private Transaction BuildHtlcTransaction(Htlc htlc)
{
bool incoming = htlc.Direction == Direction.Incoming;
var fee = TransactionFee.CalculateFee(FeeratePerKw, incoming ? TransactionFee.HtlcSuccessWeight : TransactionFee.HtlcTimeoutWeight);
var witnessScript = CreateHtlcWitnessScript(htlc);
var outputScript = OutputScripts.ToLocal(CommitmentTxParams.RevocationPublicKey.ToPubKey(), CommitmentTxParams.DelayedPaymentPublicKey.ToPubKey(), ChannelParameters.ToSelfDelay);
var outputIndex = _htlcOutputIndexMap[htlc];
var amount = htlc.AmountMsat.MSatToSatoshi() - fee;
if (amount < ChannelParameters.DustLimitSatoshis)
{
throw new InvalidOperationException("HTLC amount below dust limit");
}
Transaction tx = Transaction.Create(Network);
TxIn txIn = new TxIn(new OutPoint(_commitmentTransaction, outputIndex));
txIn.Sequence = 0;
txIn.ScriptSig = witnessScript.WitHash.ScriptPubKey;
tx.Inputs.Add(txIn);
TxOut txOut = new TxOut(Money.Satoshis(amount), outputScript.WitHash.ScriptPubKey);
tx.Outputs.Add(txOut);
tx.Version = 2;
tx.LockTime = incoming ? 0 : htlc.Expiry;
return(tx);
}
private TxOut BuildReceivedHtlcOutput(Htlc trimmedReceivedHtlc)
{
PubKey localHtlcPubkey = new PubKey(CommitmentTxParams.HtlcPublicKey.PublicKeyCompressed);
PubKey remoteHtlcPubkey = new PubKey(RemoteHtlcPubkey.PublicKeyCompressed);
PubKey localRevocationPubkey = new PubKey(CommitmentTxParams.RevocationPublicKey.PublicKeyCompressed);
Script script = OutputScripts.ReceivedHtlc(localHtlcPubkey, remoteHtlcPubkey, localRevocationPubkey, trimmedReceivedHtlc.PaymentHash, trimmedReceivedHtlc.Expiry);
return(new TxOut(Money.Satoshis(trimmedReceivedHtlc.AmountMsat.MSatToSatoshi()), script.WitHash.ScriptPubKey));
}
private WitScript CreateHtlcWitnessScript(Htlc htlc, byte[] localPubKeySignature, byte[] remotePubKeySignature,
Script witnessScript)
{
bool incoming = htlc.Direction == Direction.Incoming;
return(new WitScript(new List <byte[]>()
{
new byte[] { 0 }, remotePubKeySignature, localPubKeySignature, incoming ? htlc.PaymentPreImage : new byte[] { 0 }, witnessScript.ToBytes()
}));
}
private Script CreateHtlcWitnessScript(Htlc htlc)
{
return(htlc.Direction == Direction.Incoming ?
OutputScripts.ReceivedHtlc(CommitmentTxParams.HtlcPublicKey.ToPubKey(),
RemoteHtlcPubkey.ToPubKey(),
CommitmentTxParams.RevocationPublicKey.ToPubKey(), htlc.PaymentHash, htlc.Expiry) :
OutputScripts.OfferedHtlc(CommitmentTxParams.HtlcPublicKey.ToPubKey(),
RemoteHtlcPubkey.ToPubKey(),
CommitmentTxParams.RevocationPublicKey.ToPubKey(), htlc.PaymentHash));
}
public Transaction SignHtlcTransaction(Htlc htlc, Transaction transaction, byte[] htlcRemoteSignature, Key fundingPrivateKey)
{
var witnessScript = CreateHtlcWitnessScript(htlc);
var input = transaction.Inputs[0];
var outputIndex = _htlcOutputIndexMap[htlc];
var amount = _commitmentTransaction.Outputs[outputIndex].Value;
var inputCoin = new Coin(input.PrevOut, new TxOut(Money.Satoshis(amount), input.ScriptSig));
var scriptCoin = inputCoin.ToScriptCoin(witnessScript);
TransactionBuilder builder2 = new TransactionBuilder();
builder2.AddCoins(scriptCoin);
builder2.AddKeys(fundingPrivateKey);
var signature = transaction.SignInput(fundingPrivateKey, scriptCoin);
var witScript = CreateHtlcWitnessScript(htlc, signature.ToBytes(), htlcRemoteSignature, witnessScript);
transaction.Inputs[0].ScriptSig = Script.Empty;
transaction.Inputs[0].WitScript = witScript;
return(transaction);
}
