This library for PHP 7.4 builds an abstraction over management of Internet Protocol versions, addresses and CIDR blocks.
Using this library makes it easy to check if an IP address belongs to a subnet or not.
Installing this library can be done via Composer:
$ composer require chialab/ipuse Chialab\Ip;
$address = Ip\Address::parse('192.168.1.1');
var_dump($address->getProtocolVersion() === Ip\ProtocolVersion::ipv4()); // bool(true)
var_dump($address->getProtocolVersion() === Ip\ProtocolVersion::ipv6()); // bool(false)
$subnet = Ip\Subnet::parse('fec0::1/16');
var_dump((string)$subnet->getFirstAddress()); // string(6): "fec0::"
var_dump((string)$subnet->getNetmask()); // string(6) "ffff::"
var_dump($subnet->contains($address)); // bool(false)
var_dump($subnet->contains(Ip\Address::parse('fec0:fe08:0123:4567:89ab:cdef:1234:5678'))); // bool(true)
var_dump($subnet->hasSubnet(Ip\Subnet::parse('fec0:fe08::/32'))); // bool(true)