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.
23 #include <arpa/inet.h>
24 #include <net/route.h>
30 static void forward_router_solicitation(const struct interface *iface);
31 static void forward_router_advertisement(uint8_t *data, size_t len);
33 static void handle_icmpv6(void *addr, void *data, size_t len,
34 struct interface *iface, void *dest);
35 static void trigger_router_advert(struct uloop_timeout *event);
36 static void sigusr1_refresh(int signal);
38 static struct odhcpd_event router_event = {.uloop = {.fd = -1}, .handle_dgram = handle_icmpv6, };
40 static FILE *fp_route = NULL;
43 #define TIME_LEFT(t1, now) ((t1) != UINT32_MAX ? (t1) - (now) : UINT32_MAX)
48 int sock = socket(AF_INET6, SOCK_RAW | SOCK_CLOEXEC, IPPROTO_ICMPV6);
49 if (sock < 0 && errno != EAFNOSUPPORT) {
50 syslog(LOG_ERR, "Failed to open RAW-socket: %s", strerror(errno));
54 // Let the kernel compute our checksums
56 setsockopt(sock, IPPROTO_RAW, IPV6_CHECKSUM, &val, sizeof(val));
58 // This is required by RFC 4861
60 setsockopt(sock, IPPROTO_IPV6, IPV6_MULTICAST_HOPS, &val, sizeof(val));
61 setsockopt(sock, IPPROTO_IPV6, IPV6_UNICAST_HOPS, &val, sizeof(val));
63 // We need to know the source interface
65 setsockopt(sock, IPPROTO_IPV6, IPV6_RECVPKTINFO, &val, sizeof(val));
66 setsockopt(sock, IPPROTO_IPV6, IPV6_RECVHOPLIMIT, &val, sizeof(val));
70 setsockopt(sock, IPPROTO_IPV6, IPV6_MULTICAST_LOOP, &val, sizeof(val));
72 // Filter ICMPv6 package types
73 struct icmp6_filter filt;
74 ICMP6_FILTER_SETBLOCKALL(&filt);
75 ICMP6_FILTER_SETPASS(ND_ROUTER_ADVERT, &filt);
76 ICMP6_FILTER_SETPASS(ND_ROUTER_SOLICIT, &filt);
77 setsockopt(sock, IPPROTO_ICMPV6, ICMP6_FILTER, &filt, sizeof(filt));
80 router_event.uloop.fd = sock;
81 odhcpd_register(&router_event);
83 if (!(fp_route = fopen("/proc/net/ipv6_route", "r")))
84 syslog(LOG_ERR, "Failed to open routing table: %s",
87 signal(SIGUSR1, sigusr1_refresh);
92 int setup_router_interface(struct interface *iface, bool enable)
94 if (!fp_route || router_event.uloop.fd < 0)
97 struct ipv6_mreq all_nodes = {ALL_IPV6_NODES, iface->ifindex};
98 struct ipv6_mreq all_routers = {ALL_IPV6_ROUTERS, iface->ifindex};
100 uloop_timeout_cancel(&iface->timer_rs);
101 iface->timer_rs.cb = NULL;
103 if (iface->ifindex <= 0)
106 setsockopt(router_event.uloop.fd, IPPROTO_IPV6, IPV6_DROP_MEMBERSHIP,
107 &all_nodes, sizeof(all_nodes));
108 setsockopt(router_event.uloop.fd, IPPROTO_IPV6, IPV6_DROP_MEMBERSHIP,
109 &all_routers, sizeof(all_routers));
113 trigger_router_advert(&iface->timer_rs);
115 void *mreq = &all_routers;
117 if (iface->ra == RELAYD_RELAY && iface->master) {
119 forward_router_solicitation(iface);
120 } else if (iface->ra == RELAYD_SERVER && !iface->master) {
121 iface->timer_rs.cb = trigger_router_advert;
122 uloop_timeout_set(&iface->timer_rs, 1000);
125 if (iface->ra == RELAYD_RELAY || (iface->ra == RELAYD_SERVER && !iface->master))
126 setsockopt(router_event.uloop.fd, IPPROTO_IPV6,
127 IPV6_ADD_MEMBERSHIP, mreq, sizeof(all_nodes));
133 // Signal handler to resend all RDs
134 static void sigusr1_refresh(_unused int signal)
136 struct interface *iface;
137 list_for_each_entry(iface, &interfaces, head)
138 if (iface->ra == RELAYD_SERVER && !iface->master)
139 uloop_timeout_set(&iface->timer_rs, 1000);
142 static bool router_icmpv6_valid(struct sockaddr_in6 *source, uint8_t *data, size_t len)
144 struct icmp6_hdr *hdr = (struct icmp6_hdr *)data;
145 struct icmpv6_opt *opt, *end = (struct icmpv6_opt*)&data[len];
147 /* Hoplimit is already checked in odhcpd_receive_packets */
148 if (len < sizeof(*hdr) || hdr->icmp6_code)
151 switch (hdr->icmp6_type) {
152 case ND_ROUTER_ADVERT:
153 if (!IN6_IS_ADDR_LINKLOCAL(&source->sin6_addr))
156 opt = (struct icmpv6_opt *)((struct nd_router_advert *)data + 1);
159 case ND_ROUTER_SOLICIT:
160 opt = (struct icmpv6_opt *)((struct nd_router_solicit *)data + 1);
167 icmpv6_for_each_option(opt, opt, end)
168 if (opt->type == ND_OPT_SOURCE_LINKADDR &&
169 IN6_IS_ADDR_UNSPECIFIED(&source->sin6_addr) &&
170 hdr->icmp6_type == ND_ROUTER_SOLICIT)
173 // Check all options parsed successfully
178 // Detect whether a default route exists, also find the source prefixes
179 static bool parse_routes(struct odhcpd_ipaddr *n, ssize_t len)
183 char line[512], ifname[16];
184 bool found_default = false;
185 struct odhcpd_ipaddr p = {IN6ADDR_ANY_INIT, 0, 0, 0, 0};
186 while (fgets(line, sizeof(line), fp_route)) {
188 if (sscanf(line, "00000000000000000000000000000000 00 "
189 "%*s %*s %*s %*s %*s %*s %*s %15s", ifname) &&
190 strcmp(ifname, "lo")) {
191 found_default = true;
192 } else if (sscanf(line, "%8" SCNx32 "%8" SCNx32 "%*8" SCNx32 "%*8" SCNx32 " %hhx %*s "
193 "%*s 00000000000000000000000000000000 %*s %*s %*s %" SCNx32 " lo",
194 &p.addr.s6_addr32[0], &p.addr.s6_addr32[1], &p.prefix, &rflags) &&
195 p.prefix > 0 && (rflags & RTF_NONEXTHOP) && (rflags & RTF_REJECT)) {
196 // Find source prefixes by scanning through unreachable-routes
197 p.addr.s6_addr32[0] = htonl(p.addr.s6_addr32[0]);
198 p.addr.s6_addr32[1] = htonl(p.addr.s6_addr32[1]);
200 for (ssize_t i = 0; i < len; ++i) {
201 if (n[i].prefix <= 64 && n[i].prefix >= p.prefix &&
202 !odhcpd_bmemcmp(&p.addr, &n[i].addr, p.prefix)) {
203 n[i].dprefix = p.prefix;
211 return found_default;
214 static int calc_adv_interval(struct interface *iface, uint32_t minvalid,
217 uint32_t minival = iface->ra_mininterval;
220 *maxival = iface->ra_maxinterval;
222 if (*maxival > minvalid/3)
223 *maxival = minvalid/3;
225 if (*maxival > MaxRtrAdvInterval)
226 *maxival = MaxRtrAdvInterval;
227 else if (*maxival < 4)
230 if (minival < MinRtrAdvInterval)
231 minival = MinRtrAdvInterval;
232 else if (minival > (*maxival * 3)/4)
233 minival = (*maxival >= 9 ? *maxival/3 : *maxival);
235 odhcpd_urandom(&msecs, sizeof(msecs));
236 msecs = (labs(msecs) % ((*maxival - minival)*1000)) + minival*1000;
241 static uint16_t calc_ra_lifetime(struct interface *iface, uint32_t maxival)
243 uint16_t lifetime = 3*maxival;
245 if (iface->ra_lifetime >= 0) {
246 lifetime = iface->ra_lifetime;
247 if (lifetime < maxival)
249 else if (lifetime > 9000)
256 // Router Advert server mode
257 static uint64_t send_router_advert(struct interface *iface, const struct in6_addr *from)
259 time_t now = odhcpd_time();
260 int mtu = odhcpd_get_interface_config(iface->ifname, "mtu");
261 int hlim = odhcpd_get_interface_config(iface->ifname, "hop_limit");
267 struct nd_router_advert h;
268 struct icmpv6_opt lladdr;
269 struct nd_opt_mtu mtu;
270 struct nd_opt_prefix_info prefix[sizeof(iface->ia_addr) / sizeof(*iface->ia_addr)];
272 .h = {{.icmp6_type = ND_ROUTER_ADVERT, .icmp6_code = 0}, 0, 0},
273 .lladdr = {ND_OPT_SOURCE_LINKADDR, 1, {0}},
274 .mtu = {ND_OPT_MTU, 1, 0, htonl(mtu)},
278 adv.h.nd_ra_curhoplimit = hlim;
281 adv.h.nd_ra_flags_reserved = ND_RA_FLAG_OTHER;
283 if (iface->managed >= RELAYD_MANAGED_MFLAG)
284 adv.h.nd_ra_flags_reserved |= ND_RA_FLAG_MANAGED;
286 if (iface->route_preference < 0)
287 adv.h.nd_ra_flags_reserved |= ND_RA_PREF_LOW;
288 else if (iface->route_preference > 0)
289 adv.h.nd_ra_flags_reserved |= ND_RA_PREF_HIGH;
290 odhcpd_get_mac(iface, adv.lladdr.data);
292 // If not currently shutting down
293 struct odhcpd_ipaddr addrs[RELAYD_MAX_ADDRS];
295 uint32_t minvalid = UINT32_MAX;
296 bool default_route = false;
297 bool valid_prefix = false;
300 if (iface->timer_rs.cb) {
301 ipcnt = iface->ia_addr_len;
302 memcpy(addrs, iface->ia_addr, ipcnt * sizeof(*addrs));
304 // Check default route
305 if (iface->default_router) {
306 default_route = true;
308 if (iface->default_router > 1)
310 } else if (parse_routes(addrs, ipcnt))
311 default_route = true;
314 // Construct Prefix Information options
317 struct in6_addr dns_pref, *dns_addr = &dns_pref;
320 odhcpd_get_linklocal_interface_address(iface->ifindex, &dns_pref);
322 for (ssize_t i = 0; i < ipcnt; ++i) {
323 struct odhcpd_ipaddr *addr = &addrs[i];
325 if (addr->prefix > 96 || addr->valid <= (uint32_t)now) {
326 char namebuf[INET6_ADDRSTRLEN];
328 inet_ntop(AF_INET6, addr, namebuf, sizeof(namebuf));
329 syslog(LOG_INFO, "Address %s (prefix %d, valid %u) not suitable as RA prefix on %s",
330 namebuf, addr->prefix, addr->valid, iface->ifname);
334 struct nd_opt_prefix_info *p = NULL;
335 for (size_t i = 0; i < cnt; ++i) {
336 if (addr->prefix == adv.prefix[i].nd_opt_pi_prefix_len &&
337 !odhcpd_bmemcmp(&adv.prefix[i].nd_opt_pi_prefix,
338 &addr->addr, addr->prefix))
343 if (cnt >= ARRAY_SIZE(adv.prefix))
346 p = &adv.prefix[cnt++];
349 if (addr->preferred > (uint32_t)now &&
350 minvalid > TIME_LEFT(addr->valid, now))
351 minvalid = TIME_LEFT(addr->valid, now);
353 if (!IN6_IS_ADDR_ULA(&addr->addr) || iface->default_router)
356 odhcpd_bmemcpy(&p->nd_opt_pi_prefix, &addr->addr,
357 (iface->ra_advrouter) ? 128 : addr->prefix);
358 p->nd_opt_pi_type = ND_OPT_PREFIX_INFORMATION;
359 p->nd_opt_pi_len = 4;
360 p->nd_opt_pi_prefix_len = (addr->prefix < 64) ? 64 : addr->prefix;
361 p->nd_opt_pi_flags_reserved = 0;
362 if (!iface->ra_not_onlink)
363 p->nd_opt_pi_flags_reserved |= ND_OPT_PI_FLAG_ONLINK;
364 if (iface->managed < RELAYD_MANAGED_NO_AFLAG && addr->prefix <= 64)
365 p->nd_opt_pi_flags_reserved |= ND_OPT_PI_FLAG_AUTO;
366 if (iface->ra_advrouter)
367 p->nd_opt_pi_flags_reserved |= ND_OPT_PI_FLAG_RADDR;
368 p->nd_opt_pi_valid_time = htonl(TIME_LEFT(addr->valid, now));
369 if (addr->preferred > (uint32_t)now)
370 p->nd_opt_pi_preferred_time = htonl(TIME_LEFT(addr->preferred, now));
371 else if (addr->valid - now < 7200)
372 p->nd_opt_pi_valid_time = 0;
375 // Calculate periodic transmit
377 int msecs = calc_adv_interval(iface, minvalid, &maxival);
381 syslog(LOG_WARNING, "A default route is present but there is no public prefix "
382 "on %s thus we don't announce a default route!", iface->ifname);
383 adv.h.nd_ra_router_lifetime = 0;
385 adv.h.nd_ra_router_lifetime = htons(calc_ra_lifetime(iface, maxival));
388 adv.h.nd_ra_router_lifetime = 0;
390 syslog(LOG_INFO, "Using a RA lifetime of %d seconds on %s", ntohs(adv.h.nd_ra_router_lifetime), iface->ifname);
393 if (iface->dns_cnt > 0) {
394 dns_addr = iface->dns;
395 dns_cnt = iface->dns_cnt;
398 if (!dns_addr || IN6_IS_ADDR_UNSPECIFIED(dns_addr))
407 } dns = {ND_OPT_RECURSIVE_DNS, (1 + (2 * dns_cnt)), 0, 0, 0};
411 // DNS Search options
412 uint8_t search_buf[256], *search_domain = iface->search;
413 size_t search_len = iface->search_len, search_padded = 0;
415 if (!search_domain && !res_init() && _res.dnsrch[0] && _res.dnsrch[0][0]) {
416 int len = dn_comp(_res.dnsrch[0], search_buf,
417 sizeof(search_buf), NULL, NULL);
419 search_domain = search_buf;
425 search_padded = ((search_len + 7) & (~7)) + 8;
434 } *search = alloca(sizeof(*search) + search_padded);
436 search->type = ND_OPT_DNS_SEARCH;
437 search->len = search_len ? ((sizeof(*search) + search_padded) / 8) : 0;
440 memcpy(search->name, search_domain, search_len);
441 memset(&search->name[search_len], 0, search_padded - search_len);
444 size_t routes_cnt = 0;
452 } routes[RELAYD_MAX_PREFIXES];
454 for (ssize_t i = 0; i < ipcnt; ++i) {
455 struct odhcpd_ipaddr *addr = &addrs[i];
456 if (addr->dprefix > 64 || addr->dprefix == 0 || addr->valid <= (uint32_t)now ||
457 (addr->dprefix == 64 && addr->prefix == 64)) {
458 continue; // Address not suitable
459 } else if (addr->dprefix > 32) {
460 addr->addr.s6_addr32[1] &= htonl(~((1U << (64 - addr->dprefix)) - 1));
461 } else if (addr->dprefix <= 32) {
462 addr->addr.s6_addr32[0] &= htonl(~((1U << (32 - addr->dprefix)) - 1));
463 addr->addr.s6_addr32[1] = 0;
466 routes[routes_cnt].type = ND_OPT_ROUTE_INFO;
467 routes[routes_cnt].len = sizeof(*routes) / 8;
468 routes[routes_cnt].prefix = addr->dprefix;
469 routes[routes_cnt].flags = 0;
470 if (iface->route_preference < 0)
471 routes[routes_cnt].flags |= ND_RA_PREF_LOW;
472 else if (iface->route_preference > 0)
473 routes[routes_cnt].flags |= ND_RA_PREF_HIGH;
474 routes[routes_cnt].lifetime = htonl(TIME_LEFT(addr->valid, now));
475 routes[routes_cnt].addr[0] = addr->addr.s6_addr32[0];
476 routes[routes_cnt].addr[1] = addr->addr.s6_addr32[1];
477 routes[routes_cnt].addr[2] = 0;
478 routes[routes_cnt].addr[3] = 0;
483 search->lifetime = htonl(maxival*10);
484 dns.lifetime = search->lifetime;
486 struct icmpv6_opt adv_interval = {
487 .type = ND_OPT_RTR_ADV_INTERVAL,
489 .data = {0, 0, (maxival*1000) >> 24, (maxival*1000) >> 16, (maxival*1000) >> 8, maxival*1000}
492 struct iovec iov[RA_IOV_LEN] = {
493 {&adv, (uint8_t*)&adv.prefix[cnt] - (uint8_t*)&adv},
494 {&routes, routes_cnt * sizeof(*routes)},
495 {&dns, (dns_cnt) ? sizeof(dns) : 0},
496 {dns_addr, dns_cnt * sizeof(*dns_addr)},
497 {search, search->len * 8},
498 {&adv_interval, adv_interval.len * 8}};
499 struct sockaddr_in6 dest = {AF_INET6, 0, 0, ALL_IPV6_NODES, 0};
501 if (from && !IN6_IS_ADDR_UNSPECIFIED(from))
502 dest.sin6_addr = *from;
504 odhcpd_send(router_event.uloop.fd,
505 &dest, iov, ARRAY_SIZE(iov), iface);
511 static void trigger_router_advert(struct uloop_timeout *event)
513 struct interface *iface = container_of(event, struct interface, timer_rs);
514 int msecs = send_router_advert(iface, NULL);
516 // Rearm timer if not shut down
518 uloop_timeout_set(event, msecs);
522 // Event handler for incoming ICMPv6 packets
523 static void handle_icmpv6(void *addr, void *data, size_t len,
524 struct interface *iface, _unused void *dest)
526 struct icmp6_hdr *hdr = data;
527 struct sockaddr_in6 *from = addr;
529 if (!router_icmpv6_valid(addr, data, len))
532 if ((iface->ra == RELAYD_SERVER && !iface->master)) { // Server mode
533 if (hdr->icmp6_type == ND_ROUTER_SOLICIT)
534 send_router_advert(iface, &from->sin6_addr);
535 } else if (iface->ra == RELAYD_RELAY) { // Relay mode
536 if (hdr->icmp6_type == ND_ROUTER_ADVERT && iface->master)
537 forward_router_advertisement(data, len);
538 else if (hdr->icmp6_type == ND_ROUTER_SOLICIT && !iface->master)
539 forward_router_solicitation(odhcpd_get_master_interface());
544 // Forward router solicitation
545 static void forward_router_solicitation(const struct interface *iface)
550 struct icmp6_hdr rs = {ND_ROUTER_SOLICIT, 0, 0, {{0}}};
551 struct iovec iov = {&rs, sizeof(rs)};
552 struct sockaddr_in6 all_routers =
553 {AF_INET6, 0, 0, ALL_IPV6_ROUTERS, iface->ifindex};
555 syslog(LOG_NOTICE, "Sending RS to %s", iface->ifname);
556 odhcpd_send(router_event.uloop.fd, &all_routers, &iov, 1, iface);
560 // Handler for incoming router solicitations on slave interfaces
561 static void forward_router_advertisement(uint8_t *data, size_t len)
563 struct nd_router_advert *adv = (struct nd_router_advert *)data;
566 uint8_t *end = data + len;
567 uint8_t *mac_ptr = NULL;
568 struct in6_addr *dns_ptr = NULL;
569 size_t dns_count = 0;
571 struct icmpv6_opt *opt;
572 icmpv6_for_each_option(opt, &adv[1], end) {
573 if (opt->type == ND_OPT_SOURCE_LINKADDR) {
574 // Store address of source MAC-address
576 } else if (opt->type == ND_OPT_RECURSIVE_DNS && opt->len > 1) {
577 // Check if we have to rewrite DNS
578 dns_ptr = (struct in6_addr*)&opt->data[6];
579 dns_count = (opt->len - 1) / 2;
583 syslog(LOG_NOTICE, "Got a RA");
585 // Indicate a proxy, however we don't follow the rest of RFC 4389 yet
586 adv->nd_ra_flags_reserved |= ND_RA_FLAG_PROXY;
588 // Forward advertisement to all slave interfaces
589 struct sockaddr_in6 all_nodes = {AF_INET6, 0, 0, ALL_IPV6_NODES, 0};
590 struct iovec iov = {data, len};
592 struct interface *iface;
593 list_for_each_entry(iface, &interfaces, head) {
594 if (iface->ra != RELAYD_RELAY || iface->master)
597 // Fixup source hardware address option
599 odhcpd_get_mac(iface, mac_ptr);
601 // If we have to rewrite DNS entries
602 if (iface->always_rewrite_dns && dns_ptr && dns_count > 0) {
603 const struct in6_addr *rewrite = iface->dns;
604 struct in6_addr addr;
605 size_t rewrite_cnt = iface->dns_cnt;
607 if (rewrite_cnt == 0) {
608 if (odhcpd_get_linklocal_interface_address(iface->ifindex, &addr))
609 continue; // Unable to comply
615 // Copy over any other addresses
616 for (size_t i = 0; i < dns_count; ++i) {
617 size_t j = (i < rewrite_cnt) ? i : rewrite_cnt - 1;
618 dns_ptr[i] = rewrite[j];
622 odhcpd_send(router_event.uloop.fd, &all_nodes, &iov, 1, iface);