在 Android 上使用 Firebase 電話號碼驗證功能，透過 Firebase 進行驗證

在 Firebase PNV 公開測試版中，Firebase Authentication 無法直接接受 Firebase PNV 登入權杖，但您可以透過 Firebase Authentication 的自訂驗證功能，讓使用者透過 Firebase PNV 登入。

建立權杖交換端點

在 Firebase 中實作自訂驗證解決方案時，最重要的一步是建立端點，以便接收 Firebase PNV 權杖、驗證權杖，然後核發 Firebase 自訂驗證權杖。您的應用程式隨後可以使用這個自訂權杖登入使用者。

這個端點可代管於任何平台，但在下列範例中，端點是使用 Cloud Functions for Firebase 代管：

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;
});

使用自訂驗證權杖登入

部署端點後，請按照下列步驟將使用者登入 Firebase：

  1. 使用「開始使用 Firebase Phone Number Verification」頁面所述的流程，取得 Firebase PNV 權杖。

  2. 將這個權杖傳遞至 Cloud Functions 端點。端點會將自訂驗證權杖傳回應用程式，您可以將該權杖傳遞至 signInWithCustomToken()。

    舉例來說，您可以使用 Retrofit 編寫方法 signInWithFpnvToken()，該方法具有與 Firebase signin 方法類似的介面：

    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)
    }
}