X-Git-Url: https://www.tinc-vpn.org/git/browse?p=tinc;a=blobdiff_plain;f=src%2Fnet_packet.c;h=054679e9aa0c75bca437e96443336a21d7ee53e4;hp=724eaa33e06ac3a3a524b99214502c8818748c1d;hb=724d79e88051b9c50704424c1cda2cedcf87dba0;hpb=bc9e78250ef6fb5169d03565b7d8d9caf309eb98

diff --git a/src/net_packet.c b/src/net_packet.c
index 724eaa33..054679e9 100644
--- a/src/net_packet.c
+++ b/src/net_packet.c
@@ -1,7 +1,9 @@
 /*
     net_packet.c -- Handles in- and outgoing VPN packets
-    Copyright (C) 1998-2002 Ivo Timmermans <ivo@o2w.nl>,
-                  2000-2002 Guus Sliepen <guus@sliepen.eu.org>
+    Copyright (C) 1998-2005 Ivo Timmermans,
+                  2000-2013 Guus Sliepen <guus@tinc-vpn.org>
+                  2010      Timothy Redaelli <timothy@redaelli.eu>
+                  2010      Brandon Black <blblack@gmail.com>
 
     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
@@ -13,102 +15,295 @@
     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 1.1.2.27 2003/04/18 21:18:36 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>
-#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>
-#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 "system.h"
 
 #include <openssl/rand.h>
+#include <openssl/err.h>
 #include <openssl/evp.h>
 #include <openssl/pem.h>
 #include <openssl/hmac.h>
 
+#ifdef HAVE_ZLIB
 #include <zlib.h>
+#endif
 
-#include <utils.h>
-#include <xalloc.h>
-#include <avl_tree.h>
-#include <list.h>
+#ifdef HAVE_LZO
+#include LZO1X_H
+#endif
 
+#include "avl_tree.h"
 #include "conf.h"
 #include "connection.h"
-#include "meta.h"
+#include "device.h"
+#include "ethernet.h"
+#include "event.h"
+#include "graph.h"
+#include "logger.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;
-EVP_CIPHER_CTX packet_ctx;
+#ifdef HAVE_LZO
+static char lzo_wrkmem[LZO1X_999_MEM_COMPRESS > LZO1X_1_MEM_COMPRESS ? LZO1X_999_MEM_COMPRESS : LZO1X_1_MEM_COMPRESS];
+#endif
+
+static void send_udppacket(node_t *, vpn_packet_t *);
+
+unsigned replaywin = 16;
+bool localdiscovery = false;
 
 #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.
+
+*/
+
+void send_mtu_probe(node_t *n) {
+	vpn_packet_t packet;
+	int len, i;
+	int timeout = 1;
+	
+	n->mtuprobes++;
+	n->mtuevent = NULL;
+
+	if(!n->status.reachable || !n->status.validkey) {
+		ifdebug(TRAFFIC) logger(LOG_INFO, "Trying to send MTU probe to unreachable or rekeying node %s (%s)", n->name, n->hostname);
+		n->mtuprobes = 0;
+		return;
+	}
+
+	if(n->mtuprobes > 32) {
+		if(!n->minmtu) {
+			n->mtuprobes = 31;
+			timeout = pinginterval;
+			goto end;
+		}
+
+		ifdebug(TRAFFIC) logger(LOG_INFO, "%s (%s) did not respond to UDP ping, restarting PMTU discovery", n->name, n->hostname);
+		n->mtuprobes = 1;
+		n->minmtu = 0;
+		n->maxmtu = MTU;
+	}
+
+	if(n->mtuprobes >= 10 && n->mtuprobes < 32 && !n->minmtu) {
+		ifdebug(TRAFFIC) logger(LOG_INFO, "No response to MTU probes from %s (%s)", n->name, n->hostname);
+		n->mtuprobes = 31;
+	}
+
+	if(n->mtuprobes == 30 || (n->mtuprobes < 30 && n->minmtu >= n->maxmtu)) {
+		if(n->minmtu > n->maxmtu)
+			n->minmtu = n->maxmtu;
+		else
+			n->maxmtu = n->minmtu;
+		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);
+		n->mtuprobes = 31;
+	}
+
+	if(n->mtuprobes == 31) {
+		timeout = pinginterval;
+		goto end;
+	} else if(n->mtuprobes == 32) {
+		timeout = pingtimeout;
+	}
+
+	for(i = 0; i < 4 + localdiscovery; i++) {
+		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 + rand() % (n->maxmtu - n->minmtu);
+		}
+
+		if(len < 64)
+			len = 64;
+		
+		memset(packet.data, 0, 14);
+		RAND_pseudo_bytes(packet.data + 14, len - 14);
+		packet.len = len;
+		if(i >= 4 && n->mtuprobes <= 10)
+			packet.priority = -1;
+		else
+			packet.priority = 0;
+
+		ifdebug(TRAFFIC) logger(LOG_INFO, "Sending MTU probe length %d to %s (%s)", len, n->name, n->hostname);
+
+		send_udppacket(n, &packet);
+	}
+
+end:
+	n->mtuevent = new_event();
+	n->mtuevent->handler = (event_handler_t)send_mtu_probe;
+	n->mtuevent->data = n;
+	n->mtuevent->time = now + timeout;
+	event_add(n->mtuevent);
+}
+
+void mtu_probe_h(node_t *n, vpn_packet_t *packet, length_t len) {
+	ifdebug(TRAFFIC) logger(LOG_INFO, "Got MTU probe length %d from %s (%s)", packet->len, n->name, n->hostname);
+
+	if(!packet->data[0]) {
+		packet->data[0] = 1;
+		send_udppacket(n, packet);
+	} else {
+		if(n->mtuprobes > 30) {
+			if (len == n->maxmtu + 8) {
+				ifdebug(TRAFFIC) logger(LOG_INFO, "Increase in PMTU to %s (%s) detected, restarting PMTU discovery", n->name, n->hostname);
+				n->maxmtu = MTU;
+				n->mtuprobes = 10;
+				return;
+			}
+
+			if(n->minmtu)
+				n->mtuprobes = 30;
+			else
+				n->mtuprobes = 1;
+		}
+
+		if(len > n->maxmtu)
+			len = n->maxmtu;
+		if(n->minmtu < len)
+			n->minmtu = len;
+	}
+}
+
+static length_t compress_packet(uint8_t *dest, const uint8_t *source, length_t len, int level) {
+	if(level == 0) {
+		memcpy(dest, source, len);
+		return len;
+	} else if(level == 10) {
+#ifdef HAVE_LZO
+		lzo_uint lzolen = MAXSIZE;
+		lzo1x_1_compress(source, len, dest, &lzolen, lzo_wrkmem);
+		return lzolen;
+#else
+		return -1;
+#endif
+	} else if(level < 10) {
+#ifdef HAVE_ZLIB
+		unsigned long destlen = MAXSIZE;
+		if(compress2(dest, &destlen, source, len, level) == Z_OK)
+			return destlen;
+		else
+#endif
+			return -1;
+	} else {
+#ifdef HAVE_LZO
+		lzo_uint lzolen = MAXSIZE;
+		lzo1x_999_compress(source, len, dest, &lzolen, lzo_wrkmem);
+		return lzolen;
+#else
+		return -1;
+#endif
+	}
+	
+	return -1;
+}
+
+static length_t uncompress_packet(uint8_t *dest, const uint8_t *source, length_t len, int level) {
+	if(level == 0) {
+		memcpy(dest, source, len);
+		return len;
+	} else if(level > 9) {
+#ifdef HAVE_LZO
+		lzo_uint lzolen = MAXSIZE;
+		if(lzo1x_decompress_safe(source, len, dest, &lzolen, NULL) == LZO_E_OK)
+			return lzolen;
+		else
+#endif
+			return -1;
+	}
+#ifdef HAVE_ZLIB
+	else {
+		unsigned long destlen = MAXSIZE;
+		if(uncompress(dest, &destlen, source, len) == Z_OK)
+			return destlen;
+		else
+			return -1;
+	}
+#endif
+
+	return -1;
+}
+
 /* VPN packet I/O */
 
-void receive_udppacket(node_t *n, vpn_packet_t *inpkt)
-{
+static void receive_packet(node_t *n, vpn_packet_t *packet) {
+	ifdebug(TRAFFIC) logger(LOG_DEBUG, "Received packet of %d bytes from %s (%s)",
+			   packet->len, n->name, n->hostname);
+
+	route(n, packet);
+}
+
+static bool try_mac(const node_t *n, const vpn_packet_t *inpkt) {
+	unsigned char hmac[EVP_MAX_MD_SIZE];
+
+	if(!n->indigest || !n->inmaclength || !n->inkey || inpkt->len < sizeof inpkt->seqno + n->inmaclength)
+		return false;
+
+	HMAC(n->indigest, n->inkey, n->inkeylength, (unsigned char *) &inpkt->seqno, inpkt->len - n->inmaclength, (unsigned char *)hmac, NULL);
+
+	return !memcmp(hmac, (char *) &inpkt->seqno + inpkt->len - n->inmaclength, n->inmaclength);
+}
+
+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];
 	int outlen, outpad;
-	long int complen = MTU + 12;
-	char hmac[EVP_MAX_MD_SIZE];
+	unsigned char hmac[EVP_MAX_MD_SIZE];
 	int i;
 
-	cp();
+	if(!n->inkey) {
+		ifdebug(TRAFFIC) logger(LOG_DEBUG, "Got packet from %s (%s) but he hasn't got our key yet",
+					n->name, n->hostname);
+		return;
+	}
+
+	/* Check packet length */
+
+	if(inpkt->len < sizeof(inpkt->seqno) + n->inmaclength) {
+		ifdebug(TRAFFIC) logger(LOG_DEBUG, "Got too short packet from %s (%s)",
+					n->name, n->hostname);
+		return;
+	}
 
 	/* 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(n->indigest && n->inmaclength) {
+		inpkt->len -= n->inmaclength;
+		HMAC(n->indigest, n->inkey, n->inkeylength,
+			 (unsigned char *) &inpkt->seqno, inpkt->len, (unsigned char *)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)"),
+		if(memcmp(hmac, (char *) &inpkt->seqno + inpkt->len, n->inmaclength)) {
+			ifdebug(TRAFFIC) logger(LOG_DEBUG, "Got unauthenticated packet from %s (%s)",
 					   n->name, n->hostname);
 			return;
 		}
@@ -116,14 +311,17 @@ void receive_udppacket(node_t *n, vpn_packet_t *inpkt)
 
 	/* Decrypt the packet */
 
-	if(myself->cipher) {
+	if(n->incipher) {
 		outpkt = pkt[nextpkt++];
 
-		EVP_DecryptInit_ex(&packet_ctx, myself->cipher, NULL, myself->key,
-						myself->key + myself->cipher->key_len);
-		EVP_DecryptUpdate(&packet_ctx, (char *) &outpkt->seqno, &outlen,
-						  (char *) &inpkt->seqno, inpkt->len);
-		EVP_DecryptFinal_ex(&packet_ctx, (char *) &outpkt->seqno + outlen, &outpad);
+		if(!EVP_DecryptInit_ex(&n->inctx, NULL, NULL, NULL, NULL)
+				|| !EVP_DecryptUpdate(&n->inctx, (unsigned char *) &outpkt->seqno, &outlen,
+					(unsigned char *) &inpkt->seqno, inpkt->len)
+				|| !EVP_DecryptFinal_ex(&n->inctx, (unsigned char *) &outpkt->seqno + outlen, &outpad)) {
+			ifdebug(TRAFFIC) logger(LOG_DEBUG, "Error decrypting packet from %s (%s): %s",
+						n->name, n->hostname, ERR_error_string(ERR_get_error(), NULL));
+			return;
+		}
 		
 		outpkt->len = outlen + outpad;
 		inpkt = outpkt;
@@ -134,108 +332,125 @@ void receive_udppacket(node_t *n, vpn_packet_t *inpkt)
 	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) {
-			if(debug_lvl >= DEBUG_TRAFFIC)
-				syslog(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(inpkt->seqno <= n->received_seqno - sizeof(n->late) * 8 || !(n->late[(inpkt->seqno / 8) % sizeof(n->late)] & (1 << inpkt->seqno % 8))) {
-				syslog(LOG_WARNING, _("Got late or replayed packet from %s (%s), seqno %d, last received %d"),
-					   n->name, n->hostname, inpkt->seqno, n->received_seqno, n->late[(inpkt->seqno / 8) % sizeof(n->late)]);
-			} else
+	if(replaywin) {
+		if(inpkt->seqno != n->received_seqno + 1) {
+			if(inpkt->seqno >= n->received_seqno + replaywin * 8) {
+				if(n->farfuture++ < replaywin >> 2) {
+					logger(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;
+				}
+				logger(LOG_WARNING, "Lost %d packets from %s (%s)",
+					   	inpkt->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))) {
+					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[(inpkt->seqno / 8) % sizeof(n->late)] |= 1 << i % 8;
+					n->late[(i / 8) % replaywin] |= 1 << i % 8;
+			}
 		}
+
+		n->farfuture = 0;
+		n->late[(inpkt->seqno / 8) % replaywin] &= ~(1 << inpkt->seqno % 8);
 	}
-	
-	n->received_seqno = inpkt->seqno;
-	n->late[(n->received_seqno / 8) % sizeof(n->late)] &= ~(1 << n->received_seqno % 8);
+
+	if(inpkt->seqno > n->received_seqno)
+		n->received_seqno = inpkt->seqno;
 			
 	if(n->received_seqno > MAX_SEQNO)
 		keyexpires = 0;
 
 	/* Decompress the packet */
 
-	if(myself->compression) {
+	length_t origlen = inpkt->len;
+
+	if(n->incompression) {
 		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);
+		if((outpkt->len = uncompress_packet(outpkt->data, inpkt->data, inpkt->len, n->incompression)) < 0) {
+			ifdebug(TRAFFIC) logger(LOG_ERR, "Error while uncompressing packet from %s (%s)",
+				  		 n->name, n->hostname);
 			return;
 		}
 
-		outpkt->len = complen;
 		inpkt = outpkt;
+
+		origlen -= MTU/64 + 20;
 	}
 
-	receive_packet(n, inpkt);
+	inpkt->priority = 0;
+
+	if(!inpkt->data[12] && !inpkt->data[13])
+		mtu_probe_h(n, inpkt, origlen);
+	else
+		receive_packet(n, inpkt);
 }
 
-void receive_tcppacket(connection_t *c, char *buffer, int len)
-{
+void receive_tcppacket(connection_t *c, const char *buffer, int len) {
 	vpn_packet_t outpkt;
 
-	cp();
+	if(len > sizeof outpkt.data)
+		return;
 
 	outpkt.len = len;
+	if(c->options & OPTION_TCPONLY)
+		outpkt.priority = 0;
+	else
+		outpkt.priority = -1;
 	memcpy(outpkt.data, buffer, len);
 
 	receive_packet(c->node, &outpkt);
 }
 
-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);
-
-	route_incoming(n, packet);
-}
-
-void send_udppacket(node_t *n, vpn_packet_t *inpkt)
-{
+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;
 	int outlen, outpad;
-	long int complen = MTU + 12;
-	vpn_packet_t *copy;
+#if defined(SOL_IP) && defined(IP_TOS)
 	static int priority = 0;
+#endif
 	int origpriority;
-	int sock;
 
-	cp();
+	if(!n->status.reachable) {
+		ifdebug(TRAFFIC) logger(LOG_INFO, "Trying to send UDP packet to unreachable node %s (%s)", n->name, n->hostname);
+		return;
+	}
 
 	/* 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"),
+		ifdebug(TRAFFIC) logger(LOG_INFO,
+				   "No valid key known yet for %s (%s), forwarding via TCP",
 				   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));
+		if(n->last_req_key + 10 <= now) {
+			send_req_key(n);
+			n->last_req_key = now;
+		}
 
-		list_insert_tail(n->queue, copy);
+		send_tcppacket(n->nexthop->connection, origpkt);
 
-		if(n->queue->count > MAXQUEUELENGTH)
-			list_delete_head(n->queue);
+		return;
+	}
 
-		if(!n->status.waitingforkey)
-			send_req_key(n->nexthop->connection, myself, n);
+	if(n->options & OPTION_PMTU_DISCOVERY && inpkt->len > n->minmtu && (inpkt->data[12] | inpkt->data[13])) {
+		ifdebug(TRAFFIC) logger(LOG_INFO,
+				"Packet for %s (%s) larger than minimum MTU, forwarding via %s",
+				n->name, n->hostname, n != n->nexthop ? n->nexthop->name : "TCP");
 
-		n->status.waitingforkey = 1;
+		if(n != n->nexthop)
+			send_packet(n->nexthop, origpkt);
+		else
+			send_tcppacket(n->nexthop->connection, origpkt);
 
 		return;
 	}
@@ -245,18 +460,15 @@ void send_udppacket(node_t *n, vpn_packet_t *inpkt)
 
 	/* Compress the packet */
 
-	if(n->compression) {
+	if(n->outcompression) {
 		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)"),
+		if((outpkt->len = compress_packet(outpkt->data, inpkt->data, inpkt->len, n->outcompression)) < 0) {
+			ifdebug(TRAFFIC) logger(LOG_ERR, "Error while compressing packet to %s (%s)",
 				   n->name, n->hostname);
 			return;
 		}
 
-		outpkt->len = complen;
 		inpkt = outpkt;
 	}
 
@@ -267,13 +479,17 @@ void send_udppacket(node_t *n, vpn_packet_t *inpkt)
 
 	/* Encrypt the packet */
 
-	if(n->cipher) {
+	if(n->outcipher) {
 		outpkt = pkt[nextpkt++];
 
-		EVP_EncryptInit_ex(&packet_ctx, n->cipher, NULL, n->key, n->key + n->cipher->key_len);
-		EVP_EncryptUpdate(&packet_ctx, (char *) &outpkt->seqno, &outlen,
-						  (char *) &inpkt->seqno, inpkt->len);
-		EVP_EncryptFinal_ex(&packet_ctx, (char *) &outpkt->seqno + outlen, &outpad);
+		if(!EVP_EncryptInit_ex(&n->outctx, NULL, NULL, NULL, NULL)
+				|| !EVP_EncryptUpdate(&n->outctx, (unsigned char *) &outpkt->seqno, &outlen,
+					(unsigned char *) &inpkt->seqno, inpkt->len)
+				|| !EVP_EncryptFinal_ex(&n->outctx, (unsigned char *) &outpkt->seqno + outlen, &outpad)) {
+			ifdebug(TRAFFIC) logger(LOG_ERR, "Error while encrypting packet to %s (%s): %s",
+						n->name, n->hostname, ERR_error_string(ERR_get_error(), NULL));
+			goto end;
+		}
 
 		outpkt->len = outlen + outpad;
 		inpkt = outpkt;
@@ -281,150 +497,214 @@ void send_udppacket(node_t *n, vpn_packet_t *inpkt)
 
 	/* 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;
+	if(n->outdigest && n->outmaclength) {
+		HMAC(n->outdigest, n->outkey, n->outkeylength, (unsigned char *) &inpkt->seqno,
+			 inpkt->len, (unsigned char *) &inpkt->seqno + inpkt->len, NULL);
+		inpkt->len += n->outmaclength;
 	}
 
 	/* 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. */
+	if(n->address.sa.sa_family != listen_socket[n->sock].sa.sa.sa_family) {
+		for(int sock = 0; sock < listen_sockets; sock++) {
+			if(n->address.sa.sa_family == listen_socket[sock].sa.sa.sa_family) {
+				n->sock = sock;
+				break;
+			}
+		}
+	}
 
 	/* Send the packet */
 
+	struct sockaddr *sa;
+	socklen_t sl;
+	int sock;
+	sockaddr_t broadcast;
+
+	/* Overloaded use of priority field: -1 means local broadcast */
+
+	if(origpriority == -1 && n->prevedge) {
+		sock = rand() % listen_sockets;
+		memset(&broadcast, 0, sizeof broadcast);
+		if(listen_socket[sock].sa.sa.sa_family == AF_INET6) {
+			broadcast.in6.sin6_family = AF_INET6;
+			broadcast.in6.sin6_addr.s6_addr[0x0] = 0xff;
+			broadcast.in6.sin6_addr.s6_addr[0x1] = 0x02;
+			broadcast.in6.sin6_addr.s6_addr[0xf] = 0x01;
+			broadcast.in6.sin6_port = n->prevedge->address.in.sin_port;
+			broadcast.in6.sin6_scope_id = listen_socket[sock].sa.in6.sin6_scope_id;
+		} else {
+			broadcast.in.sin_family = AF_INET;
+			broadcast.in.sin_addr.s_addr = -1;
+			broadcast.in.sin_port = n->prevedge->address.in.sin_port;
+		}
+		sa = &broadcast.sa;
+		sl = SALEN(broadcast.sa);
+	} else {
+		if(origpriority == -1)
+			origpriority = 0;
+
+		sa = &(n->address.sa);
+		sl = SALEN(n->address.sa);
+		sock = n->sock;
+	}
+
 #if defined(SOL_IP) && defined(IP_TOS)
 	if(priorityinheritance && origpriority != priority
-	   && listen_socket[sock].sa.sa.sa_family == AF_INET) {
+	   && listen_socket[n->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(listen_socket[sock].udp, 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));
+		ifdebug(TRAFFIC) logger(LOG_DEBUG, "Setting outgoing packet priority to %d", priority);
+		if(setsockopt(listen_socket[n->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));
 	}
 #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;
+	if(sendto(listen_socket[sock].udp, (char *) &inpkt->seqno, inpkt->len, 0, sa, sl) < 0 && !sockwouldblock(sockerrno)) {
+		if(sockmsgsize(sockerrno)) {
+			if(n->maxmtu >= origlen)
+				n->maxmtu = origlen - 1;
+			if(n->mtu >= origlen)
+				n->mtu = origlen - 1;
+		} else
+			ifdebug(TRAFFIC) logger(LOG_WARNING, "Error sending packet to %s (%s): %s", n->name, n->hostname, sockstrerror(sockerrno));
 	}
 
-	inpkt->len = origlen;
+end:
+	origpkt->len = origlen;
 }
 
 /*
   send a packet to the given vpn ip.
 */
-void send_packet(node_t *n, vpn_packet_t *packet)
-{
+void send_packet(const 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!"));
-
+		if(overwrite_mac)
+			 memcpy(packet->data, mymac.x, ETH_ALEN);
+		devops.write(packet);
 		return;
 	}
 
+	ifdebug(TRAFFIC) logger(LOG_ERR, "Sending packet of %d bytes to %s (%s)",
+			   packet->len, n->name, n->hostname);
+
 	if(!n->status.reachable) {
-		if(debug_lvl >= DEBUG_TRAFFIC)
-			syslog(LOG_INFO, _("Node %s (%s) is not reachable"),
+		ifdebug(TRAFFIC) logger(LOG_INFO, "Node %s (%s) is not reachable",
 				   n->name, n->hostname);
-
 		return;
 	}
 
-	via = (n->via == myself) ? n->nexthop : n->via;
+	via = (packet->priority == -1 || n->via == myself) ? n->nexthop : n->via;
 
-	if(via != n && debug_lvl >= DEBUG_TRAFFIC)
-		syslog(LOG_ERR, _("Sending packet to %s via %s (%s)"),
+	if(via != n)
+		ifdebug(TRAFFIC) logger(LOG_INFO, "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);
+	if(packet->priority == -1 || ((myself->options | via->options) & OPTION_TCPONLY)) {
+		if(!send_tcppacket(via->connection, packet))
+			terminate_connection(via->connection, true);
 	} else
 		send_udppacket(via, packet);
 }
 
 /* Broadcast a packet using the minimum spanning tree */
 
-void broadcast_packet(node_t *from, vpn_packet_t *packet)
-{
+void broadcast_packet(const node_t *from, vpn_packet_t *packet) {
 	avl_node_t *node;
 	connection_t *c;
+	node_t *n;
 
-	cp();
+	// Always give ourself a copy of the packet.
+	if(from != myself)
+		send_packet(myself, packet);
+
+	// In TunnelServer mode, do not forward broadcast packets.
+        // The MST might not be valid and create loops.
+	if(tunnelserver || broadcast_mode == BMODE_NONE)
+		return;
 
-	if(debug_lvl >= DEBUG_TRAFFIC)
-		syslog(LOG_INFO, _("Broadcasting packet of %d bytes from %s (%s)"),
+	ifdebug(TRAFFIC) logger(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;
+	switch(broadcast_mode) {
+		// In MST mode, broadcast packets travel via the Minimum Spanning Tree.
+		// This guarantees all nodes receive the broadcast packet, and
+		// usually distributes the sending of broadcast packets over all nodes.
+		case BMODE_MST:
+			for(node = connection_tree->head; node; node = node->next) {
+				c = node->data;
+
+				if(c->status.active && c->status.mst && c != from->nexthop->connection)
+					send_packet(c->node, packet);
+			}
+			break;
+
+		// In direct mode, we send copies to each node we know of.
+	        // However, this only reaches nodes that can be reached in a single hop.
+		// We don't have enough information to forward broadcast packets in this case.
+		case BMODE_DIRECT:
+			if(from != myself)
+				break;
 
-		if(c->status.active && c->status.mst && c != from->nexthop->connection)
-			send_packet(c->node, packet);
+			for(node = node_udp_tree->head; node; node = node->next) {
+				n = node->data;
+
+				if(n->status.reachable && ((n->via == myself && n->nexthop == n) || n->via == n))
+					send_packet(n, packet);
+			}
+			break;
+
+		default:
+			break;
 	}
 }
 
-void flush_queue(node_t *n)
-{
-	list_node_t *node, *next;
+static node_t *try_harder(const sockaddr_t *from, const vpn_packet_t *pkt) {
+	avl_node_t *node;
+	edge_t *e;
+	node_t *n = NULL;
+	bool hard = false;
+	static time_t last_hard_try = 0;
 
-	cp();
+	for(node = edge_weight_tree->head; node; node = node->next) {
+		e = node->data;
 
-	if(debug_lvl >= DEBUG_TRAFFIC)
-		syslog(LOG_INFO, _("Flushing queue for %s (%s)"), n->name, n->hostname);
+		if(e->to == myself)
+			continue;
+
+		if(sockaddrcmp_noport(from, &e->address)) {
+			if(last_hard_try == now)
+				continue;
+			hard = true;
+		}
 
-	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);
+		if(!try_mac(e->to, pkt))
+			continue;
+
+		n = e->to;
+		break;
 	}
+
+	if(hard)
+		last_hard_try = now;
+
+	last_hard_try = now;
+	return n;
 }
 
-void handle_incoming_vpn_data(int sock)
-{
+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;
-	}
-
-	pkt.len = recvfrom(sock, (char *) &pkt.seqno, MAXSIZE, 0, &from.sa, &fromlen);
+	pkt.len = recvfrom(listen_socket[sock].udp, (char *) &pkt.seqno, MAXSIZE, 0, &from.sa, &fromlen);
 
-	if(pkt.len <= 0) {
-		syslog(LOG_ERR, _("Receiving packet failed: %s"), strerror(errno));
+	if(pkt.len < 0) {
+		if(!sockwouldblock(sockerrno))
+			logger(LOG_ERR, "Receiving packet failed: %s", sockstrerror(sockerrno));
 		return;
 	}
 
@@ -433,15 +713,20 @@ void handle_incoming_vpn_data(int sock)
 	n = lookup_node_udp(&from);
 
 	if(!n) {
-		hostname = sockaddr2hostname(&from);
-		syslog(LOG_WARNING, _("Received UDP packet from unknown source %s"),
-			   hostname);
-		free(hostname);
-		return;
+		n = try_harder(&from, &pkt);
+		if(n)
+			update_node_udp(n, &from);
+		else ifdebug(PROTOCOL) {
+			hostname = sockaddr2hostname(&from);
+			logger(LOG_WARNING, "Received UDP packet from unknown source %s", hostname);
+			free(hostname);
+			return;
+		}
+		else
+			return;
 	}
 
-	if(n->connection)
-		n->connection->last_ping_time = now;
+	n->sock = sock;
 
 	receive_udppacket(n, &pkt);
 }