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       1                 :            : // Copyright (c) 2009-2010 Satoshi Nakamoto
       2                 :            : // Copyright (c) 2009-2022 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 <version.h>
      11                 :            : #include <consensus/consensus.h>
      12                 :            : #include <primitives/transaction.h>
      13                 :            : #include <primitives/block.h>
      14                 :            : 
      15                 :            : /** Index marker for when no witness commitment is present in a coinbase transaction. */
      16                 :            : static constexpr int NO_WITNESS_COMMITMENT{-1};
      17                 :            : 
      18                 :            : /** Minimum size of a witness commitment structure. Defined in BIP 141. **/
      19                 :            : static constexpr size_t MINIMUM_WITNESS_COMMITMENT{38};
      20                 :            : 
      21                 :            : /** A "reason" why a transaction was invalid, suitable for determining whether the
      22                 :            :   * provider of the transaction should be banned/ignored/disconnected/etc.
      23                 :            :   */
      24                 :            : enum class TxValidationResult {
      25                 :            :     TX_RESULT_UNSET = 0,     //!< initial value. Tx has not yet been rejected
      26                 :            :     TX_CONSENSUS,            //!< invalid by consensus rules
      27                 :            :     /**
      28                 :            :      * Invalid by a change to consensus rules more recent than SegWit.
      29                 :            :      * Currently unused as there are no such consensus rule changes, and any download
      30                 :            :      * sources realistically need to support SegWit in order to provide useful data,
      31                 :            :      * so differentiating between always-invalid and invalid-by-pre-SegWit-soft-fork
      32                 :            :      * is uninteresting.
      33                 :            :      */
      34                 :            :     TX_RECENT_CONSENSUS_CHANGE,
      35                 :            :     TX_INPUTS_NOT_STANDARD,   //!< inputs (covered by txid) failed policy rules
      36                 :            :     TX_NOT_STANDARD,          //!< otherwise didn't meet our local policy rules
      37                 :            :     TX_MISSING_INPUTS,        //!< transaction was missing some of its inputs
      38                 :            :     TX_PREMATURE_SPEND,       //!< transaction spends a coinbase too early, or violates locktime/sequence locks
      39                 :            :     /**
      40                 :            :      * Transaction might have a witness prior to SegWit
      41                 :            :      * activation, or witness may have been malleated (which includes
      42                 :            :      * non-standard witnesses).
      43                 :            :      */
      44                 :            :     TX_WITNESS_MUTATED,
      45                 :            :     /**
      46                 :            :      * Transaction is missing a witness.
      47                 :            :      */
      48                 :            :     TX_WITNESS_STRIPPED,
      49                 :            :     /**
      50                 :            :      * Tx already in mempool or conflicts with a tx in the chain
      51                 :            :      * (if it conflicts with another tx in mempool, we use MEMPOOL_POLICY as it failed to reach the RBF threshold)
      52                 :            :      * Currently this is only used if the transaction already exists in the mempool or on chain.
      53                 :            :      */
      54                 :            :     TX_CONFLICT,
      55                 :            :     TX_MEMPOOL_POLICY,        //!< violated mempool's fee/size/descendant/RBF/etc limits
      56                 :            :     TX_NO_MEMPOOL,            //!< this node does not have a mempool so can't validate the transaction
      57                 :            : };
      58                 :            : 
      59                 :            : /** A "reason" why a block was invalid, suitable for determining whether the
      60                 :            :   * provider of the block should be banned/ignored/disconnected/etc.
      61                 :            :   * These are much more granular than the rejection codes, which may be more
      62                 :            :   * useful for some other use-cases.
      63                 :            :   */
      64                 :            : enum class BlockValidationResult {
      65                 :            :     BLOCK_RESULT_UNSET = 0,  //!< initial value. Block has not yet been rejected
      66                 :            :     BLOCK_CONSENSUS,         //!< invalid by consensus rules (excluding any below reasons)
      67                 :            :     /**
      68                 :            :      * Invalid by a change to consensus rules more recent than SegWit.
      69                 :            :      * Currently unused as there are no such consensus rule changes, and any download
      70                 :            :      * sources realistically need to support SegWit in order to provide useful data,
      71                 :            :      * so differentiating between always-invalid and invalid-by-pre-SegWit-soft-fork
      72                 :            :      * is uninteresting.
      73                 :            :      */
      74                 :            :     BLOCK_RECENT_CONSENSUS_CHANGE,
      75                 :            :     BLOCK_CACHED_INVALID,    //!< this block was cached as being invalid and we didn't store the reason why
      76                 :            :     BLOCK_INVALID_HEADER,    //!< invalid proof of work or time too old
      77                 :            :     BLOCK_MUTATED,           //!< the block's data didn't match the data committed to by the PoW
      78                 :            :     BLOCK_MISSING_PREV,      //!< We don't have the previous block the checked one is built on
      79                 :            :     BLOCK_INVALID_PREV,      //!< A block this one builds on is invalid
      80                 :            :     BLOCK_TIME_FUTURE,       //!< block timestamp was > 2 hours in the future (or our clock is bad)
      81                 :            :     BLOCK_CHECKPOINT,        //!< the block failed to meet one of our checkpoints
      82                 :            :     BLOCK_HEADER_LOW_WORK    //!< the block header may be on a too-little-work chain
      83                 :            : };
      84                 :            : 
      85                 :            : 
      86                 :            : 
      87                 :            : /** Template for capturing information about block/transaction validation. This is instantiated
      88                 :            :  *  by TxValidationState and BlockValidationState for validation information on transactions
      89                 :            :  *  and blocks respectively. */
      90                 :            : template <typename Result>
      91                 :       1053 : class ValidationState
      92                 :            : {
      93                 :            : private:
      94                 :            :     enum class ModeState {
      95                 :            :         M_VALID,   //!< everything ok
      96                 :            :         M_INVALID, //!< network rule violation (DoS value may be set)
      97                 :            :         M_ERROR,   //!< run-time error
      98                 :       1053 :     } m_mode{ModeState::M_VALID};
      99                 :       1053 :     Result m_result{};
     100                 :            :     std::string m_reject_reason;
     101                 :            :     std::string m_debug_message;
     102                 :            : 
     103                 :            : public:
     104                 :          0 :     bool Invalid(Result result,
     105                 :            :                  const std::string& reject_reason = "",
     106                 :            :                  const std::string& debug_message = "")
     107                 :            :     {
     108                 :          0 :         m_result = result;
     109                 :          0 :         m_reject_reason = reject_reason;
     110                 :          0 :         m_debug_message = debug_message;
     111 [ #  # ][ #  # ]:          0 :         if (m_mode != ModeState::M_ERROR) m_mode = ModeState::M_INVALID;
                 [ #  # ]
     112                 :          0 :         return false;
     113                 :            :     }
     114                 :          0 :     bool Error(const std::string& reject_reason)
     115                 :            :     {
     116         [ #  # ]:          0 :         if (m_mode == ModeState::M_VALID)
     117                 :          0 :             m_reject_reason = reject_reason;
     118                 :          0 :         m_mode = ModeState::M_ERROR;
     119                 :          0 :         return false;
     120                 :            :     }
     121                 :        150 :     bool IsValid() const { return m_mode == ModeState::M_VALID; }
     122                 :          0 :     bool IsInvalid() const { return m_mode == ModeState::M_INVALID; }
     123                 :          0 :     bool IsError() const { return m_mode == ModeState::M_ERROR; }
     124                 :          0 :     Result GetResult() const { return m_result; }
     125                 :          0 :     std::string GetRejectReason() const { return m_reject_reason; }
     126                 :          0 :     std::string GetDebugMessage() const { return m_debug_message; }
     127                 :          0 :     std::string ToString() const
     128                 :            :     {
     129 [ #  # ][ #  # ]:          0 :         if (IsValid()) {
     130 [ #  # ][ #  # ]:          0 :             return "Valid";
     131                 :            :         }
     132                 :            : 
     133 [ #  # ][ #  # ]:          0 :         if (!m_debug_message.empty()) {
     134 [ #  # ][ #  # ]:          0 :             return m_reject_reason + ", " + m_debug_message;
     135                 :            :         }
     136                 :            : 
     137                 :          0 :         return m_reject_reason;
     138                 :          0 :     }
     139                 :            : };
     140                 :            : 
     141                 :          0 : class TxValidationState : public ValidationState<TxValidationResult> {};
     142                 :          0 : class BlockValidationState : public ValidationState<BlockValidationResult> {};
     143                 :            : 
     144                 :            : // These implement the weight = (stripped_size * 4) + witness_size formula,
     145                 :            : // using only serialization with and without witness data. As witness_size
     146                 :            : // is equal to total_size - stripped_size, this formula is identical to:
     147                 :            : // weight = (stripped_size * 3) + total_size.
     148                 :       3863 : static inline int32_t GetTransactionWeight(const CTransaction& tx)
     149                 :            : {
     150                 :       3863 :     return ::GetSerializeSize(tx, PROTOCOL_VERSION | SERIALIZE_TRANSACTION_NO_WITNESS) * (WITNESS_SCALE_FACTOR - 1) + ::GetSerializeSize(tx, PROTOCOL_VERSION);
     151                 :            : }
     152                 :        450 : static inline int64_t GetBlockWeight(const CBlock& block)
     153                 :            : {
     154                 :        450 :     return ::GetSerializeSize(block, PROTOCOL_VERSION | SERIALIZE_TRANSACTION_NO_WITNESS) * (WITNESS_SCALE_FACTOR - 1) + ::GetSerializeSize(block, PROTOCOL_VERSION);
     155                 :            : }
     156                 :          0 : static inline int64_t GetTransactionInputWeight(const CTxIn& txin)
     157                 :            : {
     158                 :            :     // scriptWitness size is added here because witnesses and txins are split up in segwit serialization.
     159                 :          0 :     return ::GetSerializeSize(txin, PROTOCOL_VERSION | SERIALIZE_TRANSACTION_NO_WITNESS) * (WITNESS_SCALE_FACTOR - 1) + ::GetSerializeSize(txin, PROTOCOL_VERSION) + ::GetSerializeSize(txin.scriptWitness.stack, PROTOCOL_VERSION);
     160                 :            : }
     161                 :            : 
     162                 :            : /** Compute at which vout of the block's coinbase transaction the witness commitment occurs, or -1 if not found */
     163                 :       1050 : inline int GetWitnessCommitmentIndex(const CBlock& block)
     164                 :            : {
     165                 :       1050 :     int commitpos = NO_WITNESS_COMMITMENT;
     166         [ -  + ]:       1050 :     if (!block.vtx.empty()) {
     167         [ +  + ]:       2850 :         for (size_t o = 0; o < block.vtx[0]->vout.size(); o++) {
     168                 :       1800 :             const CTxOut& vout = block.vtx[0]->vout[o];
     169 [ +  + ][ +  - ]:       2550 :             if (vout.scriptPubKey.size() >= MINIMUM_WITNESS_COMMITMENT &&
     170         [ +  - ]:        750 :                 vout.scriptPubKey[0] == OP_RETURN &&
     171         [ +  - ]:        750 :                 vout.scriptPubKey[1] == 0x24 &&
     172         [ +  - ]:        750 :                 vout.scriptPubKey[2] == 0xaa &&
     173         [ +  - ]:        750 :                 vout.scriptPubKey[3] == 0x21 &&
     174         [ +  - ]:        750 :                 vout.scriptPubKey[4] == 0xa9 &&
     175                 :        750 :                 vout.scriptPubKey[5] == 0xed) {
     176                 :        750 :                 commitpos = o;
     177                 :        750 :             }
     178                 :       1800 :         }
     179                 :       1050 :     }
     180                 :       1050 :     return commitpos;
     181                 :            : }
     182                 :            : 
     183                 :            : #endif // BITCOIN_CONSENSUS_VALIDATION_H