electron/lib/browser/rpc-server.js

'use strict';

const electron = require('electron');
const ipcMain = electron.ipcMain;
const objectsRegistry = require('./objects-registry');
const v8Util = process.atomBinding('v8_util');
const IDWeakMap = process.atomBinding('id_weak_map').IDWeakMap;

// The internal properties of Function.
const FUNCTION_PROPERTIES = [
  'length', 'name', 'arguments', 'caller', 'prototype',
];

// The remote functions in renderer processes.
// (webContentsId) => {id: Function}
let rendererFunctions = {};

// Return the description of object's members:
let getObjectMembers = function(object) {
  let names = Object.getOwnPropertyNames(object);
  // For Function, we should not override following properties even though they
  // are "own" properties.
  if (typeof object === 'function') {
    names = names.filter((name) => {
      return !FUNCTION_PROPERTIES.includes(name);
    });
  }
  // Map properties to descriptors.
  return names.map((name) => {
    let descriptor = Object.getOwnPropertyDescriptor(object, name);
    let member = {name, enumerable: descriptor.enumerable, writable: false};
    if (descriptor.get === undefined && typeof object[name] === 'function') {
      member.type = 'method';
    } else {
      if (descriptor.set || descriptor.writable)
        member.writable = true;
      member.type = 'get';
    }
    return member;
  });
};

// Return the description of object's prototype.
let getObjectPrototype = function(object) {
  let proto = Object.getPrototypeOf(object);
  if (proto === null || proto === Object.prototype)
    return null;
  return {
    members: getObjectMembers(proto),
    proto: getObjectPrototype(proto),
  };
};

// Convert a real value into meta data.
var valueToMeta = function(sender, value, optimizeSimpleObject) {
  var el, i, len, meta;
  if (optimizeSimpleObject == null) {
    optimizeSimpleObject = false;
  }
  meta = {
    type: typeof value
  };
  if (Buffer.isBuffer(value)) {
    meta.type = 'buffer';
  }
  if (value === null) {
    meta.type = 'value';
  }
  if (Array.isArray(value)) {
    meta.type = 'array';
  }
  if (value instanceof Error) {
    meta.type = 'error';
  }
  if (value instanceof Date) {
    meta.type = 'date';
  }
  if ((value != null ? value.constructor.name : void 0) === 'Promise') {
    meta.type = 'promise';
  }

  // Treat simple objects as value.
  if (optimizeSimpleObject && meta.type === 'object' && v8Util.getHiddenValue(value, 'simple')) {
    meta.type = 'value';
  }

  // Treat the arguments object as array.
  if (meta.type === 'object' && (value.hasOwnProperty('callee')) && (value.length != null)) {
    meta.type = 'array';
  }
  if (meta.type === 'array') {
    meta.members = [];
    for (i = 0, len = value.length; i < len; i++) {
      el = value[i];
      meta.members.push(valueToMeta(sender, el));
    }
  } else if (meta.type === 'object' || meta.type === 'function') {
    meta.name = value.constructor.name;

    // Reference the original value if it's an object, because when it's
    // passed to renderer we would assume the renderer keeps a reference of
    // it.
    meta.id = objectsRegistry.add(sender, value);
    meta.members = getObjectMembers(value);
    meta.proto = getObjectPrototype(value);
  } else if (meta.type === 'buffer') {
    meta.value = Array.prototype.slice.call(value, 0);
  } else if (meta.type === 'promise') {
    meta.then = valueToMeta(sender, value.then.bind(value));
  } else if (meta.type === 'error') {
    meta.members = plainObjectToMeta(value);

    // Error.name is not part of own properties.
    meta.members.push({
      name: 'name',
      value: value.name
    });
  } else if (meta.type === 'date') {
    meta.value = value.getTime();
  } else {
    meta.type = 'value';
    meta.value = value;
  }
  return meta;
};

// Convert object to meta by value.
var plainObjectToMeta = function(obj) {
  return Object.getOwnPropertyNames(obj).map(function(name) {
    return {
      name: name,
      value: obj[name]
    };
  });
};

// Convert Error into meta data.
var exceptionToMeta = function(error) {
  return {
    type: 'exception',
    message: error.message,
    stack: error.stack || error
  };
};

// Convert array of meta data from renderer into array of real values.
var unwrapArgs = function(sender, args) {
  var metaToValue;
  metaToValue = function(meta) {
    var i, len, member, ref, returnValue;
    switch (meta.type) {
      case 'value':
        return meta.value;
      case 'remote-object':
        return objectsRegistry.get(meta.id);
      case 'array':
        return unwrapArgs(sender, meta.value);
      case 'buffer':
        return new Buffer(meta.value);
      case 'date':
        return new Date(meta.value);
      case 'promise':
        return Promise.resolve({
          then: metaToValue(meta.then)
        });
      case 'object': {
        let ret = {};
        Object.defineProperty(ret.constructor, 'name', { value: meta.name });

        ref = meta.members;
        for (i = 0, len = ref.length; i < len; i++) {
          member = ref[i];
          ret[member.name] = metaToValue(member.value);
        }
        return ret;
      }
      case 'function-with-return-value':
        returnValue = metaToValue(meta.value);
        return function() {
          return returnValue;
        };
      case 'function': {
        // Cache the callbacks in renderer.
        let webContentsId = sender.getId();
        let callbacks = rendererFunctions[webContentsId];
        if (!callbacks) {
          callbacks = rendererFunctions[webContentsId] = new IDWeakMap;
          sender.once('render-view-deleted', function(event, id) {
            callbacks.clear();
            delete rendererFunctions[id];
          });
        }

        if (callbacks.has(meta.id))
          return callbacks.get(meta.id);

        let callIntoRenderer = function(...args) {
          if ((webContentsId in rendererFunctions) && !sender.isDestroyed())
            sender.send('ATOM_RENDERER_CALLBACK', meta.id, valueToMeta(sender, args));
          else
            throw new Error(`Attempting to call a function in a renderer window that has been closed or released. Function provided here: ${meta.location}.`);
        };
        v8Util.setDestructor(callIntoRenderer, function() {
          if ((webContentsId in rendererFunctions) && !sender.isDestroyed())
            sender.send('ATOM_RENDERER_RELEASE_CALLBACK', meta.id);
        });
        callbacks.set(meta.id, callIntoRenderer);
        return callIntoRenderer;
      }
      default:
        throw new TypeError("Unknown type: " + meta.type);
    }
  };
  return args.map(metaToValue);
};

// Call a function and send reply asynchronously if it's a an asynchronous
// style function and the caller didn't pass a callback.
var callFunction = function(event, func, caller, args) {
  var funcMarkedAsync, funcName, funcPassedCallback, ref, ret;
  funcMarkedAsync = v8Util.getHiddenValue(func, 'asynchronous');
  funcPassedCallback = typeof args[args.length - 1] === 'function';
  try {
    if (funcMarkedAsync && !funcPassedCallback) {
      args.push(function(ret) {
        return event.returnValue = valueToMeta(event.sender, ret, true);
      });
      return func.apply(caller, args);
    } else {
      ret = func.apply(caller, args);
      return event.returnValue = valueToMeta(event.sender, ret, true);
    }
  } catch (error) {
    // Catch functions thrown further down in function invocation and wrap
    // them with the function name so it's easier to trace things like
    // `Error processing argument -1.`
    funcName = (ref = func.name) != null ? ref : "anonymous";
    throw new Error("Could not call remote function `" + funcName + "`. Check that the function signature is correct. Underlying error: " + error.message);
  }
};

ipcMain.on('ATOM_BROWSER_REQUIRE', function(event, module) {
  try {
    return event.returnValue = valueToMeta(event.sender, process.mainModule.require(module));
  } catch (error) {
    return event.returnValue = exceptionToMeta(error);
  }
});

ipcMain.on('ATOM_BROWSER_GET_BUILTIN', function(event, module) {
  try {
    return event.returnValue = valueToMeta(event.sender, electron[module]);
  } catch (error) {
    return event.returnValue = exceptionToMeta(error);
  }
});

ipcMain.on('ATOM_BROWSER_GLOBAL', function(event, name) {
  try {
    return event.returnValue = valueToMeta(event.sender, global[name]);
  } catch (error) {
    return event.returnValue = exceptionToMeta(error);
  }
});

ipcMain.on('ATOM_BROWSER_CURRENT_WINDOW', function(event) {
  try {
    return event.returnValue = valueToMeta(event.sender, event.sender.getOwnerBrowserWindow());
  } catch (error) {
    return event.returnValue = exceptionToMeta(error);
  }
});

ipcMain.on('ATOM_BROWSER_CURRENT_WEB_CONTENTS', function(event) {
  return event.returnValue = valueToMeta(event.sender, event.sender);
});

ipcMain.on('ATOM_BROWSER_CONSTRUCTOR', function(event, id, args) {
  try {
    args = unwrapArgs(event.sender, args);
    let constructor = objectsRegistry.get(id);

    // Call new with array of arguments.
    // http://stackoverflow.com/questions/1606797/use-of-apply-with-new-operator-is-this-possible
    let obj = new (Function.prototype.bind.apply(constructor, [null].concat(args)));
    return event.returnValue = valueToMeta(event.sender, obj);
  } catch (error) {
    return event.returnValue = exceptionToMeta(error);
  }
});

ipcMain.on('ATOM_BROWSER_FUNCTION_CALL', function(event, id, args) {
  try {
    args = unwrapArgs(event.sender, args);
    let func = objectsRegistry.get(id);
    return callFunction(event, func, global, args);
  } catch (error) {
    return event.returnValue = exceptionToMeta(error);
  }
});

ipcMain.on('ATOM_BROWSER_MEMBER_CONSTRUCTOR', function(event, id, method, args) {
  try {
    args = unwrapArgs(event.sender, args);
    let constructor = objectsRegistry.get(id)[method];

    // Call new with array of arguments.
    let obj = new (Function.prototype.bind.apply(constructor, [null].concat(args)));
    return event.returnValue = valueToMeta(event.sender, obj);
  } catch (error) {
    return event.returnValue = exceptionToMeta(error);
  }
});

ipcMain.on('ATOM_BROWSER_MEMBER_CALL', function(event, id, method, args) {
  try {
    args = unwrapArgs(event.sender, args);
    let obj = objectsRegistry.get(id);
    return callFunction(event, obj[method], obj, args);
  } catch (error) {
    return event.returnValue = exceptionToMeta(error);
  }
});

ipcMain.on('ATOM_BROWSER_MEMBER_SET', function(event, id, name, value) {
  try {
    let obj = objectsRegistry.get(id);
    obj[name] = value;
    return event.returnValue = null;
  } catch (error) {
    return event.returnValue = exceptionToMeta(error);
  }
});

ipcMain.on('ATOM_BROWSER_MEMBER_GET', function(event, id, name) {
  try {
    let obj = objectsRegistry.get(id);
    return event.returnValue = valueToMeta(event.sender, obj[name]);
  } catch (error) {
    return event.returnValue = exceptionToMeta(error);
  }
});

ipcMain.on('ATOM_BROWSER_DEREFERENCE', function(event, id) {
  return objectsRegistry.remove(event.sender.getId(), id);
});

ipcMain.on('ATOM_BROWSER_GUEST_WEB_CONTENTS', function(event, guestInstanceId) {
  try {
    let guestViewManager = require('./guest-view-manager');
    return event.returnValue = valueToMeta(event.sender, guestViewManager.getGuest(guestInstanceId));
  } catch (error) {
    return event.returnValue = exceptionToMeta(error);
  }
});

ipcMain.on('ATOM_BROWSER_ASYNC_CALL_TO_GUEST_VIEW', function(event, requestId, guestInstanceId, method, ...args) {
  try {
    let guestViewManager = require('./guest-view-manager');
    let guest = guestViewManager.getGuest(guestInstanceId);
    if (requestId) {
      const responseCallback = function(result) {
        event.sender.send(`ATOM_RENDERER_ASYNC_CALL_TO_GUEST_VIEW_RESPONSE_${requestId}`, result);
      };
      args.push(responseCallback);
    }
    guest[method].apply(guest, args);
  } catch (error) {
    return event.returnValue = exceptionToMeta(error);
  }
});