authclient.ts

// Copyright 2012 Google LLC
//
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
//      http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.

import {EventEmitter} from 'events';
import {Gaxios, GaxiosOptions, GaxiosPromise, GaxiosResponse} from 'gaxios';

import {Credentials} from './credentials';
import {OriginalAndCamel, originalOrCamelOptions} from '../util';
import {log as makeLog} from 'google-logging-utils';

import {PRODUCT_NAME, USER_AGENT} from '../shared.cjs';

/**
 * Easy access to symbol-indexed strings on config objects.
 */
export type SymbolIndexString = {
  [key: symbol]: string | undefined;
};

/**
 * Base auth configurations (e.g. from JWT or `.json` files) with conventional
 * camelCased options.
 *
 * @privateRemarks
 *
 * This interface is purposely not exported so that it can be removed once
 * {@link https://github.com/microsoft/TypeScript/issues/50715} has been
 * resolved. Then, we can use {@link OriginalAndCamel} to shrink this interface.
 *
 * Tracking: {@link https://github.com/googleapis/google-auth-library-nodejs/issues/1686}
 */
interface AuthJSONOptions {
  /**
   * The project ID corresponding to the current credentials if available.
   */
  project_id: string | null;
  /**
   * An alias for {@link AuthJSONOptions.project_id `project_id`}.
   */
  projectId: AuthJSONOptions['project_id'];

  /**
   * The quota project ID. The quota project can be used by client libraries for the billing purpose.
   * See {@link https://cloud.google.com/docs/quota Working with quotas}
   */
  quota_project_id: string;

  /**
   * An alias for {@link AuthJSONOptions.quota_project_id `quota_project_id`}.
   */
  quotaProjectId: AuthJSONOptions['quota_project_id'];

  /**
   * The default service domain for a given Cloud universe.
   *
   * @example
   * 'googleapis.com'
   */
  universe_domain: string;

  /**
   * An alias for {@link AuthJSONOptions.universe_domain `universe_domain`}.
   */
  universeDomain: AuthJSONOptions['universe_domain'];
}

/**
 * Base `AuthClient` configuration.
 *
 * The camelCased options are aliases of the snake_cased options, supporting both
 * JSON API and JS conventions.
 */
export interface AuthClientOptions
  extends Partial<OriginalAndCamel<AuthJSONOptions>> {
  /**
   * An API key to use, optional.
   */
  apiKey?: string;
  credentials?: Credentials;

  /**
   * The {@link Gaxios `Gaxios`} instance used for making requests.
   *
   * @see {@link AuthClientOptions.useAuthRequestParameters}
   */
  transporter?: Gaxios;

  /**
   * Provides default options to the transporter, such as {@link GaxiosOptions.agent `agent`} or
   *  {@link GaxiosOptions.retryConfig `retryConfig`}.
   *
   * This option is ignored if {@link AuthClientOptions.transporter `gaxios`} has been provided
   */
  transporterOptions?: GaxiosOptions;

  /**
   * The expiration threshold in milliseconds before forcing token refresh of
   * unexpired tokens.
   */
  eagerRefreshThresholdMillis?: number;

  /**
   * Whether to attempt to refresh tokens on status 401/403 responses
   * even if an attempt is made to refresh the token preemptively based
   * on the expiry_date.
   */
  forceRefreshOnFailure?: boolean;

  /**
   * Enables/disables the adding of the AuthClient's default interceptor.
   *
   * @see {@link AuthClientOptions.transporter}
   *
   * @remarks
   *
   * Disabling is useful for debugging and experimentation.
   *
   * @default true
   */
  useAuthRequestParameters?: boolean;
}

/**
 * The default cloud universe
 *
 * @see {@link AuthJSONOptions.universe_domain}
 */
export const DEFAULT_UNIVERSE = 'googleapis.com';

/**
 * The default {@link AuthClientOptions.eagerRefreshThresholdMillis}
 */
export const DEFAULT_EAGER_REFRESH_THRESHOLD_MILLIS = 5 * 60 * 1000;

/**
 * Defines the root interface for all clients that generate credentials
 * for calling Google APIs. All clients should implement this interface.
 */
export interface CredentialsClient {
  projectId?: AuthClientOptions['projectId'];
  eagerRefreshThresholdMillis: NonNullable<
    AuthClientOptions['eagerRefreshThresholdMillis']
  >;
  forceRefreshOnFailure: NonNullable<
    AuthClientOptions['forceRefreshOnFailure']
  >;

  /**
   * @return A promise that resolves with the current GCP access token
   *   response. If the current credential is expired, a new one is retrieved.
   */
  getAccessToken(): Promise<GetAccessTokenResponse>;

  /**
   * The main authentication interface. It takes an optional url which when
   * present is the endpoint being accessed, and returns a Promise which
   * resolves with authorization header fields.
   *
   * The result has the form:
   * { authorization: 'Bearer <access_token_value>' }
   * @param url The URI being authorized.
   */
  getRequestHeaders(url?: string | URL): Promise<Headers>;

  /**
   * Provides an alternative Gaxios request implementation with auth credentials
   */
  request<T>(opts: GaxiosOptions): GaxiosPromise<T>;

  /**
   * Sets the auth credentials.
   */
  setCredentials(credentials: Credentials): void;

  /**
   * Subscribes a listener to the tokens event triggered when a token is
   * generated.
   *
   * @param event The tokens event to subscribe to.
   * @param listener The listener that triggers on event trigger.
   * @return The current client instance.
   */
  on(event: 'tokens', listener: (tokens: Credentials) => void): this;
}

export declare interface AuthClient {
  on(event: 'tokens', listener: (tokens: Credentials) => void): this;
}

export abstract class AuthClient
  extends EventEmitter
  implements CredentialsClient
{
  apiKey?: string;
  projectId?: string | null;
  /**
   * The quota project ID. The quota project can be used by client libraries for the billing purpose.
   * See {@link https://cloud.google.com/docs/quota Working with quotas}
   */
  quotaProjectId?: string;
  /**
   * The {@link Gaxios `Gaxios`} instance used for making requests.
   */
  transporter: Gaxios;
  credentials: Credentials = {};
  eagerRefreshThresholdMillis = DEFAULT_EAGER_REFRESH_THRESHOLD_MILLIS;
  forceRefreshOnFailure = false;
  universeDomain = DEFAULT_UNIVERSE;

  /**
   * Symbols that can be added to GaxiosOptions to specify the method name that is
   * making an RPC call, for logging purposes, as well as a string ID that can be
   * used to correlate calls and responses.
   */
  static readonly RequestMethodNameSymbol: unique symbol = Symbol(
    'request method name',
  );
  static readonly RequestLogIdSymbol: unique symbol = Symbol('request log id');

  constructor(opts: AuthClientOptions = {}) {
    super();

    const options = originalOrCamelOptions(opts);

    // Shared auth options
    this.apiKey = opts.apiKey;
    this.projectId = options.get('project_id') ?? null;
    this.quotaProjectId = options.get('quota_project_id');
    this.credentials = options.get('credentials') ?? {};
    this.universeDomain = options.get('universe_domain') ?? DEFAULT_UNIVERSE;

    // Shared client options
    this.transporter = opts.transporter ?? new Gaxios(opts.transporterOptions);

    if (options.get('useAuthRequestParameters') !== false) {
      this.transporter.interceptors.request.add(
        AuthClient.DEFAULT_REQUEST_INTERCEPTOR,
      );
      this.transporter.interceptors.response.add(
        AuthClient.DEFAULT_RESPONSE_INTERCEPTOR,
      );
    }

    if (opts.eagerRefreshThresholdMillis) {
      this.eagerRefreshThresholdMillis = opts.eagerRefreshThresholdMillis;
    }

    this.forceRefreshOnFailure = opts.forceRefreshOnFailure ?? false;
  }

  /**
   * The public request API in which credentials may be added to the request.
   *
   * @param options options for `gaxios`
   */
  abstract request<T>(options: GaxiosOptions): GaxiosPromise<T>;

  /**
   * The main authentication interface. It takes an optional url which when
   * present is the endpoint being accessed, and returns a Promise which
   * resolves with authorization header fields.
   *
   * The result has the form:
   * ```ts
   * new Headers({'authorization': 'Bearer <access_token_value>'});
   * ```
   *
   * @param url The URI being authorized.
   */
  abstract getRequestHeaders(url?: string | URL): Promise<Headers>;

  /**
   * @return A promise that resolves with the current GCP access token
   *   response. If the current credential is expired, a new one is retrieved.
   */
  abstract getAccessToken(): Promise<{
    token?: string | null;
    res?: GaxiosResponse | null;
  }>;

  /**
   * Sets the auth credentials.
   */
  setCredentials(credentials: Credentials) {
    this.credentials = credentials;
  }

  /**
   * Append additional headers, e.g., x-goog-user-project, shared across the
   * classes inheriting AuthClient. This method should be used by any method
   * that overrides getRequestMetadataAsync(), which is a shared helper for
   * setting request information in both gRPC and HTTP API calls.
   *
   * @param headers object to append additional headers to.
   */
  protected addSharedMetadataHeaders(headers: Headers): Headers {
    // quota_project_id, stored in application_default_credentials.json, is set in
    // the x-goog-user-project header, to indicate an alternate account for
    // billing and quota:
    if (
      !headers.has('x-goog-user-project') && // don't override a value the user sets.
      this.quotaProjectId
    ) {
      headers.set('x-goog-user-project', this.quotaProjectId);
    }
    return headers;
  }

  /**
   * Adds the `x-goog-user-project` and `authorization` headers to the target Headers
   * object, if they exist on the source.
   *
   * @param target the headers to target
   * @param source the headers to source from
   * @returns the target headers
   */
  protected addUserProjectAndAuthHeaders<T extends Headers>(
    target: T,
    source: Headers,
  ): T {
    const xGoogUserProject = source.get('x-goog-user-project');
    const authorizationHeader = source.get('authorization');

    if (xGoogUserProject) {
      target.set('x-goog-user-project', xGoogUserProject);
    }

    if (authorizationHeader) {
      target.set('authorization', authorizationHeader);
    }

    return target;
  }

  static log = makeLog('auth');
  static readonly DEFAULT_REQUEST_INTERCEPTOR: Parameters<
    Gaxios['interceptors']['request']['add']
  >[0] = {
    resolved: async config => {
      // Set `x-goog-api-client`, if not already set
      if (!config.headers.has('x-goog-api-client')) {
        const nodeVersion = process.version.replace(/^v/, '');
        config.headers.set('x-goog-api-client', `gl-node/${nodeVersion}`);
      }

      // Set `User-Agent`
      const userAgent = config.headers.get('User-Agent');
      if (!userAgent) {
        config.headers.set('User-Agent', USER_AGENT);
      } else if (!userAgent.includes(`${PRODUCT_NAME}/`)) {
        config.headers.set('User-Agent', `${userAgent} ${USER_AGENT}`);
      }

      try {
        const symbols: SymbolIndexString =
          config as unknown as SymbolIndexString;
        const methodName = symbols[AuthClient.RequestMethodNameSymbol];

        // This doesn't need to be very unique or interesting, it's just an aid for
        // matching requests to responses.
        const logId = `${Math.floor(Math.random() * 1000)}`;
        symbols[AuthClient.RequestLogIdSymbol] = logId;

        // Boil down the object we're printing out.
        const logObject = {
          url: config.url,
          headers: config.headers,
        };
        if (methodName) {
          AuthClient.log.info(
            '%s [%s] request %j',
            methodName,
            logId,
            logObject,
          );
        } else {
          AuthClient.log.info('[%s] request %j', logId, logObject);
        }
      } catch (e) {
        // Logging must not create new errors; swallow them all.
      }

      return config;
    },
  };

  static readonly DEFAULT_RESPONSE_INTERCEPTOR: Parameters<
    Gaxios['interceptors']['response']['add']
  >[0] = {
    resolved: async response => {
      try {
        const symbols: SymbolIndexString =
          response.config as unknown as SymbolIndexString;
        const methodName = symbols[AuthClient.RequestMethodNameSymbol];
        const logId = symbols[AuthClient.RequestLogIdSymbol];
        if (methodName) {
          AuthClient.log.info(
            '%s [%s] response %j',
            methodName,
            logId,
            response.data,
          );
        } else {
          AuthClient.log.info('[%s] response %j', logId, response.data);
        }
      } catch (e) {
        // Logging must not create new errors; swallow them all.
      }

      return response;
    },
    rejected: async error => {
      try {
        const symbols: SymbolIndexString =
          error.config as unknown as SymbolIndexString;
        const methodName = symbols[AuthClient.RequestMethodNameSymbol];
        const logId = symbols[AuthClient.RequestLogIdSymbol];
        if (methodName) {
          AuthClient.log.info(
            '%s [%s] error %j',
            methodName,
            logId,
            error.response?.data,
          );
        } else {
          AuthClient.log.error('[%s] error %j', logId, error.response?.data);
        }
      } catch (e) {
        // Logging must not create new errors; swallow them all.
      }

      // Re-throw the error.
      throw error;
    },
  };

  /**
   * Sets the method name that is making a Gaxios request, so that logging may tag
   * log lines with the operation.
   * @param config A Gaxios request config
   * @param methodName The method name making the call
   */
  static setMethodName(config: GaxiosOptions, methodName: string) {
    try {
      const symbols: SymbolIndexString = config as unknown as SymbolIndexString;
      symbols[AuthClient.RequestMethodNameSymbol] = methodName;
    } catch (e) {
      // Logging must not create new errors; swallow them all.
    }
  }

  /**
   * Retry config for Auth-related requests.
   *
   * @remarks
   *
   * This is not a part of the default {@link AuthClient.transporter transporter/gaxios}
   * config as some downstream APIs would prefer if customers explicitly enable retries,
   * such as GCS.
   */
  protected static get RETRY_CONFIG(): GaxiosOptions {
    return {
      retry: true,
      retryConfig: {
        httpMethodsToRetry: ['GET', 'PUT', 'POST', 'HEAD', 'OPTIONS', 'DELETE'],
      },
    };
  }
}

// TypeScript does not have `HeadersInit` in the standard types yet
export type HeadersInit = ConstructorParameters<typeof Headers>[0];

export interface GetAccessTokenResponse {
  token?: string | null;
  res?: GaxiosResponse | null;
}

/**
 * @deprecated - use the Promise API instead
 */
export interface BodyResponseCallback<T> {
  (err: Error | null, res?: GaxiosResponse<T> | null): void;
}