From 8b2f8088e926c6559a73a57f1c17a2b2e856f1be Mon Sep 17 00:00:00 2001
From: Ben Adams <thundercat@illyriad.co.uk>
Date: Tue, 28 Apr 2020 20:58:38 +0100
Subject: [PATCH] Make GetKnownHttpScheme "safe" (#21204)

---
 .../src/Internal/Infrastructure/HttpUtilities.cs   | 14 ++------------
 1 file changed, 2 insertions(+), 12 deletions(-)

diff --git a/src/Servers/Kestrel/Core/src/Internal/Infrastructure/HttpUtilities.cs b/src/Servers/Kestrel/Core/src/Internal/Infrastructure/HttpUtilities.cs
index cb59fa8aff..38cd1961ff 100644
--- a/src/Servers/Kestrel/Core/src/Internal/Infrastructure/HttpUtilities.cs
+++ b/src/Servers/Kestrel/Core/src/Internal/Infrastructure/HttpUtilities.cs
@@ -430,20 +430,10 @@ namespace Microsoft.AspNetCore.Server.Kestrel.Core.Internal.Infrastructure
         /// <param name="knownScheme">A reference to the known scheme, if the input matches any</param>
         /// <returns>True when memory starts with known http or https schema</returns>
         [MethodImpl(MethodImplOptions.AggressiveInlining)]
-        public static unsafe bool GetKnownHttpScheme(this Span<byte> span, out HttpScheme knownScheme)
+        public static bool GetKnownHttpScheme(this Span<byte> span, out HttpScheme knownScheme)
         {
-            fixed (byte* data = span)
+            if (BinaryPrimitives.TryReadUInt64LittleEndian(span, out var scheme))
             {
-                return GetKnownHttpScheme(data, span.Length, out knownScheme);
-            }
-        }
-
-        [MethodImpl(MethodImplOptions.AggressiveInlining)]
-        private static unsafe bool GetKnownHttpScheme(byte* location, int length, out HttpScheme knownScheme)
-        {
-            if (length >= sizeof(ulong))
-            {
-                var scheme = *(ulong*)location;
                 if ((scheme & _mask7Chars) == _httpSchemeLong)
                 {
                     knownScheme = HttpScheme.Http;