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 strncpy(ifr.ifr_name, iface->ifname, sizeof(ifr.ifr_name));
135 if (ioctl(ioctl_sock, SIOCGIFHWADDR, &ifr) < 0)
137 memcpy(mac, ifr.ifr_hwaddr.sa_data, 6);
142 // Forwards a packet on a specific interface
143 ssize_t odhcpd_send(int socket, struct sockaddr_in6 *dest,
144 struct iovec *iov, size_t iov_len,
145 const struct interface *iface)
148 uint8_t cmsg_buf[CMSG_SPACE(sizeof(struct in6_pktinfo))] = {0};
149 struct msghdr msg = {(void*)dest, sizeof(*dest), iov, iov_len,
150 cmsg_buf, sizeof(cmsg_buf), 0};
152 // Set control data (define destination interface)
153 struct cmsghdr *chdr = CMSG_FIRSTHDR(&msg);
154 chdr->cmsg_level = IPPROTO_IPV6;
155 chdr->cmsg_type = IPV6_PKTINFO;
156 chdr->cmsg_len = CMSG_LEN(sizeof(struct in6_pktinfo));
157 struct in6_pktinfo *pktinfo = (struct in6_pktinfo*)CMSG_DATA(chdr);
158 pktinfo->ipi6_ifindex = iface->ifindex;
160 // Also set scope ID if link-local
161 if (IN6_IS_ADDR_LINKLOCAL(&dest->sin6_addr)
162 || IN6_IS_ADDR_MC_LINKLOCAL(&dest->sin6_addr))
163 dest->sin6_scope_id = iface->ifindex;
165 // IPV6_PKTINFO doesn't really work for IPv6-raw sockets (bug?)
166 if (dest->sin6_port == 0) {
167 msg.msg_control = NULL;
168 msg.msg_controllen = 0;
171 char ipbuf[INET6_ADDRSTRLEN];
172 inet_ntop(AF_INET6, &dest->sin6_addr, ipbuf, sizeof(ipbuf));
174 ssize_t sent = sendmsg(socket, &msg, MSG_DONTWAIT);
176 syslog(LOG_WARNING, "Failed to send to %s%%%s (%s)",
177 ipbuf, iface->ifname, strerror(errno));
179 syslog(LOG_NOTICE, "Sent %li bytes to %s%%%s",
180 (long)sent, ipbuf, iface->ifname);
185 // Detect an IPV6-address currently assigned to the given interface
186 ssize_t odhcpd_get_interface_addresses(int ifindex,
187 struct odhcpd_ipaddr *addrs, size_t cnt)
191 struct ifaddrmsg ifa;
192 } req = {{sizeof(req), RTM_GETADDR, NLM_F_REQUEST | NLM_F_DUMP,
193 ++rtnl_seq, 0}, {AF_INET6, 0, 0, 0, ifindex}};
194 if (send(rtnl_socket, &req, sizeof(req), 0) < (ssize_t)sizeof(req))
198 ssize_t len = 0, ret = 0;
200 for (struct nlmsghdr *nhm = NULL; ; nhm = NLMSG_NEXT(nhm, len)) {
201 while (len < 0 || !NLMSG_OK(nhm, (size_t)len)) {
202 len = recv(rtnl_socket, buf, sizeof(buf), 0);
203 nhm = (struct nlmsghdr*)buf;
204 if (len < 0 || !NLMSG_OK(nhm, (size_t)len)) {
212 if (nhm->nlmsg_type != RTM_NEWADDR)
215 // Skip address but keep clearing socket buffer
216 if (ret >= (ssize_t)cnt)
219 struct ifaddrmsg *ifa = NLMSG_DATA(nhm);
220 if (ifa->ifa_scope != RT_SCOPE_UNIVERSE ||
221 ifa->ifa_index != (unsigned)ifindex)
224 struct rtattr *rta = (struct rtattr*)&ifa[1];
225 size_t alen = NLMSG_PAYLOAD(nhm, sizeof(*ifa));
226 memset(&addrs[ret], 0, sizeof(addrs[ret]));
227 addrs[ret].prefix = ifa->ifa_prefixlen;
229 while (RTA_OK(rta, alen)) {
230 if (rta->rta_type == IFA_ADDRESS) {
231 memcpy(&addrs[ret].addr, RTA_DATA(rta),
232 sizeof(struct in6_addr));
233 } else if (rta->rta_type == IFA_CACHEINFO) {
234 struct ifa_cacheinfo *ifc = RTA_DATA(rta);
235 addrs[ret].preferred = ifc->ifa_prefered;
236 addrs[ret].valid = ifc->ifa_valid;
239 rta = RTA_NEXT(rta, alen);
242 if (ifa->ifa_flags & IFA_F_DEPRECATED)
243 addrs[ret].preferred = 0;
252 struct interface* odhcpd_get_interface_by_index(int ifindex)
254 struct interface *iface;
255 list_for_each_entry(iface, &interfaces, head)
256 if (iface->ifindex == ifindex)
263 struct interface* odhcpd_get_interface_by_name(const char *name)
265 struct interface *iface;
266 list_for_each_entry(iface, &interfaces, head)
267 if (!strcmp(iface->ifname, name))
274 struct interface* odhcpd_get_master_interface(void)
276 struct interface *iface;
277 list_for_each_entry(iface, &interfaces, head)
285 // Convenience function to receive and do basic validation of packets
286 static void odhcpd_receive_packets(struct uloop_fd *u, _unused unsigned int events)
288 struct odhcpd_event *e = container_of(u, struct odhcpd_event, uloop);
290 uint8_t data_buf[RELAYD_BUFFER_SIZE], cmsg_buf[128];
292 struct sockaddr_in6 in6;
293 struct sockaddr_in in;
294 struct sockaddr_ll ll;
295 struct sockaddr_nl nl;
299 struct iovec iov = {data_buf, sizeof(data_buf)};
300 struct msghdr msg = {&addr, sizeof(addr), &iov, 1,
301 cmsg_buf, sizeof(cmsg_buf), 0};
303 ssize_t len = recvmsg(u->fd, &msg, MSG_DONTWAIT);
312 // Extract destination interface
315 struct in6_pktinfo *pktinfo;
316 struct in_pktinfo *pkt4info;
317 for (struct cmsghdr *ch = CMSG_FIRSTHDR(&msg); ch != NULL &&
318 destiface == 0; ch = CMSG_NXTHDR(&msg, ch)) {
319 if (ch->cmsg_level == IPPROTO_IPV6 &&
320 ch->cmsg_type == IPV6_PKTINFO) {
321 pktinfo = (struct in6_pktinfo*)CMSG_DATA(ch);
322 destiface = pktinfo->ipi6_ifindex;
323 } else if (ch->cmsg_level == IPPROTO_IP &&
324 ch->cmsg_type == IP_PKTINFO) {
325 pkt4info = (struct in_pktinfo*)CMSG_DATA(ch);
326 destiface = pkt4info->ipi_ifindex;
327 } else if (ch->cmsg_level == IPPROTO_IPV6 &&
328 ch->cmsg_type == IPV6_HOPLIMIT) {
329 hlim = (int*)CMSG_DATA(ch);
333 // Check hoplimit if received
334 if (hlim && *hlim != 255)
337 // Detect interface for packet sockets
338 if (addr.ll.sll_family == AF_PACKET)
339 destiface = addr.ll.sll_ifindex;
341 struct interface *iface =
342 odhcpd_get_interface_by_index(destiface);
344 if (!iface && addr.nl.nl_family != AF_NETLINK)
347 char ipbuf[INET6_ADDRSTRLEN] = "kernel";
348 if (addr.ll.sll_family == AF_PACKET &&
349 len >= (ssize_t)sizeof(struct ip6_hdr))
350 inet_ntop(AF_INET6, &data_buf[8], ipbuf, sizeof(ipbuf));
351 else if (addr.in6.sin6_family == AF_INET6)
352 inet_ntop(AF_INET6, &addr.in6.sin6_addr, ipbuf, sizeof(ipbuf));
353 else if (addr.in.sin_family == AF_INET)
354 inet_ntop(AF_INET, &addr.in.sin_addr, ipbuf, sizeof(ipbuf));
356 syslog(LOG_NOTICE, "--");
357 syslog(LOG_NOTICE, "Received %li Bytes from %s%%%s", (long)len,
358 ipbuf, (iface) ? iface->ifname : "netlink");
360 e->handle_dgram(&addr, data_buf, len, iface);
364 // Register events for the multiplexer
365 int odhcpd_register(struct odhcpd_event *event)
367 event->uloop.cb = odhcpd_receive_packets;
368 return uloop_fd_add(&event->uloop, ULOOP_READ);
371 void odhcpd_urandom(void *data, size_t len)
373 read(urandom_fd, data, len);
377 time_t odhcpd_time(void)
380 syscall(SYS_clock_gettime, CLOCK_MONOTONIC, &ts);
385 static const char hexdigits[] = "0123456789abcdef";
386 static const int8_t hexvals[] = {
387 -1, -1, -1, -1, -1, -1, -1, -1, -1, -2, -2, -1, -1, -2, -1, -1,
388 -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1,
389 -2, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1,
390 0, 1, 2, 3, 4, 5, 6, 7, 8, 9, -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,
393 -1, 10, 11, 12, 13, 14, 15, -1, -1, -1, -1, -1, -1, -1, -1, -1,
394 -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1,
397 ssize_t odhcpd_unhexlify(uint8_t *dst, size_t len, const char *src)
400 for (c = 0; c < len && src[0] && src[1]; ++c) {
401 int8_t x = (int8_t)*src++;
402 int8_t y = (int8_t)*src++;
403 if (x < 0 || (x = hexvals[x]) < 0
404 || y < 0 || (y = hexvals[y]) < 0)
407 while (((int8_t)*src) < 0 ||
408 (*src && hexvals[(uint8_t)*src] < 0))
416 void odhcpd_hexlify(char *dst, const uint8_t *src, size_t len)
418 for (size_t i = 0; i < len; ++i) {
419 *dst++ = hexdigits[src[i] >> 4];
420 *dst++ = hexdigits[src[i] & 0x0f];