1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
|
// Copyright 2017 The Abseil Authors.
//
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
// https://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.
#ifndef ABSL_RANDOM_INTERNAL_NONSECURE_BASE_H_
#define ABSL_RANDOM_INTERNAL_NONSECURE_BASE_H_
#include <algorithm>
#include <cstdint>
#include <iterator>
#include <type_traits>
#include <utility>
#include <vector>
#include "absl/base/macros.h"
#include "absl/container/inlined_vector.h"
#include "absl/meta/type_traits.h"
#include "absl/random/internal/pool_urbg.h"
#include "absl/random/internal/salted_seed_seq.h"
#include "absl/random/internal/seed_material.h"
#include "absl/types/span.h"
namespace absl {
ABSL_NAMESPACE_BEGIN
namespace random_internal {
// RandenPoolSeedSeq is a custom seed sequence type where generate() fills the
// provided buffer via the RandenPool entropy source.
class RandenPoolSeedSeq {
private:
struct ContiguousTag {};
struct BufferTag {};
// Generate random unsigned values directly into the buffer.
template <typename Contiguous>
void generate_impl(ContiguousTag, Contiguous begin, Contiguous end) {
const size_t n = static_cast<size_t>(std::distance(begin, end));
auto* a = &(*begin);
RandenPool<uint8_t>::Fill(
absl::MakeSpan(reinterpret_cast<uint8_t*>(a), sizeof(*a) * n));
}
// Construct a buffer of size n and fill it with values, then copy
// those values into the seed iterators.
template <typename RandomAccessIterator>
void generate_impl(BufferTag, RandomAccessIterator begin,
RandomAccessIterator end) {
const size_t n = std::distance(begin, end);
absl::InlinedVector<uint32_t, 8> data(n, 0);
RandenPool<uint32_t>::Fill(absl::MakeSpan(data.begin(), data.end()));
std::copy(std::begin(data), std::end(data), begin);
}
public:
using result_type = uint32_t;
size_t size() { return 0; }
template <typename OutIterator>
void param(OutIterator) const {}
template <typename RandomAccessIterator>
void generate(RandomAccessIterator begin, RandomAccessIterator end) {
// RandomAccessIterator must be assignable from uint32_t
if (begin != end) {
using U = typename std::iterator_traits<RandomAccessIterator>::value_type;
// ContiguousTag indicates the common case of a known contiguous buffer,
// which allows directly filling the buffer. In C++20,
// std::contiguous_iterator_tag provides a mechanism for testing this
// capability, however until Abseil's support requirements allow us to
// assume C++20, limit checks to a few common cases.
using TagType = absl::conditional_t<
(std::is_pointer<RandomAccessIterator>::value ||
std::is_same<RandomAccessIterator,
typename std::vector<U>::iterator>::value),
ContiguousTag, BufferTag>;
generate_impl(TagType{}, begin, end);
}
}
};
// Each instance of NonsecureURBGBase<URBG> will be seeded by variates produced
// by a thread-unique URBG-instance.
template <typename URBG, typename Seeder = RandenPoolSeedSeq>
class NonsecureURBGBase {
public:
using result_type = typename URBG::result_type;
// Default constructor
NonsecureURBGBase() : urbg_(ConstructURBG()) {}
// Copy disallowed, move allowed.
NonsecureURBGBase(const NonsecureURBGBase&) = delete;
NonsecureURBGBase& operator=(const NonsecureURBGBase&) = delete;
NonsecureURBGBase(NonsecureURBGBase&&) = default;
NonsecureURBGBase& operator=(NonsecureURBGBase&&) = default;
// Constructor using a seed
template <class SSeq, typename = typename absl::enable_if_t<
!std::is_same<SSeq, NonsecureURBGBase>::value>>
explicit NonsecureURBGBase(SSeq&& seq)
: urbg_(ConstructURBG(std::forward<SSeq>(seq))) {}
// Note: on MSVC, min() or max() can be interpreted as MIN() or MAX(), so we
// enclose min() or max() in parens as (min)() and (max)().
// Additionally, clang-format requires no space before this construction.
// NonsecureURBGBase::min()
static constexpr result_type(min)() { return (URBG::min)(); }
// NonsecureURBGBase::max()
static constexpr result_type(max)() { return (URBG::max)(); }
// NonsecureURBGBase::operator()()
result_type operator()() { return urbg_(); }
// NonsecureURBGBase::discard()
void discard(unsigned long long values) { // NOLINT(runtime/int)
urbg_.discard(values);
}
bool operator==(const NonsecureURBGBase& other) const {
return urbg_ == other.urbg_;
}
bool operator!=(const NonsecureURBGBase& other) const {
return !(urbg_ == other.urbg_);
}
private:
static URBG ConstructURBG() {
Seeder seeder;
return URBG(seeder);
}
template <typename SSeq>
static URBG ConstructURBG(SSeq&& seq) { // NOLINT(runtime/references)
auto salted_seq =
random_internal::MakeSaltedSeedSeq(std::forward<SSeq>(seq));
return URBG(salted_seq);
}
URBG urbg_;
};
} // namespace random_internal
ABSL_NAMESPACE_END
} // namespace absl
#endif // ABSL_RANDOM_INTERNAL_NONSECURE_BASE_H_
|
