wp_kses_bad_protocol() │ WP 1.0.0

Sanitizes a string and removed disallowed URL protocols.

This function removes all non-allowed protocols from the beginning of the string. It ignores whitespace and the case of the letters, and it does understand HTML entities. It does its work recursively, so it won't be fooled by a string like javascript:javascript:alert(57).

No Hooks.

Returns

String. Filtered content.

Usage

wp_kses_bad_protocol( $content, $allowed_protocols );

$content(string) (required)

Content to filter bad protocols from.

$allowed_protocols(string[]) (required)

Array of allowed URL protocols.

Changelog

wp_kses_bad_protocol() wp kses bad protocol code ^{WP 6.9.1}

function wp_kses_bad_protocol( $content, $allowed_protocols ) {
	$content = wp_kses_no_null( $content );

	// Short-circuit if the string starts with `https://` or `http://`. Most common cases.
	if (
		( str_starts_with( $content, 'https://' ) && in_array( 'https', $allowed_protocols, true ) ) ||
		( str_starts_with( $content, 'http://' ) && in_array( 'http', $allowed_protocols, true ) )
	) {
		return $content;
	}

	$iterations = 0;

	do {
		$original_content = $content;
		$content          = wp_kses_bad_protocol_once( $content, $allowed_protocols );
	} while ( $original_content !== $content && ++$iterations < 6 );

	if ( $original_content !== $content ) {
		return '';
	}

	return $content;
}