Subversion Repositories programming

Rev

Rev 221 | Rev 224 | Go to most recent revision | Details | Compare with Previous | Last modification | View Log | RSS feed

Rev Author Line No. Line
221 ira 1 
/*******************************************************************************
2 
 * File: DHCPTable.java
3 
 * Author: Ira W. Snyder (devel@irasnyder.com)
4 
 * License: GNU General Public License v2
5 
 * Class: CS380 - Computer Networking
6 
 *
7 
 * Assignment: Project #3
8 
 * Date Last Modified: 2006-02-15
9 
 *
10 
 * Purpose: //FIXME
11 
 ******************************************************************************/
12 
 
222 ira 13 
import java.util.Date;
221 ira 14 
 
15 
public class DHCPTable
16 
{
222 ira 17 
    private DHCPTableEntry[] table = new DHCPTableEntry[100];
18 
    private IPAddr lowestIP = new IPAddr("134.71.24.1");
19 
    private IPAddr highestIP = new IPAddr("134.71.24.100");
20 
    private long timeoutMS = 8000; // 8000 millisec by default
221 ira 21 
 
222 ira 22 
    public DHCPTable ()
23 
    {
24 
        int i;
25 
        final String startStr = "134.71.24.";
26 
        IPAddr ip = null;
221 ira 27 
 
222 ira 28 
        for (i=1; i<=table.length; i++)
29 
        {
30 
            ip = new IPAddr (startStr + i);
31 
            table[i-1] = new DHCPTableEntry("", ip, 0);
32 
        }
33 
    }
34 
 
35 
    private DHCPTableEntry getFirstFreeEntry ()
221 ira 36 
    {
37 
        int i = 0;
38 
 
222 ira 39 
        for (i=0; i<table.length; i++)
40 
            if (table[i].getLeaseStart() == 0)
41 
                return table[i];
221 ira 42 
 
222 ira 43 
        throw new ArrayIndexOutOfBoundsException();
221 ira 44 
    }
45 
 
222 ira 46 
    public DHCPTableEntry addEntry (String HWAddr)
47 
    {
48 
        long curTime = new Date().getTime();
49 
        DHCPTableEntry e = getFirstFreeEntry();
50 
 
51 
        e.setHWAddr (HWAddr);
52 
        e.setLeaseStart (curTime);
53 
 
54 
        return e;
55 
    }
56 
 
221 ira 57 
    /**
222 ira 58 
     * Method: timeoutEntry()
59 
     * Purpose: tries to find an expired entry. If it has found one, it expires it
60 
     * and returns it, otherwise it returns null.
221 ira 61 
     */
222 ira 62 
    public DHCPTableEntry timeoutEntry ()
221 ira 63 
    {
222 ira 64 
        int i;
65 
        long curTime = new Date().getTime();
66 
        DHCPTableEntry e = null;
67 
 
68 
        for (i=0; i<table.length; i++)
69 
            if (table[i].getLeaseStart() != 0 && curTime > (table[i].getLeaseStart() + timeoutMS))
70 
            {
71 
                e = new DHCPTableEntry (table[i].getHWAddr(),
72 
                                        table[i].getIPAddr(),
73 
                                        table[i].getLeaseStart());
74 
 
75 
                table[i].setHWAddr ("");
76 
                table[i].setLeaseStart (0);
77 
                return e;
78 
            }
79 
 
80 
        return e; // will be null if an entry was not found
81 
    }
82 
 
83 
    public DHCPTableEntry timeoutEntry (IPAddr ip)
221 ira 84 
    {
222 ira 85 
        int i = ip.getField(3) - 1;
86 
        long curTime = new Date().getTime();
87 
        DHCPTableEntry e = null;
88 
 
89 
        if (curTime > (table[i].getLeaseStart() + timeoutMS))
221 ira 90 
        {
222 ira 91 
            // Make a copy of the object
92 
            e = new DHCPTableEntry (table[i].getHWAddr(),
93 
                                    table[i].getIPAddr(),
94 
                                    table[i].getLeaseStart());
221 ira 95 
 
222 ira 96 
            table[i].setHWAddr ("");
97 
            table[i].setLeaseStart (0);
98 
            return e;
221 ira 99 
        }
100 
 
222 ira 101 
        return null;
221 ira 102 
    }
103 
}
104