add matchesMime() util

lib/request.js

@@ -514,18 +514,22 @@ module.exports = {
   is: function(types){
     // no request body
     if (!(this.length || 'transfer-encoding' in this.header)) return null;
+
     var ct = this.type;
-    // request body without a content type?
+    // no content-type
     if (!ct) return false;
+
+    // paramless
     ct = ct.split(';')[0];
+
     if (!types) return ct;
+
+    // ensure array
     if (!Array.isArray(types)) types = [].slice.call(arguments);
-    var type, mt, cts;
+
     for (var i = 0; i < types.length; i++) {
-      type = types[i];
-      // exact match
-      if (type == ct) return type;
-      // convert to a valid mime type
+      var type = types[i];
+
       switch (type) {
         case 'urlencoded':
           mt = 'application/x-www-form-urlencoded';
@@ -533,15 +537,10 @@ module.exports = {
         default:
           mt = ~type.indexOf('/') ? type : mime.lookup(type);
       }
-      // mime types match
-      if (mt == ct) return type;
-      // type or subtype match
-      if (!~type.indexOf('*')) continue;
-      mt = mt.split('/');
-      cts = cts || ct.split('/');
-      if ('*' == mt[0] && mt[1] == cts[1]) return type;
-      if ('*' == mt[1] && mt[0] == cts[0]) return type;
+
+      if (mimeMatch(mt, ct)) return type;
     }
+
     // no matches
     return false;
   },
@@ -632,3 +631,26 @@ function extToMime(type) {
   if (~type.indexOf('/')) return type;
   return mime.lookup(type);
 }
+
+/**
+ * Check if `exected` mime type
+ * matches `actual` mime type with
+ * wildcard support.
+ *
+ * @param {String} expected
+ * @param {String} actual
+ * @return {Boolean}
+ * @api private
+ */
+
+function mimeMatch(expected, actual) {
+  if (expected == actual) return true;
+
+  if (!~expected.indexOf('*')) return false;
+
+  actual = actual.split('/');
+  expected = expected.split('/');
+
+  if ('*' == expected[0] && expected[1] == actual[1]) return true;
+  if ('*' == expected[1] && expected[0] == actual[0]) return true;
+}