recreate session tags

Garlic.cpp

@@ -23,8 +23,7 @@ namespace garlic
 		if (m_NumTags > 0)
 		{
 			m_SessionTags = new uint8_t[m_NumTags*32];
-			for (int i = 0; i < m_NumTags; i++)
-				m_Rnd.GenerateBlock (m_SessionTags + i*32, 32);
+			GenerateSessionTags ();
 		}	
 		else
 			m_SessionTags = nullptr;
@@ -34,18 +33,22 @@ namespace garlic
 	{	
 		delete[] m_SessionTags;
 	}
-		
-	I2NPMessage * GarlicRoutingSession::WrapSingleMessage (I2NPMessage * msg, I2NPMessage * leaseSet)
+	
+	void GarlicRoutingSession::GenerateSessionTags ()
 	{
-		if (GetNumRemainingSessionTags () < 1)
+		if (m_SessionTags)
 		{
-			LogPrint ("No more session tags");
-			return nullptr;
-		}	
+			for (int i = 0; i < m_NumTags; i++)
+				m_Rnd.GenerateBlock (m_SessionTags + i*32, 32);
+		}
+	}
+	
+	I2NPMessage * GarlicRoutingSession::WrapSingleMessage (I2NPMessage * msg, I2NPMessage * leaseSet)
+	{
 		I2NPMessage * m = NewI2NPMessage ();
 		size_t len = 0;
 		uint8_t * buf = m->GetPayload () + 4; // 4 bytes for length
-		if (m_NextTag < 0) // new session
+		if (m_NextTag < 0 || !m_NumTags) // new session
 		{
 			// create ElGamal block
 			ElGamalBlock elGamal;
@@ -53,23 +56,30 @@ namespace garlic
 			m_Rnd.GenerateBlock (elGamal.preIV, 32); // Pre-IV
 			uint8_t iv[32]; // IV is first 16 bytes
 			CryptoPP::SHA256().CalculateDigest(iv, elGamal.preIV, 32); 
-			i2p::crypto::ElGamalEncrypt (m_Destination->GetEncryptionPublicKey (), (uint8_t *)&elGamal, sizeof(elGamal), buf, true);
-			buf += 514;
-			// AES block
+			i2p::crypto::ElGamalEncrypt (m_Destination->GetEncryptionPublicKey (), (uint8_t *)&elGamal, sizeof(elGamal), buf, true);			
 			m_Encryption.SetKeyWithIV (m_SessionKey, 32, iv);
-			len += 514 + CreateAESBlock (buf, msg, leaseSet, true);	
+			buf += 514;
+			len += 514;	
 		}
 		else // existing session
 		{	
 			// session tag
-			memcpy (buf, m_SessionTags + m_NextTag*32, 32);
-			buf += 32;
+			memcpy (buf, m_SessionTags + m_NextTag*32, 32);			
 			uint8_t iv[32]; // IV is first 16 bytes
 			CryptoPP::SHA256().CalculateDigest(iv, m_SessionTags + m_NextTag*32, 32);
 			m_Encryption.SetKeyWithIV (m_SessionKey, 32, iv);
-			// AES block
-			len += 32 + CreateAESBlock (buf, msg, leaseSet, false);
+			buf += 32;
+			len += 32;
+
+			// re-create session tags if necessary				
+			if (m_NextTag >= m_NumTags - 1) // we have used last tag
+			{
+				GenerateSessionTags ();
+				m_NextTag = -1;
+			}			
 		}	
+		// AES block
+		len += CreateAESBlock (buf, msg, leaseSet);
 		m_NextTag++;
 		*(uint32_t *)(m->GetPayload ()) = htobe32 (len);
 		m->len += len + 4;
@@ -79,12 +89,12 @@ namespace garlic
 		return m;
 	}	
 
-	size_t GarlicRoutingSession::CreateAESBlock (uint8_t * buf, I2NPMessage * msg, I2NPMessage * leaseSet, bool isNewSession)
+	size_t GarlicRoutingSession::CreateAESBlock (uint8_t * buf, I2NPMessage * msg, I2NPMessage * leaseSet)
 	{
 		size_t blockSize = 0;
-		*(uint16_t *)buf = isNewSession ? htobe16 (m_NumTags) : 0; // tag count
+		*(uint16_t *)buf = m_NextTag < 0 ? htobe16 (m_NumTags) : 0; // tag count
 		blockSize += 2;
-		if (isNewSession)
+		if (m_NextTag < 0) // session tags recreated
 		{	
 			memcpy (buf + blockSize, m_SessionTags, m_NumTags*32); // tags
 			blockSize += m_NumTags*32;
@@ -95,7 +105,7 @@ namespace garlic
 		blockSize += 32;
 		buf[blockSize] = 0; // flag
 		blockSize++;
-		size_t len = CreateGarlicPayload (buf + blockSize, msg, leaseSet, isNewSession);
+		size_t len = CreateGarlicPayload (buf + blockSize, msg, leaseSet);
 		*payloadSize = htobe32 (len);
 		CryptoPP::SHA256().CalculateDigest(payloadHash, buf + blockSize, len);
 		blockSize += len;
@@ -106,7 +116,7 @@ namespace garlic
 		return blockSize;
 	}	
 
-	size_t GarlicRoutingSession::CreateGarlicPayload (uint8_t * payload, I2NPMessage * msg, I2NPMessage * leaseSet, bool isNewSession)
+	size_t GarlicRoutingSession::CreateGarlicPayload (uint8_t * payload, I2NPMessage * msg, I2NPMessage * leaseSet)
 	{
 		uint64_t ts = i2p::util::GetMillisecondsSinceEpoch () + 5000; // 5 sec
 		uint32_t msgID = m_Rnd.GenerateWord32 ();	
@@ -115,7 +125,7 @@ namespace garlic
 		*numCloves = 0;
 		size++;
 
-		if (isNewSession)
+		if (m_NextTag < 0) // new session
 		{
 			// clove is DeliveryStatus 
 			size += CreateDeliveryStatusClove (payload + size, msgID);
@@ -220,7 +230,22 @@ namespace garlic
 		m_Sessions.clear ();
 	}	
 
-	I2NPMessage * GarlicRouting::WrapSingleMessage (const i2p::data::RoutingDestination * destination, 
+	I2NPMessage * GarlicRouting::WrapSingleMessage (const i2p::data::RoutingDestination * destination, I2NPMessage * msg)
+	{
+		if (!destination) return nullptr;
+		auto it = m_Sessions.find (destination->GetIdentHash ());
+		if (it != m_Sessions.end ())
+		{
+			m_Sessions.erase (it);
+			delete it->second;
+		}
+		GarlicRoutingSession * session = new GarlicRoutingSession (destination, 0); // not follow-on messages expected
+		m_Sessions[destination->GetIdentHash ()] = session;
+
+		return session->WrapSingleMessage (msg, nullptr);
+	}	
+
+	I2NPMessage * GarlicRouting::WrapMessage (const i2p::data::RoutingDestination * destination, 
 		I2NPMessage * msg, I2NPMessage * leaseSet)
 	{
 		if (!destination) return nullptr;
@@ -228,27 +253,17 @@ namespace garlic
 		GarlicRoutingSession * session = nullptr;
 		if (it != m_Sessions.end ())
 			session = it->second;
-		if (session && (/*!session->IsAcknowledged () ||*/ session->GetNumRemainingSessionTags () < 1))
-		{
-			// we have to create new session
-			m_Sessions.erase (it);
-			m_CreatedSessions.erase (session->GetFirstMsgID ());
-			delete session;
-			session = nullptr;
-		}	
-		bool isNewSession = false;
 		if (!session)
 		{
-			session = new GarlicRoutingSession (destination, 16); // TODO: change it later
+			session = new GarlicRoutingSession (destination, 4); // TODO: change it later
 			m_Sessions[destination->GetIdentHash ()] = session;
-			isNewSession = true;
 		}	
 
 		I2NPMessage * ret = session->WrapSingleMessage (msg, leaseSet);
-		if (isNewSession)
+		if (!session->GetNextTag ()) // tags have beed recreated
 			m_CreatedSessions[session->GetFirstMsgID ()] = session;
 		return ret;
-	}	
+	}
 
 	void GarlicRouting::HandleGarlicMessage (uint8_t * buf, size_t len, bool isFromTunnel)
 	{
@@ -271,14 +286,18 @@ namespace garlic
 		{
 			// new session
 			ElGamalBlock elGamal;
-			i2p::crypto::ElGamalDecrypt (
+			if (i2p::crypto::ElGamalDecrypt (
 			   	isFromTunnel ? i2p::context.GetLeaseSetPrivateKey () : i2p::context.GetPrivateKey (), 
-				buf, (uint8_t *)&elGamal, true);
-			uint8_t iv[32]; // IV is first 16 bytes
-			CryptoPP::SHA256().CalculateDigest(iv, elGamal.preIV, 32); 
-			m_Decryption.SetKeyWithIV (elGamal.sessionKey, 32, iv);
-			m_Decryption.ProcessData(buf + 514, buf + 514, length - 514);
-			HandleAESBlock (buf + 514, length - 514, elGamal.sessionKey);
+				buf, (uint8_t *)&elGamal, true))
+			{	
+				uint8_t iv[32]; // IV is first 16 bytes
+				CryptoPP::SHA256().CalculateDigest(iv, elGamal.preIV, 32); 
+				m_Decryption.SetKeyWithIV (elGamal.sessionKey, 32, iv);
+				m_Decryption.ProcessData(buf + 514, buf + 514, length - 514);
+				HandleAESBlock (buf + 514, length - 514, elGamal.sessionKey);
+			}	
+			else
+				LogPrint ("Failed to decrypt garlic");
 		}	
 		
 	}	

Garlic.h

@@ -40,7 +40,7 @@ namespace garlic
 			GarlicRoutingSession (const i2p::data::RoutingDestination * destination, int numTags);
 			~GarlicRoutingSession ();
 			I2NPMessage * WrapSingleMessage (I2NPMessage * msg, I2NPMessage * leaseSet);
-			int GetNumRemainingSessionTags () const { return m_NumTags - m_NextTag; };
+			int GetNextTag () const { return m_NextTag; };
 			uint32_t GetFirstMsgID () const { return m_FirstMsgID; };
 
 			bool IsAcknowledged () const { return m_IsAcknowledged; };
@@ -48,11 +48,13 @@ namespace garlic
 			
 		private:
 
-			size_t CreateAESBlock (uint8_t * buf, I2NPMessage * msg, I2NPMessage * leaseSet, bool isNewSession);
-			size_t CreateGarlicPayload (uint8_t * payload, I2NPMessage * msg, I2NPMessage * leaseSet, bool isNewSession);
+			size_t CreateAESBlock (uint8_t * buf, I2NPMessage * msg, I2NPMessage * leaseSet);
+			size_t CreateGarlicPayload (uint8_t * payload, I2NPMessage * msg, I2NPMessage * leaseSet);
 			size_t CreateGarlicClove (uint8_t * buf, I2NPMessage * msg, bool isDestination);
 			size_t CreateDeliveryStatusClove (uint8_t * buf, uint32_t msgID);
 			
+			void GenerateSessionTags ();
+
 		private:
 
 			const i2p::data::RoutingDestination * m_Destination;
@@ -76,8 +78,9 @@ namespace garlic
 			void HandleGarlicMessage (uint8_t * buf, size_t len, bool isFromTunnel);
 			void HandleDeliveryStatusMessage (uint8_t * buf, size_t len);
 			
-			I2NPMessage * WrapSingleMessage (const i2p::data::RoutingDestination * destination, 
-				I2NPMessage * msg, I2NPMessage * leaseSet = nullptr);
+			I2NPMessage * WrapSingleMessage (const i2p::data::RoutingDestination * destination, I2NPMessage * msg);
+			I2NPMessage * WrapMessage (const i2p::data::RoutingDestination * destination, 
+			    I2NPMessage * msg, I2NPMessage * leaseSet = nullptr);
 
 		private:
 

Streaming.cpp

@@ -132,7 +132,7 @@ namespace stream
 		memcpy (packet + size, buf, len); 
 		size += len; // payload
 		m_LocalDestination->Sign (packet, size, signature);
-		I2NPMessage * msg = i2p::garlic::routing.WrapSingleMessage (m_RemoteLeaseSet, 
+		I2NPMessage * msg = i2p::garlic::routing.WrapMessage (m_RemoteLeaseSet, 
 			CreateDataMessage (this, packet, size), m_LocalDestination->GetLeaseSet ()); 
 
 		if (!m_OutboundTunnel)
@@ -166,7 +166,7 @@ namespace stream
 		*(uint16_t *)(packet + size) = 0; // no options
 		size += 2; // options size
 
-		I2NPMessage * msg = i2p::garlic::routing.WrapSingleMessage (m_RemoteLeaseSet, 
+		I2NPMessage * msg = i2p::garlic::routing.WrapMessage (m_RemoteLeaseSet, 
 			CreateDataMessage (this, packet, size));
 		if (m_OutboundTunnel)
 		{