Safe fixed-width byte reads for cryptographic code

1// Copyright (c) 2014-present The Bitcoin Core developers
2// Distributed under the MIT software license, see the accompanying
3// file COPYING or http://www.opensource.org/licenses/mit-license.php.
4
5#ifndef BITCOIN_CRYPTO_COMMON_H
6#define BITCOIN_CRYPTO_COMMON_H
7
8#include <compat/endian.h>
9
10#include <concepts>
11#include <cstddef>
12#include <cstdint>
13#include <cstring>
14
15template <typename B>
16concept ByteType = std::same_as<B, unsigned char> || std::same_as<B, std::byte>;
17
18template <ByteType B>
19inline uint16_t ReadLE16(const B* ptr)
20{
21    uint16_t x;
22    memcpy(&x, ptr, 2);
23    return le16toh_internal(x);
24}
25
26template <ByteType B>
27inline uint32_t ReadLE32(const B* ptr)
28{
29    uint32_t x;
30    memcpy(&x, ptr, 4);
31    return le32toh_internal(x);
32}
33
34template <ByteType B>
35inline uint64_t ReadLE64(const B* ptr)
36{
37    uint64_t x;
38    memcpy(&x, ptr, 8);
39    return le64toh_internal(x);
40}
41
42template <ByteType B>
43inline void WriteLE16(B* ptr, uint16_t x)
44{
45    uint16_t v = htole16_internal(x);
46    memcpy(ptr, &v, 2);
47}
48
49template <ByteType B>
50inline void WriteLE32(B* ptr, uint32_t x)
51{
52    uint32_t v = htole32_internal(x);
53    memcpy(ptr, &v, 4);
54}
55
56template <ByteType B>
57inline void WriteLE64(B* ptr, uint64_t x)
58{
59    uint64_t v = htole64_internal(x);
60    memcpy(ptr, &v, 8);
61}
62
63template <ByteType B>
64inline uint16_t ReadBE16(const B* ptr)
65{
66    uint16_t x;
67    memcpy(&x, ptr, 2);
68    return be16toh_internal(x);
69}
70
71template <ByteType B>
72inline uint32_t ReadBE32(const B* ptr)
73{
74    uint32_t x;
75    memcpy(&x, ptr, 4);
76    return be32toh_internal(x);
77}
78
79template <ByteType B>
80inline uint64_t ReadBE64(const B* ptr)
81{
82    uint64_t x;
83    memcpy(&x, ptr, 8);
84    return be64toh_internal(x);
85}
86
87template <ByteType B>
88inline void WriteBE16(B* ptr, uint16_t x)
89{
90    uint16_t v = htobe16_internal(x);
91    memcpy(ptr, &v, 2);
92}
93
94template <ByteType B>
95inline void WriteBE32(B* ptr, uint32_t x)
96{
97    uint32_t v = htobe32_internal(x);
98    memcpy(ptr, &v, 4);
99}
100
101template <ByteType B>
102inline void WriteBE64(B* ptr, uint64_t x)
103{
104    uint64_t v = htobe64_internal(x);
105    memcpy(ptr, &v, 8);
106}
107
108#endif // BITCOIN_CRYPTO_COMMON_H
109