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;
54 openlog("odhcpd", LOG_PERROR | LOG_PID, LOG_DAEMON);
58 syslog(LOG_ERR, "Must be run as root!");
62 ioctl_sock = socket(AF_INET, SOCK_DGRAM | SOCK_CLOEXEC, 0);
64 if ((rtnl_socket = odhcpd_open_rtnl()) < 0) {
65 syslog(LOG_ERR, "Unable to open socket: %s", strerror(errno));
69 if ((urandom_fd = open("/dev/urandom", O_RDONLY | O_CLOEXEC)) < 0)
72 signal(SIGUSR1, SIG_IGN);
93 int odhcpd_open_rtnl(void)
95 int sock = socket(AF_NETLINK, SOCK_RAW | SOCK_CLOEXEC, NETLINK_ROUTE);
97 // Connect to the kernel netlink interface
98 struct sockaddr_nl nl = {.nl_family = AF_NETLINK};
99 if (connect(sock, (struct sockaddr*)&nl, sizeof(nl))) {
100 syslog(LOG_ERR, "Failed to connect to kernel rtnetlink: %s",
109 // Read IPv6 MTU for interface
110 int odhcpd_get_interface_mtu(const char *ifname)
113 const char *sysctl_pattern = "/proc/sys/net/ipv6/conf/%s/mtu";
114 snprintf(buf, sizeof(buf), sysctl_pattern, ifname);
116 int fd = open(buf, O_RDONLY);
117 ssize_t len = read(fd, buf, sizeof(buf) - 1);
130 // Read IPv6 MAC for interface
131 int odhcpd_get_mac(const struct interface *iface, uint8_t mac[6])
134 memset(&ifr, 0, sizeof(ifr));
135 strncpy(ifr.ifr_name, iface->ifname, sizeof(ifr.ifr_name));
136 if (ioctl(ioctl_sock, SIOCGIFHWADDR, &ifr) < 0)
138 memcpy(mac, ifr.ifr_hwaddr.sa_data, 6);
143 // Forwards a packet on a specific interface
144 ssize_t odhcpd_send(int socket, struct sockaddr_in6 *dest,
145 struct iovec *iov, size_t iov_len,
146 const struct interface *iface)
149 uint8_t cmsg_buf[CMSG_SPACE(sizeof(struct in6_pktinfo))] = {0};
150 struct msghdr msg = {(void*)dest, sizeof(*dest), iov, iov_len,
151 cmsg_buf, sizeof(cmsg_buf), 0};
153 // Set control data (define destination interface)
154 struct cmsghdr *chdr = CMSG_FIRSTHDR(&msg);
155 chdr->cmsg_level = IPPROTO_IPV6;
156 chdr->cmsg_type = IPV6_PKTINFO;
157 chdr->cmsg_len = CMSG_LEN(sizeof(struct in6_pktinfo));
158 struct in6_pktinfo *pktinfo = (struct in6_pktinfo*)CMSG_DATA(chdr);
159 pktinfo->ipi6_ifindex = iface->ifindex;
161 // Also set scope ID if link-local
162 if (IN6_IS_ADDR_LINKLOCAL(&dest->sin6_addr)
163 || IN6_IS_ADDR_MC_LINKLOCAL(&dest->sin6_addr))
164 dest->sin6_scope_id = iface->ifindex;
166 // IPV6_PKTINFO doesn't really work for IPv6-raw sockets (bug?)
167 if (dest->sin6_port == 0) {
168 msg.msg_control = NULL;
169 msg.msg_controllen = 0;
172 char ipbuf[INET6_ADDRSTRLEN];
173 inet_ntop(AF_INET6, &dest->sin6_addr, ipbuf, sizeof(ipbuf));
175 ssize_t sent = sendmsg(socket, &msg, MSG_DONTWAIT);
177 syslog(LOG_WARNING, "Failed to send to %s%%%s (%s)",
178 ipbuf, iface->ifname, strerror(errno));
180 syslog(LOG_NOTICE, "Sent %li bytes to %s%%%s",
181 (long)sent, ipbuf, iface->ifname);
186 // Detect an IPV6-address currently assigned to the given interface
187 ssize_t odhcpd_get_interface_addresses(int ifindex,
188 struct odhcpd_ipaddr *addrs, size_t cnt)
192 struct ifaddrmsg ifa;
193 } req = {{sizeof(req), RTM_GETADDR, NLM_F_REQUEST | NLM_F_DUMP,
194 ++rtnl_seq, 0}, {AF_INET6, 0, 0, 0, ifindex}};
195 if (send(rtnl_socket, &req, sizeof(req), 0) < (ssize_t)sizeof(req))
199 ssize_t len = 0, ret = 0;
201 for (struct nlmsghdr *nhm = NULL; ; nhm = NLMSG_NEXT(nhm, len)) {
202 while (len < 0 || !NLMSG_OK(nhm, (size_t)len)) {
203 len = recv(rtnl_socket, buf, sizeof(buf), 0);
204 nhm = (struct nlmsghdr*)buf;
205 if (len < 0 || !NLMSG_OK(nhm, (size_t)len)) {
213 if (nhm->nlmsg_type != RTM_NEWADDR)
216 // Skip address but keep clearing socket buffer
217 if (ret >= (ssize_t)cnt)
220 struct ifaddrmsg *ifa = NLMSG_DATA(nhm);
221 if (ifa->ifa_scope != RT_SCOPE_UNIVERSE ||
222 ifa->ifa_index != (unsigned)ifindex)
225 struct rtattr *rta = (struct rtattr*)&ifa[1];
226 size_t alen = NLMSG_PAYLOAD(nhm, sizeof(*ifa));
227 memset(&addrs[ret], 0, sizeof(addrs[ret]));
228 addrs[ret].prefix = ifa->ifa_prefixlen;
230 while (RTA_OK(rta, alen)) {
231 if (rta->rta_type == IFA_ADDRESS) {
232 memcpy(&addrs[ret].addr, RTA_DATA(rta),
233 sizeof(struct in6_addr));
234 } else if (rta->rta_type == IFA_CACHEINFO) {
235 struct ifa_cacheinfo *ifc = RTA_DATA(rta);
236 addrs[ret].preferred = ifc->ifa_prefered;
237 addrs[ret].valid = ifc->ifa_valid;
240 rta = RTA_NEXT(rta, alen);
243 if (ifa->ifa_flags & IFA_F_DEPRECATED)
244 addrs[ret].preferred = 0;
253 struct interface* odhcpd_get_interface_by_index(int ifindex)
255 struct interface *iface;
256 list_for_each_entry(iface, &interfaces, head)
257 if (iface->ifindex == ifindex)
264 struct interface* odhcpd_get_interface_by_name(const char *name)
266 struct interface *iface;
267 list_for_each_entry(iface, &interfaces, head)
268 if (!strcmp(iface->ifname, name))
275 struct interface* odhcpd_get_master_interface(void)
277 struct interface *iface;
278 list_for_each_entry(iface, &interfaces, head)
286 // Convenience function to receive and do basic validation of packets
287 static void odhcpd_receive_packets(struct uloop_fd *u, _unused unsigned int events)
289 struct odhcpd_event *e = container_of(u, struct odhcpd_event, uloop);
291 uint8_t data_buf[RELAYD_BUFFER_SIZE], cmsg_buf[128];
293 struct sockaddr_in6 in6;
294 struct sockaddr_in in;
295 struct sockaddr_ll ll;
296 struct sockaddr_nl nl;
300 struct iovec iov = {data_buf, sizeof(data_buf)};
301 struct msghdr msg = {&addr, sizeof(addr), &iov, 1,
302 cmsg_buf, sizeof(cmsg_buf), 0};
304 ssize_t len = recvmsg(u->fd, &msg, MSG_DONTWAIT);
313 // Extract destination interface
316 struct in6_pktinfo *pktinfo;
317 struct in_pktinfo *pkt4info;
318 for (struct cmsghdr *ch = CMSG_FIRSTHDR(&msg); ch != NULL &&
319 destiface == 0; ch = CMSG_NXTHDR(&msg, ch)) {
320 if (ch->cmsg_level == IPPROTO_IPV6 &&
321 ch->cmsg_type == IPV6_PKTINFO) {
322 pktinfo = (struct in6_pktinfo*)CMSG_DATA(ch);
323 destiface = pktinfo->ipi6_ifindex;
324 } else if (ch->cmsg_level == IPPROTO_IP &&
325 ch->cmsg_type == IP_PKTINFO) {
326 pkt4info = (struct in_pktinfo*)CMSG_DATA(ch);
327 destiface = pkt4info->ipi_ifindex;
328 } else if (ch->cmsg_level == IPPROTO_IPV6 &&
329 ch->cmsg_type == IPV6_HOPLIMIT) {
330 hlim = (int*)CMSG_DATA(ch);
334 // Check hoplimit if received
335 if (hlim && *hlim != 255)
338 // Detect interface for packet sockets
339 if (addr.ll.sll_family == AF_PACKET)
340 destiface = addr.ll.sll_ifindex;
342 struct interface *iface =
343 odhcpd_get_interface_by_index(destiface);
345 if (!iface && addr.nl.nl_family != AF_NETLINK)
348 char ipbuf[INET6_ADDRSTRLEN] = "kernel";
349 if (addr.ll.sll_family == AF_PACKET &&
350 len >= (ssize_t)sizeof(struct ip6_hdr))
351 inet_ntop(AF_INET6, &data_buf[8], ipbuf, sizeof(ipbuf));
352 else if (addr.in6.sin6_family == AF_INET6)
353 inet_ntop(AF_INET6, &addr.in6.sin6_addr, ipbuf, sizeof(ipbuf));
354 else if (addr.in.sin_family == AF_INET)
355 inet_ntop(AF_INET, &addr.in.sin_addr, ipbuf, sizeof(ipbuf));
357 syslog(LOG_NOTICE, "--");
358 syslog(LOG_NOTICE, "Received %li Bytes from %s%%%s", (long)len,
359 ipbuf, (iface) ? iface->ifname : "netlink");
361 e->handle_dgram(&addr, data_buf, len, iface);
365 // Register events for the multiplexer
366 int odhcpd_register(struct odhcpd_event *event)
368 event->uloop.cb = odhcpd_receive_packets;
369 return uloop_fd_add(&event->uloop, ULOOP_READ);
372 void odhcpd_urandom(void *data, size_t len)
374 read(urandom_fd, data, len);
378 time_t odhcpd_time(void)
381 syscall(SYS_clock_gettime, CLOCK_MONOTONIC, &ts);
386 static const char hexdigits[] = "0123456789abcdef";
387 static const int8_t hexvals[] = {
388 -1, -1, -1, -1, -1, -1, -1, -1, -1, -2, -2, -1, -1, -2, -1, -1,
389 -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1,
390 -2, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1,
391 0, 1, 2, 3, 4, 5, 6, 7, 8, 9, -1, -1, -1, -1, -1, -1,
392 -1, 10, 11, 12, 13, 14, 15, -1, -1, -1, -1, -1, -1, -1, -1, -1,
393 -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1,
394 -1, 10, 11, 12, 13, 14, 15, -1, -1, -1, -1, -1, -1, -1, -1, -1,
395 -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1,
398 ssize_t odhcpd_unhexlify(uint8_t *dst, size_t len, const char *src)
401 for (c = 0; c < len && src[0] && src[1]; ++c) {
402 int8_t x = (int8_t)*src++;
403 int8_t y = (int8_t)*src++;
404 if (x < 0 || (x = hexvals[x]) < 0
405 || y < 0 || (y = hexvals[y]) < 0)
408 while (((int8_t)*src) < 0 ||
409 (*src && hexvals[(uint8_t)*src] < 0))
417 void odhcpd_hexlify(char *dst, const uint8_t *src, size_t len)
419 for (size_t i = 0; i < len; ++i) {
420 *dst++ = hexdigits[src[i] >> 4];
421 *dst++ = hexdigits[src[i] & 0x0f];