How To Stop Node Downloading File Completely

Question

I am Trying to do a Hobby Project in React and Node as part of my learning. In this project I am trying to convert http and https links to torrent. The problem i am facing is when i submit a link it downloading the complete file to the system and then converting it. How to avoid that. Here is my Code

var http = require('http');
var webtorrentify = require('webtorrentify-link');
var fs = require('fs');
var url = require('url');
var path = require('path');
var validUrl = require('valid-url');
var express = require('express');
var getUrls = require('get-urls');
var remote = require('remote-file-size');
var app = express();

var downloadLink;
var fileName;
var fileSize;
var server;
var parsed;
var param;
var link;
var port;
port = process.env.PORT || 80;

app.get('/favicon.ico', function (req, res) {
  console.log('favicon request recived');
});
app.get('*', function (req, res) {
  if (req.url === '/') {
    // app.use('/public/html', express.static(path.join(__dirname)));
    fs.readFile('public/html/index.html', function (err, data) {
      res.write(data);
    });
  } else if (req.url === '/l?thelink=') {
    fs.readFile('public/html/emptyRequest.html', function (err, data) {
      res.write(data);
      res.end();
    });
  } else {
    // ---------Reciving Url--------------------
    console.log(req.query.thelink);
    downloadLink = req.query.thelink;
    // -----------------------------------------

    // ------------checking for valid url-------
    if (validUrl.isUri(downloadLink)) {
      console.log('Looks like an URI');
      // -----------------------------------------

      // ----------Extracting filename-------------
      parsed = url.parse(downloadLink);
      fileName = path.basename(parsed.pathname);
      console.log(path.basename(parsed.pathname));
      // -------------------------------------------

      // ----------Finding File size----------------
      remote(downloadLink, function (err, o) {
        fileSize = (o / 1024) / 1024;
        console.log('size of ' + fileName + ' = ' + fileSize + ' MB');
        // -------------------------------------------
        if (fileSize < 501) {
          /// ////////////Creating Torrent////////////////////
          webtorrentify(downloadLink)
            .then(function (buffer) {
              console.log('creating the torrent');
              // res.send('what is');
              // -------------------------------------------
              res.setHeader('Content-Type', 'application/x-bittorrent');
              res.setHeader('Content-Disposition', `inline; filename="${fileName}.torrent"`);
              res.setHeader('Cache-Control', 'public, max-age=2592000'); // 30 days
              res.send(buffer);
              console.log(fileName + '.torrent created');
              res.end();
              // -------------------------------------------
            });
          /// /////////////////////////////////////////////
        } else {
          console.log('More than 500 MB');
          res.send('<h4> More than 500 MB or invalid URL </h4>');
        }
      });
    } else {
      console.log('not url');
      fs.readFile('public/html/404.html', function (err, data) {
        res.write(data);
        res.end();
      });
    }
  }
});

app.listen(port);

console.log('server up and running', port);

Answer 1

This behavior is normal as documented in webtorrentify-link's documentation:

This module will take a download URL and convert it into a .torrent file. Warning: it downloads the URL in order to do this.

And technically no module/code will be able to generate the torrent without downloading. This is because the torrent file structure requires each file pieces' hash, which can only be obtained and calculated having the full file.