diff options
Diffstat (limited to 'src/uint256.h')
| -rw-r--r-- | src/uint256.h | 339 |
1 files changed, 72 insertions, 267 deletions
diff --git a/src/uint256.h b/src/uint256.h index 8189b27cb3..6d016ab164 100644 --- a/src/uint256.h +++ b/src/uint256.h @@ -13,217 +13,37 @@ #include <string> #include <vector> -class uint_error : public std::runtime_error { -public: - explicit uint_error(const std::string& str) : std::runtime_error(str) {} -}; - -/** Template base class for unsigned big integers. */ +/** Template base class for fixed-sized opaque blobs. */ template<unsigned int BITS> -class base_uint +class base_blob { protected: - enum { WIDTH=BITS/32 }; - uint32_t pn[WIDTH]; + enum { WIDTH=BITS/8 }; + uint8_t data[WIDTH]; public: - - base_uint() + base_blob() { - for (int i = 0; i < WIDTH; i++) - pn[i] = 0; + memset(data, 0, sizeof(data)); } - base_uint(const base_uint& b) - { - for (int i = 0; i < WIDTH; i++) - pn[i] = b.pn[i]; - } - - base_uint& operator=(const base_uint& b) - { - for (int i = 0; i < WIDTH; i++) - pn[i] = b.pn[i]; - return *this; - } + explicit base_blob(const std::vector<unsigned char>& vch); - base_uint(uint64_t b) - { - pn[0] = (unsigned int)b; - pn[1] = (unsigned int)(b >> 32); - for (int i = 2; i < WIDTH; i++) - pn[i] = 0; - } - - explicit base_uint(const std::string& str); - explicit base_uint(const std::vector<unsigned char>& vch); - - bool operator!() const + bool IsNull() const { for (int i = 0; i < WIDTH; i++) - if (pn[i] != 0) + if (data[i] != 0) return false; return true; } - const base_uint operator~() const - { - base_uint ret; - for (int i = 0; i < WIDTH; i++) - ret.pn[i] = ~pn[i]; - return ret; - } - - const base_uint operator-() const - { - base_uint ret; - for (int i = 0; i < WIDTH; i++) - ret.pn[i] = ~pn[i]; - ret++; - return ret; - } - - double getdouble() const; - - base_uint& operator=(uint64_t b) - { - pn[0] = (unsigned int)b; - pn[1] = (unsigned int)(b >> 32); - for (int i = 2; i < WIDTH; i++) - pn[i] = 0; - return *this; - } - - base_uint& operator^=(const base_uint& b) - { - for (int i = 0; i < WIDTH; i++) - pn[i] ^= b.pn[i]; - return *this; - } - - base_uint& operator&=(const base_uint& b) - { - for (int i = 0; i < WIDTH; i++) - pn[i] &= b.pn[i]; - return *this; - } - - base_uint& operator|=(const base_uint& b) - { - for (int i = 0; i < WIDTH; i++) - pn[i] |= b.pn[i]; - return *this; - } - - base_uint& operator^=(uint64_t b) - { - pn[0] ^= (unsigned int)b; - pn[1] ^= (unsigned int)(b >> 32); - return *this; - } - - base_uint& operator|=(uint64_t b) - { - pn[0] |= (unsigned int)b; - pn[1] |= (unsigned int)(b >> 32); - return *this; - } - - base_uint& operator<<=(unsigned int shift); - base_uint& operator>>=(unsigned int shift); - - base_uint& operator+=(const base_uint& b) - { - uint64_t carry = 0; - for (int i = 0; i < WIDTH; i++) - { - uint64_t n = carry + pn[i] + b.pn[i]; - pn[i] = n & 0xffffffff; - carry = n >> 32; - } - return *this; - } - - base_uint& operator-=(const base_uint& b) - { - *this += -b; - return *this; - } - - base_uint& operator+=(uint64_t b64) - { - base_uint b; - b = b64; - *this += b; - return *this; - } - - base_uint& operator-=(uint64_t b64) - { - base_uint b; - b = b64; - *this += -b; - return *this; - } - - base_uint& operator*=(uint32_t b32); - base_uint& operator*=(const base_uint& b); - base_uint& operator/=(const base_uint& b); - - base_uint& operator++() - { - // prefix operator - int i = 0; - while (++pn[i] == 0 && i < WIDTH-1) - i++; - return *this; - } - - const base_uint operator++(int) - { - // postfix operator - const base_uint ret = *this; - ++(*this); - return ret; - } - - base_uint& operator--() - { - // prefix operator - int i = 0; - while (--pn[i] == (uint32_t)-1 && i < WIDTH-1) - i++; - return *this; - } - - const base_uint operator--(int) + void SetNull() { - // postfix operator - const base_uint ret = *this; - --(*this); - return ret; + memset(data, 0, sizeof(data)); } - int CompareTo(const base_uint& b) const; - bool EqualTo(uint64_t b) const; - - friend inline const base_uint operator+(const base_uint& a, const base_uint& b) { return base_uint(a) += b; } - friend inline const base_uint operator-(const base_uint& a, const base_uint& b) { return base_uint(a) -= b; } - friend inline const base_uint operator*(const base_uint& a, const base_uint& b) { return base_uint(a) *= b; } - friend inline const base_uint operator/(const base_uint& a, const base_uint& b) { return base_uint(a) /= b; } - friend inline const base_uint operator|(const base_uint& a, const base_uint& b) { return base_uint(a) |= b; } - friend inline const base_uint operator&(const base_uint& a, const base_uint& b) { return base_uint(a) &= b; } - friend inline const base_uint operator^(const base_uint& a, const base_uint& b) { return base_uint(a) ^= b; } - friend inline const base_uint operator>>(const base_uint& a, int shift) { return base_uint(a) >>= shift; } - friend inline const base_uint operator<<(const base_uint& a, int shift) { return base_uint(a) <<= shift; } - friend inline const base_uint operator*(const base_uint& a, uint32_t b) { return base_uint(a) *= b; } - friend inline bool operator==(const base_uint& a, const base_uint& b) { return memcmp(a.pn, b.pn, sizeof(a.pn)) == 0; } - friend inline bool operator!=(const base_uint& a, const base_uint& b) { return memcmp(a.pn, b.pn, sizeof(a.pn)) != 0; } - friend inline bool operator>(const base_uint& a, const base_uint& b) { return a.CompareTo(b) > 0; } - friend inline bool operator<(const base_uint& a, const base_uint& b) { return a.CompareTo(b) < 0; } - friend inline bool operator>=(const base_uint& a, const base_uint& b) { return a.CompareTo(b) >= 0; } - friend inline bool operator<=(const base_uint& a, const base_uint& b) { return a.CompareTo(b) <= 0; } - friend inline bool operator==(const base_uint& a, uint64_t b) { return a.EqualTo(b); } - friend inline bool operator!=(const base_uint& a, uint64_t b) { return !a.EqualTo(b); } + friend inline bool operator==(const base_blob& a, const base_blob& b) { return memcmp(a.data, b.data, sizeof(a.data)) == 0; } + friend inline bool operator!=(const base_blob& a, const base_blob& b) { return memcmp(a.data, b.data, sizeof(a.data)) != 0; } + friend inline bool operator<(const base_blob& a, const base_blob& b) { return memcmp(a.data, b.data, sizeof(a.data)) < 0; } std::string GetHex() const; void SetHex(const char* psz); @@ -232,122 +52,107 @@ public: unsigned char* begin() { - return (unsigned char*)&pn[0]; + return &data[0]; } unsigned char* end() { - return (unsigned char*)&pn[WIDTH]; + return &data[WIDTH]; } const unsigned char* begin() const { - return (unsigned char*)&pn[0]; + return &data[0]; } const unsigned char* end() const { - return (unsigned char*)&pn[WIDTH]; + return &data[WIDTH]; } unsigned int size() const { - return sizeof(pn); - } - - /** - * Returns the position of the highest bit set plus one, or zero if the - * value is zero. - */ - unsigned int bits() const; - - uint64_t GetLow64() const - { - assert(WIDTH >= 2); - return pn[0] | (uint64_t)pn[1] << 32; + return sizeof(data); } unsigned int GetSerializeSize(int nType, int nVersion) const { - return sizeof(pn); + return sizeof(data); } template<typename Stream> void Serialize(Stream& s, int nType, int nVersion) const { - s.write((char*)pn, sizeof(pn)); + s.write((char*)data, sizeof(data)); } template<typename Stream> void Unserialize(Stream& s, int nType, int nVersion) { - s.read((char*)pn, sizeof(pn)); - } - - // Temporary for migration to opaque uint160/256 - uint64_t GetCheapHash() const - { - return GetLow64(); - } - void SetNull() - { - memset(pn, 0, sizeof(pn)); - } - bool IsNull() const - { - for (int i = 0; i < WIDTH; i++) - if (pn[i] != 0) - return false; - return true; + s.read((char*)data, sizeof(data)); } }; -/** 160-bit unsigned big integer. */ -class uint160 : public base_uint<160> { +/** 160-bit opaque blob. + * @note This type is called uint160 for historical reasons only. It is an opaque + * blob of 160 bits and has no integer operations. + */ +class uint160 : public base_blob<160> { public: uint160() {} - uint160(const base_uint<160>& b) : base_uint<160>(b) {} - uint160(uint64_t b) : base_uint<160>(b) {} - explicit uint160(const std::string& str) : base_uint<160>(str) {} - explicit uint160(const std::vector<unsigned char>& vch) : base_uint<160>(vch) {} + uint160(const base_blob<160>& b) : base_blob<160>(b) {} + explicit uint160(const std::vector<unsigned char>& vch) : base_blob<160>(vch) {} }; -/** 256-bit unsigned big integer. */ -class uint256 : public base_uint<256> { +/** 256-bit opaque blob. + * @note This type is called uint256 for historical reasons only. It is an + * opaque blob of 256 bits and has no integer operations. Use arith_uint256 if + * those are required. + */ +class uint256 : public base_blob<256> { public: uint256() {} - uint256(const base_uint<256>& b) : base_uint<256>(b) {} - uint256(uint64_t b) : base_uint<256>(b) {} - explicit uint256(const std::string& str) : base_uint<256>(str) {} - explicit uint256(const std::vector<unsigned char>& vch) : base_uint<256>(vch) {} - - /** - * The "compact" format is a representation of a whole - * number N using an unsigned 32bit number similar to a - * floating point format. - * The most significant 8 bits are the unsigned exponent of base 256. - * This exponent can be thought of as "number of bytes of N". - * The lower 23 bits are the mantissa. - * Bit number 24 (0x800000) represents the sign of N. - * N = (-1^sign) * mantissa * 256^(exponent-3) - * - * Satoshi's original implementation used BN_bn2mpi() and BN_mpi2bn(). - * MPI uses the most significant bit of the first byte as sign. - * Thus 0x1234560000 is compact (0x05123456) - * and 0xc0de000000 is compact (0x0600c0de) - * - * Bitcoin only uses this "compact" format for encoding difficulty - * targets, which are unsigned 256bit quantities. Thus, all the - * complexities of the sign bit and using base 256 are probably an - * implementation accident. + uint256(const base_blob<256>& b) : base_blob<256>(b) {} + explicit uint256(const std::vector<unsigned char>& vch) : base_blob<256>(vch) {} + + /** A cheap hash function that just returns 64 bits from the result, it can be + * used when the contents are considered uniformly random. It is not appropriate + * when the value can easily be influenced from outside as e.g. a network adversary could + * provide values to trigger worst-case behavior. + * @note The result of this function is not stable between little and big endian. */ - uint256& SetCompact(uint32_t nCompact, bool *pfNegative = NULL, bool *pfOverflow = NULL); - uint32_t GetCompact(bool fNegative = false) const; + uint64_t GetCheapHash() const + { + uint64_t result; + memcpy((void*)&result, (void*)data, 8); + return result; + } + /** A more secure, salted hash function. + * @note This hash is not stable between little and big endian. + */ uint64_t GetHash(const uint256& salt) const; }; -// Temporary for migration to opaque uint160/256 -inline uint256 uint256S(const std::string &x) { return uint256(x); } +/* uint256 from const char *. + * This is a separate function because the constructor uint256(const char*) can result + * in dangerously catching uint256(0). + */ +inline uint256 uint256S(const char *str) +{ + uint256 rv; + rv.SetHex(str); + return rv; +} +/* uint256 from std::string. + * This is a separate function because the constructor uint256(const std::string &str) can result + * in dangerously catching uint256(0) via std::string(const char*). + */ +inline uint256 uint256S(const std::string& str) +{ + uint256 rv; + rv.SetHex(str); + return rv; +} #endif // BITCOIN_UINT256_H |