@homebridge/dbus-native/index.js

D-bus protocol implementation in native javascript

// dbus.freedesktop.org/doc/dbus-specification.html

const EventEmitter = require('events').EventEmitter;
const net = require('net');

const constants = require('./lib/constants');
const message = require('./lib/message');
const clientHandshake = require('./lib/handshake');
const serverHandshake = require('./lib/server-handshake');
const MessageBus = require('./lib/bus');
const server = require('./lib/server');

function createStream(opts) {
  if (opts.stream) return opts.stream;
  var host = opts.host;
  var port = opts.port;
  var socket = opts.socket;
  if (socket) return net.createConnection(socket);
  if (port) return net.createConnection(port, host);

  var busAddress = opts.busAddress || process.env.DBUS_SESSION_BUS_ADDRESS;
  if (!busAddress) throw new Error('unknown bus address');

  var addresses = busAddress.split(';');
  for (var i = 0; i < addresses.length; ++i) {
    var address = addresses[i];
    var familyParams = address.split(':');
    var family = familyParams[0];
    var params = {};
    familyParams[1].split(',').map(function (p) {
      var keyVal = p.split('=');
      params[keyVal[0]] = keyVal[1];
    });

    try {
      switch (family.toLowerCase()) {
        case 'tcp':
          host = params.host || 'localhost';
          port = params.port;
          return net.createConnection(port, host);
        case 'unix':
          if (params.socket) return net.createConnection(params.socket);
          if (params.abstract) {
            var abs = require('abstract-socket');
            return abs.connect('\u0000' + params.abstract);
          }
          if (params.path) return net.createConnection(params.path);
          throw new Error(
            "not enough parameters for 'unix' connection - you need to specify 'socket' or 'abstract' or 'path' parameter"
          );
        case 'unixexec':
          var eventStream = require('event-stream');
          var spawn = require('child_process').spawn;
          var args = [];
          for (var n = 1; params['arg' + n]; n++) args.push(params['arg' + n]);
          var child = spawn(params.path, args);

          return eventStream.duplex(child.stdin, child.stdout);
        default:
          throw new Error('unknown address type:' + family);
      }
    } catch (e) {
      if (i < addresses.length - 1) {
        console.warn(e.message);
        continue;
      } else {
        throw e;
      }
    }
  }
}

function createConnection(opts) {
  var self = new EventEmitter();
  if (!opts) opts = {};
  var stream = (self.stream = createStream(opts));
  stream.setNoDelay();

  stream.on('error', function (err) {
    // forward network and stream errors
    self.emit('error', err);
  });

  stream.on('end', function () {
    self.emit('end');
    self.message = function () {
      console.warn("Didn't write bytes to closed stream");
    };
  });

  self.end = function () {
    stream.end();
    return self;
  };

  var handshake = opts.server ? serverHandshake : clientHandshake;
  handshake(stream, opts, function (error, guid) {
    if (error) {
      return self.emit('error', error);
    }
    self.guid = guid;
    self.emit('connect');
    message.unmarshalMessages(
      stream,
      function (message) {
        self.emit('message', message);
      },
      opts
    );
  });

  self._messages = [];

  // pre-connect version, buffers all messages. replaced after connect
  self.message = function (msg) {
    self._messages.push(msg);
  };

  self.once('connect', function () {
    self.state = 'connected';
    for (var i = 0; i < self._messages.length; ++i) {
      stream.write(message.marshall(self._messages[i]));
    }
    self._messages.length = 0;

    // no need to buffer once connected
    self.message = function (msg) {
      stream.write(message.marshall(msg));
    };
  });

  return self;
}

module.exports.createClient = function (params) {
  var connection = createConnection(params || {});
  return new MessageBus(connection, params || {});
};

module.exports.systemBus = function () {
  return module.exports.createClient({
    busAddress:
      process.env.DBUS_SYSTEM_BUS_ADDRESS ||
      'unix:path=/var/run/dbus/system_bus_socket'
  });
};

module.exports.sessionBus = function (opts) {
  return module.exports.createClient(opts);
};

module.exports.messageType = constants.messageType;
module.exports.createConnection = createConnection;

module.exports.createServer = server.createServer;