Fetch Firebase tokens for topic

README.md

Firebase Topic Counter

This little script will output the amount of tokens subscribed to a topic.
You will need to replace the variables with your personal ones in order for it to work.

We used this function in a Lambda which sends the results to a monitoring dashboard.

How to get the variables

Screenshots in the comments.

• Go to the Firebase Console.

• Under Grow click Cloud Messaging.

• Open up your developer tools.

• Typ in a fake notification text

• Click Next

• Under the Target tab click Topic

• In the network tab you will see a request to an url similar to this one
  https://gcmcontextualcampaign-pa.clients6.google.com/v1/4/projects/${projectId}/topics?prefix=%2Ftopics%2F&key=${key}

• Save your projectId and key in the script

• Still in the developer tools, under the Application tab go to Cookies

• Click on the https://console.firebase.google.com site

• Here you will find the SID, HSID, SSID, APISID and the SAPISID

• Save these in the script.

index.js

var sha1 = require('sha1');
var fetch = require('node-fetch');

//See README.md
var key = "key";
var projectId = "firebase project id;

//Check cookies from https://console.firebase.google.com
var SID = "sid";
var HSID = "hsid";
var SSID = "ssid";
var APISID = "apisid";
var SAPISID = "sapisid";

exports.handler = async(event) => {
    const origin = "https://console.firebase.google.com";
    const secretFromDevConsole = `https://gcmcontextualcampaign-pa.clients6.google.com/v1/4/projects/${projectId}/topics?prefix=/topics/&key=${key}`;

    const generateAuthorizationHeader = () => {
        const currentTime = new Date().getTime();
        const sapisid = SAPISID;

        const hashed = sha1(`${currentTime} ${sapisid} ${origin}`);
        return `SAPISIDHASH ${currentTime}_${hashed}`;
    };

    const getTopicSubscriptionsCall = async() => {
        const authorizationKey = generateAuthorizationHeader();
        await fetch(secretFromDevConsole, {
                method: "GET",
                headers: {
                    "Authorization": authorizationKey,
                    "X-Origin": origin,
                    "cookie": `SID=${SID}; HSID=${HSID}; SSID=${SSID}; APISID=${APISID}; SAPISID=${SAPISID}`
                },
            })
            .then(response => response.json())
            .then(async json => {
                const topics = json.topic;
                topics.forEach(topic => console.log(topic.name + " " + topic.size));
                return { statusCode: 200 };
            });
    };

    await getTopicSubscriptionsCall();
};

package.json

{
  "name": "check-firebase-breaking-topic-subscriptions",
  "version": "1.0.0",
  "description": "Check Firebase breaking topic subscription",
  "main": "index.js",
  "dependencies": {
    "node-fetch": "^2.3.0",
    "sha1": "^1.1.1"
  },
  "author": "Tim Rijckaert",
  "license": "ISC"
}

Thank you @Jaluanda, your fixed worked perfectly 😊

@Aulig you're right. How do you know only the __Secure-1.. is missing ? If see many info in the original cookie header, is there a way to gen all of them ? 😅

Here is the error triggered : Request had invalid authentication credentials. Expected OAuth 2 access token, login cookie or other valid authentication credential. See https://developers.google.com/identity/sign-in/web/devconsole-project.

I tested it against some other Firebase endpoint. It works as long as you send the 3 cookies starting with __Secure-1. The __Secure-2*** and __Secure-3*** weren't necessary in my experiments (meaning it worked without them).

No idea how to generate __Secure-1PSIDTS since it frequently expires. Supposedly you can get a fresh one by calling accounts.google.com/RotateCookies but I couldn't figure out the correct way to use that endpoint. Would need to dig into the JS that calls this endpoint on the firebase website.