Firebase Realtime Database returns 401 when trying to authenticate? - firebase

Question

I am using REST API in my app to communicate with a Firebase RTDB, and trying to use a Google Access Token to authenticate my requests.
My issue is that with even the most permissive Rules on the database, I get HTTP error 401 in response to queries that try to authenticate.
For example, say I try to put some data in my database with the following command, I get 401 in return (all the values within < > are placeholders):
curl -XPUT -d '{ "UserID" : "<GOOGLE_UID>", "UserName" : "Clicksurfer", "CompletionMoves" : 8, "CompletionTime" : 16.21979 }' https://<FIREBASE_URL>.firebaseio.com/Level2/<GOOGLE_UID>.json/?access_token=<GOOGLE_ACCESS_TOKEN>
401
The strangest part is, when I abandon the use of access token altogether the query works:
curl -XPUT -d '{ "UserID" : "<GOOGLE_UID>", "UserName" : "Clicksurfer", "CompletionMoves" : 8, "CompletionTime" : 16.21979 }' https://<FIREBASE_URL>.firebaseio.com/Level2/<GOOGLE_UID>.json
200
As I said, I am currently using the most permissive rules for debugging:
{
"rules": {
".read": true,
".write": true
}
}
Any idea what might be causing this? Thanks in advance
EDIT:
I use the Google Play Games plugin for Unity in my project, among other things to get the AuthCode.
In order to do this, I needed to do a couple of things:
When building the config for Google Play Games during startup, I made sure to call the RequestServerAuthCode(false) method
Have the user login after Google Play Games sets up
Make sure that the relevant ClientID was supplied to Unity (in this case, it is a web client that has auth permissions on my Firebase rtdb).
This all looks like this:
public class GPGSAuthentication : MonoBehaviour
{
public static PlayGamesPlatform platform;
void Start()
{
if (platform == null)
{
PlayGamesClientConfiguration config = new PlayGamesClientConfiguration.Builder().RequestServerAuthCode(false).Build();
PlayGamesPlatform.InitializeInstance(config);
PlayGamesPlatform.DebugLogEnabled = true;
platform = PlayGamesPlatform.Activate();
}
Social.Active.localUser.Authenticate(success =>
{
if (success)
{
Debug.Log("GSPS - Logged in successfully");
}
else
{
Debug.Log("GSPS - Falied to login");
}
});
}
}
Now that we've done this, we can call PlayGamesPlatform.Instance.GetServerAuthCode() in order to get the AuthCode.
I traded in my AuthCode for an Access Token by sending a POST request to https://www.googleapis.com/oauth2/v4/token. In my query, I supply 4 fields:
client_id, which has the ID of the previously used client (where we got the AuthCode from).
client_secret, which has the correlating secret.
grant_type, which is always with the value "authorization_code"
code, which has the value of the AuthCode we got.
In response, I get a 200 response with 4 parameters:
access_token, the token I (fail to) use when authenticating against my Firebase rtdb.
token_type, the type of the aforementioned token.
expires_in, the amount of time before the token expires (I presume in seconds unit)
refresh_token, a token which can be used in order to get a new access_token without having to keep the Google user connected.
I then supply this access_token value to the queries I send to my DB, and promptly get the 401 error.