adjust time offset after second time discrepancy

libi2pd/SSU2.cpp

@@ -24,7 +24,8 @@ namespace transport
 		m_AddressV4 (boost::asio::ip::address_v4()), m_AddressV6 (boost::asio::ip::address_v6()),
 		m_TerminationTimer (GetService ()), m_CleanupTimer (GetService ()), m_ResendTimer (GetService ()),
 		m_IntroducersUpdateTimer (GetService ()), m_IntroducersUpdateTimerV6 (GetService ()),
-		m_IsPublished (true), m_IsSyncClockFromPeers (true), m_IsThroughProxy (false)
+		m_IsPublished (true), m_IsSyncClockFromPeers (true), m_PendingTimeOffset (0),
+		m_IsThroughProxy (false)
 	{
 	}
 
@@ -209,6 +210,24 @@ namespace transport
 		return ep.port ();
 	}
 
+	void SSU2Server::AdjustTimeOffset (int64_t offset)
+	{
+		if (offset)
+		{	
+			if (m_PendingTimeOffset) // one more
+			{	
+				offset = (m_PendingTimeOffset + offset)/2; // average
+				LogPrint (eLogWarning, "SSU2: Clock adjusted by ", -offset, " seconds");
+				i2p::util::AdjustTimeOffset (-offset);
+				m_PendingTimeOffset = 0;
+			}
+			else
+				m_PendingTimeOffset = offset; // first 
+		}	
+		else
+			m_PendingTimeOffset = 0; // reset
+	}	
+		
 	boost::asio::ip::udp::socket& SSU2Server::OpenSocket (const boost::asio::ip::udp::endpoint& localEndpoint)
 	{
 		boost::asio::ip::udp::socket& socket = localEndpoint.address ().is_v6 () ? m_SocketV6 : m_SocketV4;

libi2pd/SSU2.h

@@ -66,6 +66,7 @@ namespace transport
 			bool IsSupported (const boost::asio::ip::address& addr) const;
 			uint16_t GetPort (bool v4) const;
 			bool IsSyncClockFromPeers () const { return m_IsSyncClockFromPeers; };
+			void AdjustTimeOffset (int64_t offset);
 
 			void AddSession (std::shared_ptr<SSU2Session> session);
 			void RemoveSession (uint64_t connID);
@@ -161,6 +162,7 @@ namespace transport
 			std::shared_ptr<SSU2Session> m_LastSession;
 			bool m_IsPublished; // if we maintain introducers
 			bool m_IsSyncClockFromPeers;
+			int64_t m_PendingTimeOffset; // during peer test
 
 			// proxy
 			bool m_IsThroughProxy;

libi2pd/SSU2Session.cpp

@@ -1668,10 +1668,7 @@ namespace transport
 					if (m_Server.IsSyncClockFromPeers ())
 					{
 						if (std::abs (offset) > SSU2_CLOCK_THRESHOLD)
-						{
-							LogPrint (eLogWarning, "SSU2: Clock adjusted by ", -offset, " seconds");
-							i2p::util::AdjustTimeOffset (-offset);
-						}
+							m_Server.AdjustTimeOffset (-offset);
 					}
 					else if (std::abs (offset) > SSU2_CLOCK_SKEW)
 					{
@@ -2481,6 +2478,8 @@ namespace transport
 			else if (m_Address->IsV6 ())
 				i2p::context.SetTestingV6 (testing);
 		}
+		if (!testing)
+			m_Server.AdjustTimeOffset (0); // reset time offset when testing is over
 	}
 
 	size_t SSU2Session::CreateAddressBlock (uint8_t * buf, size_t len, const boost::asio::ip::udp::endpoint& ep)