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.
24 #include <sys/socket.h>
25 #include <netinet/in.h>
26 #include <netinet/icmp6.h>
28 #include <linux/rtnetlink.h>
35 static int sock = -1, rtnl_sock = -1;
36 static unsigned if_index = 0;
37 static char if_name[IF_NAMESIZE] = {0};
38 static volatile int rs_attempt = 0;
39 static struct in6_addr lladdr = IN6ADDR_ANY_INIT;
41 static void ra_send_rs(int signal __attribute__((unused)));
43 int ra_init(const char *ifname)
45 sock = socket(AF_INET6, SOCK_RAW | SOCK_CLOEXEC, IPPROTO_ICMPV6);
46 if_index = if_nametoindex(ifname);
47 strncpy(if_name, ifname, sizeof(if_name) - 1);
49 // Filter ICMPv6 package types
50 struct icmp6_filter filt;
51 ICMP6_FILTER_SETBLOCKALL(&filt);
52 ICMP6_FILTER_SETPASS(ND_ROUTER_ADVERT, &filt);
53 setsockopt(sock, IPPROTO_ICMPV6, ICMP6_FILTER, &filt, sizeof(filt));
56 struct ipv6_mreq an = {ALL_IPV6_NODES, if_index};
57 setsockopt(sock, IPPROTO_IPV6, IPV6_ADD_MEMBERSHIP, &an, sizeof(an));
59 // Let the kernel compute our checksums
61 setsockopt(sock, IPPROTO_RAW, IPV6_CHECKSUM, &val, sizeof(val));
63 // This is required by RFC 4861
65 setsockopt(sock, IPPROTO_IPV6, IPV6_MULTICAST_HOPS, &val, sizeof(val));
68 setsockopt(sock, SOL_SOCKET, SO_BINDTODEVICE, ifname, strlen(ifname));
71 const pid_t ourpid = getpid();
72 fcntl(sock, F_SETOWN, ourpid);
73 fcntl(sock, F_SETFL, fcntl(sock, F_GETFL) | O_ASYNC);
76 FILE *fp = fopen("/proc/net/if_inet6", "r");
78 char addrbuf[33], ifbuf[16];
79 while (fscanf(fp, "%32s %*x %*x %*x %*x %15s", addrbuf, ifbuf) == 2) {
80 if (!strcmp(ifbuf, if_name)) {
81 script_unhexlify((uint8_t*)&lladdr, sizeof(lladdr), addrbuf);
88 // Open rtnetlink socket
89 rtnl_sock = socket(AF_NETLINK, SOCK_RAW | SOCK_CLOEXEC, NETLINK_ROUTE);
90 struct sockaddr_nl rtnl_kernel = { .nl_family = AF_NETLINK };
91 if (connect(rtnl_sock, (struct sockaddr*)&rtnl_kernel, sizeof(rtnl_kernel)))
93 uint32_t group = RTNLGRP_IPV6_IFADDR;
94 setsockopt(rtnl_sock, SOL_NETLINK, NETLINK_ADD_MEMBERSHIP, &group, sizeof(group));
97 fcntl(rtnl_sock, F_SETOWN, ourpid);
98 fcntl(rtnl_sock, F_SETFL, fcntl(rtnl_sock, F_GETFL) | O_ASYNC);
101 signal(SIGALRM, ra_send_rs);
108 static void ra_send_rs(int signal __attribute__((unused)))
110 const struct icmp6_hdr rs = {ND_ROUTER_SOLICIT, 0, 0, {{0}}};
111 const struct sockaddr_in6 dest = {AF_INET6, 0, 0, ALL_IPV6_ROUTERS, if_index};
112 sendto(sock, &rs, sizeof(rs), MSG_DONTWAIT, (struct sockaddr*)&dest, sizeof(dest));
114 if (++rs_attempt <= 3)
119 static int16_t pref_to_priority(uint8_t flags)
121 flags = (flags >> 3) & 0x03;
122 return (flags == 0x0) ? 1024 : (flags == 0x1) ? 512 :
123 (flags == 0x3) ? 2048 : -1;
127 static void update_proc(const char *sect, const char *opt, uint32_t value)
130 snprintf(buf, sizeof(buf), "/proc/sys/net/ipv6/%s/%s/%s", sect, if_name, opt);
132 int fd = open(buf, O_WRONLY);
133 write(fd, buf, snprintf(buf, sizeof(buf), "%u", value));
138 static bool ra_deduplicate(const struct in6_addr *any, uint8_t length)
140 struct odhcp6c_entry entry = {IN6ADDR_ANY_INIT, length, 0, *any, 0, 0};
141 struct odhcp6c_entry *x = odhcp6c_find_entry(STATE_RA_PREFIX, &entry);
142 if (x && IN6_ARE_ADDR_EQUAL(&x->target, any)) {
143 odhcp6c_random(&x->target.s6_addr32[2], 2 * sizeof(uint32_t));
144 } else if (odhcp6c_find_entry(STATE_IA_NA, &entry)) {
145 dhcpv6_request(DHCPV6_MSG_DECLINE);
153 bool ra_rtnl_process(void)
158 ssize_t len = recv(rtnl_sock, buf, sizeof(buf), MSG_DONTWAIT);
162 for (struct nlmsghdr *nh = (struct nlmsghdr*)buf; NLMSG_OK(nh, (size_t)len);
163 nh = NLMSG_NEXT(nh, len)) {
164 struct ifaddrmsg *ifa = NLMSG_DATA(nh);
165 struct in6_addr *addr = NULL;
166 if (NLMSG_PAYLOAD(nh, 0) < sizeof(*ifa) || ifa->ifa_index != if_index ||
167 (nh->nlmsg_type == RTM_NEWADDR && !(ifa->ifa_flags & IFA_F_DADFAILED)) ||
168 (nh->nlmsg_type == RTM_DELADDR && !(ifa->ifa_flags & IFA_F_TENTATIVE)))
171 ssize_t alen = NLMSG_PAYLOAD(nh, sizeof(*ifa));
172 for (struct rtattr *rta = (struct rtattr*)&ifa[1]; RTA_OK(rta, alen);
173 rta = RTA_NEXT(rta, alen))
174 if (rta->rta_type == IFA_ADDRESS && RTA_PAYLOAD(rta) >= sizeof(*addr))
175 addr = RTA_DATA(rta);
178 found |= ra_deduplicate(addr, ifa->ifa_prefixlen);
185 bool ra_process(void)
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};
191 const struct in6_addr any = IN6ADDR_ANY_INIT;
195 struct sockaddr_in6 from;
196 socklen_t from_len = sizeof(from);
197 ssize_t len = recvfrom(sock, buf, sizeof(buf), MSG_DONTWAIT, &from, &from_len);
200 else if (len < (ssize_t)sizeof(*adv))
203 // Stop sending solicits
204 if (rs_attempt > 0) {
210 uint32_t router_valid = ntohs(adv->nd_ra_router_lifetime);
212 // Parse default route
213 entry.router = from.sin6_addr;
214 entry.priority = pref_to_priority(adv->nd_ra_flags_reserved);
215 if (entry.priority < 0)
216 entry.priority = pref_to_priority(0);
217 entry.valid = router_valid;
218 entry.preferred = entry.valid;
219 odhcp6c_update_entry(STATE_RA_ROUTE, &entry);
221 // Parse ND parameters
222 if (adv->nd_ra_reachable)
223 update_proc("neigh", "base_reachable_time_ms", ntohl(adv->nd_ra_reachable));
225 if (adv->nd_ra_retransmit)
226 update_proc("neigh", "retrans_time_ms", ntohl(adv->nd_ra_retransmit));
230 struct icmpv6_opt *opt;
231 icmpv6_for_each_option(opt, &adv[1], &buf[len]) {
232 if (opt->type == ND_OPT_MTU) {
233 update_proc("conf", "mtu", ntohl(*((uint32_t*)&opt->data[2])));
234 } else if (opt->type == ND_OPT_ROUTE_INFORMATION && opt->len <= 3) {
235 entry.router = from.sin6_addr;
237 entry.priority = pref_to_priority(opt->data[1]);
238 entry.length = opt->data[0];
239 entry.valid = ntohl(*((uint32_t*)&opt->data[2]));
240 memcpy(&entry.target, &opt->data[6], (opt->len - 1) * 8);
242 if (entry.length > 128 || IN6_IS_ADDR_LINKLOCAL(&entry.target)
243 || IN6_IS_ADDR_LOOPBACK(&entry.target)
244 || IN6_IS_ADDR_MULTICAST(&entry.target))
247 if (entry.priority > 0)
248 odhcp6c_update_entry(STATE_RA_ROUTE, &entry);
249 } else if (opt->type == ND_OPT_PREFIX_INFORMATION && opt->len == 4) {
250 struct nd_opt_prefix_info *pinfo = (struct nd_opt_prefix_info*)opt;
252 entry.target = pinfo->nd_opt_pi_prefix;
253 entry.priority = 256;
254 entry.length = pinfo->nd_opt_pi_prefix_len;
255 entry.valid = ntohl(pinfo->nd_opt_pi_valid_time);
256 entry.preferred = ntohl(pinfo->nd_opt_pi_preferred_time);
258 if (entry.length > 128 || IN6_IS_ADDR_LINKLOCAL(&entry.target)
259 || IN6_IS_ADDR_LOOPBACK(&entry.target)
260 || IN6_IS_ADDR_MULTICAST(&entry.target)
261 || entry.valid < entry.preferred)
264 if (pinfo->nd_opt_pi_flags_reserved & ND_OPT_PI_FLAG_ONLINK)
265 odhcp6c_update_entry_safe(STATE_RA_ROUTE, &entry, 7200);
267 if (!(pinfo->nd_opt_pi_flags_reserved & ND_OPT_PI_FLAG_AUTO) ||
268 pinfo->nd_opt_pi_prefix_len != 64)
271 entry.target.s6_addr32[2] = lladdr.s6_addr32[2];
272 entry.target.s6_addr32[3] = lladdr.s6_addr32[3];
274 odhcp6c_update_entry_safe(STATE_RA_PREFIX, &entry, 7200);
275 } else if (opt->type == ND_OPT_RECURSIVE_DNS && opt->len > 2) {
276 entry.router = from.sin6_addr;
279 entry.valid = ntohl(*((uint32_t*)&opt->data[2]));
282 for (ssize_t i = 0; i < (opt->len - 1) / 2; ++i) {
283 memcpy(&entry.target, &opt->data[6 + i * sizeof(entry.target)],
284 sizeof(entry.target));
285 odhcp6c_update_entry(STATE_RA_DNS, &entry);
291 struct odhcp6c_entry *entry = odhcp6c_get_state(STATE_RA_DNS, &ra_dns_len);
292 for (size_t i = 0; i < ra_dns_len / sizeof(*entry); ++i)
293 if (IN6_ARE_ADDR_EQUAL(&entry[i].router, &from.sin6_addr) &&
294 entry[i].valid > router_valid)
295 entry[i].valid = router_valid;