Upload file via io.socket.request ()

I need to upload a file via io.socket.request (), via form and ajax I could already do the header of the form is:

<form method="POST" action="/etc" enctype="multipart/form-data">

But with io.socket.request () nothing comes to my form, which I usually capture with the following function:

req.file('file').upload(function(req, res) {...});

This returns me undefined .