ClickHouse/src/Common/IPv6ToBinary.cpp
Robert Schulze a7734672b9
Use std::popcount, ::countl_zero, ::countr_zero functions
- Introduced with the C++20 <bit> header

- The problem with __builtin_c(l|t)z() is that 0 as input has an
  undefined result (*) and the code did not always check. The std::
  versions do not have this issue.

- In some cases, we continue to use buildin_c(l|t)z(), (e.g. in
  src/Common/BitHelpers.h) because the std:: versions only accept
  unsigned inputs (and they also check that) and the casting would be
  ugly.

(*) https://gcc.gnu.org/onlinedocs/gcc/Other-Builtins.html
2022-07-31 15:16:51 +00:00

127 lines
3.2 KiB
C++

#include "IPv6ToBinary.h"
#include <Poco/Net/IPAddress.h>
#include <Poco/ByteOrder.h>
#include <Common/formatIPv6.h>
#include <cstring>
#include <bit>
namespace DB
{
/// Result array could be indexed with all possible uint8 values without extra check.
/// For values greater than 128 we will store same value as for 128 (all bits set).
constexpr size_t IPV6_MASKS_COUNT = 256;
using RawMaskArrayV6 = std::array<uint8_t, IPV6_BINARY_LENGTH>;
void IPv6ToRawBinary(const Poco::Net::IPAddress & address, char * res)
{
if (Poco::Net::IPAddress::IPv6 == address.family())
{
memcpy(res, address.addr(), 16);
}
else if (Poco::Net::IPAddress::IPv4 == address.family())
{
/// Convert to IPv6-mapped address.
memset(res, 0, 10);
res[10] = '\xFF';
res[11] = '\xFF';
memcpy(&res[12], address.addr(), 4);
}
else
memset(res, 0, 16);
}
std::array<char, 16> IPv6ToBinary(const Poco::Net::IPAddress & address)
{
std::array<char, 16> res;
IPv6ToRawBinary(address, res.data());
return res;
}
template <typename RawMaskArrayT>
static constexpr RawMaskArrayT generateBitMask(size_t prefix)
{
RawMaskArrayT arr{0};
if (prefix >= arr.size() * 8)
prefix = arr.size() * 8;
size_t i = 0;
for (; prefix >= 8; ++i, prefix -= 8)
arr[i] = 0xff;
if (prefix > 0)
arr[i++] = ~(0xff >> prefix);
while (i < arr.size())
arr[i++] = 0x00;
return arr;
}
template <typename RawMaskArrayT, size_t masksCount>
static constexpr std::array<RawMaskArrayT, masksCount> generateBitMasks()
{
std::array<RawMaskArrayT, masksCount> arr{};
for (size_t i = 0; i < masksCount; ++i)
arr[i] = generateBitMask<RawMaskArrayT>(i);
return arr;
}
const std::array<uint8_t, 16> & getCIDRMaskIPv6(UInt8 prefix_len)
{
static constexpr auto IPV6_RAW_MASK_ARRAY = generateBitMasks<RawMaskArrayV6, IPV6_MASKS_COUNT>();
return IPV6_RAW_MASK_ARRAY[prefix_len];
}
bool matchIPv4Subnet(UInt32 addr, UInt32 cidr_addr, UInt8 prefix)
{
UInt32 mask = (prefix >= 32) ? 0xffffffffu : ~(0xffffffffu >> prefix);
return (addr & mask) == (cidr_addr & mask);
}
#if defined(__SSE2__)
#include <emmintrin.h>
bool matchIPv6Subnet(const uint8_t * addr, const uint8_t * cidr_addr, UInt8 prefix)
{
uint16_t mask = _mm_movemask_epi8(_mm_cmpeq_epi8(
_mm_loadu_si128(reinterpret_cast<const __m128i *>(addr)),
_mm_loadu_si128(reinterpret_cast<const __m128i *>(cidr_addr))));
mask = ~mask;
if (mask)
{
auto offset = std::countr_zero(mask);
if (prefix / 8 != offset)
return prefix / 8 < offset;
auto cmpmask = ~(0xff >> (prefix % 8));
return (addr[offset] & cmpmask) == (cidr_addr[offset] & cmpmask);
}
return true;
}
# else
bool matchIPv6Subnet(const uint8_t * addr, const uint8_t * cidr_addr, UInt8 prefix)
{
if (prefix > IPV6_BINARY_LENGTH * 8U)
prefix = IPV6_BINARY_LENGTH * 8U;
size_t i = 0;
for (; prefix >= 8; ++i, prefix -= 8)
{
if (addr[i] != cidr_addr[i])
return false;
}
if (prefix == 0)
return true;
auto mask = ~(0xff >> prefix);
return (addr[i] & mask) == (cidr_addr[i] & mask);
}
#endif // __SSE2__
}