yii\validators\IpValidator::validateSubnet PHP Method

    private function validateSubnet($ip)
    {
        if (!is_string($ip)) {
            return [$this->message, []];
        }
        $negation = null;
        $cidr = null;
        $isCidrDefault = false;
        if (preg_match($this->getIpParsePattern(), $ip, $matches)) {
            $negation = $matches[1] !== '' ? $matches[1] : null;
            $ip = $matches[2];
            $cidr = isset($matches[4]) ? $matches[4] : null;
        }
        if ($this->subnet === true && $cidr === null) {
            return [$this->noSubnet, []];
        }
        if ($this->subnet === false && $cidr !== null) {
            return [$this->hasSubnet, []];
        }
        if ($this->negation === false && $negation !== null) {
            return [$this->message, []];
        }
        if ($this->getIpVersion($ip) == 6) {
            if ($cidr !== null) {
                if ($cidr > static::IPV6_ADDRESS_LENGTH || $cidr < 0) {
                    return [$this->wrongCidr, []];
                }
            } else {
                $isCidrDefault = true;
                $cidr = static::IPV6_ADDRESS_LENGTH;
            }
            if (!$this->ipv6) {
                return [$this->ipv6NotAllowed, []];
            }
            if (!$this->validateIPv6($ip)) {
                return [$this->message, []];
            }
            if ($this->expandIPv6) {
                $ip = $this->expandIPv6($ip);
            }
        } else {
            if ($cidr !== null) {
                if ($cidr > static::IPV4_ADDRESS_LENGTH || $cidr < 0) {
                    return [$this->wrongCidr, []];
                }
            } else {
                $isCidrDefault = true;
                $cidr = static::IPV4_ADDRESS_LENGTH;
            }
            if (!$this->ipv4) {
                return [$this->ipv4NotAllowed, []];
            }
            if (!$this->validateIPv4($ip)) {
                return [$this->message, []];
            }
        }
        if (!$this->isAllowed($ip, $cidr)) {
            return [$this->notInRange, []];
        }
        $result = $negation . $ip;
        if ($this->subnet !== false && (!$isCidrDefault || $isCidrDefault && $this->normalize)) {
            $result .= "/{$cidr}";
        }
        return $result;
    }