src/odhcpd.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 <errno.h>
  17 #include <fcntl.h>
  18 #include <stdio.h>
  19 #include <resolv.h>
  20 #include <getopt.h>
  21 #include <stddef.h>
  22 #include <stdlib.h>
  23 #include <string.h>
  24 #include <unistd.h>
  25 #include <signal.h>
  26 #include <stdbool.h>
  27 #include <syslog.h>
  28 #include <alloca.h>
  29
  30 #include <arpa/inet.h>
  31 #include <net/if.h>
  32 #include <netinet/ip6.h>
  33 #include <netpacket/packet.h>
  34 #include <linux/netlink.h>
  35 #include <linux/if_addr.h>
  36 #include <linux/neighbour.h>
  37 #include <linux/rtnetlink.h>
  38
  39 #include <sys/socket.h>
  40 #include <sys/ioctl.h>
  41 #include <sys/epoll.h>
  42 #include <sys/types.h>
  43 #include <sys/wait.h>
  44 #include <sys/syscall.h>
  45
  46 #include <netlink/msg.h>
  47 #include <netlink/socket.h>
  48 #include <netlink/attr.h>
  49 #include <libubox/uloop.h>
  50 #include "odhcpd.h"
  51
  52
  53
  54 static int ioctl_sock;
  55 static struct nl_sock *rtnl_socket = NULL;
  56 static int urandom_fd = -1;
  57
  58 static void sighandler(_unused int signal)
  59 {
  60         uloop_end();
  61 }
  62
  63 static void print_usage(const char *app)
  64 {
  65         printf(
  66         "== %s Usage ==\n\n"
  67         "  -h, --help   Print this help\n"
  68         "  -l level     Specify log level 0..7 (default %d)\n",
  69                 app, config.log_level
  70         );
  71 }
  72
  73 int main(int argc, char **argv)
  74 {
  75         openlog("odhcpd", LOG_PERROR | LOG_PID, LOG_DAEMON);
  76         int opt;
  77
  78         while ((opt = getopt(argc, argv, "hl:")) != -1) {
  79                 switch (opt) {
  80                 case 'h':
  81                         print_usage(argv[0]);
  82                         return 0;
  83                 case 'l':
  84                         config.log_level = (atoi(optarg) & LOG_PRIMASK);
  85                         fprintf(stderr, "Log level set to %d\n", config.log_level);
  86                         break;
  87                 }
  88         }
  89         setlogmask(LOG_UPTO(config.log_level));
  90         uloop_init();
  91
  92         if (getuid() != 0) {
  93                 syslog(LOG_ERR, "Must be run as root!");
  94                 return 2;
  95         }
  96
  97         ioctl_sock = socket(AF_INET, SOCK_DGRAM | SOCK_CLOEXEC, 0);
  98
  99         if (!(rtnl_socket = odhcpd_create_nl_socket(NETLINK_ROUTE))) {
 100                 syslog(LOG_ERR, "Unable to open nl socket: %s", strerror(errno));
 101                 return 2;
 102         }
 103
 104         if ((urandom_fd = open("/dev/urandom", O_RDONLY | O_CLOEXEC)) < 0)
 105                 return 4;
 106
 107         signal(SIGUSR1, SIG_IGN);
 108         signal(SIGINT, sighandler);
 109         signal(SIGTERM, sighandler);
 110
 111         if (init_router())
 112                 return 4;
 113
 114         if (init_dhcpv6())
 115                 return 4;
 116
 117         if (init_ndp())
 118                 return 4;
 119
 120         if (init_dhcpv4())
 121                 return 4;
 122
 123         odhcpd_run();
 124         return 0;
 125 }
 126
 127 struct nl_sock *odhcpd_create_nl_socket(int protocol)
 128 {
 129         struct nl_sock *nl_sock;
 130
 131         nl_sock = nl_socket_alloc();
 132         if (!nl_sock)
 133                 goto err;
 134
 135         if (nl_connect(nl_sock, protocol) < 0)
 136                 goto err;
 137
 138         return nl_sock;
 139
 140 err:
 141         if (nl_sock)
 142                 nl_socket_free(nl_sock);
 143
 144         return NULL;
 145 }
 146
 147
 148 // Read IPv6 MTU for interface
 149 int odhcpd_get_interface_config(const char *ifname, const char *what)
 150 {
 151         char buf[64];
 152         const char *sysctl_pattern = "/proc/sys/net/ipv6/conf/%s/%s";
 153         snprintf(buf, sizeof(buf), sysctl_pattern, ifname, what);
 154
 155         int fd = open(buf, O_RDONLY);
 156         ssize_t len = read(fd, buf, sizeof(buf) - 1);
 157         close(fd);
 158
 159         if (len < 0)
 160                 return -1;
 161
 162         buf[len] = 0;
 163         return atoi(buf);
 164 }
 165
 166
 167 // Read IPv6 MAC for interface
 168 int odhcpd_get_mac(const struct interface *iface, uint8_t mac[6])
 169 {
 170         struct ifreq ifr;
 171         memset(&ifr, 0, sizeof(ifr));
 172         strncpy(ifr.ifr_name, iface->ifname, sizeof(ifr.ifr_name));
 173         if (ioctl(ioctl_sock, SIOCGIFHWADDR, &ifr) < 0)
 174                 return -1;
 175         memcpy(mac, ifr.ifr_hwaddr.sa_data, 6);
 176         return 0;
 177 }
 178
 179
 180 // Forwards a packet on a specific interface
 181 ssize_t odhcpd_send(int socket, struct sockaddr_in6 *dest,
 182                 struct iovec *iov, size_t iov_len,
 183                 const struct interface *iface)
 184 {
 185         // Construct headers
 186         uint8_t cmsg_buf[CMSG_SPACE(sizeof(struct in6_pktinfo))] = {0};
 187         struct msghdr msg = {
 188                 .msg_name = (void *) dest,
 189                 .msg_namelen = sizeof(*dest),
 190                 .msg_iov = iov,
 191                 .msg_iovlen = iov_len,
 192                 .msg_control = cmsg_buf,
 193                 .msg_controllen = sizeof(cmsg_buf),
 194                 .msg_flags = 0
 195         };
 196
 197         // Set control data (define destination interface)
 198         struct cmsghdr *chdr = CMSG_FIRSTHDR(&msg);
 199         chdr->cmsg_level = IPPROTO_IPV6;
 200         chdr->cmsg_type = IPV6_PKTINFO;
 201         chdr->cmsg_len = CMSG_LEN(sizeof(struct in6_pktinfo));
 202         struct in6_pktinfo *pktinfo = (struct in6_pktinfo*)CMSG_DATA(chdr);
 203         pktinfo->ipi6_ifindex = iface->ifindex;
 204
 205         // Also set scope ID if link-local
 206         if (IN6_IS_ADDR_LINKLOCAL(&dest->sin6_addr)
 207                         || IN6_IS_ADDR_MC_LINKLOCAL(&dest->sin6_addr))
 208                 dest->sin6_scope_id = iface->ifindex;
 209
 210         char ipbuf[INET6_ADDRSTRLEN];
 211         inet_ntop(AF_INET6, &dest->sin6_addr, ipbuf, sizeof(ipbuf));
 212
 213         ssize_t sent = sendmsg(socket, &msg, MSG_DONTWAIT);
 214         if (sent < 0)
 215                 syslog(LOG_NOTICE, "Failed to send to %s%%%s (%s)",
 216                                 ipbuf, iface->ifname, strerror(errno));
 217         else
 218                 syslog(LOG_DEBUG, "Sent %li bytes to %s%%%s",
 219                                 (long)sent, ipbuf, iface->ifname);
 220         return sent;
 221 }
 222
 223 struct addr_info {
 224         int ifindex;
 225         int af;
 226         struct odhcpd_ipaddr **addrs;
 227         int pending;
 228         ssize_t ret;
 229 };
 230
 231 static int cb_valid_handler(struct nl_msg *msg, void *arg)
 232 {
 233         struct addr_info *ctxt = (struct addr_info *)arg;
 234         struct odhcpd_ipaddr *addrs = *(ctxt->addrs);
 235         struct nlmsghdr *hdr = nlmsg_hdr(msg);
 236         struct ifaddrmsg *ifa;
 237         struct nlattr *nla[__IFA_MAX], *nla_addr = NULL;
 238
 239         if (hdr->nlmsg_type != RTM_NEWADDR)
 240                 return NL_SKIP;
 241
 242         ifa = NLMSG_DATA(hdr);
 243         if (ifa->ifa_scope != RT_SCOPE_UNIVERSE ||
 244                         (ctxt->af != ifa->ifa_family) ||
 245                         (ctxt->ifindex && ifa->ifa_index != (unsigned)ctxt->ifindex))
 246                 return NL_SKIP;
 247
 248         nlmsg_parse(hdr, sizeof(*ifa), nla, __IFA_MAX - 1, NULL);
 249
 250         switch (ifa->ifa_family) {
 251         case AF_INET6:
 252                 if (nla[IFA_ADDRESS])
 253                         nla_addr = nla[IFA_ADDRESS];
 254                 break;
 255
 256         case AF_INET:
 257                 if (nla[IFA_LOCAL])
 258                         nla_addr = nla[IFA_LOCAL];
 259                 break;
 260
 261         default:
 262                 break;
 263         }
 264         if (!nla_addr)
 265                 return NL_SKIP;
 266
 267         addrs = realloc(addrs, sizeof(*addrs)*(ctxt->ret + 1));
 268         if (!addrs)
 269                 return NL_SKIP;
 270
 271         memset(&addrs[ctxt->ret], 0, sizeof(addrs[ctxt->ret]));
 272         addrs[ctxt->ret].prefix = ifa->ifa_prefixlen;
 273
 274         nla_memcpy(&addrs[ctxt->ret].addr, nla_addr,
 275                         sizeof(addrs[ctxt->ret].addr));
 276
 277         if (nla[IFA_BROADCAST])
 278                 nla_memcpy(&addrs[ctxt->ret].broadcast, nla[IFA_BROADCAST],
 279                                 sizeof(addrs[ctxt->ret].broadcast));
 280
 281         if (nla[IFA_CACHEINFO]) {
 282                 struct ifa_cacheinfo *ifc = nla_data(nla[IFA_CACHEINFO]);
 283
 284                 addrs[ctxt->ret].preferred = ifc->ifa_prefered;
 285                 addrs[ctxt->ret].valid = ifc->ifa_valid;
 286         }
 287
 288         if (ifa->ifa_flags & IFA_F_DEPRECATED)
 289                 addrs[ctxt->ret].preferred = 0;
 290
 291         ctxt->ret++;
 292         *(ctxt->addrs) = addrs;
 293
 294         return NL_OK;
 295 }
 296
 297 static int cb_finish_handler(_unused struct nl_msg *msg, void *arg)
 298 {
 299         struct addr_info *ctxt = (struct addr_info *)arg;
 300
 301         ctxt->pending = 0;
 302
 303         return NL_STOP;
 304 }
 305
 306 static int cb_error_handler(_unused struct sockaddr_nl *nla, struct nlmsgerr *err,
 307                 void *arg)
 308 {
 309         struct addr_info *ctxt = (struct addr_info *)arg;
 310
 311         ctxt->pending = 0;
 312         ctxt->ret = err->error;
 313
 314         return NL_STOP;
 315 }
 316
 317 static int prefix_cmp(const void *va, const void *vb)
 318 {
 319         const struct odhcpd_ipaddr *a = va, *b = vb;
 320         return (ntohl(a->addr.in.s_addr) < ntohl(b->addr.in.s_addr)) ? 1 :
 321                 (ntohl(a->addr.in.s_addr) > ntohl(b->addr.in.s_addr)) ? -1 : 0;
 322 }
 323
 324 // compare IPv6 prefixes
 325 static int prefix6_cmp(const void *va, const void *vb)
 326 {
 327         const struct odhcpd_ipaddr *a = va, *b = vb;
 328         uint32_t a_pref = IN6_IS_ADDR_ULA(&a->addr.in6) ? 1 : a->preferred;
 329         uint32_t b_pref = IN6_IS_ADDR_ULA(&b->addr.in6) ? 1 : b->preferred;
 330         return (a_pref < b_pref) ? 1 : (a_pref > b_pref) ? -1 : 0;
 331 }
 332
 333 // Detect an IPV6-address currently assigned to the given interface
 334 ssize_t odhcpd_get_interface_addresses(int ifindex, bool v6, struct odhcpd_ipaddr **addrs)
 335 {
 336         struct nl_msg *msg;
 337         struct ifaddrmsg ifa = {
 338                 .ifa_family = v6? AF_INET6: AF_INET,
 339                 .ifa_prefixlen = 0,
 340                 .ifa_flags = 0,
 341                 .ifa_scope = 0,
 342                 .ifa_index = ifindex, };
 343         struct nl_cb *cb = nl_cb_alloc(NL_CB_DEFAULT);
 344         struct addr_info ctxt = {
 345                 .ifindex = ifindex,
 346                 .af = v6? AF_INET6: AF_INET,
 347                 .addrs = addrs,
 348                 .ret = 0,
 349                 .pending = 1,
 350         };
 351
 352         if (!cb) {
 353                 ctxt.ret = -1;
 354                 goto out;
 355         }
 356
 357         msg = nlmsg_alloc_simple(RTM_GETADDR, NLM_F_REQUEST | NLM_F_DUMP);
 358
 359         if (!msg) {
 360                 ctxt.ret = - 1;
 361                 goto out;
 362         }
 363
 364         nlmsg_append(msg, &ifa, sizeof(ifa), 0);
 365
 366         nl_cb_set(cb, NL_CB_VALID, NL_CB_CUSTOM, cb_valid_handler, &ctxt);
 367         nl_cb_set(cb, NL_CB_FINISH, NL_CB_CUSTOM, cb_finish_handler, &ctxt);
 368         nl_cb_err(cb, NL_CB_CUSTOM, cb_error_handler, &ctxt);
 369
 370         nl_send_auto_complete(rtnl_socket, msg);
 371         while (ctxt.pending > 0)
 372                 nl_recvmsgs(rtnl_socket, cb);
 373
 374         nlmsg_free(msg);
 375
 376         if (ctxt.ret <= 0)
 377                 goto out;
 378
 379         time_t now = odhcpd_time();
 380         struct odhcpd_ipaddr *addr = *addrs;
 381
 382         qsort(addr, ctxt.ret, sizeof(*addr), v6 ? prefix6_cmp : prefix_cmp);
 383
 384         for (ssize_t i = 0; i < ctxt.ret; ++i) {
 385                 if (addr[i].preferred < UINT32_MAX - now)
 386                         addr[i].preferred += now;
 387
 388                 if (addr[i].valid < UINT32_MAX - now)
 389                         addr[i].valid += now;
 390         }
 391
 392 out:
 393         nl_cb_put(cb);
 394
 395         return ctxt.ret;
 396 }
 397
 398 static int odhcpd_get_linklocal_interface_address(int ifindex, struct in6_addr *lladdr)
 399 {
 400         int status = -1;
 401         struct sockaddr_in6 addr = {AF_INET6, 0, 0, ALL_IPV6_ROUTERS, ifindex};
 402         socklen_t alen = sizeof(addr);
 403         int sock = socket(AF_INET6, SOCK_RAW, IPPROTO_ICMPV6);
 404
 405         if (!connect(sock, (struct sockaddr*)&addr, sizeof(addr)) &&
 406                         !getsockname(sock, (struct sockaddr*)&addr, &alen)) {
 407                 *lladdr = addr.sin6_addr;
 408                 status = 0;
 409         }
 410
 411         close(sock);
 412
 413         return status;
 414 }
 415
 416 /*
 417  * DNS address selection criteria order :
 418  * - use IPv6 address with valid lifetime if none is yet selected
 419  * - use IPv6 address with a preferred lifetime if the already selected IPv6 address is deprecated
 420  * - use an IPv6 ULA address if the already selected IPv6 address is not an ULA address
 421  * - use the IPv6 address with the longest preferred lifetime
 422  */
 423 int odhcpd_get_interface_dns_addr(const struct interface *iface, struct in6_addr *addr)
 424 {
 425         time_t now = odhcpd_time();
 426         ssize_t m = -1;
 427
 428         for (size_t i = 0; i < iface->ia_addr_len; ++i) {
 429                 if (iface->ia_addr[i].valid <= (uint32_t)now)
 430                         continue;
 431
 432                 if (m < 0) {
 433                         m = i;
 434                         continue;
 435                 }
 436
 437                 if (iface->ia_addr[m].preferred >= (uint32_t)now &&
 438                                 iface->ia_addr[i].preferred < (uint32_t)now)
 439                         continue;
 440
 441                 if (IN6_IS_ADDR_ULA(&iface->ia_addr[i].addr.in6)) {
 442                         if (!IN6_IS_ADDR_ULA(&iface->ia_addr[m].addr.in6)) {
 443                                 m = i;
 444                                 continue;
 445                         }
 446                 } else if (IN6_IS_ADDR_ULA(&iface->ia_addr[m].addr.in6))
 447                         continue;
 448
 449                 if (iface->ia_addr[i].preferred > iface->ia_addr[m].preferred)
 450                         m = i;
 451         }
 452
 453         if (m >= 0) {
 454                 *addr = iface->ia_addr[m].addr.in6;
 455                 return 0;
 456         }
 457
 458         return odhcpd_get_linklocal_interface_address(iface->ifindex, addr);
 459 }
 460
 461 int odhcpd_setup_route(const struct in6_addr *addr, const int prefixlen,
 462                 const struct interface *iface, const struct in6_addr *gw,
 463                 const uint32_t metric, const bool add)
 464 {
 465         struct nl_msg *msg;
 466         struct rtmsg rtm = {
 467                 .rtm_family = AF_INET6,
 468                 .rtm_dst_len = prefixlen,
 469                 .rtm_src_len = 0,
 470                 .rtm_table = RT_TABLE_MAIN,
 471                 .rtm_protocol = (add ? RTPROT_STATIC : RTPROT_UNSPEC),
 472                 .rtm_scope = (add ? (gw ? RT_SCOPE_UNIVERSE : RT_SCOPE_LINK) : RT_SCOPE_NOWHERE),
 473                 .rtm_type = (add ? RTN_UNICAST : RTN_UNSPEC),
 474         };
 475         int ret = 0;
 476
 477         msg = nlmsg_alloc_simple(add ? RTM_NEWROUTE : RTM_DELROUTE,
 478                                         add ? NLM_F_CREATE | NLM_F_REPLACE : 0);
 479         if (!msg)
 480                 return -1;
 481
 482         nlmsg_append(msg, &rtm, sizeof(rtm), 0);
 483
 484         nla_put(msg, RTA_DST, sizeof(*addr), addr);
 485         nla_put_u32(msg, RTA_OIF, iface->ifindex);
 486         nla_put_u32(msg, RTA_PRIORITY, metric);
 487
 488         if (gw)
 489                 nla_put(msg, RTA_GATEWAY, sizeof(*gw), gw);
 490
 491         ret = nl_send_auto_complete(rtnl_socket, msg);
 492         nlmsg_free(msg);
 493
 494         if (ret < 0)
 495                 return ret;
 496
 497         return nl_wait_for_ack(rtnl_socket);
 498 }
 499
 500 int odhcpd_setup_proxy_neigh(const struct in6_addr *addr,
 501                 const struct interface *iface, const bool add)
 502 {
 503         struct nl_msg *msg;
 504         struct ndmsg ndm = {
 505                 .ndm_family = AF_INET6,
 506                 .ndm_flags = NTF_PROXY,
 507                 .ndm_ifindex = iface->ifindex,
 508         };
 509         int ret = 0, flags = NLM_F_REQUEST;
 510
 511         if (add)
 512                 flags |= NLM_F_REPLACE | NLM_F_CREATE;
 513
 514         msg = nlmsg_alloc_simple(add ? RTM_NEWNEIGH : RTM_DELNEIGH, flags);
 515         if (!msg)
 516                 return -1;
 517
 518         nlmsg_append(msg, &ndm, sizeof(ndm), 0);
 519
 520         nla_put(msg, NDA_DST, sizeof(*addr), addr);
 521
 522         ret = nl_send_auto_complete(rtnl_socket, msg);
 523         nlmsg_free(msg);
 524
 525         if (ret < 0)
 526                 return ret;
 527
 528         return nl_wait_for_ack(rtnl_socket);
 529 }
 530
 531 struct interface* odhcpd_get_interface_by_index(int ifindex)
 532 {
 533         struct interface *iface;
 534         list_for_each_entry(iface, &interfaces, head)
 535                 if (iface->ifindex == ifindex)
 536                         return iface;
 537
 538         return NULL;
 539 }
 540
 541
 542 struct interface* odhcpd_get_interface_by_name(const char *name)
 543 {
 544         struct interface *iface;
 545         list_for_each_entry(iface, &interfaces, head)
 546                 if (!strcmp(iface->ifname, name))
 547                         return iface;
 548
 549         return NULL;
 550 }
 551
 552
 553 struct interface* odhcpd_get_master_interface(void)
 554 {
 555         struct interface *iface;
 556         list_for_each_entry(iface, &interfaces, head)
 557                 if (iface->master)
 558                         return iface;
 559
 560         return NULL;
 561 }
 562
 563
 564 // Convenience function to receive and do basic validation of packets
 565 static void odhcpd_receive_packets(struct uloop_fd *u, _unused unsigned int events)
 566 {
 567         struct odhcpd_event *e = container_of(u, struct odhcpd_event, uloop);
 568
 569         uint8_t data_buf[8192], cmsg_buf[128];
 570         union {
 571                 struct sockaddr_in6 in6;
 572                 struct sockaddr_in in;
 573                 struct sockaddr_ll ll;
 574                 struct sockaddr_nl nl;
 575         } addr;
 576
 577         if (u->error) {
 578                 int ret = -1;
 579                 socklen_t ret_len = sizeof(ret);
 580                 getsockopt(u->fd, SOL_SOCKET, SO_ERROR, &ret, &ret_len);
 581                 u->error = false;
 582                 if (e->handle_error)
 583                         e->handle_error(e, ret);
 584         }
 585
 586         if (e->recv_msgs) {
 587                 e->recv_msgs(e);
 588                 return;
 589         }
 590
 591         while (true) {
 592                 struct iovec iov = {data_buf, sizeof(data_buf)};
 593                 struct msghdr msg = {
 594                         .msg_name = (void *) &addr,
 595                         .msg_namelen = sizeof(addr),
 596                         .msg_iov = &iov,
 597                         .msg_iovlen = 1,
 598                         .msg_control = cmsg_buf,
 599                         .msg_controllen = sizeof(cmsg_buf),
 600                         .msg_flags = 0
 601                 };
 602
 603                 ssize_t len = recvmsg(u->fd, &msg, MSG_DONTWAIT);
 604                 if (len < 0) {
 605                         if (errno == EAGAIN)
 606                                 break;
 607                         else
 608                                 continue;
 609                 }
 610
 611
 612                 // Extract destination interface
 613                 int destiface = 0;
 614                 int *hlim = NULL;
 615                 void *dest = NULL;
 616                 struct in6_pktinfo *pktinfo;
 617                 struct in_pktinfo *pkt4info;
 618                 for (struct cmsghdr *ch = CMSG_FIRSTHDR(&msg); ch != NULL; ch = CMSG_NXTHDR(&msg, ch)) {
 619                         if (ch->cmsg_level == IPPROTO_IPV6 &&
 620                                         ch->cmsg_type == IPV6_PKTINFO) {
 621                                 pktinfo = (struct in6_pktinfo*)CMSG_DATA(ch);
 622                                 destiface = pktinfo->ipi6_ifindex;
 623                                 dest = &pktinfo->ipi6_addr;
 624                         } else if (ch->cmsg_level == IPPROTO_IP &&
 625                                         ch->cmsg_type == IP_PKTINFO) {
 626                                 pkt4info = (struct in_pktinfo*)CMSG_DATA(ch);
 627                                 destiface = pkt4info->ipi_ifindex;
 628                                 dest = &pkt4info->ipi_addr;
 629                         } else if (ch->cmsg_level == IPPROTO_IPV6 &&
 630                                         ch->cmsg_type == IPV6_HOPLIMIT) {
 631                                 hlim = (int*)CMSG_DATA(ch);
 632                         }
 633                 }
 634
 635                 // Check hoplimit if received
 636                 if (hlim && *hlim != 255)
 637                         continue;
 638
 639                 // Detect interface for packet sockets
 640                 if (addr.ll.sll_family == AF_PACKET)
 641                         destiface = addr.ll.sll_ifindex;
 642
 643                 struct interface *iface =
 644                                 odhcpd_get_interface_by_index(destiface);
 645
 646                 if (!iface && addr.nl.nl_family != AF_NETLINK)
 647                         continue;
 648
 649                 char ipbuf[INET6_ADDRSTRLEN] = "kernel";
 650                 if (addr.ll.sll_family == AF_PACKET &&
 651                                 len >= (ssize_t)sizeof(struct ip6_hdr))
 652                         inet_ntop(AF_INET6, &data_buf[8], ipbuf, sizeof(ipbuf));
 653                 else if (addr.in6.sin6_family == AF_INET6)
 654                         inet_ntop(AF_INET6, &addr.in6.sin6_addr, ipbuf, sizeof(ipbuf));
 655                 else if (addr.in.sin_family == AF_INET)
 656                         inet_ntop(AF_INET, &addr.in.sin_addr, ipbuf, sizeof(ipbuf));
 657
 658                 syslog(LOG_DEBUG, "Received %li Bytes from %s%%%s", (long)len,
 659                                 ipbuf, (iface) ? iface->ifname : "netlink");
 660
 661                 e->handle_dgram(&addr, data_buf, len, iface, dest);
 662         }
 663 }
 664
 665 // Register events for the multiplexer
 666 int odhcpd_register(struct odhcpd_event *event)
 667 {
 668         event->uloop.cb = odhcpd_receive_packets;
 669         return uloop_fd_add(&event->uloop, ULOOP_READ |
 670                         ((event->handle_error) ? ULOOP_ERROR_CB : 0));
 671 }
 672
 673 int odhcpd_deregister(struct odhcpd_event *event)
 674 {
 675         event->uloop.cb = NULL;
 676         return uloop_fd_delete(&event->uloop);
 677 }
 678
 679 void odhcpd_process(struct odhcpd_event *event)
 680 {
 681         odhcpd_receive_packets(&event->uloop, 0);
 682 }
 683
 684 int odhcpd_urandom(void *data, size_t len)
 685 {
 686         return read(urandom_fd, data, len);
 687 }
 688
 689
 690 time_t odhcpd_time(void)
 691 {
 692         struct timespec ts;
 693         syscall(SYS_clock_gettime, CLOCK_MONOTONIC, &ts);
 694         return ts.tv_sec;
 695 }
 696
 697
 698 static const char hexdigits[] = "0123456789abcdef";
 699 static const int8_t hexvals[] = {
 700     -1, -1, -1, -1, -1, -1, -1, -1, -1, -2, -2, -1, -1, -2, -1, -1,
 701     -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1,
 702     -2, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1,
 703      0,  1,  2,  3,  4,  5,  6,  7,  8,  9, -1, -1, -1, -1, -1, -1,
 704     -1, 10, 11, 12, 13, 14, 15, -1, -1, -1, -1, -1, -1, -1, -1, -1,
 705     -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1,
 706     -1, 10, 11, 12, 13, 14, 15, -1, -1, -1, -1, -1, -1, -1, -1, -1,
 707     -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1,
 708 };
 709
 710 ssize_t odhcpd_unhexlify(uint8_t *dst, size_t len, const char *src)
 711 {
 712         size_t c;
 713         for (c = 0; c < len && src[0] && src[1]; ++c) {
 714                 int8_t x = (int8_t)*src++;
 715                 int8_t y = (int8_t)*src++;
 716                 if (x < 0 || (x = hexvals[x]) < 0
 717                                 || y < 0 || (y = hexvals[y]) < 0)
 718                         return -1;
 719                 dst[c] = x << 4 | y;
 720                 while (((int8_t)*src) < 0 ||
 721                                 (*src && hexvals[(uint8_t)*src] < 0))
 722                         src++;
 723         }
 724
 725         return c;
 726 }
 727
 728
 729 void odhcpd_hexlify(char *dst, const uint8_t *src, size_t len)
 730 {
 731         for (size_t i = 0; i < len; ++i) {
 732                 *dst++ = hexdigits[src[i] >> 4];
 733                 *dst++ = hexdigits[src[i] & 0x0f];
 734         }
 735         *dst = 0;
 736 }
 737
 738
 739 int odhcpd_bmemcmp(const void *av, const void *bv, size_t bits)
 740 {
 741         const uint8_t *a = av, *b = bv;
 742         size_t bytes = bits / 8;
 743         bits %= 8;
 744
 745         int res = memcmp(a, b, bytes);
 746         if (res == 0 && bits > 0)
 747                 res = (a[bytes] >> (8 - bits)) - (b[bytes] >> (8 - bits));
 748
 749         return res;
 750 }
 751
 752
 753 void odhcpd_bmemcpy(void *av, const void *bv, size_t bits)
 754 {
 755         uint8_t *a = av;
 756         const uint8_t *b = bv;
 757
 758         size_t bytes = bits / 8;
 759         bits %= 8;
 760         memcpy(a, b, bytes);
 761
 762         if (bits > 0) {
 763                 uint8_t mask = (1 << (8 - bits)) - 1;
 764                 a[bytes] = (a[bytes] & mask) | ((~mask) & b[bytes]);
 765         }
 766 }