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, 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
;