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Add Fees to Tx from wallets fund when sweeping assets #8

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Add Fees to Tx from wallets fund when sweeping assets #8

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086936d
BRWalletAddFeeToTransaction for sweep assets
Feb 27, 2020
460e68f
BRWalletAddFeeToTransaction
Feb 28, 2020
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73 changes: 72 additions & 1 deletion core/BRWallet.c
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Original file line number Diff line number Diff line change
Expand Up @@ -543,6 +543,77 @@ BRTransaction *BRWalletCreateTransaction(BRWallet *wallet, uint64_t amount, cons
return BRWalletCreateTxForOutputs(wallet, &o, 1);
}

// this method is used in sweeping assets, fees must be added from current wallet
// adds one output to given transaction for fees to a constructed transaction
// in case of insufficient fees, transaction is freed by calling TransactionFree()
void BRWalletAddFeeToTransaction(BRWallet *wallet, BRTransaction *transaction) {

BRTransaction *tx;
uint64_t feeAmount, balance = 0, minAmount;
size_t i, j, cpfpSize = 0;
UTXO *o;
BRAddress addr = ADDRESS_NONE;
size_t outCount = 1;
const BRTxOutput *outputs;

assert(wallet != NULL);
assert(transaction != NULL);

minAmount = BRWalletMinOutputAmount(wallet);
pthread_mutex_lock(&wallet->lock);
feeAmount = _txFee(wallet->feePerKb, BRTransactionSize(transaction) + TX_OUTPUT_SIZE);

for (i = 0; i < array_count(wallet->utxos); i++) {
o = &wallet->utxos[i];
tx = BRSetGet(wallet->allTx, o);

if (!tx || tx->outputs[o->n].amount == 0 || o->n >= tx->outCount) continue;
BRTransactionAddInput(transaction, tx->txHash, o->n, tx->outputs[o->n].amount,
tx->outputs[o->n].script, tx->outputs[o->n].scriptLen, NULL, 0, TXIN_SEQUENCE);

if (BRTransactionSize(transaction) + TX_OUTPUT_SIZE > TX_MAX_SIZE) { // transaction size-in-bytes too large
BRTransactionFree(transaction);
transaction = NULL;

// check for sufficient total funds before building a smaller transaction
if (wallet->balance < _txFee(wallet->feePerKb, 10 + array_count(wallet->utxos)*TX_INPUT_SIZE +
(outCount + 1)*TX_OUTPUT_SIZE + cpfpSize)) break;
pthread_mutex_unlock(&wallet->lock);

transaction = BRWalletCreateTxForOutputs(wallet, outputs, outCount - 1); // remove last output

balance = feeAmount = 0;
pthread_mutex_lock(&wallet->lock);
break;
}

balance += tx->outputs[o->n].amount;

// fee amount after adding a change output
feeAmount = _txFee(wallet->feePerKb, BRTransactionSize(transaction) + TX_OUTPUT_SIZE + cpfpSize);

// increase fee to round off remaining wallet balance to nearest 100 satoshi
if (wallet->balance > feeAmount) feeAmount += (wallet->balance - feeAmount) % 100;

if (balance == feeAmount || balance >= feeAmount + minAmount) break;
}

pthread_mutex_unlock(&wallet->lock);

if (transaction && (outCount < 1 || balance < feeAmount)) { // no outputs/insufficient funds
BRTransactionFree(transaction);
transaction = NULL;
} else if (transaction && balance - feeAmount > minAmount) { // add change output
BRWalletUnusedAddrs(wallet, &addr, 1, 1);
uint8_t script[BRAddressScriptPubKey(NULL, 0, addr.s)];
size_t scriptLen = BRAddressScriptPubKey(script, sizeof(script), addr.s);

BRTransactionAddOutput(transaction, balance - feeAmount, script, scriptLen);
BRTransactionShuffleOutputs(transaction);
}

}

// returns an unsigned transaction that sends the specified amount from the wallet to the given address
// one asset output is added + network fees and change if any
// result must be freed by calling TransactionFree()
Expand Down Expand Up @@ -1161,7 +1232,7 @@ BRTransaction *BRWalletBurnRootAsset(BRWallet *wallet, BRAsset *asst) {
return transaction;
}

// returns an unsigned transaction that satisifes the given transaction outputs
// returns an unsigned transaction that satisfies the given transaction outputs
// result must be freed using TransactionFree()
BRTransaction *BRWalletCreateTxForOutputs(BRWallet *wallet, const BRTxOutput outputs[], size_t outCount)
{
Expand Down
12 changes: 9 additions & 3 deletions core/BRWallet.h
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Original file line number Diff line number Diff line change
Expand Up @@ -98,23 +98,29 @@ size_t BRWalletTxUnconfirmedBefore(BRWallet *wallet, BRTransaction **transaction
// current wallet balance, not including transactions known to be invalid
uint64_t BRWalletBalance(BRWallet *wallet);

// total amount spent from the wallet (exluding change)
// total amount spent from the wallet (excluding change)
uint64_t BRWalletTotalSent(BRWallet *wallet);

// total amount received by the wallet (exluding change)
// total amount received by the wallet (excluding change)
uint64_t BRWalletTotalReceived(BRWallet *wallet);

// writes unspent outputs to utxos and returns the number of outputs written, or number available if utxos is NULL
size_t BRWalletUTXOs(BRWallet *wallet, UTXO *utxos, size_t utxosCount);

// fee-per-kb of transaction size to use when creating a transaction
uint64_t BRWalletFeePerKb(BRWallet *wallet);

void BRWalletSetFeePerKb(BRWallet *wallet, uint64_t feePerKb);

// returns an unsigned transaction that sends the specified amount from the wallet to the given address
// result must be freed using TransactionFree()
BRTransaction *BRWalletCreateTransaction(BRWallet *wallet, uint64_t amount, const char *addr);

// this method is used in sweeping assets, fees must be added from current wallet
// adds one output to given transaction for fees to a constructed transaction
// in case of insufficient fees, transaction is freed by calling TransactionFree()
void BRWalletAddFeeToTransaction(BRWallet *wallet, BRTransaction *transaction);

//
//
// returns an unsigned transaction that sends the specified amount from the wallet to the given address
Expand Down Expand Up @@ -203,7 +209,7 @@ uint64_t BRWalletAmountReceivedFromTx(BRWallet *wallet, const BRTransaction *tx)
// writes the assets contained in the transaction and return the asset object count.
size_t BRWalletAssetsReceivedFromTx(BRWallet *wallet, const BRTransaction *tx, BRAsset *asset, size_t asstCount);

// returns the amount sent from the wallet by the trasaction (total wallet outputs consumed, change and fee included)
// returns the amount sent from the wallet by the transaction (total wallet outputs consumed, change and fee included)
uint64_t BRWalletAmountSentByTx(BRWallet *wallet, const BRTransaction *tx);

// returns the fee for the given transaction if all its inputs are from wallet transactions, UINT64_MAX otherwise
Expand Down