]> git.meshlink.io Git - meshlink/blobdiff - src/net_packet.c
Avoid allocating packet buffers unnecessarily.
[meshlink] / src / net_packet.c
index 754e669964ca58a5e5153fb56aa5c8e67e5268c4..8aca6aa59adda1ef8f78d9eecec914625a9a367a 100644 (file)
@@ -1,7 +1,6 @@
 /*
     net_packet.c -- Handles in- and outgoing VPN packets
-    Copyright (C) 1998-2005 Ivo Timmermans,
-                  2000-2006 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
     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;
-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;
+               }
+
+               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;
                }
 
-               len = n->minmtu + 1 + random() % (n->maxmtu - n->minmtu);
-               if(len < 64)
+               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;
 
-               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) {
-       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);
+
+               /* 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 {
-               if(n->minmtu < packet->len)
-                       n->minmtu = packet->len;
+               /* 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);
+               }
        }
 }
 
-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;
+/* VPN packet I/O */
+
+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 {
-               lzo_uint lzolen = MAXSIZE;
-               lzo1x_999_compress(source, len, dest, &lzolen, lzo_wrkmem);
-               return lzolen;
+               n->in_packets++;
+               n->in_bytes += packet->len;
+
+               route(mesh, n, packet);
        }
-       
-       return -1;
 }
 
-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;
-       } else {
-               unsigned long destlen = MAXSIZE;
-               if(uncompress(dest, &destlen, source, len) == Z_OK)
-                       return destlen;
-               else
-                       return -1;
-       }
-       
-       return -1;
+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);
 }
 
-/* VPN packet I/O */
-
-static void receive_packet(node_t *n, vpn_packet_t *packet) {
-       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);
+               }
 
-       ifdebug(TRAFFIC) logger(LOG_DEBUG, _("Received packet of %d bytes from %s (%s)"),
-                          packet->len, n->name, n->hostname);
+               return;
+       }
 
-       route(n, packet);
+       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 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;
-
-       cp();
-
-       /* Check packet length */
+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(&myself->digest)) {
-               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(&myself->digest) && !digest_verify(&myself->digest, &inpkt->seqno, inpkt->len, &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(&myself->cipher)) {
-               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(&myself->cipher, &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;
+       }
 
-       if(myself->compression) {
-               outpkt = pkt[nextpkt++];
+       /* Otherwise, address are found in edges to this node.
+          So we pick a random edge and a random socket. */
 
-               if((outpkt->len = uncompress_packet(outpkt->data, inpkt->data, inpkt->len, myself->compression)) < 0) {
-                       ifdebug(TRAFFIC) logger(LOG_ERR, _("Error while uncompressing packet from %s (%s)"),
-                                                n->name, n->hostname);
-                       return;
+       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;
                }
+       }
 
-               inpkt = outpkt;
+       if(candidate) {
+               *sa = &candidate->address;
+               *sock = prng(mesh, mesh->listen_sockets);
        }
 
-       if(!inpkt->data[12] && !inpkt->data[13])
-               mtu_probe_h(n, inpkt);
-       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;
-       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;
-       vpn_packet_t *copy;
-       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), queueing packet"),
-                                  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);
 
-               /* Since packet is on the stack of handle_tap_input(), we have to make a copy of it first. */
+       node_t *to = handle;
+       meshlink_handle_t *mesh = to->mesh;
 
-               *(copy = xmalloc(sizeof *copy)) = *inpkt;
+       /* Send it via TCP if it is a handshake packet, TCPOnly is in use, or this packet is larger than the MTU. */
 
-               list_insert_tail(n->queue, copy);
+       if(type >= SPTPS_HANDSHAKE || (type != PKT_PROBE && (len - 21) > to->minmtu)) {
+               char buf[len * 4 / 3 + 5];
+               b64encode(data, buf, len);
 
-               if(n->queue->count > MAXQUEUELENGTH)
-                       list_delete_head(n->queue);
+               /* 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->status.waitingforkey)
-                       send_req_key(n->nexthop->connection, myself, n);
+       /* Otherwise, send the packet via UDP */
 
-               n->status.waitingforkey = true;
+       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->compression) {
-               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->compression)) < 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->cipher)) {
-               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->cipher, &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->digest)) {
-               digest_create(&n->digest, &inpkt->seqno, inpkt->len, &inpkt->seqno + inpkt->len);
-               inpkt->len += digest_length(&n->digest);
+       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 */
+       vpn_packet_t inpkt;
 
-       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(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 = (n->via == myself) ? n->nexthop : n->via;
+       n->out_packets++;
+       n->out_bytes += packet->len;
+       n->status.want_udp = true;
 
-       if(via != n)
-               ifdebug(TRAFFIC) logger(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, true);
-       } else
-               send_udppacket(via, packet);
+       send_sptps_packet(mesh, n, packet);
+       return;
 }
 
-/* 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;
+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;
 
-       cp();
+       for splay_each(edge_t, e, mesh->edges) {
+               if(!e->to->status.reachable || e->to == mesh->self) {
+                       continue;
+               }
 
-       ifdebug(TRAFFIC) logger(LOG_INFO, _("Broadcasting packet of %d bytes from %s (%s)"),
-                          packet->len, from->name, from->hostname);
+               if(sockaddrcmp_noport(from, &e->address)) {
+                       if(mesh->last_hard_try == mesh->loop.now.tv_sec) {
+                               continue;
+                       }
 
-       if(from != myself)
-               send_packet(myself, packet);
+                       hard = true;
+               }
 
-       for(node = connection_tree->head; node; node = node->next) {
-               c = node->data;
+               if(!try_mac(mesh, e->to, pkt)) {
+                       continue;
+               }
 
-               if(c->status.active && c->status.mst && c != from->nexthop->connection)
-                       send_packet(c->node, packet);
+               n = e->to;
+               break;
        }
-}
-
-void flush_queue(node_t *n) {
-       list_node_t *node, *next;
-
-       cp();
 
-       ifdebug(TRAFFIC) logger(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, node->data);
-               list_delete_node(n->queue, node);
+       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;
 
-       n = lookup_node_udp(&from);
+       sockaddrunmap(&from); /* Some braindead IPv6 implementations do stupid things. */
+
+       n = lookup_node_udp(mesh, &from);
 
        if(!n) {
-               hostname = sockaddr2hostname(&from);
-               logger(LOG_WARNING, _("Received UDP packet from unknown source %s"),
-                          hostname);
-               free(hostname);
-               return;
+               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;
+               }
        }
 
-       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);
 }