X-Git-Url: https://tinc-vpn.org/git/browse?a=blobdiff_plain;f=src%2Fnet_packet.c;h=27a6542c22a959f1a0e75eb131fa8c89956c7f2b;hb=8e43a2fc744559956640d3eb9a7a26a945d94fde;hp=45989518ac8b3f6d9b58edcd6d59d4d59d40a056;hpb=fa432426df7e2e364e310ab4bac28e60f732a3c9;p=tinc

diff --git a/src/net_packet.c b/src/net_packet.c
index 45989518..27a6542c 100644
--- a/src/net_packet.c
+++ b/src/net_packet.c
@@ -64,7 +64,7 @@ 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;
+unsigned replaywin = 32;
 bool localdiscovery = true;
 bool udp_discovery = true;
 int udp_discovery_keepalive_interval = 10;
@@ -687,9 +687,7 @@ static bool send_sptps_data_priv(node_t *to, node_t *from, int type, const void
 	bool relay_supported = (relay->options >> 24) >= 4;
 	bool tcponly = (myself->options | relay->options) & OPTION_TCPONLY;
 
-	/* 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. */
+	/* 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. */
 
 	if(type == SPTPS_HANDSHAKE || tcponly || (!direct && !relay_supported) || (type != PKT_PROBE && (len - SPTPS_DATAGRAM_OVERHEAD) > relay->minmtu)) {
 		char buf[len * 4 / 3 + 5];
@@ -1394,9 +1392,20 @@ skip_harder:
 			return;
 		}
 
+		/* The packet is supposed to come from the originator or its static relay
+		   (i.e. with no dynamic relays in between).
+		   If it did not, "help" the static relay by sending it UDP info.
+		   Note that we only do this if we're the destination or the static relay;
+		   otherwise every hop would initiate its own UDP info message, resulting in elevated chatter. */
+
+		if(n != from->via && to->via == myself)
+			send_udp_info(myself, from);
+
+		/* If we're not the final recipient, relay the packet. */
+
 		if(to != myself) {
-			send_sptps_data_priv(to, n, 0, DATA(&pkt), pkt.len - 2 * sizeof(node_id_t));
-			try_tx_sptps(n, true);
+			send_sptps_data_priv(to, from, 0, DATA(&pkt), pkt.len - 2 * sizeof(node_id_t));
+			try_tx_sptps(to, true);
 			return;
 		}
 	} else {
@@ -1411,6 +1420,12 @@ skip_harder:
 	n->sock = ls - listen_socket;
 	if(direct && sockaddrcmp(&addr, &n->address))
 		update_node_udp(n, &addr);
+
+	/* If the packet went through a relay, help the sender find the appropriate MTU
+	   through the relay path. */
+
+	if(!direct)
+		send_mtu_info(myself, n, MTU);
 }
 
 void handle_device_data(void *data, int flags) {