Efficient way to read file in NodeJS - node.js

Question

I am receiving an image file sent from an Ajax request:
var data = canvas.toDataURL('image/jpg', 1.0);
$.post({
url: "/upload-image",
data: {
file: data
}
}).done(function(response) {
....
})
}
And on the server side, I want to transmit the image file to an API
function getOptions(buffer) {
return {
url: '.../face_detection',
headers: headers,
method: 'POST',
formData: {
filename: buffer
}
}
}
router.post('/upload-image', function(req, res, next) {
console.log('LOG 0' + Date.now());
var data_url = req.body.file;
var matches = data_url.match(/^data:.+\/(.+);base64,(.*)$/);
var ext = matches[1];
var base64_data = matches[2];
var buffer = new Buffer(base64_data, 'base64');
console.log('LOG 1' + Date.now());
request(getOptions(buffer), function(error, response, body) {
res.json(body);
console.log(Date.now());
});
});
The problem that I have is that the lines between LOG 0 and LOG 1 are very slow, a few seconds. But the image is only 650kb. Is there a way to accelerate this?
Using another method to read the header, avoid the buffer, change the uploading process. I don't know but I'd like to be faster.
Thank you very much.

Answer 1

I would suggest using a library to handle some of this logic. If you would prefer to keep a lean dependency list, you can take a look at the source of some of these modules and base your own solution off of them.
For converting a data URI to a buffer: data-uri-to-buffer
For figuring out a file type: file-type
I would especially recommend the file-type solution. A safer (can't say safest) way to ensure what kind of file a Buffer is is to inspect aspects of the file. file-type seems to at least take a look at the Magic Number of the file to check type. Not foolproof, but if you are accepting files from users, you have to accept the risks involved.
Also have a look at Security Stack Exchange questions for good practices. Although the following say PHP, all server software runs the risk of being vulnerable to user input:
Hacker used picture upload to get PHP code into my site
Can simply decompressing a JPEG image trigger an exploit?
Risks of a PHP image upload form
"use strict";
const dataUriToBuffer = require('data-uri-to-buffer'),
fileType = require("file-type"),
express = require("express"),
router = express.Router(),
util = require("util"),
fs = require("fs"),
path = require("path");
const writeFileAsync = util.promisify(fs.writeFile);
// Keep track of file types you support
const supportedTypes = [
"png",
"jpg",
"gif"
];
// Handle POSTs to upload-image
router.post("/upload-image", function (req, res, next) {
// Did they send us a file?
if (!req.body.file) {
// Unprocessable entity error
return res.sendStatus(422);
}
// Get the file to a buffer
const buff = dataUriToBuffer(req.body.file);
// Get the file type
const bufferMime = fileType(buff); // {ext: 'png', mime: 'image/png'}
// Is it a supported file type?
if (!supportedTypes.contains(bufferMime.ext)) {
// Unsupported media type
return res.sendStatus(415);
}
// Save or do whatever with the file
writeFileAsync(path.join("imageDir", `userimage.${bufferMime.ext}`), buff)
// Tell the user that it's all done
.then(() => res.sendStatus(200))
// Log the error and tell the user the save failed
.catch((err) => {
console.error(err);
res.sendStatus(500);
});
});