diff options
Diffstat (limited to 'src/script/interpreter.cpp')
| -rw-r--r-- | src/script/interpreter.cpp | 763 |
1 files changed, 602 insertions, 161 deletions
diff --git a/src/script/interpreter.cpp b/src/script/interpreter.cpp index 3231f2e74e..2cdff7ee57 100644 --- a/src/script/interpreter.cpp +++ b/src/script/interpreter.cpp @@ -1,22 +1,18 @@ // Copyright (c) 2009-2010 Satoshi Nakamoto -// Copyright (c) 2009-2014 The Bitcoin developers +// Copyright (c) 2009-2017 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 "interpreter.h" +#include <script/interpreter.h> -#include "primitives/transaction.h" -#include "crypto/ripemd160.h" -#include "crypto/sha1.h" -#include "crypto/sha256.h" -#include "eccryptoverify.h" -#include "pubkey.h" -#include "script/script.h" -#include "uint256.h" +#include <crypto/ripemd160.h> +#include <crypto/sha1.h> +#include <crypto/sha256.h> +#include <pubkey.h> +#include <script/script.h> +#include <uint256.h> -using namespace std; - -typedef vector<unsigned char> valtype; +typedef std::vector<unsigned char> valtype; namespace { @@ -34,7 +30,7 @@ inline bool set_error(ScriptError* ret, const ScriptError serror) return false; } -} // anon namespace +} // namespace bool CastToBool(const valtype& vch) { @@ -57,10 +53,10 @@ bool CastToBool(const valtype& vch) */ #define stacktop(i) (stack.at(stack.size()+(i))) #define altstacktop(i) (altstack.at(altstack.size()+(i))) -static inline void popstack(vector<valtype>& stack) +static inline void popstack(std::vector<valtype>& stack) { if (stack.empty()) - throw runtime_error("popstack() : stack empty"); + throw std::runtime_error("popstack(): stack empty"); stack.pop_back(); } @@ -80,8 +76,20 @@ bool static IsCompressedOrUncompressedPubKey(const valtype &vchPubKey) { return false; } } else { - // Non-canonical public key: neither compressed nor uncompressed - return false; + // 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; } @@ -93,87 +101,88 @@ bool static IsCompressedOrUncompressedPubKey(const valtype &vchPubKey) { * 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 IsDERSignature(const valtype &vchSig) { +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) - if (vchSig.size() < 9) { - // Non-canonical signature: too short - return false; - } - if (vchSig.size() > 73) { - // Non-canonical signature: too long - return false; - } - if (vchSig[0] != 0x30) { - // Non-canonical signature: wrong type - return false; - } - if (vchSig[1] != vchSig.size()-3) { - // Non-canonical signature: wrong length marker - return false; - } - unsigned int nLenR = vchSig[3]; - if (5 + nLenR >= vchSig.size()) { - // Non-canonical signature: S length misplaced - return false; - } - unsigned int nLenS = vchSig[5+nLenR]; - if ((unsigned long)(nLenR+nLenS+7) != vchSig.size()) { - // Non-canonical signature: R+S length mismatch - return false; - } + // Minimum and maximum size constraints. + if (sig.size() < 9) return false; + if (sig.size() > 73) return false; - const unsigned char *R = &vchSig[4]; - if (R[-2] != 0x02) { - // Non-canonical signature: R value type mismatch - return false; - } - if (nLenR == 0) { - // Non-canonical signature: R length is zero - return false; - } - if (R[0] & 0x80) { - // Non-canonical signature: R value negative - return false; - } - if (nLenR > 1 && (R[0] == 0x00) && !(R[1] & 0x80)) { - // Non-canonical signature: R value excessively padded - 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; - const unsigned char *S = &vchSig[6+nLenR]; - if (S[-2] != 0x02) { - // Non-canonical signature: S value type mismatch - return false; - } - if (nLenS == 0) { - // Non-canonical signature: S length is zero - return false; - } - if (S[0] & 0x80) { - // Non-canonical signature: S value negative - return false; - } - if (nLenS > 1 && (S[0] == 0x00) && !(S[1] & 0x80)) { - // Non-canonical signature: S value excessively padded - return false; - } return true; } bool static IsLowDERSignature(const valtype &vchSig, ScriptError* serror) { - if (!IsDERSignature(vchSig)) { + if (!IsValidSignatureEncoding(vchSig)) { return set_error(serror, SCRIPT_ERR_SIG_DER); } - unsigned int nLenR = vchSig[3]; - unsigned int nLenS = vchSig[5+nLenR]; - const unsigned char *S = &vchSig[6+nLenR]; + // 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 (!eccrypto::CheckSignatureElement(S, nLenS, true)) + if (!CPubKey::CheckLowS(vchSigCopy)) { return set_error(serror, SCRIPT_ERR_SIG_HIGH_S); - + } return true; } @@ -188,8 +197,13 @@ bool static IsDefinedHashtypeSignature(const valtype &vchSig) { return true; } -bool static CheckSignatureEncoding(const valtype &vchSig, unsigned int flags, ScriptError* serror) { - if ((flags & (SCRIPT_VERIFY_DERSIG | SCRIPT_VERIFY_LOW_S | SCRIPT_VERIFY_STRICTENC)) != 0 && !IsDERSignature(vchSig)) { +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 @@ -200,10 +214,14 @@ bool static CheckSignatureEncoding(const valtype &vchSig, unsigned int flags, Sc return true; } -bool static CheckPubKeyEncoding(const valtype &vchSig, unsigned int flags, ScriptError* serror) { - if ((flags & SCRIPT_VERIFY_STRICTENC) != 0 && !IsCompressedOrUncompressedPubKey(vchSig)) { +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; } @@ -230,14 +248,14 @@ bool static CheckMinimalPush(const valtype& data, opcodetype opcode) { return true; } -bool EvalScript(vector<vector<unsigned char> >& stack, const CScript& script, unsigned int flags, const BaseSignatureChecker& checker, ScriptError* serror) +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 CScriptNum bnFalse(0); + // static const CScriptNum bnTrue(1); static const valtype vchFalse(0); - static const valtype vchZero(0); + // static const valtype vchZero(0); static const valtype vchTrue(1, 1); CScript::const_iterator pc = script.begin(); @@ -245,10 +263,10 @@ bool EvalScript(vector<vector<unsigned char> >& stack, const CScript& script, un CScript::const_iterator pbegincodehash = script.begin(); opcodetype opcode; valtype vchPushValue; - vector<bool> vfExec; - vector<valtype> altstack; + std::vector<bool> vfExec; + std::vector<valtype> altstack; set_error(serror, SCRIPT_ERR_UNKNOWN_ERROR); - if (script.size() > 10000) + if (script.size() > MAX_SCRIPT_SIZE) return set_error(serror, SCRIPT_ERR_SCRIPT_SIZE); int nOpCount = 0; bool fRequireMinimal = (flags & SCRIPT_VERIFY_MINIMALDATA) != 0; @@ -268,7 +286,7 @@ bool EvalScript(vector<vector<unsigned char> >& stack, const CScript& script, un return set_error(serror, SCRIPT_ERR_PUSH_SIZE); // Note how OP_RESERVED does not count towards the opcode limit. - if (opcode > OP_16 && ++nOpCount > 201) + if (opcode > OP_16 && ++nOpCount > MAX_OPS_PER_SCRIPT) return set_error(serror, SCRIPT_ERR_OP_COUNT); if (opcode == OP_CAT || @@ -330,9 +348,82 @@ bool EvalScript(vector<vector<unsigned char> >& stack, const CScript& script, un // Control // case OP_NOP: - break; + 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; - case OP_NOP1: case OP_NOP2: case OP_NOP3: case OP_NOP4: case OP_NOP5: + // 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) @@ -350,6 +441,12 @@ bool EvalScript(vector<vector<unsigned char> >& stack, const CScript& script, un 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; @@ -756,15 +853,15 @@ bool EvalScript(vector<vector<unsigned char> >& stack, const CScript& script, un valtype& vch = stacktop(-1); valtype vchHash((opcode == OP_RIPEMD160 || opcode == OP_SHA1 || opcode == OP_HASH160) ? 20 : 32); if (opcode == OP_RIPEMD160) - CRIPEMD160().Write(begin_ptr(vch), vch.size()).Finalize(begin_ptr(vchHash)); + CRIPEMD160().Write(vch.data(), vch.size()).Finalize(vchHash.data()); else if (opcode == OP_SHA1) - CSHA1().Write(begin_ptr(vch), vch.size()).Finalize(begin_ptr(vchHash)); + CSHA1().Write(vch.data(), vch.size()).Finalize(vchHash.data()); else if (opcode == OP_SHA256) - CSHA256().Write(begin_ptr(vch), vch.size()).Finalize(begin_ptr(vchHash)); + CSHA256().Write(vch.data(), vch.size()).Finalize(vchHash.data()); else if (opcode == OP_HASH160) - CHash160().Write(begin_ptr(vch), vch.size()).Finalize(begin_ptr(vchHash)); + CHash160().Write(vch.data(), vch.size()).Finalize(vchHash.data()); else if (opcode == OP_HASH256) - CHash256().Write(begin_ptr(vch), vch.size()).Finalize(begin_ptr(vchHash)); + CHash256().Write(vch.data(), vch.size()).Finalize(vchHash.data()); popstack(stack); stack.push_back(vchHash); } @@ -790,14 +887,19 @@ bool EvalScript(vector<vector<unsigned char> >& stack, const CScript& script, un // Subset of script starting at the most recent codeseparator CScript scriptCode(pbegincodehash, pend); - // Drop the signature, since there's no way for a signature to sign itself - scriptCode.FindAndDelete(CScript(vchSig)); + // 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, serror)) { + if (!CheckSignatureEncoding(vchSig, flags, serror) || !CheckPubKeyEncoding(vchPubKey, flags, sigversion, serror)) { //serror is set return false; } - bool fSuccess = checker.CheckSig(vchSig, vchPubKey, scriptCode); + 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); @@ -822,12 +924,15 @@ bool EvalScript(vector<vector<unsigned char> >& stack, const CScript& script, un return set_error(serror, SCRIPT_ERR_INVALID_STACK_OPERATION); int nKeysCount = CScriptNum(stacktop(-i), fRequireMinimal).getint(); - if (nKeysCount < 0 || nKeysCount > 20) + if (nKeysCount < 0 || nKeysCount > MAX_PUBKEYS_PER_MULTISIG) return set_error(serror, SCRIPT_ERR_PUBKEY_COUNT); nOpCount += nKeysCount; - if (nOpCount > 201) + 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); @@ -843,11 +948,13 @@ bool EvalScript(vector<vector<unsigned char> >& stack, const CScript& script, un // Subset of script starting at the most recent codeseparator CScript scriptCode(pbegincodehash, pend); - // Drop the signatures, since there's no way for a signature to sign itself + // Drop the signature in pre-segwit scripts but not segwit scripts for (int k = 0; k < nSigsCount; k++) { valtype& vchSig = stacktop(-isig-k); - scriptCode.FindAndDelete(CScript(vchSig)); + if (sigversion == SIGVERSION_BASE) { + scriptCode.FindAndDelete(CScript(vchSig)); + } } bool fSuccess = true; @@ -859,13 +966,13 @@ bool EvalScript(vector<vector<unsigned char> >& stack, const CScript& script, un // 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, serror)) { + if (!CheckSignatureEncoding(vchSig, flags, serror) || !CheckPubKeyEncoding(vchPubKey, flags, sigversion, serror)) { // serror is set return false; } // Check signature - bool fOk = checker.CheckSig(vchSig, vchPubKey, scriptCode); + bool fOk = checker.CheckSig(vchSig, vchPubKey, scriptCode, sigversion); if (fOk) { isig++; @@ -882,8 +989,14 @@ bool EvalScript(vector<vector<unsigned char> >& stack, const CScript& script, un } // Clean up stack of actual arguments - while (i-- > 1) + 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. @@ -914,7 +1027,7 @@ bool EvalScript(vector<vector<unsigned char> >& stack, const CScript& script, un } // Size limits - if (stack.size() + altstack.size() > 1000) + if (stack.size() + altstack.size() > MAX_STACK_SIZE) return set_error(serror, SCRIPT_ERR_STACK_SIZE); } } @@ -937,12 +1050,12 @@ namespace { */ 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 + 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) : @@ -953,7 +1066,7 @@ public: /** Serialize the passed scriptCode, skipping OP_CODESEPARATORs */ template<typename S> - void SerializeScriptCode(S &s, int nType, int nVersion) const { + void SerializeScriptCode(S &s) const { CScript::const_iterator it = scriptCode.begin(); CScript::const_iterator itBegin = it; opcodetype opcode; @@ -976,70 +1089,150 @@ public: /** Serialize an input of txTo */ template<typename S> - void SerializeInput(S &s, unsigned int nInput, int nType, int nVersion) const { + 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, nType, nVersion); + ::Serialize(s, txTo.vin[nInput].prevout); // Serialize the script if (nInput != nIn) // Blank out other inputs' signatures - ::Serialize(s, CScript(), nType, nVersion); + ::Serialize(s, CScript()); else - SerializeScriptCode(s, nType, nVersion); + SerializeScriptCode(s); // Serialize the nSequence if (nInput != nIn && (fHashSingle || fHashNone)) // let the others update at will - ::Serialize(s, (int)0, nType, nVersion); + ::Serialize(s, (int)0); else - ::Serialize(s, txTo.vin[nInput].nSequence, nType, nVersion); + ::Serialize(s, txTo.vin[nInput].nSequence); } /** Serialize an output of txTo */ template<typename S> - void SerializeOutput(S &s, unsigned int nOutput, int nType, int nVersion) const { + 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(), nType, nVersion); + ::Serialize(s, CTxOut()); else - ::Serialize(s, txTo.vout[nOutput], nType, nVersion); + ::Serialize(s, txTo.vout[nOutput]); } /** Serialize txTo */ template<typename S> - void Serialize(S &s, int nType, int nVersion) const { + void Serialize(S &s) const { // Serialize nVersion - ::Serialize(s, txTo.nVersion, nType, 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, nType, nVersion); + 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, nType, nVersion); + SerializeOutput(s, nOutput); // Serialize nLockTime - ::Serialize(s, txTo.nLockTime, nType, nVersion); + ::Serialize(s, txTo.nLockTime); } }; -} // anon namespace +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 -uint256 SignatureHash(const CScript& scriptCode, const CTransaction& txTo, unsigned int nIn, int nHashType) +PrecomputedTransactionData::PrecomputedTransactionData(const CTransaction& txTo) { - if (nIn >= txTo.vin.size()) { - // nIn out of range - return 1; + // 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 1; + return one; } } @@ -1052,25 +1245,25 @@ uint256 SignatureHash(const CScript& scriptCode, const CTransaction& txTo, unsig return ss.GetHash(); } -bool SignatureChecker::VerifySignature(const std::vector<unsigned char>& vchSig, const CPubKey& pubkey, const uint256& sighash) const +bool TransactionSignatureChecker::VerifySignature(const std::vector<unsigned char>& vchSig, const CPubKey& pubkey, const uint256& sighash) const { return pubkey.Verify(sighash, vchSig); } -bool SignatureChecker::CheckSig(const vector<unsigned char>& vchSigIn, const vector<unsigned char>& vchPubKey, const CScript& scriptCode) const +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 - vector<unsigned char> vchSig(vchSigIn); + 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); + uint256 sighash = SignatureHash(scriptCode, *txTo, nIn, nHashType, amount, sigversion, this->txdata); if (!VerifySignature(vchSig, pubkey, sighash)) return false; @@ -1078,29 +1271,188 @@ bool SignatureChecker::CheckSig(const vector<unsigned char>& vchSigIn, const vec return true; } -bool VerifyScript(const CScript& scriptSig, const CScript& scriptPubKey, unsigned int flags, const BaseSignatureChecker& checker, ScriptError* serror) +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); } - vector<vector<unsigned char> > stack, stackCopy; - if (!EvalScript(stack, scriptSig, flags, checker, serror)) + 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, serror)) + 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()) { @@ -1108,25 +1460,114 @@ bool VerifyScript(const CScript& scriptSig, const CScript& scriptPubKey, unsigne if (!scriptSig.IsPushOnly()) return set_error(serror, SCRIPT_ERR_SIG_PUSHONLY); - // stackCopy cannot be empty here, because if it was the + // 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(!stackCopy.empty()); + assert(!stack.empty()); - const valtype& pubKeySerialized = stackCopy.back(); + const valtype& pubKeySerialized = stack.back(); CScript pubKey2(pubKeySerialized.begin(), pubKeySerialized.end()); - popstack(stackCopy); + popstack(stack); - if (!EvalScript(stackCopy, pubKey2, flags, checker, serror)) + if (!EvalScript(stack, pubKey2, flags, checker, SIGVERSION_BASE, serror)) // serror is set return false; - if (stackCopy.empty()) + if (stack.empty()) return set_error(serror, SCRIPT_ERR_EVAL_FALSE); - if (!CastToBool(stackCopy.back())) + if (!CastToBool(stack.back())) return set_error(serror, SCRIPT_ERR_EVAL_FALSE); - else - return set_success(serror); + + // 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; +} |