1  // Copyright (c) 2009-2010 Satoshi Nakamoto
  2  // Copyright (c) 2009-present 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_CONSENSUS_VALIDATION_H
  7  #define BITCOIN_CONSENSUS_VALIDATION_H
  8  
  9  #include <string>
 10  #include <consensus/consensus.h>
 11  #include <primitives/transaction.h>
 12  #include <primitives/block.h>
 13  
 14  /** Index marker for when no witness commitment is present in a coinbase transaction. */
 15  static constexpr int NO_WITNESS_COMMITMENT{-1};
 16  
 17  /** Minimum size of a witness commitment structure. Defined in BIP 141. **/
 18  static constexpr size_t MINIMUM_WITNESS_COMMITMENT{38};
 19  
 20  /** A "reason" why a transaction was invalid, suitable for determining whether the
 21    * provider of the transaction should be banned/ignored/disconnected/etc.
 22    */
 23  enum class TxValidationResult {
 24      TX_RESULT_UNSET = 0,     //!< initial value. Tx has not yet been rejected
 25      TX_CONSENSUS,            //!< invalid by consensus rules
 26      TX_INPUTS_NOT_STANDARD,   //!< inputs (covered by txid) failed policy rules
 27      TX_NOT_STANDARD,          //!< otherwise didn't meet our local policy rules
 28      TX_MISSING_INPUTS,        //!< transaction was missing some of its inputs
 29      TX_PREMATURE_SPEND,       //!< transaction spends a coinbase too early, or violates locktime/sequence locks
 30      /**
 31       * Transaction might have a witness prior to SegWit
 32       * activation, or witness may have been malleated (which includes
 33       * non-standard witnesses).
 34       */
 35      TX_WITNESS_MUTATED,
 36      /**
 37       * Transaction is missing a witness.
 38       */
 39      TX_WITNESS_STRIPPED,
 40      /**
 41       * Tx already in mempool or conflicts with a tx in the chain
 42       * (if it conflicts with another tx in mempool, we use MEMPOOL_POLICY as it failed to reach the RBF threshold)
 43       * Currently this is only used if the transaction already exists in the mempool or on chain.
 44       */
 45      TX_CONFLICT,
 46      TX_MEMPOOL_POLICY,        //!< violated mempool's fee/size/descendant/RBF/etc limits
 47      TX_NO_MEMPOOL,            //!< this node does not have a mempool so can't validate the transaction
 48      TX_RECONSIDERABLE,        //!< fails some policy, but might be acceptable if submitted in a (different) package
 49      TX_UNKNOWN,               //!< transaction was not validated because package failed
 50  };
 51  
 52  /** A "reason" why a block was invalid, suitable for determining whether the
 53    * provider of the block should be banned/ignored/disconnected/etc.
 54    * These are much more granular than the rejection codes, which may be more
 55    * useful for some other use-cases.
 56    */
 57  enum class BlockValidationResult {
 58      BLOCK_RESULT_UNSET = 0,  //!< initial value. Block has not yet been rejected
 59      BLOCK_CONSENSUS,         //!< invalid by consensus rules (excluding any below reasons)
 60      BLOCK_CACHED_INVALID,    //!< this block was cached as being invalid and we didn't store the reason why
 61      BLOCK_INVALID_HEADER,    //!< invalid proof of work or time too old
 62      BLOCK_MUTATED,           //!< the block's data didn't match the data committed to by the PoW
 63      BLOCK_MISSING_PREV,      //!< We don't have the previous block the checked one is built on
 64      BLOCK_INVALID_PREV,      //!< A block this one builds on is invalid
 65      BLOCK_TIME_FUTURE,       //!< block timestamp was > 2 hours in the future (or our clock is bad)
 66      BLOCK_HEADER_LOW_WORK    //!< the block header may be on a too-little-work chain
 67  };
 68  
 69  
 70  
 71  /** Template for capturing information about block/transaction validation. This is instantiated
 72   *  by TxValidationState and BlockValidationState for validation information on transactions
 73   *  and blocks respectively. */
 74  template <typename Result>
 75  class ValidationState
 76  {
 77  private:
 78      enum class ModeState {
 79          M_VALID,   //!< everything ok
 80          M_INVALID, //!< network rule violation (DoS value may be set)
 81          M_ERROR,   //!< run-time error
 82      } m_mode{ModeState::M_VALID};
 83      Result m_result{};
 84      std::string m_reject_reason;
 85      std::string m_debug_message;
 86  
 87  public:
 88      bool Invalid(Result result,
 89                   const std::string& reject_reason = "",
 90                   const std::string& debug_message = "")
 91      {
 92          m_result = result;
 93          m_reject_reason = reject_reason;
 94          m_debug_message = debug_message;
 95          if (m_mode != ModeState::M_ERROR) m_mode = ModeState::M_INVALID;
 96          return false;
 97      }
 98      bool Error(const std::string& reject_reason)
 99      {
100          if (m_mode == ModeState::M_VALID)
101              m_reject_reason = reject_reason;
102          m_mode = ModeState::M_ERROR;
103          return false;
104      }
105      bool IsValid() const { return m_mode == ModeState::M_VALID; }
106      bool IsInvalid() const { return m_mode == ModeState::M_INVALID; }
107      bool IsError() const { return m_mode == ModeState::M_ERROR; }
108      Result GetResult() const { return m_result; }
109      std::string GetRejectReason() const { return m_reject_reason; }
110      std::string GetDebugMessage() const { return m_debug_message; }
111      std::string ToString() const
112      {
113          if (IsValid()) {
114              return "Valid";
115          }
116  
117          if (!m_debug_message.empty()) {
118              return m_reject_reason + ", " + m_debug_message;
119          }
120  
121          return m_reject_reason;
122      }
123  };
124  
125  class TxValidationState : public ValidationState<TxValidationResult> {};
126  class BlockValidationState : public ValidationState<BlockValidationResult> {};
127  
128  // These implement the weight = (stripped_size * 4) + witness_size formula,
129  // using only serialization with and without witness data. As witness_size
130  // is equal to total_size - stripped_size, this formula is identical to:
131  // weight = (stripped_size * 3) + total_size.
132  static inline int32_t GetTransactionWeight(const CTransaction& tx)
133  {
134      return ::GetSerializeSize(TX_NO_WITNESS(tx)) * (WITNESS_SCALE_FACTOR - 1) + ::GetSerializeSize(TX_WITH_WITNESS(tx));
135  }
136  static inline int64_t GetBlockWeight(const CBlock& block)
137  {
138      return ::GetSerializeSize(TX_NO_WITNESS(block)) * (WITNESS_SCALE_FACTOR - 1) + ::GetSerializeSize(TX_WITH_WITNESS(block));
139  }
140  static inline int64_t GetTransactionInputWeight(const CTxIn& txin)
141  {
142      // scriptWitness size is added here because witnesses and txins are split up in segwit serialization.
143      return ::GetSerializeSize(TX_NO_WITNESS(txin)) * (WITNESS_SCALE_FACTOR - 1) + ::GetSerializeSize(TX_WITH_WITNESS(txin)) + ::GetSerializeSize(txin.scriptWitness.stack);
144  }
145  
146  /** Compute at which vout of the block's coinbase transaction the witness commitment occurs, or -1 if not found */
147  inline int GetWitnessCommitmentIndex(const CBlock& block)
148  {
149      int commitpos = NO_WITNESS_COMMITMENT;
150      if (!block.vtx.empty()) {
151          for (size_t o = 0; o < block.vtx[0]->vout.size(); o++) {
152              const CTxOut& vout = block.vtx[0]->vout[o];
153              if (vout.scriptPubKey.size() >= MINIMUM_WITNESS_COMMITMENT &&
154                  vout.scriptPubKey[0] == OP_RETURN &&
155                  vout.scriptPubKey[1] == 0x24 &&
156                  vout.scriptPubKey[2] == 0xaa &&
157                  vout.scriptPubKey[3] == 0x21 &&
158                  vout.scriptPubKey[4] == 0xa9 &&
159                  vout.scriptPubKey[5] == 0xed) {
160                  commitpos = o;
161              }
162          }
163      }
164      return commitpos;
165  }
166  
167  #endif // BITCOIN_CONSENSUS_VALIDATION_H