boolean authenticate(ChannelHandlerContext ctx, Object msg) {
    if (username == null) {
        ctx.pipeline().replace(DECODER, DECODER, new Socks5CommandRequestDecoder());
        ctx.write(new DefaultSocks5InitialResponse(Socks5AuthMethod.NO_AUTH));
        return true;
    }

    if (msg instanceof Socks5InitialRequest) {
        ctx.pipeline().replace(DECODER, DECODER, new Socks5PasswordAuthRequestDecoder());
        ctx.write(new DefaultSocks5InitialResponse(Socks5AuthMethod.PASSWORD));
        return false;
    }

    Socks5PasswordAuthRequest req = (Socks5PasswordAuthRequest) msg;
    if (req.username().equals(username) && req.password().equals(password)) {
        ctx.pipeline().replace(DECODER, DECODER, new Socks5CommandRequestDecoder());
        ctx.write(new DefaultSocks5PasswordAuthResponse(Socks5PasswordAuthStatus.SUCCESS));
        return true;
    }

    ctx.pipeline().replace(DECODER, DECODER, new Socks5PasswordAuthRequestDecoder());
    ctx.write(new DefaultSocks5PasswordAuthResponse(Socks5PasswordAuthStatus.FAILURE));
    return false;
}
 

@Override
protected void channelRead0(ChannelHandlerContext ctx, SocksMessage socksMessage)
        throws Exception {
    switch (socksMessage.version()) {
    case SOCKS4a:
        Socks4CommandRequest socksV4CmdRequest = (Socks4CommandRequest) socksMessage;
        if (socksV4CmdRequest.type() == Socks4CommandType.CONNECT) {
            onSocksSuccess(ctx, socksV4CmdRequest);
        } else {
            ctx.close();
        }
        break;
    case SOCKS5:
        if (socksMessage instanceof Socks5InitialRequest) {
            ctx.pipeline().addFirst(addChannelHandler(new Socks5CommandRequestDecoder()));
            ctx.writeAndFlush(new DefaultSocks5InitialResponse(Socks5AuthMethod.NO_AUTH));
        } else if (socksMessage instanceof Socks5PasswordAuthRequest) {
            ctx.pipeline().addFirst(addChannelHandler(new Socks5CommandRequestDecoder()));
            ctx.writeAndFlush(new DefaultSocks5PasswordAuthResponse(Socks5PasswordAuthStatus.SUCCESS));
        } else if (socksMessage instanceof Socks5CommandRequest) {
            Socks5CommandRequest socks5CmdRequest = (Socks5CommandRequest) socksMessage;
            if (socks5CmdRequest.type() == Socks5CommandType.CONNECT) {
                onSocksSuccess(ctx, socks5CmdRequest);
            } else {
                ctx.close();
            }
        } else {
            ctx.close();
        }
        break;
    case UNKNOWN:
        ctx.close();
        break;
    }
}
 

@Override
public void channelRead0(ChannelHandlerContext ctx, SocksMessage socksRequest) throws Exception {
    switch (socksRequest.version()) {
        case SOCKS4a:
            Socks4CommandRequest socksV4CmdRequest = (Socks4CommandRequest) socksRequest;
            if (socksV4CmdRequest.type() == Socks4CommandType.CONNECT) {
                ctx.pipeline().addLast(new SocksServerConnectHandler());
                ctx.pipeline().remove(this);
                ctx.fireChannelRead(socksRequest);
            } else {
                ctx.close();
            }
            break;
        case SOCKS5:
            if (socksRequest instanceof Socks5InitialRequest) {
                // auth support example
                //ctx.pipeline().addFirst(new Socks5PasswordAuthRequestDecoder());
                //ctx.write(new DefaultSocks5AuthMethodResponse(Socks5AuthMethod.PASSWORD));
                ctx.pipeline().addFirst(new Socks5CommandRequestDecoder());
                ctx.write(new DefaultSocks5InitialResponse(Socks5AuthMethod.NO_AUTH));
            } else if (socksRequest instanceof Socks5PasswordAuthRequest) {
                ctx.pipeline().addFirst(new Socks5CommandRequestDecoder());
                ctx.write(new DefaultSocks5PasswordAuthResponse(Socks5PasswordAuthStatus.SUCCESS));
            } else if (socksRequest instanceof Socks5CommandRequest) {
                Socks5CommandRequest socks5CmdRequest = (Socks5CommandRequest) socksRequest;
                if (socks5CmdRequest.type() == Socks5CommandType.CONNECT) {
                    ctx.pipeline().addLast(new SocksServerConnectHandler());
                    ctx.pipeline().remove(this);
                    ctx.fireChannelRead(socksRequest);
                } else {
                    ctx.close();
                }
            } else {
                ctx.close();
            }
            break;
        case UNKNOWN:
            ctx.close();
            break;
    }
}