使用 Firebase 电话号码验证功能在 Android 上进行 Firebase 身份验证

在 Firebase PNV 公开预览版中，Firebase Authentication 无法直接接受 Firebase PNV 令牌进行登录；不过，您可以使用 Firebase Authentication 的自定义身份验证功能，让用户通过 Firebase PNV 登录。

创建令牌交换端点

在 Firebase 中实现自定义身份验证解决方案的关键步骤是创建一个可以接收 Firebase PNV 令牌、验证该令牌，然后签发 Firebase 自定义身份验证令牌的端点。然后，您的应用可以使用此自定义令牌来登录用户。

此端点可以托管在任何平台上，但在以下示例中，该端点是使用 Cloud Functions for Firebase 托管的：

Node.js

import { JwtVerifier } from "aws-jwt-verify";
import { getApp } from "firebase-admin/app";
import { getAuth, UserRecord } from "firebase-admin/auth";
import { onRequest } from "firebase-functions/https";

// Because we're deploying to Cloud Functions for Firebase, admin credentials
// are automatically available.
const app = getApp();
const authAdmin = getAuth(app);

// Find your Firebase project number in the Firebase console.
const FIREBASE_PROJECT_NUMBER = "123456789";

// The issuer and audience claims of the FPNV token are specific to your
// project.
const issuer = `https://fpnv.googleapis.com/projects/${FIREBASE_PROJECT_NUMBER}`;
const audience = `https://fpnv.googleapis.com/projects/${FIREBASE_PROJECT_NUMBER}`;

// The JWKS URL contains the current public signing keys for FPNV tokens.
const jwksUri = "https://fpnv.googleapis.com/v1beta/jwks";

// Configure a JWT verifier to check the following:
// - The token is signed by Google
// - The issuer and audience claims match your project
// - The token has not yet expired (default begavior)
const fpnvVerifier = JwtVerifier.create({ issuer, audience, jwksUri });

// This Cloud Function is your token exchange endpoint. You pass the endpoint an
// FPNV token, and the Cloud Function verifies it and exchanges it for a
// Firebase Auth token corresponding to the same user.
export const signInWithFpnv = onRequest(async (req, res) => {
    // Get the FPNV token from the request body.
    const fpnvToken = req.body?;
    if (!fpnvToken) {
        res.sendStatus(400);
        return;
    }

    let verifiedPhoneNumber;
    try {
        // Attempt to verify the token using the verifier configured above.
        const verifiedPayload = await fpnvVerifier.verify(fpnvToken);

        // If verification succeeds, the subject claim of the token contains the
        // verified phone number.
        verifiedPhoneNumber = verifiedPayload.sub;
    } catch {
        // If verification fails, reject the token.
        res.sendStatus(403);
        return;
    }

    // Now that you have a verified phone number, look it up in your Firebase
    // project's user database.
    let user: UserRecord;
    try {
        // If a user account already exists with the phone number, retrieve it.
        user = await authAdmin.getUserByPhoneNumber(verifiedPhoneNumber);
    } catch {
        // Otherwise, create a new user account using the phone number.
        user = await authAdmin.createUser({phoneNumber: verifiedPhoneNumber});
    }

    // Finally, mint a Firebase custom auth token containing the UID of the user
    // you looked up or created. Return this token to the caller.
    const authToken = await authAdmin.createCustomToken(user.uid);
    res.status(200).send(authToken);
    return;
});

使用自定义身份验证令牌登录

部署端点后，请按照以下步骤让用户登录 Firebase：

  1. 使用Firebase Phone Number Verification使用入门页面上所述的流程获取 Firebase PNV 令牌。

  2. 将此令牌传递给 Cloud Functions 端点。该端点将向您的应用返回自定义身份验证令牌，您可以将该令牌传递给 signInWithCustomToken()。

    例如，您可以使用 Retrofit 编写一个与 Firebase 的 signin 方法具有类似接口的方法 signInWithFpnvToken()：

    Kotlin 

    class FpnvSigninExample {
    interface FPNVTokenExchangeService {
        @POST("signInWithFpnv")
        suspend fun signInWithFpnv(@Body fpnvToken: String): String
    }

    val retrofit = Retrofit.Builder()
        .baseUrl("https://example-project.cloudfunctions.net/")
        .build()
    val service: FPNVTokenExchangeService = retrofit.create(FPNVTokenExchangeService::class.java)

    suspend fun signInWithFpnvToken(fpnvToken: String): Task<AuthResult?> = coroutineScope {
        val authToken = service.signInWithFpnv(fpnvToken)
        return@coroutineScope Firebase.auth.signInWithCustomToken(authToken)
    }
}