http: improve validation performance

The new table-based lookups perform significantly better for the
common cases (checking latin1 characters).

PR-URL: https://github.com/nodejs/node/pull/6533
Reviewed-By: Matteo Collina <matteo.collina@gmail.com>
Reviewed-By: James M Snell <jasnell@gmail.com>
Reviewed-By: Fedor Indutny <fedor.indutny@gmail.com>
Reviewed-By: Benjamin Gruenbaum <benjamingr@gmail.com>

lib/_http_common.js

@@ -246,45 +246,45 @@ exports.httpSocketSetup = httpSocketSetup;
  * so take care when making changes to the implementation so that the source
  * code size does not exceed v8's default max_inlined_source_size setting.
  **/
-function isValidTokenChar(ch) {
-  if (ch >= 94 && ch <= 122)
-    return true;
-  if (ch >= 65 && ch <= 90)
-    return true;
-  if (ch === 45)
-    return true;
-  if (ch >= 48 && ch <= 57)
-    return true;
-  if (ch === 34 || ch === 40 || ch === 41 || ch === 44)
-    return false;
-  if (ch >= 33 && ch <= 46)
-    return true;
-  if (ch === 124 || ch === 126)
-    return true;
-  return false;
-}
+var validTokens = [
+  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, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, // 64 - 79
+  1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 0, 0, 0, 1, 1, // 80 - 95
+  1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, // 96 - 111
+  1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 0, 1, 0, 1, 0, // 112 - 127
+  0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, // 128 ...
+  0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
+  0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
+  0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
+  0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
+  0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
+  0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
+  0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0  // ... 255
+];
 function checkIsHttpToken(val) {
   if (typeof val !== 'string' || val.length === 0)
     return false;
-  if (!isValidTokenChar(val.charCodeAt(0)))
+  if (!validTokens[val.charCodeAt(0)])
     return false;
-  const len = val.length;
-  if (len > 1) {
-    if (!isValidTokenChar(val.charCodeAt(1)))
+  if (val.length < 2)
+    return true;
+  if (!validTokens[val.charCodeAt(1)])
     return false;
-    if (len > 2) {
-      if (!isValidTokenChar(val.charCodeAt(2)))
+  if (val.length < 3)
+    return true;
+  if (!validTokens[val.charCodeAt(2)])
     return false;
-      if (len > 3) {
-        if (!isValidTokenChar(val.charCodeAt(3)))
+  if (val.length < 4)
+    return true;
+  if (!validTokens[val.charCodeAt(3)])
     return false;
-        for (var i = 4; i < len; i++) {
-          if (!isValidTokenChar(val.charCodeAt(i)))
+  for (var i = 4; i < val.length; ++i) {
+    if (!validTokens[val.charCodeAt(i)])
       return false;
   }
-      }
-    }
-  }
   return true;
 }
 exports._checkIsHttpToken = checkIsHttpToken;
@@ -299,26 +299,44 @@ exports._checkIsHttpToken = checkIsHttpToken;
  * so take care when making changes to the implementation so that the source
  * code size does not exceed v8's default max_inlined_source_size setting.
  **/
+var validHdrChars = [
+  0, 0, 0, 0, 0, 0, 0, 0, 0, 1, 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
+  1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, // 32 - 47
+  1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, // 48 - 63
+  1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, // 64 - 79
+  1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, // 80 - 95
+  1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, // 96 - 111
+  1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 0, // 112 - 127
+  1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, // 128 ...
+  1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1,
+  1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1,
+  1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1,
+  1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1,
+  1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1,
+  1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1,
+  1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1  // ... 255
+];
 function checkInvalidHeaderChar(val) {
   val += '';
   if (val.length < 1)
     return false;
-  var c = val.charCodeAt(0);
-  if ((c <= 31 && c !== 9) || c > 255 || c === 127)
+  if (!validHdrChars[val.charCodeAt(0)])
     return true;
   if (val.length < 2)
     return false;
-  c = val.charCodeAt(1);
-  if ((c <= 31 && c !== 9) || c > 255 || c === 127)
+  if (!validHdrChars[val.charCodeAt(1)])
     return true;
   if (val.length < 3)
     return false;
-  c = val.charCodeAt(2);
-  if ((c <= 31 && c !== 9) || c > 255 || c === 127)
+  if (!validHdrChars[val.charCodeAt(2)])
+    return true;
+  if (val.length < 4)
+    return false;
+  if (!validHdrChars[val.charCodeAt(3)])
     return true;
-  for (var i = 3; i < val.length; ++i) {
-    c = val.charCodeAt(i);
-    if ((c <= 31 && c !== 9) || c > 255 || c === 127)
+  for (var i = 4; i < val.length; ++i) {
+    if (!validHdrChars[val.charCodeAt(i)])
       return true;
   }
   return false;