From 734076c6de1781f957c8bc3bf7ed6951920cfcf6 Mon Sep 17 00:00:00 2001 From: ismaelsadeeq Date: Thu, 29 Feb 2024 12:43:52 +0100 Subject: [PATCH] [wallet, rpc]: add `max_tx_weight` to tx funding options This allows a transaction's weight to be bound under a certain weight if possible and desired. This can be beneficial for future RBF attempts, or whenever a more restricted spend topology is desired. Co-authored-by: Greg Sanders --- src/rpc/client.cpp | 3 ++ src/wallet/coincontrol.h | 2 + src/wallet/coinselection.cpp | 31 ++++++++++---- src/wallet/coinselection.h | 8 +++- src/wallet/rpc/spend.cpp | 14 ++++++ src/wallet/spend.cpp | 21 +++++++-- src/wallet/test/fuzz/coinselection.cpp | 11 +++-- test/functional/rpc_psbt.py | 45 ++++++++++++++++++++ test/functional/test_framework/blocktools.py | 1 + 9 files changed, 119 insertions(+), 17 deletions(-) diff --git a/src/rpc/client.cpp b/src/rpc/client.cpp index 7dfe69a6c5021..b866fa484bf69 100644 --- a/src/rpc/client.cpp +++ b/src/rpc/client.cpp @@ -146,6 +146,7 @@ static const CRPCConvertParam vRPCConvertParams[] = { "fundrawtransaction", 1, "conf_target"}, { "fundrawtransaction", 1, "replaceable"}, { "fundrawtransaction", 1, "solving_data"}, + { "fundrawtransaction", 1, "max_tx_weight"}, { "fundrawtransaction", 2, "iswitness" }, { "walletcreatefundedpsbt", 0, "inputs" }, { "walletcreatefundedpsbt", 1, "outputs" }, @@ -164,6 +165,7 @@ static const CRPCConvertParam vRPCConvertParams[] = { "walletcreatefundedpsbt", 3, "conf_target"}, { "walletcreatefundedpsbt", 3, "replaceable"}, { "walletcreatefundedpsbt", 3, "solving_data"}, + { "walletcreatefundedpsbt", 3, "max_tx_weight"}, { "walletcreatefundedpsbt", 4, "bip32derivs" }, { "walletprocesspsbt", 1, "sign" }, { "walletprocesspsbt", 3, "bip32derivs" }, @@ -208,6 +210,7 @@ static const CRPCConvertParam vRPCConvertParams[] = { "send", 4, "conf_target"}, { "send", 4, "replaceable"}, { "send", 4, "solving_data"}, + { "send", 4, "max_tx_weight"}, { "sendall", 0, "recipients" }, { "sendall", 1, "conf_target" }, { "sendall", 3, "fee_rate"}, diff --git a/src/wallet/coincontrol.h b/src/wallet/coincontrol.h index b2f813383dc5a..d36314312ad1f 100644 --- a/src/wallet/coincontrol.h +++ b/src/wallet/coincontrol.h @@ -115,6 +115,8 @@ class CCoinControl std::optional m_locktime; //! Version std::optional m_version; + //! Caps weight of resulting tx + std::optional m_max_tx_weight{std::nullopt}; CCoinControl(); diff --git a/src/wallet/coinselection.cpp b/src/wallet/coinselection.cpp index c37d42d22a4fb..a54d1a46685f1 100644 --- a/src/wallet/coinselection.cpp +++ b/src/wallet/coinselection.cpp @@ -597,11 +597,12 @@ util::Result SelectCoinsSRD(const std::vector& utx * nTargetValue, with indices corresponding to groups. If the ith * entry is true, that means the ith group in groups was selected. * param@[out] nBest Total amount of subset chosen that is closest to nTargetValue. + * paramp[in] max_selection_weight The maximum allowed weight for a selection result to be valid. * param@[in] iterations Maximum number of tries. */ static void ApproximateBestSubset(FastRandomContext& insecure_rand, const std::vector& groups, const CAmount& nTotalLower, const CAmount& nTargetValue, - std::vector& vfBest, CAmount& nBest, int iterations = 1000) + std::vector& vfBest, CAmount& nBest, int max_selection_weight, int iterations = 1000) { std::vector vfIncluded; @@ -613,6 +614,7 @@ static void ApproximateBestSubset(FastRandomContext& insecure_rand, const std::v { vfIncluded.assign(groups.size(), false); CAmount nTotal = 0; + int selected_coins_weight{0}; bool fReachedTarget = false; for (int nPass = 0; nPass < 2 && !fReachedTarget; nPass++) { @@ -627,9 +629,9 @@ static void ApproximateBestSubset(FastRandomContext& insecure_rand, const std::v if (nPass == 0 ? insecure_rand.randbool() : !vfIncluded[i]) { nTotal += groups[i].GetSelectionAmount(); + selected_coins_weight += groups[i].m_weight; vfIncluded[i] = true; - if (nTotal >= nTargetValue) - { + if (nTotal >= nTargetValue && selected_coins_weight <= max_selection_weight) { fReachedTarget = true; // If the total is between nTargetValue and nBest, it's our new best // approximation. @@ -639,6 +641,7 @@ static void ApproximateBestSubset(FastRandomContext& insecure_rand, const std::v vfBest = vfIncluded; } nTotal -= groups[i].GetSelectionAmount(); + selected_coins_weight -= groups[i].m_weight; vfIncluded[i] = false; } } @@ -652,6 +655,7 @@ util::Result KnapsackSolver(std::vector& groups, c { SelectionResult result(nTargetValue, SelectionAlgorithm::KNAPSACK); + bool max_weight_exceeded{false}; // List of values less than target std::optional lowest_larger; // Groups with selection amount smaller than the target and any change we might produce. @@ -662,6 +666,10 @@ util::Result KnapsackSolver(std::vector& groups, c Shuffle(groups.begin(), groups.end(), rng); for (const OutputGroup& group : groups) { + if (group.m_weight > max_selection_weight) { + max_weight_exceeded = true; + continue; + } if (group.GetSelectionAmount() == nTargetValue) { result.AddInput(group); return result; @@ -677,11 +685,18 @@ util::Result KnapsackSolver(std::vector& groups, c for (const auto& group : applicable_groups) { result.AddInput(group); } - return result; + if (result.GetWeight() <= max_selection_weight) return result; + else max_weight_exceeded = true; + + // Try something else + result.Clear(); } if (nTotalLower < nTargetValue) { - if (!lowest_larger) return util::Error(); + if (!lowest_larger) { + if (max_weight_exceeded) return ErrorMaxWeightExceeded(); + return util::Error(); + } result.AddInput(*lowest_larger); return result; } @@ -691,9 +706,9 @@ util::Result KnapsackSolver(std::vector& groups, c std::vector vfBest; CAmount nBest; - ApproximateBestSubset(rng, applicable_groups, nTotalLower, nTargetValue, vfBest, nBest); + ApproximateBestSubset(rng, applicable_groups, nTotalLower, nTargetValue, vfBest, nBest, max_selection_weight); if (nBest != nTargetValue && nTotalLower >= nTargetValue + change_target) { - ApproximateBestSubset(rng, applicable_groups, nTotalLower, nTargetValue + change_target, vfBest, nBest); + ApproximateBestSubset(rng, applicable_groups, nTotalLower, nTargetValue + change_target, vfBest, nBest, max_selection_weight); } // If we have a bigger coin and (either the stochastic approximation didn't find a good solution, @@ -728,7 +743,7 @@ util::Result KnapsackSolver(std::vector& groups, c LogPrint(BCLog::SELECTCOINS, "%stotal %s\n", log_message, FormatMoney(nBest)); } } - + Assume(result.GetWeight() <= max_selection_weight); return result; } diff --git a/src/wallet/coinselection.h b/src/wallet/coinselection.h index 1f234427d2c6c..8a81cfc268213 100644 --- a/src/wallet/coinselection.h +++ b/src/wallet/coinselection.h @@ -174,10 +174,13 @@ struct CoinSelectionParams { * 1) Received from other wallets, 2) replacing other txs, 3) that have been replaced. */ bool m_include_unsafe_inputs = false; + /** The maximum weight for this transaction. */ + std::optional m_max_tx_weight{std::nullopt}; CoinSelectionParams(FastRandomContext& rng_fast, int change_output_size, int change_spend_size, CAmount min_change_target, CFeeRate effective_feerate, - CFeeRate long_term_feerate, CFeeRate discard_feerate, int tx_noinputs_size, bool avoid_partial) + CFeeRate long_term_feerate, CFeeRate discard_feerate, int tx_noinputs_size, bool avoid_partial, + std::optional max_tx_weight = std::nullopt) : rng_fast{rng_fast}, change_output_size(change_output_size), change_spend_size(change_spend_size), @@ -186,7 +189,8 @@ struct CoinSelectionParams { m_long_term_feerate(long_term_feerate), m_discard_feerate(discard_feerate), tx_noinputs_size(tx_noinputs_size), - m_avoid_partial_spends(avoid_partial) + m_avoid_partial_spends(avoid_partial), + m_max_tx_weight(max_tx_weight) { } CoinSelectionParams(FastRandomContext& rng_fast) diff --git a/src/wallet/rpc/spend.cpp b/src/wallet/rpc/spend.cpp index ac2a4826f05d9..8ea51e65c7897 100644 --- a/src/wallet/rpc/spend.cpp +++ b/src/wallet/rpc/spend.cpp @@ -542,6 +542,7 @@ CreatedTransactionResult FundTransaction(CWallet& wallet, const CMutableTransact {"minconf", UniValueType(UniValue::VNUM)}, {"maxconf", UniValueType(UniValue::VNUM)}, {"input_weights", UniValueType(UniValue::VARR)}, + {"max_tx_weight", UniValueType(UniValue::VNUM)}, }, true, true); @@ -701,6 +702,10 @@ CreatedTransactionResult FundTransaction(CWallet& wallet, const CMutableTransact } } + if (options.exists("max_tx_weight")) { + coinControl.m_max_tx_weight = options["max_tx_weight"].getInt(); + } + if (recipients.empty()) throw JSONRPCError(RPC_INVALID_PARAMETER, "TX must have at least one output"); @@ -786,6 +791,8 @@ RPCHelpMan fundrawtransaction() }, }, }, + {"max_tx_weight", RPCArg::Type::NUM, RPCArg::Default{MAX_STANDARD_TX_WEIGHT}, "The maximum acceptable transaction weight.\n" + "Transaction building will fail if this can not be satisfied."}, }, FundTxDoc()), RPCArgOptions{ @@ -1240,6 +1247,8 @@ RPCHelpMan send() {"vout_index", RPCArg::Type::NUM, RPCArg::Optional::OMITTED, "The zero-based output index, before a change output is added."}, }, }, + {"max_tx_weight", RPCArg::Type::NUM, RPCArg::Default{MAX_STANDARD_TX_WEIGHT}, "The maximum acceptable transaction weight.\n" + "Transaction building will fail if this can not be satisfied."}, }, FundTxDoc()), RPCArgOptions{.oneline_description="options"}}, @@ -1287,6 +1296,9 @@ RPCHelpMan send() // Automatically select coins, unless at least one is manually selected. Can // be overridden by options.add_inputs. coin_control.m_allow_other_inputs = rawTx.vin.size() == 0; + if (options.exists("max_tx_weight")) { + coin_control.m_max_tx_weight = options["max_tx_weight"].getInt(); + } SetOptionsInputWeights(options["inputs"], options); // Clear tx.vout since it is not meant to be used now that we are passing outputs directly. // This sets us up for a future PR to completely remove tx from the function signature in favor of passing inputs directly @@ -1697,6 +1709,8 @@ RPCHelpMan walletcreatefundedpsbt() {"vout_index", RPCArg::Type::NUM, RPCArg::Optional::OMITTED, "The zero-based output index, before a change output is added."}, }, }, + {"max_tx_weight", RPCArg::Type::NUM, RPCArg::Default{MAX_STANDARD_TX_WEIGHT}, "The maximum acceptable transaction weight.\n" + "Transaction building will fail if this can not be satisfied."}, }, FundTxDoc()), RPCArgOptions{.oneline_description="options"}}, diff --git a/src/wallet/spend.cpp b/src/wallet/spend.cpp index e0546c6210a8f..1ad570442e0f5 100644 --- a/src/wallet/spend.cpp +++ b/src/wallet/spend.cpp @@ -696,7 +696,12 @@ util::Result ChooseSelectionResult(interfaces::Chain& chain, co }; // Maximum allowed weight for selected coins. - int max_selection_weight = MAX_STANDARD_TX_WEIGHT - (coin_selection_params.tx_noinputs_size * WITNESS_SCALE_FACTOR); + int max_transaction_weight = coin_selection_params.m_max_tx_weight.value_or(MAX_STANDARD_TX_WEIGHT); + int tx_weight_no_input = coin_selection_params.tx_noinputs_size * WITNESS_SCALE_FACTOR; + int max_selection_weight = max_transaction_weight - tx_weight_no_input; + if (max_selection_weight <= 0) { + return util::Error{_("Maximum transaction weight is less than transaction weight without inputs")}; + } // SFFO frequently causes issues in the context of changeless input sets: skip BnB when SFFO is active if (!coin_selection_params.m_subtract_fee_outputs) { @@ -706,7 +711,11 @@ util::Result ChooseSelectionResult(interfaces::Chain& chain, co } // Deduct change weight because remaining Coin Selection algorithms can create change output - max_selection_weight -= (coin_selection_params.change_output_size * WITNESS_SCALE_FACTOR); + int change_outputs_weight = coin_selection_params.change_output_size * WITNESS_SCALE_FACTOR; + max_selection_weight -= change_outputs_weight; + if (max_selection_weight < 0 && results.empty()) { + return util::Error{_("Maximum transaction weight is too low, can not accommodate change output")}; + } // The knapsack solver has some legacy behavior where it will spend dust outputs. We retain this behavior, so don't filter for positive only here. if (auto knapsack_result{KnapsackSolver(groups.mixed_group, nTargetValue, coin_selection_params.m_min_change_target, coin_selection_params.rng_fast, max_selection_weight)}) { @@ -801,7 +810,7 @@ util::Result SelectCoins(const CWallet& wallet, CoinsResult& av coin_selection_params.m_change_fee); // Verify we haven't exceeded the maximum allowed weight - int max_inputs_weight = MAX_STANDARD_TX_WEIGHT - (coin_selection_params.tx_noinputs_size * WITNESS_SCALE_FACTOR); + int max_inputs_weight = coin_selection_params.m_max_tx_weight.value_or(MAX_STANDARD_TX_WEIGHT) - (coin_selection_params.tx_noinputs_size * WITNESS_SCALE_FACTOR); if (op_selection_result->GetWeight() > max_inputs_weight) { return util::Error{_("The combination of the pre-selected inputs and the wallet automatic inputs selection exceeds the transaction maximum weight. " "Please try sending a smaller amount or manually consolidating your wallet's UTXOs")}; @@ -1002,7 +1011,11 @@ static util::Result CreateTransactionInternal( CoinSelectionParams coin_selection_params{rng_fast}; // Parameters for coin selection, init with dummy coin_selection_params.m_avoid_partial_spends = coin_control.m_avoid_partial_spends; coin_selection_params.m_include_unsafe_inputs = coin_control.m_include_unsafe_inputs; - + coin_selection_params.m_max_tx_weight = coin_control.m_max_tx_weight.value_or(MAX_STANDARD_TX_WEIGHT); + int minimum_tx_weight = MIN_STANDARD_TX_NONWITNESS_SIZE * WITNESS_SCALE_FACTOR; + if (coin_selection_params.m_max_tx_weight.value() < minimum_tx_weight || coin_selection_params.m_max_tx_weight.value() > MAX_STANDARD_TX_WEIGHT) { + return util::Error{strprintf(_("Maximum transaction weight must be between %d and %d"), minimum_tx_weight, MAX_STANDARD_TX_WEIGHT)}; + } // Set the long term feerate estimate to the wallet's consolidate feerate coin_selection_params.m_long_term_feerate = wallet.m_consolidate_feerate; diff --git a/src/wallet/test/fuzz/coinselection.cpp b/src/wallet/test/fuzz/coinselection.cpp index 72975c3d681e3..209c87fd422bd 100644 --- a/src/wallet/test/fuzz/coinselection.cpp +++ b/src/wallet/test/fuzz/coinselection.cpp @@ -256,29 +256,34 @@ FUZZ_TARGET(coinselection) (void)group.EligibleForSpending(filter); } + int max_selection_weight = fuzzed_data_provider.ConsumeIntegralInRange(0, std::numeric_limits::max()); + // Run coinselection algorithms auto result_bnb = coin_params.m_subtract_fee_outputs ? util::Error{Untranslated("BnB disabled when SFFO is enabled")} : - SelectCoinsBnB(group_pos, target, coin_params.m_cost_of_change, MAX_STANDARD_TX_WEIGHT); + SelectCoinsBnB(group_pos, target, coin_params.m_cost_of_change, max_selection_weight); if (result_bnb) { assert(result_bnb->GetChange(coin_params.min_viable_change, coin_params.m_change_fee) == 0); assert(result_bnb->GetSelectedValue() >= target); + assert(result_bnb->GetWeight() <= max_selection_weight); (void)result_bnb->GetShuffledInputVector(); (void)result_bnb->GetInputSet(); } - auto result_srd = SelectCoinsSRD(group_pos, target, coin_params.m_change_fee, fast_random_context, MAX_STANDARD_TX_WEIGHT); + auto result_srd = SelectCoinsSRD(group_pos, target, coin_params.m_change_fee, fast_random_context, max_selection_weight); if (result_srd) { assert(result_srd->GetSelectedValue() >= target); assert(result_srd->GetChange(CHANGE_LOWER, coin_params.m_change_fee) > 0); // Demonstrate that SRD creates change of at least CHANGE_LOWER + assert(result_srd->GetWeight() <= max_selection_weight); result_srd->RecalculateWaste(coin_params.min_viable_change, coin_params.m_cost_of_change, coin_params.m_change_fee); (void)result_srd->GetShuffledInputVector(); (void)result_srd->GetInputSet(); } CAmount change_target{GenerateChangeTarget(target, coin_params.m_change_fee, fast_random_context)}; - auto result_knapsack = KnapsackSolver(group_all, target, change_target, fast_random_context, MAX_STANDARD_TX_WEIGHT); + auto result_knapsack = KnapsackSolver(group_all, target, change_target, fast_random_context, max_selection_weight); if (result_knapsack) { assert(result_knapsack->GetSelectedValue() >= target); + assert(result_knapsack->GetWeight() <= max_selection_weight); result_knapsack->RecalculateWaste(coin_params.min_viable_change, coin_params.m_cost_of_change, coin_params.m_change_fee); (void)result_knapsack->GetShuffledInputVector(); (void)result_knapsack->GetInputSet(); diff --git a/test/functional/rpc_psbt.py b/test/functional/rpc_psbt.py index 6ee7e56886816..111ca63618256 100755 --- a/test/functional/rpc_psbt.py +++ b/test/functional/rpc_psbt.py @@ -8,6 +8,9 @@ from itertools import product from random import randbytes +from test_framework.blocktools import ( + MAX_STANDARD_TX_WEIGHT, +) from test_framework.descriptors import descsum_create from test_framework.key import H_POINT from test_framework.messages import ( @@ -16,6 +19,7 @@ CTxIn, CTxOut, MAX_BIP125_RBF_SEQUENCE, + WITNESS_SCALE_FACTOR, ) from test_framework.psbt import ( PSBT, @@ -30,6 +34,7 @@ PSBT_OUT_TAP_TREE, ) from test_framework.script import CScript, OP_TRUE +from test_framework.script_util import MIN_STANDARD_TX_NONWITNESS_SIZE from test_framework.test_framework import BitcoinTestFramework from test_framework.util import ( assert_approx, @@ -186,6 +191,46 @@ def run_test(self): # Create and fund a raw tx for sending 10 BTC psbtx1 = self.nodes[0].walletcreatefundedpsbt([], {self.nodes[2].getnewaddress():10})['psbt'] + self.log.info("Test for invalid maximum transaction weights") + dest_arg = [{self.nodes[0].getnewaddress(): 1}] + min_tx_weight = MIN_STANDARD_TX_NONWITNESS_SIZE * WITNESS_SCALE_FACTOR + assert_raises_rpc_error(-4, f"Maximum transaction weight must be between {min_tx_weight} and {MAX_STANDARD_TX_WEIGHT}", self.nodes[0].walletcreatefundedpsbt, [], dest_arg, 0, {"max_tx_weight": -1}) + assert_raises_rpc_error(-4, f"Maximum transaction weight must be between {min_tx_weight} and {MAX_STANDARD_TX_WEIGHT}", self.nodes[0].walletcreatefundedpsbt, [], dest_arg, 0, {"max_tx_weight": 0}) + assert_raises_rpc_error(-4, f"Maximum transaction weight must be between {min_tx_weight} and {MAX_STANDARD_TX_WEIGHT}", self.nodes[0].walletcreatefundedpsbt, [], dest_arg, 0, {"max_tx_weight": MAX_STANDARD_TX_WEIGHT + 1}) + + # Base transaction vsize: version (4) + locktime (4) + input count (1) + witness overhead (1) = 10 vbytes + base_tx_vsize = 10 + # One P2WPKH output vsize: outpoint (31 vbytes) + p2wpkh_output_vsize = 31 + # 1 vbyte for output count + output_count = 1 + tx_weight_without_inputs = (base_tx_vsize + output_count + p2wpkh_output_vsize) * WITNESS_SCALE_FACTOR + # min_tx_weight is greater than transaction weight without inputs + assert_greater_than(min_tx_weight, tx_weight_without_inputs) + + # In order to test for when the passed max weight is less than the transaction weight without inputs + # Define destination with two outputs. + dest_arg_large = [{self.nodes[0].getnewaddress(): 1}, {self.nodes[0].getnewaddress(): 1}] + large_tx_vsize_without_inputs = base_tx_vsize + output_count + (p2wpkh_output_vsize * 2) + large_tx_weight_without_inputs = large_tx_vsize_without_inputs * WITNESS_SCALE_FACTOR + assert_greater_than(large_tx_weight_without_inputs, min_tx_weight) + # Test for max_tx_weight less than Transaction weight without inputs + assert_raises_rpc_error(-4, "Maximum transaction weight is less than transaction weight without inputs", self.nodes[0].walletcreatefundedpsbt, [], dest_arg_large, 0, {"max_tx_weight": min_tx_weight}) + assert_raises_rpc_error(-4, "Maximum transaction weight is less than transaction weight without inputs", self.nodes[0].walletcreatefundedpsbt, [], dest_arg_large, 0, {"max_tx_weight": large_tx_weight_without_inputs}) + + # Test for max_tx_weight just enough to include inputs but not change output + assert_raises_rpc_error(-4, "Maximum transaction weight is too low, can not accommodate change output", self.nodes[0].walletcreatefundedpsbt, [], dest_arg_large, 0, {"max_tx_weight": (large_tx_vsize_without_inputs + 1) * WITNESS_SCALE_FACTOR}) + self.log.info("Test that a funded PSBT is always faithful to max_tx_weight option") + large_tx_vsize_with_change = large_tx_vsize_without_inputs + p2wpkh_output_vsize + # It's enough but won't accommodate selected input size + assert_raises_rpc_error(-4, "The inputs size exceeds the maximum weight", self.nodes[0].walletcreatefundedpsbt, [], dest_arg_large, 0, {"max_tx_weight": (large_tx_vsize_with_change) * WITNESS_SCALE_FACTOR}) + + max_tx_weight_sufficient = 1000 # 1k vbytes is enough + psbt = self.nodes[0].walletcreatefundedpsbt(outputs=dest_arg,locktime=0, options={"max_tx_weight": max_tx_weight_sufficient})["psbt"] + weight = self.nodes[0].decodepsbt(psbt)["tx"]["weight"] + # ensure the transaction's weight is below the specified max_tx_weight. + assert_greater_than_or_equal(max_tx_weight_sufficient, weight) + # If inputs are specified, do not automatically add more: utxo1 = self.nodes[0].listunspent()[0] assert_raises_rpc_error(-4, "The preselected coins total amount does not cover the transaction target. " diff --git a/test/functional/test_framework/blocktools.py b/test/functional/test_framework/blocktools.py index f0dc866f692a8..338b7fa3b00c9 100644 --- a/test/functional/test_framework/blocktools.py +++ b/test/functional/test_framework/blocktools.py @@ -48,6 +48,7 @@ MAX_BLOCK_SIGOPS = 20000 MAX_BLOCK_SIGOPS_WEIGHT = MAX_BLOCK_SIGOPS * WITNESS_SCALE_FACTOR +MAX_STANDARD_TX_WEIGHT = 400000 # Genesis block time (regtest) TIME_GENESIS_BLOCK = 1296688602