use std::mt19937 instead rand(). termination timeout variance

libi2pd/NTCP2.cpp

@@ -108,10 +108,10 @@ namespace transport
 		m_EphemeralKeys = i2p::transport::transports.GetNextX25519KeysPair ();
 	}
 
-	void NTCP2Establisher::CreateSessionRequestMessage ()
+	void NTCP2Establisher::CreateSessionRequestMessage (std::mt19937& rng)
 	{
 		// create buffer and fill padding
-		auto paddingLength = rand () % (NTCP2_SESSION_REQUEST_MAX_SIZE - 64); // message length doesn't exceed 287 bytes
+		auto paddingLength = rng () % (NTCP2_SESSION_REQUEST_MAX_SIZE - 64); // message length doesn't exceed 287 bytes
 		m_SessionRequestBufferLen = paddingLength + 64;
 		RAND_bytes (m_SessionRequestBuffer + 64, paddingLength);
 		// encrypt X
@@ -149,9 +149,9 @@ namespace transport
 		i2p::crypto::AEADChaCha20Poly1305 (options, 16, GetH (), 32, GetK (), nonce, m_SessionRequestBuffer + 32, 32, true); // encrypt
 	}
 
-	void NTCP2Establisher::CreateSessionCreatedMessage ()
+	void NTCP2Establisher::CreateSessionCreatedMessage (std::mt19937& rng)
 	{
-		auto paddingLen = rand () % (NTCP2_SESSION_CREATED_MAX_SIZE - 64);
+		auto paddingLen = rng () % (NTCP2_SESSION_CREATED_MAX_SIZE - 64);
 		m_SessionCreatedBufferLen = paddingLen + 64;
 		RAND_bytes (m_SessionCreatedBuffer + 64, paddingLen);
 		// encrypt Y
@@ -349,7 +349,7 @@ namespace transport
 				LogPrint (eLogWarning, "NTCP2: Missing NTCP2 address");
 		}
 		m_NextRouterInfoResendTime = i2p::util::GetSecondsSinceEpoch () + NTCP2_ROUTERINFO_RESEND_INTERVAL +
-			rand ()%NTCP2_ROUTERINFO_RESEND_INTERVAL_THRESHOLD;
+			m_Server.GetRng ()() % NTCP2_ROUTERINFO_RESEND_INTERVAL_THRESHOLD;
 	}
 
 	NTCP2Session::~NTCP2Session ()
@@ -411,7 +411,7 @@ namespace transport
 	{
 		m_IsEstablished = true;
 		m_Establisher.reset (nullptr);
-		SetTerminationTimeout (NTCP2_TERMINATION_TIMEOUT);
+		SetTerminationTimeout (NTCP2_TERMINATION_TIMEOUT + m_Server.GetRng ()() % NTCP2_TERMINATION_TIMEOUT_VARIANCE);
 		SendQueue ();
 		transports.PeerConnected (shared_from_this ());
 	}
@@ -464,7 +464,7 @@ namespace transport
 
 	void NTCP2Session::SendSessionRequest ()
 	{
-		m_Establisher->CreateSessionRequestMessage ();
+		m_Establisher->CreateSessionRequestMessage (m_Server.GetRng ());
 		// send message
 		m_HandshakeInterval = i2p::util::GetMillisecondsSinceEpoch ();
 		boost::asio::async_write (m_Socket, boost::asio::buffer (m_Establisher->m_SessionRequestBuffer, m_Establisher->m_SessionRequestBufferLen), boost::asio::transfer_all (),
@@ -542,7 +542,7 @@ namespace transport
 
 	void NTCP2Session::SendSessionCreated ()
 	{
-		m_Establisher->CreateSessionCreatedMessage ();
+		m_Establisher->CreateSessionCreatedMessage (m_Server.GetRng ());
 		// send message
 		m_HandshakeInterval = i2p::util::GetMillisecondsSinceEpoch ();
 		boost::asio::async_write (m_Socket, boost::asio::buffer (m_Establisher->m_SessionCreatedBuffer, m_Establisher->m_SessionCreatedBufferLen), boost::asio::transfer_all (),
@@ -1121,7 +1121,7 @@ namespace transport
 			if (GetLastActivityTimestamp () > m_NextRouterInfoResendTime)
 			{
 				m_NextRouterInfoResendTime += NTCP2_ROUTERINFO_RESEND_INTERVAL +
-					rand ()%NTCP2_ROUTERINFO_RESEND_INTERVAL_THRESHOLD;
+					m_Server.GetRng ()() % NTCP2_ROUTERINFO_RESEND_INTERVAL_THRESHOLD;
 				SendRouterInfo ();
 			}
 			else
@@ -1298,7 +1298,8 @@ namespace transport
 
 	NTCP2Server::NTCP2Server ():
 		RunnableServiceWithWork ("NTCP2"), m_TerminationTimer (GetService ()),
-			m_ProxyType(eNoProxy), m_Resolver(GetService ())
+		m_ProxyType(eNoProxy), m_Resolver(GetService ()),
+		m_Rng(i2p::util::GetMonotonicMicroseconds ()%1000000LL)
 	{
 	}
 

libi2pd/NTCP2.h

@@ -14,6 +14,7 @@
 #include <list>
 #include <map>
 #include <array>
+#include <random>
 #include <openssl/bn.h>
 #include <openssl/evp.h>
 #include <boost/asio.hpp>
@@ -35,7 +36,8 @@ namespace transport
 
 	const int NTCP2_CONNECT_TIMEOUT = 5; // 5 seconds
 	const int NTCP2_ESTABLISH_TIMEOUT = 10; // 10 seconds
-	const int NTCP2_TERMINATION_TIMEOUT = 120; // 2 minutes
+	const int NTCP2_TERMINATION_TIMEOUT = 115; // 2 minutes - 5 seconds
+	const int NTCP2_TERMINATION_TIMEOUT_VARIANCE = 10; // 10 seconds
 	const int NTCP2_TERMINATION_CHECK_TIMEOUT = 30; // 30 seconds
 	const int NTCP2_RECEIVE_BUFFER_DELETION_TIMEOUT = 3; // 3 seconds
 	const int NTCP2_ROUTERINFO_RESEND_INTERVAL = 25*60; // 25 minuntes in seconds
@@ -103,8 +105,8 @@ namespace transport
 		void KeyDerivationFunction2 (const uint8_t * sessionRequest, size_t sessionRequestLen, const uint8_t * epub); // for SessionCreate
 		void CreateEphemeralKey ();
 
-		void CreateSessionRequestMessage ();
-		void CreateSessionCreatedMessage ();
+		void CreateSessionRequestMessage (std::mt19937& rng);
+		void CreateSessionCreatedMessage (std::mt19937& rng);
 		void CreateSessionConfirmedMessagePart1 (const uint8_t * nonce);
 		void CreateSessionConfirmedMessagePart2 (const uint8_t * nonce);
 
@@ -248,6 +250,7 @@ namespace transport
 			void Start ();
 			void Stop ();
 			boost::asio::io_service& GetService () { return GetIOService (); };
+			std::mt19937& GetRng () { return m_Rng; };
 
 			bool AddNTCP2Session (std::shared_ptr<NTCP2Session> session, bool incoming = false);
 			void RemoveNTCP2Session (std::shared_ptr<NTCP2Session> session);
@@ -286,6 +289,7 @@ namespace transport
 			boost::asio::ip::tcp::resolver m_Resolver;
 			std::unique_ptr<boost::asio::ip::tcp::endpoint> m_ProxyEndpoint;
 			std::shared_ptr<boost::asio::ip::tcp::endpoint> m_Address4, m_Address6, m_YggdrasilAddress;
+			std::mt19937 m_Rng;
 
 		public: