acks and resends

Streaming.cpp

@@ -21,7 +21,7 @@ namespace stream
 		const i2p::data::LeaseSet& remote): m_Service (service), m_SendStreamID (0), 
 		m_SequenceNumber (0), m_LastReceivedSequenceNumber (-1), m_IsOpen (false),  
 		m_LeaseSetUpdated (true), m_LocalDestination (local), 
-		m_RemoteLeaseSet (&remote), m_ReceiveTimer (m_Service)
+		m_RemoteLeaseSet (&remote), m_ReceiveTimer (m_Service), m_ResendTimer (m_Service)
 	{
 		m_RecvStreamID = i2p::context.GetRandomNumberGenerator ().GenerateWord32 ();
 		UpdateCurrentRemoteLease ();
@@ -30,7 +30,7 @@ namespace stream
 	Stream::Stream (boost::asio::io_service& service, StreamingDestination * local):
 		m_Service (service), m_SendStreamID (0), m_SequenceNumber (0), m_LastReceivedSequenceNumber (-1), 
 		m_IsOpen (false), m_LeaseSetUpdated (true), m_LocalDestination (local),
-		m_RemoteLeaseSet (nullptr), m_ReceiveTimer (m_Service)
+		m_RemoteLeaseSet (nullptr), m_ReceiveTimer (m_Service), m_ResendTimer (m_Service)
 	{
 		m_RecvStreamID = i2p::context.GetRandomNumberGenerator ().GenerateWord32 ();
 	}
@@ -38,6 +38,7 @@ namespace stream
 	Stream::~Stream ()
 	{
 		m_ReceiveTimer.cancel ();
+		m_ResendTimer.cancel ();
 		while (!m_ReceiveQueue.empty ())
 		{
 			auto packet = m_ReceiveQueue.front ();
@@ -46,6 +47,8 @@ namespace stream
 		}		
 		for (auto it: m_SavedPackets)
 			delete it;
+		for (auto it: m_SentPackets)
+			delete it;
 	}	
 		
 	void Stream::HandleNextPacket (Packet * packet)
@@ -53,6 +56,9 @@ namespace stream
 		if (!m_SendStreamID) 
 			m_SendStreamID = packet->GetReceiveStreamID (); 	
 
+		if (!packet->IsNoAck ()) // ack received
+			ProcessAck (packet);
+		
 		int32_t receivedSeqn = packet->GetSeqn ();
 		bool isSyn = packet->IsSYN ();
 		if (!receivedSeqn && !isSyn)
@@ -172,9 +178,30 @@ namespace stream
 			m_ReceiveTimer.cancel ();
 		}
 	}	
+
+	void Stream::ProcessAck (Packet * packet)
+	{
+		uint32_t ackThrough = packet->GetAckThrough ();
+		// TODO: handle NACKs
+		for (auto it = m_SentPackets.begin (); it != m_SentPackets.end ();)
+		{			
+			if ((*it)->GetSeqn () <= ackThrough)
+			{
+				auto sentPacket = *it;
+				LogPrint ("Packet ", sentPacket->GetSeqn (), " acknowledged");
+				m_SentPackets.erase (it++);
+				delete sentPacket;	
+			}
+			else
+				break;
+		}
+		if (m_SentPackets.empty ())
+			m_ResendTimer.cancel ();
+	}		
 		
 	size_t Stream::Send (const uint8_t * buf, size_t len, int timeout)
 	{
+		bool isNoAck = m_LastReceivedSequenceNumber < 0; // first packet
 		Packet * p = new Packet ();
 		uint8_t * packet = p->GetBuffer ();
 		// TODO: implement setters
@@ -185,7 +212,10 @@ namespace stream
 		size += 4; // receiveStreamID
 		*(uint32_t *)(packet + size) = htobe32 (m_SequenceNumber++);
 		size += 4; // sequenceNum
-		*(uint32_t *)(packet + size) = 0; // TODO
+		if (isNoAck)			
+			*(uint32_t *)(packet + size) = htobe32 (m_LastReceivedSequenceNumber);
+		else
+			*(uint32_t *)(packet + size) = 0;
 		size += 4; // ack Through
 		packet[size] = 0; 
 		size++; // NACK count
@@ -194,9 +224,10 @@ namespace stream
 		{	
 			//  initial packet
 			m_IsOpen = true;
-			*(uint16_t *)(packet + size) = htobe16 (PACKET_FLAG_SYNCHRONIZE | 
-				PACKET_FLAG_FROM_INCLUDED | PACKET_FLAG_SIGNATURE_INCLUDED | 
-				PACKET_FLAG_MAX_PACKET_SIZE_INCLUDED | PACKET_FLAG_NO_ACK);
+			uint16_t flags = PACKET_FLAG_SYNCHRONIZE | PACKET_FLAG_FROM_INCLUDED | 
+				PACKET_FLAG_SIGNATURE_INCLUDED | PACKET_FLAG_MAX_PACKET_SIZE_INCLUDED;
+			if (isNoAck) flags |= PACKET_FLAG_NO_ACK;
+			*(uint16_t *)(packet + size) = htobe16 (flags);
 			size += 2; // flags
 			*(uint16_t *)(packet + size) = htobe16 (i2p::data::DEFAULT_IDENTITY_SIZE + 40 + 2); // identity + signature + packet size
 			size += 2; // options size
@@ -310,7 +341,15 @@ namespace stream
 		if (packet)
 		{	
 			bool ret = SendPacket (packet->GetBuffer (), packet->GetLength ());
-			delete packet;
+			if (ret)
+			{
+				bool isEmpty = m_SentPackets.empty ();
+				m_SentPackets.insert (packet);
+				if (isEmpty)
+					ScheduleResend ();
+			}	
+			else	
+				delete packet;
 			return ret;
 		}	
 		else
@@ -364,6 +403,24 @@ namespace stream
 		return false;
 	}
 
+	void Stream::ScheduleResend ()
+	{
+		m_ResendTimer.cancel ();
+		m_ResendTimer.expires_from_now (boost::posix_time::seconds(RESEND_TIMEOUT));
+		m_ResendTimer.async_wait (boost::bind (&Stream::HandleResendTimer,
+			this, boost::asio::placeholders::error));
+	}
+		
+	void Stream::HandleResendTimer (const boost::system::error_code& ecode)
+	{
+		if (ecode != boost::asio::error::operation_aborted)
+		{	
+			for (auto it : m_SentPackets)
+				SendPacket (it->GetBuffer (), it->GetLength ());
+			ScheduleResend ();
+		}	
+	}	
+		
 	void Stream::UpdateCurrentRemoteLease ()
 	{
 		if (!m_RemoteLeaseSet)

Streaming.h

@@ -36,6 +36,7 @@ namespace stream
 	const size_t STREAMING_MTU = 1730;
 	const size_t MAX_PACKET_SIZE = 4096;
 	const size_t COMPRESSION_THRESHOLD_SIZE = 66;	
+	const int RESEND_TIMEOUT = 10; // in seconds
 	
 	struct Packet
 	{
@@ -58,6 +59,7 @@ namespace stream
 		const uint8_t * GetPayload () const { return GetOptionData () + GetOptionSize (); };
 
 		bool IsSYN () const { return GetFlags () & PACKET_FLAG_SYNCHRONIZE; };
+		bool IsNoAck () const { return GetFlags () & PACKET_FLAG_NO_ACK; };
 	};	
 
 	struct PacketCmp
@@ -102,6 +104,7 @@ namespace stream
 
 			void SavePacket (Packet * packet);
 			void ProcessPacket (Packet * packet);
+			void ProcessAck (Packet * packet);
 			size_t ConcatenatePackets (uint8_t * buf, size_t len);
 
 			void UpdateCurrentRemoteLease ();
@@ -109,6 +112,9 @@ namespace stream
 			template<typename Buffer, typename ReceiveHandler>
 			void HandleReceiveTimer (const boost::system::error_code& ecode, const Buffer& buffer, ReceiveHandler handler);
 
+			void ScheduleResend ();
+			void HandleResendTimer (const boost::system::error_code& ecode);
+			
 		private:
 
 			boost::asio::io_service& m_Service;
@@ -121,7 +127,8 @@ namespace stream
 			i2p::data::Lease m_CurrentRemoteLease;
 			std::queue<Packet *> m_ReceiveQueue;
 			std::set<Packet *, PacketCmp> m_SavedPackets;
-			boost::asio::deadline_timer m_ReceiveTimer;
+			std::set<Packet *, PacketCmp> m_SentPackets;
+			boost::asio::deadline_timer m_ReceiveTimer, m_ResendTimer;
 	};
 	
 	class StreamingDestination: public i2p::data::LocalDestination