http: optimize checkIsHttpToken for short strings

Use lookup table instead of regex for strings shorter than 10
characters to improve performance for common short header names
while maintaining compatibility.

Author: JinhyeokFang

lib/_http_common.js

@@ -24,6 +24,7 @@
 const {
   MathMin,
   Symbol,
+  Uint8Array,
 } = primordials;
 const { setImmediate } = require('timers');
 
@@ -205,7 +206,30 @@ function freeParser(parser, req, socket) {
   }
 }
 
+// Character code ranges for valid HTTP tokens
+// Valid chars: ^_`a-zA-Z-0-9!#$%&'*+.|~
+// Based on RFC 7230 Section 3.2.6 token definition
+// See https://tools.ietf.org/html/rfc7230#section-3.2.6
 const tokenRegExp = /^[\^_`a-zA-Z\-0-9!#$%&'*+.|~]+$/;
+const validTokenChars = new Uint8Array([
+  0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, // 0-15
+  0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, // 16-31
+  0, 1, 0, 1, 1, 1, 1, 1, 0, 0, 1, 1, 0, 1, 1, 0, // 32-47 (!"#$%&'()*+,-./)
+  1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 0, 0, 0, 0, 0, 0, // 48-63 (0-9:;<=>?)
+  0, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, // 64-79 (@A-O)
+  1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 0, 0, 0, 1, 1, // 80-95 (P-Z[\]^_)
+  1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, // 96-111 (`a-o)
+  1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 0, 1, 0, 1, 0, // 112-127 (p-z{|}~)
+  0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, // 128-143
+  0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, // 144-159
+  0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, // 160-175
+  0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, // 176-191
+  0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, // 192-207
+  0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, // 208-223
+  0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, // 224-239
+  0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,  // 240-255
+]);
+
 /**
  * Verifies that the given val is a valid HTTP token
  * per the rules defined in RFC 7230
@@ -214,7 +238,19 @@ const tokenRegExp = /^[\^_`a-zA-Z\-0-9!#$%&'*+.|~]+$/;
  * @returns {boolean}
  */
 function checkIsHttpToken(val) {
-  return tokenRegExp.test(val);
+  if (val.length >= 10) {
+    return tokenRegExp.test(val);
+  }
+
+  if (val.length === 0) return false;
+
+  // Use lookup table for short strings, regex for longer ones
+  for (let i = 0; i < val.length; i++) {
+    if (!validTokenChars[val.charCodeAt(i)]) {
+      return false;
+    }
+  }
+  return true;
 }
 
 const headerCharRegex = /[^\t\x20-\x7e\x80-\xff]/;