X-Git-Url: https://tinc-vpn.org/git/browse?a=blobdiff_plain;f=src%2Fnet_packet.c;h=e9e2172c67f8ef6a5d44c3dc4d15312807d61cc5;hb=ae5b56c03d1e1af7561d7f1d1d8a333c3a9691ff;hp=456b43d23b1a958848b0a9fb67518d1689d74860;hpb=f3801cb54311da2c30cbe27cd66559a2ea5daa91;p=tinc

diff --git a/src/net_packet.c b/src/net_packet.c
index 456b43d2..e9e2172c 100644
--- a/src/net_packet.c
+++ b/src/net_packet.c
@@ -52,6 +52,11 @@
 #define MAX(a, b) ((a) > (b) ? (a) : (b))
 #endif
 
+/* The minimum size of a probe is 14 bytes, but since we normally use CBC mode
+   encryption, we can add a few extra random bytes without increasing the
+   resulting packet size. */
+#define MIN_PROBE_SIZE 18
+
 int keylifetime = 0;
 #ifdef HAVE_LZO
 static char lzo_wrkmem[LZO1X_999_MEM_COMPRESS > LZO1X_1_MEM_COMPRESS ? LZO1X_999_MEM_COMPRESS : LZO1X_1_MEM_COMPRESS];
@@ -62,7 +67,7 @@ static void send_udppacket(node_t *, vpn_packet_t *);
 unsigned replaywin = 16;
 bool localdiscovery = true;
 bool udp_discovery = true;
-int udp_discovery_keepalive_interval = 9;
+int udp_discovery_keepalive_interval = 10;
 int udp_discovery_interval = 2;
 int udp_discovery_timeout = 30;
 
@@ -90,101 +95,87 @@ static void udp_probe_timeout_handler(void *data) {
 
 	logger(DEBUG_TRAFFIC, LOG_INFO, "Too much time has elapsed since last UDP ping response from %s (%s), stopping UDP communication", n->name, n->hostname);
 	n->status.udp_confirmed = false;
+	n->maxrecentlen = 0;
 	n->mtuprobes = 0;
 	n->minmtu = 0;
 	n->maxmtu = MTU;
 }
 
+static void send_udp_probe_reply(node_t *n, vpn_packet_t *packet, length_t len) {
+	if(!n->status.sptps && !n->status.validkey) {
+		logger(DEBUG_TRAFFIC, LOG_INFO, "Trying to send UDP probe reply to %s (%s) but we don't have his key yet", n->name, n->hostname);
+		return;
+	}
+
+	/* Type 2 probe replies were introduced in protocol 17.3 */
+	if ((n->options >> 24) >= 3) {
+		DATA(packet)[0] = 2;
+		uint16_t len16 = htons(len);
+		memcpy(DATA(packet) + 1, &len16, 2);
+		packet->len = MIN_PROBE_SIZE;
+		logger(DEBUG_TRAFFIC, LOG_INFO, "Sending type 2 probe reply length %u to %s (%s)", len, n->name, n->hostname);
+
+	} else {
+		/* Legacy protocol: n won't understand type 2 probe replies. */
+		DATA(packet)[0] = 1;
+		logger(DEBUG_TRAFFIC, LOG_INFO, "Sending type 1 probe reply length %u to %s (%s)", len, n->name, n->hostname);
+	}
+
+	/* 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(n, packet);
+	n->status.udp_confirmed = udp_confirmed;
+}
+
 static void udp_probe_h(node_t *n, vpn_packet_t *packet, length_t len) {
 	if(!DATA(packet)[0]) {
 		logger(DEBUG_TRAFFIC, LOG_INFO, "Got UDP probe request %d from %s (%s)", packet->len, n->name, n->hostname);
+		return send_udp_probe_reply(n, packet, 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) {
-			uint8_t *data = DATA(packet);
-			*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 = 14; // Minimum size for any probe packet.
-		} else {
-			/* Legacy protocol: n won't understand type 2 probe replies. */
-			DATA(packet)[0] = 1;
-		}
-
-		/* Temporarily set udp_confirmed, so that the reply is sent
-		   back exactly the way it came in. */
+	if (DATA(packet)[0] == 2) {
+		// It's a type 2 probe reply, use the length field inside the packet
+		uint16_t len16;
+		memcpy(&len16, DATA(packet) + 1, 2);
+		len = ntohs(len16);
+	}
 
-		bool udp_confirmed = n->status.udp_confirmed;
-		n->status.udp_confirmed = true;
-		send_udppacket(n, packet);
-		n->status.udp_confirmed = udp_confirmed;
-	} else {
-		length_t probelen = len;
-		if (DATA(packet)[0] == 2) {
-			if (len < 3)
-				logger(DEBUG_TRAFFIC, LOG_WARNING, "Received invalid (too short) UDP probe reply from %s (%s)", n->name, n->hostname);
-			else {
-				uint16_t probelen16; memcpy(&probelen16, DATA(packet) + 1, 2); probelen = ntohs(probelen16);
-			}
-		}
-		logger(DEBUG_TRAFFIC, LOG_INFO, "Got type %d UDP probe reply %d from %s (%s)", DATA(packet)[0], probelen, n->name, n->hostname);
+	logger(DEBUG_TRAFFIC, LOG_INFO, "Got type %d UDP probe reply %d from %s (%s)", DATA(packet)[0], len, 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. */
-		n->status.udp_confirmed = true;
+	/* It's a valid reply: now we know bidirectional communication
+	   is possible using the address and socket that the reply
+	   packet used. */
+	n->status.udp_confirmed = true;
 
-		if(udp_discovery) {
-			timeout_del(&n->udp_ping_timeout);
-			timeout_add(&n->udp_ping_timeout, &udp_probe_timeout_handler, n, &(struct timeval){udp_discovery_timeout, 0});
-		}
+	// Reset the UDP ping timer.
+	n->udp_ping_sent = now;
 
-		if(probelen >= n->maxmtu + 1) {
-			logger(DEBUG_TRAFFIC, LOG_INFO, "Increase in PMTU to %s (%s) detected, restarting PMTU discovery", n->name, n->hostname);
-			n->maxmtu = MTU;
-			/* Set mtuprobes to 1 so that try_mtu() doesn't reset maxmtu */
-			n->mtuprobes = 1;
-			return;
-		}
+	if(udp_discovery) {
+		timeout_del(&n->udp_ping_timeout);
+		timeout_add(&n->udp_ping_timeout, &udp_probe_timeout_handler, n, &(struct timeval){udp_discovery_timeout, 0});
+	}
 
-		/* If applicable, raise the minimum supported MTU */
+	if(len > n->maxmtu) {
+		logger(DEBUG_TRAFFIC, LOG_INFO, "Increase in PMTU to %s (%s) detected, restarting PMTU discovery", n->name, n->hostname);
+		n->minmtu = len;
+		n->maxmtu = MTU;
+		/* Set mtuprobes to 1 so that try_mtu() doesn't reset maxmtu */
+		n->mtuprobes = 1;
+		return;
+	} else if(n->mtuprobes < 0 && len == n->maxmtu) {
+		/* We got a maxmtu sized packet, confirming the PMTU is still valid. */
+		n->mtuprobes = -1;
+		n->mtu_ping_sent = now;
+	}
 
-		if(probelen > n->maxmtu)
-			probelen = n->maxmtu;
-		if(n->minmtu < probelen) {
-			n->minmtu = probelen;
-			try_fix_mtu(n);
-		}
+	/* If applicable, raise the minimum supported MTU */
 
-		/* Calculate RTT.
-		   The RTT is the time between the MTU probe burst was sent and the first
-		   reply is received.
-		 */
-
-		struct timeval now, diff;
-		gettimeofday(&now, NULL);
-		timersub(&now, &n->probe_time, &diff);
-
-		struct timeval probe_timestamp = now;
-		if (DATA(packet)[0] == 2 && packet->len >= 11) {
-			uint32_t sec; memcpy(&sec, DATA(packet) + 3, 4);
-			uint32_t usec; memcpy(&usec, DATA(packet) + 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 = probe_timestamp;
-			logger(DEBUG_TRAFFIC, LOG_DEBUG, "%s (%s) RTT %.2f ms, rx packet loss %.2f %%", n->name, n->hostname, n->rtt * 1e3, n->packetloss * 1e2);
-		}
+	if(n->minmtu < len) {
+		n->minmtu = len;
+		try_fix_mtu(n);
 	}
 }
 
@@ -292,7 +283,11 @@ static bool receive_udppacket(node_t *n, vpn_packet_t *inpkt) {
 			return false;
 		}
 		inpkt->offset += 2 * sizeof(node_id_t);
-		if(!sptps_receive_data(&n->sptps, DATA(inpkt), inpkt->len - 2 * sizeof(node_id_t))) {
+		n->status.udppacket = true;
+		bool result = sptps_receive_data(&n->sptps, DATA(inpkt), inpkt->len - 2 * sizeof(node_id_t));
+		n->status.udppacket = false;
+
+		if(!result) {
 			logger(DEBUG_TRAFFIC, LOG_ERR, "Got bad packet from %s (%s)", n->name, n->hostname);
 			return false;
 		}
@@ -403,6 +398,9 @@ static bool receive_udppacket(node_t *n, vpn_packet_t *inpkt) {
 		origlen -= MTU/64 + 20;
 	}
 
+	if(inpkt->len > n->maxrecentlen)
+		n->maxrecentlen = inpkt->len;
+
 	inpkt->priority = 0;
 
 	if(!DATA(inpkt)[12] && !DATA(inpkt)[13])
@@ -773,8 +771,14 @@ bool receive_sptps_record(void *handle, uint8_t type, const void *data, uint16_t
 	inpkt.offset = DEFAULT_PACKET_OFFSET;
 
 	if(type == PKT_PROBE) {
+		if(!from->status.udppacket) {
+			logger(DEBUG_ALWAYS, LOG_ERR, "Got SPTPS PROBE packet from %s (%s) via TCP", from->name, from->hostname);
+			return false;
+		}
 		inpkt.len = len;
 		memcpy(DATA(&inpkt), data, len);
+		if(inpkt.len > from->maxrecentlen)
+			from->maxrecentlen = inpkt.len;
 		udp_probe_h(from, &inpkt, len);
 		return true;
 	}
@@ -826,6 +830,9 @@ bool receive_sptps_record(void *handle, uint8_t type, const void *data, uint16_t
 		}
 	}
 
+	if(from->status.udppacket && inpkt.len > from->maxrecentlen)
+		from->maxrecentlen = inpkt.len;
+
 	receive_packet(from, &inpkt);
 	return true;
 }
@@ -870,18 +877,40 @@ static void try_udp(node_t* n) {
 	if(!udp_discovery)
 		return;
 
+	/* Send gratuitous probe replies to 1.1 nodes. */
+
+	if((n->options >> 24) >= 3 && n->status.udp_confirmed) {
+		struct timeval ping_tx_elapsed;
+		timersub(&now, &n->udp_reply_sent, &ping_tx_elapsed);
+
+		if(ping_tx_elapsed.tv_sec >= udp_discovery_keepalive_interval - 1) {
+			n->udp_reply_sent = now;
+			if(n->maxrecentlen) {
+				vpn_packet_t pkt;
+				pkt.len = n->maxrecentlen;
+				pkt.offset = DEFAULT_PACKET_OFFSET;
+				memset(DATA(&pkt), 0, 14);
+				randomize(DATA(&pkt) + 14, MIN_PROBE_SIZE - 14);
+				send_udp_probe_reply(n, &pkt, pkt.len);
+				n->maxrecentlen = 0;
+			}
+		}
+	}
+
+	/* Probe request */
+
 	struct timeval ping_tx_elapsed;
 	timersub(&now, &n->udp_ping_sent, &ping_tx_elapsed);
 
 	int interval = n->status.udp_confirmed ? udp_discovery_keepalive_interval : udp_discovery_interval;
 
 	if(ping_tx_elapsed.tv_sec >= interval) {
-		send_udp_probe_packet(n, MAX(n->minmtu, 16));
+		send_udp_probe_packet(n, MIN_PROBE_SIZE);
 		n->udp_ping_sent = now;
 
 		if(localdiscovery && !n->status.udp_confirmed && n->prevedge) {
 			n->status.send_locally = true;
-			send_udp_probe_packet(n, 16);
+			send_udp_probe_packet(n, MIN_PROBE_SIZE);
 			n->status.send_locally = false;
 		}
 	}
@@ -978,6 +1007,7 @@ static void try_mtu(node_t *n) {
 		return;
 
 	if(udp_discovery && !n->status.udp_confirmed) {
+		n->maxrecentlen = 0;
 		n->mtuprobes = 0;
 		n->minmtu = 0;
 		n->maxmtu = MTU;
@@ -986,25 +1016,43 @@ static void try_mtu(node_t *n) {
 
 	/* mtuprobes == 0..19: initial discovery, send bursts with 1 second interval, mtuprobes++
 	   mtuprobes ==    20: fix MTU, and go to -1
-	   mtuprobes ==    -1: send one >maxmtu probe every pingtimeout */
+	   mtuprobes ==    -1: send one maxmtu and one maxmtu+1 probe every pinginterval
+	   mtuprobes ==-2..-3: send one maxmtu probe every second
+	   mtuprobes ==    -4: maxmtu no longer valid, reset minmtu and maxmtu and go to 0 */
 
 	struct timeval elapsed;
-	timersub(&now, &n->probe_sent_time, &elapsed);
+	timersub(&now, &n->mtu_ping_sent, &elapsed);
 	if(n->mtuprobes >= 0) {
 		if(n->mtuprobes != 0 && elapsed.tv_sec == 0 && elapsed.tv_usec < 333333)
 			return;
 	} else {
-		if(elapsed.tv_sec < pingtimeout)
-			return;
+		if(n->mtuprobes < -1) {
+			if(elapsed.tv_sec < 1)
+				return;
+		} else {
+			if(elapsed.tv_sec < pinginterval)
+				return;
+		}
 	}
 
+	n->mtu_ping_sent = now;
+
 	try_fix_mtu(n);
 
+	if(n->mtuprobes < -3) {
+		/* We lost three MTU probes, restart discovery */
+		logger(DEBUG_TRAFFIC, LOG_INFO, "Decrease in PMTU to %s (%s) detected, restarting PMTU discovery", n->name, n->hostname);
+		n->mtuprobes = 0;
+		n->minmtu = 0;
+	}
+
 	if(n->mtuprobes < 0) {
-		/* After the initial discovery, we only send one >maxmtu probe
-		   to detect PMTU increases. */
-		if(n->maxmtu + 1 < MTU)
+		/* After the initial discovery, we only send one maxmtu and one
+		   maxmtu+1 probe to detect PMTU increases. */
+		send_udp_probe_packet(n, n->maxmtu);
+		if(n->mtuprobes == -1 && n->maxmtu + 1 < MTU)
 			send_udp_probe_packet(n, n->maxmtu + 1);
+		n->mtuprobes--;
 	} else {
 		/* Before initial discovery begins, set maxmtu to the most likely value.
 		   If it's underestimated, we will correct it after initial discovery. */
@@ -1049,23 +1097,6 @@ static void try_mtu(node_t *n) {
 		if(n->mtuprobes >= 0)
 			n->mtuprobes++;
 	}
-
-	n->probe_counter = 0;
-	n->probe_sent_time = now;
-	n->probe_time = now;
-
-	/* Calculate the packet loss of incoming traffic by comparing the rate of
-	   packets received to the rate with which the sequence number has increased.
-	   TODO: this is unrelated to PMTU discovery - it should be moved elsewhere.
-	 */
-
-	if(n->received > n->prev_received)
-		n->packetloss = 1.0 - (n->received - n->prev_received) / (float)(n->received_seqno - n->prev_received_seqno);
-	else
-		n->packetloss = n->received_seqno <= n->prev_received_seqno;
-
-	n->prev_received_seqno = n->received_seqno;
-	n->prev_received = n->received;
 }
 
 /* These functions try to establish a tunnel to a node (or its relay) so that
@@ -1081,7 +1112,7 @@ static void try_mtu(node_t *n) {
    idle.
 */
 
-static void try_tx_sptps(node_t *n) {
+static void try_tx_sptps(node_t *n, bool mtu) {
 	/* If n is a TCP-only neighbor, we'll only use "cleartext" PACKET
 	   messages anyway, so there's no need for SPTPS at all. */
 
@@ -1104,13 +1135,14 @@ static void try_tx_sptps(node_t *n) {
 	/* If we do have a relay, try everything with that one instead. */
 
 	if(via != n)
-		return try_tx_sptps(via);
+		return try_tx_sptps(via, mtu);
 
 	try_udp(n);
-	try_mtu(n);
+	if(mtu)
+		try_mtu(n);
 }
 
-static void try_tx_legacy(node_t *n) {
+static void try_tx_legacy(node_t *n, bool mtu) {
 	/* Does he have our key? If not, send one. */
 
 	if(!n->status.validkey_in)
@@ -1127,7 +1159,15 @@ static void try_tx_legacy(node_t *n) {
 	}
 
 	try_udp(n);
-	try_mtu(n);
+	if(mtu)
+		try_mtu(n);
+}
+
+void try_tx(node_t *n, bool mtu) {
+	if(n->status.sptps)
+		try_tx_sptps(n, mtu);
+	else
+		try_tx_legacy(n, mtu);
 }
 
 void send_packet(node_t *n, vpn_packet_t *packet) {
@@ -1160,7 +1200,7 @@ void send_packet(node_t *n, vpn_packet_t *packet) {
 
 	if(n->status.sptps) {
 		send_sptps_packet(n, packet);
-		try_tx_sptps(n);
+		try_tx_sptps(n, true);
 		return;
 	}
 
@@ -1180,7 +1220,7 @@ void send_packet(node_t *n, vpn_packet_t *packet) {
 	}
 
 	send_udppacket(via, packet);
-	try_tx_legacy(via);
+	try_tx_legacy(via, true);
 }
 
 void broadcast_packet(const node_t *from, vpn_packet_t *packet) {