Worker.java

/*-
 *  Copyright (C) 2009 Peter Baldwin   
 *  
 *  This program is free software: you can redistribute it and/or modify
 *  it under the terms of the GNU General Public License as published by
 *  the Free Software Foundation, either version 3 of the License, or
 *  (at your option) any later version.
 *
 *  This program is distributed in the hope that it will be useful,
 *  but WITHOUT ANY WARRANTY; without even the implied warranty of
 *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 *  GNU General Public License for more details.
 *
 *  You should have received a copy of the GNU General Public License
 *  along with this program.  If not, see <http://www.gnu.org/licenses/>.
 */

package org.peterbaldwin.vlcremote.sweep;

import java.io.IOException;
import java.net.HttpURLConnection;
import java.net.InetAddress;
import java.net.MalformedURLException;
import java.net.URL;

final class Worker extends Thread {
    public interface Manager {
        /**
         * Retrieves and removes the next IP address, or returns {@code null} if
         * there are not more addresses to scan.
         */
        byte[] pollIpAddress();
    }

    public interface Callback {
        /**
         * Indicates that an address is reachable.
         */
        void onReachable(InetAddress address, int port, String hostname, int responseCode);

        /**
         * Indicates that an address is unreachable.
         */
        void onUnreachable(byte[] ipAddress, int port, IOException e);
    }

    private final int mPort;
    private final String mPath;
    private Manager mManager;
    private Callback mCallback;

    public Worker(int port, String path) {
        mPort = port;
        mPath = path;
    }

    public void setManager(Manager manager) {
        mManager = manager;
    }

    public void setCallback(Callback callback) {
        mCallback = callback;
    }

    private static URL createUrl(String scheme, String host, int port, String path) {
        try {
            return new URL("http", host, port, path);
        } catch (MalformedURLException e) {
            throw new IllegalArgumentException(e);
        }
    }

    @Override
    public void run() {
        // Note: InetAddress#isReachable(int) always returns false for Windows
        // hosts because applications do not have permission to perform ICMP
        // echo requests.
        for (;;) {
            byte[] ipAddress = mManager.pollIpAddress();
            if (ipAddress == null) {
                break;
            }
            try {
                InetAddress address = InetAddress.getByAddress(ipAddress);
                String hostAddress = address.getHostAddress();
                URL url = createUrl("http", hostAddress, mPort, mPath);
                HttpURLConnection connection = (HttpURLConnection) url.openConnection();
                connection.setConnectTimeout(1000);
                try {
                    int responseCode = connection.getResponseCode();
                    String hostname = address.getHostName();
                    mCallback.onReachable(address, mPort, hostname, responseCode);
                } finally {
                    connection.disconnect();
                }
            } catch (IOException e) {
                mCallback.onUnreachable(ipAddress, mPort, e);
            }
        }
    }
}