What is wrong with this Node.js snippet?

Question

I am learning node.js and the course says there is something wrong with the following snippet.

const fs = require('fs');
const http = require('http');
 
const server = http.createServer((req, res) => {
  if (req.headers['x-secret'] != process.env.SECRET )
    res.writeHead(403).end('Secret incorrect');
 
  let body = [];
  req.on('data', chunk => {
    body.push(chunk);
  });
  req.on('end', () => {
    body = JSON.parse(Buffer.concat(body).toString());
    fs.writeFileSync(body.filename, body.file);
    res.writeHead(200).end('OK');
  });
});
 
server.listen(7654);

Possible things I've found include:

https should be used instead of http (secure server)
Res.writeHead.end is not valid syntax. Res.writeHead and res.end
should be written separately
fs.writeFile() should be used, not the async version
There's no failsafe built-in (?)

However the course seems to be saying that there's a big mistake, which I can't really find.

Please help!

Thanks

Maybe the fact that your condition statement doesn't actually prevent parsing the request body in the event that the secret is unspecified or wrong? — Patrick Roberts
– Patrick Roberts, Commented Jan 8, 2023 at 1:04
There's no return statement, so no, it doesn't. The program still processes the request, parses it, then invalidly calls res.writeHead(200).end('OK'); — Patrick Roberts
– Patrick Roberts, Commented Jan 8, 2023 at 17:37

Tigran Vardanyan · Accepted Answer · 2023-01-08 02:54:31Z

1

Buffer.concat(body).toString() is not valid JSON, so You can't parse it. what you will receive if you log it

----------------------------118769234111712879210320
Content-Disposition: form-data; name="data"; filename="test.json"
Content-Type: application/json

{
    "test": "156"
}
----------------------------118769234111712879210320--

like this

answered Jan 8, 2023 at 2:54

Tigran Vardanyan

463 bronze badges

Sign up to request clarification or add additional context in comments.

1 Comment

Jordan Kasper Over a year ago

Welcome to StackOverflow! Please provide a possible solution in addition to a description of the problem.

Sushilzzz · Accepted Answer · 2023-01-08 16:45:08Z

0

The only problem i see here is in the line

let body = [];

you cannot initialize body as an empty array as you are using it as an object in line

fs.writeFileSync(body.filename, body.file);

you cannot do body.filename as dot notation is only used in an object.

answered Jan 8, 2023 at 16:45

Sushilzzz

5871 gold badge5 silver badges20 bronze badges

2 Comments

Patrick Roberts Over a year ago

Notice body gets reassigned before that line with a call to JSON.parse(...)

Sushilzzz Over a year ago

@PatrickRoberts Lol, I didn't see that. I never reassign. so what's wrong here? I mostly use express

Collectives™ on Stack Overflow

What is wrong with this Node.js snippet?

2 Answers 2

1 Comment

2 Comments

Your Answer

Hot Network Questions

Collectives™ on Stack Overflow

2 Answers 2

1 Comment

2 Comments

Your Answer

Sign up or log in

Post as a guest

Related