class Subnet::IPv6

Overview

Class Subnet::IPv6 is used to handle IPv6 type addresses.

IPv6 addresses

IPv6 addresses are 128 bits long, in contrast with IPv4 addresses which are only 32 bits long. An IPv6 address is generally written as eight groups of four hexadecimal digits, each group representing 16 bits or two octect. For example, the following is a valid IPv6 address:

2001:0db8:0000:0000:0008:0800:200c:417a

Letters in an IPv6 address are usually written downcase, as per RFC. You can create a new IPv6 object using uppercase letters, but they will be converted.

Compression

Since IPv6 addresses are very long to write, there are some semplifications and compressions that you can use to shorten them.

Using compression, the IPv6 address written above can be shorten into the following, equivalent, address

2001:db8::8:800:200c:417a

This short version is often used in human representation.

Network Mask

As we used to do with IPv4 addresses, an IPv6 address can be written using the prefix notation to specify the subnet mask:

2001:db8::8:800:200c:417a/64

The /64 part means that the first 64 bits of the address are representing the network portion, and the last 64 bits are the host portion.

Included Modules

Direct Known Subclasses

Defined in:

subnet/ipv6.cr

Constant Summary

IN6FORMAT = ("%04x:" * 8).chomp(':')

Format string to pretty print IPv6 addresses

Constructors

Class Method Summary

Instance Method Summary

Instance methods inherited from module Subnet

ipv4? ipv4?, ipv6? ipv6?, to_json(json : JSON::Builder) to_json

Constructor methods inherited from module Subnet

new(value : JSON::PullParser) : Subnet new, parse(str) : Subnet parse

Class methods inherited from module Subnet

deprecate(message = nil) deprecate, ntoa(uint) ntoa, valid?(addr) valid?, valid_ip?(addr) valid_ip?, valid_ipv4?(addr) valid_ipv4?, valid_ipv4_netmask?(addr) valid_ipv4_netmask?, valid_ipv4_subnet?(addr) valid_ipv4_subnet?, valid_ipv6?(addr) valid_ipv6?, valid_ipv6_subnet?(addr) valid_ipv6_subnet?

Constructor Detail

def self.new(str : String) #

Creates a new IPv6 address object.

An IPv6 address can be expressed in any of the following forms:

  • "2001:0db8:0000:0000:0008:0800:200C:417A": IPv6 address with no compression
  • "2001:db8:0:0:8:800:200C:417A": IPv6 address with leading zeros compression
  • "2001:db8::8:800:200C:417A": IPv6 address with full compression

In all these 3 cases, a new IPv6 address object will be created, using the default subnet mask /128

You can also specify the subnet mask as with IPv4 addresses:

ip6 = Subnet.parse "2001:db8::8:800:200c:417a/64"

[View source]
def self.new(value : JSON::PullParser) : Subnet::IPv6 #

[View source]

Class Method Detail

def self.compress(str) #

Compress an IPv6 address in its compressed form

Subnet::IPv6.compress "2001:0DB8:0000:CD30:0000:0000:0000:0000"
# => "2001:db8:0:cd30::"

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def self.expand(str) #

Expands an IPv6 address in the canocical form

Subnet::IPv6.expand "2001:0DB8:0:CD30::"
# => "2001:0DB8:0000:CD30:0000:0000:0000:0000"

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def self.groups(str) #

Extract 16 bits groups from a string


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def self.parse_data(data, prefix = 128) #

Creates a new IPv6 object from binary data, like the one you get from a network stream.

For example, on a network stream the IP

"2001:db8::8:800:200c:417a"

is represented with the binary data

" \001\r\270\000\000\000\000\000\b\b\000 \fAz"

With that data you can create a new IPv6 object:

ip6 = Subnet::IPv6::parse_data " \001\r\270\000\000\000\000\000\b\b\000 \fAz"
ip6.prefix = 64

ip6.to_s
# => "2001:db8::8:800:200c:417a/64"

[View source]
def self.parse_hex(hexstring, prefix = 128) #

Creates a new IPv6 object from a number expressed in hexdecimal format:

ip6 = Subnet::IPv6::parse_hex("20010db80000000000080800200c417a")
ip6.prefix = 64

ip6.to_string
# => "2001:db8::8:800:200c:417a/64"

The #prefix parameter is optional:

ip6 = Subnet::IPv6::parse_hex("20010db80000000000080800200c417a", 64)

ip6.to_string
# => "2001:db8::8:800:200c:417a/64"

[View source]
def self.parse_u128(u128, prefix = 128) #

Creates a new IPv6 object from an unsigned 128 bits integer.

ip6 = Subnet::IPv6::parse_u128(42540766411282592856906245548098208122)
ip6.prefix = 64

ip6.to_string
# => "2001:db8::8:800:200c:417a/64"

The #prefix parameter is optional:

ip6 = Subnet::IPv6::parse_u128(42540766411282592856906245548098208122, 64)

ip6.to_string
# => "2001:db8::8:800:200c:417a/64"

[View source]

Instance Method Detail

def <=>(oth) #

Spaceship operator to compare IPv6 objects

Comparing IPv6 addresses is useful to ordinate them into lists that match our intuitive perception of ordered IP addresses.

The first comparison criteria is the u128 value. For example, 2001:db8:1::1 will be considered to be less than 2001:db8:2::1, because, in a ordered list, we expect 2001:db8:1::1 to come before 2001:db8:2::1.

The second criteria, in case two IPv6 objects have identical addresses, is the prefix. An higher prefix will be considered greater than a lower prefix. This is because we expect to see 2001:db8:1::1/64 come before 2001:db8:1::1/65

Example:

ip1 = Subnet.parse "2001:db8:1::1/64"
ip2 = Subnet.parse "2001:db8:2::1/64"
ip3 = Subnet.parse "2001:db8:1::1/65"

ip1 < ip2
# => true
ip1 < ip3
# => false

[ip1, ip2, ip3].sort.map { |i| i.to_string }
# => ["2001:db8:1::1/64","2001:db8:1::1/65","2001:db8:2::1/64"]

[View source]
def [](index) #

Returns the 16-bits value specified by index

ip = Subnet::IPv6.new("2001:db8::8:800:200c:417a/64")

ip[0]
# => 8193
ip[1]
# => 3512
ip[2]
# => 0
ip[3]
# => 0

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def []=(index, value) #

Updated the octet specified at index


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def address : String #

Returns the IPv6 address in uncompressed form:

ip6 = Subnet.parse "2001:db8::8:800:200c:417a/64"

ip6.address
# => "2001:0db8:0000:0000:0008:0800:200c:417a"

[View source]
def allocate(skip = 0) #

Allocates a new ip from the current subnet. Optional skip parameter can be used to skip addresses.

Will raise StopIteration exception when all addresses have been allocated

Example:

ip = Subnet::IPv6.new("10.0.0.0/24")
ip.allocate
# => "10.0.0.1/24"
ip.allocate
# => "10.0.0.2/24"
ip.allocate(2)
# => "10.0.0.5/24"

Uses an internal @allocator which tracks the state of allocated addresses.


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def arpa #

ditto


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def bits #

Returns the address portion of an IP in binary format, as a string containing a sequence of 0 and 1

ip6 = Subnet::IPv6.new("2001:db8::8:800:200c:417a")

ip6.bits
# => "0010000000000001000011011011100000 [...] "

[View source]
def broadcast_u128 #

Returns the broadcast address in Unsigned 128bits format

ip6 = Subnet.parse "2001:db8::8:800:200c:417a/64"

ip6.broadcast_u128
# => 42540766411282592875350729025363378175

Please note that there is no Broadcast concept in IPv6 addresses as in IPv4 addresses, and this method is just an helper to other functions.


[View source]
def compressed : String #

Compressed form of the IPv6 address

ip6 = Subnet.parse "2001:db8::8:800:200c:417a/64"

ip6.compressed
# => "2001:db8::8:800:200c:417a"

[View source]
def data #

Returns the address portion of an IPv6 object in a network byte order format.

ip6 = Subnet.parse "2001:db8::8:800:200c:417a/64"

ip6.data
# => " \001\r\270\000\000\000\000\000\b\b\000 \fAz"

It is usually used to include an IP address in a data packet to be sent over a socket


[View source]
def each(&) #

Iterates over all the IP addresses for the given network (or IP address).

The object yielded is a new IPv6 object created from the iteration.

ip6 = Subnet::IPv6.new("2001:db8::4/125")

ip6.each do |i|
  p i.compressed
end
# => "2001:db8::"
# => "2001:db8::1"
# => "2001:db8::2"
# => "2001:db8::3"
# => "2001:db8::4"
# => "2001:db8::5"
# => "2001:db8::6"
# => "2001:db8::7"

WARNING if the host portion is very large, this method can be very slow and possibly hang your system!


[View source]
def group(index) #

ditto


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def groups : Array(Int32) #

Returns an array with the 16 bits groups in decimal format:

ip6 = Subnet.parse "2001:db8::8:800:200c:417a/64"

ip6.groups
# => [8193, 3512, 0, 0, 8, 2048, 8204, 16762]

[View source]
def hex_groups #

Returns an array of the 16 bits groups in hexdecimal format:

ip6 = Subnet.parse "2001:db8::8:800:200c:417a/64"

ip6.hex_groups
# => ["2001", "0db8", "0000", "0000", "0008", "0800", "200c", "417a"]

Not to be confused with the similar IPv6#hexstring method.


[View source]
def hexstring #

Returns a Base16 number representing the IPv6 address

ip6 = Subnet.parse "2001:db8::8:800:200c:417a/64"

ip6.hexstring
# => "20010db80000000000080800200c417a"

[View source]
def includes?(oth) #

Checks whether a subnet includes the given IP address.

Example:

ip6 = Subnet.parse "2001:db8::8:800:200c:417a/64"
addr = Subnet.parse "2001:db8::8:800:200c:1/128"

ip6.includes? addr
# => true

ip6.includes? Subnet::IPv6.new("2001:db8:1::8:800:200c:417a/76")
# => false

[View source]
def link_local? #

Checks if an IPv6 address objects belongs to a link-local network RFC4291

Example:

ip = Subnet.parse "fe80::1"
ip.link_local?
# => true

[View source]
def literal #

Literal version of the IPv6 address

ip6 = Subnet.parse "2001:db8::8:800:200c:417a/64"

ip6.literal
# => "2001-0db8-0000-0000-0008-0800-200c-417a.ipv6-literal.net"

[View source]
def loopback? #

Returns true if the address is a loopback address

See Subnet::IPv6::Loopback for more information


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def mapped? #

Returns true if the address is a mapped address

See Subnet::IPv6::Mapped for more information


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def network #

Returns a new IPv6 object with the network number for the given IP.

ip = Subnet.parse "2001:db8:1:1:1:1:1:1/32"

ip.network.to_string
# => "2001:db8::/32"

[View source]
def network? #

True if the IPv6 address is a network

ip6 = Subnet.parse "2001:db8::8:800:200c:417a/64"

ip6.network?
# => false

ip6 = Subnet.parse "2001:db8:8:800::/64"

ip6.network?
# => true

[View source]
def network_u128 #

Returns the network number in Unsigned 128bits format

ip6 = Subnet.parse "2001:db8::8:800:200c:417a/64"

ip6.network_u128
# => 42540766411282592856903984951653826560

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def pred #

Returns the predecessor to the IP address

Example:

ip = Subnet.parse("192.168.45.23/16")

ip.pred.to_string
=> "192.168.45.22/16"

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def prefix : Prefix128 #

Returns an instance of the prefix object

ip6 = Subnet.parse "2001:db8::8:800:200c:417a/64"

ip6.prefix
# => 64

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def prefix=(num) #

Set a new prefix number for the object

This is useful if you want to change the prefix to an object created with IPv6::parse_u128 or if the object was created using the default prefix of 128 bits.

ip6 = Subnet::IPv6.new("2001:db8::8:800:200c:417a")

puts ip6.to_string
# => "2001:db8::8:800:200c:417a/128"

ip6.prefix = 64
puts ip6.to_string
# => "2001:db8::8:800:200c:417a/64"

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def reverse #

Returns the IPv6 address in a DNS reverse lookup string, as per RFC3172 and RFC2874.

ip6 = Subnet.parse "3ffe:505:2::f"

ip6.reverse
# => "f.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.2.0.0.0.5.0.5.0.e.f.f.3.ip6.arpa"

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def size #

Returns the number of IP addresses included in the network. It also counts the network address and the broadcast address.

ip6 = Subnet::IPv6.new("2001:db8::8:800:200c:417a/64")

ip6.size
# => 18446744073709551616

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def succ #

Returns the successor to the IP address

Example:

ip = Subnet.parse("192.168.45.23/16")

ip.succ.to_string
=> "192.168.45.24/16"

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def to_big_i #

Return the address as a BigInt


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def to_i #

Returns a the address in as a BigInt (will return a UInt128 once support for that is finished in the stdlib)

ip6 = Subnet.parse "2001:db8::8:800:200c:417a/64"

ip6.to_i
# => 42540766411282592856906245548098208122

[View source]
def to_json(json : JSON::Builder) #

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def to_s : String #

Returns the IPv6 address in a human readable form, using the compressed address.

ip6 = Subnet.parse "2001:db8::8:800:200c:417a/64"

ip6.to_s
# => "2001:db8::8:800:200c:417a"

[View source]
def to_string #

Returns the IPv6 address in a human readable form, using the compressed address.

ip6 = Subnet.parse "2001:0db8:0000:0000:0008:0800:200c:417a/64"

ip6.to_string
# => "2001:db8::8:800:200c:417a/64"

[View source]
def to_string_uncompressed #

Unlike its counterpart IPv6#to_string method, IPv6#to_string_uncompressed returns the whole IPv6 address and prefix in an uncompressed form

ip6 = Subnet.parse "2001:db8::8:800:200c:417a/64"

ip6.to_string_uncompressed
# => "2001:0db8:0000:0000:0008:0800:200c:417a/64"

[View source]
def to_u128 #

ditto


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def unique_local? #

Checks if an IPv6 address objects belongs to a unique-local network RFC4193

Example:

ip = Subnet.parse "fc00::1"
ip.unique_local?
# => true

[View source]
def unspecified? #

Returns true if the address is an unspecified address

See Subnet::IPv6::Unspecified for more information


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