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# -*- coding: us-ascii -*-
# frozen_string_literal: true
# == \Random number formatter.
#
# Formats generated random numbers in many manners. When <tt>'random/formatter'</tt>
# is required, several methods are added to empty core module <tt>Random::Formatter</tt>,
# making them available as Random's instance and module methods.
#
# Standard library SecureRandom is also extended with the module, and the methods
# described below are available as a module methods in it.
#
# === Examples
#
# Generate random hexadecimal strings:
#
# require 'random/formatter'
#
# prng = Random.new
# prng.hex(10) #=> "52750b30ffbc7de3b362"
# prng.hex(10) #=> "92b15d6c8dc4beb5f559"
# prng.hex(13) #=> "39b290146bea6ce975c37cfc23"
# # or just
# Random.hex #=> "1aed0c631e41be7f77365415541052ee"
#
# Generate random base64 strings:
#
# prng.base64(10) #=> "EcmTPZwWRAozdA=="
# prng.base64(10) #=> "KO1nIU+p9DKxGg=="
# prng.base64(12) #=> "7kJSM/MzBJI+75j8"
# Random.base64(4) #=> "bsQ3fQ=="
#
# Generate random binary strings:
#
# prng.random_bytes(10) #=> "\016\t{\370g\310pbr\301"
# prng.random_bytes(10) #=> "\323U\030TO\234\357\020\a\337"
# Random.random_bytes(6) #=> "\xA1\xE6Lr\xC43"
#
# Generate alphanumeric strings:
#
# prng.alphanumeric(10) #=> "S8baxMJnPl"
# prng.alphanumeric(10) #=> "aOxAg8BAJe"
# Random.alphanumeric #=> "TmP9OsJHJLtaZYhP"
#
# Generate UUIDs:
#
# prng.uuid #=> "2d931510-d99f-494a-8c67-87feb05e1594"
# prng.uuid #=> "bad85eb9-0713-4da7-8d36-07a8e4b00eab"
# Random.uuid #=> "f14e0271-de96-45cc-8911-8910292a42cd"
#
# All methods are available in the standard library SecureRandom, too:
#
# SecureRandom.hex #=> "05b45376a30c67238eb93b16499e50cf"
module Random::Formatter
# Generate a random binary string.
#
# The argument _n_ specifies the length of the result string.
#
# If _n_ is not specified or is nil, 16 is assumed.
# It may be larger in future.
#
# The result may contain any byte: "\x00" - "\xff".
#
# require 'random/formatter'
#
# Random.random_bytes #=> "\xD8\\\xE0\xF4\r\xB2\xFC*WM\xFF\x83\x18\xF45\xB6"
# # or
# prng = Random.new
# prng.random_bytes #=> "m\xDC\xFC/\a\x00Uf\xB2\xB2P\xBD\xFF6S\x97"
def random_bytes(n=nil)
n = n ? n.to_int : 16
gen_random(n)
end
# Generate a random hexadecimal string.
#
# The argument _n_ specifies the length, in bytes, of the random number to be generated.
# The length of the resulting hexadecimal string is twice of _n_.
#
# If _n_ is not specified or is nil, 16 is assumed.
# It may be larger in the future.
#
# The result may contain 0-9 and a-f.
#
# require 'random/formatter'
#
# Random.hex #=> "eb693ec8252cd630102fd0d0fb7c3485"
# # or
# prng = Random.new
# prng.hex #=> "91dc3bfb4de5b11d029d376634589b61"
def hex(n=nil)
random_bytes(n).unpack1("H*")
end
# Generate a random base64 string.
#
# The argument _n_ specifies the length, in bytes, of the random number
# to be generated. The length of the result string is about 4/3 of _n_.
#
# If _n_ is not specified or is nil, 16 is assumed.
# It may be larger in the future.
#
# The result may contain A-Z, a-z, 0-9, "+", "/" and "=".
#
# require 'random/formatter'
#
# Random.base64 #=> "/2BuBuLf3+WfSKyQbRcc/A=="
# # or
# prng = Random.new
# prng.base64 #=> "6BbW0pxO0YENxn38HMUbcQ=="
#
# See RFC 3548 for the definition of base64.
def base64(n=nil)
[random_bytes(n)].pack("m0")
end
# Generate a random URL-safe base64 string.
#
# The argument _n_ specifies the length, in bytes, of the random number
# to be generated. The length of the result string is about 4/3 of _n_.
#
# If _n_ is not specified or is nil, 16 is assumed.
# It may be larger in the future.
#
# The boolean argument _padding_ specifies the padding.
# If it is false or nil, padding is not generated.
# Otherwise padding is generated.
# By default, padding is not generated because "=" may be used as a URL delimiter.
#
# The result may contain A-Z, a-z, 0-9, "-" and "_".
# "=" is also used if _padding_ is true.
#
# require 'random/formatter'
#
# Random.urlsafe_base64 #=> "b4GOKm4pOYU_-BOXcrUGDg"
# # or
# prng = Random.new
# prng.urlsafe_base64 #=> "UZLdOkzop70Ddx-IJR0ABg"
#
# prng.urlsafe_base64(nil, true) #=> "i0XQ-7gglIsHGV2_BNPrdQ=="
# prng.urlsafe_base64(nil, true) #=> "-M8rLhr7JEpJlqFGUMmOxg=="
#
# See RFC 3548 for the definition of URL-safe base64.
def urlsafe_base64(n=nil, padding=false)
s = [random_bytes(n)].pack("m0")
s.tr!("+/", "-_")
s.delete!("=") unless padding
s
end
# Generate a random v4 UUID (Universally Unique IDentifier).
#
# require 'random/formatter'
#
# Random.uuid #=> "2d931510-d99f-494a-8c67-87feb05e1594"
# Random.uuid #=> "bad85eb9-0713-4da7-8d36-07a8e4b00eab"
# # or
# prng = Random.new
# prng.uuid #=> "62936e70-1815-439b-bf89-8492855a7e6b"
#
# The version 4 UUID is purely random (except the version).
# It doesn't contain meaningful information such as MAC addresses, timestamps, etc.
#
# The result contains 122 random bits (15.25 random bytes).
#
# See RFC4122[https://datatracker.ietf.org/doc/html/rfc4122] for details of UUID.
#
def uuid
ary = random_bytes(16).unpack("NnnnnN")
ary[2] = (ary[2] & 0x0fff) | 0x4000
ary[3] = (ary[3] & 0x3fff) | 0x8000
"%08x-%04x-%04x-%04x-%04x%08x" % ary
end
alias uuid_v4 uuid
# Generate a random v7 UUID (Universally Unique IDentifier).
#
# require 'random/formatter'
#
# Random.uuid_v7 # => "0188d4c3-1311-7f96-85c7-242a7aa58f1e"
# Random.uuid_v7 # => "0188d4c3-16fe-744f-86af-38fa04c62bb5"
# Random.uuid_v7 # => "0188d4c3-1af8-764f-b049-c204ce0afa23"
# Random.uuid_v7 # => "0188d4c3-1e74-7085-b14f-ef6415dc6f31"
# # |<--sorted-->| |<----- random ---->|
#
# # or
# prng = Random.new
# prng.uuid_v7 # => "0188ca51-5e72-7950-a11d-def7ff977c98"
#
# The version 7 UUID starts with the least significant 48 bits of a 64 bit
# Unix timestamp (milliseconds since the epoch) and fills the remaining bits
# with random data, excluding the version and variant bits.
#
# This allows version 7 UUIDs to be sorted by creation time. Time ordered
# UUIDs can be used for better database index locality of newly inserted
# records, which may have a significant performance benefit compared to random
# data inserts.
#
# The result contains 74 random bits (9.25 random bytes).
#
# Note that this method cannot be made reproducable because its output
# includes not only random bits but also timestamp.
#
# See draft-ietf-uuidrev-rfc4122bis[https://datatracker.ietf.org/doc/draft-ietf-uuidrev-rfc4122bis/]
# for details of UUIDv7.
#
# ==== Monotonicity
#
# UUIDv7 has millisecond precision by default, so multiple UUIDs created
# within the same millisecond are not issued in monotonically increasing
# order. To create UUIDs that are time-ordered with sub-millisecond
# precision, up to 12 bits of additional timestamp may added with
# +extra_timestamp_bits+. The extra timestamp precision comes at the expense
# of random bits. Setting <tt>extra_timestamp_bits: 12</tt> provides ~244ns
# of precision, but only 62 random bits (7.75 random bytes).
#
# prng = Random.new
# Array.new(4) { prng.uuid_v7(extra_timestamp_bits: 12) }
# # =>
# ["0188d4c7-13da-74f9-8b53-22a786ffdd5a",
# "0188d4c7-13da-753b-83a5-7fb9b2afaeea",
# "0188d4c7-13da-754a-88ea-ac0baeedd8db",
# "0188d4c7-13da-7557-83e1-7cad9cda0d8d"]
# # |<--- sorted --->| |<-- random --->|
#
# Array.new(4) { prng.uuid_v7(extra_timestamp_bits: 8) }
# # =>
# ["0188d4c7-3333-7a95-850a-de6edb858f7e",
# "0188d4c7-3333-7ae8-842e-bc3a8b7d0cf9", # <- out of order
# "0188d4c7-3333-7ae2-995a-9f135dc44ead", # <- out of order
# "0188d4c7-3333-7af9-87c3-8f612edac82e"]
# # |<--- sorted -->||<---- random --->|
#
# Any rollbacks of the system clock will break monotonicity. UUIDv7 is based
# on UTC, which excludes leap seconds and can rollback the clock. To avoid
# this, the system clock can synchronize with an NTP server configured to use
# a "leap smear" approach. NTP or PTP will also be needed to synchronize
# across distributed nodes.
#
# Counters and other mechanisms for stronger guarantees of monotonicity are
# not implemented. Applications with stricter requirements should follow
# {Section 6.2}[https://www.ietf.org/archive/id/draft-ietf-uuidrev-rfc4122bis-07.html#monotonicity_counters]
# of the specification.
#
def uuid_v7(extra_timestamp_bits: 0)
case (extra_timestamp_bits = Integer(extra_timestamp_bits))
when 0 # min timestamp precision
ms = Process.clock_gettime(Process::CLOCK_REALTIME, :millisecond)
rand = random_bytes(10)
rand.setbyte(0, rand.getbyte(0) & 0x0f | 0x70) # version
rand.setbyte(2, rand.getbyte(2) & 0x3f | 0x80) # variant
"%08x-%04x-%s" % [
(ms & 0x0000_ffff_ffff_0000) >> 16,
(ms & 0x0000_0000_0000_ffff),
rand.unpack("H4H4H12").join("-")
]
when 12 # max timestamp precision
ms, ns = Process.clock_gettime(Process::CLOCK_REALTIME, :nanosecond)
.divmod(1_000_000)
extra_bits = ns * 4096 / 1_000_000
rand = random_bytes(8)
rand.setbyte(0, rand.getbyte(0) & 0x3f | 0x80) # variant
"%08x-%04x-7%03x-%s" % [
(ms & 0x0000_ffff_ffff_0000) >> 16,
(ms & 0x0000_0000_0000_ffff),
extra_bits,
rand.unpack("H4H12").join("-")
]
when (0..12) # the generic version is slower than the special cases above
rand_a, rand_b1, rand_b2, rand_b3 = random_bytes(10).unpack("nnnN")
rand_mask_bits = 12 - extra_timestamp_bits
ms, ns = Process.clock_gettime(Process::CLOCK_REALTIME, :nanosecond)
.divmod(1_000_000)
"%08x-%04x-%04x-%04x-%04x%08x" % [
(ms & 0x0000_ffff_ffff_0000) >> 16,
(ms & 0x0000_0000_0000_ffff),
0x7000 |
((ns * (1 << extra_timestamp_bits) / 1_000_000) << rand_mask_bits) |
rand_a & ((1 << rand_mask_bits) - 1),
0x8000 | (rand_b1 & 0x3fff),
rand_b2,
rand_b3
]
else
raise ArgumentError, "extra_timestamp_bits must be in 0..12"
end
end
# Internal interface to Random; Generate random data _n_ bytes.
private def gen_random(n)
self.bytes(n)
end
# Generate a string that randomly draws from a
# source array of characters.
#
# The argument _source_ specifies the array of characters from which
# to generate the string.
# The argument _n_ specifies the length, in characters, of the string to be
# generated.
#
# The result may contain whatever characters are in the source array.
#
# require 'random/formatter'
#
# prng.choose([*'l'..'r'], 16) #=> "lmrqpoonmmlqlron"
# prng.choose([*'0'..'9'], 5) #=> "27309"
private def choose(source, n)
size = source.size
m = 1
limit = size
while limit * size <= 0x100000000
limit *= size
m += 1
end
result = ''.dup
while m <= n
rs = random_number(limit)
is = rs.digits(size)
(m-is.length).times { is << 0 }
result << source.values_at(*is).join('')
n -= m
end
if 0 < n
rs = random_number(limit)
is = rs.digits(size)
if is.length < n
(n-is.length).times { is << 0 }
else
is.pop while n < is.length
end
result.concat source.values_at(*is).join('')
end
result
end
# The default character list for #alphanumeric.
ALPHANUMERIC = [*'A'..'Z', *'a'..'z', *'0'..'9']
# Generate a random alphanumeric string.
#
# The argument _n_ specifies the length, in characters, of the alphanumeric
# string to be generated.
# The argument _chars_ specifies the character list which the result is
# consist of.
#
# If _n_ is not specified or is nil, 16 is assumed.
# It may be larger in the future.
#
# The result may contain A-Z, a-z and 0-9, unless _chars_ is specified.
#
# require 'random/formatter'
#
# Random.alphanumeric #=> "2BuBuLf3WfSKyQbR"
# # or
# prng = Random.new
# prng.alphanumeric(10) #=> "i6K93NdqiH"
#
# Random.alphanumeric(4, chars: [*"0".."9"]) #=> "2952"
# # or
# prng = Random.new
# prng.alphanumeric(10, chars: [*"!".."/"]) #=> ",.,++%/''."
def alphanumeric(n = nil, chars: ALPHANUMERIC)
n = 16 if n.nil?
choose(chars, n)
end
end