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>
37 static int sock = -1, rtnl_sock = -1;
38 static unsigned if_index = 0;
39 static char if_name[IF_NAMESIZE] = {0};
40 static volatile int rs_attempt = 0;
41 static struct in6_addr lladdr = IN6ADDR_ANY_INIT;
43 static void ra_send_rs(int signal __attribute__((unused)));
45 int ra_init(const char *ifname)
47 sock = socket(AF_INET6, SOCK_RAW | SOCK_CLOEXEC, IPPROTO_ICMPV6);
48 if_index = if_nametoindex(ifname);
49 strncpy(if_name, ifname, sizeof(if_name) - 1);
51 // Filter ICMPv6 package types
52 struct icmp6_filter filt;
53 ICMP6_FILTER_SETBLOCKALL(&filt);
54 ICMP6_FILTER_SETPASS(ND_ROUTER_ADVERT, &filt);
55 setsockopt(sock, IPPROTO_ICMPV6, ICMP6_FILTER, &filt, sizeof(filt));
58 struct ipv6_mreq an = {ALL_IPV6_NODES, if_index};
59 setsockopt(sock, IPPROTO_IPV6, IPV6_ADD_MEMBERSHIP, &an, sizeof(an));
61 // Let the kernel compute our checksums
63 setsockopt(sock, IPPROTO_RAW, IPV6_CHECKSUM, &val, sizeof(val));
65 // This is required by RFC 4861
67 setsockopt(sock, IPPROTO_IPV6, IPV6_MULTICAST_HOPS, &val, sizeof(val));
70 setsockopt(sock, SOL_SOCKET, SO_BINDTODEVICE, ifname, strlen(ifname));
73 const pid_t ourpid = getpid();
74 fcntl(sock, F_SETOWN, ourpid);
75 fcntl(sock, F_SETFL, fcntl(sock, F_GETFL) | O_ASYNC);
78 FILE *fp = fopen("/proc/net/if_inet6", "r");
80 char addrbuf[33], ifbuf[16];
81 while (fscanf(fp, "%32s %*x %*x %*x %*x %15s", addrbuf, ifbuf) == 2) {
82 if (!strcmp(ifbuf, if_name)) {
83 script_unhexlify((uint8_t*)&lladdr, sizeof(lladdr), addrbuf);
90 // Open rtnetlink socket
91 rtnl_sock = socket(AF_NETLINK, SOCK_RAW | SOCK_CLOEXEC, NETLINK_ROUTE);
92 struct sockaddr_nl rtnl_kernel = { .nl_family = AF_NETLINK };
93 if (connect(rtnl_sock, (struct sockaddr*)&rtnl_kernel, sizeof(rtnl_kernel)))
95 uint32_t group = RTNLGRP_IPV6_IFADDR;
96 setsockopt(rtnl_sock, SOL_NETLINK, NETLINK_ADD_MEMBERSHIP, &group, sizeof(group));
99 fcntl(rtnl_sock, F_SETOWN, ourpid);
100 fcntl(rtnl_sock, F_SETFL, fcntl(rtnl_sock, F_GETFL) | O_ASYNC);
103 signal(SIGALRM, ra_send_rs);
110 static void ra_send_rs(int signal __attribute__((unused)))
112 const struct icmp6_hdr rs = {ND_ROUTER_SOLICIT, 0, 0, {{0}}};
113 const struct sockaddr_in6 dest = {AF_INET6, 0, 0, ALL_IPV6_ROUTERS, if_index};
114 sendto(sock, &rs, sizeof(rs), MSG_DONTWAIT, (struct sockaddr*)&dest, sizeof(dest));
116 if (++rs_attempt <= 3)
121 static int16_t pref_to_priority(uint8_t flags)
123 flags = (flags >> 3) & 0x03;
124 return (flags == 0x0) ? 1024 : (flags == 0x1) ? 512 :
125 (flags == 0x3) ? 2048 : -1;
129 static void update_proc(const char *sect, const char *opt, uint32_t value)
132 snprintf(buf, sizeof(buf), "/proc/sys/net/ipv6/%s/%s/%s", sect, if_name, opt);
134 int fd = open(buf, O_WRONLY);
135 write(fd, buf, snprintf(buf, sizeof(buf), "%u", value));
140 static bool ra_deduplicate(const struct in6_addr *any, uint8_t length)
142 struct odhcp6c_entry entry = {IN6ADDR_ANY_INIT, length, 0, *any, 0, 0};
143 struct odhcp6c_entry *x = odhcp6c_find_entry(STATE_RA_PREFIX, &entry);
144 if (x && IN6_ARE_ADDR_EQUAL(&x->target, any)) {
145 odhcp6c_random(&x->target.s6_addr32[2], 2 * sizeof(uint32_t));
146 } else if (odhcp6c_find_entry(STATE_IA_NA, &entry)) {
147 dhcpv6_request(DHCPV6_MSG_DECLINE);
155 bool ra_rtnl_process(void)
158 uint32_t elapsed = odhcp6c_elapsed();
161 ssize_t len = recv(rtnl_sock, buf, sizeof(buf), MSG_DONTWAIT);
168 for (struct nlmsghdr *nh = (struct nlmsghdr*)buf; NLMSG_OK(nh, (size_t)len);
169 nh = NLMSG_NEXT(nh, len)) {
170 struct ifaddrmsg *ifa = NLMSG_DATA(nh);
171 struct in6_addr *addr = NULL;
172 if (NLMSG_PAYLOAD(nh, 0) < sizeof(*ifa) || ifa->ifa_index != if_index ||
173 (nh->nlmsg_type == RTM_NEWADDR && !(ifa->ifa_flags & IFA_F_DADFAILED)) ||
174 (nh->nlmsg_type == RTM_DELADDR && !(ifa->ifa_flags & IFA_F_TENTATIVE)) ||
175 (nh->nlmsg_type != RTM_NEWADDR && nh->nlmsg_type != RTM_DELADDR))
178 ssize_t alen = NLMSG_PAYLOAD(nh, sizeof(*ifa));
179 for (struct rtattr *rta = (struct rtattr*)&ifa[1]; RTA_OK(rta, alen);
180 rta = RTA_NEXT(rta, alen))
181 if (rta->rta_type == IFA_ADDRESS && RTA_PAYLOAD(rta) >= sizeof(*addr))
182 addr = RTA_DATA(rta);
185 char ipbuf[INET6_ADDRSTRLEN];
186 inet_ntop(AF_INET6, addr, ipbuf, sizeof(ipbuf));
187 syslog(LOG_WARNING, "duplicate address detected: %s (code: %u:%x)",
188 ipbuf, (unsigned)nh->nlmsg_type, (unsigned)ifa->ifa_flags);
189 found |= ra_deduplicate(addr, ifa->ifa_prefixlen);
197 bool ra_process(void)
201 struct nd_router_advert *adv = (struct nd_router_advert*)buf;
202 struct odhcp6c_entry entry = {IN6ADDR_ANY_INIT, 0, 0, IN6ADDR_ANY_INIT, 0, 0};
203 const struct in6_addr any = IN6ADDR_ANY_INIT;
206 struct sockaddr_in6 from;
207 socklen_t from_len = sizeof(from);
208 ssize_t len = recvfrom(sock, buf, sizeof(buf), MSG_DONTWAIT, &from, &from_len);
211 else if (len < (ssize_t)sizeof(*adv))
214 // Stop sending solicits
215 if (rs_attempt > 0) {
224 uint32_t router_valid = ntohs(adv->nd_ra_router_lifetime);
226 // Parse default route
229 entry.router = from.sin6_addr;
230 entry.priority = pref_to_priority(adv->nd_ra_flags_reserved);
231 if (entry.priority < 0)
232 entry.priority = pref_to_priority(0);
233 entry.valid = router_valid;
234 entry.preferred = entry.valid;
235 odhcp6c_update_entry(STATE_RA_ROUTE, &entry);
237 // Parse ND parameters
238 if (ntohl(adv->nd_ra_reachable) <= 3600000)
239 update_proc("neigh", "base_reachable_time_ms", ntohl(adv->nd_ra_reachable));
241 if (ntohl(adv->nd_ra_retransmit) <= 60000)
242 update_proc("neigh", "retrans_time_ms", ntohl(adv->nd_ra_retransmit));
246 struct icmpv6_opt *opt;
247 icmpv6_for_each_option(opt, &adv[1], &buf[len]) {
248 if (opt->type == ND_OPT_MTU) {
249 uint32_t *mtu = (uint32_t*)&opt->data[2];
250 if (ntohl(*mtu) >= 1280 && ntohl(*mtu) <= 65535)
251 update_proc("conf", "mtu", ntohl(*mtu));
252 } else if (opt->type == ND_OPT_ROUTE_INFORMATION && opt->len <= 3) {
253 entry.router = from.sin6_addr;
255 entry.priority = pref_to_priority(opt->data[1]);
256 entry.length = opt->data[0];
257 uint32_t *valid = (uint32_t*)&opt->data[2];
258 entry.valid = ntohl(*valid);
259 memcpy(&entry.target, &opt->data[6], (opt->len - 1) * 8);
261 if (entry.length > 128 || IN6_IS_ADDR_LINKLOCAL(&entry.target)
262 || IN6_IS_ADDR_LOOPBACK(&entry.target)
263 || IN6_IS_ADDR_MULTICAST(&entry.target))
266 if (entry.priority > 0)
267 odhcp6c_update_entry(STATE_RA_ROUTE, &entry);
268 } else if (opt->type == ND_OPT_PREFIX_INFORMATION && opt->len == 4) {
269 struct nd_opt_prefix_info *pinfo = (struct nd_opt_prefix_info*)opt;
271 entry.target = pinfo->nd_opt_pi_prefix;
272 entry.priority = 256;
273 entry.length = pinfo->nd_opt_pi_prefix_len;
274 entry.valid = ntohl(pinfo->nd_opt_pi_valid_time);
275 entry.preferred = ntohl(pinfo->nd_opt_pi_preferred_time);
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)
280 || entry.valid < entry.preferred)
283 if (pinfo->nd_opt_pi_flags_reserved & ND_OPT_PI_FLAG_ONLINK)
284 odhcp6c_update_entry_safe(STATE_RA_ROUTE, &entry, 7200);
286 if (!(pinfo->nd_opt_pi_flags_reserved & ND_OPT_PI_FLAG_AUTO) ||
287 pinfo->nd_opt_pi_prefix_len != 64)
290 entry.target.s6_addr32[2] = lladdr.s6_addr32[2];
291 entry.target.s6_addr32[3] = lladdr.s6_addr32[3];
293 odhcp6c_update_entry_safe(STATE_RA_PREFIX, &entry, 7200);
294 } else if (opt->type == ND_OPT_RECURSIVE_DNS && opt->len > 2) {
295 entry.router = from.sin6_addr;
298 uint32_t *valid = (uint32_t*)&opt->data[2];
299 entry.valid = ntohl(*valid);
302 for (ssize_t i = 0; i < (opt->len - 1) / 2; ++i) {
303 memcpy(&entry.target, &opt->data[6 + i * sizeof(entry.target)],
304 sizeof(entry.target));
305 odhcp6c_update_entry(STATE_RA_DNS, &entry);
311 struct odhcp6c_entry *entry = odhcp6c_get_state(STATE_RA_DNS, &ra_dns_len);
312 for (size_t i = 0; i < ra_dns_len / sizeof(*entry); ++i)
313 if (IN6_ARE_ADDR_EQUAL(&entry[i].router, &from.sin6_addr) &&
314 entry[i].valid > router_valid)
315 entry[i].valid = router_valid;