The comment_max_links_url
filter
We can count the number of internal links in the comment’s content and subtract that from the total number of links found there ($num_links
), with the help of the following filter inside the check_comment()
core function:
/**
* Filters the number of links found in a comment
*
* @since 3.0.0
* @since 4.7.0 Added the `$comment` parameter.
*
* @param int $num_links The number of links found.
* @param string $url Comment author's URL. Included in allowed links total.
* @param string $comment Content of the comment.
*/
$num_links = apply_filters( 'comment_max_links_url', $num_links, $url, $comment );
The core only counts the number of <a>
tags, containing the href
attribute, with:
$num_links = preg_match_all( '/<a [^>]*href/i', $comment, $out );
Demo plugin – Allow links from the home url host
Here’s an example, to allow any internal links in the comment’s content:
/**
* Allow any internal links from the home url host, in the comment's content
*
* @see http://wordpress.stackexchange.com/a/257917/26350
*/
add_filter( 'comment_max_links_url', function( $num_links, $url, $comment )
{
// Allowed hosts
$allowed_host = wp_parse_url( home_url(), PHP_URL_HOST );
// Get all links
$all_links = preg_match_all(
'/<a [^>]*href=["\']([^"\']+)/i',
$comment,
$links
);
// No links
if( empty( $links[1] ) || ! is_array( $links[1] ) )
return $num_links;
// Count links that are from our home url domain
$internal_links = array_reduce(
$links[1],
function( $internal, $link ) use ( $allowed_host )
{
if( $allowed_host === wp_parse_url( $link, PHP_URL_HOST ) )
$internal += 1;
return $internal;
},
0
);
return ( $num_links - $internal_links );
}, 10, 3 );
Demo plugin – Allow links from multiple hosts
Here’s an example with multiple allowed hosts:
/**
* Allow any internal links, from multiple allowed hosts, in the comment's content
*
* @see http://wordpress.stackexchange.com/a/257917/26350
*/
add_filter( 'comment_max_links_url', function( $num_links, $url, $comment )
{
// Allowed hosts
$allowed_hosts = [ 'foo.tld', 'bar.tld' ]; // <-- Adjust to your needs!
// Get all links
$all_links = preg_match_all(
'/<a [^>]*href=["\']([^"\']+)/i',
$comment,
$links
);
// No links
if( empty( $links[1] ) || ! is_array( $links[1] ) )
return $num_links;
// Count links that are from our allowed hosts
$internal_links = array_reduce(
$links[1],
function( $internal, $link ) use ( $allowed_hosts )
{
if( in_array( wp_parse_url( $link, PHP_URL_HOST ), $allowed_hosts, true ) )
$internal += 1;
return $internal;
},
0
);
return ( $num_links - $internal_links );
}, 10, 3 );
We used array_reduce()
and wp_parse_url()
to help with the counting of the internal links or links from allowed hosts, in the above plugins.
Please test it further and adjust to your needs!