negotiate method

  1. @override
Future<Result<NegotiatorState, NegotiatorError>> negotiate(
  1. XMLNode nonza
)
override

Called with the currently received nonza nonza when the negotiator is active. If the negotiator is just elected to be the next one, then nonza is equal to the <stream:features /> nonza.

Returns the next state of the negotiator. If done or retryLater is selected, then negotiator won't be called again. If retryLater is returned, then the negotiator must switch some internal state to prevent getting matched immediately again. If ready is returned, then the negotiator indicates that it is not done with negotiation.

Implementation

@override
Future<Result<NegotiatorState, NegotiatorError>> negotiate(
  XMLNode nonza,
) async {
  switch (_sasl2State) {
    case Sasl2State.idle:
      _sasl2Data = nonza.firstTag('authentication', xmlns: sasl2Xmlns);
      final mechanisms = XMLNode.xmlns(
        tag: 'mechanisms',
        xmlns: saslXmlns,
        children:
            _sasl2Data!.children.where((c) => c.tag == 'mechanism').toList(),
      );
      for (final negotiator in _saslNegotiators) {
        if (negotiator.matchesFeature([mechanisms])) {
          _currentSaslNegotiator = negotiator;
          _currentSaslNegotiator!.pickForSasl2();
          break;
        }
      }

      // We must have a SASL negotiator by now
      if (_currentSaslNegotiator == null) {
        return Result(NoSASLMechanismSelectedError());
      }

      // Collect additional data by interested negotiators
      final inline = _sasl2Data!.firstTag('inline');
      final children = List<XMLNode>.empty(growable: true);
      if (inline != null && inline.children.isNotEmpty) {
        for (final negotiator in _featureNegotiators) {
          if (negotiator.canInlineFeature(inline.children)) {
            _activeSasl2Negotiators.add(negotiator.id);
            children.addAll(
              await negotiator.onSasl2FeaturesReceived(_sasl2Data!),
            );
          }
        }
      }

      // Build the authenticate nonza
      final authenticate = XMLNode.xmlns(
        tag: 'authenticate',
        xmlns: sasl2Xmlns,
        attributes: {
          'mechanism': _currentSaslNegotiator!.mechanismName,
        },
        children: [
          XMLNode(
            tag: 'initial-response',
            text: await _currentSaslNegotiator!.getRawStep(''),
          ),
          if (userAgent != null) userAgent!.toXml(),
          ...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
        final negotiators = _featureNegotiators
            .where(
              (negotiator) => _activeSasl2Negotiators.contains(negotiator.id),
            )
            .toList()
          ..add(_currentSaslNegotiator!);
        for (final negotiator in negotiators) {
          final result = await negotiator.onSasl2Success(nonza);
          if (!result.isType<bool>()) {
            return Result(result.get<NegotiatorError>());
          }
        }

        // We're done
        attributes.setAuthenticated();
        attributes.removeNegotiatingFeature(saslXmlns);

        // Check if we also received a resource with the SASL2 success
        final jid = JID.fromString(
          nonza.firstTag('authorization-identifier')!.innerText(),
        );
        if (!jid.isBare()) {
          attributes.setResource(jid.resource);
        }

        return const Result(NegotiatorState.done);
      } else if (nonza.tag == 'challenge') {
        // We still have to negotiate
        final challenge = nonza.innerText();
        final response = XMLNode.xmlns(
          tag: 'response',
          xmlns: sasl2Xmlns,
          text: await _currentSaslNegotiator!.getRawStep(challenge),
        );
        attributes.sendNonza(response);
      } else if (nonza.tag == 'failure') {
        final negotiators = _featureNegotiators
            .where(
              (negotiator) => _activeSasl2Negotiators.contains(negotiator.id),
            )
            .toList()
          ..add(_currentSaslNegotiator!);
        for (final negotiator in negotiators) {
          await negotiator.onSasl2Failure(nonza);
        }

        // Check if we should retry and, if we should, reset the current
        // negotiator, this negotiator, and retry.
        if (_currentSaslNegotiator!.shouldRetrySasl()) {
          _currentSaslNegotiator!.reset();
          reset();
          return const Result(
            NegotiatorState.retryLater,
          );
        }

        return Result(
          SaslError.fromFailure(nonza),
        );
      }
  }

  return const Result(NegotiatorState.ready);
}