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Java example source code file (SocksServer.java)

This example Java source code file (SocksServer.java) is included in the alvinalexander.com "Java Source Code Warehouse" project. The intent of this project is to help you "Learn Java by Example" TM.

Learn more about this Java project at its project page.

Java - Java tags/keywords

clienthandler, connect, inetsocketaddress, inputstream, ioexception, net, network, outputstream, serversocket, socksserver, string, stringbuffer, thread, tunnel, udp_assoc, user_passw, util

The SocksServer.java Java example source code

/*
 * Copyright (c) 2002, 2012, Oracle and/or its affiliates. All rights reserved.
 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
 *
 * This code is free software; you can redistribute it and/or modify it
 * under the terms of the GNU General Public License version 2 only, as
 * published by the Free Software Foundation.
 *
 * This code is distributed in the hope that it will be useful, but WITHOUT
 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
 * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
 * version 2 for more details (a copy is included in the LICENSE file that
 * accompanied this code).
 *
 * You should have received a copy of the GNU General Public License version
 * 2 along with this work; if not, write to the Free Software Foundation,
 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
 *
 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
 * or visit www.oracle.com if you need additional information or have any
 * questions.
 */
import java.net.*;
import java.io.*;
import java.util.HashMap;

public class SocksServer extends Thread {
    // Some useful SOCKS constant

    static final int PROTO_VERS4        = 4;
    static final int PROTO_VERS         = 5;
    static final int DEFAULT_PORT       = 1080;

    static final int NO_AUTH            = 0;
    static final int GSSAPI             = 1;
    static final int USER_PASSW         = 2;
    static final int NO_METHODS         = -1;

    static final int CONNECT            = 1;
    static final int BIND               = 2;
    static final int UDP_ASSOC          = 3;

    static final int IPV4               = 1;
    static final int DOMAIN_NAME        = 3;
    static final int IPV6               = 4;

    static final int REQUEST_OK         = 0;
    static final int GENERAL_FAILURE    = 1;
    static final int NOT_ALLOWED        = 2;
    static final int NET_UNREACHABLE    = 3;
    static final int HOST_UNREACHABLE   = 4;
    static final int CONN_REFUSED       = 5;
    static final int TTL_EXPIRED        = 6;
    static final int CMD_NOT_SUPPORTED  = 7;
    static final int ADDR_TYPE_NOT_SUP  = 8;

    private int port;
    private ServerSocket server;
    private boolean useV4 = false;
    private HashMap<String,String> users = new HashMap<>();
    private volatile boolean done = false;
    // Inner class to handle protocol with client
    // This is the bulk of the work (protocol handler)
    class ClientHandler extends Thread {
        private InputStream in;
        private OutputStream out;
        private Socket client;
        private Socket dest;

        // Simple tunneling class, moving bits from one stream to another

        class Tunnel extends Thread {
            private InputStream tin;
            private OutputStream tout;

            Tunnel(InputStream in, OutputStream out) {
                tin = in;
                tout = out;
            }

            public void run() {
                int b;
                while (true) {
                    try {
                        b = tin.read();
                        if (b == -1) {
                            tin.close();
                            tout.close();
                            return;
                        }
                        tout.write(b);
                    } catch (IOException e) {
                        // actually exit from the thread
                        return;
                    }
                }
            }
        }

        ClientHandler(Socket s) throws IOException {
            client = s;
            in = client.getInputStream();
            out = client.getOutputStream();
        }

        private void readBuf(InputStream is, byte[] buf) throws IOException {
            int l = buf.length;
            int count = 0;
            int i;
            do {
                i = is.read(buf, count, l - count);
                if (i == -1)
                    throw new IOException("unexpected EOF");
                count += i;
            } while (count < l);
        }


        private boolean userPassAuth() throws IOException {
            int ver = in.read();
            int ulen = in.read();
            if (ulen <= 0)
                throw new SocketException("SOCKS protocol error");
            byte[] buf = new byte[ulen];
            readBuf(in, buf);
            String uname = new String(buf);
            String password = null;
            ulen = in.read();
            if (ulen < 0)
                throw new SocketException("SOCKS protocol error");
            if (ulen > 0) {
                buf = new byte[ulen];
                readBuf(in, buf);
                password = new String(buf);
            }
            // Check username/password validity here
            System.err.println("User: '" + uname);
            System.err.println("PSWD: '" + password);
            if (users.containsKey(uname)) {
                String p1 = users.get(uname);
                System.err.println("p1 = " + p1);
                if (p1.equals(password)) {
                    out.write(PROTO_VERS);
                    out.write(REQUEST_OK);
                    out.flush();
                    return true;
                }
            }
            out.write(PROTO_VERS);
            out.write(NOT_ALLOWED);
            out.flush();
            return false;
        }

        private void purge() throws IOException {
            boolean done = false;
            int i = 0;
            client.setSoTimeout(1000);
            while(!done && i != -1) {
                try {
                    i = in.read();
                } catch(IOException e) {
                    done = true;
                }
            }
        }


        // Handle the SOCKS version 4 protocl

        private void getRequestV4() throws IOException {
            int ver = in.read();
            int cmd = in.read();
            if (ver == -1 || cmd == -1) {
                // EOF
                in.close();
                out.close();
                return;
            }

            if (ver != 0 && ver != 4) {
                out.write(PROTO_VERS4);
                out.write(91); // Bad Request
                out.write(0);
                out.write(0);
                out.write(0);
                out.write(0);
                out.write(0);
                out.write(0);
                out.write(0);
                out.flush();
                purge();
                out.close();
                in.close();
                return;
            }

            if (cmd == CONNECT) {
                int port = ((in.read() & 0xff) << 8);
                port += (in.read() & 0xff);
                byte[] buf = new byte[4];
                readBuf(in, buf);
                InetAddress addr = InetAddress.getByAddress(buf);
                // We don't use the username...
                int c;
                do {
                    c = (in.read() & 0xff);
                } while (c!=0);
                boolean ok = true;
                try {
                    dest = new Socket(addr, port);
                } catch (IOException e) {
                    ok = false;
                }
                if (!ok) {
                    out.write(PROTO_VERS4);
                    out.write(91);
                    out.write(0);
                    out.write(0);
                    out.write(buf);
                    out.flush();
                    purge();
                    out.close();
                    in.close();
                    return;
                }
                out.write(PROTO_VERS4);
                out.write(90); // Success
                out.write((port >> 8) & 0xff);
                out.write(port & 0xff);
                out.write(buf);
                out.flush();
                InputStream in2 = dest.getInputStream();
                OutputStream out2 = dest.getOutputStream();

                Tunnel tunnel = new Tunnel(in2, out);
                tunnel.start();

                int b = 0;
                do {
                    try {
                        b = in.read();
                        if (b == -1) {
                            in.close();
                            out2.close();
                            return;
                        }
                        out2.write(b);
                    } catch (IOException ex) {
                    }
                } while (!client.isClosed());
            }
        }


        // Negociate the authentication scheme with the client
        private void negociate() throws IOException {
            int ver = in.read();
            int n = in.read();
            byte[] buf = null;
            if (n > 0) {
                buf = new byte[n];
                readBuf(in, buf);
            }
            int scheme = NO_AUTH;
            for (int i = 0; i < n; i++)
                if (buf[i] == USER_PASSW)
                    scheme = USER_PASSW;
            out.write(PROTO_VERS);
            out.write(scheme);
            out.flush();
            if (scheme == USER_PASSW)
                userPassAuth();
        }

        // Send error message then close the streams
        private void sendError(int code) {
            try {
                out.write(PROTO_VERS);
                out.write(code);
                out.write(0);
                out.write(IPV4);
                for (int i=0; i<6; i++)
                    out.write(0);
                out.flush();
                out.close();
            } catch (IOException ex) {
            }
        }

        // Actually connect the proxy to the destination then initiate tunneling

        private void doConnect(InetSocketAddress addr) throws IOException {
            dest = new Socket();
            try {
                dest.connect(addr, 10000);
            } catch (SocketTimeoutException ex) {
                sendError(HOST_UNREACHABLE);
                return;
            } catch (ConnectException cex) {
                sendError(CONN_REFUSED);
                return;
            }
            // Success
            InetAddress iadd = addr.getAddress();
            if (iadd instanceof Inet4Address) {
                out.write(PROTO_VERS);
                out.write(REQUEST_OK);
                out.write(0);
                out.write(IPV4);
                out.write(iadd.getAddress());
            } else if (iadd instanceof Inet6Address) {
                out.write(PROTO_VERS);
                out.write(REQUEST_OK);
                out.write(0);
                out.write(IPV6);
                out.write(iadd.getAddress());
            } else {
                sendError(GENERAL_FAILURE);
                return;
            }
            out.write((addr.getPort() >> 8) & 0xff);
            out.write((addr.getPort() >> 0) & 0xff);
            out.flush();

            InputStream in2 = dest.getInputStream();
            OutputStream out2 = dest.getOutputStream();

            Tunnel tunnel = new Tunnel(in2, out);
            tunnel.start();

            int b = 0;
            do {
                // Note that the socket might be closed from another thread (the tunnel)
                try {
                    b = in.read();
                    if (b == -1) {
                        in.close();
                        out2.close();
                        return;
                    }
                    out2.write(b);
                } catch(IOException ioe) {
                }
            } while (!client.isClosed());
        }

        private void doBind(InetSocketAddress addr) throws IOException {
            ServerSocket svr = new ServerSocket();
            svr.bind(null);
            InetSocketAddress bad = (InetSocketAddress) svr.getLocalSocketAddress();
            out.write(PROTO_VERS);
            out.write(REQUEST_OK);
            out.write(0);
            out.write(IPV4);
            out.write(bad.getAddress().getAddress());
            out.write((bad.getPort() >> 8) & 0xff);
            out.write((bad.getPort() & 0xff));
            out.flush();
            dest = svr.accept();
            bad = (InetSocketAddress) dest.getRemoteSocketAddress();
            out.write(PROTO_VERS);
            out.write(REQUEST_OK);
            out.write(0);
            out.write(IPV4);
            out.write(bad.getAddress().getAddress());
            out.write((bad.getPort() >> 8) & 0xff);
            out.write((bad.getPort() & 0xff));
            out.flush();
            InputStream in2 = dest.getInputStream();
            OutputStream out2 = dest.getOutputStream();

            Tunnel tunnel = new Tunnel(in2, out);
            tunnel.start();

            int b = 0;
            do {
                // Note that the socket might be close from another thread (the tunnel)
                try {
                    b = in.read();
                    if (b == -1) {
                        in.close();
                        out2.close();
                        return;
                    }
                    out2.write(b);
                } catch(IOException ioe) {
                }
            } while (!client.isClosed());

        }

        // Handle the SOCKS v5 requests

        private void getRequest() throws IOException {
            int ver = in.read();
            int cmd = in.read();
            if (ver == -1 || cmd == -1) {
                in.close();
                out.close();
                return;
            }
            int rsv = in.read();
            int atyp = in.read();
            String addr = null;
            int port = 0;

            switch(atyp) {
            case IPV4:
                {
                byte[] buf = new byte[4];
                readBuf(in, buf);
                int i = 0;
                StringBuffer sb = new StringBuffer();
                for (i = 0; i < 4; i++) {
                    sb.append(buf[i]&0xff);
                    if (i < 3)
                        sb.append('.');
                }
                addr = sb.toString();
                }
                break;
            case DOMAIN_NAME:
                {
                int i = in.read();
                byte[] buf = new byte[i];
                readBuf(in, buf);
                addr = new String(buf);
                }
                break;
            case IPV6:
                {
                byte[] buf = new byte[16];
                readBuf(in, buf);
                int i = 0;
                StringBuffer sb = new StringBuffer();
                for (i = 0; i<16; i++) {
                    sb.append(Integer.toHexString(buf[i]&0xff));
                    if (i < 15)
                        sb.append(':');
                }
                addr = sb.toString();
                }
                break;
            }

            port = ((in.read()&0xff) << 8);
            port += (in.read()&0xff);

            InetSocketAddress socAddr = new InetSocketAddress(addr, port);
            switch(cmd) {
            case CONNECT:
                doConnect(socAddr);
                break;
            case BIND:
                doBind(socAddr);
                break;
            case UDP_ASSOC:
                // doUDP(socAddr);
                break;
            }
        }

        public void run() {
            String line = null;
            try {
                if (useV4) {
                    getRequestV4();
                } else {
                    negociate();
                    getRequest();
                }
            } catch (IOException ex) {
                try {
                    sendError(GENERAL_FAILURE);
                } catch (Exception e) {
                }
            } finally {
                try {
                    client.close();
                } catch (IOException e2) {
                }
            }
        }

    }

    public SocksServer(int port, boolean v4) throws IOException {
        this(port);
        this.useV4 = v4;
    }

    public SocksServer(int port) throws IOException {
        this.port = port;
        server = new ServerSocket();
        if (port == 0) {
            server.bind(null);
            this.port = server.getLocalPort();
        } else {
            server.bind(new InetSocketAddress(port));
        }
    }

    public SocksServer() throws IOException {
        this (DEFAULT_PORT);
    }

    public void addUser(String user, String passwd) {
        users.put(user, passwd);
    }

    public int getPort() {
        return port;
    }

    public void terminate() {
        done = true;
        try { server.close(); } catch (IOException unused) {}
    }

    public void run() {
        ClientHandler cl = null;
        while (!done) {
            try {
                Socket s = server.accept();
                cl = new ClientHandler(s);
                cl.start();
            } catch (IOException ex) {
                if (cl != null)
                    cl.interrupt();
            }
        }
    }
}

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