Hide functionality behind appctx switch

dotnet · Jun 14, 2024 · 6b967a0 · 6b967a0
1 parent 24f2e9f
commit 6b967a0
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Showing 3 changed files with 38 additions and 2 deletions.
diff --git a/src/libraries/Common/src/System/AppContextSwitchHelper.cs b/src/libraries/Common/src/System/AppContextSwitchHelper.cs
@@ -0,0 +1,30 @@
+// Licensed to the .NET Foundation under one or more agreements.
+// The .NET Foundation licenses this file to you under the MIT license.
+
+using System.Globalization;
+
+namespace System
+{
+    internal static class AppContextSwitchHelper
+    {
+        internal static bool GetBooleanConfig(string switchName, bool defaultValue) =>
+            AppContext.TryGetSwitch(switchName, out bool value) ? value : defaultValue;
+
+        internal static bool GetBooleanConfig(string switchName, string envVariable, bool defaultValue = false)
+        {
+            if (Environment.GetEnvironmentVariable(envVariable) is string str)
+            {
+                if (str == "1" || string.Equals(str, bool.TrueString, StringComparison.OrdinalIgnoreCase))
+                {
+                    return true;
+                }
+                if (str == "1" || string.Equals(str, bool.FalseString, StringComparison.OrdinalIgnoreCase))
+                {
+                    return false;
+                }
+            }
+
+            return GetBooleanConfig(switchName, defaultValue);
+        }
+    }
+}
diff --git a/src/libraries/System.Net.Quic/src/System.Net.Quic.csproj b/src/libraries/System.Net.Quic/src/System.Net.Quic.csproj
@@ -29,6 +29,7 @@
     <Compile Include="System\Net\Quic\**\*.cs" Exclude="System\Net\Quic\*.Unsupported.cs"/>
     <!-- System.Net common -->
     <Compile Include="$(CommonPath)DisableRuntimeMarshalling.cs" Link="Common\DisableRuntimeMarshalling.cs" />
+    <Compile Include="$(CommonPath)System\AppContextSwitchHelper.cs" Link="Common\System\AppContextSwitchHelper.cs" />
     <Compile Include="$(CommonPath)System\Net\SafeHandleCache.cs" Link="Common\System\Net\SafeHandleCache.cs" />
     <Compile Include="$(CommonPath)System\Net\ArrayBuffer.cs" Link="Common\System\Net\ArrayBuffer.cs" />
     <Compile Include="$(CommonPath)System\Net\MultiArrayBuffer.cs" Link="Common\System\Net\MultiArrayBuffer.cs" />

diff --git a/src/libraries/System.Net.Quic/src/System/Net/Quic/Internal/MsQuicApi.cs b/src/libraries/System.Net.Quic/src/System/Net/Quic/Internal/MsQuicApi.cs
@@ -74,7 +74,7 @@ private MsQuicApi(QUIC_API_TABLE* apiTable)
     static MsQuicApi()
     {
         bool loaded = false;
-        IntPtr msQuicHandle;
+        IntPtr msQuicHandle = IntPtr.Zero;
         Version = default;
 
         // MsQuic is using DualMode sockets and that will fail even for IPv4 if AF_INET6 is not available.
@@ -97,7 +97,10 @@ static MsQuicApi()
             // support developers explicitly providing OpenSSL version of MsQuic.
             // in the application directory, so we first check there and default
             // to the Schannel version if not found.
-            loaded = NativeLibrary.TryLoad(Path.Combine(AppContext.BaseDirectory, Interop.Libraries.MsQuic), out msQuicHandle);
+            if (AllowAppLocalMsQuic())
+            {
+                loaded = NativeLibrary.TryLoad(Path.Combine(AppContext.BaseDirectory, Interop.Libraries.MsQuic), out msQuicHandle);
+            }
 
             if (!loaded)
             {
@@ -275,4 +278,6 @@ private static bool IsTls13Disabled(bool isServer)
 #endif
         return false;
     }
+
+    private static bool AllowAppLocalMsQuic() => AppContextSwitchHelper.GetBooleanConfig("System.Net.Quic.AppLocalMsQuic", "DOTNET_SYSTEM_NET_QUIC_APPLOCALMSQUIC");
 }