce;
1090                                 if (!(a->flags & OAF_STATIC))
1091                                         a->valid_until = now;
1092                         } else {
1093                                 if (hostname_len > 0) {
1094                                         a->hostname = realloc(a->hostname, hostname_len + 1);
1095                                         if (a->hostname) {
1096                                                 memcpy(a->hostname, hostname, hostname_len);
1097                                                 a->hostname[hostname_len] = 0;
1098                                         }
1099                                 }
1100
1101                                 if (!(a->flags & OAF_BOUND)) {
1102                                         a->accept_fr_nonce = accept_fr_nonce;
1103                                         *incl_fr_opt = accept_fr_nonce;
1104                                         odhcpd_urandom(a->key, sizeof(a->key));
1105                                         a->flags |= OAF_BOUND;
1106                                 } else
1107                                         *incl_fr_opt = false;
1108
1109                                 if (!(a->flags & OAF_STATIC))
1110                                         a->valid_until = ((*leasetime == UINT32_MAX) ? 0 : (time_t)(now + *leasetime));
1111                         }
1112                 } else if (!assigned && a) {
1113                         /* Cleanup failed assignment */
1114                         free_dhcpv4_assignment(a);
1115                         a = NULL;
1116                 }
1117
1118                 if (assigned && a)
1119                         lease = a;
1120         } else if (msg == DHCPV4_MSG_RELEASE && a) {
1121                 a->flags &= ~OAF_BOUND;
1122
1123                 if (!(a->flags & OAF_STATIC))
1124                         a->valid_until = now - 1;
1125
1126         } else if (msg == DHCPV4_MSG_DECLINE && a) {
1127                 a->flags &= ~OAF_BOUND;
1128
1129                 if (!(a->flags & OAF_STATIC)) {
1130                         memset(a->hwaddr, 0, sizeof(a->hwaddr));
1131                         a->valid_until = now + 3600; /* Block address for 1h */
1132                 }
1133         }
1134
1135         dhcpv6_write_statefile();
1136
1137         return lease;
1138 }