Cisco Router : Socket Listener : Network C# Source Code

    

/*
C# Network Programming 
by Richard Blum

Publisher: Sybex 
ISBN: 0782141765
*/
using System.Net;
using System.Net.Sockets;

using System;
using System.Drawing;
using System.IO;
using System.Threading;
using System.Windows.Forms;

public class CiscoRouter : Form
{

   private TextBox host;
   private TextBox community;
   private ListBox results;
   private Thread monitor;
   private FileStream fs;
   private StreamWriter sw;

   public CiscoRouter()
   {
      Text = "Cisco Router Utilization";
      Size = new Size(400, 380);

      Label label1 = new Label();
      label1.Parent = this;
      label1.Text = "Host:";
      label1.AutoSize = true;
      label1.Location = new Point(10, 30);

      host = new TextBox();
      host.Parent = this;
      host.Size = new Size(170, 2 * Font.Height);
      host.Location = new Point(40, 27);

      Label label2 = new Label();
      label2.Parent = this;
      label2.Text = "Community:";
      label2.AutoSize = true;
      label2.Location = new Point(10, 60);

      community = new TextBox();
      community.Parent = this;
      community.Size = new Size(170, 2 * Font.Height);
      community.Location = new Point(75, 57);

      results = new ListBox();
      results.Parent = this;
      results.Location = new Point(10, 85);
      results.Size = new Size(360, 18 * Font.Height);

      Button start = new Button();
      start.Parent = this;
      start.Text = "Start";
      start.Location = new Point(250, 52);
      start.Size = new Size(5 * Font.Height, 2 * Font.Height);
      start.Click += new EventHandler(ButtonStartOnClick);

      Button stop = new Button();
      stop.Parent = this;
      stop.Text = "Stop";
      stop.Location = new Point(320, 52);
      stop.Size = new Size(5 * Font.Height, 2 * Font.Height);
      stop.Click += new EventHandler(ButtonStopOnClick);
   }

   void ButtonStartOnClick(Object obj, EventArgs ea)
   {
      monitor = new Thread(new ThreadStart(checkRouter));
      monitor.IsBackground = true;
      monitor.Start();
   }

   void ButtonStopOnClick(Object obj, EventArgs ea)
   {
      monitor.Abort();
      sw.Close();
      fs.Close();
   }

   void checkRouter()
   {
      int commlength, miblength, datastart, cpuUtil;
      SNMP conn = new SNMP();
      byte[] response = new byte[1024];
      DateTime time;
      string logFile = "routerlog.txt";
      fs = new FileStream(logFile, FileMode.OpenOrCreate,
            FileAccess.ReadWrite);
      sw = new StreamWriter(fs);

      while (true)
      {
         response = conn.get("get", host.Text,
             community.Text, "1.3.6.1.4.1.9.2.1.58.0");
         if (response[0] == 0xff)
         {
            results.Items.Add("No reponse from host");
            sw.WriteLine("No response from host");
            sw.Flush();
            break;
         }
         commlength = Convert.ToInt16(response[6]);
         miblength = Convert.ToInt16(response[23 + commlength]);
         datastart = 26 + commlength + miblength;

         cpuUtil = Convert.ToInt16(response[datastart]);
         time = DateTime.Now;
         results.Items.Add(time + " CPU Utilization: " + cpuUtil + "%");
         sw.WriteLine("{0} CPU Utilization: {1}%", time, cpuUtil);
         sw.Flush();
         Thread.Sleep(5 * 60000);
      }
   }

   public static void Main()
   {
      Application.Run(new CiscoRouter());
   }
}


class SNMP
{
   public SNMP()
   {

   }

   public byte[] get(string request, string host, string community, string mibstring)
   {
      byte[] packet = new byte[1024];
      byte[] mib = new byte[1024];
      int snmplen;
      int comlen = community.Length;
      string[] mibvals = mibstring.Split('.');
      int miblen = mibvals.Length;
      int cnt = 0, temp, i;
      int orgmiblen = miblen;
      int pos = 0;

      // Convert the string MIB into a byte array of integer values
      // Unfortunately, values over 128 require multiple bytes
      // which also increases the MIB length
      for (i = 0; i < orgmiblen; i++)
      {
         temp = Convert.ToInt16(mibvals[i]);
         if (temp > 127)
         {
            mib[cnt] = Convert.ToByte(128 + (temp / 128));
            mib[cnt + 1] = Convert.ToByte(temp - ((temp / 128) * 128));
            cnt += 2;
            miblen++;
         } else
         {
            mib[cnt] = Convert.ToByte(temp);
            cnt++;
         }
      }
      snmplen = 29 + comlen + miblen - 1;  //Length of entire SNMP packet

      //The SNMP sequence start
      packet[pos++] = 0x30; //Sequence start
      packet[pos++] = Convert.ToByte(snmplen - 2);  //sequence size

      //SNMP version
      packet[pos++] = 0x02; //Integer type
      packet[pos++] = 0x01; //length
      packet[pos++] = 0x00; //SNMP version 1

      //Community name
      packet[pos++] = 0x04; // String type
      packet[pos++] = Convert.ToByte(comlen); //length
      //Convert community name to byte array
      byte[] data = Encoding.ASCII.GetBytes(community);
      for (i = 0; i < data.Length; i++)
      {
         packet[pos++] = data[i];
      }

      //Add GetRequest or GetNextRequest value
      if (request == "get")
         packet[pos++] = 0xA0;
      else
         packet[pos++] = 0xA1;

      packet[pos++] = Convert.ToByte(20 + miblen - 1); //Size of total MIB

      //Request ID
      packet[pos++] = 0x02; //Integer type
      packet[pos++] = 0x04; //length
      packet[pos++] = 0x00; //SNMP request ID
      packet[pos++] = 0x00;
      packet[pos++] = 0x00;
      packet[pos++] = 0x01;

      //Error status
      packet[pos++] = 0x02; //Integer type
      packet[pos++] = 0x01; //length
      packet[pos++] = 0x00; //SNMP error status

      //Error index
      packet[pos++] = 0x02; //Integer type
      packet[pos++] = 0x01; //length
      packet[pos++] = 0x00; //SNMP error index

      //Start of variable bindings
      packet[pos++] = 0x30; //Start of variable bindings sequence

      packet[pos++] = Convert.ToByte(6 + miblen - 1); // Size of variable binding

      packet[pos++] = 0x30; //Start of first variable bindings sequence
      packet[pos++] = Convert.ToByte(6 + miblen - 1 - 2); // size
      packet[pos++] = 0x06; //Object type
      packet[pos++] = Convert.ToByte(miblen - 1); //length

      //Start of MIB
      packet[pos++] = 0x2b;
      //Place MIB array in packet
      for(i = 2; i < miblen; i++)
         packet[pos++] = Convert.ToByte(mib[i]);
      packet[pos++] = 0x05; //Null object value
      packet[pos++] = 0x00; //Null

      //Send packet to destination
      Socket sock = new Socket(AddressFamily.InterNetwork, SocketType.Dgram,
                       ProtocolType.Udp);
      sock.SetSocketOption(SocketOptionLevel.Socket,
                      SocketOptionName.ReceiveTimeout, 5000);
      IPHostEntry ihe = Dns.Resolve(host);
      IPEndPoint iep = new IPEndPoint(ihe.AddressList[0], 161);
      EndPoint ep = (EndPoint)iep;
      sock.SendTo(packet, snmplen, SocketFlags.None, iep);

      //Receive response from packet
      try
      {
         int recv = sock.ReceiveFrom(packet, ref ep);
      } catch (SocketException)
      {
         packet[0] = 0xff;
      }
      return packet;
   }

   public string getnextMIB(byte[] mibin)
   {
      string output = "1.3";
      int commlength = mibin[6];
      int mibstart = 6 + commlength + 17; //find the start of the mib section
      //The MIB length is the length defined in the SNMP packet
     // minus 1 to remove the ending .0, which is not used
      int miblength = mibin[mibstart] - 1;
      mibstart += 2; //skip over the length and 0x2b values
      int mibvalue;

      for(int i = mibstart; i < mibstart + miblength; i++)
      {
         mibvalue = Convert.ToInt16(mibin[i]);
         if (mibvalue > 128)
         {
            mibvalue = (mibvalue/128)*128 + Convert.ToInt16(mibin[i+1]);
            i++;
         }
         output += "." + mibvalue;
      }
      return output;
   }
}