Add graceful TCP termination and remove useless TCP window full check

LipiLee · Apr 30, 2018 · a511e0e · a511e0e · LipiLee · Apr 30, 2018
1 parent 9704cc2
commit a511e0e
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Showing 2 changed files with 22 additions and 11 deletions.
diff --git a/app/src/main/java/com/lipisoft/toyshark/SessionHandler.java b/app/src/main/java/com/lipisoft/toyshark/SessionHandler.java
@@ -97,10 +97,14 @@ private void handleTCPPacket(ByteBuffer clientPacketData, IPv4Header ipHeader, T
 			Session session = SessionManager.INSTANCE.getSessionByKey(key);
 
 			if(session == null) {
-				Log.e(TAG,"**** ==> Session not found: " + key);
-				if(!tcpheader.isRST() && !tcpheader.isFIN()){
+				if (tcpheader.isFIN()) {
+					sendLastAck(ipHeader, tcpheader);
+				} else if (!tcpheader.isRST()) {
 					sendRstPacket(ipHeader, tcpheader, dataLength);
 				}
+				else {
+					Log.e(TAG,"**** ==> Session not found: " + key);
+				}
 				return;
 			}
 
@@ -208,6 +212,20 @@ private void sendRstPacket(IPv4Header ip, TCPHeader tcp, int dataLength){
 			Log.e(TAG,"failed to send RST packet: " + e.getMessage());
 		}
 	}
+
+	private void sendLastAck(IPv4Header ip, TCPHeader tcp){
+		byte[] data = TCPPacketFactory.createResponseAckData(ip, tcp, tcp.getSequenceNumber()+1);
+		try {
+			writer.write(data);
+			packetData.addData(data);
+			Log.d(TAG,"Sent RST Packet to client with dest => " +
+					PacketUtil.intToIPAddress(ip.getDestinationIP()) + ":" +
+					tcp.getDestinationPort());
+		} catch (IOException e) {
+			Log.e(TAG,"failed to send RST packet: " + e.getMessage());
+		}
+	}
+
 	private void ackFinAck(IPv4Header ip, TCPHeader tcp, Session session){
 		//TODO: check if client send only FIN without ACK
 		long ack = tcp.getSequenceNumber() + 1;
@@ -331,14 +349,6 @@ private void acceptAck(IPv4Header ipHeader, TCPHeader tcpHeader, Session session
 			if(tcpHeader.getWindowSize() > 0){
 				session.setSendWindowSizeAndScale(tcpHeader.getWindowSize(), session.getSendWindowScale());
 			}
-			long byteReceived = tcpHeader.getAckNumber() - session.getSendUnack();
-			if(byteReceived > 0){
-				session.decreaseAmountSentSinceLastAck(byteReceived);
-			}
-			if(session.isClientWindowFull()){
-				Log.d(TAG,"window: "+session.getSendWindow()+" is full? "+session.isClientWindowFull() + " for "+PacketUtil.intToIPAddress(ipHeader.getDestinationIP())
-					+":"+tcpHeader.getDestinationPort()+"-"+PacketUtil.intToIPAddress(ipHeader.getSourceIP())+":"+tcpHeader.getSourcePort());
-			}
 			session.setSendUnack(tcpHeader.getAckNumber());
 			session.setRecSequence(tcpHeader.getSequenceNumber());
 			session.setTimestampReplyto(tcpHeader.getTimeStampSender());

diff --git a/app/src/main/java/com/lipisoft/toyshark/transport/tcp/TCPPacketFactory.java b/app/src/main/java/com/lipisoft/toyshark/transport/tcp/TCPPacketFactory.java
@@ -128,7 +128,7 @@ public static byte[] createFinData(IPv4Header ip, TCPHeader tcp, long ackNumber,
 		ip.setIdentification(PacketUtil.getPacketId());
 
 		tcp.setIsRST(false);
-		tcp.setIsACK(false);
+		tcp.setIsACK(true);
 		tcp.setIsSYN(false);
 		tcp.setIsPSH(false);
 		tcp.setIsCWR(false);
@@ -247,6 +247,7 @@ public static byte[] createResponseAckData(IPv4Header ipHeader, TCPHeader tcphea
 		tcp.setIsACK(true);
 		tcp.setIsSYN(false);
 		tcp.setIsPSH(false);
+		tcp.setIsFIN(false);
 
 		//set response timestamps in options fields
 		tcp.setTimeStampReplyTo(tcp.getTimeStampSender());