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);
90 int odhcpd_open_rtnl(void)
92 int sock = socket(AF_NETLINK, SOCK_RAW | SOCK_CLOEXEC, NETLINK_ROUTE);
94 // Connect to the kernel netlink interface
95 struct sockaddr_nl nl = {.nl_family = AF_NETLINK};
96 if (connect(sock, (struct sockaddr*)&nl, sizeof(nl))) {
97 syslog(LOG_ERR, "Failed to connect to kernel rtnetlink: %s",
106 // Read IPv6 MTU for interface
107 int odhcpd_get_interface_mtu(const char *ifname)
110 const char *sysctl_pattern = "/proc/sys/net/ipv6/conf/%s/mtu";
111 snprintf(buf, sizeof(buf), sysctl_pattern, ifname);
113 int fd = open(buf, O_RDONLY);
114 ssize_t len = read(fd, buf, sizeof(buf) - 1);
127 // Read IPv6 MAC for interface
128 int odhcpd_get_mac(const struct interface *iface, uint8_t mac[6])
131 memset(&ifr, 0, sizeof(ifr));
132 strncpy(ifr.ifr_name, iface->ifname, sizeof(ifr.ifr_name));
133 if (ioctl(ioctl_sock, SIOCGIFHWADDR, &ifr) < 0)
135 memcpy(mac, ifr.ifr_hwaddr.sa_data, 6);
140 // Forwards a packet on a specific interface
141 ssize_t odhcpd_send(int socket, struct sockaddr_in6 *dest,
142 struct iovec *iov, size_t iov_len,
143 const struct interface *iface)
146 uint8_t cmsg_buf[CMSG_SPACE(sizeof(struct in6_pktinfo))] = {0};
147 struct msghdr msg = {(void*)dest, sizeof(*dest), iov, iov_len,
148 cmsg_buf, sizeof(cmsg_buf), 0};
150 // Set control data (define destination interface)
151 struct cmsghdr *chdr = CMSG_FIRSTHDR(&msg);
152 chdr->cmsg_level = IPPROTO_IPV6;
153 chdr->cmsg_type = IPV6_PKTINFO;
154 chdr->cmsg_len = CMSG_LEN(sizeof(struct in6_pktinfo));
155 struct in6_pktinfo *pktinfo = (struct in6_pktinfo*)CMSG_DATA(chdr);
156 pktinfo->ipi6_ifindex = iface->ifindex;
158 // Also set scope ID if link-local
159 if (IN6_IS_ADDR_LINKLOCAL(&dest->sin6_addr)
160 || IN6_IS_ADDR_MC_LINKLOCAL(&dest->sin6_addr))
161 dest->sin6_scope_id = iface->ifindex;
163 // IPV6_PKTINFO doesn't really work for IPv6-raw sockets (bug?)
164 if (dest->sin6_port == 0) {
165 msg.msg_control = NULL;
166 msg.msg_controllen = 0;
169 char ipbuf[INET6_ADDRSTRLEN];
170 inet_ntop(AF_INET6, &dest->sin6_addr, ipbuf, sizeof(ipbuf));
172 ssize_t sent = sendmsg(socket, &msg, MSG_DONTWAIT);
174 syslog(LOG_WARNING, "Failed to send to %s%%%s (%s)",
175 ipbuf, iface->ifname, strerror(errno));
177 syslog(LOG_NOTICE, "Sent %li bytes to %s%%%s",
178 (long)sent, ipbuf, iface->ifname);
183 // Detect an IPV6-address currently assigned to the given interface
184 ssize_t odhcpd_get_interface_addresses(int ifindex,
185 struct odhcpd_ipaddr *addrs, size_t cnt)
189 struct ifaddrmsg ifa;
190 } req = {{sizeof(req), RTM_GETADDR, NLM_F_REQUEST | NLM_F_DUMP,
191 ++rtnl_seq, 0}, {AF_INET6, 0, 0, 0, ifindex}};
192 if (send(rtnl_socket, &req, sizeof(req), 0) < (ssize_t)sizeof(req))
196 ssize_t len = 0, ret = 0;
198 for (struct nlmsghdr *nhm = NULL; ; nhm = NLMSG_NEXT(nhm, len)) {
199 while (len < 0 || !NLMSG_OK(nhm, (size_t)len)) {
200 len = recv(rtnl_socket, buf, sizeof(buf), 0);
201 nhm = (struct nlmsghdr*)buf;
202 if (len < 0 || !NLMSG_OK(nhm, (size_t)len)) {
210 if (nhm->nlmsg_type != RTM_NEWADDR)
213 // Skip address but keep clearing socket buffer
214 if (ret >= (ssize_t)cnt)
217 struct ifaddrmsg *ifa = NLMSG_DATA(nhm);
218 if (ifa->ifa_scope != RT_SCOPE_UNIVERSE ||
219 ifa->ifa_index != (unsigned)ifindex)
222 struct rtattr *rta = (struct rtattr*)&ifa[1];
223 size_t alen = NLMSG_PAYLOAD(nhm, sizeof(*ifa));
224 memset(&addrs[ret], 0, sizeof(addrs[ret]));
225 addrs[ret].prefix = ifa->ifa_prefixlen;
227 while (RTA_OK(rta, alen)) {
228 if (rta->rta_type == IFA_ADDRESS) {
229 memcpy(&addrs[ret].addr, RTA_DATA(rta),
230 sizeof(struct in6_addr));
231 } else if (rta->rta_type == IFA_CACHEINFO) {
232 struct ifa_cacheinfo *ifc = RTA_DATA(rta);
233 addrs[ret].preferred = ifc->ifa_prefered;
234 addrs[ret].valid = ifc->ifa_valid;
237 rta = RTA_NEXT(rta, alen);
240 if (ifa->ifa_flags & IFA_F_DEPRECATED)
241 addrs[ret].preferred = 0;
250 struct interface* odhcpd_get_interface_by_index(int ifindex)
252 struct interface *iface;
253 list_for_each_entry(iface, &interfaces, head)
254 if (iface->ifindex == ifindex)
261 struct interface* odhcpd_get_interface_by_name(const char *name)
263 struct interface *iface;
264 list_for_each_entry(iface, &interfaces, head)
265 if (!strcmp(iface->ifname, name))
272 struct interface* odhcpd_get_master_interface(void)
274 struct interface *iface;
275 list_for_each_entry(iface, &interfaces, head)
283 // Convenience function to receive and do basic validation of packets
284 static void odhcpd_receive_packets(struct uloop_fd *u, _unused unsigned int events)
286 struct odhcpd_event *e = container_of(u, struct odhcpd_event, uloop);
288 uint8_t data_buf[RELAYD_BUFFER_SIZE], cmsg_buf[128];
290 struct sockaddr_in6 in6;
291 struct sockaddr_in in;
292 struct sockaddr_ll ll;
293 struct sockaddr_nl nl;
297 struct iovec iov = {data_buf, sizeof(data_buf)};
298 struct msghdr msg = {&addr, sizeof(addr), &iov, 1,
299 cmsg_buf, sizeof(cmsg_buf), 0};
301 ssize_t len = recvmsg(u->fd, &msg, MSG_DONTWAIT);
310 // Extract destination interface
313 struct in6_pktinfo *pktinfo;
314 struct in_pktinfo *pkt4info;
315 for (struct cmsghdr *ch = CMSG_FIRSTHDR(&msg); ch != NULL &&
316 destiface == 0; ch = CMSG_NXTHDR(&msg, ch)) {
317 if (ch->cmsg_level == IPPROTO_IPV6 &&
318 ch->cmsg_type == IPV6_PKTINFO) {
319 pktinfo = (struct in6_pktinfo*)CMSG_DATA(ch);
320 destiface = pktinfo->ipi6_ifindex;
321 } else if (ch->cmsg_level == IPPROTO_IP &&
322 ch->cmsg_type == IP_PKTINFO) {
323 pkt4info = (struct in_pktinfo*)CMSG_DATA(ch);
324 destiface = pkt4info->ipi_ifindex;
325 } else if (ch->cmsg_level == IPPROTO_IPV6 &&
326 ch->cmsg_type == IPV6_HOPLIMIT) {
327 hlim = (int*)CMSG_DATA(ch);
331 // Check hoplimit if received
332 if (hlim && *hlim != 255)
335 // Detect interface for packet sockets
336 if (addr.ll.sll_family == AF_PACKET)
337 destiface = addr.ll.sll_ifindex;
339 struct interface *iface =
340 odhcpd_get_interface_by_index(destiface);
342 if (!iface && addr.nl.nl_family != AF_NETLINK)
345 char ipbuf[INET6_ADDRSTRLEN] = "kernel";
346 if (addr.ll.sll_family == AF_PACKET &&
347 len >= (ssize_t)sizeof(struct ip6_hdr))
348 inet_ntop(AF_INET6, &data_buf[8], ipbuf, sizeof(ipbuf));
349 else if (addr.in6.sin6_family == AF_INET6)
350 inet_ntop(AF_INET6, &addr.in6.sin6_addr, ipbuf, sizeof(ipbuf));
351 else if (addr.in.sin_family == AF_INET)
352 inet_ntop(AF_INET, &addr.in.sin_addr, ipbuf, sizeof(ipbuf));
354 syslog(LOG_NOTICE, "--");
355 syslog(LOG_NOTICE, "Received %li Bytes from %s%%%s", (long)len,
356 ipbuf, (iface) ? iface->ifname : "netlink");
358 e->handle_dgram(&addr, data_buf, len, iface);
362 // Register events for the multiplexer
363 int odhcpd_register(struct odhcpd_event *event)
365 event->uloop.cb = odhcpd_receive_packets;
366 return uloop_fd_add(&event->uloop, ULOOP_READ);
369 void odhcpd_urandom(void *data, size_t len)
371 read(urandom_fd, data, len);
375 time_t odhcpd_time(void)
378 syscall(SYS_clock_gettime, CLOCK_MONOTONIC, &ts);
383 static const char hexdigits[] = "0123456789abcdef";
384 static const int8_t hexvals[] = {
385 -1, -1, -1, -1, -1, -1, -1, -1, -1, -2, -2, -1, -1, -2, -1, -1,
386 -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1,
387 -2, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1,
388 0, 1, 2, 3, 4, 5, 6, 7, 8, 9, -1, -1, -1, -1, -1, -1,
389 -1, 10, 11, 12, 13, 14, 15, -1, -1, -1, -1, -1, -1, -1, -1, -1,
390 -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1,
391 -1, 10, 11, 12, 13, 14, 15, -1, -1, -1, -1, -1, -1, -1, -1, -1,
392 -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1,
395 ssize_t odhcpd_unhexlify(uint8_t *dst, size_t len, const char *src)
398 for (c = 0; c < len && src[0] && src[1]; ++c) {
399 int8_t x = (int8_t)*src++;
400 int8_t y = (int8_t)*src++;
401 if (x < 0 || (x = hexvals[x]) < 0
402 || y < 0 || (y = hexvals[y]) < 0)
405 while (((int8_t)*src) < 0 ||
406 (*src && hexvals[(uint8_t)*src] < 0))
414 void odhcpd_hexlify(char *dst, const uint8_t *src, size_t len)
416 for (size_t i = 0; i < len; ++i) {
417 *dst++ = hexdigits[src[i] >> 4];
418 *dst++ = hexdigits[src[i] & 0x0f];