feat(xep): Implement negotiating PLAIN via SASL2

packages/moxxmpp/lib/src/connection.dart

@@ -253,6 +253,19 @@ class XmppConnection {
     }
   }
 
+  // Mark the current connection as authenticated.
+  void _setAuthenticated() {
+    _sendEvent(AuthenticationSuccessEvent());
+    _isAuthenticated = true;
+  }
+
+  /// Remove [feature] from the stream features we are currently negotiating.
+  void _removeNegotiatingFeature(String feature) {
+    _streamFeatures.removeWhere((node) {
+      return node.attributes['xmlns'] == feature;
+    });
+  }
+
   /// Register a list of negotiator with the connection.
   Future<void> registerFeatureNegotiators(
       List<XmppFeatureNegotiatorBase> negotiators) async {
@@ -268,6 +281,8 @@ class XmppConnection {
           () => _connectionSettings.jid.withResource(_resource),
           () => _socket,
           () => _isAuthenticated,
+          _setAuthenticated,
+          _removeNegotiatingFeature,
         ),
       );
       _featureNegotiators[negotiator.id] = negotiator;
@@ -900,10 +915,7 @@ class XmppConnection {
           _streamFeatures.clear();
           _sendStreamHeader();
         } else {
-          _streamFeatures.removeWhere((node) {
+          _removeNegotiatingFeature(_currentNegotiator!.negotiatingXmlns);
-            return node.attributes['xmlns'] ==
-                _currentNegotiator!.negotiatingXmlns;
-          });
           _currentNegotiator = null;
 
           if (_isMandatoryNegotiationDone(_streamFeatures) &&
@@ -1024,11 +1036,6 @@ class XmppConnection {
 
       _log.finest('Resetting _serverFeatures');
       _serverFeatures.clear();
-    } else if (event is AuthenticationSuccessEvent) {
-      _log.finest(
-        'Received AuthenticationSuccessEvent. Setting _isAuthenticated to true',
-      );
-      _isAuthenticated = true;
     }
 
     for (final manager in _xmppManagers.values) {

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

@@ -35,6 +35,8 @@ class NegotiatorAttributes {
     this.getFullJID,
     this.getSocket,
     this.isAuthenticated,
+    this.setAuthenticated,
+    this.removeNegotiatingFeature,
   );
 
   /// Sends the nonza nonza and optionally redacts it in logs if redact is not null.
@@ -61,6 +63,13 @@ class NegotiatorAttributes {
 
   /// Returns true if the stream is authenticated. Returns false if not.
   final bool Function() isAuthenticated;
+
+  /// Sets the authentication state of the connection to true.
+  final void Function() setAuthenticated;
+
+  /// Remove a stream feature from our internal cache. This is useful for when you
+  /// negotiated a feature for another negotiator, like SASL2.
+  final void Function(String) removeNegotiatingFeature;
 }
 
 abstract class XmppFeatureNegotiatorBase {

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

@@ -11,14 +11,14 @@ import 'package:moxxmpp/src/stringxml.dart';
 import 'package:moxxmpp/src/types/result.dart';
 
 class SaslPlainAuthNonza extends SaslAuthNonza {
-  SaslPlainAuthNonza(String username, String password)
+  SaslPlainAuthNonza(String data)
       : super(
           'PLAIN',
-          base64.encode(utf8.encode('\u0000$username\u0000$password')),
+          data,
         );
 }
 
-class SaslPlainNegotiator extends SaslNegotiator {
+class SaslPlainNegotiator extends Sasl2AuthenticationNegotiator {
   SaslPlainNegotiator()
       : _authSent = false,
         _log = Logger('SaslPlainNegotiator'),
@@ -48,10 +48,10 @@ class SaslPlainNegotiator extends SaslNegotiator {
     XMLNode nonza,
   ) async {
     if (!_authSent) {
-      final settings = attributes.getConnectionSettings();
+      final data = await getRawStep('');
       attributes.sendNonza(
-        SaslPlainAuthNonza(settings.jid.local, settings.password),
+        SaslPlainAuthNonza(data),
-        redact: SaslPlainAuthNonza('******', '******').toXml(),
+        redact: SaslPlainAuthNonza('******').toXml(),
       );
       _authSent = true;
       return const Result(NegotiatorState.ready);
@@ -59,6 +59,7 @@ class SaslPlainNegotiator extends SaslNegotiator {
       final tag = nonza.tag;
       if (tag == 'success') {
         await attributes.sendEvent(AuthenticationSuccessEvent());
+        attributes.setAuthenticated();
         return const Result(NegotiatorState.done);
       } else {
         // We assume it's a <failure/>
@@ -84,4 +85,21 @@ class SaslPlainNegotiator extends SaslNegotiator {
         .getNegotiatorById<Sasl2Negotiator>(sasl2Negotiator)
         ?.registerSaslNegotiator(this);
   }
+
+  @override
+  Future<String> getRawStep(String input) async {
+    final settings = attributes.getConnectionSettings();
+    return base64.encode(
+        utf8.encode('\u0000${settings.jid.local}\u0000${settings.password}'));
+  }
+
+  @override
+  Future<void> onSasl2Success(XMLNode response) async {
+    state = NegotiatorState.done;
+  }
+
+  @override
+  Future<List<XMLNode>> onSasl2FeaturesReceived(XMLNode sasl2Features) async {
+    return [];
+  }
 }

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

@@ -299,7 +299,7 @@ class SaslScramNegotiator extends SaslNegotiator {
           );
         }
 
-        await attributes.sendEvent(AuthenticationSuccessEvent());
+        attributes.setAuthenticated();
         return const Result(NegotiatorState.done);
       case ScramState.error:
         return Result(

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

@@ -1,3 +1,4 @@
+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';
@@ -7,6 +8,34 @@ import 'package:moxxmpp/src/types/result.dart';
 
 typedef Sasl2FeaturesReceivedCallback = Future<List<XMLNode>> Function(XMLNode);
 
+abstract class Sasl2FeatureNegotiator extends XmppFeatureNegotiatorBase {
+  Sasl2FeatureNegotiator(
+    int priority,
+    bool sendStreamHeaderWhenDone,
+    String negotiatingXmlns,
+    String id,
+  ) : super(priority, sendStreamHeaderWhenDone, negotiatingXmlns, 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
+  /// added to the SASL2 <authenticate /> nonza.
+  Future<List<XMLNode>> onSasl2FeaturesReceived(XMLNode sasl2Features);
+
+  /// Called by the SASL2 negotiator when the SASL2 negotiations are done. [response]
+  /// is the entire response nonza.
+  Future<void> onSasl2Success(XMLNode response);
+}
+
+abstract class Sasl2AuthenticationNegotiator extends SaslNegotiator
+    implements Sasl2FeatureNegotiator {
+  Sasl2AuthenticationNegotiator(int priority, String id, String mechanismName)
+      : super(priority, id, mechanismName);
+
+  /// Perform a SASL step with [input] as the already parsed input data. Returns
+  /// the base64-encoded response data.
+  Future<String> getRawStep(String input);
+}
+
 class NoSASLMechanismSelectedError extends NegotiatorError {
   @override
   bool isRecoverable() => false;
@@ -58,6 +87,8 @@ class UserAgent {
 enum Sasl2State {
   // No request has been sent yet.
   idle,
+  // We have sent the <authenticate /> nonza.
+  authenticateSent,
 }
 
 /// A negotiator that implements XEP-0388 SASL2. Alone, it does nothing. Has to be
@@ -72,28 +103,29 @@ class Sasl2Negotiator extends XmppFeatureNegotiatorBase {
 
   /// List of callbacks that are registered against us. Will be called once we get
   /// SASL2 features.
-  final List<Sasl2FeaturesReceivedCallback> _featureCallbacks =
+  final List<Sasl2FeatureNegotiator> _featureNegotiators =
-      List<Sasl2FeaturesReceivedCallback>.empty(growable: true);
+      List<Sasl2FeatureNegotiator>.empty(growable: true);
 
   /// List of SASL negotiators, sorted by their priority. The higher the priority, the
   /// lower its index.
-  final List<SaslNegotiator> _saslNegotiators =
+  final List<Sasl2AuthenticationNegotiator> _saslNegotiators =
-      List<SaslNegotiator>.empty(growable: true);
+      List<Sasl2AuthenticationNegotiator>.empty(growable: true);
 
   /// The state the SASL2 negotiator is currently in.
   Sasl2State _sasl2State = Sasl2State.idle;
 
   /// The SASL negotiator that will negotiate authentication.
-  SaslNegotiator? _currentSaslNegotiator;
+  Sasl2AuthenticationNegotiator? _currentSaslNegotiator;
 
-  void registerSaslNegotiator(SaslNegotiator negotiator) {
+  void registerSaslNegotiator(Sasl2AuthenticationNegotiator negotiator) {
+    _featureNegotiators.add(negotiator);
     _saslNegotiators
       ..add(negotiator)
       ..sort((a, b) => b.priority.compareTo(a.priority));
   }
 
-  void registerFeaturesCallback(Sasl2FeaturesReceivedCallback callback) {
+  void registerNegotiator(Sasl2FeatureNegotiator negotiator) {
-    _featureCallbacks.add(callback);
+    _featureNegotiators.add(negotiator);
   }
 
   @override
@@ -121,9 +153,9 @@ class Sasl2Negotiator extends XmppFeatureNegotiatorBase {
 
         // Collect additional data by interested negotiators
         final children = List<XMLNode>.empty(growable: true);
-        for (final callback in _featureCallbacks) {
+        for (final negotiator in _featureNegotiators) {
           children.addAll(
-            await callback(sasl2),
+            await negotiator.onSasl2FeaturesReceived(sasl2),
           );
         }
 
@@ -136,16 +168,29 @@ class Sasl2Negotiator extends XmppFeatureNegotiatorBase {
           },
           children: [
             if (userAgent != null) userAgent!.toXml(),
-
-            // TODO: Get the initial response
             XMLNode(
               tag: 'initial-response',
+              text: await _currentSaslNegotiator!.getRawStep(''),
             ),
             ...children,
           ],
         );
+
+        _sasl2State = Sasl2State.authenticateSent;
         attributes.sendNonza(authenticate);
         return const Result(NegotiatorState.ready);
+      case Sasl2State.authenticateSent:
+        if (nonza.tag == 'success') {
+          // Tell the dependent negotiators about the result
+          for (final negotiator in _featureNegotiators) {
+            await negotiator.onSasl2Success(nonza);
+          }
+
+          // We're done
+          attributes.setAuthenticated();
+          attributes.removeNegotiatingFeature(saslXmlns);
+          return const Result(NegotiatorState.done);
+        }
     }
 
     return const Result(NegotiatorState.ready);

packages/moxxmpp/test/sasl/scram_test.dart

@@ -57,6 +57,8 @@ void main() {
           () => JID.fromString('user@server'),
           () => fakeSocket,
           () => false,
+          () {},
+          (_) {},
         ),
       );
 
@@ -150,6 +152,8 @@ void main() {
           () => JID.fromString('user@server'),
           () => fakeSocket,
           () => false,
+          () {},
+          (_) {},
         ),
       );
 
@@ -198,6 +202,8 @@ void main() {
           () => JID.fromString('user@server'),
           () => fakeSocket,
           () => false,
+          () {},
+          (_) {},
         ),
       );
 
@@ -236,6 +242,8 @@ void main() {
           () => JID.fromString('user@server'),
           () => fakeSocket,
           () => false,
+          () {},
+          (_) {},
         ),
       );
 
@@ -277,6 +285,8 @@ void main() {
           () => JID.fromString('user@server'),
           () => fakeSocket,
           () => false,
+          () {},
+          (_) {},
         ),
       );
 

packages/moxxmpp/test/xeps/xep_0198_test.dart

@@ -391,10 +391,10 @@ void main() {
           "<enable xmlns='urn:xmpp:sm:3' resume='true' />",
           '<enabled xmlns="urn:xmpp:sm:3" id="some-long-sm-id" resume="true" />',
         ),
-        // StringExpectation(
+        StringExpectation(
-        //   "<presence xmlns='jabber:client' from='polynomdivision@test.server/MU29eEZn'><show>chat</show></presence>",
+          "<presence xmlns='jabber:client' from='polynomdivision@test.server/MU29eEZn'><show>chat</show></presence>",
-        //   '<iq type="result" />',
+          '<iq type="result" />',
-        // ),
+        ),
         StanzaExpectation(
           "<iq to='user@example.com' type='get' id='a' xmlns='jabber:client' />",
           "<iq from='user@example.com' type='result' id='a' />",
@@ -450,7 +450,7 @@ void main() {
         addFrom: StanzaFromType.none,
       );
 
-      expect(sm.state.s2c, /*2*/ 1);
+      expect(sm.state.s2c, 2);
     });
   });
 

packages/moxxmpp/test/xeps/xep_0388_test.dart

@@ -24,11 +24,26 @@ void main() {
     <authentication xmlns='urn:xmpp:sasl:2'>
       <mechanism>PLAIN</mechanism>
     </authentication>
+    <bind xmlns="urn:ietf:params:xml:ns:xmpp-bind">
+      <required/>
+    </bind>
   </stream:features>''',
       ),
       StanzaExpectation(
         "<authenticate xmlns='urn:xmpp:sasl:2' mechanism='PLAIN'><user-agent id='d4565fa7-4d72-4749-b3d3-740edbf87770'><software>moxxmpp</software><device>PapaTutuWawa's awesome device</device></user-agent><initial-response>AHBvbHlub21kaXZpc2lvbgBhYWFh</initial-response></authenticate>",
-        '',
+        '''
+<success xmlns='urn:xmpp:sasl:2'>
+  <authorization-identifier>polynomdivision@test.server</authorization-identifier>
+</success>
+        ''',
+      ),
+      StanzaExpectation(
+        "<iq xmlns='jabber:client' type='set' id='aaaa'><bind xmlns='urn:ietf:params:xml:ns:xmpp-bind' /></iq>",
+        '''
+'<iq xmlns="jabber:client" type="result" id="a"><bind xmlns="urn:ietf:params:xml:ns:xmpp-bind"><jid>polynomdivision@test.server/MU29eEZn</jid></bind></iq>',
+        ''',
+        adjustId: true,
+        ignoreId: true,
       ),
     ]);
     final conn = XmppConnection(