http.request body forwarding breaks request

Question

I am writing some sort of proxy and I am trying to forward everything to the "client-server":

const headers = req.headers;
delete headers['content-length'];
const body = '...maybe some content...';

const chunks: any[] = [];

const request = http
    .request(
        url,
        {
            method: req.method,
            headers,
        },
        (msg) => {
            msg.on('data', (data) => chunks.push(data));
        },
    )
    .on('error', (error) => {
        reject(error);
    })
    .on('close', () => {
        resolve(Buffer.concat(chunks).toString('utf8'));
    });

request.write(body, (error) => {
    if (error) {
        reject(error);
    }
});

request.end();

All in all it is working as I expect it to, but if I send any data (body) in a GET request, then I am getting a Error: socket hang up. Node's documentation says that most likely the connection closes before the response is received.

The client server accepts a body in a GET and does not refuse the connection or something alike (tested via Postman).

What is happening in Node; Why does the connection close prematurely?

Answer 1

The request Content-Length was causing the premature connection termination.

Node docs state

• Sending a 'Content-Length' header will disable the default chunked encoding.

I was removing the header from the incoming request, for Node to handle it automatically.
Turns out, that Node only computes the content-length in POST/PATCH/PUT requests. In other methods, even by properly using .write() the Content-Length will not be set automatically, causing the premature closure.

To fix this, compute the length of the body on your own and send in in the headers:

const body = '...maybe some content...';

const chunks: any[] = [];

const request = http
    .request(
        url,
        {
            method: req.method,
            headers: {
                ...req.headers,
                'content-length': Buffer.byteLength(body),
            },
        },
        (msg) => {
            msg.on('data', (data) => chunks.push(data));
        },
    )
    .on('error', (error) => {
        reject(error);
    })
    .on('close', () => {
        resolve(Buffer.concat(chunks).toString('utf8'));
    });

request.write(body, (error) => {
    if (error) {
        reject(error);
    }
});

request.end();