Typo3: Convert <link> to <a> Regex PHP

typo3_link_conversion_functions

<?php

function convert_external_link_tags($html)
{
    $pattern = '/<link\s(.+)\s-\s(.*)?\s(".*")?>(.+)<\/link>/U';
    $replacement = '<a href="$1" target="$2" title=$3>$4</a>';
    preg_match_all($pattern, $html, $matches, PREG_PATTERN_ORDER);
    return preg_replace($pattern, $replacement, $html);
}

function convert_internal_link_tags($html)
{
    $pattern = '/<link\s([0-9]+)>(.+)<\/link>/U';
    $replacement = '<a href="http://www.nnu.edu/index.php?id=$1">$2</a>';
    preg_match_all($pattern, $html, $matches, PREG_PATTERN_ORDER);
    return preg_replace($pattern, $replacement, $html);
}

?>

Many Thanks!