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Field digest is endian-independent:

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fix #1863
close #1864

* Added some comments
* Add 64-bit specific calculation
* Fix endian-dependence in digest
This commit is contained in:
Vinnie Falco
2020-02-28 08:30:04 -08:00
parent 2c2e2c0812
commit f5273300f9
2 changed files with 31 additions and 10 deletions
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1
CHANGELOG.md
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@ -7,6 +7,7 @@ Version 286:
* Refactor flat_static_buffer
* Fix missing include in sha1.hpp
* Fix ostream warning
* Field digest is endian-independent
API Changes:

40
include/boost/beast/http/impl/field.ipp
View File

@ -24,6 +24,22 @@ namespace detail {
struct field_table
{
static
std::uint32_t
get_chars(
unsigned char const* p) noexcept
{
// VFALCO memcpy is endian-dependent
//std::memcpy(&v, p, 4);
// Compiler should be smart enough to
// optimize this down to one instruction.
return
p[0] |
(p[1] << 8) |
(p[2] << 16) |
(p[3] << 24);
}
using array_type =
std::array<string_view, 353>;
@ -34,16 +50,19 @@ struct field_table
{
std::uint32_t r = 0;
std::size_t n = s.size();
unsigned char const* p =reinterpret_cast<
auto p = reinterpret_cast<
unsigned char const*>(s.data());
// consume N characters at a time
// VFALCO Can we do 8 on 64-bit systems?
while(n >= 4)
{
std::uint32_t v;
std::memcpy(&v, p, 4);
r = r * 5 + ( v | 0x20202020 );
auto const v = get_chars(p);
r = (r * 5 + (
v | 0x20202020 )); // convert to lower
p += 4;
n -= 4;
}
// handle remaining characters
while( n > 0 )
{
r = r * 5 + ( *p | 0x20 );
@ -59,20 +78,21 @@ struct field_table
bool
equals(string_view lhs, string_view rhs)
{
using Int = std::uint32_t; // or std::size_t
using Int = std::uint32_t; // VFALCO std::size_t?
auto n = lhs.size();
if(n != rhs.size())
return false;
auto p1 = lhs.data();
auto p2 = rhs.data();
auto p1 = reinterpret_cast<
unsigned char const*>(lhs.data());
auto p2 = reinterpret_cast<
unsigned char const*>(rhs.data());
auto constexpr S = sizeof(Int);
auto constexpr Mask = static_cast<Int>(
0xDFDFDFDFDFDFDFDF & ~Int{0});
for(; n >= S; p1 += S, p2 += S, n -= S)
{
Int v1, v2;
std::memcpy( &v1, p1, S );
std::memcpy( &v2, p2, S );
Int const v1 = get_chars(p1);
Int const v2 = get_chars(p2);
if((v1 ^ v2) & Mask)
return false;
}