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// Copyright (c) 2009-2010 Satoshi Nakamoto
// Copyright (c) 2009-2018 The Bitcoin Core developers
// Distributed under the MIT software license, see the accompanying
// file COPYING or http://www.opensource.org/licenses/mit-license.php.
#include <script/interpreter.h>
#include <crypto/ripemd160.h>
#include <crypto/sha1.h>
#include <crypto/sha256.h>
#include <pubkey.h>
#include <script/script.h>
#include <uint256.h>
typedef std::vector<unsigned char> valtype;
namespace {
inline bool set_success(ScriptError* ret)
{
if (ret)
*ret = SCRIPT_ERR_OK;
return true;
}
inline bool set_error(ScriptError* ret, const ScriptError serror)
{
if (ret)
*ret = serror;
return false;
}
} // namespace
bool CastToBool(const valtype& vch)
{
for (unsigned int i = 0; i < vch.size(); i++)
{
if (vch[i] != 0)
{
// Can be negative zero
if (i == vch.size()-1 && vch[i] == 0x80)
return false;
return true;
}
}
return false;
}
/**
* Script is a stack machine (like Forth) that evaluates a predicate
* returning a bool indicating valid or not. There are no loops.
*/
#define stacktop(i) (stack.at(stack.size()+(i)))
#define altstacktop(i) (altstack.at(altstack.size()+(i)))
static inline void popstack(std::vector<valtype>& stack)
{
if (stack.empty())
throw std::runtime_error("popstack(): stack empty");
stack.pop_back();
}
bool static IsCompressedOrUncompressedPubKey(const valtype &vchPubKey) {
if (vchPubKey.size() < CPubKey::COMPRESSED_PUBLIC_KEY_SIZE) {
// Non-canonical public key: too short
return false;
}
if (vchPubKey[0] == 0x04) {
if (vchPubKey.size() != CPubKey::PUBLIC_KEY_SIZE) {
// Non-canonical public key: invalid length for uncompressed key
return false;
}
} else if (vchPubKey[0] == 0x02 || vchPubKey[0] == 0x03) {
if (vchPubKey.size() != CPubKey::COMPRESSED_PUBLIC_KEY_SIZE) {
// Non-canonical public key: invalid length for compressed key
return false;
}
} else {
// Non-canonical public key: neither compressed nor uncompressed
return false;
}
return true;
}
bool static IsCompressedPubKey(const valtype &vchPubKey) {
if (vchPubKey.size() != CPubKey::COMPRESSED_PUBLIC_KEY_SIZE) {
// Non-canonical public key: invalid length for compressed key
return false;
}
if (vchPubKey[0] != 0x02 && vchPubKey[0] != 0x03) {
// Non-canonical public key: invalid prefix for compressed key
return false;
}
return true;
}
/**
* A canonical signature exists of: <30> <total len> <02> <len R> <R> <02> <len S> <S> <hashtype>
* Where R and S are not negative (their first byte has its highest bit not set), and not
* excessively padded (do not start with a 0 byte, unless an otherwise negative number follows,
* in which case a single 0 byte is necessary and even required).
*
* See https://bitcointalk.org/index.php?topic=8392.msg127623#msg127623
*
* This function is consensus-critical since BIP66.
*/
bool static IsValidSignatureEncoding(const std::vector<unsigned char> &sig) {
// Format: 0x30 [total-length] 0x02 [R-length] [R] 0x02 [S-length] [S] [sighash]
// * total-length: 1-byte length descriptor of everything that follows,
// excluding the sighash byte.
// * R-length: 1-byte length descriptor of the R value that follows.
// * R: arbitrary-length big-endian encoded R value. It must use the shortest
// possible encoding for a positive integer (which means no null bytes at
// the start, except a single one when the next byte has its highest bit set).
// * S-length: 1-byte length descriptor of the S value that follows.
// * S: arbitrary-length big-endian encoded S value. The same rules apply.
// * sighash: 1-byte value indicating what data is hashed (not part of the DER
// signature)
// Minimum and maximum size constraints.
if (sig.size() < 9) return false;
if (sig.size() > 73) return false;
// A signature is of type 0x30 (compound).
if (sig[0] != 0x30) return false;
// Make sure the length covers the entire signature.
if (sig[1] != sig.size() - 3) return false;
// Extract the length of the R element.
unsigned int lenR = sig[3];
// Make sure the length of the S element is still inside the signature.
if (5 + lenR >= sig.size()) return false;
// Extract the length of the S element.
unsigned int lenS = sig[5 + lenR];
// Verify that the length of the signature matches the sum of the length
// of the elements.
if ((size_t)(lenR + lenS + 7) != sig.size()) return false;
// Check whether the R element is an integer.
if (sig[2] != 0x02) return false;
// Zero-length integers are not allowed for R.
if (lenR == 0) return false;
// Negative numbers are not allowed for R.
if (sig[4] & 0x80) return false;
// Null bytes at the start of R are not allowed, unless R would
// otherwise be interpreted as a negative number.
if (lenR > 1 && (sig[4] == 0x00) && !(sig[5] & 0x80)) return false;
// Check whether the S element is an integer.
if (sig[lenR + 4] != 0x02) return false;
// Zero-length integers are not allowed for S.
if (lenS == 0) return false;
// Negative numbers are not allowed for S.
if (sig[lenR + 6] & 0x80) return false;
// Null bytes at the start of S are not allowed, unless S would otherwise be
// interpreted as a negative number.
if (lenS > 1 && (sig[lenR + 6] == 0x00) && !(sig[lenR + 7] & 0x80)) return false;
return true;
}
bool static IsLowDERSignature(const valtype &vchSig, ScriptError* serror) {
if (!IsValidSignatureEncoding(vchSig)) {
return set_error(serror, SCRIPT_ERR_SIG_DER);
}
// https://bitcoin.stackexchange.com/a/12556:
// Also note that inside transaction signatures, an extra hashtype byte
// follows the actual signature data.
std::vector<unsigned char> vchSigCopy(vchSig.begin(), vchSig.begin() + vchSig.size() - 1);
// If the S value is above the order of the curve divided by two, its
// complement modulo the order could have been used instead, which is
// one byte shorter when encoded correctly.
if (!CPubKey::CheckLowS(vchSigCopy)) {
return set_error(serror, SCRIPT_ERR_SIG_HIGH_S);
}
return true;
}
bool static IsDefinedHashtypeSignature(const valtype &vchSig) {
if (vchSig.size() == 0) {
return false;
}
unsigned char nHashType = vchSig[vchSig.size() - 1] & (~(SIGHASH_ANYONECANPAY));
if (nHashType < SIGHASH_ALL || nHashType > SIGHASH_SINGLE)
return false;
return true;
}
bool CheckSignatureEncoding(const std::vector<unsigned char> &vchSig, unsigned int flags, ScriptError* serror) {
// Empty signature. Not strictly DER encoded, but allowed to provide a
// compact way to provide an invalid signature for use with CHECK(MULTI)SIG
if (vchSig.size() == 0) {
return true;
}
if ((flags & (SCRIPT_VERIFY_DERSIG | SCRIPT_VERIFY_LOW_S | SCRIPT_VERIFY_STRICTENC)) != 0 && !IsValidSignatureEncoding(vchSig)) {
return set_error(serror, SCRIPT_ERR_SIG_DER);
} else if ((flags & SCRIPT_VERIFY_LOW_S) != 0 && !IsLowDERSignature(vchSig, serror)) {
// serror is set
return false;
} else if ((flags & SCRIPT_VERIFY_STRICTENC) != 0 && !IsDefinedHashtypeSignature(vchSig)) {
return set_error(serror, SCRIPT_ERR_SIG_HASHTYPE);
}
return true;
}
bool static CheckPubKeyEncoding(const valtype &vchPubKey, unsigned int flags, const SigVersion &sigversion, ScriptError* serror) {
if ((flags & SCRIPT_VERIFY_STRICTENC) != 0 && !IsCompressedOrUncompressedPubKey(vchPubKey)) {
return set_error(serror, SCRIPT_ERR_PUBKEYTYPE);
}
// Only compressed keys are accepted in segwit
if ((flags & SCRIPT_VERIFY_WITNESS_PUBKEYTYPE) != 0 && sigversion == SigVersion::WITNESS_V0 && !IsCompressedPubKey(vchPubKey)) {
return set_error(serror, SCRIPT_ERR_WITNESS_PUBKEYTYPE);
}
return true;
}
bool static CheckMinimalPush(const valtype& data, opcodetype opcode) {
// Excludes OP_1NEGATE, OP_1-16 since they are by definition minimal
assert(0 <= opcode && opcode <= OP_PUSHDATA4);
if (data.size() == 0) {
// Should have used OP_0.
return opcode == OP_0;
} else if (data.size() == 1 && data[0] >= 1 && data[0] <= 16) {
// Should have used OP_1 .. OP_16.
return false;
} else if (data.size() == 1 && data[0] == 0x81) {
// Should have used OP_1NEGATE.
return false;
} else if (data.size() <= 75) {
// Must have used a direct push (opcode indicating number of bytes pushed + those bytes).
return opcode == data.size();
} else if (data.size() <= 255) {
// Must have used OP_PUSHDATA.
return opcode == OP_PUSHDATA1;
} else if (data.size() <= 65535) {
// Must have used OP_PUSHDATA2.
return opcode == OP_PUSHDATA2;
}
return true;
}
int FindAndDelete(CScript& script, const CScript& b)
{
int nFound = 0;
if (b.empty())
return nFound;
CScript result;
CScript::const_iterator pc = script.begin(), pc2 = script.begin(), end = script.end();
opcodetype opcode;
do
{
result.insert(result.end(), pc2, pc);
while (static_cast<size_t>(end - pc) >= b.size() && std::equal(b.begin(), b.end(), pc))
{
pc = pc + b.size();
++nFound;
}
pc2 = pc;
}
while (script.GetOp(pc, opcode));
if (nFound > 0) {
result.insert(result.end(), pc2, end);
script = std::move(result);
}
return nFound;
}
bool EvalScript(std::vector<std::vector<unsigned char> >& stack, const CScript& script, unsigned int flags, const BaseSignatureChecker& checker, SigVersion sigversion, ScriptError* serror)
{
static const CScriptNum bnZero(0);
static const CScriptNum bnOne(1);
// static const CScriptNum bnFalse(0);
// static const CScriptNum bnTrue(1);
static const valtype vchFalse(0);
// static const valtype vchZero(0);
static const valtype vchTrue(1, 1);
CScript::const_iterator pc = script.begin();
CScript::const_iterator pend = script.end();
CScript::const_iterator pbegincodehash = script.begin();
opcodetype opcode;
valtype vchPushValue;
std::vector<bool> vfExec;
std::vector<valtype> altstack;
set_error(serror, SCRIPT_ERR_UNKNOWN_ERROR);
if (script.size() > MAX_SCRIPT_SIZE)
return set_error(serror, SCRIPT_ERR_SCRIPT_SIZE);
int nOpCount = 0;
bool fRequireMinimal = (flags & SCRIPT_VERIFY_MINIMALDATA) != 0;
try
{
while (pc < pend)
{
bool fExec = !count(vfExec.begin(), vfExec.end(), false);
//
// Read instruction
//
if (!script.GetOp(pc, opcode, vchPushValue))
return set_error(serror, SCRIPT_ERR_BAD_OPCODE);
if (vchPushValue.size() > MAX_SCRIPT_ELEMENT_SIZE)
return set_error(serror, SCRIPT_ERR_PUSH_SIZE);
// Note how OP_RESERVED does not count towards the opcode limit.
if (opcode > OP_16 && ++nOpCount > MAX_OPS_PER_SCRIPT)
return set_error(serror, SCRIPT_ERR_OP_COUNT);
if (opcode == OP_CAT ||
opcode == OP_SUBSTR ||
opcode == OP_LEFT ||
opcode == OP_RIGHT ||
opcode == OP_INVERT ||
opcode == OP_AND ||
opcode == OP_OR ||
opcode == OP_XOR ||
opcode == OP_2MUL ||
opcode == OP_2DIV ||
opcode == OP_MUL ||
opcode == OP_DIV ||
opcode == OP_MOD ||
opcode == OP_LSHIFT ||
opcode == OP_RSHIFT)
return set_error(serror, SCRIPT_ERR_DISABLED_OPCODE); // Disabled opcodes.
// With SCRIPT_VERIFY_CONST_SCRIPTCODE, OP_CODESEPARATOR in non-segwit script is rejected even in an unexecuted branch
if (opcode == OP_CODESEPARATOR && sigversion == SigVersion::BASE && (flags & SCRIPT_VERIFY_CONST_SCRIPTCODE))
return set_error(serror, SCRIPT_ERR_OP_CODESEPARATOR);
if (fExec && 0 <= opcode && opcode <= OP_PUSHDATA4) {
if (fRequireMinimal && !CheckMinimalPush(vchPushValue, opcode)) {
return set_error(serror, SCRIPT_ERR_MINIMALDATA);
}
stack.push_back(vchPushValue);
} else if (fExec || (OP_IF <= opcode && opcode <= OP_ENDIF))
switch (opcode)
{
//
// Push value
//
case OP_1NEGATE:
case OP_1:
case OP_2:
case OP_3:
case OP_4:
case OP_5:
case OP_6:
case OP_7:
case OP_8:
case OP_9:
case OP_10:
case OP_11:
case OP_12:
case OP_13:
case OP_14:
case OP_15:
case OP_16:
{
// ( -- value)
CScriptNum bn((int)opcode - (int)(OP_1 - 1));
stack.push_back(bn.getvch());
// The result of these opcodes should always be the minimal way to push the data
// they push, so no need for a CheckMinimalPush here.
}
break;
//
// Control
//
case OP_NOP:
break;
case OP_CHECKLOCKTIMEVERIFY:
{
if (!(flags & SCRIPT_VERIFY_CHECKLOCKTIMEVERIFY)) {
// not enabled; treat as a NOP2
break;
}
if (stack.size() < 1)
return set_error(serror, SCRIPT_ERR_INVALID_STACK_OPERATION);
// Note that elsewhere numeric opcodes are limited to
// operands in the range -2**31+1 to 2**31-1, however it is
// legal for opcodes to produce results exceeding that
// range. This limitation is implemented by CScriptNum's
// default 4-byte limit.
//
// If we kept to that limit we'd have a year 2038 problem,
// even though the nLockTime field in transactions
// themselves is uint32 which only becomes meaningless
// after the year 2106.
//
// Thus as a special case we tell CScriptNum to accept up
// to 5-byte bignums, which are good until 2**39-1, well
// beyond the 2**32-1 limit of the nLockTime field itself.
const CScriptNum nLockTime(stacktop(-1), fRequireMinimal, 5);
// In the rare event that the argument may be < 0 due to
// some arithmetic being done first, you can always use
// 0 MAX CHECKLOCKTIMEVERIFY.
if (nLockTime < 0)
return set_error(serror, SCRIPT_ERR_NEGATIVE_LOCKTIME);
// Actually compare the specified lock time with the transaction.
if (!checker.CheckLockTime(nLockTime))
return set_error(serror, SCRIPT_ERR_UNSATISFIED_LOCKTIME);
break;
}
case OP_CHECKSEQUENCEVERIFY:
{
if (!(flags & SCRIPT_VERIFY_CHECKSEQUENCEVERIFY)) {
// not enabled; treat as a NOP3
break;
}
if (stack.size() < 1)
return set_error(serror, SCRIPT_ERR_INVALID_STACK_OPERATION);
// nSequence, like nLockTime, is a 32-bit unsigned integer
// field. See the comment in CHECKLOCKTIMEVERIFY regarding
// 5-byte numeric operands.
const CScriptNum nSequence(stacktop(-1), fRequireMinimal, 5);
// In the rare event that the argument may be < 0 due to
// some arithmetic being done first, you can always use
// 0 MAX CHECKSEQUENCEVERIFY.
if (nSequence < 0)
return set_error(serror, SCRIPT_ERR_NEGATIVE_LOCKTIME);
// To provide for future soft-fork extensibility, if the
// operand has the disabled lock-time flag set,
// CHECKSEQUENCEVERIFY behaves as a NOP.
if ((nSequence & CTxIn::SEQUENCE_LOCKTIME_DISABLE_FLAG) != 0)
break;
// Compare the specified sequence number with the input.
if (!checker.CheckSequence(nSequence))
return set_error(serror, SCRIPT_ERR_UNSATISFIED_LOCKTIME);
break;
}
case OP_NOP1: case OP_NOP4: case OP_NOP5:
case OP_NOP6: case OP_NOP7: case OP_NOP8: case OP_NOP9: case OP_NOP10:
{
if (flags & SCRIPT_VERIFY_DISCOURAGE_UPGRADABLE_NOPS)
return set_error(serror, SCRIPT_ERR_DISCOURAGE_UPGRADABLE_NOPS);
}
break;
case OP_IF:
case OP_NOTIF:
{
// <expression> if [statements] [else [statements]] endif
bool fValue = false;
if (fExec)
{
if (stack.size() < 1)
return set_error(serror, SCRIPT_ERR_UNBALANCED_CONDITIONAL);
valtype& vch = stacktop(-1);
if (sigversion == SigVersion::WITNESS_V0 && (flags & SCRIPT_VERIFY_MINIMALIF)) {
if (vch.size() > 1)
return set_error(serror, SCRIPT_ERR_MINIMALIF);
if (vch.size() == 1 && vch[0] != 1)
return set_error(serror, SCRIPT_ERR_MINIMALIF);
}
fValue = CastToBool(vch);
if (opcode == OP_NOTIF)
fValue = !fValue;
popstack(stack);
}
vfExec.push_back(fValue);
}
break;
case OP_ELSE:
{
if (vfExec.empty())
return set_error(serror, SCRIPT_ERR_UNBALANCED_CONDITIONAL);
vfExec.back() = !vfExec.back();
}
break;
case OP_ENDIF:
{
if (vfExec.empty())
return set_error(serror, SCRIPT_ERR_UNBALANCED_CONDITIONAL);
vfExec.pop_back();
}
break;
case OP_VERIFY:
{
// (true -- ) or
// (false -- false) and return
if (stack.size() < 1)
return set_error(serror, SCRIPT_ERR_INVALID_STACK_OPERATION);
bool fValue = CastToBool(stacktop(-1));
if (fValue)
popstack(stack);
else
return set_error(serror, SCRIPT_ERR_VERIFY);
}
break;
case OP_RETURN:
{
return set_error(serror, SCRIPT_ERR_OP_RETURN);
}
break;
//
// Stack ops
//
case OP_TOALTSTACK:
{
if (stack.size() < 1)
return set_error(serror, SCRIPT_ERR_INVALID_STACK_OPERATION);
altstack.push_back(stacktop(-1));
popstack(stack);
}
break;
case OP_FROMALTSTACK:
{
if (altstack.size() < 1)
return set_error(serror, SCRIPT_ERR_INVALID_ALTSTACK_OPERATION);
stack.push_back(altstacktop(-1));
popstack(altstack);
}
break;
case OP_2DROP:
{
// (x1 x2 -- )
if (stack.size() < 2)
return set_error(serror, SCRIPT_ERR_INVALID_STACK_OPERATION);
popstack(stack);
popstack(stack);
}
break;
case OP_2DUP:
{
// (x1 x2 -- x1 x2 x1 x2)
if (stack.size() < 2)
return set_error(serror, SCRIPT_ERR_INVALID_STACK_OPERATION);
valtype vch1 = stacktop(-2);
valtype vch2 = stacktop(-1);
stack.push_back(vch1);
stack.push_back(vch2);
}
break;
case OP_3DUP:
{
// (x1 x2 x3 -- x1 x2 x3 x1 x2 x3)
if (stack.size() < 3)
return set_error(serror, SCRIPT_ERR_INVALID_STACK_OPERATION);
valtype vch1 = stacktop(-3);
valtype vch2 = stacktop(-2);
valtype vch3 = stacktop(-1);
stack.push_back(vch1);
stack.push_back(vch2);
stack.push_back(vch3);
}
break;
case OP_2OVER:
{
// (x1 x2 x3 x4 -- x1 x2 x3 x4 x1 x2)
if (stack.size() < 4)
return set_error(serror, SCRIPT_ERR_INVALID_STACK_OPERATION);
valtype vch1 = stacktop(-4);
valtype vch2 = stacktop(-3);
stack.push_back(vch1);
stack.push_back(vch2);
}
break;
case OP_2ROT:
{
// (x1 x2 x3 x4 x5 x6 -- x3 x4 x5 x6 x1 x2)
if (stack.size() < 6)
return set_error(serror, SCRIPT_ERR_INVALID_STACK_OPERATION);
valtype vch1 = stacktop(-6);
valtype vch2 = stacktop(-5);
stack.erase(stack.end()-6, stack.end()-4);
stack.push_back(vch1);
stack.push_back(vch2);
}
break;
case OP_2SWAP:
{
// (x1 x2 x3 x4 -- x3 x4 x1 x2)
if (stack.size() < 4)
return set_error(serror, SCRIPT_ERR_INVALID_STACK_OPERATION);
swap(stacktop(-4), stacktop(-2));
swap(stacktop(-3), stacktop(-1));
}
break;
case OP_IFDUP:
{
// (x - 0 | x x)
if (stack.size() < 1)
return set_error(serror, SCRIPT_ERR_INVALID_STACK_OPERATION);
valtype vch = stacktop(-1);
if (CastToBool(vch))
stack.push_back(vch);
}
break;
case OP_DEPTH:
{
// -- stacksize
CScriptNum bn(stack.size());
stack.push_back(bn.getvch());
}
break;
case OP_DROP:
{
// (x -- )
if (stack.size() < 1)
return set_error(serror, SCRIPT_ERR_INVALID_STACK_OPERATION);
popstack(stack);
}
break;
case OP_DUP:
{
// (x -- x x)
if (stack.size() < 1)
return set_error(serror, SCRIPT_ERR_INVALID_STACK_OPERATION);
valtype vch = stacktop(-1);
stack.push_back(vch);
}
break;
case OP_NIP:
{
// (x1 x2 -- x2)
if (stack.size() < 2)
return set_error(serror, SCRIPT_ERR_INVALID_STACK_OPERATION);
stack.erase(stack.end() - 2);
}
break;
case OP_OVER:
{
// (x1 x2 -- x1 x2 x1)
if (stack.size() < 2)
return set_error(serror, SCRIPT_ERR_INVALID_STACK_OPERATION);
valtype vch = stacktop(-2);
stack.push_back(vch);
}
break;
case OP_PICK:
case OP_ROLL:
{
// (xn ... x2 x1 x0 n - xn ... x2 x1 x0 xn)
// (xn ... x2 x1 x0 n - ... x2 x1 x0 xn)
if (stack.size() < 2)
return set_error(serror, SCRIPT_ERR_INVALID_STACK_OPERATION);
int n = CScriptNum(stacktop(-1), fRequireMinimal).getint();
popstack(stack);
if (n < 0 || n >= (int)stack.size())
return set_error(serror, SCRIPT_ERR_INVALID_STACK_OPERATION);
valtype vch = stacktop(-n-1);
if (opcode == OP_ROLL)
stack.erase(stack.end()-n-1);
stack.push_back(vch);
}
break;
case OP_ROT:
{
// (x1 x2 x3 -- x2 x3 x1)
// x2 x1 x3 after first swap
// x2 x3 x1 after second swap
if (stack.size() < 3)
return set_error(serror, SCRIPT_ERR_INVALID_STACK_OPERATION);
swap(stacktop(-3), stacktop(-2));
swap(stacktop(-2), stacktop(-1));
}
break;
case OP_SWAP:
{
// (x1 x2 -- x2 x1)
if (stack.size() < 2)
return set_error(serror, SCRIPT_ERR_INVALID_STACK_OPERATION);
swap(stacktop(-2), stacktop(-1));
}
break;
case OP_TUCK:
{
// (x1 x2 -- x2 x1 x2)
if (stack.size() < 2)
return set_error(serror, SCRIPT_ERR_INVALID_STACK_OPERATION);
valtype vch = stacktop(-1);
stack.insert(stack.end()-2, vch);
}
break;
case OP_SIZE:
{
// (in -- in size)
if (stack.size() < 1)
return set_error(serror, SCRIPT_ERR_INVALID_STACK_OPERATION);
CScriptNum bn(stacktop(-1).size());
stack.push_back(bn.getvch());
}
break;
//
// Bitwise logic
//
case OP_EQUAL:
case OP_EQUALVERIFY:
//case OP_NOTEQUAL: // use OP_NUMNOTEQUAL
{
// (x1 x2 - bool)
if (stack.size() < 2)
return set_error(serror, SCRIPT_ERR_INVALID_STACK_OPERATION);
valtype& vch1 = stacktop(-2);
valtype& vch2 = stacktop(-1);
bool fEqual = (vch1 == vch2);
// OP_NOTEQUAL is disabled because it would be too easy to say
// something like n != 1 and have some wiseguy pass in 1 with extra
// zero bytes after it (numerically, 0x01 == 0x0001 == 0x000001)
//if (opcode == OP_NOTEQUAL)
// fEqual = !fEqual;
popstack(stack);
popstack(stack);
stack.push_back(fEqual ? vchTrue : vchFalse);
if (opcode == OP_EQUALVERIFY)
{
if (fEqual)
popstack(stack);
else
return set_error(serror, SCRIPT_ERR_EQUALVERIFY);
}
}
break;
//
// Numeric
//
case OP_1ADD:
case OP_1SUB:
case OP_NEGATE:
case OP_ABS:
case OP_NOT:
case OP_0NOTEQUAL:
{
// (in -- out)
if (stack.size() < 1)
return set_error(serror, SCRIPT_ERR_INVALID_STACK_OPERATION);
CScriptNum bn(stacktop(-1), fRequireMinimal);
switch (opcode)
{
case OP_1ADD: bn += bnOne; break;
case OP_1SUB: bn -= bnOne; break;
case OP_NEGATE: bn = -bn; break;
case OP_ABS: if (bn < bnZero) bn = -bn; break;
case OP_NOT: bn = (bn == bnZero); break;
case OP_0NOTEQUAL: bn = (bn != bnZero); break;
default: assert(!"invalid opcode"); break;
}
popstack(stack);
stack.push_back(bn.getvch());
}
break;
case OP_ADD:
case OP_SUB:
case OP_BOOLAND:
case OP_BOOLOR:
case OP_NUMEQUAL:
case OP_NUMEQUALVERIFY:
case OP_NUMNOTEQUAL:
case OP_LESSTHAN:
case OP_GREATERTHAN:
case OP_LESSTHANOREQUAL:
case OP_GREATERTHANOREQUAL:
case OP_MIN:
case OP_MAX:
{
// (x1 x2 -- out)
if (stack.size() < 2)
return set_error(serror, SCRIPT_ERR_INVALID_STACK_OPERATION);
CScriptNum bn1(stacktop(-2), fRequireMinimal);
CScriptNum bn2(stacktop(-1), fRequireMinimal);
CScriptNum bn(0);
switch (opcode)
{
case OP_ADD:
bn = bn1 + bn2;
break;
case OP_SUB:
bn = bn1 - bn2;
break;
case OP_BOOLAND: bn = (bn1 != bnZero && bn2 != bnZero); break;
case OP_BOOLOR: bn = (bn1 != bnZero || bn2 != bnZero); break;
case OP_NUMEQUAL: bn = (bn1 == bn2); break;
case OP_NUMEQUALVERIFY: bn = (bn1 == bn2); break;
case OP_NUMNOTEQUAL: bn = (bn1 != bn2); break;
case OP_LESSTHAN: bn = (bn1 < bn2); break;
case OP_GREATERTHAN: bn = (bn1 > bn2); break;
case OP_LESSTHANOREQUAL: bn = (bn1 <= bn2); break;
case OP_GREATERTHANOREQUAL: bn = (bn1 >= bn2); break;
case OP_MIN: bn = (bn1 < bn2 ? bn1 : bn2); break;
case OP_MAX: bn = (bn1 > bn2 ? bn1 : bn2); break;
default: assert(!"invalid opcode"); break;
}
popstack(stack);
popstack(stack);
stack.push_back(bn.getvch());
if (opcode == OP_NUMEQUALVERIFY)
{
if (CastToBool(stacktop(-1)))
popstack(stack);
else
return set_error(serror, SCRIPT_ERR_NUMEQUALVERIFY);
}
}
break;
case OP_WITHIN:
{
// (x min max -- out)
if (stack.size() < 3)
return set_error(serror, SCRIPT_ERR_INVALID_STACK_OPERATION);
CScriptNum bn1(stacktop(-3), fRequireMinimal);
CScriptNum bn2(stacktop(-2), fRequireMinimal);
CScriptNum bn3(stacktop(-1), fRequireMinimal);
bool fValue = (bn2 <= bn1 && bn1 < bn3);
popstack(stack);
popstack(stack);
popstack(stack);
stack.push_back(fValue ? vchTrue : vchFalse);
}
break;
//
// Crypto
//
case OP_RIPEMD160:
case OP_SHA1:
case OP_SHA256:
case OP_HASH160:
case OP_HASH256:
{
// (in -- hash)
if (stack.size() < 1)
return set_error(serror, SCRIPT_ERR_INVALID_STACK_OPERATION);
valtype& vch = stacktop(-1);
valtype vchHash((opcode == OP_RIPEMD160 || opcode == OP_SHA1 || opcode == OP_HASH160) ? 20 : 32);
if (opcode == OP_RIPEMD160)
CRIPEMD160().Write(vch.data(), vch.size()).Finalize(vchHash.data());
else if (opcode == OP_SHA1)
CSHA1().Write(vch.data(), vch.size()).Finalize(vchHash.data());
else if (opcode == OP_SHA256)
CSHA256().Write(vch.data(), vch.size()).Finalize(vchHash.data());
else if (opcode == OP_HASH160)
CHash160().Write(vch.data(), vch.size()).Finalize(vchHash.data());
else if (opcode == OP_HASH256)
CHash256().Write(vch.data(), vch.size()).Finalize(vchHash.data());
popstack(stack);
stack.push_back(vchHash);
}
break;
case OP_CODESEPARATOR:
{
// If SCRIPT_VERIFY_CONST_SCRIPTCODE flag is set, use of OP_CODESEPARATOR is rejected in pre-segwit
// script, even in an unexecuted branch (this is checked above the opcode case statement).
// Hash starts after the code separator
pbegincodehash = pc;
}
break;
case OP_CHECKSIG:
case OP_CHECKSIGVERIFY:
{
// (sig pubkey -- bool)
if (stack.size() < 2)
return set_error(serror, SCRIPT_ERR_INVALID_STACK_OPERATION);
valtype& vchSig = stacktop(-2);
valtype& vchPubKey = stacktop(-1);
// Subset of script starting at the most recent codeseparator
CScript scriptCode(pbegincodehash, pend);
// Drop the signature in pre-segwit scripts but not segwit scripts
if (sigversion == SigVersion::BASE) {
int found = FindAndDelete(scriptCode, CScript(vchSig));
if (found > 0 && (flags & SCRIPT_VERIFY_CONST_SCRIPTCODE))
return set_error(serror, SCRIPT_ERR_SIG_FINDANDDELETE);
}
if (!CheckSignatureEncoding(vchSig, flags, serror) || !CheckPubKeyEncoding(vchPubKey, flags, sigversion, serror)) {
//serror is set
return false;
}
bool fSuccess = checker.CheckSig(vchSig, vchPubKey, scriptCode, sigversion);
if (!fSuccess && (flags & SCRIPT_VERIFY_NULLFAIL) && vchSig.size())
return set_error(serror, SCRIPT_ERR_SIG_NULLFAIL);
popstack(stack);
popstack(stack);
stack.push_back(fSuccess ? vchTrue : vchFalse);
if (opcode == OP_CHECKSIGVERIFY)
{
if (fSuccess)
popstack(stack);
else
return set_error(serror, SCRIPT_ERR_CHECKSIGVERIFY);
}
}
break;
case OP_CHECKMULTISIG:
case OP_CHECKMULTISIGVERIFY:
{
// ([sig ...] num_of_signatures [pubkey ...] num_of_pubkeys -- bool)
int i = 1;
if ((int)stack.size() < i)
return set_error(serror, SCRIPT_ERR_INVALID_STACK_OPERATION);
int nKeysCount = CScriptNum(stacktop(-i), fRequireMinimal).getint();
if (nKeysCount < 0 || nKeysCount > MAX_PUBKEYS_PER_MULTISIG)
return set_error(serror, SCRIPT_ERR_PUBKEY_COUNT);
nOpCount += nKeysCount;
if (nOpCount > MAX_OPS_PER_SCRIPT)
return set_error(serror, SCRIPT_ERR_OP_COUNT);
int ikey = ++i;
// ikey2 is the position of last non-signature item in the stack. Top stack item = 1.
// With SCRIPT_VERIFY_NULLFAIL, this is used for cleanup if operation fails.
int ikey2 = nKeysCount + 2;
i += nKeysCount;
if ((int)stack.size() < i)
return set_error(serror, SCRIPT_ERR_INVALID_STACK_OPERATION);
int nSigsCount = CScriptNum(stacktop(-i), fRequireMinimal).getint();
if (nSigsCount < 0 || nSigsCount > nKeysCount)
return set_error(serror, SCRIPT_ERR_SIG_COUNT);
int isig = ++i;
i += nSigsCount;
if ((int)stack.size() < i)
return set_error(serror, SCRIPT_ERR_INVALID_STACK_OPERATION);
// Subset of script starting at the most recent codeseparator
CScript scriptCode(pbegincodehash, pend);
// Drop the signature in pre-segwit scripts but not segwit scripts
for (int k = 0; k < nSigsCount; k++)
{
valtype& vchSig = stacktop(-isig-k);
if (sigversion == SigVersion::BASE) {
int found = FindAndDelete(scriptCode, CScript(vchSig));
if (found > 0 && (flags & SCRIPT_VERIFY_CONST_SCRIPTCODE))
return set_error(serror, SCRIPT_ERR_SIG_FINDANDDELETE);
}
}
bool fSuccess = true;
while (fSuccess && nSigsCount > 0)
{
valtype& vchSig = stacktop(-isig);
valtype& vchPubKey = stacktop(-ikey);
// Note how this makes the exact order of pubkey/signature evaluation
// distinguishable by CHECKMULTISIG NOT if the STRICTENC flag is set.
// See the script_(in)valid tests for details.
if (!CheckSignatureEncoding(vchSig, flags, serror) || !CheckPubKeyEncoding(vchPubKey, flags, sigversion, serror)) {
// serror is set
return false;
}
// Check signature
bool fOk = checker.CheckSig(vchSig, vchPubKey, scriptCode, sigversion);
if (fOk) {
isig++;
nSigsCount--;
}
ikey++;
nKeysCount--;
// If there are more signatures left than keys left,
// then too many signatures have failed. Exit early,
// without checking any further signatures.
if (nSigsCount > nKeysCount)
fSuccess = false;
}
// Clean up stack of actual arguments
while (i-- > 1) {
// If the operation failed, we require that all signatures must be empty vector
if (!fSuccess && (flags & SCRIPT_VERIFY_NULLFAIL) && !ikey2 && stacktop(-1).size())
return set_error(serror, SCRIPT_ERR_SIG_NULLFAIL);
if (ikey2 > 0)
ikey2--;
popstack(stack);
}
// A bug causes CHECKMULTISIG to consume one extra argument
// whose contents were not checked in any way.
//
// Unfortunately this is a potential source of mutability,
// so optionally verify it is exactly equal to zero prior
// to removing it from the stack.
if (stack.size() < 1)
return set_error(serror, SCRIPT_ERR_INVALID_STACK_OPERATION);
if ((flags & SCRIPT_VERIFY_NULLDUMMY) && stacktop(-1).size())
return set_error(serror, SCRIPT_ERR_SIG_NULLDUMMY);
popstack(stack);
stack.push_back(fSuccess ? vchTrue : vchFalse);
if (opcode == OP_CHECKMULTISIGVERIFY)
{
if (fSuccess)
popstack(stack);
else
return set_error(serror, SCRIPT_ERR_CHECKMULTISIGVERIFY);
}
}
break;
default:
return set_error(serror, SCRIPT_ERR_BAD_OPCODE);
}
// Size limits
if (stack.size() + altstack.size() > MAX_STACK_SIZE)
return set_error(serror, SCRIPT_ERR_STACK_SIZE);
}
}
catch (...)
{
return set_error(serror, SCRIPT_ERR_UNKNOWN_ERROR);
}
if (!vfExec.empty())
return set_error(serror, SCRIPT_ERR_UNBALANCED_CONDITIONAL);
return set_success(serror);
}
namespace {
/**
* Wrapper that serializes like CTransaction, but with the modifications
* required for the signature hash done in-place
*/
template <class T>
class CTransactionSignatureSerializer
{
private:
const T& txTo; //!< reference to the spending transaction (the one being serialized)
const CScript& scriptCode; //!< output script being consumed
const unsigned int nIn; //!< input index of txTo being signed
const bool fAnyoneCanPay; //!< whether the hashtype has the SIGHASH_ANYONECANPAY flag set
const bool fHashSingle; //!< whether the hashtype is SIGHASH_SINGLE
const bool fHashNone; //!< whether the hashtype is SIGHASH_NONE
public:
CTransactionSignatureSerializer(const T& txToIn, const CScript& scriptCodeIn, unsigned int nInIn, int nHashTypeIn) :
txTo(txToIn), scriptCode(scriptCodeIn), nIn(nInIn),
fAnyoneCanPay(!!(nHashTypeIn & SIGHASH_ANYONECANPAY)),
fHashSingle((nHashTypeIn & 0x1f) == SIGHASH_SINGLE),
fHashNone((nHashTypeIn & 0x1f) == SIGHASH_NONE) {}
/** Serialize the passed scriptCode, skipping OP_CODESEPARATORs */
template<typename S>
void SerializeScriptCode(S &s) const {
CScript::const_iterator it = scriptCode.begin();
CScript::const_iterator itBegin = it;
opcodetype opcode;
unsigned int nCodeSeparators = 0;
while (scriptCode.GetOp(it, opcode)) {
if (opcode == OP_CODESEPARATOR)
nCodeSeparators++;
}
::WriteCompactSize(s, scriptCode.size() - nCodeSeparators);
it = itBegin;
while (scriptCode.GetOp(it, opcode)) {
if (opcode == OP_CODESEPARATOR) {
s.write((char*)&itBegin[0], it-itBegin-1);
itBegin = it;
}
}
if (itBegin != scriptCode.end())
s.write((char*)&itBegin[0], it-itBegin);
}
/** Serialize an input of txTo */
template<typename S>
void SerializeInput(S &s, unsigned int nInput) const {
// In case of SIGHASH_ANYONECANPAY, only the input being signed is serialized
if (fAnyoneCanPay)
nInput = nIn;
// Serialize the prevout
::Serialize(s, txTo.vin[nInput].prevout);
// Serialize the script
if (nInput != nIn)
// Blank out other inputs' signatures
::Serialize(s, CScript());
else
SerializeScriptCode(s);
// Serialize the nSequence
if (nInput != nIn && (fHashSingle || fHashNone))
// let the others update at will
::Serialize(s, (int)0);
else
::Serialize(s, txTo.vin[nInput].nSequence);
}
/** Serialize an output of txTo */
template<typename S>
void SerializeOutput(S &s, unsigned int nOutput) const {
if (fHashSingle && nOutput != nIn)
// Do not lock-in the txout payee at other indices as txin
::Serialize(s, CTxOut());
else
::Serialize(s, txTo.vout[nOutput]);
}
/** Serialize txTo */
template<typename S>
void Serialize(S &s) const {
// Serialize nVersion
::Serialize(s, txTo.nVersion);
// Serialize vin
unsigned int nInputs = fAnyoneCanPay ? 1 : txTo.vin.size();
::WriteCompactSize(s, nInputs);
for (unsigned int nInput = 0; nInput < nInputs; nInput++)
SerializeInput(s, nInput);
// Serialize vout
unsigned int nOutputs = fHashNone ? 0 : (fHashSingle ? nIn+1 : txTo.vout.size());
::WriteCompactSize(s, nOutputs);
for (unsigned int nOutput = 0; nOutput < nOutputs; nOutput++)
SerializeOutput(s, nOutput);
// Serialize nLockTime
::Serialize(s, txTo.nLockTime);
}
};
template <class T>
uint256 GetPrevoutHash(const T& txTo)
{
CHashWriter ss(SER_GETHASH, 0);
for (const auto& txin : txTo.vin) {
ss << txin.prevout;
}
return ss.GetHash();
}
template <class T>
uint256 GetSequenceHash(const T& txTo)
{
CHashWriter ss(SER_GETHASH, 0);
for (const auto& txin : txTo.vin) {
ss << txin.nSequence;
}
return ss.GetHash();
}
template <class T>
uint256 GetOutputsHash(const T& txTo)
{
CHashWriter ss(SER_GETHASH, 0);
for (const auto& txout : txTo.vout) {
ss << txout;
}
return ss.GetHash();
}
} // namespace
template <class T>
PrecomputedTransactionData::PrecomputedTransactionData(const T& txTo)
{
// Cache is calculated only for transactions with witness
if (txTo.HasWitness()) {
hashPrevouts = GetPrevoutHash(txTo);
hashSequence = GetSequenceHash(txTo);
hashOutputs = GetOutputsHash(txTo);
ready = true;
}
}
// explicit instantiation
template PrecomputedTransactionData::PrecomputedTransactionData(const CTransaction& txTo);
template PrecomputedTransactionData::PrecomputedTransactionData(const CMutableTransaction& txTo);
template <class T>
uint256 SignatureHash(const CScript& scriptCode, const T& txTo, unsigned int nIn, int nHashType, const CAmount& amount, SigVersion sigversion, const PrecomputedTransactionData* cache)
{
assert(nIn < txTo.vin.size());
if (sigversion == SigVersion::WITNESS_V0) {
uint256 hashPrevouts;
uint256 hashSequence;
uint256 hashOutputs;
const bool cacheready = cache && cache->ready;
if (!(nHashType & SIGHASH_ANYONECANPAY)) {
hashPrevouts = cacheready ? cache->hashPrevouts : GetPrevoutHash(txTo);
}
if (!(nHashType & SIGHASH_ANYONECANPAY) && (nHashType & 0x1f) != SIGHASH_SINGLE && (nHashType & 0x1f) != SIGHASH_NONE) {
hashSequence = cacheready ? cache->hashSequence : GetSequenceHash(txTo);
}
if ((nHashType & 0x1f) != SIGHASH_SINGLE && (nHashType & 0x1f) != SIGHASH_NONE) {
hashOutputs = cacheready ? cache->hashOutputs : GetOutputsHash(txTo);
} else if ((nHashType & 0x1f) == SIGHASH_SINGLE && nIn < txTo.vout.size()) {
CHashWriter ss(SER_GETHASH, 0);
ss << txTo.vout[nIn];
hashOutputs = ss.GetHash();
}
CHashWriter ss(SER_GETHASH, 0);
// Version
ss << txTo.nVersion;
// Input prevouts/nSequence (none/all, depending on flags)
ss << hashPrevouts;
ss << hashSequence;
// The input being signed (replacing the scriptSig with scriptCode + amount)
// The prevout may already be contained in hashPrevout, and the nSequence
// may already be contain in hashSequence.
ss << txTo.vin[nIn].prevout;
ss << scriptCode;
ss << amount;
ss << txTo.vin[nIn].nSequence;
// Outputs (none/one/all, depending on flags)
ss << hashOutputs;
// Locktime
ss << txTo.nLockTime;
// Sighash type
ss << nHashType;
return ss.GetHash();
}
static const uint256 one(uint256S("0000000000000000000000000000000000000000000000000000000000000001"));
// Check for invalid use of SIGHASH_SINGLE
if ((nHashType & 0x1f) == SIGHASH_SINGLE) {
if (nIn >= txTo.vout.size()) {
// nOut out of range
return one;
}
}
// Wrapper to serialize only the necessary parts of the transaction being signed
CTransactionSignatureSerializer<T> txTmp(txTo, scriptCode, nIn, nHashType);
// Serialize and hash
CHashWriter ss(SER_GETHASH, 0);
ss << txTmp << nHashType;
return ss.GetHash();
}
template <class T>
bool GenericTransactionSignatureChecker<T>::VerifySignature(const std::vector<unsigned char>& vchSig, const CPubKey& pubkey, const uint256& sighash) const
{
return pubkey.Verify(sighash, vchSig);
}
template <class T>
bool GenericTransactionSignatureChecker<T>::CheckSig(const std::vector<unsigned char>& vchSigIn, const std::vector<unsigned char>& vchPubKey, const CScript& scriptCode, SigVersion sigversion) const
{
CPubKey pubkey(vchPubKey);
if (!pubkey.IsValid())
return false;
// Hash type is one byte tacked on to the end of the signature
std::vector<unsigned char> vchSig(vchSigIn);
if (vchSig.empty())
return false;
int nHashType = vchSig.back();
vchSig.pop_back();
uint256 sighash = SignatureHash(scriptCode, *txTo, nIn, nHashType, amount, sigversion, this->txdata);
if (!VerifySignature(vchSig, pubkey, sighash))
return false;
return true;
}
template <class T>
bool GenericTransactionSignatureChecker<T>::CheckLockTime(const CScriptNum& nLockTime) const
{
// There are two kinds of nLockTime: lock-by-blockheight
// and lock-by-blocktime, distinguished by whether
// nLockTime < LOCKTIME_THRESHOLD.
//
// We want to compare apples to apples, so fail the script
// unless the type of nLockTime being tested is the same as
// the nLockTime in the transaction.
if (!(
(txTo->nLockTime < LOCKTIME_THRESHOLD && nLockTime < LOCKTIME_THRESHOLD) ||
(txTo->nLockTime >= LOCKTIME_THRESHOLD && nLockTime >= LOCKTIME_THRESHOLD)
))
return false;
// Now that we know we're comparing apples-to-apples, the
// comparison is a simple numeric one.
if (nLockTime > (int64_t)txTo->nLockTime)
return false;
// Finally the nLockTime feature can be disabled and thus
// CHECKLOCKTIMEVERIFY bypassed if every txin has been
// finalized by setting nSequence to maxint. The
// transaction would be allowed into the blockchain, making
// the opcode ineffective.
//
// Testing if this vin is not final is sufficient to
// prevent this condition. Alternatively we could test all
// inputs, but testing just this input minimizes the data
// required to prove correct CHECKLOCKTIMEVERIFY execution.
if (CTxIn::SEQUENCE_FINAL == txTo->vin[nIn].nSequence)
return false;
return true;
}
template <class T>
bool GenericTransactionSignatureChecker<T>::CheckSequence(const CScriptNum& nSequence) const
{
// Relative lock times are supported by comparing the passed
// in operand to the sequence number of the input.
const int64_t txToSequence = (int64_t)txTo->vin[nIn].nSequence;
// Fail if the transaction's version number is not set high
// enough to trigger BIP 68 rules.
if (static_cast<uint32_t>(txTo->nVersion) < 2)
return false;
// Sequence numbers with their most significant bit set are not
// consensus constrained. Testing that the transaction's sequence
// number do not have this bit set prevents using this property
// to get around a CHECKSEQUENCEVERIFY check.
if (txToSequence & CTxIn::SEQUENCE_LOCKTIME_DISABLE_FLAG)
return false;
// Mask off any bits that do not have consensus-enforced meaning
// before doing the integer comparisons
const uint32_t nLockTimeMask = CTxIn::SEQUENCE_LOCKTIME_TYPE_FLAG | CTxIn::SEQUENCE_LOCKTIME_MASK;
const int64_t txToSequenceMasked = txToSequence & nLockTimeMask;
const CScriptNum nSequenceMasked = nSequence & nLockTimeMask;
// There are two kinds of nSequence: lock-by-blockheight
// and lock-by-blocktime, distinguished by whether
// nSequenceMasked < CTxIn::SEQUENCE_LOCKTIME_TYPE_FLAG.
//
// We want to compare apples to apples, so fail the script
// unless the type of nSequenceMasked being tested is the same as
// the nSequenceMasked in the transaction.
if (!(
(txToSequenceMasked < CTxIn::SEQUENCE_LOCKTIME_TYPE_FLAG && nSequenceMasked < CTxIn::SEQUENCE_LOCKTIME_TYPE_FLAG) ||
(txToSequenceMasked >= CTxIn::SEQUENCE_LOCKTIME_TYPE_FLAG && nSequenceMasked >= CTxIn::SEQUENCE_LOCKTIME_TYPE_FLAG)
)) {
return false;
}
// Now that we know we're comparing apples-to-apples, the
// comparison is a simple numeric one.
if (nSequenceMasked > txToSequenceMasked)
return false;
return true;
}
// explicit instantiation
template class GenericTransactionSignatureChecker<CTransaction>;
template class GenericTransactionSignatureChecker<CMutableTransaction>;
static bool VerifyWitnessProgram(const CScriptWitness& witness, int witversion, const std::vector<unsigned char>& program, unsigned int flags, const BaseSignatureChecker& checker, ScriptError* serror)
{
std::vector<std::vector<unsigned char> > stack;
CScript scriptPubKey;
if (witversion == 0) {
if (program.size() == WITNESS_V0_SCRIPTHASH_SIZE) {
// Version 0 segregated witness program: SHA256(CScript) inside the program, CScript + inputs in witness
if (witness.stack.size() == 0) {
return set_error(serror, SCRIPT_ERR_WITNESS_PROGRAM_WITNESS_EMPTY);
}
scriptPubKey = CScript(witness.stack.back().begin(), witness.stack.back().end());
stack = std::vector<std::vector<unsigned char> >(witness.stack.begin(), witness.stack.end() - 1);
uint256 hashScriptPubKey;
CSHA256().Write(&scriptPubKey[0], scriptPubKey.size()).Finalize(hashScriptPubKey.begin());
if (memcmp(hashScriptPubKey.begin(), program.data(), 32)) {
return set_error(serror, SCRIPT_ERR_WITNESS_PROGRAM_MISMATCH);
}
} else if (program.size() == WITNESS_V0_KEYHASH_SIZE) {
// Special case for pay-to-pubkeyhash; signature + pubkey in witness
if (witness.stack.size() != 2) {
return set_error(serror, SCRIPT_ERR_WITNESS_PROGRAM_MISMATCH); // 2 items in witness
}
scriptPubKey << OP_DUP << OP_HASH160 << program << OP_EQUALVERIFY << OP_CHECKSIG;
stack = witness.stack;
} else {
return set_error(serror, SCRIPT_ERR_WITNESS_PROGRAM_WRONG_LENGTH);
}
} else if (flags & SCRIPT_VERIFY_DISCOURAGE_UPGRADABLE_WITNESS_PROGRAM) {
return set_error(serror, SCRIPT_ERR_DISCOURAGE_UPGRADABLE_WITNESS_PROGRAM);
} else {
// Higher version witness scripts return true for future softfork compatibility
return set_success(serror);
}
// Disallow stack item size > MAX_SCRIPT_ELEMENT_SIZE in witness stack
for (unsigned int i = 0; i < stack.size(); i++) {
if (stack.at(i).size() > MAX_SCRIPT_ELEMENT_SIZE)
return set_error(serror, SCRIPT_ERR_PUSH_SIZE);
}
if (!EvalScript(stack, scriptPubKey, flags, checker, SigVersion::WITNESS_V0, serror)) {
return false;
}
// Scripts inside witness implicitly require cleanstack behaviour
if (stack.size() != 1)
return set_error(serror, SCRIPT_ERR_CLEANSTACK);
if (!CastToBool(stack.back()))
return set_error(serror, SCRIPT_ERR_EVAL_FALSE);
return true;
}
bool VerifyScript(const CScript& scriptSig, const CScript& scriptPubKey, const CScriptWitness* witness, unsigned int flags, const BaseSignatureChecker& checker, ScriptError* serror)
{
static const CScriptWitness emptyWitness;
if (witness == nullptr) {
witness = &emptyWitness;
}
bool hadWitness = false;
set_error(serror, SCRIPT_ERR_UNKNOWN_ERROR);
if ((flags & SCRIPT_VERIFY_SIGPUSHONLY) != 0 && !scriptSig.IsPushOnly()) {
return set_error(serror, SCRIPT_ERR_SIG_PUSHONLY);
}
std::vector<std::vector<unsigned char> > stack, stackCopy;
if (!EvalScript(stack, scriptSig, flags, checker, SigVersion::BASE, serror))
// serror is set
return false;
if (flags & SCRIPT_VERIFY_P2SH)
stackCopy = stack;
if (!EvalScript(stack, scriptPubKey, flags, checker, SigVersion::BASE, serror))
// serror is set
return false;
if (stack.empty())
return set_error(serror, SCRIPT_ERR_EVAL_FALSE);
if (CastToBool(stack.back()) == false)
return set_error(serror, SCRIPT_ERR_EVAL_FALSE);
// Bare witness programs
int witnessversion;
std::vector<unsigned char> witnessprogram;
if (flags & SCRIPT_VERIFY_WITNESS) {
if (scriptPubKey.IsWitnessProgram(witnessversion, witnessprogram)) {
hadWitness = true;
if (scriptSig.size() != 0) {
// The scriptSig must be _exactly_ CScript(), otherwise we reintroduce malleability.
return set_error(serror, SCRIPT_ERR_WITNESS_MALLEATED);
}
if (!VerifyWitnessProgram(*witness, witnessversion, witnessprogram, flags, checker, serror)) {
return false;
}
// Bypass the cleanstack check at the end. The actual stack is obviously not clean
// for witness programs.
stack.resize(1);
}
}
// Additional validation for spend-to-script-hash transactions:
if ((flags & SCRIPT_VERIFY_P2SH) && scriptPubKey.IsPayToScriptHash())
{
// scriptSig must be literals-only or validation fails
if (!scriptSig.IsPushOnly())
return set_error(serror, SCRIPT_ERR_SIG_PUSHONLY);
// Restore stack.
swap(stack, stackCopy);
// stack cannot be empty here, because if it was the
// P2SH HASH <> EQUAL scriptPubKey would be evaluated with
// an empty stack and the EvalScript above would return false.
assert(!stack.empty());
const valtype& pubKeySerialized = stack.back();
CScript pubKey2(pubKeySerialized.begin(), pubKeySerialized.end());
popstack(stack);
if (!EvalScript(stack, pubKey2, flags, checker, SigVersion::BASE, serror))
// serror is set
return false;
if (stack.empty())
return set_error(serror, SCRIPT_ERR_EVAL_FALSE);
if (!CastToBool(stack.back()))
return set_error(serror, SCRIPT_ERR_EVAL_FALSE);
// P2SH witness program
if (flags & SCRIPT_VERIFY_WITNESS) {
if (pubKey2.IsWitnessProgram(witnessversion, witnessprogram)) {
hadWitness = true;
if (scriptSig != CScript() << std::vector<unsigned char>(pubKey2.begin(), pubKey2.end())) {
// The scriptSig must be _exactly_ a single push of the redeemScript. Otherwise we
// reintroduce malleability.
return set_error(serror, SCRIPT_ERR_WITNESS_MALLEATED_P2SH);
}
if (!VerifyWitnessProgram(*witness, witnessversion, witnessprogram, flags, checker, serror)) {
return false;
}
// Bypass the cleanstack check at the end. The actual stack is obviously not clean
// for witness programs.
stack.resize(1);
}
}
}
// The CLEANSTACK check is only performed after potential P2SH evaluation,
// as the non-P2SH evaluation of a P2SH script will obviously not result in
// a clean stack (the P2SH inputs remain). The same holds for witness evaluation.
if ((flags & SCRIPT_VERIFY_CLEANSTACK) != 0) {
// Disallow CLEANSTACK without P2SH, as otherwise a switch CLEANSTACK->P2SH+CLEANSTACK
// would be possible, which is not a softfork (and P2SH should be one).
assert((flags & SCRIPT_VERIFY_P2SH) != 0);
assert((flags & SCRIPT_VERIFY_WITNESS) != 0);
if (stack.size() != 1) {
return set_error(serror, SCRIPT_ERR_CLEANSTACK);
}
}
if (flags & SCRIPT_VERIFY_WITNESS) {
// We can't check for correct unexpected witness data if P2SH was off, so require
// that WITNESS implies P2SH. Otherwise, going from WITNESS->P2SH+WITNESS would be
// possible, which is not a softfork.
assert((flags & SCRIPT_VERIFY_P2SH) != 0);
if (!hadWitness && !witness->IsNull()) {
return set_error(serror, SCRIPT_ERR_WITNESS_UNEXPECTED);
}
}
return set_success(serror);
}
size_t static WitnessSigOps(int witversion, const std::vector<unsigned char>& witprogram, const CScriptWitness& witness)
{
if (witversion == 0) {
if (witprogram.size() == WITNESS_V0_KEYHASH_SIZE)
return 1;
if (witprogram.size() == WITNESS_V0_SCRIPTHASH_SIZE && witness.stack.size() > 0) {
CScript subscript(witness.stack.back().begin(), witness.stack.back().end());
return subscript.GetSigOpCount(true);
}
}
// Future flags may be implemented here.
return 0;
}
size_t CountWitnessSigOps(const CScript& scriptSig, const CScript& scriptPubKey, const CScriptWitness* witness, unsigned int flags)
{
static const CScriptWitness witnessEmpty;
if ((flags & SCRIPT_VERIFY_WITNESS) == 0) {
return 0;
}
assert((flags & SCRIPT_VERIFY_P2SH) != 0);
int witnessversion;
std::vector<unsigned char> witnessprogram;
if (scriptPubKey.IsWitnessProgram(witnessversion, witnessprogram)) {
return WitnessSigOps(witnessversion, witnessprogram, witness ? *witness : witnessEmpty);
}
if (scriptPubKey.IsPayToScriptHash() && scriptSig.IsPushOnly()) {
CScript::const_iterator pc = scriptSig.begin();
std::vector<unsigned char> data;
while (pc < scriptSig.end()) {
opcodetype opcode;
scriptSig.GetOp(pc, opcode, data);
}
CScript subscript(data.begin(), data.end());
if (subscript.IsWitnessProgram(witnessversion, witnessprogram)) {
return WitnessSigOps(witnessversion, witnessprogram, witness ? *witness : witnessEmpty);
}
}
return 0;
}
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