Abstract the SSPI context generation

This change introduces SSPIContextProvider that can generate payloads for SSPI. Specifically, this change plumbs the current SSPI context generation into this object, while later changes will continue to update the shape to be a more general purpose, public API.

Author: twsouthwick

src/Microsoft.Data.SqlClient/netcore/src/Microsoft.Data.SqlClient.csproj

@@ -516,6 +516,18 @@
     <Compile Include="..\..\src\System\Diagnostics\CodeAnalysis.cs">
       <Link>Common\System\Diagnostics\CodeAnalysis.cs</Link>
     </Compile>
+    <Compile Include="..\..\src\Microsoft\Data\SqlClient\SSPI\ManagedSSPIContextProvider.cs">
+      <Link>Microsoft\Data\SqlClient\SSPI\ManagedSSPIContextProvider.cs</Link>
+    </Compile>
+    <Compile Include="..\..\src\Microsoft\Data\SqlClient\SSPI\NegotiateSSPIContextProvider.cs">
+      <Link>Microsoft\Data\SqlClient\SSPI\NegotiateSSPIContextProvider.cs</Link>
+    </Compile>
+    <Compile Include="..\..\src\Microsoft\Data\SqlClient\SSPI\SSPIContextProvider.cs">
+      <Link>Microsoft\Data\SqlClient\SSPI\SSPIContextProvider.cs</Link>
+    </Compile>
+    <Compile Include="..\..\src\Microsoft\Data\SqlClient\TdsParser.Shared.cs">
+      <Link>Microsoft\Data\SqlClient\TdsParser.Shared.cs</Link>
+    </Compile>  
   </ItemGroup>
   <ItemGroup Condition="'$(TargetGroup)' == 'netstandard' OR '$(TargetGroup)' == 'netcoreapp' OR '$(IsUAPAssembly)' == 'true'">
     <Compile Include="Microsoft.Data.SqlClient.TypeForwards.cs" />
@@ -580,7 +592,7 @@
     <Compile Include="Microsoft\Data\SqlClient\SqlConnectionFactory.AssemblyLoadContext.cs" />
   </ItemGroup>
   <ItemGroup>
-    <Compile Include="..\..\src\Resources\StringsHelper.cs">
+  <Compile Include="..\..\src\Resources\StringsHelper.cs">
       <Link>Resources\StringsHelper.cs</Link>
     </Compile>  
     <Compile Include="..\..\src\Resources\Strings.Designer.cs">
@@ -767,7 +779,8 @@
   <ItemGroup Condition="'$(TargetsWindows)' == 'true' and '$(IsUAPAssembly)' != 'true'">
     <Compile Include="$(CommonPath)\Interop\Windows\kernel32\Interop.LoadLibraryEx.cs">
       <Link>Common\Interop\Windows\kernel32\Interop.LoadLibraryEx.cs</Link>
-    </Compile>
+    </Compile>    
+    <Compile Include="..\..\src\Microsoft\Data\SqlClient\SSPI\NativeSSPIContextProvider.cs" Link="Microsoft\Data\SqlClient\SSPI\NativeSSPIContextProvider.cs" />
     <Compile Include="Interop\SNINativeMethodWrapper.Windows.cs" />
     <Compile Include="Microsoft\Data\ProviderBase\DbConnectionPoolIdentity.Windows.cs" />
     <Compile Include="Microsoft\Data\SqlClient\LocalDBAPI.Windows.cs" />
@@ -1007,6 +1020,9 @@
     <PackageReference Condition="$(TargetGroup) == 'netstandard'" Include="System.Security.Cryptography.Cng" Version="$(SystemSecurityCryptographyCngVersion)" />
     <PackageReference Condition="$(BuildForRelease) == 'true'" Include="Microsoft.SourceLink.GitHub" Version="$(MicrosoftSourceLinkGitHubVersion)" PrivateAssets="All" />
   </ItemGroup>
+  <ItemGroup>
+    <Folder Include="Microsoft\Data\SqlClient\SSPI\" />
+  </ItemGroup>
   <Import Project="$(ToolsDir)targets\GenerateThisAssemblyCs.targets" />
   <Import Project="$(ToolsDir)targets\ResolveContract.targets" Condition="'$(OSGroup)' == 'AnyOS'" />
   <Import Project="$(ToolsDir)targets\NotSupported.targets" Condition="'$(OSGroup)' == 'AnyOS'" />

src/Microsoft.Data.SqlClient/netcore/src/Microsoft/Data/SqlClient/TdsParser.Windows.cs

@@ -10,8 +10,6 @@ namespace Microsoft.Data.SqlClient
 {
     internal sealed partial class TdsParser
     {
-        private static volatile bool s_fSSPILoaded = false; // bool to indicate whether library has been loaded
-
         internal void PostReadAsyncForMars()
         {
             if (TdsParserStateObjectFactory.UseManagedSNI)
@@ -43,37 +41,7 @@ internal void PostReadAsyncForMars()
                 _physicalStateObj.AddError(ProcessSNIError(_physicalStateObj));
                 ThrowExceptionAndWarning(_physicalStateObj);
             }
-        }
-
-        private void LoadSSPILibrary()
-        {
-            if (TdsParserStateObjectFactory.UseManagedSNI)
-                return;
-            // Outer check so we don't acquire lock once it's loaded.
-            if (!s_fSSPILoaded)
-            {
-                lock (s_tdsParserLock)
-                {
-                    // re-check inside lock
-                    if (!s_fSSPILoaded)
-                    {
-                        // use local for ref param to defer setting s_maxSSPILength until we know the call succeeded.
-                        uint maxLength = 0;
-
-                        if (0 != SNINativeMethodWrapper.SNISecInitPackage(ref maxLength))
-                            SSPIError(SQLMessage.SSPIInitializeError(), TdsEnums.INIT_SSPI_PACKAGE);
-
-                        s_maxSSPILength = maxLength;
-                        s_fSSPILoaded = true;
-                    }
-                }
-            }
-
-            if (s_maxSSPILength > int.MaxValue)
-            {
-                throw SQL.InvalidSSPIPacketSize();   // SqlBu 332503
-            }
-        }
+        }         
 
         private void WaitForSSLHandShakeToComplete(ref uint error, ref int protocolVersion)
         {