All these checks:
```if(inet_pton($ip) < (int) inet_pton($subnet)) {// ...}
if(! (inet_pton($ip) < inet_pton($bcast))) {// ...}
if($ip == $backend) {// ...}```
can be bypassed by using IP address with the last part starts with `0: 192.168.112.02`. The `file_get_contents` function will normalize the IP into 192.168.112.2 and fetch the content.