Client Side:
Using the auth2 init function, you can pass the hosted_domain parameter to restrict the accounts listed on the signin popup to those matching your hosted_domain. You can see this in the documentation here: https://developers.google.com/identity/sign-in/web/reference
Server Side:
Even with a restricted client-side list you will need to verify that the id_token matches the hosted domain you specified. For some implementations this means checking the hd attribute you receive from Google after verifying the token.
Full Stack Example:
Web Code:
gapi.load('auth2', function () {
// init auth2 with your hosted_domain
// only matching accounts will show up in the list or be accepted
var auth2 = gapi.auth2.init({
client_id: "your-client-id.apps.googleusercontent.com",
hosted_domain: 'your-special-domain.example'
});
// setup your signin button
auth2.attachClickHandler(yourButtonElement, {});
// when the current user changes
auth2.currentUser.listen(function (user) {
// if the user is signed in
if (user && user.isSignedIn()) {
// validate the token on your server,
// your server will need to double check that the
// `hd` matches your specified `hosted_domain`;
validateTokenOnYourServer(user.getAuthResponse().id_token)
.then(function () {
console.log('yay');
})
.catch(function (err) {
auth2.then(function() { auth2.signOut(); });
});
}
});
});
Server Code (using googles Node.js library):
If you're not using Node.js you can view other examples here: https://developers.google.com/identity/sign-in/web/backend-auth
const GoogleAuth = require('google-auth-library');
const Auth = new GoogleAuth();
const authData = JSON.parse(fs.readFileSync(your_auth_creds_json_file));
const oauth = new Auth.OAuth2(authData.web.client_id, authData.web.client_secret);
const acceptableISSs = new Set(
['accounts.google.com', 'https://accounts.google.com']
);
const validateToken = (token) => {
return new Promise((resolve, reject) => {
if (!token) {
reject();
}
oauth.verifyIdToken(token, null, (err, ticket) => {
if (err) {
return reject(err);
}
const payload = ticket.getPayload();
const tokenIsOK = payload &&
payload.aud === authData.web.client_id &&
new Date(payload.exp * 1000) > new Date() &&
acceptableISSs.has(payload.iss) &&
payload.hd === 'your-special-domain.example';
return tokenIsOK ? resolve() : reject();
});
});
};
