Socks4ProxyServer Class — netty Architecture

Source Code

handler-proxy/src/test/java/io/netty/handler/proxy/Socks4ProxyServer.java lines 39–145

final class Socks4ProxyServer extends ProxyServer {

    Socks4ProxyServer(boolean useSsl, TestMode testMode, InetSocketAddress destination) {
        super(useSsl, testMode, destination);
    }

    Socks4ProxyServer(boolean useSsl, TestMode testMode, InetSocketAddress destination, String username) {
        super(useSsl, testMode, destination, username, null);
    }

    @Override
    protected void configure(SocketChannel ch) throws Exception {
        ChannelPipeline p = ch.pipeline();
        switch (testMode) {
        case INTERMEDIARY:
            p.addLast(new Socks4ServerDecoder());
            p.addLast(Socks4ServerEncoder.INSTANCE);
            p.addLast(new Socks4IntermediaryHandler());
            break;
        case TERMINAL:
            p.addLast(new Socks4ServerDecoder());
            p.addLast(Socks4ServerEncoder.INSTANCE);
            p.addLast(new Socks4TerminalHandler());
            break;
        case UNRESPONSIVE:
            p.addLast(UnresponsiveHandler.INSTANCE);
            break;
        }
    }

    private boolean authenticate(ChannelHandlerContext ctx, Socks4CommandRequest req) {
        assertEquals(Socks4CommandType.CONNECT, req.type());

        if (testMode != TestMode.INTERMEDIARY) {
            ctx.pipeline().addBefore(ctx.name(), "lineDecoder", new LineBasedFrameDecoder(64, false, true));
        }

        boolean authzSuccess;
        if (username != null) {
            authzSuccess = username.equals(req.userId());
        } else {
            authzSuccess = true;
        }
        return authzSuccess;
    }

    private final class Socks4IntermediaryHandler extends IntermediaryHandler {

        private SocketAddress intermediaryDestination;

        @Override
        protected boolean handleProxyProtocol(ChannelHandlerContext ctx, Object msg) throws Exception {
            Socks4CommandRequest req = (Socks4CommandRequest) msg;
            Socks4CommandResponse res;

            if (!authenticate(ctx, req)) {
                res = new DefaultSocks4CommandResponse(Socks4CommandStatus.IDENTD_AUTH_FAILURE);
            } else {
                res = new DefaultSocks4CommandResponse(Socks4CommandStatus.SUCCESS);
                intermediaryDestination = SocketUtils.socketAddress(req.dstAddr(), req.dstPort());
            }

            ctx.write(res);

            ctx.pipeline().remove(Socks4ServerDecoder.class);
            ctx.pipeline().remove(Socks4ServerEncoder.class);

            return true;
        }

        @Override
        protected SocketAddress intermediaryDestination() {
            return intermediaryDestination;
        }
    }

    private final class Socks4TerminalHandler extends TerminalHandler {
        @Override
        protected boolean handleProxyProtocol(ChannelHandlerContext ctx, Object msg) throws Exception {
            Socks4CommandRequest req = (Socks4CommandRequest) msg;
            boolean authzSuccess = authenticate(ctx, req);