algorithm.hpp

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#pragma once
 
/// @file userver/crypto/algorithm.hpp
/// @brief @copybrief crypto::algorithm
/// @ingroup userver_universal
 
#include <string_view>
 
USERVER_NAMESPACE_BEGIN
 
/// Miscellaneous cryptographic routines
namespace crypto::algorithm {
 
/// Performs constant-time string comparison if the strings are of equal size
///
/// @snippet storages/secdist/secdist_test.cpp UserPasswords
bool AreStringsEqualConstTime(std::string_view str1, std::string_view str2) noexcept;
 
/// Performs constant-time string comparison comparator
struct StringsEqualConstTimeComparator {
    bool operator()(std::string_view x, std::string_view y) const noexcept {
        return algorithm::AreStringsEqualConstTime(x, y);
    }
 
    /// Overload for utils::StrongTypedef that hold string like objects
    template <typename T>
    auto operator()(const T& x, const T& y) const noexcept
        -> decltype(algorithm::AreStringsEqualConstTime(x.GetUnderlying(), y.GetUnderlying())) {
        static_assert(
            noexcept(algorithm::AreStringsEqualConstTime(x.GetUnderlying(), y.GetUnderlying())),
            "The comparator should not throw as this affects efficiency "
            "on some platforms"
        );
 
        return algorithm::AreStringsEqualConstTime(x.GetUnderlying(), y.GetUnderlying());
    }
};
 
}  // namespace crypto::algorithm
 
USERVER_NAMESPACE_END