Respect the documented precedence of options (#163)

cors.go

@@ -140,33 +140,29 @@ func New(options Options) *Cors {
 		c.Log = log.New(os.Stdout, "[cors] ", log.LstdFlags)
 	}
 
-	if options.AllowOriginVaryRequestFunc != nil {
+	// Allowed origins
+	switch {
+	case options.AllowOriginVaryRequestFunc != nil:
 		c.allowOriginFunc = options.AllowOriginVaryRequestFunc
-	} else if options.AllowOriginRequestFunc != nil {
+	case options.AllowOriginRequestFunc != nil:
 		c.allowOriginFunc = func(r *http.Request, origin string) (bool, []string) {
 			return options.AllowOriginRequestFunc(r, origin), nil
 		}
-	} else if options.AllowOriginFunc != nil {
+	case options.AllowOriginFunc != nil:
 		c.allowOriginFunc = func(r *http.Request, origin string) (bool, []string) {
 			return options.AllowOriginFunc(origin), nil
 		}
-	}
-
-	// Normalize options
-	// Note: for origins matching, the spec requires a case-sensitive matching.
-	// As it may error prone, we chose to ignore the spec here.
-
-	// Allowed Origins
-	if len(options.AllowedOrigins) == 0 {
+	case len(options.AllowedOrigins) == 0:
 		if c.allowOriginFunc == nil {
 			// Default is all origins
 			c.allowedOriginsAll = true
 		}
-	} else {
+	default:
 		c.allowedOrigins = []string{}
 		c.allowedWOrigins = []wildcard{}
 		for _, origin := range options.AllowedOrigins {
-			// Normalize
+			// Note: for origins matching, the spec requires a case-sensitive matching.
+			// As it may error prone, we chose to ignore the spec here.
 			origin = strings.ToLower(origin)
 			if origin == "*" {
 				// If "*" is present in the list, turn the whole list into a match all

cors_test.go

@@ -481,6 +481,23 @@ func TestSpec(t *testing.T) {
 				"Access-Control-Allow-Origin": "http://foobar.com",
 			},
 			true,
+		}, {
+			"AllowedOriginsPlusAllowOriginFunc",
+			Options{
+				AllowedOrigins: []string{"*"},
+				AllowOriginFunc: func(origin string) bool {
+					return true
+				},
+			},
+			"GET",
+			map[string]string{
+				"Origin": "http://foobar.com",
+			},
+			map[string]string{
+				"Vary":                        "Origin",
+				"Access-Control-Allow-Origin": "http://foobar.com",
+			},
+			true,
 		},
 	}
 	for i := range cases {