From 18729a05e59c93eb258eb0a72cf2af4c22b28041 Mon Sep 17 00:00:00 2001
From: Jan Tattermusch <jtattermusch@google.com>
Date: Thu, 8 Oct 2015 18:40:00 -0700
Subject: Polishing of C# auth API

---
 src/csharp/Grpc.Core/CallCredentials.cs | 30 ++++++++++++++++++++----------
 1 file changed, 20 insertions(+), 10 deletions(-)

(limited to 'src/csharp/Grpc.Core/CallCredentials.cs')

diff --git a/src/csharp/Grpc.Core/CallCredentials.cs b/src/csharp/Grpc.Core/CallCredentials.cs
index 809c9f412d..400a9825de 100644
--- a/src/csharp/Grpc.Core/CallCredentials.cs
+++ b/src/csharp/Grpc.Core/CallCredentials.cs
@@ -40,6 +40,14 @@ using Grpc.Core.Utils;
 
 namespace Grpc.Core
 {
+    /// <summary>
+    /// Asynchronous authentication interceptor for <see cref="CallCredentials"/>.
+    /// </summary>
+    /// <param name="authUri">URL of a service to which current remote call needs to authenticate</param>
+    /// <param name="metadata">Metadata to populate with entries that will be added to outgoing call's headers.</param>
+    /// <returns></returns>
+    public delegate Task AsyncAuthInterceptor(string authUri, Metadata metadata);
+
     /// <summary>
     /// Client-side call credentials. Provide authorization with per-call granularity.
     /// </summary>
@@ -56,6 +64,16 @@ namespace Grpc.Core
             return new CompositeCallCredentials(credentials);
         }
 
+        /// <summary>
+        /// Creates a new instance of <c>CallCredentials</c> class from an
+        /// interceptor that can attach metadata to outgoing calls.
+        /// </summary>
+        /// <param name="interceptor">authentication interceptor</param>
+        public static CallCredentials FromInterceptor(AsyncAuthInterceptor interceptor)
+        {
+            return new MetadataCredentials(interceptor);
+        }
+
         /// <summary>
         /// Creates native object for the credentials.
         /// </summary>
@@ -63,19 +81,11 @@ namespace Grpc.Core
         internal abstract CredentialsSafeHandle ToNativeCredentials();
     }
 
-    /// <summary>
-    /// Asynchronous authentication interceptor for <see cref="MetadataCredentials"/>.
-    /// </summary>
-    /// <param name="authUri">URL of a service to which current remote call needs to authenticate</param>
-    /// <param name="metadata">Metadata to populate with entries that will be added to outgoing call's headers.</param>
-    /// <returns></returns>
-    public delegate Task AsyncAuthInterceptor(string authUri, Metadata metadata);
-
     /// <summary>
     /// Client-side credentials that delegate metadata based auth to an interceptor.
     /// The interceptor is automatically invoked for each remote call that uses <c>MetadataCredentials.</c>
     /// </summary>
-    public class MetadataCredentials : CallCredentials
+    internal sealed class MetadataCredentials : CallCredentials
     {
         readonly AsyncAuthInterceptor interceptor;
 
@@ -85,7 +95,7 @@ namespace Grpc.Core
         /// <param name="interceptor">authentication interceptor</param>
         public MetadataCredentials(AsyncAuthInterceptor interceptor)
         {
-            this.interceptor = interceptor;
+            this.interceptor = Preconditions.CheckNotNull(interceptor);
         }
 
         internal override CredentialsSafeHandle ToNativeCredentials()
-- 
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