PHP Detecting if source image url link leads to a “broken” image?

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Suppose you have a thumbnail generator script that accepts source images in the form of a URL. Is there a way to detect if the source URL is \"broken\" - whether nonexistent

onerror Event

Execute a JavaScript if an error occurs when loading an image:

The onerror event is triggered if an error occurs while loading an external file (e.g. a document or an image).

Example:

<!DOCTYPE html>
<html>
<body>

<img src="image.gif" onerror="myFunction()">

<p>A function is triggered if an error occurs when loading the image. The function shows an alert box with a text.
In this example we refer to an image that does not exist, therefore the onerror event occurs.</p>

<script>
function myFunction() {
  alert('The image could not be loaded.');
}
</script>

</body>
</html>

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-上瘾入骨i

2020-12-30 04:35
The only really reliable way is to request the image using file_get_contents(), and finding out its image type using getimagesize().

Only if getimagesize() returns a valid file type, can you rely that it is in fact a valid image.

This is quite resource heavy, though.

You could consider not doing any server-side checks at all, and adding an onerror JavaScript event to the finished image resource:
```
<img src="..." onerror="this.style.display = 'none'">
```
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慢半拍i

2020-12-30 04:37

Fast Solution for broken or not found images link
i suggest you that don't use getimagesize() because it will 1st download image then it will check images size+if this will not image then it will throw exception so use below code

if(checkRemoteFile($imgurl))
{
//found url, its mean
echo "this is image";
}

function checkRemoteFile($url)
{
    $ch = curl_init();
    curl_setopt($ch, CURLOPT_URL,$url);
    // don't download content
    curl_setopt($ch, CURLOPT_NOBODY, 1);
    curl_setopt($ch, CURLOPT_FAILONERROR, 1);
    curl_setopt($ch, CURLOPT_RETURNTRANSFER, 1);
    if(curl_exec($ch)!==FALSE)
    {
        return true;
    }
    else
    {
        return false;
    }
}

Note: this current code help you to identify broken or not found url image this will not help you to identify image type or headers

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北荒

2020-12-30 04:38

did you try file_get_contents() method?

http://php.net/manual/en/function.file-get-contents.php

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面向向阳花

2020-12-30 04:39

use file_exists function in php, you can check urls with it.

See documentation below, shows how to check img... exactly what you need

FILE EXISTS - http://www.php.net/manual/en/function.file-exists.php#93572

URL EXISTS - http://www.php.net/manual/en/function.file-exists.php#85246

Here is alternative code for checking the url. If you will test in browser replace \n with <br/>

<?php

$urls = array('http://www.google.com/images/logos/ps_logo2.png', 'http://www.google.com/images/logos/ps_logo2_not_exists.png');

foreach($urls as $url){
   echo "$url - ";
   echo url_exists($url) ? "Exists" : 'Not Exists';
   echo "\n\n";
}


function url_exists($url) {
    $hdrs = @get_headers($url);

    echo @$hdrs[1]."\n";

    return is_array($hdrs) ? preg_match('/^HTTP\\/\\d+\\.\\d+\\s+2\\d\\d\\s+.*$/',$hdrs[0]) : false;
}
?>

Output is as follows

http://www.google.com/images/logos/ps_logo2.png - Content-Type: image/png
Exists

http://www.google.com/images/logos/ps_logo2_not_exists.png - Content-Type: text/html; charset=UTF-8
Not Exists

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