How to curl and display image where file type is unknown from url

Question

Background

I am building an image search for oscobo, a privacy search engine.
We use a Bing URL to fetch thumbnails to display to the user on the image search results page. For example: https://oscobo.com/image.php?q=london.
We do not want to connect the client to Bing directly (as in the above example) but intend to use a reverse proxy script that uses cURL to fetch the image and then send it back to the browser.
The script works well when we know what the file type is (e.g. jpg) and we can pick the correct content-type for the Header accordingly before we echo the image back to the browser.
The problem we have is that the URL to Bing does not contain the filetype, it looks along the lines of http://tse3.mm.bing.net/th?id=OIP.M1a65dd11fb2b159f4fe44eba7dcfa0a6H0&pid=15.1&H=90&W=160

Question

How can we modify this script to work with the URL that does not display the file type?

Any ideas or input much appreciated.

The PHP on the page

$html = '';
$images = $results->bossresponse->images->results;
foreach ($images as $image) {
                    $theurl = "{$image->thumbnailurl}";
                    $theurl = base64_encode($theurl);
                    $reverseurl = "reverseproxy.php?url=$theurl";
                    $html .= "<a href=\"{$image->clickurl}\"> <img class=border src=\"$reverseurl\" height=\"140px\"></a>";
                    }
echo $html;

The reverse script reverseproxy.php

<?php
$file = base64_decode(@$_GET['url']);
$aFile = end(explode('.' , $file));
if($aFile == 'jpg' or $aFile == 'jpeg'){
header('Content-Type: image/jpeg');
}elseif($aFile == 'png'){
header('Content-Type: image/png');
}elseif($aFile == 'gif'){
header('Content-Type: image/gif');
}else{
die('not supported');
}

if($file != ''){
        $cache_expire = 60*60*24*365;
        header("Pragma: public");
        header("Cache-Control: maxage=". $cache_expire);
        header('Expires: ' . gmdate('D, d M Y H:i:s', time() +         $cache_expire).' GMT');

//The cURL stuff...
$ch = curl_init();
curl_setopt($ch, CURLOPT_URL, "$file");
curl_setopt($ch, CURLOPT_HEADER, 0);
curl_setopt($ch, CURLOPT_RETURNTRANSFER, 1);
curl_setopt($ch, CURLOPT_BINARYTRANSFER,1);
$picture = curl_exec($ch);
curl_close($ch);
//Display the image in the browser

echo $picture;

    }
    exit;      

    ?>

Have you looked at CURLOPT_HEADERFUNCTION to read the HTTP header as the file is downloaded? http://stackoverflow.com/questions/6482068/curl-setoptch-curlopt-headerfunction-arraythis-readheader-not-working — RCrowt, Jan 05 '16 at 18:46

score 1 · Accepted Answer · edited May 23 '17 at 11:44

A quick test in the console shows that the image type information can be obtained from the response header: curl -D headers.txt http://tse3.mm.bing.net/th?id=OIP.M1a65dd11fb2b159f4fe44eba7dcfa0a6H0&pid=15.1&H=90&W=160 So you could consider the HTTP response header. This answer shows how it can be done with cURL in PHP: Can PHP cURL retrieve response headers AND body in a single request?

Hope this helps, good luck!

How to curl and display image where file type is unknown from url

1 Answers1