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// Copyright (c) 2009-2010 Satoshi Nakamoto
// Copyright (c) 2009-2021 The Bitcoin Core developers
// Distributed under the MIT software license, see the accompanying
// file COPYING or http://www.opensource.org/licenses/mit-license.php.
#ifndef BITCOIN_CONSENSUS_VALIDATION_H
#define BITCOIN_CONSENSUS_VALIDATION_H
#include <string>
#include <version.h>
#include <consensus/consensus.h>
#include <primitives/transaction.h>
#include <primitives/block.h>
/** Index marker for when no witness commitment is present in a coinbase transaction. */
static constexpr int NO_WITNESS_COMMITMENT{-1};
/** Minimum size of a witness commitment structure. Defined in BIP 141. **/
static constexpr size_t MINIMUM_WITNESS_COMMITMENT{38};
/** A "reason" why a transaction was invalid, suitable for determining whether the
* provider of the transaction should be banned/ignored/disconnected/etc.
*/
enum class TxValidationResult {
TX_RESULT_UNSET = 0, //!< initial value. Tx has not yet been rejected
TX_CONSENSUS, //!< invalid by consensus rules
/**
* Invalid by a change to consensus rules more recent than SegWit.
* Currently unused as there are no such consensus rule changes, and any download
* sources realistically need to support SegWit in order to provide useful data,
* so differentiating between always-invalid and invalid-by-pre-SegWit-soft-fork
* is uninteresting.
*/
TX_RECENT_CONSENSUS_CHANGE,
TX_INPUTS_NOT_STANDARD, //!< inputs (covered by txid) failed policy rules
TX_NOT_STANDARD, //!< otherwise didn't meet our local policy rules
TX_MISSING_INPUTS, //!< transaction was missing some of its inputs
TX_PREMATURE_SPEND, //!< transaction spends a coinbase too early, or violates locktime/sequence locks
/**
* Transaction might have a witness prior to SegWit
* activation, or witness may have been malleated (which includes
* non-standard witnesses).
*/
TX_WITNESS_MUTATED,
/**
* Transaction is missing a witness.
*/
TX_WITNESS_STRIPPED,
/**
* Tx already in mempool or conflicts with a tx in the chain
* (if it conflicts with another tx in mempool, we use MEMPOOL_POLICY as it failed to reach the RBF threshold)
* Currently this is only used if the transaction already exists in the mempool or on chain.
*/
TX_CONFLICT,
TX_MEMPOOL_POLICY, //!< violated mempool's fee/size/descendant/RBF/etc limits
TX_NO_MEMPOOL, //!< this node does not have a mempool so can't validate the transaction
};
/** A "reason" why a block was invalid, suitable for determining whether the
* provider of the block should be banned/ignored/disconnected/etc.
* These are much more granular than the rejection codes, which may be more
* useful for some other use-cases.
*/
enum class BlockValidationResult {
BLOCK_RESULT_UNSET = 0, //!< initial value. Block has not yet been rejected
BLOCK_CONSENSUS, //!< invalid by consensus rules (excluding any below reasons)
/**
* Invalid by a change to consensus rules more recent than SegWit.
* Currently unused as there are no such consensus rule changes, and any download
* sources realistically need to support SegWit in order to provide useful data,
* so differentiating between always-invalid and invalid-by-pre-SegWit-soft-fork
* is uninteresting.
*/
BLOCK_RECENT_CONSENSUS_CHANGE,
BLOCK_CACHED_INVALID, //!< this block was cached as being invalid and we didn't store the reason why
BLOCK_INVALID_HEADER, //!< invalid proof of work or time too old
BLOCK_MUTATED, //!< the block's data didn't match the data committed to by the PoW
BLOCK_MISSING_PREV, //!< We don't have the previous block the checked one is built on
BLOCK_INVALID_PREV, //!< A block this one builds on is invalid
BLOCK_TIME_FUTURE, //!< block timestamp was > 2 hours in the future (or our clock is bad)
BLOCK_CHECKPOINT, //!< the block failed to meet one of our checkpoints
BLOCK_HEADER_LOW_WORK //!< the block header may be on a too-little-work chain
};
/** Template for capturing information about block/transaction validation. This is instantiated
* by TxValidationState and BlockValidationState for validation information on transactions
* and blocks respectively. */
template <typename Result>
class ValidationState
{
private:
enum class ModeState {
M_VALID, //!< everything ok
M_INVALID, //!< network rule violation (DoS value may be set)
M_ERROR, //!< run-time error
} m_mode{ModeState::M_VALID};
Result m_result{};
std::string m_reject_reason;
std::string m_debug_message;
public:
bool Invalid(Result result,
const std::string& reject_reason = "",
const std::string& debug_message = "")
{
m_result = result;
m_reject_reason = reject_reason;
m_debug_message = debug_message;
if (m_mode != ModeState::M_ERROR) m_mode = ModeState::M_INVALID;
return false;
}
bool Error(const std::string& reject_reason)
{
if (m_mode == ModeState::M_VALID)
m_reject_reason = reject_reason;
m_mode = ModeState::M_ERROR;
return false;
}
bool IsValid() const { return m_mode == ModeState::M_VALID; }
bool IsInvalid() const { return m_mode == ModeState::M_INVALID; }
bool IsError() const { return m_mode == ModeState::M_ERROR; }
Result GetResult() const { return m_result; }
std::string GetRejectReason() const { return m_reject_reason; }
std::string GetDebugMessage() const { return m_debug_message; }
std::string ToString() const
{
if (IsValid()) {
return "Valid";
}
if (!m_debug_message.empty()) {
return m_reject_reason + ", " + m_debug_message;
}
return m_reject_reason;
}
};
class TxValidationState : public ValidationState<TxValidationResult> {};
class BlockValidationState : public ValidationState<BlockValidationResult> {};
// These implement the weight = (stripped_size * 4) + witness_size formula,
// using only serialization with and without witness data. As witness_size
// is equal to total_size - stripped_size, this formula is identical to:
// weight = (stripped_size * 3) + total_size.
static inline int64_t GetTransactionWeight(const CTransaction& tx)
{
return ::GetSerializeSize(tx, PROTOCOL_VERSION | SERIALIZE_TRANSACTION_NO_WITNESS) * (WITNESS_SCALE_FACTOR - 1) + ::GetSerializeSize(tx, PROTOCOL_VERSION);
}
static inline int64_t GetBlockWeight(const CBlock& block)
{
return ::GetSerializeSize(block, PROTOCOL_VERSION | SERIALIZE_TRANSACTION_NO_WITNESS) * (WITNESS_SCALE_FACTOR - 1) + ::GetSerializeSize(block, PROTOCOL_VERSION);
}
static inline int64_t GetTransactionInputWeight(const CTxIn& txin)
{
// scriptWitness size is added here because witnesses and txins are split up in segwit serialization.
return ::GetSerializeSize(txin, PROTOCOL_VERSION | SERIALIZE_TRANSACTION_NO_WITNESS) * (WITNESS_SCALE_FACTOR - 1) + ::GetSerializeSize(txin, PROTOCOL_VERSION) + ::GetSerializeSize(txin.scriptWitness.stack, PROTOCOL_VERSION);
}
/** Compute at which vout of the block's coinbase transaction the witness commitment occurs, or -1 if not found */
inline int GetWitnessCommitmentIndex(const CBlock& block)
{
int commitpos = NO_WITNESS_COMMITMENT;
if (!block.vtx.empty()) {
for (size_t o = 0; o < block.vtx[0]->vout.size(); o++) {
const CTxOut& vout = block.vtx[0]->vout[o];
if (vout.scriptPubKey.size() >= MINIMUM_WITNESS_COMMITMENT &&
vout.scriptPubKey[0] == OP_RETURN &&
vout.scriptPubKey[1] == 0x24 &&
vout.scriptPubKey[2] == 0xaa &&
vout.scriptPubKey[3] == 0x21 &&
vout.scriptPubKey[4] == 0xa9 &&
vout.scriptPubKey[5] == 0xed) {
commitpos = o;
}
}
}
return commitpos;
}
#endif // BITCOIN_CONSENSUS_VALIDATION_H
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