feat(core): Make SCRAM SASL2 aware

packages/moxxmpp/lib/src/connection.dart

@@ -268,7 +268,8 @@ class XmppConnection {
 
   /// Register a list of negotiator with the connection.
   Future<void> registerFeatureNegotiators(
-      List<XmppFeatureNegotiatorBase> negotiators) async {
+    List<XmppFeatureNegotiatorBase> negotiators,
+  ) async {
     for (final negotiator in negotiators) {
       _log.finest('Registering ${negotiator.id}');
       negotiator.register(

packages/moxxmpp/lib/src/negotiators/sasl/plain.dart

@@ -4,7 +4,6 @@ import 'package:moxxmpp/src/events.dart';
 import 'package:moxxmpp/src/negotiators/namespaces.dart';
 import 'package:moxxmpp/src/negotiators/negotiator.dart';
 import 'package:moxxmpp/src/negotiators/sasl/errors.dart';
-import 'package:moxxmpp/src/negotiators/sasl/negotiator.dart';
 import 'package:moxxmpp/src/negotiators/sasl/nonza.dart';
 import 'package:moxxmpp/src/negotiators/sasl2.dart';
 import 'package:moxxmpp/src/stringxml.dart';
@@ -58,7 +57,6 @@ class SaslPlainNegotiator extends Sasl2AuthenticationNegotiator {
     } else {
       final tag = nonza.tag;
       if (tag == 'success') {
-        await attributes.sendEvent(AuthenticationSuccessEvent());
         attributes.setAuthenticated();
         return const Result(NegotiatorState.done);
       } else {
@@ -90,7 +88,8 @@ class SaslPlainNegotiator extends Sasl2AuthenticationNegotiator {
   Future<String> getRawStep(String input) async {
     final settings = attributes.getConnectionSettings();
     return base64.encode(
-        utf8.encode('\u0000${settings.jid.local}\u0000${settings.password}'));
+      utf8.encode('\u0000${settings.jid.local}\u0000${settings.password}'),
+    );
   }
 
   @override

packages/moxxmpp/lib/src/negotiators/sasl/scram.dart

@@ -8,8 +8,8 @@ import 'package:moxxmpp/src/negotiators/namespaces.dart';
 import 'package:moxxmpp/src/negotiators/negotiator.dart';
 import 'package:moxxmpp/src/negotiators/sasl/errors.dart';
 import 'package:moxxmpp/src/negotiators/sasl/kv.dart';
-import 'package:moxxmpp/src/negotiators/sasl/negotiator.dart';
 import 'package:moxxmpp/src/negotiators/sasl/nonza.dart';
+import 'package:moxxmpp/src/negotiators/sasl2.dart';
 import 'package:moxxmpp/src/stringxml.dart';
 import 'package:moxxmpp/src/types/result.dart';
 import 'package:random_string/random_string.dart';
@@ -95,7 +95,7 @@ enum ScramState { preSent, initialMessageSent, challengeResponseSent, error }
 
 const gs2Header = 'n,,';
 
-class SaslScramNegotiator extends SaslNegotiator {
+class SaslScramNegotiator extends Sasl2AuthenticationNegotiator {
   // NOTE: NEVER, and I mean, NEVER set clientNonce or initalMessageNoGS2. They are just there for testing
   SaslScramNegotiator(
     int priority,
@@ -236,20 +236,9 @@ class SaslScramNegotiator extends SaslNegotiator {
   ) async {
     switch (_scramState) {
       case ScramState.preSent:
-        if (clientNonce == null || clientNonce == '') {
-          clientNonce = randomAlphaNumeric(
-            40,
-            provider: CoreRandomProvider.from(Random.secure()),
-          );
-        }
-
-        initialMessageNoGS2 =
-            'n=${attributes.getConnectionSettings().jid.local},r=$clientNonce';
-
-        _scramState = ScramState.initialMessageSent;
         attributes.sendNonza(
           SaslScramAuthNonza(
-            body: base64.encode(utf8.encode(gs2Header + initialMessageNoGS2)),
+            body: await getRawStep(''),
             type: hashType,
           ),
           redact: SaslScramAuthNonza(body: '******', type: hashType).toXml(),
@@ -266,12 +255,8 @@ class SaslScramNegotiator extends SaslNegotiator {
           );
         }
 
-        final challengeBase64 = nonza.innerText();
-        final response = await calculateChallengeResponse(challengeBase64);
-        final responseBase64 = base64.encode(utf8.encode(response));
-        _scramState = ScramState.challengeResponseSent;
         attributes.sendNonza(
-          SaslScramResponseNonza(body: responseBase64),
+          SaslScramResponseNonza(body: await getRawStep(nonza.innerText())),
           redact: SaslScramResponseNonza(body: '******').toXml(),
         );
         return const Result(NegotiatorState.ready);
@@ -314,4 +299,43 @@ class SaslScramNegotiator extends SaslNegotiator {
 
     super.reset();
   }
+
+  @override
+  Future<String> getRawStep(String input) async {
+    switch (_scramState) {
+      case ScramState.preSent:
+        if (clientNonce == null || clientNonce == '') {
+          clientNonce = randomAlphaNumeric(
+            40,
+            provider: CoreRandomProvider.from(Random.secure()),
+          );
+        }
+
+        initialMessageNoGS2 =
+            'n=${attributes.getConnectionSettings().jid.local},r=$clientNonce';
+
+        _scramState = ScramState.initialMessageSent;
+        return base64.encode(utf8.encode(gs2Header + initialMessageNoGS2));
+      case ScramState.initialMessageSent:
+        final challengeBase64 = input;
+        final response = await calculateChallengeResponse(challengeBase64);
+        final responseBase64 = base64.encode(utf8.encode(response));
+        _scramState = ScramState.challengeResponseSent;
+
+        return responseBase64;
+      case ScramState.challengeResponseSent:
+      case ScramState.error:
+        return '';
+    }
+  }
+
+  @override
+  Future<List<XMLNode>> onSasl2FeaturesReceived(XMLNode sasl2Features) async {
+    return [];
+  }
+
+  @override
+  Future<void> onSasl2Success(XMLNode response) async {
+    state = NegotiatorState.done;
+  }
 }

packages/moxxmpp/lib/src/negotiators/sasl2.dart

@@ -1,4 +1,3 @@
-import 'package:moxxmpp/src/events.dart';
 import 'package:moxxmpp/src/namespaces.dart';
 import 'package:moxxmpp/src/negotiators/namespaces.dart';
 import 'package:moxxmpp/src/negotiators/negotiator.dart';
@@ -6,15 +5,14 @@ import 'package:moxxmpp/src/negotiators/sasl/negotiator.dart';
 import 'package:moxxmpp/src/stringxml.dart';
 import 'package:moxxmpp/src/types/result.dart';
 
-typedef Sasl2FeaturesReceivedCallback = Future<List<XMLNode>> Function(XMLNode);
-
+/// A special type of [XmppFeatureNegotiatorBase] that is aware of SASL2.
 abstract class Sasl2FeatureNegotiator extends XmppFeatureNegotiatorBase {
   Sasl2FeatureNegotiator(
-    int priority,
-    bool sendStreamHeaderWhenDone,
-    String negotiatingXmlns,
-    String id,
-  ) : super(priority, sendStreamHeaderWhenDone, negotiatingXmlns, id);
+    super.priority,
+    super.sendStreamHeaderWhenDone,
+    super.negotiatingXmlns,
+    super.id,
+  );
 
   /// Called by the SASL2 negotiator when we received the SASL2 stream features
   /// [sasl2Features]. The return value is a list of XML elements that should be
@@ -26,10 +24,10 @@ abstract class Sasl2FeatureNegotiator extends XmppFeatureNegotiatorBase {
   Future<void> onSasl2Success(XMLNode response);
 }
 
+/// A special type of [SaslNegotiator] that is aware of SASL2.
 abstract class Sasl2AuthenticationNegotiator extends SaslNegotiator
     implements Sasl2FeatureNegotiator {
-  Sasl2AuthenticationNegotiator(int priority, String id, String mechanismName)
-      : super(priority, id, mechanismName);
+  Sasl2AuthenticationNegotiator(super.priority, super.id, super.mechanismName);
 
   /// Perform a SASL step with [input] as the already parsed input data. Returns
   /// the base64-encoded response data.
@@ -59,8 +57,10 @@ class UserAgent {
   final String? device;
 
   XMLNode toXml() {
-    assert(id != null || software != null || device != null,
-        'A completely empty user agent makes no sense');
+    assert(
+      id != null || software != null || device != null,
+      'A completely empty user agent makes no sense',
+    );
     return XMLNode(
       tag: 'user-agent',
       attributes: id != null
@@ -130,7 +130,8 @@ class Sasl2Negotiator extends XmppFeatureNegotiatorBase {
 
   @override
   Future<Result<NegotiatorState, NegotiatorError>> negotiate(
-      XMLNode nonza) async {
+    XMLNode nonza,
+  ) async {
     switch (_sasl2State) {
       case Sasl2State.idle:
         final sasl2 = nonza.firstTag('authentication', xmlns: sasl2Xmlns)!;