/*
 * Copyright (c) 2002-2018 ymnk, JCraft,Inc. All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without modification, are permitted
 * provided that the following conditions are met:
 *
 * 1. Redistributions of source code must retain the above copyright notice, this list of conditions
 * and the following disclaimer.
 *
 * 2. Redistributions in binary form must reproduce the above copyright notice, this list of
 * conditions and the following disclaimer in the documentation and/or other materials provided with
 * the distribution.
 *
 * 3. The names of the authors may not be used to endorse or promote products derived from this
 * software without specific prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED ``AS IS'' AND ANY EXPRESSED OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
 * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
 * DISCLAIMED. IN NO EVENT SHALL JCRAFT, INC. OR ANY CONTRIBUTORS TO THIS SOFTWARE BE LIABLE FOR ANY
 * DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
 * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR
 * BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
 * SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 */

/*
This file depends on following documents:
  - RFC 1928  SOCKS Protocol Verseion 5
  - RFC 1929  Username/Password Authentication for SOCKS V5.
*/

package com.jcraft.jsch;

import java.io.IOException;
import java.io.InputStream;
import java.io.OutputStream;
import java.net.Socket;

public class ProxySOCKS5 implements Proxy {
  private static int DEFAULTPORT = 1080;
  private String proxy_host;
  private int proxy_port;
  private InputStream in;
  private OutputStream out;
  private Socket socket;
  private String user;
  private String passwd;

  public ProxySOCKS5(String proxy_host) {
    int port = DEFAULTPORT;
    String host = proxy_host;
    if (proxy_host.indexOf(':') != -1) {
      try {
        host = proxy_host.substring(0, proxy_host.indexOf(':'));
        port = Integer.parseInt(proxy_host.substring(proxy_host.indexOf(':') + 1));
      } catch (Exception e) {
      }
    }
    this.proxy_host = host;
    this.proxy_port = port;
  }

  public ProxySOCKS5(String proxy_host, int proxy_port) {
    this.proxy_host = proxy_host;
    this.proxy_port = proxy_port;
  }

  public void setUserPasswd(String user, String passwd) {
    this.user = user;
    this.passwd = passwd;
  }

  @Override
  public void connect(SocketFactory socket_factory, String host, int port, int timeout)
      throws JSchException {
    try {
      if (socket_factory == null) {
        socket = Util.createSocket(proxy_host, proxy_port, timeout);
        // socket=new Socket(proxy_host, proxy_port);
        in = socket.getInputStream();
        out = socket.getOutputStream();
      } else {
        socket = socket_factory.createSocket(proxy_host, proxy_port);
        in = socket_factory.getInputStream(socket);
        out = socket_factory.getOutputStream(socket);
      }
      if (timeout > 0) {
        socket.setSoTimeout(timeout);
      }
      socket.setTcpNoDelay(true);

      byte[] buf = new byte[1024];
      int index = 0;

      /*
                      +----+----------+----------+
                      |VER | NMETHODS | METHODS  |
                      +----+----------+----------+
                      | 1  |    1     | 1 to 255 |
                      +----+----------+----------+

      The VER field is set to X'05' for this version of the protocol.  The
      NMETHODS field contains the number of method identifier octets that
      appear in the METHODS field.

      The values currently defined for METHOD are:

             o  X'00' NO AUTHENTICATION REQUIRED
             o  X'01' GSSAPI
             o  X'02' USERNAME/PASSWORD
             o  X'03' to X'7F' IANA ASSIGNED
             o  X'80' to X'FE' RESERVED FOR PRIVATE METHODS
             o  X'FF' NO ACCEPTABLE METHODS
      */

      buf[index++] = 5;

      buf[index++] = 2;
      buf[index++] = 0; // NO AUTHENTICATION REQUIRED
      buf[index++] = 2; // USERNAME/PASSWORD

      out.write(buf, 0, index);

      /*
      The server selects from one of the methods given in METHODS, and
      sends a METHOD selection message:

                            +----+--------+
                            |VER | METHOD |
                            +----+--------+
                            | 1  |   1    |
                            +----+--------+
      */
      // in.read(buf, 0, 2);
      fill(in, buf, 2);

      boolean check = false;
      switch ((buf[1]) & 0xff) {
        case 0: // NO AUTHENTICATION REQUIRED
          check = true;
          break;
        case 2: // USERNAME/PASSWORD
          if (user == null || passwd == null)
            break;

          /*
          Once the SOCKS V5 server has started, and the client has selected the
          Username/Password Authentication protocol, the Username/Password
          subnegotiation begins.  This begins with the client producing a
          Username/Password request:

                  +----+------+----------+------+----------+
                  |VER | ULEN |  UNAME   | PLEN |  PASSWD  |
                  +----+------+----------+------+----------+
                  | 1  |  1   | 1 to 255 |  1   | 1 to 255 |
                  +----+------+----------+------+----------+

          The VER field contains the current version of the subnegotiation,
          which is X'01'. The ULEN field contains the length of the UNAME field
          that follows. The UNAME field contains the username as known to the
          source operating system. The PLEN field contains the length of the
          PASSWD field that follows. The PASSWD field contains the password
          association with the given UNAME.
          */
          index = 0;
          buf[index++] = 1;
          buf[index++] = (byte) (user.length());
          System.arraycopy(Util.str2byte(user), 0, buf, index, user.length());
          index += user.length();
          buf[index++] = (byte) (passwd.length());
          System.arraycopy(Util.str2byte(passwd), 0, buf, index, passwd.length());
          index += passwd.length();

          out.write(buf, 0, index);

          /*
          The server verifies the supplied UNAME and PASSWD, and sends the
          following response:

                               +----+--------+
                               |VER | STATUS |
                               +----+--------+
                               | 1  |   1    |
                               +----+--------+

          A STATUS field of X'00' indicates success. If the server returns a
          `failure' (STATUS value other than X'00') status, it MUST close the
          connection.
          */
          // in.read(buf, 0, 2);
          fill(in, buf, 2);
          if (buf[1] == 0)
            check = true;
          break;
        default:
      }

      if (!check) {
        try {
          socket.close();
        } catch (Exception eee) {
        }
        throw new JSchProxyException("fail in SOCKS5 proxy");
      }

      /*
      The SOCKS request is formed as follows:

           +----+-----+-------+------+----------+----------+
           |VER | CMD |  RSV  | ATYP | DST.ADDR | DST.PORT |
           +----+-----+-------+------+----------+----------+
           | 1  |  1  | X'00' |  1   | Variable |    2     |
           +----+-----+-------+------+----------+----------+

        Where:

             o  VER    protocol version: X'05'
             o  CMD
                o  CONNECT X'01'
                o  BIND X'02'
                o  UDP ASSOCIATE X'03'
             o  RSV    RESERVED
             o  ATYP   address type of following address
                o  IP V4 address: X'01'
                o  DOMAINNAME: X'03'
                o  IP V6 address: X'04'
             o  DST.ADDR       desired destination address
             o  DST.PORT desired destination port in network octet
                order
      */

      index = 0;
      buf[index++] = 5;
      buf[index++] = 1; // CONNECT
      buf[index++] = 0;

      byte[] hostb = Util.str2byte(host);
      int len = hostb.length;
      buf[index++] = 3; // DOMAINNAME
      buf[index++] = (byte) (len);
      System.arraycopy(hostb, 0, buf, index, len);
      index += len;
      buf[index++] = (byte) (port >>> 8);
      buf[index++] = (byte) (port & 0xff);

      out.write(buf, 0, index);

      /*
      The SOCKS request information is sent by the client as soon as it has
      established a connection to the SOCKS server, and completed the
      authentication negotiations.  The server evaluates the request, and
      returns a reply formed as follows:

           +----+-----+-------+------+----------+----------+
           |VER | REP |  RSV  | ATYP | BND.ADDR | BND.PORT |
           +----+-----+-------+------+----------+----------+
           | 1  |  1  | X'00' |  1   | Variable |    2     |
           +----+-----+-------+------+----------+----------+

        Where:

             o  VER    protocol version: X'05'
             o  REP    Reply field:
                o  X'00' succeeded
                o  X'01' general SOCKS server failure
                o  X'02' connection not allowed by ruleset
                o  X'03' Network unreachable
                o  X'04' Host unreachable
                o  X'05' Connection refused
                o  X'06' TTL expired
                o  X'07' Command not supported
                o  X'08' Address type not supported
                o  X'09' to X'FF' unassigned
             o  RSV    RESERVED
             o  ATYP   address type of following address
                o  IP V4 address: X'01'
                o  DOMAINNAME: X'03'
                o  IP V6 address: X'04'
             o  BND.ADDR       server bound address
             o  BND.PORT       server bound port in network octet order
      */


      // in.read(buf, 0, 4);
      fill(in, buf, 4);

      if (buf[1] != 0) {
        try {
          socket.close();
        } catch (Exception eee) {
        }
        throw new JSchProxyException("ProxySOCKS5: server returns " + buf[1]);
      }

      switch (buf[3] & 0xff) {
        case 1:
          // in.read(buf, 0, 6);
          fill(in, buf, 6);
          break;
        case 3:
          // in.read(buf, 0, 1);
          fill(in, buf, 1);
          // in.read(buf, 0, buf[0]+2);
          fill(in, buf, (buf[0] & 0xff) + 2);
          break;
        case 4:
          // in.read(buf, 0, 18);
          fill(in, buf, 18);
          break;
        default:
      }
    } catch (RuntimeException e) {
      throw e;
    } catch (Exception e) {
      try {
        if (socket != null)
          socket.close();
      } catch (Exception eee) {
      }
      String message = "ProxySOCKS5: " + e.toString();
      throw new JSchProxyException(message, e);
    }
  }

  @Override
  public InputStream getInputStream() {
    return in;
  }

  @Override
  public OutputStream getOutputStream() {
    return out;
  }

  @Override
  public Socket getSocket() {
    return socket;
  }

  @Override
  public void close() {
    try {
      if (in != null)
        in.close();
      if (out != null)
        out.close();
      if (socket != null)
        socket.close();
    } catch (Exception e) {
    }
    in = null;
    out = null;
    socket = null;
  }

  public static int getDefaultPort() {
    return DEFAULTPORT;
  }

  private void fill(InputStream in, byte[] buf, int len) throws JSchException, IOException {
    int s = 0;
    while (s < len) {
      int i = in.read(buf, s, len - s);
      if (i <= 0) {
        throw new JSchProxyException("ProxySOCKS5: stream is closed");
      }
      s += i;
    }
  }
}
