in reply to Parsing incorrect html

Or extract each inner html section and parse it separately. 

#!/usr/bin/perl

# http://perlmonks.org/?node_id=1192280

use strict;
use warnings;

$_ = do { local $/; <DATA> };

# find inner html sections

my $nestcount = 1;

while( s:(
  <html>               # starting html
  ((?!</?html>).)*?    # no html or /html in the middle
  </html>              # ending /html
  ): NON_NESTED_HTML $nestcount :sx )
  {
  my $nonnestedhtml = $1;
  print "NON_NESTED_HTML $nestcount\n\n$nonnestedhtml\n\n";
  $nestcount++;
  # here you can parse an inner non-nested html section
  }

print "this is what's left\n\n$_\n\n";

__DATA__
<!DOCTYPE html>
<html>
    <head>
        <script>/*some ugly header stuff*/</script>
    </head>
    <body>
        <html>
            <head>
                <script>/*some embedded document*/</script>
            </head>
            <body>
                <h1>Hello</h1>
                <p>this is a test</p>
                <p>this is a second test</p>
            </body>
        </html>
        <p>some kind of wrapped footer</p>
    </body>
</html>

[download]

Produces: 

NON_NESTED_HTML 1

<html>
            <head>
                <script>/*some embedded document*/</script>
            </head>
            <body>
                <h1>Hello</h1>
                <p>this is a test</p>
                <p>this is a second test</p>
            </body>
        </html>

NON_NESTED_HTML 2

<html>
    <head>
        <script>/*some ugly header stuff*/</script>
    </head>
    <body>
         NON_NESTED_HTML 1 
        <p>some kind of wrapped footer</p>
    </body>
</html>

this is what's left

<!DOCTYPE html>
 NON_NESTED_HTML 2

[download]

(parsing left as an exercise for the reader :)

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