Revert "Improve Decode against timing attacks"

This reverts commit 1be1b717b743c89f2393561985403b51bc192255.

1 files changed, 16 insertions, 27 deletions

diff --git a/securecookie.go b/securecookie.go
index 5580507..1b7acf8 100644
--- a/securecookie.go
+++ b/securecookie.go
@@ -177,71 +177,60 @@ func (s *SecureCookie) Encode(name string, value interface{}) (string, error) {
 // it was stored. The value argument is the encoded cookie value. The dst
 // argument is where the cookie will be decoded. It must be a pointer.
 func (s *SecureCookie) Decode(name, value string, dst interface{}) error {
-	var retErr error
-	setErr := func(err error) {
-		if retErr == nil {
-			retErr = err
-		}
-	}
-
 	if s.err != nil {
-		setErr(s.err)
+		return s.err
 	}
 	if s.hashKey == nil {
 		s.err = errHashKeyNotSet
-		setErr(s.err)
+		return s.err
 	}
 	// 1. Check length.
 	if s.maxLength != 0 && len(value) > s.maxLength {
-		setErr(errors.New("securecookie: the value is too long"))
+		return errors.New("securecookie: the value is too long")
 	}
 	// 2. Decode from base64.
 	b, err := decode([]byte(value))
 	if err != nil {
-		setErr(err)
-		// Dummy b to avoid errors
-		b = []byte("||")
+		return err
 	}
 	// 3. Verify MAC. Value is "date|value|mac".
 	parts := bytes.SplitN(b, []byte("|"), 3)
 	if len(parts) != 3 {
-		setErr(ErrMacInvalid)
+		return ErrMacInvalid
 	}
 	h := hmac.New(s.hashFunc, s.hashKey)
 	b = append([]byte(name+"|"), b[:len(b)-len(parts[2])-1]...)
 	if err = verifyMac(h, b, parts[2]); err != nil {
-		setErr(err)
+		return err
 	}
 	// 4. Verify date ranges.
 	var t1 int64
 	if t1, err = strconv.ParseInt(string(parts[0]), 10, 64); err != nil {
-		setErr(errors.New("securecookie: invalid timestamp"))
+		return errors.New("securecookie: invalid timestamp")
 	}
 	t2 := s.timestamp()
 	if s.minAge != 0 && t1 > t2-s.minAge {
-		setErr(errors.New("securecookie: timestamp is too new"))
+		return errors.New("securecookie: timestamp is too new")
 	}
 	if s.maxAge != 0 && t1 < t2-s.maxAge {
-		setErr(errors.New("securecookie: expired timestamp"))
+		return errors.New("securecookie: expired timestamp")
 	}
 	// 5. Decrypt (optional).
 	b, err = decode(parts[1])
 	if err != nil {
-		setErr(err)
+		return err
 	}
 	if s.block != nil {
 		if b, err = decrypt(s.block, b); err != nil {
-			setErr(err)
+			return err
 		}
 	}
-
-	// Check for errors before deserialization to avoid unwanted side effects
-	if retErr != nil {
-		return retErr
-	}
-
 	// 6. Deserialize.
-	return deserialize(b, dst)
+	if err = deserialize(b, dst); err != nil {
+		return err
+	}
+	// Done.
+	return nil
 }
 
 // timestamp returns the current timestamp, in seconds.