Use IndexOfAnyValues in ForwardedHeadersMiddleware

src/Middleware/HttpOverrides/src/ForwardedHeadersMiddleware.cs

@@ -1,6 +1,7 @@
 // Licensed to the .NET Foundation under one or more agreements.
 // The .NET Foundation licenses this file to you under the MIT license.
 
+using System.Buffers;
 using System.Linq;
 using System.Net;
 using System.Runtime.CompilerServices;
@@ -17,50 +18,24 @@ namespace Microsoft.AspNetCore.HttpOverrides;
 /// </summary>
 public class ForwardedHeadersMiddleware
 {
-    private static readonly bool[] HostCharValidity = new bool[127];
-    private static readonly bool[] SchemeCharValidity = new bool[123];
-
     private readonly ForwardedHeadersOptions _options;
     private readonly RequestDelegate _next;
     private readonly ILogger _logger;
     private bool _allowAllHosts;
     private IList<StringSegment>? _allowedHosts;
 
-    static ForwardedHeadersMiddleware()
-    {
-        // RFC 3986 scheme = ALPHA * (ALPHA / DIGIT / "+" / "-" / ".")
-        SchemeCharValidity['+'] = true;
-        SchemeCharValidity['-'] = true;
-        SchemeCharValidity['.'] = true;
-
-        // Host Matches Http.Sys and Kestrel
-        // Host Matches RFC 3986 except "*" / "+" / "," / ";" / "=" and "%" HEXDIG HEXDIG which are not allowed by Http.Sys
-        HostCharValidity['!'] = true;
-        HostCharValidity['$'] = true;
-        HostCharValidity['&'] = true;
-        HostCharValidity['\''] = true;
-        HostCharValidity['('] = true;
-        HostCharValidity[')'] = true;
-        HostCharValidity['-'] = true;
-        HostCharValidity['.'] = true;
-        HostCharValidity['_'] = true;
-        HostCharValidity['~'] = true;
-        for (var ch = '0'; ch <= '9'; ch++)
-        {
-            SchemeCharValidity[ch] = true;
-            HostCharValidity[ch] = true;
-        }
-        for (var ch = 'A'; ch <= 'Z'; ch++)
-        {
-            SchemeCharValidity[ch] = true;
-            HostCharValidity[ch] = true;
-        }
-        for (var ch = 'a'; ch <= 'z'; ch++)
-        {
-            SchemeCharValidity[ch] = true;
-            HostCharValidity[ch] = true;
-        }
-    }
+    // RFC 3986 scheme = ALPHA * (ALPHA / DIGIT / "+" / "-" / ".")
+    private static readonly IndexOfAnyValues<char> SchemeChars =
+        IndexOfAnyValues.Create("+-.0123456789ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz");
+
+    // Host Matches Http.Sys and Kestrel
+    // Host Matches RFC 3986 except "*" / "+" / "," / ";" / "=" and "%" HEXDIG HEXDIG which are not allowed by Http.Sys
+    private static readonly IndexOfAnyValues<char> HostChars =
+        IndexOfAnyValues.Create("!$&'()-.0123456789ABCDEFGHIJKLMNOPQRSTUVWXYZ_abcdefghijklmnopqrstuvwxyz~");
+
+    // 0-9 / A-F / a-f / ":" / "."
+    private static readonly IndexOfAnyValues<char> Ipv6HostChars =
+        IndexOfAnyValues.Create(".0123456789:ABCDEFabcdef");
 
     /// <summary>
     /// Create a new <see cref="ForwardedHeadersMiddleware"/>.
@@ -264,7 +239,7 @@ public void ApplyForwarders(HttpContext context)
 
             if (checkProto)
             {
-                if (!string.IsNullOrEmpty(set.Scheme) && TryValidateScheme(set.Scheme))
+                if (!string.IsNullOrEmpty(set.Scheme) && set.Scheme.AsSpan().IndexOfAnyExcept(SchemeChars) < 0)
                 {
                     applyChanges = true;
                     currentValues.Scheme = set.Scheme;
@@ -383,26 +358,6 @@ private struct SetOfForwarders
         public string Scheme;
     }
 
-    // Empty was checked for by the caller
-    [MethodImpl(MethodImplOptions.AggressiveInlining)]
-    private static bool TryValidateScheme(string scheme)
-    {
-        for (var i = 0; i < scheme.Length; i++)
-        {
-            if (!IsValidSchemeChar(scheme[i]))
-            {
-                return false;
-            }
-        }
-        return true;
-    }
-
-    [MethodImpl(MethodImplOptions.AggressiveInlining)]
-    private static bool IsValidSchemeChar(char ch)
-    {
-        return ch < SchemeCharValidity.Length && SchemeCharValidity[ch];
-    }
-
     // Empty was checked for by the caller
     [MethodImpl(MethodImplOptions.AggressiveInlining)]
     private static bool TryValidateHost(string host)
@@ -418,87 +373,48 @@ private static bool TryValidateHost(string host)
             return false;
         }
 
-        var i = 0;
-        for (; i < host.Length; i++)
+        var firstNonHostCharIdx = host.AsSpan().IndexOfAnyExcept(HostChars);
+        if (firstNonHostCharIdx == -1)
         {
-            if (!IsValidHostChar(host[i]))
-            {
-                break;
-            }
+            // no port
+            return true;
+        }
+        else
+        {
+            return TryValidateHostPort(host, firstNonHostCharIdx);
         }
-        return TryValidateHostPort(host, i);
-    }
-
-    [MethodImpl(MethodImplOptions.AggressiveInlining)]
-    private static bool IsValidHostChar(char ch)
-    {
-        return ch < HostCharValidity.Length && HostCharValidity[ch];
     }
 
     // The lead '[' was already checked
     [MethodImpl(MethodImplOptions.AggressiveInlining)]
     private static bool TryValidateIPv6Host(string hostText)
     {
-        for (var i = 1; i < hostText.Length; i++)
-        {
-            var ch = hostText[i];
-            if (ch == ']')
-            {
-                // [::1] is the shortest valid IPv6 host
-                if (i < 4)
-                {
-                    return false;
-                }
-                return TryValidateHostPort(hostText, i + 1);
-            }
+        var host = hostText.AsSpan(1);
 
-            if (!IsHex(ch) && ch != ':' && ch != '.')
-            {
-                return false;
-            }
+        var hostEndIdx = host.IndexOfAnyExcept(Ipv6HostChars);
+        if ((uint)hostEndIdx >= (uint)host.Length || // No ']'. The uint cast is there to eliminate the
+                                                     // bounds check on the 'host[hostEndIdx]' access below.
+            host[hostEndIdx] != ']' || // We found an invalid host character
+            hostEndIdx < 3) // [::1] is the shortest valid IPv6 host
+        {
+            return false;
         }
 
-        // Must contain a ']'
-        return false;
+        // If there's nothing left, we're good. If there's more, validate it as a port.
+        // +2 to skip the '[' and ']' (the '[' wasn't included in hostEndIdx because we
+        // cut it off in the AsSpan above).
+        return (hostEndIdx + 2 == hostText.Length) || TryValidateHostPort(hostText, hostEndIdx + 2);
     }
 
     [MethodImpl(MethodImplOptions.AggressiveInlining)]
     private static bool TryValidateHostPort(string hostText, int offset)
     {
-        if (offset == hostText.Length)
-        {
-            // No port
-            return true;
-        }
-
         if (hostText[offset] != ':' || hostText.Length == offset + 1)
         {
             // Must have at least one number after the colon if present.
             return false;
         }
 
-        for (var i = offset + 1; i < hostText.Length; i++)
-        {
-            if (!IsNumeric(hostText[i]))
-            {
-                return false;
-            }
-        }
-
-        return true;
-    }
-
-    [MethodImpl(MethodImplOptions.AggressiveInlining)]
-    private static bool IsNumeric(char ch)
-    {
-        return '0' <= ch && ch <= '9';
-    }
-
-    [MethodImpl(MethodImplOptions.AggressiveInlining)]
-    private static bool IsHex(char ch)
-    {
-        return IsNumeric(ch)
-            || ('a' <= ch && ch <= 'f')
-            || ('A' <= ch && ch <= 'F');
+        return hostText.AsSpan(offset + 1).IndexOfAnyExceptInRange('0', '9') < 0;
     }
 }