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Diffstat (limited to 'src/script/interpreter.cpp')
| -rw-r--r-- | src/script/interpreter.cpp | 1567 |
1 files changed, 1567 insertions, 0 deletions
diff --git a/src/script/interpreter.cpp b/src/script/interpreter.cpp new file mode 100644 index 0000000000..3c3f92fe46 --- /dev/null +++ b/src/script/interpreter.cpp @@ -0,0 +1,1567 @@ +// Copyright (c) 2009-2010 Satoshi Nakamoto +// Copyright (c) 2009-2016 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() < 33) { + // Non-canonical public key: too short + return false; + } + if (vchPubKey[0] == 0x04) { + if (vchPubKey.size() != 65) { + // Non-canonical public key: invalid length for uncompressed key + return false; + } + } else if (vchPubKey[0] == 0x02 || vchPubKey[0] == 0x03) { + if (vchPubKey.size() != 33) { + // 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() != 33) { + // 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 integers (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); + } + std::vector<unsigned char> vchSigCopy(vchSig.begin(), vchSig.begin() + vchSig.size() - 1); + 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) { + if (data.size() == 0) { + // Could have used OP_0. + return opcode == OP_0; + } else if (data.size() == 1 && data[0] >= 1 && data[0] <= 16) { + // Could have used OP_1 .. OP_16. + return opcode == OP_1 + (data[0] - 1); + } else if (data.size() == 1 && data[0] == 0x81) { + // Could have used OP_1NEGATE. + return opcode == OP_1NEGATE; + } else if (data.size() <= 75) { + // Could have used a direct push (opcode indicating number of bytes pushed + those bytes). + return opcode == data.size(); + } else if (data.size() <= 255) { + // Could have used OP_PUSHDATA. + return opcode == OP_PUSHDATA1; + } else if (data.size() <= 65535) { + // Could have used OP_PUSHDATA2. + return opcode == OP_PUSHDATA2; + } + return true; +} + +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. + + 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: + { + // 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) { + scriptCode.FindAndDelete(CScript(vchSig)); + } + + 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) { + scriptCode.FindAndDelete(CScript(vchSig)); + } + } + + 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 + */ +class CTransactionSignatureSerializer { +private: + const CTransaction& 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 CTransaction &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); + } +}; + +uint256 GetPrevoutHash(const CTransaction& txTo) { + CHashWriter ss(SER_GETHASH, 0); + for (const auto& txin : txTo.vin) { + ss << txin.prevout; + } + return ss.GetHash(); +} + +uint256 GetSequenceHash(const CTransaction& txTo) { + CHashWriter ss(SER_GETHASH, 0); + for (const auto& txin : txTo.vin) { + ss << txin.nSequence; + } + return ss.GetHash(); +} + +uint256 GetOutputsHash(const CTransaction& txTo) { + CHashWriter ss(SER_GETHASH, 0); + for (const auto& txout : txTo.vout) { + ss << txout; + } + return ss.GetHash(); +} + +} // namespace + +PrecomputedTransactionData::PrecomputedTransactionData(const CTransaction& txTo) +{ + // Cache is calculated only for transactions with witness + if (txTo.HasWitness()) { + hashPrevouts = GetPrevoutHash(txTo); + hashSequence = GetSequenceHash(txTo); + hashOutputs = GetOutputsHash(txTo); + ready = true; + } +} + +uint256 SignatureHash(const CScript& scriptCode, const CTransaction& 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 txTmp(txTo, scriptCode, nIn, nHashType); + + // Serialize and hash + CHashWriter ss(SER_GETHASH, 0); + ss << txTmp << nHashType; + return ss.GetHash(); +} + +bool TransactionSignatureChecker::VerifySignature(const std::vector<unsigned char>& vchSig, const CPubKey& pubkey, const uint256& sighash) const +{ + return pubkey.Verify(sighash, vchSig); +} + +bool TransactionSignatureChecker::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; +} + +bool TransactionSignatureChecker::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; +} + +bool TransactionSignatureChecker::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; +} + +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() == 32) { + // 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() == 20) { + // 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_EVAL_FALSE); + 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, int flags) +{ + if (witversion == 0) { + if (witprogram.size() == 20) + return 1; + + if (witprogram.size() == 32 && 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, flags); + } + + 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, flags); + } + } + + return 0; +} |