diff --git a/src/Grpc.Net.Client/Internal/NtDll.cs b/src/Grpc.Net.Client/Internal/NtDll.cs
new file mode 100644
index 000000000..2abdbf5ad
--- /dev/null
+++ b/src/Grpc.Net.Client/Internal/NtDll.cs
@@ -0,0 +1,72 @@
+#region Copyright notice and license
+
+// Copyright 2019 The gRPC Authors
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+// http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+#endregion
+
+#if !NET5_0_OR_GREATER
+
+using System.Runtime.InteropServices;
+
+namespace Grpc.Net.Client.Internal;
+
+///
+/// Types for calling RtlGetVersion. See https://www.pinvoke.net/default.aspx/ntdll/RtlGetVersion.html
+///
+internal static class NtDll
+{
+ [DllImport("ntdll.dll", SetLastError = true, CharSet = CharSet.Unicode)]
+ internal static extern NTSTATUS RtlGetVersion(ref OSVERSIONINFOEX versionInfo);
+
+ internal static Version DetectWindowsVersion()
+ {
+ var osVersionInfo = new OSVERSIONINFOEX { OSVersionInfoSize = Marshal.SizeOf(typeof(OSVERSIONINFOEX)) };
+
+ if (RtlGetVersion(ref osVersionInfo) != NTSTATUS.STATUS_SUCCESS)
+ {
+ throw new InvalidOperationException($"Failed to call internal {nameof(RtlGetVersion)}.");
+ }
+
+ return new Version(osVersionInfo.MajorVersion, osVersionInfo.MinorVersion, osVersionInfo.BuildNumber, 0);
+ }
+
+ internal enum NTSTATUS : uint
+ {
+ ///
+ /// The operation completed successfully.
+ ///
+ STATUS_SUCCESS = 0x00000000
+ }
+
+ [StructLayout(LayoutKind.Sequential, CharSet = CharSet.Unicode)]
+ internal struct OSVERSIONINFOEX
+ {
+ // The OSVersionInfoSize field must be set to Marshal.SizeOf(typeof(OSVERSIONINFOEX))
+ public int OSVersionInfoSize;
+ public int MajorVersion;
+ public int MinorVersion;
+ public int BuildNumber;
+ public int PlatformId;
+ [MarshalAs(UnmanagedType.ByValTStr, SizeConst = 128)]
+ public string CSDVersion;
+ public ushort ServicePackMajor;
+ public ushort ServicePackMinor;
+ public short SuiteMask;
+ public byte ProductType;
+ public byte Reserved;
+ }
+}
+
+#endif
diff --git a/src/Grpc.Net.Client/Internal/OperatingSystem.cs b/src/Grpc.Net.Client/Internal/OperatingSystem.cs
index fcc7a0753..4d2e45c73 100644
--- a/src/Grpc.Net.Client/Internal/OperatingSystem.cs
+++ b/src/Grpc.Net.Client/Internal/OperatingSystem.cs
@@ -39,13 +39,23 @@ internal sealed class OperatingSystem : IOperatingSystem
private OperatingSystem()
{
- IsBrowser = RuntimeInformation.IsOSPlatform(OSPlatform.Create("browser"));
#if NET5_0_OR_GREATER
IsAndroid = System.OperatingSystem.IsAndroid();
+ IsWindows = System.OperatingSystem.IsWindows();
+ IsBrowser = System.OperatingSystem.IsBrowser();
+ OSVersion = Environment.OSVersion.Version;
#else
IsAndroid = false;
-#endif
IsWindows = RuntimeInformation.IsOSPlatform(OSPlatform.Windows);
- OSVersion = Environment.OSVersion.Version;
+ IsBrowser = RuntimeInformation.IsOSPlatform(OSPlatform.Create("browser"));
+
+ // Older versions of .NET report an OSVersion.Version based on Windows compatibility settings.
+ // For example, if an app running on Windows 11 is configured to be "compatible" with Windows 10
+ // then the version returned is always Windows 10.
+ //
+ // Get correct Windows version directly from Windows by calling RtlGetVersion.
+ // https://www.pinvoke.net/default.aspx/ntdll/RtlGetVersion.html
+ OSVersion = IsWindows ? NtDll.DetectWindowsVersion() : Environment.OSVersion.Version;
+#endif
}
}
diff --git a/test/Grpc.Net.Client.Tests/OperatingSystemTests.cs b/test/Grpc.Net.Client.Tests/OperatingSystemTests.cs
new file mode 100644
index 000000000..c91c3b6e1
--- /dev/null
+++ b/test/Grpc.Net.Client.Tests/OperatingSystemTests.cs
@@ -0,0 +1,43 @@
+#region Copyright notice and license
+
+// Copyright 2019 The gRPC Authors
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+// http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+#endregion
+
+using Grpc.Net.Client.Internal;
+using NUnit.Framework;
+using OperatingSystem = Grpc.Net.Client.Internal.OperatingSystem;
+
+namespace Grpc.Net.Client.Tests;
+
+public class OperatingSystemTests
+{
+#if !NET5_0_OR_GREATER
+ [Test]
+ [Platform("Win", Reason = "Only runs on Windows where ntdll.dll is present.")]
+ public void DetectWindowsVersion_Windows_MatchesEnvironment()
+ {
+ // It is safe to compare Environment.OSVersion.Version on netfx because tests have no compatibilty setting.
+ Assert.AreEqual(Environment.OSVersion.Version, NtDll.DetectWindowsVersion());
+ }
+#endif
+
+ [Test]
+ public void OSVersion_ModernDotNet_MatchesEnvironment()
+ {
+ // It is safe to compare Environment.OSVersion.Version on netfx because tests have no compatibilty setting.
+ Assert.AreEqual(Environment.OSVersion.Version, OperatingSystem.Instance.OSVersion);
+ }
+}