Test Your DNS Response Times with DNS Tester

using System;
using System.IO;
using System.Text;
using System.Text.RegularExpressions;
using System.Drawing;
using System.Collections;
using System.ComponentModel;
using System.Windows.Forms;
using System.Data;
using System.Net;
using System.Net.Sockets;
using System.Security.Cryptography;
using System.Diagnostics;


namespace dnstester
{
	// Charles Putney
	// 18 Quinns Road
	// Co. Dublin
	// Ireland
	//
	// This file and the code contained within is freeware and may be
	// distributed and edited without restriction.
		// 
	// 
	public class DNSTester : System.Windows.Forms.Form
	{
		
		private System.Windows.Forms.TextBox DNSBox1;
		private System.Windows.Forms.TextBox DNSBox2;
		private System.Windows.Forms.Label label1;
		private System.Windows.Forms.Label label2;
		private System.Windows.Forms.Button Testbutton;
		private System.Windows.Forms.ListView ResultView;
		private System.Windows.Forms.ColumnHeader DNS1Timing;
		private System.Windows.Forms.ColumnHeader DNS2Timing;
		private System.Windows.Forms.ColumnHeader WebName;
		private System.Windows.Forms.ListBox StatusBox;
		private System.Windows.Forms.Label label5;
		private System.Windows.Forms.ColumnHeader DNS1IP;
		private System.Windows.Forms.ColumnHeader DNS2IP;
		private System.Windows.Forms.TextBox HTTPProxyBox;
		private System.Windows.Forms.Label label6;
		
		/// <summary>
		/// Required designer variable.
		/// </summary>
		private System.ComponentModel.Container components = null;

		public DNSTester()
		{
			//
			// Required for Windows Form Designer support
			//
			InitializeComponent();
				
	

			//
			// TODO: Add any constructor code after InitializeComponent call
			//
		}

		/// <summary>
		/// Clean up any resources being used.
		/// </summary>
		protected override void Dispose( bool disposing )
		{
			if( disposing )
			{
				if (components != null) 
				{
					components.Dispose();
				}
			}
			base.Dispose( disposing );
		}

		#region Windows Form Designer generated code
		/// <summary>
		/// Required method for Designer support - do not modify
		/// the contents of this method with the code editor.
		/// </summary>
		private void InitializeComponent()
		{
			this.DNSBox1 = new System.Windows.Forms.TextBox();
			this.DNSBox2 = new System.Windows.Forms.TextBox();
			this.Testbutton = new System.Windows.Forms.Button();
			this.ResultView = new System.Windows.Forms.ListView();
			this.WebName = new System.Windows.Forms.ColumnHeader();
			this.DNS1IP = new System.Windows.Forms.ColumnHeader();
			this.DNS1Timing = new System.Windows.Forms.ColumnHeader();
			this.DNS2IP = new System.Windows.Forms.ColumnHeader();
			this.DNS2Timing = new System.Windows.Forms.ColumnHeader();
			this.StatusBox = new System.Windows.Forms.ListBox();
			this.HTTPProxyBox = new System.Windows.Forms.TextBox();
			this.label1 = new System.Windows.Forms.Label();
			this.label2 = new System.Windows.Forms.Label();
			this.label5 = new System.Windows.Forms.Label();
			this.label6 = new System.Windows.Forms.Label();
			this.SuspendLayout();
			// 
			// DNSBox1
			// 
			this.DNSBox1.Location = new System.Drawing.Point(96, 40);
			this.DNSBox1.Name = "DNSBox1";
			this.DNSBox1.TabIndex = 12;
			this.DNSBox1.Text = "4.2.2.1";
			this.DNSBox1.TextChanged += new System.EventHandler(this.DNSBox1_TextChanged);
			// 
			// DNSBox2
			// 
			this.DNSBox2.Location = new System.Drawing.Point(292, 40);
			this.DNSBox2.Name = "DNSBox2";
			this.DNSBox2.TabIndex = 1;
			this.DNSBox2.Text = "152.158.16.48";
			this.DNSBox2.TextChanged += new System.EventHandler(this.DNSBox2_TextChanged);
			// 
			// Testbutton
			// 
			this.Testbutton.Location = new System.Drawing.Point(632, 24);
			this.Testbutton.Name = "Testbutton";
			this.Testbutton.TabIndex = 4;
			this.Testbutton.Text = "Test";
			this.Testbutton.Click += new System.EventHandler(this.Testbutton_Click);
			// 
			// ResultView
			// 
			this.ResultView.Columns.AddRange(new System.Windows.Forms.ColumnHeader[] {
																						 this.WebName,
																						 this.DNS1IP,
																						 this.DNS1Timing,
																						 this.DNS2IP,
																						 this.DNS2Timing});
			this.ResultView.GridLines = true;
			this.ResultView.HeaderStyle = System.Windows.Forms.ColumnHeaderStyle.Nonclickable;
			this.ResultView.Location = new System.Drawing.Point(56, 80);
			this.ResultView.MultiSelect = false;
			this.ResultView.Name = "ResultView";
			this.ResultView.Size = new System.Drawing.Size(700, 344);
			this.ResultView.TabIndex = 11;
			this.ResultView.View = System.Windows.Forms.View.Details;
			// 
			// WebName
			// 
			this.WebName.Text = "                  URL";
			this.WebName.Width = 160;
			// 
			// DNS1IP
			// 
			this.DNS1IP.Text = "IP Address from DNS 1";
			this.DNS1IP.TextAlign = System.Windows.Forms.HorizontalAlignment.Center;
			this.DNS1IP.Width = 140;
			// 
			// DNS1Timing
			// 
			this.DNS1Timing.Text = "DNS 1 Timing";
			this.DNS1Timing.TextAlign = System.Windows.Forms.HorizontalAlignment.Center;
			this.DNS1Timing.Width = 120;
			// 
			// DNS2IP
			// 
			this.DNS2IP.Text = "IP Address from DNS 2";
			this.DNS2IP.TextAlign = System.Windows.Forms.HorizontalAlignment.Center;
			this.DNS2IP.Width = 140;
			// 
			// DNS2Timing
			// 
			this.DNS2Timing.Text = "DNS 2 Timing";
			this.DNS2Timing.TextAlign = System.Windows.Forms.HorizontalAlignment.Center;
			this.DNS2Timing.Width = 120;
			// 
			// StatusBox
			// 
			this.StatusBox.HorizontalScrollbar = true;
			this.StatusBox.Location = new System.Drawing.Point(80, 456);
			this.StatusBox.Name = "StatusBox";
			this.StatusBox.Size = new System.Drawing.Size(616, 95);
			this.StatusBox.TabIndex = 13;
			// 
			// HTTPProxyBox
			// 
			this.HTTPProxyBox.Location = new System.Drawing.Point(488, 40);
			this.HTTPProxyBox.Name = "HTTPProxyBox";
			this.HTTPProxyBox.TabIndex = 15;
			this.HTTPProxyBox.Text = "";
			this.HTTPProxyBox.TextChanged += new System.EventHandler(this.HTTPProxyBox_TextChanged);
			// 
			// label1
			// 
			this.label1.Location = new System.Drawing.Point(96, 16);
			this.label1.Name = "label1";
			this.label1.TabIndex = 2;
			this.label1.Text = "DNS 1";
			this.label1.TextAlign = System.Drawing.ContentAlignment.MiddleCenter;
			// 
			// label2
			// 
			this.label2.Location = new System.Drawing.Point(288, 16);
			this.label2.Name = "label2";
			this.label2.TabIndex = 3;
			this.label2.Text = "DNS 2";
			this.label2.TextAlign = System.Drawing.ContentAlignment.MiddleCenter;
			// 
			// label5
			// 
			this.label5.Location = new System.Drawing.Point(16, 488);
			this.label5.Name = "label5";
			this.label5.Size = new System.Drawing.Size(56, 24);
			this.label5.TabIndex = 14;
			this.label5.Text = "Status";
			// 
			// label6
			// 
			this.label6.Location = new System.Drawing.Point(488, 16);
			this.label6.Name = "label6";
			this.label6.TabIndex = 16;
			this.label6.Text = "HTTP Proxy";
			this.label6.TextAlign = System.Drawing.ContentAlignment.MiddleCenter;
			// 
			// DNSTester
			// 
			this.AutoScaleBaseSize = new System.Drawing.Size(5, 13);
			this.ClientSize = new System.Drawing.Size(792, 573);
			this.Controls.Add(this.HTTPProxyBox);
			this.Controls.Add(this.DNSBox1);
			this.Controls.Add(this.DNSBox2);
			this.Controls.Add(this.StatusBox);
			this.Controls.Add(this.ResultView);
			this.Controls.Add(this.Testbutton);
			this.Controls.Add(this.label1);
			this.Controls.Add(this.label2);
			this.Controls.Add(this.label5);
			this.Controls.Add(this.label6);
			this.Name = "DNSTester";
			this.Text = "DNS Tester";
			this.ResumeLayout(false);

		}
		#endregion

		/// <summary>
		/// The main entry point for the application.
		/// </summary>
		/// 
		public string DNS1,DNS2;
		public ListViewItem listURL = new ListViewItem();
		public ListViewItem.ListViewSubItem listDNS1IP = new ListViewItem.ListViewSubItem();		
		public ListViewItem.ListViewSubItem listDNS1time = new ListViewItem.ListViewSubItem();	
		public ListViewItem.ListViewSubItem listDNS2IP = new ListViewItem.ListViewSubItem();		
		public ListViewItem.ListViewSubItem listDNS2time = new ListViewItem.ListViewSubItem();

				
		

		[STAThread]
		
		static void Main() 
		{
			Application.Run(new DNSTester());
		}

		
		private void Testbutton_Click(object sender, System.EventArgs e)
		{
			int i;
			string[] CleanNames = new string[500];
			int CleanNamesCount=0;
		
			DNS1=DNSBox1.Text;
			DNS2=DNSBox2.Text;
			
			ResultView.Items.Clear();
			ResultView.Update();
			Application.DoEvents();


			GetWebAddresses(ref CleanNames,ref CleanNamesCount);

			for (i=0;i<CleanNamesCount;i++)
			{	
				ListViewItem listURL = new ListViewItem(CleanNames[i]);
				listURL.SubItems.Add(" ");
				listURL.SubItems.Add(" ");
				listURL.SubItems.Add(" ");
				listURL.SubItems.Add(" ");

				ResultView.Items.Add(listURL);
			}
				ResultView.EnsureVisible(ResultView.Items.Count-1);
		
				ResultView.Update();
				Application.DoEvents();
				
				CheckDNS(CleanNames,CleanNamesCount,DNS1,DNS2);
				
		}

		private void GetWebAddresses(ref string[] CleanNames, ref int CleanNamesCount)
		{
			int i,j;
			byte[] random = new Byte[256];
			string Letters="";
			// Make a 3 letter random string
			
			//RNGCryptoServiceProvider is an implementation of a random number generator.
			RNGCryptoServiceProvider rng = new RNGCryptoServiceProvider();
			rng.GetBytes(random); // The array is now filled with cryptographically strong random bytes.
			for (i=1;i<256;i++)
			{
				// Just take the first three letters
				if (random[i] > 0x40 && random[i] < 0x5b) Letters=Letters+Convert.ToChar(random[i]);
				if (Letters.Length == 3)break;
			}
		
			// Use Google to get random addresses for DNS testing

			// Initialize the WebRequest.
			StatusBoxPrint("Web Proxy set to: " + HTTPProxyBox.Text);
			StatusBoxPrint("Getting Google request");
			try
			{
				WebRequest GoogleRequest = WebRequest.Create("http://www.google.com/search?num=100&q="+Letters); //Letters);
				WebResponse GoogleResponse = GoogleRequest.GetResponse();
				Application.DoEvents();
				// Get the response stream.
				Stream GoogleStream = GoogleResponse.GetResponseStream();
				StatusBoxPrint("Google response received");
				// Use a StreamReader to read the entire response.
				
				StreamReader GoogleReader = new StreamReader(GoogleStream, Encoding.ASCII);
				string GoogleString = GoogleReader.ReadToEnd();
				// Close the response stream and response to free resources.
				GoogleStream.Close();
				GoogleResponse.Close();
				Application.DoEvents();

				// find all .xxx.com addresses
				MatchCollection HostNames;
				string[] Names = new string[1000];
				// Create a new Regex object and define the regular expression.
				Regex Dotcom = new Regex("[.]([A-Za-z]*)[.]com"); 
				// Use the Matches method to find all matches in the input string.
				HostNames = Dotcom.Matches(GoogleString);
				
				Application.DoEvents();
				// Loop through the match collection to retrieve all 
				// matches and delete the leading "."
				for (i = 0; i < HostNames.Count; i++) 
				{
					Names[i]= HostNames[i].Value.Remove(0,1);  
				}
				// eliminate google.com and repeated entries
				for (i=0; i<HostNames.Count-1;i++)
				{
					if (Names[i]=="google.com") Names[i]="";
					for (j=i+1;j<HostNames.Count;j++)
					{
						if (Names[i]==Names[j]) Names[j]="";
					}
				}
				// count list and compact
				j=0;
				for (i=0;i<HostNames.Count;i++)
				{
					if (Names[i] != "")
					{
						CleanNames[j]=Names[i];
						j++;
					}
				}
				CleanNamesCount=j;
				StatusBoxPrint(CleanNamesCount + " Random URL's found");
			
			}
			catch
			{
				StatusBoxPrint("Host Google.com not found - are you connected ?");
			}

		}

	
		private void CheckDNS(string[] URLNames, int URLNamescount, string DNSAddress1, string DNSAddress2)
		{
			int i;
			const int IPPort=53;
			const string TransactionID1="Q1"; // Use transaction ID of Q1 and Q2 to identify our packet and DNS
			const string TransactionID2="Q2";
			const string TypeString="\u0001"+"\u0000"+"\u0000"+"\u0001"+"\u0000"+"\u0000"+"\u0000"+"\u0000"+"\u0000"+"\u0000";
			const string TrailerString="\u0000"+"\u0000"+"\u0001"+"\u0000"+"\u0001";
			const int DNSReceiveTimeout=5000;
			string URLNameStart, DomainName, QueryString, ReceiveString, IPResponse, sDeltaTime;
			int URLNameStartLength,DomainNameLength,index, TransactionDNS;
			byte[] Sendbytes = new byte[256];
			long StartTime, StopTime;
			string DeltaTime;
			Socket DNSsocket = new Socket(AddressFamily.InterNetwork, SocketType.Dgram, ProtocolType.Udp);
			DNSsocket.SetSocketOption(SocketOptionLevel.Socket, SocketOptionName.ReceiveTimeout, DNSReceiveTimeout);
			IPEndPoint dnsEP1 = new IPEndPoint(IPAddress.Parse(DNSAddress1),IPPort);
			IPEndPoint dnsEP2 = new IPEndPoint(IPAddress.Parse(DNSAddress2),IPPort);

			// Start the clock
			StartTime=DateTime.Now.Ticks;

			// i=0; // for testing - do one
			for (i=0;i<URLNamescount;i++)
			{
				URLNameStart = URLNames[i].Substring(0,URLNames[i].IndexOf("."));
				DomainName = URLNames[i].Substring(URLNames[i].IndexOf(".")+1,URLNames[i].Length-URLNames[i].IndexOf(".")-1);
				// Build the query 
				QueryString = TransactionID1+TypeString+(char)URLNameStart.Length+URLNameStart+(char)DomainName.Length+DomainName+TrailerString;
				Sendbytes = Encoding.ASCII.GetBytes(QueryString);
				DNSsocket.SendTo(Sendbytes, Sendbytes.Length, SocketFlags.None, dnsEP1);

				// send the same message to both DNS servers except for the transaction ID
				QueryString = TransactionID2+TypeString+(char)URLNameStart.Length+URLNameStart+(char)DomainName.Length+DomainName+TrailerString;
				Sendbytes = Encoding.ASCII.GetBytes(QueryString);
				DNSsocket.SendTo(Sendbytes, Sendbytes.Length, SocketFlags.None, dnsEP2);
			}
		
			byte[] Receivebytes = new byte[512];

			try
			{
				// wait for a response up to timeout
			more: DNSsocket.Receive(Receivebytes);

				
				// make sure the message returned is ours
				if (Receivebytes[0] == Sendbytes[0] && (Receivebytes[1] == 0x31) || (Receivebytes[1] == 0x32))
				{
					if (Receivebytes[2] == 0x81 && Receivebytes[3] == 0x80)
					{
						// Get the time now
						StopTime = DateTime.Now.Ticks;
						DeltaTime = Convert.ToString((double)(StopTime - StartTime)/10000000);
						
						// Decode the answers
						// Find the URL that was returned
						TransactionDNS=Receivebytes[1];
						ReceiveString = Encoding.ASCII.GetString(Receivebytes);
						index=12;
						URLNameStartLength=Receivebytes[index];
						index++;
						URLNameStart=ReceiveString.Substring(index,URLNameStartLength);
						index=index+URLNameStartLength;
						DomainNameLength=Receivebytes[index];
						index++;
						DomainName=ReceiveString.Substring(index,DomainNameLength);
						index=index+DomainNameLength;
						index=index+8;

						// Get the record type
						int ResponseType=Receivebytes[index];
						index=index+9;

						// Get the IP address if applicable
						IPResponse="";
						switch (ResponseType)
						{
							case 1: IPResponse = Convert.ToString(Receivebytes[index])+"."
										+ Convert.ToString(Receivebytes[index+1])+"."
										+ Convert.ToString(Receivebytes[index+2])+"."
										+ Convert.ToString(Receivebytes[index+3]); break;
							case 5: IPResponse = "CNAME"; break;
							case 6: IPResponse = "SOA"; break;
						}
						StatusBoxPrint("DNS Answer: "+URLNameStart+"."+DomainName+" = "+IPResponse);
				
						// Find the URL entry in the list
						for (i=0;i<ResultView.Items.Count;i++)
						{
							if (ResultView.Items[i].Text == URLNameStart+"."+DomainName)
							{	
							
								switch (TransactionDNS)
								{
									case 0x31:
										ResultView.Items[i].SubItems[1].Text=Convert.ToString(IPResponse);
										sDeltaTime=Convert.ToString(DeltaTime);
										if (sDeltaTime.Length > 5) ResultView.Items[i].SubItems[2].Text = sDeltaTime.Substring(0,5);
										else ResultView.Items[i].SubItems[2].Text = sDeltaTime;
										ResultView.Items[i].ForeColor=System.Drawing.Color.Red;
										ResultView.EnsureVisible(i);
										ResultView.Update();
										Application.DoEvents();
										ResultView.Items[i].ForeColor=System.Drawing.Color.Black;
										break;

									case 0x32:
										ResultView.Items[i].SubItems[3].Text=Convert.ToString(IPResponse);
										sDeltaTime=Convert.ToString(DeltaTime);
										if (sDeltaTime.Length > 5) ResultView.Items[i].SubItems[4].Text = sDeltaTime.Substring(0,5);
										else ResultView.Items[i].SubItems[4].Text = sDeltaTime;
										ResultView.Items[i].ForeColor=System.Drawing.Color.Red;
										ResultView.EnsureVisible(i);
										ResultView.Update();
										Application.DoEvents();
										ResultView.Items[i].ForeColor=System.Drawing.Color.Black;
										break;
								}
							}
						}
					}
					goto more;
				}
			}
			catch (SocketException e)
			{
				if (Convert.ToString(e).IndexOf("time")>0)
				{
					StatusBoxPrint("Timeout - No response received for "+ Convert.ToString (DNSReceiveTimeout/1000) + " seconds");
				}
				else
				{
					StatusBoxPrint(Convert.ToString(e)); // for testing	
				}
			}
			finally
			{
				// close the socket
				DNSsocket.Close();
			}
		
		}
	
			private void StatusBox_TextChanged(object sender, System.EventArgs e)
		{
			StatusBox.TopIndex=StatusBox.Items.Count;
			StatusBox.Update();
		}
		private void StatusBoxPrint(string LogText)
		{
			StatusBox.Items.Add(DateTime.Now+"  "+LogText);
			StatusBox.TopIndex=StatusBox.Items.Count-1;
			if (StatusBox.Items.Count > 5000)
			{
				StatusBox.Items.RemoveAt(0);
			}
			StatusBox.Update();
		}
		private void DNSAvg1Box_TextChanged(object sender, System.EventArgs e)
		{
		
		}

		private void DNSAvg2Box_TextChanged(object sender, System.EventArgs e)
		{
		
		}

		private void DNSBox1_TextChanged(object sender, System.EventArgs e)
		{
			DNS1=DNSBox1.Text;
		}

		private void DNSBox2_TextChanged(object sender, System.EventArgs e)
		{
			DNS2=DNSBox2.Text;
		}

	
		private void ResultBox_SelectedIndexChanged(object sender, System.EventArgs e)
		{
		
		}

		private void HTTPProxyBox_TextChanged(object sender, System.EventArgs e)
		{
			if (HTTPProxyBox.Text != "")
			{
				GlobalProxySelection.Select = new WebProxy(HTTPProxyBox.Text);
			}
			else
			{
				GlobalProxySelection.Select = GlobalProxySelection.GetEmptyWebProxy();
			}
		}
	}

}