Source
File: wp-includes/functions.php
function wp_privacy_anonymize_ip( $ip_addr, $ipv6_fallback = false ) {
// Detect what kind of IP address this is.
$ip_prefix = '';
$is_ipv6 = substr_count( $ip_addr, ':' ) > 1;
$is_ipv4 = ( 3 === substr_count( $ip_addr, '.' ) );
if ( $is_ipv6 && $is_ipv4 ) {
// IPv6 compatibility mode, temporarily strip the IPv6 part, and treat it like IPv4.
$ip_prefix = '::ffff:';
$ip_addr = preg_replace( '/^\[?[0-9a-f:]*:/i', '', $ip_addr );
$ip_addr = str_replace( ']', '', $ip_addr );
$is_ipv6 = false;
}
if ( $is_ipv6 ) {
// IPv6 addresses will always be enclosed in [] if there's a port.
$left_bracket = strpos( $ip_addr, '[' );
$right_bracket = strpos( $ip_addr, ']' );
$percent = strpos( $ip_addr, '%' );
$netmask = 'ffff:ffff:ffff:ffff:0000:0000:0000:0000';
// Strip the port (and [] from IPv6 addresses), if they exist.
if ( false !== $left_bracket && false !== $right_bracket ) {
$ip_addr = substr( $ip_addr, $left_bracket + 1, $right_bracket - $left_bracket - 1 );
} elseif ( false !== $left_bracket || false !== $right_bracket ) {
// The IP has one bracket, but not both, so it's malformed.
return '::';
}
// Strip the reachability scope.
if ( false !== $percent ) {
$ip_addr = substr( $ip_addr, 0, $percent );
}
// No invalid characters should be left.
if ( preg_match( '/[^0-9a-f:]/i', $ip_addr ) ) {
return '::';
}
// Partially anonymize the IP by reducing it to the corresponding network ID.
if ( function_exists( 'inet_pton' ) && function_exists( 'inet_ntop' ) ) {
$ip_addr = inet_ntop( inet_pton( $ip_addr ) & inet_pton( $netmask ) );
if ( false === $ip_addr ) {
return '::';
}
} elseif ( ! $ipv6_fallback ) {
return '::';
}
} elseif ( $is_ipv4 ) {
// Strip any port and partially anonymize the IP.
$last_octet_position = strrpos( $ip_addr, '.' );
$ip_addr = substr( $ip_addr, 0, $last_octet_position ) . '.0';
} else {
return '0.0.0.0';
}
// Restore the IPv6 prefix to compatibility mode addresses.
return $ip_prefix . $ip_addr;
}