[WinHTTP] Remove legacy (Win 8.1-) WinInet proxy handling

src/libraries/System.Net.Http.WinHttpHandler/src/System.Net.Http.WinHttpHandler.csproj

@@ -68,8 +68,6 @@ System.Net.Http.WinHttpHandler</PackageDescription>
              Link="Common\System\Net\UriScheme.cs" />
     <Compile Include="$(CommonPath)\System\Net\Http\HttpHandlerDefaults.cs"
              Link="Common\System\Net\Http\HttpHandlerDefaults.cs" />
-    <Compile Include="$(CommonPath)\System\Net\Http\WinInetProxyHelper.cs"
-             Link="Common\System\Net\Http\WinInetProxyHelper.cs" />
     <Compile Include="$(CommonPath)\System\Net\Security\CertificateHelper.cs"
              Link="Common\System\Net\Security\CertificateHelper.cs" />
     <Compile Include="$(CommonPath)\System\Net\Security\CertificateHelper.Windows.cs"

src/libraries/System.Net.Http.WinHttpHandler/src/System/Net/Http/WinHttpHandler.cs

@@ -52,7 +52,6 @@ public class WinHttpHandler : HttpMessageHandler
 
         private readonly object _lockObject = new object();
         private bool _doManualDecompressionCheck;
-        private WinInetProxyHelper? _proxyHelper;
         private bool _automaticRedirection = HttpHandlerDefaults.DefaultAutomaticRedirection;
         private int _maxAutomaticRedirections = HttpHandlerDefaults.DefaultMaxAutomaticRedirections;
         private DecompressionMethods _automaticDecompression = HttpHandlerDefaults.DefaultAutomaticDecompression;
@@ -814,29 +813,7 @@ private void EnsureSessionHandleExists(WinHttpRequestState state)
                             Interop.WinHttp.WINHTTP_NO_PROXY_NAME,
                             Interop.WinHttp.WINHTTP_NO_PROXY_BYPASS,
                             (int)Interop.WinHttp.WINHTTP_FLAG_ASYNC);
-
-                        if (sessionHandle.IsInvalid)
-                        {
-                            int lastError = Marshal.GetLastWin32Error();
-                            if (NetEventSource.Log.IsEnabled()) NetEventSource.Error(this, $"error={lastError}");
-
-                            if (lastError != Interop.WinHttp.ERROR_INVALID_PARAMETER)
-                            {
-                                ThrowOnInvalidHandle(sessionHandle, nameof(Interop.WinHttp.WinHttpOpen));
-                            }
-
-                            // We must be running on a platform earlier than Win8.1/Win2K12R2 which doesn't support
-                            // WINHTTP_ACCESS_TYPE_AUTOMATIC_PROXY.  So, we'll need to read the Wininet style proxy
-                            // settings ourself using our WinInetProxyHelper object.
-                            _proxyHelper = new WinInetProxyHelper();
-                            sessionHandle = Interop.WinHttp.WinHttpOpen(
-                                IntPtr.Zero,
-                                _proxyHelper.ManualSettingsOnly ? Interop.WinHttp.WINHTTP_ACCESS_TYPE_NAMED_PROXY : Interop.WinHttp.WINHTTP_ACCESS_TYPE_NO_PROXY,
-                                _proxyHelper.ManualSettingsOnly ? _proxyHelper.Proxy : Interop.WinHttp.WINHTTP_NO_PROXY_NAME,
-                                _proxyHelper.ManualSettingsOnly ? _proxyHelper.ProxyBypass : Interop.WinHttp.WINHTTP_NO_PROXY_BYPASS,
-                                (int)Interop.WinHttp.WINHTTP_FLAG_ASYNC);
-                            ThrowOnInvalidHandle(sessionHandle, nameof(Interop.WinHttp.WinHttpOpen));
-                        }
+                        ThrowOnInvalidHandle(sessionHandle, nameof(Interop.WinHttp.WinHttpOpen));
 
                         uint optionAssuredNonBlockingTrue = 1; // TRUE
 
@@ -1282,17 +1259,15 @@ private void SetRequestHandleOptions(WinHttpRequestState state)
             SetRequestHandleHttp2Options(state.RequestHandle, state.RequestMessage.Version);
         }
 
-        private void SetRequestHandleProxyOptions(WinHttpRequestState state)
+        private static void SetRequestHandleProxyOptions(WinHttpRequestState state)
         {
             Debug.Assert(state.RequestMessage != null);
             Debug.Assert(state.RequestMessage.RequestUri != null);
             Debug.Assert(state.RequestHandle != null);
 
-            // We've already set the proxy on the session handle if we're using no proxy or default proxy settings.
-            // We only need to change it on the request handle if we have a specific IWebProxy or need to manually
-            // implement Wininet-style auto proxy detection.
-            if (state.WindowsProxyUsePolicy == WindowsProxyUsePolicy.UseCustomProxy ||
-                state.WindowsProxyUsePolicy == WindowsProxyUsePolicy.UseWinInetProxy)
+            // We've already set the proxy on the session handle if we're using no proxy or default/auto proxy settings.
+            // We only need to change it on the request handle if we have a specific custom IWebProxy.
+            if (state.WindowsProxyUsePolicy == WindowsProxyUsePolicy.UseCustomProxy)
             {
                 Interop.WinHttp.WINHTTP_PROXY_INFO proxyInfo = default;
                 bool updateProxySettings = false;
@@ -1302,7 +1277,6 @@ private void SetRequestHandleProxyOptions(WinHttpRequestState state)
                 {
                     if (state.Proxy != null)
                     {
-                        Debug.Assert(state.WindowsProxyUsePolicy == WindowsProxyUsePolicy.UseCustomProxy);
                         updateProxySettings = true;
 
                         Uri? proxyUri = state.Proxy.IsBypassed(uri) ? null : state.Proxy.GetProxy(uri);
@@ -1317,13 +1291,6 @@ private void SetRequestHandleProxyOptions(WinHttpRequestState state)
                             proxyInfo.Proxy = Marshal.StringToHGlobalUni(proxyString);
                         }
                     }
-                    else if (_proxyHelper != null && _proxyHelper.AutoSettingsUsed)
-                    {
-                        if (_proxyHelper.GetProxyForUrl(_sessionHandle, uri, out proxyInfo))
-                        {
-                            updateProxySettings = true;
-                        }
-                    }
 
                     if (updateProxySettings)
                     {

src/libraries/System.Net.Http.WinHttpHandler/tests/UnitTests/FakeInterop.cs

@@ -93,13 +93,6 @@ public static SafeWinHttpHandle WinHttpOpen(
                 return new FakeSafeWinHttpHandle(false);
             }
 
-            if (accessType == Interop.WinHttp.WINHTTP_ACCESS_TYPE_AUTOMATIC_PROXY &&
-                !TestControl.WinHttpAutomaticProxySupport)
-            {
-                TestControl.LastWin32Error = (int)Interop.WinHttp.ERROR_INVALID_PARAMETER;
-                return new FakeSafeWinHttpHandle(false);
-            }
-
             APICallHistory.ProxyInfo proxyInfo;
             proxyInfo.AccessType = accessType;
             proxyInfo.Proxy = proxyName;

src/libraries/System.Net.Http.WinHttpHandler/tests/UnitTests/System.Net.Http.WinHttpHandler.Unit.Tests.csproj

@@ -42,8 +42,6 @@
              Link="Common\System\Net\UriScheme.cs" />
     <Compile Include="$(CommonPath)System\Net\Http\HttpHandlerDefaults.cs"
              Link="Common\System\Net\Http\HttpHandlerDefaults.cs" />
-    <Compile Include="$(CommonPath)\System\Net\Http\WinInetProxyHelper.cs"
-             Link="Common\System\Net\Http\WinInetProxyHelper.cs" />
     <Compile Include="$(CommonPath)System\Net\Security\CertificateHelper.cs"
              Link="Common\System\Net\Security\CertificateHelper.cs" />
     <Compile Include="$(CommonPath)System\Net\Security\CertificateHelper.Windows.cs"
@@ -86,8 +84,6 @@
              Link="ProductionCode\WinHttpTrailersHelper.cs" />
     <Compile Include="..\..\src\System\Net\Http\WinHttpTransportContext.cs"
              Link="ProductionCode\WinHttpTransportContext.cs" />
-    <Compile Include="..\..\..\System.Net.Http\src\System\Net\Http\SocketsHttpHandler\HttpWindowsProxy.cs"
-             Link="ProductionCode\HttpWindowsProxy.cs" />
     <Compile Include="..\..\..\System.Net.Http\src\System\Net\Http\SocketsHttpHandler\FailedProxyCache.cs"
              Link="ProductionCode\FailedProxyCache.cs" />
     <Compile Include="..\..\..\System.Net.Http\src\System\Net\Http\SocketsHttpHandler\IMultiWebProxy.cs"
@@ -104,7 +100,6 @@
     <Compile Include="FakeRegistry.cs" />
     <Compile Include="FakeSafeWinHttpHandle.cs" />
     <Compile Include="FakeX509Certificates.cs" />
-    <Compile Include="HttpWindowsProxyTest.cs" />
     <Compile Include="SafeWinHttpHandleTest.cs" />
     <Compile Include="SendRequestHelper.cs" />
     <Compile Include="TestServer.cs" />

src/libraries/System.Net.Http.WinHttpHandler/tests/UnitTests/TestControl.cs

@@ -17,7 +17,6 @@ public static class TestControl
 
         public static int LastWin32Error { get; set; }
 
-        public static bool WinHttpAutomaticProxySupport { get; set; }
         public static bool WinHttpDecompressionSupport { get; set; }
 
         public static bool PACFileNotDetectedOnNetwork { get; set; }
@@ -32,7 +31,6 @@ public static void Reset()
             WinHttpReceiveResponse = new ApiControl();
             WinHttpWriteData = new ApiControl();
 
-            WinHttpAutomaticProxySupport = true;
             WinHttpDecompressionSupport = true;
 
             LastWin32Error = 0;

src/libraries/System.Net.Http.WinHttpHandler/tests/UnitTests/WinHttpHandlerTest.cs

@@ -784,7 +784,6 @@ await VerifyResponseContent(
         [Fact]
         public void SendAsync_AutomaticProxySupportAndUseWinInetSettings_ExpectedWinHttpSessionProxySettings()
         {
-            TestControl.WinHttpAutomaticProxySupport = true;
             var handler = new WinHttpHandler();
 
             SendRequestHelper.Send(
@@ -797,120 +796,6 @@ public void SendAsync_AutomaticProxySupportAndUseWinInetSettings_ExpectedWinHttp
             Assert.Equal(Interop.WinHttp.WINHTTP_ACCESS_TYPE_AUTOMATIC_PROXY, APICallHistory.SessionProxySettings.AccessType);
         }
 
-        [Fact]
-        public void SendAsync_NoAutomaticProxySupportAndUseWinInetSettingsWithAutoDetectSetting_ExpectedWinHttpProxySettings()
-        {
-            TestControl.WinHttpAutomaticProxySupport = false;
-            FakeRegistry.WinInetProxySettings.AutoDetect = true;
-            var handler = new WinHttpHandler();
-
-            SendRequestHelper.Send(
-                handler,
-                delegate
-                {
-                    handler.WindowsProxyUsePolicy = WindowsProxyUsePolicy.UseWinInetProxy;
-                });
-
-            Assert.Equal(Interop.WinHttp.WINHTTP_ACCESS_TYPE_NO_PROXY, APICallHistory.SessionProxySettings.AccessType);
-            Assert.Equal(Interop.WinHttp.WINHTTP_ACCESS_TYPE_NAMED_PROXY, APICallHistory.RequestProxySettings.AccessType);
-        }
-
-        [Fact]
-        public void SendAsync_NoAutomaticProxySupportAndUseWinInetSettingsWithEmptySettings_ExpectedWinHttpProxySettings()
-        {
-            TestControl.WinHttpAutomaticProxySupport = false;
-            var handler = new WinHttpHandler();
-
-            SendRequestHelper.Send(
-                handler,
-                delegate
-                {
-                    handler.WindowsProxyUsePolicy = WindowsProxyUsePolicy.UseWinInetProxy;
-                });
-
-            Assert.Equal(Interop.WinHttp.WINHTTP_ACCESS_TYPE_NO_PROXY, APICallHistory.SessionProxySettings.AccessType);
-            Assert.False(APICallHistory.RequestProxySettings.AccessType.HasValue);
-        }
-
-        [Fact]
-        public void SendAsync_NoAutomaticProxySupportAndUseWinInetSettingsWithManualSettingsOnly_ExpectedWinHttpProxySettings()
-        {
-            TestControl.WinHttpAutomaticProxySupport = false;
-            FakeRegistry.WinInetProxySettings.Proxy = FakeProxy;
-            var handler = new WinHttpHandler();
-
-            SendRequestHelper.Send(
-                handler,
-                delegate
-                {
-                    handler.WindowsProxyUsePolicy = WindowsProxyUsePolicy.UseWinInetProxy;
-                });
-
-            Assert.Equal(Interop.WinHttp.WINHTTP_ACCESS_TYPE_NAMED_PROXY, APICallHistory.SessionProxySettings.AccessType);
-            Assert.False(APICallHistory.RequestProxySettings.AccessType.HasValue);
-        }
-
-        [Fact]
-        public void SendAsync_NoAutomaticProxySupportAndUseWinInetSettingsWithMissingRegistrySettings_ExpectedWinHttpProxySettings()
-        {
-            TestControl.WinHttpAutomaticProxySupport = false;
-            FakeRegistry.WinInetProxySettings.RegistryKeyMissing = true;
-            var handler = new WinHttpHandler();
-
-            SendRequestHelper.Send(
-                handler,
-                delegate
-                {
-                    handler.WindowsProxyUsePolicy = WindowsProxyUsePolicy.UseWinInetProxy;
-                });
-
-            Assert.Equal(Interop.WinHttp.WINHTTP_ACCESS_TYPE_NO_PROXY, APICallHistory.SessionProxySettings.AccessType);
-            Assert.False(APICallHistory.RequestProxySettings.AccessType.HasValue);
-        }
-
-        [Fact]
-        public void SendAsync_NoAutomaticProxySupportAndUseWinInetSettingsWithAutoDetectButPACFileNotDetectedOnNetwork_ExpectedWinHttpProxySettings()
-        {
-            TestControl.WinHttpAutomaticProxySupport = false;
-            TestControl.PACFileNotDetectedOnNetwork = true;
-            FakeRegistry.WinInetProxySettings.AutoDetect = true;
-            var handler = new WinHttpHandler();
-
-            SendRequestHelper.Send(
-                handler,
-                delegate
-                {
-                    handler.WindowsProxyUsePolicy = WindowsProxyUsePolicy.UseWinInetProxy;
-                });
-
-            Assert.Equal(Interop.WinHttp.WINHTTP_ACCESS_TYPE_NO_PROXY, APICallHistory.SessionProxySettings.AccessType);
-            Assert.Null(APICallHistory.RequestProxySettings.AccessType);
-        }
-
-        [Fact]
-        public void SendAsync_NoAutomaticProxySupportAndUseWinInetSettingsWithAutoDetectSettingAndManualSettingButPACFileNotFoundOnNetwork_ExpectedWinHttpProxySettings()
-        {
-            const string manualProxy = FakeProxy;
-            TestControl.WinHttpAutomaticProxySupport = false;
-            FakeRegistry.WinInetProxySettings.AutoDetect = true;
-            FakeRegistry.WinInetProxySettings.Proxy = manualProxy;
-            TestControl.PACFileNotDetectedOnNetwork = true;
-            var handler = new WinHttpHandler();
-
-            SendRequestHelper.Send(
-                handler,
-                delegate
-                {
-                    handler.WindowsProxyUsePolicy = WindowsProxyUsePolicy.UseWinInetProxy;
-                });
-
-            // Both AutoDetect and manual proxy are specified.  If AutoDetect fails to find
-            // the PAC file on the network, then we should fall back to manual setting.
-            Assert.Equal(Interop.WinHttp.WINHTTP_ACCESS_TYPE_NO_PROXY, APICallHistory.SessionProxySettings.AccessType);
-            Assert.Equal(Interop.WinHttp.WINHTTP_ACCESS_TYPE_NAMED_PROXY, APICallHistory.RequestProxySettings.AccessType);
-            Assert.Equal(manualProxy, APICallHistory.RequestProxySettings.Proxy);
-        }
-
         [Fact]
         public void SendAsync_UseNoProxy_ExpectedWinHttpProxySettings()
         {
@@ -961,7 +846,6 @@ public void SendAsync_UseCustomProxyWithBypass_ExpectedWinHttpProxySettings()
         [Fact]
         public void SendAsync_AutomaticProxySupportAndUseDefaultWebProxy_ExpectedWinHttpSessionProxySettings()
         {
-            TestControl.WinHttpAutomaticProxySupport = true;
             var handler = new WinHttpHandler();
 
             SendRequestHelper.Send(

src/libraries/System.Net.Http/src/System.Net.Http.csproj

@@ -372,6 +372,7 @@
     <Compile Include="System\Net\Http\SocketsHttpHandler\HttpEnvironmentProxy.Windows.cs" />
     <Compile Include="System\Net\Http\SocketsHttpHandler\HttpNoProxy.cs" />
     <Compile Include="System\Net\Http\SocketsHttpHandler\HttpWindowsProxy.cs" />
+    <Compile Include="System\Net\Http\SocketsHttpHandler\WinInetProxyHelper.cs" />
     <Compile Include="System\Net\Http\SocketsHttpHandler\CurrentUserIdentityProvider.Windows.cs" />
     <Compile Include="$(CommonPath)Interop\Windows\Interop.BOOL.cs"
              Link="Common\Interop\Windows\Interop.BOOL.cs" />
@@ -395,8 +396,6 @@
              Link="Common\System\Net\UriScheme.cs" />
     <Compile Include="$(CommonPath)\System\Net\Http\HttpHandlerDefaults.cs"
              Link="Common\System\Net\Http\HttpHandlerDefaults.cs" />
-    <Compile Include="$(CommonPath)\System\Net\Http\WinInetProxyHelper.cs"
-             Link="Common\System\Net\Http\WinInetProxyHelper.cs" />
     <Compile Include="$(CommonPath)\System\Net\Security\CertificateHelper.cs"
              Link="Common\System\Net\Security\CertificateHelper.cs" />
     <Compile Include="$(CommonPath)\System\Net\Security\CertificateHelper.Windows.cs"