[ERR_INVALID_ARG_TYPE]: The first argument must be of type string or an instance of Buffer. when using admin.auth().verifyIdToken

Question

I am writing a back-end server (using Node.js) to let users to interact with Firebase. Here is what I have so far:

• I can let users create their firebase account (using email and password) via admin ADK;
• I can let users log in to their firebase account (using email and password they already created) via REST API; and return back their idToken as well as refreshToken.

However, I really wonder that, every time a user log in, they will have an entirely new idToken (that lasts for 1 hour); so will the old one expire instantaneously when the new idToken is generated? So, I think I would use the firebase-admin SDK verifyIdToken function to do just what I need.

The problem is, even when I input the new idToken, the function just fails. I don't really know what's going on here.

Here's the error in case I don't perform a catch:

(node:9240) UnhandledPromiseRejectionWarning: TypeError [ERR_INVALID_ARG_TYPE]: The first argument must be of type string or an instance of Buffer. Received type number (1598554002)
at write_ (_http_outgoing.js:653:11)
at ServerResponse.write (_http_outgoing.js:621:15)
at D:\Viet Properties\Coding\ViMath\spreadsheet.js:315:19
at processTicksAndRejections (internal/process/task_queues.js:97:5)
at async verifyid (D:\Viet Properties\Coding\ViMath\spreadsheet.js:314:5)
at async Server.<anonymous> (D:\Viet Properties\Coding\ViMath\spreadsheet.js:584:17)
(node:9240) UnhandledPromiseRejectionWarning: Unhandled promise rejection. This error originated either by throwing inside of an async function without a catch block, or by rejecting a promise which was not handled with .catch(). To terminate the node process on unhandled promise rejection, use the CLI flag`--unhandled-rejections=strict` (see https://nodejs.org/api/cli.html#cli_unhandled_rejections_mode). (rejection id: 1)
(node:9240) [DEP0018] DeprecationWarning: Unhandled promise rejections are deprecated. In the future, promise rejections that are not handled will terminate the Node.js process with a non-zero exit code.

Here's the function that I call:

async function verifyid(data, serverres) {
   serverres.write(data.id);
   await admin.auth().verifyIdToken(data.id).then(function(token) {
       serverres.write(token.exp)
   }).catch(function(error) {
       serverres.write(`Error code: ${error.code} \r\nError message: ${error.message}`);
   });
};

The main code is here:

var server = http.createServer(async function (req, res) {
    var urllink = url.parse(req.url, true);
    var urldata = urllink.query;

    if (Object.entries(urldata).length !== 0){
        switch(urldata.goal){
            //I dropped some cases here for clearance of the code
            case 'verifyid':
                await verifyid(urldata, res)
                res.end();
                break;
            default:
                res.write("Error: No action has been specified!")
                res.end();
        };
    };
  });


//initialize admin
var admin = require('firebase-admin');
var serviceAccount = require("./vimath_serviceAccountKey.json");
const { parse } = require('path');
const { userInfo } = require('os');

admin.initializeApp({
    credential: admin.credential.cert(serviceAccount),
    databaseURL: 'https://[my project].firebaseio.com'
});

server.listen(8080);

Can you guys have a look?

Thank you very much in advance,

And have a nice day,

Answer 1

The error is thrown at this line:

serverres.write(token.exp)

That API expects a string or a Buffer, but you're passing a number.