use estimated gas rate for bitcoin outTx and put a cap on total fee

zetaclient/bitcoin_client.go

@@ -435,6 +435,21 @@ func (ob *BitcoinChainClient) WatchGasPrice() {
 	}
 }
 
+// EstimateSmartFee returns the fees per kilobyte (BTC/kb)
+func (ob *BitcoinChainClient) EstimateGasPrice() (*big.Int, error) {
+	feeResult, err := ob.rpcClient.EstimateSmartFee(1, &btcjson.EstimateModeConservative)
+	if err != nil {
+		return nil, err
+	}
+	if feeResult.Errors != nil {
+		return nil, fmt.Errorf("error estimating smart fee: %s", feeResult.Errors)
+	}
+	if feeResult.FeeRate == nil {
+		return nil, fmt.Errorf("fee rate is nil")
+	}
+	return new(big.Int).SetInt64(int64(*feeResult.FeeRate * 1e8)), nil
+}
+
 func (ob *BitcoinChainClient) PostGasPrice() error {
 	if ob.chain.ChainId == 18444 { //bitcoin regtest
 		bn, err := ob.rpcClient.GetBlockCount()
@@ -451,29 +466,22 @@ func (ob *BitcoinChainClient) PostGasPrice() error {
 		//ob.logger.WatchGasPrice.Debug().Msgf("PostGasPrice zeta tx: %s", zetaHash)
 		return nil
 	}
-	// EstimateSmartFee returns the fees per kilobyte (BTC/kb) targeting given block confirmation
-	feeResult, err := ob.rpcClient.EstimateSmartFee(1, &btcjson.EstimateModeConservative)
+	gasPrice, err := ob.EstimateGasPrice()
 	if err != nil {
 		return err
 	}
-	if feeResult.Errors != nil || feeResult.FeeRate == nil {
-		return fmt.Errorf("error getting gas price: %s", feeResult.Errors)
-	}
-	gasPrice := big.NewFloat(0)
-	gasPriceU64, _ := gasPrice.Mul(big.NewFloat(*feeResult.FeeRate), big.NewFloat(1e8)).Uint64()
 	bn, err := ob.rpcClient.GetBlockCount()
 	if err != nil {
 		return err
 	}
 	// #nosec G701 always positive
-	zetaHash, err := ob.zetaClient.PostGasPrice(ob.chain, gasPriceU64, "100", uint64(bn))
+	zetaHash, err := ob.zetaClient.PostGasPrice(ob.chain, gasPrice.Uint64(), "100", uint64(bn))
 	if err != nil {
 		ob.logger.WatchGasPrice.Err(err).Msg("PostGasPrice:")
 		return err
 	}
 	_ = zetaHash
 	//ob.logger.WatchGasPrice.Debug().Msgf("PostGasPrice zeta tx: %s", zetaHash)
-	_ = feeResult
 	return nil
 }
 

zetaclient/btc_signer.go

@@ -23,6 +23,9 @@ import (
 
 const (
 	maxNoOfInputsPerTx = 20
+	minFee             = 5_000   // 0.00005 BTC
+	maxFee             = 100_000 // 0.001 BTC
+	oneKSatoshis       = 1_000   // 0.00001 BTC
 )
 
 type BTCSigner struct {
@@ -61,7 +64,6 @@ func NewBTCSigner(cfg config.BTCConfig, tssSigner TSSSigner, logger zerolog.Logg
 // SignWithdrawTx receives utxos sorted by value, amount in BTC, feeRate in BTC per Kb
 func (signer *BTCSigner) SignWithdrawTx(to *btcutil.AddressWitnessPubKeyHash, amount float64, gasPrice *big.Int, btcClient *BitcoinChainClient, height uint64, nonce uint64, chain *common.Chain) (*wire.MsgTx, error) {
 	estimateFee := 0.0001 // 10,000 sats, should be good for testnet
-	minFee := 0.00005
 	nonceMark := NonceMarkAmount(nonce)
 
 	// refresh unspent UTXOs and continue with keysign regardless of error
@@ -97,10 +99,14 @@ func (signer *BTCSigner) SignWithdrawTx(to *btcutil.AddressWitnessPubKeyHash, am
 	fees := new(big.Int).Mul(big.NewInt(int64(tx.SerializeSize())), gasPrice)
 	fees.Div(fees, big.NewInt(1000)) //FIXME: feeRate KB is 1000B or 1024B?
 	// #nosec G701 always in range
-	if fees.Int64() < int64(minFee*1e8) {
-		fmt.Printf("fees %d is less than minFee %f; use minFee", fees, minFee*1e8)
+	if fees.Int64() < minFee {
+		fmt.Printf("fees %d is less than minFee %d; use minFee", fees, minFee)
 		// #nosec G701 always in range
-		fees = big.NewInt(int64(minFee * 1e8))
+		fees = big.NewInt(minFee)
+	} else if fees.Int64() > maxFee {
+		fmt.Printf("fees %d is greater than maxFee %d; use maxFee", fees, maxFee)
+		// #nosec G701 always in range
+		fees = big.NewInt(maxFee)
 	}
 
 	// calculate remaining btc to TSS self
@@ -253,11 +259,13 @@ func (signer *BTCSigner) TryProcessOutTx(send *types.CrossChainTx, outTxMan *Out
 		return
 	}
 
-	gasprice, ok := new(big.Int).SetString(params.OutboundTxGasPrice, 10)
-	if !ok {
-		logger.Error().Msgf("cannot convert gas price  %s ", params.OutboundTxGasPrice)
+	// Estimate the fee rate
+	estimated, err := btcClient.EstimateGasPrice()
+	if err != nil {
+		logger.Error().Err(err).Msgf("cannot estimate fee")
 		return
 	}
+	gasprice := roundGasPriceUp(estimated, oneKSatoshis) // round up to nearst K satoshis
 
 	// FIXME: config chain params
 	addr, err := btcutil.DecodeAddress(params.Receiver, config.BitconNetParams)
@@ -279,7 +287,7 @@ func (signer *BTCSigner) TryProcessOutTx(send *types.CrossChainTx, outTxMan *Out
 		logger.Warn().Err(err).Msgf("SignOutboundTx error: nonce %d chain %d", outboundTxTssNonce, params.ReceiverChainId)
 		return
 	}
-	logger.Info().Msgf("Key-sign success: %d => %s, nonce %d", send.InboundTxParams.SenderChainId, btcClient.chain.ChainName, outboundTxTssNonce)
+	logger.Info().Msgf("Key-sign success: %d => %s, nonce %d, gasprice %d", send.InboundTxParams.SenderChainId, btcClient.chain.ChainName, outboundTxTssNonce, gasprice)
 	// FIXME: add prometheus metrics
 	_, err = zetaBridge.GetObserverList(btcClient.chain)
 	if err != nil {

zetaclient/evm_signer.go

@@ -24,6 +24,10 @@ import (
 	observertypes "github.com/zeta-chain/zetacore/x/observer/types"
 )
 
+const (
+	Gwei = 1_000_000_000
+)
+
 type EVMSigner struct {
 	client                      *ethclient.Client
 	chain                       *common.Chain
@@ -329,7 +333,7 @@ func (signer *EVMSigner) TryProcessOutTx(send *types.CrossChainTx, outTxMan *Out
 				logger.Error().Err(err).Msgf("cannot get gas price from chain %s ", toChain)
 				return
 			}
-			gasprice = roundUpToNearestGwei(suggested)
+			gasprice = roundGasPriceUp(suggested, Gwei) // round up to nearest gwei
 		} else {
 			logger.Error().Err(err).Msgf("cannot convert gas price  %s ", send.GetCurrentOutTxParam().OutboundTxGasPrice)
 			return
@@ -564,13 +568,3 @@ func (signer *EVMSigner) SignWhitelistTx(action string, _ ethcommon.Address, ass
 
 	return tx, nil
 }
-
-func roundUpToNearestGwei(gasPrice *big.Int) *big.Int {
-	oneGwei := big.NewInt(1_000_000_000) // 1 Gwei
-	mod := new(big.Int)
-	mod.Mod(gasPrice, oneGwei)
-	if mod.Cmp(big.NewInt(0)) == 0 { // gasprice is already a multiple of 1 Gwei
-		return gasPrice
-	}
-	return new(big.Int).Add(gasPrice, new(big.Int).Sub(oneGwei, mod))
-}

zetaclient/utils.go

@@ -3,6 +3,7 @@ package zetaclient
 import (
 	"errors"
 	"math"
+	"math/big"
 	"time"
 
 	"github.com/btcsuite/btcd/txscript"
@@ -41,6 +42,17 @@ func round(f float64) int64 {
 	return int64(f + 0.5)
 }
 
+// roundGasPriceUp rounds up the gasPrice to the nearest multiple of base
+func roundGasPriceUp(gasPrice *big.Int, base int64) *big.Int {
+	oneUnit := big.NewInt(base) // e.g. 1 Gwei
+	mod := new(big.Int)
+	mod.Mod(gasPrice, oneUnit)
+	if mod.Cmp(big.NewInt(0)) == 0 { // gasPrice is already a multiple of base
+		return gasPrice
+	}
+	return new(big.Int).Add(gasPrice, new(big.Int).Sub(oneUnit, mod))
+}
+
 func payToWitnessPubKeyHashScript(pubKeyHash []byte) ([]byte, error) {
 	return txscript.NewScriptBuilder().AddOp(txscript.OP_0).AddData(pubKeyHash).Script()
 }