Make OperationError final (#177)

Author: jonasfj

lib/src/impl_ffi/impl_ffi.aesgcm.dart

@@ -41,7 +41,7 @@ Future<Uint8List> _aesGcmEncryptDecrypt(
   final additionalData_ = additionalData ??= <int>[];
   if (isEncrypt && data.length > (1 << 39) - 256) {
     // More than this is not allowed by Web crypto spec, we shall honor that.
-    throw _OperationError('data may not be more than 2^39 - 256 bytes');
+    throw operationError('data may not be more than 2^39 - 256 bytes');
   }
   if (tagLength != 32 &&
       tagLength != 64 &&
@@ -50,7 +50,7 @@ Future<Uint8List> _aesGcmEncryptDecrypt(
       tagLength != 112 &&
       tagLength != 120 &&
       tagLength != 128) {
-    throw _OperationError('tagLength must be 32, 64, 96, 104, 112, 120 or 128');
+    throw operationError('tagLength must be 32, 64, 96, 104, 112, 120 or 128');
   }
 
   // TODO: Check iv length is less than EVP_AEAD_nonce_length, if this is a requirement!

lib/src/impl_ffi/impl_ffi.dart

@@ -48,16 +48,6 @@ part 'impl_ffi.rsa_common.dart';
 part 'impl_ffi.ec_common.dart';
 part 'impl_ffi.aes_common.dart';
 
-/// Implementation of [OperationError].
-class _OperationError extends Error implements OperationError {
-  final String _message;
-
-  _OperationError(this._message);
-
-  @override
-  String toString() => _message;
-}
-
 const WebCryptoImpl webCryptImpl = _WebCryptoImpl();
 
 final class _WebCryptoImpl implements WebCryptoImpl {

lib/src/impl_ffi/impl_ffi.ec_common.dart

@@ -41,7 +41,7 @@ EllipticCurve _ecCurveFromNID(int nid) {
     return EllipticCurve.p521;
   }
   // This should never happen!
-  throw _OperationError('internal error detecting curve');
+  throw operationError('internal error detecting curve');
 }
 
 String _ecCurveToJwkCrv(EllipticCurve curve) {

lib/src/impl_ffi/impl_ffi.ecdh.dart

@@ -142,7 +142,7 @@ final class _EcdhPrivateKeyImpl implements EcdhPrivateKeyImpl {
           ssl.EC_GROUP_get_degree(ssl.EC_KEY_get0_group(privEcKey));
       final maxLength = 8 * (fieldSize / 8).ceil();
       if (length > maxLength) {
-        throw _OperationError(
+        throw operationError(
           'Length in ECDH key derivation is too large. '
           'Maximum allowed is $maxLength bits.',
         );

lib/src/impl_ffi/impl_ffi.hkdf.dart

@@ -53,7 +53,7 @@ final class _HkdfSecretKeyImpl implements HkdfSecretKeyImpl {
     // Mirroring limitations in chromium:
     // https://chromium.googlesource.com/chromium/src/+/43d62c50b705f88c67b14539e91fd8fd017f70c4/components/webcrypto/algorithms/hkdf.cc#74
     if (length % 8 != 0) {
-      throw _OperationError('The length for HKDF must be a multiple of 8 bits');
+      throw operationError('The length for HKDF must be a multiple of 8 bits');
     }
 
     final lengthInBytes = length ~/ 8;
@@ -76,7 +76,7 @@ final class _HkdfSecretKeyImpl implements HkdfSecretKeyImpl {
         if (ERR_GET_LIB(packed_error) == ERR_LIB_HKDF &&
             ERR_GET_REASON(packed_error) == HKDF_R_OUTPUT_TOO_LARGE) {
           ssl.ERR_clear_error();
-          throw _OperationError(
+          throw operationError(
             'Length specified for HkdfSecretKey.deriveBits is too long',
           );
         }

lib/src/impl_ffi/impl_ffi.pbkdf2.dart

@@ -55,15 +55,15 @@ final class _Pbkdf2SecretKeyImpl implements Pbkdf2SecretKeyImpl {
     // Mirroring limitations in chromium:
     // https://chromium.googlesource.com/chromium/src/+/43d62c50b705f88c67b14539e91fd8fd017f70c4/components/webcrypto/algorithms/pbkdf2.cc#75
     if (length % 8 != 0) {
-      throw _OperationError(
+      throw operationError(
           'The length for PBKDF2 must be a multiple of 8 bits');
     }
     if (length == 0) {
-      throw _OperationError(
+      throw operationError(
           'A length of zero is not allowed Pbkdf2SecretKey.deriveBits');
     }
     if (iterations <= 0) {
-      throw _OperationError(
+      throw operationError(
           'Iterations <= 0 is not allowed for Pbkdf2SecretKey.deriveBits');
     }
 

lib/src/impl_ffi/impl_ffi.utils.dart

@@ -102,7 +102,7 @@ void _checkOp(bool condition, {String? message, String? fallback}) {
     // Always extract the error to ensure we clear the error queue.
     final err = _extractError();
     message ??= err ?? fallback ?? 'unknown error';
-    throw _OperationError(message);
+    throw operationError(message);
   }
 }
 

lib/src/impl_interface/impl_interface.dart

@@ -17,6 +17,8 @@ library impl_stub;
 import 'dart:typed_data';
 import 'dart:async';
 
+import 'package:meta/meta.dart';
+
 part 'impl_interface.aescbc.dart';
 part 'impl_interface.aesctr.dart';
 part 'impl_interface.hmac.dart';
@@ -62,6 +64,20 @@ enum EllipticCurve {
   p521,
 }
 
+/// Thrown when an operation failed for an operation-specific reason.
+final class OperationError extends Error {
+  final String _message;
+
+  OperationError._(this._message); // keep the constructor private.
+
+  @override
+  String toString() => _message;
+}
+
+/// Creating an [OperationError].
+@internal
+OperationError operationError(String message) => OperationError._(message);
+
 /// Interface to be provided by platform implementations.
 ///
 /// A platform implementation of `package:webcrypto` must define a

lib/src/impl_js/impl_js.dart

@@ -19,7 +19,6 @@ import 'dart:typed_data';
 
 import 'package:webcrypto/src/impl_interface/impl_interface.dart';
 
-import '../webcrypto/webcrypto.dart';
 import '../crypto_subtle.dart' as subtle;
 
 part 'impl_js.aescbc.dart';
@@ -37,14 +36,6 @@ part 'impl_js.rsapss.dart';
 part 'impl_js.rsassapkcs1v15.dart';
 part 'impl_js.utils.dart';
 
-/// Implementation of [OperationError].
-class _OperationError extends Error implements OperationError {
-  final String _message;
-  _OperationError(this._message);
-  @override
-  String toString() => _message;
-}
-
 const WebCryptoImpl webCryptImpl = _WebCryptoImpl();
 
 final class _WebCryptoImpl implements WebCryptoImpl {

lib/src/impl_js/impl_js.utils.dart

@@ -69,7 +69,7 @@ Object _translateDomException(
     case 'DataError':
       return FormatException(message);
     case 'OperationError':
-      return _OperationError(message);
+      return operationError(message);
     case 'InvalidAccessError':
       // InvalidAccessError occurs when the request operation is not valid for
       // the provided key. This is typically because: