@appium/base-driver/lib/protocol/protocol.js

Base driver class for Appium drivers

import _ from 'lodash';
import {util, logger} from '@appium/support';
import {validators} from './validators';
import {
  errors,
  isErrorType,
  getResponseForW3CError,
  errorFromMJSONWPStatusCode,
  errorFromW3CJsonCode,
} from './errors';
import {METHOD_MAP, NO_SESSION_ID_COMMANDS} from './routes';
import B from 'bluebird';
import {formatResponseValue, formatStatus} from './helpers';
import {MAX_LOG_BODY_LENGTH, PROTOCOLS, DEFAULT_BASE_PATH} from '../constants';
import {isW3cCaps} from '../helpers/capabilities';
import log from '../basedriver/logger';
import { generateDriverLogPrefix } from '../basedriver/helpers';

export const CREATE_SESSION_COMMAND = 'createSession';
export const DELETE_SESSION_COMMAND = 'deleteSession';
export const GET_STATUS_COMMAND = 'getStatus';
export const LIST_DRIVER_COMMANDS_COMMAND = 'listCommands';
export const LIST_DRIVER_EXTENSIONS_COMMAND = 'listExtensions';

/** @type {Set<string>} */
const deprecatedCommandsLogged = new Set();

function determineProtocol(createSessionArgs) {
  return _.some(createSessionArgs, isW3cCaps) ? PROTOCOLS.W3C : PROTOCOLS.MJSONWP;
}

function extractProtocol(driver, sessionId = null) {
  const dstDriver = _.isFunction(driver.driverForSession)
    ? driver.driverForSession(sessionId)
    : driver;
  if (dstDriver === driver) {
    // Shortcircuit if the driver instance is not an umbrella driver
    // or it is Fake driver instance, where `driver.driverForSession`
    // always returns self instance
    return driver.protocol;
  }

  // Extract the protocol for the current session if the given driver is the umbrella one
  return dstDriver?.protocol ?? PROTOCOLS.W3C;
}

function isSessionCommand(command) {
  return !_.includes(NO_SESSION_ID_COMMANDS, command);
}

/**
 *
 * @param {import('@appium/types').ExternalDriver} driver
 * @param {string?} [sessionId]
 * @returns {import('@appium/types').AppiumLogger}
 */
function getLogger(driver, sessionId = null) {
  const dstDriver =
    sessionId && _.isFunction(driver.driverForSession)
      ? driver.driverForSession(sessionId) ?? driver
      : driver;
  if (_.isFunction(dstDriver.log?.info)) {
    return dstDriver.log;
  }

  const logPrefix = generateDriverLogPrefix(dstDriver);
  return logger.getLogger(logPrefix);
}

function wrapParams(paramSets, jsonObj) {
  /* There are commands like performTouch which take a single parameter (primitive type or array).
   * Some drivers choose to pass this parameter as a value (eg. [action1, action2...]) while others to
   * wrap it within an object(eg' {gesture:  [action1, action2...]}), which makes it hard to validate.
   * The wrap option in the spec enforce wrapping before validation, so that all params are wrapped at
   * the time they are validated and later passed to the commands.
   */
  let res = jsonObj;
  if (_.isArray(jsonObj) || !_.isObject(jsonObj)) {
    res = {};
    res[paramSets.wrap] = jsonObj;
  }
  return res;
}

function unwrapParams(paramSets, jsonObj) {
  /* There are commands like setNetworkConnection which send parameters wrapped inside a key such as
   * "parameters". This function unwraps them (eg. {"parameters": {"type": 1}} becomes {"type": 1}).
   */
  let res = jsonObj;
  if (_.isObject(jsonObj)) {
    // some clients, like ruby, don't wrap
    if (jsonObj[paramSets.unwrap]) {
      res = jsonObj[paramSets.unwrap];
    }
  }
  return res;
}

export function checkParams(paramSets, jsonObj, protocol) {
  let requiredParams = [];
  let optionalParams = [];
  let receivedParams = _.keys(jsonObj);

  if (paramSets) {
    if (paramSets.required) {
      // we might have an array of parameters,
      // or an array of arrays of parameters, so standardize
      if (!_.isArray(_.first(paramSets.required))) {
        requiredParams = [paramSets.required];
      } else {
        requiredParams = paramSets.required;
      }
    }
    // optional parameters are just an array
    if (paramSets.optional) {
      optionalParams = paramSets.optional;
    }

    // If a function was provided as the 'validate' key, it will here be called with
    // jsonObj as the param. If it returns something falsy, verification will be
    // considered to have passed. If it returns something else, that will be the
    // argument to an error which is thrown to the user
    if (paramSets.validate) {
      let message = paramSets.validate(jsonObj, protocol);
      if (message) {
        throw new errors.BadParametersError(message, jsonObj);
      }
    }
  }

  // if we have no required parameters, all is well
  if (requiredParams.length === 0) {
    return;
  }

  // some clients pass in the session id in the params
  if (optionalParams.indexOf('sessionId') === -1) {
    optionalParams.push('sessionId');
  }

  // some clients pass in an element id in the params
  if (optionalParams.indexOf('id') === -1) {
    optionalParams.push('id');
  }

  // go through the required parameters and check against our arguments
  for (let params of requiredParams) {
    if (
      _.difference(receivedParams, params, optionalParams).length === 0 &&
      _.difference(params, receivedParams).length === 0
    ) {
      // we have a set of parameters that is correct
      // so short-circuit
      return;
    }
  }
  throw new errors.BadParametersError(paramSets, receivedParams);
}

/*
 * This method takes 3 pieces of data: request parameters ('requestParams'),
 * a request JSON body ('jsonObj'), and 'payloadParams', which is the section
 * from the route definition for a particular endpoint which has instructions
 * on handling parameters. This method returns an array of arguments which will
 * be applied to a command.
 */
export function makeArgs(requestParams, jsonObj, payloadParams, protocol) {
  // We want to pass the "url" parameters to the commands in reverse order
  // since the command will sometimes want to ignore, say, the sessionId.
  // This has the effect of putting sessionId last, which means in JS we can
  // omit it from the function signature if we're not going to use it.
  let urlParams = _.keys(requestParams).reverse();

  // In the simple case, the required parameters are a basic array in
  // payloadParams.required, so start there. It's possible that there are
  // multiple optional sets of required params, though, so handle that case
  // too.
  let requiredParams = payloadParams.required;
  if (_.isArray(_.first(payloadParams.required))) {
    // If there are optional sets of required params, then we will have an
    // array of arrays in payloadParams.required, so loop through each set and
    // pick the one that matches which JSON params were actually sent. We've
    // already been through validation so we're guaranteed to find a match.
    let keys = _.keys(jsonObj);
    for (let params of payloadParams.required) {
      if (_.without(params, ...keys).length === 0) {
        requiredParams = params;
        break;
      }
    }
  }

  // Now we construct our list of arguments which will be passed to the command
  let args;
  if (_.isFunction(payloadParams.makeArgs)) {
    // In the route spec, a particular route might define a 'makeArgs' function
    // if it wants full control over how to turn JSON parameters into command
    // arguments. So we pass it the JSON parameters and it returns an array
    // which will be applied to the handling command. For example if it returns
    // [1, 2, 3], we will call `command(1, 2, 3, ...)` (url params are separate
    // from JSON params and get concatenated below).
    args = payloadParams.makeArgs(jsonObj, protocol);
  } else {
    // Otherwise, collect all the required and optional params and flatten them
    // into an argument array
    args = _.flatten(requiredParams).map((p) => jsonObj[p]);
    if (payloadParams.optional) {
      args = args.concat(_.flatten(payloadParams.optional).map((p) => jsonObj[p]));
    }
  }
  // Finally, get our url params (session id, element id, etc...) on the end of
  // the list
  args = args.concat(urlParams.map((u) => requestParams[u]));
  return args;
}

function validateExecuteMethodParams(params, paramSpec) {
  // the w3c protocol will give us an array of arguments to apply to a javascript function.
  // that's not what we're doing. we're going to look for a JS object as the first arg, so we
  // can perform validation on it. we'll ignore everything else.
  if (!params || !_.isArray(params) || params.length > 1) {
    throw new errors.InvalidArgumentError(
      `Did not get correct format of arguments for execute method. Expected zero or one ` +
        `arguments to execute script and instead received: ${JSON.stringify(params)}`
    );
  }
  let args = params[0] ?? {};
  if (!_.isPlainObject(args)) {
    throw new errors.InvalidArgumentError(
      `Did not receive an appropriate execute method parameters object. It needs to be ` +
        `deserializable as a plain JS object`
    );
  }
  if (!paramSpec) {
    paramSpec = {required: [], optional: []};
  } else {
    paramSpec.required ??= [];
    paramSpec.optional ??= [];
    const unknownNames = _.difference(_.keys(args), paramSpec.required, paramSpec.optional);
    if (!_.isEmpty(unknownNames)) {
      log.info(`The following script arguments are not known and will be ignored: ${unknownNames}`);
      args = _.pickBy(args, (v, k) => !unknownNames.includes(k));
    }
    checkParams(paramSpec, args, null);
  }
  const argsToApply = makeArgs({}, args, paramSpec, null);
  return argsToApply;
}

/**
 *
 * @param {import('@appium/types').Core} driver
 * @returns {import('../express/server').RouteConfiguringFunction}
 */
function routeConfiguringFunction(driver) {
  if (!driver.sessionExists) {
    throw new Error('Drivers must implement `sessionExists` property');
  }

  if (!(/** @type {any} */ (driver).executeCommand || /** @type {any} */ (driver).execute)) {
    throw new Error('Drivers must implement `executeCommand` or `execute` method');
  }

  // return a function which will add all the routes to the driver. Here extraMethods might be
  // passed in as defined by Appium plugins, so we need to add those to the default list
  return function addRoutes(app, {basePath = DEFAULT_BASE_PATH, extraMethodMap = {}} = {}) {
    // store basePath on the driver instance so it can use it if necessary
    // for example in determining proxy avoidance
    driver.basePath = basePath;

    const allMethods = {...METHOD_MAP, ...extraMethodMap};

    for (const [path, methods] of _.toPairs(allMethods)) {
      for (const [method, spec] of _.toPairs(methods)) {
        // set up the express route handler
        buildHandler(
          app,
          method,
          `${basePath}${path}`,
          spec,
          driver,
          isSessionCommand(/** @type {import('@appium/types').DriverMethodDef} */ (spec).command)
        );
      }
    }
  };
}

function buildHandler(app, method, path, spec, driver, isSessCmd) {
  let asyncHandler = async (req, res) => {
    let jsonObj = req.body;
    let httpResBody = {};
    let httpStatus = 200;
    let newSessionId;
    let currentProtocol = extractProtocol(driver, req.params.sessionId);

    try {
      // if the route accessed is deprecated, log a warning
      if (spec.deprecated && !deprecatedCommandsLogged.has(spec.command)) {
        deprecatedCommandsLogged.add(spec.command);
        getLogger(driver, req.params.sessionId).warn(
          `Command '${spec.command}' has been deprecated and will be removed in a future ` +
            `version of Appium or your driver/plugin. Please use a different method or contact the ` +
            `driver/plugin author to add explicit support for the command before it is removed`
        );
      }

      // if this is a session command but we don't have a session,
      // error out early (especially before proxying)
      if (isSessCmd && !driver.sessionExists(req.params.sessionId)) {
        throw new errors.NoSuchDriverError();
      }

      // if the driver is currently proxying commands to another JSONWP server, bypass all our
      // checks and assume the upstream server knows what it's doing. But keep this in the
      // try/catch block so if proxying itself fails, we give a message to the client. Of course we
      // only want to do these when we have a session command; the Appium driver must be
      // responsible for start/stop session, etc... We also allow the command spec to declare that
      // this command should never be proxied (which is useful for plugin developers who add
      // commands and generally would not want that command to be proxied instead of handled by the
      // plugin)
      let didPluginOverrideProxy = false;
      if (isSessCmd && !spec.neverProxy && driverShouldDoJwpProxy(driver, req, spec.command)) {
        if (
          !driver.pluginsToHandleCmd ||
          driver.pluginsToHandleCmd(spec.command, req.params.sessionId).length === 0
        ) {
          await doJwpProxy(driver, req, res);
          return;
        }
        getLogger(driver, req.params.sessionId).debug(
          `Would have proxied ` +
            `command directly, but a plugin exists which might require its value, so will let ` +
            `its value be collected internally and made part of plugin chain`
        );
        didPluginOverrideProxy = true;
      }

      // if a command is not in our method map, it's because we
      // have no plans to ever implement it
      if (!spec.command) {
        throw new errors.NotImplementedError();
      }

      // wrap params if necessary
      if (spec.payloadParams && spec.payloadParams.wrap) {
        jsonObj = wrapParams(spec.payloadParams, jsonObj);
      }

      // unwrap params if necessary
      if (spec.payloadParams && spec.payloadParams.unwrap) {
        jsonObj = unwrapParams(spec.payloadParams, jsonObj);
      }

      if (spec.command === CREATE_SESSION_COMMAND) {
        // try to determine protocol by session creation args, so we can throw a
        // properly formatted error if arguments validation fails
        currentProtocol = determineProtocol(
          makeArgs(req.params, jsonObj, spec.payloadParams || {})
        );
      }

      // ensure that the json payload conforms to the spec
      checkParams(spec.payloadParams, jsonObj, currentProtocol);

      // turn the command and json payload into an argument list for
      // the driver methods
      let args = makeArgs(req.params, jsonObj, spec.payloadParams || {}, currentProtocol);
      let driverRes;
      // validate command args according to MJSONWP
      if (validators[spec.command]) {
        validators[spec.command](...args);
      }

      // run the driver command wrapped inside the argument validators
      getLogger(driver, req.params.sessionId).debug(
        `Calling ` +
          `${driver.constructor.name}.${spec.command}() with args: ` +
          _.truncate(JSON.stringify(args), {length: MAX_LOG_BODY_LENGTH})
      );

      if (didPluginOverrideProxy) {
        // TODO for now we add this information on the args list, but that's mixing purposes here.
        // We really should add another 'options' parameter to 'executeCommand', but this would be
        // a breaking change for all drivers so would need to be handled carefully.
        args.push({reqForProxy: req});
      }

      driverRes = await driver.executeCommand(spec.command, ...args);

      // Get the protocol after executeCommand
      currentProtocol = extractProtocol(driver, req.params.sessionId) || currentProtocol;

      // If `executeCommand` was overridden and the method returns an object
      // with a protocol and value/error property, re-assign the protocol
      if (_.isPlainObject(driverRes) && _.has(driverRes, 'protocol')) {
        currentProtocol = driverRes.protocol || currentProtocol;
        if (driverRes.error) {
          throw driverRes.error;
        }
        driverRes = driverRes.value;
      }

      // unpack createSession response
      if (spec.command === CREATE_SESSION_COMMAND) {
        newSessionId = driverRes[0];
        getLogger(driver, newSessionId).debug(
          `Cached the protocol value '${currentProtocol}' for the new session ${newSessionId}`
        );
        if (currentProtocol === PROTOCOLS.MJSONWP) {
          driverRes = driverRes[1];
        } else if (currentProtocol === PROTOCOLS.W3C) {
          driverRes = {
            capabilities: driverRes[1],
          };
        }
      }

      driverRes = formatResponseValue(driverRes);

      // delete should not return anything even if successful
      if (spec.command === DELETE_SESSION_COMMAND) {
        getLogger(driver, req.params.sessionId).debug(
          `Received response: ${_.truncate(JSON.stringify(driverRes), {
            length: MAX_LOG_BODY_LENGTH,
          })}`
        );
        getLogger(driver, req.params.sessionId).debug('But deleting session, so not returning');
        driverRes = null;
      }

      // if the status is not 0,  throw the appropriate error for status code.
      if (util.hasValue(driverRes)) {
        if (
          util.hasValue(driverRes.status) &&
          !isNaN(driverRes.status) &&
          parseInt(driverRes.status, 10) !== 0
        ) {
          throw errorFromMJSONWPStatusCode(driverRes.status, driverRes.value);
        } else if (_.isPlainObject(driverRes.value) && driverRes.value.error) {
          throw errorFromW3CJsonCode(
            driverRes.value.error,
            driverRes.value.message,
            driverRes.value.stacktrace
          );
        }
      }

      httpResBody.value = driverRes;
      getLogger(driver, req.params.sessionId || newSessionId).debug(
        `Responding ` +
          `to client with driver.${spec.command}() result: ${_.truncate(JSON.stringify(driverRes), {
            length: MAX_LOG_BODY_LENGTH,
          })}`
      );
    } catch (err) {
      // if anything goes wrong, figure out what our response should be
      // based on the type of error that we encountered
      let actualErr;
      if (err instanceof Error || (_.has(err, 'stack') && _.has(err, 'message'))) {
        actualErr = err;
      } else {
        getLogger(driver, req.params.sessionId || newSessionId).warn(
          'The thrown error object does not seem to be a valid instance of the Error class. This ' +
            'might be a genuine bug of a driver or a plugin.'
        );
        actualErr = new Error(`${err ?? 'unknown'}`);
      }

      currentProtocol =
        currentProtocol || extractProtocol(driver, req.params.sessionId || newSessionId);

      let errMsg = err.stacktrace || err.stack;
      if (!_.includes(errMsg, err.message)) {
        // if the message has more information, add it. but often the message
        // is the first part of the stack trace
        errMsg = `${err.message}${errMsg ? '\n' + errMsg : ''}`;
      }
      if (isErrorType(err, errors.ProxyRequestError)) {
        actualErr = err.getActualError();
      } else {
        getLogger(driver, req.params.sessionId || newSessionId).debug(
          `Encountered internal error running command: ${errMsg}`
        );
      }

      [httpStatus, httpResBody] = getResponseForW3CError(actualErr);
    }

    // decode the response, which is either a string or json
    if (_.isString(httpResBody)) {
      res.status(httpStatus).send(httpResBody);
    } else {
      if (newSessionId) {
        if (currentProtocol === PROTOCOLS.W3C) {
          httpResBody.value.sessionId = newSessionId;
        } else {
          httpResBody.sessionId = newSessionId;
        }
      } else {
        httpResBody.sessionId = req.params.sessionId || null;
      }
      // Don't include sessionId in W3C responses
      if (currentProtocol === PROTOCOLS.W3C) {
        delete httpResBody.sessionId;
      }

      httpResBody = formatStatus(httpResBody);
      res.status(httpStatus).json(httpResBody);
    }
  };
  // add the method to the app
  app[method.toLowerCase()](path, (req, res) => {
    B.resolve(asyncHandler(req, res)).done();
  });
}

function driverShouldDoJwpProxy(driver, req, command) {
  // drivers need to explicitly say when the proxy is active
  if (!driver.proxyActive(req.params.sessionId)) {
    return false;
  }

  // we should never proxy deleteSession because we need to give the containing
  // driver an opportunity to clean itself up
  if (command === DELETE_SESSION_COMMAND) {
    return false;
  }

  // validate avoidance schema, and say we shouldn't proxy if anything in the
  // avoid list matches our req
  if (driver.proxyRouteIsAvoided(req.params.sessionId, req.method, req.originalUrl, req.body)) {
    return false;
  }

  return true;
}

async function doJwpProxy(driver, req, res) {
  getLogger(driver, req.params.sessionId).info(
    'Driver proxy active, passing request on via HTTP proxy'
  );

  // check that the inner driver has a proxy function
  if (!driver.canProxy(req.params.sessionId)) {
    throw new Error('Trying to proxy to a server but the driver is unable to proxy');
  }
  try {
    await driver.executeCommand('proxyReqRes', req, res, req.params.sessionId);
  } catch (err) {
    if (isErrorType(err, errors.ProxyRequestError)) {
      throw err;
    } else {
      throw new Error(`Could not proxy. Proxy error: ${err.message}`);
    }
  }
}

export {
  routeConfiguringFunction,
  isSessionCommand,
  driverShouldDoJwpProxy,
  determineProtocol,
  deprecatedCommandsLogged,
  validateExecuteMethodParams,
};