Is posible upload file whit PHP and get public share link to file?

This is the code I have for PHP v2 for uploading a file, using curl functions, but I'm at a loss as to how to describe what the POST data should look like. 

<?php

$ch = curl_init();
curl_setopt($ch, CURLOPT_RETURNTRANSFER, true);
curl_setopt($ch, CURLOPT_POST, true);

$token = "yourtoken";
$host = "https://api.dropboxapi.com/";

//set headers
$headers = array('Authorization: Bearer '.$token,
 'Content-Type: application/octet-stream',
 'Dropbox-API-Arg: {"path":"/test.txt","mode":"add"}',
);

$f = fopen("test.txt", "rb");

curl_setopt($ch, CURLOPT_URL, $host);
curl_setopt($ch, CURLOPT_HTTPHEADER, $headers);

// What should the POST data look like? Using the file handle? That doesn't work.
curl_setopt($ch, CURLOPT_POSTFIELDS, $f);

$response = curl_exec($ch);

fclose($f);

echo "<br />File Upload Response: <br />";
var_export($response);
echo "<br />File UPload HTTP CODE: <br />";
var_export(curl_getinfo($ch, CURLINFO_HTTP_CODE));

curl_close($ch);