From 276c479a5fe1dd8ada8ccc5fe6def5f793afd26b Mon Sep 17 00:00:00 2001
From: catbref <misc-github@talk2dom.com>
Date: Fri, 21 Aug 2020 17:37:04 +0100
Subject: [PATCH] Refactor to allow better Bitcoin fee estimation in the
future.
---
.../java/org/qortal/controller/TradeBot.java | 56 +++++++++++++++----
src/main/java/org/qortal/crosschain/BTC.java | 14 +++++
2 files changed, 60 insertions(+), 10 deletions(-)
diff --git a/src/main/java/org/qortal/controller/TradeBot.java b/src/main/java/org/qortal/controller/TradeBot.java
index f35b1312..550df4db 100644
--- a/src/main/java/org/qortal/controller/TradeBot.java
+++ b/src/main/java/org/qortal/controller/TradeBot.java
@@ -63,7 +63,8 @@ public class TradeBot {
private static final Logger LOGGER = LogManager.getLogger(TradeBot.class);
private static final Random RANDOM = new SecureRandom();
- private static final long FEE_AMOUNT = 5000L;
+
+ private static final long P2SH_B_OUTPUT_AMOUNT = 1000L; // P2SH-B output amount needs to be higher than the dust threshold (3000 sats/kB).
private static TradeBot instance;
@@ -233,7 +234,7 @@ public class TradeBot {
byte[] tradeForeignPublicKeyHash = Crypto.hash160(tradeForeignPublicKey);
byte[] receivingPublicKeyHash = Base58.decode(receivingAddress); // Actually the whole address, not just PKH
- // We need to generate lockTime-A: halfway of refundTimeout from now
+ // We need to generate lockTime-A: add tradeTimeout to now
int lockTimeA = crossChainTradeData.tradeTimeout * 60 + (int) (NTP.getTime() / 1000L);
TradeBotData tradeBotData = new TradeBotData(tradePrivateKey, TradeBotData.State.ALICE_WAITING_FOR_P2SH_A,
@@ -246,7 +247,14 @@ public class TradeBot {
// Check we have enough funds via xprv58 to fund both P2SHs to cover expectedBitcoin
String tradeForeignAddress = BTC.getInstance().pkhToAddress(tradeForeignPublicKeyHash);
- long totalFundsRequired = crossChainTradeData.expectedBitcoin + FEE_AMOUNT /* P2SH-A */ + FEE_AMOUNT /* P2SH-B */;
+ Long estimatedFee = BTC.getInstance().estimateFee(lockTimeA * 1000L);
+ if (estimatedFee == null) {
+ LOGGER.debug(() -> String.format("Couldn't estimate Bitcoin fees?"));
+ return ResponseResult.BTC_NETWORK_ISSUE;
+ }
+
+ long totalFundsRequired = crossChainTradeData.expectedBitcoin + estimatedFee /* P2SH-A */
+ + P2SH_B_OUTPUT_AMOUNT + estimatedFee /* P2SH-B */;
Transaction fundingCheckTransaction = BTC.getInstance().buildSpend(xprv58, tradeForeignAddress, totalFundsRequired);
if (fundingCheckTransaction == null)
@@ -257,7 +265,7 @@ public class TradeBot {
String p2shAddress = BTC.getInstance().deriveP2shAddress(redeemScriptBytes);
// Fund P2SH-A
- Transaction p2shFundingTransaction = BTC.getInstance().buildSpend(tradeBotData.getXprv58(), p2shAddress, crossChainTradeData.expectedBitcoin + FEE_AMOUNT);
+ Transaction p2shFundingTransaction = BTC.getInstance().buildSpend(tradeBotData.getXprv58(), p2shAddress, crossChainTradeData.expectedBitcoin + estimatedFee);
if (p2shFundingTransaction == null) {
LOGGER.warn(() -> String.format("Unable to build P2SH-A funding transaction - lack of funds?"));
return ResponseResult.BTC_BALANCE_ISSUE;
@@ -539,9 +547,23 @@ public class TradeBot {
byte[] redeemScript = BTCP2SH.buildScript(aliceForeignPublicKeyHash, lockTimeA, tradeBotData.getTradeForeignPublicKeyHash(), hashOfSecretA);
String p2shAddress = BTC.getInstance().deriveP2shAddress(redeemScript);
+ Long estimatedFee = BTC.getInstance().estimateFee(lockTimeA * 1000L);
+ if (estimatedFee == null) {
+ LOGGER.debug(() -> String.format("Couldn't estimate Bitcoin fees?"));
+ // Not worth trying other MESSAGEs... give up for now
+ return;
+ }
+
+ final long minimumBalance = tradeBotData.getBitcoinAmount() + estimatedFee;
Long balance = BTC.getInstance().getBalance(p2shAddress);
- if (balance == null || balance < tradeBotData.getBitcoinAmount())
+ if (balance == null || balance < minimumBalance) {
+ // P2SH-A has no, or insufficient, balance
+ if (balance != null && balance > 0)
+ LOGGER.debug(() -> String.format("P2SH-A %s balance %s lower than expected %s", p2shAddress, BTC.format(balance), BTC.format(minimumBalance)));
+
+ // There might be another MESSAGE from someone else with an actually funded P2SH-A...
continue;
+ }
// Good to go - send MESSAGE to AT
@@ -694,7 +716,13 @@ public class TradeBot {
byte[] redeemScriptBytes = BTCP2SH.buildScript(tradeBotData.getTradeForeignPublicKeyHash(), lockTimeB, crossChainTradeData.creatorBitcoinPKH, crossChainTradeData.hashOfSecretB);
String p2shAddress = BTC.getInstance().deriveP2shAddress(redeemScriptBytes);
- Transaction p2shFundingTransaction = BTC.getInstance().buildSpend(tradeBotData.getXprv58(), p2shAddress, FEE_AMOUNT);
+ Long estimatedFee = BTC.getInstance().estimateFee(lockTimeA * 1000L);
+ if (estimatedFee == null) {
+ LOGGER.debug(() -> String.format("Couldn't estimate Bitcoin fees?"));
+ return;
+ }
+
+ Transaction p2shFundingTransaction = BTC.getInstance().buildSpend(tradeBotData.getXprv58(), p2shAddress, P2SH_B_OUTPUT_AMOUNT + estimatedFee);
if (p2shFundingTransaction == null) {
LOGGER.warn(() -> String.format("Unable to build P2SH-B funding transaction - lack of funds?"));
return;
@@ -757,16 +785,24 @@ public class TradeBot {
byte[] redeemScriptBytes = BTCP2SH.buildScript(crossChainTradeData.partnerBitcoinPKH, crossChainTradeData.lockTimeB, crossChainTradeData.creatorBitcoinPKH, crossChainTradeData.hashOfSecretB);
String p2shAddress = BTC.getInstance().deriveP2shAddress(redeemScriptBytes);
+ int lockTimeA = tradeBotData.getLockTimeA();
+ Long estimatedFee = BTC.getInstance().estimateFee(lockTimeA * 1000L);
+ if (estimatedFee == null) {
+ LOGGER.debug(() -> String.format("Couldn't estimate Bitcoin fees?"));
+ return;
+ }
+
+ final long minimumBalance = P2SH_B_OUTPUT_AMOUNT + estimatedFee;
Long balance = BTC.getInstance().getBalance(p2shAddress);
- if (balance == null || balance < FEE_AMOUNT) {
+ if (balance == null || balance < minimumBalance) {
if (balance != null && balance > 0)
- LOGGER.debug(() -> String.format("P2SH-B balance %s lower than expected %s", BTC.format(balance), BTC.format(FEE_AMOUNT)));
+ LOGGER.debug(() -> String.format("P2SH-B %s balance %s lower than expected %s", p2shAddress, BTC.format(balance), BTC.format(minimumBalance)));
return;
}
// Redeem P2SH-B using secret-B
- Coin redeemAmount = Coin.ZERO; // The real funds are in P2SH-A
+ Coin redeemAmount = Coin.valueOf(P2SH_B_OUTPUT_AMOUNT); // An actual amount to avoid dust filter, remaining used as fees. The real funds are in P2SH-A.
ECKey redeemKey = ECKey.fromPrivate(tradeBotData.getTradePrivateKey());
List<TransactionOutput> fundingOutputs = BTC.getInstance().getUnspentOutputs(p2shAddress);
byte[] receivingAccountInfo = tradeBotData.getReceivingAccountInfo();
@@ -976,7 +1012,7 @@ public class TradeBot {
byte[] redeemScriptBytes = BTCP2SH.buildScript(tradeBotData.getTradeForeignPublicKeyHash(), crossChainTradeData.lockTimeB, crossChainTradeData.creatorBitcoinPKH, crossChainTradeData.hashOfSecretB);
String p2shAddress = BTC.getInstance().deriveP2shAddress(redeemScriptBytes);
- Coin refundAmount = Coin.ZERO;
+ Coin refundAmount = Coin.valueOf(P2SH_B_OUTPUT_AMOUNT); // An actual amount to avoid dust filter, remaining used as fees.
ECKey refundKey = ECKey.fromPrivate(tradeBotData.getTradePrivateKey());
List<TransactionOutput> fundingOutputs = BTC.getInstance().getUnspentOutputs(p2shAddress);
diff --git a/src/main/java/org/qortal/crosschain/BTC.java b/src/main/java/org/qortal/crosschain/BTC.java
index 99c06b93..bf3ecda0 100644
--- a/src/main/java/org/qortal/crosschain/BTC.java
+++ b/src/main/java/org/qortal/crosschain/BTC.java
@@ -158,6 +158,20 @@ public class BTC {
return blockTimestamps.get(5);
}
+ /**
+ * Returns estimated BTC fee, in sats per 1000bytes, optionally for historic timestamp.
+ *
+ * @param timestamp optional milliseconds since epoch
+ * @return sats per 1000bytes, or null if something went wrong
+ */
+ public Long estimateFee(Long timestamp) {
+ // TODO: This will need to be replaced with something better in the near future!
+ if (timestamp != null && timestamp < 1598280000000L)
+ return 4000L;
+
+ return 10_000L;
+ }
+
public Long getBalance(String base58Address) {
return this.electrumX.getBalance(addressToScript(base58Address));
}