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.
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;
58 static void ra_send_rs(int signal __attribute__((unused)));
60 int ra_init(const char *ifname, const struct in6_addr *ifid)
62 const pid_t ourpid = getpid();
63 sock = socket(AF_INET6, SOCK_RAW | SOCK_CLOEXEC, IPPROTO_ICMPV6);
67 if_index = if_nametoindex(ifname);
71 strncpy(if_name, ifname, sizeof(if_name) - 1);
74 rtnl = socket(AF_NETLINK, SOCK_DGRAM | SOCK_CLOEXEC, NETLINK_ROUTE);
78 struct sockaddr_nl rtnl_kernel = { .nl_family = AF_NETLINK };
79 if (connect(rtnl, (const struct sockaddr*)&rtnl_kernel, sizeof(rtnl_kernel)) < 0)
82 int val = RTNLGRP_LINK;
83 setsockopt(rtnl, SOL_NETLINK, NETLINK_ADD_MEMBERSHIP, &val, sizeof(val));
84 fcntl(rtnl, F_SETOWN, ourpid);
85 fcntl(rtnl, F_SETFL, fcntl(sock, F_GETFL) | O_ASYNC);
91 .hdr = {sizeof(req), RTM_GETLINK, NLM_F_REQUEST, 1, 0},
92 .ifi = {.ifi_index = if_index}
94 send(rtnl, &req, sizeof(req), 0);
96 // Filter ICMPv6 package types
97 struct icmp6_filter filt;
98 ICMP6_FILTER_SETBLOCKALL(&filt);
99 ICMP6_FILTER_SETPASS(ND_ROUTER_ADVERT, &filt);
100 setsockopt(sock, IPPROTO_ICMPV6, ICMP6_FILTER, &filt, sizeof(filt));
103 struct ipv6_mreq an = {ALL_IPV6_NODES, if_index};
104 setsockopt(sock, IPPROTO_IPV6, IPV6_ADD_MEMBERSHIP, &an, sizeof(an));
106 // Let the kernel compute our checksums
108 setsockopt(sock, IPPROTO_RAW, IPV6_CHECKSUM, &val, sizeof(val));
110 // This is required by RFC 4861
112 setsockopt(sock, IPPROTO_IPV6, IPV6_MULTICAST_HOPS, &val, sizeof(val));
114 // Receive multicast hops
116 setsockopt(sock, IPPROTO_IPV6, IPV6_RECVHOPLIMIT, &val, sizeof(val));
118 // Bind to one device
119 setsockopt(sock, SOL_SOCKET, SO_BINDTODEVICE, ifname, strlen(ifname));
122 fcntl(sock, F_SETOWN, ourpid);
123 fcntl(sock, F_SETFL, fcntl(sock, F_GETFL) | O_ASYNC);
126 signal(SIGALRM, ra_send_rs);
133 static void ra_send_rs(int signal __attribute__((unused)))
135 const struct icmp6_hdr rs = {ND_ROUTER_SOLICIT, 0, 0, {{0}}};
136 const struct sockaddr_in6 dest = {AF_INET6, 0, 0, ALL_IPV6_ROUTERS, if_index};
137 sendto(sock, &rs, sizeof(rs), MSG_DONTWAIT, (struct sockaddr*)&dest, sizeof(dest));
139 if (++rs_attempt <= 3)
144 static int16_t pref_to_priority(uint8_t flags)
146 flags = (flags >> 3) & 0x03;
147 return (flags == 0x0) ? 1024 : (flags == 0x1) ? 512 :
148 (flags == 0x3) ? 2048 : -1;
152 static void update_proc(const char *sect, const char *opt, uint32_t value)
155 snprintf(buf, sizeof(buf), "/proc/sys/net/ipv6/%s/%s/%s", sect, if_name, opt);
157 int fd = open(buf, O_WRONLY);
158 write(fd, buf, snprintf(buf, sizeof(buf), "%u", value));
163 bool ra_link_up(void)
165 static bool firstcall = true;
168 struct ifinfomsg msg;
176 read = recv(rtnl, &resp, sizeof(resp), MSG_DONTWAIT);
177 if (read < 0 || !NLMSG_OK(&resp.hdr, (size_t)read) ||
178 resp.hdr.nlmsg_type != RTM_NEWLINK ||
179 resp.msg.ifi_index != if_index)
182 bool hascarrier = resp.msg.ifi_flags & IFF_LOWER_UP;
183 if (!firstcall && nocarrier != !hascarrier)
186 nocarrier = !hascarrier;
191 syslog(LOG_NOTICE, "carrier => %i event on %s", (int)!nocarrier, if_name);
200 static bool ra_icmpv6_valid(struct sockaddr_in6 *source, int hlim, uint8_t *data, size_t len)
202 struct icmp6_hdr *hdr = (struct icmp6_hdr*)data;
203 struct icmpv6_opt *opt, *end = (struct icmpv6_opt*)&data[len];
205 if (hlim != 255 || len < sizeof(*hdr) || hdr->icmp6_code)
208 switch (hdr->icmp6_type) {
209 case ND_ROUTER_ADVERT:
210 if (!IN6_IS_ADDR_LINKLOCAL(&source->sin6_addr))
213 opt = (struct icmpv6_opt*)((struct nd_router_advert*)data + 1);
220 icmpv6_for_each_option(opt, opt, end)
226 bool ra_process(void)
229 bool changed = false;
230 bool has_lladdr = !IN6_IS_ADDR_UNSPECIFIED(&lladdr);
231 uint8_t buf[1500], cmsg_buf[128];
232 struct nd_router_advert *adv = (struct nd_router_advert*)buf;
233 struct odhcp6c_entry entry = {IN6ADDR_ANY_INIT, 0, 0, IN6ADDR_ANY_INIT, 0, 0, 0, 0, 0};
234 const struct in6_addr any = IN6ADDR_ANY_INIT;
237 // Autodetect interface-id if not specified
238 struct ifaddrs *ifaddr, *ifa;
240 if (getifaddrs(&ifaddr) == 0) {
241 for (ifa = ifaddr; ifa != NULL; ifa = ifa->ifa_next) {
242 struct sockaddr_in6 *addr;
244 if (ifa->ifa_addr == NULL || ifa->ifa_addr->sa_family != AF_INET6)
247 addr = (struct sockaddr_in6*)ifa->ifa_addr;
249 if (!IN6_IS_ADDR_LINKLOCAL(&addr->sin6_addr))
252 if (!strcmp(ifa->ifa_name, if_name)) {
253 lladdr = addr->sin6_addr;
264 struct sockaddr_in6 from;
265 struct iovec iov = {buf, sizeof(buf)};
266 struct msghdr msg = {&from, sizeof(from), &iov, 1,
267 cmsg_buf, sizeof(cmsg_buf), 0};
269 ssize_t len = recvmsg(sock, &msg, MSG_DONTWAIT);
277 for (struct cmsghdr *ch = CMSG_FIRSTHDR(&msg); ch != NULL;
278 ch = CMSG_NXTHDR(&msg, ch))
279 if (ch->cmsg_level == IPPROTO_IPV6 &&
280 ch->cmsg_type == IPV6_HOPLIMIT)
281 memcpy(&hlim, CMSG_DATA(ch), sizeof(hlim));
283 if (!ra_icmpv6_valid(&from, hlim, buf, len))
286 // Stop sending solicits
287 if (rs_attempt > 0) {
296 uint32_t router_valid = ntohs(adv->nd_ra_router_lifetime);
298 // Parse default route
301 entry.router = from.sin6_addr;
302 entry.priority = pref_to_priority(adv->nd_ra_flags_reserved);
303 if (entry.priority < 0)
304 entry.priority = pref_to_priority(0);
305 entry.valid = router_valid;
306 entry.preferred = entry.valid;
307 changed |= odhcp6c_update_entry(STATE_RA_ROUTE, &entry);
310 if (adv->nd_ra_curhoplimit)
311 update_proc("conf", "hop_limit", adv->nd_ra_curhoplimit);
313 // Parse ND parameters
314 if (ntohl(adv->nd_ra_reachable) <= 3600000)
315 update_proc("neigh", "base_reachable_time_ms", ntohl(adv->nd_ra_reachable));
317 if (ntohl(adv->nd_ra_retransmit) <= 60000)
318 update_proc("neigh", "retrans_time_ms", ntohl(adv->nd_ra_retransmit));
322 struct icmpv6_opt *opt;
323 icmpv6_for_each_option(opt, &adv[1], &buf[len]) {
324 if (opt->type == ND_OPT_MTU) {
325 uint32_t *mtu = (uint32_t*)&opt->data[2];
326 if (ntohl(*mtu) >= 1280 && ntohl(*mtu) <= 65535)
327 update_proc("conf", "mtu", ntohl(*mtu));
328 } else if (opt->type == ND_OPT_ROUTE_INFORMATION && opt->len <= 3) {
329 entry.router = from.sin6_addr;
331 entry.priority = pref_to_priority(opt->data[1]);
332 entry.length = opt->data[0];
333 uint32_t *valid = (uint32_t*)&opt->data[2];
334 entry.valid = ntohl(*valid);
335 memcpy(&entry.target, &opt->data[6], (opt->len - 1) * 8);
337 if (entry.length > 128 || IN6_IS_ADDR_LINKLOCAL(&entry.target)
338 || IN6_IS_ADDR_LOOPBACK(&entry.target)
339 || IN6_IS_ADDR_MULTICAST(&entry.target))
342 if (entry.priority > 0)
343 changed |= odhcp6c_update_entry(STATE_RA_ROUTE, &entry);
344 } else if (opt->type == ND_OPT_PREFIX_INFORMATION && opt->len == 4) {
345 struct nd_opt_prefix_info *pinfo = (struct nd_opt_prefix_info*)opt;
347 entry.target = pinfo->nd_opt_pi_prefix;
348 entry.priority = 256;
349 entry.length = pinfo->nd_opt_pi_prefix_len;
350 entry.valid = ntohl(pinfo->nd_opt_pi_valid_time);
351 entry.preferred = ntohl(pinfo->nd_opt_pi_preferred_time);
353 if (entry.length > 128 || IN6_IS_ADDR_LINKLOCAL(&entry.target)
354 || IN6_IS_ADDR_LOOPBACK(&entry.target)
355 || IN6_IS_ADDR_MULTICAST(&entry.target)
356 || entry.valid < entry.preferred)
359 if (pinfo->nd_opt_pi_flags_reserved & ND_OPT_PI_FLAG_ONLINK)
360 changed |= odhcp6c_update_entry_safe(STATE_RA_ROUTE, &entry, 7200);
362 if (!(pinfo->nd_opt_pi_flags_reserved & ND_OPT_PI_FLAG_AUTO) ||
363 pinfo->nd_opt_pi_prefix_len != 64)
366 entry.target.s6_addr32[2] = lladdr.s6_addr32[2];
367 entry.target.s6_addr32[3] = lladdr.s6_addr32[3];
369 changed |= odhcp6c_update_entry_safe(STATE_RA_PREFIX, &entry, 7200);
370 } else if (opt->type == ND_OPT_RECURSIVE_DNS && opt->len > 2) {
371 entry.router = from.sin6_addr;
374 uint32_t *valid = (uint32_t*)&opt->data[2];
375 entry.valid = ntohl(*valid);
378 for (ssize_t i = 0; i < (opt->len - 1) / 2; ++i) {
379 memcpy(&entry.target, &opt->data[6 + i * sizeof(entry.target)],
380 sizeof(entry.target));
381 changed |= odhcp6c_update_entry(STATE_RA_DNS, &entry);
387 struct odhcp6c_entry *entry = odhcp6c_get_state(STATE_RA_DNS, &ra_dns_len);
388 for (size_t i = 0; i < ra_dns_len / sizeof(*entry); ++i)
389 if (IN6_ARE_ADDR_EQUAL(&entry[i].router, &from.sin6_addr) &&
390 entry[i].valid > router_valid)
391 entry[i].valid = router_valid;
397 return found && changed;