Initial commit

1 files changed, 502 insertions, 0 deletions

diff --git a/src/router.c b/src/router.c
new file mode 100644
index 0000000..9258acf
--- /dev/null
+++ b/src/router.c
@@ -0,0 +1,502 @@
+/**
+ * Copyright (C) 2012-2013 Steven Barth <steven@midlink.org>
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License v2 as published by
+ * the Free Software Foundation.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ */
+
+#include <errno.h>
+#include <fcntl.h>
+#include <signal.h>
+#include <resolv.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <unistd.h>
+#include <stdbool.h>
+#include <net/route.h>
+
+#include "router.h"
+#include "odhcpd.h"
+
+
+static void forward_router_solicitation(const struct interface *iface);
+static void forward_router_advertisement(uint8_t *data, size_t len);
+
+static void handle_icmpv6(void *addr, void *data, size_t len,
+		struct interface *iface);
+static void send_router_advert(struct uloop_timeout *event);
+static void sigusr1_refresh(int signal);
+
+static struct odhcpd_event router_event = {{.fd = -1}, handle_icmpv6};
+
+static FILE *fp_route = NULL;
+
+
+int init_router(void)
+{
+	// Open ICMPv6 socket
+	int sock = socket(AF_INET6, SOCK_RAW | SOCK_CLOEXEC, IPPROTO_ICMPV6);
+	if (sock < 0 && errno != EAFNOSUPPORT) {
+		syslog(LOG_ERR, "Failed to open RAW-socket: %s", strerror(errno));
+		return -1;
+	}
+
+	// Let the kernel compute our checksums
+	int val = 2;
+	setsockopt(sock, IPPROTO_RAW, IPV6_CHECKSUM, &val, sizeof(val));
+
+	// This is required by RFC 4861
+	val = 255;
+	setsockopt(sock, IPPROTO_IPV6, IPV6_MULTICAST_HOPS, &val, sizeof(val));
+	setsockopt(sock, IPPROTO_IPV6, IPV6_UNICAST_HOPS, &val, sizeof(val));
+
+	// We need to know the source interface
+	val = 1;
+	setsockopt(sock, IPPROTO_IPV6, IPV6_RECVPKTINFO, &val, sizeof(val));
+	setsockopt(sock, IPPROTO_IPV6, IPV6_RECVHOPLIMIT, &val, sizeof(val));
+
+	// Don't loop back
+	val = 0;
+	setsockopt(sock, IPPROTO_IPV6, IPV6_MULTICAST_LOOP, &val, sizeof(val));
+
+	// Filter ICMPv6 package types
+	struct icmp6_filter filt;
+	ICMP6_FILTER_SETBLOCKALL(&filt);
+	ICMP6_FILTER_SETPASS(ND_ROUTER_ADVERT, &filt);
+	ICMP6_FILTER_SETPASS(ND_ROUTER_SOLICIT, &filt);
+	setsockopt(sock, IPPROTO_ICMPV6, ICMP6_FILTER, &filt, sizeof(filt));
+
+	// Register socket
+	router_event.uloop.fd = sock;
+	odhcpd_register(&router_event);
+
+	if (!(fp_route = fopen("/proc/net/ipv6_route", "r")))
+		syslog(LOG_ERR, "Failed to open routing table: %s",
+				strerror(errno));
+
+	signal(SIGUSR1, sigusr1_refresh);
+	return 0;
+}
+
+
+int setup_router_interface(struct interface *iface, bool enable)
+{
+	struct ipv6_mreq all_nodes = {ALL_IPV6_NODES, iface->ifindex};
+	struct ipv6_mreq all_routers = {ALL_IPV6_ROUTERS, iface->ifindex};
+
+	uloop_timeout_cancel(&iface->timer_rs);
+	iface->timer_rs.cb = NULL;
+
+	setsockopt(router_event.uloop.fd, IPPROTO_IPV6, IPV6_DROP_MEMBERSHIP,
+			&all_nodes, sizeof(all_nodes));
+	setsockopt(router_event.uloop.fd, IPPROTO_IPV6, IPV6_DROP_MEMBERSHIP,
+			&all_routers, sizeof(all_routers));
+
+	if (!enable) {
+		if (iface->ra)
+			send_router_advert(&iface->timer_rs);
+	} else {
+		void *mreq = &all_routers;
+
+		if (iface->ra == RELAYD_RELAY && iface->master) {
+			mreq = &all_nodes;
+			forward_router_solicitation(iface);
+		} else if (iface->ra == RELAYD_SERVER && !iface->master) {
+			iface->timer_rs.cb = send_router_advert;
+			send_router_advert(&iface->timer_rs);
+		}
+
+		if (iface->ra == RELAYD_RELAY || (iface->ra == RELAYD_SERVER && !iface->master))
+			setsockopt(router_event.uloop.fd, IPPROTO_IPV6,
+					IPV6_ADD_MEMBERSHIP, mreq, sizeof(all_nodes));
+	}
+	return 0;
+}
+
+
+// Signal handler to resend all RDs
+static void sigusr1_refresh(_unused int signal)
+{
+	struct interface *iface;
+	list_for_each_entry(iface, &interfaces, head)
+		if (iface->ra == RELAYD_SERVER && !iface->master)
+			uloop_timeout_set(&iface->timer_rs, 1000);
+}
+
+
+// Event handler for incoming ICMPv6 packets
+static void handle_icmpv6(_unused void *addr, void *data, size_t len,
+		struct interface *iface)
+{
+	struct icmp6_hdr *hdr = data;
+	if ((iface->ra == RELAYD_SERVER && !iface->master)) { // Server mode
+		if (hdr->icmp6_type == ND_ROUTER_SOLICIT)
+			send_router_advert(&iface->timer_rs);
+	} else if (iface->ra == RELAYD_RELAY) { // Relay mode
+		if (hdr->icmp6_type == ND_ROUTER_ADVERT && iface->master)
+			forward_router_advertisement(data, len);
+		else if (hdr->icmp6_type == ND_ROUTER_SOLICIT && !iface->master)
+			forward_router_solicitation(odhcpd_get_master_interface());
+	}
+}
+
+
+static bool match_route(const struct odhcpd_ipaddr *n, const struct in6_addr *addr)
+{
+	if (n->prefix <= 32)
+		return ntohl(n->addr.s6_addr32[0]) >> (32 - n->prefix) ==
+				ntohl(addr->s6_addr32[0]) >> (32 - n->prefix);
+
+	if (n->addr.s6_addr32[0] != addr->s6_addr32[0])
+		return false;
+
+	return ntohl(n->addr.s6_addr32[1]) >> (64 - n->prefix) ==
+			ntohl(addr->s6_addr32[1]) >> (64 - n->prefix);
+}
+
+
+// Detect whether a default route exists, also find the source prefixes
+static bool parse_routes(struct odhcpd_ipaddr *n, ssize_t len)
+{
+	rewind(fp_route);
+
+	char line[512], ifname[16];
+	bool found_default = false;
+	struct odhcpd_ipaddr p = {IN6ADDR_ANY_INIT, 0, 0, 0};
+	while (fgets(line, sizeof(line), fp_route)) {
+		uint32_t rflags;
+		if (sscanf(line, "00000000000000000000000000000000 00 "
+				"%*s %*s %*s %*s %*s %*s %*s %15s", ifname) &&
+				strcmp(ifname, "lo")) {
+			found_default = true;
+		} else if (sscanf(line, "%8" SCNx32 "%8" SCNx32 "%*8" SCNx32 "%*8" SCNx32 " %hhx %*s "
+				"%*s 00000000000000000000000000000000 %*s %*s %*s %" SCNx32 " lo",
+				&p.addr.s6_addr32[0], &p.addr.s6_addr32[1], &p.prefix, &rflags) &&
+				p.prefix > 0 && (rflags & RTF_NONEXTHOP) && (rflags & RTF_REJECT)) {
+			// Find source prefixes by scanning through unreachable-routes
+			p.addr.s6_addr32[0] = htonl(p.addr.s6_addr32[0]);
+			p.addr.s6_addr32[1] = htonl(p.addr.s6_addr32[1]);
+
+			for (ssize_t i = 0; i < len; ++i) {
+				if (n[i].prefix <= 64 && n[i].prefix >= p.prefix &&
+						match_route(&p, &n[i].addr)) {
+					n[i].prefix = p.prefix;
+					break;
+				}
+			}
+
+		}
+	}
+
+	return found_default;
+}
+
+
+// Router Advert server mode
+static void send_router_advert(struct uloop_timeout *event)
+{
+	struct interface *iface =
+			container_of(event, struct interface, timer_rs);
+
+	int mtu = odhcpd_get_interface_mtu(iface->ifname);
+	if (mtu < 0)
+		mtu = 1500;
+
+	struct {
+		struct nd_router_advert h;
+		struct icmpv6_opt lladdr;
+		struct nd_opt_mtu mtu;
+		struct nd_opt_prefix_info prefix[RELAYD_MAX_PREFIXES];
+	} adv = {
+		.h = {{.icmp6_type = ND_ROUTER_ADVERT, .icmp6_code = 0}, 0, 0},
+		.lladdr = {ND_OPT_SOURCE_LINKADDR, 1, {0}},
+		.mtu = {ND_OPT_MTU, 1, 0, htonl(mtu)},
+	};
+	adv.h.nd_ra_flags_reserved = ND_RA_FLAG_OTHER;
+	if (iface->managed >= RELAYD_MANAGED_MFLAG)
+		adv.h.nd_ra_flags_reserved |= ND_RA_FLAG_MANAGED;
+
+	if (iface->route_preference < 0)
+		adv.h.nd_ra_flags_reserved |= ND_RA_PREF_LOW;
+	else if (iface->route_preference > 0)
+		adv.h.nd_ra_flags_reserved |= ND_RA_PREF_HIGH;
+	odhcpd_get_mac(iface, adv.lladdr.data);
+
+	// If not currently shutting down
+	struct odhcpd_ipaddr addrs[RELAYD_MAX_PREFIXES];
+	ssize_t ipcnt = 0;
+
+	// If not shutdown
+	if (event->cb) {
+		ipcnt = odhcpd_get_interface_addresses(iface->ifindex,
+				addrs, ARRAY_SIZE(addrs));
+
+		// Check default route
+		if (parse_routes(addrs, ipcnt) || iface->default_router > 1)
+			adv.h.nd_ra_router_lifetime =
+					htons(3 * MaxRtrAdvInterval);
+	}
+
+	// Construct Prefix Information options
+	bool have_public = false;
+	size_t cnt = 0;
+
+	struct in6_addr *dns_addr = NULL;
+	uint32_t dns_time = 0;
+	size_t dns_cnt = 1;
+
+	for (ssize_t i = 0; i < ipcnt; ++i) {
+		struct odhcpd_ipaddr *addr = &addrs[i];
+		if (addr->prefix > 64)
+			continue; // Address not suitable
+
+		if (addr->preferred > MaxPreferredTime)
+			addr->preferred = MaxPreferredTime;
+
+		if (addr->valid > MaxValidTime)
+			addr->valid = MaxValidTime;
+
+		struct nd_opt_prefix_info *p = NULL;
+		for (size_t i = 0; i < cnt; ++i) {
+			if (!memcmp(&adv.prefix[i].nd_opt_pi_prefix,
+					&addr->addr, 8))
+				p = &adv.prefix[i];
+		}
+
+		if (!p) {
+			if (cnt >= ARRAY_SIZE(adv.prefix))
+				break;
+
+			p = &adv.prefix[cnt++];
+		}
+
+		if ((addr->addr.s6_addr[0] & 0xfe) != 0xfc && addr->preferred > 0)
+			have_public = true;
+
+		memcpy(&p->nd_opt_pi_prefix, &addr->addr, 8);
+		p->nd_opt_pi_type = ND_OPT_PREFIX_INFORMATION;
+		p->nd_opt_pi_len = 4;
+		p->nd_opt_pi_prefix_len = 64;
+		p->nd_opt_pi_flags_reserved = 0;
+		if (!iface->ra_not_onlink)
+			p->nd_opt_pi_flags_reserved |= ND_OPT_PI_FLAG_ONLINK;
+		if (iface->managed < RELAYD_MANAGED_NO_AFLAG)
+			p->nd_opt_pi_flags_reserved |= ND_OPT_PI_FLAG_AUTO;
+		p->nd_opt_pi_valid_time = htonl(addr->valid);
+		p->nd_opt_pi_preferred_time = htonl(addr->preferred);
+
+		if (addr->preferred > dns_time) {
+			dns_time = addr->preferred;
+			dns_addr = &addr->addr;
+		}
+	}
+
+	if (!have_public && !iface->default_router && adv.h.nd_ra_router_lifetime) {
+		syslog(LOG_WARNING, "A default route is present but there is no public prefix "
+				"on %s thus we don't announce a default route!", iface->ifname);
+		adv.h.nd_ra_router_lifetime = 0;
+	}
+
+	if (have_public && iface->deprecate_ula_if_public_avail)
+		for (size_t i = 0; i < cnt; ++i)
+			if ((adv.prefix[i].nd_opt_pi_prefix.s6_addr[0] & 0xfe) == 0xfc)
+				adv.prefix[i].nd_opt_pi_preferred_time = 0;
+
+	// DNS Recursive DNS
+	if (iface->dns_cnt > 0) {
+		dns_addr = iface->dns;
+		dns_cnt = iface->dns_cnt;
+		dns_time = 2 * MaxRtrAdvInterval;
+	}
+
+	if (!dns_addr)
+		dns_cnt = 0;
+
+	struct {
+		uint8_t type;
+		uint8_t len;
+		uint8_t pad;
+		uint8_t pad2;
+		uint32_t lifetime;
+	} dns = {ND_OPT_RECURSIVE_DNS, (1 + (2 * dns_cnt)), 0, 0, htonl(dns_time)};
+
+
+
+	// DNS Search options
+	uint8_t search_buf[256], *search_domain = iface->search;
+	size_t search_len = iface->search_len, search_padded = 0;
+
+	if (!search_domain && !res_init() && _res.dnsrch[0] && _res.dnsrch[0][0]) {
+		int len = dn_comp(_res.dnsrch[0], search_buf,
+				sizeof(search_buf), NULL, NULL);
+		if (len > 0) {
+			search_domain = search_buf;
+			search_len = len;
+		}
+	}
+
+	if (search_len > 0)
+		search_padded = ((search_len + 7) & (~7)) + 8;
+
+	struct {
+		uint8_t type;
+		uint8_t len;
+		uint8_t pad;
+		uint8_t pad2;
+		uint32_t lifetime;
+		uint8_t name[];
+	} *search = alloca(sizeof(*search) + search_padded);
+	search->type = ND_OPT_DNS_SEARCH;
+	search->len = search_len ? ((sizeof(*search) + search_padded) / 8) : 0;
+	search->pad = 0;
+	search->pad2 = 0;
+	search->lifetime = htonl(2 * MaxRtrAdvInterval);;
+	memcpy(search->name, search_domain, search_len);
+	memset(&search->name[search_len], 0, search_padded - search_len);
+
+
+	size_t routes_cnt = 0;
+	struct {
+		uint8_t type;
+		uint8_t len;
+		uint8_t prefix;
+		uint8_t flags;
+		uint32_t lifetime;
+		uint32_t addr[4];
+	} routes[RELAYD_MAX_PREFIXES];
+
+	for (ssize_t i = 0; i < ipcnt; ++i) {
+		struct odhcpd_ipaddr *addr = &addrs[i];
+		if (addr->prefix > 64 || addr->prefix == 0) {
+			continue; // Address not suitable
+		} else if (addr->prefix > 32) {
+			addr->addr.s6_addr32[1] &= htonl(~((1U << (64 - addr->prefix)) - 1));
+		} else if (addr->prefix <= 32) {
+			addr->addr.s6_addr32[0] &= htonl(~((1U << (32 - addr->prefix)) - 1));
+			addr->addr.s6_addr32[1] = 0;
+		}
+
+		routes[routes_cnt].type = ND_OPT_ROUTE_INFO;
+		routes[routes_cnt].len = sizeof(*routes) / 8;
+		routes[routes_cnt].prefix = addr->prefix;
+		routes[routes_cnt].flags = 0;
+		if (iface->route_preference < 0)
+			routes[routes_cnt].flags |= ND_RA_PREF_LOW;
+		else if (iface->route_preference > 0)
+			routes[routes_cnt].flags |= ND_RA_PREF_HIGH;
+		routes[routes_cnt].lifetime = htonl(addr->valid);
+		routes[routes_cnt].addr[0] = addr->addr.s6_addr32[0];
+		routes[routes_cnt].addr[1] = addr->addr.s6_addr32[1];
+		routes[routes_cnt].addr[2] = addr->addr.s6_addr32[2];
+		routes[routes_cnt].addr[3] = addr->addr.s6_addr32[3];
+
+		++routes_cnt;
+	}
+
+
+	struct iovec iov[] = {{&adv, (uint8_t*)&adv.prefix[cnt] - (uint8_t*)&adv},
+			{&routes, routes_cnt * sizeof(*routes)},
+			{&dns, (dns_cnt) ? sizeof(dns) : 0},
+			{dns_addr, dns_cnt * sizeof(*dns_addr)},
+			{search, search->len * 8}};
+	struct sockaddr_in6 all_nodes = {AF_INET6, 0, 0, ALL_IPV6_NODES, 0};
+	odhcpd_send(router_event.uloop.fd,
+			&all_nodes, iov, ARRAY_SIZE(iov), iface);
+
+	// Rearm timer
+	int msecs;
+	odhcpd_urandom(&msecs, sizeof(msecs));
+	msecs = (labs(msecs) % (1000 * (MaxRtrAdvInterval
+			- MinRtrAdvInterval))) + (MinRtrAdvInterval * 1000);
+	uloop_timeout_set(&iface->timer_rs, msecs);
+}
+
+
+// Forward router solicitation
+static void forward_router_solicitation(const struct interface *iface)
+{
+	if (!iface)
+		return;
+
+	struct icmp6_hdr rs = {ND_ROUTER_SOLICIT, 0, 0, {{0}}};
+	struct iovec iov = {&rs, sizeof(rs)};
+	struct sockaddr_in6 all_routers =
+		{AF_INET6, 0, 0, ALL_IPV6_ROUTERS, iface->ifindex};
+
+	syslog(LOG_NOTICE, "Sending RS to %s", iface->ifname);
+	odhcpd_send(router_event.uloop.fd, &all_routers, &iov, 1, iface);
+}
+
+
+// Handler for incoming router solicitations on slave interfaces
+static void forward_router_advertisement(uint8_t *data, size_t len)
+{
+	struct nd_router_advert *adv = (struct nd_router_advert *)data;
+
+	// Rewrite options
+	uint8_t *end = data + len;
+	uint8_t *mac_ptr = NULL;
+	struct in6_addr *dns_ptr = NULL;
+	size_t dns_count = 0;
+
+	struct icmpv6_opt *opt;
+	icmpv6_for_each_option(opt, &adv[1], end) {
+		if (opt->type == ND_OPT_SOURCE_LINKADDR) {
+			// Store address of source MAC-address
+			mac_ptr = opt->data;
+		} else if (opt->type == ND_OPT_RECURSIVE_DNS && opt->len > 1) {
+			// Check if we have to rewrite DNS
+			dns_ptr = (struct in6_addr*)&opt->data[6];
+			dns_count = (opt->len - 1) / 2;
+		}
+	}
+
+	syslog(LOG_NOTICE, "Got a RA");
+
+	// Indicate a proxy, however we don't follow the rest of RFC 4389 yet
+	adv->nd_ra_flags_reserved |= ND_RA_FLAG_PROXY;
+
+	// Forward advertisement to all slave interfaces
+	struct sockaddr_in6 all_nodes = {AF_INET6, 0, 0, ALL_IPV6_NODES, 0};
+	struct iovec iov = {data, len};
+
+	struct odhcpd_ipaddr addr;
+	struct interface *iface;
+	list_for_each_entry(iface, &interfaces, head) {
+		if (iface->ra != RELAYD_RELAY || iface->master)
+			continue;
+
+		// Fixup source hardware address option
+		if (mac_ptr)
+			odhcpd_get_mac(iface, mac_ptr);
+
+		// If we have to rewrite DNS entries
+		if (iface->always_rewrite_dns && dns_ptr && dns_count > 0) {
+			const struct in6_addr *rewrite = iface->dns;
+			size_t rewrite_cnt = iface->dns_cnt;
+
+			if (rewrite_cnt == 0) {
+				if (odhcpd_get_interface_addresses(iface->ifindex, &addr, 1) < 1)
+					continue; // Unable to comply
+
+				rewrite = &addr.addr;
+				rewrite_cnt = 1;
+			}
+
+			// Copy over any other addresses
+			for (size_t i = 0; i < dns_count; ++i) {
+				size_t j = (i < rewrite_cnt) ? i : rewrite_cnt - 1;
+				dns_ptr[i] = rewrite[j];
+			}
+		}
+
+		odhcpd_send(router_event.uloop.fd, &all_nodes, &iov, 1, iface);
+	}
+}