Prepend source node ID information to UDP datagrams.
[tinc] / src / net_packet.c
index c255261..6b7c3b9 100644 (file)
@@ -42,7 +42,6 @@
 #include "net.h"
 #include "netutl.h"
 #include "protocol.h"
-#include "process.h"
 #include "route.h"
 #include "utils.h"
 #include "xalloc.h"
@@ -55,7 +54,7 @@ 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;
-bool localdiscovery = false;
+bool localdiscovery = true;
 
 #define MAX_SEQNO 1073741824
 
@@ -143,16 +142,15 @@ static void send_mtu_probe_handler(void *data) {
                memset(packet.data, 0, 14);
                randomize(packet.data + 14, len - 14);
                packet.len = len;
-               if(i >= 4 && n->mtuprobes <= 10)
-                       packet.priority = -1;
-               else
-                       packet.priority = 0;
+               packet.priority = 0;
+               n->status.send_locally = i >= 4 && n->mtuprobes <= 10 && n->prevedge;
 
                logger(DEBUG_TRAFFIC, LOG_INFO, "Sending MTU probe length %d to %s (%s)", len, n->name, n->hostname);
 
                send_udppacket(n, &packet);
        }
 
+       n->status.send_locally = false;
        n->probe_counter = 0;
        gettimeofday(&n->probe_time, NULL);
 
@@ -178,12 +176,25 @@ void send_mtu_probe(node_t *n) {
 }
 
 static void mtu_probe_h(node_t *n, vpn_packet_t *packet, length_t len) {
-       logger(DEBUG_TRAFFIC, LOG_INFO, "Got MTU probe length %d from %s (%s)", packet->len, n->name, n->hostname);
-
        if(!packet->data[0]) {
+               logger(DEBUG_TRAFFIC, LOG_INFO, "Got MTU probe request %d from %s (%s)", packet->len, n->name, n->hostname);
+
                /* It's a probe request, send back a reply */
 
-               packet->data[0] = 1;
+               /* Type 2 probe replies were introduced in protocol 17.3 */
+               if ((n->options >> 24) >= 3) {
+                       uint8_t* data = packet->data;
+                       *data++ = 2;
+                       uint16_t len16 = htons(len); memcpy(data, &len16, 2); data += 2;
+                       struct timeval now;
+                       gettimeofday(&now, NULL);
+                       uint32_t sec = htonl(now.tv_sec); memcpy(data, &sec, 4); data += 4;
+                       uint32_t usec = htonl(now.tv_usec); memcpy(data, &usec, 4); data += 4;
+                       packet->len = data - packet->data;
+               } else {
+                       /* Legacy protocol: n won't understand type 2 probe replies. */
+                       packet->data[0] = 1;
+               }
 
                /* Temporarily set udp_confirmed, so that the reply is sent
                   back exactly the way it came in. */
@@ -193,6 +204,16 @@ static void mtu_probe_h(node_t *n, vpn_packet_t *packet, length_t len) {
                send_udppacket(n, packet);
                n->status.udp_confirmed = udp_confirmed;
        } else {
+               length_t probelen = len;
+               if (packet->data[0] == 2) {
+                       if (len < 3)
+                               logger(DEBUG_TRAFFIC, LOG_WARNING, "Received invalid (too short) MTU probe reply from %s (%s)", n->name, n->hostname);
+                       else {
+                               uint16_t probelen16; memcpy(&probelen16, packet->data + 1, 2); probelen = ntohs(probelen16);
+                       }
+               }
+               logger(DEBUG_TRAFFIC, LOG_INFO, "Got type %d MTU probe reply %d from %s (%s)", packet->data[0], probelen, n->name, n->hostname);
+
                /* It's a valid reply: now we know bidirectional communication
                   is possible using the address and socket that the reply
                   packet used. */
@@ -202,7 +223,7 @@ static void mtu_probe_h(node_t *n, vpn_packet_t *packet, length_t len) {
                /* If we haven't established the PMTU yet, restart the discovery process. */
 
                if(n->mtuprobes > 30) {
-                       if (len == n->maxmtu + 8) {
+                       if (probelen == n->maxmtu + 8) {
                                logger(DEBUG_TRAFFIC, LOG_INFO, "Increase in PMTU to %s (%s) detected, restarting PMTU discovery", n->name, n->hostname);
                                n->maxmtu = MTU;
                                n->mtuprobes = 10;
@@ -217,27 +238,38 @@ static void mtu_probe_h(node_t *n, vpn_packet_t *packet, length_t len) {
 
                /* If applicable, raise the minimum supported MTU */
 
-               if(len > n->maxmtu)
-                       len = n->maxmtu;
-               if(n->minmtu < len)
-                       n->minmtu = len;
+               if(probelen > n->maxmtu)
+                       probelen = n->maxmtu;
+               if(n->minmtu < probelen)
+                       n->minmtu = probelen;
 
                /* Calculate RTT and bandwidth.
                   The RTT is the time between the MTU probe burst was sent and the first
                   reply is received. The bandwidth is measured using the time between the
-                  arrival of the first and third probe reply.
+                  arrival of the first and third probe reply (or type 2 probe requests).
                 */
 
                struct timeval now, diff;
                gettimeofday(&now, NULL);
                timersub(&now, &n->probe_time, &diff);
+
+               struct timeval probe_timestamp = now;
+               if (packet->data[0] == 2 && packet->len >= 11) {
+                       uint32_t sec; memcpy(&sec, packet->data + 3, 4);
+                       uint32_t usec; memcpy(&usec, packet->data + 7, 4);
+                       probe_timestamp.tv_sec = ntohl(sec);
+                       probe_timestamp.tv_usec = ntohl(usec);
+               }
+               
                n->probe_counter++;
 
                if(n->probe_counter == 1) {
                        n->rtt = diff.tv_sec + diff.tv_usec * 1e-6;
-                       n->probe_time = now;
+                       n->probe_time = probe_timestamp;
                } else if(n->probe_counter == 3) {
-                       n->bandwidth = 2.0 * len / (diff.tv_sec + diff.tv_usec * 1e-6);
+                       struct timeval probe_timestamp_diff;
+                       timersub(&probe_timestamp, &n->probe_time, &probe_timestamp_diff);
+                       n->bandwidth = 2.0 * probelen / (probe_timestamp_diff.tv_sec + probe_timestamp_diff.tv_usec * 1e-6);
                        logger(DEBUG_TRAFFIC, LOG_DEBUG, "%s (%s) RTT %.2f ms, burst bandwidth %.3f Mbit/s, rx packet loss %.2f %%", n->name, n->hostname, n->rtt * 1e3, n->bandwidth * 8e-6, n->packetloss * 1e2);
                }
        }
@@ -324,22 +356,28 @@ static bool try_mac(node_t *n, const vpn_packet_t *inpkt) {
        return digest_verify(n->indigest, &inpkt->seqno, inpkt->len - digest_length(n->indigest), (const char *)&inpkt->seqno + inpkt->len - digest_length(n->indigest));
 }
 
-static void receive_udppacket(node_t *n, vpn_packet_t *inpkt) {
+static bool 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;
 
        if(n->status.sptps) {
-               sptps_receive_data(&n->sptps, (char *)&inpkt->seqno, inpkt->len);
-               return;
+               if(!n->sptps.state) {
+                       if(!n->status.waitingforkey) {
+                               logger(DEBUG_TRAFFIC, LOG_DEBUG, "Got packet from %s (%s) but we haven't exchanged keys yet", n->name, n->hostname);
+                               send_req_key(n);
+                       } else {
+                               logger(DEBUG_TRAFFIC, LOG_DEBUG, "Got packet from %s (%s) but he hasn't got our key yet", n->name, n->hostname);
+                       }
+                       return false;
+               }
+               return sptps_receive_data(&n->sptps, (char *)&inpkt->seqno, inpkt->len);
        }
 
-       if(!cipher_active(n->incipher)) {
-               logger(DEBUG_TRAFFIC, LOG_DEBUG, "Got packet from %s (%s) but he hasn't got our key yet",
-                                       n->name, n->hostname);
-               return;
+       if(!n->status.validkey) {
+               logger(DEBUG_TRAFFIC, LOG_DEBUG, "Got packet from %s (%s) but he hasn't got our key yet", n->name, n->hostname);
+               return false;
        }
 
        /* Check packet length */
@@ -347,7 +385,7 @@ static void receive_udppacket(node_t *n, vpn_packet_t *inpkt) {
        if(inpkt->len < sizeof inpkt->seqno + digest_length(n->indigest)) {
                logger(DEBUG_TRAFFIC, LOG_DEBUG, "Got too short packet from %s (%s)",
                                        n->name, n->hostname);
-               return;
+               return false;
        }
 
        /* Check the message authentication code */
@@ -356,18 +394,18 @@ static void receive_udppacket(node_t *n, vpn_packet_t *inpkt) {
                inpkt->len -= digest_length(n->indigest);
                if(!digest_verify(n->indigest, &inpkt->seqno, inpkt->len, (const char *)&inpkt->seqno + inpkt->len)) {
                        logger(DEBUG_TRAFFIC, LOG_DEBUG, "Got unauthenticated packet from %s (%s)", n->name, n->hostname);
-                       return;
+                       return false;
                }
        }
        /* Decrypt the packet */
 
        if(cipher_active(n->incipher)) {
-               outpkt = pkt[nextpkt++];
+               vpn_packet_t *outpkt = pkt[nextpkt++];
                outlen = MAXSIZE;
 
                if(!cipher_decrypt(n->incipher, &inpkt->seqno, inpkt->len, &outpkt->seqno, &outlen, true)) {
                        logger(DEBUG_TRAFFIC, LOG_DEBUG, "Error decrypting packet from %s (%s)", n->name, n->hostname);
-                       return;
+                       return false;
                }
 
                outpkt->len = outlen;
@@ -377,37 +415,39 @@ static void receive_udppacket(node_t *n, vpn_packet_t *inpkt) {
        /* Check the sequence number */
 
        inpkt->len -= sizeof inpkt->seqno;
-       inpkt->seqno = ntohl(inpkt->seqno);
+       uint32_t seqno;
+       memcpy(&seqno, inpkt->seqno, sizeof seqno);
+       seqno = ntohl(seqno);
 
        if(replaywin) {
-               if(inpkt->seqno != n->received_seqno + 1) {
-                       if(inpkt->seqno >= n->received_seqno + replaywin * 8) {
+               if(seqno != n->received_seqno + 1) {
+                       if(seqno >= n->received_seqno + replaywin * 8) {
                                if(n->farfuture++ < replaywin >> 2) {
                                        logger(DEBUG_ALWAYS, LOG_WARNING, "Packet from %s (%s) is %d seqs in the future, dropped (%u)",
-                                               n->name, n->hostname, inpkt->seqno - n->received_seqno - 1, n->farfuture);
-                                       return;
+                                               n->name, n->hostname, seqno - n->received_seqno - 1, n->farfuture);
+                                       return false;
                                }
                                logger(DEBUG_ALWAYS, LOG_WARNING, "Lost %d packets from %s (%s)",
-                                               inpkt->seqno - n->received_seqno - 1, n->name, n->hostname);
+                                               seqno - n->received_seqno - 1, n->name, n->hostname);
                                memset(n->late, 0, replaywin);
-                       } else if (inpkt->seqno <= n->received_seqno) {
-                               if((n->received_seqno >= replaywin * 8 && inpkt->seqno <= n->received_seqno - replaywin * 8) || !(n->late[(inpkt->seqno / 8) % replaywin] & (1 << inpkt->seqno % 8))) {
+                       } else if (seqno <= n->received_seqno) {
+                               if((n->received_seqno >= replaywin * 8 && seqno <= n->received_seqno - replaywin * 8) || !(n->late[(seqno / 8) % replaywin] & (1 << seqno % 8))) {
                                        logger(DEBUG_ALWAYS, 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;
+                                               n->name, n->hostname, seqno, n->received_seqno);
+                                       return false;
                                }
                        } else {
-                               for(int i = n->received_seqno + 1; i < inpkt->seqno; i++)
+                               for(int i = n->received_seqno + 1; i < seqno; i++)
                                        n->late[(i / 8) % replaywin] |= 1 << i % 8;
                        }
                }
 
                n->farfuture = 0;
-               n->late[(inpkt->seqno / 8) % replaywin] &= ~(1 << inpkt->seqno % 8);
+               n->late[(seqno / 8) % replaywin] &= ~(1 << seqno % 8);
        }
 
-       if(inpkt->seqno > n->received_seqno)
-               n->received_seqno = inpkt->seqno;
+       if(seqno > n->received_seqno)
+               n->received_seqno = seqno;
 
        n->received++;
 
@@ -419,12 +459,12 @@ static void receive_udppacket(node_t *n, vpn_packet_t *inpkt) {
        length_t origlen = inpkt->len;
 
        if(n->incompression) {
-               outpkt = pkt[nextpkt++];
+               vpn_packet_t *outpkt = pkt[nextpkt++];
 
                if((outpkt->len = uncompress_packet(outpkt->data, inpkt->data, inpkt->len, n->incompression)) < 0) {
                        logger(DEBUG_TRAFFIC, LOG_ERR, "Error while uncompressing packet from %s (%s)",
                                                 n->name, n->hostname);
-                       return;
+                       return false;
                }
 
                inpkt = outpkt;
@@ -438,6 +478,7 @@ static void receive_udppacket(node_t *n, vpn_packet_t *inpkt) {
                mtu_probe_h(n, inpkt, origlen);
        else
                receive_packet(n, inpkt);
+       return true;
 }
 
 void receive_tcppacket(connection_t *c, const char *buffer, int len) {
@@ -503,6 +544,18 @@ static void send_sptps_packet(node_t *n, vpn_packet_t *origpkt) {
        return;
 }
 
+static void adapt_socket(const sockaddr_t *sa, int *sock) {
+       /* Make sure we have a suitable socket for the chosen address */
+       if(listen_socket[*sock].sa.sa.sa_family != sa->sa.sa_family) {
+               for(int i = 0; i < listen_sockets; i++) {
+                       if(listen_socket[i].sa.sa.sa_family == sa->sa.sa_family) {
+                               *sock = i;
+                               break;
+                       }
+               }
+       }
+}
+
 static void choose_udp_address(const node_t *n, const sockaddr_t **sa, int *sock) {
        /* Latest guess */
        *sa = &n->address;
@@ -541,43 +594,29 @@ static void choose_udp_address(const node_t *n, const sockaddr_t **sa, int *sock
                *sock = rand() % listen_sockets;
        }
 
-       /* Make sure we have a suitable socket for the chosen address */
-       if(listen_socket[*sock].sa.sa.sa_family != (*sa)->sa.sa_family) {
-               for(int i = 0; i < listen_sockets; i++) {
-                       if(listen_socket[i].sa.sa.sa_family == (*sa)->sa.sa_family) {
-                               *sock = i;
-                               break;
-                       }
-               }
-       }
+       adapt_socket(*sa, sock);
 }
 
-static void choose_broadcast_address(const node_t *n, const sockaddr_t **sa, int *sock) {
-       static sockaddr_t broadcast_ipv4 = {
-               .in = {
-                       .sin_family = AF_INET,
-                       .sin_addr.s_addr = -1,
-               }
-       };
-
-       static sockaddr_t broadcast_ipv6 = {
-               .in6 = {
-                       .sin6_family = AF_INET6,
-                       .sin6_addr.s6_addr[0x0] = 0xff,
-                       .sin6_addr.s6_addr[0x1] = 0x02,
-                       .sin6_addr.s6_addr[0xf] = 0x01,
-               }
-       };
+static void choose_local_address(const node_t *n, const sockaddr_t **sa, int *sock) {
+       *sa = NULL;
 
-       *sock = rand() % listen_sockets;
+       /* Pick one of the edges from this node at random, then use its local address. */
 
-       if(listen_socket[*sock].sa.sa.sa_family == AF_INET6) {
-               broadcast_ipv6.in6.sin6_port = n->prevedge->address.in.sin_port;
-               broadcast_ipv6.in6.sin6_scope_id = listen_socket[*sock].sa.in6.sin6_scope_id;
-               *sa = &broadcast_ipv6;
-       } else {
-               broadcast_ipv4.in.sin_port = n->prevedge->address.in.sin_port;
-               *sa = &broadcast_ipv4;
+       int i = 0;
+       int j = rand() % n->edge_tree->count;
+       edge_t *candidate = NULL;
+
+       for splay_each(edge_t, e, n->edge_tree) {
+               if(i++ == j) {
+                       candidate = e;
+                       break;
+               }
+       }
+
+       if (candidate && candidate->local_address.sa.sa_family) {
+               *sa = &candidate->local_address;
+               *sock = rand() % listen_sockets;
+               adapt_socket(*sa, sock);
        }
 }
 
@@ -591,8 +630,8 @@ static void send_udppacket(node_t *n, vpn_packet_t *origpkt) {
        size_t outlen;
 #if defined(SOL_IP) && defined(IP_TOS)
        static int priority = 0;
-#endif
        int origpriority = origpkt->priority;
+#endif
 
        if(!n->status.reachable) {
                logger(DEBUG_TRAFFIC, LOG_INFO, "Trying to send UDP packet to unreachable node %s (%s)", n->name, n->hostname);
@@ -648,7 +687,8 @@ static void send_udppacket(node_t *n, vpn_packet_t *origpkt) {
 
        /* Add sequence number */
 
-       inpkt->seqno = htonl(++(n->sent_seqno));
+       uint32_t seqno = htonl(++(n->sent_seqno));
+       memcpy(inpkt->seqno, &seqno, sizeof inpkt->seqno);
        inpkt->len += sizeof inpkt->seqno;
 
        /* Encrypt the packet */
@@ -657,7 +697,7 @@ static void send_udppacket(node_t *n, vpn_packet_t *origpkt) {
                outpkt = pkt[nextpkt++];
                outlen = MAXSIZE;
 
-               if(!cipher_encrypt(n->outcipher, &inpkt->seqno, inpkt->len, &outpkt->seqno, &outlen, true)) {
+               if(!cipher_encrypt(n->outcipher, inpkt->seqno, inpkt->len, outpkt->seqno, &outlen, true)) {
                        logger(DEBUG_TRAFFIC, LOG_ERR, "Error while encrypting packet to %s (%s)", n->name, n->hostname);
                        goto end;
                }
@@ -669,20 +709,22 @@ static void send_udppacket(node_t *n, vpn_packet_t *origpkt) {
        /* Add the message authentication code */
 
        if(digest_active(n->outdigest)) {
-               digest_create(n->outdigest, &inpkt->seqno, inpkt->len, (char *)&inpkt->seqno + inpkt->len);
+               if(!digest_create(n->outdigest, inpkt->seqno, inpkt->len, inpkt->seqno + inpkt->len)) {
+                       logger(DEBUG_TRAFFIC, LOG_ERR, "Error while encrypting packet to %s (%s)", n->name, n->hostname);
+                       goto end;
+               }
+
                inpkt->len += digest_length(n->outdigest);
        }
 
        /* Send the packet */
 
-       const sockaddr_t *sa;
+       const sockaddr_t *sa = NULL;
        int sock;
 
-       /* Overloaded use of priority field: -1 means local broadcast */
-
-       if(origpriority == -1 && n->prevedge)
-               choose_broadcast_address(n, &sa, &sock);
-       else
+       if(n->status.send_locally)
+               choose_local_address(n, &sa, &sock);
+       if(!sa)
                choose_udp_address(n, &sa, &sock);
 
 #if defined(SOL_IP) && defined(IP_TOS)
@@ -691,11 +733,11 @@ static void send_udppacket(node_t *n, vpn_packet_t *origpkt) {
                priority = origpriority;
                logger(DEBUG_TRAFFIC, LOG_DEBUG, "Setting outgoing packet priority to %d", priority);
                if(setsockopt(listen_socket[n->sock].udp.fd, SOL_IP, IP_TOS, &priority, sizeof(priority))) /* SO_PRIORITY doesn't seem to work */
-                       logger(DEBUG_ALWAYS, LOG_ERR, "System call `%s' failed: %s", "setsockopt", strerror(errno));
+                       logger(DEBUG_ALWAYS, LOG_ERR, "System call `%s' failed: %s", "setsockopt", sockstrerror(sockerrno));
        }
 #endif
 
-       if(sendto(listen_socket[sock].udp.fd, (char *) &inpkt->seqno, inpkt->len, 0, &sa->sa, SALEN(sa->sa)) < 0 && !sockwouldblock(sockerrno)) {
+       if(sendto(listen_socket[sock].udp.fd, inpkt->seqno, inpkt->len, 0, &sa->sa, SALEN(sa->sa)) < 0 && !sockwouldblock(sockerrno)) {
                if(sockmsgsize(sockerrno)) {
                        if(n->maxmtu >= origlen)
                                n->maxmtu = origlen - 1;
@@ -714,26 +756,43 @@ bool send_sptps_data(void *handle, uint8_t type, const char *data, size_t len) {
 
        /* 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 || ((myself->options | to->options) & OPTION_TCPONLY) || (type != PKT_PROBE && len > to->minmtu)) {
+       if(type >= SPTPS_HANDSHAKE || ((myself->options | to->options) & OPTION_TCPONLY) || (type != PKT_PROBE && (len - SPTPS_DATAGRAM_OVERHEAD) > 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(to->nexthop->connection, "%d %s %s %s -1 -1 -1 %d", ANS_KEY, myself->name, to->name, buf, myself->incompression);
-               else
+               if(!to->status.validkey) {
+                       to->incompression = myself->incompression;
+                       return send_request(to->nexthop->connection, "%d %s %s %s -1 -1 -1 %d", ANS_KEY, myself->name, to->name, buf, to->incompression);
+               } else {
                        return send_request(to->nexthop->connection, "%d %s %s %d %s", REQ_KEY, myself->name, to->name, REQ_SPTPS, buf);
+               }
        }
 
        /* Otherwise, send the packet via UDP */
 
-       const sockaddr_t *sa;
+       const sockaddr_t *sa = NULL;
        int sock;
 
-       choose_udp_address(to, &sa, &sock);
+       if(to->status.send_locally)
+               choose_local_address(to, &sa, &sock);
+       if(!sa)
+               choose_udp_address(to, &sa, &sock);
+
+       bool add_srcid = (to->options >> 24) >= 4;
+       size_t overhead = 0;
+       if (add_srcid) overhead += sizeof myself->id;
+       char buf[len + overhead]; char* buf_ptr = buf;
+       if(add_srcid) {
+               memcpy(buf_ptr, &myself->id, sizeof myself->id); buf_ptr += sizeof myself->id;
+       }
+       /* TODO: if this copy turns out to be a performance concern, change sptps_send_record() to add some "pre-padding" to the buffer and use that instead */
+       memcpy(buf_ptr, data, len); buf_ptr += len;
 
-       if(sendto(listen_socket[sock].udp.fd, data, len, 0, &sa->sa, SALEN(sa->sa)) < 0 && !sockwouldblock(sockerrno)) {
+       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
+                       len -= SPTPS_DATAGRAM_OVERHEAD;
                        if(to->maxmtu >= len)
                                to->maxmtu = len - 1;
                        if(to->mtu >= len)
@@ -890,7 +949,7 @@ void broadcast_packet(const node_t *from, vpn_packet_t *packet) {
                // usually distributes the sending of broadcast packets over all nodes.
                case BMODE_MST:
                        for list_each(connection_t, c, connection_list)
-                               if(c->status.active && c->status.mst && c != from->nexthop->connection)
+                               if(c->edge && c->status.mst && c != from->nexthop->connection)
                                        send_packet(c->node, packet);
                        break;
 
@@ -902,7 +961,7 @@ void broadcast_packet(const node_t *from, vpn_packet_t *packet) {
                                break;
 
                        for splay_each(node_t, n, node_tree)
-                               if(n->status.reachable && ((n->via == myself && n->nexthop == n) || n->via == n))
+                               if(n->status.reachable && n != myself && ((n->via == myself && n->nexthop == n) || n->via == n))
                                        send_packet(n, packet);
                        break;
 
@@ -946,10 +1005,10 @@ void handle_incoming_vpn_data(void *data, int flags) {
        char *hostname;
        sockaddr_t from = {{0}};
        socklen_t fromlen = sizeof from;
-       node_t *n;
+       node_t *n = NULL;
        int len;
 
-       len = recvfrom(ls->udp.fd, (char *) &pkt.seqno, MAXSIZE, 0, &from.sa, &fromlen);
+       len = recvfrom(ls->udp.fd, &pkt.srcid, MAXSIZE, 0, &from.sa, &fromlen);
 
        if(len <= 0 || len > MAXSIZE) {
                if(!sockwouldblock(sockerrno))
@@ -961,25 +1020,34 @@ void handle_incoming_vpn_data(void *data, int flags) {
 
        sockaddrunmap(&from); /* Some braindead IPv6 implementations do stupid things. */
 
-       n = lookup_node_udp(&from);
+       if(len >= sizeof pkt.srcid)
+               n = lookup_node_id(&pkt.srcid);
+       if(n)
+               pkt.len -= sizeof pkt.srcid;
+       else {
+               /* Most likely an old-style packet without a source ID. */
+               memmove(pkt.seqno, &pkt.srcid, sizeof pkt - offsetof(vpn_packet_t, seqno));
+               n = lookup_node_udp(&from);
+       }
 
-       if(!n) {
+       if(!n)
                n = try_harder(&from, &pkt);
-               if(n)
-                       update_node_udp(n, &from);
-               else if(debug_level >= DEBUG_PROTOCOL) {
+
+       if(!n) {
+               if(debug_level >= DEBUG_PROTOCOL) {
                        hostname = sockaddr2hostname(&from);
                        logger(DEBUG_PROTOCOL, LOG_WARNING, "Received UDP packet from unknown source %s", hostname);
                        free(hostname);
-                       return;
                }
-               else
-                       return;
+               return;
        }
 
-       n->sock = ls - listen_socket;
+       if(!receive_udppacket(n, &pkt))
+               return;
 
-       receive_udppacket(n, &pkt);
+       n->sock = ls - listen_socket;
+       if(sockaddrcmp(&from, &n->address))
+               update_node_udp(n, &from);
 }
 
 void handle_device_data(void *data, int flags) {