<?php
$html = '<html>
<head>
<meta name="keywords" content="slovo, slovo2, slovo3">
<meta name="description" content="Tento text potřebuji vyextrahovat">
</head>';
$doc = new DOMDocument();
@$doc->loadHTML($html);
$tags = $doc->getElementsByTagName('meta');
foreach ($tags as $tag) {
echo $tag->getAttribute('content');
}
PD9waHAKCiRodG1sID0gJzxodG1sPgo8aGVhZD4KPG1ldGEgbmFtZT0ia2V5d29yZHMiIGNvbnRlbnQ9InNsb3ZvLCBzbG92bzIsIHNsb3ZvMyI+CjxtZXRhIG5hbWU9ImRlc2NyaXB0aW9uIiBjb250ZW50PSJUZW50byB0ZXh0IHBvdMWZZWJ1amkgdnlleHRyYWhvdmF0Ij4gCjwvaGVhZD4nOwoKJGRvYyA9IG5ldyBET01Eb2N1bWVudCgpOwpAJGRvYy0+bG9hZEhUTUwoJGh0bWwpOwokdGFncyA9ICRkb2MtPmdldEVsZW1lbnRzQnlUYWdOYW1lKCdtZXRhJyk7CgoKIApmb3JlYWNoICgkdGFncyBhcyAkdGFnKSB7CiAgICAgICBlY2hvICR0YWctPmdldEF0dHJpYnV0ZSgnY29udGVudCcpOwogCiAgICAgICAgfQ==