Firebase Phone auth is not verifying the OTP entered - firebase

Question

I am trying to integrate phone authentication system in my flutter app. But even when I enter a wrong OTP the user gets verified and enters into the next page.
I am using Dialog box to ask for OTP
context: context,
barrierDismissible: false,
builder: (BuildContext context) {
return new AlertDialog(
title: Text('Enter sms Code'),
content: TextFormField(
controller: _smsController,
keyboardType: TextInputType.number,
textInputAction: TextInputAction.done,
decoration: InputDecoration(
hintText: 'Enter OTP', icon: Icon(Icons.perm_phone_msg)),
maxLength: 6,
maxLengthEnforced: true,
),
contentPadding: EdgeInsets.all(10.0),
actions: <Widget>[
new RaisedButton(
child: Text('Login'),
textColor: Colors.white,
onPressed: () {
_signInWithPhoneNumber(context);
})
],
);
});```
```void _signInWithPhoneNumber(BuildContext context) async {
final AuthCredential credential = await PhoneAuthProvider.getCredential(
verificationId: _verificationId,
smsCode: _smsController.text,
);
await _auth
.signInWithCredential(credential)
.then((FirebaseUser user) async {
final FirebaseUser currentUser = await _auth.currentUser();
assert(user.uid == currentUser.uid);
Navigator.of(context).pop();
Navigator.push(
context,
MaterialPageRoute(
builder: (context) => InfoScreen(_phoneNumberController.text)));
}).catchError((e) {
print(e.message);
Navigator.of(context).pop();
});
}
}```

Answer 1

You have to get same of auth to verify a OTP of firebase admin as explained here.

Answer 2

You have done the mistake with the PhoneAuthProvider
final AuthCredential credential = await PhoneAuthProvider.getCredential(
verificationId: _verificationId,
smsCode: _smsController.text,
);
Replace above code with this:
FirebaseAuth.instance
.signInWithPhoneNumber(verificationId: verificationId, smsCode: smsCode)
.then((user) {
Navigator.of(context).pushReplacementNamed('/homepage');
}).catchError((e) {
print(e);
});
Using this you can verify the phone with code. For more details please visit Here

Answer 3

I think you have to add an onCompleteListener by changing the ".then(FirebaseUser ...)" to ".addOnCompleteListener(this, new OnCompleteListener(AuthResult res) {});"
The AuthResult object has a boolean "isSuccessful()" which you can check to make sure the user entered the correct code.
I assume that Firebase returns the FirebaseUser object no matter if the code actually matches.