echo.java

/*
 * Licensed to the Apache Software Foundation (ASF) under one or more
 * contributor license agreements.  See the NOTICE file distributed with
 * this work for additional information regarding copyright ownership.
 * The ASF 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 org.apache.commons.net.examples.unix;

import java.io.BufferedReader;
import java.io.IOException;
import java.io.InputStreamReader;
import java.io.InterruptedIOException;
import java.io.OutputStreamWriter;
import java.io.PrintWriter;
import java.net.InetAddress;
import java.net.SocketException;
import java.nio.charset.Charset;
import java.time.Duration;

import org.apache.commons.net.echo.EchoTCPClient;
import org.apache.commons.net.echo.EchoUDPClient;

/**
 * This is an example program demonstrating how to use the EchoTCPClient and EchoUDPClient classes. This program connects to the default echo service port of a
 * specified server, then reads lines from standard input, writing them to the echo server, and then printing the echo. The default is to use the TCP port. Use
 * the -udp flag to use the UDP port.
 * <p>
 * Usage: echo [-udp] <hostname>
 * </p>
 */
public final class echo {

    public static void echoTCP(final String host) throws IOException {
        final EchoTCPClient client = new EchoTCPClient();
        String line;

        // We want to timeout if a response takes longer than 60 seconds
        client.setDefaultTimeout(60000);
        client.connect(host);
        try {
            System.out.println("Connected to " + host + ".");
            final Charset charset = Charset.defaultCharset();
            final BufferedReader input = new BufferedReader(new InputStreamReader(System.in, charset));
            try (PrintWriter echoOutput = new PrintWriter(new OutputStreamWriter(client.getOutputStream(), charset), true);
                    BufferedReader echoInput = new BufferedReader(new InputStreamReader(client.getInputStream(), charset))) {
                while ((line = input.readLine()) != null) {
                    echoOutput.println(line);
                    System.out.println(echoInput.readLine());
                }
            }
            // Don't close System.in
        } finally {
            client.disconnect();
        }
    }

    public static void echoUDP(final String host) throws IOException {
        int length, count;
        byte[] data;
        String line;
        final BufferedReader input;
        final InetAddress address;

        final Charset charset = Charset.defaultCharset();
        input = new BufferedReader(new InputStreamReader(System.in, charset));
        address = InetAddress.getByName(host);
        try (EchoUDPClient client = new EchoUDPClient()) {

            client.open();
            // If we don't receive an echo within 5 seconds, assume the packet is lost.
            client.setSoTimeout(Duration.ofSeconds(5));
            System.out.println("Ready to echo to " + host + ".");

            // Remember, there are no guarantees about the ordering of returned
            // UDP packets, so there is a chance the output may be jumbled.
            while ((line = input.readLine()) != null) {
                data = line.getBytes(charset);
                client.send(data, address);
                count = 0;
                do {
                    try {
                        length = client.receive(data);
                    }
                    // Here we catch both SocketException and InterruptedIOException,
                    // because even though the JDK 1.1 docs claim that
                    // InterruptedIOException is thrown on a timeout, it seems
                    // SocketException is also thrown.
                    catch (final SocketException e) {
                        // We timed out and assume the packet is lost.
                        System.err.println("SocketException: Timed out and dropped packet");
                        break;
                    } catch (final InterruptedIOException e) {
                        // We timed out and assume the packet is lost.
                        System.err.println("InterruptedIOException: Timed out and dropped packet");
                        break;
                    }
                    System.out.print(new String(data, 0, length, charset));
                    count += length;
                } while (count < data.length);

                System.out.println();
            }

        }
    }

    public static void main(final String[] args) {

        if (args.length == 1) {
            try {
                echoTCP(args[0]);
            } catch (final IOException e) {
                e.printStackTrace();
                System.exit(1);
            }
        } else if (args.length == 2 && args[0].equals("-udp")) {
            try {
                echoUDP(args[1]);
            } catch (final IOException e) {
                e.printStackTrace();
                System.exit(1);
            }
        } else {
            System.err.println("Usage: echo [-udp] <hostname>");
            System.exit(1);
        }

    }

}