Csharp/C Sharp/Network/Socket Listener

Cisco Router

/*
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;
   }
}

Listening For Sockets

/*
 * C# Programmers Pocket Consultant
 * Author: Gregory S. MacBeth
 * Email: gmacbeth@comporium.net
 * Create Date: June 27, 2003
 * Last Modified Date:
 * Version: 1
 */
using System;
using System.Net;
using System.Text;
using System.Net.Sockets;
namespace Client.Chapter_14___Networking_and_WWW
{
  public class ListeningForSockets
  {
    [STAThread]
    static void Main(string[] args)
    {
      int PortNumber = 10000;
      TcpListener MyListener = new TcpListener(PortNumber);
      MyListener.Start();
      //Console.WriteLine("Waiting For Connection");
      TcpClient MyClient = MyListener.AcceptTcpClient();
      Console.WriteLine("Connection Accepted");
      NetworkStream MyNetStream = MyClient.GetStream();
      String Response = "Connection Has been accepted";
      Byte[] SendTheseBytes = Encoding.ASCII.GetBytes(Response);
      MyNetStream.Write(SendTheseBytes, 0, SendTheseBytes.Length);
      MyClient.Close();
      MyListener.Stop();
    }
  }
}

Trace Route

/*
C# Network Programming 
by Richard Blum
Publisher: Sybex 
ISBN: 0782141765
*/
using System;
using System.Net;
using System.Net.Sockets;
using System.Text;
public class TraceRoute
{
   public static void Main(string[] argv)
   {
      byte[] data = new byte[1024];
      int recv, timestart, timestop;
      Socket host = new Socket(AddressFamily.InterNetwork, SocketType.Raw, ProtocolType.Icmp);
      IPHostEntry iphe = Dns.Resolve(argv[0]);
      IPEndPoint iep = new IPEndPoint(iphe.AddressList[0], 0);
      EndPoint ep = (EndPoint)iep;
      ICMP packet = new ICMP();
      packet.Type = 0x08;
      packet.Code = 0x00;
      packet.Checksum = 0;
      Buffer.BlockCopy(BitConverter.GetBytes(1), 0, packet.Message, 0, 2);
      Buffer.BlockCopy(BitConverter.GetBytes(1), 0, packet.Message, 2, 2);
      data = Encoding.ASCII.GetBytes("test packet");
      Buffer.BlockCopy(data, 0, packet.Message, 4, data.Length);
      packet.MessageSize = data.Length + 4;
      int packetsize = packet.MessageSize + 4;
      UInt16 chcksum = packet.getChecksum();
      packet.Checksum = chcksum;
      host.SetSocketOption(SocketOptionLevel.Socket, SocketOptionName.ReceiveTimeout, 3000);
      int badcount = 0;
      for (int i = 1; i < 50; i++)
      {
         host.SetSocketOption(SocketOptionLevel.IP, SocketOptionName.IpTimeToLive, i);
         timestart = Environment.TickCount;
         host.SendTo(packet.getBytes(), packetsize, SocketFlags.None, iep);
         try
         {
            data = new byte[1024];
            recv = host.ReceiveFrom(data, ref ep);
            timestop = Environment.TickCount;
            ICMP response = new ICMP(data, recv);
            if (response.Type == 11)
               Console.WriteLine("hop {0}: response from {1}, {2}ms", i, ep.ToString(), timestop-timestart);
            if (response.Type == 0)
            {
               Console.WriteLine("{0} reached in {1} hops, {2}ms.", ep.ToString(), i, timestop-timestart);
               break;
            }
            badcount = 0;
         } catch (SocketException)
         {
            Console.WriteLine("hop {0}: No response from remote host", i);
            badcount++;
            if (badcount == 5)
            {
               Console.WriteLine("Unable to contact remote host");
               break;
            }
         }
      }
      
      host.Close();
   }
}
class ICMP
{
   public byte Type;
   public byte Code;
   public UInt16 Checksum;
   public int MessageSize;
   public byte[] Message = new byte[1024];
   public ICMP()
   {
   }
   public ICMP(byte[] data, int size)
   {
      Type = data[20];
      Code = data[21];
      Checksum = BitConverter.ToUInt16(data, 22);
      MessageSize = size - 24;
      Buffer.BlockCopy(data, 24, Message, 0, MessageSize);
   }
   public byte[] getBytes()
   {
      byte[] data = new byte[MessageSize + 9];
      Buffer.BlockCopy(BitConverter.GetBytes(Type), 0, data, 0, 1);
      Buffer.BlockCopy(BitConverter.GetBytes(Code), 0, data, 1, 1);
      Buffer.BlockCopy(BitConverter.GetBytes(Checksum), 0, data, 2, 2);
      Buffer.BlockCopy(Message, 0, data, 4, MessageSize);
      return data;
   }
   public UInt16 getChecksum()
   {
      UInt32 chcksm = 0;
      byte[] data = getBytes();
      int packetsize = MessageSize + 8;
      int index = 0;
      while ( index < packetsize)
      {
         chcksm += Convert.ToUInt32(BitConverter.ToUInt16(data, index));
         index += 2;
      }
      chcksm = (chcksm >> 16) + (chcksm & 0xffff);
      chcksm += (chcksm >> 16);
      return (UInt16)(~chcksm);
   }
}