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bitcoin-bitcoin-core/src/bignum.h
Dwayne C. Litzenberger 8c8e8c2e93 Fix bugs on 'unsigned char' platforms. 
In ISO C++, the signedness of 'char' is undefined.  On some platforms (e.g.
ARM), 'char' is an unsigned type, but some of the code relies on 'char' being
signed (as it is on x86).  This is indicated by compiler warnings like this:

 bignum.h: In constructor 'CBigNum::CBigNum(char)':
 bignum.h:81:59: warning: comparison is always true due to limited range of data type [-Wtype-limits]

 util.cpp: In function 'bool IsHex(const string&)':
 util.cpp:427:28: warning: comparison is always false due to limited range of data type [-Wtype-limits]

In particular, IsHex erroneously returned true regardless of the input
characters, as long as the length of the string was a positive multiple of 2.

Note: For testing, it's possible using GCC to force char to be unsigned by
adding the -funsigned-char parameter to xCXXFLAGS.
2012-04-18 00:33:32 -04:00

540 lines
15 KiB
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// Copyright (c) 2009-2010 Satoshi Nakamoto
// Copyright (c) 2009-2012 The Bitcoin developers
// Distributed under the MIT/X11 software license, see the accompanying
// file license.txt or http://www.opensource.org/licenses/mit-license.php.
#ifndef BITCOIN_BIGNUM_H
#define BITCOIN_BIGNUM_H
#include <stdexcept>
#include <vector>
#include <openssl/bn.h>
#include "util.h" // for uint64
/** Errors thrown by the bignum class */
class bignum_error : public std::runtime_error
{
public:
explicit bignum_error(const std::string& str) : std::runtime_error(str) {}
};
/** RAII encapsulated BN_CTX (OpenSSL bignum context) */
class CAutoBN_CTX
{
protected:
BN_CTX* pctx;
BN_CTX* operator=(BN_CTX* pnew) { return pctx = pnew; }
public:
CAutoBN_CTX()
{
pctx = BN_CTX_new();
if (pctx == NULL)
throw bignum_error("CAutoBN_CTX : BN_CTX_new() returned NULL");
}
~CAutoBN_CTX()
{
if (pctx != NULL)
BN_CTX_free(pctx);
}
operator BN_CTX*() { return pctx; }
BN_CTX& operator*() { return *pctx; }
BN_CTX** operator&() { return &pctx; }
bool operator!() { return (pctx == NULL); }
};
/** C++ wrapper for BIGNUM (OpenSSL bignum) */
class CBigNum : public BIGNUM
{
public:
CBigNum()
{
BN_init(this);
}
CBigNum(const CBigNum& b)
{
BN_init(this);
if (!BN_copy(this, &b))
{
BN_clear_free(this);
throw bignum_error("CBigNum::CBigNum(const CBigNum&) : BN_copy failed");
}
}
CBigNum& operator=(const CBigNum& b)
{
if (!BN_copy(this, &b))
throw bignum_error("CBigNum::operator= : BN_copy failed");
return (*this);
}
~CBigNum()
{
BN_clear_free(this);
}
//CBigNum(char n) is not portable. Use 'signed char' or 'unsigned char'.
CBigNum(signed char n) { BN_init(this); if (n >= 0) setulong(n); else setint64(n); }
CBigNum(short n) { BN_init(this); if (n >= 0) setulong(n); else setint64(n); }
CBigNum(int n) { BN_init(this); if (n >= 0) setulong(n); else setint64(n); }
CBigNum(long n) { BN_init(this); if (n >= 0) setulong(n); else setint64(n); }
CBigNum(int64 n) { BN_init(this); setint64(n); }
CBigNum(unsigned char n) { BN_init(this); setulong(n); }
CBigNum(unsigned short n) { BN_init(this); setulong(n); }
CBigNum(unsigned int n) { BN_init(this); setulong(n); }
CBigNum(unsigned long n) { BN_init(this); setulong(n); }
CBigNum(uint64 n) { BN_init(this); setuint64(n); }
explicit CBigNum(uint256 n) { BN_init(this); setuint256(n); }
explicit CBigNum(const std::vector<unsigned char>& vch)
{
BN_init(this);
setvch(vch);
}
void setulong(unsigned long n)
{
if (!BN_set_word(this, n))
throw bignum_error("CBigNum conversion from unsigned long : BN_set_word failed");
}
unsigned long getulong() const
{
return BN_get_word(this);
}
unsigned int getuint() const
{
return BN_get_word(this);
}
int getint() const
{
unsigned long n = BN_get_word(this);
if (!BN_is_negative(this))
return (n > std::numeric_limits<int>::max() ? std::numeric_limits<int>::max() : n);
else
return (n > std::numeric_limits<int>::max() ? std::numeric_limits<int>::min() : -(int)n);
}
void setint64(int64 n)
{
unsigned char pch[sizeof(n) + 6];
unsigned char* p = pch + 4;
bool fNegative = false;
if (n < (int64)0)
{
n = -n;
fNegative = true;
}
bool fLeadingZeroes = true;
for (int i = 0; i < 8; i++)
{
unsigned char c = (n >> 56) & 0xff;
n <<= 8;
if (fLeadingZeroes)
{
if (c == 0)
continue;
if (c & 0x80)
*p++ = (fNegative ? 0x80 : 0);
else if (fNegative)
c |= 0x80;
fLeadingZeroes = false;
}
*p++ = c;
}
unsigned int nSize = p - (pch + 4);
pch[0] = (nSize >> 24) & 0xff;
pch[1] = (nSize >> 16) & 0xff;
pch[2] = (nSize >> 8) & 0xff;
pch[3] = (nSize) & 0xff;
BN_mpi2bn(pch, p - pch, this);
}
void setuint64(uint64 n)
{
unsigned char pch[sizeof(n) + 6];
unsigned char* p = pch + 4;
bool fLeadingZeroes = true;
for (int i = 0; i < 8; i++)
{
unsigned char c = (n >> 56) & 0xff;
n <<= 8;
if (fLeadingZeroes)
{
if (c == 0)
continue;
if (c & 0x80)
*p++ = 0;
fLeadingZeroes = false;
}
*p++ = c;
}
unsigned int nSize = p - (pch + 4);
pch[0] = (nSize >> 24) & 0xff;
pch[1] = (nSize >> 16) & 0xff;
pch[2] = (nSize >> 8) & 0xff;
pch[3] = (nSize) & 0xff;
BN_mpi2bn(pch, p - pch, this);
}
void setuint256(uint256 n)
{
unsigned char pch[sizeof(n) + 6];
unsigned char* p = pch + 4;
bool fLeadingZeroes = true;
unsigned char* pbegin = (unsigned char*)&n;
unsigned char* psrc = pbegin + sizeof(n);
while (psrc != pbegin)
{
unsigned char c = *(--psrc);
if (fLeadingZeroes)
{
if (c == 0)
continue;
if (c & 0x80)
*p++ = 0;
fLeadingZeroes = false;
}
*p++ = c;
}
unsigned int nSize = p - (pch + 4);
pch[0] = (nSize >> 24) & 0xff;
pch[1] = (nSize >> 16) & 0xff;
pch[2] = (nSize >> 8) & 0xff;
pch[3] = (nSize >> 0) & 0xff;
BN_mpi2bn(pch, p - pch, this);
}
uint256 getuint256()
{
unsigned int nSize = BN_bn2mpi(this, NULL);
if (nSize < 4)
return 0;
std::vector<unsigned char> vch(nSize);
BN_bn2mpi(this, &vch[0]);
if (vch.size() > 4)
vch[4] &= 0x7f;
uint256 n = 0;
for (int i = 0, j = vch.size()-1; i < sizeof(n) && j >= 4; i++, j--)
((unsigned char*)&n)[i] = vch[j];
return n;
}
void setvch(const std::vector<unsigned char>& vch)
{
std::vector<unsigned char> vch2(vch.size() + 4);
unsigned int nSize = vch.size();
// BIGNUM's byte stream format expects 4 bytes of
// big endian size data info at the front
vch2[0] = (nSize >> 24) & 0xff;
vch2[1] = (nSize >> 16) & 0xff;
vch2[2] = (nSize >> 8) & 0xff;
vch2[3] = (nSize >> 0) & 0xff;
// swap data to big endian
reverse_copy(vch.begin(), vch.end(), vch2.begin() + 4);
BN_mpi2bn(&vch2[0], vch2.size(), this);
}
std::vector<unsigned char> getvch() const
{
unsigned int nSize = BN_bn2mpi(this, NULL);
if (nSize <= 4)
return std::vector<unsigned char>();
std::vector<unsigned char> vch(nSize);
BN_bn2mpi(this, &vch[0]);
vch.erase(vch.begin(), vch.begin() + 4);
reverse(vch.begin(), vch.end());
return vch;
}
CBigNum& SetCompact(unsigned int nCompact)
{
unsigned int nSize = nCompact >> 24;
std::vector<unsigned char> vch(4 + nSize);
vch[3] = nSize;
if (nSize >= 1) vch[4] = (nCompact >> 16) & 0xff;
if (nSize >= 2) vch[5] = (nCompact >> 8) & 0xff;
if (nSize >= 3) vch[6] = (nCompact >> 0) & 0xff;
BN_mpi2bn(&vch[0], vch.size(), this);
return *this;
}
unsigned int GetCompact() const
{
unsigned int nSize = BN_bn2mpi(this, NULL);
std::vector<unsigned char> vch(nSize);
nSize -= 4;
BN_bn2mpi(this, &vch[0]);
unsigned int nCompact = nSize << 24;
if (nSize >= 1) nCompact |= (vch[4] << 16);
if (nSize >= 2) nCompact |= (vch[5] << 8);
if (nSize >= 3) nCompact |= (vch[6] << 0);
return nCompact;
}
void SetHex(const std::string& str)
{
// skip 0x
const char* psz = str.c_str();
while (isspace(*psz))
psz++;
bool fNegative = false;
if (*psz == '-')
{
fNegative = true;
psz++;
}
if (psz[0] == '0' && tolower(psz[1]) == 'x')
psz += 2;
while (isspace(*psz))
psz++;
// hex string to bignum
static signed char phexdigit[256] = { 0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0, 0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0, 0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0, 0,1,2,3,4,5,6,7,8,9,0,0,0,0,0,0, 0,0xa,0xb,0xc,0xd,0xe,0xf,0,0,0,0,0,0,0,0,0, 0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0, 0,0xa,0xb,0xc,0xd,0xe,0xf,0,0,0,0,0,0,0,0,0 };
*this = 0;
while (isxdigit(*psz))
{
*this <<= 4;
int n = phexdigit[(unsigned char)*psz++];
*this += n;
}
if (fNegative)
*this = 0 - *this;
}
std::string ToString(int nBase=10) const
{
CAutoBN_CTX pctx;
CBigNum bnBase = nBase;
CBigNum bn0 = 0;
std::string str;
CBigNum bn = *this;
BN_set_negative(&bn, false);
CBigNum dv;
CBigNum rem;
if (BN_cmp(&bn, &bn0) == 0)
return "0";
while (BN_cmp(&bn, &bn0) > 0)
{
if (!BN_div(&dv, &rem, &bn, &bnBase, pctx))
throw bignum_error("CBigNum::ToString() : BN_div failed");
bn = dv;
unsigned int c = rem.getulong();
str += "0123456789abcdef"[c];
}
if (BN_is_negative(this))
str += "-";
reverse(str.begin(), str.end());
return str;
}
std::string GetHex() const
{
return ToString(16);
}
unsigned int GetSerializeSize(int nType=0, int nVersion=PROTOCOL_VERSION) const
{
return ::GetSerializeSize(getvch(), nType, nVersion);
}
template<typename Stream>
void Serialize(Stream& s, int nType=0, int nVersion=PROTOCOL_VERSION) const
{
::Serialize(s, getvch(), nType, nVersion);
}
template<typename Stream>
void Unserialize(Stream& s, int nType=0, int nVersion=PROTOCOL_VERSION)
{
std::vector<unsigned char> vch;
::Unserialize(s, vch, nType, nVersion);
setvch(vch);
}
bool operator!() const
{
return BN_is_zero(this);
}
CBigNum& operator+=(const CBigNum& b)
{
if (!BN_add(this, this, &b))
throw bignum_error("CBigNum::operator+= : BN_add failed");
return *this;
}
CBigNum& operator-=(const CBigNum& b)
{
*this = *this - b;
return *this;
}
CBigNum& operator*=(const CBigNum& b)
{
CAutoBN_CTX pctx;
if (!BN_mul(this, this, &b, pctx))
throw bignum_error("CBigNum::operator*= : BN_mul failed");
return *this;
}
CBigNum& operator/=(const CBigNum& b)
{
*this = *this / b;
return *this;
}
CBigNum& operator%=(const CBigNum& b)
{
*this = *this % b;
return *this;
}
CBigNum& operator<<=(unsigned int shift)
{
if (!BN_lshift(this, this, shift))
throw bignum_error("CBigNum:operator<<= : BN_lshift failed");
return *this;
}
CBigNum& operator>>=(unsigned int shift)
{
// Note: BN_rshift segfaults on 64-bit if 2^shift is greater than the number
// if built on ubuntu 9.04 or 9.10, probably depends on version of openssl
CBigNum a = 1;
a <<= shift;
if (BN_cmp(&a, this) > 0)
{
*this = 0;
return *this;
}
if (!BN_rshift(this, this, shift))
throw bignum_error("CBigNum:operator>>= : BN_rshift failed");
return *this;
}
CBigNum& operator++()
{
// prefix operator
if (!BN_add(this, this, BN_value_one()))
throw bignum_error("CBigNum::operator++ : BN_add failed");
return *this;
}
const CBigNum operator++(int)
{
// postfix operator
const CBigNum ret = *this;
++(*this);
return ret;
}
CBigNum& operator--()
{
// prefix operator
CBigNum r;
if (!BN_sub(&r, this, BN_value_one()))
throw bignum_error("CBigNum::operator-- : BN_sub failed");
*this = r;
return *this;
}
const CBigNum operator--(int)
{
// postfix operator
const CBigNum ret = *this;
--(*this);
return ret;
}
friend inline const CBigNum operator-(const CBigNum& a, const CBigNum& b);
friend inline const CBigNum operator/(const CBigNum& a, const CBigNum& b);
friend inline const CBigNum operator%(const CBigNum& a, const CBigNum& b);
};
inline const CBigNum operator+(const CBigNum& a, const CBigNum& b)
{
CBigNum r;
if (!BN_add(&r, &a, &b))
throw bignum_error("CBigNum::operator+ : BN_add failed");
return r;
}
inline const CBigNum operator-(const CBigNum& a, const CBigNum& b)
{
CBigNum r;
if (!BN_sub(&r, &a, &b))
throw bignum_error("CBigNum::operator- : BN_sub failed");
return r;
}
inline const CBigNum operator-(const CBigNum& a)
{
CBigNum r(a);
BN_set_negative(&r, !BN_is_negative(&r));
return r;
}
inline const CBigNum operator*(const CBigNum& a, const CBigNum& b)
{
CAutoBN_CTX pctx;
CBigNum r;
if (!BN_mul(&r, &a, &b, pctx))
throw bignum_error("CBigNum::operator* : BN_mul failed");
return r;
}
inline const CBigNum operator/(const CBigNum& a, const CBigNum& b)
{
CAutoBN_CTX pctx;
CBigNum r;
if (!BN_div(&r, NULL, &a, &b, pctx))
throw bignum_error("CBigNum::operator/ : BN_div failed");
return r;
}
inline const CBigNum operator%(const CBigNum& a, const CBigNum& b)
{
CAutoBN_CTX pctx;
CBigNum r;
if (!BN_mod(&r, &a, &b, pctx))
throw bignum_error("CBigNum::operator% : BN_div failed");
return r;
}
inline const CBigNum operator<<(const CBigNum& a, unsigned int shift)
{
CBigNum r;
if (!BN_lshift(&r, &a, shift))
throw bignum_error("CBigNum:operator<< : BN_lshift failed");
return r;
}
inline const CBigNum operator>>(const CBigNum& a, unsigned int shift)
{
CBigNum r = a;
r >>= shift;
return r;
}
inline bool operator==(const CBigNum& a, const CBigNum& b) { return (BN_cmp(&a, &b) == 0); }
inline bool operator!=(const CBigNum& a, const CBigNum& b) { return (BN_cmp(&a, &b) != 0); }
inline bool operator<=(const CBigNum& a, const CBigNum& b) { return (BN_cmp(&a, &b) <= 0); }
inline bool operator>=(const CBigNum& a, const CBigNum& b) { return (BN_cmp(&a, &b) >= 0); }
inline bool operator<(const CBigNum& a, const CBigNum& b) { return (BN_cmp(&a, &b) < 0); }
inline bool operator>(const CBigNum& a, const CBigNum& b) { return (BN_cmp(&a, &b) > 0); }
#endif
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