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.
27 #include <arpa/inet.h>
28 #include <sys/socket.h>
29 #include <sys/types.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;
61 struct icmpv6_opt lladdr;
63 .hdr = {ND_ROUTER_SOLICIT, 0, 0, {{0}}},
64 .lladdr = {ND_OPT_SOURCE_LINKADDR, 1, {0}},
68 static void ra_send_rs(int signal __attribute__((unused)));
70 int ra_init(const char *ifname, const struct in6_addr *ifid)
72 const pid_t ourpid = getpid();
73 sock = socket(AF_INET6, SOCK_RAW | SOCK_CLOEXEC, IPPROTO_ICMPV6);
77 if_index = if_nametoindex(ifname);
81 strncpy(if_name, ifname, sizeof(if_name) - 1);
84 rtnl = socket(AF_NETLINK, SOCK_DGRAM | SOCK_CLOEXEC, NETLINK_ROUTE);
88 struct sockaddr_nl rtnl_kernel = { .nl_family = AF_NETLINK };
89 if (connect(rtnl, (const struct sockaddr*)&rtnl_kernel, sizeof(rtnl_kernel)) < 0)
92 int val = RTNLGRP_LINK;
93 setsockopt(rtnl, SOL_NETLINK, NETLINK_ADD_MEMBERSHIP, &val, sizeof(val));
94 fcntl(rtnl, F_SETOWN, ourpid);
95 fcntl(rtnl, F_SETFL, fcntl(sock, F_GETFL) | O_ASYNC);
101 .hdr = {sizeof(req), RTM_GETLINK, NLM_F_REQUEST, 1, 0},
102 .ifi = {.ifi_index = if_index}
104 send(rtnl, &req, sizeof(req), 0);
107 // Filter ICMPv6 package types
108 struct icmp6_filter filt;
109 ICMP6_FILTER_SETBLOCKALL(&filt);
110 ICMP6_FILTER_SETPASS(ND_ROUTER_ADVERT, &filt);
111 setsockopt(sock, IPPROTO_ICMPV6, ICMP6_FILTER, &filt, sizeof(filt));
114 struct ipv6_mreq an = {ALL_IPV6_NODES, if_index};
115 setsockopt(sock, IPPROTO_IPV6, IPV6_ADD_MEMBERSHIP, &an, sizeof(an));
117 // Let the kernel compute our checksums
119 setsockopt(sock, IPPROTO_RAW, IPV6_CHECKSUM, &val, sizeof(val));
121 // This is required by RFC 4861
123 setsockopt(sock, IPPROTO_IPV6, IPV6_MULTICAST_HOPS, &val, sizeof(val));
125 // Receive multicast hops
127 setsockopt(sock, IPPROTO_IPV6, IPV6_RECVHOPLIMIT, &val, sizeof(val));
129 // Bind to one device
130 setsockopt(sock, SOL_SOCKET, SO_BINDTODEVICE, ifname, strlen(ifname));
133 fcntl(sock, F_SETOWN, ourpid);
134 fcntl(sock, F_SETFL, fcntl(sock, F_GETFL) | O_ASYNC);
137 signal(SIGALRM, ra_send_rs);
144 static void ra_send_rs(int signal __attribute__((unused)))
146 const struct sockaddr_in6 dest = {AF_INET6, 0, 0, ALL_IPV6_ROUTERS, if_index};
147 const struct icmpv6_opt llnull = {ND_OPT_SOURCE_LINKADDR, 1, {0}};
150 if ((rs_attempt % 2 == 0) && memcmp(&rs.lladdr, &llnull, sizeof(llnull)))
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) ? 512 : (flags == 0x1) ? 384 :
166 (flags == 0x3) ? 640 : -1;
170 bool ra_link_up(void)
172 static bool firstcall = true;
175 struct ifinfomsg msg;
183 read = recv(rtnl, &resp, sizeof(resp), MSG_DONTWAIT);
184 if (read < 0 || !NLMSG_OK(&resp.hdr, (size_t)read) ||
185 resp.hdr.nlmsg_type != RTM_NEWLINK ||
186 resp.msg.ifi_index != if_index)
189 ssize_t alen = NLMSG_PAYLOAD(&resp.hdr, sizeof(resp.msg));
190 for (struct rtattr *rta = (struct rtattr*)(resp.pad);
191 RTA_OK(rta, alen); rta = RTA_NEXT(rta, alen)) {
192 if (rta->rta_type == IFLA_ADDRESS &&
193 RTA_PAYLOAD(rta) >= sizeof(rs.lladdr.data))
194 memcpy(rs.lladdr.data, RTA_DATA(rta), sizeof(rs.lladdr.data));
197 bool hascarrier = resp.msg.ifi_flags & IFF_LOWER_UP;
198 if (!firstcall && nocarrier != !hascarrier)
201 nocarrier = !hascarrier;
206 syslog(LOG_NOTICE, "carrier => %i event on %s", (int)!nocarrier, if_name);
215 static bool ra_icmpv6_valid(struct sockaddr_in6 *source, int hlim, uint8_t *data, size_t len)
217 struct icmp6_hdr *hdr = (struct icmp6_hdr*)data;
218 struct icmpv6_opt *opt, *end = (struct icmpv6_opt*)&data[len];
220 if (hlim != 255 || len < sizeof(*hdr) || hdr->icmp6_code)
223 switch (hdr->icmp6_type) {
224 case ND_ROUTER_ADVERT:
225 if (!IN6_IS_ADDR_LINKLOCAL(&source->sin6_addr))
228 opt = (struct icmpv6_opt*)((struct nd_router_advert*)data + 1);
235 icmpv6_for_each_option(opt, opt, end)
241 int ra_conf_hoplimit(int newvalue)
243 static int value = 0;
249 int ra_conf_mtu(int newvalue)
251 static int value = 0;
252 if (newvalue >= 1280 && newvalue <= 65535)
257 int ra_conf_reachable(int newvalue)
259 static int value = 0;
260 if (newvalue > 0 && newvalue <= 3600000)
265 int ra_conf_retransmit(int newvalue)
267 static int value = 0;
268 if (newvalue > 0 && newvalue <= 60000)
273 bool ra_process(void)
276 bool changed = false;
277 uint8_t buf[1500] __aligned(4);
278 uint8_t cmsg_buf[128] __aligned(__alignof__(struct cmsghdr));
279 struct nd_router_advert *adv = (struct nd_router_advert*)buf;
280 struct odhcp6c_entry *entry = alloca(sizeof(*entry) + 256);
281 const struct in6_addr any = IN6ADDR_ANY_INIT;
283 memset(entry, 0, sizeof(*entry));
285 if (IN6_IS_ADDR_UNSPECIFIED(&lladdr)) {
286 struct sockaddr_in6 addr = {AF_INET6, 0, 0, ALL_IPV6_ROUTERS, if_index};
287 socklen_t alen = sizeof(addr);
288 int sock = socket(AF_INET6, SOCK_RAW, IPPROTO_ICMPV6);
290 if (!connect(sock, (struct sockaddr*)&addr, sizeof(addr)) &&
291 !getsockname(sock, (struct sockaddr*)&addr, &alen))
292 lladdr = addr.sin6_addr;
298 struct sockaddr_in6 from;
299 struct iovec iov = {buf, sizeof(buf)};
300 struct msghdr msg = {
301 .msg_name = (void *) &from,
302 .msg_namelen = sizeof(from),
305 .msg_control = cmsg_buf,
306 .msg_controllen = sizeof(cmsg_buf),
310 ssize_t len = recvmsg(sock, &msg, MSG_DONTWAIT);
314 if (IN6_IS_ADDR_UNSPECIFIED(&lladdr))
318 for (struct cmsghdr *ch = CMSG_FIRSTHDR(&msg); ch != NULL;
319 ch = CMSG_NXTHDR(&msg, ch))
320 if (ch->cmsg_level == IPPROTO_IPV6 &&
321 ch->cmsg_type == IPV6_HOPLIMIT)
322 memcpy(&hlim, CMSG_DATA(ch), sizeof(hlim));
324 if (!ra_icmpv6_valid(&from, hlim, buf, len))
327 // Stop sending solicits
328 if (rs_attempt > 0) {
337 uint32_t router_valid = ntohs(adv->nd_ra_router_lifetime);
339 // Parse default route
342 entry->router = from.sin6_addr;
343 entry->priority = pref_to_priority(adv->nd_ra_flags_reserved);
344 if (entry->priority < 0)
345 entry->priority = pref_to_priority(0);
346 entry->valid = router_valid;
347 entry->preferred = entry->valid;
348 changed |= odhcp6c_update_entry(STATE_RA_ROUTE, entry, 0, true);
351 ra_conf_hoplimit(adv->nd_ra_curhoplimit);
353 // Parse ND parameters
354 ra_conf_reachable(ntohl(adv->nd_ra_reachable));
355 ra_conf_retransmit(ntohl(adv->nd_ra_retransmit));
358 struct icmpv6_opt *opt;
359 icmpv6_for_each_option(opt, &adv[1], &buf[len]) {
360 if (opt->type == ND_OPT_MTU) {
361 uint32_t *mtu = (uint32_t*)&opt->data[2];
362 ra_conf_mtu(ntohl(*mtu));
363 } else if (opt->type == ND_OPT_ROUTE_INFORMATION && opt->len <= 3) {
364 entry->router = from.sin6_addr;
366 entry->priority = pref_to_priority(opt->data[1]);
367 entry->length = opt->data[0];
368 uint32_t *valid = (uint32_t*)&opt->data[2];
369 entry->valid = ntohl(*valid);
370 memcpy(&entry->target, &opt->data[6], (opt->len - 1) * 8);
372 if (entry->length > 128 || IN6_IS_ADDR_LINKLOCAL(&entry->target)
373 || IN6_IS_ADDR_LOOPBACK(&entry->target)
374 || IN6_IS_ADDR_MULTICAST(&entry->target))
377 if (entry->priority > 0)
378 changed |= odhcp6c_update_entry(STATE_RA_ROUTE, entry, 0, true);
379 } else if (opt->type == ND_OPT_PREFIX_INFORMATION && opt->len == 4) {
380 struct nd_opt_prefix_info *pinfo = (struct nd_opt_prefix_info*)opt;
382 entry->target = pinfo->nd_opt_pi_prefix;
383 entry->priority = 256;
384 entry->length = pinfo->nd_opt_pi_prefix_len;
385 entry->valid = ntohl(pinfo->nd_opt_pi_valid_time);
386 entry->preferred = ntohl(pinfo->nd_opt_pi_preferred_time);
388 if (entry->length > 128 || IN6_IS_ADDR_LINKLOCAL(&entry->target)
389 || IN6_IS_ADDR_LOOPBACK(&entry->target)
390 || IN6_IS_ADDR_MULTICAST(&entry->target)
391 || entry->valid < entry->preferred)
394 if (pinfo->nd_opt_pi_flags_reserved & ND_OPT_PI_FLAG_ONLINK)
395 changed |= odhcp6c_update_entry(STATE_RA_ROUTE, entry, 7200, true);
397 if (!(pinfo->nd_opt_pi_flags_reserved & ND_OPT_PI_FLAG_AUTO) ||
398 pinfo->nd_opt_pi_prefix_len != 64)
401 entry->target.s6_addr32[2] = lladdr.s6_addr32[2];
402 entry->target.s6_addr32[3] = lladdr.s6_addr32[3];
404 changed |= odhcp6c_update_entry(STATE_RA_PREFIX, entry, 7200, true);
405 } else if (opt->type == ND_OPT_RECURSIVE_DNS && opt->len > 2) {
406 entry->router = from.sin6_addr;
409 uint32_t *valid = (uint32_t*)&opt->data[2];
410 entry->valid = ntohl(*valid);
411 entry->preferred = 0;
413 for (ssize_t i = 0; i < (opt->len - 1) / 2; ++i) {
414 memcpy(&entry->target, &opt->data[6 + i * sizeof(entry->target)],
415 sizeof(entry->target));
416 changed |= odhcp6c_update_entry(STATE_RA_DNS, entry, 0, true);
418 } else if (opt->type == ND_OPT_DNSSL && opt->len > 1) {
419 uint32_t *valid = (uint32_t*)&opt->data[2];
420 uint8_t *buf = &opt->data[6];
421 uint8_t *end = &buf[(opt->len - 1) * 8];
423 entry->router = from.sin6_addr;
424 entry->valid = ntohl(*valid);
427 int len = dn_expand(buf, end, buf, (char*)entry->auxtarget, 256);
432 entry->auxlen = strlen((char*)entry->auxtarget);
434 if (entry->auxlen == 0)
437 changed |= odhcp6c_update_entry(STATE_RA_SEARCH, entry, 0, true);
443 int states[2] = {STATE_RA_DNS, STATE_RA_SEARCH};
444 for (size_t i = 0; i < 2; ++i) {
446 uint8_t *start = odhcp6c_get_state(states[i], &ra_dns_len);
447 for (struct odhcp6c_entry *c = (struct odhcp6c_entry*)start;
448 (uint8_t*)c < &start[ra_dns_len] &&
449 (uint8_t*)odhcp6c_next_entry(c) <= &start[ra_dns_len];
450 c = odhcp6c_next_entry(c))
451 if (IN6_ARE_ADDR_EQUAL(&c->router, &from.sin6_addr) &&
452 c->valid > router_valid)
453 c->valid = router_valid;
460 return found && changed;