driveChannel method

Future<bool> driveChannel(Channel sock)

Implementation

Future<bool> driveChannel(Channel sock) async {
  //
  //  0. check channel state
  //
  ChannelStatus cs = sock.status;
  if (cs == ChannelStatus.init) {
    // preparing
    return false;
  } else if (cs == ChannelStatus.closed) {
    // finished
    return false;
  }
  // cs == opened
  // cs == alive
  Uint8List? data;
  SocketAddress? remote;
  SocketAddress? local;
  //
  //  1. try to receive
  //
  try {
    Pair<Uint8List?, SocketAddress?> pair = await sock.receive(MSS);
    data = pair.first;
    remote = pair.second;
  } on IOException catch (e) {
    // print(e);
    remote = sock.remoteAddress;
    local = sock.localAddress;
    ConnectionDelegate? gate = delegate;
    Channel? cached;
    if (gate == null || remote == null) {
      // UDP channel may not connected,
      // so no connection for it
      cached = removeChannel(sock, remote: remote, local: local);
    } else {
      // remove channel and callback with connection
      Connection? conn = getConnection(remote: remote, local: local);
      cached = removeChannel(sock, remote: remote, local: local);
      if (conn != null) {
        await gate.onConnectionError(IOError(e), conn);
      }
    }
    // close removed/error channels
    if (cached == null || identical(cached, sock)) {} else {
      await closeChannel(cached);
    }
    await closeChannel(sock);
    return false;
  }
  if (remote == null || data == null) {
    // received nothing
    return false;
  } else {
    assert(data.isNotEmpty, 'data should not empty: $remote');
    local = sock.localAddress;
  }
  //
  //  2. get connection for processing received data
  //
  Connection? conn = await connect(remote: remote, local: local);
  if (conn != null) {
    await conn.onReceivedData(data);
  }
  return true;
}