001/*
002 *  Licensed to the Apache Software Foundation (ASF) under one
003 *  or more contributor license agreements.  See the NOTICE file
004 *  distributed with this work for additional information
005 *  regarding copyright ownership.  The ASF licenses this file
006 *  to you under the Apache License, Version 2.0 (the
007 *  "License"); you may not use this file except in compliance
008 *  with the License.  You may obtain a copy of the License at
009 *
010 *    http://www.apache.org/licenses/LICENSE-2.0
011 *
012 *  Unless required by applicable law or agreed to in writing,
013 *  software distributed under the License is distributed on an
014 *  "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
015 *  KIND, either express or implied.  See the License for the
016 *  specific language governing permissions and limitations
017 *  under the License.
018 *
019 */
020package org.apache.mina.proxy.handlers.socks;
021
022import java.util.Arrays;
023
024import org.apache.mina.core.buffer.IoBuffer;
025import org.apache.mina.core.filterchain.IoFilter.NextFilter;
026import org.apache.mina.proxy.session.ProxyIoSession;
027import org.apache.mina.proxy.utils.ByteUtilities;
028import org.slf4j.Logger;
029import org.slf4j.LoggerFactory;
030
031/**
032 * Socks4LogicHandler.java - SOCKS4/SOCKS4a authentication mechanisms logic handler.
033 * 
034 * @author <a href="http://mina.apache.org">Apache MINA Project</a>
035 * @since MINA 2.0.0-M3
036 */
037public class Socks4LogicHandler extends AbstractSocksLogicHandler {
038
039    private final static Logger logger = LoggerFactory.getLogger(Socks4LogicHandler.class);
040
041    /**
042     * @see AbstractSocksLogicHandler#AbstractSocksLogicHandler(ProxyIoSession)
043     * 
044     * @param proxyIoSession The original session
045     */
046    public Socks4LogicHandler(final ProxyIoSession proxyIoSession) {
047        super(proxyIoSession);
048    }
049
050    /**
051     * Perform the handshake.
052     * 
053     * @param nextFilter the next filter
054     */
055    public void doHandshake(final NextFilter nextFilter) {
056        logger.debug(" doHandshake()");
057
058        // Send request
059        writeRequest(nextFilter, request);
060    }
061
062    /**
063     * Encode a SOCKS4/SOCKS4a request and writes it to the next filter
064     * so it can be sent to the proxy server.
065     * 
066     * @param nextFilter the next filter
067     * @param request the request to send.
068     */
069    protected void writeRequest(final NextFilter nextFilter, final SocksProxyRequest request) {
070        try {
071            boolean isV4ARequest = Arrays.equals(request.getIpAddress(), SocksProxyConstants.FAKE_IP);
072            byte[] userID = request.getUserName().getBytes("ASCII");
073            byte[] host = isV4ARequest ? request.getHost().getBytes("ASCII") : null;
074
075            int len = 9 + userID.length;
076
077            if (isV4ARequest) {
078                len += host.length + 1;
079            }
080
081            IoBuffer buf = IoBuffer.allocate(len);
082
083            buf.put(request.getProtocolVersion());
084            buf.put(request.getCommandCode());
085            buf.put(request.getPort());
086            buf.put(request.getIpAddress());
087            buf.put(userID);
088            buf.put(SocksProxyConstants.TERMINATOR);
089
090            if (isV4ARequest) {
091                buf.put(host);
092                buf.put(SocksProxyConstants.TERMINATOR);
093            }
094
095            if (isV4ARequest) {
096                logger.debug("  sending SOCKS4a request");
097            } else {
098                logger.debug("  sending SOCKS4 request");
099            }
100
101            buf.flip();
102            writeData(nextFilter, buf);
103        } catch (Exception ex) {
104            closeSession("Unable to send Socks request: ", ex);
105        }
106    }
107
108    /**
109     * Handle incoming data during the handshake process. Should consume only the
110     * handshake data from the buffer, leaving any extra data in place.
111     * 
112     * @param nextFilter the next filter
113     * @param buf the server response data buffer
114     */
115    public void messageReceived(final NextFilter nextFilter, final IoBuffer buf) {
116        try {
117            if (buf.remaining() >= SocksProxyConstants.SOCKS_4_RESPONSE_SIZE) {
118                handleResponse(buf);
119            }
120        } catch (Exception ex) {
121            closeSession("Proxy handshake failed: ", ex);
122        }
123    }
124
125    /**
126     * Handle a SOCKS4/SOCKS4a response from the proxy server. Test
127     * the response buffer reply code and call {@link #setHandshakeComplete()}
128     * if access is granted.
129     * 
130     * @param buf the buffer holding the server response data.
131     * @throws Exception if server response is malformed or if request is rejected
132     * by the proxy server.
133     */
134    protected void handleResponse(final IoBuffer buf) throws Exception {
135        byte first = buf.get(0);
136
137        if (first != 0) {
138            throw new Exception("Socks response seems to be malformed");
139        }
140
141        byte status = buf.get(1);
142
143        // Consumes all the response data from the buffer
144        buf.position(buf.position() + SocksProxyConstants.SOCKS_4_RESPONSE_SIZE);
145
146        if (status == SocksProxyConstants.V4_REPLY_REQUEST_GRANTED) {
147            setHandshakeComplete();
148        } else {
149            throw new Exception("Proxy handshake failed - Code: 0x" + ByteUtilities.asHex(new byte[] { status }) + " ("
150                    + SocksProxyConstants.getReplyCodeAsString(status) + ")");
151        }
152    }
153}