Remove unneeded feature flags and pass cancellationToken to DNS request

src/Renci.SshNet/Abstractions/DnsAbstraction.cs

@@ -1,22 +1,8 @@
 using System;
 using System.Net;
 using System.Net.Sockets;
-using System.Threading.Tasks;
-
-#if FEATURE_DNS_SYNC
-#elif FEATURE_DNS_APM
-using Renci.SshNet.Common;
-#elif FEATURE_DNS_TAP
-#elif FEATURE_DEVICEINFORMATION_APM
-using System.Collections.Generic;
-using System.Linq;
 using System.Threading;
-using Microsoft.Phone.Net.NetworkInformation;
-#elif FEATURE_DATAGRAMSOCKET
-using System.Collections.Generic;
-using Windows.Networking;
-using Windows.Networking.Sockets;
-#endif
+using System.Threading.Tasks;
 
 namespace Renci.SshNet.Abstractions
 {
@@ -36,72 +22,27 @@ public static IPAddress[] GetHostAddresses(string hostNameOrAddress)
         {
             /* TODO Eliminate sync variant, and implement timeout */
 
-#if FEATURE_DNS_SYNC
             return Dns.GetHostAddresses(hostNameOrAddress);
-#elif FEATURE_DNS_APM
-            var asyncResult = Dns.BeginGetHostAddresses(hostNameOrAddress, null, null);
-            if (!asyncResult.AsyncWaitHandle.WaitOne(Session.InfiniteTimeSpan))
-                throw new SshOperationTimeoutException("Timeout resolving host name.");
-            return Dns.EndGetHostAddresses(asyncResult);
-#elif FEATURE_DNS_TAP
-            return Dns.GetHostAddressesAsync(hostNameOrAddress).GetAwaiter().GetResult();
-#else
-            IPAddress address;
-            if (IPAddress.TryParse(hostNameOrAddress, out address))
-                return new [] { address};
-
-#if FEATURE_DEVICEINFORMATION_APM
-            var resolveCompleted = new ManualResetEvent(false);
-            NameResolutionResult nameResolutionResult = null;
-            DeviceNetworkInformation.ResolveHostNameAsync(new DnsEndPoint(hostNameOrAddress, 0), result =>
-            {
-                nameResolutionResult = result;
-                resolveCompleted.Set();
-            }, null);
-
-            // wait until address is resolved
-            resolveCompleted.WaitOne();
-
-            if (nameResolutionResult.NetworkErrorCode == NetworkError.Success)
-            {
-                var addresses = new List<IPAddress>(nameResolutionResult.IPEndPoints.Select(p => p.Address).Distinct());
-                return addresses.ToArray();
-            }
-            throw new SocketException((int)nameResolutionResult.NetworkErrorCode);
-#elif FEATURE_DATAGRAMSOCKET
-
-            // TODO we may need to only return those IP addresses that are supported on the current system
-            // TODO http://wojciechkulik.pl/csharp/winrt-how-to-detect-supported-ip-versions
-
-            var endpointPairs = DatagramSocket.GetEndpointPairsAsync(new HostName(hostNameOrAddress), "").GetAwaiter().GetResult();
-            var addresses = new List<IPAddress>();
-            foreach (var endpointPair in endpointPairs)
-            {
-                if (endpointPair.RemoteHostName.Type == HostNameType.Ipv4 || endpointPair.RemoteHostName.Type == HostNameType.Ipv6)
-                    addresses.Add(IPAddress.Parse(endpointPair.RemoteHostName.CanonicalName));
-            }
-            if (addresses.Count == 0)
-                throw new SocketException((int) System.Net.Sockets.SocketError.HostNotFound);
-            return addresses.ToArray();
-#else
-            throw new NotSupportedException("Resolving hostname to IP address is not implemented.");
-#endif // FEATURE_DEVICEINFORMATION_APM
-#endif
         }
 
         /// <summary>
         /// Returns the Internet Protocol (IP) addresses for the specified host.
         /// </summary>
         /// <param name="hostNameOrAddress">The host name or IP address to resolve.</param>
+        /// <param name="cancellationToken">A cancellation token that can be used to signal the asynchronous operation should be canceled.</param>
         /// <returns>
         /// A task with result of an array of type <see cref="IPAddress"/> that holds the IP addresses for the host that
         /// is specified by the <paramref name="hostNameOrAddress"/> parameter.
         /// </returns>
         /// <exception cref="ArgumentNullException"><paramref name="hostNameOrAddress"/> is <see langword="null"/>.</exception>
         /// <exception cref="SocketException">An error is encountered when resolving <paramref name="hostNameOrAddress"/>.</exception>
-        public static Task<IPAddress[]> GetHostAddressesAsync(string hostNameOrAddress)
+        public static Task<IPAddress[]> GetHostAddressesAsync(string hostNameOrAddress, CancellationToken cancellationToken)
         {
+#if NET6_0_OR_GREATER
+            return Dns.GetHostAddressesAsync(hostNameOrAddress, cancellationToken);
+#else
             return Dns.GetHostAddressesAsync(hostNameOrAddress);
+#endif
         }
     }
 }

src/Renci.SshNet/Abstractions/SocketAbstraction.cs

@@ -59,7 +59,6 @@ public static async Task ConnectAsync(Socket socket, IPEndPoint remoteEndpoint,
 
         private static void ConnectCore(Socket socket, IPEndPoint remoteEndpoint, TimeSpan connectTimeout, bool ownsSocket)
         {
-#if FEATURE_SOCKET_EAP
             var connectCompleted = new ManualResetEvent(initialState: false);
             var args = new SocketAsyncEventArgs
                 {
@@ -113,19 +112,6 @@ private static void ConnectCore(Socket socket, IPEndPoint remoteEndpoint, TimeSp
 
             // dispose SocketAsyncEventArgs
             args.Dispose();
-#elif FEATURE_SOCKET_APM
-            var connectResult = socket.BeginConnect(remoteEndpoint, null, null);
-            if (!connectResult.AsyncWaitHandle.WaitOne(connectTimeout, false))
-                throw new SshOperationTimeoutException(string.Format(CultureInfo.InvariantCulture,
-                    "Connection failed to establish within {0:F0} milliseconds.", connectTimeout.TotalMilliseconds));
-            socket.EndConnect(connectResult);
-#elif FEATURE_SOCKET_TAP
-            if (!socket.ConnectAsync(remoteEndpoint).Wait(connectTimeout))
-                throw new SshOperationTimeoutException(string.Format(CultureInfo.InvariantCulture,
-                    "Connection failed to establish within {0:F0} milliseconds.", connectTimeout.TotalMilliseconds));
-#else
-            #error Connecting to a remote endpoint is not implemented.
-#endif
         }
 
         public static void ClearReadBuffer(Socket socket)
@@ -391,12 +377,10 @@ public static bool IsErrorResumable(SocketError socketError)
 #pragma warning restore IDE0010 // Add missing cases
         }
 
-#if FEATURE_SOCKET_EAP
         private static void ConnectCompleted(object sender, SocketAsyncEventArgs e)
         {
             var eventWaitHandle = (ManualResetEvent) e.UserToken;
             _ = eventWaitHandle?.Set();
         }
-#endif // FEATURE_SOCKET_EAP
     }
 }

src/Renci.SshNet/Connection/ConnectorBase.cs

@@ -73,7 +73,7 @@ protected async Task<Socket> SocketConnectAsync(string host, int port, Cancellat
         {
             cancellationToken.ThrowIfCancellationRequested();
 
-            var ipAddress = (await DnsAbstraction.GetHostAddressesAsync(host).ConfigureAwait(false))[0];
+            var ipAddress = (await DnsAbstraction.GetHostAddressesAsync(host, cancellationToken).ConfigureAwait(false))[0];
             var ep = new IPEndPoint(ipAddress, port);
 
             DiagnosticAbstraction.Log(string.Format("Initiating connection to '{0}:{1}'.", host, port));

src/Renci.SshNet/Renci.SshNet.csproj

@@ -6,7 +6,7 @@
   </PropertyGroup>
 
   <PropertyGroup Condition=" '$(TargetFramework)' == 'net462' ">
-    <DefineConstants>$(DefineConstants);FEATURE_BINARY_SERIALIZATION;FEATURE_SOCKET_EAP;FEATURE_SOCKET_APM;FEATURE_DNS_SYNC;FEATURE_HASH_RIPEMD160_CREATE;FEATURE_HMAC_RIPEMD160</DefineConstants>
+    <DefineConstants>$(DefineConstants);FEATURE_BINARY_SERIALIZATION;FEATURE_HASH_RIPEMD160_CREATE;FEATURE_HMAC_RIPEMD160</DefineConstants>
   </PropertyGroup>
 
   <ItemGroup Condition=" '$(TargetFramework)' == 'netstandard2.0' or '$(TargetFramework)' == 'netstandard2.1' or '$(TargetFramework)' == 'net6.0' or '$(TargetFramework)' == 'net7.0' or '$(TargetFramework)' == 'net8.0' ">
@@ -16,8 +16,4 @@
   <ItemGroup Condition=" '$(TargetFramework)' == 'net462' or '$(TargetFramework)' == 'netstandard2.0' ">
     <PackageReference Include="Microsoft.Bcl.AsyncInterfaces" Version="1.0.0" />
   </ItemGroup>
-
-  <PropertyGroup Condition=" '$(TargetFramework)' == 'netstandard2.0' or '$(TargetFramework)' == 'netstandard2.1' or '$(TargetFramework)' == 'net6.0' or '$(TargetFramework)' == 'net7.0' or '$(TargetFramework)' == 'net8.0' ">
-    <DefineConstants>$(DefineConstants);FEATURE_SOCKET_TAP;FEATURE_SOCKET_APM;FEATURE_SOCKET_EAP;FEATURE_DNS_SYNC;FEATURE_DNS_APM;FEATURE_DNS_TAP</DefineConstants>
-  </PropertyGroup>
 </Project>