Initial rewrite of NDP proxy

1 files changed, 117 insertions, 204 deletions

diff --git a/src/ndp.c b/src/ndp.c
index 44884be..9840ed4 100644
--- a/src/ndp.c
+++ b/src/ndp.c
@@ -17,6 +17,7 @@
 #include <signal.h>
 #include <errno.h>
 
+#include <fcntl.h>
 #include <unistd.h>
 #include <arpa/inet.h>
 #include <sys/socket.h>
@@ -36,18 +37,11 @@ static void handle_solicit(void *addr, void *data, size_t len,
 		struct interface *iface, void *dest);
 static void handle_rtnetlink(void *addr, void *data, size_t len,
 		struct interface *iface, void *dest);
-static struct ndp_neighbor* find_neighbor(struct in6_addr *addr, bool strict);
-static void modify_neighbor(struct in6_addr *addr, struct interface *iface,
-		bool add);
 static ssize_t ping6(struct in6_addr *addr,
 		const struct interface *iface);
 
-static struct list_head neighbors = LIST_HEAD_INIT(neighbors);
-static size_t neighbor_count = 0;
 static uint32_t rtnl_seqid = 0;
-
 static int ping_socket = -1;
-static struct odhcpd_event ndp_event = {{.fd = -1}, handle_solicit};
 static struct odhcpd_event rtnl_event = {{.fd = -1}, handle_rtnetlink};
 
 
@@ -116,105 +110,71 @@ int init_ndp(void)
 	group = RTNLGRP_NEIGH;
 	setsockopt(rtnl_event.uloop.fd, SOL_NETLINK, NETLINK_ADD_MEMBERSHIP, &group, sizeof(group));
 
-	// Synthesize initial neighbor events
-	struct {
-		struct nlmsghdr nh;
-		struct ndmsg ndm;
-	} req = {
-		{sizeof(req), RTM_GETNEIGH, NLM_F_REQUEST | NLM_F_DUMP,
-				++rtnl_seqid, 0},
-		{.ndm_family = AF_INET6}
-	};
-	send(rtnl_event.uloop.fd, &req, sizeof(req), MSG_DONTWAIT);
-
 	return 0;
 }
 
 
 int setup_ndp_interface(struct interface *iface, bool enable)
 {
-	struct packet_mreq mreq = {iface->ifindex, PACKET_MR_ALLMULTI, ETH_ALEN, {0}};
-	setsockopt(ndp_event.uloop.fd, SOL_PACKET, PACKET_DROP_MEMBERSHIP, &mreq, sizeof(mreq));
-
-	struct ndp_neighbor *c, *n;
-	list_for_each_entry_safe(c, n, &neighbors, head)
-		if (c->iface == iface && (c->timeout == 0 || iface->ndp != RELAYD_RELAY || !enable))
-			modify_neighbor(&c->addr, c->iface, false);
+	char procbuf[64];
+	snprintf(procbuf, sizeof(procbuf), "/proc/sys/net/ipv6/conf/%s/proxy_ndp", iface->ifname);
+	int procfd = open(procbuf, O_WRONLY);
 
-	if (enable && iface->ndp == RELAYD_RELAY) {
-		setsockopt(ndp_event.uloop.fd, SOL_PACKET, PACKET_ADD_MEMBERSHIP, &mreq, sizeof(mreq));
-
-		if (iface->static_ndp_len) {
-			char *entry = alloca(iface->static_ndp_len), *saveptr;
-			if (!entry) {
-				syslog(LOG_ERR, "Alloca failed for static NDP list");
-				return -1;
-			}
-			memcpy(entry, iface->static_ndp, iface->static_ndp_len);
-
-			for (entry = strtok_r(entry, " ", &saveptr); entry; entry = strtok_r(NULL, " ", &saveptr)) {
-				char *sep;
-				struct ndp_neighbor *n = malloc(sizeof(*n));
-				if (!n) {
-					syslog(LOG_ERR, "Malloc failed for static NDP-prefix %s", entry);
-					return -1;
-				}
-
-				n->iface = iface;
-				n->timeout = 0;
-
-				sep = strchr(entry, '/');
-				if (!sep) {
-					free(n);
-					syslog(LOG_ERR, "Invalid static NDP-prefix %s", entry);
-					return -1;
-				}
-				
-				*sep = 0;
-				n->len = atoi(sep + 1);
-				if (inet_pton(AF_INET6, entry, &n->addr) != 1 || n->len > 128) {
-					free(n);
-					syslog(LOG_ERR, "Invalid static NDP-prefix %s/%s", entry, sep + 1);
-					return -1;
-				}
+	if (iface->ndp_event.uloop.fd >= 0) {
+		uloop_fd_delete(&iface->ndp_event.uloop);
+		close(iface->ndp_event.uloop.fd);
+		iface->ndp_event.uloop.fd = -1;
 
-				list_add(&n->head, &neighbors);
-			}
-		}
+		write(procfd, "0\n", 2);
 	}
 
-	bool enable_packet = false;
-	struct interface *i;
-	list_for_each_entry(i, &interfaces, head) {
-		if (i == iface && !enable)
-			continue;
-
-		if (i->ndp == RELAYD_RELAY)
-			enable_packet = true;
-	}
+	if (enable && iface->ndp == RELAYD_RELAY) {
+		write(procfd, "1\n", 2);
 
-	if (enable_packet && ndp_event.uloop.fd < 0) {
-		// Create socket for intercepting NDP
-		int sock = socket(AF_PACKET, SOCK_DGRAM | SOCK_CLOEXEC | SOCK_NONBLOCK,
-				htons(ETH_P_ALL)); // ETH_P_ALL for ingress + egress
+		int sock = socket(AF_PACKET, SOCK_DGRAM | SOCK_CLOEXEC, htons(ETH_P_IPV6));
 		if (sock < 0) {
 			syslog(LOG_ERR, "Unable to open packet socket: %s",
 					strerror(errno));
 			return -1;
 		}
 
+#ifdef PACKET_RECV_TYPE
+		int pktt = 1 << PACKET_MULTICAST;
+		setsockopt(sock, SOL_PACKET, PACKET_RECV_TYPE, &pktt, sizeof(pktt));
+#endif
+
 		if (setsockopt(sock, SOL_SOCKET, SO_ATTACH_FILTER,
 				&bpf_prog, sizeof(bpf_prog))) {
 			syslog(LOG_ERR, "Failed to set BPF: %s", strerror(errno));
 			return -1;
 		}
 
-		ndp_event.uloop.fd = sock;
-		odhcpd_register(&ndp_event);
-	} else if (!enable_packet && ndp_event.uloop.fd >= 0) {
-		close(ndp_event.uloop.fd);
-		ndp_event.uloop.fd = -1;
+		struct sockaddr_ll ll = {
+			.sll_family = AF_PACKET,
+			.sll_ifindex = iface->ifindex,
+			.sll_protocol = htons(ETH_P_IPV6),
+		};
+		bind(sock, (struct sockaddr*)&ll, sizeof(ll));
+
+		struct packet_mreq mreq = {iface->ifindex, PACKET_MR_ALLMULTI, ETH_ALEN, {0}};
+		setsockopt(sock, SOL_PACKET, PACKET_ADD_MEMBERSHIP, &mreq, sizeof(mreq));
+
+		iface->ndp_event.uloop.fd = sock;
+		iface->ndp_event.handle_dgram = handle_solicit;
+		odhcpd_register(&iface->ndp_event);
+
+		// Dump neighbor events
+		struct {
+			struct nlmsghdr nh;
+			struct ndmsg ndm;
+		} req = {
+			{sizeof(req), RTM_GETNEIGH, NLM_F_REQUEST | NLM_F_DUMP,
+					++rtnl_seqid, 0},
+			{.ndm_family = AF_INET6}
+		};
+		send(rtnl_event.uloop.fd, &req, sizeof(req), MSG_DONTWAIT);
 	}
+	close(procfd);
 
 	return 0;
 }
@@ -266,61 +226,14 @@ static void handle_solicit(void *addr, void *data, size_t len,
 
 	uint8_t mac[6];
 	odhcpd_get_mac(iface, mac);
-	if (!memcmp(ll->sll_addr, mac, sizeof(mac)) &&
-			ll->sll_pkttype != PACKET_OUTGOING)
+	if (!memcmp(ll->sll_addr, mac, sizeof(mac)))
 		return; // Looped back
 
-	time_t now = time(NULL);
-
-	struct ndp_neighbor *n = find_neighbor(&req->nd_ns_target, false);
-	if (n && (n->iface || abs(n->timeout - now) < 5)) {
-		syslog(LOG_DEBUG, "%s is on %s", ipbuf,
-				(n->iface) ? n->iface->ifname : "<pending>");
-		if (!n->iface || n->iface == iface)
-			return;
-
-		// Found on other interface, answer with advertisement
-		struct {
-			struct nd_neighbor_advert body;
-			struct nd_opt_hdr opt_ll_hdr;
-			uint8_t mac[6];
-		} advert = {
-			.body = {
-				.nd_na_hdr = {ND_NEIGHBOR_ADVERT,
-					0, 0, {{0}}},
-				.nd_na_target = req->nd_ns_target,
-			},
-			.opt_ll_hdr = {ND_OPT_TARGET_LINKADDR, 1},
-		};
-
-		memcpy(advert.mac, mac, sizeof(advert.mac));
-		advert.body.nd_na_flags_reserved = ND_NA_FLAG_ROUTER |
-				ND_NA_FLAG_SOLICITED;
-
-		struct sockaddr_in6 dest = {AF_INET6, 0, 0, ALL_IPV6_NODES, 0};
-		if (!ns_is_dad) // If not DAD, then unicast to source
-			dest.sin6_addr = ip6->ip6_src;
-
-		// Linux seems to not honor IPV6_PKTINFO on raw-sockets, so work around
-		setsockopt(ping_socket, SOL_SOCKET, SO_BINDTODEVICE,
-					iface->ifname, sizeof(iface->ifname));
-		struct iovec iov = {&advert, sizeof(advert)};
-		odhcpd_send(ping_socket, &dest, &iov, 1, iface);
-	} else {
-		// Send echo to all other interfaces to see where target is on
-		// This will trigger neighbor discovery which is what we want.
-		// We will observe the neighbor cache to see results.
-
-		ssize_t sent = 0;
-		struct interface *c;
-		list_for_each_entry(c, &interfaces, head)
-			if (iface->ndp == RELAYD_RELAY && iface != c &&
-					(!ns_is_dad || !c->external == false))
-				sent += ping6(&req->nd_ns_target, c);
-
-		if (sent > 0) // Sent a ping, add pending neighbor entry
-			modify_neighbor(&req->nd_ns_target, NULL, true);
-	}
+	struct interface *c;
+	list_for_each_entry(c, &interfaces, head)
+		if (iface->ndp == RELAYD_RELAY && iface != c &&
+				(!ns_is_dad || !c->external == false))
+			ping6(&req->nd_ns_target, c);
 }
 
 
@@ -384,74 +297,15 @@ static void setup_route(struct in6_addr *addr, struct interface *iface,
 	odhcpd_setup_route(addr, 128, iface, NULL, add);
 }
 
-static void free_neighbor(struct ndp_neighbor *n)
-{
-	setup_route(&n->addr, n->iface, false);
-	list_del(&n->head);
-	free(n);
-	--neighbor_count;
-}
-
-static struct ndp_neighbor* find_neighbor(struct in6_addr *addr, bool strict)
-{
-	time_t now = time(NULL);
-	struct ndp_neighbor *n, *e;
-	list_for_each_entry_safe(n, e, &neighbors, head) {
-		if ((!strict && !odhcpd_bmemcmp(&n->addr, addr, n->len)) ||
-				(n->len == 128 && IN6_ARE_ADDR_EQUAL(&n->addr, addr)))
-			return n;
-
-		if (!n->iface && abs(n->timeout - now) >= 5)
-			free_neighbor(n);
-	}
-	return NULL;
-}
-
-
-// Modified our own neighbor-entries
-static void modify_neighbor(struct in6_addr *addr,
-		struct interface *iface, bool add)
-{
-	if (!addr || (void*)addr == (void*)iface)
-		return;
-
-	struct ndp_neighbor *n = find_neighbor(addr, true);
-	if (!add) { // Delete action
-		if (n && (!n->iface || n->iface == iface))
-			free_neighbor(n);
-	} else if (!n) { // No entry yet, add one if possible
-		if (neighbor_count >= NDP_MAX_NEIGHBORS ||
-				!(n = malloc(sizeof(*n))))
-			return;
-
-		n->len = 128;
-		n->addr = *addr;
-		n->iface = iface;
-		if (!n->iface)
-			time(&n->timeout);
-		list_add(&n->head, &neighbors);
-		++neighbor_count;
-		setup_route(addr, n->iface, add);
-	} else if (n->iface == iface) {
-		if (!n->iface)
-			time(&n->timeout);
-	} else if (iface && (!n->iface ||
-			(!iface->external && n->iface->external))) {
-		setup_route(addr, n->iface, false);
-		n->iface = iface;
-		setup_route(addr, n->iface, add);
-	}
-	// TODO: In case a host switches interfaces we might want
-	// to set its old neighbor entry to NUD_STALE and ping it
-	// on the old interface to confirm if the MACs match.
-}
-
 
 // Handler for neighbor cache entries from the kernel. This is our source
 // to learn and unlearn hosts on interfaces.
 static void handle_rtnetlink(_unused void *addr, void *data, size_t len,
 		_unused struct interface *iface, _unused void *dest)
 {
+	bool dump_neigh = false;
+	struct in6_addr last_solicited = IN6ADDR_ANY_INIT;
+
 	for (struct nlmsghdr *nh = data; NLMSG_OK(nh, len);
 			nh = NLMSG_NEXT(nh, len)) {
 		struct rtmsg *rtm = NLMSG_DATA(nh);
@@ -506,8 +360,61 @@ static void handle_rtnetlink(_unused void *addr, void *data, size_t len,
 				(NUD_REACHABLE | NUD_STALE | NUD_DELAY | NUD_PROBE
 						| NUD_PERMANENT | NUD_NOARP)));
 
-		if (iface->ndp == RELAYD_RELAY)
-			modify_neighbor(addr, iface, add);
+		if (iface->ndp == RELAYD_RELAY) {
+			// Replay change to all neighbor cache
+			struct {
+				struct nlmsghdr nh;
+				struct ndmsg ndm;
+				struct nlattr nla_dst;
+				struct in6_addr dst;
+			} req = {
+				{sizeof(req), RTM_DELNEIGH, NLM_F_REQUEST,
+						++rtnl_seqid, 0},
+				{.ndm_family = AF_INET6, .ndm_flags = NTF_PROXY},
+				{sizeof(struct nlattr) + sizeof(struct in6_addr), NDA_DST},
+				*addr
+			};
+
+			if (add) {
+				req.nh.nlmsg_type = RTM_NEWNEIGH;
+				req.nh.nlmsg_flags |= NLM_F_CREATE;
+
+				struct interface *c;
+				list_for_each_entry(c, &interfaces, head) {
+					if (c->ndp == RELAYD_RELAY && iface != c) {
+						req.ndm.ndm_ifindex = c->ifindex;
+						send(rtnl_event.uloop.fd, &req, sizeof(req), MSG_DONTWAIT);
+					}
+				}
+
+				setup_route(addr, iface, true);
+			} else {
+				if (nh->nlmsg_type == RTM_NEWNEIGH) {
+					// might be locally originating
+					if (!IN6_ARE_ADDR_EQUAL(&last_solicited, addr)) {
+						last_solicited = *addr;
+
+						struct interface *c;
+						list_for_each_entry(c, &interfaces, head)
+							if (iface->ndp == RELAYD_RELAY && iface != c &&
+									!c->external == false)
+								ping6(addr, c);
+					}
+				} else {
+					struct interface *c;
+					list_for_each_entry(c, &interfaces, head) {
+						if (c->ndp == RELAYD_RELAY && iface != c) {
+							req.ndm.ndm_ifindex = c->ifindex;
+							send(rtnl_event.uloop.fd, &req, sizeof(req), MSG_DONTWAIT);
+						}
+					}
+					setup_route(addr, iface, false);
+
+					// also: dump to add proxies back in case it moved elsewhere
+					dump_neigh = true;
+				}
+			}
+		}
 
 		if (is_addr && iface->ra == RELAYD_SERVER)
 			raise(SIGUSR1); // Inform about a change in addresses
@@ -530,11 +437,17 @@ static void handle_rtnetlink(_unused void *addr, void *data, size_t len,
 				}
 			}
 		}
+	}
 
-		/* TODO: See if this is required for optimal operation
-		// Keep neighbor entries alive so we don't loose routes
-		 */
-		if (add && (ndm->ndm_state & NUD_STALE))
-			ping6(addr, iface);
+	if (dump_neigh) {
+		struct {
+			struct nlmsghdr nh;
+			struct ndmsg ndm;
+		} req = {
+			{sizeof(req), RTM_GETNEIGH, NLM_F_REQUEST | NLM_F_DUMP,
+					++rtnl_seqid, 0},
+			{.ndm_family = AF_INET6}
+		};
+		send(rtnl_event.uloop.fd, &req, sizeof(req), MSG_DONTWAIT);
 	}
 }