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.
28 #include <arpa/inet.h>
30 #include <netinet/ip6.h>
31 #include <netpacket/packet.h>
32 #include <linux/rtnetlink.h>
34 #include <sys/socket.h>
35 #include <sys/ioctl.h>
36 #include <sys/epoll.h>
37 #include <sys/types.h>
39 #include <sys/syscall.h>
41 #include <libubox/uloop.h>
46 static int ioctl_sock;
47 static int rtnl_socket = -1;
48 static int rtnl_seq = 0;
49 static int urandom_fd = -1;
52 static void sighandler(_unused int signal)
60 openlog("odhcpd", LOG_PERROR | LOG_PID, LOG_DAEMON);
61 setlogmask(LOG_UPTO(LOG_WARNING));
65 syslog(LOG_ERR, "Must be run as root!");
69 ioctl_sock = socket(AF_INET, SOCK_DGRAM | SOCK_CLOEXEC, 0);
71 if ((rtnl_socket = odhcpd_open_rtnl()) < 0) {
72 syslog(LOG_ERR, "Unable to open socket: %s", strerror(errno));
76 if ((urandom_fd = open("/dev/urandom", O_RDONLY | O_CLOEXEC)) < 0)
79 signal(SIGUSR1, SIG_IGN);
80 signal(SIGINT, sighandler);
81 signal(SIGTERM, sighandler);
99 int odhcpd_open_rtnl(void)
101 int sock = socket(AF_NETLINK, SOCK_RAW | SOCK_CLOEXEC, NETLINK_ROUTE);
103 // Connect to the kernel netlink interface
104 struct sockaddr_nl nl = {.nl_family = AF_NETLINK};
105 if (connect(sock, (struct sockaddr*)&nl, sizeof(nl))) {
106 syslog(LOG_ERR, "Failed to connect to kernel rtnetlink: %s",
115 // Read IPv6 MTU for interface
116 int odhcpd_get_interface_mtu(const char *ifname)
119 const char *sysctl_pattern = "/proc/sys/net/ipv6/conf/%s/mtu";
120 snprintf(buf, sizeof(buf), sysctl_pattern, ifname);
122 int fd = open(buf, O_RDONLY);
123 ssize_t len = read(fd, buf, sizeof(buf) - 1);
136 // Read IPv6 MAC for interface
137 int odhcpd_get_mac(const struct interface *iface, uint8_t mac[6])
140 memset(&ifr, 0, sizeof(ifr));
141 strncpy(ifr.ifr_name, iface->ifname, sizeof(ifr.ifr_name));
142 if (ioctl(ioctl_sock, SIOCGIFHWADDR, &ifr) < 0)
144 memcpy(mac, ifr.ifr_hwaddr.sa_data, 6);
149 // Forwards a packet on a specific interface
150 ssize_t odhcpd_send(int socket, struct sockaddr_in6 *dest,
151 struct iovec *iov, size_t iov_len,
152 const struct interface *iface)
155 uint8_t cmsg_buf[CMSG_SPACE(sizeof(struct in6_pktinfo))] = {0};
156 struct msghdr msg = {
157 .msg_name = (void *) dest,
158 .msg_namelen = sizeof(*dest),
160 .msg_iovlen = iov_len,
161 .msg_control = cmsg_buf,
162 .msg_controllen = sizeof(cmsg_buf),
166 // Set control data (define destination interface)
167 struct cmsghdr *chdr = CMSG_FIRSTHDR(&msg);
168 chdr->cmsg_level = IPPROTO_IPV6;
169 chdr->cmsg_type = IPV6_PKTINFO;
170 chdr->cmsg_len = CMSG_LEN(sizeof(struct in6_pktinfo));
171 struct in6_pktinfo *pktinfo = (struct in6_pktinfo*)CMSG_DATA(chdr);
172 pktinfo->ipi6_ifindex = iface->ifindex;
174 // Also set scope ID if link-local
175 if (IN6_IS_ADDR_LINKLOCAL(&dest->sin6_addr)
176 || IN6_IS_ADDR_MC_LINKLOCAL(&dest->sin6_addr))
177 dest->sin6_scope_id = iface->ifindex;
179 // IPV6_PKTINFO doesn't really work for IPv6-raw sockets (bug?)
180 if (dest->sin6_port == 0) {
181 msg.msg_control = NULL;
182 msg.msg_controllen = 0;
185 char ipbuf[INET6_ADDRSTRLEN];
186 inet_ntop(AF_INET6, &dest->sin6_addr, ipbuf, sizeof(ipbuf));
188 ssize_t sent = sendmsg(socket, &msg, MSG_DONTWAIT);
190 syslog(LOG_NOTICE, "Failed to send to %s%%%s (%s)",
191 ipbuf, iface->ifname, strerror(errno));
193 syslog(LOG_DEBUG, "Sent %li bytes to %s%%%s",
194 (long)sent, ipbuf, iface->ifname);
199 // Detect an IPV6-address currently assigned to the given interface
200 ssize_t odhcpd_get_interface_addresses(int ifindex,
201 struct odhcpd_ipaddr *addrs, size_t cnt)
205 struct ifaddrmsg ifa;
206 } req = {{sizeof(req), RTM_GETADDR, NLM_F_REQUEST | NLM_F_DUMP,
207 ++rtnl_seq, 0}, {AF_INET6, 0, 0, 0, ifindex}};
208 if (send(rtnl_socket, &req, sizeof(req), 0) < (ssize_t)sizeof(req))
212 ssize_t len = 0, ret = 0;
214 for (struct nlmsghdr *nhm = NULL; ; nhm = NLMSG_NEXT(nhm, len)) {
215 while (len < 0 || !NLMSG_OK(nhm, (size_t)len)) {
216 len = recv(rtnl_socket, buf, sizeof(buf), 0);
217 nhm = (struct nlmsghdr*)buf;
218 if (len < 0 || !NLMSG_OK(nhm, (size_t)len)) {
226 if (nhm->nlmsg_type != RTM_NEWADDR)
229 // Skip address but keep clearing socket buffer
230 if (ret >= (ssize_t)cnt)
233 struct ifaddrmsg *ifa = NLMSG_DATA(nhm);
234 if (ifa->ifa_scope != RT_SCOPE_UNIVERSE ||
235 (ifindex && ifa->ifa_index != (unsigned)ifindex))
238 struct rtattr *rta = (struct rtattr*)&ifa[1];
239 size_t alen = NLMSG_PAYLOAD(nhm, sizeof(*ifa));
240 memset(&addrs[ret], 0, sizeof(addrs[ret]));
241 addrs[ret].prefix = ifa->ifa_prefixlen;
243 while (RTA_OK(rta, alen)) {
244 if (rta->rta_type == IFA_ADDRESS) {
245 memcpy(&addrs[ret].addr, RTA_DATA(rta),
246 sizeof(struct in6_addr));
247 } else if (rta->rta_type == IFA_CACHEINFO) {
248 struct ifa_cacheinfo *ifc = RTA_DATA(rta);
249 addrs[ret].preferred = ifc->ifa_prefered;
250 addrs[ret].valid = ifc->ifa_valid;
253 rta = RTA_NEXT(rta, alen);
256 if (ifa->ifa_flags & IFA_F_DEPRECATED)
257 addrs[ret].preferred = 0;
265 int odhcpd_get_preferred_interface_address(int ifindex, struct in6_addr *addr)
267 struct odhcpd_ipaddr ipaddrs[8];
268 ssize_t ip_cnt = odhcpd_get_interface_addresses(ifindex, ipaddrs, ARRAY_SIZE(ipaddrs));
269 uint32_t preferred = 0;
272 for (ssize_t i = 0; i < ip_cnt; i++) {
273 struct odhcpd_ipaddr *ipaddr = &ipaddrs[i];
275 if (ipaddr->preferred > preferred || !preferred) {
276 preferred = ipaddr->preferred;
277 *addr = ipaddr->addr;
285 struct interface* odhcpd_get_interface_by_index(int ifindex)
287 struct interface *iface;
288 list_for_each_entry(iface, &interfaces, head)
289 if (iface->ifindex == ifindex)
296 struct interface* odhcpd_get_interface_by_name(const char *name)
298 struct interface *iface;
299 list_for_each_entry(iface, &interfaces, head)
300 if (!strcmp(iface->ifname, name))
307 struct interface* odhcpd_get_master_interface(void)
309 struct interface *iface;
310 list_for_each_entry(iface, &interfaces, head)
318 // Convenience function to receive and do basic validation of packets
319 static void odhcpd_receive_packets(struct uloop_fd *u, _unused unsigned int events)
321 struct odhcpd_event *e = container_of(u, struct odhcpd_event, uloop);
323 uint8_t data_buf[RELAYD_BUFFER_SIZE], cmsg_buf[128];
325 struct sockaddr_in6 in6;
326 struct sockaddr_in in;
327 struct sockaddr_ll ll;
328 struct sockaddr_nl nl;
332 struct iovec iov = {data_buf, sizeof(data_buf)};
333 struct msghdr msg = {
334 .msg_name = (void *) &addr,
335 .msg_namelen = sizeof(addr),
338 .msg_control = cmsg_buf,
339 .msg_controllen = sizeof(cmsg_buf),
343 ssize_t len = recvmsg(u->fd, &msg, MSG_DONTWAIT);
352 // Extract destination interface
356 struct in6_pktinfo *pktinfo;
357 struct in_pktinfo *pkt4info;
358 for (struct cmsghdr *ch = CMSG_FIRSTHDR(&msg); ch != NULL; ch = CMSG_NXTHDR(&msg, ch)) {
359 if (ch->cmsg_level == IPPROTO_IPV6 &&
360 ch->cmsg_type == IPV6_PKTINFO) {
361 pktinfo = (struct in6_pktinfo*)CMSG_DATA(ch);
362 destiface = pktinfo->ipi6_ifindex;
363 dest = &pktinfo->ipi6_addr;
364 } else if (ch->cmsg_level == IPPROTO_IP &&
365 ch->cmsg_type == IP_PKTINFO) {
366 pkt4info = (struct in_pktinfo*)CMSG_DATA(ch);
367 destiface = pkt4info->ipi_ifindex;
368 dest = &pkt4info->ipi_addr;
369 } else if (ch->cmsg_level == IPPROTO_IPV6 &&
370 ch->cmsg_type == IPV6_HOPLIMIT) {
371 hlim = (int*)CMSG_DATA(ch);
375 // Check hoplimit if received
376 if (hlim && *hlim != 255)
379 // Detect interface for packet sockets
380 if (addr.ll.sll_family == AF_PACKET)
381 destiface = addr.ll.sll_ifindex;
383 struct interface *iface =
384 odhcpd_get_interface_by_index(destiface);
386 if (!iface && addr.nl.nl_family != AF_NETLINK)
389 char ipbuf[INET6_ADDRSTRLEN] = "kernel";
390 if (addr.ll.sll_family == AF_PACKET &&
391 len >= (ssize_t)sizeof(struct ip6_hdr))
392 inet_ntop(AF_INET6, &data_buf[8], ipbuf, sizeof(ipbuf));
393 else if (addr.in6.sin6_family == AF_INET6)
394 inet_ntop(AF_INET6, &addr.in6.sin6_addr, ipbuf, sizeof(ipbuf));
395 else if (addr.in.sin_family == AF_INET)
396 inet_ntop(AF_INET, &addr.in.sin_addr, ipbuf, sizeof(ipbuf));
398 syslog(LOG_DEBUG, "--");
399 syslog(LOG_DEBUG, "Received %li Bytes from %s%%%s", (long)len,
400 ipbuf, (iface) ? iface->ifname : "netlink");
402 e->handle_dgram(&addr, data_buf, len, iface, dest);
406 // Register events for the multiplexer
407 int odhcpd_register(struct odhcpd_event *event)
409 event->uloop.cb = odhcpd_receive_packets;
410 return uloop_fd_add(&event->uloop, ULOOP_READ);
413 void odhcpd_process(struct odhcpd_event *event)
415 odhcpd_receive_packets(&event->uloop, 0);
418 int odhcpd_urandom(void *data, size_t len)
420 return read(urandom_fd, data, len);
424 time_t odhcpd_time(void)
427 syscall(SYS_clock_gettime, CLOCK_MONOTONIC, &ts);
432 static const char hexdigits[] = "0123456789abcdef";
433 static const int8_t hexvals[] = {
434 -1, -1, -1, -1, -1, -1, -1, -1, -1, -2, -2, -1, -1, -2, -1, -1,
435 -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1,
436 -2, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1,
437 0, 1, 2, 3, 4, 5, 6, 7, 8, 9, -1, -1, -1, -1, -1, -1,
438 -1, 10, 11, 12, 13, 14, 15, -1, -1, -1, -1, -1, -1, -1, -1, -1,
439 -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1,
440 -1, 10, 11, 12, 13, 14, 15, -1, -1, -1, -1, -1, -1, -1, -1, -1,
441 -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1,
444 ssize_t odhcpd_unhexlify(uint8_t *dst, size_t len, const char *src)
447 for (c = 0; c < len && src[0] && src[1]; ++c) {
448 int8_t x = (int8_t)*src++;
449 int8_t y = (int8_t)*src++;
450 if (x < 0 || (x = hexvals[x]) < 0
451 || y < 0 || (y = hexvals[y]) < 0)
454 while (((int8_t)*src) < 0 ||
455 (*src && hexvals[(uint8_t)*src] < 0))
463 void odhcpd_hexlify(char *dst, const uint8_t *src, size_t len)
465 for (size_t i = 0; i < len; ++i) {
466 *dst++ = hexdigits[src[i] >> 4];
467 *dst++ = hexdigits[src[i] & 0x0f];
473 int odhcpd_bmemcmp(const void *av, const void *bv, size_t bits)
475 const uint8_t *a = av, *b = bv;
476 size_t bytes = bits / 8;
479 int res = memcmp(a, b, bytes);
480 if (res == 0 && bits > 0)
481 res = (a[bytes] >> (8 - bits)) - (b[bytes] >> (8 - bits));
487 void odhcpd_bmemcpy(void *av, const void *bv, size_t bits)
490 const uint8_t *b = bv;
492 size_t bytes = bits / 8;
497 uint8_t mask = (1 << (8 - bits)) - 1;
498 a[bytes] = (a[bytes] & mask) | ((~mask) & b[bytes]);