From 2fef595b83a4fdee89a02c35ed4bf1e235b66bb3 Mon Sep 17 00:00:00 2001
From: orignal <i2porignal@yandex.ru>
Date: Thu, 31 Mar 2022 15:35:55 -0400
Subject: [PATCH] resend packets

---
 libi2pd/SSU2.cpp | 65 +++++++++++++++++++++++++++++++++++++-----------
 libi2pd/SSU2.h   |  6 ++++-
 2 files changed, 55 insertions(+), 16 deletions(-)

diff --git a/libi2pd/SSU2.cpp b/libi2pd/SSU2.cpp
index 54783f9b..67cf9658 100644
--- a/libi2pd/SSU2.cpp
+++ b/libi2pd/SSU2.cpp
@@ -104,8 +104,8 @@ namespace transport
 		for (auto it: msgs)
 			m_SendQueue.push_back (it);
 		SendQueue ();
-	}
-
+	}	
+		
 	void SSU2Session::SendQueue ()
 	{	
 		if (!m_SendQueue.empty ())
@@ -146,6 +146,28 @@ namespace transport
 			}	
 		}	
 	}	
+
+	void SSU2Session::Resend (uint64_t ts)
+	{
+		if (m_SendQueue.empty ()) return;
+		for (auto it = m_SentPackets.begin (); it != m_SentPackets.end (); )
+			if (ts > it->second->nextResendTime)
+			{
+				if (it->second->numResends > SSU2_MAX_NUM_RESENDS)
+					it = m_SentPackets.erase (it);
+				else
+				{
+					m_Server.Send (it->second->header.buf, 16, it->second->payload, it->second->payloadLen, m_RemoteEndpoint);
+					it->second->numResends++;
+					it->second->nextResendTime = ts + it->second->numResends*SSU2_RESEND_INTERVAL;		
+					m_LastActivityTimestamp = ts;
+					m_NumSentBytes += it->second->payloadLen + 16;
+					it++;	
+				}		
+			}
+			else
+				it++;
+	}	
 		
 	void SSU2Session::ProcessFirstIncomingMessage (uint64_t connID, uint8_t * buf, size_t len)
 	{
@@ -765,19 +787,14 @@ namespace transport
 	{
 		if (m_SentPackets.empty ()) return;
 		uint32_t ackThrough = bufbe32toh (buf);
-		auto it = m_SentPackets.rbegin ();
-		while (it != m_SentPackets.rend () && it->first > ackThrough) ++it; // find first less pack <= ackThrough
-		if (it == m_SentPackets.rend ()) return;
-		int32_t firstPacketNum = ackThrough - buf[4]; // acnt
-		if (firstPacketNum < 0) firstPacketNum = 0;
+		uint32_t firstPacketNum = ackThrough > buf[4] ? ackThrough - buf[4] : 0; // acnt
+		auto it = m_SentPackets.begin ();
+		while (it != m_SentPackets.end () && it->first < firstPacketNum) it++; // find first acked packet
+		if (it == m_SentPackets.end ()) return; // not found
 		auto it1 = it;
-		while (it1 != m_SentPackets.rend () && it1->first >= (uint32_t)firstPacketNum) it1++;
-		if (it1 == m_SentPackets.rend ())
-		{
-			m_SentPackets.erase (m_SentPackets.begin (), it.base ());
-			return;
-		}	
-		m_SentPackets.erase (it1.base (), it.base ());
+		while (it1 != m_SentPackets.end () && it1->first <= ackThrough) it1++;
+		it1--;
+		m_SentPackets.erase (it, it1);
 		// TODO: handle ranges
 	}
 		
@@ -944,7 +961,7 @@ namespace transport
 		
 	SSU2Server::SSU2Server ():
 		RunnableServiceWithWork ("SSU2"), m_Socket (GetService ()), m_SocketV6 (GetService ()),
-		m_TerminationTimer (GetService ())
+		m_TerminationTimer (GetService ()), m_ResendTimer (GetService ())
 	{
 	}
 
@@ -1200,6 +1217,24 @@ namespace transport
 		}
 	}
 
+	void SSU2Server::ScheduleResend ()
+	{
+		m_ResendTimer.expires_from_now (boost::posix_time::seconds(SSU2_RESEND_INTERVAL));
+		m_ResendTimer.async_wait (std::bind (&SSU2Server::HandleResendTimer,
+			this, std::placeholders::_1));
+	}
+		
+	void SSU2Server::HandleResendTimer (const boost::system::error_code& ecode)
+	{
+		if (ecode != boost::asio::error::operation_aborted)
+		{
+			auto ts = i2p::util::GetSecondsSinceEpoch ();
+			for (auto it: m_Sessions)
+				it.second->Resend (ts);
+			ScheduleResend ();
+		}	
+	}	
+		
 	void SSU2Server::UpdateOutgoingToken (const boost::asio::ip::udp::endpoint& ep, uint64_t token, uint32_t exp)
 	{
 		m_OutgoingTokens[ep] = {token, exp};
diff --git a/libi2pd/SSU2.h b/libi2pd/SSU2.h
index 8b04bbc4..f50aa7b4 100644
--- a/libi2pd/SSU2.h
+++ b/libi2pd/SSU2.h
@@ -122,6 +122,7 @@ namespace transport
 			void TerminateByTimeout ();
 			void Done () override;
 			void SendI2NPMessages (const std::vector<std::shared_ptr<I2NPMessage> >& msgs) override;
+			void Resend (uint64_t ts);
 			bool IsEstablished () const { return m_State == eSSU2SessionStateEstablished; };
 			uint64_t GetConnID () const { return m_SourceConnID; };
 			
@@ -223,6 +224,9 @@ namespace transport
 
 			void ScheduleTermination ();
 			void HandleTerminationTimer (const boost::system::error_code& ecode);
+
+			void ScheduleResend ();
+			void HandleResendTimer (const boost::system::error_code& ecode);
 			
 		private:
 
@@ -231,7 +235,7 @@ namespace transport
 			std::map<boost::asio::ip::udp::endpoint, std::shared_ptr<SSU2Session> > m_PendingOutgoingSessions;
 			std::map<boost::asio::ip::udp::endpoint, std::pair<uint64_t, uint32_t> > m_IncomingTokens, m_OutgoingTokens; // remote endpoint -> (token, expires in seconds)
 			i2p::util::MemoryPoolMt<Packet> m_PacketsPool;
-			boost::asio::deadline_timer m_TerminationTimer;
+			boost::asio::deadline_timer m_TerminationTimer, m_ResendTimer;
 
 		public: