How to upload an internet file without an extension

I'm generating a QR code that I then want to upload to my server. Problem is, the image / qr code, while it looks great on the screen, doesn't have your typical URL in that there's no extension, at least as far as I can see.

Here's the image source code: https://chart.googleapis.com/chart?cht=qr&chs=250x250&chl=http://www.countryshowdown.com/app/view_contestants.php?id=53102&choe=UTF-8&chld=L

I can tell that it's a PNG when I look at the properties, but how do I convert the above mess into something that your typical upload script will understand and execute?

Right now, I'm using this ($url is the image source code you see above):

$name = basename($url);
list($txt, $ext) = explode(".", $name);
$name = $txt.time();
$name = $name.".".$ext;
 echo $ext;
//check if the files are only image / document
if($ext == "jpg" or $ext == "png" or $ext == "gif" or $ext == "doc" or $ext == "docx" or $ext == "pdf")
{
//here is the actual code to get the file from the url and save it to the uploads folder
//get the file from the url using file_get_contents and put it into the folder using file_put_contents
$upload = file_put_contents("qr/$name",file_get_contents($url));
//check success

if($upload)  echo "Success: <a href='qr/".$name."' target='_blank'>Check Uploaded</a>"; else "please check your folder permission";
}
else
{
echo "Please upload only image/document files";
}

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The result is the error that's cued to trigger when the code doesn't see a recognizable extension. How do I transform the above url into file name with an png extension that can then be uploaded?