policy.cpp File Reference

#include <policy/policy.h>
#include <consensus/validation.h>
#include <coins.h>
#include <span.h>

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Functions
CAmount	GetDustThreshold (const CTxOut &txout, const CFeeRate &dustRelayFeeIn)
bool	IsDust (const CTxOut &txout, const CFeeRate &dustRelayFeeIn)
bool	IsStandard (const CScript &scriptPubKey, TxoutType &whichType)
bool	IsStandardTx (const CTransaction &tx, bool permit_bare_multisig, const CFeeRate &dust_relay_fee, std::string &reason)
	Check for standard transaction types. More...
bool	AreInputsStandard (const CTransaction &tx, const CCoinsViewCache &mapInputs, bool taproot_active)
	Check transaction inputs to mitigate two potential denial-of-service attacks: More...
bool	IsWitnessStandard (const CTransaction &tx, const CCoinsViewCache &mapInputs)
	Check if the transaction is over standard P2WSH resources limit: 3600bytes witnessScript size, 80bytes per witness stack element, 100 witness stack elements These limits are adequate for multisignatures up to n-of-100 using OP_CHECKSIG, OP_ADD, and OP_EQUAL. More...
int64_t	GetVirtualTransactionSize (int64_t nWeight, int64_t nSigOpCost, unsigned int bytes_per_sigop)
	Compute the virtual transaction size (weight reinterpreted as bytes). More...
int64_t	GetVirtualTransactionSize (const CTransaction &tx, int64_t nSigOpCost, unsigned int bytes_per_sigop)
int64_t	GetVirtualTransactionInputSize (const CTxIn &txin, int64_t nSigOpCost, unsigned int bytes_per_sigop)

Function Documentation

AreInputsStandard()

bool AreInputsStandard	(	const CTransaction &	tx,
		const CCoinsViewCache &	mapInputs,
		bool	taproot_active
	)

Check transaction inputs to mitigate two potential denial-of-service attacks:

Check for standard transaction types.

1. scriptSigs with extra data stuffed into them, not consumed by scriptPubKey (or P2SH script)
2. P2SH scripts with a crazy number of expensive CHECKSIG/CHECKMULTISIG operations

Why bother? To avoid denial-of-service attacks; an attacker can submit a standard HASH... OP_EQUAL transaction, which will get accepted into blocks. The redemption script can be anything; an attacker could use a very expensive-to-check-upon-redemption script like: DUP CHECKSIG DROP ... repeated 100 times... OP_1

Note that only the non-witness portion of the transaction is checked here.

Definition at line 164 of file policy.cpp.

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GetDustThreshold()

CAmount GetDustThreshold	(	const CTxOut &	txout,
		const CFeeRate &	dustRelayFeeIn
	)

Definition at line 14 of file policy.cpp.

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GetVirtualTransactionInputSize()

int64_t GetVirtualTransactionInputSize	(	const CTxIn &	txin,
		int64_t	nSigOpCost,
		unsigned int	bytes_per_sigop
	)

Definition at line 295 of file policy.cpp.

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GetVirtualTransactionSize() [1/2]

int64_t GetVirtualTransactionSize	(	const CTransaction &	tx,
		int64_t	nSigOpCost,
		unsigned int	bytes_per_sigop
	)

Definition at line 290 of file policy.cpp.

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GetVirtualTransactionSize() [2/2]

int64_t GetVirtualTransactionSize	(	int64_t	nWeight,
		int64_t	nSigOpCost,
		unsigned int	bytes_per_sigop
	)

Compute the virtual transaction size (weight reinterpreted as bytes).

Definition at line 285 of file policy.cpp.

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IsDust()

bool IsDust	(	const CTxOut &	txout,
		const CFeeRate &	dustRelayFeeIn
	)

Definition at line 53 of file policy.cpp.

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IsStandard()

bool IsStandard	(	const CScript &	scriptPubKey,
		TxoutType &	whichType
	)

Definition at line 58 of file policy.cpp.

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IsStandardTx()

bool IsStandardTx	(	const CTransaction &	tx,
		bool	permit_bare_multisig,
		const CFeeRate &	dust_relay_fee,
		std::string &	reason
	)

Check for standard transaction types.

Returns

True if all outputs (scriptPubKeys) use only standard transaction forms

Definition at line 81 of file policy.cpp.

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IsWitnessStandard()

bool IsWitnessStandard	(	const CTransaction &	tx,
		const CCoinsViewCache &	mapInputs
	)

Check if the transaction is over standard P2WSH resources limit: 3600bytes witnessScript size, 80bytes per witness stack element, 100 witness stack elements These limits are adequate for multisignatures up to n-of-100 using OP_CHECKSIG, OP_ADD, and OP_EQUAL.

Also enforce a maximum stack item size limit and no annexes for tapscript spends.

Definition at line 201 of file policy.cpp.

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