Validation results and weight helpers

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