org.bbottema.javasocksproxyserver.Utils Maven / Gradle / Ivy

Go to download
/*
 * Copyright © 2019 Benny Bottema ([email protected])
 *
 * Licensed 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 org.bbottema.javasocksproxyserver;

import org.jetbrains.annotations.NotNull;
import org.jetbrains.annotations.Nullable;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;

import java.io.IOException;
import java.net.*;

import static java.lang.String.format;

public final class Utils {

	private static final Logger LOGGER = LoggerFactory.getLogger(Utils.class);

	@Nullable
	public static InetAddress calcInetAddress(byte[] addr) {
		InetAddress IA;
		StringBuilder sIA = new StringBuilder();

		if (addr.length < 4) {
			LOGGER.error("calcInetAddress() - Invalid length of IP v4 - " + addr.length + " bytes");
			return null;
		}

		// IP v4 Address Type
		for (int i = 0; i < 4; i++) {
			sIA.append(byte2int(addr[i]));
			if (i < 3) sIA.append(".");
		}

		try {
			IA = InetAddress.getByName(sIA.toString());
		} catch (UnknownHostException e) {
			return null;
		}

		return IA;
	}

	public static int byte2int(byte b) {
		return (int) b < 0 ? 0x100 + (int) b : b;
	}

	public static int calcPort(byte Hi, byte Lo) {
		return ((byte2int(Hi) << 8) | byte2int(Lo));
	}

	@NotNull
	public static String iP2Str(InetAddress IP) {
		return IP == null
				? "NA/NA"
				: format("%s/%s", IP.getHostName(), IP.getHostAddress());
	}

	@NotNull
	public static String getSocketInfo(Socket sock) {
		return sock == null
				? ""
				: format("<%s:%d>", Utils.iP2Str(sock.getInetAddress()), sock.getPort());
	}

	@NotNull
	public static String getSocketInfo(DatagramPacket DGP) {
		return DGP == null
				? ""
				: format("<%s:%d>", Utils.iP2Str(DGP.getAddress()), DGP.getPort());
	}

	public static int getFreePort() {
		try (ServerSocket serverSocket = new ServerSocket(0)) {
			return serverSocket.getLocalPort();
		} catch (IOException e) {
			throw new RuntimeException(e);
		}
	}

	public static boolean isLocalPortAvailableToConnect(int port) {
		try (Socket ignored = new Socket("localhost", port)) {
			return true;
		} catch (ConnectException e) {
			return false;
		} catch (IOException e) {
			throw new IllegalStateException("Error while trying to check open port", e);
		}
	}
}