PHP - Upload an image file to other domain with CURL

Question

I have two domain, as example site1.loc and site2.loc. In site1.loc i have a php form file like this:

<?php
$c_name = "";
$c_phone = "";

if($_SERVER['REQUEST_METHOD']=="POST"){

    $c_name = $_POST['c_name'];
    $c_phone = $_POST['c_phone'];
    $c_pic = $_FILES['c_pic']['name']; // Image file

        // submit target URL
        $url = 'http://site2.loc/handler.php';

        $fields = array(
           'field1'=>$c_name,
           'field2'=>$c_phone,
           'field3'=>$c_pic
        );

        $postvars='';
        $sep='';
        foreach($fields as $key=>$value) 
        { 
           $postvars.= $sep.urlencode($key).'='.urlencode($value); 
           $sep='&'; 
        }


        //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($ch,CURLOPT_POSTFIELDS,$postvars);

        //execute post
        $result = curl_exec($ch);

        if(curl_errno($ch)) {
            echo 'Error: ' . curl_error($ch);
        }
        else {
            echo $result;
        }

        //close connection
        curl_close($ch);

}


echo '
<form action="" method="post" enctype="multipart/form-data">
    Name : <input type="text" name="c_name" value="'.$c_name.'" /> <br />
    Phone : <input type="text" name="c_phone" value="'.$c_phone.'" /> <br />
    Image : <input type="file" name="c_pic" /> <br />
    <input type="submit" />
</form>
    ';
?>

and handler.php in site2.loc like this:

<?php
ob_start();
if (!isset($_SESSION)) { session_start(); }

    // CONNECT TO DB
    $db_con = mysql_connect("localhost", "root", "root");// or die("Could not connect to db.");
    if(!mysql_select_db("site2",$db_con)) die("No database selected.");

    // POST
    if(isset($_POST)){
        $c_name = $_POST['field1'];
        $c_phone = $_POST['field2'];    
        $c_pic = $_POST['field3'];  

        // UPLOAD FILE
        /* UPLOAD IMAGE CODE HERE */

        // INSERT TO DB
        if(mysql_query("INSERT INTO kontak (nama, telpon) VALUES ('$c_name','$c_phone')")){
            echo "INSERT SUCCESS";
        } else {
            echo "INSERT FAILED";
        }
    }

?>

This script runs well for storing the data to the database, but can not for upload an image file. Can anybody help me modify scripts above in order to upload an image file?

Thanks before.

Answer 1

No code in this answer, just a work flow example that will bypass curl:

1. User posts a form with the uploaded file to "site 1", as per normal.
2. "site 1" processes the form and the uploaded file. The file is placed in a temp directory which is web accessible.
3. On "site 1", once the uploaded file has been checked, make a file_get_contents('http://site2.loc/pullfile.php?f=filename&sec=checkcode') call. The contents of pullfile.php will do just that, pull the file from "site 1" to "site 2".
4. The return from file_get_contents() can be checked for an error return from the "site 2" pullfile.php and on error, deal with it. No error, remove the temp file.
5. The &sec=checkcode could be used to confirm the file has been uploaded successfully to "site 2". It could be an MD5 of the file or something else you come up with.

Just an idea.

Edit: Some sample code to help make things clearer, maybe :]

// ---- Site 1, formprocess.php ----

// Your form processing goes here, including
// saving the uploaded file to a temp dir.

// Once the uploaded file is checked for errors, 
// you need move it to a known temp folder called 
// 'tmp'.

// this is the uploaded file name (which you would
// have got from the processed form data in $_FILES
// For this sample code, it is simple hard-coded.
$site1File = 'test.jpg';

$site1FileMd5 = md5_file('./tmp/'.$site1File);

// now make a remote request to "site 2"
$site2Result = file_get_contents('http://'.SITE_2_URL.'/pullfile.php?f='.$site1File.'&md5='.$site1FileMd5);

if ($site2Result == 'done') {
    unlink('./tmp/'.$site1File);
} else {
    echo '<p>
         Uploaded file failed to transfer to '.SITE_2_URL.'
          - but will be dealt with later.
         </p>';
}

And this will be the 'pullfile.php' on site 2

// ----- Site 2, pullfile.php -----

// This script will pull a file from site 1 and
// place it in '/uploaded'

// used to cross-check the uploaded file
$fileMd5 = $_GET['md5'];
$fileName = basename($_GET['f']);

// we need to pull the file from the './tmp/' dir on site 1
$pulledFile = file_get_contents('http://'.SITE_1_URL.'/tmp/'.$fileName);

// save that file to disk
$result = file_put_contents('./uploaded/'.$fileName,$pulledFile);
if (! $result) {
    echo 'Error: problem writing file to disk';
    exit;
}

$pulledMd5 = md5_file('./uploaded/'.$fileName);
if ($pulledMd5 != $fileMd5) {
    echo 'Error: md5 mis-match';
    exit;
}

// At this point, everything should be right.
// We pass back 'done' to site 1, so we know 
// everything went smooth. This way, a 'blank'
// return can be treated as an error too.
echo 'done';
exit;

Answer 2

CURLOPT_POSTFIELDS The full data to post in a HTTP "POST" operation. To post a file, prepend a filename with @ and use the full path. This can either be passed as a urlencoded string like 'para1=va1&para2=val2&...' or as an array with the field name as key and field data as value. If value is an array, the Content-Type header will be set to multipart/form-data.

http://php.net/manual/en/function.curl-setopt.php

Code snippet:

$postvars['file'] = '@full/path/to/file.jpg';

$ch = curl_init();
curl_setopt($ch, CURLOPT_URL, $url);
curl_setopt($ch, CURLOPT_POST, count($fields));
curl_setopt($ch, CURLOPT_POSTFIELDS, $postvars);
curl_exec($ch);