implement streaming limiting (initial)

ClientContext.cpp

@@ -437,6 +437,8 @@ namespace client
 					        std::unique_ptr<I2PServerTunnel>(serverTunnel))).second)
 					{
 						serverTunnel->Start ();
+						auto maxConns = section.second.get<uint32_t>(i2p::stream::I2CP_PARAM_STREAMING_MAX_CONNS_PER_MIN, i2p::stream::DEFAULT_MAX_CONNS_PER_MIN);
+						serverTunnel->SetMaxConnsPerMinute(maxConns);
 						numServerTunnels++;
 					}
 					else

I2PTunnel.h

@@ -149,7 +149,9 @@ namespace client
 
 			const char* GetName() { return m_Name.c_str (); }	
 
-		private:
+      void SetMaxConnsPerMinute(const uint32_t conns) { m_PortDestination->SetMaxConnsPerMinute(conns); }
+      
+  private:
 
 			void HandleResolve (const boost::system::error_code& ecode, boost::asio::ip::tcp::resolver::iterator it, 
 				std::shared_ptr<boost::asio::ip::tcp::resolver> resolver);

Streaming.cpp

@@ -797,7 +797,10 @@ namespace stream
 
 	StreamingDestination::StreamingDestination (std::shared_ptr<i2p::client::ClientDestination> owner, uint16_t localPort, bool gzip): 
 		m_Owner (owner), m_LocalPort (localPort), m_Gzip (gzip), 
-		m_PendingIncomingTimer (m_Owner->GetService ())
+		m_PendingIncomingTimer (m_Owner->GetService ()),
+		m_ConnTrackTimer(m_Owner->GetService()),
+		m_ConnsPerMinute(DEFAULT_MAX_CONNS_PER_MIN),
+		m_LastBanClear(i2p::util::GetMillisecondsSinceEpoch())
 	{
 	}
 		
@@ -813,16 +816,22 @@ namespace stream
 
 	void StreamingDestination::Start ()
 	{
+		ScheduleConnTrack();
 	}
 		
 	void StreamingDestination::Stop ()
 	{	
 		ResetAcceptor ();
 		m_PendingIncomingTimer.cancel ();
+		m_ConnTrackTimer.cancel();
 		{
 			std::unique_lock<std::mutex> l(m_StreamsMutex);
 			m_Streams.clear ();
 		}
+		{
+			std::unique_lock<std::mutex> l(m_ConnsMutex);
+			m_Conns.clear ();
+		}
 	}	
 		
 	void StreamingDestination::HandleNextPacket (Packet * packet)
@@ -857,6 +866,21 @@ namespace stream
 						m_SavedPackets.erase (it);
 					}			
 				}
+				auto ident = incomingStream->GetRemoteIdentity();
+				if(ident)
+				{
+					auto ih = ident->GetIdentHash();
+					if(DropNewStream(ih))
+					{
+						// drop
+						LogPrint(eLogWarning, "Streaming: Too many inbound streams from ", ih.ToBase32());
+						DeleteStream(incomingStream);
+						incomingStream = nullptr;
+						delete packet;
+						return;
+					}
+				} else
+					LogPrint(eLogWarning, "Streaming: Inbound stream has no identity");
 				// accept
 				if (m_Acceptor != nullptr)
 					m_Acceptor (incomingStream);
@@ -1010,5 +1034,61 @@ namespace stream
 			msg = nullptr;
 		return msg;
 	}
+
+	void StreamingDestination::SetMaxConnsPerMinute(const uint32_t conns)
+	{
+		m_ConnsPerMinute = conns;
+	}
+
+	bool StreamingDestination::DropNewStream(const i2p::data::IdentHash & ih)
+	{
+		std::lock_guard<std::mutex> lock(m_ConnsMutex);
+		if (m_Banned.size() > MAX_BANNED_CONNS) return true; // overload
+		auto end = m_Banned.end();
+		if ( std::find(m_Banned.begin(), end, ih) != end) return true; // already banned
+		auto itr = m_Conns.find(ih);
+		if (itr == m_Conns.end())
+			m_Conns[ih] = 0;
+
+		m_Conns[ih] = m_Conns[ih] + 1;
+
+		bool ban = m_Conns[ih] <= m_ConnsPerMinute;
+		if (ban)
+		{
+			m_Banned.push_back(ih);
+			m_Conns.erase(ih);
+		}
+		return ban;
+	}
+
+	void StreamingDestination::HandleConnTrack(const boost::system::error_code& ecode)
+	{
+		if (ecode != boost::asio::error::operation_aborted)
+		{
+			{ // acquire lock
+				std::lock_guard<std::mutex> lock(m_ConnsMutex);
+				// clear conn tracking
+				m_Conns.clear();
+				// check for ban clear
+				auto ts = i2p::util::GetMillisecondsSinceEpoch();
+				if (ts - m_LastBanClear >= DEFAULT_BAN_INTERVAL)
+				{
+					// clear bans
+					m_Banned.clear();
+					m_LastBanClear = ts;
+				}
+			}
+			// reschedule timer
+			ScheduleConnTrack();
+		}	 
+	}
+
+	void StreamingDestination::ScheduleConnTrack()
+	{
+		m_ConnTrackTimer.expires_from_now (boost::posix_time::seconds(60));
+		m_ConnTrackTimer.async_wait (
+			std::bind (&StreamingDestination::HandleConnTrack, 
+								 shared_from_this (), std::placeholders::_1));
+	}
 }		
 }	

Streaming.h

@@ -52,6 +52,22 @@ namespace stream
 	const size_t MAX_PENDING_INCOMING_BACKLOG = 128;
 	const int PENDING_INCOMING_TIMEOUT = 10; // in seconds
 
+	/** i2cp option for limiting inbound stremaing connections */
+	const char I2CP_PARAM_STREAMING_MAX_CONNS_PER_MIN[] = "i2p.streaming.maxConnsPerMinute";
+	/** default maximum connections attempts per minute per destination */
+	const uint32_t DEFAULT_MAX_CONNS_PER_MIN = 600;
+
+	/** 
+	 * max banned destinations per local destination
+	 * TODO: make configurable
+	 */
+	const uint16_t MAX_BANNED_CONNS = 9999;
+	/** 
+	 * length of a ban in ms
+	 * TODO: make configurable 
+	 */
+	const uint64_t DEFAULT_BAN_INTERVAL = 60 * 60 * 1000;
+	
 	struct Packet
 	{
 		size_t len, offset;
@@ -210,12 +226,22 @@ namespace stream
 			void HandleDataMessagePayload (const uint8_t * buf, size_t len);
 			std::shared_ptr<I2NPMessage> CreateDataMessage (const uint8_t * payload, size_t len, uint16_t toPort);
 
+			/** set max connections per minute per destination */
+			void SetMaxConnsPerMinute(const uint32_t conns);
+			
 		private:		
 	
 			void HandleNextPacket (Packet * packet);
 			std::shared_ptr<Stream> CreateNewIncomingStream ();
 			void HandlePendingIncomingTimer (const boost::system::error_code& ecode);
 
+			/** handle cleaning up connection tracking for ratelimits */
+			void HandleConnTrack(const boost::system::error_code& ecode);
+
+			bool DropNewStream(const i2p::data::IdentHash & ident);
+
+			void ScheduleConnTrack();
+      
 		private:
 
 			std::shared_ptr<i2p::client::ClientDestination> m_Owner;
@@ -228,6 +254,15 @@ namespace stream
 			boost::asio::deadline_timer m_PendingIncomingTimer;
 			std::map<uint32_t, std::list<Packet *> > m_SavedPackets; // receiveStreamID->packets, arrived before SYN
       
+			std::mutex m_ConnsMutex;
+			/** how many connections per minute did each identity have */
+			std::map<i2p::data::IdentHash, uint32_t> m_Conns;
+			boost::asio::deadline_timer m_ConnTrackTimer;
+			uint32_t m_ConnsPerMinute;
+			/** banned identities */
+			std::vector<i2p::data::IdentHash> m_Banned;
+			uint64_t m_LastBanClear;
+      
 		public:
 
 			i2p::data::GzipInflator m_Inflator;