From 51d7a6921c8d6a337773f261a04301ef75ee5e3b Mon Sep 17 00:00:00 2001 From: jeffro256 Date: Sun, 14 May 2023 11:41:59 -0500 Subject: wallet: feature: transfer amount with fee included To transfer ~5 XMR to an address such that your balance drops by exactly 5 XMR, provide a `subtractfeefrom` flag to the `transfer` command. For example: transfer 76bDHojqFYiFCCYYtzTveJ8oFtmpNp3X1TgV2oKP7rHmZyFK1RvyE4r8vsJzf7SyNohMnbKT9wbcD3XUTgsZLX8LU5JBCfm 5 subtractfeefrom=all If my walet balance was exactly 30 XMR before this transaction, it will be exactly 25 XMR afterwards and the destination address will receive slightly less than 5 XMR. You can manually select which destinations fund the transaction fee and which ones do not by providing the destination index. For example: transfer 75sr8AAr... 3 74M7W4eg... 4 7AbWqDZ6... 5 subtractfeefrom=0,2 This will drop your balance by exactly 12 XMR including fees and will spread the fee cost proportionally (3:5 ratio) over destinations with addresses `75sr8AAr...` and `7AbWqDZ6...`, respectively. Disclaimer: This feature was paid for by @LocalMonero. --- src/wallet/wallet2.cpp | 164 +++++++++++++++++++++++++++++++++++++++++-------- 1 file changed, 140 insertions(+), 24 deletions(-) (limited to 'src/wallet/wallet2.cpp') diff --git a/src/wallet/wallet2.cpp b/src/wallet/wallet2.cpp index 0218c8292..96a6c6d71 100644 --- a/src/wallet/wallet2.cpp +++ b/src/wallet/wallet2.cpp @@ -10523,7 +10523,7 @@ bool wallet2::light_wallet_key_image_is_ours(const crypto::key_image& key_image, // This system allows for sending (almost) the entire balance, since it does // not generate spurious change in all txes, thus decreasing the instantaneous // usable balance. -std::vector wallet2::create_transactions_2(std::vector dsts, const size_t fake_outs_count, const uint64_t unlock_time, uint32_t priority, const std::vector& extra, uint32_t subaddr_account, std::set subaddr_indices) +std::vector wallet2::create_transactions_2(std::vector dsts, const size_t fake_outs_count, const uint64_t unlock_time, uint32_t priority, const std::vector& extra, uint32_t subaddr_account, std::set subaddr_indices, const unique_index_container& subtract_fee_from_outputs) { //ensure device is let in NONE mode in any case hw::device &hwdev = m_account.get_device(); @@ -10538,11 +10538,12 @@ std::vector wallet2::create_transactions_2(std::vector>> unused_transfers_indices_per_subaddr; std::vector>> unused_dust_indices_per_subaddr; - uint64_t needed_money; + uint64_t needed_money, total_needed_money; // 'needed_money' is the sum of the destination amounts, while 'total_needed_money' includes 'needed_money' plus the fee if not 'subtract_fee_from_outputs' uint64_t accumulated_fee, accumulated_change; struct TX { std::vector selected_transfers; std::vector dsts; + std::vector dsts_are_fee_subtractable; cryptonote::transaction tx; pending_tx ptx; size_t weight; @@ -10552,9 +10553,11 @@ std::vector wallet2::create_transactions_2(std::vector::iterator i; @@ -10564,6 +10567,7 @@ std::vector wallet2::create_transactions_2(std::vector= max_dsts) return false; dsts.push_back(de); + dsts_are_fee_subtractable.push_back(subtracting_fee); i = dsts.end() - 1; i->amount = 0; } @@ -10579,13 +10583,67 @@ std::vector wallet2::create_transactions_2(std::vector get_adjusted_dsts(uint64_t needed_fee) const + { + uint64_t dest_total = 0; + uint64_t subtractable_dest_total = 0; + std::vector subtractable_indices; + subtractable_indices.reserve(dsts.size()); + for (size_t i = 0; i < dsts.size(); ++i) + { + dest_total += dsts[i].amount; + if (dsts_are_fee_subtractable[i]) + { + subtractable_dest_total += dsts[i].amount; + subtractable_indices.push_back(i); + } + } + + if (subtractable_indices.empty()) // if subtract_fee_from_outputs is not enabled for this tx + return dsts; + + THROW_WALLET_EXCEPTION_IF(subtractable_dest_total < needed_fee, error::tx_not_possible, + subtractable_dest_total, dest_total, needed_fee); + + std::vector res = dsts; + + // subtract fees from destinations equally, rounded down, until dust is left where we subtract 1 + uint64_t subtractable_remaining = needed_fee; + auto si_it = subtractable_indices.cbegin(); + uint64_t amount_to_subtract = 0; + while (subtractable_remaining) + { + // Set the amount to subtract iterating at the beginning of the list so equal amounts are + // subtracted throughout the list of destinations. We use max(x, 1) so that we we still step + // forwards even when the amount remaining is less than the number of subtractable indices + if (si_it == subtractable_indices.cbegin()) + amount_to_subtract = std::max(subtractable_remaining / subtractable_indices.size(), 1); + + cryptonote::tx_destination_entry& d = res[*si_it]; + THROW_WALLET_EXCEPTION_IF(d.amount <= amount_to_subtract, error::zero_amount); + + subtractable_remaining -= amount_to_subtract; + d.amount -= amount_to_subtract; + ++si_it; + + // Wrap around to first subtractable index once we hit the end of the list + if (si_it == subtractable_indices.cend()) + si_it = subtractable_indices.cbegin(); + } + + return res; + } }; + std::vector txes; bool adding_fee; // true if new outputs go towards fee, rather than destinations uint64_t needed_fee, available_for_fee = 0; @@ -10608,6 +10666,14 @@ std::vector wallet2::create_transactions_2(std::vector= dsts.size(), + error::subtract_fee_from_bad_index, *subtract_fee_from_outputs.crbegin()); + + // throw if subtract_fee_from_outputs is enabled and we have too many outputs to fit into one tx + THROW_WALLET_EXCEPTION_IF(subtract_fee_from_outputs.size() && dsts.size() > BULLETPROOF_MAX_OUTPUTS - 1, + error::wallet_internal_error, "subtractfeefrom transfers cannot be split over multiple transactions yet"); + // calculate total amount being sent to all destinations // throw if total amount overflows uint64_t needed_money = 0; @@ -10635,6 +10701,7 @@ std::vector wallet2::create_transactions_2(std::vector wallet2::create_transactions_2(std::vector balance_subtotal, error::not_enough_money, + THROW_WALLET_EXCEPTION_IF(total_needed_money > balance_subtotal || min_fee > balance_subtotal, error::not_enough_money, balance_subtotal, needed_money, 0); // first check overall balance is enough, then unlocked one, so we throw distinct exceptions - THROW_WALLET_EXCEPTION_IF(needed_money + min_fee > unlocked_balance_subtotal, error::not_enough_unlocked_money, + THROW_WALLET_EXCEPTION_IF(total_needed_money > unlocked_balance_subtotal || min_fee > unlocked_balance_subtotal, error::not_enough_unlocked_money, unlocked_balance_subtotal, needed_money, 0); for (uint32_t i : subaddr_indices) @@ -10748,7 +10815,8 @@ std::vector wallet2::create_transactions_2(std::vector wallet2::create_transactions_2(std::vector* unused_transfers_indices = &unused_transfers_indices_per_subaddr[0].second; std::vector* unused_dust_indices = &unused_dust_indices_per_subaddr[0].second; @@ -10864,7 +10932,8 @@ std::vector wallet2::create_transactions_2(std::vector wallet2::create_transactions_2(std::vector 0 && !dsts.empty() && @@ -10881,7 +10951,8 @@ std::vector wallet2::create_transactions_2(std::vector wallet2::create_transactions_2(std::vector wallet2::create_transactions_2(std::vector wallet2::create_transactions_2(std::vector test_ptx.fee; ++fee_tries) { + tx_dsts = tx.get_adjusted_dsts(needed_fee); + if (use_rct) - transfer_selected_rct(tx.dsts, tx.selected_transfers, fake_outs_count, outs, valid_public_keys_cache, unlock_time, needed_fee, extra, + transfer_selected_rct(tx_dsts, tx.selected_transfers, fake_outs_count, outs, valid_public_keys_cache, unlock_time, needed_fee, extra, test_tx, test_ptx, rct_config, use_view_tags); else - transfer_selected(tx.dsts, tx.selected_transfers, fake_outs_count, outs, valid_public_keys_cache, unlock_time, needed_fee, extra, + transfer_selected(tx_dsts, tx.selected_transfers, fake_outs_count, outs, valid_public_keys_cache, unlock_time, needed_fee, extra, detail::digit_split_strategy, tx_dust_policy(::config::DEFAULT_DUST_THRESHOLD), test_tx, test_ptx, use_view_tags); txBlob = t_serializable_object_to_blob(test_ptx.tx); needed_fee = calculate_fee(use_per_byte_fee, test_ptx.tx, txBlob.size(), base_fee, fee_quantization_mask); LOG_PRINT_L2("Made an attempt at a final " << get_weight_string(test_ptx.tx, txBlob.size()) << " tx, with " << print_money(test_ptx.fee) << " fee and " << print_money(test_ptx.change_dts.amount) << " change"); - } while (needed_fee > test_ptx.fee); + }; + + THROW_WALLET_EXCEPTION_IF(fee_tries == 10, error::wallet_internal_error, + "Too many attempts to raise pending tx fee to level of needed fee"); LOG_PRINT_L2("Made a final " << get_weight_string(test_ptx.tx, txBlob.size()) << " tx, with " << print_money(test_ptx.fee) << " fee and " << print_money(test_ptx.change_dts.amount) << " change"); @@ -11061,10 +11159,13 @@ skip_tx: for (std::vector::iterator i = txes.begin(); i != txes.end(); ++i) { TX &tx = *i; + + const auto tx_dsts = tx.get_adjusted_dsts(tx.needed_fee); + cryptonote::transaction test_tx; pending_tx test_ptx; if (use_rct) { - transfer_selected_rct(tx.dsts, /* NOMOD std::vector dsts,*/ + transfer_selected_rct(tx_dsts, /* NOMOD std::vector dsts,*/ tx.selected_transfers, /* const std::list selected_transfers */ fake_outs_count, /* CONST size_t fake_outputs_count, */ tx.outs, /* MOD std::vector> &outs, */ @@ -11077,7 +11178,7 @@ skip_tx: rct_config, use_view_tags); /* const bool use_view_tags */ } else { - transfer_selected(tx.dsts, + transfer_selected(tx_dsts, tx.selected_transfers, fake_outs_count, tx.outs, @@ -11111,23 +11212,38 @@ skip_tx: ptx_vector.push_back(tx.ptx); } - THROW_WALLET_EXCEPTION_IF(!sanity_check(ptx_vector, original_dsts), error::wallet_internal_error, "Created transaction(s) failed sanity check"); + THROW_WALLET_EXCEPTION_IF(!sanity_check(ptx_vector, original_dsts, subtract_fee_from_outputs), error::wallet_internal_error, "Created transaction(s) failed sanity check"); // if we made it this far, we're OK to actually send the transactions return ptx_vector; } -bool wallet2::sanity_check(const std::vector &ptx_vector, std::vector dsts) const +bool wallet2::sanity_check(const std::vector &ptx_vector, const std::vector& dsts, const unique_index_container& subtract_fee_from_outputs) const { - MDEBUG("sanity_check: " << ptx_vector.size() << " txes, " << dsts.size() << " destinations"); + MDEBUG("sanity_check: " << ptx_vector.size() << " txes, " << dsts.size() << " destinations, subtract_fee_from_outputs " << + (subtract_fee_from_outputs.size() ? "enabled" : "disabled")); THROW_WALLET_EXCEPTION_IF(ptx_vector.empty(), error::wallet_internal_error, "No transactions"); + THROW_WALLET_EXCEPTION_IF(!subtract_fee_from_outputs.empty() && ptx_vector.size() != 1, + error::wallet_internal_error, "feature subtractfeefrom not supported for split transactions"); + + // For destinations from where the fee is subtracted, the required amount has to be at least + // target amount - (tx fee / num_subtractable + 1). +1 since fee might not be evenly divisble by + // the number of subtractble destinations. For non-subtractable destinations, we need at least + // the target amount. + const size_t num_subtractable_dests = subtract_fee_from_outputs.size(); + const uint64_t fee0 = ptx_vector[0].fee; + const uint64_t subtractable_fee_deduction = fee0 / std::max(num_subtractable_dests, 1) + 1; // check every party in there does receive at least the required amount std::unordered_map> required; - for (const auto &d: dsts) + for (size_t i = 0; i < dsts.size(); ++i) { - required[d.addr].first += d.amount; + const cryptonote::tx_destination_entry& d = dsts[i]; + const bool dest_is_subtractable = subtract_fee_from_outputs.count(i); + const uint64_t fee_deduction = dest_is_subtractable ? subtractable_fee_deduction : 0; + const uint64_t required_amount = d.amount - std::min(fee_deduction, d.amount); + required[d.addr].first += required_amount; required[d.addr].second = d.is_subaddress; } -- cgit v1.2.3