/**
* Updates the outputs on the payment contract transaction and re-signs it. The state must be
* READY in order to call this method. The signature that is returned should be sent to the server
* so it has the ability to broadcast the best seen payment when the channel closes or times out.
*
* <p>The returned signature is over the payment transaction, which we never have a valid copy of
* and thus there is no accessor for it on this object.
*
* <p>To spend the whole channel increment by {@link PaymentChannelClientState#getTotalValue()} -
* {@link PaymentChannelClientState#getValueRefunded()}
*
* @param size How many satoshis to increment the payment by (note: not the new total).
* @throws ValueOutOfRangeException If size is negative or the channel does not have sufficient
* money in it to complete this payment.
*/
public synchronized IncrementedPayment incrementPaymentBy(Coin size)
throws ValueOutOfRangeException {
checkState(state == State.READY);
checkNotExpired();
checkNotNull(size); // Validity of size will be checked by makeUnsignedChannelContract.
if (size.signum() < 0) throw new ValueOutOfRangeException("Tried to decrement payment");
Coin newValueToMe = valueToMe.subtract(size);
if (newValueToMe.compareTo(Transaction.MIN_NONDUST_OUTPUT) < 0 && newValueToMe.signum() > 0) {
log.info(
"New value being sent back as change was smaller than minimum nondust output, sending all");
size = valueToMe;
newValueToMe = Coin.ZERO;
}
if (newValueToMe.signum() < 0)
throw new ValueOutOfRangeException(
"Channel has too little money to pay " + size + " satoshis");
Transaction tx = makeUnsignedChannelContract(newValueToMe);
log.info("Signing new payment tx {}", tx);
Transaction.SigHash mode;
// If we spent all the money we put into this channel, we (by definition) don't care what the
// outputs are, so
// we sign with SIGHASH_NONE to let the server do what it wants.
if (newValueToMe.equals(Coin.ZERO)) mode = Transaction.SigHash.NONE;
else mode = Transaction.SigHash.SINGLE;
TransactionSignature sig = tx.calculateSignature(0, myKey, multisigScript, mode, true);
valueToMe = newValueToMe;
updateChannelInWallet();
IncrementedPayment payment = new IncrementedPayment();
payment.signature = sig;
payment.amount = size;
return payment;
}
public TransactionOutput(
NetworkParameters params, @Nullable Transaction parent, Coin value, byte[] scriptBytes) {
super(params);
// Negative values obviously make no sense, except for -1 which is used as a sentinel value when
// calculating
// SIGHASH_SINGLE signatures, so unfortunately we have to allow that here.
checkArgument(
value.signum() >= 0 || value.equals(Coin.NEGATIVE_SATOSHI), "Negative values not allowed");
checkArgument(
value.compareTo(NetworkParameters.MAX_MONEY) < 0,
"Values larger than MAX_MONEY not allowed");
this.value = value.value;
this.scriptBytes = scriptBytes;
parentTransaction = parent;
availableForSpending = true;
length = 8 + VarInt.sizeOf(scriptBytes.length) + scriptBytes.length;
}
PaymentChannelServerState(
StoredServerChannel storedServerChannel, Wallet wallet, TransactionBroadcaster broadcaster)
throws VerificationException {
synchronized (storedServerChannel) {
this.wallet = checkNotNull(wallet);
this.broadcaster = checkNotNull(broadcaster);
this.multisigContract = checkNotNull(storedServerChannel.contract);
this.multisigScript = multisigContract.getOutput(0).getScriptPubKey();
this.clientKey = ECKey.fromPublicOnly(multisigScript.getChunks().get(1).data);
this.clientOutput = checkNotNull(storedServerChannel.clientOutput);
this.refundTransactionUnlockTimeSecs = storedServerChannel.refundTransactionUnlockTimeSecs;
this.serverKey = checkNotNull(storedServerChannel.myKey);
this.totalValue = multisigContract.getOutput(0).getValue();
this.bestValueToMe = checkNotNull(storedServerChannel.bestValueToMe);
this.bestValueSignature = storedServerChannel.bestValueSignature;
checkArgument(bestValueToMe.equals(Coin.ZERO) || bestValueSignature != null);
this.storedServerChannel = storedServerChannel;
storedServerChannel.state = this;
this.state = State.READY;
}
}
/**
* Called when the client provides us with a new signature and wishes to increment total payment
* by size. Verifies the provided signature and only updates values if everything checks out. If
* the new refundSize is not the lowest we have seen, it is simply ignored.
*
* @param refundSize How many satoshis of the original contract are refunded to the client (the
* rest are ours)
* @param signatureBytes The new signature spending the multi-sig contract to a new payment
* transaction
* @throws VerificationException If the signature does not verify or size is out of range (incl
* being rejected by the network as dust).
* @return true if there is more value left on the channel, false if it is now fully used up.
*/
public synchronized boolean incrementPayment(Coin refundSize, byte[] signatureBytes)
throws VerificationException, ValueOutOfRangeException, InsufficientMoneyException {
checkState(state == State.READY);
checkNotNull(refundSize);
checkNotNull(signatureBytes);
TransactionSignature signature = TransactionSignature.decodeFromBitcoin(signatureBytes, true);
// We allow snapping to zero for the payment amount because it's treated specially later, but
// not less than
// the dust level because that would prevent the transaction from being relayed/mined.
final boolean fullyUsedUp = refundSize.equals(Coin.ZERO);
if (refundSize.compareTo(clientOutput.getMinNonDustValue()) < 0 && !fullyUsedUp)
throw new ValueOutOfRangeException(
"Attempt to refund negative value or value too small to be accepted by the network");
Coin newValueToMe = totalValue.subtract(refundSize);
if (newValueToMe.signum() < 0)
throw new ValueOutOfRangeException("Attempt to refund more than the contract allows.");
if (newValueToMe.compareTo(bestValueToMe) < 0)
throw new ValueOutOfRangeException("Attempt to roll back payment on the channel.");
// Get the wallet's copy of the multisigContract (ie with confidence information), if this is
// null, the wallet
// was not connected to the peergroup when the contract was broadcast (which may cause issues
// down the road, and
// disables our double-spend check next)
Transaction walletContract = wallet.getTransaction(multisigContract.getHash());
checkNotNull(
walletContract,
"Wallet did not contain multisig contract {} after state was marked READY",
multisigContract.getHash());
// Note that we check for DEAD state here, but this test is essentially useless in production
// because we will
// miss most double-spends due to bloom filtering right now anyway. This will eventually fixed
// by network-wide
// double-spend notifications, so we just wait instead of attempting to add all dependant
// outpoints to our bloom
// filters (and probably missing lots of edge-cases).
if (walletContract.getConfidence().getConfidenceType()
== TransactionConfidence.ConfidenceType.DEAD) {
close();
throw new VerificationException("Multisig contract was double-spent");
}
Transaction.SigHash mode;
// If the client doesn't want anything back, they shouldn't sign any outputs at all.
if (fullyUsedUp) mode = Transaction.SigHash.NONE;
else mode = Transaction.SigHash.SINGLE;
if (signature.sigHashMode() != mode || !signature.anyoneCanPay())
throw new VerificationException(
"New payment signature was not signed with the right SIGHASH flags.");
Wallet.SendRequest req = makeUnsignedChannelContract(newValueToMe);
// Now check the signature is correct.
// Note that the client must sign with SIGHASH_{SINGLE/NONE} | SIGHASH_ANYONECANPAY to allow us
// to add additional
// inputs (in case we need to add significant fee, or something...) and any outputs we want to
// pay to.
Sha256Hash sighash = req.tx.hashForSignature(0, multisigScript, mode, true);
if (!clientKey.verify(sighash, signature))
throw new VerificationException("Signature does not verify on tx\n" + req.tx);
bestValueToMe = newValueToMe;
bestValueSignature = signatureBytes;
updateChannelInWallet();
return !fullyUsedUp;
}
