how I can extract images from html code and then validate if are stored in my web server

Question

I've been working on a post editor, I want to generate thumbnails from all images inserted on the html code, so, before to do that I want to get all basic image attributes

example:

$mydomain = 'mysite.com';
$htmlcode = <<<EOD
<p>sample text</p>
<img src='/path/to/my/image.ext' width='120' height='90'  />
<hr />
<img src='html://www.mysite.com/some/ther/path/image.ext' /> <!-- no attributes -->
<hr />
<p>blah blah <img src="http://www.notmyserver.com/path/lorem-ipsum.ext" widht='120' height='90' /></p>
EOD;


function get_all_image_attributes($htmlcode){    
// some code... 
return $images; // array with image src (required), width (if has), heigth (if has)...
}

// then validate (I really need this part)    
$images   = get_all_image_attributes($htmlcode);

function verify($images,$mydomain){
// code...
return $valid_images;
}

A valid image would be (.jpg, .jpeg, .gif, .png)

src="/path/image.ext"

src="http://www.mysite.com/path/image.ext"

src="http://www.mysite.com/some/path/image.ext"

src="http://mysite.com/some/path/image.ext"

src="www.mysite.com/path/image.ext"

ps.

The part to generate thumbnails is already done, don't worry :)

updated

//I have done the following
$html = str_get_html($html);
$images = $html->find('img');
foreach ($images as $image){
 $filename = getfilename($image);
// I would like validate the file if is located in other path,
// or if it contains 'http://[www.]mysite.com/'
 if(file_exists(PUBLICPATH.'post_images/'.$filename))
  valid_imgs[] =  BASEURL.'post_images/'.$filename;
}

function getfilename($full_filename){
    $filename = substr( strrchr($full_filename , "/") ,1); 
    if(!$filename)
      $filename = $full_filename; 
    $filename = preg_replace("/^[.]*/","",$filename);
    return $filename;
}

Answer 1

Use an HTML parser. With PHP Simple HTML DOM Parser, you can do something along the lines of this:

$html = str_get_html($htmlcode);
foreach($html->find('img') as $element) {
    verify_image($element->src);
}

Answer 2

something like this would probably be good:

#!/usr/bin/perl 
open(F, 'tmp.txt');
while(<F>) { 
   while (m/img[^>]* src="([^"]+)"/g) { 
      my $imgurl = $1;
      verify_image($imgurl);
   }
}