ping.java

这是ICMP源程序包含PING的接收和发送

import java.util.*;
import java.math.*;

public class Ping {
    private native int icmp_send(String host, int sequence, String data);
    private native String icmp_recv(int timeout);

    static {
	System.loadLibrary("ping");
    }

    private int counter;
    private HashSet received;

    public Ping() {
	counter = 0;
	received = new HashSet();
    }

    public int send(String host) {
	return send(host, "012345678901234567890123456789");
    }

    public int send(String host, int bytes) {
	StringBuffer sb = new StringBuffer();

	for (int i = 0; i < bytes; i++) {
	    sb.append(i%9);
	}

	return send(host, sb.toString());
    }

    public int send(String host, String data) {
	if (data.length() > 64000) {
	    System.err.println("Data item too long. 64,000 bytes max.");
	    return -5;
	}

	data = System.currentTimeMillis() + " " + data;

	int ret = icmp_send(host, counter, data);

	counter++;

	return ret;
    }

    public long recv(int timeout) {
	String res = icmp_recv(timeout);
	
	long endtime = System.currentTimeMillis();
	
	boolean duplicate = false;

	if (res == null) {
	    System.err.println("Timeout waiting for packet");
	    return -1;
	}
	
	Integer I = new Integer(res.substring(0, res.indexOf(" ")));
	if (received.contains(I)) {
	    duplicate = true;
	} else {
	    received.add(I);
	}

	String data = res.substring((res.indexOf(" ")+1));
	data = data.substring(0, data.indexOf(" "));
	BigInteger bi =	new BigInteger(data);
	long starttime = bi.longValue();

	return (endtime - starttime);
    }
}