@loopback/authentication

@loopback/authentication

A LoopBack component for authentication support.

This is a reference implementation showing how to implement an authentication component, it is not production ready.

Overview

The component demonstrates how to leverage Passport module and extension points provided by LoopBack Next to implement an authentication layer.

Installation

npm install --save @loopback/authentication

Basic use

Start by decorating your controller methods with @authenticate to require the request to be authenticated.

// controllers/my-controller.ts
import {UserProfile, authenticate, AuthenticationBindings} from '@loopback/authentication';
import {inject} from '@loopback/core';
import {get} from '@loopback/rest';

export class MyController {
  constructor(@inject(AuthenticationBindings.CURRENT_USER) private user: UserProfile) {}

  @authenticate('BasicStrategy')
  @get('/whoAmI')
  whoAmI() {
    return this.user.id;
  }
}

Next, implement a Strategy provider to map strategy names specified in @authenticate decorators into Passport Strategy instances. Remember to install passport, passport-http, @types/passport, and @types/passport-http modules beforehand.

// providers/auth-strategy.ts
import {
  inject,
  Provider,
  ValueOrPromise,
} from '@loopback/context';
import {
  AuthenticationBindings,
  AuthenticationMetadata,
} from '@loopback/authentication';

import {Strategy} from 'passport';
import {BasicStrategy} from 'passport-http';

export class MyAuthStrategyProvider implements Provider<Strategy | undefined> {
  constructor(
    @inject(AuthenticationBindings.METADATA)
    private metadata: AuthenticationMetadata,
  ) {}

  value() : ValueOrPromise<Strategy | undefined> {

    // The function was not decorated, so we shouldn't attempt authentication
    if (!this.metadata) {
      return undefined;
    }

    const name = this.metadata.strategy;
    if (name === 'BasicStrategy') {
      return new BasicStrategy(this.verify);
    } else {
      return Promise.reject(`The strategy ${name} is not available.`);
    }
  }

  verify(username: string, password: string, cb: Function) {
    // find user by name & password
    // call cb(null, false) when user not found
    // call cb(null, userProfile) when user is authenticated
  }
}

In order to perform authentication, we need to implement a custom Sequence invoking the authentication at the right time during the request handling.

// sequence.ts
import {
  inject,
} from '@loopback/core';

import {
  FindRoute,
  InvokeMethod,
  ParsedRequest,
  ParseParams,
  Reject,
  Send,
  ServerResponse,
  SequenceHandler,
  RestBindings,
} from '@loopback/rest';

import {
  AuthenticateFn,
  AuthenticationBindings,
} from '@loopback/authentication';

const SequenceActions = RestBindings.SequenceActions;

export class MySequence implements SequenceHandler {
  constructor(
    @inject(SequenceActions.FIND_ROUTE) protected findRoute: FindRoute,
    @inject(SequenceActions.PARSE_PARAMS) protected parseParams: ParseParams,
    @inject(SequenceActions.INVOKE_METHOD) protected invoke: InvokeMethod,
    @inject(SequenceActions.SEND) protected send: Send,
    @inject(SequenceActions.REJECT) protected reject: Reject,
    @inject(AuthenticationBindings.AUTH_ACTION)
    protected authenticateRequest: AuthenticateFn,
  ) {}

  async handle(req: ParsedRequest, res: ServerResponse) {
    try {
      const route = this.findRoute(req);

      // This is the important line added to the default sequence implementation
      await this.authenticateRequest(req);

      const args = await this.parseParams(req, route);
      const result = await this.invoke(route, args);
      this.send(res, result);
    } catch (err) {
      this.reject(res, req, err);
    }
  }
}

Finally, put it all together in your application class:

import {Application} from '@loopback/core';
import {
  AuthenticationComponent,
  AuthenticationBindings,
} from '@loopback/authentication';
import {RestComponent, RestServer} from '@loopback/rest';
import {MyAuthStrategyProvider} from './providers/auth-strategy';
import {MyController} from './controllers/my-controller';
import {MySequence} from './sequence';

class MyApp extends Application {
  constructor() {
    super({
      components: [AuthenticationComponent, RestComponent],
      rest: {
        sequence: MySequence
      },
      controllers: [MyController],
    });

    this.controller(MyController);
  }

  async start() {
    const server = await this.getServer(RestServer);

    server.bind(AuthenticationBindings.STRATEGY)
    .toProvider(MyAuthStrategyProvider);
    await super.start();

    console.log(`REST server running on port: ${server.getSync('rest.port')}`);
  }
}

You can try your authentication component by using your favourite REST client and by setting the authorization header. Here is an example of what your request might look like using curl:

curl -X GET \
  http://localhost:3000/whoami \
  -H 'authorization: Basic Zm9vOmJhcg=='

Related resources

For more info about passport, see passport.js.

Contributions

• Guidelines
• Join the team

Tests

run npm test from the root folder.

Contributors

See all contributors.

License

MIT