Updated

2023-03-02 10:02:06 +01:00
parent cd376044d5
commit 4afe9153ed
4 changed files with 122 additions and 77 deletions
--- a/EonaCat.DnsTester/Helpers/DnsHelper.cs
+++ b/EonaCat.DnsTester/Helpers/DnsHelper.cs
@@ -146,14 +146,27 @@ namespace EonaCat.DnsTester.Helpers
        {
            Console.WriteLine("new byte[] { " + responseBytes + " }");

+            // Check if response is valid
+            if (responseBytes.Length < 12)
+            {
+                throw new Exception("Invalid DNS response");
+            }
+
            // Set the offset to the start
            var offset = 0;

            // Parse the DNS header
            ushort id = (ushort)((responseBytes[0] << 8) | responseBytes[1]);
            ushort flags = (ushort)((responseBytes[2] << 8) | responseBytes[3]);
+            bool isResponse = (flags & 0x8000) != 0;
            ushort qdcount = (ushort)((responseBytes[4] << 8) | responseBytes[5]);
            ushort ancount = (ushort)((responseBytes[6] << 8) | responseBytes[7]);
+
+            if (!isResponse)
+            {
+                throw new Exception("Invalid DNS response");
+            }
+
            ushort nscount = (ushort)((responseBytes[8] << 8) | responseBytes[9]);
            ushort arcount = (ushort)((responseBytes[10] << 8) | responseBytes[11]);
            
@@ -243,62 +256,53 @@ namespace EonaCat.DnsTester.Helpers
        static ResourceRecord ParseDnsAnswerRecord(byte[] responseBytes, ref int offset)
        {
            // Parse the DNS name
-            string name = DnsNameParser.ParseName(responseBytes, ref offset);
+            string name = DnsNameParser.ExtractDomainName(responseBytes, ref offset);
            if (name == null)
            {
                return null;
            }

            // Parse the DNS type, class, ttl, and data length
-            DnsRecordType type = (DnsRecordType)((responseBytes[offset] << 8) | responseBytes[offset++]);
-            DnsRecordClass klass = (DnsRecordClass)((responseBytes[offset] << 8) | responseBytes[offset++]);
-            uint ttl = (uint)((responseBytes[offset] << 24) | (responseBytes[offset++] << 16) | (responseBytes[offset++] << 8) | responseBytes[offset++]);
-            ushort rdlen = (ushort)((responseBytes[offset] << 8) + responseBytes[offset++]);
-            offset += 10;
+            DnsRecordType type = (DnsRecordType)((responseBytes[offset++] << 8) + responseBytes[offset++]);
+            DnsRecordClass klass = (DnsRecordClass)((responseBytes[offset++] << 8) + responseBytes[offset++]);
+            int ttl = (responseBytes[offset++] << 24) + (responseBytes[offset++] << 16) + (responseBytes[offset++] << 8) + responseBytes[offset++];

-            // Parse the DNS data
-            string data = null;
+            // Extract record data length
+            int dataLength = (responseBytes[offset] << 8) + responseBytes[offset + 1];
+            offset += 2;
+
+            // Extract record data
+            byte[] recordData = new byte[dataLength];
+            Buffer.BlockCopy(responseBytes, offset, recordData, 0, dataLength);
+
+            string recordDataAsString = null;
            switch ((DnsRecordType)type)
            {
                case DnsRecordType.A:
-                    if (rdlen != 4)
+                    if (dataLength != 4)
                    {
                        return null;
                    }
-
-                    data = new IPAddress(new byte[]
-                    {
-                responseBytes[offset], responseBytes[offset + 1], responseBytes[offset + 2],
-                responseBytes[offset + 3]
-                    }).ToString();
-                    offset += rdlen;
+                    recordDataAsString = new IPAddress(recordData).ToString();
+                    offset += recordData.Length;
                    break;
                case DnsRecordType.CNAME:
+                    recordDataAsString = DnsNameParser.ExtractDomainName(responseBytes, ref offset);
+                    break;
                case DnsRecordType.NS:
-                    data = DnsNameParser.ParseName(responseBytes, ref offset);
-                    if (data == null)
-                    {
-                        return null;
-                    }
-
+                    recordDataAsString = DnsNameParser.ExtractDomainName(responseBytes, ref offset);
                    break;
                case DnsRecordType.MX:
-                    ushort preference = (ushort)((responseBytes[offset] << 8) | responseBytes[offset + 1]);
+                    int preference = (responseBytes[0] << 8) + responseBytes[1];
                    offset += 2;
-                    string exchange = DnsNameParser.ParseName(responseBytes, ref offset);
-                    if (exchange == null)
-                    {
-                        return null;
-                    }
-
-                    data = $"{preference} {exchange}";
+                    string exchange = DnsNameParser.ExtractDomainName(responseBytes, ref offset);
+                    recordDataAsString = $"{preference} {exchange}";
                    break;
                case DnsRecordType.TXT:
-                    data = Encoding.ASCII.GetString(responseBytes, offset, rdlen);
-                    offset += rdlen;
+                    recordDataAsString = Encoding.ASCII.GetString(recordData);
                    break;
                default:
-                    offset += rdlen;
+                    offset += dataLength;
                    break;
            }

@@ -308,7 +312,7 @@ namespace EonaCat.DnsTester.Helpers
                Type = type,
                Class = klass,
                Ttl = TimeSpan.FromSeconds(ttl),
-                Data = data,
+                Data = recordDataAsString,
            };
        }

@@ -358,7 +362,7 @@ namespace EonaCat.DnsTester.Helpers
    {
        A = 1,
        NS = 2,
-        CNAME = 5,
+        CNAME = 6,
        MX = 15,
        TXT = 16,
        AAAA = 28,
--- a/EonaCat.DnsTester/Helpers/DnsNameParser.cs
+++ b/EonaCat.DnsTester/Helpers/DnsNameParser.cs
@@ -1,4 +1,5 @@
 using System.Collections.Generic;
+using System.Text;

 namespace EonaCat.DnsTester.Helpers
 {
@@ -29,5 +30,34 @@ namespace EonaCat.DnsTester.Helpers

            return string.Join(".", labels);
        }
+
+        public static string ExtractDomainName(byte[] buffer, ref int offset)
+        {
+            List<string> labels = new List<string>();
+
+            while (true)
+            {
+                byte labelLength = buffer[offset++];
+
+                if (labelLength == 0)
+                {
+                    break;
+                }
+
+                if ((labelLength & 0xC0) == 0xC0)
+                {
+                    // Compressed domain name
+                    int pointer = (int)(((labelLength & 0x3F) << 8) + buffer[offset++]);
+                    labels.Add(ExtractDomainName(buffer, ref pointer));
+                    break;
+                }
+
+                string label = Encoding.ASCII.GetString(buffer, offset, labelLength);
+                labels.Add(label);
+                offset += labelLength;
+            }
+
+            return string.Join(".", labels);
+        }
    }
 }
--- a/EonaCat.DnsTester/MainForm.Designer.cs
+++ b/EonaCat.DnsTester/MainForm.Designer.cs
@@ -49,9 +49,9 @@
            StatusBox = new System.Windows.Forms.ListBox();
            ResultView = new System.Windows.Forms.ListView();
            Url = new System.Windows.Forms.ColumnHeader();
-            DNS1IP = new System.Windows.Forms.ColumnHeader();
+            DNS1DATA = new System.Windows.Forms.ColumnHeader();
            DNS1Performance = new System.Windows.Forms.ColumnHeader();
-            DNS2IP = new System.Windows.Forms.ColumnHeader();
+            DNS2DATA = new System.Windows.Forms.ColumnHeader();
            DNS2Performance = new System.Windows.Forms.ColumnHeader();
            panel3 = new System.Windows.Forms.Panel();
            btnResolveHost = new System.Windows.Forms.Button();
@@ -273,7 +273,7 @@
            // 
            // ResultView
            // 
-            ResultView.Columns.AddRange(new System.Windows.Forms.ColumnHeader[] { Url, DNS1IP, DNS1Performance, DNS2IP, DNS2Performance });
+            ResultView.Columns.AddRange(new System.Windows.Forms.ColumnHeader[] { Url, DNS1DATA, DNS1Performance, DNS2DATA, DNS2Performance });
            ResultView.GridLines = true;
            ResultView.HeaderStyle = System.Windows.Forms.ColumnHeaderStyle.Nonclickable;
            ResultView.Location = new System.Drawing.Point(56, 49);
@@ -290,27 +290,27 @@
            Url.Text = "URL";
            Url.Width = 160;
            // 
-            // DNS1IP
+            // DNS1DATA
            // 
-            DNS1IP.Text = "IP Address from DNS 1";
-            DNS1IP.TextAlign = System.Windows.Forms.HorizontalAlignment.Center;
-            DNS1IP.Width = 140;
+            DNS1DATA.Text = "Data";
+            DNS1DATA.TextAlign = System.Windows.Forms.HorizontalAlignment.Center;
+            DNS1DATA.Width = 140;
            // 
            // DNS1Performance
            // 
-            DNS1Performance.Text = "DNS 1 Performance";
+            DNS1Performance.Text = "Performance";
            DNS1Performance.TextAlign = System.Windows.Forms.HorizontalAlignment.Center;
            DNS1Performance.Width = 120;
            // 
-            // DNS2IP
+            // DNS2DATA
            // 
-            DNS2IP.Text = "IP Address from DNS 2";
-            DNS2IP.TextAlign = System.Windows.Forms.HorizontalAlignment.Center;
-            DNS2IP.Width = 140;
+            DNS2DATA.Text = "Data";
+            DNS2DATA.TextAlign = System.Windows.Forms.HorizontalAlignment.Center;
+            DNS2DATA.Width = 140;
            // 
            // DNS2Performance
            // 
-            DNS2Performance.Text = "DNS 2 Performance";
+            DNS2Performance.Text = "Performance";
            DNS2Performance.TextAlign = System.Windows.Forms.HorizontalAlignment.Center;
            DNS2Performance.Width = 120;
            // 
@@ -428,9 +428,9 @@
        private System.Windows.Forms.ListBox StatusBox;
        private System.Windows.Forms.ListView ResultView;
        private System.Windows.Forms.ColumnHeader Url;
-        private System.Windows.Forms.ColumnHeader DNS1IP;
+        private System.Windows.Forms.ColumnHeader DNS1DATA;
        private System.Windows.Forms.ColumnHeader DNS1Performance;
-        private System.Windows.Forms.ColumnHeader DNS2IP;
+        private System.Windows.Forms.ColumnHeader DNS2DATA;
        private System.Windows.Forms.ColumnHeader DNS2Performance;
        private System.Windows.Forms.Panel panel3;
        private System.Windows.Forms.Button btnResolveHost;
--- a/EonaCat.DnsTester/MainForm.cs
+++ b/EonaCat.DnsTester/MainForm.cs
@@ -273,38 +273,49 @@ namespace EonaCat.DnsTester
            var stopTime = DateTime.Now.Ticks;
            var deltaTime = Convert.ToString((double)(stopTime - dnsResponse.StartTime) / 10000000, CultureInfo.InvariantCulture);

-            SetStatus($"ResourceRecord: Name: {dnsResponse.Answers.FirstOrDefault().Name} : Type : {dnsResponse.Answers.FirstOrDefault().Type} : Data :  {dnsResponse.Answers.FirstOrDefault().Data}");
+            foreach (var answer in dnsResponse.Answers)
+            {
+                SetStatus(
+                    $"ResourceRecord: Name: {answer.Name} : Type : {answer.Type} : Data :  {answer.Data}");
+            }
+

            for (int i = 0; i < ResultView.Items.Count; i++)
            {
-                if (ResultView.Items[i].Text != $"{dnsResponse.Answers.FirstOrDefault().Name.TrimEnd('.')}") continue;
-
-                string sDeltaTime;
-                switch (dnsResponse.DnsId)
+                foreach (var answer in dnsResponse.Answers)
                {
-                    case "Dns1":
-                        ResultView.Items[i].SubItems[1].Text = Convert.ToString(dnsResponse.Answers.FirstOrDefault().Data);
-                        sDeltaTime = Convert.ToString(deltaTime);
-                        ResultView.Items[i].SubItems[2].Text =
-                            sDeltaTime.Length > 5 ? sDeltaTime.Substring(0, 5) : 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;
+                    if (ResultView.Items[i].Text != $"{answer.Name.TrimEnd('.')}")
+                        continue;

-                    case "Dns2":
-                        ResultView.Items[i].SubItems[3].Text = Convert.ToString(dnsResponse.Answers.FirstOrDefault().Data);
-                        sDeltaTime = Convert.ToString(deltaTime);
-                        ResultView.Items[i].SubItems[4].Text =
-                            sDeltaTime.Length > 5 ? sDeltaTime.Substring(0, 5) : 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;
+                    string sDeltaTime;
+                    switch (dnsResponse.DnsId)
+                    {
+                        case "Dns1":
+                            ResultView.Items[i].SubItems[1].Text =
+                                Convert.ToString(answer.Data);
+                            sDeltaTime = Convert.ToString(deltaTime);
+                            ResultView.Items[i].SubItems[2].Text =
+                                sDeltaTime.Length > 5 ? sDeltaTime.Substring(0, 5) : 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 "Dns2":
+                            ResultView.Items[i].SubItems[3].Text =
+                                Convert.ToString(answer.Data);
+                            sDeltaTime = Convert.ToString(deltaTime);
+                            ResultView.Items[i].SubItems[4].Text =
+                                sDeltaTime.Length > 5 ? sDeltaTime.Substring(0, 5) : 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;
+                    }
                }
            }
        }