--- /dev/null
+# -*- Mode: perl; indent-tabs-mode: nil -*-
+#
+# The contents of this file are subject to the Mozilla Public
+# License Version 1.1 (the "License"); you may not use this file
+# except in compliance with the License. You may obtain a copy of
+# the License at http://www.mozilla.org/MPL/
+#
+# Software distributed under the License is distributed on an "AS
+# IS" basis, WITHOUT WARRANTY OF ANY KIND, either express or
+# implied. See the License for the specific language governing
+# rights and limitations under the License.
+#
+# The Original Code is the Bugzilla Bug Tracking System.
+#
+# The Initial Developer of the Original Code is Google Inc.
+# Portions created by the Initial Developer are Copyright (C) 2011
+# the Initial Developer. All Rights Reserved.
+#
+# Contributor(s):
+# Max Kanat-Alexander <mkanat@bugzilla.org>
+
+package Bugzilla::RNG;
+use strict;
+use base qw(Exporter);
+use Bugzilla::Constants qw(ON_WINDOWS);
+
+use IO::File;
+use Math::Random::ISAAC;
+use if ON_WINDOWS, 'Win32::API';
+
+our $RNG;
+our @EXPORT_OK = qw(rand srand irand);
+
+# ISAAC, a 32-bit generator, should only be capable of generating numbers
+# between 0 and 2^32 - 1. We want _to_float to generate numbers possibly
+# including 0, but always less than 1.0. Dividing the integer produced
+# by irand() by this number should do that exactly.
+use constant DIVIDE_BY => 2**32;
+
+# How many bytes of seed to read.
+use constant SEED_SIZE => 16; # 128 bits.
+
+#################
+# Windows Stuff #
+#################
+
+# The type of cryptographic service provider we want to use.
+# This doesn't really matter for our purposes, so we just pick
+# PROV_RSA_FULL, which seems reasonable. For more info, see
+# http://msdn.microsoft.com/en-us/library/aa380244(v=VS.85).aspx
+use constant PROV_RSA_FULL => 1;
+
+# Flags for CryptGenRandom:
+# Don't ever display a UI to the user, just fail if one would be needed.
+use constant CRYPT_SILENT => 64;
+# Don't require existing public/private keypairs.
+use constant CRYPT_VERIFYCONTEXT => 0xF0000000;
+
+# For some reason, BOOLEAN doesn't work properly as a return type with
+# Win32::API.
+use constant RTLGENRANDOM_PROTO => <<END;
+INT SystemFunction036(
+ PVOID RandomBuffer,
+ ULONG RandomBufferLength
+)
+END
+
+#################
+# RNG Functions #
+#################
+
+sub rand (;$) {
+ my ($limit) = @_;
+ my $int = irand();
+ return _to_float($int, $limit);
+}
+
+sub irand (;$) {
+ my ($limit) = @_;
+ Bugzilla::RNG::srand() if !defined $RNG;
+ my $int = $RNG->irand();
+ if (defined $limit) {
+ # We can't just use the mod operator because it will bias
+ # our output. Search for "modulo bias" on the Internet for
+ # details. This is slower than mod(), but does not have a bias,
+ # as demonstrated by Math::Random::Secure's uniform.t test.
+ return int(_to_float($int, $limit));
+ }
+ return $int;
+}
+
+sub srand (;$) {
+ my ($value) = @_;
+ # Remove any RNG that might already have been made.
+ $RNG = undef;
+ my %args;
+ if (defined $value) {
+ $args{seed} = $value;
+ }
+ $RNG = _create_rng(\%args);
+}
+
+sub _to_float {
+ my ($integer, $limit) = @_;
+ $limit ||= 1;
+ return ($integer / DIVIDE_BY) * $limit;
+}
+
+##########################
+# Seed and PRNG Creation #
+##########################
+
+sub _create_rng {
+ my ($params) = @_;
+
+ if (!defined $params->{seed}) {
+ $params->{seed} = _get_seed();
+ }
+
+ _check_seed($params->{seed});
+
+ my @seed_ints = unpack('L*', $params->{seed});
+
+ my $rng = Math::Random::ISAAC->new(@seed_ints);
+
+ # It's faster to skip the frontend interface of Math::Random::ISAAC
+ # and just use the backend directly. However, in case the internal
+ # code of Math::Random::ISAAC changes at some point, we do make sure
+ # that the {backend} element actually exists first.
+ return $rng->{backend} ? $rng->{backend} : $rng;
+}
+
+sub _check_seed {
+ my ($seed) = @_;
+ if (length($seed) < 8) {
+ warn "Your seed is less than 8 bytes (64 bits). It could be"
+ . " easy to crack";
+ }
+ # If it looks like we were seeded with a 32-bit integer, warn the
+ # user that they are making a dangerous, easily-crackable mistake.
+ elsif (length($seed) <= 10 and $seed =~ /^\d+$/) {
+ warn "RNG seeded with a 32-bit integer, this is easy to crack";
+ }
+}
+
+sub _get_seed {
+ return _windows_seed() if ON_WINDOWS;
+
+ if (-r '/dev/urandom') {
+ return _read_seed_from('/dev/urandom');
+ }
+
+ return _read_seed_from('/dev/random');
+}
+
+sub _read_seed_from {
+ my ($from) = @_;
+
+ my $fh = IO::File->new($from, "r") or die "$from: $!";
+ my $buffer;
+ $fh->read($buffer, SEED_SIZE);
+ if (length($buffer) < SEED_SIZE) {
+ die "Could not read enough seed bytes from $from, got only "
+ . length($buffer);
+ }
+ $fh->close;
+ return $buffer;
+}
+
+sub _windows_seed {
+ my ($major, $minor) = (Win32::GetOSVersion())[1,2];
+ if ($major < 5) {
+ die "Bugzilla does not support versions of Windows before"
+ . " Windows 2000";
+ }
+ # This means Windows 2000.
+ if ($major == 5 and $minor == 0) {
+ return _win2k_seed();
+ }
+
+ my $rtlgenrand = Win32::API->new('advapi32', RTLGENRANDOM_PROTO);
+ if (!defined $rtlgenrand) {
+ die "Could not import RtlGenRand: $^E";
+ }
+ my $buffer = chr(0) x SEED_SIZE;
+ my $result = $rtlgenrand->Call($buffer, SEED_SIZE);
+ if (!$result) {
+ die "RtlGenRand failed: $^E";
+ }
+ return $buffer;
+}
+
+sub _win2k_seed {
+ my $crypt_acquire = Win32::API->new(
+ "advapi32", 'CryptAcquireContext', 'PPPNN', 'I');
+ if (!defined $crypt_acquire) {
+ die "Could not import CryptAcquireContext: $^E";
+ }
+
+ my $crypt_release = Win32::API->new(
+ "advapi32", 'CryptReleaseContext', 'NN', 'I');
+ if (!defined $crypt_release) {
+ die "Could not import CryptReleaseContext: $^E";
+ }
+
+ my $crypt_gen_random = Win32::API->new(
+ "advapi32", 'CryptGenRandom', 'NNP', 'I');
+ if (!defined $crypt_gen_random) {
+ die "Could not import CryptGenRandom: $^E";
+ }
+
+ my $context = chr(0) x Win32::API::Type->sizeof('PULONG');
+ my $acquire_result = $crypt_acquire->Call(
+ $context, 0, 0, PROV_RSA_FULL, CRYPT_SILENT | CRYPT_VERIFYCONTEXT);
+ if (!defined $acquire_result) {
+ die "CryptAcquireContext failed: $^E";
+ }
+
+ my $pack_type = Win32::API::Type::packing('PULONG');
+ $context = unpack($pack_type, $context);
+
+ my $buffer = chr(0) x SEED_SIZE;
+ my $rand_result = $crypt_gen_random->Call($context, SEED_SIZE, $buffer);
+ my $rand_error = $^E;
+ # We don't check this if it fails, we don't care.
+ $crypt_release->Call($context, 0);
+ if (!defined $rand_result) {
+ die "CryptGenRandom failed: $rand_error";
+ }
+ return $buffer;
+}
+
+1;
projects / thirdparty / bugzilla.git / commitdiff
