Same exact thing using YAPE::HTML ;)( YAPE::HTML is pure-perl for those who don't know)

use YAPE::HTML;
use Data::Dumper;
use strict;
use warnings;

my $content = q[
<img src="img.link1">
<img src="img.link2" alt="foo">
<img height=20 width=25 src=img.link3 >
<IMG src='img.link4'>
<link href="css.link1">
<a class=foo href="normal.link1">
<A href=normal.link2 class="foo" >
<a href="normal.link3">
<a class=foo href='normal.link4'>
<a Href='normal.link5'>
];

my $parser  = YAPE::HTML->new($content);

my( @a, @link, @img );

# here is the tokenizing part
while ( my $chunk = $parser->next ) {
    if( $chunk->type eq 'tag' ){
        if( $chunk->tag eq 'a' ){
            push @a,
                $chunk->get_attr('href')
                    if $chunk->has_attr('href');
        }
        elsif( $chunk->tag eq 'link' ){
            push @link,
                $chunk->get_attr('href')
                    if $chunk->has_attr('href');
        }
        elsif($chunk->tag eq 'img'){
            push @img,
                $chunk->get_attr('src')
                    if $chunk->has_attr('src');
        }
    }
}

print Dumper \@img,\@link,\@a;

__END__

$VAR1 = [
          'img.link1',
          'img.link2',
          'img.link3',
          'img.link4'
        ];
$VAR2 = [
          'css.link1'
        ];
$VAR3 = [
          'normal.link1',
          'normal.link2',
          'normal.link3',
          'normal.link4',
          'normal.link5'
        ];
[download]