Use loop for acceptParams (#6066)

lib/utils.js

@@ -124,16 +124,33 @@ exports.contentDisposition = deprecate.function(contentDisposition,
  */
 
 function acceptParams (str) {
-  var parts = str.split(/ *; */);
-  var ret = { value: parts[0], quality: 1, params: {} }
+  var length = str.length;
+  var colonIndex = str.indexOf(';');
+  var index = colonIndex === -1 ? length : colonIndex;
+  var ret = { value: str.slice(0, index).trim(), quality: 1, params: {} };
 
-  for (var i = 1; i < parts.length; ++i) {
-    var pms = parts[i].split(/ *= */);
-    if ('q' === pms[0]) {
-      ret.quality = parseFloat(pms[1]);
+  while (index < length) {
+    var splitIndex = str.indexOf('=', index);
+    if (splitIndex === -1) break;
+
+    var colonIndex = str.indexOf(';', index);
+    var endIndex = colonIndex === -1 ? length : colonIndex;
+
+    if (splitIndex > endIndex) {
+      index = str.lastIndexOf(';', splitIndex - 1) + 1;
+      continue;
+    }
+
+    var key = str.slice(index, splitIndex).trim();
+    var value = str.slice(splitIndex + 1, endIndex).trim();
+
+    if (key === 'q') {
+      ret.quality = parseFloat(value);
     } else {
-      ret.params[pms[0]] = pms[1];
+      ret.params[key] = value;
     }
+
+    index = endIndex + 1;
   }
 
   return ret;