如何使用PHP简化IP地址？ 尝试long2ip（ip2long（address））

Question

My system includes a third party box that stores IP addresses and compares them to values sent from my Web interface. I have a problem that a user entered the netmask for the third party box as 255.255.255.000, and the box stored it as 255.255.255.0. However the next time the box reboots and is told that the mask includes 000 it concludes that these values are different and updates its database and reboots. And reboots. And reboots.

My intent is to solve this by storing the netmask in my own system in the simplified form 255.255.255.0 (and as another example store 010.001.002.005 as 10.1.2.5). But I'm brand new to PHP. I tried code $mask = long2ip(ip2long($mask)) to convert the entry to a standardized form but just got back 0.0.0.0. Is there something special I need to do to convert the IP to long and back? Is there a better way to simplify this?

Answer 1

ip2long returns false on an error and it doesn't seem to detect 000 as valid. Since 255.255.255.000 isn't detected as a valid IP, it will return false, so long2ip(false) won't spit out a valid IP.

You could just check that ip2long(input) returns true before even accepting the IP address. Having proper validation in place would prevent invalid IPs from breaking the system. Trying to implement auto-correction for all of the possible invalid IP addresses is going to be much harder than just enforcing a valid IP to begin with.

Answer 2

To follow the suggestion by @ka_lin in the comments, just explode it into parts, convert it to an int which will drop leading 0's and rebuild it with implode...

$mask = implode(".", array_map("intval", explode(".", $mask)));

A simple and less overhead version assumes 4 parts to the IP address...

list ($o1, $o2, $o3, $o4) = explode(".", $mask);
$mask = (int)$o1.".".(int)$o2.".".(int)$o3.".".(int)$o4;

It is difficult as 010.001.002.005 is a valid IP address, but could also be confusing (sometimes numbers starting with a 0 are octal).

Answer 3

A note: ip2long() has an issue: It doesn't accept the valid ip address 127.1 (classic a notation, but valid!) or 127.0.0.010 (RFC says invalid, but most read 010 as octal number).

The alternative if gethostbyname() . But gethostbyname() has issues too: If an invalid ip is entered (like 127.0.0.1234 ), it makes a DNS lookup and returns the source, if the lookup fails.

A solution can be:

long2ip(ip2long(gethostbyname($IP_ADDRESS)))

My personal solution is the following function:

function aton ( $addr )
{
    $l = explode('.',$addr);
    switch (count($l))
    {
        case 0: return FALSE;

        case 1: return intval($l[0]) & 0xffffffff;

        case 2: return  ( intval($l[0]) << 24
                        | intval($l[1])
                        ) & 0xffffffff;

        case 3: return  ( intval($l[0]) << 24
                        | intval($l[1]) << 16
                        | intval($l[2])
                        ) & 0xffffffff;

        default: return ( intval($l[0]) << 24
                        | intval($l[1]) << 16
                        | intval($l[2]) <<  8
                        | intval($l[3])
                        ) & 0xffffffff;
    }
}

With this function, you can use:

long2ip(aton($IP_ADDRESS))

btw, I had never issues with special ip addresses like 255.255.255.0 .