From dd4799adfdf8e1166c7b2c95036ceaaf928f97df Mon Sep 17 00:00:00 2001
From: John Luo <jt.luo@mail.utoronto.ca>
Date: Wed, 14 Sep 2016 11:53:54 -0700
Subject: [PATCH] Split by commas when normalizing headers

---
 .../ResponseCacheMiddleware.cs                |  9 +++---
 .../ResponseCacheMiddlewareTests.cs           | 29 ++++++++++++++++---
 2 files changed, 30 insertions(+), 8 deletions(-)

diff --git a/src/Microsoft.AspNetCore.ResponseCaching/ResponseCacheMiddleware.cs b/src/Microsoft.AspNetCore.ResponseCaching/ResponseCacheMiddleware.cs
index 5c395ad306..85b8fec0ea 100644
--- a/src/Microsoft.AspNetCore.ResponseCaching/ResponseCacheMiddleware.cs
+++ b/src/Microsoft.AspNetCore.ResponseCaching/ResponseCacheMiddleware.cs
@@ -2,6 +2,7 @@
 // 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.Builder;
@@ -211,7 +212,7 @@ namespace Microsoft.AspNetCore.ResponseCaching
 
                 // Create the cache entry now
                 var response = context.HttpContext.Response;
-                var varyHeaderValue = response.Headers[HeaderNames.Vary];
+                var varyHeaderValue = new StringValues(response.Headers.GetCommaSeparatedValues(HeaderNames.Vary));
                 var varyParamsValue = context.HttpContext.GetResponseCacheFeature()?.VaryByParams ?? StringValues.Empty;
                 context.CachedResponseValidFor = context.ResponseCacheControlHeaderValue.SharedMaxAge ??
                     context.ResponseCacheControlHeaderValue.MaxAge ??
@@ -222,8 +223,8 @@ namespace Microsoft.AspNetCore.ResponseCaching
                 if (!StringValues.IsNullOrEmpty(varyHeaderValue) || !StringValues.IsNullOrEmpty(varyParamsValue))
                 {
                     // Normalize order and casing of vary by rules
-                    var normalizedVaryHeaderValue = GetNormalizedStringValues(varyHeaderValue);
-                    var normalizedVaryParamsValue = GetNormalizedStringValues(varyParamsValue);
+                    var normalizedVaryHeaderValue = GetOrderCasingNormalizedStringValues(varyHeaderValue);
+                    var normalizedVaryParamsValue = GetOrderCasingNormalizedStringValues(varyParamsValue);
 
                     // Update vary rules if they are different
                     if (context.CachedVaryByRules == null ||
@@ -374,7 +375,7 @@ namespace Microsoft.AspNetCore.ResponseCaching
         }
 
         // Normalize order and casing
-        internal static StringValues GetNormalizedStringValues(StringValues stringValues)
+        internal static StringValues GetOrderCasingNormalizedStringValues(StringValues stringValues)
         {
             if (stringValues.Count == 1)
             {
diff --git a/test/Microsoft.AspNetCore.ResponseCaching.Tests/ResponseCacheMiddlewareTests.cs b/test/Microsoft.AspNetCore.ResponseCaching.Tests/ResponseCacheMiddlewareTests.cs
index a329104ed1..8ef4b51bf0 100644
--- a/test/Microsoft.AspNetCore.ResponseCaching.Tests/ResponseCacheMiddlewareTests.cs
+++ b/test/Microsoft.AspNetCore.ResponseCaching.Tests/ResponseCacheMiddlewareTests.cs
@@ -410,6 +410,18 @@ namespace Microsoft.AspNetCore.ResponseCaching.Tests
             Assert.NotNull(context.CachedResponse);
         }
 
+        [Fact]
+        public void FinalizeCachingHeaders_SplitsVaryHeaderByCommas()
+        {
+            var middleware = TestUtils.CreateTestMiddleware();
+            var context = TestUtils.CreateTestContext();
+            context.HttpContext.Response.Headers[HeaderNames.Vary] = "HeaderB, heaDera";
+
+            middleware.FinalizeCacheHeaders(context);
+
+            Assert.Equal(new StringValues(new[] { "HEADERA", "HEADERB" }), context.CachedVaryByRules.Headers);
+        }
+
         [Fact]
         public async Task FinalizeCacheBody_StoreResponseBodySeparately_IfLargerThanLimit()
         {
@@ -554,26 +566,35 @@ namespace Microsoft.AspNetCore.ResponseCaching.Tests
         }
 
         [Fact]
-        public void NormalizeStringValues_NormalizesCasingToUpper()
+        public void GetOrderCasingNormalizedStringValues_NormalizesCasingToUpper()
         {
             var uppercaseStrings = new StringValues(new[] { "STRINGA", "STRINGB" });
             var lowercaseStrings = new StringValues(new[] { "stringA", "stringB" });
 
-            var normalizedStrings = ResponseCacheMiddleware.GetNormalizedStringValues(lowercaseStrings);
+            var normalizedStrings = ResponseCacheMiddleware.GetOrderCasingNormalizedStringValues(lowercaseStrings);
 
             Assert.Equal(uppercaseStrings, normalizedStrings);
         }
 
         [Fact]
-        public void NormalizeStringValues_NormalizesOrder()
+        public void GetOrderCasingNormalizedStringValues_NormalizesOrder()
         {
             var orderedStrings = new StringValues(new[] { "STRINGA", "STRINGB" });
             var reverseOrderStrings = new StringValues(new[] { "STRINGB", "STRINGA" });
 
-            var normalizedStrings = ResponseCacheMiddleware.GetNormalizedStringValues(reverseOrderStrings);
+            var normalizedStrings = ResponseCacheMiddleware.GetOrderCasingNormalizedStringValues(reverseOrderStrings);
 
             Assert.Equal(orderedStrings, normalizedStrings);
         }
 
+        [Fact]
+        public void GetOrderCasingNormalizedStringValues_PreservesCommas()
+        {
+            var originalStrings = new StringValues(new[] { "STRINGA, STRINGB" });
+
+            var normalizedStrings = ResponseCacheMiddleware.GetOrderCasingNormalizedStringValues(originalStrings);
+
+            Assert.Equal(originalStrings, normalizedStrings);
+        }
     }
 }