twonly-app/lib/src/services/signal/session.signal.dart

import 'dart:typed_data';

import 'package:libsignal_protocol_dart/libsignal_protocol_dart.dart';
import 'package:twonly/locator.dart';
import 'package:twonly/src/model/protobuf/api/websocket/server_to_client.pb.dart';
import 'package:twonly/src/services/signal/consts.signal.dart';
import 'package:twonly/src/services/signal/protocol_state.signal.dart';
import 'package:twonly/src/services/signal/utils.signal.dart';
import 'package:twonly/src/utils/log.dart';

Future<bool> processSignalUserData(Response_UserData userData) async {
  return lockingSignalProtocol.protect(() async {
    final SignalProtocolStore? signalStore = await getSignalStore();

    if (signalStore == null) {
      return false;
    }

    final targetAddress = getSignalAddress(userData.userId.toInt());

    final sessionBuilder = SessionBuilder.fromSignalStore(
      signalStore,
      targetAddress,
    );

    ECPublicKey? tempPrePublicKey;
    int? tempPreKeyId;

    if (userData.prekeys.isNotEmpty) {
      tempPrePublicKey = Curve.decodePoint(
        DjbECPublicKey(
          Uint8List.fromList(userData.prekeys.first.prekey),
        ).serialize(),
        1,
      );
      tempPreKeyId = userData.prekeys.first.id.toInt();
    }

    final tempSignedPreKeyId = userData.signedPrekeyId.toInt();

    final tempSignedPreKeyPublic = Curve.decodePoint(
      DjbECPublicKey(Uint8List.fromList(userData.signedPrekey)).serialize(),
      1,
    );

    final tempSignedPreKeySignature = Uint8List.fromList(
      userData.signedPrekeySignature,
    );

    final tempIdentityKey = IdentityKey(
      Curve.decodePoint(
        DjbECPublicKey(
          Uint8List.fromList(userData.publicIdentityKey),
        ).serialize(),
        1,
      ),
    );

    final preKeyBundle = PreKeyBundle(
      userData.registrationId.toInt(),
      defaultDeviceId,
      tempPreKeyId,
      tempPrePublicKey,
      tempSignedPreKeyId,
      tempSignedPreKeyPublic,
      tempSignedPreKeySignature,
      tempIdentityKey,
    );

    try {
      await sessionBuilder.processPreKeyBundle(preKeyBundle);
      return true;
    } catch (e) {
      Log.error('could not process pre key bundle: $e');
      return false;
    }
  });
}

Future<Uint8List?> getPublicKeyFromContact(int contactId) async {
  final signalStore = await getSignalStore();
  if (signalStore == null) return null;
  try {
    final targetIdentity = await signalStore.getIdentity(
      SignalProtocolAddress(
        contactId.toString(),
        defaultDeviceId,
      ),
    );
    if (targetIdentity != null) {
      return targetIdentity.publicKey.serialize();
    }
    return null;
  } catch (e) {
    return null;
  }
}

Future<bool> handleSessionResync(int fromUserId) async {
  final userData = await apiService.getUserById(fromUserId);
  if (userData != null) {
    Log.info('Got new session data from the server to re-sync the session');
    return processSignalUserData(userData);
  }
  Log.info('Could not download userdata from the server.');
  return false;
}