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>
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, const struct in6_addr *ifid)
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);
52 // Filter ICMPv6 package types
53 struct icmp6_filter filt;
54 ICMP6_FILTER_SETBLOCKALL(&filt);
55 ICMP6_FILTER_SETPASS(ND_ROUTER_ADVERT, &filt);
56 setsockopt(sock, IPPROTO_ICMPV6, ICMP6_FILTER, &filt, sizeof(filt));
59 struct ipv6_mreq an = {ALL_IPV6_NODES, if_index};
60 setsockopt(sock, IPPROTO_IPV6, IPV6_ADD_MEMBERSHIP, &an, sizeof(an));
62 // Let the kernel compute our checksums
64 setsockopt(sock, IPPROTO_RAW, IPV6_CHECKSUM, &val, sizeof(val));
66 // This is required by RFC 4861
68 setsockopt(sock, IPPROTO_IPV6, IPV6_MULTICAST_HOPS, &val, sizeof(val));
71 setsockopt(sock, SOL_SOCKET, SO_BINDTODEVICE, ifname, strlen(ifname));
74 const pid_t ourpid = getpid();
75 fcntl(sock, F_SETOWN, ourpid);
76 fcntl(sock, F_SETFL, fcntl(sock, F_GETFL) | O_ASYNC);
78 if (IN6_IS_ADDR_UNSPECIFIED(&lladdr)) {
79 // Autodetect interface-id if not specified
80 FILE *fp = fopen("/proc/net/if_inet6", "r");
82 char addrbuf[33], ifbuf[16];
83 while (fscanf(fp, "%32s %*x %*x %*x %*x %15s", addrbuf, ifbuf) == 2) {
84 if (!strcmp(ifbuf, if_name)) {
85 script_unhexlify((uint8_t*)&lladdr, sizeof(lladdr), addrbuf);
94 signal(SIGALRM, ra_send_rs);
101 static void ra_send_rs(int signal __attribute__((unused)))
103 const struct icmp6_hdr rs = {ND_ROUTER_SOLICIT, 0, 0, {{0}}};
104 const struct sockaddr_in6 dest = {AF_INET6, 0, 0, ALL_IPV6_ROUTERS, if_index};
105 sendto(sock, &rs, sizeof(rs), MSG_DONTWAIT, (struct sockaddr*)&dest, sizeof(dest));
107 if (++rs_attempt <= 3)
112 static int16_t pref_to_priority(uint8_t flags)
114 flags = (flags >> 3) & 0x03;
115 return (flags == 0x0) ? 1024 : (flags == 0x1) ? 512 :
116 (flags == 0x3) ? 2048 : -1;
120 static void update_proc(const char *sect, const char *opt, uint32_t value)
123 snprintf(buf, sizeof(buf), "/proc/sys/net/ipv6/%s/%s/%s", sect, if_name, opt);
125 int fd = open(buf, O_WRONLY);
126 write(fd, buf, snprintf(buf, sizeof(buf), "%u", value));
131 bool ra_process(void)
135 struct nd_router_advert *adv = (struct nd_router_advert*)buf;
136 struct odhcp6c_entry entry = {IN6ADDR_ANY_INIT, 0, 0, IN6ADDR_ANY_INIT, 0, 0};
137 const struct in6_addr any = IN6ADDR_ANY_INIT;
140 struct sockaddr_in6 from;
141 socklen_t from_len = sizeof(from);
142 ssize_t len = recvfrom(sock, buf, sizeof(buf), MSG_DONTWAIT, &from, &from_len);
145 else if (len < (ssize_t)sizeof(*adv))
148 // Stop sending solicits
149 if (rs_attempt > 0) {
158 uint32_t router_valid = ntohs(adv->nd_ra_router_lifetime);
160 // Parse default route
163 entry.router = from.sin6_addr;
164 entry.priority = pref_to_priority(adv->nd_ra_flags_reserved);
165 if (entry.priority < 0)
166 entry.priority = pref_to_priority(0);
167 entry.valid = router_valid;
168 entry.preferred = entry.valid;
169 odhcp6c_update_entry(STATE_RA_ROUTE, &entry);
171 // Parse ND parameters
172 if (ntohl(adv->nd_ra_reachable) <= 3600000)
173 update_proc("neigh", "base_reachable_time_ms", ntohl(adv->nd_ra_reachable));
175 if (ntohl(adv->nd_ra_retransmit) <= 60000)
176 update_proc("neigh", "retrans_time_ms", ntohl(adv->nd_ra_retransmit));
180 struct icmpv6_opt *opt;
181 icmpv6_for_each_option(opt, &adv[1], &buf[len]) {
182 if (opt->type == ND_OPT_MTU) {
183 uint32_t *mtu = (uint32_t*)&opt->data[2];
184 if (ntohl(*mtu) >= 1280 && ntohl(*mtu) <= 65535)
185 update_proc("conf", "mtu", ntohl(*mtu));
186 } else if (opt->type == ND_OPT_ROUTE_INFORMATION && opt->len <= 3) {
187 entry.router = from.sin6_addr;
189 entry.priority = pref_to_priority(opt->data[1]);
190 entry.length = opt->data[0];
191 uint32_t *valid = (uint32_t*)&opt->data[2];
192 entry.valid = ntohl(*valid);
193 memcpy(&entry.target, &opt->data[6], (opt->len - 1) * 8);
195 if (entry.length > 128 || IN6_IS_ADDR_LINKLOCAL(&entry.target)
196 || IN6_IS_ADDR_LOOPBACK(&entry.target)
197 || IN6_IS_ADDR_MULTICAST(&entry.target))
200 if (entry.priority > 0)
201 odhcp6c_update_entry(STATE_RA_ROUTE, &entry);
202 } else if (opt->type == ND_OPT_PREFIX_INFORMATION && opt->len == 4) {
203 struct nd_opt_prefix_info *pinfo = (struct nd_opt_prefix_info*)opt;
205 entry.target = pinfo->nd_opt_pi_prefix;
206 entry.priority = 256;
207 entry.length = pinfo->nd_opt_pi_prefix_len;
208 entry.valid = ntohl(pinfo->nd_opt_pi_valid_time);
209 entry.preferred = ntohl(pinfo->nd_opt_pi_preferred_time);
211 if (entry.length > 128 || IN6_IS_ADDR_LINKLOCAL(&entry.target)
212 || IN6_IS_ADDR_LOOPBACK(&entry.target)
213 || IN6_IS_ADDR_MULTICAST(&entry.target)
214 || entry.valid < entry.preferred)
217 if (pinfo->nd_opt_pi_flags_reserved & ND_OPT_PI_FLAG_ONLINK)
218 odhcp6c_update_entry_safe(STATE_RA_ROUTE, &entry, 7200);
220 if (!(pinfo->nd_opt_pi_flags_reserved & ND_OPT_PI_FLAG_AUTO) ||
221 pinfo->nd_opt_pi_prefix_len != 64)
224 entry.target.s6_addr32[2] = lladdr.s6_addr32[2];
225 entry.target.s6_addr32[3] = lladdr.s6_addr32[3];
227 odhcp6c_update_entry_safe(STATE_RA_PREFIX, &entry, 7200);
228 } else if (opt->type == ND_OPT_RECURSIVE_DNS && opt->len > 2) {
229 entry.router = from.sin6_addr;
232 uint32_t *valid = (uint32_t*)&opt->data[2];
233 entry.valid = ntohl(*valid);
236 for (ssize_t i = 0; i < (opt->len - 1) / 2; ++i) {
237 memcpy(&entry.target, &opt->data[6 + i * sizeof(entry.target)],
238 sizeof(entry.target));
239 odhcp6c_update_entry(STATE_RA_DNS, &entry);
245 struct odhcp6c_entry *entry = odhcp6c_get_state(STATE_RA_DNS, &ra_dns_len);
246 for (size_t i = 0; i < ra_dns_len / sizeof(*entry); ++i)
247 if (IN6_ARE_ADDR_EQUAL(&entry[i].router, &from.sin6_addr) &&
248 entry[i].valid > router_valid)
249 entry[i].valid = router_valid;