Send tcp using thread

Question

MyRcon2.java
package rconed;
import rconed.Rcon;
import rconed.SourceRcon;
public void run() {
    try {
      String stringShow = null;
      SourceRcon R = new SourceRcon();
      stringShow = R.send(this.ip, this.port, this.password, this.command);
      System.out.println(stringShow);
    }catch (Exception e) {}
public void startServer(int portNumber)
    try
      byte[] buf = new byte[1000];
      DatagramSocket ss = new DatagramSocket(portNumber);
      while (true)
        DatagramPacket ip = new DatagramPacket(buf, buf.length);
        ss.receive(ip);
        String rev=new String(buf,0,ip.getLength());
        StringTokenizer st = new StringTokenizer(rev, "/****/");
        MyRcon2 Send = new MyRcon2();
        Send.ip = st.nextToken();
        Send.port = Integer.parseInt(st.nextToken());
        Send.password = st.nextToken();
        Send.command = st.nextToken();
        Thread t =new Thread(Send);
                                                                 t.start();
    }catch (IOException e){}
  }SourceRcon.java
package rconed;
import rconed.exception.BadRcon;
import rconed.exception.ResponseEmpty;
import java.io.*;
import java.net.*;
import java.nio.ByteBuffer;
import java.nio.ByteOrder;
* User: oscahie (aka PiTaGoRaS)<br/>
* Date: 03-jan-2005<br/>
* Time: 19:11:40<br/>
* version: 0.4<br/>
* Rcon library for Source Engine based games<br/>
public class SourceRcon {
    final static int SERVERDATA_EXECCOMMAND = 2;
    final static int SERVERDATA_AUTH = 3;
    final static int SERVERDATA_RESPONSE_VALUE = 0;
    final static int SERVERDATA_AUTH_RESPONSE = 2;
    final static int RESPONSE_TIMEOUT = 2000;
    final static int MULTIPLE_PACKETS_TIMEOUT = 300;
    static Socket rconSocket = null;
    static InputStream in = null;
    static OutputStream out = null;
     * Send the RCON command to the game server (must have been previously authed with the correct rcon_password)
     * @param ipStr     The IP (as a String) of the machine where the RCON command will go.
     * @param port      The port of the machine where the RCON command will go.
     * @param password  The RCON password.
     * @param command   The RCON command (without the rcon prefix).
     * @return The reponse text from the server after trying the RCON command.
     * @throws SocketTimeoutException when there is any problem communicating with the server.
    public static String send(String ipStr, int port, String password, String command) throws SocketTimeoutException, BadRcon, ResponseEmpty {
        return send(ipStr, port, password, command, 0);
     * Send the RCON command to the game server (must have been previously authed with the correct rcon_password)
     * @param ipStr     The IP (as a String) of the machine where the RCON command will go.
     * @param port      The port of the machine where the RCON command will go.
     * @param password  The RCON password.
     * @param command   The RCON command (without the rcon prefix).
     * @param localPort The port of the local machine to use for sending out the RCON request.
     * @return The reponse text from the server after trying the RCON command.
     * @throws SocketTimeoutException when there is any problem communicating with the server.
    public static String send(String ipStr, int port, String password, String command, int localPort) throws SocketTimeoutException, BadRcon, ResponseEmpty {
        String response = "";
        try {
            rconSocket = new Socket();
            InetAddress addr = InetAddress.getLocalHost();
            byte[] ipAddr = addr.getAddress();
            InetAddress inetLocal = InetAddress.getByAddress(ipAddr);
            rconSocket.bind(new InetSocketAddress(inetLocal, localPort));
            rconSocket.connect(new InetSocketAddress(ipStr, port), 1000);
            out = rconSocket.getOutputStream();
            in = rconSocket.getInputStream();
            rconSocket.setSoTimeout(RESPONSE_TIMEOUT);
            if (rcon_auth(password)) {
                // We are now authed
                ByteBuffer[] resp = sendCommand(command);
                // Close socket handlers, we don't need them more
                out.close(); in.close(); rconSocket.close();
                if (resp != null) {
                    response = assemblePackets(resp);
                    if (response.length() == 0) {
                        throw new ResponseEmpty();
            else {
                throw new BadRcon();
        } catch (SocketTimeoutException timeout) {
            throw timeout;
        } catch (UnknownHostException e) {
            System.err.println("UnknownHostException: " + e.getCause());
        } catch (IOException e) {
            System.err.println("Couldn't get I/O for the connection: "+ e.getCause());
        return response;
    private static ByteBuffer[] sendCommand(String command) throws SocketTimeoutException {
        byte[] request = contructPacket(2, SERVERDATA_EXECCOMMAND, command);
        ByteBuffer[] resp = new ByteBuffer[128];
        int i = 0;
        try {
            out.write(request);
            resp[i] = receivePacket();  // First and maybe the unique response packet
            try {
                // We don't know how many packets will return in response, so we'll
                // read() the socket until TimeoutException occurs.
                rconSocket.setSoTimeout(MULTIPLE_PACKETS_TIMEOUT);
                while (true) {
                    resp[++i] = receivePacket();
            } catch (SocketTimeoutException e) {
                // No more packets in the response, go on
                return resp;
        } catch (SocketTimeoutException timeout) {
            // Timeout while connecting to the server
            throw timeout;
        } catch (Exception e2) {
            System.err.println("I/O error on socket\n");
        return null;
    private static byte[] contructPacket(int id, int cmdtype, String s1) {
        ByteBuffer p = ByteBuffer.allocate(s1.length() + 16);
        p.order(ByteOrder.LITTLE_ENDIAN);
        // length of the packet
        p.putInt(s1.length() + 12);
        // request id
        p.putInt(id);
        // type of command
        p.putInt(cmdtype);
        // the command itself
        p.put(s1.getBytes());
        // two null bytes at the end
        p.put((byte) 0x00);
        p.put((byte) 0x00);
        // null string2 (see Source protocol)
        p.put((byte) 0x00);
        p.put((byte) 0x00);
        return p.array();
    private static ByteBuffer receivePacket() throws Exception {
        ByteBuffer p = ByteBuffer.allocate(4120);
        p.order(ByteOrder.LITTLE_ENDIAN);
        byte[] length = new byte[4];
        if (in.read(length, 0, 4) == 4) {
            // Now we've the length of the packet, let's go read the bytes
            p.put(length);
            int i = 0;
            while (i < p.getInt(0)) {
                p.put((byte) in.read());
                i++;
            return p;
        else {
            return null;
    private static String assemblePackets(ByteBuffer[] packets) {
    // Return the text from all the response packets together
        String response = "";
        for (int i = 0; i < packets.length; i++) {
            if (packets[i] != null) {
                response = response.concat(new String(packets.array(), 12, packets[i].position()-14));
return response;
private static boolean rcon_auth(String rcon_password) throws SocketTimeoutException {
byte[] authRequest = contructPacket(1337, SERVERDATA_AUTH, rcon_password);
ByteBuffer response = ByteBuffer.allocate(64);
try {
out.write(authRequest);
response = receivePacket(); // junk response packet
response = receivePacket();
// Lets see if the received request_id is leet enougth ;)
if ((response.getInt(4) == 1337) && (response.getInt(8) == SERVERDATA_AUTH_RESPONSE)) {
return true;
} catch (SocketTimeoutException timeout) {
throw timeout;
} catch (Exception e) {
System.err.println("I/O error on socket\n");
return false;
}Rcon.java package rconed;
import java.io.IOException;
import java.net.DatagramPacket;
import java.net.DatagramSocket;
import java.net.InetAddress;
import java.net.SocketTimeoutException;
import rconed.exception.BadRcon;
import rconed.exception.ResponseEmpty;
* Rcon is a simple Java library for issuing RCON commands to game servers.
* <p/>
* This has currently only been used with HalfLife based servers.
* <p/>
* Example:
* <p/>
* response = Rcon.send(27778, "127.0.0.1", 27015, rconPassword, "log on");
* <p/>
* PiTaGoRas - 21/12/2004<br>
* Now also supports responses divided into multiple packets, bad rcon password
* detection and other minor fixes/improvements.
* <p/>
* @author DeadEd
* @version 1.1
public abstract class Rcon {
private static final int RESPONSE_TIMEOUT = 2000;
private static final int MULTIPLE_PACKETS_TIMEOUT = 300;
* Send the RCON request. Sends the command to the game server. A port
* (localPort must be opened to send the command through.
* @param localPort The port on the local machine where the RCON request can be made from.
* @param ipStr The IP (as a String) of the machine where the RCON command will go.
* @param port The port of the machine where the RCON command will go.
* @param password The RCON password.
* @param command The RCON command (without the rcon prefix).
* @return The reponse text from the server after trying the RCON command.
* @throws SocketTimeoutException when there is any problem communicating with the server.
public static String send(int localPort, String ipStr, int port, String password, String command)
throws SocketTimeoutException, BadRcon, ResponseEmpty {
RconPacket[] requested = sendRequest(localPort, ipStr, port, password, command);
String response = assemblePacket(requested);
if (response.matches("Bad rcon_password.\n")) {
throw new BadRcon();
if (response.length() == 0) {
throw new ResponseEmpty();
return response;
private static DatagramPacket getDatagramPacket(String request, InetAddress inet, int port) {
byte first = -1;
byte last = 0;
byte[] buffer = request.getBytes();
byte[] commandBytes = new byte[buffer.length + 5];
commandBytes[0] = first;
commandBytes[1] = first;
commandBytes[2] = first;
commandBytes[3] = first;
for (int i = 0; i < buffer.length; i++) {
commandBytes[i + 4] = buffer[i];
commandBytes[buffer.length + 4] = last;
return new DatagramPacket(commandBytes, commandBytes.length, inet, port);
private static RconPacket[] sendRequest(int localPort, String ipStr, int port, String password,
String command) throws SocketTimeoutException {
DatagramSocket socket = null;
RconPacket[] resp = new RconPacket[128];
try {
socket = new DatagramSocket(localPort);
int packetSize = 1400;
InetAddress address = InetAddress.getByName(ipStr);
byte[] ip = address.getAddress();
InetAddress inet = InetAddress.getByAddress(ip);
String msg = "challenge rcon\n";
DatagramPacket out = getDatagramPacket(msg, inet, port);
socket.send(out);
// get the challenge
byte[] data = new byte[packetSize];
DatagramPacket inPacket = new DatagramPacket(data, packetSize);
socket.setSoTimeout(RESPONSE_TIMEOUT);
socket.receive(inPacket);
// compose the final command and send to the server
String challenge = parseResponse(inPacket.getData());
String challengeNumber = challenge.substring(challenge.indexOf("rcon") + 5).trim();
String commandStr = "rcon " + challengeNumber + " \"" + password + "\" " + command;
DatagramPacket out2 = getDatagramPacket(commandStr, inet, port);
socket.send(out2);
// get the response
byte[] data2 = new byte[packetSize];
DatagramPacket inPacket2 = new DatagramPacket(data2, packetSize);
socket.setSoTimeout(RESPONSE_TIMEOUT);
socket.receive(inPacket2);
resp[0] = new RconPacket(inPacket2);
try {
// Wait for a possible multiple packets response
socket.setSoTimeout(MULTIPLE_PACKETS_TIMEOUT);
int i = 1;
while (true) {
socket.receive(inPacket2);
resp[i++] = new RconPacket(inPacket2);
} catch (SocketTimeoutException sex) {
// Server didn't send more packets
} catch (SocketTimeoutException sex) {
throw sex;
} catch (IOException ex) {
ex.printStackTrace();
} finally {
if (socket != null) {
socket.close();
return resp;
private static String parseResponse(byte[] buf) {
String retVal = "";
if (buf[0] != -1 || buf[1] != -1 || buf[2] != -1 || buf[3] != -1) {
retVal = "ERROR";
} else {
int off = 5;
StringBuffer challenge = new StringBuffer(20);
while (buf[off] != 0) {
challenge.append((char) (buf[off++] & 255));
retVal = challenge.toString();
return retVal;
private static String assemblePacket(RconPacket[] respPacket) {
String resp = "";
// TODO: inspect the headers to decide the correct order
for (int i = 0; i < respPacket.length; i++) {
if (respPacket[i] != null) {
resp = resp.concat(respPacket[i].data);
return resp;
class RconPacket {
* ASCII representation of the full packet received (header included)
public String ascii = "";
* The data included in the packet, header removed
public String data = "";
* The full packet received (header included) in bytes
public byte[] bytes = new byte[1400];
* Length of the packet
public int length = 0;
* Represents a rcon response packet from the game server. A response may be split
* into multiple packets, so an array of RconPackets should be used.
* @param packet One DatagramPacket returned by the server
public RconPacket(DatagramPacket packet) {
this.ascii = new String(packet.getData(), 0, packet.getLength());
this.bytes = ascii.getBytes();
this.length = packet.getLength();
// Now we remove the headers from the packet to have just the text
if (bytes[0] == -2) {
// this response comes divided into two packets
if (bytes[13] == 108) {
this.data = new String(packet.getData(), 14, packet.getLength() - 16);
} else {
this.data = new String(packet.getData(), 11, packet.getLength() - 13);
} else {
// Single packet
this.data = new String(packet.getData(), 5, packet.getLength() - 7);
MyRcon2.java receive command is
127.0.0.1/****/54321/****/password****/command"
if there are more than 1 commands receive at the same time,
SourceRcon.java line 96 will get error
"Couldn't get I/O for the connection: null"
if i change  line 96 to
System.err.println("Couldn't get I/O for the connection: "+ e.getMessage());
it display
Couldn't get I/O for the connection: Invalid argument: JVM_Bind                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                  

Answer 1

InetAddress addr = InetAddress.getLocalHost();
byte[] ipAddr = addr.getAddress();
InetAddress inetLocal = InetAddress.getByAddress(ipAddr);
rconSocket.bind(new InetSocketAddress(inetLocal, localPort));Remove those four lines, or at least save yourself some trouble and set inetLocal to null and localPort to zero.
Why do you want to specify a local bind-address and port? It's not usually done.