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 router_netevent_cb(unsigned long event, struct netevent_handler_info *info);
38 static struct odhcpd_event router_event = {.uloop = {.fd = -1}, .handle_dgram = handle_icmpv6, };
39 static struct netevent_handler router_netevent_handler = { .cb = router_netevent_cb, };
41 static FILE *fp_route = NULL;
44 #define TIME_LEFT(t1, now) ((t1) != UINT32_MAX ? (t1) - (now) : UINT32_MAX)
49 int sock = socket(AF_INET6, SOCK_RAW | SOCK_CLOEXEC, IPPROTO_ICMPV6);
50 if (sock < 0 && errno != EAFNOSUPPORT) {
51 syslog(LOG_ERR, "Failed to open RAW-socket: %s", strerror(errno));
55 // Let the kernel compute our checksums
57 setsockopt(sock, IPPROTO_RAW, IPV6_CHECKSUM, &val, sizeof(val));
59 // This is required by RFC 4861
61 setsockopt(sock, IPPROTO_IPV6, IPV6_MULTICAST_HOPS, &val, sizeof(val));
62 setsockopt(sock, IPPROTO_IPV6, IPV6_UNICAST_HOPS, &val, sizeof(val));
64 // We need to know the source interface
66 setsockopt(sock, IPPROTO_IPV6, IPV6_RECVPKTINFO, &val, sizeof(val));
67 setsockopt(sock, IPPROTO_IPV6, IPV6_RECVHOPLIMIT, &val, sizeof(val));
71 setsockopt(sock, IPPROTO_IPV6, IPV6_MULTICAST_LOOP, &val, sizeof(val));
73 // Filter ICMPv6 package types
74 struct icmp6_filter filt;
75 ICMP6_FILTER_SETBLOCKALL(&filt);
76 ICMP6_FILTER_SETPASS(ND_ROUTER_ADVERT, &filt);
77 ICMP6_FILTER_SETPASS(ND_ROUTER_SOLICIT, &filt);
78 setsockopt(sock, IPPROTO_ICMPV6, ICMP6_FILTER, &filt, sizeof(filt));
81 router_event.uloop.fd = sock;
82 odhcpd_register(&router_event);
84 if (!(fp_route = fopen("/proc/net/ipv6_route", "r")))
85 syslog(LOG_ERR, "Failed to open routing table: %s",
88 netlink_add_netevent_handler(&router_netevent_handler);
94 int router_setup_interface(struct interface *iface, bool enable)
96 if (!fp_route || router_event.uloop.fd < 0)
99 struct ipv6_mreq all_nodes = {ALL_IPV6_NODES, iface->ifindex};
100 struct ipv6_mreq all_routers = {ALL_IPV6_ROUTERS, iface->ifindex};
102 uloop_timeout_cancel(&iface->timer_rs);
103 iface->timer_rs.cb = NULL;
105 if (iface->ifindex <= 0)
108 setsockopt(router_event.uloop.fd, IPPROTO_IPV6, IPV6_DROP_MEMBERSHIP,
109 &all_nodes, sizeof(all_nodes));
110 setsockopt(router_event.uloop.fd, IPPROTO_IPV6, IPV6_DROP_MEMBERSHIP,
111 &all_routers, sizeof(all_routers));
115 trigger_router_advert(&iface->timer_rs);
117 void *mreq = &all_routers;
119 if (iface->ra == MODE_RELAY && iface->master) {
121 forward_router_solicitation(iface);
122 } else if (iface->ra == MODE_SERVER && !iface->master) {
123 iface->timer_rs.cb = trigger_router_advert;
124 uloop_timeout_set(&iface->timer_rs, 1000);
127 if (iface->ra == MODE_RELAY || (iface->ra == MODE_SERVER && !iface->master))
128 setsockopt(router_event.uloop.fd, IPPROTO_IPV6,
129 IPV6_ADD_MEMBERSHIP, mreq, sizeof(all_nodes));
135 static void router_netevent_cb(unsigned long event, struct netevent_handler_info *info)
137 struct interface *iface;
140 case NETEV_ROUTE6_ADD:
141 case NETEV_ROUTE6_DEL:
142 if (info->rt.dst_len)
145 list_for_each_entry(iface, &interfaces, head) {
146 if (iface->ra == MODE_SERVER && !iface->master)
147 uloop_timeout_set(&iface->timer_rs, 1000);
150 case NETEV_ADDR6LIST_CHANGE:
152 if (iface && iface->ra == MODE_SERVER && !iface->master)
153 uloop_timeout_set(&iface->timer_rs, 1000);
161 static bool router_icmpv6_valid(struct sockaddr_in6 *source, uint8_t *data, size_t len)
163 struct icmp6_hdr *hdr = (struct icmp6_hdr *)data;
164 struct icmpv6_opt *opt, *end = (struct icmpv6_opt*)&data[len];
166 /* Hoplimit is already checked in odhcpd_receive_packets */
167 if (len < sizeof(*hdr) || hdr->icmp6_code)
170 switch (hdr->icmp6_type) {
171 case ND_ROUTER_ADVERT:
172 if (!IN6_IS_ADDR_LINKLOCAL(&source->sin6_addr))
175 opt = (struct icmpv6_opt *)((struct nd_router_advert *)data + 1);
178 case ND_ROUTER_SOLICIT:
179 opt = (struct icmpv6_opt *)((struct nd_router_solicit *)data + 1);
186 icmpv6_for_each_option(opt, opt, end)
187 if (opt->type == ND_OPT_SOURCE_LINKADDR &&
188 IN6_IS_ADDR_UNSPECIFIED(&source->sin6_addr) &&
189 hdr->icmp6_type == ND_ROUTER_SOLICIT)
192 // Check all options parsed successfully
197 // Detect whether a default route exists, also find the source prefixes
198 static bool parse_routes(struct odhcpd_ipaddr *n, ssize_t len)
202 char line[512], ifname[16];
203 bool found_default = false;
204 struct odhcpd_ipaddr p = { .addr.in6 = IN6ADDR_ANY_INIT, .prefix = 0,
205 .dprefix = 0, .preferred = 0, .valid = 0};
207 while (fgets(line, sizeof(line), fp_route)) {
209 if (sscanf(line, "00000000000000000000000000000000 00 "
210 "%*s %*s %*s %*s %*s %*s %*s %15s", ifname) &&
211 strcmp(ifname, "lo")) {
212 found_default = true;
213 } else if (sscanf(line, "%8" SCNx32 "%8" SCNx32 "%*8" SCNx32 "%*8" SCNx32 " %hhx %*s "
214 "%*s 00000000000000000000000000000000 %*s %*s %*s %" SCNx32 " lo",
215 &p.addr.in6.s6_addr32[0], &p.addr.in6.s6_addr32[1], &p.prefix, &rflags) &&
216 p.prefix > 0 && (rflags & RTF_NONEXTHOP) && (rflags & RTF_REJECT)) {
217 // Find source prefixes by scanning through unreachable-routes
218 p.addr.in6.s6_addr32[0] = htonl(p.addr.in6.s6_addr32[0]);
219 p.addr.in6.s6_addr32[1] = htonl(p.addr.in6.s6_addr32[1]);
221 for (ssize_t i = 0; i < len; ++i) {
222 if (n[i].prefix <= 64 && n[i].prefix >= p.prefix &&
223 !odhcpd_bmemcmp(&p.addr.in6, &n[i].addr.in6, p.prefix)) {
224 n[i].dprefix = p.prefix;
232 return found_default;
235 static int calc_adv_interval(struct interface *iface, uint32_t minvalid,
238 uint32_t minival = iface->ra_mininterval;
241 *maxival = iface->ra_maxinterval;
243 if (*maxival > minvalid/3)
244 *maxival = minvalid/3;
246 if (*maxival > MaxRtrAdvInterval)
247 *maxival = MaxRtrAdvInterval;
248 else if (*maxival < 4)
251 if (minival < MinRtrAdvInterval)
252 minival = MinRtrAdvInterval;
253 else if (minival > (*maxival * 3)/4)
254 minival = (*maxival >= 9 ? *maxival/3 : *maxival);
256 odhcpd_urandom(&msecs, sizeof(msecs));
257 msecs = (labs(msecs) % ((*maxival != minival) ? (*maxival - minival)*1000 : 500)) +
263 static uint16_t calc_ra_lifetime(struct interface *iface, uint32_t maxival)
265 uint16_t lifetime = 3*maxival;
267 if (iface->ra_lifetime >= 0) {
268 lifetime = iface->ra_lifetime;
269 if (lifetime < maxival)
271 else if (lifetime > 9000)
289 // Router Advert server mode
290 static uint64_t send_router_advert(struct interface *iface, const struct in6_addr *from)
292 time_t now = odhcpd_time();
293 int mtu = iface->ra_mtu;
294 int hlim = iface->ra_hoplimit;
297 mtu = odhcpd_get_interface_config(iface->ifname, "mtu");
303 hlim = odhcpd_get_interface_config(iface->ifname, "hop_limit");
306 struct nd_router_advert h;
307 struct icmpv6_opt lladdr;
308 struct nd_opt_mtu mtu;
310 .h = {{.icmp6_type = ND_ROUTER_ADVERT, .icmp6_code = 0}, 0, 0},
311 .lladdr = {ND_OPT_SOURCE_LINKADDR, 1, {0}},
312 .mtu = {ND_OPT_MTU, 1, 0, htonl(mtu)},
316 adv.h.nd_ra_curhoplimit = hlim;
319 adv.h.nd_ra_flags_reserved = ND_RA_FLAG_OTHER;
321 if (iface->ra_managed >= RA_MANAGED_MFLAG)
322 adv.h.nd_ra_flags_reserved |= ND_RA_FLAG_MANAGED;
324 if (iface->route_preference < 0)
325 adv.h.nd_ra_flags_reserved |= ND_RA_PREF_LOW;
326 else if (iface->route_preference > 0)
327 adv.h.nd_ra_flags_reserved |= ND_RA_PREF_HIGH;
329 adv.h.nd_ra_reachable = htonl(iface->ra_reachabletime);
330 adv.h.nd_ra_retransmit = htonl(iface->ra_retranstime);
332 odhcpd_get_mac(iface, adv.lladdr.data);
334 // If not currently shutting down
335 struct odhcpd_ipaddr *addrs = NULL;
337 uint32_t minvalid = UINT32_MAX;
338 bool default_route = false;
339 bool valid_prefix = false;
342 if (iface->timer_rs.cb) {
343 size_t size = sizeof(*addrs) * iface->addr6_len;
344 addrs = alloca(size);
345 memcpy(addrs, iface->addr6, size);
347 ipcnt = iface->addr6_len;
349 // Check default route
350 if (iface->default_router) {
351 default_route = true;
353 if (iface->default_router > 1)
355 } else if (parse_routes(addrs, ipcnt))
356 default_route = true;
360 struct in6_addr dns_pref, *dns_addr = &dns_pref;
363 odhcpd_get_interface_dns_addr(iface, &dns_pref);
365 // Construct Prefix Information options
367 struct nd_opt_prefix_info *pfxs = NULL;
369 for (ssize_t i = 0; i < ipcnt; ++i) {
370 struct odhcpd_ipaddr *addr = &addrs[i];
371 uint32_t preferred = 0;
374 if (addr->prefix > 96 || addr->valid <= (uint32_t)now) {
375 char namebuf[INET6_ADDRSTRLEN];
377 inet_ntop(AF_INET6, &addr->addr.in6, namebuf, sizeof(namebuf));
378 syslog(LOG_INFO, "Address %s (prefix %d, valid %u) not suitable as RA prefix on %s",
379 namebuf, addr->prefix, addr->valid, iface->ifname);
383 struct nd_opt_prefix_info *p = NULL;
384 for (size_t i = 0; i < pfxs_cnt; ++i) {
385 if (addr->prefix == pfxs[i].nd_opt_pi_prefix_len &&
386 !odhcpd_bmemcmp(&pfxs[i].nd_opt_pi_prefix,
387 &addr->addr.in6, addr->prefix))
392 struct nd_opt_prefix_info *tmp;
394 tmp = realloc(pfxs, sizeof(*pfxs) * (pfxs_cnt + 1));
396 syslog(LOG_ERR, "Realloc failed for RA prefix option on interface %s", iface->ifname);
401 p = &pfxs[pfxs_cnt++];
402 memset(p, 0, sizeof(*p));
405 if (addr->preferred > (uint32_t)now) {
406 preferred = TIME_LEFT(addr->preferred, now);
408 if (iface->ra_useleasetime &&
409 preferred > iface->dhcpv4_leasetime)
410 preferred = iface->dhcpv4_leasetime;
413 valid = TIME_LEFT(addr->valid, now);
414 if (iface->ra_useleasetime && valid > iface->dhcpv4_leasetime)
415 valid = iface->dhcpv4_leasetime;
417 if (minvalid > valid)
420 if (!IN6_IS_ADDR_ULA(&addr->addr.in6) || iface->default_router)
423 odhcpd_bmemcpy(&p->nd_opt_pi_prefix, &addr->addr.in6,
424 (iface->ra_advrouter) ? 128 : addr->prefix);
425 p->nd_opt_pi_type = ND_OPT_PREFIX_INFORMATION;
426 p->nd_opt_pi_len = 4;
427 p->nd_opt_pi_prefix_len = (addr->prefix < 64) ? 64 : addr->prefix;
428 p->nd_opt_pi_flags_reserved = 0;
429 if (!iface->ra_not_onlink)
430 p->nd_opt_pi_flags_reserved |= ND_OPT_PI_FLAG_ONLINK;
431 if (iface->ra_managed < RA_MANAGED_NO_AFLAG && addr->prefix <= 64)
432 p->nd_opt_pi_flags_reserved |= ND_OPT_PI_FLAG_AUTO;
433 if (iface->ra_advrouter)
434 p->nd_opt_pi_flags_reserved |= ND_OPT_PI_FLAG_RADDR;
435 p->nd_opt_pi_preferred_time = htonl(preferred);
436 p->nd_opt_pi_valid_time = htonl(valid);
439 // Calculate periodic transmit
441 int msecs = calc_adv_interval(iface, minvalid, &maxival);
445 syslog(LOG_WARNING, "A default route is present but there is no public prefix "
446 "on %s thus we don't announce a default route!", iface->ifname);
447 adv.h.nd_ra_router_lifetime = 0;
449 adv.h.nd_ra_router_lifetime = htons(calc_ra_lifetime(iface, maxival));
452 adv.h.nd_ra_router_lifetime = 0;
454 syslog(LOG_INFO, "Using a RA lifetime of %d seconds on %s", ntohs(adv.h.nd_ra_router_lifetime), iface->ifname);
457 if (iface->dns_cnt > 0) {
458 dns_addr = iface->dns;
459 dns_cnt = iface->dns_cnt;
462 if (!dns_addr || IN6_IS_ADDR_UNSPECIFIED(dns_addr))
471 } dns = {ND_OPT_RECURSIVE_DNS, (1 + (2 * dns_cnt)), 0, 0, 0};
473 // DNS Search options
474 uint8_t search_buf[256], *search_domain = iface->search;
475 size_t search_len = iface->search_len, search_padded = 0;
477 if (!search_domain && !res_init() && _res.dnsrch[0] && _res.dnsrch[0][0]) {
478 int len = dn_comp(_res.dnsrch[0], search_buf,
479 sizeof(search_buf), NULL, NULL);
481 search_domain = search_buf;
487 search_padded = ((search_len + 7) & (~7)) + 8;
496 } *search = alloca(sizeof(*search) + search_padded);
498 search->type = ND_OPT_DNS_SEARCH;
499 search->len = search_len ? ((sizeof(*search) + search_padded) / 8) : 0;
502 memcpy(search->name, search_domain, search_len);
503 memset(&search->name[search_len], 0, search_padded - search_len);
506 size_t routes_cnt = 0;
514 } *tmp, *routes = NULL;
516 for (ssize_t i = 0; i < ipcnt; ++i) {
517 struct odhcpd_ipaddr *addr = &addrs[i];
518 if (addr->dprefix > 64 || addr->dprefix == 0 || addr->valid <= (uint32_t)now ||
519 (addr->dprefix == 64 && addr->prefix == 64)) {
520 continue; // Address not suitable
521 } else if (addr->dprefix > 32) {
522 addr->addr.in6.s6_addr32[1] &= htonl(~((1U << (64 - addr->dprefix)) - 1));
523 } else if (addr->dprefix <= 32) {
524 addr->addr.in6.s6_addr32[0] &= htonl(~((1U << (32 - addr->dprefix)) - 1));
525 addr->addr.in6.s6_addr32[1] = 0;
528 tmp = realloc(routes, sizeof(*routes) * (routes_cnt + 1));
530 syslog(LOG_ERR, "Realloc failed for RA route option on interface %s", iface->ifname);
536 memset(&routes[routes_cnt], 0, sizeof(*routes));
537 routes[routes_cnt].type = ND_OPT_ROUTE_INFO;
538 routes[routes_cnt].len = sizeof(*routes) / 8;
539 routes[routes_cnt].prefix = addr->dprefix;
540 routes[routes_cnt].flags = 0;
541 if (iface->route_preference < 0)
542 routes[routes_cnt].flags |= ND_RA_PREF_LOW;
543 else if (iface->route_preference > 0)
544 routes[routes_cnt].flags |= ND_RA_PREF_HIGH;
545 routes[routes_cnt].lifetime = htonl(TIME_LEFT(addr->valid, now));
546 routes[routes_cnt].addr[0] = addr->addr.in6.s6_addr32[0];
547 routes[routes_cnt].addr[1] = addr->addr.in6.s6_addr32[1];
548 routes[routes_cnt].addr[2] = 0;
549 routes[routes_cnt].addr[3] = 0;
554 search->lifetime = htonl(maxival*10);
555 dns.lifetime = search->lifetime;
557 struct icmpv6_opt adv_interval = {
558 .type = ND_OPT_RTR_ADV_INTERVAL,
560 .data = {0, 0, (maxival*1000) >> 24, (maxival*1000) >> 16, (maxival*1000) >> 8, maxival*1000}
563 struct iovec iov[IOV_RA_TOTAL] = {
564 [IOV_RA_ADV] = {&adv, sizeof(adv)},
565 [IOV_RA_PFXS] = {pfxs, pfxs_cnt * sizeof(*pfxs)},
566 [IOV_RA_ROUTES] = {routes, routes_cnt * sizeof(*routes)},
567 [IOV_RA_DNS] = {&dns, (dns_cnt) ? sizeof(dns) : 0},
568 [IOV_RA_DNS_ADDR] = {dns_addr, dns_cnt * sizeof(*dns_addr)},
569 [IOV_RA_SEARCH] = {search, search->len * 8},
570 [IOV_RA_ADV_INTERVAL] = {&adv_interval, adv_interval.len * 8}};
571 struct sockaddr_in6 dest = {AF_INET6, 0, 0, ALL_IPV6_NODES, 0};
573 if (from && !IN6_IS_ADDR_UNSPECIFIED(from))
574 dest.sin6_addr = *from;
576 odhcpd_send(router_event.uloop.fd,
577 &dest, iov, ARRAY_SIZE(iov), iface);
586 static void trigger_router_advert(struct uloop_timeout *event)
588 struct interface *iface = container_of(event, struct interface, timer_rs);
589 int msecs = send_router_advert(iface, NULL);
591 // Rearm timer if not shut down
593 uloop_timeout_set(event, msecs);
597 // Event handler for incoming ICMPv6 packets
598 static void handle_icmpv6(void *addr, void *data, size_t len,
599 struct interface *iface, _unused void *dest)
601 struct icmp6_hdr *hdr = data;
602 struct sockaddr_in6 *from = addr;
604 if (!router_icmpv6_valid(addr, data, len))
607 if ((iface->ra == MODE_SERVER && !iface->master)) { // Server mode
608 if (hdr->icmp6_type == ND_ROUTER_SOLICIT)
609 send_router_advert(iface, &from->sin6_addr);
610 } else if (iface->ra == MODE_RELAY) { // Relay mode
611 if (hdr->icmp6_type == ND_ROUTER_ADVERT && iface->master)
612 forward_router_advertisement(data, len);
613 else if (hdr->icmp6_type == ND_ROUTER_SOLICIT && !iface->master)
614 forward_router_solicitation(odhcpd_get_master_interface());
619 // Forward router solicitation
620 static void forward_router_solicitation(const struct interface *iface)
625 struct icmp6_hdr rs = {ND_ROUTER_SOLICIT, 0, 0, {{0}}};
626 struct iovec iov = {&rs, sizeof(rs)};
627 struct sockaddr_in6 all_routers =
628 {AF_INET6, 0, 0, ALL_IPV6_ROUTERS, iface->ifindex};
630 syslog(LOG_NOTICE, "Sending RS to %s", iface->ifname);
631 odhcpd_send(router_event.uloop.fd, &all_routers, &iov, 1, iface);
635 // Handler for incoming router solicitations on slave interfaces
636 static void forward_router_advertisement(uint8_t *data, size_t len)
638 struct nd_router_advert *adv = (struct nd_router_advert *)data;
641 uint8_t *end = data + len;
642 uint8_t *mac_ptr = NULL;
643 struct in6_addr *dns_ptr = NULL;
644 size_t dns_count = 0;
646 struct icmpv6_opt *opt;
647 icmpv6_for_each_option(opt, &adv[1], end) {
648 if (opt->type == ND_OPT_SOURCE_LINKADDR) {
649 // Store address of source MAC-address
651 } else if (opt->type == ND_OPT_RECURSIVE_DNS && opt->len > 1) {
652 // Check if we have to rewrite DNS
653 dns_ptr = (struct in6_addr*)&opt->data[6];
654 dns_count = (opt->len - 1) / 2;
658 syslog(LOG_NOTICE, "Got a RA");
660 // Indicate a proxy, however we don't follow the rest of RFC 4389 yet
661 adv->nd_ra_flags_reserved |= ND_RA_FLAG_PROXY;
663 // Forward advertisement to all slave interfaces
664 struct sockaddr_in6 all_nodes = {AF_INET6, 0, 0, ALL_IPV6_NODES, 0};
665 struct iovec iov = {data, len};
667 struct interface *iface;
668 list_for_each_entry(iface, &interfaces, head) {
669 if (iface->ra != MODE_RELAY || iface->master)
672 // Fixup source hardware address option
674 odhcpd_get_mac(iface, mac_ptr);
676 // If we have to rewrite DNS entries
677 if (iface->always_rewrite_dns && dns_ptr && dns_count > 0) {
678 const struct in6_addr *rewrite = iface->dns;
679 struct in6_addr addr;
680 size_t rewrite_cnt = iface->dns_cnt;
682 if (rewrite_cnt == 0) {
683 if (odhcpd_get_interface_dns_addr(iface, &addr))
684 continue; // Unable to comply
690 // Copy over any other addresses
691 for (size_t i = 0; i < dns_count; ++i) {
692 size_t j = (i < rewrite_cnt) ? i : rewrite_cnt - 1;
693 dns_ptr[i] = rewrite[j];
697 odhcpd_send(router_event.uloop.fd, &all_nodes, &iov, 1, iface);