From 2d7fe232b7c1f2ef62e7bf2f3100adb51e9bc0d4 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Magdalena=20Grodzi=C5=84ska?= <mag.grodzinska@gmail.com>
Date: Mon, 6 Jan 2020 22:13:48 +0100
Subject: Add segmentation handling

---
 .../mimuw/cloudatlas/agent/modules/UDUPClient.java | 62 +++++++++++++++++-----
 1 file changed, 48 insertions(+), 14 deletions(-)

(limited to 'src/main/java/pl/edu/mimuw/cloudatlas/agent/modules/UDUPClient.java')

diff --git a/src/main/java/pl/edu/mimuw/cloudatlas/agent/modules/UDUPClient.java b/src/main/java/pl/edu/mimuw/cloudatlas/agent/modules/UDUPClient.java
index 82aaeb1..d7cbc9d 100644
--- a/src/main/java/pl/edu/mimuw/cloudatlas/agent/modules/UDUPClient.java
+++ b/src/main/java/pl/edu/mimuw/cloudatlas/agent/modules/UDUPClient.java
@@ -2,8 +2,10 @@ package pl.edu.mimuw.cloudatlas.agent.modules;
 
 import pl.edu.mimuw.cloudatlas.agent.messages.UDUPMessage;
 
+import javax.xml.crypto.Data;
 import java.io.IOException;
 import java.net.*;
+import java.nio.ByteBuffer;
 
 public class UDUPClient {
     private UDUP udp;
@@ -11,6 +13,7 @@ public class UDUPClient {
     private int serverPort;
     private DatagramSocket socket;
     private int bufsize;
+    private int lastTransmission;
 
     UDUPClient(UDUP udp, int serverPort, int bufferSize) throws SocketException {
         this.udp = udp;
@@ -18,26 +21,57 @@ public class UDUPClient {
         this.socket = new DatagramSocket();
         this.bufsize = bufferSize;
         this.serializer = new UDUPSerializer();
+        this.lastTransmission = 0;
     }
 
-    public void sendMessage(UDUPMessage msg) throws IOException {
-        int offset = 0;
-        int outputSize;
+    private void logSending(DatagramPacket packet, int packetNo, byte[] buf) {
+        System.out.print("UDP sends packet no " + packetNo +
+                " with realbufsize " + (bufsize - 8) +
+                " out of data buffer with size " + buf.length +
+                " to " + packet.getAddress() + ": ");
+        for (byte b : packet.getData()) {
+            System.out.print(b);
+        }
+        System.out.println();
+    }
 
-        byte[] buf = this.serializer.serialize(msg);
-        outputSize = buf.length;
+    byte[] toByteArray(int val) {
+        return ByteBuffer.allocate(4).putInt(val).array();
+    }
+
+    private byte[] packSendBuffer(int transmissionNo, int packetNo, byte[] buf) {
+        byte[] sendBuf = new byte[bufsize];
+        int sendBufSize = bufsize - 8;
+        System.arraycopy(toByteArray(transmissionNo), 0, sendBuf, 0, 4);
+        System.arraycopy(toByteArray(packetNo), 0, sendBuf, 4, 4);
+        if (packetNo*sendBufSize >= buf.length) {
+            System.arraycopy(buf, 0, sendBuf, 8, sendBufSize);
+        } else {
+            System.arraycopy(buf, (packetNo-1)*sendBufSize, sendBuf, 8, sendBufSize);
+        }
+        return sendBuf;
+    }
+
+    boolean checkEndOfTransmission(int packetNo, int dataBufSize) {
+        int sendBufSize = bufsize - 8;
+        int dataSentSoFar = (packetNo - 1) * sendBufSize;
+        System.out.println("used data " + dataSentSoFar + " " + dataBufSize);
+        return dataSentSoFar >= dataBufSize;
+    }
+
+    public void sendMessage(UDUPMessage msg) throws IOException {
+        int packetNo = 1;
+        byte[] sendBuf;
+        byte[] dataBuf = this.serializer.serialize(msg);
+        this.lastTransmission++;
 
         do {
-            outputSize =- bufsize;
-            offset += bufsize;
-            DatagramPacket packet = new DatagramPacket(buf, buf.length, msg.getContact().getAddress(), this.serverPort);
-            System.out.println("UDP sends message: ");
-            for (byte b : buf) {
-                System.out.print(b);
-            }
-            System.out.println("to " + packet.getAddress());
+            sendBuf = packSendBuffer(this.lastTransmission, packetNo, dataBuf);
+            DatagramPacket packet = new DatagramPacket(sendBuf, bufsize, msg.getContact().getAddress(), this.serverPort);
             this.socket.send(packet);
-        } while (outputSize > bufsize);
+            logSending(packet, packetNo, dataBuf);
+            packetNo++;
+        } while (!checkEndOfTransmission(packetNo, dataBuf.length));
     }
 
     void close() {
-- 
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