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Java example source code file (Socks5ProxyHandler.java)

This example Java source code file (Socks5ProxyHandler.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

auth_password, exception, init_request_password, net, network, object, override, protocol, proxyconnectexception, socks5authmethod, socks5commandresponse, socks5initialresponse, socks5initialresponsedecoder, socks5passwordauthresponse, socks5proxyhandler, string, util

The Socks5ProxyHandler.java Java example source code

/*
 * Copyright 2014 The Netty Project
 *
 * The Netty Project licenses this file to you under the Apache License,
 * version 2.0 (the "License"); you may not use this file except in compliance
 * with the License. You may obtain a copy of the License at:
 *
 *   http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
 * WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the
 * License for the specific language governing permissions and limitations
 * under the License.
 */

package io.netty.handler.proxy;

import io.netty.channel.ChannelHandlerContext;
import io.netty.channel.ChannelPipeline;
import io.netty.handler.codec.socksx.v5.DefaultSocks5InitialRequest;
import io.netty.handler.codec.socksx.v5.DefaultSocks5CommandRequest;
import io.netty.handler.codec.socksx.v5.DefaultSocks5PasswordAuthRequest;
import io.netty.handler.codec.socksx.v5.Socks5AddressType;
import io.netty.handler.codec.socksx.v5.Socks5AuthMethod;
import io.netty.handler.codec.socksx.v5.Socks5InitialRequest;
import io.netty.handler.codec.socksx.v5.Socks5InitialResponse;
import io.netty.handler.codec.socksx.v5.Socks5InitialResponseDecoder;
import io.netty.handler.codec.socksx.v5.Socks5ClientEncoder;
import io.netty.handler.codec.socksx.v5.Socks5CommandResponse;
import io.netty.handler.codec.socksx.v5.Socks5CommandResponseDecoder;
import io.netty.handler.codec.socksx.v5.Socks5CommandStatus;
import io.netty.handler.codec.socksx.v5.Socks5CommandType;
import io.netty.handler.codec.socksx.v5.Socks5PasswordAuthResponse;
import io.netty.handler.codec.socksx.v5.Socks5PasswordAuthResponseDecoder;
import io.netty.handler.codec.socksx.v5.Socks5PasswordAuthStatus;
import io.netty.util.NetUtil;
import io.netty.util.internal.StringUtil;

import java.net.InetSocketAddress;
import java.net.SocketAddress;
import java.util.Arrays;
import java.util.Collections;

public final class Socks5ProxyHandler extends ProxyHandler {

    private static final String PROTOCOL = "socks5";
    private static final String AUTH_PASSWORD = "password";

    private static final Socks5InitialRequest INIT_REQUEST_NO_AUTH =
            new DefaultSocks5InitialRequest(Collections.singletonList(Socks5AuthMethod.NO_AUTH));

    private static final Socks5InitialRequest INIT_REQUEST_PASSWORD =
            new DefaultSocks5InitialRequest(Arrays.asList(Socks5AuthMethod.NO_AUTH, Socks5AuthMethod.PASSWORD));

    private final String username;
    private final String password;

    private String decoderName;
    private String encoderName;

    public Socks5ProxyHandler(SocketAddress proxyAddress) {
        this(proxyAddress, null, null);
    }

    public Socks5ProxyHandler(SocketAddress proxyAddress, String username, String password) {
        super(proxyAddress);
        if (username != null && username.length() == 0) {
            username = null;
        }
        if (password != null && password.length() == 0) {
            password = null;
        }
        this.username = username;
        this.password = password;
    }

    @Override
    public String protocol() {
        return PROTOCOL;
    }

    @Override
    public String authScheme() {
        return socksAuthMethod() == Socks5AuthMethod.PASSWORD? AUTH_PASSWORD : AUTH_NONE;
    }

    public String username() {
        return username;
    }

    public String password() {
        return password;
    }

    @Override
    protected void addCodec(ChannelHandlerContext ctx) throws Exception {
        ChannelPipeline p = ctx.pipeline();
        String name = ctx.name();

        Socks5InitialResponseDecoder decoder = new Socks5InitialResponseDecoder();
        p.addBefore(name, null, decoder);

        decoderName = p.context(decoder).name();
        encoderName = decoderName + ".encoder";

        p.addBefore(name, encoderName, Socks5ClientEncoder.DEFAULT);
    }

    @Override
    protected void removeEncoder(ChannelHandlerContext ctx) throws Exception {
        ctx.pipeline().remove(encoderName);
    }

    @Override
    protected void removeDecoder(ChannelHandlerContext ctx) throws Exception {
        ChannelPipeline p = ctx.pipeline();
        if (p.context(decoderName) != null) {
            p.remove(decoderName);
        }
    }

    @Override
    protected Object newInitialMessage(ChannelHandlerContext ctx) throws Exception {
        return socksAuthMethod() == Socks5AuthMethod.PASSWORD? INIT_REQUEST_PASSWORD : INIT_REQUEST_NO_AUTH;
    }

    @Override
    protected boolean handleResponse(ChannelHandlerContext ctx, Object response) throws Exception {
        if (response instanceof Socks5InitialResponse) {
            Socks5InitialResponse res = (Socks5InitialResponse) response;
            Socks5AuthMethod authMethod = socksAuthMethod();

            if (res.authMethod() != Socks5AuthMethod.NO_AUTH && res.authMethod() != authMethod) {
                // Server did not allow unauthenticated access nor accept the requested authentication scheme.
                throw new ProxyConnectException(exceptionMessage("unexpected authMethod: " + res.authMethod()));
            }

            if (authMethod == Socks5AuthMethod.NO_AUTH) {
                sendConnectCommand(ctx);
            } else if (authMethod == Socks5AuthMethod.PASSWORD) {
                // In case of password authentication, send an authentication request.
                ctx.pipeline().replace(decoderName, decoderName, new Socks5PasswordAuthResponseDecoder());
                sendToProxyServer(new DefaultSocks5PasswordAuthRequest(
                        username != null? username : "", password != null? password : ""));
            } else {
                // Should never reach here.
                throw new Error();
            }

            return false;
        }

        if (response instanceof Socks5PasswordAuthResponse) {
            // Received an authentication response from the server.
            Socks5PasswordAuthResponse res = (Socks5PasswordAuthResponse) response;
            if (res.status() != Socks5PasswordAuthStatus.SUCCESS) {
                throw new ProxyConnectException(exceptionMessage("authStatus: " + res.status()));
            }

            sendConnectCommand(ctx);
            return false;
        }

        // This should be the last message from the server.
        Socks5CommandResponse res = (Socks5CommandResponse) response;
        if (res.status() != Socks5CommandStatus.SUCCESS) {
            throw new ProxyConnectException(exceptionMessage("status: " + res.status()));
        }

        return true;
    }

    private Socks5AuthMethod socksAuthMethod() {
        Socks5AuthMethod authMethod;
        if (username == null && password == null) {
            authMethod = Socks5AuthMethod.NO_AUTH;
        } else {
            authMethod = Socks5AuthMethod.PASSWORD;
        }
        return authMethod;
    }

    private void sendConnectCommand(ChannelHandlerContext ctx) throws Exception {
        InetSocketAddress raddr = destinationAddress();
        Socks5AddressType addrType;
        String rhost;
        if (raddr.isUnresolved()) {
            addrType = Socks5AddressType.DOMAIN;
            rhost = raddr.getHostString();
        } else {
            rhost = raddr.getAddress().getHostAddress();
            if (NetUtil.isValidIpV4Address(rhost)) {
                addrType = Socks5AddressType.IPv4;
            } else if (NetUtil.isValidIpV6Address(rhost)) {
                addrType = Socks5AddressType.IPv6;
            } else {
                throw new ProxyConnectException(
                        exceptionMessage("unknown address type: " + StringUtil.simpleClassName(rhost)));
            }
        }

        ctx.pipeline().replace(decoderName, decoderName, new Socks5CommandResponseDecoder());
        sendToProxyServer(new DefaultSocks5CommandRequest(Socks5CommandType.CONNECT, addrType, rhost, raddr.getPort()));
    }
}

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