2 * Copyright (C) 2012-2013 Steven Barth <steven@midlink.org>
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.
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.
30 #include <arpa/inet.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>
39 #include <sys/socket.h>
40 #include <sys/ioctl.h>
41 #include <sys/epoll.h>
42 #include <sys/types.h>
44 #include <sys/syscall.h>
46 #include <netlink/msg.h>
47 #include <netlink/socket.h>
48 #include <netlink/attr.h>
49 #include <libubox/uloop.h>
54 static int ioctl_sock;
55 static struct nl_sock *rtnl_socket = NULL;
56 static int urandom_fd = -1;
58 static void sighandler(_unused int signal)
63 static void print_usage(const char *app)
67 " -h, --help Print this help\n"
68 " -l level Specify log level 0..7 (default %d)\n",
73 int main(int argc, char **argv)
75 openlog("odhcpd", LOG_PERROR | LOG_PID, LOG_DAEMON);
78 while ((opt = getopt(argc, argv, "hl:")) != -1) {
84 config.log_level = (atoi(optarg) & LOG_PRIMASK);
85 fprintf(stderr, "Log level set to %d\n", config.log_level);
89 setlogmask(LOG_UPTO(config.log_level));
93 syslog(LOG_ERR, "Must be run as root!");
97 ioctl_sock = socket(AF_INET, SOCK_DGRAM | SOCK_CLOEXEC, 0);
99 if (!(rtnl_socket = odhcpd_create_nl_socket(NETLINK_ROUTE))) {
100 syslog(LOG_ERR, "Unable to open nl socket: %s", strerror(errno));
104 if ((urandom_fd = open("/dev/urandom", O_RDONLY | O_CLOEXEC)) < 0)
107 signal(SIGUSR1, SIG_IGN);
108 signal(SIGINT, sighandler);
109 signal(SIGTERM, sighandler);
127 struct nl_sock *odhcpd_create_nl_socket(int protocol)
129 struct nl_sock *nl_sock;
131 nl_sock = nl_socket_alloc();
135 if (nl_connect(nl_sock, protocol) < 0)
142 nl_socket_free(nl_sock);
148 // Read IPv6 MTU for interface
149 int odhcpd_get_interface_config(const char *ifname, const char *what)
152 const char *sysctl_pattern = "/proc/sys/net/ipv6/conf/%s/%s";
153 snprintf(buf, sizeof(buf), sysctl_pattern, ifname, what);
155 int fd = open(buf, O_RDONLY);
156 ssize_t len = read(fd, buf, sizeof(buf) - 1);
167 // Read IPv6 MAC for interface
168 int odhcpd_get_mac(const struct interface *iface, uint8_t mac[6])
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)
175 memcpy(mac, ifr.ifr_hwaddr.sa_data, 6);
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)
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),
191 .msg_iovlen = iov_len,
192 .msg_control = cmsg_buf,
193 .msg_controllen = sizeof(cmsg_buf),
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;
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;
210 char ipbuf[INET6_ADDRSTRLEN];
211 inet_ntop(AF_INET6, &dest->sin6_addr, ipbuf, sizeof(ipbuf));
213 ssize_t sent = sendmsg(socket, &msg, MSG_DONTWAIT);
215 syslog(LOG_NOTICE, "Failed to send to %s%%%s (%s)",
216 ipbuf, iface->ifname, strerror(errno));
218 syslog(LOG_DEBUG, "Sent %li bytes to %s%%%s",
219 (long)sent, ipbuf, iface->ifname);
226 struct odhcpd_ipaddr **addrs;
231 static int cb_valid_handler(struct nl_msg *msg, void *arg)
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;
239 if (hdr->nlmsg_type != RTM_NEWADDR)
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))
248 nlmsg_parse(hdr, sizeof(*ifa), nla, __IFA_MAX - 1, NULL);
250 switch (ifa->ifa_family) {
252 if (nla[IFA_ADDRESS])
253 nla_addr = nla[IFA_ADDRESS];
258 nla_addr = nla[IFA_LOCAL];
267 addrs = realloc(addrs, sizeof(*addrs)*(ctxt->ret + 1));
271 memset(&addrs[ctxt->ret], 0, sizeof(addrs[ctxt->ret]));
272 addrs[ctxt->ret].prefix = ifa->ifa_prefixlen;
274 nla_memcpy(&addrs[ctxt->ret].addr, nla_addr,
275 sizeof(addrs[ctxt->ret].addr));
277 if (nla[IFA_BROADCAST])
278 nla_memcpy(&addrs[ctxt->ret].broadcast, nla[IFA_BROADCAST],
279 sizeof(addrs[ctxt->ret].broadcast));
281 if (nla[IFA_CACHEINFO]) {
282 struct ifa_cacheinfo *ifc = nla_data(nla[IFA_CACHEINFO]);
284 addrs[ctxt->ret].preferred = ifc->ifa_prefered;
285 addrs[ctxt->ret].valid = ifc->ifa_valid;
288 if (ifa->ifa_flags & IFA_F_DEPRECATED)
289 addrs[ctxt->ret].preferred = 0;
292 *(ctxt->addrs) = addrs;
297 static int cb_finish_handler(_unused struct nl_msg *msg, void *arg)
299 struct addr_info *ctxt = (struct addr_info *)arg;
306 static int cb_error_handler(_unused struct sockaddr_nl *nla, struct nlmsgerr *err,
309 struct addr_info *ctxt = (struct addr_info *)arg;
312 ctxt->ret = err->error;
317 static int prefix_cmp(const void *va, const void *vb)
319 const struct odhcpd_ipaddr *a = va, *b = vb;
322 if (a->prefix == b->prefix) {
323 ret = (ntohl(a->addr.in.s_addr) < ntohl(b->addr.in.s_addr)) ? 1 :
324 (ntohl(a->addr.in.s_addr) > ntohl(b->addr.in.s_addr)) ? -1 : 0;
326 ret = a->prefix < b->prefix ? 1 : -1;
331 // compare IPv6 prefixes
332 static int prefix6_cmp(const void *va, const void *vb)
334 const struct odhcpd_ipaddr *a = va, *b = vb;
335 uint32_t a_pref = IN6_IS_ADDR_ULA(&a->addr.in6) ? 1 : a->preferred;
336 uint32_t b_pref = IN6_IS_ADDR_ULA(&b->addr.in6) ? 1 : b->preferred;
337 return (a_pref < b_pref) ? 1 : (a_pref > b_pref) ? -1 : 0;
340 // Detect an IPV6-address currently assigned to the given interface
341 ssize_t odhcpd_get_interface_addresses(int ifindex, bool v6, struct odhcpd_ipaddr **addrs)
344 struct ifaddrmsg ifa = {
345 .ifa_family = v6? AF_INET6: AF_INET,
349 .ifa_index = ifindex, };
350 struct nl_cb *cb = nl_cb_alloc(NL_CB_DEFAULT);
351 struct addr_info ctxt = {
353 .af = v6? AF_INET6: AF_INET,
364 msg = nlmsg_alloc_simple(RTM_GETADDR, NLM_F_REQUEST | NLM_F_DUMP);
371 nlmsg_append(msg, &ifa, sizeof(ifa), 0);
373 nl_cb_set(cb, NL_CB_VALID, NL_CB_CUSTOM, cb_valid_handler, &ctxt);
374 nl_cb_set(cb, NL_CB_FINISH, NL_CB_CUSTOM, cb_finish_handler, &ctxt);
375 nl_cb_err(cb, NL_CB_CUSTOM, cb_error_handler, &ctxt);
377 nl_send_auto_complete(rtnl_socket, msg);
378 while (ctxt.pending > 0)
379 nl_recvmsgs(rtnl_socket, cb);
386 time_t now = odhcpd_time();
387 struct odhcpd_ipaddr *addr = *addrs;
389 qsort(addr, ctxt.ret, sizeof(*addr), v6 ? prefix6_cmp : prefix_cmp);
391 for (ssize_t i = 0; i < ctxt.ret; ++i) {
392 if (addr[i].preferred < UINT32_MAX - now)
393 addr[i].preferred += now;
395 if (addr[i].valid < UINT32_MAX - now)
396 addr[i].valid += now;
405 static int odhcpd_get_linklocal_interface_address(int ifindex, struct in6_addr *lladdr)
408 struct sockaddr_in6 addr = {AF_INET6, 0, 0, ALL_IPV6_ROUTERS, ifindex};
409 socklen_t alen = sizeof(addr);
410 int sock = socket(AF_INET6, SOCK_RAW, IPPROTO_ICMPV6);
412 if (!connect(sock, (struct sockaddr*)&addr, sizeof(addr)) &&
413 !getsockname(sock, (struct sockaddr*)&addr, &alen)) {
414 *lladdr = addr.sin6_addr;
424 * DNS address selection criteria order :
425 * - use IPv6 address with valid lifetime if none is yet selected
426 * - use IPv6 address with a preferred lifetime if the already selected IPv6 address is deprecated
427 * - use an IPv6 ULA address if the already selected IPv6 address is not an ULA address
428 * - use the IPv6 address with the longest preferred lifetime
430 int odhcpd_get_interface_dns_addr(const struct interface *iface, struct in6_addr *addr)
432 time_t now = odhcpd_time();
435 for (size_t i = 0; i < iface->ia_addr_len; ++i) {
436 if (iface->ia_addr[i].valid <= (uint32_t)now)
444 if (iface->ia_addr[m].preferred >= (uint32_t)now &&
445 iface->ia_addr[i].preferred < (uint32_t)now)
448 if (IN6_IS_ADDR_ULA(&iface->ia_addr[i].addr.in6)) {
449 if (!IN6_IS_ADDR_ULA(&iface->ia_addr[m].addr.in6)) {
453 } else if (IN6_IS_ADDR_ULA(&iface->ia_addr[m].addr.in6))
456 if (iface->ia_addr[i].preferred > iface->ia_addr[m].preferred)
461 *addr = iface->ia_addr[m].addr.in6;
465 return odhcpd_get_linklocal_interface_address(iface->ifindex, addr);
468 int odhcpd_setup_route(const struct in6_addr *addr, const int prefixlen,
469 const struct interface *iface, const struct in6_addr *gw,
470 const uint32_t metric, const bool add)
474 .rtm_family = AF_INET6,
475 .rtm_dst_len = prefixlen,
477 .rtm_table = RT_TABLE_MAIN,
478 .rtm_protocol = (add ? RTPROT_STATIC : RTPROT_UNSPEC),
479 .rtm_scope = (add ? (gw ? RT_SCOPE_UNIVERSE : RT_SCOPE_LINK) : RT_SCOPE_NOWHERE),
480 .rtm_type = (add ? RTN_UNICAST : RTN_UNSPEC),
484 msg = nlmsg_alloc_simple(add ? RTM_NEWROUTE : RTM_DELROUTE,
485 add ? NLM_F_CREATE | NLM_F_REPLACE : 0);
489 nlmsg_append(msg, &rtm, sizeof(rtm), 0);
491 nla_put(msg, RTA_DST, sizeof(*addr), addr);
492 nla_put_u32(msg, RTA_OIF, iface->ifindex);
493 nla_put_u32(msg, RTA_PRIORITY, metric);
496 nla_put(msg, RTA_GATEWAY, sizeof(*gw), gw);
498 ret = nl_send_auto_complete(rtnl_socket, msg);
504 return nl_wait_for_ack(rtnl_socket);
507 int odhcpd_setup_proxy_neigh(const struct in6_addr *addr,
508 const struct interface *iface, const bool add)
512 .ndm_family = AF_INET6,
513 .ndm_flags = NTF_PROXY,
514 .ndm_ifindex = iface->ifindex,
516 int ret = 0, flags = NLM_F_REQUEST;
519 flags |= NLM_F_REPLACE | NLM_F_CREATE;
521 msg = nlmsg_alloc_simple(add ? RTM_NEWNEIGH : RTM_DELNEIGH, flags);
525 nlmsg_append(msg, &ndm, sizeof(ndm), 0);
527 nla_put(msg, NDA_DST, sizeof(*addr), addr);
529 ret = nl_send_auto_complete(rtnl_socket, msg);
535 return nl_wait_for_ack(rtnl_socket);
538 int odhcpd_setup_addr(struct odhcpd_ipaddr *addr,
539 const struct interface *iface, const bool v6,
543 struct ifaddrmsg ifa = {
544 .ifa_family = v6 ? AF_INET6 : AF_INET,
545 .ifa_prefixlen = addr->prefix,
548 .ifa_index = iface->ifindex, };
549 int ret = 0, flags = NLM_F_REQUEST;
552 flags |= NLM_F_REPLACE | NLM_F_CREATE;
554 msg = nlmsg_alloc_simple(add ? RTM_NEWADDR : RTM_DELADDR, 0);
558 nlmsg_append(msg, &ifa, sizeof(ifa), flags);
559 nla_put(msg, IFA_LOCAL, v6 ? 16 : 4, &addr->addr);
561 struct ifa_cacheinfo cinfo = { .ifa_prefered = 0xffffffffU,
562 .ifa_valid = 0xffffffffU,
565 time_t now = odhcpd_time();
567 if (addr->preferred) {
568 int64_t preferred = addr->preferred - now;
571 else if (preferred > UINT32_MAX)
572 preferred = UINT32_MAX;
574 cinfo.ifa_prefered = preferred;
578 int64_t valid = addr->valid - now;
583 else if (valid > UINT32_MAX)
586 cinfo.ifa_valid = valid;
589 nla_put(msg, IFA_CACHEINFO, sizeof(cinfo), &cinfo);
591 nla_put_u32(msg, IFA_FLAGS, IFA_F_NOPREFIXROUTE);
593 if (addr->broadcast.s_addr)
594 nla_put_u32(msg, IFA_BROADCAST, addr->broadcast.s_addr);
597 ret = nl_send_auto_complete(rtnl_socket, msg);
603 return nl_wait_for_ack(rtnl_socket);
606 struct interface* odhcpd_get_interface_by_index(int ifindex)
608 struct interface *iface;
609 list_for_each_entry(iface, &interfaces, head)
610 if (iface->ifindex == ifindex)
617 struct interface* odhcpd_get_interface_by_name(const char *name)
619 struct interface *iface;
620 list_for_each_entry(iface, &interfaces, head)
621 if (!strcmp(iface->ifname, name))
628 struct interface* odhcpd_get_master_interface(void)
630 struct interface *iface;
631 list_for_each_entry(iface, &interfaces, head)
639 // Convenience function to receive and do basic validation of packets
640 static void odhcpd_receive_packets(struct uloop_fd *u, _unused unsigned int events)
642 struct odhcpd_event *e = container_of(u, struct odhcpd_event, uloop);
644 uint8_t data_buf[8192], cmsg_buf[128];
646 struct sockaddr_in6 in6;
647 struct sockaddr_in in;
648 struct sockaddr_ll ll;
649 struct sockaddr_nl nl;
654 socklen_t ret_len = sizeof(ret);
655 getsockopt(u->fd, SOL_SOCKET, SO_ERROR, &ret, &ret_len);
658 e->handle_error(e, ret);
667 struct iovec iov = {data_buf, sizeof(data_buf)};
668 struct msghdr msg = {
669 .msg_name = (void *) &addr,
670 .msg_namelen = sizeof(addr),
673 .msg_control = cmsg_buf,
674 .msg_controllen = sizeof(cmsg_buf),
678 ssize_t len = recvmsg(u->fd, &msg, MSG_DONTWAIT);
687 // Extract destination interface
691 struct in6_pktinfo *pktinfo;
692 struct in_pktinfo *pkt4info;
693 for (struct cmsghdr *ch = CMSG_FIRSTHDR(&msg); ch != NULL; ch = CMSG_NXTHDR(&msg, ch)) {
694 if (ch->cmsg_level == IPPROTO_IPV6 &&
695 ch->cmsg_type == IPV6_PKTINFO) {
696 pktinfo = (struct in6_pktinfo*)CMSG_DATA(ch);
697 destiface = pktinfo->ipi6_ifindex;
698 dest = &pktinfo->ipi6_addr;
699 } else if (ch->cmsg_level == IPPROTO_IP &&
700 ch->cmsg_type == IP_PKTINFO) {
701 pkt4info = (struct in_pktinfo*)CMSG_DATA(ch);
702 destiface = pkt4info->ipi_ifindex;
703 dest = &pkt4info->ipi_addr;
704 } else if (ch->cmsg_level == IPPROTO_IPV6 &&
705 ch->cmsg_type == IPV6_HOPLIMIT) {
706 hlim = (int*)CMSG_DATA(ch);
710 // Check hoplimit if received
711 if (hlim && *hlim != 255)
714 // Detect interface for packet sockets
715 if (addr.ll.sll_family == AF_PACKET)
716 destiface = addr.ll.sll_ifindex;
718 struct interface *iface =
719 odhcpd_get_interface_by_index(destiface);
721 if (!iface && addr.nl.nl_family != AF_NETLINK)
724 char ipbuf[INET6_ADDRSTRLEN] = "kernel";
725 if (addr.ll.sll_family == AF_PACKET &&
726 len >= (ssize_t)sizeof(struct ip6_hdr))
727 inet_ntop(AF_INET6, &data_buf[8], ipbuf, sizeof(ipbuf));
728 else if (addr.in6.sin6_family == AF_INET6)
729 inet_ntop(AF_INET6, &addr.in6.sin6_addr, ipbuf, sizeof(ipbuf));
730 else if (addr.in.sin_family == AF_INET)
731 inet_ntop(AF_INET, &addr.in.sin_addr, ipbuf, sizeof(ipbuf));
733 syslog(LOG_DEBUG, "Received %li Bytes from %s%%%s", (long)len,
734 ipbuf, (iface) ? iface->ifname : "netlink");
736 e->handle_dgram(&addr, data_buf, len, iface, dest);
740 // Register events for the multiplexer
741 int odhcpd_register(struct odhcpd_event *event)
743 event->uloop.cb = odhcpd_receive_packets;
744 return uloop_fd_add(&event->uloop, ULOOP_READ |
745 ((event->handle_error) ? ULOOP_ERROR_CB : 0));
748 int odhcpd_deregister(struct odhcpd_event *event)
750 event->uloop.cb = NULL;
751 return uloop_fd_delete(&event->uloop);
754 void odhcpd_process(struct odhcpd_event *event)
756 odhcpd_receive_packets(&event->uloop, 0);
759 int odhcpd_urandom(void *data, size_t len)
761 return read(urandom_fd, data, len);
765 time_t odhcpd_time(void)
768 syscall(SYS_clock_gettime, CLOCK_MONOTONIC, &ts);
773 static const char hexdigits[] = "0123456789abcdef";
774 static const int8_t hexvals[] = {
775 -1, -1, -1, -1, -1, -1, -1, -1, -1, -2, -2, -1, -1, -2, -1, -1,
776 -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1,
777 -2, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1,
778 0, 1, 2, 3, 4, 5, 6, 7, 8, 9, -1, -1, -1, -1, -1, -1,
779 -1, 10, 11, 12, 13, 14, 15, -1, -1, -1, -1, -1, -1, -1, -1, -1,
780 -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1,
781 -1, 10, 11, 12, 13, 14, 15, -1, -1, -1, -1, -1, -1, -1, -1, -1,
782 -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1,
785 ssize_t odhcpd_unhexlify(uint8_t *dst, size_t len, const char *src)
788 for (c = 0; c < len && src[0] && src[1]; ++c) {
789 int8_t x = (int8_t)*src++;
790 int8_t y = (int8_t)*src++;
791 if (x < 0 || (x = hexvals[x]) < 0
792 || y < 0 || (y = hexvals[y]) < 0)
795 while (((int8_t)*src) < 0 ||
796 (*src && hexvals[(uint8_t)*src] < 0))
804 void odhcpd_hexlify(char *dst, const uint8_t *src, size_t len)
806 for (size_t i = 0; i < len; ++i) {
807 *dst++ = hexdigits[src[i] >> 4];
808 *dst++ = hexdigits[src[i] & 0x0f];
814 int odhcpd_bmemcmp(const void *av, const void *bv, size_t bits)
816 const uint8_t *a = av, *b = bv;
817 size_t bytes = bits / 8;
820 int res = memcmp(a, b, bytes);
821 if (res == 0 && bits > 0)
822 res = (a[bytes] >> (8 - bits)) - (b[bytes] >> (8 - bits));
828 void odhcpd_bmemcpy(void *av, const void *bv, size_t bits)
831 const uint8_t *b = bv;
833 size_t bytes = bits / 8;
838 uint8_t mask = (1 << (8 - bits)) - 1;
839 a[bytes] = (a[bytes] & mask) | ((~mask) & b[bytes]);
844 int odhcpd_netmask2bitlen(bool inet6, void *mask)
851 for (bits = 0, v6 = mask;
852 bits < 128 && (v6->s6_addr[bits / 8] << (bits % 8)) & 128;
855 for (bits = 0, v4 = mask;
856 bits < 32 && (ntohl(v4->s_addr) << bits) & 0x80000000;
862 bool odhcpd_bitlen2netmask(bool inet6, unsigned int bits, void *mask)
875 for (unsigned int i = 0; i < sizeof(v6->s6_addr); i++)
877 b = (bits > 8) ? 8 : bits;
878 v6->s6_addr[i] = (uint8_t)(0xFF << (8 - b));
888 v4->s_addr = bits ? htonl(~((1 << (32 - bits)) - 1)) : 0;