Repository: bitcoin/bitcoin
File: src/policy/policy.h (C/C++)

Code before:
/** The maximum number of potentially executed legacy signature operations in a single standard tx */
static constexpr unsigned int MAX_TX_LEGACY_SIGOPS{2'500};
/** Default for -incrementalrelayfee, which sets the minimum feerate increase for mempool limiting or replacement **/
static constexpr unsigned int DEFAULT_INCREMENTAL_RELAY_FEE{1000};
/** Default for -bytespersigop */
static constexpr unsigned int DEFAULT_BYTES_PER_SIGOP{20};
/** Default for -permitbaremultisig */
static constexpr bool DEFAULT_PERMIT_BAREMULTISIG{true};
/** The maximum number of witness stack items in a standard P2WSH script */
static constexpr unsigned int MAX_STANDARD_P2WSH_STACK_ITEMS{100};
/** The maximum size in bytes of each witness stack item in a standard P2WSH script */
static constexpr unsigned int MAX_STANDARD_P2WSH_STACK_ITEM_SIZE{80};
/** The maximum size in bytes of each witness stack item in a standard BIP 342 script (Taproot, leaf version 0xc0) */
static constexpr unsigned int MAX_STANDARD_TAPSCRIPT_STACK_ITEM_SIZE{80};
/** The maximum size in bytes of a standard witnessScript */
static constexpr unsigned int MAX_STANDARD_P2WSH_SCRIPT_SIZE{3600};
/** The maximum size of a standard ScriptSig */
static constexpr unsigned int MAX_STANDARD_SCRIPTSIG_SIZE{1650};
/** Min feerate for defining dust.
 * Changing the dust limit changes which transactions are
 * standard and should be done with care and ideally rarely. It makes sense to
 * only increase the dust limit after prior releases were already not creating
 * outputs below the new threshold */
static constexpr unsigned int DUST_RELAY_TX_FEE{3000};
/** Default for -minrelaytxfee, minimum relay fee for transactions */
static constexpr unsigned int DEFAULT_MIN_RELAY_TX_FEE{1000};
/** Default for -limitancestorcount, max number of in-mempool ancestors */
static constexpr unsigned int DEFAULT_ANCESTOR_LIMIT{25};
/** Default for -limitancestorsize, maximum kilobytes of tx + all in-mempool ancestors */
static constexpr unsigned int DEFAULT_ANCESTOR_SIZE_LIMIT_KVB{101};
/** Default for -limitdescendantcount, max number of in-mempool descendants */
static constexpr unsigned int DEFAULT_DESCENDANT_LIMIT{25};
/** Default for -limitdescendantsize, maximum kilobytes of in-mempool descendants */
static constexpr unsigned int DEFAULT_DESCENDANT_SIZE_LIMIT_KVB{101};
/** Default for -datacarrier */
static const bool DEFAULT_ACCEPT_DATACARRIER = true;
/**
 * Default setting for -datacarriersize in vbytes.
 */
static const unsigned int MAX_OP_RETURN_RELAY = MAX_STANDARD_TX_WEIGHT / WITNESS_SCALE_FACTOR;
/**
 * An extra transaction can be added to a package, as long as it only has one
 * ancestor and is no larger than this. Not really any reason to make this
 * configurable as it doesn't materially change DoS parameters.
 */
static constexpr unsigned int EXTRA_DESCENDANT_TX_SIZE_LIMIT{10000};

/**
 * Maximum number of ephemeral dust outputs allowed.
 */
static constexpr unsigned int MAX_DUST_OUTPUTS_PER_TX{1};

Review comment (bug):
In 5792f8999912b00461cea63f65be9c8dbf3ad403 "[policy] lower default minrelaytxfee and incrementalrelayfee to 100sat/kvB"

Since `DEFAULT_MIN_RELAY_TX_FEE` and `DEFAULT_INCREMENTAL_RELAY_FEE` are tied to each other, it might make sense to consolidate these defaults into a single value. Alternatively, we could have a `static_assert` that ensures that the defaults are equal to each other, or within whatever range is acceptable.

I noticed that when I change `DEFAULT_MIN_RELAY_TX_FEE`, almost none of the tests fail, and none of the tests that I would expect fail, failed. Given that this was one of the issues with #32959, I think we should have some safeguard here if this may be changed again in the future.

Code after:
/** The maximum number of potentially executed legacy signature operations in a single standard tx */
static constexpr unsigned int MAX_TX_LEGACY_SIGOPS{2'500};
/** Default for -incrementalrelayfee, which sets the minimum feerate increase for mempool limiting or replacement **/
static constexpr unsigned int DEFAULT_INCREMENTAL_RELAY_FEE{100};
/** Default for -bytespersigop */
static constexpr unsigned int DEFAULT_BYTES_PER_SIGOP{20};
/** Default for -permitbaremultisig */
static constexpr bool DEFAULT_PERMIT_BAREMULTISIG{true};
/** The maximum number of witness stack items in a standard P2WSH script */
static constexpr unsigned int MAX_STANDARD_P2WSH_STACK_ITEMS{100};
/** The maximum size in bytes of each witness stack item in a standard P2WSH script */
static constexpr unsigned int MAX_STANDARD_P2WSH_STACK_ITEM_SIZE{80};
/** The maximum size in bytes of each witness stack item in a standard BIP 342 script (Taproot, leaf version 0xc0) */
static constexpr unsigned int MAX_STANDARD_TAPSCRIPT_STACK_ITEM_SIZE{80};
/** The maximum size in bytes of a standard witnessScript */
static constexpr unsigned int MAX_STANDARD_P2WSH_SCRIPT_SIZE{3600};
/** The maximum size of a standard ScriptSig */
static constexpr unsigned int MAX_STANDARD_SCRIPTSIG_SIZE{1650};
/** Min feerate for defining dust.
 * Changing the dust limit changes which transactions are
 * standard and should be done with care and ideally rarely. It makes sense to
 * only increase the dust limit after prior releases were already not creating
 * outputs below the new threshold */
static constexpr unsigned int DUST_RELAY_TX_FEE{3000};
/** Default for -minrelaytxfee, minimum relay fee for transactions */
static constexpr unsigned int DEFAULT_MIN_RELAY_TX_FEE{100};
/** Default for -limitancestorcount, max number of in-mempool ancestors */
static constexpr unsigned int DEFAULT_ANCESTOR_LIMIT{25};
/** Default for -limitancestorsize, maximum kilobytes of tx + all in-mempool ancestors */
static constexpr unsigned int DEFAULT_ANCESTOR_SIZE_LIMIT_KVB{101};
/** Default for -limitdescendantcount, max number of in-mempool descendants */
static constexpr unsigned int DEFAULT_DESCENDANT_LIMIT{25};
/** Default for -limitdescendantsize, maximum kilobytes of in-mempool descendants */
static constexpr unsigned int DEFAULT_DESCENDANT_SIZE_LIMIT_KVB{101};
/** Default for -datacarrier */
static const bool DEFAULT_ACCEPT_DATACARRIER = true;
/**
 * Default setting for -datacarriersize in vbytes.
 */
static const unsigned int MAX_OP_RETURN_RELAY = MAX_STANDARD_TX_WEIGHT / WITNESS_SCALE_FACTOR;
/**
 * An extra transaction can be added to a package, as long as it only has one
 * ancestor and is no larger than this. Not really any reason to make this
 * configurable as it doesn't materially change DoS parameters.
 */
static constexpr unsigned int EXTRA_DESCENDANT_TX_SIZE_LIMIT{10000};

/**
 * Maximum number of ephemeral dust outputs allowed.
 */
static constexpr unsigned int MAX_DUST_OUTPUTS_PER_TX{1};