mirror of
https://github.com/matrix-construct/construct
synced 2024-08-16 22:54:41 +02:00
177 lines
4.6 KiB
C++
177 lines
4.6 KiB
C++
// Matrix Construct
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//
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// Copyright (C) Matrix Construct Developers, Authors & Contributors
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// Copyright (C) 2016-2018 Jason Volk <jason@zemos.net>
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//
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// Permission to use, copy, modify, and/or distribute this software for any
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// purpose with or without fee is hereby granted, provided that the above
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// copyright notice and this permission notice is present in all copies. The
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// full license for this software is available in the LICENSE file.
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#pragma once
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#define HAVE_IRCD_HASH_H
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namespace ircd
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{
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// constexpr bernstein string hasher suite; these functions will hash the
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// string at compile time leaving an integer residue at runtime. Decent
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// primes are at least 7681 and 5381.
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template<size_t PRIME = 7681> constexpr size_t hash(const char *const &str, const size_t i = 0);
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template<size_t PRIME = 7681> constexpr size_t hash(const char16_t *const &str, const size_t i = 0);
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template<size_t PRIME = 7681> constexpr size_t hash(const std::string_view &str, const size_t i = 0);
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// Note that at runtime this hash uses multiplication on every character
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// which can consume many cycles...
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template<size_t PRIME = 7681> size_t hash(const std::string &str, const size_t i = 0);
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template<size_t PRIME = 7681> size_t hash(const std::u16string &str, const size_t i = 0);
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}
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/// Collision-Resistant Hashing
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///
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/// ircd::crh contains support for collision-resistant hash functions including
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/// cryptographic hash functions.
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namespace ircd::crh
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{
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IRCD_EXCEPTION(ircd::error, error)
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struct hash;
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struct sha256;
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}
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// Export aliases down to ircd::
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namespace ircd
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{
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using crh::hash;
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using crh::sha256;
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}
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/// Abstract interface to a hashing context for any algorithm in ircd::crh
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///
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/// Use this type when dealing with algorithm-agnostic hashing.
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struct ircd::crh::hash
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{
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/// Returns the byte length of the mutable_buffer for digests
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virtual size_t length() const = 0;
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/// Samples the digest at the current state (without modifying)
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virtual void digest(const mutable_buffer &) const = 0;
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/// Samples the digest and modifies the state (depending on impl)
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virtual void finalize(const mutable_buffer &b)
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{
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digest(b);
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}
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/// Appends to the message
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virtual void update(const const_buffer &) = 0;
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// conveniences for output
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template<size_t SIZE> fixed_const_buffer<SIZE> digest() const;
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template<size_t SIZE> operator fixed_const_buffer<SIZE>() const;
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// conveniences for input
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void operator()(const mutable_buffer &out, const const_buffer &in);
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hash &operator+=(const const_buffer &);
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virtual ~hash() noexcept;
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};
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/// SHA-256 hashing device.
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struct ircd::crh::sha256
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final
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:hash
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{
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struct ctx;
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static constexpr const size_t digest_size
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{
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256 / 8
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};
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using buf = fixed_const_buffer<digest_size>;
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protected:
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std::unique_ptr<ctx> ctx;
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public:
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size_t length() const override;
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void digest(const mutable_buffer &) const override;
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void finalize(const mutable_buffer &) override;
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void update(const const_buffer &) override;
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sha256(const mutable_buffer &, const const_buffer &);
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sha256(const const_buffer &);
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sha256();
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~sha256() noexcept;
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};
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/// Automatic gratification from hash::digest()
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template<size_t SIZE>
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ircd::crh::hash::operator
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fixed_const_buffer<SIZE>()
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const
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{
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return digest<SIZE>();
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}
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/// Digests the hash into the buffer of the specified SIZE and returns it
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template<size_t SIZE>
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ircd::fixed_const_buffer<SIZE>
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ircd::crh::hash::digest()
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const
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{
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assert(SIZE >= length());
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return fixed_const_buffer<SIZE>
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{
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[this](const auto &buffer)
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{
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this->digest(buffer);
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}
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};
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}
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/// Runtime hashing of a std::u16string (for js). Non-cryptographic.
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template<size_t PRIME>
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size_t
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ircd::hash(const std::u16string &str,
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const size_t i)
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{
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return i >= str.size()? PRIME : (hash(str, i+1) * 33ULL) ^ str.at(i);
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}
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/// Runtime hashing of a std::string. Non-cryptographic.
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template<size_t PRIME>
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size_t
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ircd::hash(const std::string &str,
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const size_t i)
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{
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return i >= str.size()? PRIME : (hash(str, i+1) * 33ULL) ^ str.at(i);
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}
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/// Runtime hashing of a string_view. Non-cryptographic.
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template<size_t PRIME>
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constexpr size_t
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ircd::hash(const std::string_view &str,
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const size_t i)
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{
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return i >= str.size()? PRIME : (hash(str, i+1) * 33ULL) ^ str.at(i);
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}
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/// Compile-time hashing of a wider string literal (for js). Non-cryptographic.
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template<size_t PRIME>
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constexpr size_t
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ircd::hash(const char16_t *const &str,
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const size_t i)
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{
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return !str[i]? PRIME : (hash(str, i+1) * 33ULL) ^ str[i];
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}
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/// Compile-time hashing of a string literal. Non-cryptographic.
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template<size_t PRIME>
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constexpr size_t
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ircd::hash(const char *const &str,
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const size_t i)
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{
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return !str[i]? PRIME : (hash(str, i+1) * 33ULL) ^ str[i];
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}
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