Net::CIDR3pm

@cidr_list=Net::CIDR::range2cidr(@range_list);

Each element in the @range_list is a string "start-finish", where "start" is the first IP address and "finish" is the last IP address. range2cidr() converts each range into an equivalent CIDR netblock. It returns a list of netblocks except in the case where it is given only one parameter and is called in scalar context.

For example:

    @a=Net::CIDR::range2cidr("192.168.0.0-192.168.255.255");

The result is a one-element array, with $a[0] being "192.168.0.0/16". range2cidr() processes each "start-finish" element in @range_list separately. But if invoked like so:

    $a=Net::CIDR::range2cidr("192.168.0.0-192.168.255.255");

The result is a scalar "192.168.0.0/16".

Where each element cannot be expressed as a single CIDR netblock range2cidr() will generate as many CIDR netblocks as are necessary to cover the full range of IP addresses. Example:

    @a=Net::CIDR::range2cidr("192.168.1.0-192.168.2.255");

The result is a two element array: ("192.168.1.0/24","192.168.2.0/24");

    @a=Net::CIDR::range2cidr(
                   "d08c:43::-d08c:43:ffff:ffff:ffff:ffff:ffff:ffff");

The result is an one element array: ("d08c:43::/32") that reflects this IPv6 netblock in CIDR notation.

range2cidr() does not merge adjacent or overlapping netblocks in @range_list.

@range_list=Net::CIDR::cidr2range(@cidr_list);

The cidr2range() functions converts a netblock list in CIDR notation to a list of "start-finish" IP address ranges:

    @a=Net::CIDR::cidr2range("10.0.0.0/14", "192.168.0.0/24");

The result is a two-element array: ("10.0.0.0-10.3.255.255", "192.168.0.0-192.168.0.255").

    @a=Net::CIDR::cidr2range("d08c:43::/32");

The result is a one-element array: ("d08c:43::-d08c:43:ffff:ffff:ffff:ffff:ffff:ffff").

cidr2range() does not merge adjacent or overlapping netblocks in @cidr_list.

@netblock_list = Net::CIDR::addr2cidr($address);

The addr2cidr function takes an IP address and returns a list of all the CIDR netblocks it might belong to:

    @a=Net::CIDR::addr2cidr('192.168.0.31');

The result is a thirtythree-element array: ('192.168.0.31/32', '192.168.0.30/31', '192.168.0.28/30', '192.168.0.24/29',
[and so on]) consisting of all the possible subnets containing this address from 0.0.0.0/0 to address/32.

Any addresses supplied to addr2cidr after the first will be ignored. It works similarly for IPv6 addresses, returning a list of one hundred and twenty nine elements.

$cidr=Net::CIDR::addrandmask2cidr($address, $netmask);

The addrandmask2cidr function takes an IP address and a netmask, and returns the CIDR range whose size fits the netmask and which contains the address. It is an error to supply one parameter in IPv4-ish format and the other in IPv6-ish format, and it is an error to supply a netmask which does not consist solely of 1 bits followed by 0 bits. For example, '255.255.248.192' is an invalid netmask, as is '255.255.255.32' because both contain 0 bits in between 1 bits.

Technically speaking both of those *are* valid netmasks, but a) you'd have to be insane to use them, and b) there's no corresponding CIDR range.

@octet_list=Net::CIDR::cidr2octets(@cidr_list);

cidr2octets() takes @cidr_list and returns a list of leading octets representing those netblocks. Example:

    @octet_list=Net::CIDR::cidr2octets("10.0.0.0/14", "192.168.0.0/24");

The result is the following five-element array: ("10.0", "10.1", "10.2", "10.3", "192.168.0").

For IPv6 addresses, the hexadecimal words in the resulting list are zero-padded:

    @octet_list=Net::CIDR::cidr2octets("::dead:beef:0:0/110");

The result is a four-element array: ("0000:0000:0000:0000:dead:beef:0000", "0000:0000:0000:0000:dead:beef:0001", "0000:0000:0000:0000:dead:beef:0002", "0000:0000:0000:0000:dead:beef:0003"). Prefixes of IPv6 CIDR blocks should be even multiples of 16 bits, otherwise they can potentially expand out to a 32,768-element array, each!

@cidr_list=Net::CIDR::cidradd($block, @cidr_list);

The cidradd() functions allows a CIDR list to be built one CIDR netblock at a time, merging adjacent and overlapping ranges. $block is a single netblock, expressed as either "start-finish", or "address/prefix". Example:

    @cidr_list=Net::CIDR::range2cidr("192.168.0.0-192.168.0.255");
    @cidr_list=Net::CIDR::cidradd("10.0.0.0/8", @cidr_list);
    @cidr_list=Net::CIDR::cidradd("192.168.1.0-192.168.1.255", @cidr_list);

The result is a two-element array: ("10.0.0.0/8", "192.168.0.0/23"). IPv6 addresses are handled in an analogous fashion.

$found=Net::CIDR::cidrlookup($ip, @cidr_list);

Search for $ip in @cidr_list. $ip can be a single IP address, or a netblock in CIDR or start-finish notation. lookup() returns 1 if $ip overlaps any netblock in @cidr_list, 0 if not.

$ip=Net::CIDR::cidrvalidate($ip);

Validate whether $ip is a valid IPv4 or IPv6 address, or a CIDR. Returns its argument or undef. Spaces are removed, and IPv6 hexadecimal address are converted to lowercase.

$ip with less than four octets gets filled out with additional octets, and the modified value gets returned. This turns "192.168/16" into a proper "192.168.0.0/16".

If $ip contains a "/", it must be a valid CIDR, otherwise it must be a valid IPv4 or an IPv6 address.

A technically invalid CIDR, such as "192.168.0.1/24" fails validation, returning undef.