X-Git-Url: https://tinc-vpn.org/git/browse?a=blobdiff_plain;f=src%2Fnet_packet.c;h=a24a7add6080d1d20dd6b0267fb464fe2ecc5be7;hb=558b19c2432d938afc4a659668bd461ace6ed744;hp=012085e22bf8e9beb40185e11febd90701ede2b1;hpb=3d41e7d71247998b7c4a3dd4eacb93bd3529428d;p=tinc

diff --git a/src/net_packet.c b/src/net_packet.c
index 012085e2..a24a7add 100644
--- a/src/net_packet.c
+++ b/src/net_packet.c
@@ -54,8 +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;
-sockaddr_t localdiscovery_address;
+bool localdiscovery = true;
 
 #define MAX_SEQNO 1073741824
 
@@ -144,14 +143,14 @@ static void send_mtu_probe_handler(void *data) {
 		randomize(packet.data + 14, len - 14);
 		packet.len = len;
 		packet.priority = 0;
-		n->status.broadcast = i >= 4 && n->mtuprobes <= 10 && n->prevedge;
+		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.broadcast = false;
+	n->status.send_locally = false;
 	n->probe_counter = 0;
 	gettimeofday(&n->probe_time, NULL);
 
@@ -183,7 +182,7 @@ static void mtu_probe_h(node_t *n, vpn_packet_t *packet, length_t len) {
 		/* It's a probe request, send back a reply */
 
 		/* Type 2 probe replies were introduced in protocol 17.3 */
-		if ((n->options >> 24) == 3) {
+		if ((n->options >> 24) >= 3) {
 			uint8_t* data = packet->data;
 			*data++ = 2;
 			uint16_t len16 = htons(len); memcpy(data, &len16, 2); data += 2;
@@ -349,19 +348,18 @@ static void receive_packet(node_t *n, vpn_packet_t *packet) {
 
 static bool try_mac(node_t *n, const vpn_packet_t *inpkt) {
 	if(n->status.sptps)
-		return sptps_verify_datagram(&n->sptps, (char *)&inpkt->seqno, inpkt->len);
+		return sptps_verify_datagram(&n->sptps, ((sptps_packet_t *)inpkt)->data, inpkt->len);
 
 	if(!digest_active(n->indigest) || inpkt->len < sizeof inpkt->seqno + digest_length(n->indigest))
 		return false;
 
-	return digest_verify(n->indigest, &inpkt->seqno, inpkt->len - digest_length(n->indigest), (const char *)&inpkt->seqno + inpkt->len - digest_length(n->indigest));
+	return digest_verify(n->indigest, (const char *)&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) {
@@ -372,15 +370,18 @@ static void receive_udppacket(node_t *n, vpn_packet_t *inpkt) {
 			} else {
 				logger(DEBUG_TRAFFIC, LOG_DEBUG, "Got packet from %s (%s) but he hasn't got our key yet", n->name, n->hostname);
 			}
-			return;
+			return false;
 		}
-		sptps_receive_data(&n->sptps, (char *)&inpkt->seqno, inpkt->len);
-		return;
+		if(!sptps_receive_data(&n->sptps, ((sptps_packet_t *)&inpkt)->data, inpkt->len)) {
+			logger(DEBUG_TRAFFIC, LOG_ERR, "Got bad packet from %s (%s)", n->name, n->hostname);
+			return false;
+		}
+		return true;
 	}
 
-	if(!cipher_active(n->incipher)) {
+	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;
+		return false;
 	}
 
 	/* Check packet length */
@@ -388,7 +389,7 @@ 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 */
@@ -397,18 +398,18 @@ 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;
@@ -418,37 +419,37 @@ 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 = ntohl(inpkt->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++;
 
@@ -460,12 +461,12 @@ 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;
@@ -479,6 +480,7 @@ 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) {
@@ -497,19 +499,27 @@ void receive_tcppacket(connection_t *c, const char *buffer, int len) {
 	receive_packet(c->node, &outpkt);
 }
 
+static bool try_sptps(node_t *n) {
+	if(n->status.validkey)
+		return true;
+
+	logger(DEBUG_TRAFFIC, LOG_INFO, "No valid key known yet for %s (%s)", n->name, n->hostname);
+
+	if(!n->status.waitingforkey)
+		send_req_key(n);
+	else if(n->last_req_key + 10 < now.tv_sec) {
+		logger(DEBUG_ALWAYS, LOG_DEBUG, "No key from %s after 10 seconds, restarting SPTPS", n->name);
+		sptps_stop(&n->sptps);
+		n->status.waitingforkey = false;
+		send_req_key(n);
+	}
+
+	return false;
+}
+
 static void send_sptps_packet(node_t *n, vpn_packet_t *origpkt) {
-	if(!n->status.validkey) {
-		logger(DEBUG_TRAFFIC, LOG_INFO, "No valid key known yet for %s (%s)", n->name, n->hostname);
-		if(!n->status.waitingforkey)
-			send_req_key(n);
-		else if(n->last_req_key + 10 < now.tv_sec) {
-			logger(DEBUG_ALWAYS, LOG_DEBUG, "No key from %s after 10 seconds, restarting SPTPS", n->name);
-			sptps_stop(&n->sptps);
-			n->status.waitingforkey = false;
-			send_req_key(n);
-		}
+	if (!try_sptps(n))
 		return;
-	}
 
 	uint8_t type = 0;
 	int offset = 0;
@@ -544,6 +554,18 @@ 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;
@@ -582,54 +604,30 @@ 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) {
-		if(localdiscovery_address.sa.sa_family == AF_INET6) {
-			localdiscovery_address.in6.sin6_port = n->prevedge->address.in.sin_port;
-			*sa = &localdiscovery_address;
-		} else {
-			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 {
-		if(localdiscovery_address.sa.sa_family == AF_INET) {
-			localdiscovery_address.in.sin_port = n->prevedge->address.in.sin_port;
-			*sa = &localdiscovery_address;
-		} 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);
+	}
 }
 
 static void send_udppacket(node_t *n, vpn_packet_t *origpkt) {
@@ -642,8 +640,8 @@ 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);
@@ -720,7 +718,7 @@ static void send_udppacket(node_t *n, vpn_packet_t *origpkt) {
 	/* Add the message authentication code */
 
 	if(digest_active(n->outdigest)) {
-		if(!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;
 		}
@@ -730,12 +728,12 @@ static void send_udppacket(node_t *n, vpn_packet_t *origpkt) {
 
 	/* Send the packet */
 
-	const sockaddr_t *sa;
+	const sockaddr_t *sa = NULL;
 	int sock;
 
-	if(n->status.broadcast)
-		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)
@@ -744,11 +742,11 @@ 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;
@@ -762,42 +760,67 @@ end:
 	origpkt->len = origlen;
 }
 
-bool send_sptps_data(void *handle, uint8_t type, const char *data, size_t len) {
-	node_t *to = handle;
+static bool send_sptps_data_priv(node_t *to, node_t *from, int type, const void *data, size_t len) {
+	node_t *relay = (to->via != myself && (type == PKT_PROBE || (len - SPTPS_DATAGRAM_OVERHEAD) <= to->via->minmtu)) ? to->via : to->nexthop;
+	bool direct = from == myself && to == relay;
+	bool relay_supported = (relay->options >> 24) >= 4;
+	bool tcponly = (myself->options | relay->options) & OPTION_TCPONLY;
+
+	/* We don't really need the relay's key, but we need to establish a UDP tunnel with it and discover its MTU. */
+	if (!direct && relay_supported && !tcponly)
+		try_sptps(relay);
 
-	/* Send it via TCP if it is a handshake packet, TCPOnly is in use, or this packet is larger than the MTU. */
+	/* Send it via TCP if it is a handshake packet, TCPOnly is in use, this is a relay packet that the other node cannot understand, or this packet is larger than the MTU.
+	   TODO: When relaying, the original sender does not know the end-to-end PMTU (it only knows the PMTU of the first hop).
+	         This can lead to scenarios where large packets are sent over UDP to relay, but then relay has no choice but fall back to TCP. */
 
-	if(type >= SPTPS_HANDSHAKE || ((myself->options | to->options) & OPTION_TCPONLY) || (type != PKT_PROBE && len > to->minmtu)) {
+	if(type == SPTPS_HANDSHAKE || tcponly || (!direct && !relay_supported) || (type != PKT_PROBE && (len - SPTPS_DATAGRAM_OVERHEAD) > relay->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) {
+		if(from == myself && !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);
+			return send_request(to->nexthop->connection, "%d %s %s %s -1 -1 -1 %d", ANS_KEY, from->name, to->name, buf, to->incompression);
 		} else {
-			return send_request(to->nexthop->connection, "%d %s %s %d %s", REQ_KEY, myself->name, to->name, REQ_SPTPS, buf);
+			return send_request(to->nexthop->connection, "%d %s %s %d %s", REQ_KEY, from->name, to->name, REQ_SPTPS, buf);
 		}
 	}
 
-	/* Otherwise, send the packet via UDP */
-
-	const sockaddr_t *sa;
-	int sock;
+	size_t overhead = 0;
+	if(relay_supported) overhead += sizeof to->id + sizeof from->id;
+	char buf[len + overhead]; char* buf_ptr = buf;
+	if(relay_supported) {
+		if(direct) {
+			/* Inform the recipient that this packet was sent directly. */
+			node_id_t nullid = {};
+			memcpy(buf_ptr, &nullid, sizeof nullid); buf_ptr += sizeof nullid;
+		} else {
+			memcpy(buf_ptr, &to->id, sizeof to->id); buf_ptr += sizeof to->id;
+		}
+		memcpy(buf_ptr, &from->id, sizeof from->id); buf_ptr += sizeof from->id;
 
-	if(to->status.broadcast)
-		choose_broadcast_address(to, &sa, &sock);
-	else
-		choose_udp_address(to, &sa, &sock);
+	}
+	/* 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)) {
+	const sockaddr_t *sa = NULL;
+	int sock;
+	if(relay->status.send_locally)
+		choose_local_address(relay, &sa, &sock);
+	if(!sa)
+		choose_udp_address(relay, &sa, &sock);
+	logger(DEBUG_TRAFFIC, LOG_INFO, "Sending packet from %s (%s) to %s (%s) via %s (%s)", from->name, from->hostname, to->name, to->hostname, relay->name, relay->hostname);
+	if(sendto(listen_socket[sock].udp.fd, buf, buf_ptr - buf, 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;
+			// Compensate for SPTPS overhead
+			len -= SPTPS_DATAGRAM_OVERHEAD;
+			if(relay->maxmtu >= len)
+				relay->maxmtu = len - 1;
+			if(relay->mtu >= len)
+				relay->mtu = len - 1;
 		} else {
-			logger(DEBUG_TRAFFIC, LOG_WARNING, "Error sending UDP SPTPS packet to %s (%s): %s", to->name, to->hostname, sockstrerror(sockerrno));
+			logger(DEBUG_TRAFFIC, LOG_WARNING, "Error sending UDP SPTPS packet to %s (%s): %s", relay->name, relay->hostname, sockstrerror(sockerrno));
 			return false;
 		}
 	}
@@ -805,6 +828,10 @@ bool send_sptps_data(void *handle, uint8_t type, const char *data, size_t len) {
 	return true;
 }
 
+bool send_sptps_data(void *handle, uint8_t type, const char *data, size_t len) {
+	return send_sptps_data_priv(handle, myself, type, data, len);
+}
+
 bool receive_sptps_record(void *handle, uint8_t type, const char *data, uint16_t len) {
 	node_t *from = handle;
 
@@ -948,7 +975,7 @@ 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;
 
@@ -1001,13 +1028,15 @@ static node_t *try_harder(const sockaddr_t *from, const vpn_packet_t *pkt) {
 void handle_incoming_vpn_data(void *data, int flags) {
 	listen_socket_t *ls = data;
 	vpn_packet_t pkt;
+	sptps_packet_t *spkt = (sptps_packet_t *)&pkt;
 	char *hostname;
-	sockaddr_t from = {{0}};
-	socklen_t fromlen = sizeof from;
-	node_t *n;
-	int len;
+	node_id_t nullid = {};
+	sockaddr_t addr = {};
+	socklen_t addrlen = sizeof addr;
+	node_t *from, *to;
+	bool direct = false;
 
-	len = recvfrom(ls->udp.fd, (char *) &pkt.seqno, MAXSIZE, 0, &from.sa, &fromlen);
+	int len = recvfrom(ls->udp.fd, &pkt.seqno, MAXSIZE, 0, &addr.sa, &addrlen);
 
 	if(len <= 0 || len > MAXSIZE) {
 		if(!sockwouldblock(sockerrno))
@@ -1017,27 +1046,66 @@ void handle_incoming_vpn_data(void *data, int flags) {
 
 	pkt.len = len;
 
-	sockaddrunmap(&from); /* Some braindead IPv6 implementations do stupid things. */
+	sockaddrunmap(&addr); /* Some braindead IPv6 implementations do stupid things. */
 
-	n = lookup_node_udp(&from);
+	// Try to figure out who sent this packet.
+
+	node_t *n = lookup_node_udp(&addr);
 
 	if(!n) {
-		n = try_harder(&from, &pkt);
-		if(n)
-			update_node_udp(n, &from);
-		else if(debug_level >= DEBUG_PROTOCOL) {
-			hostname = sockaddr2hostname(&from);
+		// It might be from a 1.1 node, which might have a source ID in the packet.
+		from = lookup_node_id(&spkt->srcid);
+		if(from && !memcmp(&spkt->dstid, &nullid, sizeof nullid) && from->status.sptps) {
+			if(sptps_verify_datagram(&from->sptps, spkt->data, spkt->len - sizeof(spkt->srcid) - sizeof(spkt->dstid)))
+				n = from;
+			else
+				goto skip_harder;
+		}
+	}
+
+	if(!n)
+		n = try_harder(&addr, &pkt);
+
+skip_harder:
+	if(!n) {
+		if(debug_level >= DEBUG_PROTOCOL) {
+			hostname = sockaddr2hostname(&addr);
 			logger(DEBUG_PROTOCOL, LOG_WARNING, "Received UDP packet from unknown source %s", hostname);
 			free(hostname);
+		}
+		return;
+	}
+
+	if(n->status.sptps) {
+		if(memcmp(&spkt->dstid, &nullid, sizeof nullid)) {
+			direct = true;
+			from = n;
+			to = myself;
+		} else {
+			from = lookup_node_id(&spkt->srcid);
+			to = lookup_node_id(&spkt->dstid);
+		}
+		if(!from || !to) {
+			logger(DEBUG_PROTOCOL, LOG_WARNING, "Received UDP packet from %s (%s) with unknown source and/or destination ID", n->name, n->hostname);
 			return;
 		}
-		else
+
+		spkt->len -= sizeof spkt->dstid + sizeof spkt->srcid;
+		if(to != myself) {
+			send_sptps_data_priv(to, n, 0, spkt->data, spkt->len);
 			return;
+		}
+	} else {
+		direct = true;
+		from = n;
 	}
 
-	n->sock = ls - listen_socket;
+	if(!receive_udppacket(from, &pkt))
+		return;
 
-	receive_udppacket(n, &pkt);
+	n->sock = ls - listen_socket;
+	if(direct && sockaddrcmp(&addr, &n->address))
+		update_node_udp(n, &addr);
 }
 
 void handle_device_data(void *data, int flags) {