change datagram routing path if nothing comes back in 10 seconds

libi2pd/Datagram.cpp

@@ -315,6 +315,13 @@ namespace datagram
 		}	
 		
 		auto path = m_RoutingSession->GetSharedRoutingPath();
+		if (path && m_RoutingSession->IsRatchets () &&
+		    m_LastUse > m_RoutingSession->GetLastActivityTimestamp ()*1000 + DATAGRAM_SESSION_PATH_TIMEOUT)
+		{	
+			m_RoutingSession->SetSharedRoutingPath (nullptr);
+			path = nullptr;
+		}
+				
 		if (path) 
 		{
 			if (path->outboundTunnel && !path->outboundTunnel->IsEstablished ())

libi2pd/ECIESX25519AEADRatchetSession.cpp

@@ -770,7 +770,7 @@ namespace garlic
 			if (m_NextSendRatchet->newKey) payloadLen += 32;
 		}
 		uint8_t paddingSize = 0;
-		if (payloadLen)
+		if (payloadLen || ts > m_LastSentTimestamp + ECIESX25519_SEND_INACTIVITY_TIMEOUT)
 		{
 			int delta = (int)ECIESX25519_OPTIMAL_PAYLOAD_SIZE - (int)payloadLen;
 			if (delta < 0 || delta > 3) // don't create padding if we are close to optimal size
@@ -791,6 +791,9 @@ namespace garlic
 			}
 		}
 		std::vector<uint8_t> v(payloadLen);
+		if (payloadLen)
+		{	
+			m_LastSentTimestamp = ts;
 			size_t offset = 0;
 			// DateTime
 			if (first)
@@ -868,6 +871,7 @@ namespace garlic
 				htobe16buf (v.data () + offset, paddingSize); offset += 2;
 				memset (v.data () + offset, 0, paddingSize); offset += paddingSize;
 			}
+		}	
 		return v;
 	}
 

libi2pd/ECIESX25519AEADRatchetSession.h

@@ -27,7 +27,8 @@ namespace garlic
 {
 	const int ECIESX25519_RESTART_TIMEOUT = 120; // number of second since session creation we can restart session after
 	const int ECIESX25519_EXPIRATION_TIMEOUT = 480; // in seconds
-	const int ECIESX25519_INACTIVITY_TIMEOUT = 90; // number of second we receive nothing and should restart if we can
+	const int ECIESX25519_INACTIVITY_TIMEOUT = 90; // number of seconds we receive nothing and should restart if we can
+	const int ECIESX25519_SEND_INACTIVITY_TIMEOUT = 5000; // number of milliseconds we can send empty(pyaload only) packet after 
 	const int ECIESX25519_INCOMING_TAGS_EXPIRATION_TIMEOUT = 600; // in seconds
 	const int ECIESX25519_PREVIOUS_TAGSET_EXPIRATION_TIMEOUT = 180; // 180
 	const int ECIESX25519_TAGSET_MAX_NUM_TAGS = 4096; // number of tags we request new tagset after
@@ -148,6 +149,7 @@ namespace garlic
 			bool IsInactive (uint64_t ts) const { return ts > m_LastActivityTimestamp + ECIESX25519_INACTIVITY_TIMEOUT && CanBeRestarted (ts); }
 			
 			bool IsRatchets () const { return true; };
+			uint64_t GetLastActivityTimestamp () const { return m_LastActivityTimestamp; };
 
 		private:
 
@@ -182,7 +184,8 @@ namespace garlic
 			uint8_t m_NSREncodedKey[32], m_NSRH[32], m_NSRKey[32]; // new session reply, for incoming only
 			std::shared_ptr<i2p::crypto::X25519Keys> m_EphemeralKeys;
 			SessionState m_State = eSessionStateNew;
-			uint64_t m_SessionCreatedTimestamp = 0,  m_LastActivityTimestamp = 0; // incoming
+			uint64_t m_SessionCreatedTimestamp = 0,  m_LastActivityTimestamp = 0, // incoming
+				m_LastSentTimestamp = 0; // in milliseconds
 			std::shared_ptr<RatchetTagSet> m_SendTagset, m_NSRSendTagset;
 			std::unique_ptr<i2p::data::IdentHash> m_Destination;// TODO: might not need it
 			std::list<std::pair<uint16_t, int> > m_AckRequests; // (tagsetid, index)

libi2pd/Garlic.h

@@ -114,6 +114,7 @@ namespace garlic
 			virtual bool CleanupUnconfirmedTags () { return false; }; // for I2CP, override in ElGamalAESSession
 			virtual bool MessageConfirmed (uint32_t msgID);
 			virtual bool IsRatchets () const { return false; };
+			virtual uint64_t GetLastActivityTimestamp () const { return 0; }; // non-zero for rathets only
 
 			void SetLeaseSetUpdated ()
 			{