make opaque parameter optional

Author: wfurt

src/System.Net.Http/src/System/Net/Http/Managed/AuthenticationHelper.Digest.cs

@@ -95,11 +95,7 @@ public static async Task<string> GetDigestTokenForCredential(NetworkCredential c
                 return null;
             }
 
-            string opaque;
-            if (!digestResponse.Parameters.TryGetValue(Opaque, out opaque))
-            {
-                return null;
-            }
+            string opaque = digestResponse.Parameters.ContainsKey(Opaque) ? digestResponse.Parameters[Opaque] : null;
 
             string realm = digestResponse.Parameters.ContainsKey(Realm) ? digestResponse.Parameters[Realm] : string.Empty;
 
@@ -189,7 +185,10 @@ public static async Task<string> GetDigestTokenForCredential(NetworkCredential c
             sb.AppendKeyValue(Algorithm, algorithm, includeQuotes: false);
 
             // Add opaque
-            sb.AppendKeyValue(Opaque, opaque);
+            if (opaque != null)
+            {
+                sb.AppendKeyValue(Opaque, opaque);
+            }
 
             // Add qop
             sb.AppendKeyValue(Qop, qop, includeQuotes: false);

src/System.Net.Http/tests/UnitTests/DigestAuthenticationTests.cs

@@ -40,5 +40,16 @@ public static IEnumerable<object[]> DigestResponse_Challenge_TestData()
             yield return new object[] { "=value1,key2=,", s_emptyStringList, s_emptyStringList };
             yield return new object[] { "key1\tm= value1", s_emptyStringList, s_emptyStringList };
         }
+
+        [Theory]
+        [InlineData("realm=\"NetCore\", nonce=\"qMRqWgAAAAAQMjIABgAAAFwEiEwAAAAA\", qop=\"auth\", stale=false")]
+        public async void DigestResponse_AuthToken_Succeeds(string response)
+        {
+            NetworkCredential credential = new NetworkCredential("foo","bar");
+            AuthenticationHelper.DigestResponse digestResponse = new AuthenticationHelper.DigestResponse(response);
+            HttpRequestMessage request = new HttpRequestMessage(HttpMethod.Get, "http://microsoft.com/");
+
+            Assert.True(await AuthenticationHelper.TrySetDigestAuthToken(request, credential, digestResponse, HttpKnownHeaderNames.ProxyAuthorization).ConfigureAwait(false));
+        }
     }
 }