X-Git-Url: http://git.meshlink.io/?a=blobdiff_plain;f=src%2Fnet_packet.c;h=8aca6aa59adda1ef8f78d9eecec914625a9a367a;hb=963c5055505f2fc117cd5efa06eaa02c9b2bf85d;hp=8bf41c39405b62d2c1e6e78898d04e5908e81346;hpb=9b129c07e273ae113f3c67a9feeee82e8146f3a1;p=meshlink

diff --git a/src/net_packet.c b/src/net_packet.c
index 8bf41c39..8aca6aa5 100644
--- a/src/net_packet.c
+++ b/src/net_packet.c
@@ -1,7 +1,6 @@
 /*
     net_packet.c -- Handles in- and outgoing VPN packets
-    Copyright (C) 1998-2005 Ivo Timmermans,
-                  2000-2009 Guus Sliepen <guus@tinc-vpn.org>
+    Copyright (C) 2014-2017 Guus Sliepen <guus@meshlink.io>
 
     This program is free software; you can redistribute it and/or modify
     it under the terms of the GNU General Public License as published by
@@ -13,531 +12,569 @@
     MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
     GNU General Public License for more details.
 
-    You should have received a copy of the GNU General Public License
-    along with this program; if not, write to the Free Software
-    Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
-
-    $Id$
+    You should have received a copy of the GNU General Public License along
+    with this program; if not, write to the Free Software Foundation, Inc.,
+    51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
 */
 
 #include "system.h"
 
-#include <zlib.h>
-#include LZO1X_H
-
-#include "splay_tree.h"
-#include "cipher.h"
 #include "conf.h"
 #include "connection.h"
 #include "crypto.h"
-#include "digest.h"
-#include "device.h"
-#include "ethernet.h"
 #include "graph.h"
-#include "list.h"
 #include "logger.h"
+#include "meshlink_internal.h"
 #include "net.h"
 #include "netutl.h"
 #include "protocol.h"
-#include "process.h"
 #include "route.h"
 #include "utils.h"
 #include "xalloc.h"
 
-#ifdef WSAEMSGSIZE
-#define EMSGSIZE WSAEMSGSIZE
-#endif
-
 int keylifetime = 0;
-int keyexpires = 0;
-static char lzo_wrkmem[LZO1X_999_MEM_COMPRESS > LZO1X_1_MEM_COMPRESS ? LZO1X_999_MEM_COMPRESS : LZO1X_1_MEM_COMPRESS];
 
-static void send_udppacket(node_t *, vpn_packet_t *);
+static void send_udppacket(meshlink_handle_t *mesh, node_t *, vpn_packet_t *);
 
 #define MAX_SEQNO 1073741824
 
-static void send_mtu_probe_handler(int fd, short events, void *data) {
+/* mtuprobes == 1..30: initial discovery, send bursts with 1 second interval
+   mtuprobes ==    31: sleep pinginterval seconds
+   mtuprobes ==    32: send 1 burst, sleep pingtimeout second
+   mtuprobes ==    33: no response from other side, restart PMTU discovery process
+
+   Probes are sent in batches of at least three, with random sizes between the
+   lower and upper boundaries for the MTU thus far discovered.
+
+   After the initial discovery, a fourth packet is added to each batch with a
+   size larger than the currently known PMTU, to test if the PMTU has increased.
+
+   In case local discovery is enabled, another packet is added to each batch,
+   which will be broadcast to the local network.
+
+*/
+
+static void send_mtu_probe_handler(event_loop_t *loop, void *data) {
+	meshlink_handle_t *mesh = loop->data;
 	node_t *n = data;
-	vpn_packet_t packet;
-	int len, i;
-	
-	cp();
+	int timeout = 1;
 
 	n->mtuprobes++;
 
-	if(n->mtuprobes >= 10 && !n->minmtu) {
-		ifdebug(TRAFFIC) logger(LOG_INFO, _("No response to MTU probes from %s (%s)"), n->name, n->hostname);
+	if(!n->status.reachable || !n->status.validkey) {
+		logger(mesh, MESHLINK_INFO, "Trying to send MTU probe to unreachable or rekeying node %s", n->name);
+		n->mtuprobes = 0;
 		return;
 	}
 
-	for(i = 0; i < 3; i++) {
-		if(n->mtuprobes >= 30 || n->minmtu >= n->maxmtu) {
-			n->mtu = n->minmtu;
-			ifdebug(TRAFFIC) logger(LOG_INFO, _("Fixing MTU of %s (%s) to %d after %d probes"), n->name, n->hostname, n->mtu, n->mtuprobes);
-			return;
+	if(n->mtuprobes > 32) {
+		if(!n->minmtu) {
+			n->mtuprobes = 31;
+			timeout = mesh->dev_class_traits[n->devclass].pinginterval;
+			goto end;
 		}
 
-		len = n->minmtu + 1 + random() % (n->maxmtu - n->minmtu);
-		if(len < 64)
+		logger(mesh, MESHLINK_INFO, "%s did not respond to UDP ping, restarting PMTU discovery", n->name);
+		n->status.udp_confirmed = false;
+		n->mtuprobes = 1;
+		n->minmtu = 0;
+		n->maxmtu = MTU;
+
+		update_node_pmtu(mesh, n);
+	}
+
+	if(n->mtuprobes >= 10 && n->mtuprobes < 32 && !n->minmtu) {
+		logger(mesh, MESHLINK_INFO, "No response to MTU probes from %s", n->name);
+		n->mtuprobes = 31;
+	}
+
+	if(n->mtuprobes == 30 || (n->mtuprobes < 30 && n->minmtu >= n->maxmtu)) {
+		if(n->minmtu > n->maxmtu) {
+			n->minmtu = n->maxmtu;
+			update_node_pmtu(mesh, n);
+		} else {
+			n->maxmtu = n->minmtu;
+		}
+
+		n->mtu = n->minmtu;
+		logger(mesh, MESHLINK_INFO, "Fixing MTU of %s to %d after %d probes", n->name, n->mtu, n->mtuprobes);
+		n->mtuprobes = 31;
+	}
+
+	if(n->mtuprobes == 31) {
+		if(!n->minmtu && n->status.want_udp) {
+			/* Send a dummy ANS_KEY to try to update the reflexive UDP address */
+			send_request(mesh, n->nexthop->connection, NULL, "%d %s %s . -1 -1 -1 0", ANS_KEY, mesh->self->name, n->name);
+			n->status.want_udp = false;
+		}
+
+		timeout = mesh->dev_class_traits[n->devclass].pinginterval;
+		goto end;
+	} else if(n->mtuprobes == 32) {
+		timeout = mesh->dev_class_traits[n->devclass].pingtimeout;
+	}
+
+	for(int i = 0; i < 5; i++) {
+		int len;
+
+		if(i == 0) {
+			if(n->mtuprobes < 30 || n->maxmtu + 8 >= MTU) {
+				continue;
+			}
+
+			len = n->maxmtu + 8;
+		} else if(n->maxmtu <= n->minmtu) {
+			len = n->maxmtu;
+		} else {
+			len = n->minmtu + 1 + prng(mesh, n->maxmtu - n->minmtu);
+		}
+
+		if(len < 64) {
 			len = 64;
-		
+		}
+
+		vpn_packet_t packet;
+		packet.probe = true;
 		memset(packet.data, 0, 14);
 		randomize(packet.data + 14, len - 14);
 		packet.len = len;
-		packet.priority = 0;
+		n->status.broadcast = i >= 4 && n->mtuprobes <= 10 && n->prevedge;
 
-		ifdebug(TRAFFIC) logger(LOG_INFO, _("Sending MTU probe length %d to %s (%s)"), len, n->name, n->hostname);
+		logger(mesh, MESHLINK_DEBUG, "Sending MTU probe length %d to %s", len, n->name);
 
-		send_udppacket(n, &packet);
+		send_udppacket(mesh, n, &packet);
 	}
 
-	event_add(&n->mtuevent, &(struct timeval){1, 0});
+	n->status.broadcast = false;
+
+end:
+	timeout_set(&mesh->loop, &n->mtutimeout, &(struct timespec) {
+		timeout, prng(mesh, TIMER_FUDGE)
+	});
 }
 
-void send_mtu_probe(node_t *n) {
-	if(!timeout_initialized(&n->mtuevent))
-		timeout_set(&n->mtuevent, send_mtu_probe_handler, n);
-	send_mtu_probe_handler(0, 0, n);
+void send_mtu_probe(meshlink_handle_t *mesh, node_t *n) {
+	timeout_add(&mesh->loop, &n->mtutimeout, send_mtu_probe_handler, n, &(struct timespec) {
+		1, 0
+	});
+	send_mtu_probe_handler(&mesh->loop, n);
 }
 
-void mtu_probe_h(node_t *n, vpn_packet_t *packet, length_t len) {
-	ifdebug(TRAFFIC) logger(LOG_INFO, _("Got MTU probe length %d from %s (%s)"), packet->len, n->name, n->hostname);
+static void mtu_probe_h(meshlink_handle_t *mesh, node_t *n, vpn_packet_t *packet, uint16_t len) {
+	if(len < 64) {
+		logger(mesh, MESHLINK_WARNING, "Got too short MTU probe length %d from %s", packet->len, n->name);
+		return;
+	}
+
+	logger(mesh, MESHLINK_DEBUG, "Got MTU probe length %d from %s", packet->len, n->name);
 
 	if(!packet->data[0]) {
+		/* It's a probe request, send back a reply */
+
 		packet->data[0] = 1;
-		send_packet(n, packet);
-	} else {
-		if(n->minmtu < len)
-			n->minmtu = len;
-	}
-}
 
-static length_t compress_packet(uint8_t *dest, const uint8_t *source, length_t len, int level) {
-	if(level == 10) {
-		lzo_uint lzolen = MAXSIZE;
-		lzo1x_1_compress(source, len, dest, &lzolen, lzo_wrkmem);
-		return lzolen;
-	} else if(level < 10) {
-		unsigned long destlen = MAXSIZE;
-		if(compress2(dest, &destlen, source, len, level) == Z_OK)
-			return destlen;
-		else
-			return -1;
-	} else {
-		lzo_uint lzolen = MAXSIZE;
-		lzo1x_999_compress(source, len, dest, &lzolen, lzo_wrkmem);
-		return lzolen;
-	}
-	
-	return -1;
-}
+		/* Temporarily set udp_confirmed, so that the reply is sent
+		   back exactly the way it came in. */
 
-static length_t uncompress_packet(uint8_t *dest, const uint8_t *source, length_t len, int level) {
-	if(level > 9) {
-		lzo_uint lzolen = MAXSIZE;
-		if(lzo1x_decompress_safe(source, len, dest, &lzolen, NULL) == LZO_E_OK)
-			return lzolen;
-		else
-			return -1;
+		bool udp_confirmed = n->status.udp_confirmed;
+		n->status.udp_confirmed = true;
+		send_udppacket(mesh, n, packet);
+		n->status.udp_confirmed = udp_confirmed;
 	} else {
-		unsigned long destlen = MAXSIZE;
-		if(uncompress(dest, &destlen, source, len) == Z_OK)
-			return destlen;
-		else
-			return -1;
-	}
-	
-	return -1;
-}
+		/* It's a valid reply: now we know bidirectional communication
+		   is possible using the address and socket that the reply
+		   packet used. */
+
+		if(!n->status.udp_confirmed) {
+			char *address, *port;
+			sockaddr2str(&n->address, &address, &port);
+			send_request(mesh, n->nexthop->connection, NULL, "%d %s %s . -1 -1 -1 0 %s %s", ANS_KEY, n->name, n->name, address, port);
+			free(address);
+			free(port);
+			n->status.udp_confirmed = true;
+		}
 
-/* VPN packet I/O */
+		/* If we haven't established the PMTU yet, restart the discovery process. */
+
+		if(n->mtuprobes > 30) {
+			if(len == n->maxmtu + 8) {
+				logger(mesh, MESHLINK_INFO, "Increase in PMTU to %s detected, restarting PMTU discovery", n->name);
+				n->maxmtu = MTU;
+				n->mtuprobes = 10;
+				return;
+			}
 
-static void receive_packet(node_t *n, vpn_packet_t *packet) {
-	cp();
+			if(n->minmtu) {
+				n->mtuprobes = 30;
+			} else {
+				n->mtuprobes = 1;
+			}
+		}
 
-	ifdebug(TRAFFIC) logger(LOG_DEBUG, _("Received packet of %d bytes from %s (%s)"),
-			   packet->len, n->name, n->hostname);
+		/* If applicable, raise the minimum supported MTU */
+
+		if(len > n->maxmtu) {
+			len = n->maxmtu;
+		}
 
-	route(n, packet);
+		if(n->minmtu < len) {
+			n->minmtu = len;
+			update_node_pmtu(mesh, n);
+		}
+	}
 }
 
-static bool try_mac(node_t *n, const vpn_packet_t *inpkt)
-{
-	if(!digest_active(&n->indigest) || inpkt->len < sizeof inpkt->seqno + digest_length(&n->indigest))
-		return false;
+/* VPN packet I/O */
 
-	return digest_verify(&n->indigest, &inpkt->seqno, inpkt->len, (const char *)&inpkt->seqno + inpkt->len);
+static void receive_packet(meshlink_handle_t *mesh, node_t *n, vpn_packet_t *packet) {
+	logger(mesh, MESHLINK_DEBUG, "Received packet of %d bytes from %s", packet->len, n->name);
+
+	if(n->status.blacklisted) {
+		logger(mesh, MESHLINK_WARNING, "Dropping packet from blacklisted node %s", n->name);
+	} else {
+		n->in_packets++;
+		n->in_bytes += packet->len;
+
+		route(mesh, n, packet);
+	}
 }
 
-static void receive_udppacket(node_t *n, vpn_packet_t *inpkt)
-{
-	vpn_packet_t pkt1, pkt2;
-	vpn_packet_t *pkt[] = { &pkt1, &pkt2, &pkt1, &pkt2 };
-	int nextpkt = 0;
-	vpn_packet_t *outpkt = pkt[0];
-	size_t outlen;
-	int i;
+static bool try_mac(meshlink_handle_t *mesh, node_t *n, const vpn_packet_t *inpkt) {
+	(void)mesh;
+	return sptps_verify_datagram(&n->sptps, inpkt->data, inpkt->len);
+}
 
-	cp();
+static void receive_udppacket(meshlink_handle_t *mesh, node_t *n, vpn_packet_t *inpkt) {
+	if(!n->sptps.state) {
+		if(!n->status.waitingforkey) {
+			logger(mesh, MESHLINK_DEBUG, "Got packet from %s but we haven't exchanged keys yet", n->name);
+			send_req_key(mesh, n);
+		} else {
+			logger(mesh, MESHLINK_DEBUG, "Got packet from %s but he hasn't got our key yet", n->name);
+		}
 
-	if(!cipher_active(&n->incipher)) {
-		ifdebug(TRAFFIC) logger(LOG_DEBUG, _("Got packet from %s (%s) but he hasn't got our key yet"),
-					n->name, n->hostname);
 		return;
 	}
 
-	/* Check packet length */
+	if(!sptps_receive_data(&n->sptps, inpkt->data, inpkt->len)) {
+		logger(mesh, MESHLINK_ERROR, "Could not process SPTPS data from %s: %s", n->name, strerror(errno));
+	}
+}
+
+static void send_sptps_packet(meshlink_handle_t *mesh, node_t *n, vpn_packet_t *origpkt) {
+	if(!n->status.validkey) {
+		logger(mesh, MESHLINK_INFO, "No valid key known yet for %s", n->name);
+
+		if(!n->status.waitingforkey) {
+			send_req_key(mesh, n);
+		} else if(n->last_req_key + 10 < mesh->loop.now.tv_sec) {
+			logger(mesh, MESHLINK_DEBUG, "No key from %s after 10 seconds, restarting SPTPS", n->name);
+			sptps_stop(&n->sptps);
+			n->status.waitingforkey = false;
+			send_req_key(mesh, n);
+		}
 
-	if(inpkt->len < sizeof inpkt->seqno + digest_length(&n->indigest)) {
-		ifdebug(TRAFFIC) logger(LOG_DEBUG, _("Got too short packet from %s (%s)"),
-					n->name, n->hostname);
 		return;
 	}
 
-	/* Check the message authentication code */
+	uint8_t type = 0;
 
-	if(digest_active(&n->indigest) && !digest_verify(&n->indigest, &inpkt->seqno, inpkt->len, (const char *)&inpkt->seqno + inpkt->len)) {
-		ifdebug(TRAFFIC) logger(LOG_DEBUG, _("Got unauthenticated packet from %s (%s)"), n->name, n->hostname);
+	// If it's a probe, send it immediately without trying to compress it.
+	if(origpkt->probe) {
+		sptps_send_record(&n->sptps, PKT_PROBE, origpkt->data, origpkt->len);
 		return;
 	}
 
-	/* Decrypt the packet */
+	sptps_send_record(&n->sptps, type, origpkt->data, origpkt->len);
+	return;
+}
 
-	if(cipher_active(&n->incipher)) {
-		outpkt = pkt[nextpkt++];
-		outlen = MAXSIZE;
+static void choose_udp_address(meshlink_handle_t *mesh, const node_t *n, const sockaddr_t **sa, int *sock) {
+	/* Latest guess */
+	*sa = &n->address;
+	*sock = n->sock;
 
-		if(!cipher_decrypt(&n->incipher, &inpkt->seqno, inpkt->len, &outpkt->seqno, &outlen, true)) {
-			ifdebug(TRAFFIC) logger(LOG_DEBUG, _("Error decrypting packet from %s (%s)"), n->name, n->hostname);
-			return;
-		}
-		
-		outpkt->len = outlen;
-		inpkt = outpkt;
-	}
-
-	/* Check the sequence number */
-
-	inpkt->len -= sizeof inpkt->seqno;
-	inpkt->seqno = ntohl(inpkt->seqno);
-
-	if(inpkt->seqno != n->received_seqno + 1) {
-		if(inpkt->seqno >= n->received_seqno + sizeof n->late * 8) {
-			logger(LOG_WARNING, _("Lost %d packets from %s (%s)"),
-					   inpkt->seqno - n->received_seqno - 1, n->name, n->hostname);
-			
-			memset(n->late, 0, sizeof n->late);
-		} else if (inpkt->seqno <= n->received_seqno) {
-			if((n->received_seqno >= sizeof n->late * 8 && inpkt->seqno <= n->received_seqno - sizeof n->late * 8) || !(n->late[(inpkt->seqno / 8) % sizeof n->late] & (1 << inpkt->seqno % 8))) {
-				logger(LOG_WARNING, _("Got late or replayed packet from %s (%s), seqno %d, last received %d"),
-					   n->name, n->hostname, inpkt->seqno, n->received_seqno);
-				return;
-			}
-		} else {
-			for(i = n->received_seqno + 1; i < inpkt->seqno; i++)
-				n->late[(i / 8) % sizeof n->late] |= 1 << i % 8;
-		}
+	/* If the UDP address is confirmed, use it. */
+	if(n->status.udp_confirmed) {
+		return;
 	}
-	
-	n->late[(inpkt->seqno / 8) % sizeof n->late] &= ~(1 << inpkt->seqno % 8);
 
-	if(inpkt->seqno > n->received_seqno)
-		n->received_seqno = inpkt->seqno;
-			
-	if(n->received_seqno > MAX_SEQNO)
-		regenerate_key();
+	/* Send every third packet to n->address; that could be set
+	   to the node's reflexive UDP address discovered during key
+	   exchange. */
 
-	/* Decompress the packet */
+	if(++mesh->udp_choice >= 3) {
+		mesh->udp_choice = 0;
+		return;
+	}
 
-	length_t origlen = inpkt->len;
+	/* Otherwise, address are found in edges to this node.
+	   So we pick a random edge and a random socket. */
 
-	if(n->incompression) {
-		outpkt = pkt[nextpkt++];
+	int i = 0;
+	int j = prng(mesh, n->edge_tree->count);
+	edge_t *candidate = NULL;
 
-		if((outpkt->len = uncompress_packet(outpkt->data, inpkt->data, inpkt->len, n->incompression)) < 0) {
-			ifdebug(TRAFFIC) logger(LOG_ERR, _("Error while uncompressing packet from %s (%s)"),
-				  		 n->name, n->hostname);
-			return;
+	for splay_each(edge_t, e, n->edge_tree) {
+		if(i++ == j) {
+			candidate = e->reverse;
+			break;
 		}
-
-		inpkt = outpkt;
-
-		origlen -= MTU/64 + 20;
 	}
 
-	inpkt->priority = 0;
+	if(candidate) {
+		*sa = &candidate->address;
+		*sock = prng(mesh, mesh->listen_sockets);
+	}
 
-	if(!inpkt->data[12] && !inpkt->data[13])
-		mtu_probe_h(n, inpkt, origlen);
-	else
-		receive_packet(n, inpkt);
+	/* Make sure we have a suitable socket for the chosen address */
+	if(mesh->listen_socket[*sock].sa.sa.sa_family != (*sa)->sa.sa_family) {
+		for(int i = 0; i < mesh->listen_sockets; i++) {
+			if(mesh->listen_socket[i].sa.sa.sa_family == (*sa)->sa.sa_family) {
+				*sock = i;
+				break;
+			}
+		}
+	}
 }
 
-void receive_tcppacket(connection_t *c, char *buffer, int len) {
-	vpn_packet_t outpkt;
+static void choose_broadcast_address(meshlink_handle_t *mesh, const node_t *n, const sockaddr_t **sa, int *sock) {
+	*sock = prng(mesh, mesh->listen_sockets);
+	sockaddr_t *broadcast_sa = &mesh->listen_socket[*sock].broadcast_sa;
 
-	cp();
-
-	outpkt.len = len;
-	if(c->options & OPTION_TCPONLY)
-		outpkt.priority = 0;
-	else
-		outpkt.priority = -1;
-	memcpy(outpkt.data, buffer, len);
+	if(broadcast_sa->sa.sa_family == AF_INET6) {
+		broadcast_sa->in6.sin6_port = n->prevedge->address.in.sin_port;
+	} else {
+		broadcast_sa->in.sin_port = n->prevedge->address.in.sin_port;
+	}
 
-	receive_packet(c->node, &outpkt);
+	*sa = broadcast_sa;
 }
 
-static void send_udppacket(node_t *n, vpn_packet_t *origpkt) {
-	vpn_packet_t pkt1, pkt2;
-	vpn_packet_t *pkt[] = { &pkt1, &pkt2, &pkt1, &pkt2 };
-	vpn_packet_t *inpkt = origpkt;
-	int nextpkt = 0;
-	vpn_packet_t *outpkt;
-	int origlen;
-	size_t outlen;
-	static int priority = 0;
-	int origpriority;
-	int sock;
-
-	cp();
+static void send_udppacket(meshlink_handle_t *mesh, node_t *n, vpn_packet_t *origpkt) {
+	if(!n->status.reachable) {
+		logger(mesh, MESHLINK_INFO, "Trying to send UDP packet to unreachable node %s", n->name);
+		return;
+	}
 
-	/* Make sure we have a valid key */
+	send_sptps_packet(mesh, n, origpkt);
+}
 
-	if(!n->status.validkey) {
-		ifdebug(TRAFFIC) logger(LOG_INFO,
-				   _("No valid key known yet for %s (%s), forwarding via TCP"),
-				   n->name, n->hostname);
+bool send_sptps_data(void *handle, uint8_t type, const void *data, size_t len) {
+	assert(handle);
+	assert(data);
+	assert(len);
 
-		if(!n->status.waitingforkey)
-			send_req_key(n);
+	node_t *to = handle;
+	meshlink_handle_t *mesh = to->mesh;
 
-		n->status.waitingforkey = true;
+	/* Send it via TCP if it is a handshake packet, TCPOnly is in use, or this packet is larger than the MTU. */
 
-		send_tcppacket(n->nexthop->connection, origpkt);
+	if(type >= SPTPS_HANDSHAKE || (type != PKT_PROBE && (len - 21) > to->minmtu)) {
+		char buf[len * 4 / 3 + 5];
+		b64encode(data, buf, len);
 
-		return;
+		/* 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(!to->status.validkey) {
+			return send_request(mesh, to->nexthop->connection, NULL, "%d %s %s %s -1 -1 -1 %d", ANS_KEY, mesh->self->name, to->name, buf, 0);
+		} else {
+			return send_request(mesh, to->nexthop->connection, NULL, "%d %s %s %d %s", REQ_KEY, mesh->self->name, to->name, REQ_SPTPS, buf);
+		}
 	}
 
-	if(n->options & OPTION_PMTU_DISCOVERY && !n->minmtu && (inpkt->data[12] | inpkt->data[13])) {
-		ifdebug(TRAFFIC) logger(LOG_INFO,
-				_("No minimum MTU established yet for %s (%s), forwarding via TCP"),
-				n->name, n->hostname);
+	/* Otherwise, send the packet via UDP */
 
-		send_tcppacket(n->nexthop->connection, origpkt);
+	const sockaddr_t *sa;
+	int sock;
 
-		return;
+	if(to->status.broadcast) {
+		choose_broadcast_address(mesh, to, &sa, &sock);
+	} else {
+		choose_udp_address(mesh, to, &sa, &sock);
 	}
 
-	origlen = inpkt->len;
-	origpriority = inpkt->priority;
-
-	/* Compress the packet */
-
-	if(n->outcompression) {
-		outpkt = pkt[nextpkt++];
+	if(sendto(mesh->listen_socket[sock].udp.fd, data, len, 0, &sa->sa, SALEN(sa->sa)) < 0 && !sockwouldblock(sockerrno)) {
+		if(sockmsgsize(sockerrno)) {
+			if(to->maxmtu >= len) {
+				to->maxmtu = len - 1;
+			}
 
-		if((outpkt->len = compress_packet(outpkt->data, inpkt->data, inpkt->len, n->outcompression)) < 0) {
-			ifdebug(TRAFFIC) logger(LOG_ERR, _("Error while compressing packet to %s (%s)"),
-				   n->name, n->hostname);
-			return;
+			if(to->mtu >= len) {
+				to->mtu = len - 1;
+			}
+		} else {
+			logger(mesh, MESHLINK_WARNING, "Error sending UDP SPTPS packet to %s: %s", to->name, sockstrerror(sockerrno));
+			return false;
 		}
-
-		inpkt = outpkt;
 	}
 
-	/* Add sequence number */
+	return true;
+}
 
-	inpkt->seqno = htonl(++(n->sent_seqno));
-	inpkt->len += sizeof inpkt->seqno;
+bool receive_sptps_record(void *handle, uint8_t type, const void *data, uint16_t len) {
+	assert(handle);
+	assert(!data || len);
 
-	/* Encrypt the packet */
+	node_t *from = handle;
+	meshlink_handle_t *mesh = from->mesh;
 
-	if(cipher_active(&n->outcipher)) {
-		outpkt = pkt[nextpkt++];
-		outlen = MAXSIZE;
+	if(type == SPTPS_HANDSHAKE) {
+		if(!from->status.validkey) {
+			logger(mesh, MESHLINK_INFO, "SPTPS key exchange with %s successful", from->name);
+			from->status.validkey = true;
+			from->status.waitingforkey = false;
 
-		if(!cipher_encrypt(&n->outcipher, &inpkt->seqno, inpkt->len, &outpkt->seqno, &outlen, true)) {
-			ifdebug(TRAFFIC) logger(LOG_ERR, _("Error while encrypting packet to %s (%s)"), n->name, n->hostname);
-			goto end;
+			if(from->utcp) {
+				utcp_reset_timers(from->utcp);
+			}
 		}
 
-		outpkt->len = outlen;
-		inpkt = outpkt;
+		return true;
 	}
 
-	/* Add the message authentication code */
-
-	if(digest_active(&n->outdigest)) {
-		digest_create(&n->outdigest, &inpkt->seqno, inpkt->len, (char *)&inpkt->seqno + inpkt->len);
-		inpkt->len += digest_length(&n->outdigest);
+	if(len > MAXSIZE) {
+		logger(mesh, MESHLINK_ERROR, "Packet from %s larger than maximum supported size (%d > %d)", from->name, len, MAXSIZE);
+		return false;
 	}
 
-	/* Determine which socket we have to use */
-
-	for(sock = 0; sock < listen_sockets; sock++)
-		if(n->address.sa.sa_family == listen_socket[sock].sa.sa.sa_family)
-			break;
-
-	if(sock >= listen_sockets)
-		sock = 0;				/* If none is available, just use the first and hope for the best. */
+	vpn_packet_t inpkt;
 
-	/* Send the packet */
+	if(type == PKT_PROBE) {
+		inpkt.len = len;
+		inpkt.probe = true;
+		memcpy(inpkt.data, data, len);
+		mtu_probe_h(mesh, from, &inpkt, len);
+		return true;
+	} else {
+		inpkt.probe = false;
+	}
 
-#if defined(SOL_IP) && defined(IP_TOS)
-	if(priorityinheritance && origpriority != priority
-	   && listen_socket[sock].sa.sa.sa_family == AF_INET) {
-		priority = origpriority;
-		ifdebug(TRAFFIC) logger(LOG_DEBUG, _("Setting outgoing packet priority to %d"), priority);
-		if(setsockopt(listen_socket[sock].udp, SOL_IP, IP_TOS, &priority, sizeof priority))	/* SO_PRIORITY doesn't seem to work */
-			logger(LOG_ERR, _("System call `%s' failed: %s"), "setsockopt", strerror(errno));
+	if(type & ~(PKT_COMPRESSED)) {
+		logger(mesh, MESHLINK_ERROR, "Unexpected SPTPS record type %d len %d from %s", type, len, from->name);
+		return false;
 	}
-#endif
 
-	if((sendto(listen_socket[sock].udp, (char *) &inpkt->seqno, inpkt->len, 0, &(n->address.sa), SALEN(n->address.sa))) < 0) {
-		if(errno == EMSGSIZE) {
-			if(n->maxmtu >= origlen)
-				n->maxmtu = origlen - 1;
-			if(n->mtu >= origlen)
-				n->mtu = origlen - 1;
-		} else
-			logger(LOG_ERR, _("Error sending packet to %s (%s): %s"), n->name, n->hostname, strerror(errno));
+	if(type & PKT_COMPRESSED) {
+		logger(mesh, MESHLINK_ERROR, "Error while decompressing packet from %s", from->name);
+		return false;
 	}
 
-end:
-	origpkt->len = origlen;
+	memcpy(inpkt.data, data, len); // TODO: get rid of memcpy
+	inpkt.len = len;
+
+	receive_packet(mesh, from, &inpkt);
+	return true;
 }
 
 /*
   send a packet to the given vpn ip.
 */
-void send_packet(const node_t *n, vpn_packet_t *packet) {
-	node_t *via;
-
-	cp();
-
-	if(n == myself) {
-		if(overwrite_mac)
-			 memcpy(packet->data, mymac.x, ETH_ALEN);
-		write_packet(packet);
+void send_packet(meshlink_handle_t *mesh, node_t *n, vpn_packet_t *packet) {
+	if(n == mesh->self) {
+		n->out_packets++;
+		n->out_bytes += packet->len;
+		// TODO: send to application
 		return;
 	}
 
-	ifdebug(TRAFFIC) logger(LOG_ERR, _("Sending packet of %d bytes to %s (%s)"),
-			   packet->len, n->name, n->hostname);
+	logger(mesh, MESHLINK_DEBUG, "Sending packet of %d bytes to %s", packet->len, n->name);
 
 	if(!n->status.reachable) {
-		ifdebug(TRAFFIC) logger(LOG_INFO, _("Node %s (%s) is not reachable"),
-				   n->name, n->hostname);
+		logger(mesh, MESHLINK_WARNING, "Node %s is not reachable", n->name);
 		return;
 	}
 
-	via = (packet->priority == -1 || n->via == myself) ? n->nexthop : n->via;
-
-	if(via != n)
-		ifdebug(TRAFFIC) logger(LOG_INFO, _("Sending packet to %s via %s (%s)"),
-			   n->name, via->name, n->via->hostname);
-
-	if(packet->priority == -1 || ((myself->options | via->options) & OPTION_TCPONLY)) {
-		if(!send_tcppacket(via->connection, packet))
-			terminate_connection(via->connection, true);
-	} else
-		send_udppacket(via, packet);
-}
-
-/* Broadcast a packet using the minimum spanning tree */
-
-void broadcast_packet(const node_t *from, vpn_packet_t *packet) {
-	splay_node_t *node;
-	connection_t *c;
-
-	cp();
-
-	ifdebug(TRAFFIC) logger(LOG_INFO, _("Broadcasting packet of %d bytes from %s (%s)"),
-			   packet->len, from->name, from->hostname);
-
-	if(from != myself) {
-		send_packet(myself, packet);
-
-		// In TunnelServer mode, do not forward broadcast packets.
-                // The MST might not be valid and create loops.
-		if(tunnelserver)
-			return;
-	}
-
-	for(node = connection_tree->head; node; node = node->next) {
-		c = node->data;
+	n->out_packets++;
+	n->out_bytes += packet->len;
+	n->status.want_udp = true;
 
-		if(c->status.active && c->status.mst && c != from->nexthop->connection)
-			send_packet(c->node, packet);
-	}
+	send_sptps_packet(mesh, n, packet);
+	return;
 }
 
-static node_t *try_harder(const sockaddr_t *from, const vpn_packet_t *pkt) {
-	splay_node_t *node;
-	edge_t *e;
+static node_t *try_harder(meshlink_handle_t *mesh, const sockaddr_t *from, const vpn_packet_t *pkt) {
 	node_t *n = NULL;
+	bool hard = false;
 
-	for(node = edge_weight_tree->head; node; node = node->next) {
-		e = node->data;
-
-		if(sockaddrcmp_noport(from, &e->address))
+	for splay_each(edge_t, e, mesh->edges) {
+		if(!e->to->status.reachable || e->to == mesh->self) {
 			continue;
+		}
+
+		if(sockaddrcmp_noport(from, &e->address)) {
+			if(mesh->last_hard_try == mesh->loop.now.tv_sec) {
+				continue;
+			}
 
-		if(!n)
-			n = e->to;
+			hard = true;
+		}
 
-		if(!try_mac(e->to, pkt))
+		if(!try_mac(mesh, e->to, pkt)) {
 			continue;
+		}
 
 		n = e->to;
 		break;
 	}
 
+	if(hard) {
+		mesh->last_hard_try = mesh->loop.now.tv_sec;
+	}
+
 	return n;
 }
 
-void handle_incoming_vpn_data(int sock, short events, void *data)
-{
+void handle_incoming_vpn_data(event_loop_t *loop, void *data, int flags) {
+	(void)flags;
+	meshlink_handle_t *mesh = loop->data;
+	listen_socket_t *ls = data;
 	vpn_packet_t pkt;
 	char *hostname;
 	sockaddr_t from;
-	socklen_t fromlen = sizeof from;
+	socklen_t fromlen = sizeof(from);
 	node_t *n;
+	int len;
 
-	cp();
+	memset(&from, 0, sizeof(from));
 
-	pkt.len = recvfrom(sock, (char *) &pkt.seqno, MAXSIZE, 0, &from.sa, &fromlen);
+	len = recvfrom(ls->udp.fd, pkt.data, MAXSIZE, 0, &from.sa, &fromlen);
+
+	if(len <= 0 || len > MAXSIZE) {
+		if(!sockwouldblock(sockerrno)) {
+			logger(mesh, MESHLINK_ERROR, "Receiving packet failed: %s", sockstrerror(sockerrno));
+		}
 
-	if(pkt.len < 0) {
-		logger(LOG_ERR, _("Receiving packet failed: %s"), strerror(errno));
 		return;
 	}
 
-	sockaddrunmap(&from);		/* Some braindead IPv6 implementations do stupid things. */
+	pkt.len = len;
+
+	sockaddrunmap(&from); /* Some braindead IPv6 implementations do stupid things. */
 
-	n = lookup_node_udp(&from);
+	n = lookup_node_udp(mesh, &from);
 
 	if(!n) {
-		n = try_harder(&from, &pkt);
-		if(n)
-			update_node_udp(n, &from);
-		else ifdebug(PROTOCOL) {
+		n = try_harder(mesh, &from, &pkt);
+
+		if(n) {
+			update_node_udp(mesh, n, &from);
+		} else if(mesh->log_level <= MESHLINK_WARNING) {
 			hostname = sockaddr2hostname(&from);
-			logger(LOG_WARNING, _("Received UDP packet from unknown source %s"), hostname);
+			logger(mesh, MESHLINK_WARNING, "Received UDP packet from unknown source %s", hostname);
 			free(hostname);
 			return;
-		}
-		else
+		} else {
 			return;
+		}
 	}
 
-	receive_udppacket(n, &pkt);
-}
+	if(n->status.blacklisted) {
+		logger(mesh, MESHLINK_WARNING, "Dropping packet from blacklisted node %s", n->name);
+		return;
+	}
 
-void handle_device_data(int sock, short events, void *data) {
-	vpn_packet_t packet;
+	n->sock = ls - mesh->listen_socket;
 
-	if(read_packet(&packet))
-		route(myself, &packet);
+	receive_udppacket(mesh, n, &pkt);
 }