GoogleClassroomRE

Documentation on reverse engineered Google Classroom API

Common parameters

Param	Value
`_reqid`	(any int, can be same across all requests)
`ch_id`	0/1 (int, used for multiple account selection, use same value as displayed in browser

Data

Requests to the internal APIs are submitted with post data containing what seems to be a template of variables to return, and a CSRF token. This data differs per API endpoint as different possible datasets can be returned, so use browser network tab to sample each request.

Example data: (token and ids have been changed)

f.req: [[1000,null,1,0],[[[true,true,true,true,true,false,null,[true,true,true,null,true,true,true],true,true,true,true,true,true,[true],null,null,null,true,3],[true,true,true,true,true,true,[true],true,null,[true,true],true,true,null,true,[[true,true,[],[null,true]],true],null,false],[null,true],null,[true,true]],[[true,true,true,true,true,false,null,[true,true,true,null,true,true,true],true,true,true,true,true,true,[true],null,null,null,true,3]],[[true,true,true,true,true,false,null,[true,true,true,null,true,true,true],true,true,true,true,true,true,[true],null,null,null,true,3],[true,true,true,true,true,true,[true],true,null,[true,true],true,true,null,true,[[true,true,[],[null,true]],true],null,false],[true]],null,null,[[true,true,true,true,true,false,null,[true,true,true,null,true,true,true],true,true,true,true,true,true,[true],null,null,null,true,3]]],[[[],[["674647454344"]],[2,5],[2],[],[],[],[],[],null,null,[],null,[],[1]]]]

token: u84u9eutjiowpurgioujf9q80uf98ufiquiutr98tu89888d

Headers

Along with the authentication cookies, the only other required header is

Content-Type: application/x-www-form-urlencoded

Authentication

Authentication is done using 3 cookies:

SID
HSID
SSID

Which can be copied from a browser for testing purposes

Getting valid json from API

The APIs return the same 4 characters before the JSON data )]}'. This can be cut from the start of the string and then the response can be interpretted as JSON.

API

Use/Desc	URL	Params	Data
List lessons	`https://classroom.google.com/u/{ch_id}/v8/querycourse?_reqid={req_id}&rt=j`	`_reqid` and `ch_id`	Yes
Get work	`https://classroom.google.com/u/{ch_id}/v8/streamitem/query?_reqid={req_id}&rt=j`	`_reqid` and `ch_id`	Yes
Submit work / mark task as done	`https://classroom.google.com/u/{ch_id}/v8/streamitem/query?_reqid={req_id}&rt=j`	`_reqid` and `ch_id`	Yes

Work

Fetch work from endpoint https://classroom.google.com/u/{ch_id}/v8/streamitem/query?_reqid={req_id}&rt=j, cut first 4 characters then load the JSON object.
Get the list of work from the object - workJSON[0][0][2]
Loop through each object in the list, using set offsets to get specific data points

Data point	Index (python format)
Base	`[1]`
Base -> workid	`[0][0][0]`
Base -> classid	`[0][0][1][0]`
Base -> createdmilis	`[1][1]`
Base -> duemilis	`[1][0]`
Base -> name	`[0][5]`
Base -> description	`[0][22][1]`

Direct link to page is generated using base64 encoded values for classid and workid:

f"https://classroom.google.com/u/{ch_id}/c/{urlsafe_b64encode(self.classid.encode()).decode()}/a/{urlsafe_b64encode(self.workid.encode()).decode()}/details"

Getting state of submission

Post to "https://classroom.google.com/u/{ch_id}/v8/querysubmission?_reqid={req_id}&rt=j, adding classids and workids to the list in the data template.

Data point	Index (python format)
Base -> submissionState	`[20]`
Base -> submissionmilis	`[21]`

submissionState is an enum:

Value	Text
1	No due date / Due (If `duemilis` is set then assume due)
2	Missing
3	Submitted
4	Handed in late
8 / 10	Marked

self.substate = base[20]
match self.substate:
    case 1:
        if self.duemilis is None:
            self.state = "No due date"
        else:
            self.state = "Due"
        self.submitted = False
    case 2:
        self.state = "Missing"
        self.submitted = False
    case 3:
        self.state = "Submitted"
        self.submitted = True
    case 4:
        self.state = "Handed in late"
        self.submitted = True
    case 8 | 10:
        self.state = "Marked"
        self.submitted = True
    case _:
        self.state = str(self.substate)
if self.submitted:
    self.submilis = base[21]
    self.subtime = datetime.utcfromtimestamp(
        self.submilis/1000).strftime('%Y-%m-%d %H:%M:%S')

Error detection

If an error occurs then data at [0][0][2] will be er

j = json.loads(page.text[4:])[0][0][2]
if page.text[0][0][0] == "er":
    return False

NullString1 / GoogleClassroomRE