src/script/interpreter.h

   1 // Copyright (c) 2009-2010 Satoshi Nakamoto
   2 // Copyright (c) 2009-2016 The Bitcoin Core developers
   3 // Distributed under the MIT software license, see the accompanying
   4 // file COPYING or http://www.opensource.org/licenses/mit-license.php.
   5
   6 #ifndef BITCOIN_SCRIPT_INTERPRETER_H
   7 #define BITCOIN_SCRIPT_INTERPRETER_H
   8
   9 #include <script/script_error.h>
  10 #include <primitives/transaction.h>
  11
  12 #include <vector>
  13 #include <stdint.h>
  14 #include <string>
  15
  16 class CPubKey;
  17 class CScript;
  18 class CTransaction;
  19 class uint256;
  20
  21 /** Signature hash types/flags */
  22 enum
  23 {
  24     SIGHASH_ALL = 1,
  25     SIGHASH_NONE = 2,
  26     SIGHASH_SINGLE = 3,
  27     SIGHASH_ANYONECANPAY = 0x80,
  28 };
  29
  30 /** Script verification flags.
  31  *
  32  *  All flags are intended to be soft forks: the set of acceptable scripts under
  33  *  flags (A | B) is a subset of the acceptable scripts under flag (A).
  34  */
  35 enum
  36 {
  37     SCRIPT_VERIFY_NONE      = 0,
  38
  39     // Evaluate P2SH subscripts (BIP16).
  40     SCRIPT_VERIFY_P2SH      = (1U << 0),
  41
  42     // Passing a non-strict-DER signature or one with undefined hashtype to a checksig operation causes script failure.
  43     // Evaluating a pubkey that is not (0x04 + 64 bytes) or (0x02 or 0x03 + 32 bytes) by checksig causes script failure.
  44     // (not used or intended as a consensus rule).
  45     SCRIPT_VERIFY_STRICTENC = (1U << 1),
  46
  47     // Passing a non-strict-DER signature to a checksig operation causes script failure (BIP62 rule 1)
  48     SCRIPT_VERIFY_DERSIG    = (1U << 2),
  49
  50     // Passing a non-strict-DER signature or one with S > order/2 to a checksig operation causes script failure
  51     // (BIP62 rule 5).
  52     SCRIPT_VERIFY_LOW_S     = (1U << 3),
  53
  54     // verify dummy stack item consumed by CHECKMULTISIG is of zero-length (BIP62 rule 7).
  55     SCRIPT_VERIFY_NULLDUMMY = (1U << 4),
  56
  57     // Using a non-push operator in the scriptSig causes script failure (BIP62 rule 2).
  58     SCRIPT_VERIFY_SIGPUSHONLY = (1U << 5),
  59
  60     // Require minimal encodings for all push operations (OP_0... OP_16, OP_1NEGATE where possible, direct
  61     // pushes up to 75 bytes, OP_PUSHDATA up to 255 bytes, OP_PUSHDATA2 for anything larger). Evaluating
  62     // any other push causes the script to fail (BIP62 rule 3).
  63     // In addition, whenever a stack element is interpreted as a number, it must be of minimal length (BIP62 rule 4).
  64     SCRIPT_VERIFY_MINIMALDATA = (1U << 6),
  65
  66     // Discourage use of NOPs reserved for upgrades (NOP1-10)
  67     //
  68     // Provided so that nodes can avoid accepting or mining transactions
  69     // containing executed NOP's whose meaning may change after a soft-fork,
  70     // thus rendering the script invalid; with this flag set executing
  71     // discouraged NOPs fails the script. This verification flag will never be
  72     // a mandatory flag applied to scripts in a block. NOPs that are not
  73     // executed, e.g.  within an unexecuted IF ENDIF block, are *not* rejected.
  74     // NOPs that have associated forks to give them new meaning (CLTV, CSV)
  75     // are not subject to this rule.
  76     SCRIPT_VERIFY_DISCOURAGE_UPGRADABLE_NOPS  = (1U << 7),
  77
  78     // Require that only a single stack element remains after evaluation. This changes the success criterion from
  79     // "At least one stack element must remain, and when interpreted as a boolean, it must be true" to
  80     // "Exactly one stack element must remain, and when interpreted as a boolean, it must be true".
  81     // (BIP62 rule 6)
  82     // Note: CLEANSTACK should never be used without P2SH or WITNESS.
  83     SCRIPT_VERIFY_CLEANSTACK = (1U << 8),
  84
  85     // Verify CHECKLOCKTIMEVERIFY
  86     //
  87     // See BIP65 for details.
  88     SCRIPT_VERIFY_CHECKLOCKTIMEVERIFY = (1U << 9),
  89
  90     // support CHECKSEQUENCEVERIFY opcode
  91     //
  92     // See BIP112 for details
  93     SCRIPT_VERIFY_CHECKSEQUENCEVERIFY = (1U << 10),
  94
  95     // Support segregated witness
  96     //
  97     SCRIPT_VERIFY_WITNESS = (1U << 11),
  98
  99     // Making v1-v16 witness program non-standard
 100     //
 101     SCRIPT_VERIFY_DISCOURAGE_UPGRADABLE_WITNESS_PROGRAM = (1U << 12),
 102
 103     // Segwit script only: Require the argument of OP_IF/NOTIF to be exactly 0x01 or empty vector
 104     //
 105     SCRIPT_VERIFY_MINIMALIF = (1U << 13),
 106
 107     // Signature(s) must be empty vector if an CHECK(MULTI)SIG operation failed
 108     //
 109     SCRIPT_VERIFY_NULLFAIL = (1U << 14),
 110
 111     // Public keys in segregated witness scripts must be compressed
 112     //
 113     SCRIPT_VERIFY_WITNESS_PUBKEYTYPE = (1U << 15),
 114 };
 115
 116 bool CheckSignatureEncoding(const std::vector<unsigned char> &vchSig, unsigned int flags, ScriptError* serror);
 117
 118 struct PrecomputedTransactionData
 119 {
 120     uint256 hashPrevouts, hashSequence, hashOutputs;
 121     bool ready = false;
 122
 123     explicit PrecomputedTransactionData(const CTransaction& tx);
 124 };
 125
 126 enum SigVersion
 127 {
 128     SIGVERSION_BASE = 0,
 129     SIGVERSION_WITNESS_V0 = 1,
 130 };
 131
 132 uint256 SignatureHash(const CScript &scriptCode, const CTransaction& txTo, unsigned int nIn, int nHashType, const CAmount& amount, SigVersion sigversion, const PrecomputedTransactionData* cache = nullptr);
 133
 134 class BaseSignatureChecker
 135 {
 136 public:
 137     virtual bool CheckSig(const std::vector<unsigned char>& scriptSig, const std::vector<unsigned char>& vchPubKey, const CScript& scriptCode, SigVersion sigversion) const
 138     {
 139         return false;
 140     }
 141
 142     virtual bool CheckLockTime(const CScriptNum& nLockTime) const
 143     {
 144          return false;
 145     }
 146
 147     virtual bool CheckSequence(const CScriptNum& nSequence) const
 148     {
 149          return false;
 150     }
 151
 152     virtual ~BaseSignatureChecker() {}
 153 };
 154
 155 class TransactionSignatureChecker : public BaseSignatureChecker
 156 {
 157 private:
 158     const CTransaction* txTo;
 159     unsigned int nIn;
 160     const CAmount amount;
 161     const PrecomputedTransactionData* txdata;
 162
 163 protected:
 164     virtual bool VerifySignature(const std::vector<unsigned char>& vchSig, const CPubKey& vchPubKey, const uint256& sighash) const;
 165
 166 public:
 167     TransactionSignatureChecker(const CTransaction* txToIn, unsigned int nInIn, const CAmount& amountIn) : txTo(txToIn), nIn(nInIn), amount(amountIn), txdata(nullptr) {}
 168     TransactionSignatureChecker(const CTransaction* txToIn, unsigned int nInIn, const CAmount& amountIn, const PrecomputedTransactionData& txdataIn) : txTo(txToIn), nIn(nInIn), amount(amountIn), txdata(&txdataIn) {}
 169     bool CheckSig(const std::vector<unsigned char>& scriptSig, const std::vector<unsigned char>& vchPubKey, const CScript& scriptCode, SigVersion sigversion) const override;
 170     bool CheckLockTime(const CScriptNum& nLockTime) const override;
 171     bool CheckSequence(const CScriptNum& nSequence) const override;
 172 };
 173
 174 class MutableTransactionSignatureChecker : public TransactionSignatureChecker
 175 {
 176 private:
 177     const CTransaction txTo;
 178
 179 public:
 180     MutableTransactionSignatureChecker(const CMutableTransaction* txToIn, unsigned int nInIn, const CAmount& amountIn) : TransactionSignatureChecker(&txTo, nInIn, amountIn), txTo(*txToIn) {}
 181 };
 182
 183 bool EvalScript(std::vector<std::vector<unsigned char> >& stack, const CScript& script, unsigned int flags, const BaseSignatureChecker& checker, SigVersion sigversion, ScriptError* error = nullptr);
 184 bool VerifyScript(const CScript& scriptSig, const CScript& scriptPubKey, const CScriptWitness* witness, unsigned int flags, const BaseSignatureChecker& checker, ScriptError* serror = nullptr);
 185
 186 size_t CountWitnessSigOps(const CScript& scriptSig, const CScript& scriptPubKey, const CScriptWitness* witness, unsigned int flags);
 187
 188 #endif // BITCOIN_SCRIPT_INTERPRETER_H