UDP Ping Client/Server program
java代写/网络编程代写/socket代写: 这是一个利用java进行UDP程序编写的训练，主要是基于UDP网络协议进行网络编程
Ping is a network utility tool that is used to test reachability to a particular host on a TCP/IP
network. It works by sending a packet to a specified host and waiting for a reply. Ping can be
used for troubleshooting to test connectivity and determine response time between two IP
host machines. The standard Ping program uses ICMP (Internet Control Message Protocol).
However, in this project you will create a pair of Ping Client/Server program built on UDP.
Your ping program is to send 10 ping messages to the target server over UDP. For each
message your client is to determine and print RTT when the corresponding ping message is
returned. Since UDP is an unreliable protocol a packet sent by the client or server may be lost.
For this reason, the client cannot wait indefinitely for a reply to a ping message. You should
have the client wait up to one second for a reply from the server; if no reply is received, the
client should assume that the packet was lost and print a message accordingly.
Server code: The Ping server code is given below.
/**
* PingServer.java
*/
class PingServer {
public static void main(String args[]) throws Exception
{
DatagramSocket serverSocket = new DatagramSocket(2014); //server will run on port #2014
byte[] receiveData = new byte[1024];
//Processing loop
while(true)
{
//create a random number generator for use in packet loss simulation
Random random = new Random();
//create a datagram packet to hold incoming UDP packet
DatagramPacket receivePacket = new DatagramPacket(receiveData, receiveData.length);
// get the client message
serverSocket.receive(receivePacket);
String sentence = new String(receivePacket.getData(),0, receivePacket.getLength());
InetAddress IPAddress = receivePacket.getAddress(); //get client’s IP
int port = receivePacket.getPort(); //get client’s port #
//print out the clients’s IP address, port number and the message
System.out.println(“client’s port # = ” + port);
System.out.println(“client’sIP = ” +IPAddress);
System.out.println(“client’s message = ” +sentence);
//capitalize the message from the client
String capitalizedSentence = sentence.toUpperCase();
//simulate the packet loss
int rand =random.nextInt(10);//a random number in the range of 0 to10
// if rand is less than 4 we consider the packet lost and do not reply
if (rand < 4) {
System .out.println("Reply not sent");
continue;
}
//otherwise, the server responds
byte[] sendData = capitalizedSentence.getBytes();
DatagramPacket sendPacket =new DatagramPacket(sendData, sendData.length, IPAddress,
port);
serverSocket.send(sendPacket);
System.out.println("Reply to the client sent");
}//while
}//main
}
You should study the server code carefully so that you can write the corresponding ping client
program. Your ping client program should sends 10 ping requests to the server. After sending
each request client waits up to one second for reply from the server. If no reply is received
during this time period, client times out. In this case you should print out the time out message.
Specifically, your client program should do the following:
(1)Print out the current time and the ping attempt number. Send the ping message using UDP.
(2) Print the response message from server, if any (the server will capitalize the message sent
by the client and send it back to the client). Print out the elapsed time in microseconds.
(3) Calculate and print the round trip time (RTT), in microseconds, of each packet, if server
responses.
(4) Otherwise, print “Request timed out”.