peerjs/lib/peer.js

var util = require('./util');
var EventEmitter = require('eventemitter3');
var Socket = require('./socket');
var MediaConnection = require('./mediaconnection');
var DataConnection = require('./dataconnection');

/**
 * A peer who can initiate connections with other peers.
 */
function Peer(id, options) {
  if (!(this instanceof Peer)) return new Peer(id, options);
  EventEmitter.call(this);

  // Deal with overloading
  if (id && id.constructor == Object) {
    options = id;
    id = undefined;
  } else if (id) {
    // Ensure id is a string
    id = id.toString();
  }
  //

  // Configurize options
  options = util.extend({
    debug: 0, // 1: Errors, 2: Warnings, 3: All logs
    host: util.CLOUD_HOST,
    port: util.CLOUD_PORT,
    key: 'peerjs',
    path: '/',
    token: util.randomToken(),
    config: util.defaultConfig
  }, options);
  this.options = options;
  // Detect relative URL host.
  if (options.host === '/') {
    options.host = window.location.hostname;
  }
  // Set path correctly.
  if (options.path[0] !== '/') {
    options.path = '/' + options.path;
  }
  if (options.path[options.path.length - 1] !== '/') {
    options.path += '/';
  }

  // Set whether we use SSL to same as current host
  if (options.secure === undefined && options.host !== util.CLOUD_HOST) {
    options.secure = util.isSecure();
  }
  // Set a custom log function if present
  if (options.logFunction) {
    util.setLogFunction(options.logFunction);
  }
  util.setLogLevel(options.debug);
  //

  // Sanity checks
  // Ensure WebRTC supported
  if (!util.supports.audioVideo && !util.supports.data ) {
    this._delayedAbort('browser-incompatible', 'The current browser does not support WebRTC');
    return;
  }
  // Ensure alphanumeric id
  if (!util.validateId(id)) {
    this._delayedAbort('invalid-id', 'ID "' + id + '" is invalid');
    return;
  }
  // Ensure valid key
  if (!util.validateKey(options.key)) {
    this._delayedAbort('invalid-key', 'API KEY "' + options.key + '" is invalid');
    return;
  }
  // Ensure not using unsecure cloud server on SSL page
  if (options.secure && options.host === '0.peerjs.com') {
    this._delayedAbort('ssl-unavailable',
      'The cloud server currently does not support HTTPS. Please run your own PeerServer to use HTTPS.');
    return;
  }
  //

  // States.
  this.destroyed = false; // Connections have been killed
  this.disconnected = false; // Connection to PeerServer killed but P2P connections still active
  this.open = false; // Sockets and such are not yet open.
  //

  // References
  this.connections = {}; // DataConnections for this peer.
  this._lostMessages = {}; // src => [list of messages]
  //

  // Start the server connection
  this._initializeServerConnection();
  if (id) {
    this._initialize(id);
  } else {
    this._retrieveId();
  }
  //
}

util.inherits(Peer, EventEmitter);

// Initialize the 'socket' (which is actually a mix of XHR streaming and
// websockets.)
Peer.prototype._initializeServerConnection = function() {
  var self = this;
  this.socket = new Socket(this.options.secure, this.options.host, this.options.port, this.options.path, this.options.key);
  this.socket.on('message', function(data) {
    self._handleMessage(data);
  });
  this.socket.on('error', function(error) {
    self._abort('socket-error', error);
  });
  this.socket.on('disconnected', function() {
    // If we haven't explicitly disconnected, emit error and disconnect.
    if (!self.disconnected) {
      self.emitError('network', 'Lost connection to server.');
      self.disconnect();
    }
  });
  this.socket.on('close', function() {
    // If we haven't explicitly disconnected, emit error.
    if (!self.disconnected) {
      self._abort('socket-closed', 'Underlying socket is already closed.');
    }
  });
};

/** Get a unique ID from the server via XHR. */
Peer.prototype._retrieveId = function(cb) {
  var self = this;
  var http = new XMLHttpRequest();
  var protocol = this.options.secure ? 'https://' : 'http://';
  var url = protocol + this.options.host + ':' + this.options.port +
    this.options.path + this.options.key + '/id';
  var queryString = '?ts=' + new Date().getTime() + '' + Math.random();
  url += queryString;

  // If there's no ID we need to wait for one before trying to init socket.
  http.open('get', url, true);
  http.onerror = function(e) {
    util.error('Error retrieving ID', e);
    var pathError = '';
    if (self.options.path === '/' && self.options.host !== util.CLOUD_HOST) {
      pathError = ' If you passed in a `path` to your self-hosted PeerServer, ' +
        'you\'ll also need to pass in that same path when creating a new ' +
        'Peer.';
    }
    self._abort('server-error', 'Could not get an ID from the server.' + pathError);
  };
  http.onreadystatechange = function() {
    if (http.readyState !== 4) {
      return;
    }
    if (http.status !== 200) {
      http.onerror();
      return;
    }
    self._initialize(http.responseText);
  };
  http.send(null);
};

/** Initialize a connection with the server. */
Peer.prototype._initialize = function(id) {
  this.id = id;
  this.socket.start(this.id, this.options.token);
};

/** Handles messages from the server. */
Peer.prototype._handleMessage = function(message) {
  var type = message.type;
  var payload = message.payload;
  var peer = message.src;

  switch (type) {
    case 'OPEN': // The connection to the server is open.
      this.emit('open', this.id);
      this.open = true;
      break;
    case 'ERROR': // Server error.
      this._abort('server-error', payload.msg);
      break;
    case 'ID-TAKEN': // The selected ID is taken.
      this._abort('unavailable-id', 'ID `' + this.id + '` is taken');
      break;
    case 'INVALID-KEY': // The given API key cannot be found.
      this._abort('invalid-key', 'API KEY "' + this.options.key + '" is invalid');
      break;

    //
    case 'LEAVE': // Another peer has closed its connection to this peer.
      util.log('Received leave message from', peer);
      this._cleanupPeer(peer);
      break;

    case 'EXPIRE': // The offer sent to a peer has expired without response.
      this.emitError('peer-unavailable', 'Could not connect to peer ' + peer);
      break;
    case 'OFFER': // we should consider switching this to CALL/CONNECT, but this is the least breaking option.
      var connectionId = payload.connectionId;
      var connection = this.getConnection(peer, connectionId);

      if (connection) {
        util.warn('Offer received for existing Connection ID:', connectionId);
        //connection.handleMessage(message);
      } else {
        // Create a new connection.
        if (payload.type === 'media') {
          connection = new MediaConnection(peer, this, {
            connectionId: connectionId,
            _payload: payload,
            metadata: payload.metadata
          });
          this._addConnection(peer, connection);
          this.emit('call', connection);
        } else if (payload.type === 'data') {
          connection = new DataConnection(peer, this, {
            connectionId: connectionId,
            _payload: payload,
            metadata: payload.metadata,
            label: payload.label,
            serialization: payload.serialization,
            reliable: payload.reliable
          });
          this._addConnection(peer, connection);
          this.emit('connection', connection);
        } else {
          util.warn('Received malformed connection type:', payload.type);
          return;
        }
        // Find messages.
        var messages = this._getMessages(connectionId);
        for (var i = 0, ii = messages.length; i < ii; i += 1) {
          connection.handleMessage(messages[i]);
        }
      }
      break;
    default:
      if (!payload) {
        util.warn('You received a malformed message from ' + peer + ' of type ' + type);
        return;
      }

      var id = payload.connectionId;
      connection = this.getConnection(peer, id);

      if (connection && connection.pc) {
        // Pass it on.
        connection.handleMessage(message);
      } else if (id) {
        // Store for possible later use
        this._storeMessage(id, message);
      } else {
        util.warn('You received an unrecognized message:', message);
      }
      break;
  }
};

/** Stores messages without a set up connection, to be claimed later. */
Peer.prototype._storeMessage = function(connectionId, message) {
  if (!this._lostMessages[connectionId]) {
    this._lostMessages[connectionId] = [];
  }
  this._lostMessages[connectionId].push(message);
};

/** Retrieve messages from lost message store */
Peer.prototype._getMessages = function(connectionId) {
  var messages = this._lostMessages[connectionId];
  if (messages) {
    delete this._lostMessages[connectionId];
    return messages;
  } else {
    return [];
  }
};

/**
 * Returns a DataConnection to the specified peer. See documentation for a
 * complete list of options.
 */
Peer.prototype.connect = function(peer, options) {
  if (this.disconnected) {
    util.warn('You cannot connect to a new Peer because you called ' +
      '.disconnect() on this Peer and ended your connection with the ' +
      'server. You can create a new Peer to reconnect, or call reconnect ' +
      'on this peer if you believe its ID to still be available.');
    this.emitError('disconnected', 'Cannot connect to new Peer after disconnecting from server.');
    return;
  }
  var connection = new DataConnection(peer, this, options);
  this._addConnection(peer, connection);
  return connection;
};

/**
 * Returns a MediaConnection to the specified peer. See documentation for a
 * complete list of options.
 */
Peer.prototype.call = function(peer, stream, options) {
  if (this.disconnected) {
    util.warn('You cannot connect to a new Peer because you called ' +
      '.disconnect() on this Peer and ended your connection with the ' +
      'server. You can create a new Peer to reconnect.');
    this.emitError('disconnected', 'Cannot connect to new Peer after disconnecting from server.');
    return;
  }
  if (!stream) {
    util.error('To call a peer, you must provide a stream from your browser\'s `getUserMedia`.');
    return;
  }
  options = options || {};
  options._stream = stream;
  var call = new MediaConnection(peer, this, options);
  this._addConnection(peer, call);
  return call;
};

/** Add a data/media connection to this peer. */
Peer.prototype._addConnection = function(peer, connection) {
  if (!this.connections[peer]) {
    this.connections[peer] = [];
  }
  this.connections[peer].push(connection);
};

/** Retrieve a data/media connection for this peer. */
Peer.prototype.getConnection = function(peer, id) {
  var connections = this.connections[peer];
  if (!connections) {
    return null;
  }
  for (var i = 0, ii = connections.length; i < ii; i++) {
    if (connections[i].id === id) {
      return connections[i];
    }
  }
  return null;
};

Peer.prototype._delayedAbort = function(type, message) {
  var self = this;
  util.setZeroTimeout(function(){
    self._abort(type, message);
  });
};

/**
 * Destroys the Peer and emits an error message.
 * The Peer is not destroyed if it's in a disconnected state, in which case
 * it retains its disconnected state and its existing connections.
 */
Peer.prototype._abort = function(type, message) {
  util.error('Aborting!');
  if (!this._lastServerId) {
    this.destroy();
  } else {
    this.disconnect();
  }
  this.emitError(type, message);
};

/** Emits a typed error message. */
Peer.prototype.emitError = function(type, err) {
  util.error('Error:', err);
  if (typeof err === 'string') {
    err = new Error(err);
  }
  err.type = type;
  this.emit('error', err);
};

/**
 * Destroys the Peer: closes all active connections as well as the connection
 *  to the server.
 * Warning: The peer can no longer create or accept connections after being
 *  destroyed.
 */
Peer.prototype.destroy = function() {
  if (!this.destroyed) {
    this._cleanup();
    this.disconnect();
    this.destroyed = true;
  }
};


/** Disconnects every connection on this peer. */
Peer.prototype._cleanup = function() {
  if (this.connections) {
    var peers = Object.keys(this.connections);
    for (var i = 0, ii = peers.length; i < ii; i++) {
      this._cleanupPeer(peers[i]);
    }
  }
  this.emit('close');
};

/** Closes all connections to this peer. */
Peer.prototype._cleanupPeer = function(peer) {
  var connections = this.connections[peer];
  for (var j = 0, jj = connections.length; j < jj; j += 1) {
    connections[j].close();
  }
};

/**
 * Disconnects the Peer's connection to the PeerServer. Does not close any
 *  active connections.
 * Warning: The peer can no longer create or accept connections after being
 *  disconnected. It also cannot reconnect to the server.
 */
Peer.prototype.disconnect = function() {
  var self = this;
  util.setZeroTimeout(function(){
    if (!self.disconnected) {
      self.disconnected = true;
      self.open = false;
      if (self.socket) {
        self.socket.close();
      }
      self.emit('disconnected', self.id);
      self._lastServerId = self.id;
      self.id = null;
    }
  });
};

/** Attempts to reconnect with the same ID. */
Peer.prototype.reconnect = function() {
  if (this.disconnected && !this.destroyed) {
    util.log('Attempting reconnection to server with ID ' + this._lastServerId);
    this.disconnected = false;
    this._initializeServerConnection();
    this._initialize(this._lastServerId);
  } else if (this.destroyed) {
    throw new Error('This peer cannot reconnect to the server. It has already been destroyed.');
  } else if (!this.disconnected && !this.open) {
    // Do nothing. We're still connecting the first time.
    util.error('In a hurry? We\'re still trying to make the initial connection!');
  } else {
    throw new Error('Peer ' + this.id + ' cannot reconnect because it is not disconnected from the server!');
  }
};

/**
 * Get a list of available peer IDs. If you're running your own server, you'll
 * want to set allow_discovery: true in the PeerServer options. If you're using
 * the cloud server, email team@peerjs.com to get the functionality enabled for
 * your key.
 */
Peer.prototype.listAllPeers = function(cb) {
  cb = cb || function() {};
  var self = this;
  var http = new XMLHttpRequest();
  var protocol = this.options.secure ? 'https://' : 'http://';
  var url = protocol + this.options.host + ':' + this.options.port +
    this.options.path + this.options.key + '/peers';
  var queryString = '?ts=' + new Date().getTime() + '' + Math.random();
  url += queryString;

  // If there's no ID we need to wait for one before trying to init socket.
  http.open('get', url, true);
  http.onerror = function(e) {
    self._abort('server-error', 'Could not get peers from the server.');
    cb([]);
  };
  http.onreadystatechange = function() {
    if (http.readyState !== 4) {
      return;
    }
    if (http.status === 401) {
      var helpfulError = '';
      if (self.options.host !== util.CLOUD_HOST) {
        helpfulError = 'It looks like you\'re using the cloud server. You can email ' +
          'team@peerjs.com to enable peer listing for your API key.';
      } else {
        helpfulError = 'You need to enable `allow_discovery` on your self-hosted ' +
          'PeerServer to use this feature.';
      }
      cb([]);
      throw new Error('It doesn\'t look like you have permission to list peers IDs. ' + helpfulError);
    } else if (http.status !== 200) {
      cb([]);
    } else {
      cb(JSON.parse(http.responseText));
    }
  };
  http.send(null);
};

module.exports = Peer;