Support non utf-8 charsets (#741)

Author: sungam3r

src/Transports.AspNetCore/GraphQLHttpMiddleware.cs

@@ -80,7 +80,25 @@ public virtual async Task InvokeAsync(HttpContext context, RequestDelegate next)
                         GraphQLRequest[] deserializationResult;
                         try
                         {
+#if NET5_0_OR_GREATER
+                            if (!TryGetEncoding(mediaTypeHeader.CharSet, out var sourceEncoding))
+                            {
+                                await HandleContentTypeCouldNotBeParsedErrorAsync(context);
+                                return;
+                            }
+                            // Wrap content stream into a transcoding stream that buffers the data transcoded from the sourceEncoding to utf-8.
+                            if (sourceEncoding != null && sourceEncoding != System.Text.Encoding.UTF8)
+                            {
+                                using var tempStream = System.Text.Encoding.CreateTranscodingStream(httpRequest.Body, innerStreamEncoding: sourceEncoding, outerStreamEncoding: System.Text.Encoding.UTF8, leaveOpen: true);
+                                deserializationResult = await _serializer.ReadAsync<GraphQLRequest[]>(tempStream, cancellationToken);
+                            }
+                            else
+                            {
+                                deserializationResult = await _serializer.ReadAsync<GraphQLRequest[]>(httpRequest.Body, cancellationToken);
+                            }
+#else
                             deserializationResult = await _serializer.ReadAsync<GraphQLRequest[]>(httpRequest.Body, cancellationToken);
+#endif
                         }
                         catch (Exception ex)
                         {
@@ -288,5 +306,34 @@ private async Task<GraphQLRequest> DeserializeFromGraphBodyAsync(Stream bodyStre
 
             return new GraphQLRequest { Query = query }; // application/graphql MediaType supports only query text
         }
+
+#if NET5_0_OR_GREATER
+        private static bool TryGetEncoding(string charset, out System.Text.Encoding encoding)
+        {
+            encoding = null;
+
+            if (string.IsNullOrEmpty(charset))
+                return true;
+
+            try
+            {
+                // Remove at most a single set of quotes.
+                if (charset.Length > 2 && charset[0] == '\"' && charset[charset.Length - 1] == '\"')
+                {
+                    encoding = System.Text.Encoding.GetEncoding(charset.Substring(1, charset.Length - 2));
+                }
+                else
+                {
+                    encoding = System.Text.Encoding.GetEncoding(charset);
+                }
+            }
+            catch (ArgumentException)
+            {
+                return false;
+            }
+
+            return true;
+        }
+#endif
     }
 }

tests/Samples.Server.Tests/ResponseTests.cs

@@ -98,6 +98,16 @@ public async Task Wrong_Query_Should_Return_Error(HttpMethod httpMethod, HttpCon
                 "Invalid 'Content-Type' header: non-supported media type 'something/unknown; charset=utf-8'. Must be of 'application/json', 'application/graphql' or 'application/x-www-form-urlencoded'. See: http://graphql.org/learn/serving-over-http/."
             },
 
+            // MediaTypeHeaderValue ctor throws exception
+            // POST with unsupported charset should be a unsupported media type
+            //new object[]
+            //{
+            //    HttpMethod.Post,
+            //    new StringContent(Serializer.ToJson(new GraphQLRequest { Query = "query { __schema { queryType { name } } }" }), Encoding.UTF8, "application/json; charset=utf-3"),
+            //    HttpStatusCode.UnsupportedMediaType,
+            //    "Invalid 'Content-Type' header: non-supported media type 'application/json; charset=utf-3'. Must be of 'application/json', 'application/graphql' or 'application/x-www-form-urlencoded'. See: http://graphql.org/learn/serving-over-http/."
+            //},
+
             // POST with JSON mime type that doesn't start with an object or array token should be a bad request
             new object[]
             {