Implement ServerManagement and ClientManagement

src/clientP2P/ClientManagementUDP.java

@@ -1,18 +1,30 @@
 package clientP2P;
-import exception.NotFound;
-import exception.ProtocolError;
 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 java.net.UnknownHostException;
 import java.util.Scanner;
 import java.net.InetAddress;
-import java.net.DatagramPacket;
 import java.net.DatagramSocket;
-import java.io.File;
+import java.net.SocketException;
 import java.io.IOException;
-import java.io.FileWriter;
+import java.nio.file.Files;
+import java.io.File;
+import protocolP2P.ProtocolP2PDatagram;
+import protocolP2P.Payload;
+import protocolP2P.RequestResponseCode;
+import protocolP2P.FileList;
+import protocolP2P.FilePart;
+import protocolP2P.LoadRequest;
 
-
-/** Implementation of P2P-JAVA-PROJECT VERSION 1.0 protocol for UDP.
+/** Implementation of P2P-JAVA-PROJECT CLIENT
  * @author	Louis Royer
  * @author	Flavien Haas
  * @author	JS Auge
@@ -22,142 +34,139 @@ public class ClientManagementUDP implements Runnable {
 	private String baseDirectory;
 	private int UDPPort;
 	private String host;
-	private final String protocolID = "P2P-JAVA-PROJECT VERSION 1.0";
+	private DatagramSocket socket;
+
 
 
 	/** Constructor for UDP implementation, with baseDirectory and UDPPort parameters.
 	 * @param baseDirectory	the root directory where files are stored
+	 * @param host	hostname of the server
 	 * @param UDPPort	the server will listen on this port
 	 */
 	public ClientManagementUDP(String baseDirectory, String host, int UDPPort) {
 		this.baseDirectory = baseDirectory;
 		this.host = host;
 		this.UDPPort = UDPPort;
+		try {
+			socket = new DatagramSocket();
+		} catch (SocketException e) {
+			System.err.println("Error: No socket available.");
+			System.exit(-1);
+		}
 	}
 
 	/** Implementation of Runnable
 	 */
 	public void run() {
-		System.out.println("Files present on the server:");
 		try {
-			String msg = sendMsg(sendListDirectoryRequest());
-			System.out.println(listDirectory(msg));
+			String[] list = listDirectory();
+			System.out.println("Files present on the server:");
+			for(String listItem: list) {
+				System.out.println(listItem);
+			}
 			System.out.println("Name of the file to download:");
 			Scanner scanner = new Scanner(System.in);
 			String f = scanner.nextLine();
-			msg = sendMsg(sendDownloadRequest(f));
-			download(msg, f);
-		} catch (TransmissionError e) {
-			System.out.println("Transmission error");
-		} catch (ProtocolError e) {
-			System.out.println("Protocol error");
-		} catch (NotFound e) {
-			System.out.println("File not found");
+			download(f);
+			System.out.println("File sucessfully downloaded");
+		} catch (EmptyDirectory e) {
+			System.err.println("Error: Server has no file in directory");
 		} catch (InternalError e) {
-			System.out.println("Server internal error");
+			System.err.println("Error: Client internal error");
+		} catch (UnknownHostException e) {
+			System.err.println("Error: Server host is unknown");
 		} catch (IOException e) {
-			System.out.println("Cannot write to file");
+			System.err.println("Error: Request cannot be send or response cannot be received");
+		} catch (TransmissionError e) {
+			System.err.println("Error: Message received is too big");
+		} catch (ProtocolError e) {
+			System.err.println("Error: Cannot decode server’s response");
+		} catch (VersionError e) {
+			System.err.println("Error: Server’s response use bad version of the protocol");
+		} catch (SizeError e) {
+			System.err.println("Error: Cannot handle this packets because of internal representation limitations of numbers on the client");
+		} catch (InternalRemoteError e) {
+			System.err.println("Error: Server internal error");
+		} catch (ProtocolRemoteError e) {
+			System.err.println("Error: Server cannot decode client’s request");
+		} catch (VersionRemoteError e) {
+			System.err.println("Error: Server cannot decode this version of the protocol");
+		} catch (NotFound e) {
+			System.err.println("Error: Server have not this file in directory");
 		}
 	}
 
-	/** Prepare request to download file
-	 * @param filename	name of the file to be downloaded
-	 * @return	request to be send
-	 */
-	private String sendDownloadRequest(String filename) {
-		return protocolID + "\nDOWNLOAD\n" + filename + "\n";
-	}
-
-	/** Download file.
-	 * @param response	Servers's response
-	 * @throws NotFound
-	 * @throws ProtocolError
-	 * @throws InternalError
-	 */
-	private void download(String response, String filename) throws TransmissionError, NotFound, ProtocolError, InternalError, IOException {
-		try {
-			String r[] = response.split("\n");
-			checkProtocolID(r[0]);
-			switch (r[1]) {
-			case "LOAD":
-				int size = Integer.parseInt(r[2]);
-				if (r[3].length() != size - 1) {
-					throw new TransmissionError();
-				}
-				FileWriter fileWriter = new FileWriter(baseDirectory + filename);
-				fileWriter.write(r[3]);
-				fileWriter.close();
-				break;
-			case "NOT FOUND":
-				throw new NotFound();
-			case "INTERNAL ERROR":
-				throw new InternalError();
-			default:
-				System.out.println("Error: Unknow format `" + r[1] + "`");
-				throw new ProtocolError();
-			}
-		} catch (java.lang.ArrayIndexOutOfBoundsException e) {
-			System.out.println("Error: IndexOutOfBonds");
-			throw new ProtocolError();
-		} catch (NumberFormatException e) {
-			System.out.println("Error: NumberFormat");
-			throw new ProtocolError();
-		}
-	}
-
-	/** Prepare request to list files on server
-	 * @return	request to be send
-	 */
-	private String sendListDirectoryRequest() {
-		return protocolID + "\nLIST\n";
-	}
-
-	/** Parse list of directory response from server
-	 * @param response	server's response
-	 * @return	list of files, separated by CRLF
-	 * @throws ProtocolError
-	 */
-	private String listDirectory(String response) throws ProtocolError {
-		try {
-			String r[] = response.split("\n");
-			checkProtocolID(r[0]);
-			return response.split(protocolID + "\nLIST\n")[1].split("\n\n")[0];
-		} catch (java.lang.ArrayIndexOutOfBoundsException e) {
-			throw new ProtocolError();
-		}
-	}
-
-	/** Check client's protocol identifier matches message's protocol identifier.
-	 * Throws a ProtocolError if mismatched.
-	 * @param msgProtocolID	part of the request containing protocol identifier
+	/** Try to download a file
+	 * @param filename	name of the file to download
+	 * @throws	NotFound
+	 * @throws	InternalError
+	 * @throws	UnknownHostException
+	 * @throws	IOException
+	 * @throws	TransmissionError
 	 * @throws	ProtocolError
+	 * @throws	VersionError
+	 * @throws	SizeError
+	 * @throws	InternalRemoteError
+	 * @throws	ProtocolRemoteError
+	 * @throws	VersionRemoteError
 	 */
-	private void checkProtocolID(String msgProtocolID) throws ProtocolError {
-		if (!protocolID.equals(msgProtocolID)) {
-			throw new ProtocolError();
-		}
+	private void download(String filename) throws NotFound, InternalError, UnknownHostException, IOException, TransmissionError, ProtocolError, VersionError, SizeError, InternalRemoteError, ProtocolRemoteError, VersionRemoteError {
+		ProtocolP2PDatagram d = new ProtocolP2PDatagram((Payload) new LoadRequest(filename));
+		d.send(socket, host, UDPPort);
+		try {
+			Payload p = ProtocolP2PDatagram.receive(socket).getPayload();
+			assert p instanceof FilePart : "This payload must be instance of FilePart";
+			if (!(p instanceof FilePart)) {
+				throw new InternalError();
+			} else {
+				FilePart fp = (FilePart)p;
+				if (!fp.getFilename().equals(filename)) {
+					System.err.println("Error: wrong file received");
+					throw new ProtocolError();
+				}
+				if (fp.getOffset() != 0 || fp.getPartialContent().length != fp.getTotalSize()) {
+					System.err.println("Error: cannot handle partial files (not implemented)");
+					throw new InternalError();
+				}
+				try {
+					Files.write(new File(baseDirectory + filename).toPath(), fp.getPartialContent());
+				} catch (IOException e) {
+					System.err.println("Error: cannot write file (" + baseDirectory + filename + ")");
+				}
+			}
+		} catch (EmptyDirectory e) {
+		throw new ProtocolError();
 	}
 
-	/** Send message to server
-	 * @param msg	message to be send
-	 * @return	server's response
-	 */
-	private String sendMsg(String msg) throws TransmissionError {
-		//TODO changer le gros try catch
-		try{
-			InetAddress dst = InetAddress.getByName(host);
-			byte [] buffer = msg.getBytes();
-			byte [] buffer2 = new byte[1500];
-			DatagramSocket socket = new DatagramSocket();
-			DatagramPacket reception = new DatagramPacket(buffer2, 1500);
-			DatagramPacket emission = new DatagramPacket(buffer, buffer.length, dst, UDPPort);
-			socket.send(emission);
-			socket.receive(reception);
-			return new String(reception.getData(), 0, reception.getLength());
-		} catch (Exception e){
-			System.out.println(e);
-			throw new TransmissionError();
-		}
+	}
 
+	/** list server’s directory content
+	 * @return	list of files
+	 * @throws	InternalError
+	 * @throws	UnknowHostException
+	 * @throws	IOException
+	 * @throws	TransmissionError
+	 * @throws	ProtocolError
+	 * @throws	VersionError
+	 * @throws	SizeError
+	 * @throws	EmptyDirectory
+	 * @throws	InternalRemoteError
+	 * @throws	ProtocolRemoteError
+	 * @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);
+		try {
+			Payload p = ProtocolP2PDatagram.receive(socket).getPayload();
+			assert p instanceof FileList : "This payload must be instance of Filelist";
+			if (!(p instanceof FileList)) {
+				throw new InternalError();
+			} else {
+				return ((FileList)p).getFileList();
+			}
+		} catch (NotFound e) {
+			throw new ProtocolError();
+		}
 	}
 }

src/clientP2P/ClientP2P.java

@@ -10,7 +10,7 @@ public class ClientP2P {
 	public ClientP2P() {
 		directories = new Directories("P2P_JAVA_PROJECT_CLIENT");
 		host = "localhost";
-		port = 40000;
+		port = 40001;
 		System.out.println("Client will try to contact server at " + host + " on port " + port + ". It will save files in " + directories.getDataHomeDirectory());
 		directories.askOpenDataHomeDirectory();
 	}

src/protocolP2P/FileList.java

@@ -15,21 +15,21 @@ import java.io.UnsupportedEncodingException;
  * @version	1.0
  */
 public class FileList extends Payload {
-	private String[] content;
+	private String[] fileList;
 
 	/** Constructor (typically used by the server) with an ArrayList parameter containing
 	 * filenames.
-	 * @param content	a list of files. Must not be empty.
+	 * @param fileList	a list of files. Must not be empty.
 	 * @throws	InternalError
 	 */
-	public FileList(String[] content) throws InternalError {
+	public FileList(String[] fileList) throws InternalError {
 		super(RequestResponseCode.LIST_RESPONSE);
 		/* assert to help debugging */
-		assert content.length != 0 : "Payload size of FileList must not be empty, use EmptyDirectory from Payload instead";
-		if (content.length == 0) {
+		assert fileList.length != 0 : "Payload size of FileList must not be empty, use EmptyDirectory from Payload instead";
+		if (fileList.length == 0) {
 			throw new InternalError();
 		}
-		this.content = content;
+		this.fileList = fileList;
 	}
 
 	/** Constructor (typically used by client) with a byte[] parameter containing the datagram received.
@@ -49,7 +49,7 @@ public class FileList extends Payload {
 		}
 		int size = getPayloadSize(datagram);
 		try {
-			content = (new String(datagram, 8, size, "UTF-8")).split("\n");
+			fileList = (new String(datagram, 8, size, "UTF-8")).split("\n");
 		} catch (UnsupportedEncodingException e) {
 			throw new InternalError();
 		}
@@ -64,18 +64,17 @@ public class FileList extends Payload {
 	protected byte[] toDatagram() throws InternalError {
 		// compute size
 		int size = 8;
-		for (String s : content) {
+		for (String s : fileList) {
 			size += s.length();
 		}
 		byte[] datagram = new byte[size]; // java initialize all to zero
-		// size is keep blank (ProtocolP2PDatagram will handle it)
 		// set request/response code
 		datagram[RequestResponseCode.RRCODE_POSITION] = requestResponseCode.codeValue;
 		// bits 16-31 are reserved for future use
-		setPayloadSize(size, datagram);
-		// Write content
+		setPayloadSize(size - 8, datagram);
+		// Write fileList
 		int bCount = 8;
-		for(String s : content) {
+		for(String s : fileList) {
 			if (bCount != 8) { // not on first iteration
 				try {
 					datagram[bCount] = "\n".getBytes("UTF-8")[0]; // separator
@@ -98,4 +97,11 @@ public class FileList extends Payload {
 		}
 		return datagram;
 	}
+
+	/** fileList getter.
+	 * @return	fileList
+	 */
+	public String[] getFileList() {
+		return fileList;
+	}
 }

src/protocolP2P/FilePart.java

@@ -76,11 +76,10 @@ public class FilePart extends Payload {
 		// compute payload size
 		int size = 28 + filename.length() + partialContent.length;
 		byte[] datagram = new byte[size]; // java initialize all to zero
-		// size is keep blank (ProtocolP2PDatagram will handle it)
 		// set request/response code
 		datagram[RequestResponseCode.RRCODE_POSITION] = requestResponseCode.codeValue;
 		// bits 16-31 are reserved for future use
-		setPayloadSize(size, datagram);
+		setPayloadSize(size - 8, datagram);
 		// write offset to datagram (Byte 8)
 		BytesArrayTools.write(datagram, 8, offset);
 		// write totalSize to datagram (Byte 16)
@@ -90,20 +89,20 @@ public class FilePart extends Payload {
 		// write filename to datagram
 		try {
 			byte[] bFilename = filename.getBytes("UTF-8");
+			int i = filename.length() + 24;
+			for (byte b : bFilename) {
+				datagram[i] = b;
+				i += 1;
+			}
+			// write partialContent to datagram
+			for (byte b: partialContent) {
+				datagram[i] = b;
+				i += 1;
+			}
+			return datagram;
 		} catch (UnsupportedEncodingException e) {
 			throw new InternalError();
 		}
-		int i = filename.length() + 24;
-		for (byte b : bFilename) {
-			datagram[i] = b;
-			i += 1;
-		}
-		// write partialContent to datagram
-		for (byte b: partialContent) {
-			datagram[i] = b;
-			i += 1;
-		}
-		return datagram;
 	}
 
 	/** Write from bytes 8 to 15 of datagram into offset.
@@ -170,4 +169,31 @@ public class FilePart extends Payload {
 		}
 	}
 
+	/** partialContent getter.
+	 * @return	partialcontent
+	 */
+	public byte[] getPartialContent() {
+		return partialContent;
+	}
+
+	/** filename getter.
+	 * @return	String
+	 */
+	public String getFilename() {
+		return filename;
+	}
+
+	/** offset getter.
+	 * @return	offset
+	 */
+	public long getOffset() {
+		return offset;
+	}
+
+	/** totalSize getter.
+	 * @return	totalSize
+	 */
+	public long getTotalSize() {
+		return totalSize;
+	}
 }

src/protocolP2P/LoadRequest.java

@@ -0,0 +1,90 @@
+package protocolP2P;
+import protocolP2P.Payload;
+import protocolP2P.RequestResponseCode;
+import exception.TransmissionError;
+import exception.ProtocolError;
+import exception.InternalError;
+import exception.SizeError;
+import java.io.UnsupportedEncodingException;
+
+/** Representation of payload for load request.
+ * @author	Louis Royer
+ * @author	Flavien Haas
+ * @author	JS Auge
+ * @version	1.0
+ */
+public class LoadRequest extends Payload {
+	private String filename;
+
+	/** Constructor (typically used by the server) with a filename parameter.
+	 * @param filename	name of the file to download. Must not be empty.
+	 * @throws	InternalError
+	 */
+	public LoadRequest(String filename) throws InternalError {
+		super(RequestResponseCode.LOAD_REQUEST);
+		/* assert to help debugging */
+		assert filename.length() != 0 : "Payload size of LoadRequest must not be empty";
+		if (filename.length() == 0) {
+			throw new InternalError();
+		}
+		this.filename = filename;
+	}
+
+	/** Constructor (typically used by client) with a byte[] parameter containing the datagram received.
+	 * @param datagram	the full datagram received
+	 * @throws	SizeError
+	 * @throws	InternalError
+	 * @throws	ProtocolError
+	 * @throws	TransmissionError
+	 */
+	protected LoadRequest(byte[] datagram) throws TransmissionError, SizeError, ProtocolError, InternalError {
+		super(datagram);
+		/* 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";
+		/* InternalErrorException */
+		if (requestResponseCode!= RequestResponseCode.LOAD_REQUEST) {
+			throw new InternalError();
+		}
+		int size = getPayloadSize(datagram);
+		try {
+			filename = new String(datagram, 8, 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
+	 * @throws	InternalError
+	 */
+	protected byte[] toDatagram() throws InternalError {
+		// compute size
+		int size = 8 + filename.length();
+		byte[] datagram = 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);
+		// Write filename
+		int bCount = 8;
+		try {
+			byte[] sb = filename.getBytes("UTF-8");
+			for(byte b : sb) {
+				datagram[bCount] = b;
+				bCount += 1;
+			}
+		} catch (UnsupportedEncodingException e) {
+			throw new InternalError();
+		}
+		return datagram;
+	}
+
+	/** filename getter.
+	 * @return	filename
+	 */
+	public String getFilename() {
+		return filename;
+	}
+}

src/protocolP2P/Payload.java

@@ -2,6 +2,7 @@ package protocolP2P;
 import protocolP2P.RequestResponseCode;
 import protocolP2P.FilePart;
 import protocolP2P.FileList;
+import protocolP2P.LoadRequest;
 import exception.ProtocolError;
 import exception.InternalError;
 import exception.TransmissionError;
@@ -26,6 +27,7 @@ public class Payload {
 		/* asserts to help debugging */
 		assert requestResponseCode != RequestResponseCode.LIST_RESPONSE || (this instanceof FileList) : "LIST_RESPONSE must use FilePart class";
 		assert requestResponseCode != RequestResponseCode.LOAD_RESPONSE || (this instanceof FilePart) : "LOAD_RESPONSE must use FileList class";
+		assert requestResponseCode != RequestResponseCode.LOAD_REQUEST  || (this instanceof LoadRequest) : "LOAD_REQUEST must use LoadRequest class";
 		this.requestResponseCode = requestResponseCode;
 		checkRequestResponseCode(); // this can throw InternalError
 	}
@@ -46,6 +48,7 @@ public class Payload {
 		}
 		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]);
 		checkRequestResponseCode(); // this can throw InternalError
 	}
@@ -56,7 +59,8 @@ public class Payload {
 	private void checkRequestResponseCode() throws InternalError {
 		/* Incorrect use cases (use subclasses instead) */
 		if ((requestResponseCode == RequestResponseCode.LIST_RESPONSE && !(this instanceof FileList))
-		 || (requestResponseCode == RequestResponseCode.LOAD_RESPONSE && !(this instanceof FilePart))) {
+		 || (requestResponseCode == RequestResponseCode.LOAD_RESPONSE && !(this instanceof FilePart))
+		 || (requestResponseCode == RequestResponseCode.LOAD_REQUEST  && !(this instanceof LoadRequest))) {
 			throw new InternalError();
 		}
 	}
@@ -70,7 +74,7 @@ public class Payload {
 	protected byte[] toDatagram() 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
-		// size is keep blank (ProtocolP2PDatagram will handle it)
+		// size is zero (and this is the default)
 		// set request/response code
 		datagram[RequestResponseCode.RRCODE_POSITION] = requestResponseCode.codeValue;
 		// bits 16-31 are reserved for future use
@@ -102,4 +106,11 @@ public class Payload {
 	protected static int getPayloadSize(byte[] datagram) throws SizeError {
 		return BytesArrayTools.readInt(datagram, PAYLOAD_SIZE_POSITION);
 	}
+
+	/** RRCode getter.
+	 * @return	Request/Response code
+	 */
+	public RequestResponseCode getRequestResponseCode() {
+		return requestResponseCode;
+	}
 }

src/protocolP2P/ProtocolP2PDatagram.java

@@ -1,11 +1,19 @@
 package protocolP2P;
-import exception.ProtocolError;
-import exception.VersionError;
-import exception.SizeError;
 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 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;
@@ -25,6 +33,8 @@ public class ProtocolP2PDatagram {
 	private final static int VERSION_POSITON = 0;
 	private byte version;
 	private Payload payload;
+	private InetAddress hostR;
+	private int portR;
 
 	/** Constructor with payload parameter (typically used when sending datagram).
 	 * @param payload	the payload associated with the datagram to send
@@ -53,32 +63,86 @@ public class ProtocolP2PDatagram {
 
 	/** 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) throws InternalError, 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);
+		DatagramPacket datagramPacket = new DatagramPacket(datagram, datagram.length, received.getHostR(), received.getPortR());
 		socket.send(datagramPacket);
 	}
 
+	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
-	 * @return	payload of the datagram
 	 * @throws	TransmissionError
 	 * @throws	ProtocolError
 	 * @throws	VersionError
 	 * @throws	InternalError
 	 * @throws	SizeError
+	 * @throws	ProtocolRemoteError
+	 * @throws	VersionRemoteError
+	 * @throws	InternalRemoteError
+	 * @throws	EmptyDirectory
+	 * @throws	NotFound
+	 * @throws	IOException
 	 */
-	public static Payload receive(DatagramSocket socket) throws TransmissionError, ProtocolError, VersionError, InternalError, SizeError {
+	public static ProtocolP2PDatagram receive(DatagramSocket socket) throws NotFound, EmptyDirectory, InternalRemoteError, VersionRemoteError, ProtocolRemoteError, TransmissionError, ProtocolError, VersionError, InternalError, SizeError, IOException {
 		// reception
 		byte[] datagram = new byte[4096];
 		DatagramPacket reception = new DatagramPacket(datagram, datagram.length);
+		socket.receive(reception);
 		// contruction
-		ProtocolP2PDatagram p = new ProtocolP2PDatagram(datagram);
-		return p.getPayload();
+		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();
+				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
@@ -100,6 +164,9 @@ public class ProtocolP2PDatagram {
 			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;
@@ -111,7 +178,7 @@ public class ProtocolP2PDatagram {
 	 * @return the full datagram to send
 	 * @throws	InternalError
 	 */
-	private byte[] toDatagram() throws InternalError {
+	protected byte[] toDatagram() throws InternalError {
 		byte[] datagram = payload.toDatagram();
 		datagram[VERSION_POSITON] = version;
 		return datagram;
@@ -121,7 +188,7 @@ public class ProtocolP2PDatagram {
 	/** Returns Payload associated with the datagram.
 	 * @return	payload associated with the datagram
 	 */
-	private Payload getPayload() {
+	public Payload getPayload() {
 		return payload;
 	}
 
@@ -133,5 +200,33 @@ public class ProtocolP2PDatagram {
 			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;
+	}
 }
 

src/protocolP2P/RequestResponseCode.java

@@ -50,7 +50,7 @@ public enum RequestResponseCode {
 	 * @param code	value of the element in datagram
 	 * @return enum element
 	 */
-	public static RequestResponseCode fromCode(byte code) throws ProtocolError {
+	protected static RequestResponseCode fromCode(byte code) throws ProtocolError {
 		RequestResponseCode r= BY_CODE.get(Byte.valueOf(code));
 		if (r == null) {
 			throw new ProtocolError();

src/remoteException/EmptyDirectory.java

@@ -0,0 +1,4 @@
+package remoteException;
+public class EmptyDirectory extends Exception {
+	private static final long serialVersionUID = 11L;
+}

src/remoteException/InternalRemoteError.java

@@ -0,0 +1,4 @@
+package remoteException;
+public class InternalRemoteError extends Exception {
+	private static final long serialVersionUID = 11L;
+}

src/remoteException/NotFound.java

@@ -1,4 +1,4 @@
-package exception;
+package remoteException;
 public class NotFound extends Exception {
 	private static final long serialVersionUID = 11L;
 }

src/remoteException/ProtocolRemoteError.java

@@ -0,0 +1,4 @@
+package remoteException;
+public class ProtocolRemoteError extends Exception {
+	private static final long serialVersionUID = 11L;
+}

src/remoteException/VersionRemoteError.java

@@ -0,0 +1,4 @@
+package remoteException;
+public class VersionRemoteError extends Exception {
+	private static final long serialVersionUID = 11L;
+}

src/serverP2P/ServerManagementUDP.java

@@ -2,13 +2,26 @@ package serverP2P;
 import java.util.Vector;
 import java.io.File;
 import java.io.IOException;
-import java.net.DatagramPacket;
 import java.net.DatagramSocket;
-import exception.ProtocolError;
-import exception.NotFound;
-import exception.InternalError;
+import java.net.SocketException;
 import java.nio.file.Paths;
 import java.nio.file.Files;
+import protocolP2P.ProtocolP2PDatagram;
+import protocolP2P.RequestResponseCode;
+import protocolP2P.Payload;
+import protocolP2P.LoadRequest;
+import protocolP2P.FileList;
+import protocolP2P.FilePart;
+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;
 
 
 /** Implementation of P2P-JAVA-PROJECT VERSION 1.0 protocol for UDP.
@@ -19,10 +32,10 @@ import java.nio.file.Files;
  */
 public class ServerManagementUDP implements Runnable {
 
-	private Vector<String> fileList;
+	private String[] fileList;
 	private String baseDirectory;
 	private int UDPPort;
-	private final String protocolID = "P2P-JAVA-PROJECT VERSION 1.0";
+	private DatagramSocket socket;
 
 	/** Constructor for UDP implementation, with baseDirectory and UDPPort parameters.
 	 * @param baseDirectory	the root directory where files are stored
@@ -31,148 +44,106 @@ public class ServerManagementUDP implements Runnable {
 	public ServerManagementUDP(String baseDirectory, int UDPPort) {
 		this.baseDirectory = baseDirectory;
 		this.UDPPort = UDPPort;
-		fileList = new Vector<String>();
 		initFileList();
+		try {
+			socket = new DatagramSocket(UDPPort);
+		} catch (SocketException e) {
+			System.err.println("Error: cannot listen on port " + UDPPort);
+			System.exit(-1);
+		}
 	}
 
 	/** Implementation of runnable. This methods allows to run the server.
 	 */
 	public void run() {
-		try {
-			// socket creation on port UDPPort
-			DatagramSocket socket = new DatagramSocket(UDPPort);
-			// buffer to receive UDP Datagram
-			final byte[] buffer = new byte[1024];
-			while(true) {
-				// java object to receive Datagram
-				DatagramPacket dgram = new DatagramPacket(buffer, buffer.length);
-				// wait and receive datagram
-				socket.receive(dgram);
-				// extract data
-				String str = new String(dgram.getData(), 0, dgram.getLength());
-				// process request
-				str = processRequest(str);
-				dgram.setData(str.getBytes());
-				dgram.setLength(str.getBytes().length);
-				// send response
-				socket.send(dgram);
-			}
-		} catch (Exception e) {
-			// TODO: treat exceptions
-		}
-	}
-
-	/** Process the request received.
-	 * @param request	the request received
-	 * @return	data to be send as response
-	 */
-	String processRequest(String request) {
-		String res = protocolID + "\n";
-		String formattedRequest[] = request.split("\n");
-		try {
+		while(true) {
 			try {
-				checkProtocolID(formattedRequest[0]);
-				switch (formattedRequest[1]) {
-					case "LIST":
-						System.out.println("List request");
-						res += sendFileList();
+				ProtocolP2PDatagram pd = ProtocolP2PDatagram.receive(socket);
+				Payload p = pd.getPayload();
+				switch (p.getRequestResponseCode()) {
+					case LOAD_REQUEST:
+						System.out.println("Received LOAD_REQUEST");
+						assert p instanceof LoadRequest : "payload must be an instance of LoadRequest";
+						if (!(p instanceof LoadRequest)) {
+							sendInternalError(pd);
+						} else {
+							String filename = ((LoadRequest)p).getFilename();
+							try {
+								byte[] load = Files.readAllBytes(Paths.get(baseDirectory + filename));
+								try {
+									(new ProtocolP2PDatagram((Payload)(new FilePart(filename, load.length, 0, load)))).send(socket, pd);
+								} catch (Exception e2) {
+									System.err.println(e2);
+								}
+							} catch (IOException e) {
+								try {
+									(new ProtocolP2PDatagram(new Payload(RequestResponseCode.NOT_FOUND))).send(socket, pd);
+								} catch (Exception e2) {
+									System.err.println(e2);
+								}
+							}
+						}
 						break;
-					case "DOWNLOAD":
-						System.out.println("Download request: " + formattedRequest[2]);
-						res += upload(formattedRequest[2]);
+					case LIST_REQUEST:
+						System.out.println("Received LIST_REQUEST");
+						try {
+							if (fileList.length == 0) {
+								System.err.println("Sending EMPTY_DIRECTORY");
+								(new ProtocolP2PDatagram(new Payload(RequestResponseCode.EMPTY_DIRECTORY))).send(socket, pd);
+							} else {
+								System.out.println("Sending LIST_RESPONSE");
+								(new ProtocolP2PDatagram((Payload)(new FileList(fileList)))).send(socket, pd);
+							}
+						} catch (Exception e2) {
+							System.err.println(e2);
+						}
 						break;
 					default:
-						throw new ProtocolError();
+						sendInternalError(pd);
 				}
-			} catch (java.lang.ArrayIndexOutOfBoundsException e) {
-				throw new ProtocolError();
+			} 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 (ProtocolError e) {
-			// wrong version or wrong implementation
-			res += sendProtocolError();
-		} catch (InternalError e) {
-			res += sendInternalError();
-		} catch (NotFound e) {
-			res += sendNotFound();
 		}
-		return res;
 	}
 
 	/** Initialize local list of all files allowed to be shared.
 	 */
 	private void initFileList() {
 		File folder = new File(baseDirectory);
+		Vector<String> v = new Vector<String>();
 		File[] files = folder.listFiles();
 		/* Add non-recursively files's names to fileList */
 		for (File f : files) {
 			if (f.isFile()) {
-				fileList.add(f.getName());
+				v.add(f.getName());
 			}
 		}
+		fileList = new String[v.size()];
+		v.toArray(fileList);
 	}
 
-	/** Check server's protocol identifier matches message's protocol identifier.
-	 * Throws a ProtocolError if mismatched.
-	 * @param msgProtocolID	part of the request containing protocol identifier
-	 * @throws	ProtocolError
-	 */
-	private void checkProtocolID(String msgProtocolID) throws ProtocolError {
-		if (!protocolID.equals(msgProtocolID)) {
-			throw new ProtocolError();
-		}
-	}
 
-	/** Prepare the data to be send if a file is requested
-	 * @param filename	name of the file to be send
-	 * @return	data to be send
-	 * @throws	NotFound
-	 * @throws InternalError
+	
+	/** Send an internal error message.
+	 * @param pd	ProtocolP2PDatagram to respond
 	 */
-	private String upload(String filename) throws NotFound, InternalError {
-		File file = new File(baseDirectory + filename);
-		System.out.println("Uploading `" + baseDirectory + filename + "`");
-		if (!file.exists() || !file.isFile()) {
-			throw new NotFound();
-		}
-		String res = "LOAD\n" + file.length() + "\n";
+	private void sendInternalError(ProtocolP2PDatagram pd) {
 		try {
-			res += new String(Files.readAllBytes(Paths.get(baseDirectory + filename)));
-		} catch (IOException e) {
-			throw new InternalError();
+			(new ProtocolP2PDatagram(new Payload(RequestResponseCode.INTERNAL_ERROR))).send(socket, pd);
+		} catch (Exception e) {
+			System.err.println(e);
 		}
-		return res;
-	}
-
-	/** Prepare the data to be send if file list is requested
-	 * @return	data to be send
-	 */
-	private String sendFileList() {
-		String res = "LIST\n";
-		for (String f : fileList) {
-			res += (f + "\n");
-		}
-		return res + "\n";
-	}
-
-	/** Prepare data to be send if protocol error is detected
-	 * @return	data to be send
-	 */
-	private String sendProtocolError() {
-		return "PROTOCOL ERROR\n";
-	}
-
-	/** Prepare data to be send if file is not found
-	 * @return	data to be send
-	 */
-	private String sendNotFound() {
-		return "NOT FOUND\n";
-	}
-
-	/** Prepare data to be send if internal error encounterred
-	 * @return	data to be send
-	 */
-	private String sendInternalError() {
-		return "INTERNAL ERROR\n";
 	}
 
 }
+

src/serverP2P/ServerP2P.java

@@ -8,7 +8,7 @@ public class ServerP2P {
 
 	public ServerP2P() {
 		directories = new Directories("P2P_JAVA_PROJECT_SERVER");
-		port = 40000;
+		port = 40001;
 		System.out.println("Server will listen on port " + port + " and serve files from " + directories.getDataHomeDirectory());
 		directories.askOpenDataHomeDirectory();
 	}