Include ContentLength when enumerating HttpHeaders (#54760)

* Include ContentLength when enumerating HttpHeaders

...even if no bits are set.

Fixes #54557

* Remove now-unnecessary using

* Remove code that should have been deleted

* Add MethodImplOptions.AggressiveInlining

* Remove now-unnecessary using

Author: amcasey

src/Servers/Kestrel/Core/src/Internal/Http/HttpHeaders.Generated.cs

@@ -8670,6 +8670,16 @@ public bool MoveNext()
                     return true;
                 }
             }
+
+            [MethodImpl(MethodImplOptions.AggressiveInlining)]
+            private static int GetNext(long bits, bool hasContentLength)
+            {
+                return bits != 0
+                    ? BitOperations.TrailingZeroCount(bits)
+                    : hasContentLength
+                        ? 49
+                        : -1;
+            }
         }
     }
 
@@ -15496,6 +15506,16 @@ public bool MoveNext()
                     return true;
                 }
             }
+
+            [MethodImpl(MethodImplOptions.AggressiveInlining)]
+            private static int GetNext(long bits, bool hasContentLength)
+            {
+                return bits != 0
+                    ? BitOperations.TrailingZeroCount(bits)
+                    : hasContentLength
+                        ? 38
+                        : -1;
+            }
         }
     }
 
@@ -17609,4 +17629,4 @@ public bool MoveNext()
             }
         }
     }
-}
+}

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

@@ -4,7 +4,6 @@
 using System.Buffers.Text;
 using System.Collections;
 using System.Globalization;
-using System.Numerics;
 using System.Runtime.CompilerServices;
 using System.Text;
 using Microsoft.AspNetCore.Server.Kestrel.Core.Internal.Infrastructure;
@@ -244,7 +243,7 @@ internal Enumerator(HttpRequestHeaders collection)
         {
             _collection = collection;
             _currentBits = collection._bits;
-            _next = _currentBits != 0 ? BitOperations.TrailingZeroCount(_currentBits) : -1;
+            _next = GetNext(_currentBits, collection.ContentLength.HasValue);
             _current = default;
             _hasUnknown = collection.MaybeUnknown != null;
             _unknownEnumerator = _hasUnknown
@@ -263,7 +262,7 @@ public readonly void Dispose()
         public void Reset()
         {
             _currentBits = _collection._bits;
-            _next = _currentBits != 0 ? BitOperations.TrailingZeroCount(_currentBits) : -1;
+            _next = GetNext(_currentBits, _collection.ContentLength.HasValue);
         }
     }
 }

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

@@ -5,7 +5,6 @@
 using System.Collections;
 using System.Diagnostics.CodeAnalysis;
 using System.IO.Pipelines;
-using System.Numerics;
 using System.Runtime.CompilerServices;
 using System.Text;
 using Microsoft.Extensions.Primitives;
@@ -152,7 +151,7 @@ internal Enumerator(HttpResponseHeaders collection)
         {
             _collection = collection;
             _currentBits = collection._bits;
-            _next = _currentBits != 0 ? BitOperations.TrailingZeroCount(_currentBits) : -1;
+            _next = GetNext(_currentBits, collection.ContentLength.HasValue);
             _current = default;
             _currentKnownType = default;
             _hasUnknown = collection.MaybeUnknown != null;
@@ -174,7 +173,7 @@ public readonly void Dispose()
         public void Reset()
         {
             _currentBits = _collection._bits;
-            _next = _currentBits != 0 ? BitOperations.TrailingZeroCount(_currentBits) : -1;
+            _next = GetNext(_currentBits, _collection.ContentLength.HasValue);
         }
     }
 }

src/Servers/Kestrel/Core/test/HttpRequestHeadersTests.cs

@@ -831,6 +831,18 @@ public void MultiValueReuseEmptyAfterReset(bool reuseValue, string headerName)
         Assert.Equal(0, count);
     }
 
+    [Fact]
+    public void ContentLengthEnumerableWithoutOtherKnownHeader()
+    {
+        IHeaderDictionary headers = new HttpRequestHeaders();
+        headers["content-length"] = "1024";
+        Assert.Single(headers);
+        headers["unknown"] = "value";
+        Assert.Equal(2, headers.Count()); // NB: enumerable count, not property
+        headers["host"] = "myhost";
+        Assert.Equal(3, headers.Count()); // NB: enumerable count, not property
+    }
+
     private static (string PrevHeaderValue, string NextHeaderValue) GetHeaderValues(HttpRequestHeaders headers, string prevName, string nextName, string prevValue, string nextValue)
     {
         headers.Reset();

src/Servers/Kestrel/Core/test/HttpResponseHeadersTests.cs

@@ -392,6 +392,18 @@ public void ContentLengthValueClearedWhenHeadersCleared()
         Assert.Null(headers.ContentLength);
     }
 
+    [Fact]
+    public void ContentLengthEnumerableWithoutOtherKnownHeader()
+    {
+        IHeaderDictionary headers = new HttpResponseHeaders();
+        headers["content-length"] = "1024";
+        Assert.Single(headers);
+        headers["unknown"] = "value";
+        Assert.Equal(2, headers.Count()); // NB: enumerable count, not property
+        headers["host"] = "myhost";
+        Assert.Equal(3, headers.Count()); // NB: enumerable count, not property
+    }
+
     private static long ParseLong(string value)
     {
         return long.Parse(value, NumberStyles.AllowLeadingWhite | NumberStyles.AllowTrailingWhite, CultureInfo.InvariantCulture);

src/Servers/Kestrel/shared/KnownHeaders.cs

@@ -1428,7 +1428,17 @@ public bool MoveNext()
                     {(!loop.ClassName.Contains("Trailers") ? $@"_next = _collection._contentLength.HasValue ? {loop.Headers.Length - 1} : -1;" : "_next = -1;")}
                     return true;
                 }}
-            }}
+            }}{(loop.ClassName.Contains("Trailers") ? "" : $@"
+
+            [MethodImpl(MethodImplOptions.AggressiveInlining)]
+            private static int GetNext(long bits, bool hasContentLength)
+            {{
+                return bits != 0
+                    ? BitOperations.TrailingZeroCount(bits)
+                    : hasContentLength
+                        ? {loop.Headers.Length - 1}
+                        : -1;
+            }}")}
         }}
     }}
 ")}}}";