jodd-http/src/main/java/jodd/http/net/Socks4ProxySocketFactory.java
private Socket createSocks4ProxySocket(final String host, final int port) {
		Socket socket = null;
		final String proxyHost = proxy.getProxyAddress();
		final int proxyPort = proxy.getProxyPort();
		final String user = proxy.getProxyUsername();

		try {
			socket = Sockets.connect(proxyHost, proxyPort, connectionTimeout);

			final InputStream in = socket.getInputStream();
			final OutputStream out = socket.getOutputStream();

			socket.setTcpNoDelay(true);

			byte[] buf = new byte[1024];

			// 1) CONNECT

			int index = 0;
			buf[index++] = 4;
			buf[index++] = 1;

			buf[index++] = (byte) (port >>> 8);
			buf[index++] = (byte) (port & 0xff);

			InetAddress addr = InetAddress.getByName(host);
			byte[] byteAddress = addr.getAddress();
			for (byte byteAddres : byteAddress) {
				buf[index++] = byteAddres;
			}

			if (user != null) {
				System.arraycopy(user.getBytes(), 0, buf, index, user.length());
				index += user.length();
			}
			buf[index++] = 0;
			out.write(buf, 0, index);

			// 2) RESPONSE

			int len = 6;
			int s = 0;
			while (s < len) {
				int i = in.read(buf, s, len - s);
				if (i <= 0) {
					throw new HttpException(ProxyInfo.ProxyType.SOCKS4, "stream is closed");
				}
				s += i;
			}
			if (buf[0] != 0) {
				throw new HttpException(ProxyInfo.ProxyType.SOCKS4, "proxy returned VN " + buf[0]);
			}
			if (buf[1] != 90) {
				try {
					socket.close();
				} catch (Exception ignore) {
				}
				throw new HttpException(ProxyInfo.ProxyType.SOCKS4, "proxy returned CD " + buf[1]);
			}

			byte[] temp = new byte[2];
			in.read(temp, 0, 2);

			return socket;
		} catch (RuntimeException rtex) {
			closeSocket(socket);
			throw rtex;
		} catch (Exception ex) {
			closeSocket(socket);
			throw new HttpException(ProxyInfo.ProxyType.SOCKS4, ex.toString(), ex);
		}
	}
private Socket createSocks4ProxySocket(final String host, final int port) {
		Socket socket = null;
		final String proxyHost = proxy.getProxyAddress();
		final int proxyPort = proxy.getProxyPort();
		final String user = proxy.getProxyUsername();

		try {
			socket = Sockets.connect(proxyHost, proxyPort, connectionTimeout);

			final InputStream in = socket.getInputStream();
			final OutputStream out = socket.getOutputStream();

			socket.setTcpNoDelay(true);

			byte[] buf = new byte[1024];

			// 1) CONNECT

			int index = 0;
			buf[index++] = 4;
			buf[index++] = 1;

			buf[index++] = (byte) (port >>> 8);
			buf[index++] = (byte) (port & 0xff);

			InetAddress addr = InetAddress.getByName(host);
			byte[] byteAddress = addr.getAddress();
			for (byte byteAddres : byteAddress) {
				buf[index++] = byteAddres;
			}

			if (user != null) {
				System.arraycopy(user.getBytes(), 0, buf, index, user.length());
				index += user.length();
			}
			buf[index++] = 0;
			out.write(buf, 0, index);

			// 2) RESPONSE

			int len = 6;
			int s = 0;
			while (s < len) {
				int i = in.read(buf, s, len - s);
				if (i <= 0) {
					throw new HttpException(ProxyInfo.ProxyType.SOCKS4, "stream is closed");
				}
				s += i;
			}
			if (buf[0] != 0) {
				throw new HttpException(ProxyInfo.ProxyType.SOCKS4, "proxy returned VN " + buf[0]);
			}
			if (buf[1] != 90) {
				try {
					socket.close();
				} catch (Exception ignore) {
				}
				throw new HttpException(ProxyInfo.ProxyType.SOCKS4, "proxy returned CD " + buf[1]);
			}

			byte[] temp = new byte[2];
			in.read(temp, 0, 2);

			return socket;
		} catch (RuntimeException rtex) {
			closeSocket(socket);
			throw rtex;
		} catch (Exception ex) {
			closeSocket(socket);
			throw new HttpException(ProxyInfo.ProxyType.SOCKS4, ex.toString(), ex);
		}
	}
Connects to the SOCKS4 proxy and returns proxified socket.