Adding .NET 6 target and minor improvements (#169)

Author: MichaCo

samples/MiniDig/MiniDig.csproj

@@ -1,11 +1,10 @@
 <Project Sdk="Microsoft.NET.Sdk">
 
   <PropertyGroup>
-    <TargetFramework>net5.0</TargetFramework>
+    <TargetFramework>net6.0</TargetFramework>
     <AssemblyName>MiniDig</AssemblyName>
     <OutputType>Exe</OutputType>
     <PackageId>MiniDig</PackageId>
-    <LangVersion>latest</LangVersion>
   </PropertyGroup>
   <PropertyGroup>
     <TreatWarningsAsErrors>false</TreatWarningsAsErrors>

src/DnsClient/DnsClient.csproj

@@ -1,9 +1,9 @@
-<Project Sdk="Microsoft.NET.Sdk">
+<Project Sdk="Microsoft.NET.Sdk">
   <PropertyGroup>
-    <VersionPrefix>1.6.1</VersionPrefix>
+    <VersionPrefix>1.7.0</VersionPrefix>
     <VersionSuffix Condition="'$(VersionSuffix)'!='' AND '$(BuildNumber)' != ''">$(VersionSuffix)-$(BuildNumber)</VersionSuffix>
 
-    <TargetFrameworks>net5.0;netstandard1.3;netstandard2.0;netstandard2.1;net45;net471</TargetFrameworks>
+    <TargetFrameworks>net6.0;net5.0;netstandard1.3;netstandard2.0;netstandard2.1;net45;net471</TargetFrameworks>
     <DebugType>full</DebugType>
 
     <Product>DnsClient.NET</Product>
@@ -21,11 +21,12 @@
     <PackageTags>dns;client;stub;resolver;name;server;core;service;discovery</PackageTags>
 
     <PackageIcon>icon.png</PackageIcon>
+    <PackageReadmeFile>README.md</PackageReadmeFile>
     <PackageProjectUrl>http://dnsclient.michaco.net</PackageProjectUrl>
     <PackageLicenseExpression>Apache-2.0</PackageLicenseExpression>
     <WebPage>http://dnsclient.michaco.net</WebPage>
     <RepositoryType>git</RepositoryType>
-    <RepositoryUrl>https://github.com/MichaCo/DnsClient.NET</RepositoryUrl>
+    <RepositoryUrl>https://github.com/MichaCo/DnsClient.NET</RepositoryUrl>    
 
     <GenerateDocumentationFile>true</GenerateDocumentationFile>
     <LangVersion>latest</LangVersion>
@@ -40,6 +41,7 @@
 
   <ItemGroup>
     <None Include="..\..\icon.png" Pack="true" PackagePath="" />
+    <None Include="..\..\README.md" Pack="true" PackagePath="\"/>
   </ItemGroup>
 
   <ItemGroup Condition=" '$(TargetFramework)' != 'net45' ">

src/DnsClient/DnsDatagramReader.cs

@@ -8,12 +8,22 @@
 
 namespace DnsClient
 {
-    internal class DnsDatagramReader
+#pragma warning disable CS1591 // Missing XML comment for publicly visible type or member
+#pragma warning disable CS3002 // Return type is not CLS-compliant
+
+    /// <summary>
+    /// Helper to read from DNS datagrams.
+    /// </summary>
+    /// <remarks>
+    /// The API of this class might change over time and receive breaking changes. Use at own risk.
+    /// </remarks>
+    public class DnsDatagramReader
     {
         public const int IPv6Length = 16;
         public const int IPv4Length = 4;
         private const byte ReferenceByte = 0xc0;
         private const string ACEPrefix = "xn--";
+        private const int MaxRecursion = 100;
 
         private readonly byte[] _ipV4Buffer = new byte[4];
         private readonly byte[] _ipV6Buffer = new byte[16];
@@ -181,18 +191,6 @@ public void Advance(int length)
             Index += length;
         }
 
-        public void SanitizeResult(int expectedIndex, int dataLength)
-        {
-            if (Index != expectedIndex)
-            {
-                throw new DnsResponseParseException(
-                    message: $"Record reader index out of sync. Expected to read till {expectedIndex} but tried to read till index {Index}.",
-                    data: _data.ToArray(),
-                    index: Index,
-                    length: dataLength);
-            }
-        }
-
         public DnsString ReadDnsName()
         {
             var builder = StringBuilderObjectPool.Default.Get();
@@ -275,8 +273,13 @@ public DnsString ReadQuestionQueryString()
             return DnsString.FromResponseQueryString(value);
         }
 
-        public ICollection<ArraySegment<byte>> ReadLabels()
+        public IReadOnlyList<ArraySegment<byte>> ReadLabels(int recursion = 0)
         {
+            if (recursion++ >= MaxRecursion)
+            {
+                throw new DnsResponseParseException("Max recursion reached.", _data.ToArray(), Index, 0);
+            }
+
             var result = new List<ArraySegment<byte>>(10);
 
             // read the length byte for the label, then get the content from offset+1 to length
@@ -300,7 +303,7 @@ public ICollection<ArraySegment<byte>> ReadLabels()
                     }
 
                     var subReader = new DnsDatagramReader(_data.SubArrayFromOriginal(subIndex));
-                    var newLabels = subReader.ReadLabels();
+                    var newLabels = subReader.ReadLabels(recursion);
                     result.AddRange(newLabels); // add range actually much faster than concat and equal to or faster than for-each.. (array copy would work maybe)
                     return result;
                 }
@@ -353,6 +356,18 @@ public uint ReadUInt32NetworkOrder()
 
             return (uint)(ReadUInt16NetworkOrder() << 16 | ReadUInt16NetworkOrder());
         }
+
+        internal void SanitizeResult(int expectedIndex, int dataLength)
+        {
+            if (Index != expectedIndex)
+            {
+                throw new DnsResponseParseException(
+                    message: $"Record reader index out of sync. Expected to read till {expectedIndex} but tried to read till index {Index}.",
+                    data: _data.ToArray(),
+                    index: Index,
+                    length: dataLength);
+            }
+        }
     }
 
     internal static class ArraySegmentExtensions
@@ -367,4 +382,7 @@ public static ArraySegment<T> SubArrayFromOriginal<T>(this ArraySegment<T> array
             return new ArraySegment<T>(array.Array, startIndex, array.Array.Length - startIndex);
         }
     }
+
+#pragma warning restore CS3002 // Return type is not CLS-compliant
+#pragma warning restore CS1591 // Missing XML comment for publicly visible type or member
 }

src/DnsClient/DnsUdpMessageHandler.cs

@@ -95,7 +95,15 @@ public override async Task<DnsResponseMessage> QueryAsync(
 
                 using (var memory = new PooledBytes(readSize))
                 {
-#if !NET45
+
+#if NET6_0_OR_GREATER
+                    int received = await udpClient.Client.ReceiveAsync(
+                        new ArraySegment<byte>(memory.Buffer),
+                        SocketFlags.None,
+                        cancellationToken: cancellationToken).ConfigureAwait(false);
+
+                    var response = GetResponseMessage(new ArraySegment<byte>(memory.Buffer, 0, received));
+#elif !NET45
                     int received = await udpClient.Client.ReceiveAsync(new ArraySegment<byte>(memory.Buffer), SocketFlags.None).ConfigureAwait(false);
 
                     var response = GetResponseMessage(new ArraySegment<byte>(memory.Buffer, 0, received));

src/DnsClient/Internal/PooledBytes.cs

@@ -70,7 +70,7 @@ private void Dispose(bool disposing)
             if (disposing && !_disposed)
             {
                 _disposed = true;
-                s_pool.Return(_buffer.Array);
+                s_pool.Return(_buffer.Array, clearArray: true);
             }
         }
     }

src/DnsClient/Interop/Windows/NameResolutionPolicy.cs

@@ -8,6 +8,8 @@
 
 namespace DnsClient.Windows
 {
+#if !NET45
+
     internal static class NameResolutionPolicy
     {
         private static readonly char[] s_splitOn = new char[] { ';' };
@@ -19,12 +21,16 @@ internal static class NameResolutionPolicy
         internal static IReadOnlyCollection<NameServer> Resolve(bool includeGenericServers = true, bool includeDirectAccessServers = true)
         {
             var nameServers = new HashSet<NameServer>();
-#if !NET45
+
+#if NET5_0_OR_GREATER
+            if (!OperatingSystem.IsWindows())
+#else
             if (!RuntimeInformation.IsOSPlatform(OSPlatform.Windows))
+#endif
             {
                 return nameServers;
             }
-#endif
+
             // [MS-GPNRPT] dictates that the NRPT is stored in two separate registry keys.
             //
             //  - The Policy key is pushed down through Group Policy.
@@ -123,4 +129,5 @@ private static void AddServers(HashSet<NameServer> nameServers, string[] names,
             }
         }
     }
+#endif
 }

src/DnsClient/NameServer.cs

@@ -1,5 +1,6 @@
 using System;
 using System.Collections.Generic;
+using System.IO;
 using System.Linq;
 using System.Net;
 using System.Net.NetworkInformation;
@@ -254,7 +255,7 @@ public static IReadOnlyCollection<NameServer> ResolveNameServers(bool skipIPv6Si
             }
             catch (Exception ex)
             {
-                logger?.LogInformation(ex, "Resolving name servers using .NET framework failed.");
+                logger?.LogWarning(ex, "Resolving name servers using .NET framework failed.");
                 exceptions.Add(ex);
             }
 
@@ -270,7 +271,7 @@ public static IReadOnlyCollection<NameServer> ResolveNameServers(bool skipIPv6Si
                 }
                 catch (Exception ex)
                 {
-                    logger?.LogInformation(ex, "Resolving name servers using native implementation failed.");
+                    logger?.LogWarning(ex, "Resolving name servers using native implementation failed.");
                     exceptions.Add(ex);
                 }
             }
@@ -305,36 +306,39 @@ public static IReadOnlyCollection<NameServer> ResolveNameServers(bool skipIPv6Si
             }
 
 #endif
-            if (!fallbackToGooglePublicDns && exceptions.Count > 0)
-            {
-                if (exceptions.Count > 1)
-                {
-                    throw new AggregateException("Error resolving name servers", exceptions);
-                }
-                else
-                {
-                    throw new InvalidOperationException("Error resolving name servers", exceptions.First());
-                }
-            }
-
             IReadOnlyCollection<NameServer> filtered = nameServers
                 .Where(p => (p.IPEndPoint.Address.AddressFamily == AddressFamily.InterNetwork
                             || p.IPEndPoint.Address.AddressFamily == AddressFamily.InterNetworkV6)
                     && (!p.IPEndPoint.Address.IsIPv6SiteLocal || !skipIPv6SiteLocal))
                 .ToArray();
 
-            filtered = ValidateNameServers(filtered, logger);
+            try
+            {
+                filtered = ValidateNameServers(filtered, logger);
+            }
+            catch (Exception ex)
+            {
+                logger?.LogWarning(ex, "NameServer validation failed.");
+                exceptions.Add(ex);
+            }
 
-            if (filtered.Count == 0 && fallbackToGooglePublicDns)
+            if (filtered.Count == 0)
             {
-                logger?.LogWarning("Could not resolve any NameServers, falling back to Google public servers.");
-                return new NameServer[]
+                if (!fallbackToGooglePublicDns && exceptions.Count > 0)
                 {
-                    GooglePublicDnsIPv6,
-                    GooglePublicDns2IPv6,
-                    GooglePublicDns,
-                    GooglePublicDns2,
-                };
+                    throw new InvalidOperationException("Could not resolve any NameServers.", exceptions.First());
+                }
+                else if (fallbackToGooglePublicDns)
+                {
+                    logger?.LogWarning("Could not resolve any NameServers, falling back to Google public servers.");
+                    return new NameServer[]
+                    {
+                        GooglePublicDns,
+                        GooglePublicDns2,
+                        GooglePublicDnsIPv6,
+                        GooglePublicDns2IPv6
+                    };
+                }
             }
 
             logger?.LogDebug("Resolved {0} name servers: [{1}].", filtered.Count, string.Join(",", filtered.AsEnumerable()));
@@ -357,18 +361,37 @@ public static IReadOnlyCollection<NameServer> ResolveNameServers(bool skipIPv6Si
         public static IReadOnlyCollection<NameServer> ResolveNameServersNative()
         {
             List<NameServer> addresses = new List<NameServer>();
+
+#if NET5_0_OR_GREATER
+            if (OperatingSystem.IsWindows())
+#else
             if (RuntimeInformation.IsOSPlatform(OSPlatform.Windows))
+#endif
             {
-                var fixedInfo = Windows.IpHlpApi.FixedNetworkInformation.GetFixedInformation();
-
-                foreach (var ip in fixedInfo.DnsAddresses)
+                try
                 {
-                    addresses.Add(new NameServer(ip, DefaultPort, fixedInfo.DomainName));
+                    var fixedInfo = Windows.IpHlpApi.FixedNetworkInformation.GetFixedInformation();
+
+                    foreach (var ip in fixedInfo.DnsAddresses)
+                    {
+                        addresses.Add(new NameServer(ip, DefaultPort, fixedInfo.DomainName));
+                    }
                 }
+                catch { }
             }
+#if NET5_0_OR_GREATER
+            if (OperatingSystem.IsLinux() || OperatingSystem.IsMacOS())
+#else
             else if (RuntimeInformation.IsOSPlatform(OSPlatform.Linux) || RuntimeInformation.IsOSPlatform(OSPlatform.OSX))
+#endif
             {
-                addresses = Linux.StringParsingHelpers.ParseDnsAddressesFromResolvConfFile(EtcResolvConfFile);
+                try
+                {
+                    addresses = Linux.StringParsingHelpers.ParseDnsAddressesFromResolvConfFile(EtcResolvConfFile);
+                }
+                catch (Exception e) when (e is FileNotFoundException || e is UnauthorizedAccessException)
+                {
+                }
             }
 
             return addresses;
@@ -380,12 +403,7 @@ public static IReadOnlyCollection<NameServer> ResolveNameServersNative()
         /// <returns>Returns a collection of name servers from the policy table</returns>
         public static IReadOnlyCollection<NameServer> ResolveNameResolutionPolicyServers()
         {
-            if (RuntimeInformation.IsOSPlatform(OSPlatform.Windows))
-            {
-                return NameResolutionPolicy.Resolve();
-            }
-
-            return Array.Empty<NameServer>();
+            return NameResolutionPolicy.Resolve();
         }
 
 #endif
@@ -413,16 +431,20 @@ private static IReadOnlyCollection<NameServer> QueryNetworkInterfaces()
             var result = new HashSet<NameServer>();
 
             var adapters = NetworkInterface.GetAllNetworkInterfaces();
+            if (adapters == null)
+            {
+                return result.ToArray();
+            }
 
             foreach (NetworkInterface networkInterface in
                 adapters
-                    .Where(p => (p.OperationalStatus == OperationalStatus.Up || p.OperationalStatus == OperationalStatus.Unknown)
+                    .Where(p => p != null && (p.OperationalStatus == OperationalStatus.Up || p.OperationalStatus == OperationalStatus.Unknown)
                     && p.NetworkInterfaceType != NetworkInterfaceType.Loopback))
             {
-                var properties = networkInterface.GetIPProperties();
+                var properties = networkInterface?.GetIPProperties();
 
                 // Can be null under mono for whatever reason...
-                if (properties == null)
+                if (properties?.DnsAddresses == null)
                 {
                     continue;
                 }