Https request Post from an Angular App to ExpressJS Node.js Server results in request write() end() is not a function and socket hang up Error

Question

I am trying to invoke an Authorization Token API to get an access token. The trigger is from an angular application via a button click.

The angular service code is below:

import { Injectable } from '@angular/core';
import { HttpClient } from '@angular/common/http';
import { User } from  './../auth/user';
import { AuthResponse } from  './../auth/auth-response';
import { tap } from  'rxjs/operators';
import { Observable, BehaviorSubject } from  'rxjs';

@Injectable({
  providedIn: 'root'
})
export class AuthService {

  AUTH_SERVER = "http://localhost:3000";
  authSubject  =  new  BehaviorSubject(false);

  constructor(private httpClient: HttpClient) { }

  register(user: User): Observable<AuthResponse> {
      return this.httpClient.post<AuthResponse>(`${this.AUTH_SERVER}/register`, user).pipe(
        tap((res:  AuthResponse ) => {

          if (res.token) {
            console.log("ACCESS_TOKEN : "+ res.token.access_token);
            localStorage.set("ACCESS_TOKEN", res.token.access_token);
            localStorage.set("EXPIRES_IN", res.token.token_type);
            localStorage.set("ACCESS_TOKEN", res.token.expires_in);
            localStorage.set("EXPIRES_IN", res.token.refresh_token);
            this.authSubject.next(true);
          }
        })

      );
    }
}

And the NodeJS Backend service code is below:

const express = require('express')
const https = require('https')
const app = express()
const  router  =  express.Router();
const cors = require('cors');
const bodyParser  = require("body-parser")
const api_helper = require('./util/api_helper')

const port = 3000

app.use(cors());
router.use(bodyParser.urlencoded({ extended:  false }));
router.use(bodyParser.json());

router.get('/', (req, res) => {
    res.status(200).send('Welcome to Make REST API Calls to Authorisation Server In Express!');
});


router.post('/register', (req, res) => {

  console.log('nodejs user name = '+req.body.username);
  console.log('nodejs password = '+req.body.password);

  var client_id = 'xxxx';
  var client_secret = 'yyyyyy';
  var auth_header = 'Basic ' + Buffer.from(client_id + ':' + client_secret).toString('base64');

  const data = "grant_type=password&username=ddddd&password=eeeeee&client_id=fff&client_secret=Joe75";

  const options = {
      hostname: 'linux-2222',
      port: 8543,
      path: '/xxxx/oauth2/token',
      method: 'POST',
      headers: {
          'Content-Type': 'application/x-www-formurlencoded',
          'Content-Length': data.length
      }
  };

  const requestVar = https.request(options, (res) => {
    console.log(`statusCode: ${res.statusCode}`)

    res.on('data', (chunk) => {
      console.log(`BODY: ${chunk}`);
    });

    res.on('end', () => {
      console.log('No more data in response.');
    });
  });

  requestVar.write(data);
  requestVar.end();

  req.on('error', (error) => {
    console.log('error is ' + error);
  });


});

app.use(router);
app.listen(port, () => console.log(`Node server listening on port ${port}!`))

The error I am getting is below:

Entering the server endpoint 
nodejs user name = xxx
nodejs password = yyyy
(node:6285) Warning: Setting the NODE_TLS_REJECT_UNAUTHORIZED environment variable to '0' makes TLS connections and HTTPS requests insecure by disabling certificate verification.

**TypeError: req.write is not a function**
    at /Users/admin/Development/mod/integrator/src/app/app.js:78:7
    at invokeCallback (/Users/admin/Development/mod/integrator/node_modules/raw-body/index.js:224:16)
events.js:288
      throw er; // Unhandled 'error' event
      ^

Error: socket hang up
    at connResetException (internal/errors.js:604:14)
    at TLSSocket.socketOnEnd (_http_client.js:460:23)
    at TLSSocket.emit (events.js:323:22)
    at endReadableNT (_stream_readable.js:1204:12)
    at processTicksAndRejections (internal/process/task_queues.js:84:21)
Emitted 'error' event on ClientRequest instance at:
    at TLSSocket.socketOnEnd (_http_client.js:460:9)
    at TLSSocket.emit (events.js:323:22)
    at endReadableNT (_stream_readable.js:1204:12)
    at processTicksAndRejections (internal/process/task_queues.js:84:21) {
  code: 'ECONNRESET'
}
npm ERR! code ELIFECYCLE
npm ERR! errno 1
npm ERR! integrator@0.0.1 start: `NODE_TLS_REJECT_UNAUTHORIZED='0' node ./src/app/contractor_lifecycle_app.js`
npm ERR! Exit status 1
npm ERR! 
npm ERR! Failed at the integrator@0.0.1 start script.
npm ERR! This is probably not a problem with npm. There is likely additional logging output above.

npm ERR! A complete log of this run can be found in:
npm ERR!     /Users/admin/.npm/_logs/2020-03-28T11_37_38_559Z-debug.log

The nodejs console shows errors with : TypeError: req.write is not a function and Error: socket hang up . FYI, I am getting the access token in postname using the relevant http request options. And I was able to use the access token to get a protected resource in postman.

But, I cannot even consume the authorization endpoint via nodejs express.

Please, I need someone to help, any ideas will do. It appears the problem is with the https.request logic, but I dont know exactly where.

NOTE: The request parameter from the angular app is being successfuly logged in the console in the nodejs https request post function.

Answer 1

The req in the following line:

router.post('/register', (req, res) => {

was overriding the following:

req.write(data);
req.end(); 

The request write() and end() are methods of the object returned from https.request(options, (res) => {

So, I have updated the code by assigning the https.request(options, (res) => { .. to a new varibale called requestVar.

And now I am getting my acccess token from the authorization server. I have updated original post with the fix. Hurray.