revert

Author: twsouthwick

src/Microsoft.Data.SqlClient/src/Microsoft/Data/SqlClient/SSPI/NegotiateSSPIContextProvider.cs

@@ -11,27 +11,34 @@ namespace Microsoft.Data.SqlClient
 {
     internal sealed class NegotiateSSPIContextProvider : SSPIContextProvider
     {
+        private NegotiateAuthentication? _negotiateAuth = null;
+
         protected override void GenerateSspiClientContext(ReadOnlySpan<byte> incomingBlob, IBufferWriter<byte> outgoingBlobWriter, byte[][] _sniSpnBuffer)
         {
-            NegotiateAuthenticationStatusCode statusCode = default;
+            NegotiateAuthenticationStatusCode statusCode = NegotiateAuthenticationStatusCode.UnknownCredentials;
 
             for (int i = 0; i < _sniSpnBuffer.Length; i++)
             {
-                var negotiateAuth = new NegotiateAuthentication(new NegotiateAuthenticationClientOptions { Package = "Negotiate", TargetName = Encoding.Unicode.GetString(_sniSpnBuffer[i]) });
-                var result = negotiateAuth.GetOutgoingBlob(incomingBlob, out statusCode);
-
+                _negotiateAuth ??= new(new NegotiateAuthenticationClientOptions { Package = "Negotiate", TargetName = Encoding.Unicode.GetString(_sniSpnBuffer[i]) });
+                var sendBuff = _negotiateAuth.GetOutgoingBlob(incomingBlob, out statusCode)!;
                 // Log session id, status code and the actual SPN used in the negotiation
                 SqlClientEventSource.Log.TryTraceEvent("{0}.{1} | Info | Session Id {2}, StatusCode={3}, SPN={4}", nameof(NegotiateSSPIContextProvider),
-                    nameof(GenerateSspiClientContext), _physicalStateObj.SessionId, statusCode, negotiateAuth.TargetName);
-
+                    nameof(GenerateSspiClientContext), _physicalStateObj.SessionId, statusCode, _negotiateAuth.TargetName);
                 if (statusCode == NegotiateAuthenticationStatusCode.Completed || statusCode == NegotiateAuthenticationStatusCode.ContinueNeeded)
                 {
-                    outgoingBlobWriter.Write(result);
-                    return;
+                    outgoingBlobWriter.Write(sendBuff);
+                    break; // Successful case, exit the loop with current SPN.
+                }
+                else
+                {
+                    _negotiateAuth = null; // Reset _negotiateAuth to be generated again for next SPN.
                 }
             }
 
-            throw new InvalidOperationException(SQLMessage.SSPIGenerateError() + Environment.NewLine + statusCode);
+            if (statusCode is not NegotiateAuthenticationStatusCode.Completed and not NegotiateAuthenticationStatusCode.ContinueNeeded)
+            {
+                throw new InvalidOperationException(SQLMessage.SSPIGenerateError() + Environment.NewLine + statusCode);
+            }
         }
     }
 }