Question

I’ve working on parsing an input, which is HTML. However, I need to be able to find all href or src attributes that DON’T have a protocol such as http://, https:// or ftp:// etc on them, and when they don’t replace it with a variable that contains a protocol and domain.

So for example I want

<a href="/_mylink/goes/here">Link 1</a>
<a href="http://site.com/_myotherlink/goes/here">Link 2</a>

to return:

<a href="http://mydomain.com/_mylink/goes/here">Link 1</a>
<a href="http://site.com/_myotherlink/goes/here">Link 2</a>

I can get the whole href attribute, but I can’t seem to work out how to only match and replace IF it’s missing a protocol. I found that [^0-9] would work in a inverse/not way, but I found i couldn’t get it to work when trying it with http:// etc.

Edit:

Just to make mention of it, as it’s become obvious to me that it’s part of the ‘scope’ of this question, I want to avoid having url encodings as a result of the replacement, as I use things like {} onto some of these, and I don’t want them to have things like %7B %7D in them.

Answer 1

Why not use the DOM to easily replace these attributes? For example

$domain = 'http://mydomain.com';
$currentPath = '/some/absolute/path/'; // make sure this starts and ends with a forward-slash

$doc = new DOMDocument();
$doc->loadHTML($html);

$xpath = new DOMXPath($doc);
$attrs = $xpath->query('//@href[not(contains(., "://"))]');
foreach ($attrs as $attr) {
    $attr->value = sprintf('%s%s%s',
        $domain,
        $attr->value[0] == '/' ? '' : $currentPath,
        htmlspecialchars($attr->value)
    );
}

$attrs = $xpath->query('//@src[not(contains(., "://"))]');
foreach ($attrs as $attr) {
    $attr->value = sprintf('%s%s%s',
        $domain,
        $attr->value[0] == '/' ? '' : $currentPath,
        htmlspecialchars($attr->value)
    );
}

echo $doc->saveHTML();