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// file : libbutl/sha256.cxx -*- C++ -*-
// license : MIT; see accompanying LICENSE file
#ifndef __cpp_modules_ts
#include <libbutl/sha256.mxx>
#endif
// C interface for sha256c.
//
#include <stdint.h>
#include <stddef.h> // size_t
struct SHA256_CTX
{
uint32_t state[8];
uint64_t count;
uint8_t buf[64];
};
extern "C"
{
static void SHA256_Init (SHA256_CTX*);
static void SHA256_Update (SHA256_CTX*, const void*, size_t);
static void SHA256_Final (uint8_t[32], SHA256_CTX*);
#include "sha256c.c"
}
#include <cassert>
#ifndef __cpp_lib_modules_ts
#include <string>
#include <cstddef>
#include <cstdint>
#include <cctype> // isxdigit()
#include <istream>
#include <stdexcept> // invalid_argument
#endif
// Other includes.
#ifdef __cpp_modules_ts
module butl.sha256;
// Only imports additional to interface.
#ifdef __cpp_lib_modules_ts
import std.io;
#endif
#ifdef __clang__
#ifdef __cpp_lib_modules_ts
import std.core;
#endif
#endif
import butl.utility; // *case()
#else
#include <libbutl/utility.mxx>
#include <libbutl/bufstreambuf.hxx>
#endif
using namespace std;
namespace butl
{
void sha256::
reset ()
{
SHA256_Init (reinterpret_cast<SHA256_CTX*> (buf_));
done_ = false;
empty_ = true;
}
void sha256::
append (const void* b, size_t n)
{
if (n != 0)
{
SHA256_Update (reinterpret_cast<SHA256_CTX*> (buf_), b, n);
if (empty_)
empty_ = false;
}
}
void sha256::
append (istream& is)
{
bufstreambuf* buf (dynamic_cast<bufstreambuf*> (is.rdbuf ()));
assert (buf != nullptr);
while (is.peek () != istream::traits_type::eof () && is.good ())
{
size_t n (buf->egptr () - buf->gptr ());
append (buf->gptr (), n);
buf->gbump (static_cast<int> (n));
}
}
const sha256::digest_type& sha256::
binary () const
{
if (!done_)
{
SHA256_Final (bin_, reinterpret_cast<SHA256_CTX*> (buf_));
done_ = true;
buf_[0] = '\0'; // Indicate we haven't computed the string yet.
}
return bin_;
}
static const char hex_map[16] = {
'0', '1', '2', '3', '4', '5', '6', '7', '8', '9',
'a', 'b', 'c', 'd', 'e', 'f'};
const char* sha256::
string () const
{
if (!done_)
binary ();
if (buf_[0] == '\0')
{
for (size_t i (0); i != 32; ++i)
{
buf_[i * 2] = hex_map[bin_[i] >> 4];
buf_[i * 2 + 1] = hex_map[bin_[i] & 0x0f];
}
buf_[64] = '\0';
}
return buf_;
}
string
sha256_to_fingerprint (const string& s)
{
auto bad = []() {throw invalid_argument ("invalid SHA256 string");};
size_t n (s.size ());
if (n != 64)
bad ();
string f;
f.reserve (n + 31);
for (size_t i (0); i != n; ++i)
{
char c (s[i]);
if (!isxdigit (c))
bad ();
if (i > 0 && i % 2 == 0)
f += ":";
f += ucase (c);
}
return f;
}
string
fingerprint_to_sha256 (const string& f, size_t rn)
{
auto bad = []() {throw invalid_argument ("invalid fingerprint");};
size_t n (f.size ());
if (n != 32 * 3 - 1)
bad ();
if (rn > 64)
rn = 64;
string s;
s.reserve (rn);
// Note that we continue to validate the fingerprint after the result is
// ready.
//
for (size_t i (0); i != n; ++i)
{
char c (f[i]);
if ((i + 1) % 3 == 0)
{
if (c != ':')
bad ();
}
else
{
if (!isxdigit (c))
bad ();
if (s.size () != rn)
s += lcase (c);
}
}
return s;
}
}
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