2 * Copyright (C) 2012-2014 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.
26 #include <arpa/inet.h>
27 #include <sys/socket.h>
28 #include <sys/types.h>
29 #include <sys/ioctl.h>
30 #include <netinet/in.h>
31 #include <netinet/icmp6.h>
33 #include <linux/rtnetlink.h>
36 #define SOL_NETLINK 270
39 #ifndef NETLINK_ADD_MEMBERSHIP
40 #define NETLINK_ADD_MEMBERSHIP 1
44 #define IFF_LOWER_UP 0x10000
51 static bool nocarrier = false;
53 static int sock = -1, rtnl = -1;
54 static int if_index = 0;
55 static char if_name[IF_NAMESIZE] = {0};
56 static volatile int rs_attempt = 0;
57 static struct in6_addr lladdr = IN6ADDR_ANY_INIT;
59 static void ra_send_rs(int signal __attribute__((unused)));
61 int ra_init(const char *ifname, const struct in6_addr *ifid)
63 const pid_t ourpid = getpid();
64 sock = socket(AF_INET6, SOCK_RAW | SOCK_CLOEXEC, IPPROTO_ICMPV6);
68 if_index = if_nametoindex(ifname);
72 strncpy(if_name, ifname, sizeof(if_name) - 1);
75 rtnl = socket(AF_NETLINK, SOCK_DGRAM | SOCK_CLOEXEC, NETLINK_ROUTE);
79 struct sockaddr_nl rtnl_kernel = { .nl_family = AF_NETLINK };
80 if (connect(rtnl, (const struct sockaddr*)&rtnl_kernel, sizeof(rtnl_kernel)) < 0)
83 int val = RTNLGRP_LINK;
84 setsockopt(rtnl, SOL_NETLINK, NETLINK_ADD_MEMBERSHIP, &val, sizeof(val));
85 fcntl(rtnl, F_SETOWN, ourpid);
86 fcntl(rtnl, F_SETFL, fcntl(sock, F_GETFL) | O_ASYNC);
92 .hdr = {sizeof(req), RTM_GETLINK, NLM_F_REQUEST, 1, 0},
93 .ifi = {.ifi_index = if_index}
95 send(rtnl, &req, sizeof(req), 0);
97 // Filter ICMPv6 package types
98 struct icmp6_filter filt;
99 ICMP6_FILTER_SETBLOCKALL(&filt);
100 ICMP6_FILTER_SETPASS(ND_ROUTER_ADVERT, &filt);
101 setsockopt(sock, IPPROTO_ICMPV6, ICMP6_FILTER, &filt, sizeof(filt));
104 struct ipv6_mreq an = {ALL_IPV6_NODES, if_index};
105 setsockopt(sock, IPPROTO_IPV6, IPV6_ADD_MEMBERSHIP, &an, sizeof(an));
107 // Let the kernel compute our checksums
109 setsockopt(sock, IPPROTO_RAW, IPV6_CHECKSUM, &val, sizeof(val));
111 // This is required by RFC 4861
113 setsockopt(sock, IPPROTO_IPV6, IPV6_MULTICAST_HOPS, &val, sizeof(val));
115 // Receive multicast hops
117 setsockopt(sock, IPPROTO_IPV6, IPV6_RECVHOPLIMIT, &val, sizeof(val));
119 // Bind to one device
120 setsockopt(sock, SOL_SOCKET, SO_BINDTODEVICE, ifname, strlen(ifname));
123 fcntl(sock, F_SETOWN, ourpid);
124 fcntl(sock, F_SETFL, fcntl(sock, F_GETFL) | O_ASYNC);
127 signal(SIGALRM, ra_send_rs);
134 static void ra_send_rs(int signal __attribute__((unused)))
137 struct icmp6_hdr hdr;
138 struct icmpv6_opt lladdr;
140 .hdr = {ND_ROUTER_SOLICIT, 0, 0, {{0}}},
141 .lladdr = {ND_OPT_SOURCE_LINKADDR, 1, {0}},
143 const struct sockaddr_in6 dest = {AF_INET6, 0, 0, ALL_IPV6_ROUTERS, if_index};
144 size_t len = sizeof(rs);
147 memset(&ifr, 0, sizeof(ifr));
148 strncpy(ifr.ifr_name, if_name, sizeof(ifr.ifr_name));
149 if (!ioctl(sock, SIOCGIFHWADDR, &ifr)
150 && memcmp(rs.lladdr.data, ifr.ifr_hwaddr.sa_data, 6))
151 memcpy(rs.lladdr.data, ifr.ifr_hwaddr.sa_data, 6);
153 len = sizeof(struct icmp6_hdr);
155 sendto(sock, &rs, len, MSG_DONTWAIT, (struct sockaddr*)&dest, sizeof(dest));
157 if (++rs_attempt <= 3)
162 static int16_t pref_to_priority(uint8_t flags)
164 flags = (flags >> 3) & 0x03;
165 return (flags == 0x0) ? 1024 : (flags == 0x1) ? 512 :
166 (flags == 0x3) ? 2048 : -1;
170 static void update_proc(const char *sect, const char *opt, uint32_t value)
173 snprintf(buf, sizeof(buf), "/proc/sys/net/ipv6/%s/%s/%s", sect, if_name, opt);
175 int fd = open(buf, O_WRONLY);
176 write(fd, buf, snprintf(buf, sizeof(buf), "%u", value));
181 bool ra_link_up(void)
183 static bool firstcall = true;
186 struct ifinfomsg msg;
194 read = recv(rtnl, &resp, sizeof(resp), MSG_DONTWAIT);
195 if (read < 0 || !NLMSG_OK(&resp.hdr, (size_t)read) ||
196 resp.hdr.nlmsg_type != RTM_NEWLINK ||
197 resp.msg.ifi_index != if_index)
200 bool hascarrier = resp.msg.ifi_flags & IFF_LOWER_UP;
201 if (!firstcall && nocarrier != !hascarrier)
204 nocarrier = !hascarrier;
209 syslog(LOG_NOTICE, "carrier => %i event on %s", (int)!nocarrier, if_name);
218 static bool ra_icmpv6_valid(struct sockaddr_in6 *source, int hlim, uint8_t *data, size_t len)
220 struct icmp6_hdr *hdr = (struct icmp6_hdr*)data;
221 struct icmpv6_opt *opt, *end = (struct icmpv6_opt*)&data[len];
223 if (hlim != 255 || len < sizeof(*hdr) || hdr->icmp6_code)
226 switch (hdr->icmp6_type) {
227 case ND_ROUTER_ADVERT:
228 if (!IN6_IS_ADDR_LINKLOCAL(&source->sin6_addr))
231 opt = (struct icmpv6_opt*)((struct nd_router_advert*)data + 1);
238 icmpv6_for_each_option(opt, opt, end)
244 bool ra_process(void)
247 bool changed = false;
248 bool has_lladdr = !IN6_IS_ADDR_UNSPECIFIED(&lladdr);
249 uint8_t buf[1500], cmsg_buf[128];
250 struct nd_router_advert *adv = (struct nd_router_advert*)buf;
251 struct odhcp6c_entry entry = {IN6ADDR_ANY_INIT, 0, 0, IN6ADDR_ANY_INIT, 0, 0, 0, 0, 0, 0};
252 const struct in6_addr any = IN6ADDR_ANY_INIT;
255 // Autodetect interface-id if not specified
256 struct ifaddrs *ifaddr, *ifa;
258 if (getifaddrs(&ifaddr) == 0) {
259 for (ifa = ifaddr; ifa != NULL; ifa = ifa->ifa_next) {
260 struct sockaddr_in6 *addr;
262 if (ifa->ifa_addr == NULL || ifa->ifa_addr->sa_family != AF_INET6)
265 addr = (struct sockaddr_in6*)ifa->ifa_addr;
267 if (!IN6_IS_ADDR_LINKLOCAL(&addr->sin6_addr))
270 if (!strcmp(ifa->ifa_name, if_name)) {
271 lladdr = addr->sin6_addr;
282 struct sockaddr_in6 from;
283 struct iovec iov = {buf, sizeof(buf)};
284 struct msghdr msg = {&from, sizeof(from), &iov, 1,
285 cmsg_buf, sizeof(cmsg_buf), 0};
287 ssize_t len = recvmsg(sock, &msg, MSG_DONTWAIT);
295 for (struct cmsghdr *ch = CMSG_FIRSTHDR(&msg); ch != NULL;
296 ch = CMSG_NXTHDR(&msg, ch))
297 if (ch->cmsg_level == IPPROTO_IPV6 &&
298 ch->cmsg_type == IPV6_HOPLIMIT)
299 memcpy(&hlim, CMSG_DATA(ch), sizeof(hlim));
301 if (!ra_icmpv6_valid(&from, hlim, buf, len))
304 // Stop sending solicits
305 if (rs_attempt > 0) {
314 uint32_t router_valid = ntohs(adv->nd_ra_router_lifetime);
316 // Parse default route
319 entry.router = from.sin6_addr;
320 entry.priority = pref_to_priority(adv->nd_ra_flags_reserved);
321 if (entry.priority < 0)
322 entry.priority = pref_to_priority(0);
323 entry.valid = router_valid;
324 entry.preferred = entry.valid;
325 changed |= odhcp6c_update_entry(STATE_RA_ROUTE, &entry);
328 if (adv->nd_ra_curhoplimit)
329 update_proc("conf", "hop_limit", adv->nd_ra_curhoplimit);
331 // Parse ND parameters
332 uint32_t reachable = ntohl(adv->nd_ra_reachable);
333 if (reachable > 0 && reachable <= 3600000)
334 update_proc("neigh", "base_reachable_time_ms", reachable);
336 uint32_t retransmit = ntohl(adv->nd_ra_retransmit);
337 if (retransmit > 0 && retransmit <= 60000)
338 update_proc("neigh", "retrans_time_ms", retransmit);
342 struct icmpv6_opt *opt;
343 icmpv6_for_each_option(opt, &adv[1], &buf[len]) {
344 if (opt->type == ND_OPT_MTU) {
345 uint32_t *mtu = (uint32_t*)&opt->data[2];
346 if (ntohl(*mtu) >= 1280 && ntohl(*mtu) <= 65535)
347 update_proc("conf", "mtu", ntohl(*mtu));
348 } else if (opt->type == ND_OPT_ROUTE_INFORMATION && opt->len <= 3) {
349 entry.router = from.sin6_addr;
351 entry.priority = pref_to_priority(opt->data[1]);
352 entry.length = opt->data[0];
353 uint32_t *valid = (uint32_t*)&opt->data[2];
354 entry.valid = ntohl(*valid);
355 memcpy(&entry.target, &opt->data[6], (opt->len - 1) * 8);
357 if (entry.length > 128 || IN6_IS_ADDR_LINKLOCAL(&entry.target)
358 || IN6_IS_ADDR_LOOPBACK(&entry.target)
359 || IN6_IS_ADDR_MULTICAST(&entry.target))
362 if (entry.priority > 0)
363 changed |= odhcp6c_update_entry(STATE_RA_ROUTE, &entry);
364 } else if (opt->type == ND_OPT_PREFIX_INFORMATION && opt->len == 4) {
365 struct nd_opt_prefix_info *pinfo = (struct nd_opt_prefix_info*)opt;
367 entry.target = pinfo->nd_opt_pi_prefix;
368 entry.priority = 256;
369 entry.length = pinfo->nd_opt_pi_prefix_len;
370 entry.valid = ntohl(pinfo->nd_opt_pi_valid_time);
371 entry.preferred = ntohl(pinfo->nd_opt_pi_preferred_time);
373 if (entry.length > 128 || IN6_IS_ADDR_LINKLOCAL(&entry.target)
374 || IN6_IS_ADDR_LOOPBACK(&entry.target)
375 || IN6_IS_ADDR_MULTICAST(&entry.target)
376 || entry.valid < entry.preferred)
379 if (pinfo->nd_opt_pi_flags_reserved & ND_OPT_PI_FLAG_ONLINK)
380 changed |= odhcp6c_update_entry_safe(STATE_RA_ROUTE, &entry, 7200);
382 if (!(pinfo->nd_opt_pi_flags_reserved & ND_OPT_PI_FLAG_AUTO) ||
383 pinfo->nd_opt_pi_prefix_len != 64)
386 entry.target.s6_addr32[2] = lladdr.s6_addr32[2];
387 entry.target.s6_addr32[3] = lladdr.s6_addr32[3];
389 changed |= odhcp6c_update_entry_safe(STATE_RA_PREFIX, &entry, 7200);
390 } else if (opt->type == ND_OPT_RECURSIVE_DNS && opt->len > 2) {
391 entry.router = from.sin6_addr;
394 uint32_t *valid = (uint32_t*)&opt->data[2];
395 entry.valid = ntohl(*valid);
398 for (ssize_t i = 0; i < (opt->len - 1) / 2; ++i) {
399 memcpy(&entry.target, &opt->data[6 + i * sizeof(entry.target)],
400 sizeof(entry.target));
401 changed |= odhcp6c_update_entry(STATE_RA_DNS, &entry);
407 struct odhcp6c_entry *entry = odhcp6c_get_state(STATE_RA_DNS, &ra_dns_len);
408 for (size_t i = 0; i < ra_dns_len / sizeof(*entry); ++i)
409 if (IN6_ARE_ADDR_EQUAL(&entry[i].router, &from.sin6_addr) &&
410 entry[i].valid > router_valid)
411 entry[i].valid = router_valid;
417 return found && changed;