ping/pong for streaming

libi2pd/Destination.cpp

@@ -851,6 +851,7 @@ namespace client
 		bool isPublic, const std::map<std::string, std::string> * params):
 		LeaseSetDestination (service, isPublic, params), 
 		m_Keys (keys), m_StreamingAckDelay (DEFAULT_INITIAL_ACK_DELAY), 
+		m_IsStreamingAnswerPings (DEFAULT_ANSWER_PINGS),
 		m_DatagramDestination (nullptr), m_RefCounter (0),
 		m_ReadyChecker(service)
 	{
@@ -918,6 +919,9 @@ namespace client
 				auto it = params->find (I2CP_PARAM_STREAMING_INITIAL_ACK_DELAY);
 				if (it != params->end ())
 					m_StreamingAckDelay = std::stoi(it->second);
+				it = params->find (I2CP_PARAM_STREAMING_ANSWER_PINGS);
+				if (it != params->end ())
+					m_IsStreamingAnswerPings = (it->second == "true");
 				
 				if (GetLeaseSetType () == i2p::data::NETDB_STORE_TYPE_ENCRYPTED_LEASESET2)
 				{

libi2pd/Destination.h

@@ -78,6 +78,8 @@ namespace client
 	// streaming
 	const char I2CP_PARAM_STREAMING_INITIAL_ACK_DELAY[] = "i2p.streaming.initialAckDelay";
 	const int DEFAULT_INITIAL_ACK_DELAY = 200; // milliseconds
+	const char I2CP_PARAM_STREAMING_ANSWER_PINGS[] = "i2p.streaming.answerPings";
+	const int DEFAULT_ANSWER_PINGS = true; 
 
 	typedef std::function<void (std::shared_ptr<i2p::stream::Stream> stream)> StreamRequestComplete;
 
@@ -242,6 +244,7 @@ namespace client
 			bool IsAcceptingStreams () const;
 			void AcceptOnce (const i2p::stream::StreamingDestination::Acceptor& acceptor);
 			int GetStreamingAckDelay () const { return m_StreamingAckDelay; }
+			bool IsStreamingAnswerPings () const { return m_IsStreamingAnswerPings; }
 			
 			// datagram
 			i2p::datagram::DatagramDestination * GetDatagramDestination () const { return m_DatagramDestination; };
@@ -275,6 +278,7 @@ namespace client
 			std::unique_ptr<EncryptionKey> m_ECIESx25519EncryptionKey;
 
 			int m_StreamingAckDelay;
+			bool m_IsStreamingAnswerPings;
 			std::shared_ptr<i2p::stream::StreamingDestination> m_StreamingDestination; // default
 			std::map<uint16_t, std::shared_ptr<i2p::stream::StreamingDestination> > m_StreamingDestinationsByPorts;
 			i2p::datagram::DatagramDestination * m_DatagramDestination;

libi2pd/Streaming.cpp

@@ -351,6 +351,28 @@ namespace stream
 		return true;
 	}
 
+	void Stream::HandlePing (Packet * packet)
+	{
+		uint16_t flags = packet->GetFlags ();
+		if (ProcessOptions (flags, packet) && m_RemoteIdentity)
+		{
+			// send pong
+			Packet p;
+			memset (p.buf, 0, 22); // minimal header all zeroes
+			memcpy (p.buf + 4, packet->buf, 4); // but receiveStreamID is the sendStreamID from the ping
+			htobe16buf (p.buf + 18, PACKET_FLAG_ECHO); // and echo flag
+			ssize_t payloadLen = packet->len - (packet->GetPayload () - packet->buf);
+			if (payloadLen > 0)
+				memcpy (p.buf + 22, packet->GetPayload (), payloadLen);
+			else
+				payloadLen = 0;
+			p.len = payloadLen + 22;
+			SendPackets (std::vector<Packet *> { &p });
+			LogPrint (eLogDebug, "Streaming: Pong of ", p.len, " bytes sent");
+		}	
+		m_LocalDestination.DeletePacket (packet);
+	}	
+		
 	void Stream::ProcessAck (Packet * packet)
 	{
 		bool acknowledged = false;
@@ -609,6 +631,7 @@ namespace stream
 			packet[size] = 0;
 			size++; // NACK count
 		}
+		packet[size] = 0;
 		size++; // resend delay
 		htobuf16 (packet + size, 0); // no flags set
 		size += 2; // flags
@@ -666,6 +689,7 @@ namespace stream
 		size += 4; // ack Through
 		packet[size] = 0;
 		size++; // NACK count
+		packet[size] = 0;
 		size++; // resend delay
 		htobe16buf (packet + size, PACKET_FLAG_CLOSE | PACKET_FLAG_SIGNATURE_INCLUDED);
 		size += 2; // flags
@@ -1016,6 +1040,13 @@ namespace stream
 			auto it = m_Streams.find (sendStreamID);
 			if (it != m_Streams.end ())
 				it->second->HandleNextPacket (packet);
+			else if (packet->IsEcho () && m_Owner->IsStreamingAnswerPings ())
+			{
+				// ping
+				LogPrint (eLogInfo, "Streaming: Ping received sSID=", sendStreamID);
+				auto s = std::make_shared<Stream> (m_Owner->GetService (), *this);
+				s->HandlePing (packet);
+			}		
 			else
 			{
 				LogPrint (eLogInfo, "Streaming: Unknown stream sSID=", sendStreamID);

libi2pd/Streaming.h

@@ -87,6 +87,7 @@ namespace stream
 
 		bool IsSYN () const { return GetFlags () & PACKET_FLAG_SYNCHRONIZE; };
 		bool IsNoAck () const { return GetFlags () & PACKET_FLAG_NO_ACK; };
+		bool IsEcho () const { return GetFlags () & PACKET_FLAG_ECHO; };
 	};
 
 	struct PacketCmp
@@ -168,6 +169,7 @@ namespace stream
 			StreamingDestination& GetLocalDestination () { return m_LocalDestination; };
 
 			void HandleNextPacket (Packet * packet);
+			void HandlePing (Packet * packet);
 			size_t Send (const uint8_t * buf, size_t len);
 			void AsyncSend (const uint8_t * buf, size_t len, SendHandler handler);
 

libi2pd_client/ClientContext.cpp

@@ -453,6 +453,7 @@ namespace client
 		options[I2CP_PARAM_MIN_TUNNEL_LATENCY] = GetI2CPOption(section, I2CP_PARAM_MIN_TUNNEL_LATENCY, DEFAULT_MIN_TUNNEL_LATENCY);
 		options[I2CP_PARAM_MAX_TUNNEL_LATENCY] = GetI2CPOption(section, I2CP_PARAM_MAX_TUNNEL_LATENCY, DEFAULT_MAX_TUNNEL_LATENCY);
 		options[I2CP_PARAM_STREAMING_INITIAL_ACK_DELAY] = GetI2CPOption(section, I2CP_PARAM_STREAMING_INITIAL_ACK_DELAY, DEFAULT_INITIAL_ACK_DELAY);
+		options[I2CP_PARAM_STREAMING_ANSWER_PINGS] = GetI2CPOption(section, I2CP_PARAM_STREAMING_ANSWER_PINGS, DEFAULT_ANSWER_PINGS);
 		options[I2CP_PARAM_LEASESET_TYPE] = GetI2CPOption(section, I2CP_PARAM_LEASESET_TYPE, DEFAULT_LEASESET_TYPE);
 		std::string encType = GetI2CPStringOption(section, I2CP_PARAM_LEASESET_ENCRYPTION_TYPE, "");
 		if (encType.length () > 0) options[I2CP_PARAM_LEASESET_ENCRYPTION_TYPE] = encType;