save unacked seqn. handle acked option. calculate RTT

libi2pd_client/UDPTunnel.cpp

@@ -38,10 +38,10 @@ namespace client
 			if (options->Get (UDP_SESSION_SEQN, seqn) && seqn > m_LastSession->m_LastReceivedPacketNum)
 			{	
 				m_LastSession->m_LastReceivedPacketNum = seqn;
-				i2p::util::Mapping options;
-				options.Put (UDP_SESSION_ACKED, m_LastSession->m_LastReceivedPacketNum);
+				i2p::util::Mapping replyOptions;
+				replyOptions.Put (UDP_SESSION_ACKED, m_LastSession->m_LastReceivedPacketNum);
 				m_LastSession->m_Destination->SendDatagram(m_LastSession->GetDatagramSession (),
-					nullptr, 0, m_LastSession->LocalPort, m_LastSession->RemotePort, &options); // Ack only, no payload
+					nullptr, 0, m_LastSession->LocalPort, m_LastSession->RemotePort, &replyOptions); // Ack only, no payload
 			}	
 		}		
 	}
@@ -277,7 +277,7 @@ namespace client
 		m_Name (name), m_RemoteDest (remoteDest), m_LocalDest (localDestination), m_LocalEndpoint (localEndpoint),
 		m_ResolveThread (nullptr), m_LocalSocket (nullptr), RemotePort (remotePort),
 		m_LastPort (0), m_cancel_resolve (false), m_Gzip (gzip), m_DatagramVersion (datagramVersion),
-		m_NextSendPacketNum (1), m_LastReceivedPacketNum (0)
+		m_NextSendPacketNum (1), m_LastReceivedPacketNum (0), m_RTT (0)
 	{
 	}
 
@@ -377,10 +377,13 @@ namespace client
 		auto ts = i2p::util::GetMillisecondsSinceEpoch ();
 		LogPrint (eLogDebug, "UDP Client: Send ", transferred, " to ", m_RemoteAddr->identHash.ToBase32 (), ":", RemotePort);
 		auto session = GetDatagramSession ();
-		if (ts > m_LastSession->second + I2P_UDP_REPLIABLE_DATAGRAM_INTERVAL)
+		uint64_t repliableDatagramInterval = I2P_UDP_REPLIABLE_DATAGRAM_INTERVAL;
+		if (m_RTT && m_RTT < I2P_UDP_REPLIABLE_DATAGRAM_INTERVAL*10) repliableDatagramInterval = m_RTT/10;
+		if (ts > m_LastSession->second + repliableDatagramInterval )
 		{	
 			if (m_DatagramVersion == i2p::datagram::eDatagramV3)
 			{	
+				m_UnackedDatagrams.push_back ({ m_NextSendPacketNum, ts });
 				i2p::util::Mapping options;
 				options.Put (UDP_SESSION_SEQN, m_NextSendPacketNum);
 				if (m_LastReceivedPacketNum > 0)
@@ -467,11 +470,13 @@ namespace client
 				if (options->Get (UDP_SESSION_SEQN, seqn) && seqn > m_LastReceivedPacketNum)
 				{	
 					m_LastReceivedPacketNum = seqn;
-					i2p::util::Mapping options;
-					options.Put (UDP_SESSION_ACKED, m_LastReceivedPacketNum);
+					i2p::util::Mapping replyOptions;
+					replyOptions.Put (UDP_SESSION_ACKED, m_LastReceivedPacketNum);
 					m_LocalDest->GetDatagramDestination ()->SendDatagram (GetDatagramSession (),
-						nullptr, 0, m_LastPort, RemotePort, &options); // Ack only, no payload
-				}	
+						nullptr, 0, m_LastPort, RemotePort, &replyOptions); // Ack only, no payload
+				}
+				if (options->Get (UDP_SESSION_ACKED, seqn))
+					Acked (seqn);
 			}
 			if (len > 0)
 				HandleRecvFromI2PRaw (fromPort, toPort, buf, len);
@@ -503,5 +508,19 @@ namespace client
 			LogPrint (eLogWarning, "UDP Client: Not tracking udp session using port ", (int) toPort);
 	}
 
+	void I2PUDPClientTunnel::Acked (uint32_t seqn)
+	{
+		if (m_UnackedDatagrams.empty () && seqn < m_UnackedDatagrams.front ().first) return;
+		auto it = m_UnackedDatagrams.begin ();
+		while (it != m_UnackedDatagrams.end ())
+		{
+			if (it->first > seqn) break;
+			if (it->first == seqn)
+				m_RTT = i2p::util::GetMillisecondsSinceEpoch () - it->second;
+			it++;
+		}	
+		m_UnackedDatagrams.erase (m_UnackedDatagrams.begin (), it);
+	}	
+		
 }
 }

libi2pd_client/UDPTunnel.h

@@ -14,6 +14,7 @@
 #include <memory>
 #include <thread>
 #include <vector>
+#include <list>
 #include <unordered_map>
 #include <boost/asio.hpp>
 #include "util.h"
@@ -32,7 +33,7 @@ namespace client
 
 	/** max size for i2p udp */
 	const size_t I2P_UDP_MAX_MTU = 64*1024;
-
+	
 	struct UDPSession
 	{
 		i2p::datagram::DatagramDestination * m_Destination;
@@ -110,7 +111,7 @@ namespace client
 			void HandleRecvFromI2PRaw (uint16_t fromPort, uint16_t toPort, const uint8_t * buf, size_t len);
 			UDPSessionPtr ObtainUDPSession (const i2p::data::IdentityEx& from, uint16_t localPort, uint16_t remotePort);
 			uint32_t GetSessionIndex (uint16_t fromPort, uint16_t toPort) const { return ((uint32_t)fromPort << 16) + toPort; }
-
+			
 		private:
 
 			bool m_IsUniqueLocal;
@@ -165,7 +166,8 @@ namespace client
 			void HandleRecvFromI2PRaw (uint16_t fromPort, uint16_t toPort, const uint8_t * buf, size_t len);
 			void TryResolving ();
 			std::shared_ptr<i2p::datagram::DatagramSession> GetDatagramSession ();
-
+			void Acked (uint32_t seqn);
+			
 		private:
 
 			const std::string m_Name;
@@ -186,7 +188,9 @@ namespace client
 			std::shared_ptr<UDPConvo> m_LastSession;
 			std::weak_ptr<i2p::datagram::DatagramSession> m_LastDatagramSession;
 			uint32_t m_NextSendPacketNum, m_LastReceivedPacketNum;
-
+			std::list<std::pair<uint32_t, uint64_t> > m_UnackedDatagrams; // list of sent but not acked repliable datagrams(seqn, timestamp) in ascending order
+			uint64_t m_RTT; // milliseconds
+			
 		public:
 
 			bool isUpdated; // transient, used during reload only