fetch: improve performance of isValidHeaderValue

benchmarks/fetch/is-valid-header-value.mjs

@@ -0,0 +1,38 @@
+import { bench, run } from 'mitata'
+import { isValidHeaderValue } from '../../lib/web/fetch/util.js'
+
+const valid = 'valid123'
+const invalidNUL = 'invalid\x00'
+const invalidCR = 'invalid\r'
+const invalidLF = 'invalid\n'
+const invalidTrailingTab = 'invalid\t'
+const invalidLeadingTab = '\tinvalid'
+const invalidTrailingSpace = 'invalid '
+const invalidLeadingSpace = ' invalid'
+
+bench('isValidHeaderValue valid', () => {
+  isValidHeaderValue(valid)
+})
+bench('isValidHeaderValue invalid containing NUL', () => {
+  isValidHeaderValue(invalidNUL)
+})
+bench('isValidHeaderValue invalid containing CR', () => {
+  isValidHeaderValue(invalidCR)
+})
+bench('isValidHeaderValue invalid containing LF', () => {
+  isValidHeaderValue(invalidLF)
+})
+bench('isValidHeaderValue invalid trailing TAB', () => {
+  isValidHeaderValue(invalidTrailingTab)
+})
+bench('isValidHeaderValue invalid leading TAB', () => {
+  isValidHeaderValue(invalidLeadingTab)
+})
+bench('isValidHeaderValue invalid trailing SPACE', () => {
+  isValidHeaderValue(invalidTrailingSpace)
+})
+bench('isValidHeaderValue invalid leading SPACE', () => {
+  isValidHeaderValue(invalidLeadingSpace)
+})
+
+await run()

lib/web/fetch/util.js

@@ -159,24 +159,15 @@ const isValidHeaderName = isValidHTTPToken
 function isValidHeaderValue (potentialValue) {
   // - Has no leading or trailing HTTP tab or space bytes.
   // - Contains no 0x00 (NUL) or HTTP newline bytes.
-  if (
-    potentialValue.startsWith('\t') ||
-    potentialValue.startsWith(' ') ||
-    potentialValue.endsWith('\t') ||
-    potentialValue.endsWith(' ')
-  ) {
-    return false
-  }
-
-  if (
-    potentialValue.includes('\0') ||
+  return (
+    potentialValue[0] === '\t' ||
+    potentialValue[0] === ' ' ||
+    potentialValue[potentialValue.length - 1] === '\t' ||
+    potentialValue[potentialValue.length - 1] === ' ' ||
+    potentialValue.includes('\n') ||
     potentialValue.includes('\r') ||
-    potentialValue.includes('\n')
-  ) {
-    return false
-  }
-
-  return true
+    potentialValue.includes('\0')
+  ) === false
 }
 
 // https://w3c.github.io/webappsec-referrer-policy/#set-requests-referrer-policy-on-redirect

test/fetch/util.js

@@ -355,3 +355,41 @@ describe('urlHasHttpsScheme', () => {
     assert.strictEqual(urlHasHttpsScheme({ protocol: 'https:' }), true)
   })
 })
+
+describe('isValidHeaderValue', () => {
+  const { isValidHeaderValue } = util
+
+  test('should return true for valid string', () => {
+    assert.strictEqual(isValidHeaderValue('valid123'), true)
+    assert.strictEqual(isValidHeaderValue('va lid123'), true)
+    assert.strictEqual(isValidHeaderValue('va\tlid123'), true)
+  })
+  test('should return false for string containing NUL', () => {
+    assert.strictEqual(isValidHeaderValue('invalid\0'), false)
+    assert.strictEqual(isValidHeaderValue('in\0valid'), false)
+    assert.strictEqual(isValidHeaderValue('\0invalid'), false)
+  })
+  test('should return false for string containing CR', () => {
+    assert.strictEqual(isValidHeaderValue('invalid\r'), false)
+    assert.strictEqual(isValidHeaderValue('in\rvalid'), false)
+    assert.strictEqual(isValidHeaderValue('\rinvalid'), false)
+  })
+  test('should return false for string containing LF', () => {
+    assert.strictEqual(isValidHeaderValue('invalid\n'), false)
+    assert.strictEqual(isValidHeaderValue('in\nvalid'), false)
+    assert.strictEqual(isValidHeaderValue('\ninvalid'), false)
+  })
+
+  test('should return false for string with leading TAB', () => {
+    assert.strictEqual(isValidHeaderValue('\tinvalid'), false)
+  })
+  test('should return false for string with trailing TAB', () => {
+    assert.strictEqual(isValidHeaderValue('invalid\t'), false)
+  })
+  test('should return false for string with leading SPACE', () => {
+    assert.strictEqual(isValidHeaderValue(' invalid'), false)
+  })
+  test('should return false for string with trailing SPACE', () => {
+    assert.strictEqual(isValidHeaderValue('invalid '), false)
+  })
+})