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 <netinet/in.h>
30 #include <netinet/icmp6.h>
32 #include <linux/rtnetlink.h>
35 #define SOL_NETLINK 270
38 #ifndef NETLINK_ADD_MEMBERSHIP
39 #define NETLINK_ADD_MEMBERSHIP 1
43 #define IFF_LOWER_UP 0x10000
50 static bool nocarrier = false;
52 static int sock = -1, rtnl = -1;
53 static int if_index = 0;
54 static char if_name[IF_NAMESIZE] = {0};
55 static volatile int rs_attempt = 0;
56 static struct in6_addr lladdr = IN6ADDR_ANY_INIT;
60 struct icmpv6_opt lladdr;
62 .hdr = {ND_ROUTER_SOLICIT, 0, 0, {{0}}},
63 .lladdr = {ND_OPT_SOURCE_LINKADDR, 1, {0}},
67 static void ra_send_rs(int signal __attribute__((unused)));
69 int ra_init(const char *ifname, const struct in6_addr *ifid)
71 const pid_t ourpid = getpid();
72 sock = socket(AF_INET6, SOCK_RAW | SOCK_CLOEXEC, IPPROTO_ICMPV6);
76 if_index = if_nametoindex(ifname);
80 strncpy(if_name, ifname, sizeof(if_name) - 1);
83 rtnl = socket(AF_NETLINK, SOCK_DGRAM | SOCK_CLOEXEC, NETLINK_ROUTE);
87 struct sockaddr_nl rtnl_kernel = { .nl_family = AF_NETLINK };
88 if (connect(rtnl, (const struct sockaddr*)&rtnl_kernel, sizeof(rtnl_kernel)) < 0)
91 int val = RTNLGRP_LINK;
92 setsockopt(rtnl, SOL_NETLINK, NETLINK_ADD_MEMBERSHIP, &val, sizeof(val));
93 fcntl(rtnl, F_SETOWN, ourpid);
94 fcntl(rtnl, F_SETFL, fcntl(sock, F_GETFL) | O_ASYNC);
100 .hdr = {sizeof(req), RTM_GETLINK, NLM_F_REQUEST, 1, 0},
101 .ifi = {.ifi_index = if_index}
103 send(rtnl, &req, sizeof(req), 0);
106 // Filter ICMPv6 package types
107 struct icmp6_filter filt;
108 ICMP6_FILTER_SETBLOCKALL(&filt);
109 ICMP6_FILTER_SETPASS(ND_ROUTER_ADVERT, &filt);
110 setsockopt(sock, IPPROTO_ICMPV6, ICMP6_FILTER, &filt, sizeof(filt));
113 struct ipv6_mreq an = {ALL_IPV6_NODES, if_index};
114 setsockopt(sock, IPPROTO_IPV6, IPV6_ADD_MEMBERSHIP, &an, sizeof(an));
116 // Let the kernel compute our checksums
118 setsockopt(sock, IPPROTO_RAW, IPV6_CHECKSUM, &val, sizeof(val));
120 // This is required by RFC 4861
122 setsockopt(sock, IPPROTO_IPV6, IPV6_MULTICAST_HOPS, &val, sizeof(val));
124 // Receive multicast hops
126 setsockopt(sock, IPPROTO_IPV6, IPV6_RECVHOPLIMIT, &val, sizeof(val));
128 // Bind to one device
129 setsockopt(sock, SOL_SOCKET, SO_BINDTODEVICE, ifname, strlen(ifname));
132 fcntl(sock, F_SETOWN, ourpid);
133 fcntl(sock, F_SETFL, fcntl(sock, F_GETFL) | O_ASYNC);
136 signal(SIGALRM, ra_send_rs);
143 static void ra_send_rs(int signal __attribute__((unused)))
145 const struct sockaddr_in6 dest = {AF_INET6, 0, 0, ALL_IPV6_ROUTERS, if_index};
146 const struct icmpv6_opt llnull = {ND_OPT_SOURCE_LINKADDR, 1, {0}};
149 if ((rs_attempt % 2 == 0) && memcmp(&rs.lladdr, &llnull, sizeof(llnull)))
152 len = sizeof(struct icmp6_hdr);
154 sendto(sock, &rs, len, MSG_DONTWAIT, (struct sockaddr*)&dest, sizeof(dest));
156 if (++rs_attempt <= 3)
161 static int16_t pref_to_priority(uint8_t flags)
163 flags = (flags >> 3) & 0x03;
164 return (flags == 0x0) ? 1024 : (flags == 0x1) ? 512 :
165 (flags == 0x3) ? 2048 : -1;
169 static void update_proc(const char *sect, const char *opt, uint32_t value)
172 snprintf(buf, sizeof(buf), "/proc/sys/net/ipv6/%s/%s/%s", sect, if_name, opt);
174 int fd = open(buf, O_WRONLY);
175 write(fd, buf, snprintf(buf, sizeof(buf), "%u", value));
180 bool ra_link_up(void)
182 static bool firstcall = true;
185 struct ifinfomsg msg;
193 read = recv(rtnl, &resp, sizeof(resp), MSG_DONTWAIT);
194 if (read < 0 || !NLMSG_OK(&resp.hdr, (size_t)read) ||
195 resp.hdr.nlmsg_type != RTM_NEWLINK ||
196 resp.msg.ifi_index != if_index)
199 ssize_t alen = NLMSG_PAYLOAD(&resp.hdr, sizeof(resp.msg));
200 for (struct rtattr *rta = (struct rtattr*)(resp.pad);
201 RTA_OK(rta, alen); rta = RTA_NEXT(rta, alen)) {
202 if (rta->rta_type == IFLA_ADDRESS &&
203 RTA_PAYLOAD(rta) >= sizeof(rs.lladdr.data))
204 memcpy(rs.lladdr.data, RTA_DATA(rta), sizeof(rs.lladdr.data));
207 bool hascarrier = resp.msg.ifi_flags & IFF_LOWER_UP;
208 if (!firstcall && nocarrier != !hascarrier)
211 nocarrier = !hascarrier;
216 syslog(LOG_NOTICE, "carrier => %i event on %s", (int)!nocarrier, if_name);
225 static bool ra_icmpv6_valid(struct sockaddr_in6 *source, int hlim, uint8_t *data, size_t len)
227 struct icmp6_hdr *hdr = (struct icmp6_hdr*)data;
228 struct icmpv6_opt *opt, *end = (struct icmpv6_opt*)&data[len];
230 if (hlim != 255 || len < sizeof(*hdr) || hdr->icmp6_code)
233 switch (hdr->icmp6_type) {
234 case ND_ROUTER_ADVERT:
235 if (!IN6_IS_ADDR_LINKLOCAL(&source->sin6_addr))
238 opt = (struct icmpv6_opt*)((struct nd_router_advert*)data + 1);
245 icmpv6_for_each_option(opt, opt, end)
251 bool ra_process(void)
254 bool changed = false;
255 bool has_lladdr = !IN6_IS_ADDR_UNSPECIFIED(&lladdr);
256 uint8_t buf[1500], cmsg_buf[128];
257 struct nd_router_advert *adv = (struct nd_router_advert*)buf;
258 struct odhcp6c_entry entry = {IN6ADDR_ANY_INIT, 0, 0, IN6ADDR_ANY_INIT, 0, 0, 0, 0, 0, 0};
259 const struct in6_addr any = IN6ADDR_ANY_INIT;
262 // Autodetect interface-id if not specified
263 struct ifaddrs *ifaddr, *ifa;
265 if (getifaddrs(&ifaddr) == 0) {
266 for (ifa = ifaddr; ifa != NULL; ifa = ifa->ifa_next) {
267 struct sockaddr_in6 *addr;
269 if (ifa->ifa_addr == NULL || ifa->ifa_addr->sa_family != AF_INET6)
272 addr = (struct sockaddr_in6*)ifa->ifa_addr;
274 if (!IN6_IS_ADDR_LINKLOCAL(&addr->sin6_addr))
277 if (!strcmp(ifa->ifa_name, if_name)) {
278 lladdr = addr->sin6_addr;
289 struct sockaddr_in6 from;
290 struct iovec iov = {buf, sizeof(buf)};
291 struct msghdr msg = {&from, sizeof(from), &iov, 1,
292 cmsg_buf, sizeof(cmsg_buf), 0};
294 ssize_t len = recvmsg(sock, &msg, MSG_DONTWAIT);
302 for (struct cmsghdr *ch = CMSG_FIRSTHDR(&msg); ch != NULL;
303 ch = CMSG_NXTHDR(&msg, ch))
304 if (ch->cmsg_level == IPPROTO_IPV6 &&
305 ch->cmsg_type == IPV6_HOPLIMIT)
306 memcpy(&hlim, CMSG_DATA(ch), sizeof(hlim));
308 if (!ra_icmpv6_valid(&from, hlim, buf, len))
311 // Stop sending solicits
312 if (rs_attempt > 0) {
321 uint32_t router_valid = ntohs(adv->nd_ra_router_lifetime);
323 // Parse default route
326 entry.router = from.sin6_addr;
327 entry.priority = pref_to_priority(adv->nd_ra_flags_reserved);
328 if (entry.priority < 0)
329 entry.priority = pref_to_priority(0);
330 entry.valid = router_valid;
331 entry.preferred = entry.valid;
332 changed |= odhcp6c_update_entry(STATE_RA_ROUTE, &entry, 0, true);
335 if (adv->nd_ra_curhoplimit)
336 update_proc("conf", "hop_limit", adv->nd_ra_curhoplimit);
338 // Parse ND parameters
339 uint32_t reachable = ntohl(adv->nd_ra_reachable);
340 if (reachable > 0 && reachable <= 3600000)
341 update_proc("neigh", "base_reachable_time_ms", reachable);
343 uint32_t retransmit = ntohl(adv->nd_ra_retransmit);
344 if (retransmit > 0 && retransmit <= 60000)
345 update_proc("neigh", "retrans_time_ms", retransmit);
349 struct icmpv6_opt *opt;
350 icmpv6_for_each_option(opt, &adv[1], &buf[len]) {
351 if (opt->type == ND_OPT_MTU) {
352 uint32_t *mtu = (uint32_t*)&opt->data[2];
353 if (ntohl(*mtu) >= 1280 && ntohl(*mtu) <= 65535)
354 update_proc("conf", "mtu", ntohl(*mtu));
355 } else if (opt->type == ND_OPT_ROUTE_INFORMATION && opt->len <= 3) {
356 entry.router = from.sin6_addr;
358 entry.priority = pref_to_priority(opt->data[1]);
359 entry.length = opt->data[0];
360 uint32_t *valid = (uint32_t*)&opt->data[2];
361 entry.valid = ntohl(*valid);
362 memcpy(&entry.target, &opt->data[6], (opt->len - 1) * 8);
364 if (entry.length > 128 || IN6_IS_ADDR_LINKLOCAL(&entry.target)
365 || IN6_IS_ADDR_LOOPBACK(&entry.target)
366 || IN6_IS_ADDR_MULTICAST(&entry.target))
369 if (entry.priority > 0)
370 changed |= odhcp6c_update_entry(STATE_RA_ROUTE, &entry, 0, true);
371 } else if (opt->type == ND_OPT_PREFIX_INFORMATION && opt->len == 4) {
372 struct nd_opt_prefix_info *pinfo = (struct nd_opt_prefix_info*)opt;
374 entry.target = pinfo->nd_opt_pi_prefix;
375 entry.priority = 256;
376 entry.length = pinfo->nd_opt_pi_prefix_len;
377 entry.valid = ntohl(pinfo->nd_opt_pi_valid_time);
378 entry.preferred = ntohl(pinfo->nd_opt_pi_preferred_time);
380 if (entry.length > 128 || IN6_IS_ADDR_LINKLOCAL(&entry.target)
381 || IN6_IS_ADDR_LOOPBACK(&entry.target)
382 || IN6_IS_ADDR_MULTICAST(&entry.target)
383 || entry.valid < entry.preferred)
386 if (pinfo->nd_opt_pi_flags_reserved & ND_OPT_PI_FLAG_ONLINK)
387 changed |= odhcp6c_update_entry(STATE_RA_ROUTE, &entry, 7200, true);
389 if (!(pinfo->nd_opt_pi_flags_reserved & ND_OPT_PI_FLAG_AUTO) ||
390 pinfo->nd_opt_pi_prefix_len != 64)
393 entry.target.s6_addr32[2] = lladdr.s6_addr32[2];
394 entry.target.s6_addr32[3] = lladdr.s6_addr32[3];
396 changed |= odhcp6c_update_entry(STATE_RA_PREFIX, &entry, 7200, true);
397 } else if (opt->type == ND_OPT_RECURSIVE_DNS && opt->len > 2) {
398 entry.router = from.sin6_addr;
401 uint32_t *valid = (uint32_t*)&opt->data[2];
402 entry.valid = ntohl(*valid);
405 for (ssize_t i = 0; i < (opt->len - 1) / 2; ++i) {
406 memcpy(&entry.target, &opt->data[6 + i * sizeof(entry.target)],
407 sizeof(entry.target));
408 changed |= odhcp6c_update_entry(STATE_RA_DNS, &entry, 0, true);
414 struct odhcp6c_entry *entry = odhcp6c_get_state(STATE_RA_DNS, &ra_dns_len);
415 for (size_t i = 0; i < ra_dns_len / sizeof(*entry); ++i)
416 if (IN6_ARE_ADDR_EQUAL(&entry[i].router, &from.sin6_addr) &&
417 entry[i].valid > router_valid)
418 entry[i].valid = router_valid;
424 return found && changed;