Avoid unnecessary buffer copies & allocates in NIO

Author: pimterry

app/src/main/java/tech/httptoolkit/android/vpn/capture/SOCKS5Handler.java

@@ -76,10 +76,6 @@ public void confirmHandshakeDataWritten() {
 
     @Override
     public void processHandshakeData(ByteBuffer data) {
-        ByteBuffer view = data.asReadOnlyBuffer();
-        byte[] bytes = new byte[view.remaining()];
-        view.get(bytes);
-
         switch (socksState) {
             case AUTH_REQUEST_PENDING:
                 if (SOCKS5Protocol.parseAuthResponse(data)) {

app/src/main/java/tech/httptoolkit/android/vpn/socket/SocketChannelReader.java

@@ -39,6 +39,10 @@ class SocketChannelReader {
 
 	private final ClientPacketWriter writer;
 
+	// We're single-threaded, so we can just reuse a single max-size buffer
+	// over and over instead of endlessly reallocating it.
+	private final ByteBuffer readBuffer = ByteBuffer.allocate(DataConst.MAX_RECEIVE_BUFFER_SIZE);
+
 	public SocketChannelReader(ClientPacketWriter writer) {
 		this.writer = writer;
 	}
@@ -89,17 +93,16 @@ private void readTCP(@NonNull Session session) {
 		}
 
 		SocketChannel channel = (SocketChannel) session.getChannel();
-		ByteBuffer buffer = ByteBuffer.allocate(DataConst.MAX_RECEIVE_BUFFER_SIZE);
 		int len;
 
 		try {
 			do {
-				len = channel.read(buffer);
+				len = channel.read(readBuffer);
 				if (len > 0) { //-1 mean it reach the end of stream
-					buffer.limit(len);
-					buffer.flip();
-					sendToRequester(buffer, session);
-					buffer.clear();
+					readBuffer.limit(len);
+					readBuffer.flip();
+					sendToRequester(readBuffer, session);
+					readBuffer.clear();
 				} else if (len == -1) {
 					Log.d(TAG,"End of data from remote server, will send FIN to client");
 					Log.d(TAG,"send FIN to: " + session);
@@ -206,7 +209,6 @@ private void sendFin(Session session){
 
 	private void readUDP(Session session){
 		DatagramChannel channel = (DatagramChannel) session.getChannel();
-		ByteBuffer buffer = ByteBuffer.allocate(DataConst.MAX_RECEIVE_BUFFER_SIZE);
 		int len;
 
 		try {
@@ -215,23 +217,21 @@ private void readUDP(Session session){
 					break;
 				}
 
-				len = channel.read(buffer);
+				len = channel.read(readBuffer);
 				if (len > 0) {
-					buffer.limit(len);
-					buffer.flip();
+					readBuffer.limit(len);
+					readBuffer.flip();
 
 					//create UDP packet
-					byte[] data = new byte[len];
-					System.arraycopy(buffer.array(),0, data, 0, len);
 					byte[] packetData = UDPPacketFactory.createResponsePacket(
-							session.getLastIpHeader(), session.getLastUdpHeader(), data);
+							session.getLastIpHeader(), session.getLastUdpHeader(), readBuffer);
+					readBuffer.clear();
 
 					//write to client
 					writer.write(packetData);
 
 					Log.d(TAG,"SDR: sent " + len + " bytes to UDP client, packetData.length: "
 							+ packetData.length);
-					buffer.clear();
 				}
 			} while(len > 0);
 		}catch(NotYetConnectedException ex){

app/src/main/java/tech/httptoolkit/android/vpn/transport/udp/UDPPacketFactory.java

@@ -34,12 +34,10 @@ public static UDPHeader copyHeader(UDPHeader header){
 	 * @param packetData packet data to be sent to client
 	 * @return array of byte
 	 */
-	public static byte[] createResponsePacket(IPv4Header ip, UDPHeader udp, byte[] packetData){
+	public static byte[] createResponsePacket(IPv4Header ip, UDPHeader udp, ByteBuffer packetData){
 		byte[] buffer;
 		int udpLen = 8;
-		if(packetData != null){
-			udpLen += packetData.length;
-		}
+		udpLen += packetData.remaining();
 		int srcPort = udp.getDestinationPort();
 		int destPort = udp.getSourcePort();
 		short checksum = 0;
@@ -90,8 +88,7 @@ public static byte[] createResponsePacket(IPv4Header ip, UDPHeader udp, byte[] p
 		start += 2;
 
 		//now copy udp data
-		if (packetData != null)
-		System.arraycopy(packetData, 0, buffer, start, packetData.length);
+		packetData.get(buffer, start, packetData.remaining());
 
 		return buffer;
 	}