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Server.java
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Server.java
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import java.io.*;
import java.net.*;
import java.util.*;
public class Server {
Map< String, String [] > csInfo = new HashMap< String, String [] >();
DatagramSocket sock = null;
public static void echol(String msg) {
System.out.println(msg);
}
public static void echo(Object msg) {
System.out.print(msg);
}
public void broadcast( Map< String, String [] > csInfo ) throws Exception {
byte [] bcsInfo = makePacket( csInfo, "table" );
for ( Map.Entry < String, String [] > entry : csInfo.entrySet() ) {
String [] arr = entry.getValue();
Object [] rArr = stringToRaw( arr );
if ( rArr[ 2 ] == "Yes") {
DatagramPacket dpcsInfo = new DatagramPacket(bcsInfo, bcsInfo.length, (InetAddress)rArr[ 0 ], (Integer)rArr[ 1 ] );
sock.send( dpcsInfo );
}
}
}
public String readOffline(String destName) {
try {
File file = new File(destName + ".txt");
if (file.exists()) {
BufferedReader br = new BufferedReader(new FileReader(file.getAbsoluteFile()));
StringBuilder sb = new StringBuilder();
String line = br.readLine();
sb.append(line);
sb.append(System.lineSeparator());
line = br.readLine();
while (line != null) {
sb.append(">>>");
sb.append(line);
sb.append(System.lineSeparator());
line = br.readLine();
}
file.delete();
return sb.toString();
}
}
catch (Exception e) {
e.printStackTrace();
}
return null;
}
// content, dest name
public void writeOffline(String destName, String content ) {
BufferedWriter bw = null;
FileWriter fw = null;
try {
File file = new File(destName + ".txt");
// if file doesnt exists, then create it
if (!file.exists()) {
file.createNewFile();
}
// true = append file
fw = new FileWriter(file.getAbsoluteFile(), true);
bw = new BufferedWriter(fw);
bw.write(content);
bw.newLine();
} catch (IOException e) {
e.printStackTrace();
} finally {
try {
if (bw != null)
bw.close();
if (fw != null)
fw.close();
} catch (IOException ex) {
ex.printStackTrace();
}
}
}
public Object [] stringToRaw( String [] arr ) throws Exception {
String sIP = arr[ 0 ];
String sPort = arr[ 1 ];
Object [] rarr = new Object[ 3 ];
rarr [ 0 ] = InetAddress.getByName( sIP );
rarr [ 1 ] = Integer.parseInt( sPort );
rarr [ 2 ] = arr[ 2 ];
return rarr;
}
// TODO: throw Exception
public byte [] makePacket( Object some, String cmd ) throws Exception {
Map< String, Object > packetDic = new HashMap< String, Object >();
packetDic.put( cmd, some );
ByteArrayOutputStream byteOut = new ByteArrayOutputStream();
ObjectOutputStream out = new ObjectOutputStream(byteOut);
out.writeObject(packetDic);
return byteOut.toByteArray();
}
public Map< String, Object > decode( byte [] data ) throws Exception {
ByteArrayInputStream byteIn = new ByteArrayInputStream(data);
ObjectInputStream in = new ObjectInputStream(byteIn);
Object inObj = in.readObject(); // dictionary
Map< String, Object > dic = ( Map< String, Object > ) inObj;
return dic;
}
public void work( int port ) {
try {
sock = new DatagramSocket( port );
byte[] buffer = new byte[65536];
DatagramPacket incoming = new DatagramPacket(buffer, buffer.length);
while (true) {
sock.receive(incoming);
byte[] data = incoming.getData();
// get port and address info
int cPort = incoming.getPort();
InetAddress cIP = incoming.getAddress();
Map< String, Object > packetDic = decode( data );
String name;
if ( ( name = ( String )packetDic.get("dereg") ) != null ) {
// update the table
String [] entry = csInfo.get( name );
entry[ 2 ] = "No";
csInfo.put( name, entry );
String sregAck = "[You are Offline. Bye]";
byte [] back = makePacket( sregAck, "deregack" );
DatagramPacket dpack = new DatagramPacket(back, back.length, cIP, cPort );
sock.send( dpack );
broadcast( csInfo);
}
else if ( packetDic.get("reg" ) != null ) {
String s = (String)packetDic.get("reg" );
String scIP = cIP.getHostAddress();
String scPort = Integer.toString( cPort );
String [] cInfoArr = { scIP, scPort, "Yes" };
// name: { clientIP, clientPort, status }
csInfo.put( s, cInfoArr );
// send registration ack to the client
String sregAck = "[Welcome, You are registered.]";
byte [] back = makePacket( sregAck, "ack" );
DatagramPacket dpack = new DatagramPacket(back, back.length, cIP, cPort );
sock.send( dpack );
String offMessage;
if ( ( offMessage = readOffline(s) ) != null ) {
String offAck = "[You have messages]";
byte [] boffAck = makePacket( offAck, "sendoff" );
DatagramPacket dpoffAck = new DatagramPacket(boffAck, boffAck.length, cIP, cPort );
sock.send( dpoffAck );
byte [] boffMessage = makePacket( offMessage, "sendoff" );
DatagramPacket dpoffMessage = new DatagramPacket(boffMessage, boffMessage.length, cIP, cPort );
sock.send( dpoffMessage );
}
// broadcast table
broadcast( csInfo);
}
else if ( packetDic.get("send" ) != null ) {
String s = (String)packetDic.get("send" );
String [] sArr = s.split(" ", 2 );
String destName = sArr[ 0 ];
if ( ( csInfo.get( destName ) )[ 2 ].equals("No")) {
writeOffline( destName, sArr[1]);
// send saved ack to client
String savedAck = "[Messages received by the server and saved]";
byte [] bsavedAck = makePacket( savedAck, "savedAck");
DatagramPacket dpsavedAck = new DatagramPacket(bsavedAck, bsavedAck.length, cIP, cPort );
sock.send( dpsavedAck);
//rebroadcast the table
broadcast( csInfo );
}
// if client is online
else {
String sregAck = "[Client " + destName + " exists!!]";
byte [] back = makePacket( sregAck, "errorAck" );
DatagramPacket dpack = new DatagramPacket(back, back.length, cIP, cPort );
sock.send( dpack );
}
}
}
} catch (Exception e) {
e.printStackTrace();
}
}
public static void main(String args[]) throws Exception {
try {
Server server = new Server();
server.work( Integer.parseInt( args[ 0 ] ));
} catch ( ArrayIndexOutOfBoundsException e ) {
echol("Wrong Server-mode Input Format: please use 'Udpchat -s <port>'");
}
}
}