OAuth, PHP, Rest API and curl gives 400 Bad Request - php

Question

We got a couple of apps, utilizing the car2go Rest-API with OAuth 1.0.
All our web apps stopped working 2 days ago. All curl POST requests are failing now with the following error:
400 Bad Request
Your browser sent a request that this server could not understand.
Error code: 53
Parser Error: [Content-Length: -]
I spend a lot of time trying to figure out if the problem is my oauth workflow. But in the end all parameters and signatures and stuff is correct. I successfully fire the POST via Postman (REST-Client)
So my conclusion is that somehow the php code for the curl is suddenly not working anymore.
This is the (very ugly) curl function. A difference to most tutorials about curl POST is, that I'm passing a full URL with all parameters already attached, so I don't need CURLOPT_POSTFIELDS.
function curlAPI($params) {
//open connection
$ch = curl_init();
$url = $params['url'];
curl_setopt($ch,CURLOPT_HEADER,false);
//set the url, number of POST vars, POST data
curl_setopt($ch,CURLOPT_URL,$url);
curl_setopt($ch, CURLOPT_USERAGENT, $_SERVER['HTTP_USER_AGENT']);
curl_setopt($ch, CURLOPT_FOLLOWLOCATION,true);
curl_setopt($ch, CURLOPT_MAXREDIRS,50);
curl_setopt($ch, CURLOPT_TIMEOUT_MS, 5000);
if($params['type'] == 'POST') {
// POST
curl_setopt($ch,CURLOPT_POST, true);
} else if($params['type'] == 'DELETE') {
// DELETE
curl_setopt($ch, CURLOPT_CUSTOMREQUEST, "DELETE");
} else if($params['type'] == 'PUT') {
$update_json = array();
// PUT
curl_setopt($ch, CURLOPT_CUSTOMREQUEST, "PUT");
curl_setopt($ch, CURLOPT_POSTFIELDS,'');
} else {
// GET
curl_setopt($ch,CURLOPT_POST,0);
}
curl_setopt($ch, CURLOPT_RETURNTRANSFER, true);
curl_setopt($ch, CURLOPT_FOLLOWLOCATION, true);
//execute post
$result['result'] = curl_exec($ch);
// debug
if (FALSE === $result['result']) {
$result['errorInfo'] = curl_error($ch).' - '.curl_errno($ch);
}
$reponseInfo = array();
$reponseInfo['info'] = curl_getinfo($ch);
$reponseInfo['error'] = curl_error($ch);
//close connection
curl_close($ch);
$result['reponseInfo'] = $reponseInfo;
return json_encode($result);
}

Answer 1

Ok, this is what fixed this nightmare:
curl_setopt($ch,CURLOPT_HTTPHEADER ,array('Content-Length: 0'));
Aparrently it's not ok to send a curl POST without a header.