Google Calender Oauth with offline access - vbscript

Question

I am trying to access the Google Calendar API using VBScript and Oauth offline access. I managed to get a refresh token and an access token, and now I want to get to the step where I actually use the API, using the following code:
sUrl="https://www.googleapis.com/calendar/v3/users/me/calendarList"
sRequest = "access_token="&accesstoken
response=HTTPPost (sUrl, sRequest)
Function HTTPPost(sUrl, sRequest)
set oHTTP = CreateObject("MSXML2.ServerXMLHTTP")
oHTTP.open "POST", sUrl,false
oHTTP.setRequestHeader "Content-Type", "application/x-www-form-urlencoded"
oHTTP.setRequestHeader "Content-Length", Len(sRequest)
oHTTP.send sRequest
HTTPPost = oHTTP.responseText
End Function
The response I get is :
{
"error": {
"errors": [
{
"domain": "global",
"reason": "authError",
"message": "Invalid Credentials",
"locationType": "header",
"location": "Authorization"
}
],
"code": 401,
"message": "Invalid Credentials"
}
}
This is even though the access token is valid - If I change sURL to https://www.googleapis.com/oauth2/v1/tokeninfo and run the script I get the following response showing a valid token:
{
"issued_to": "...",
"audience": "...,
"scope": "https://www.googleapis.com/auth/calendar",
"expires_in": 2568,
"access_type": "offline"
}
And also if I paste the URL https://www.googleapis.com/calendar/v3/users/me/calendarList?access_token=... into a browser I get a valid response from Google listing the user's calendars

Answer 1

401: Invalid Credentials
Invalid authorization header. The access token you're using is either
expired or invalid.
Access tokens are only good for 1 hour. After the hour is up the access token has expired and you need to use the refresh token to request a new one.
The raw code to get a new acesss token looks something like this. the key is grant_type=refresh_token this tells the authentication server you are requesting a new token.
https://accounts.google.com/o/oauth2/token
client_id={ClientId}.apps.googleusercontent.com&client_secret={ClientSecret}&refresh_token=1/ffYmfI0sjR54Ft9oupubLzrJhD1hZS5tWQcyAvNECCA&grant_type=refresh_token

Answer 2

Your code uses HTTP POST but use an HTTP GET request is required as specified here: https://developers.google.com/google-apps/calendar/v3/reference/calendarList/list. Also, you can provide the access token in the access_token parameter (and not in the oauth_token parameter as suggested in the other answer), but another option is to provide it in an Authorization header as in:
Authorization: Bearer <token>
As an example, a token that returns from:
curl -v https://www.googleapis.com/oauth2/v1/tokeninfo?access_token=<token>`
the following introspection result:
{
"issued_to": "<...>.apps.googleusercontent.com",
"audience": "<...>.apps.googleusercontent.com",
"user_id": "<...>",
"scope": "<> https://www.googleapis.com/auth/calendar",
"expires_in": 3527,
"email": "<...>",
"verified_email": true,
"access_type": "offline"
}
can be used in against the Calendar API URL:
curl -v -H "Authorization: Bearer <>" https://www.googleapis.com/calendar/v3/users/me/calendarList
so that it gives me a list of JSON calendar data:
{
"kind": "calendar#calendarList",
"etag": "\"1420511621463000\"",
"nextSyncToken": "00001420511621463000",
"items": [
{
"kind": "calendar#calendarListEntry",
"etag": "\"1418127331044000\"",
...

Answer 3

I managed to figure this out - the calendarList API requires sending an empty body, therefore I change the code to:
set oHTTP = CreateObject("MSXML2.ServerXMLHTTP")
oHTTP.open "GET", sUrl&srequest,false
oHTTP.setRequestHeader "Content-Type", "application/x-www-form-urlencoded"
oHTTP.send
getcal = oHTTP.responseText