diff options
Diffstat (limited to 'src/util')
-rw-r--r-- | src/util/golombrice.h | 31 | ||||
-rw-r--r-- | src/util/overflow.h | 31 | ||||
-rw-r--r-- | src/util/sock.cpp | 27 | ||||
-rw-r--r-- | src/util/sock.h | 9 |
4 files changed, 98 insertions, 0 deletions
diff --git a/src/util/golombrice.h b/src/util/golombrice.h index 67d262406f..f14cb594db 100644 --- a/src/util/golombrice.h +++ b/src/util/golombrice.h @@ -40,4 +40,35 @@ uint64_t GolombRiceDecode(BitStreamReader<IStream>& bitreader, uint8_t P) return (q << P) + r; } +// Map a value x that is uniformly distributed in the range [0, 2^64) to a +// value uniformly distributed in [0, n) by returning the upper 64 bits of +// x * n. +// +// See: https://lemire.me/blog/2016/06/27/a-fast-alternative-to-the-modulo-reduction/ +static inline uint64_t MapIntoRange(uint64_t x, uint64_t n) +{ +#ifdef __SIZEOF_INT128__ + return (static_cast<unsigned __int128>(x) * static_cast<unsigned __int128>(n)) >> 64; +#else + // To perform the calculation on 64-bit numbers without losing the + // result to overflow, split the numbers into the most significant and + // least significant 32 bits and perform multiplication piece-wise. + // + // See: https://stackoverflow.com/a/26855440 + const uint64_t x_hi = x >> 32; + const uint64_t x_lo = x & 0xFFFFFFFF; + const uint64_t n_hi = n >> 32; + const uint64_t n_lo = n & 0xFFFFFFFF; + + const uint64_t ac = x_hi * n_hi; + const uint64_t ad = x_hi * n_lo; + const uint64_t bc = x_lo * n_hi; + const uint64_t bd = x_lo * n_lo; + + const uint64_t mid34 = (bd >> 32) + (bc & 0xFFFFFFFF) + (ad & 0xFFFFFFFF); + const uint64_t upper64 = ac + (bc >> 32) + (ad >> 32) + (mid34 >> 32); + return upper64; +#endif +} + #endif // BITCOIN_UTIL_GOLOMBRICE_H diff --git a/src/util/overflow.h b/src/util/overflow.h new file mode 100644 index 0000000000..5982af8d04 --- /dev/null +++ b/src/util/overflow.h @@ -0,0 +1,31 @@ +// Copyright (c) 2021 The Bitcoin Core developers +// Distributed under the MIT software license, see the accompanying +// file COPYING or http://www.opensource.org/licenses/mit-license.php. + +#ifndef BITCOIN_UTIL_OVERFLOW_H +#define BITCOIN_UTIL_OVERFLOW_H + +#include <limits> +#include <type_traits> + +template <class T> +[[nodiscard]] bool AdditionOverflow(const T i, const T j) noexcept +{ + static_assert(std::is_integral<T>::value, "Integral required."); + if (std::numeric_limits<T>::is_signed) { + return (i > 0 && j > std::numeric_limits<T>::max() - i) || + (i < 0 && j < std::numeric_limits<T>::min() - i); + } + return std::numeric_limits<T>::max() - i < j; +} + +template <class T> +[[nodiscard]] std::optional<T> CheckedAdd(const T i, const T j) noexcept +{ + if (AdditionOverflow(i, j)) { + return std::nullopt; + } + return i + j; +} + +#endif // BITCOIN_UTIL_OVERFLOW_H diff --git a/src/util/sock.cpp b/src/util/sock.cpp index 1a4d67a65e..2029d70a37 100644 --- a/src/util/sock.cpp +++ b/src/util/sock.cpp @@ -10,6 +10,7 @@ #include <util/system.h> #include <util/time.h> +#include <memory> #include <stdexcept> #include <string> @@ -73,6 +74,32 @@ int Sock::Connect(const sockaddr* addr, socklen_t addr_len) const return connect(m_socket, addr, addr_len); } +std::unique_ptr<Sock> Sock::Accept(sockaddr* addr, socklen_t* addr_len) const +{ +#ifdef WIN32 + static constexpr auto ERR = INVALID_SOCKET; +#else + static constexpr auto ERR = SOCKET_ERROR; +#endif + + std::unique_ptr<Sock> sock; + + const auto socket = accept(m_socket, addr, addr_len); + if (socket != ERR) { + try { + sock = std::make_unique<Sock>(socket); + } catch (const std::exception&) { +#ifdef WIN32 + closesocket(socket); +#else + close(socket); +#endif + } + } + + return sock; +} + int Sock::GetSockOpt(int level, int opt_name, void* opt_val, socklen_t* opt_len) const { return getsockopt(m_socket, level, opt_name, static_cast<char*>(opt_val), opt_len); diff --git a/src/util/sock.h b/src/util/sock.h index 59cc8c0b1d..7510482857 100644 --- a/src/util/sock.h +++ b/src/util/sock.h @@ -10,6 +10,7 @@ #include <util/time.h> #include <chrono> +#include <memory> #include <string> /** @@ -97,6 +98,14 @@ public: [[nodiscard]] virtual int Connect(const sockaddr* addr, socklen_t addr_len) const; /** + * accept(2) wrapper. Equivalent to `std::make_unique<Sock>(accept(this->Get(), addr, addr_len))`. + * Code that uses this wrapper can be unit tested if this method is overridden by a mock Sock + * implementation. + * The returned unique_ptr is empty if `accept()` failed in which case errno will be set. + */ + [[nodiscard]] virtual std::unique_ptr<Sock> Accept(sockaddr* addr, socklen_t* addr_len) const; + + /** * getsockopt(2) wrapper. Equivalent to * `getsockopt(this->Get(), level, opt_name, opt_val, opt_len)`. Code that uses this * wrapper can be unit tested if this method is overridden by a mock Sock implementation. |