X-Git-Url: http://git.meshlink.io/?a=blobdiff_plain;f=src%2Fnet_packet.c;h=953887a53d3eed52c741c76712fb7ccffb42f263;hb=529b8fab8c21e7ae5af91d742ff202eab38e51f3;hp=691260edd072d398fa47035531d851475f8e1a37;hpb=78e88521845ae3bdd963ae5a414cb9c251963fa2;p=meshlink

diff --git a/src/net_packet.c b/src/net_packet.c
index 691260ed..953887a5 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) 1998-2002 Ivo Timmermans <itimmermans@bigfoot.com>,
-                  2000-2002 Guus Sliepen <guus@sliepen.warande.net>
+    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
@@ -13,420 +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: net_packet.c,v 1.1.2.16 2002/06/08 14:08:57 guus Exp $
+    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 "config.h"
-
-#include <errno.h>
-#include <fcntl.h>
-#include <netdb.h>
-#include <netinet/in.h>
-#ifdef HAVE_NETINET_IN_SYSTM_H
- #include <netinet/in_systm.h>
-#endif
-#ifdef HAVE_NETINET_IP_H
- #include <netinet/ip.h>
-#endif
-#ifdef HAVE_NETINET_TCP_H
- #include <netinet/tcp.h>
-#endif
-#include <stdio.h>
-#include <stdlib.h>
-#include <string.h>
-#include <signal.h>
-#include <sys/time.h>
-#include <sys/types.h>
-#include <syslog.h>
-#include <unistd.h>
-#include <sys/ioctl.h>
-/* SunOS really wants sys/socket.h BEFORE net/if.h,
-   and FreeBSD wants these lines below the rest. */
-#include <arpa/inet.h>
-#include <sys/socket.h>
-#include <net/if.h>
-
-#include <openssl/rand.h>
-#include <openssl/evp.h>
-#include <openssl/pem.h>
-#include <openssl/hmac.h>
-
-#include <zlib.h>
-
-#include <utils.h>
-#include <xalloc.h>
-#include <avl_tree.h>
-#include <list.h>
+#include "system.h"
 
 #include "conf.h"
 #include "connection.h"
-#include "meta.h"
+#include "crypto.h"
+#include "graph.h"
+#include "logger.h"
+#include "meshlink_internal.h"
 #include "net.h"
 #include "netutl.h"
-#include "process.h"
 #include "protocol.h"
-#include "subnet.h"
-#include "graph.h"
-#include "process.h"
 #include "route.h"
-#include "device.h"
-#include "event.h"
-
-#include "system.h"
+#include "utils.h"
+#include "xalloc.h"
 
 int keylifetime = 0;
-int keyexpires = 0;
+
+static void send_udppacket(meshlink_handle_t *mesh, node_t *, vpn_packet_t *);
 
 #define MAX_SEQNO 1073741824
 
+/* 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;
+	int timeout = 1;
+
+	n->mtuprobes++;
+
+	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;
+	}
+
+	if(n->mtuprobes > 32) {
+		if(!n->minmtu) {
+			n->mtuprobes = 31;
+			timeout = mesh->dev_class_traits[n->devclass].pinginterval;
+			goto end;
+		}
+
+		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;
+		n->status.broadcast = i >= 4 && n->mtuprobes <= 10 && n->prevedge;
+
+		logger(mesh, MESHLINK_DEBUG, "Sending MTU probe length %d to %s", len, n->name);
+
+		send_udppacket(mesh, n, &packet);
+	}
+
+	n->status.broadcast = false;
+
+end:
+	timeout_set(&mesh->loop, &n->mtutimeout, &(struct timeval) {
+		timeout, prng(mesh, TIMER_FUDGE)
+	});
+}
+
+void send_mtu_probe(meshlink_handle_t *mesh, node_t *n) {
+	timeout_add(&mesh->loop, &n->mtutimeout, send_mtu_probe_handler, n, &(struct timeval) {
+		1, 0
+	});
+	send_mtu_probe_handler(&mesh->loop, n);
+}
+
+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;
+
+		/* Temporarily set udp_confirmed, so that the reply is sent
+		   back exactly the way it came in. */
+
+		bool udp_confirmed = n->status.udp_confirmed;
+		n->status.udp_confirmed = true;
+		send_udppacket(mesh, n, packet);
+		n->status.udp_confirmed = udp_confirmed;
+	} else {
+		/* 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;
+		}
+
+		/* 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;
+			}
+
+			if(n->minmtu) {
+				n->mtuprobes = 30;
+			} else {
+				n->mtuprobes = 1;
+			}
+		}
+
+		/* If applicable, raise the minimum supported MTU */
+
+		if(len > n->maxmtu) {
+			len = n->maxmtu;
+		}
+
+		if(n->minmtu < len) {
+			n->minmtu = len;
+			update_node_pmtu(mesh, n);
+		}
+	}
+}
+
 /* VPN packet I/O */
 
-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];
-  int outlen, outpad;
-  long int complen = MTU + 12;
-  EVP_CIPHER_CTX ctx;
-  char hmac[EVP_MAX_MD_SIZE];
-cp
-  /* Check the message authentication code */
-
-  if(myself->digest && myself->maclength)
-    {
-      inpkt->len -= myself->maclength;
-      HMAC(myself->digest, myself->key, myself->keylength, (char *)&inpkt->seqno, inpkt->len, hmac, NULL);
-      if(memcmp(hmac, (char *)&inpkt->seqno + inpkt->len, myself->maclength))
-        {
-          if(debug_lvl >= DEBUG_TRAFFIC)
-            syslog(LOG_DEBUG, _("Got unauthenticated packet from %s (%s)"), n->name, n->hostname);
-          return;
-        }
-    }
-
-  /* Decrypt the packet */
-
-  if(myself->cipher)
-  {
-    outpkt = pkt[nextpkt++];
-
-    EVP_DecryptInit(&ctx, myself->cipher, myself->key, myself->key + myself->cipher->key_len);
-    EVP_DecryptUpdate(&ctx, (char *)&outpkt->seqno, &outlen, (char *)&inpkt->seqno, inpkt->len);
-    EVP_DecryptFinal(&ctx, (char *)&outpkt->seqno + outlen, &outpad);
-
-    outpkt->len = outlen + outpad;
-    inpkt = outpkt;
-  }
-
-  /* Check the sequence number */
-
-  inpkt->len -= sizeof(inpkt->seqno);
-  inpkt->seqno = ntohl(inpkt->seqno);
-
-  if(inpkt->seqno <= n->received_seqno)
-  {
-    if(debug_lvl >= DEBUG_TRAFFIC)
-      syslog(LOG_DEBUG, _("Got late or replayed packet from %s (%s), seqno %d"), n->name, n->hostname, inpkt->seqno);
-    return;
-  }
-  
-  n->received_seqno = inpkt->seqno;
-
-  if(n->received_seqno > MAX_SEQNO)
-    keyexpires = 0;
-
-  /* Decompress the packet */
-  
-  if(myself->compression)
-  {
-    outpkt = pkt[nextpkt++];
-
-    if(uncompress(outpkt->data, &complen, inpkt->data, inpkt->len) != Z_OK)
-    {
-      syslog(LOG_ERR, _("Error while uncompressing packet from %s (%s)"), n->name, n->hostname);
-      return;
-    }
-    
-    outpkt->len = complen;
-    inpkt = outpkt;
-  }
-
-  receive_packet(n, inpkt);
-cp
+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);
+	}
 }
 
-void receive_tcppacket(connection_t *c, char *buffer, int len)
-{
-  vpn_packet_t outpkt;
-cp
-  outpkt.len = len;
-  memcpy(outpkt.data, buffer, len);
+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);
+}
 
-  receive_packet(c->node, &outpkt);
-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);
+		}
+
+		return;
+	}
+
+	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));
+	}
 }
 
-void receive_packet(node_t *n, vpn_packet_t *packet)
-{
-cp
-  if(debug_lvl >= DEBUG_TRAFFIC)
-    syslog(LOG_DEBUG, _("Received packet of %d bytes from %s (%s)"), packet->len, n->name, n->hostname);
+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);
 
-  route_incoming(n, packet);
-cp
+		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);
+		}
+
+		return;
+	}
+
+	uint8_t type = 0;
+
+	// 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;
+	}
+
+	sptps_send_record(&n->sptps, type, origpkt->data, origpkt->len);
+	return;
 }
 
-void send_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;
-  int origlen;
-  int outlen, outpad;
-  long int complen = MTU + 12;
-  EVP_CIPHER_CTX ctx;
-  vpn_packet_t *copy;
-  static int priority = 0;
-  int origpriority;
-  int sock;
-cp
-  /* Make sure we have a valid key */
-
-  if(!n->status.validkey)
-    {
-      if(debug_lvl >= DEBUG_TRAFFIC)
-        syslog(LOG_INFO, _("No valid key known yet for %s (%s), queueing packet"),
-               n->name, n->hostname);
-
-      /* Since packet is on the stack of handle_tap_input(),
-         we have to make a copy of it first. */
-
-      copy = xmalloc(sizeof(vpn_packet_t));
-      memcpy(copy, inpkt, sizeof(vpn_packet_t));
-
-      list_insert_tail(n->queue, copy);
-
-      if(n->queue->count > MAXQUEUELENGTH)
-        list_delete_head(n->queue);
-
-      if(!n->status.waitingforkey)
-        send_req_key(n->nexthop->connection, myself, n);
-
-      n->status.waitingforkey = 1;
-
-      return;
-    }
-
-  origlen = inpkt->len;
-  origpriority = inpkt->priority;
-
-  /* Compress the packet */
-
-  if(n->compression)
-  {
-    outpkt = pkt[nextpkt++];
-
-    if(compress2(outpkt->data, &complen, inpkt->data, inpkt->len, n->compression) != Z_OK)
-    {
-      syslog(LOG_ERR, _("Error while compressing packet to %s (%s)"), n->name, n->hostname);
-      return;
-    }
-    
-    outpkt->len = complen;
-    inpkt = outpkt;
-  }
-
-  /* Add sequence number */
-
-  inpkt->seqno = htonl(++(n->sent_seqno));
-  inpkt->len += sizeof(inpkt->seqno);
-
-  /* Encrypt the packet */
-
-  if(n->cipher)
-  {
-    outpkt = pkt[nextpkt++];
-
-    EVP_EncryptInit(&ctx, n->cipher, n->key, n->key + n->cipher->key_len);
-    EVP_EncryptUpdate(&ctx, (char *)&outpkt->seqno, &outlen, (char *)&inpkt->seqno, inpkt->len);
-    EVP_EncryptFinal(&ctx, (char *)&outpkt->seqno + outlen, &outpad);
-
-    outpkt->len = outlen + outpad;
-    inpkt = outpkt;
-  }
-
-  /* Add the message authentication code */
-
-  if(n->digest && n->maclength)
-    {
-      HMAC(n->digest, n->key, n->keylength, (char *)&inpkt->seqno, inpkt->len, (char *)&inpkt->seqno + inpkt->len, &outlen);
-      inpkt->len += n->maclength;
-    }
-
-  /* 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. */
-  
-  /* Send the packet */
-
-#if defined(SOL_IP) && defined(IP_TOS)
-  if(priorityinheritance && origpriority != priority && listen_socket[sock].sa.sa.sa_family == AF_INET)
-    {
-      priority = origpriority;
-      if(debug_lvl >= DEBUG_TRAFFIC)
-        syslog(LOG_DEBUG, _("Setting outgoing packet priority to %d"), priority);
-      if(setsockopt(sock, SOL_IP, IP_TOS, &priority, sizeof(priority))) /* SO_PRIORITY doesn't seem to work */
-	syslog(LOG_ERR, _("System call `%s' failed: %s"), "setsockopt", strerror(errno));
-    }
-#endif
-
-  if((sendto(listen_socket[sock].udp, (char *)&inpkt->seqno, inpkt->len, 0, &(n->address.sa), SALEN(n->address.sa))) < 0)
-    {
-      syslog(LOG_ERR, _("Error sending packet to %s (%s): %s"),
-             n->name, n->hostname, strerror(errno));
-      return;
-    }
-  
-  inpkt->len = origlen;
-cp
+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 the UDP address is confirmed, use it. */
+	if(n->status.udp_confirmed) {
+		return;
+	}
+
+	/* Send every third packet to n->address; that could be set
+	   to the node's reflexive UDP address discovered during key
+	   exchange. */
+
+	if(++mesh->udp_choice >= 3) {
+		mesh->udp_choice = 0;
+		return;
+	}
+
+	/* Otherwise, address are found in edges to this node.
+	   So we pick a random edge and a random socket. */
+
+	int i = 0;
+	int j = prng(mesh, n->edge_tree->count);
+	edge_t *candidate = NULL;
+
+	for splay_each(edge_t, e, n->edge_tree) {
+		if(i++ == j) {
+			candidate = e->reverse;
+			break;
+		}
+	}
+
+	if(candidate) {
+		*sa = &candidate->address;
+		*sock = prng(mesh, mesh->listen_sockets);
+	}
+
+	/* 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;
+			}
+		}
+	}
+}
+
+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;
+
+	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;
+	}
+
+	*sa = broadcast_sa;
+}
+
+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;
+	}
+
+	send_sptps_packet(mesh, n, origpkt);
+}
+
+bool send_sptps_data(void *handle, uint8_t type, const void *data, size_t len) {
+	assert(handle);
+	assert(data);
+	assert(len);
+
+	node_t *to = handle;
+	meshlink_handle_t *mesh = to->mesh;
+
+	/* Send it via TCP if it is a handshake packet, TCPOnly is in use, or this packet is larger than the MTU. */
+
+	if(type >= SPTPS_HANDSHAKE || (type != PKT_PROBE && len > to->minmtu)) {
+		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(!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);
+		}
+	}
+
+	/* Otherwise, send the packet via UDP */
+
+	const sockaddr_t *sa;
+	int sock;
+
+	if(to->status.broadcast) {
+		choose_broadcast_address(mesh, to, &sa, &sock);
+	} else {
+		choose_udp_address(mesh, to, &sa, &sock);
+	}
+
+	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(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;
+		}
+	}
+
+	return true;
+}
+
+bool receive_sptps_record(void *handle, uint8_t type, const void *data, uint16_t len) {
+	assert(handle);
+	assert(!data || len);
+
+	node_t *from = handle;
+	meshlink_handle_t *mesh = from->mesh;
+
+	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(from->utcp) {
+				utcp_reset_timers(from->utcp);
+			}
+		}
+
+		return true;
+	}
+
+	if(len > MTU) {
+		logger(mesh, MESHLINK_ERROR, "Packet from %s larger than maximum supported size (%d > %d)", from->name, len, MTU);
+		return false;
+	}
+
+	vpn_packet_t inpkt;
+
+	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(type & ~(PKT_COMPRESSED)) {
+		logger(mesh, MESHLINK_ERROR, "Unexpected SPTPS record type %d len %d from %s", type, len, from->name);
+		return false;
+	}
+
+	if(type & PKT_COMPRESSED) {
+		logger(mesh, MESHLINK_ERROR, "Error while decompressing packet from %s", from->name);
+		return false;
+	}
+
+	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(node_t *n, vpn_packet_t *packet)
-{
-  node_t *via;
-cp
-  if(debug_lvl >= DEBUG_TRAFFIC)
-    syslog(LOG_ERR, _("Sending packet of %d bytes to %s (%s)"),
-           packet->len, n->name, n->hostname);
-
-  if(n == myself)
-    {
-      if(debug_lvl >= DEBUG_TRAFFIC)
-        {
-          syslog(LOG_NOTICE, _("Packet is looping back to us!"));
-        }
-
-      return;
-    }
- 
-  if(!n->status.reachable)
-    {
-      if(debug_lvl >= DEBUG_TRAFFIC)
-        syslog(LOG_INFO, _("Node %s (%s) is not reachable"),
-               n->name, n->hostname);
-      return;
-    }
-
-  via = (n->via == myself)?n->nexthop:n->via;
-
-  if(via != n && debug_lvl >= DEBUG_TRAFFIC)
-    syslog(LOG_ERR, _("Sending packet to %s via %s (%s)"),
-           n->name, via->name, n->via->hostname);
-
-  if((myself->options | via->options) & OPTION_TCPONLY)
-    {
-      if(send_tcppacket(via->connection, packet))
-        terminate_connection(via->connection, 1);
-    }
-  else
-    send_udppacket(via, 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;
+	}
+
+	logger(mesh, MESHLINK_DEBUG, "Sending packet of %d bytes to %s", packet->len, n->name);
+
+	if(!n->status.reachable) {
+		logger(mesh, MESHLINK_WARNING, "Node %s is not reachable", n->name);
+		return;
+	}
+
+	n->out_packets++;
+	n->out_bytes += packet->len;
+	n->status.want_udp = true;
+
+	send_sptps_packet(mesh, n, packet);
+	return;
 }
 
-/* Broadcast a packet using the minimum spanning tree */
-
-void broadcast_packet(node_t *from, vpn_packet_t *packet)
-{
-  avl_node_t *node;
-  connection_t *c;
-cp
-  if(debug_lvl >= DEBUG_TRAFFIC)
-    syslog(LOG_INFO, _("Broadcasting packet of %d bytes from %s (%s)"),
-           packet->len, from->name, from->hostname);
-
-  for(node = connection_tree->head; node; node = node->next)
-    {
-      c = (connection_t *)node->data;
-      if(c->status.active && c->status.mst && c != from->nexthop->connection)
-        send_packet(c->node, packet);
-    }
-cp
-}
+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;
 
-void flush_queue(node_t *n)
-{
-  list_node_t *node, *next;
-cp
-  if(debug_lvl >= DEBUG_TRAFFIC)
-    syslog(LOG_INFO, _("Flushing queue for %s (%s)"), n->name, n->hostname);
-
-  for(node = n->queue->head; node; node = next)
-    {
-      next = node->next;
-      send_udppacket(n, (vpn_packet_t *)node->data);
-      list_delete_node(n->queue, node);
-    }
-cp
-}
+	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;
+			}
+
+			hard = true;
+		}
+
+		if(!try_mac(mesh, e->to, pkt)) {
+			continue;
+		}
+
+		n = e->to;
+		break;
+	}
 
-void handle_incoming_vpn_data(int sock)
-{
-  vpn_packet_t pkt;
-  int x, l = sizeof(x);
-  char *hostname;
-  sockaddr_t from;
-  socklen_t fromlen = sizeof(from);
-  node_t *n;
-cp
-  if(getsockopt(sock, SOL_SOCKET, SO_ERROR, &x, &l) < 0)
-    {
-      syslog(LOG_ERR, _("This is a bug: %s:%d: %d:%s"),
-             __FILE__, __LINE__, sock, strerror(errno));
-      cp_trace();
-      exit(1);
-    }
-  if(x)
-    {
-      syslog(LOG_ERR, _("Incoming data socket error: %s"), strerror(x));
-      return;
-    }
-
-  if((pkt.len = recvfrom(sock, (char *)&pkt.seqno, MAXSIZE, 0, &from.sa, &fromlen)) <= 0)
-    {
-      syslog(LOG_ERR, _("Receiving packet failed: %s"), strerror(errno));
-      return;
-    }
-
-  sockaddrunmap(&from);  /* Some braindead IPv6 implementations do stupid things. */
-
-  n = lookup_node_udp(&from);
-
-  if(!n)
-    {
-      hostname = sockaddr2hostname(&from);
-      syslog(LOG_WARNING, _("Received UDP packet from unknown source %s"), hostname);
-      free(hostname);
-      return;
-    }
-
-  if(n->connection)
-    n->connection->last_ping_time = now;
-
-  receive_udppacket(n, &pkt);
-cp
+	if(hard) {
+		mesh->last_hard_try = mesh->loop.now.tv_sec;
+	}
+
+	return n;
 }
 
+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);
+	node_t *n;
+	int len;
+
+	memset(&from, 0, sizeof(from));
+
+	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));
+		}
+
+		return;
+	}
+
+	pkt.len = len;
+
+	sockaddrunmap(&from); /* Some braindead IPv6 implementations do stupid things. */
+
+	n = lookup_node_udp(mesh, &from);
+
+	if(!n) {
+		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(mesh, MESHLINK_WARNING, "Received UDP packet from unknown source %s", hostname);
+			free(hostname);
+			return;
+		} else {
+			return;
+		}
+	}
+
+	if(n->status.blacklisted) {
+		logger(mesh, MESHLINK_WARNING, "Dropping packet from blacklisted node %s", n->name);
+		return;
+	}
+
+	n->sock = ls - mesh->listen_socket;
+
+	receive_udppacket(mesh, n, &pkt);
+}