Throw multiple content lengths

Author: benaadams

src/Microsoft.AspNetCore.Server.Kestrel/BadHttpRequestException.cs

@@ -43,6 +43,9 @@ internal static BadHttpRequestException GetException(RequestRejectionReason reas
                 case RequestRejectionReason.MalformedRequestInvalidHeaders:
                     ex = new BadHttpRequestException("Malformed request: invalid headers.", StatusCodes.Status400BadRequest);
                     break;
+                case RequestRejectionReason.MultipleContentLengths:
+                    ex = new BadHttpRequestException("Multiple content length headers.", StatusCodes.Status400BadRequest);
+                    break;
                 case RequestRejectionReason.UnexpectedEndOfRequestContent:
                     ex = new BadHttpRequestException("Unexpected end of request content.", StatusCodes.Status400BadRequest);
                     break;

src/Microsoft.AspNetCore.Server.Kestrel/Internal/Http/FrameHeaders.Generated.cs

@@ -5123,7 +5123,7 @@ private unsafe void AppendNonPrimaryHeaders(byte[] keyBytes, int keyOffset, int
                             {
                                 if (ContentLength.HasValue)
                                 {
-                                    ThrowInvalidRequestContentLengthException(AppendValue(HeaderUtilities.FormatInt64(ContentLength.Value), value).ToString());
+                                    ThrowRequestMultipleContentLengths();
                                 }
                                 else
                                 {

src/Microsoft.AspNetCore.Server.Kestrel/Internal/Http/FrameHeaders.cs

@@ -450,6 +450,11 @@ protected static void ThrowInvalidRequestContentLengthException(string value)
             throw BadHttpRequestException.GetException(RequestRejectionReason.InvalidContentLength, value);
         }
 
+        protected static void ThrowRequestMultipleContentLengths()
+        {
+            throw BadHttpRequestException.GetException(RequestRejectionReason.MultipleContentLengths);
+        }
+
         private static void ThrowInvalidHeaderCharacter(char ch)
         {
             throw new InvalidOperationException(string.Format("Invalid non-ASCII or control character in header: 0x{0:X4}", (ushort)ch));

src/Microsoft.AspNetCore.Server.Kestrel/Internal/Http/RequestRejectionReason.cs

@@ -15,6 +15,7 @@ public enum RequestRejectionReason
         InvalidRequestLine,
         MalformedRequestInvalidHeaders,
         InvalidContentLength,
+        MultipleContentLengths,
         UnexpectedEndOfRequestContent,
         BadChunkSuffix,
         BadChunkSizeData,

tools/Microsoft.AspNetCore.Server.Kestrel.GeneratedCode/KnownHeaders.cs

@@ -34,11 +34,11 @@ static string AppendSwitch(IEnumerable<IGrouping<int, KnownHeader>> values, stri
                             {{{(header.Identifier == "ContentLength" ? $@"
                                 if (ContentLength.HasValue)
                                 {{
-                                    ThrowInvalid{(className == "FrameResponseHeaders" ? "Response" : "Request")}ContentLengthException(AppendValue(HeaderUtilities.FormatInt64(ContentLength.Value), value).ToString());
+                                    ThrowRequestMultipleContentLengths();
                                 }}
                                 else
                                 {{
-                                    ContentLength = Parse{(className == "FrameResponseHeaders" ? "Response" : "Request")}ContentLength(value);
+                                    ContentLength = ParseRequestContentLength(value);
                                 }}
                                 return;" : $@"
                                 if ({header.TestBit()})