Change to ProtocolP2PPacket, should be easier to implement tcp

src/clientP2P/ClientManagementUDP.java

@@ -20,7 +20,7 @@ import java.nio.file.Files;
 import java.io.File;
 import java.nio.file.Paths;
 import java.nio.file.StandardOpenOption;
-import protocolP2P.ProtocolP2PDatagram;
+import protocolP2P.ProtocolP2PPacketUDP;
 import protocolP2P.Payload;
 import protocolP2P.RequestResponseCode;
 import protocolP2P.FileList;
@@ -52,9 +52,13 @@ public class ClientManagementUDP implements Runnable {
 		this.UDPPort = UDPPort;
 		try {
 			socket = new DatagramSocket();
+			socket.connect(InetAddress.getByName(host), UDPPort);
 		} catch (SocketException e) {
 			System.err.println("Error: No socket available.");
 			System.exit(-1);
+		} catch (UnknownHostException e) {
+			System.err.println("Error: Unknown host.");
+			System.exit(-1);
 		}
 	}
 
@@ -118,13 +122,13 @@ public class ClientManagementUDP implements Runnable {
 	 */
 	private void download(String filename) throws EmptyFile, NotFound, InternalError, UnknownHostException, IOException, TransmissionError, ProtocolError, VersionError, SizeError, InternalRemoteError, ProtocolRemoteError, VersionRemoteError {
 		final long MAX_PARTIAL_SIZE = 1024;
-		ProtocolP2PDatagram d = new ProtocolP2PDatagram((Payload) new LoadRequest(filename, 0, MAX_PARTIAL_SIZE));
-		d.send(socket, host, UDPPort);
+		ProtocolP2PPacketUDP d = new ProtocolP2PPacketUDP((Payload) new LoadRequest(filename, 0, MAX_PARTIAL_SIZE));
+		d.sendRequest((Object)socket);
 		boolean fileFullyWritten = false;
 		long offset = 0;
 		do {
 			try {
-				Payload p = ProtocolP2PDatagram.receive(socket).getPayload();
+				Payload p = d.receiveResponse().getPayload();
 				assert p instanceof FilePart : "This payload must be instance of FilePart";
 				if (!(p instanceof FilePart)) {
 					throw new InternalError();
@@ -148,8 +152,8 @@ public class ClientManagementUDP implements Runnable {
 						// next partialContentRequest
 						if (offset != fp.getTotalSize()) {
 							System.err.println("Sending following request with offset: " + offset + " maxpartialsize: " + MAX_PARTIAL_SIZE);
-							d = new ProtocolP2PDatagram((Payload) new LoadRequest(filename, offset, MAX_PARTIAL_SIZE));
-							d.send(socket, host, UDPPort);
+							d = new ProtocolP2PPacketUDP((Payload) new LoadRequest(filename, offset, MAX_PARTIAL_SIZE));
+							d.sendRequest((Object)socket);
 						} else {
 							fileFullyWritten = true;
 						}
@@ -168,8 +172,8 @@ public class ClientManagementUDP implements Runnable {
 							fileFullyWritten = true;
 						} else {
 							// next partialContentRequest
-							d = new ProtocolP2PDatagram((Payload) new LoadRequest(filename, offset, MAX_PARTIAL_SIZE));
-							d.send(socket, host, UDPPort);
+							d = new ProtocolP2PPacketUDP((Payload) new LoadRequest(filename, offset, MAX_PARTIAL_SIZE));
+							d.sendRequest((Object)socket);
 						}
 					
 					} else {
@@ -199,10 +203,10 @@ public class ClientManagementUDP implements Runnable {
 	 * @throws	VersionRemoteError
 	 */
 	private String[] listDirectory() throws EmptyDirectory, InternalError, UnknownHostException, IOException, TransmissionError, ProtocolError, VersionError, SizeError, InternalRemoteError, ProtocolRemoteError, VersionRemoteError {
-		ProtocolP2PDatagram d = new ProtocolP2PDatagram(new Payload(RequestResponseCode.LIST_REQUEST));
-		d.send(socket, host, UDPPort);
+		ProtocolP2PPacketUDP d = new ProtocolP2PPacketUDP(new Payload(RequestResponseCode.LIST_REQUEST));
+		d.sendRequest((Object)socket);
 		try {
-			Payload p = ProtocolP2PDatagram.receive(socket).getPayload();
+			Payload p = d.receiveResponse().getPayload();
 			assert p instanceof FileList : "This payload must be instance of Filelist";
 			if (!(p instanceof FileList)) {
 				throw new InternalError();

src/clientP2P/ClientP2P.java

@@ -1,6 +1,6 @@
 package clientP2P;
 import clientP2P.ClientManagementUDP;
-import clientP2P.ClientManagementTCP;
+//import clientP2P.ClientManagementTCP;
 import tools.Directories;
 import java.util.Scanner;
 
@@ -21,20 +21,24 @@ public class ClientP2P {
 		System.out.println("Which transport protocol do you want to use? [TCP/udp]");
 		Scanner sc = new Scanner(System.in);
 		String transportchoosen = sc.nextLine();
+		Thread t;
 		switch(transportchoosen){
 			case "UDP":
 			case "udp":
 			case "2" :
-				ClientManagementUDP cm = new ClientManagementUDP(c.directories.getDataHomeDirectory(), c.host, c.port);
+				ClientManagementUDP cmudp = new ClientManagementUDP(c.directories.getDataHomeDirectory(), c.host, c.port);
+				t = new Thread(cmudp);
 				break;
 			case "TCP":
 			case "tcp":
 			case "1":
 			default:
-				ClientManagementTCP cm = new ClientManagementTCP(c.directories.getDataHomeDirectory(), c.host, c.port);
-		    break;
+				//ClientManagementTCP cmtcp = new ClientManagementTCP(c.directories.getDataHomeDirectory(), c.host, c.port);
+				//t = new Thread(cmtcp);
+				//break;
+				throw new java.lang.UnsupportedOperationException();
 		  }
-		Thread t = new Thread(cm);
+
 		t.setName("client P2P-JAVA-PROJECT");
 		t.start();
 	}

src/exception/SizeError.java

@@ -1,5 +1,5 @@
 package exception;
-/** Used on reception side when size as set in datagram is too big, and we cant store this in a int/long as usual. */
+/** Used on reception side when size as set in Packet is too big, and we cant store this in a int/long as usual. */
 public class SizeError extends Exception {
 	private static final long serialVersionUID = 12L;
 }

src/protocolP2P/FileList.java

@@ -32,54 +32,54 @@ public class FileList extends Payload {
 		this.fileList = fileList;
 	}
 
-	/** Constructor (typically used by client) with a byte[] parameter containing the datagram received.
-	 * @param datagram	the full datagram received
+	/** Constructor (typically used by client) with a byte[] parameter containing the Packet received.
+	 * @param packet	the full packet received
 	 * @throws	SizeError
 	 * @throws	InternalError
 	 * @throws	ProtocolError
 	 * @throws	TransmissionError
 	 */
-	protected FileList(byte[] datagram) throws TransmissionError, SizeError, ProtocolError, InternalError {
-		super(datagram);
+	protected FileList(byte[] packet) throws TransmissionError, SizeError, ProtocolError, InternalError {
+		super(packet);
 		/* assert to help debugging */
-		assert requestResponseCode == RequestResponseCode.LIST_RESPONSE : "FileList subclass is incompatible with this datagram, request/response code must be checked before using this constructor";
+		assert requestResponseCode == RequestResponseCode.LIST_RESPONSE : "FileList subclass is incompatible with this Packet, request/response code must be checked before using this constructor";
 		/* InternalErrorException */
 		if (requestResponseCode!= RequestResponseCode.LIST_RESPONSE) {
 			throw new InternalError();
 		}
-		int size = getPayloadSize(datagram);
+		int size = getPayloadSize(packet);
 		try {
-			fileList = (new String(datagram, 8, size, "UTF-8")).split("\n");
+			fileList = (new String(packet, PAYLOAD_START_POSITION, size, "UTF-8")).split("\n");
 		} catch (UnsupportedEncodingException e) {
 			throw new InternalError();
 		}
 	}
 
-	/** Returns a byte[] containing datagram with padding.
-	 * This datagram is still incomplete and should not be send directly.
-	 * ProtocolP2PDatagram will use this method to generate the complete datagram.
-	 * @return datagram with padding
+	/** Returns a byte[] containing Packet with padding.
+	 * This Packet is still incomplete and should not be send directly.
+	 * ProtocolP2PPacket will use this method to generate the complete Packet.
+	 * @return Packet with padding
 	 * @throws	InternalError
 	 */
-	protected byte[] toDatagram() throws InternalError {
+	protected byte[] toPacket() throws InternalError {
 		// compute size
-		int size = 8;
+		int size = PAYLOAD_START_POSITION;
 		for (String s : fileList) {
 			size += s.length();
-			size += 1;
+			size += 1; // size for '\n'
 		}
-		size -=1;
-		byte[] datagram = new byte[size]; // java initialize all to zero
+		size -=1; // remove trailing '\n'
+		byte[] packet = new byte[size]; // java initialize all to zero
 		// set request/response code
-		datagram[RequestResponseCode.RRCODE_POSITION] = requestResponseCode.codeValue;
-		// bits 16-31 are reserved for future use
-		setPayloadSize(size - 8, datagram);
+		packet[RequestResponseCode.RRCODE_POSITION] = requestResponseCode.codeValue;
+		// set payload size
+		setPayloadSize(size - PAYLOAD_START_POSITION, packet);
 		// Write fileList
-		int bCount = 8;
+		int bCount = PAYLOAD_START_POSITION;
 		for(String s : fileList) {
-			if (bCount != 8) { // not on first iteration
+			if (bCount != PAYLOAD_START_POSITION) { // not on first iteration
 				try {
-					datagram[bCount] = "\n".getBytes("UTF-8")[0]; // separator
+					packet[bCount] = "\n".getBytes("UTF-8")[0]; // separator
 				} catch (UnsupportedEncodingException e) {
 					throw new InternalError();
 				}
@@ -89,7 +89,7 @@ public class FileList extends Payload {
 			try {
 				byte[] sb = s.getBytes("UTF-8");
 				for(byte b : sb) {
-					datagram[bCount] = b;
+					packet[bCount] = b;
 					bCount += 1;
 				}
 			} catch (UnsupportedEncodingException e) {
@@ -97,7 +97,7 @@ public class FileList extends Payload {
 			}
 			
 		}
-		return datagram;
+		return packet;
 	}
 
 	/** fileList getter.

src/protocolP2P/FilePart.java

@@ -20,7 +20,7 @@ public class FilePart extends Payload {
 	private long totalSize;
 	private long offset;
 	private byte[] partialContent;
-	static final private int OFFSET_POSITION = 8;
+	static final private int OFFSET_POSITION = PAYLOAD_START_POSITION;
 	static final private int TOTAL_FILESIZE_POSITION = OFFSET_POSITION + 8;
 	static final private int FILENAME_SIZE_POSITION = TOTAL_FILESIZE_POSITION + 8;
 	static final private int FILENAME_POSITION = FILENAME_SIZE_POSITION + 4;
@@ -50,123 +50,123 @@ public class FilePart extends Payload {
 		this.partialContent = partialContent;
 	}
 
-	/** Constructor (typically used by client) with datagram received as parameter.
-	 * @param datagram	the full datagram received
+	/** Constructor (typically used by client) with Packet received as parameter.
+	 * @param packet	the full Packet received
 	 * @throws	SizeError
 	 * @throws	InternalError
 	 * @throws	TransmissionError
 	 */
-	protected FilePart(byte[] datagram) throws TransmissionError, SizeError, ProtocolError, InternalError {
-		super(datagram);
+	protected FilePart(byte[] packet) throws TransmissionError, SizeError, ProtocolError, InternalError {
+		super(packet);
 		/* assert to help debugging */
-		assert requestResponseCode == RequestResponseCode.LOAD_RESPONSE : "FilePart subclass is incompatible with this datagram, request/response code must be checked before using this constructor";
+		assert requestResponseCode == RequestResponseCode.LOAD_RESPONSE : "FilePart subclass is incompatible with this Packet, request/response code must be checked before using this constructor";
 		/* InternalErrorException */
 		if (requestResponseCode != RequestResponseCode.LOAD_RESPONSE) {
 			throw new InternalError();
 		}
-		setOffset(datagram); // this can throw SizeError
-		setTotalSize(datagram); // this can throw SizeError
-		setFilename(datagram); // this can throw ProtocolError, SizeError
-		setPartialContent(datagram); // this can throw SizeError
+		setOffset(packet); // this can throw SizeError
+		setTotalSize(packet); // this can throw SizeError
+		setFilename(packet); // this can throw ProtocolError, SizeError
+		setPartialContent(packet); // this can throw SizeError
 	}
 
-	/** Returns a byte[] containing datagram with padding.
-	 * This datagram is still incomplete and should not be send directly.
-	 * ProtocolP2PDatagram will use this method to generate the complete datagram.
-	 * @return datagram with padding
+	/** Returns a byte[] containing Packet with padding.
+	 * This Packet is still incomplete and should not be send directly.
+	 * ProtocolP2PPacket will use this method to generate the complete Packet.
+	 * @return Packet with padding
 	 * @throws	InternalError
 	 */
-	protected byte[] toDatagram() throws InternalError {
+	protected byte[] toPacket() throws InternalError {
 		// compute total size
 		int size = FILENAME_POSITION + filename.length() + partialContent.length;
-		byte[] datagram = new byte[size + 1]; // java initialize all to zero
+		byte[] packet = new byte[size + 1]; // java initialize all to zero
 		// set request/response code
-		datagram[RequestResponseCode.RRCODE_POSITION] = requestResponseCode.codeValue;
-		// bits 16-31 are reserved for future use
-		setPayloadSize(size - OFFSET_POSITION, datagram);
-		// write offset to datagram
-		BytesArrayTools.write(datagram, OFFSET_POSITION, (long)offset);
-		// write totalSize to datagram
-		BytesArrayTools.write(datagram, TOTAL_FILESIZE_POSITION, (long)totalSize);
-		// write filename’s size to datagram
-		BytesArrayTools.write(datagram, FILENAME_SIZE_POSITION, (int)filename.length());
+		packet[RequestResponseCode.RRCODE_POSITION] = requestResponseCode.codeValue;
+		// set Payload size
+		setPayloadSize(size - OFFSET_POSITION, packet);
+		// write offset to Packet
+		BytesArrayTools.write(packet, OFFSET_POSITION, offset);
+		// write totalSize to Packet
+		BytesArrayTools.write(packet, TOTAL_FILESIZE_POSITION, totalSize);
+		// write filename’s size to Packet
+		BytesArrayTools.write(packet, FILENAME_SIZE_POSITION, filename.length());
 		try {
-			// write filename to datagram
+			// write filename to Packet
 			int i = FILENAME_POSITION;
 			for (byte b : filename.getBytes("UTF-8")) {
-				datagram[i] = b;
+				packet[i] = b;
 				i += 1;
 			}
-			// write partialContent to datagram
+			// write partialContent to Packet
 			for (byte b: partialContent) {
-				datagram[i] = b;
+				packet[i] = b;
 				i += 1;
 			}
-			return datagram;
+			return packet;
 		} catch (UnsupportedEncodingException e) {
 			throw new InternalError();
 		}
 	}
 
-	/** Write from datagram into offset.
-	 * @param datagram	received datagram
+	/** Write from Packet into offset.
+	 * @param packet	received Packet
 	 * @throws	SizeError
 	 */
-	private void setOffset(byte[] datagram) throws SizeError {
-		offset = BytesArrayTools.readLong(datagram, OFFSET_POSITION);
+	private void setOffset(byte[] packet) throws SizeError {
+		offset = BytesArrayTools.readLong(packet, OFFSET_POSITION);
 	}
-	/** Write from datagram into totalSize.
-	 * @param datagram	received datagram
+	/** Write from Packet into totalSize.
+	 * @param packet	received Packet
 	 * @throws	SizeError
 	 */
-	private void setTotalSize(byte[] datagram) throws SizeError {
-		totalSize = BytesArrayTools.readLong(datagram, TOTAL_FILESIZE_POSITION);
+	private void setTotalSize(byte[] packet) throws SizeError {
+		totalSize = BytesArrayTools.readLong(packet, TOTAL_FILESIZE_POSITION);
 	}
 
-	/** Read filename’s size from datagram.
-	 * @param datagram	received datagram
+	/** Read filename’s size from Packet.
+	 * @param packet	received Packet
 	 * @throws	ProtocolError
 	 * @throws	SizeError
 	 * @return	filename’s size
 	 */
-	private int getFilenameSize(byte[] datagram) throws SizeError, ProtocolError {
-		int size = BytesArrayTools.readInt(datagram, FILENAME_SIZE_POSITION); // this can throw SizeError
+	private int getFilenameSize(byte[] packet) throws SizeError, ProtocolError {
+		int size = BytesArrayTools.readInt(packet, FILENAME_SIZE_POSITION); // this can throw SizeError
 		// filename size cannot be zero
 		if (size == 0) {
 			throw new ProtocolError();
 		}
-		// cannot excess datagram size
-		if ((FILENAME_POSITION + size) > (getPayloadSize(datagram) + OFFSET_POSITION)) {
+		// cannot excess packet size
+		if ((FILENAME_POSITION + size) > (getPayloadSize(packet) + OFFSET_POSITION)) {
 			throw new ProtocolError();
 		}
 		return size;
 	}
 
-	/** Write from datagram into filename.
-	 * @param datagram	received datagram
+	/** Write from Packet into filename.
+	 * @param packet	received Packet
 	 * @throws	ProtocolError
 	 * @throws	SizeError
 	 * @throws	InternalError
 	 */
-	private void setFilename(byte[] datagram) throws ProtocolError, SizeError, InternalError {
-		int filenameSize = getFilenameSize(datagram); // this can throw ProtocolError or SizeError
+	private void setFilename(byte[] packet) throws ProtocolError, SizeError, InternalError {
+		int filenameSize = getFilenameSize(packet); // this can throw ProtocolError or SizeError
 		try {
-			filename = new String(datagram, FILENAME_POSITION, filenameSize, "UTF-8");
+			filename = new String(packet, FILENAME_POSITION, filenameSize, "UTF-8");
 		} catch (UnsupportedEncodingException e) {
 			throw new InternalError();
 		}
 	}
 
-	/** Write from datagram into partialContent.
-	 * @param datagram	received datagram
+	/** Write from Packet into partialContent.
+	 * @param packet	received Packet
 	 * @throws	SizeError
 	 * @throws	ProtocolError
 	 */
-	private void setPartialContent(byte[] datagram) throws ProtocolError, SizeError {
-		int start = FILENAME_POSITION + getFilenameSize(datagram); // this can throw SizeError or ProtocolError
-		int end = OFFSET_POSITION + getPayloadSize(datagram); // this can throw SizeError
+	private void setPartialContent(byte[] packet) throws ProtocolError, SizeError {
+		int start = FILENAME_POSITION + getFilenameSize(packet); // this can throw SizeError or ProtocolError
+		int end = OFFSET_POSITION + getPayloadSize(packet); // this can throw SizeError
 		try {
-			partialContent = Arrays.copyOfRange(datagram, start, end);
+			partialContent = Arrays.copyOfRange(packet, start, end);
 		} catch (ArrayIndexOutOfBoundsException e) {
 			throw new ProtocolError();
 		}

src/protocolP2P/LoadRequest.java

@@ -18,7 +18,7 @@ public class LoadRequest extends Payload {
 	private String filename;
 	private long maxSizePartialContent;
 	private long offset;
-	static final private int OFFSET_POSITION = 8;
+	static final private int OFFSET_POSITION = PAYLOAD_START_POSITION;
 	static final private int MAX_SIZE_PARTIAL_CONTENT_POSITION = OFFSET_POSITION + 8;
 	static final private int FILENAME_SIZE_POSITION = MAX_SIZE_PARTIAL_CONTENT_POSITION + 8;
 	static final private int FILENAME_POSITION = FILENAME_SIZE_POSITION + 4;
@@ -41,74 +41,75 @@ public class LoadRequest extends Payload {
 		this.offset = offset;
 	}
 
-	/** Constructor (typically used by client) with a byte[] parameter containing the datagram received.
-	 * @param datagram	the full datagram received
+	/** Constructor (typically used by client) with a byte[] parameter containing the Packet received.
+	 * @param packet	the full Packet received
 	 * @throws	SizeError
 	 * @throws	InternalError
 	 * @throws	ProtocolError
 	 * @throws	TransmissionError
 	 */
-	protected LoadRequest(byte[] datagram) throws TransmissionError, SizeError, ProtocolError, InternalError {
-		super(datagram);
+	protected LoadRequest(byte[] packet) throws TransmissionError, SizeError, ProtocolError, InternalError {
+		super(packet);
 		/* assert to help debugging */
-		assert requestResponseCode == RequestResponseCode.LOAD_REQUEST : "LoadRequest subclass is incompatible with this datagram, request/response code must be checked before using this constructor";
+		assert requestResponseCode == RequestResponseCode.LOAD_REQUEST : "LoadRequest subclass is incompatible with this Packet, request/response code must be checked before using this constructor";
 		/* InternalErrorException */
 		if (requestResponseCode!= RequestResponseCode.LOAD_REQUEST) {
 			throw new InternalError();
 		}
 		/* Read offset */
-		offset = BytesArrayTools.readLong(datagram, OFFSET_POSITION);
+		offset = BytesArrayTools.readLong(packet, OFFSET_POSITION);
 
 		/* Read maxSizePartialContent */
-		maxSizePartialContent = BytesArrayTools.readLong(datagram, MAX_SIZE_PARTIAL_CONTENT_POSITION);
+		maxSizePartialContent = BytesArrayTools.readLong(packet, MAX_SIZE_PARTIAL_CONTENT_POSITION);
 		
 		/* Read filename */
-		int size = BytesArrayTools.readInt(datagram, FILENAME_SIZE_POSITION);
+		int size = BytesArrayTools.readInt(packet, FILENAME_SIZE_POSITION);
 		try {
-			filename = new String(datagram, FILENAME_POSITION, size, "UTF-8");
+			filename = new String(packet, FILENAME_POSITION, size, "UTF-8");
 		} catch (UnsupportedEncodingException e) {
 			throw new InternalError();
 		}
 	}
 
-	/** Returns a byte[] containing datagram with padding.
-	 * This datagram is still incomplete and should not be send directly.
-	 * ProtocolP2PDatagram will use this method to generate the complete datagram.
-	 * @return datagram with padding
+	/** Returns a byte[] containing Packet with padding.
+	 * This Packet is still incomplete and should not be send directly.
+	 * ProtocolP2PPacket will use this method to generate the complete Packet.
+	 * @return Packet with padding
 	 * @throws	InternalError
 	 */
-	protected byte[] toDatagram() throws InternalError {
+	protected byte[] toPacket() throws InternalError {
 		// compute size
 		int filenameSize = filename.length();
 		int size = FILENAME_POSITION + filenameSize;
-		byte[] datagram = new byte[size + 1]; // java initialize all to zero
+		byte[] packet = new byte[size + 1]; // java initialize all to zero
+		
 		// set request/response code
-		datagram[RequestResponseCode.RRCODE_POSITION] = requestResponseCode.codeValue;
-		// bits 16-31 are reserved for future use
-		// 8 bytes for headers
-		setPayloadSize(size - OFFSET_POSITION, datagram);
+		packet[RequestResponseCode.RRCODE_POSITION] = requestResponseCode.codeValue;
+		
+		// set Payload size
+		setPayloadSize(size - OFFSET_POSITION, packet);
 
 		// Write offset
-		BytesArrayTools.write(datagram, OFFSET_POSITION, (long)offset);
+		BytesArrayTools.write(packet, OFFSET_POSITION, (long)offset);
 
 		// Write maxSizePartialContent
-		BytesArrayTools.write(datagram, MAX_SIZE_PARTIAL_CONTENT_POSITION, (long)maxSizePartialContent);
+		BytesArrayTools.write(packet, MAX_SIZE_PARTIAL_CONTENT_POSITION, (long)maxSizePartialContent);
 
 		// Write filenameSize
-		BytesArrayTools.write(datagram, FILENAME_SIZE_POSITION, (int)filenameSize);
+		BytesArrayTools.write(packet, FILENAME_SIZE_POSITION, (int)filenameSize);
 		
 		// Write filename
 		int bCount = FILENAME_POSITION;
 		try {
 			byte[] sb = filename.getBytes("UTF-8");
 			for(byte b : sb) {
-				datagram[bCount] = b;
+				packet[bCount] = b;
 				bCount += 1;
 			}
 		} catch (UnsupportedEncodingException e) {
 			throw new InternalError();
 		}
-		return datagram;
+		return packet;
 	}
 
 	/** filename getter.

src/protocolP2P/Payload.java

@@ -32,24 +32,24 @@ public class Payload {
 		checkRequestResponseCode(); // this can throw InternalError
 	}
 
-	/** Constructor used to create a Payload (when no more specific subclasses exists) using datagram as parameter.
+	/** Constructor used to create a Payload (when no more specific subclasses exists) using packet as parameter.
 	 * If payload size is not empty, using subclass is required.
-	 * @param datagram	the full datagram received
+	 * @param packet	the full packet received
 	 * @throws	ProtocolError
 	 * @throws	InternalError
 	 * @throws	TransmissionError
 	 * @throws	SizeError
 	 */
-	protected Payload(byte[] datagram) throws SizeError, ProtocolError, InternalError, TransmissionError {
+	protected Payload(byte[] packet) throws SizeError, ProtocolError, InternalError, TransmissionError {
 		/* asserts to help debugging */
-		assert getPayloadSize(datagram) + 8 <= datagram.length : "Payload is truncated";
-		if (datagram.length < getPayloadSize(datagram) + 8) {
+		assert getPayloadSize(packet) + 8 <= packet.length : "Payload is truncated";
+		if (packet.length < getPayloadSize(packet) + 8) {
 			throw new TransmissionError();
 		}
-		assert RequestResponseCode.fromCode(datagram[RequestResponseCode.RRCODE_POSITION]) != RequestResponseCode.LIST_RESPONSE || (this instanceof FileList) : "LIST_RESPONSE must use FilePart class";
-		assert RequestResponseCode.fromCode(datagram[RequestResponseCode.RRCODE_POSITION]) != RequestResponseCode.LOAD_RESPONSE || (this instanceof FilePart) : "LOAD_RESPONSE must use FileList class";
-		assert RequestResponseCode.fromCode(datagram[RequestResponseCode.RRCODE_POSITION]) != RequestResponseCode.LOAD_REQUEST  || (this instanceof LoadRequest) : "LOAD_REQUEST must use LoadRequest class";
-		requestResponseCode = RequestResponseCode.fromCode(datagram[RequestResponseCode.RRCODE_POSITION]);
+		assert RequestResponseCode.fromCode(packet[RequestResponseCode.RRCODE_POSITION]) != RequestResponseCode.LIST_RESPONSE || (this instanceof FileList) : "LIST_RESPONSE must use FilePart class";
+		assert RequestResponseCode.fromCode(packet[RequestResponseCode.RRCODE_POSITION]) != RequestResponseCode.LOAD_RESPONSE || (this instanceof FilePart) : "LOAD_RESPONSE must use FileList class";
+		assert RequestResponseCode.fromCode(packet[RequestResponseCode.RRCODE_POSITION]) != RequestResponseCode.LOAD_REQUEST  || (this instanceof LoadRequest) : "LOAD_REQUEST must use LoadRequest class";
+		requestResponseCode = RequestResponseCode.fromCode(packet[RequestResponseCode.RRCODE_POSITION]);
 		checkRequestResponseCode(); // this can throw InternalError
 	}
 
@@ -65,29 +65,29 @@ public class Payload {
 		}
 	}
 	
-	/** Returns a byte[] containing datagram with padding.
-	 * This datagram is still incomplete and should not be send directly.
-	 * ProtocolP2PDatagram will use this method to generate the complete datagram.
-	 * @return datagram with padding
+	/** Returns a byte[] containing Packet with padding.
+	 * This Packet is still incomplete and should not be send directly.
+	 * ProtocolP2PPacket will use this method to generate the complete Packet.
+	 * @return Packet with padding
 	 * @throws	InternalError
 	 */
-	protected byte[] toDatagram() throws InternalError {
+	protected byte[] toPacket() throws InternalError {
 		// InternalError is impossible in this method on Payload class but still on subclasses
-		byte [] datagram = new byte[8]; // java initialize all to zero
+		byte [] packet = new byte[8]; // java initialize all to zero
 		// size is zero (and this is the default)
 		// set request/response code
-		datagram[RequestResponseCode.RRCODE_POSITION] = requestResponseCode.codeValue;
+		packet[RequestResponseCode.RRCODE_POSITION] = requestResponseCode.codeValue;
 		// bits 16-31 are reserved for future use
-		// payload size is 0 (this is what java have initialized datagram)
-		return datagram;
+		// payload size is 0 (this is what java have initialized Packet)
+		return packet;
 	}
 
-	/** Set payload’s size in a datagram.
+	/** Set payload’s size in a Packet.
 	 * @param size	integer representing payload size
-	 * @param datagram	datagram to be completed
+	 * @param packet	Packet to be completed
 	 * @throws	InternalError
 	 */ 
-	protected static void setPayloadSize(int size, byte[] datagram) throws InternalError {
+	protected static void setPayloadSize(int size, byte[] packet) throws InternalError {
 		/* assert to help debugging */
 		assert size >= 0: "Payload size cannot be negative";
 		if (size < 0) {
@@ -95,16 +95,16 @@ public class Payload {
 			// because this is only for reception side
 			throw new InternalError();
 		}
-		BytesArrayTools.write(datagram, PAYLOAD_SIZE_POSITION, size);
+		BytesArrayTools.write(packet, PAYLOAD_SIZE_POSITION, size);
 	}
 
-	/** Get payload’s size from a datagram.
-	 * @param datagram	the full datagram received
+	/** Get payload’s size from a Packet.
+	 * @param packet	the full Packet received
 	 * @return	integer representing payload size
 	 * @throws	SizeError
 	 */
-	protected static int getPayloadSize(byte[] datagram) throws SizeError {
-		return BytesArrayTools.readInt(datagram, PAYLOAD_SIZE_POSITION);
+	protected static int getPayloadSize(byte[] packet) throws SizeError {
+		return BytesArrayTools.readInt(packet, PAYLOAD_SIZE_POSITION);
 	}
 
 	/** RRCode getter.

src/protocolP2P/ProtocolP2PDatagram.java

@@ -1,298 +0,0 @@
-package protocolP2P;
-import exception.InternalError;
-import exception.ProtocolError;
-import exception.SizeError;
-import exception.TransmissionError;
-import exception.VersionError;
-import remoteException.EmptyDirectory;
-import remoteException.InternalRemoteError;
-import remoteException.NotFound;
-import remoteException.ProtocolRemoteError;
-import remoteException.VersionRemoteError;
-import remoteException.EmptyFile;
-import tools.BytesArrayTools;
-import protocolP2P.Payload;
-import protocolP2P.RequestResponseCode;
-import protocolP2P.LoadRequest;
-import protocolP2P.FileList;
-import protocolP2P.FilePart;
-import java.util.ArrayList;
-import java.lang.Byte;
-import java.net.DatagramPacket;
-import java.net.DatagramSocket;
-import java.net.InetAddress;
-import java.io.IOException;
-import java.net.UnknownHostException;
-
-/** Representation of datagram.
- * @author	Louis Royer
- * @author	Flavien Haas
- * @author	JS Auge
- * @version	1.0
- */
-public class ProtocolP2PDatagram {
-	private final static byte PROTOCOL_VERSION = 0x12;
-	private final static int VERSION_POSITON = 0;
-	private byte version;
-	private Payload payload;
-	private InetAddress hostR;
-	private int portR;
-	private final static int CHECKSUM_POSITION = 2;
-
-	/** Constructor with payload parameter (typically used when sending datagram).
-	 * @param payload	the payload associated with the datagram to send
-	 */
-	public ProtocolP2PDatagram(Payload payload) {
-		version = PROTOCOL_VERSION;
-		this.payload = payload;
-	}
-
-	/** Send datagram on socket (from client)
-	 * @param socket	DatagramSocket used to send datagram.
-	 * @param host	host to send datagram (null if this is a response)
-	 * @param port	port to send datagram (null if this is a response)
-	 * @throws	InternalError
-	 * @throws	UnknownHostException
-	 * @throws	IOException
-	 */
-	public void send(DatagramSocket socket, String host, int port) throws InternalError, UnknownHostException, IOException {
-		InetAddress dst = InetAddress.getByName(host);
-		byte[] datagram = toDatagram();
-		// generate DatagramPacket
-		DatagramPacket datagramPacket = new DatagramPacket(datagram, datagram.length, dst, port);
-		// send it
-		socket.send(datagramPacket);
-	}
-
-	/** Send datagram on socket (from server, as a response)
-	 * @param socket	DatagramSocket used to send datagram.
-	 * @param received	datagram to respond (aka request)
-	 * @throws	InternalError
-	 * @throws	IOException
-	 */
-	public void send(DatagramSocket socket, ProtocolP2PDatagram received) throws InternalError, IOException {
-		assert received.getPortR() != 0 && received.getHostR() != null : "This method should be used only as response to a request";
-		if (received.getPortR() == 0 || received.getHostR() == null) {
-			throw new InternalError();
-		}
-		byte[] datagram = toDatagram();
-		// generate DatagramPacket
-		DatagramPacket datagramPacket = new DatagramPacket(datagram, datagram.length, received.getHostR(), received.getPortR());
-		socket.send(datagramPacket);
-	}
-
-	/** Send a response.
-	 * @param socket	DatagramSocket used to send response
-	 * @param host	host to send response
-	 * @param port	port to send response
-	 * @throws	InternalError
-	 * @throws	IOException
-	 */
-	protected void sendResponse(DatagramSocket socket, InetAddress host, int port) throws InternalError, IOException {
-		assert port != 0 && host != null : "This method should be used only as response to a request";
-		if (port == 0 || host == null) {
-			throw new InternalError();
-		}
-		byte[] datagram = toDatagram();
-		DatagramPacket datagramPacket = new DatagramPacket(datagram, datagram.length, host, port);
-		socket.send(datagramPacket);
-	}
-
-	/** Receive datagram on socket
-	 * @param socket	DatagramSocket used to receive datagram
-	 * @throws	TransmissionError
-	 * @throws	ProtocolError
-	 * @throws	VersionError
-	 * @throws	InternalError
-	 * @throws	SizeError
-	 * @throws	ProtocolRemoteError
-	 * @throws	VersionRemoteError
-	 * @throws	InternalRemoteError
-	 * @throws	EmptyDirectory
-	 * @throws	NotFound
-	 * @throws	IOException
-	 * @throws	EmptyFile
-	 */
-	public static ProtocolP2PDatagram receive(DatagramSocket socket) throws EmptyFile, NotFound, EmptyDirectory, InternalRemoteError, VersionRemoteError, ProtocolRemoteError, TransmissionError, ProtocolError, VersionError, InternalError, SizeError, IOException {
-		// reception
-		byte[] datagram = new byte[4096*2];
-		DatagramPacket reception = new DatagramPacket(datagram, datagram.length);
-		socket.receive(reception);
-		// contruction
-		try {
-			ProtocolP2PDatagram p = new ProtocolP2PDatagram(datagram);
-			p.setHostR(reception.getAddress());
-			p.setPortR(reception.getPort());
-			Payload payload = p.getPayload();
-			switch (payload.getRequestResponseCode()) {
-				case PROTOCOL_ERROR :
-					throw new ProtocolRemoteError();
-				case VERSION_ERROR :
-					throw new VersionRemoteError();
-				case INTERNAL_ERROR :
-					throw new InternalRemoteError();
-				case EMPTY_DIRECTORY :
-					throw new EmptyDirectory();
-				case NOT_FOUND :
-					throw new NotFound();
-				case EMPTY_FILE:
-					throw new EmptyFile();
-				default :
-					return p;
-			}
-		} catch (TransmissionError e) {
-			(new ProtocolP2PDatagram(new Payload(RequestResponseCode.INTERNAL_ERROR))).sendResponse(socket, reception.getAddress(), reception.getPort());
-			throw e;
-		} catch (ProtocolError e) {
-			(new ProtocolP2PDatagram(new Payload(RequestResponseCode.PROTOCOL_ERROR))).sendResponse(socket, reception.getAddress(), reception.getPort());
-			throw e;
-		} catch (VersionError e) {
-			(new ProtocolP2PDatagram(new Payload(RequestResponseCode.VERSION_ERROR))).sendResponse(socket, reception.getAddress(), reception.getPort());
-			throw e;
-		} catch (InternalError e) {
-			(new ProtocolP2PDatagram(new Payload(RequestResponseCode.INTERNAL_ERROR))).sendResponse(socket, reception.getAddress(), reception.getPort());
-			throw e;
-		} catch (SizeError e) {
-			(new ProtocolP2PDatagram(new Payload(RequestResponseCode.INTERNAL_ERROR))).sendResponse(socket, reception.getAddress(), reception.getPort());
-			throw e;
-		}
-	}
-	/** Private constructor with datagram as byte[] parameter (typically used when receiving datagram).
-	 * @param datagram	the full datagram received
-	 * @throws	TransmissionError
-	 * @throws	ProtocolError
-	 * @throws	VersionError
-	 * @throws	InternalError
-	 * @throws	SizeError
-	 */
-	private ProtocolP2PDatagram(byte[] datagram) throws TransmissionError, ProtocolError, VersionError, InternalError, SizeError {
-		// unwrap version
-		version = datagram[VERSION_POSITON];
-		checkProtocolVersion(); // this can throw VersionError
-		checkCheckSum(datagram);
-		RequestResponseCode r = RequestResponseCode.fromCode(datagram[RequestResponseCode.RRCODE_POSITION]); // this can throw ProtocolError
-		switch (r) {
-			case LIST_RESPONSE:
-				payload = (Payload) new FileList(datagram);
-				break;
-			case LOAD_RESPONSE:
-				payload = (Payload) new FilePart(datagram);
-				break;
-			case LOAD_REQUEST:
-				payload = (Payload) new LoadRequest(datagram);
-				break;
-			default:
-				payload = new Payload(datagram); // this can throw TransmissionError
-				break;
-			}
-	}
-
-	/** Returns a byte[] containing full datagram (typically used when sending datagram).
-	 * This datagram is still complete and ready to be send.
-	 * @return the full datagram to send
-	 * @throws	InternalError
-	 */
-	protected byte[] toDatagram() throws InternalError {
-		byte[] datagram = payload.toDatagram();
-		datagram[VERSION_POSITON] = version;
-		setCheckSum(datagram);
-		return datagram;
-	}
-
-	/** Returns Payload associated with the datagram.
-	 * @return	payload associated with the datagram
-	 */
-	public Payload getPayload() {
-		return payload;
-	}
-
-	/** Used to check protocol version when a datagram is constructed from bytes[].
-	 * @throws	VersionError
-	 */
-	private void checkProtocolVersion() throws VersionError {
-		if (PROTOCOL_VERSION != version) {
-			throw new VersionError();
-		}
-	}
-
-	/** portR getter.
-	 * @return	portR
-	 */
-	protected int getPortR() {
-		return portR;
-	}
-
-	/** portR setter.
-	 * @param portR	portR
-	 */
-	 protected void setPortR(int portR) {
-		 this.portR = portR;
-	 }
-
-	/** hostR getter.
-	 * @return	hostR
-	 */
-	protected InetAddress getHostR() {
-		return hostR;
-	}
-
-	/** hostH setter.
-	 * @param hostR	hostR
-	 */
-	protected void setHostR(InetAddress hostR) {
-		this.hostR = hostR;
-	}
-
-	/** Used to compute Checksum of a specific datagram
-	* @param datagram full datagram
-	* @return checksum
-	* @throws SizeError
-	*/
-
-	private int computeCheckSum(byte [] datagram) throws SizeError {
-		/*
-		* The checksum field is the 16 bit one’s complement of the one’s complement sum of all 16-bit words
-		* in the header and text. If a segment contains an odd number of header and text octets to be checksummed,
-		* the last octet is padded on the right with zeros to form a 16-bit word for checksum purposes.
-		* The pad is not transmitted as part of the segment. While computing the checksum, the checksum field
-		* itself is replaced with zeros.
-		*/
-		int checksum = 0;
-		for (int i=CHECKSUM_POSITION+2; i<CHECKSUM_POSITION+2+4+Payload.getPayloadSize(datagram); ++i) {
-			checksum += BytesArrayTools.readInt16Bits(datagram,i);
-			checksum &= 0xffff;
-		}
-		return checksum ^ 0xffff;
-	}
-
-	/** Used to set checksum into datagram
-	* @param datagram full datagram
-	* @throws InternalError
-	*/
-
-	private void setCheckSum(byte [] datagram) throws InternalError {
-		try {
-			int checksum = computeCheckSum(datagram);
-			BytesArrayTools.write16Bits(datagram,CHECKSUM_POSITION,checksum);
-		} catch (SizeError e) {
-			throw new InternalError();
-		}
-	}
-
-	/** Used to check if the checksum is correct
-	* @param datagram full datagram
-	* @throws TransmissionError
-	*/
-
-	private void checkCheckSum(byte [] datagram) throws TransmissionError {
-		try {
-			int checksum = BytesArrayTools.readInt16Bits(datagram,CHECKSUM_POSITION);
-			int computedCheckSum = computeCheckSum(datagram);
-			if (computedCheckSum != checksum){
-				throw new TransmissionError();
-			}
-		} catch(SizeError e) {
-			throw new TransmissionError();
-		}
-	}
-}

src/protocolP2P/ProtocolP2PPacket.java

@@ -0,0 +1,102 @@
+package protocolP2P;
+import exception.InternalError;
+import exception.ProtocolError;
+import exception.SizeError;
+import exception.TransmissionError;
+import exception.VersionError;
+import remoteException.EmptyDirectory;
+import remoteException.InternalRemoteError;
+import remoteException.NotFound;
+import remoteException.ProtocolRemoteError;
+import remoteException.VersionRemoteError;
+import remoteException.EmptyFile;
+import java.net.InetAddress;
+import java.io.IOException;
+
+/** Representation of packet.
+ * @author	Louis Royer
+ * @author	Flavien Haas
+ * @author	JS Auge
+ * @version	1.0
+ */
+public abstract class ProtocolP2PPacket {
+	private final static byte PROTOCOL_VERSION = 0x12;
+	protected final static int VERSION_POSITION = 0;
+	protected byte version;
+	protected Payload payload;
+
+	/** Constructor with payload parameter (typically used when sending Packet).
+	 * @param payload	the payload associated with the Packet to send
+	 */
+	public ProtocolP2PPacket(Payload payload) {
+		version = PROTOCOL_VERSION;
+		this.payload = payload;
+	}
+
+	/** Send a request
+	 * @param socket	Socket used to send packet.
+	 * @throws	InternalError
+	 * @throws	IOException
+	 */
+	public abstract void sendRequest(Object socket) throws InternalError, IOException;
+
+	/** Send a response
+	 * @param response	Response to send.
+	 * @throws	InternalError
+	 * @throws	IOException
+	 */
+	public abstract void sendResponse(ProtocolP2PPacket response) throws InternalError, IOException;
+
+	/** Receive a response
+	 * @throws	EmptyFile
+	 * @throws	NotFound
+	 * @throws	EmptyDirectory
+	 * @throws	InternalRemoteError
+	 * @throws	VersionRemoteError
+	 * @throws	ProtocolRemoteError
+	 * @throws	TransmissionError
+	 * @throws	ProtocolError
+	 * @throws	VersionError
+	 * @throws	InternalError
+	 * @throws	SizeError
+	 * @throws	IOException
+	 */
+	public abstract ProtocolP2PPacket receiveResponse() throws EmptyFile, NotFound, EmptyDirectory, InternalRemoteError, VersionRemoteError, ProtocolRemoteError, TransmissionError, ProtocolError, VersionError, InternalError, SizeError, IOException;
+
+	/** Receive a request, subclasses must overwrite this constructor.
+	 * @param serverSocket	socket used to get the request
+	 * @throws	TransmissionError
+	 * @throws	ProtocolError
+	 * @throws	VersionError
+	 * @throws	InternalError
+	 * @throws	SizeError
+	 * @throws	IOException
+	 */
+	protected ProtocolP2PPacket(Object serverSocket) throws TransmissionError, ProtocolError, VersionError, InternalError, SizeError, IOException {}
+
+	/** Construct a packet from byte[], subclasses must overwrite this constructor.
+	 * @param packet	Packet received
+	 * @throws	TransmissionError
+	 * @throws	ProtocolError
+	 * @throws	VersionError
+	 * @throws	InternalError
+	 * @throws	SizeError
+	 */
+	protected ProtocolP2PPacket(byte[] packet) throws TransmissionError, ProtocolError, VersionError, InternalError, SizeError {}
+	
+	/** Returns Payload associated with the Packet.
+	 * @return	payload associated with the Packet.
+	 */
+	public Payload getPayload() {
+		return payload;
+	}
+
+	/** Used to check protocol version when a Packet is constructed from bytes[].
+	 * @throws	VersionError
+	 */
+	protected void checkProtocolVersion() throws VersionError {
+		if (PROTOCOL_VERSION != version) {
+			throw new VersionError();
+		}
+	}
+}

src/protocolP2P/ProtocolP2PPacketUDP.java

@@ -0,0 +1,359 @@
+package protocolP2P;
+import exception.InternalError;
+import exception.ProtocolError;
+import exception.SizeError;
+import exception.TransmissionError;
+import exception.VersionError;
+import remoteException.EmptyDirectory;
+import remoteException.InternalRemoteError;
+import remoteException.NotFound;
+import remoteException.ProtocolRemoteError;
+import remoteException.VersionRemoteError;
+import remoteException.EmptyFile;
+import tools.BytesArrayTools;
+import protocolP2P.Payload;
+import protocolP2P.RequestResponseCode;
+import protocolP2P.LoadRequest;
+import protocolP2P.FileList;
+import protocolP2P.FilePart;
+import java.util.ArrayList;
+import java.lang.Byte;
+import java.net.DatagramPacket;
+import java.net.DatagramSocket;
+import java.net.SocketAddress;
+import java.io.IOException;
+
+/** Representation of packet.
+ * @author	Louis Royer
+ * @author	Flavien Haas
+ * @author	JS Auge
+ * @version	1.0
+ */
+public class ProtocolP2PPacketUDP extends ProtocolP2PPacket {
+	
+	private final static int CHECKSUM_POSITION = 2;
+	private SocketAddress responseSocketAddress; // socket address used when receptionning request and to sending response
+	private DatagramSocket responseSocket; // socket used to recept request and send response
+	private DatagramSocket requestSocket; // socket used to send request and to reception response
+	
+	/** Constructor with payload parameter (typically used when sending packet).
+	 * @param payload	the payload associated with the packet to send
+	 */
+	public ProtocolP2PPacketUDP(Payload payload) {
+		super(payload);
+	}
+
+	/** Send a Packet. Socket must be set and connected.
+	 * @param socket	DatagramSocket used to send Packet.
+	 * @throws	InternalError
+	 * @throws	IOException
+	 */
+	protected void send(DatagramSocket socket) throws InternalError, IOException {
+		send(socket, null);
+	}
+
+	/** Send a Packet. Socket must be set and connected, or an addr can be given.
+	 * @param socket	DatagramSocket used to send Packet.
+	 * @param addr	SocketAddress used to send Packet.
+	 * @throws	InternalError
+	 * @throws	IOException
+	 */
+	protected void send(DatagramSocket socket, SocketAddress addr) throws InternalError, IOException {
+		assert socket != null : "Trying to send a Packet but no socket defined";
+		assert socket.isConnected() || addr != null : "Trying to send a Packet but socket not connected, and no socketAddress given";
+		if (socket == null || ((!socket.isConnected()) && (addr == null))) {
+			throw new InternalError();
+		}
+		// generate DatagramPacket
+		byte[] packet = toPacket();
+		DatagramPacket datagramPacket = new DatagramPacket(packet, packet.length);
+		if (addr != null) {
+			datagramPacket.setSocketAddress(addr);
+		}
+		// send it
+		socket.send(datagramPacket);
+	}
+
+	/** Send a Request throught socket. Socket must be connected (typically used from client).
+	 * @param socket	DatagramSocket. Must be connected.
+	 * @throws	InternalError
+	 * @throws	IOException
+	 */
+	public void sendRequest(Object socket) throws InternalError, IOException {
+		assert socket instanceof DatagramSocket: "Wrong socket type";
+		if (socket instanceof DatagramSocket) {
+			requestSocket = (DatagramSocket)socket;
+			send(requestSocket);
+		} else {
+			throw new InternalError();
+		}
+	}
+
+	/** Receive Request (typically used from server).
+	 * @param serverSocket	socket used to receive request
+	 * @throws	TransmissionError
+	 * @throws	ProtocolError
+	 * @throws	VersionError
+	 * @throws	InternalError
+	 * @throws	SizeError
+	 * @throws	IOException
+	 * @return	ProtocolP2PPacket received.
+	 */
+	public ProtocolP2PPacketUDP(Object serverSocket) throws TransmissionError, ProtocolError, VersionError, InternalError, SizeError, IOException {
+		super(serverSocket);
+		assert serverSocket instanceof DatagramSocket : "Wrong socket type";
+		if (!(serverSocket instanceof DatagramSocket)) {
+			throw new InternalError();
+		}
+		DatagramSocket ss = (DatagramSocket)serverSocket;
+		byte[] packet = new byte[1024];
+		DatagramPacket reception = new DatagramPacket(packet, packet.length);
+		ss.receive(reception);
+		responseSocketAddress = reception.getSocketAddress();
+		// contruction
+		boolean protocolError = false;
+		try {
+			constructPacket(packet, ss);
+			Payload payload = getPayload();
+			switch (payload.getRequestResponseCode()) {
+				case PROTOCOL_ERROR :
+					// we do not want to create an infinite loop of protocolError message exchange.
+					protocolError = true;
+					break;
+				case VERSION_ERROR :
+				case INTERNAL_ERROR :
+				case EMPTY_DIRECTORY :
+				case NOT_FOUND :
+				case EMPTY_FILE:
+				case LOAD_RESPONSE:
+				case LIST_RESPONSE:
+					// we were expecting a request, but we are receiving a response
+					throw new ProtocolError();
+				default :
+					break;
+			}
+		} catch (TransmissionError e) {
+			(new ProtocolP2PPacketUDP(new Payload(RequestResponseCode.INTERNAL_ERROR))).send(ss, responseSocketAddress);
+			throw e;
+		} catch (ProtocolError e) {
+			(new ProtocolP2PPacketUDP(new Payload(RequestResponseCode.PROTOCOL_ERROR))).send(ss, responseSocketAddress);
+			throw e;
+		} catch (VersionError e) {
+			(new ProtocolP2PPacketUDP(new Payload(RequestResponseCode.VERSION_ERROR))).send(ss, responseSocketAddress);
+			throw e;
+		} catch (InternalError e) {
+			(new ProtocolP2PPacketUDP(new Payload(RequestResponseCode.INTERNAL_ERROR))).send(ss, responseSocketAddress);
+			throw e;
+		} catch (SizeError e) {
+			(new ProtocolP2PPacketUDP(new Payload(RequestResponseCode.INTERNAL_ERROR))).send(ss, responseSocketAddress);
+			throw e;
+		}
+		if (protocolError) {
+			throw new ProtocolError();
+		}
+	}
+
+	/** Send a Response to a Request (typically used from server).
+	 * @param response	Packet to send as a response.
+	 * @throws	InternalError
+	 * @throws	IOException
+	 */
+	public void sendResponse(ProtocolP2PPacket response) throws InternalError, IOException {
+		assert response instanceof ProtocolP2PPacketUDP: "Wrong Packet type";
+		if (response instanceof ProtocolP2PPacketUDP) {
+			ProtocolP2PPacketUDP r = (ProtocolP2PPacketUDP) response;
+			assert responseSocket != null : "Cannot send response to a packet not received";
+			if (responseSocket == null) {
+				throw new InternalError();
+			}
+			assert responseSocketAddress != null : "Cannot send response because address of client has not been saved";
+			if (responseSocketAddress == null) {
+				throw new InternalError();
+			}
+			r.send(responseSocket, responseSocketAddress);
+		} else {
+			throw new InternalError();
+		}
+	}
+
+	/** Receive response (typically used by client).
+	 * @return	ProtocolP2PPacket received
+	 * @throws	EmptyFile
+	 * @throws	NotFound
+	 * @throws	EmptyDirectory
+	 * @throws	InternalRemoteError
+	 * @throws	VersionRemoteError
+	 * @throws	ProtocolRemoteError
+	 * @throws	TransmissionError
+	 * @throws	ProtocolError
+	 * @throws	VersionError
+	 * @throws	InternalError
+	 * @throws	SizeError
+	 * @throws	IOException
+	 */
+	public ProtocolP2PPacket receiveResponse() throws EmptyFile, NotFound, EmptyDirectory, InternalRemoteError, VersionRemoteError, ProtocolRemoteError, TransmissionError, ProtocolError, VersionError, InternalError, SizeError, IOException {
+		assert requestSocket != null : "Cannot receive response because request packet not sent.";
+		if (requestSocket == null) {
+			throw new InternalError();
+		}
+		// reception
+		byte[] packet = new byte[8192];
+		DatagramPacket reception = new DatagramPacket(packet, packet.length);
+		requestSocket.receive(reception);
+		// contruction
+		try {
+			ProtocolP2PPacketUDP p = new ProtocolP2PPacketUDP(packet);
+			Payload payload = p.getPayload();
+			switch (payload.getRequestResponseCode()) {
+				case PROTOCOL_ERROR :
+					throw new ProtocolRemoteError();
+				case VERSION_ERROR :
+					throw new VersionRemoteError();
+				case INTERNAL_ERROR :
+					throw new InternalRemoteError();
+				case EMPTY_DIRECTORY :
+					throw new EmptyDirectory();
+				case NOT_FOUND :
+					throw new NotFound();
+				case EMPTY_FILE:
+					throw new EmptyFile();
+				default :
+					return (ProtocolP2PPacket)p;
+			}
+		} catch (TransmissionError e) {
+			(new ProtocolP2PPacketUDP(new Payload(RequestResponseCode.INTERNAL_ERROR))).send(requestSocket);
+			throw e;
+		} catch (ProtocolError e) {
+			(new ProtocolP2PPacketUDP(new Payload(RequestResponseCode.PROTOCOL_ERROR))).send(requestSocket);
+			throw e;
+		} catch (VersionError e) {
+			(new ProtocolP2PPacketUDP(new Payload(RequestResponseCode.VERSION_ERROR))).send(requestSocket);
+			throw e;
+		} catch (InternalError e) {
+			(new ProtocolP2PPacketUDP(new Payload(RequestResponseCode.INTERNAL_ERROR))).send(requestSocket);
+			throw e;
+		} catch (SizeError e) {
+			(new ProtocolP2PPacketUDP(new Payload(RequestResponseCode.INTERNAL_ERROR))).send(requestSocket);
+			throw e;
+		}
+	}
+
+	/** Private constructor with packet as byte[] parameter (typically used when receiving Packet response).
+	 * @param packet	the full Packet received
+	 * @throws	TransmissionError
+	 * @throws	ProtocolError
+	 * @throws	VersionError
+	 * @throws	InternalError
+	 * @throws	SizeError
+	 */
+	private ProtocolP2PPacketUDP(byte[] packet) throws TransmissionError, ProtocolError, VersionError, InternalError, SizeError {
+		super(packet);
+		constructPacket(packet);
+	}
+
+	/** Private constructor helper with packet as byte[] parameter (typically used when receiving Packet response/request).
+	 * @param packet	the full Packet received
+	 * @throws	TransmissionError
+	 * @throws	ProtocolError
+	 * @throws	VersionError
+	 * @throws	InternalError
+	 * @throws	SizeError
+	 */
+	private void constructPacket(byte[] packet) throws TransmissionError, ProtocolError, VersionError, InternalError, SizeError {
+		// unwrap version
+		version = packet[VERSION_POSITION];
+		checkProtocolVersion(); // this can throw VersionError
+		checkCheckSum(packet);
+		RequestResponseCode r = RequestResponseCode.fromCode(packet[RequestResponseCode.RRCODE_POSITION]); // this can throw ProtocolError
+		switch (r) {
+			case LIST_RESPONSE:
+				payload = (Payload) new FileList(packet);
+				break;
+			case LOAD_RESPONSE:
+				payload = (Payload) new FilePart(packet);
+				break;
+			case LOAD_REQUEST:
+				payload = (Payload) new LoadRequest(packet);
+				break;
+			default:
+				payload = new Payload(packet); // this can throw TransmissionError
+				break;
+		}
+	}
+
+	/** Private constructor helper with packet as byte[] parameter and (typically used when receiving Packet request).
+	 * @param packet	the full Packet received
+	 * @param responseSocket	socket address used to reception this request (use this one to respond)
+	 * @throws	TransmissionError
+	 * @throws	ProtocolError
+	 * @throws	VersionError
+	 * @throws	InternalError
+	 * @throws	SizeError
+	 */
+	private void constructPacket(byte[] packet, DatagramSocket responseSocket) throws TransmissionError, ProtocolError, VersionError, InternalError, SizeError {
+		constructPacket(packet);
+		this.responseSocket = responseSocket;
+	}
+
+	/** Returns a byte[] containing full packet (typically used when sending packet).
+	 * This packet is complete and ready to be send.
+	 * @return the full packet to send
+	 * @throws	InternalError
+	 */
+	protected byte[] toPacket() throws InternalError {
+		byte[] packet = payload.toPacket();
+		packet[VERSION_POSITION] = version;
+		setCheckSum(packet);
+		return packet;
+	}
+
+	/** Compute checksum associated to packet.
+	 * @param packet	the full packet received
+	 * @throws	SizeError
+	 */
+	private int computeCheckSum(byte [] packet) throws SizeError {
+		/*
+		* The checksum field is the 16 bit one’s complement of the one’s complement sum of all 16-bit words
+		* in the header and text. If a segment contains an odd number of header and text octets to be checksummed,
+		* the last octet is padded on the right with zeros to form a 16-bit word for checksum purposes.
+		* The pad is not transmitted as part of the segment. While computing the checksum, the checksum field
+		* itself is replaced with zeros.
+		*/
+		int checksum = 0;
+		for (int i=CHECKSUM_POSITION+2; i<CHECKSUM_POSITION+2+4+Payload.getPayloadSize(packet); ++i) {
+			checksum += BytesArrayTools.readInt16Bits(packet, i);
+			checksum &= 0xffff;
+		}
+		return checksum ^ 0xffff;
+	}
+
+	/** Used to set checksum into packet
+	* @param packet	full packet
+	* @throws InternalError
+	*/
+	private void setCheckSum(byte [] packet) throws InternalError {
+		try {
+			int checksum = computeCheckSum(packet);
+			BytesArrayTools.write16Bits(packet, CHECKSUM_POSITION, checksum);
+		} catch (SizeError e) {
+			throw new InternalError();
+		}
+	}
+
+	/** Used to check if the checksum is correct
+	* @param packet	full packet
+	* @throws TransmissionError
+	*/
+
+	private void checkCheckSum(byte [] packet) throws TransmissionError {
+		try {
+			int checksum = BytesArrayTools.readInt16Bits(packet, CHECKSUM_POSITION);
+			int computedCheckSum = computeCheckSum(packet);
+			if (computedCheckSum != checksum){
+				throw new TransmissionError();
+			}
+		} catch(SizeError e) {
+			throw new TransmissionError();
+		}
+	}
+}

src/protocolP2P/RequestResponseCode.java

@@ -39,7 +39,7 @@ public enum RequestResponseCode {
 
 	/** Private constructor
 	 * @param codeType	type of code (request or response)
-	 * @param codeValue	value of the element in datagram
+	 * @param codeValue	value of the element in Packet
 	 * @return	enum element
 	 */
 	private RequestResponseCode(CodeType codeType, byte codeValue) {
@@ -47,8 +47,8 @@ public enum RequestResponseCode {
 		this.codeValue = codeValue;
 	}
 
-	/** Gives enum from datagram code.
-	 * @param code	value of the element in datagram
+	/** Gives enum from Packet code.
+	 * @param code	value of the element in packet
 	 * @return enum element
 	 */
 	protected static RequestResponseCode fromCode(byte code) throws ProtocolError {

src/serverP2P/ServerManagementUDP.java

@@ -3,10 +3,12 @@ import java.util.Vector;
 import java.io.File;
 import java.io.IOException;
 import java.net.DatagramSocket;
+import java.net.InetAddress;
 import java.net.SocketException;
 import java.nio.file.Paths;
 import java.nio.file.Files;
-import protocolP2P.ProtocolP2PDatagram;
+import protocolP2P.ProtocolP2PPacketUDP;
+import protocolP2P.ProtocolP2PPacket;
 import protocolP2P.RequestResponseCode;
 import protocolP2P.Payload;
 import protocolP2P.LoadRequest;
@@ -60,7 +62,7 @@ public class ServerManagementUDP implements Runnable {
 	public void run() {
 		while(true) {
 			try {
-				ProtocolP2PDatagram pd = ProtocolP2PDatagram.receive(socket);
+				ProtocolP2PPacketUDP pd = new ProtocolP2PPacketUDP((Object)socket);
 				Payload p = pd.getPayload();
 				switch (p.getRequestResponseCode()) {
 					case LOAD_REQUEST:
@@ -87,9 +89,9 @@ public class ServerManagementUDP implements Runnable {
 								if (Arrays.binarySearch(fileList, filename) >= 0) {
 									try {
 										if (load.length == 0) {
-											(new ProtocolP2PDatagram(new Payload(RequestResponseCode.EMPTY_FILE))).send(socket, pd);
+											pd.sendResponse((ProtocolP2PPacket)new ProtocolP2PPacketUDP(new Payload(RequestResponseCode.EMPTY_FILE)));
 										} else {
-											(new ProtocolP2PDatagram((Payload)(new FilePart(filename, fullLoad.length, offset, load)))).send(socket, pd);
+											pd.sendResponse((ProtocolP2PPacket)new ProtocolP2PPacketUDP((Payload)(new FilePart(filename, fullLoad.length, offset, load))));
 										}
 									} catch (Exception e2) {
 										System.err.println(e2);
@@ -105,7 +107,7 @@ public class ServerManagementUDP implements Runnable {
 								}
 							} catch (IOException e) {
 								try {
-									(new ProtocolP2PDatagram(new Payload(RequestResponseCode.NOT_FOUND))).send(socket, pd);
+									pd.sendResponse((ProtocolP2PPacket)new ProtocolP2PPacketUDP(new Payload(RequestResponseCode.NOT_FOUND)));
 								} catch (Exception e2) {
 									System.err.println(e2);
 								}
@@ -117,10 +119,10 @@ public class ServerManagementUDP implements Runnable {
 						try {
 							if (fileList.length == 0) {
 								System.err.println("Sending EMPTY_DIRECTORY");
-								(new ProtocolP2PDatagram(new Payload(RequestResponseCode.EMPTY_DIRECTORY))).send(socket, pd);
+								pd.sendResponse((ProtocolP2PPacket)new ProtocolP2PPacketUDP(new Payload(RequestResponseCode.EMPTY_DIRECTORY)));
 							} else {
 								System.out.println("Sending LIST_RESPONSE");
-								(new ProtocolP2PDatagram((Payload)(new FileList(fileList)))).send(socket, pd);
+								pd.sendResponse((ProtocolP2PPacket)new ProtocolP2PPacketUDP((Payload)(new FileList(fileList))));
 							}
 						} catch (Exception e2) {
 							System.err.println(e2);
@@ -129,18 +131,12 @@ public class ServerManagementUDP implements Runnable {
 					default:
 						sendInternalError(pd);
 				}
-			} catch (NotFound e) {
-			} catch (EmptyDirectory e) {
-			} catch (InternalRemoteError e) {
-			} catch (VersionRemoteError e) {
-			} catch (ProtocolRemoteError e) {
 			} catch (IOException e) {
 			} catch (TransmissionError e) {
 			} catch (ProtocolError e) {
 			} catch (VersionError e) {
 			} catch (InternalError e) {
 			} catch (SizeError e) {
-			} catch (EmptyFile e) {
 			}
 		}
 	}
@@ -165,11 +161,11 @@ public class ServerManagementUDP implements Runnable {
 
 	
 	/** Send an internal error message.
-	 * @param pd	ProtocolP2PDatagram to respond
+	 * @param pd	ProtocolP2PPacketUDP to respond
 	 */
-	private void sendInternalError(ProtocolP2PDatagram pd) {
+	private void sendInternalError(ProtocolP2PPacketUDP pd) {
 		try {
-			(new ProtocolP2PDatagram(new Payload(RequestResponseCode.INTERNAL_ERROR))).send(socket, pd);
+			pd.sendResponse((ProtocolP2PPacket)new ProtocolP2PPacketUDP(new Payload(RequestResponseCode.INTERNAL_ERROR)));
 		} catch (Exception e) {
 			System.err.println(e);
 		}