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/*************************************************************************//**
*
* Copyright © 2017 AT&T Intellectual Property. All rights reserved.
*
* 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 main.java;
import java.io.IOException;
import java.net.DatagramPacket;
import java.net.DatagramSocket;
/*
* Client-side Failure Detector (FD) implementation.
* @param server_addr: IP address of the remote server
* @param port: the port that the FD service listens for incoming UDP packets
* @param timeout: how often the FD checks the status of client processes
* @param debug: debug mode on/off
*/
public class DNSServer {
public static void main(String[] args) throws IOException {
if(args.length != 5) {
System.out.println("Missing input parameters");
System.out.println("Usage:");
System.out.print("\t- java FDClient [process ID] [server IP address] [server port] [timeout (sec)] [debug]\n");
System.exit(0);
}
// IP address and port of the remote server
String PID = args[0];
String SERVER_ADDR = args[1];
int PORT = Integer.parseInt(args[2]);
long TIMEOUT = Long.parseLong(args[3]) * 1000; // convert the FD timeout to milliseconds
int debug = Integer.parseInt(args[4]);
boolean DEBUG;
if(debug <= 0)
DEBUG = false;
else
DEBUG = true;
// Run FD client
new FDClient(PID, SERVER_ADDR, PORT, TIMEOUT, DEBUG);
// Listen for reply messages
@SuppressWarnings("resource")
DatagramSocket sock = new DatagramSocket(PORT);
byte[] buffer = new byte[256];
boolean gre_tunnel_enabled = false;
while(true) {
DatagramPacket packet = new DatagramPacket(buffer, buffer.length);
sock.receive(packet);
String[] content = new String(packet.getData()).trim().split(":"); // Remove leading and trailing spaces
String msg_type = content[0];
String ip = content[1];
// Process only PING UDP packets
if(msg_type.equals("PONG")) {
if(DEBUG) System.out.println("Reply message received from process " + ip);
if(!gre_tunnel_enabled) {
// Set GRE tunnel towards load balancer
String script = new String("bash /opt/FDclient/set_gre_tunnel.sh " + ip);
Runtime.getRuntime().exec(script);
if(DEBUG) System.out.println("GRE tunnel towards load balancer " + ip + " done");
gre_tunnel_enabled = true;
}
}
else {
if(DEBUG) System.out.println("The received message is not a PONG. Received content: " + content);
}
}
}
}
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