Fix etag parsing

Author: JunTaoLuo

src/Microsoft.AspNetCore.ResponseCaching/ResponseCachingMiddleware.cs

@@ -2,11 +2,11 @@
 // Licensed under the Apache License, Version 2.0. See License.txt in the project root for license information.
 
 using System;
+using System.Collections.Generic;
 using System.Globalization;
 using System.Threading.Tasks;
 using Microsoft.AspNetCore.Http;
 using Microsoft.AspNetCore.Http.Features;
-using Microsoft.AspNetCore.Http.Headers;
 using Microsoft.AspNetCore.ResponseCaching.Internal;
 using Microsoft.Extensions.Internal;
 using Microsoft.Extensions.Logging;
@@ -366,14 +366,14 @@ internal static bool ContentIsNotModified(ResponseCachingContext context)
                 }
 
                 EntityTagHeaderValue eTag;
+                IList<EntityTagHeaderValue> ifNoneMatchEtags;
                 if (!StringValues.IsNullOrEmpty(cachedResponseHeaders[HeaderNames.ETag])
-                    && EntityTagHeaderValue.TryParse(cachedResponseHeaders[HeaderNames.ETag], out eTag))
+                    && EntityTagHeaderValue.TryParse(cachedResponseHeaders[HeaderNames.ETag], out eTag)
+                    && EntityTagHeaderValue.TryParseList(ifNoneMatchHeader, out ifNoneMatchEtags))
                 {
-                    foreach (var tag in ifNoneMatchHeader)
+                    foreach (var requestETag in ifNoneMatchEtags)
                     {
-                        EntityTagHeaderValue requestETag;
-                        if (EntityTagHeaderValue.TryParse(tag, out requestETag) &&
-                            eTag.Compare(requestETag, useStrongComparison: false))
+                        if (eTag.Compare(requestETag, useStrongComparison: false))
                         {
                             context.Logger.LogNotModifiedIfNoneMatchMatched(requestETag);
                             return true;

test/Microsoft.AspNetCore.ResponseCaching.Tests/ResponseCachingMiddlewareTests.cs

@@ -5,7 +5,6 @@
 using System.Collections.Generic;
 using System.Threading.Tasks;
 using Microsoft.AspNetCore.Http;
-using Microsoft.AspNetCore.Http.Headers;
 using Microsoft.AspNetCore.ResponseCaching.Internal;
 using Microsoft.Extensions.Logging.Testing;
 using Microsoft.Extensions.Primitives;
@@ -306,14 +305,30 @@ public void ContentIsNotModified_IfNoneMatch_ExplicitWithoutMatch_False()
             var sink = new TestSink();
             var context = TestUtils.CreateTestContext(sink);
             context.CachedResponseHeaders = new HeaderDictionary();
-            context.HttpContext.Response.Headers[HeaderNames.ETag] = new EntityTagHeaderValue("\"E2\"").ToString();
+            context.CachedResponseHeaders[HeaderNames.ETag] = new EntityTagHeaderValue("\"E2\"").ToString();
 
             context.HttpContext.Request.Headers[HeaderNames.IfNoneMatch] = new List<EntityTagHeaderValue>(new[] { new EntityTagHeaderValue("\"E1\"") }).ToString();
 
             Assert.False(ResponseCachingMiddleware.ContentIsNotModified(context));
             Assert.Empty(sink.Writes);
         }
 
+        [Fact]
+        public void ContentIsNotModified_IfNoneMatch_MatchesAtLeastOneValue_True()
+        {
+            var sink = new TestSink();
+            var context = TestUtils.CreateTestContext(sink);
+            context.CachedResponseHeaders = new HeaderDictionary();
+            context.CachedResponseHeaders[HeaderNames.ETag] = new EntityTagHeaderValue("\"E2\"").ToString();
+
+            context.HttpContext.Request.Headers[HeaderNames.IfNoneMatch] = new string[] { "\"E0\", \"E1\"", "\"E1\", \"E2\"" };
+
+            Assert.True(ResponseCachingMiddleware.ContentIsNotModified(context));
+            TestUtils.AssertLoggedMessages(
+                sink.Writes,
+                LoggedMessage.NotModifiedIfNoneMatchMatched);
+        }
+
         [Fact]
         public async Task FinalizeCacheHeaders_DoNotUpdateShouldCacheResponse_IfResponseIsNotCacheable()
         {