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typescript - 如何在 LoopBack4 中处理特定请求/会话数据

问题描述

目前我在我们的 LoopBack4 应用程序中遇到了一个问题。我们有一些控制器。我们正在使用 JWT 进行授权。在令牌有效负载中，我们存储了为请求用户授予的权限列表。此外，我们添加了一个 AuthorizationInterceptor 来检查权限。

我犯了一个错误，将令牌数据写入静态变量并从应用程序内的服务和其他位置请求它。如果有并发请求传入，则一个请求会覆盖另一请求的令牌。请求 A 现在正在使用请求 B 的权限。

问题：

应用：

每个控制器：

export class MiscController
{
    constructor(@inject(AServiceBindings.VALUE) public aService: AService) {}

    @get('/hasright', {})
    @authenticate('jwt', {"required":[1,2,3]}) // this gets checked by AuthorizationInterceptor
    async getVersion(): Promise<object>
    {
        return {hasRight: JWTService.checkRight(4)};
    }
}

jwt-服务：

export class JWTService implements TokenService
{
    static AuthToken: Authtoken|null;
    static rights: number[];

    // constructor ...

    /** A method to check rights */
    static hasRight(rightId: number): boolean
    {
        return inArray(rightId, JWTService.rights);
    }

    async verifyToken(token: string): Promise<UserProfile>
    {
        // verify the token ...

        // write the Tokendata to static variables
        JWTService.AuthToken = authtoken;
        JWTService.rights = rightIds;

        return userProfile;
    }
}

export const JWTServiceBindings = {
    VALUE: BindingKey.create<JWTService>("services.JWTService")
};

授权拦截器.ts

@globalInterceptor('', {tags: {name: 'authorize'}})
export class AuthorizationInterceptor implements Provider<Interceptor>
{
    constructor(
        @inject(AuthenticationBindings.METADATA) public metadata: AuthenticationMetadata,
        @inject(TokenServiceBindings.USER_PERMISSIONS) protected checkPermissions: UserPermissionsFn,
        @inject.getter(AuthenticationBindings.CURRENT_USER) public getCurrentUser: Getter<MyUserProfile>
    ) {}

    /**
     * This method is used by LoopBack context to produce an interceptor function
     * for the binding.
     *
     * @returns An interceptor function
     */
    value()
    {
        return this.intercept.bind(this);
    }

    /**
     * The logic to intercept an invocation
     * @param invocationCtx - Invocation context
     * @param next - A function to invoke next interceptor or the target method
     */
    async intercept(invocationCtx: InvocationContext, next: () => ValueOrPromise<InvocationResult>)
    {
        if(!this.metadata)
        {
            return next();
        }

        const requiredPermissions = this.metadata.options as RequiredPermissions;
        const user                = await this.getCurrentUser();

        if(!this.checkPermissions(user.permissions, requiredPermissions))
        {
            throw new HttpErrors.Forbidden('Permission denied! You do not have the needed right to request this function.');
        }

        return next();
    }
}

JWT身份验证策略

export class JWTAuthenticationStrategy implements AuthenticationStrategy
{
    name = 'jwt';

    constructor(@inject(JWTServiceBindings.VALUE) public tokenService: JWTService) {}

    async authenticate(request: Request): Promise<UserProfile | undefined>
    {
        const token: string = this.extractCredentials(request);

        return this.tokenService.verifyToken(token);
    }

    // extract credentials etc ...
}

应用程序.ts

export class MyApplication extends BootMixin(ServiceMixin(RepositoryMixin(RestApplication)))
{
    constructor(options: ApplicationConfig = {})
    {
        super(options);

        // Bind authentication component related elements
        this.component(AuthenticationComponent);

        registerAuthenticationStrategy(this, JWTAuthenticationStrategy);
        this.bind(JWTServiceBindings.VALUE).toClass(JWTService);
        this.bind(TokenServiceBindings.USER_PERMISSIONS).toProvider(UserPermissionsProvider);
        this.bind(TokenServiceBindings.TOKEN_SECRET).to(TokenServiceConstants.TOKEN_SECRET_VALUE);

        // Set up the custom sequence
        this.sequence(MySequence);

        // many more bindings and other stuff to do ...
    }
}

序列.ts

export class MySequence implements SequenceHandler
{
    // constructor ...

    async handle(context: RequestContext)
    {
        // const session = this.restoreSession(context); // restoreSession is not a function.

        try
        {
            const {request, response} = context;

            const route = this.findRoute(request);

            // call authentication action
            await this.authenticateRequest(request);
            userId = getMyUserId(); // using helper method

            // Authentication successful, proceed to invoke controller
            const args   = await this.parseParams(request, route);
            const result = await this.invoke(route, args);
            this.send(response, result);
        }
        catch(err)
        {
            this.reject(context, err);
        }
        finally
        {
            // some action using userId p.e. ...
        }
    }
}

helper.ts // 一个包含小函数的简单文件

export function getMyUserId(): number
{
    return ((JWTService.AuthToken && JWTService.AuthToken.UserId) || 0);
}

最重要的是，我们已经实现了一些服务来处理大事。我现在需要的是一种解决方案来访问服务和应用程序其他部分中的用户数据，例如授权用户的令牌。我必须在哪里以及如何放置令牌？

我在 StackOverflow 和 GitHub 上找到了参考资料： How to use stateful requests in Loopback 4? -> https://github.com/strongloop/loopback-next/issues/1863

两者都有解释，我必须添加const session = this.restoreSession(context);到自己的 sequence.ts 中。我已经做到了，但是 restoreSession 不是一个函数。

我还发现了使用包 express-session 的建议。这在这里没有帮助，因为我们的客户端无法存储 cookie。

标签： typescriptexpressloopbackjsloopback4

解决方案

我找到了一个解决方案，基于此文档：https ://github.com/strongloop/loopback-next/blob/607dc0a3550880437568a36f3049e1de66ec73ae/docs/site/Context.md#request-level-context-request

我做了什么？

  1. 在 sequence.ts 中绑定基于上下文的值
export class MySequence implements SequenceHandler
{
    // constructor ...

    async handle(context: RequestContext)
    {
        try
        {
            const {request, response} = context;

            const route = this.findRoute(request);

            // call authentication action
            const userProfile = await this.authenticateRequest(request);
            // userId = getMyUserId(); is removed, due to the fact, that we now store the value in a bind method, see next lines
            context.bind('MY_USER_ID').to(userProfile.id); // this is the essential part. "MY_USER_ID" is a key and we bind a value to that key based on the context (request)

            // Authentication successful, proceed to invoke controller
            const args   = await this.parseParams(request, route);
            const result = await this.invoke(route, args);
            this.send(response, result);
        }
        catch(err)
        {
            this.reject(context, err);
        }
        finally
        {
            // some action using userId p.e. ...
        }
    }
}
  1. JWT-Service 必须从我的静态方法中清除：
export class JWTService implements TokenService
{
    // static AuthToken: Authtoken|null; // not needed anymore
    // static rights: number[]; // not needed anymore

    // constructor ...

    /** A method to check rights */
    /* this is not possible anymore
    static hasRight(rightId: number): boolean
    {
        return inArray(rightId, JWTService.rights);
    }
    */

    async verifyToken(token: string): Promise<UserProfile>
    {
        // verify the token ...

        // do not write the Tokendata to static variables
        // JWTService.AuthToken = authtoken;
        // JWTService.rights = rightIds;

        return userProfile;
    }
}
  1. 需要基于上下文的数据的控制器必须注入绑定值
export class aController
{
    constructor(
        @inject('MY_USER_ID') public authorizedUserId: number 
        // here comes the injection of the bound value from the context
    ) {}

    @get('/myuserid', {})
    @authenticate('jwt', {})
    async getVersion(): Promise<object>
    {
        return this.authorizedUserId; 
        // authorizedUserId is a variable instantiated with the constructors dependency injection
    }
}

在序列之后加载的每个控制器和每个服务（不包括 jwt-service）都能够注入绑定值并可能使用它。

这有点棘手，因为链接的文档没有完全涵盖这种方法，但毕竟它现在对我有用。如果有人有更好的解决方案，请现在告诉我！

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