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.
25 #include <arpa/inet.h>
26 #include <sys/socket.h>
27 #include <netinet/in.h>
28 #include <netinet/icmp6.h>
30 #include <linux/rtnetlink.h>
33 #define SOL_NETLINK 270
36 #ifndef NETLINK_ADD_MEMBERSHIP
37 #define NETLINK_ADD_MEMBERSHIP 1
41 #define IFF_LOWER_UP 0x10000
48 static bool nocarrier = false;
50 static int sock = -1, rtnl = -1;
51 static int if_index = 0;
52 static char if_name[IF_NAMESIZE] = {0};
53 static volatile int rs_attempt = 0;
54 static struct in6_addr lladdr = IN6ADDR_ANY_INIT;
56 static void ra_send_rs(int signal __attribute__((unused)));
58 int ra_init(const char *ifname, const struct in6_addr *ifid)
60 const pid_t ourpid = getpid();
61 sock = socket(AF_INET6, SOCK_RAW | SOCK_CLOEXEC, IPPROTO_ICMPV6);
65 if_index = if_nametoindex(ifname);
69 strncpy(if_name, ifname, sizeof(if_name) - 1);
72 rtnl = socket(AF_NETLINK, SOCK_DGRAM | SOCK_CLOEXEC, NETLINK_ROUTE);
76 struct sockaddr_nl rtnl_kernel = { .nl_family = AF_NETLINK };
77 if (connect(rtnl, (const struct sockaddr*)&rtnl_kernel, sizeof(rtnl_kernel)) < 0)
80 int val = RTNLGRP_LINK;
81 setsockopt(rtnl, SOL_NETLINK, NETLINK_ADD_MEMBERSHIP, &val, sizeof(val));
82 fcntl(rtnl, F_SETOWN, ourpid);
83 fcntl(rtnl, F_SETFL, fcntl(sock, F_GETFL) | O_ASYNC);
89 .hdr = {sizeof(req), RTM_GETLINK, NLM_F_REQUEST, 1, 0},
90 .ifi = {.ifi_index = if_index}
92 send(rtnl, &req, sizeof(req), 0);
94 // Filter ICMPv6 package types
95 struct icmp6_filter filt;
96 ICMP6_FILTER_SETBLOCKALL(&filt);
97 ICMP6_FILTER_SETPASS(ND_ROUTER_ADVERT, &filt);
98 setsockopt(sock, IPPROTO_ICMPV6, ICMP6_FILTER, &filt, sizeof(filt));
101 struct ipv6_mreq an = {ALL_IPV6_NODES, if_index};
102 setsockopt(sock, IPPROTO_IPV6, IPV6_ADD_MEMBERSHIP, &an, sizeof(an));
104 // Let the kernel compute our checksums
106 setsockopt(sock, IPPROTO_RAW, IPV6_CHECKSUM, &val, sizeof(val));
108 // This is required by RFC 4861
110 setsockopt(sock, IPPROTO_IPV6, IPV6_MULTICAST_HOPS, &val, sizeof(val));
112 // Receive multicast hops
114 setsockopt(sock, IPPROTO_IPV6, IPV6_RECVHOPLIMIT, &val, sizeof(val));
116 // Bind to one device
117 setsockopt(sock, SOL_SOCKET, SO_BINDTODEVICE, ifname, strlen(ifname));
120 fcntl(sock, F_SETOWN, ourpid);
121 fcntl(sock, F_SETFL, fcntl(sock, F_GETFL) | O_ASYNC);
124 signal(SIGALRM, ra_send_rs);
131 static void ra_send_rs(int signal __attribute__((unused)))
133 const struct icmp6_hdr rs = {ND_ROUTER_SOLICIT, 0, 0, {{0}}};
134 const struct sockaddr_in6 dest = {AF_INET6, 0, 0, ALL_IPV6_ROUTERS, if_index};
135 sendto(sock, &rs, sizeof(rs), MSG_DONTWAIT, (struct sockaddr*)&dest, sizeof(dest));
137 if (++rs_attempt <= 3)
142 static int16_t pref_to_priority(uint8_t flags)
144 flags = (flags >> 3) & 0x03;
145 return (flags == 0x0) ? 1024 : (flags == 0x1) ? 512 :
146 (flags == 0x3) ? 2048 : -1;
150 static void update_proc(const char *sect, const char *opt, uint32_t value)
153 snprintf(buf, sizeof(buf), "/proc/sys/net/ipv6/%s/%s/%s", sect, if_name, opt);
155 int fd = open(buf, O_WRONLY);
156 write(fd, buf, snprintf(buf, sizeof(buf), "%u", value));
161 bool ra_link_up(void)
163 static bool firstcall = true;
166 struct ifinfomsg msg;
174 read = recv(rtnl, &resp, sizeof(resp), MSG_DONTWAIT);
175 if (read < 0 || !NLMSG_OK(&resp.hdr, (size_t)read) ||
176 resp.hdr.nlmsg_type != RTM_NEWLINK ||
177 resp.msg.ifi_index != if_index)
180 bool hascarrier = resp.msg.ifi_flags & IFF_LOWER_UP;
181 if (!firstcall && nocarrier != !hascarrier)
184 nocarrier = !hascarrier;
189 syslog(LOG_NOTICE, "carrier => %i event on %s", (int)!nocarrier, if_name);
198 static int ra_icmpv6_valid(struct sockaddr_in6 *source, int hlim, uint8_t *data, size_t len)
200 struct icmp6_hdr *hdr = (struct icmp6_hdr *)data;
201 struct icmpv6_opt *opt;
207 if (len < sizeof(*hdr))
213 switch (hdr->icmp6_type) {
214 case ND_ROUTER_ADVERT:
215 if (!IN6_IS_ADDR_LINKLOCAL(&source->sin6_addr))
218 opt = (struct icmpv6_opt *)((struct nd_router_advert *)data + 1);
219 optlen = len - sizeof(struct nd_router_advert);
227 size_t l = opt->len << 3;
229 if (optlen < sizeof(*opt))
232 if (l > optlen || l == 0)
235 opt = (struct icmpv6_opt *)(((uint8_t *)opt) + l);
243 bool ra_process(void)
246 bool changed = false;
247 uint8_t buf[1500], cmsg_buf[128];
248 struct nd_router_advert *adv = (struct nd_router_advert*)buf;
249 struct odhcp6c_entry entry = {IN6ADDR_ANY_INIT, 0, 0, IN6ADDR_ANY_INIT, 0, 0, 0, 0, 0};
250 const struct in6_addr any = IN6ADDR_ANY_INIT;
252 if (IN6_IS_ADDR_UNSPECIFIED(&lladdr)) {
253 // Autodetect interface-id if not specified
254 FILE *fp = fopen("/proc/net/if_inet6", "r");
256 char addrbuf[33], ifbuf[16];
257 while (fscanf(fp, "%32s %*x %*x %*x %*x %15s", addrbuf, ifbuf) == 2) {
258 if (!strcmp(ifbuf, if_name)) {
259 script_unhexlify((uint8_t*)&lladdr, sizeof(lladdr), addrbuf);
268 struct sockaddr_in6 from;
269 struct iovec iov = {buf, sizeof(buf)};
270 struct msghdr msg = {&from, sizeof(from), &iov, 1,
271 cmsg_buf, sizeof(cmsg_buf), 0};
273 ssize_t len = recvmsg(sock, &msg, MSG_DONTWAIT);
278 for (struct cmsghdr *ch = CMSG_FIRSTHDR(&msg); ch != NULL;
279 ch = CMSG_NXTHDR(&msg, ch))
280 if (ch->cmsg_level == IPPROTO_IPV6 &&
281 ch->cmsg_type == IPV6_HOPLIMIT)
282 memcpy(&hlim, CMSG_DATA(ch), sizeof(hlim));
284 if (!ra_icmpv6_valid(&from, hlim, buf, len))
287 // Stop sending solicits
288 if (rs_attempt > 0) {
297 uint32_t router_valid = ntohs(adv->nd_ra_router_lifetime);
299 // Parse default route
302 entry.router = from.sin6_addr;
303 entry.priority = pref_to_priority(adv->nd_ra_flags_reserved);
304 if (entry.priority < 0)
305 entry.priority = pref_to_priority(0);
306 entry.valid = router_valid;
307 entry.preferred = entry.valid;
308 changed |= odhcp6c_update_entry(STATE_RA_ROUTE, &entry);
310 // Parse ND parameters
311 if (ntohl(adv->nd_ra_reachable) <= 3600000)
312 update_proc("neigh", "base_reachable_time_ms", ntohl(adv->nd_ra_reachable));
314 if (ntohl(adv->nd_ra_retransmit) <= 60000)
315 update_proc("neigh", "retrans_time_ms", ntohl(adv->nd_ra_retransmit));
319 struct icmpv6_opt *opt;
320 icmpv6_for_each_option(opt, &adv[1], &buf[len]) {
321 if (opt->type == ND_OPT_MTU) {
322 struct nd_opt_mtu *mtu = (struct nd_opt_mtu *)opt;
323 if (ntohl(mtu->nd_opt_mtu_mtu) >= 1280 && ntohl(mtu->nd_opt_mtu_mtu) <= 65535)
324 update_proc("conf", "mtu", ntohl(mtu->nd_opt_mtu_mtu));
325 } else if (opt->type == ND_OPT_ROUTE_INFORMATION && opt->len <= 3) {
326 struct nd_opt_route_info *rinfo = (struct nd_opt_route_info *)opt;
327 entry.router = from.sin6_addr;
329 entry.priority = pref_to_priority(rinfo->nd_opt_ri_prf);
330 entry.length = rinfo->nd_opt_ri_prefix_len;
331 entry.valid = ntohl(rinfo->nd_opt_ri_route_lifetime);
332 memcpy(&entry.target, &rinfo->nd_opt_ri_prefix[0], (rinfo->nd_opt_ri_len - 1) * 8);
334 if (entry.length > 128 || IN6_IS_ADDR_LINKLOCAL(&entry.target)
335 || IN6_IS_ADDR_LOOPBACK(&entry.target)
336 || IN6_IS_ADDR_MULTICAST(&entry.target))
339 if (entry.priority > 0)
340 changed |= odhcp6c_update_entry(STATE_RA_ROUTE, &entry);
341 } else if (opt->type == ND_OPT_PREFIX_INFORMATION && opt->len == 4) {
342 struct nd_opt_prefix_info *pinfo = (struct nd_opt_prefix_info *)opt;
344 entry.target = pinfo->nd_opt_pi_prefix;
345 entry.priority = 256;
346 entry.length = pinfo->nd_opt_pi_prefix_len;
347 entry.valid = ntohl(pinfo->nd_opt_pi_valid_time);
348 entry.preferred = ntohl(pinfo->nd_opt_pi_preferred_time);
350 if (entry.length > 128 || IN6_IS_ADDR_LINKLOCAL(&entry.target)
351 || IN6_IS_ADDR_LOOPBACK(&entry.target)
352 || IN6_IS_ADDR_MULTICAST(&entry.target)
353 || entry.valid < entry.preferred)
356 if (pinfo->nd_opt_pi_flags_reserved & ND_OPT_PI_FLAG_ONLINK)
357 changed |= odhcp6c_update_entry_safe(STATE_RA_ROUTE, &entry, 7200);
359 if (!(pinfo->nd_opt_pi_flags_reserved & ND_OPT_PI_FLAG_AUTO) ||
360 pinfo->nd_opt_pi_prefix_len != 64)
363 entry.target.s6_addr32[2] = lladdr.s6_addr32[2];
364 entry.target.s6_addr32[3] = lladdr.s6_addr32[3];
366 changed |= odhcp6c_update_entry_safe(STATE_RA_PREFIX, &entry, 7200);
367 } else if (opt->type == ND_OPT_RECURSIVE_DNS && opt->len > 2) {
368 struct nd_opt_recursive_dns *rdns = (struct nd_opt_recursive_dns *)opt;
369 entry.router = from.sin6_addr;
372 entry.valid = ntohl(rdns->lifetime);
375 for (ssize_t i = 0; i < (opt->len - 1) / 2; ++i) {
376 memcpy(&entry.target, &rdns->servers[i],
377 sizeof(entry.target));
378 changed |= odhcp6c_update_entry(STATE_RA_DNS, &entry);
384 struct odhcp6c_entry *entry = odhcp6c_get_state(STATE_RA_DNS, &ra_dns_len);
385 for (size_t i = 0; i < ra_dns_len / sizeof(*entry); ++i)
386 if (IN6_ARE_ADDR_EQUAL(&entry[i].router, &from.sin6_addr) &&
387 entry[i].valid > router_valid)
388 entry[i].valid = router_valid;
394 return found && changed;