Firebase身份验证主要在前端完成

Firebase authentication is mostly done in the front end

正确。当使用Firebase提供的SDK时，用户身份验证完全在客户端完成。

Correct. User auth is entirely done client-side when using the provided SDKs from Firebase.

但是，如果您需要进行一些特殊的身份验证，例如与LDAP / AD集成或其他一些企业恶作剧，那么你需要做自定义令牌创建客户端-s SDK将用于验证用户。

However, if you need to do some special auth, such as integrating with LDAP/AD or some other enterprise shenanigans, then you would need to do custom token creation that client-side SDKs would use to authenticate the user.

我如何获得 req.user 在后端使用Firebase吗？

How can I get req.user to work with Firebase in the back end?

你需要自己实施。流客户端将类似于：

This is something you will need to implement yourself. The flow client-side would go something like:

1. 用户执行auth客户端。
   
   
   
   
   • 默认情况下，Firebase会在 localstorage 中设置身份验证状态。请参阅身份验证状态持久性
     
   
   

1. User performs auth client-side.
   • Firebase will set auth state in localstorage by default. See Authentication State Persistence

假设您在请求标头上附加了令牌： FIREBASE_AUTH_TOKEN：abc 。请参阅 Firebase检索用户数据存储在本地存储中作为firebase：authUser：

Let's assume you attach the token on the request header: FIREBASE_AUTH_TOKEN: abc. See Firebase retrieve the user data stored in local storage as firebase:authUser:

所以在服务器端，使用 Firebase Admin SDK ，您将检索该令牌并通过 verifyIdToken 。中间件下面的快速脏示例：

So on the server side, using the Firebase Admin SDK, you will retrieve that token and verify it via verifyIdToken. Quick dirty example below of middleware:

const {auth} = require('firebase-admin');
const authService = auth();

exports.requiresAuth = async (req, res, next) => {
    const idToken = req.header('FIREBASE_AUTH_TOKEN');

    // https://firebase.google.com/docs/reference/admin/node/admin.auth.DecodedIdToken
    let decodedIdToken;

    try {
        decodedIdToken = await authService.verifyIdToken(idToken);
    } catch (error) {
        next(error);
        return;
    }

    req.user = decodedIdToken;
    next();
}

然后你会像这样使用这个中间件：

You would then use this middleware like so:

const express = require('express');
const router = express.Router();
const {requiresLogin} = require('./my-middleware.js');

router.get('/example', requiresLogin, async (req, res) => {
    console.log(req.user)
})

我希望这可以让你知道该怎么做。我暂时没有使用Firebase，上面的信息是我从文档中收集到的信息。

I hope this gives you an idea of what to do. I haven't worked with Firebase for a while and the information above is what I gathered from looking at the documentation.