How do I send a buffer in an HTTP request?

Question

I have a file in memory (buffer) - there is no file on the file system. I want to send that buffer to another server that talks HTTP.

For example, some API A creates a file in memory, SignServer manipulates such files, and responds with a new buffer. My API takes the file from A and feeds it to SignServer.

I tried sending the file to SignServer in multiple ways, but it keeps responding with status 400 (missing field 'data' in request).

---

What I tried:

var http = require('http');
var querystring = require('querystring');

var data = querystring.stringify({
    workerName: 'PDFSigner',
    data: file_buffer
});

var request = new http.ClientRequest({
    hostname: 'localhost',
    port: 8080,
    path: '/signserver/process',
    method: 'GET',
    headers: {
        'Content-Type': 'application/x-www-form-urlencoded',
        // I also tried 'multipart/form-data'
        'Content-Length': Buffer.byteLength(data)
    }
});

request.end(data);

I tried printing data, and it showed:

workerName=PDFSigner&data=

Which is bad because data wasn't set to file_buffer. I tried printing file_buffer, and it does have content (not null, not undefined, actually has bytes inside). So stringifying the buffer gave an empty string.

I tried doing the same thing with the request module and it didn't work either.

Note that SignServer isn't written in Node nor JavaScript. It's a Java application, so it probably doesn't work with json (which is why I'm trying to do it with querystring). Yes, I tried sending json.

Answer 1

The reason why data is set to an empty string is described in this issue and the solution is given in this issue.

escape and stringify the buffer like so:

var data = querystring.stringify({
    workerName: 'PDFSigner',
    data: escape(file_buffer).toString('binary')
});

As @robertklep mentioned, your other problem is that you can't send a big file using application/x-www-form-urlencoded. You'd need to do it with multipart/form-data.