/*
 * ftp4j - A pure Java FTP client library
 * 
 * Copyright (C) 2008-2010 Carlo Pelliccia (www.sauronsoftware.it)
 * 
 * This program is free software: you can redistribute it and/or modify
 * it under the terms of the GNU Lesser General Public License version
 * 2.1, as published by the Free Software Foundation.
 *
 * This program 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 Lesser General Public License 2.1 for more details.
 *
 * You should have received a copy of the GNU Lesser General Public
 * License version 2.1 along with this program.
 * If not, see <http://www.gnu.org/licenses/>.
 */
package it.sauronsoftware.ftp4j.connectors;

import it.sauronsoftware.ftp4j.FTPConnector;

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

/**
 * This one connects a remote ftp host through a SOCKS5 proxy server.
 * 
 * The connector's default value for the
 * <em>useSuggestedAddressForDataConnections</em> flag is <em>false</em>.
 * 
 * @author Carlo Pelliccia
 */
public class SOCKS5Connector extends FTPConnector {

	/**
	 * The socks5 proxy host name.
	 */
	private String socks5host;

	/**
	 * The socks5 proxy port.
	 */
	private int socks5port;

	/**
	 * The socks5 proxy user (optional).
	 */
	private String socks5user;

	/**
	 * The socks5 proxy password (optional).
	 */
	private String socks5pass;

	/**
	 * It builds the connector.
	 * 
	 * @param socks5host
	 *            The socks5 proxy host name.
	 * @param socks5port
	 *            The socks5 proxy port.
	 * @param socks5user
	 *            The socks5 proxy user (optional, can be set to null).
	 * @param socks5pass
	 *            The socks5 proxy password (optional, can be set to null if
	 *            also socks5user is null).
	 */
	public SOCKS5Connector(String socks5host, int socks5port,
			String socks5user, String socks5pass) {
		this.socks5host = socks5host;
		this.socks5port = socks5port;
		this.socks5user = socks5user;
		this.socks5pass = socks5pass;
	}

	/**
	 * It builds the connector.
	 * 
	 * @param socks5host
	 *            The socks5 proxy host name.
	 * @param socks5port
	 *            The socks5 proxy port.
	 */
	public SOCKS5Connector(String socks5host, int socks5port) {
		this(socks5host, socks5port, null, null);
	}

	private Socket socksConnect(String host, int port, boolean forDataTransfer) throws IOException {
		// Authentication flag
		boolean authentication = socks5user != null && socks5pass != null;
		// A connection status flag.
		boolean connected = false;
		// The socket for the connection with the proxy.
		Socket socket = null;
		InputStream in = null;
		OutputStream out = null;
		// FTPConnection routine.
		try {
			if (forDataTransfer) {
				socket = tcpConnectForDataTransferChannel(socks5host, socks5port);
			} else {
				socket = tcpConnectForCommunicationChannel(socks5host, socks5port);
			}
			in = socket.getInputStream();
			out = socket.getOutputStream();
			int aux;
			// Version 5.
			out.write(0x05);
			// Authentication?
			if (authentication) {
				// Authentication with username/password.
				out.write(0x01);
				out.write(0x02);
			} else {
				// No authentication.
				out.write(0x01);
				out.write(0x00);
			}
			// Get the response.
			aux = read(in);
			if (aux != 0x05) {
				throw new IOException("SOCKS5Connector: invalid proxy response");
			}
			aux = read(in);
			if (authentication) {
				if (aux != 0x02) {
					throw new IOException(
							"SOCKS5Connector: proxy doesn't support "
									+ "username/password authentication method");
				}
				// Authentication with username/password.
				byte[] user = socks5user.getBytes("UTF-8");
				byte[] pass = socks5pass.getBytes("UTF-8");
				int userLength = user.length;
				int passLength = pass.length;
				// Check sizes.
				if (userLength > 0xff) {
					throw new IOException("SOCKS5Connector: username too long");
				}
				if (passLength > 0xff) {
					throw new IOException("SOCKS5Connector: password too long");
				}
				// Version 1.
				out.write(0x01);
				// Username.
				out.write(userLength);
				out.write(user);
				// Password.
				out.write(passLength);
				out.write(pass);
				// Check the response.
				aux = read(in);
				if (aux != 0x01) {
					throw new IOException(
							"SOCKS5Connector: invalid proxy response");
				}
				aux = read(in);
				if (aux != 0x00) {
					throw new IOException(
							"SOCKS5Connector: authentication failed");
				}
			} else {
				if (aux != 0x00) {
					throw new IOException(
							"SOCKS5Connector: proxy requires authentication");
				}
			}
			// FTPConnection request.
			// Version 5.
			out.write(0x05);
			// CONNECT method
			out.write(0x01);
			// Reserved.
			out.write(0x00);
			// Address type -> domain.
			out.write(0x03);
			// Domain.
			byte[] domain = host.getBytes("UTF-8");
			if (domain.length > 0xff) {
				throw new IOException("SOCKS5Connector: domain name too long");
			}
			out.write(domain.length);
			out.write(domain);
			// Port number.
			out.write(port >> 8);
			out.write(port);

			// FTPConnection response
			// Version?
			aux = read(in);
			if (aux != 0x05) {
				throw new IOException("SOCKS5Connector: invalid proxy response");
			}
			// Status?
			aux = read(in);
			switch (aux) {
			case 0x00:
				// Connected!
				break;
			case 0x01:
				throw new IOException("SOCKS5Connector: general failure");
			case 0x02:
				throw new IOException(
						"SOCKS5Connector: connection not allowed by ruleset");
			case 0x03:
				throw new IOException("SOCKS5Connector: network unreachable");
			case 0x04:
				throw new IOException("SOCKS5Connector: host unreachable");
			case 0x05:
				throw new IOException(
						"SOCKS5Connector: connection refused by destination host");
			case 0x06:
				throw new IOException("SOCKS5Connector: TTL expired");
			case 0x07:
				throw new IOException(
						"SOCKS5Connector: command not supported / protocol error");
			case 0x08:
				throw new IOException(
						"SOCKS5Connector: address type not supported");
			default:
				throw new IOException("SOCKS5Connector: invalid proxy response");
			}
			// Reserved.
			in.skip(1);
			// Address type.
			aux = read(in);
			if (aux == 0x01) {
				// IPv4.
				in.skip(4);
			} else if (aux == 0x03) {
				// Domain name.
				aux = read(in);
				in.skip(aux);
			} else if (aux == 0x04) {
				// IPv6.
				in.skip(16);
			} else {
				throw new IOException("SOCKS5Connector: invalid proxy response");
			}
			// Port number.
			in.skip(2);
			// Well done!
			connected = true;
		} catch (IOException e) {
			throw e;
		} finally {
			if (!connected) {
				if (out != null) {
					try {
						out.close();
					} catch (Throwable t) {
						;
					}
				}
				if (in != null) {
					try {
						in.close();
					} catch (Throwable t) {
						;
					}
				}
				if (socket != null) {
					try {
						socket.close();
					} catch (Throwable t) {
						;
					}
				}
			}
		}
		return socket;
	}

	private int read(InputStream in) throws IOException {
		int aux = in.read();
		if (aux < 0) {
			throw new IOException(
					"SOCKS5Connector: connection closed by the proxy");
		}
		return aux;
	}

	public Socket connectForCommunicationChannel(String host, int port)
			throws IOException {
		return socksConnect(host, port, false);
	}

	public Socket connectForDataTransferChannel(String host, int port)
			throws IOException {
		return socksConnect(host, port, true);
	}

}