format correctly chuncked response with Content-Length header (#69016) (#70744)

Co-authored-by: Badre BSAILA <[email protected]>

Author: MihaZupan

src/libraries/System.Net.Http/src/System/Net/Http/SocketsHttpHandler/HttpConnection.cs

@@ -739,6 +739,10 @@ public async Task<HttpResponseMessage> SendAsyncCore(HttpRequestMessage request,
                     _pool.InvalidateHttp11Connection(this);
                     _detachedFromPool = true;
                 }
+                else if (response.Headers.TransferEncodingChunked == true)
+                {
+                    responseStream = new ChunkedEncodingReadStream(this, response);
+                }
                 else if (response.Content.Headers.ContentLength != null)
                 {
                     long contentLength = response.Content.Headers.ContentLength.GetValueOrDefault();
@@ -752,10 +756,6 @@ public async Task<HttpResponseMessage> SendAsyncCore(HttpRequestMessage request,
                         responseStream = new ContentLengthReadStream(this, (ulong)contentLength);
                     }
                 }
-                else if (response.Headers.TransferEncodingChunked == true)
-                {
-                    responseStream = new ChunkedEncodingReadStream(this, response);
-                }
                 else
                 {
                     responseStream = new ConnectionCloseReadStream(this);

src/libraries/System.Net.Http/tests/FunctionalTests/HttpClientHandlerTest.Headers.cs

@@ -561,5 +561,40 @@ await LoopbackServerFactory.CreateClientAndServerAsync(
                     await server.HandleRequestAsync(headers: headerData);
                 });
         }
+
+        [Fact]
+        public async Task SendAsync_ContentLengthAndTransferEncodingHeaders_IgnoreContentLength()
+        {
+            await LoopbackServer.CreateServerAsync(async (server, uri) =>
+            {
+                HttpRequestMessage requestMessage = new HttpRequestMessage(HttpMethod.Get, uri)
+                {
+                    Version = UseVersion
+                };
+                using HttpClient client = new HttpClient();
+                Task<HttpResponseMessage> getResponse = client.SendAsync(requestMessage);
+                await server.AcceptConnectionAsync(async connection =>
+                {
+                    await connection.SendResponseAsync(HttpStatusCode.OK,
+                        new List<HttpHeaderData>
+                        {
+                            new HttpHeaderData("Content-Length", "33"),
+                            new HttpHeaderData("Transfer-Encoding", "chunked")
+                        }, "5\r\nhello\r\n5\r\nworld\r\n3\r\nyay\r\n0\r\n\r\n");
+
+                    using (HttpResponseMessage response = await getResponse)
+                    {
+                        Assert.Equal(HttpStatusCode.OK, response.StatusCode);
+
+                        Assert.True(response.Headers.Contains("Transfer-Encoding"));
+                        Assert.Equal("chunked", Assert.Single(response.Headers.GetValues("Transfer-Encoding")));
+                        Assert.Equal(33, response.Content.Headers.ContentLength);
+
+                        string content = await response.Content.ReadAsStringAsync();
+                        Assert.Equal("helloworldyay", content);
+                    }
+                });
+            });
+        }
     }
 }