how to upload a file from node.js

Question

I found many posts when I queried for this problem, but they all refer to how to upload a file from your browser to a node.js server. I want to upload a file from node.js code to another server. I tried to write it based on my limited knowledge of node.js, but it doesn't work.

function (data) {
  var reqdata = 'file='+data;
  var request = http.request({
    host : HOST_NAME,
    port : HOST_PORT,
    path : PATH,
    method : 'POST',
    headers : {
      'Content-Type' : 'multipart/form-data',
      'Content-Length' : reqdata.length
    }
  }, function (response) {
      var data = '';
      response.on('data', function(chunk) {
        data += chunk.toString();
      });
      response.on('end', function() {
        console.log(data);
      });
    });

  request.write(reqdata+'

');
  request.end();
})

The above function is called by other code that generates data.

I tried to upload same data file using curl -F "file=@<filepath>" and the upload is successful. But my code fails. The server returns an application specific error which hints that the uploaded file was invalid/corrupt.

I collected tcpdump data and analysed it in wireshark. The packet sent from my node.js code lacks the boundary required for the multipart data. I see this message in wireshark packet

The multipart dissector could not find the required boundary parameter.

Any idea how to accomplish this in node.js code?

Answer 1

jhcc's answer is almost there.

Having to come up with support for this in our tests, I tweaked it slightly.

Here's the modified version that works for us:

var boundaryKey = Math.random().toString(16); // random string
request.setHeader('Content-Type', 'multipart/form-data; boundary="'+boundaryKey+'"');
// the header for the one and only part (need to use CRLF here)
request.write( 
  '--' + boundaryKey + '
'
  // use your file's mime type here, if known
  + 'Content-Type: application/octet-stream
' 
  // "name" is the name of the form field
  // "filename" is the name of the original file
  + 'Content-Disposition: form-data; name="my_file"; filename="my_file.bin"
'
  + 'Content-Transfer-Encoding: binary

' 
);
fs.createReadStream('./my_file.bin', { bufferSize: 4 * 1024 })
  .on('end', function() {
    // mark the end of the one and only part
    request.end('
--' + boundaryKey + '--'); 
  })
  // set "end" to false in the options so .end() isn't called on the request
  .pipe(request, { end: false }) // maybe write directly to the socket here?

Changes are:

• ReadableStream.pipe returns the piped-to stream, so end never gets called on that. Instead, wait for end on the file read stream.
• request.end puts the boundary on a new line.