Anyway to 'spy' on the activity of curl_init() & curl_exec()?

I have some PHP code that was at one point WORKING FINE. It makes a call out to an external API, the API has NOT CHANGED AT ALL. The PHP code has also NOT CHANGED AT ALL. But suddenly, I am getting no results back for this function:

if (!function_exists(setFieldsAndCallURL))
{ 
    function setFieldsAndCallURL($url,$fields)
    {

        //url-ify the data for the POST
        $fields_string='';
              foreach($fields as $key=>$value) 
                { $fields_string .= $key.'='.$value.'&'; }
        rtrim($fields_string,'&');

        //open connection
        $ch = curl_init();

        //set the url, number of POST vars, POST data
        curl_setopt($ch,CURLOPT_URL,$url);
        curl_setopt($ch,CURLOPT_POST,count($fields));
        curl_setopt($ch,CURLOPT_POSTFIELDS,$fields_string);
        curl_setopt($ch, CURLOPT_RETURNTRANSFER, 1); 

        //execute the jump
        $result = '';
        $result = curl_exec($ch);

        //close connection
        curl_close($ch);

        return $result;
      }
}

Before, it would return a text GUID when called:

$userURL ='https://api.nottherealendpointurl.net/public/user/authenticate';

$userFields = array(
     'username'=>$username,
     'lastName'=>$lastname,
     'firstName'=>$firstname,
     'email'=>$email,
     'token'=>urlencode($adminKey),
);

//Login this particular user
$userKey = setFieldsAndCallURL($userURL,$userFields);

But sudde开发者_开发知识库nly it has started returning "" (empty string) and I have no idea why.

Is there any way to get more info and spy on the inner workings of this thing? See the call it is making using HTTP header logging software? Or anything?

NOTE: I have already tested the POST manually to the API and it is working as expected, I am still getting back the proper GUID. For some reason doing it through this curl thing just suddenly quit doing it properly. Nobody has any idea what could be different now.

Propably the ip of the server is blocked by now, where your local ip is not?

You might want to add

 $headerFile = fopen(filepath_to_header_file);
 $errorFile = fopen(filepath_to_error_file);    

 curl_setopt($ch, CURLOPT_VERBOSE, 1); 
 curl_setopt($ch, CURLOPT_HEADER, 1); 
 curl_setopt($ch, CURLOPT_WRITEHEADER, $headerFile ); 
 curl_setopt($ch, CURLOPT_STDERR, $errorFile );

to get the header of the response and the errors into files and look their content up.

edit: To verify if the ip of the server is blocked you could try something like this

$host = "ssl://api.nottherealendpointurl.net/";
$port = 443;
$url = "/public/user/authenticate";

$timeout = 30;
$errno = "";
$errstr= "";

$fp = fsockopen($host, $port, $errno, $errstr, $timeout);
if($fp)
{
    $request = "GET ".$url." HTTP/1.1\r\n";
    $request.= "Host: ".$host."\r\n";
    $request.= "User-Agent: Mozilla/5.0 (Windows; U; Windows NT 5.1; de-DE; rv:1.7.12) Gecko/20050919 Firefox/1.0.7\r\n";
    $request.= "Connection: Close\r\n\r\n";

    fwrite($fp, $request);
    while (!feof($fp))
    {
        $data .= fgets($fp, 128);
    }
    fclose($fp);
    echo $data;
}
else
{
    echo "ERROR: ".$errstr;
}

where $data contains the response from the remote server-

Depending on what platform you're on you can look at the raw packets, for linux command line only, that'd be tcpdump for widows/others you can use wireshark.

tcpdump -i eth1 tcp port 80

or

http://www.wireshark.org/download.html