Login to site using cURL and get data(image) from it

Question

I am trying to get an chart image from a remote site.
But the image seemed to be created dynamically from the site when called.
It will return nothing when not logged in.

This is the image URL

<img src="http://fuelbuyer.dtn.com/energy/view/energy/chart.do?width=150&height=120&chartType=0&ts=1352196066175&rackId=446&productId=179&points=8&showExtraLine=True">

I somehow managed to log in using this CODE and tried to display image.
But it is not working.

$ch = curl_init();
$url = 'http://fuelbuyer.dtn.com/energy/common/signin.do?';
$login = 'username=$USER&password=$pass&autoLogin=true&partnerId=0&partnerName=';
curl_setopt($ch, CURLOPT_URL, $url.$login);
curl_setopt($ch, CURLOPT_RETURNTRANSFER, 1);
curl_setopt($ch, CURLOPT_FOLLOWLOCATION, 1);
curl_setopt($ch, CURLOPT_HEADER, 0);
$output = curl_exec($ch);
$info = curl_getinfo($ch);
curl_close($ch); 

Calling the image URL directly (on browser Addressbar ONLY WHEN LOGGED IN) , will give some code like

" ‰PNG IHDR–xŸ-œGPIDATxÚílÇÇ IHKB-ËuÄت!Eš°Š !ÈB IÀµ©…œ€ $@S‡8¶ ªÀ”D²œÐbR Æ`˜WjAx;~Äø…ç·ï±;³ýÎk×ûºÙݳ™»Þ_+´Ü÷v÷·3óÿf¾™òqnAa@„ùÂM›6åÔ5}£¡k訚Ži踶¾USž†Nh(_M'5tJC Á™°‚ðN?ÿ¼3>¾=5µîòåêÕô©V¢:‰ê%º+QƒD5õ©Y"›D-Õ*Q›Dí}ê¨S¢.‰º%²Kä蓳­Û¹“߸ÑUPà’ˆ“ˆ—õéôéÓ!rBP¸¡Ÿÿ¼®¨¨F"ïò“"´ÂOŠÐ4?G}=ŽŠ"×ÎgdPòc!† #—[WB} "

but when called like

<img src="http://fuelbuyer.dtn.com/energy/view/energy/chart.do?width=150&height=120&chartType=0&ts=1352196066175&rackId=446&productId=179&points=8&showExtraLine=True">

will give the correct image.

I really dont know what to do next.

How can I log into the site using cURL and execute this line.
<img src="http://fuelbuyer.dtn.com/energy/view/energy/chart.do?width=150&height=120&chartType=0&ts=1352196066175&rackId=446&productId=179&points=8&showExtraLine=True">
The site will be redirected to the home page when successfully logged in.
So, I have to prevent from redirection too.
The session will be terminated after few seconds.

Thanking you in advance,
Eugine P J

I got it working. Refer this comment.
Unable to fetch my schedule data from my schools site. Login with cURL wont work

Answer 1

You need to let the browser know that it's an image, try adding this to your PHP code:

header("Content-Type: image/png");
$ch = curl_init();
$url = 'http://img842.imageshack.us/img842/7650/pngtransparencydemonstr.png';
curl_setopt($ch, CURLOPT_URL, $url);
curl_setopt($ch, CURLOPT_RETURNTRANSFER, 1);
curl_setopt($ch, CURLOPT_FOLLOWLOCATION, 1);
curl_setopt($ch, CURLOPT_HEADER, 0);
$output = curl_exec($ch);
$info = curl_getinfo($ch);
curl_close($ch);
echo $output;

Answer 2

The image you received with cURL is correct (see, you get a PNG header).

If you want to display it on a page of yours - let's ignore licensing issues here - you need to put your scraping code, above, in a page of its own, e.g. myimage.php.

Then in your HTML code you put

<img src="myimage.php" />

and in the myimage.php, once you have $output, you just output it:

<?php
$ch  = curl_init();
$url = 'http://fuelbuyer.dtn.com/energy/common/signin.do?';
$login = 'username='.$USER.'&password=$pass&autoLogin=true&partnerId=0&partnerName=';
curl_setopt($ch, CURLOPT_URL, $url.$login);
curl_setopt($ch, CURLOPT_RETURNTRANSFER, 1);
curl_setopt($ch, CURLOPT_FOLLOWLOCATION, 1);
curl_setopt($ch, CURLOPT_HEADER, 0);
$output = curl_exec($ch);
// $info = curl_getinfo($ch);
curl_close($ch); 

// Let's suppose that $content (what we want to send) is exactly equal to $output
$content = $output;
// If, instead, we have in the output something like <img src="crypto-unique.png" />"
// we will need to parse $output (using XML maybe, or, just this once, a regex)
// and get its URL, then retrieve the image using cURL again, and *this* will be our
// final $content.

// Just output
Header("Content-Type: image/png");
Header("Content-Length: " . strlen($content));
die($content);

// Or if we wanted to manipulate it, e.g. send it as JPEG at 75% quality
$gd = imageCreateFromString($content);
Header('Content-Type: image/jpeg');
ImageJPEG($gd, '', 75);
die();

?>

For the sordid details of more complicated login schemes, see the answer to How can I scrape website content in PHP from a website that requires a cookie login?

Answer 3

Have you tried an image header?

header("Content-Type: image/png");
header("Content-Disposition: attachment; filename=image.png" );