Only set Content-Length when serving body (#6886)

Addresses #6875

Author: jbagga

src/Microsoft.AspNetCore.Mvc.Core/Infrastructure/FileResultExecutorBase.cs

@@ -89,7 +89,10 @@ protected virtual (RangeItemHeaderValue range, long rangeLength, bool serveBody)
                 // Assuming the request is not a range request, the Content-Length header is set to the length of the entire file. 
                 // If the request is a valid range request, this header is overwritten with the length of the range as part of the 
                 // range processing (see method SetContentLength).
-                response.ContentLength = fileLength.Value;
+                if (serveBody)
+                {
+                    response.ContentLength = fileLength.Value;
+                }
                 if (HttpMethods.IsHead(request.Method) || HttpMethods.IsGet(request.Method))
                 {
                     if ((preconditionState == PreconditionState.Unspecified ||

test/Microsoft.AspNetCore.Mvc.Core.Test/FileContentResultTest.cs

@@ -348,7 +348,7 @@ public async Task WriteFileAsync_RangeRequested_PreconditionFailed()
             var body = streamReader.ReadToEndAsync().Result;
             Assert.Equal(StatusCodes.Status412PreconditionFailed, httpResponse.StatusCode);
             Assert.Equal("bytes", httpResponse.Headers[HeaderNames.AcceptRanges]);
-            Assert.Equal(11, httpResponse.ContentLength);
+            Assert.Null(httpResponse.ContentLength);
             Assert.Empty(httpResponse.Headers[HeaderNames.ContentRange]);
             Assert.NotEmpty(httpResponse.Headers[HeaderNames.LastModified]);
             Assert.Empty(body);
@@ -390,7 +390,7 @@ public async Task WriteFileAsync_RangeRequested_NotModified()
             var body = streamReader.ReadToEndAsync().Result;
             Assert.Equal(StatusCodes.Status304NotModified, httpResponse.StatusCode);
             Assert.Equal("bytes", httpResponse.Headers[HeaderNames.AcceptRanges]);
-            Assert.Equal(11, httpResponse.ContentLength);
+            Assert.Null(httpResponse.ContentLength);
             Assert.Empty(httpResponse.Headers[HeaderNames.ContentRange]);
             Assert.NotEmpty(httpResponse.Headers[HeaderNames.LastModified]);
             Assert.Empty(body);

test/Microsoft.AspNetCore.Mvc.Core.Test/FileStreamResultTest.cs

@@ -338,7 +338,7 @@ public async Task WriteFileAsync_RangeRequested_PreconditionFailed()
             var body = streamReader.ReadToEndAsync().Result;
             Assert.Equal(StatusCodes.Status412PreconditionFailed, httpResponse.StatusCode);
             Assert.Equal("bytes", httpResponse.Headers[HeaderNames.AcceptRanges]);
-            Assert.Equal(11, httpResponse.ContentLength);
+            Assert.Null(httpResponse.ContentLength);
             Assert.Empty(httpResponse.Headers[HeaderNames.ContentRange]);
             Assert.NotEmpty(httpResponse.Headers[HeaderNames.LastModified]);
             Assert.Empty(body);
@@ -381,7 +381,7 @@ public async Task WriteFileAsync_RangeRequested_NotModified()
             var body = streamReader.ReadToEndAsync().Result;
             Assert.Equal(StatusCodes.Status304NotModified, httpResponse.StatusCode);
             Assert.Equal("bytes", httpResponse.Headers[HeaderNames.AcceptRanges]);
-            Assert.Equal(11, httpResponse.ContentLength);
+            Assert.Null(httpResponse.ContentLength);
             Assert.Empty(httpResponse.Headers[HeaderNames.ContentRange]);
             Assert.NotEmpty(httpResponse.Headers[HeaderNames.LastModified]);
             Assert.Empty(body);

test/Microsoft.AspNetCore.Mvc.Core.Test/PhysicalFileResultTest.cs

@@ -242,7 +242,7 @@ public async Task WriteFileAsync_RangeRequested_PreconditionFailed()
             var body = streamReader.ReadToEndAsync().Result;
             Assert.Equal(StatusCodes.Status412PreconditionFailed, httpResponse.StatusCode);
             Assert.Equal("bytes", httpResponse.Headers[HeaderNames.AcceptRanges]);
-            Assert.Equal(34, httpResponse.ContentLength);
+            Assert.Null(httpResponse.ContentLength);
             Assert.Empty(httpResponse.Headers[HeaderNames.ContentRange]);
             Assert.NotEmpty(httpResponse.Headers[HeaderNames.LastModified]);
             Assert.Empty(body);
@@ -272,7 +272,7 @@ public async Task WriteFileAsync_RangeRequested_NotModified()
             var body = streamReader.ReadToEndAsync().Result;
             Assert.Equal(StatusCodes.Status304NotModified, httpResponse.StatusCode);
             Assert.Equal("bytes", httpResponse.Headers[HeaderNames.AcceptRanges]);
-            Assert.Equal(34, httpResponse.ContentLength);
+            Assert.Null(httpResponse.ContentLength);
             Assert.Empty(httpResponse.Headers[HeaderNames.ContentRange]);
             Assert.NotEmpty(httpResponse.Headers[HeaderNames.LastModified]);
             Assert.Empty(body);

test/Microsoft.AspNetCore.Mvc.Core.Test/VirtualFileResultTest.cs

@@ -314,7 +314,7 @@ public async Task WriteFileAsync_RangeRequested_PreconditionFailed()
             var body = streamReader.ReadToEndAsync().Result;
             Assert.Equal(StatusCodes.Status412PreconditionFailed, httpResponse.StatusCode);
             Assert.Equal("bytes", httpResponse.Headers[HeaderNames.AcceptRanges]);
-            Assert.Equal(33, httpResponse.ContentLength);
+            Assert.Null(httpResponse.ContentLength);
             Assert.Empty(httpResponse.Headers[HeaderNames.ContentRange]);
             Assert.NotEmpty(httpResponse.Headers[HeaderNames.LastModified]);
             Assert.Empty(body);
@@ -356,7 +356,7 @@ public async Task WriteFileAsync_RangeRequested_NotModified()
             var body = streamReader.ReadToEndAsync().Result;
             Assert.Equal(StatusCodes.Status304NotModified, httpResponse.StatusCode);
             Assert.Equal("bytes", httpResponse.Headers[HeaderNames.AcceptRanges]);
-            Assert.Equal(33, httpResponse.ContentLength);
+            Assert.Null(httpResponse.ContentLength);
             Assert.Empty(httpResponse.Headers[HeaderNames.ContentRange]);
             Assert.NotEmpty(httpResponse.Headers[HeaderNames.LastModified]);
             Assert.Empty(body);