Merge in 'release/7.0-rc1' changes

Author: dotnet-bot

src/Servers/Kestrel/Core/src/Internal/Http/HttpProtocol.cs

@@ -1153,7 +1153,17 @@ private HttpResponseHeaders CreateResponseHeaders(bool appCompleted)
         {
             if (!CanIncludeResponseContentLengthHeader())
             {
-                RejectInvalidHeaderForNonBodyResponse(appCompleted, HeaderNames.ContentLength);
+                if (responseHeaders.ContentLength.Value == 0)
+                {
+                    // If the response shouldn't include a Content-Length but it's 0
+                    // we'll just get rid of it without throwing an error, since it
+                    // is semantically equivalent to not having a Content-Length.
+                    responseHeaders.ContentLength = null;
+                }
+                else
+                {
+                    RejectInvalidHeaderForNonBodyResponse(appCompleted, HeaderNames.ContentLength);
+                }
             }
             else if (StatusCode == StatusCodes.Status205ResetContent && responseHeaders.ContentLength.Value != 0)
             {

src/Servers/Kestrel/test/InMemory.FunctionalTests/ResponseTests.cs

@@ -625,8 +625,27 @@ public static IEnumerable<object[]> Get1xxAnd204MethodCombinations()
 
     [Theory]
     [MemberData(nameof(Get1xxAnd204MethodCombinations))]
-    public async Task AttemptingToWriteContentLengthFailsFor1xxAnd204Responses(int statusCode, HttpMethod method)
-        => await AttemptingToWriteContentLengthFails(statusCode, method).ConfigureAwait(true);
+    public async Task AttemptingToWriteNonzeroContentLengthFailsFor1xxAnd204Responses(int statusCode, HttpMethod method)
+        => await AttemptingToWriteNonzeroContentLengthFails(statusCode, method).ConfigureAwait(true);
+
+    [Theory]
+    [MemberData(nameof(Get1xxAnd204MethodCombinations))]
+    public async Task AttemptingToWriteZeroContentLengthFor1xxAnd204Responses_ContentLengthRemoved(int statusCode, HttpMethod method)
+        => await AttemptingToWriteZeroContentLength_ContentLengthRemoved(statusCode, method).ConfigureAwait(true);
+
+    [Theory]
+    [InlineData(StatusCodes.Status200OK)]
+    [InlineData(StatusCodes.Status201Created)]
+    [InlineData(StatusCodes.Status202Accepted)]
+    [InlineData(StatusCodes.Status203NonAuthoritative)]
+    [InlineData(StatusCodes.Status204NoContent)]
+    [InlineData(StatusCodes.Status205ResetContent)]
+    [InlineData(StatusCodes.Status206PartialContent)]
+    [InlineData(StatusCodes.Status207MultiStatus)]
+    [InlineData(StatusCodes.Status208AlreadyReported)]
+    [InlineData(StatusCodes.Status226IMUsed)]
+    public async Task AttemptingToWriteNonzeroContentLengthFailsFor2xxResponsesOnConnect(int statusCode)
+        => await AttemptingToWriteNonzeroContentLengthFails(statusCode, HttpMethod.Connect).ConfigureAwait(true);
 
     [Theory]
     [InlineData(StatusCodes.Status200OK)]
@@ -639,17 +658,17 @@ public async Task AttemptingToWriteContentLengthFailsFor1xxAnd204Responses(int s
     [InlineData(StatusCodes.Status207MultiStatus)]
     [InlineData(StatusCodes.Status208AlreadyReported)]
     [InlineData(StatusCodes.Status226IMUsed)]
-    public async Task AttemptingToWriteContentLengthFailsFor2xxResponsesOnConnect(int statusCode)
-        => await AttemptingToWriteContentLengthFails(statusCode, HttpMethod.Connect).ConfigureAwait(true);
+    public async Task AttemptingToWriteZeroContentLengthFor2xxResponsesOnConnect_ContentLengthRemoved(int statusCode)
+        => await AttemptingToWriteZeroContentLength_ContentLengthRemoved(statusCode, HttpMethod.Connect).ConfigureAwait(true);
 
-    private async Task AttemptingToWriteContentLengthFails(int statusCode, HttpMethod method)
+    private async Task AttemptingToWriteNonzeroContentLengthFails(int statusCode, HttpMethod method)
     {
         var responseWriteTcs = new TaskCompletionSource(TaskCreationOptions.RunContinuationsAsynchronously);
 
         await using (var server = new TestServer(async httpContext =>
         {
             httpContext.Response.StatusCode = statusCode;
-            httpContext.Response.Headers.ContentLength = 0;
+            httpContext.Response.Headers.ContentLength = 1;
 
             try
             {
@@ -678,6 +697,45 @@ await connection.Send(
         }
     }
 
+    private async Task AttemptingToWriteZeroContentLength_ContentLengthRemoved(int statusCode, HttpMethod method)
+    {
+        var responseWriteTcs = new TaskCompletionSource(TaskCreationOptions.RunContinuationsAsynchronously);
+
+        await using (var server = new TestServer(async httpContext =>
+        {
+            httpContext.Response.StatusCode = statusCode;
+            httpContext.Response.Headers.ContentLength = 0;
+
+            try
+            {
+                await httpContext.Response.StartAsync();
+            }
+            catch (Exception ex)
+            {
+                responseWriteTcs.TrySetException(ex);
+                throw;
+            }
+
+            responseWriteTcs.TrySetResult();
+        }, new TestServiceContext(LoggerFactory)))
+        {
+            using (var connection = server.CreateConnection())
+            {
+                await connection.Send(
+                    $"{HttpUtilities.MethodToString(method)} / HTTP/1.1",
+                    "Host:",
+                    "",
+                    "");
+
+                await connection.Receive(
+                    $"HTTP/1.1 {Encoding.ASCII.GetString(ReasonPhrases.ToStatusBytes(statusCode))}",
+                    $"Date: {server.Context.DateHeaderValue}",
+                    "",
+                    "");
+            }
+        }
+    }
+
     [Fact]
     public async Task AttemptingToWriteNonzeroContentLengthFailsFor205Response()
     {