@aws-amplify/core/src/Credentials.ts

Core category of aws-amplify

// Copyright Amazon.com, Inc. or its affiliates. All Rights Reserved.
// SPDX-License-Identifier: Apache-2.0
import { ConsoleLogger as Logger } from './Logger';
import { StorageHelper } from './StorageHelper';
import { makeQuerablePromise } from './JS';
import { FacebookOAuth, GoogleOAuth } from './OAuthHelper';
import { jitteredExponentialRetry } from './Util';
import { ICredentials } from './types';
import { Amplify } from './Amplify';
import { getId, getCredentialsForIdentity } from './AwsClients/CognitoIdentity';
import { parseAWSExports } from './parseAWSExports';
import { Hub } from './Hub';

const logger = new Logger('Credentials');

const CREDENTIALS_TTL = 50 * 60 * 1000; // 50 min, can be modified on config if required in the future

const COGNITO_IDENTITY_KEY_PREFIX = 'CognitoIdentityId-';

const AMPLIFY_SYMBOL = (
	typeof Symbol !== 'undefined' && typeof Symbol.for === 'function'
		? Symbol.for('amplify_default')
		: '@@amplify_default'
) as Symbol;

const dispatchCredentialsEvent = (
	event: string,
	data: any,
	message: string
) => {
	Hub.dispatch('core', { event, data, message }, 'Credentials', AMPLIFY_SYMBOL);
};

export class CredentialsClass {
	private _config;
	private _credentials;
	private _credentials_source;
	private _gettingCredPromise = null;
	private _refreshHandlers = {};
	private _storage;
	private _storageSync;
	private _identityId;
	private _nextCredentialsRefresh: number;

	// Allow `Auth` to be injected for SSR, but Auth isn't a required dependency for Credentials
	Auth = undefined;

	constructor(config) {
		this.configure(config);
		this._refreshHandlers['google'] = GoogleOAuth.refreshGoogleToken;
		this._refreshHandlers['facebook'] = FacebookOAuth.refreshFacebookToken;
	}

	public getModuleName() {
		return 'Credentials';
	}

	public getCredSource() {
		return this._credentials_source;
	}

	public configure(config) {
		if (!config) return this._config || {};

		this._config = Object.assign({}, this._config, config);
		const { refreshHandlers } = this._config;
		// If the developer has provided an object of refresh handlers,
		// then we can merge the provided handlers with the current handlers.
		if (refreshHandlers) {
			this._refreshHandlers = {
				...this._refreshHandlers,
				...refreshHandlers,
			};
		}

		this._storage = this._config.storage;

		if (!this._storage) {
			this._storage = new StorageHelper().getStorage();
		}

		this._storageSync = Promise.resolve();
		if (typeof this._storage['sync'] === 'function') {
			this._storageSync = this._storage['sync']();
		}

		dispatchCredentialsEvent(
			'credentials_configured',
			null,
			`Credentials has been configured successfully`
		);

		return this._config;
	}

	public get() {
		logger.debug('getting credentials');
		return this._pickupCredentials();
	}

	// currently we only store the guest identity in local storage
	private _getCognitoIdentityIdStorageKey(identityPoolId: string) {
		return `${COGNITO_IDENTITY_KEY_PREFIX}${identityPoolId}`;
	}

	private _pickupCredentials() {
		logger.debug('picking up credentials');
		if (!this._gettingCredPromise || !this._gettingCredPromise.isPending()) {
			logger.debug('getting new cred promise');
			this._gettingCredPromise = makeQuerablePromise(this._keepAlive());
		} else {
			logger.debug('getting old cred promise');
		}
		return this._gettingCredPromise;
	}

	private async _keepAlive() {
		logger.debug('checking if credentials exists and not expired');
		const cred = this._credentials;
		if (cred && !this._isExpired(cred) && !this._isPastTTL()) {
			logger.debug('credentials not changed and not expired, directly return');
			return Promise.resolve(cred);
		}

		logger.debug('need to get a new credential or refresh the existing one');

		// Some use-cases don't require Auth for signing in, but use Credentials for guest users (e.g. Analytics)
		// Prefer locally scoped `Auth`, but fallback to registered `Amplify.Auth` global otherwise.
		const { Auth = Amplify.Auth } = this;

		if (!Auth || typeof Auth.currentUserCredentials !== 'function') {
			// If Auth module is not imported, do a best effort to get guest credentials
			return this._setCredentialsForGuest();
		}

		if (!this._isExpired(cred) && this._isPastTTL()) {
			logger.debug('ttl has passed but token is not yet expired');
			try {
				const user = await Auth.currentUserPoolUser();
				const session = await Auth.currentSession();
				const refreshToken = session.refreshToken;
				const refreshRequest = new Promise((res, rej) => {
					user.refreshSession(refreshToken, (err, data) => {
						return err ? rej(err) : res(data);
					});
				});
				await refreshRequest; // note that rejections will be caught and handled in the catch block.
			} catch (err) {
				// should not throw because user might just be on guest access or is authenticated through federation
				logger.debug('Error attempting to refreshing the session', err);
			}
		}
		return Auth.currentUserCredentials();
	}

	public refreshFederatedToken(federatedInfo) {
		logger.debug('Getting federated credentials');
		const { provider, user, token, identity_id } = federatedInfo;
		let { expires_at } = federatedInfo;

		// Make sure expires_at is in millis
		expires_at =
			new Date(expires_at).getFullYear() === 1970
				? expires_at * 1000
				: expires_at;

		const that = this;
		logger.debug('checking if federated jwt token expired');
		if (expires_at > new Date().getTime()) {
			// if not expired
			logger.debug('token not expired');
			return this._setCredentialsFromFederation({
				provider,
				token,
				user,
				identity_id,
				expires_at,
			});
		} else {
			// if refresh handler exists
			if (
				that._refreshHandlers[provider] &&
				typeof that._refreshHandlers[provider] === 'function'
			) {
				logger.debug('getting refreshed jwt token from federation provider');
				return this._providerRefreshWithRetry({
					refreshHandler: that._refreshHandlers[provider],
					provider,
					user,
				});
			} else {
				logger.debug('no refresh handler for provider:', provider);
				this.clear();
				return Promise.reject('no refresh handler for provider');
			}
		}
	}

	private _providerRefreshWithRetry({ refreshHandler, provider, user }) {
		const MAX_DELAY_MS = 10 * 1000;
		// refreshHandler will retry network errors, otherwise it will
		// return NonRetryableError to break out of jitteredExponentialRetry
		return jitteredExponentialRetry<any>(refreshHandler, [], MAX_DELAY_MS)
			.then(data => {
				logger.debug('refresh federated token sucessfully', data);
				return this._setCredentialsFromFederation({
					provider,
					token: data.token,
					user,
					identity_id: data.identity_id,
					expires_at: data.expires_at,
				});
			})
			.catch(e => {
				const isNetworkError =
					typeof e === 'string' &&
					e.toLowerCase().lastIndexOf('network error', e.length) === 0;

				if (!isNetworkError) {
					this.clear();
				}

				logger.debug('refresh federated token failed', e);
				return Promise.reject('refreshing federation token failed: ' + e);
			});
	}

	private _isExpired(credentials): boolean {
		if (!credentials) {
			logger.debug('no credentials for expiration check');
			return true;
		}
		logger.debug('are these credentials expired?', credentials);
		const ts = Date.now();

		/* returns date object.
			https://github.com/aws/aws-sdk-js-v3/blob/v1.0.0-beta.1/packages/types/src/credentials.ts#L26
		*/
		const { expiration } = credentials;
		return expiration.getTime() <= ts;
	}

	private _isPastTTL(): boolean {
		return this._nextCredentialsRefresh <= Date.now();
	}

	private async _setCredentialsForGuest() {
		logger.debug('setting credentials for guest');
		if (!this._config?.identityPoolId) {
			// If Credentials are not configured thru Auth module,
			// doing best effort to check if the library was configured
			this._config = Object.assign(
				{},
				this._config,
				parseAWSExports(this._config || {}).Auth
			);
		}
		const { identityPoolId, region, mandatorySignIn, identityPoolRegion } =
			this._config;

		if (mandatorySignIn) {
			return Promise.reject(
				'cannot get guest credentials when mandatory signin enabled'
			);
		}

		if (!identityPoolId) {
			logger.debug(
				'No Cognito Identity pool provided for unauthenticated access'
			);
			return Promise.reject(
				'No Cognito Identity pool provided for unauthenticated access'
			);
		}

		if (!identityPoolRegion && !region) {
			logger.debug('region is not configured for getting the credentials');
			return Promise.reject(
				'region is not configured for getting the credentials'
			);
		}

		const identityId = (this._identityId = await this._getGuestIdentityId());

		const cognitoConfig = { region: identityPoolRegion ?? region };

		const guestCredentialsProvider = async () => {
			if (!identityId) {
				const { IdentityId } = await getId(cognitoConfig, {
					IdentityPoolId: identityPoolId,
				});
				this._identityId = IdentityId;
			}
			const { Credentials } = await getCredentialsForIdentity(cognitoConfig, {
				IdentityId: this._identityId,
			});
			return {
				identityId: this._identityId,
				accessKeyId: Credentials.AccessKeyId,
				secretAccessKey: Credentials.SecretKey,
				sessionToken: Credentials.SessionToken,
				expiration: Credentials.Expiration,
			};
		};
		let credentials = guestCredentialsProvider().catch(async err => {
			throw err;
		});

		return this._loadCredentials(credentials, 'guest', false, null)
			.then(res => {
				return res;
			})
			.catch(async e => {
				// If identity id is deleted in the console, we make one attempt to recreate it
				// and remove existing id from cache.
				if (
					e.name === 'ResourceNotFoundException' &&
					e.message === `Identity '${identityId}' not found.`
				) {
					logger.debug('Failed to load guest credentials');
					await this._removeGuestIdentityId();

					const guestCredentialsProvider = async () => {
						const { IdentityId } = await getId(cognitoConfig, {
							IdentityPoolId: identityPoolId,
						});
						this._identityId = IdentityId;
						const { Credentials } = await getCredentialsForIdentity(
							cognitoConfig,
							{
								IdentityId,
							}
						);

						return {
							identityId: IdentityId,
							accessKeyId: Credentials.AccessKeyId,
							secretAccessKey: Credentials.SecretKey,
							sessionToken: Credentials.SessionToken,
							expiration: Credentials.Expiration,
						};
					};

					credentials = guestCredentialsProvider().catch(async err => {
						throw err;
					});

					return this._loadCredentials(credentials, 'guest', false, null);
				} else {
					return e;
				}
			});
	}

	private _setCredentialsFromFederation(params) {
		const { provider, token } = params;
		let { identity_id } = params;
		const domains = {
			google: 'accounts.google.com',
			facebook: 'graph.facebook.com',
			amazon: 'www.amazon.com',
			developer: 'cognito-identity.amazonaws.com',
		};

		// Use custom provider url instead of the predefined ones
		const domain = domains[provider] || provider;
		if (!domain) {
			return Promise.reject('You must specify a federated provider');
		}

		const logins = {};
		logins[domain] = token;

		const { identityPoolId, region, identityPoolRegion } = this._config;
		if (!identityPoolId) {
			logger.debug('No Cognito Federated Identity pool provided');
			return Promise.reject('No Cognito Federated Identity pool provided');
		}
		if (!identityPoolRegion && !region) {
			logger.debug('region is not configured for getting the credentials');
			return Promise.reject(
				'region is not configured for getting the credentials'
			);
		}

		const cognitoConfig = { region: identityPoolRegion ?? region };

		const authenticatedCredentialsProvider = async () => {
			if (!identity_id) {
				const { IdentityId } = await getId(cognitoConfig, {
					IdentityPoolId: identityPoolId,
					Logins: logins,
				});
				identity_id = IdentityId;
			}
			const { Credentials } = await getCredentialsForIdentity(cognitoConfig, {
				IdentityId: identity_id,
				Logins: logins,
			});
			return {
				identityId: identity_id,
				accessKeyId: Credentials.AccessKeyId,
				secretAccessKey: Credentials.SecretKey,
				sessionToken: Credentials.SessionToken,
				expiration: Credentials.Expiration,
			};
		};

		const credentials = authenticatedCredentialsProvider().catch(async err => {
			throw err;
		});

		return this._loadCredentials(credentials, 'federated', true, params);
	}

	private _setCredentialsFromSession(session): Promise<ICredentials> {
		logger.debug('set credentials from session');
		const idToken = session.getIdToken().getJwtToken();
		const { region, userPoolId, identityPoolId, identityPoolRegion } =
			this._config;
		if (!identityPoolId) {
			logger.debug('No Cognito Federated Identity pool provided');
			return Promise.reject('No Cognito Federated Identity pool provided');
		}
		if (!identityPoolRegion && !region) {
			logger.debug('region is not configured for getting the credentials');
			return Promise.reject(
				'region is not configured for getting the credentials'
			);
		}
		const key = 'cognito-idp.' + region + '.amazonaws.com/' + userPoolId;
		const logins = {};
		logins[key] = idToken;

		const cognitoConfig = { region: identityPoolRegion ?? region };

		/* 
			Retreiving identityId with GetIdCommand to mimic the behavior in the following code in aws-sdk-v3:
			https://git.io/JeDxU

			Note: Retreive identityId from CredentialsProvider once aws-sdk-js v3 supports this.
		*/
		const credentialsProvider = async () => {
			// try to fetch the local stored guest identity, if found, we will associate it with the logins
			const guestIdentityId = await this._getGuestIdentityId();

			let generatedOrRetrievedIdentityId;
			if (!guestIdentityId) {
				// for a first-time user, this will return a brand new identity
				// for a returning user, this will retrieve the previous identity assocaited with the logins
				const { IdentityId } = await getId(cognitoConfig, {
					IdentityPoolId: identityPoolId,
					Logins: logins,
				});
				generatedOrRetrievedIdentityId = IdentityId;
			}

			const {
				Credentials: { AccessKeyId, Expiration, SecretKey, SessionToken },
				// single source of truth for the primary identity associated with the logins
				// only if a guest identity is used for a first-time user, that guest identity will become its primary identity
				IdentityId: primaryIdentityId,
			} = await getCredentialsForIdentity(cognitoConfig, {
				IdentityId: guestIdentityId || generatedOrRetrievedIdentityId,
				Logins: logins,
			});

			this._identityId = primaryIdentityId;
			if (guestIdentityId) {
				// if guestIdentity is found and used by GetCredentialsForIdentity
				// it will be linked to the logins provided, and disqualified as an unauth identity
				logger.debug(
					`The guest identity ${guestIdentityId} has been successfully linked to the logins`
				);
				if (guestIdentityId === primaryIdentityId) {
					logger.debug(
						`The guest identity ${guestIdentityId} has become the primary identity`
					);
				}
				// remove it from local storage to avoid being used as a guest Identity by _setCredentialsForGuest
				await this._removeGuestIdentityId();
			}

			// https://github.com/aws/aws-sdk-js-v3/blob/main/packages/credential-provider-cognito-identity/src/fromCognitoIdentity.ts#L40
			return {
				accessKeyId: AccessKeyId,
				secretAccessKey: SecretKey,
				sessionToken: SessionToken,
				expiration: Expiration,
				identityId: primaryIdentityId,
			};
		};

		const credentials = credentialsProvider().catch(async err => {
			throw err;
		});

		return this._loadCredentials(credentials, 'userPool', true, null);
	}

	private _loadCredentials(
		credentials,
		source,
		authenticated,
		info
	): Promise<ICredentials> {
		const that = this;
		return new Promise((res, rej) => {
			credentials
				.then(async credentials => {
					logger.debug('Load credentials successfully', credentials);
					if (this._identityId && !credentials.identityId) {
						credentials['identityId'] = this._identityId;
					}

					that._credentials = credentials;
					that._credentials.authenticated = authenticated;
					that._credentials_source = source;
					that._nextCredentialsRefresh = new Date().getTime() + CREDENTIALS_TTL;
					if (source === 'federated') {
						const user = Object.assign(
							{ id: this._credentials.identityId },
							info.user
						);
						const { provider, token, expires_at, identity_id } = info;
						try {
							this._storage.setItem(
								'aws-amplify-federatedInfo',
								JSON.stringify({
									provider,
									token,
									user,
									expires_at,
									identity_id,
								})
							);
						} catch (e) {
							logger.debug('Failed to put federated info into auth storage', e);
						}
					}
					if (source === 'guest') {
						await this._setGuestIdentityId(credentials.identityId);
					}
					res(that._credentials);
					return;
				})
				.catch(err => {
					if (err) {
						logger.debug('Failed to load credentials', credentials);
						logger.debug('Error loading credentials', err);
						rej(err);
						return;
					}
				});
		});
	}

	public set(params, source): Promise<ICredentials> {
		if (source === 'session') {
			return this._setCredentialsFromSession(params);
		} else if (source === 'federation') {
			return this._setCredentialsFromFederation(params);
		} else if (source === 'guest') {
			return this._setCredentialsForGuest();
		} else {
			logger.debug('no source specified for setting credentials');
			return Promise.reject('invalid source');
		}
	}

	public async clear() {
		this._credentials = null;
		this._credentials_source = null;
		logger.debug('removing aws-amplify-federatedInfo from storage');
		this._storage.removeItem('aws-amplify-federatedInfo');
	}

	/* operations on local stored guest identity */
	private async _getGuestIdentityId(): Promise<string> {
		const { identityPoolId } = this._config;
		try {
			await this._storageSync;
			return this._storage.getItem(
				this._getCognitoIdentityIdStorageKey(identityPoolId)
			);
		} catch (e) {
			logger.debug('Failed to get the cached guest identityId', e);
		}
	}

	private async _setGuestIdentityId(identityId: string) {
		const { identityPoolId } = this._config;
		try {
			await this._storageSync;
			this._storage.setItem(
				this._getCognitoIdentityIdStorageKey(identityPoolId),
				identityId
			);
		} catch (e) {
			logger.debug('Failed to cache guest identityId', e);
		}
	}

	private async _removeGuestIdentityId() {
		const { identityPoolId } = this._config;
		logger.debug(
			`removing ${this._getCognitoIdentityIdStorageKey(
				identityPoolId
			)} from storage`
		);
		this._storage.removeItem(
			this._getCognitoIdentityIdStorageKey(identityPoolId)
		);
	}

	/**
	 * Compact version of credentials
	 * @param {Object} credentials
	 * @return {Object} - Credentials
	 */
	public shear(credentials) {
		return {
			accessKeyId: credentials.accessKeyId,
			sessionToken: credentials.sessionToken,
			secretAccessKey: credentials.secretAccessKey,
			identityId: credentials.identityId,
			authenticated: credentials.authenticated,
		};
	}
}

export const Credentials = new CredentialsClass(null);

Amplify.register(Credentials);