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);
62 if_index = if_nametoindex(ifname);
63 strncpy(if_name, ifname, sizeof(if_name) - 1);
66 rtnl = socket(AF_NETLINK, SOCK_DGRAM | SOCK_CLOEXEC, NETLINK_ROUTE);
67 struct sockaddr_nl rtnl_kernel = { .nl_family = AF_NETLINK };
68 connect(rtnl, (const struct sockaddr*)&rtnl_kernel, sizeof(rtnl_kernel));
70 int val = RTNLGRP_LINK;
71 setsockopt(rtnl, SOL_NETLINK, NETLINK_ADD_MEMBERSHIP, &val, sizeof(val));
72 fcntl(rtnl, F_SETOWN, ourpid);
73 fcntl(rtnl, F_SETFL, fcntl(sock, F_GETFL) | O_ASYNC);
79 .hdr = {sizeof(req), RTM_GETLINK, NLM_F_REQUEST, 1, 0},
80 .ifi = {.ifi_index = if_index}
82 send(rtnl, &req, sizeof(req), 0);
84 // Filter ICMPv6 package types
85 struct icmp6_filter filt;
86 ICMP6_FILTER_SETBLOCKALL(&filt);
87 ICMP6_FILTER_SETPASS(ND_ROUTER_ADVERT, &filt);
88 setsockopt(sock, IPPROTO_ICMPV6, ICMP6_FILTER, &filt, sizeof(filt));
91 struct ipv6_mreq an = {ALL_IPV6_NODES, if_index};
92 setsockopt(sock, IPPROTO_IPV6, IPV6_ADD_MEMBERSHIP, &an, sizeof(an));
94 // Let the kernel compute our checksums
96 setsockopt(sock, IPPROTO_RAW, IPV6_CHECKSUM, &val, sizeof(val));
98 // This is required by RFC 4861
100 setsockopt(sock, IPPROTO_IPV6, IPV6_MULTICAST_HOPS, &val, sizeof(val));
102 // Receive multicast hops
104 setsockopt(sock, IPPROTO_IPV6, IPV6_RECVHOPLIMIT, &val, sizeof(val));
106 // Bind to one device
107 setsockopt(sock, SOL_SOCKET, SO_BINDTODEVICE, ifname, strlen(ifname));
110 fcntl(sock, F_SETOWN, ourpid);
111 fcntl(sock, F_SETFL, fcntl(sock, F_GETFL) | O_ASYNC);
114 signal(SIGALRM, ra_send_rs);
121 static void ra_send_rs(int signal __attribute__((unused)))
123 const struct icmp6_hdr rs = {ND_ROUTER_SOLICIT, 0, 0, {{0}}};
124 const struct sockaddr_in6 dest = {AF_INET6, 0, 0, ALL_IPV6_ROUTERS, if_index};
125 sendto(sock, &rs, sizeof(rs), MSG_DONTWAIT, (struct sockaddr*)&dest, sizeof(dest));
127 if (++rs_attempt <= 3)
132 static int16_t pref_to_priority(uint8_t flags)
134 flags = (flags >> 3) & 0x03;
135 return (flags == 0x0) ? 1024 : (flags == 0x1) ? 512 :
136 (flags == 0x3) ? 2048 : -1;
140 static void update_proc(const char *sect, const char *opt, uint32_t value)
143 snprintf(buf, sizeof(buf), "/proc/sys/net/ipv6/%s/%s/%s", sect, if_name, opt);
145 int fd = open(buf, O_WRONLY);
146 write(fd, buf, snprintf(buf, sizeof(buf), "%u", value));
151 bool ra_link_up(void)
155 struct ifinfomsg msg;
163 read = recv(rtnl, &resp, sizeof(resp), MSG_DONTWAIT);
164 if (!NLMSG_OK(&resp.hdr, read) || resp.hdr.nlmsg_type != RTM_NEWLINK ||
165 resp.msg.ifi_index != if_index)
168 bool hascarrier = resp.msg.ifi_flags & IFF_LOWER_UP;
169 if (nocarrier && hascarrier)
172 nocarrier = !hascarrier;
176 syslog(LOG_NOTICE, "carrier up event on %s", if_name);
184 bool ra_process(void)
187 bool changed = false;
188 uint8_t buf[1500], cmsg_buf[128];
189 struct nd_router_advert *adv = (struct nd_router_advert*)buf;
190 struct odhcp6c_entry entry = {IN6ADDR_ANY_INIT, 0, 0, IN6ADDR_ANY_INIT, 0, 0, 0, 0, 0};
191 const struct in6_addr any = IN6ADDR_ANY_INIT;
193 if (IN6_IS_ADDR_UNSPECIFIED(&lladdr)) {
194 // Autodetect interface-id if not specified
195 FILE *fp = fopen("/proc/net/if_inet6", "r");
197 char addrbuf[33], ifbuf[16];
198 while (fscanf(fp, "%32s %*x %*x %*x %*x %15s", addrbuf, ifbuf) == 2) {
199 if (!strcmp(ifbuf, if_name)) {
200 script_unhexlify((uint8_t*)&lladdr, sizeof(lladdr), addrbuf);
209 struct sockaddr_in6 from;
210 struct iovec iov = {buf, sizeof(buf)};
211 struct msghdr msg = {&from, sizeof(from), &iov, 1,
212 cmsg_buf, sizeof(cmsg_buf), 0};
214 ssize_t len = recvmsg(sock, &msg, MSG_DONTWAIT);
217 else if (len < (ssize_t)sizeof(*adv))
221 for (struct cmsghdr *ch = CMSG_FIRSTHDR(&msg); ch != NULL;
222 ch = CMSG_NXTHDR(&msg, ch))
223 if (ch->cmsg_level == IPPROTO_IPV6 &&
224 ch->cmsg_type == IPV6_HOPLIMIT)
225 memcpy(&hlim, CMSG_DATA(ch), sizeof(hlim));
230 // Stop sending solicits
231 if (rs_attempt > 0) {
240 uint32_t router_valid = ntohs(adv->nd_ra_router_lifetime);
242 // Parse default route
245 entry.router = from.sin6_addr;
246 entry.priority = pref_to_priority(adv->nd_ra_flags_reserved);
247 if (entry.priority < 0)
248 entry.priority = pref_to_priority(0);
249 entry.valid = router_valid;
250 entry.preferred = entry.valid;
251 changed |= odhcp6c_update_entry(STATE_RA_ROUTE, &entry);
253 // Parse ND parameters
254 if (ntohl(adv->nd_ra_reachable) <= 3600000)
255 update_proc("neigh", "base_reachable_time_ms", ntohl(adv->nd_ra_reachable));
257 if (ntohl(adv->nd_ra_retransmit) <= 60000)
258 update_proc("neigh", "retrans_time_ms", ntohl(adv->nd_ra_retransmit));
262 struct icmpv6_opt *opt;
263 icmpv6_for_each_option(opt, &adv[1], &buf[len]) {
264 if (opt->type == ND_OPT_MTU) {
265 uint32_t *mtu = (uint32_t*)&opt->data[2];
266 if (ntohl(*mtu) >= 1280 && ntohl(*mtu) <= 65535)
267 update_proc("conf", "mtu", ntohl(*mtu));
268 } else if (opt->type == ND_OPT_ROUTE_INFORMATION && opt->len <= 3) {
269 entry.router = from.sin6_addr;
271 entry.priority = pref_to_priority(opt->data[1]);
272 entry.length = opt->data[0];
273 uint32_t *valid = (uint32_t*)&opt->data[2];
274 entry.valid = ntohl(*valid);
275 memcpy(&entry.target, &opt->data[6], (opt->len - 1) * 8);
277 if (entry.length > 128 || IN6_IS_ADDR_LINKLOCAL(&entry.target)
278 || IN6_IS_ADDR_LOOPBACK(&entry.target)
279 || IN6_IS_ADDR_MULTICAST(&entry.target))
282 if (entry.priority > 0)
283 changed |= odhcp6c_update_entry(STATE_RA_ROUTE, &entry);
284 } else if (opt->type == ND_OPT_PREFIX_INFORMATION && opt->len == 4) {
285 struct nd_opt_prefix_info *pinfo = (struct nd_opt_prefix_info*)opt;
287 entry.target = pinfo->nd_opt_pi_prefix;
288 entry.priority = 256;
289 entry.length = pinfo->nd_opt_pi_prefix_len;
290 entry.valid = ntohl(pinfo->nd_opt_pi_valid_time);
291 entry.preferred = ntohl(pinfo->nd_opt_pi_preferred_time);
293 if (entry.length > 128 || IN6_IS_ADDR_LINKLOCAL(&entry.target)
294 || IN6_IS_ADDR_LOOPBACK(&entry.target)
295 || IN6_IS_ADDR_MULTICAST(&entry.target)
296 || entry.valid < entry.preferred)
299 if (pinfo->nd_opt_pi_flags_reserved & ND_OPT_PI_FLAG_ONLINK)
300 changed |= odhcp6c_update_entry_safe(STATE_RA_ROUTE, &entry, 7200);
302 if (!(pinfo->nd_opt_pi_flags_reserved & ND_OPT_PI_FLAG_AUTO) ||
303 pinfo->nd_opt_pi_prefix_len != 64)
306 entry.target.s6_addr32[2] = lladdr.s6_addr32[2];
307 entry.target.s6_addr32[3] = lladdr.s6_addr32[3];
309 changed |= odhcp6c_update_entry_safe(STATE_RA_PREFIX, &entry, 7200);
310 } else if (opt->type == ND_OPT_RECURSIVE_DNS && opt->len > 2) {
311 entry.router = from.sin6_addr;
314 uint32_t *valid = (uint32_t*)&opt->data[2];
315 entry.valid = ntohl(*valid);
318 for (ssize_t i = 0; i < (opt->len - 1) / 2; ++i) {
319 memcpy(&entry.target, &opt->data[6 + i * sizeof(entry.target)],
320 sizeof(entry.target));
321 changed |= odhcp6c_update_entry(STATE_RA_DNS, &entry);
327 struct odhcp6c_entry *entry = odhcp6c_get_state(STATE_RA_DNS, &ra_dns_len);
328 for (size_t i = 0; i < ra_dns_len / sizeof(*entry); ++i)
329 if (IN6_ARE_ADDR_EQUAL(&entry[i].router, &from.sin6_addr) &&
330 entry[i].valid > router_valid)
331 entry[i].valid = router_valid;
337 return found && changed;