Fix issue #1883, MultipartMixed grows cache indefinitely

src/Microsoft.OData.Core/MediaTypeUtils.cs

@@ -56,12 +56,12 @@ internal static class MediaTypeUtils
         /// <summary>
         /// Max size to cache match info.
         /// </summary>
-        private const int MatchInfoCacheMaxSize = 256;
+        private const int MatchInfoCacheInitialSize = 256;
 
         /// <summary>
         /// Concurrent cache to cache match info.
         /// </summary>
-        private static MatchInfoConcurrentCache MatchInfoCache = new MatchInfoConcurrentCache(MatchInfoCacheMaxSize);
+        private static MatchInfoConcurrentCache MatchInfoCache = new MatchInfoConcurrentCache(MatchInfoCacheInitialSize);
 
         /// <summary>UTF-8 encoding, without the BOM preamble.</summary>
         /// <remarks>
@@ -413,6 +413,15 @@ internal static ODataFormat GetFormatFromContentType(string contentTypeName, ODa
             throw new ODataContentTypeException(Strings.MediaTypeUtils_CannotDetermineFormatFromContentType(str, contentTypeName));
         }
 
+        /// <summary>
+        /// Internal method for testing membership of the cache
+        /// </summary>
+        /// <returns>The ContentTypes in the cache in the MediaInfoCache</returns>
+        internal static IEnumerable<string> GetCacheKeys()
+        {
+            return MatchInfoCache.GetKeys();
+        }
+
         /// <summary>
         /// Parses the specified content type header into a media type instance.
         /// </summary>
@@ -908,7 +917,7 @@ public MatchInfoCacheKey(ODataMediaTypeResolver resolver, ODataPayloadKind paylo
             {
                 this.MediaTypeResolver = resolver;
                 this.PayloadKind = payloadKind;
-                this.ContentTypeName = contentTypeName;
+                this.ContentTypeName = RemoveBoundary(contentTypeName);
             }
 
             /// <summary>
@@ -924,7 +933,7 @@ public MatchInfoCacheKey(ODataMediaTypeResolver resolver, ODataPayloadKind paylo
             /// <summary>
             /// Name of content type.
             /// </summary>
-            private string ContentTypeName { get; set; }
+            internal string ContentTypeName { get; set; }
 
             /// <summary>
             /// Returns a value indicating whether this instance is equal to a specified object.
@@ -967,6 +976,27 @@ public override int GetHashCode()
                 int result = this.MediaTypeResolver.GetHashCode() ^ this.PayloadKind.GetHashCode();
                 return this.ContentTypeName != null ? result ^ this.ContentTypeName.GetHashCode() : result;
             }
+
+            /// <summary>
+            /// Multipart/mixed content types have a boundary that varies by request.
+            /// It should not be used as part of the format key.
+            /// </summary>
+            /// <param name="contentTypeName"></param>
+            /// <returns></returns>
+            private static string RemoveBoundary(string contentTypeName)
+            {
+                if (contentTypeName.StartsWith("multipart", StringComparison.OrdinalIgnoreCase))
+                {
+                    // our formatters don't care about parameters for multipart, so just strip them all out for simplicity
+                    int parameter = contentTypeName.IndexOf(';');
+                    if (parameter > 0)
+                    {
+                        return contentTypeName.Substring(0, parameter);
+                    }
+                }
+
+                return contentTypeName;
+            }
         }
 
         /// <summary>
@@ -982,10 +1012,10 @@ private sealed class MatchInfoConcurrentCache
             /// <summary>
             /// Constructor.
             /// </summary>
-            /// <param name="maxSize">Max size of the elements that the cache can contain.</param>
-            public MatchInfoConcurrentCache(int maxSize)
+            /// <param name="initialSize">Initial size of the cache.</param>
+            public MatchInfoConcurrentCache(int initialSize)
             {
-                this.dict = new ConcurrentDictionary<MatchInfoCacheKey, MediaTypeMatchInfo>(4, maxSize);
+                this.dict = new ConcurrentDictionary<MatchInfoCacheKey, MediaTypeMatchInfo>(4, initialSize);
             }
 
             /// <summary>
@@ -1018,6 +1048,15 @@ public void Add(MatchInfoCacheKey key, MediaTypeMatchInfo value)
                     this.dict.TryAdd(key, value);
                 }
             }
+
+            /// <summary>
+            /// Internal method for validating expected elements in the cache
+            /// </summary>
+            /// <returns>ContentType of items in the cache</returns>
+            internal IEnumerable<string> GetKeys()
+            {
+                return this.dict.Keys.Select(k => k.ContentTypeName);
+            }
         }
     }
 }

test/FunctionalTests/Microsoft.OData.Core.Tests/MediaTypeUtilsTests.cs

@@ -434,6 +434,20 @@ public void AlterContentTypeForJsonPaddingIfNeededShouldFailIfAppJsonIsNotAtStar
             Action target = () => MediaTypeUtils.AlterContentTypeForJsonPadding(original);
             target.Throws<ODataException>(Strings.ODataMessageWriter_JsonPaddingOnInvalidContentType("tricky/application/json"));
         }
+
+        [Fact]
+        public void MultipartBoundariesShouldNotGrowCache()
+        {
+            for (int i = 1; i < 100; i++)
+            {
+                ODataMediaType mediaType;
+                Encoding encoding;
+                ODataPayloadKind payloadKind;
+                MediaTypeUtils.GetFormatFromContentType(string.Format("multipart/mixed;boundary={0}", Guid.NewGuid()), new ODataPayloadKind[] { ODataPayloadKind.Batch }, ODataMediaTypeResolver.GetMediaTypeResolver(null), out mediaType, out encoding, out payloadKind);
+            }
+
+            Assert.True(MediaTypeUtils.GetCacheKeys().Count(k => k.StartsWith("multipart/mixed")) == 1, "Multiple multipart/mixed keys in cache");
+        }
     }
 
     internal class TestMediaTypeWithFormat