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Net::CIDR − Manipulate IPv4/IPv6 netblocks in CIDR notation
use Net::CIDR;
use Net::CIDR ':all';
my $var;
if ($var = Net::CIDR::cidrvalidate($var))
{
// ... do something
}
print join("\n",
Net::CIDR::range2cidr("192.168.0.0−192.168.255.255",
"10.0.0.0−10.3.255.255"))
. "\n";
#
# Output from above:
#
# 192.168.0.0/16
# 10.0.0.0/14
print join("\n",
Net::CIDR::range2cidr(
"dead:beef::−dead:beef:ffff:ffff:ffff:ffff:ffff:ffff"))
. "\n";
#
# Output from above:
#
# dead:beef::/32
print join("\n",
Net::CIDR::range2cidr("192.168.1.0−192.168.2.255"))
. "\n";
#
# Output from above:
#
# 192.168.1.0/24
# 192.168.2.0/24
print join("\n",
Net::CIDR::cidr2range("192.168.0.0/16")) .
"\n";
#
# Output from above:
#
# 192.168.0.0−192.168.255.255
print join("\n",
Net::CIDR::cidr2range("dead::beef::/46")) .
"\n";
#
# Output from above:
#
# dead:beef::−dead:beef:3:ffff:ffff:ffff:ffff:ffff
@list=("192.168.0.0/24");
@list=Net::CIDR::cidradd("192.168.1.0−192.168.1.255",
@list);
print join("\n", @list) . "\n";
#
# Output from above:
#
# 192.168.0.0/23
print join("\n",
Net::CIDR::cidr2octets("192.168.0.0/22")) .
"\n";
#
# Output from above:
#
# 192.168.0
# 192.168.1
# 192.168.2
# 192.168.3
print join("\n",
Net::CIDR::cidr2octets("dead::beef::/46")) .
"\n";
#
# Output from above:
#
# dead:beef:0000
# dead:beef:0001
# dead:beef:0002
# dead:beef:0003
@list=("192.168.0.0/24");
print Net::CIDR::cidrlookup("192.168.0.12",
@list);
#
# Output from above:
#
# 1
@list = Net::CIDR::addr2cidr("192.168.0.31");
print join("\n", @list);
#
# Output from above:
#
# 192.168.0.31/32
# 192.168.0.30/31
# 192.168.0.28/30
# 192.168.0.24/29
# 192.168.0.16/28
# 192.168.0.0/27
# 192.168.0.0/26
# 192.168.0.0/25
# 192.168.0.0/24
# 192.168.0.0/23
# [and so on]
print Net::CIDR::addrandmask2cidr("195.149.50.61",
"255.255.255.248")."\n";
#
# Output from above:
#
# 195.149.50.56/29
The Net::CIDR package contains functions that manipulate lists of IP netblocks expressed in CIDR notation. The Net::CIDR functions handle both IPv4 and IPv6 addresses.
The cidrvalidate() function, described below, checks that its argument is a single, valid IP address or a CIDR. The remaining functions expect that their parameters consist of validated IPs or CIDRs. See cidrvalidate() and BUGS, below, for more information.
@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.
Garbage in, garbage out. Always use cidrvalidate() before doing anything with untrusted input. Otherwise, "slightly" invalid input will work (extraneous whitespace is generally OK ), but the functions will croak if you’re totally off the wall.
Sam Varshavchik <sam@email−scan.com>
With some contributions from David Cantrell <david@cantrell.org.uk>