Is there a way to generate a firebase email verification link before a user is actually signed up? - firebase

Question

I am currently implementing a MFA system with Firebase Authentication & Google Authenticator.
Since my users are not allowed to authenticate with a non-verified email address, I'd like to prevent them from signing-in if their Firebase Authentication email_verified is set to false. To do that, I am using Google Cloud Identity Provider blocking functions, this works perfectly.
However, when it comes to the registration beforeCreate blocking function hook, I can't find a way to generate an email verification link for the user currently being created, the documentation says:
Requiring email verification on registration The following example
shows how to require a user to verify their email after registering:
export.beforeCreate = authClient.functions().beforeCreateHandler((user, context) => {
const locale = context.locale;
if (user.email && !user.emailVerified) {
// Send custom email verification on sign-up.
return admin.auth()
.generateEmailVerificationLink(user.email)
.then((link) => {
return sendCustomVerificationEmail(
user.email, link, locale
);
});
}
});
export.beforeSignIn = authClient.functions().beforeSignInHandler((user, context) => {
if (user.email && !user.emailVerified) {
throw new gcipCloudFunctions.https.HttpsError(
'invalid-argument', `"${user.email}" needs to be verified before access is granted.`);
}
});
However, as far as I understand, generateEmailVerificationLink() can only be called to generate email verification link of an existing Firebase Authentication user. At this stage (while running beforeCreate blocking function), the user is not created yet.
Now I am wondering, I am missing something or is the Google documentation wrong?

Answer 1

No.
User data is created upon registration in the database.
Then, you may send an Email-Verification with a link automatically.
This Email-Verification just updates the field emaiVerified of said user data.
If you want to prevent users with unverified Emails from logging in, you need to adjust your Login page and check whether emaiVerified is true.
Important: Google will sign in a user right upon registration whether the email is verified or not, as this is the expected behavior from the perspective of a user. Email verification is ensured on the second, manual login.
(Also, please do not screenshot code.)

Answer 2

You can let a user sign in via email link at first, and call firebase.User.updatePassword() to set its password.
I am using Angular-Firebase, this is the logic code.
if (this.fireAuth.isSignInWithEmailLink(this.router.url)) {
const email = this.storage.get(SIGN_IN_EMAIL_KEY) as string;
this.storage.delete(SIGN_IN_EMAIL_KEY);
this.emailVerified = true;
this.accountCtrl.setValue(email);
from(this.fireAuth.signInWithEmailLink(email, this.router.url)).pipe(
catchError((error: FirebaseError) => {
const notification = this.notification;
notification.openError(notification.stripMessage(error.message));
this.emailVerified = false;
return of(null);
}),
filter((result) => !!result)
).subscribe((credential) => {
this.user = credential.user;
});
}
const notification = this.notification;
const info = form.value;
this.requesting = true;
form.control.disable();
(this.emailVerified ? from(this.user.updatePassword(info.password)) : from(this.fireAuth.signInWithEmailLink(info.account))).pipe(
catchError((error: FirebaseError) => {
switch (error.code) {
case AUTH_ERROR_CODES_MAP_DO_NOT_USE_INTERNALLY.POPUP_CLOSED_BY_USER:
break;
default:
console.log(error.code);
notification.openError(notification.stripMessage(error.message));
}
this.requesting = false;
form.control.enable();
return of(null);
}),
filter((result) => !!result)
).subscribe((result: firebase.auth.UserCredential) => {
if (this.emailVerified) {
if (result.user) {
notification.openError(`注册成功。`);
this.router.navigateByUrl(this.authService.redirectUrl || '');
} else {
notification.openError(`注册失败。`);
this.requesting = false;
form.control.enable();
}
} else {
this.storage.set(SIGN_IN_EMAIL_KEY, info.account);
}
});

Answer 3

Mate, if database won't create a new user using his email and password, and you send him email verification which will create his account, how the heck database will know his password? If it didn't create his account in the first step? Stop overthinking and just secure database using rules and routes in application if you don't want user to read some data while he didn't confirm email address.
It is that simple:
match /secretCollection/{docId} {
allow read, write: if isEmailVerified()
}
function isEmailVerified() {
return request.auth.token.email_verified
}

Answer 4

I think the blocking function documentation is wrong.
beforeCreate: "Triggers before a new user is saved to the Firebase Authentication database, and before a token is returned to your client app."
generateEmailVerificationLink: "To generate an email verification link, provide the existing user’s unverified email... The operation will resolve with the email action link. The email used must belong to an existing user."
Has anyone come up with a work around while still using blocking functions?
Using firebase rules to check for verification isn't helpful if the goal is to perform some action in the blocking function, such as setting custom claims.