X-Git-Url: https://tinc-vpn.org/git/browse?p=tinc;a=blobdiff_plain;f=src%2Fnet_packet.c;h=6f72e05b3380d4102c19521dbd178d36b02d2375;hp=e9e2172c67f8ef6a5d44c3dc4d15312807d61cc5;hb=bdd84660c756437cf3bc8f64adf612055acc84ea;hpb=ae5b56c03d1e1af7561d7f1d1d8a333c3a9691ff

diff --git a/src/net_packet.c b/src/net_packet.c
index e9e2172c..6f72e05b 100644
--- a/src/net_packet.c
+++ b/src/net_packet.c
@@ -64,7 +64,7 @@ static char lzo_wrkmem[LZO1X_999_MEM_COMPRESS > LZO1X_1_MEM_COMPRESS ? LZO1X_999
 
 static void send_udppacket(node_t *, vpn_packet_t *);
 
-unsigned replaywin = 16;
+unsigned replaywin = 32;
 bool localdiscovery = true;
 bool udp_discovery = true;
 int udp_discovery_keepalive_interval = 10;
@@ -257,10 +257,10 @@ static bool try_mac(node_t *n, const vpn_packet_t *inpkt) {
 #ifdef DISABLE_LEGACY
 	return false;
 #else
-	if(!digest_active(n->indigest) || inpkt->len < sizeof(seqno_t) + digest_length(n->indigest))
+	if(!n->status.validkey_in || !digest_active(n->indigest) || inpkt->len < sizeof(seqno_t) + digest_length(n->indigest))
 		return false;
 
-	return digest_verify(n->indigest, SEQNO(inpkt), inpkt->len - digest_length(n->indigest), DATA(inpkt) + inpkt->len - digest_length(n->indigest));
+	return digest_verify(n->indigest, inpkt->data, inpkt->len - digest_length(n->indigest), inpkt->data + inpkt->len - digest_length(n->indigest));
 #endif
 }
 
@@ -282,13 +282,19 @@ static bool receive_udppacket(node_t *n, vpn_packet_t *inpkt) {
 			}
 			return false;
 		}
-		inpkt->offset += 2 * sizeof(node_id_t);
 		n->status.udppacket = true;
-		bool result = sptps_receive_data(&n->sptps, DATA(inpkt), inpkt->len - 2 * sizeof(node_id_t));
+		bool result = sptps_receive_data(&n->sptps, DATA(inpkt), inpkt->len);
 		n->status.udppacket = false;
 
 		if(!result) {
-			logger(DEBUG_TRAFFIC, LOG_ERR, "Got bad packet from %s (%s)", n->name, n->hostname);
+			/* Uh-oh. It might be that the tunnel is stuck in some corrupted state,
+			   so let's restart SPTPS in case that helps. But don't do that too often
+			   to prevent storms, and because that would make life a little too easy
+			   for external attackers trying to DoS us. */
+			if(n->last_req_key < now.tv_sec - 10) {
+				logger(DEBUG_PROTOCOL, LOG_ERR, "Failed to decode raw TCP packet from %s (%s), restarting SPTPS", n->name, n->hostname);
+				send_req_key(n);
+			}
 			return false;
 		}
 		return true;
@@ -428,6 +434,64 @@ void receive_tcppacket(connection_t *c, const char *buffer, int len) {
 	receive_packet(c->node, &outpkt);
 }
 
+bool receive_tcppacket_sptps(connection_t *c, const char *data, int len) {
+	if (len < sizeof(node_id_t) + sizeof(node_id_t)) {
+		logger(DEBUG_ALWAYS, LOG_ERR, "Got too short TCP SPTPS packet from %s (%s)", c->name, c->hostname);
+		return false;
+	}
+
+	node_t *to = lookup_node_id((node_id_t *)data);
+	data += sizeof(node_id_t); len -= sizeof(node_id_t);
+	if(!to) {
+		logger(DEBUG_PROTOCOL, LOG_ERR, "Got TCP SPTPS packet from %s (%s) with unknown destination ID", c->name, c->hostname);
+		return true;
+	}
+
+	node_t *from = lookup_node_id((node_id_t *)data);
+	data += sizeof(node_id_t); len -= sizeof(node_id_t);
+	if(!from) {
+		logger(DEBUG_PROTOCOL, LOG_ERR, "Got TCP SPTPS packet from %s (%s) with unknown source ID", c->name, c->hostname);
+		return true;
+	}
+
+	if(!to->status.reachable) {
+		/* This can happen in the form of a race condition
+		   if the node just became unreachable. */
+		logger(DEBUG_TRAFFIC, LOG_WARNING, "Cannot relay TCP packet from %s (%s) because the destination, %s (%s), is unreachable", from->name, from->hostname, to->name, to->hostname);
+		return true;
+	}
+
+	/* Help the sender reach us over UDP.
+	   Note that we only do this if we're the destination or the static relay;
+	   otherwise every hop would initiate its own UDP info message, resulting in elevated chatter. */
+	if(to->via == myself)
+		send_udp_info(myself, from);
+
+	/* If we're not the final recipient, relay the packet. */
+
+	if(to != myself) {
+		send_sptps_data(to, from, 0, data, len);
+		try_tx(to, true);
+		return true;
+	}
+
+	/* The packet is for us */
+
+	if(!sptps_receive_data(&from->sptps, data, len)) {
+		/* Uh-oh. It might be that the tunnel is stuck in some corrupted state,
+		   so let's restart SPTPS in case that helps. But don't do that too often
+		   to prevent storms. */
+		if(from->last_req_key < now.tv_sec - 10) {
+			logger(DEBUG_PROTOCOL, LOG_ERR, "Failed to decode raw TCP packet from %s (%s), restarting SPTPS", from->name, from->hostname);
+			send_req_key(from);
+		}
+		return true;
+	}
+
+	send_mtu_info(myself, from, MTU);
+	return true;
+}
+
 static void send_sptps_packet(node_t *n, vpn_packet_t *origpkt) {
 	if(!n->status.validkey && !n->connection)
 		return;
@@ -681,26 +745,34 @@ end:
 #endif
 }
 
-static bool send_sptps_data_priv(node_t *to, node_t *from, int type, const void *data, size_t len) {
+bool send_sptps_data(node_t *to, node_t *from, int type, const void *data, size_t len) {
 	node_t *relay = (to->via != myself && (type == PKT_PROBE || (len - SPTPS_DATAGRAM_OVERHEAD) <= to->via->minmtu)) ? to->via : to->nexthop;
 	bool direct = from == myself && to == relay;
 	bool relay_supported = (relay->options >> 24) >= 4;
 	bool tcponly = (myself->options | relay->options) & OPTION_TCPONLY;
 
-	/* Send it via TCP if it is a handshake packet, TCPOnly is in use, this is a relay packet that the other node cannot understand, or this packet is larger than the MTU.
-	   TODO: When relaying, the original sender does not know the end-to-end PMTU (it only knows the PMTU of the first hop).
-	         This can lead to scenarios where large packets are sent over UDP to relay, but then relay has no choice but fall back to TCP. */
+	/* Send it via TCP if it is a handshake packet, TCPOnly is in use, this is a relay packet that the other node cannot understand, or this packet is larger than the MTU. */
 
 	if(type == SPTPS_HANDSHAKE || tcponly || (!direct && !relay_supported) || (type != PKT_PROBE && (len - SPTPS_DATAGRAM_OVERHEAD) > relay->minmtu)) {
+		if(type != SPTPS_HANDSHAKE && (to->nexthop->connection->options >> 24) >= 7) {
+			char buf[len + sizeof to->id + sizeof from->id]; char* buf_ptr = buf;
+			memcpy(buf_ptr, &to->id, sizeof to->id); buf_ptr += sizeof to->id;
+			memcpy(buf_ptr, &from->id, sizeof from->id); buf_ptr += sizeof from->id;
+			memcpy(buf_ptr, data, len); buf_ptr += len;
+			logger(DEBUG_TRAFFIC, LOG_INFO, "Sending packet from %s (%s) to %s (%s) via %s (%s) (TCP)", from->name, from->hostname, to->name, to->hostname, to->nexthop->name, to->nexthop->hostname);
+			return send_sptps_tcppacket(to->nexthop->connection, buf, sizeof buf);
+		}
+
 		char buf[len * 4 / 3 + 5];
 		b64encode(data, buf, len);
-		/* If no valid key is known yet, send the packets using ANS_KEY requests,
-		   to ensure we get to learn the reflexive UDP address. */
-		if(from == myself && !to->status.validkey) {
+		/* If this is a handshake packet, use ANS_KEY instead of REQ_KEY, for two reasons:
+		    - We don't want intermediate nodes to switch to UDP to relay these packets;
+		    - ANS_KEY allows us to learn the reflexive UDP address. */
+		if(type == SPTPS_HANDSHAKE) {
 			to->incompression = myself->incompression;
 			return send_request(to->nexthop->connection, "%d %s %s %s -1 -1 -1 %d", ANS_KEY, from->name, to->name, buf, to->incompression);
 		} else {
-			return send_request(to->nexthop->connection, "%d %s %s %d %s", REQ_KEY, from->name, to->name, REQ_SPTPS, buf);
+			return send_request(to->nexthop->connection, "%d %s %s %d %s", REQ_KEY, from->name, to->name, SPTPS_PACKET, buf);
 		}
 	}
 
@@ -727,7 +799,7 @@ static bool send_sptps_data_priv(node_t *to, node_t *from, int type, const void
 		choose_local_address(relay, &sa, &sock);
 	if(!sa)
 		choose_udp_address(relay, &sa, &sock);
-	logger(DEBUG_TRAFFIC, LOG_INFO, "Sending packet from %s (%s) to %s (%s) via %s (%s)", from->name, from->hostname, to->name, to->hostname, relay->name, relay->hostname);
+	logger(DEBUG_TRAFFIC, LOG_INFO, "Sending packet from %s (%s) to %s (%s) via %s (%s) (UDP)", from->name, from->hostname, to->name, to->hostname, relay->name, relay->hostname);
 	if(sendto(listen_socket[sock].udp.fd, buf, buf_ptr - buf, 0, &sa->sa, SALEN(sa->sa)) < 0 && !sockwouldblock(sockerrno)) {
 		if(sockmsgsize(sockerrno)) {
 			// Compensate for SPTPS overhead
@@ -746,10 +818,6 @@ static bool send_sptps_data_priv(node_t *to, node_t *from, int type, const void
 	return true;
 }
 
-bool send_sptps_data(void *handle, uint8_t type, const void *data, size_t len) {
-	return send_sptps_data_priv(handle, myself, type, data, len);
-}
-
 bool receive_sptps_record(void *handle, uint8_t type, const void *data, uint16_t len) {
 	node_t *from = handle;
 
@@ -958,6 +1026,7 @@ static length_t choose_initial_maxmtu(node_t *n) {
 		mtu -= SPTPS_DATAGRAM_OVERHEAD;
 		if((n->options >> 24) >= 4)
 			mtu -= sizeof(node_id_t) + sizeof(node_id_t);
+#ifndef DISABLE_LEGACY
 	} else {
 		mtu -= digest_length(n->outdigest);
 
@@ -977,6 +1046,7 @@ static length_t choose_initial_maxmtu(node_t *n) {
 		}
 
 		mtu -= 4; // seqno
+#endif
 	}
 
 	if (mtu < 512) {
@@ -1123,23 +1193,29 @@ static void try_tx_sptps(node_t *n, bool mtu) {
 
 	try_sptps(n);
 
-	/* Do we need to relay packets? */
+	/* Do we need to statically relay packets? */
 
 	node_t *via = (n->via == myself) ? n->nexthop : n->via;
 
-	/* If the relay doesn't support SPTPS, everything goes via TCP anyway. */
+	/* If we do have a static relay, try everything with that one instead, if it supports relaying. */
 
-	if((via->options >> 24) < 4)
-		return;
-
-	/* If we do have a relay, try everything with that one instead. */
+	if(via != n) {
+		if((via->options >> 24) < 4)
+			return;
+		return try_tx(via, mtu);
+	}
 
-	if(via != n)
-		return try_tx_sptps(via, mtu);
+	/* Otherwise, try to establish UDP connectivity. */
 
 	try_udp(n);
 	if(mtu)
 		try_mtu(n);
+
+	/* If we don't have UDP connectivity (yet), we need to use a dynamic relay (nexthop)
+	   while we try to establish direct connectivity. */
+
+	if(!n->status.udp_confirmed && n != n->nexthop && (n->nexthop->options >> 24) >= 4)
+		try_tx(n->nexthop, mtu);
 }
 
 static void try_tx_legacy(node_t *n, bool mtu) {
@@ -1164,6 +1240,8 @@ static void try_tx_legacy(node_t *n, bool mtu) {
 }
 
 void try_tx(node_t *n, bool mtu) {
+	if(!n->status.reachable)
+		return;
 	if(n->status.sptps)
 		try_tx_sptps(n, mtu);
 	else
@@ -1174,8 +1252,12 @@ void send_packet(node_t *n, vpn_packet_t *packet) {
 	// If it's for myself, write it to the tun/tap device.
 
 	if(n == myself) {
-		if(overwrite_mac)
+		if(overwrite_mac) {
 			 memcpy(DATA(packet), mymac.x, ETH_ALEN);
+			 // Use an arbitrary fake source address.
+			 memcpy(DATA(packet) + ETH_ALEN, DATA(packet), ETH_ALEN);
+			 DATA(packet)[ETH_ALEN * 2 - 1] ^= 0xFF;
+		}
 		n->out_packets++;
 		n->out_bytes += packet->len;
 		devops.write(packet);
@@ -1200,7 +1282,7 @@ void send_packet(node_t *n, vpn_packet_t *packet) {
 
 	if(n->status.sptps) {
 		send_sptps_packet(n, packet);
-		try_tx_sptps(n, true);
+		try_tx(n, true);
 		return;
 	}
 
@@ -1220,7 +1302,7 @@ void send_packet(node_t *n, vpn_packet_t *packet) {
 	}
 
 	send_udppacket(via, packet);
-	try_tx_legacy(via, true);
+	try_tx(via, true);
 }
 
 void broadcast_packet(const node_t *from, vpn_packet_t *packet) {
@@ -1263,33 +1345,52 @@ void broadcast_packet(const node_t *from, vpn_packet_t *packet) {
 	}
 }
 
+/* We got a packet from some IP address, but we don't know who sent it.  Try to
+   verify the message authentication code against all active session keys.
+   Since this is actually an expensive operation, we only do a full check once
+   a minute, the rest of the time we only check against nodes for which we know
+   an IP address that matches the one from the packet.  */
+
 static node_t *try_harder(const sockaddr_t *from, const vpn_packet_t *pkt) {
-	node_t *n = NULL;
+	node_t *match = NULL;
 	bool hard = false;
 	static time_t last_hard_try = 0;
 
-	for splay_each(edge_t, e, edge_weight_tree) {
-		if(!e->to->status.reachable || e->to == myself)
+	for splay_each(node_t, n, node_tree) {
+		if(!n->status.reachable || n == myself)
+			continue;
+
+		if(!n->status.validkey_in && !(n->status.sptps && n->sptps.instate))
 			continue;
 
-		if(sockaddrcmp_noport(from, &e->address)) {
+		bool soft = false;
+
+		for splay_each(edge_t, e, n->edge_tree) {
+			if(!e->reverse)
+				continue;
+			if(!sockaddrcmp_noport(from, &e->reverse->address)) {
+				soft = true;
+				break;
+			}
+		}
+
+		if(!soft) {
 			if(last_hard_try == now.tv_sec)
 				continue;
 			hard = true;
 		}
 
-		if(!try_mac(e->to, pkt))
+		if(!try_mac(n, pkt))
 			continue;
 
-		n = e->to;
+		match = n;
 		break;
 	}
 
 	if(hard)
 		last_hard_try = now.tv_sec;
 
-	last_hard_try = now.tv_sec;
-	return n;
+	return match;
 }
 
 void handle_incoming_vpn_data(void *data, int flags) {
@@ -1319,6 +1420,9 @@ void handle_incoming_vpn_data(void *data, int flags) {
 
 	node_t *n = lookup_node_udp(&addr);
 
+	if(n && !n->status.udp_confirmed)
+		n = NULL; // Don't believe it if we don't have confirmation yet.
+
 	if(!n) {
 		// It might be from a 1.1 node, which might have a source ID in the packet.
 		pkt.offset = 2 * sizeof(node_id_t);
@@ -1346,10 +1450,16 @@ skip_harder:
 		return;
 	}
 
+	pkt.offset = 0;
+
 	if(n->status.sptps) {
-		pkt.offset = 2 * sizeof(node_id_t);
+		bool relay_enabled = (n->options >> 24) >= 4;
+		if (relay_enabled) {
+			pkt.offset = 2 * sizeof(node_id_t);
+			pkt.len -= pkt.offset;
+		}
 
-		if(!memcmp(DSTID(&pkt), &nullid, sizeof nullid)) {
+		if(!memcmp(DSTID(&pkt), &nullid, sizeof nullid) || !relay_enabled) {
 			direct = true;
 			from = n;
 			to = myself;
@@ -1362,8 +1472,27 @@ skip_harder:
 			return;
 		}
 
+		if(!to->status.reachable) {
+			/* This can happen in the form of a race condition
+			   if the node just became unreachable. */
+			logger(DEBUG_TRAFFIC, LOG_WARNING, "Cannot relay packet from %s (%s) because the destination, %s (%s), is unreachable", from->name, from->hostname, to->name, to->hostname);
+			return;
+		}
+
+		/* The packet is supposed to come from the originator or its static relay
+		   (i.e. with no dynamic relays in between).
+		   If it did not, "help" the static relay by sending it UDP info.
+		   Note that we only do this if we're the destination or the static relay;
+		   otherwise every hop would initiate its own UDP info message, resulting in elevated chatter. */
+
+		if(n != from->via && to->via == myself)
+			send_udp_info(myself, from);
+
+		/* If we're not the final recipient, relay the packet. */
+
 		if(to != myself) {
-			send_sptps_data_priv(to, n, 0, DATA(&pkt), pkt.len - 2 * sizeof(node_id_t));
+			send_sptps_data(to, from, 0, DATA(&pkt), pkt.len);
+			try_tx(to, true);
 			return;
 		}
 	} else {
@@ -1371,13 +1500,18 @@ skip_harder:
 		from = n;
 	}
 
-	pkt.offset = 0;
 	if(!receive_udppacket(from, &pkt))
 		return;
 
 	n->sock = ls - listen_socket;
 	if(direct && sockaddrcmp(&addr, &n->address))
 		update_node_udp(n, &addr);
+
+	/* If the packet went through a relay, help the sender find the appropriate MTU
+	   through the relay path. */
+
+	if(!direct)
+		send_mtu_info(myself, n, MTU);
 }
 
 void handle_device_data(void *data, int flags) {