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