Add a filter to array of allow ported number in multisite.

[spacedmonkey]

The allowed port numbers to setup a multisite are fixed. See this line.

        if ( ( false !== $has_ports && ! in_array( $has_ports, array( ':80', ':443' ), true ) ) ) {

However, a site maintainer may want to change these values to help enable serving their multisite from a custom port.

This ticket is a breakout from #21077

[realloc]

The code referenced in the description no longer exists. The $has_ports check with in_array( $has_ports, array( ':80', ':443' ), true ) has been refactored out of core.

The underlying limitation is still present, though. The ports :80 and :443 remain hardcoded in two places, with no filter to allow custom ports:

wp-admin/includes/network.php (network setup):

$hostname = preg_replace( '/(?::80|:443)$/', '', get_clean_basedomain() );

wp-includes/ms-settings.php (bootstrap):

if ( str_ends_with( $domain, ':80' ) ) {
    ...
} elseif ( str_ends_with( $domain, ':443' ) ) {
    ...
}

So the enhancement is still valid, but the description should be updated to point at these two locations. A filter would need to cover both to keep setup and bootstrap consistent.

Adds a ms_default_port_suffixes filter so site owners can customize which port suffixes are treated as "default" when Multisite bootstraps a request and when the Tools → Network Setup screen suggests a hostname, instead of the hardcoded :80/:443. Without this, a Multisite install served from a non-standard port (e.g. :8080) has no supported way to make that port behave like the standard ones during domain matching.

Introduces ms_default_port_suffixes() in wp-includes/functions.php, which wraps the new filter and defaults to array( ':80', ':443' ) — the same values previously hardcoded. Both existing call sites now use it: the Multisite bootstrap domain normalization in wp-includes/ms-settings.php, and the default hostname suggestion in wp-admin/includes/network.php's network setup wizard. Behavior is unchanged unless the new filter is used, since both call sites fall back to the same default port list.

The function is defined in wp-includes/functions.php (rather than an ms-* file) because wp-admin/includes/network.php runs during the one-time "enable Multisite" step, before Multisite itself is active — so ms-functions.php/ms-load.php aren't guaranteed loaded yet at that point, while functions.php always is.

Added tests/phpunit/tests/functions/msDefaultPortSuffixes.php, covering the default return value and that it can be filtered. The existing Tests_Multisite_Bootstrap suite (60 tests) continues to pass unchanged, confirming no regression to domain/network resolution.

## Use of AI Tools

AI assistance: Yes
Tool(s): Claude Code
Model(s): Claude Sonnet 5
Used for: Implementation, tests, and PR description. Reviewed by Igor Rozum.

Adds a ms_default_port_suffixes filter so site owners can customize which port suffixes are treated as "default" when Multisite bootstraps a request and when the Tools → Network Setup screen suggests a hostname, instead of the hardcoded :80/:443. Without this, a Multisite install served from a non-standard port (e.g. :8080) has no supported way to make that port behave like the standard ones during domain matching.

Introduces ms_default_port_suffixes() in wp-includes/functions.php, which wraps the new filter and defaults to array( ':80', ':443' ) — the same values previously hardcoded. Both existing call sites now use it: the Multisite bootstrap domain normalization in wp-includes/ms-settings.php, and the default hostname suggestion in wp-admin/includes/network.php's network setup wizard. Behavior is unchanged unless the new filter is used, since both call sites fall back to the same default port list.

The function is defined in wp-includes/functions.php (rather than an ms-* file) because wp-admin/includes/network.php runs during the one-time "enable Multisite" step, before Multisite itself is active — so ms-functions.php/ms-load.php aren't guaranteed loaded yet at that point, while functions.php always is.

Added tests/phpunit/tests/functions/msDefaultPortSuffixes.php, covering the default return value and that it can be filtered. The existing Tests_Multisite_Bootstrap suite (60 tests) continues to pass unchanged, confirming no regression to domain/network resolution.

## Use of AI Tools

AI assistance: Yes
Tool(s): Claude Code
Model(s): Claude Sonnet 5
Used for: Implementation, tests, and PR description. Reviewed by Igor Rozum.