/// <summary>
/// Used only in creation of the genesis block.
/// </summary>
internal TransactionInput(NetworkParameters @params, Transaction parentTransaction, byte[] scriptBytes)
: base(@params)
{
ScriptBytes = scriptBytes;
Outpoint = new TransactionOutPoint(@params, -1, null);
_sequence = uint.MaxValue;
ParentTransaction = parentTransaction;
}
/// <summary>
/// Creates an UNSIGNED input that links to the given output
/// </summary>
internal TransactionInput(NetworkParameters @params, Transaction parentTransaction, TransactionOutput output)
: base(@params)
{
var outputIndex = output.Index;
Outpoint = new TransactionOutPoint(@params, outputIndex, output.ParentTransaction);
ScriptBytes = EmptyArray;
_sequence = uint.MaxValue;
ParentTransaction = parentTransaction;
}
internal TransactionOutPoint(NetworkParameters @params, int index, Transaction fromTx)
: base(@params)
{
Index = index;
if (fromTx != null)
{
Hash = fromTx.Hash;
FromTx = fromTx;
}
else
{
// This happens when constructing the genesis block.
Hash = Sha256Hash.ZeroHash;
}
}
/// <summary>
/// Creates a transaction that sends $coins.$cents BTC to the given address.
/// </summary>
/// <remarks>
/// IMPORTANT: This method does NOT update the wallet. If you call createSend again you may get two transactions
/// that spend the same coins. You have to call confirmSend on the created transaction to prevent this,
/// but that should only occur once the transaction has been accepted by the network. This implies you cannot have
/// more than one outstanding sending tx at once.
/// </remarks>
/// <param name="address">The BitCoin address to send the money to.</param>
/// <param name="nanocoins">How much currency to send, in nanocoins.</param>
/// <param name="changeAddress">
/// Which address to send the change to, in case we can't make exactly the right value from
/// our coins. This should be an address we own (is in the keychain).
/// </param>
/// <returns>
/// A new <see cref="Transaction"/> or null if we cannot afford this send.
/// </returns>
internal Transaction CreateSend(Address address, ulong nanocoins, Address changeAddress)
{
lock (this)
{
_log.Info("Creating send tx to " + address + " for " +
Utils.BitcoinValueToFriendlyString(nanocoins));
// To send money to somebody else, we need to do gather up transactions with unspent outputs until we have
// sufficient value. Many coin selection algorithms are possible, we use a simple but suboptimal one.
// TODO: Sort coins so we use the smallest first, to combat wallet fragmentation and reduce fees.
var valueGathered = 0UL;
var gathered = new LinkedList<TransactionOutput>();
foreach (var tx in Unspent.Values)
{
foreach (var output in tx.Outputs)
{
if (!output.IsAvailableForSpending) continue;
if (!output.IsMine(this)) continue;
gathered.AddLast(output);
valueGathered += output.Value;
}
if (valueGathered >= nanocoins) break;
}
// Can we afford this?
if (valueGathered < nanocoins)
{
_log.Info("Insufficient value in wallet for send, missing " +
Utils.BitcoinValueToFriendlyString(nanocoins - valueGathered));
// TODO: Should throw an exception here.
return null;
}
Debug.Assert(gathered.Count > 0);
var sendTx = new Transaction(_params);
sendTx.AddOutput(new TransactionOutput(_params, sendTx, nanocoins, address));
var change = (long) (valueGathered - nanocoins);
if (change > 0)
{
// The value of the inputs is greater than what we want to send. Just like in real life then,
// we need to take back some coins ... this is called "change". Add another output that sends the change
// back to us.
_log.Info(" with " + Utils.BitcoinValueToFriendlyString((ulong) change) + " coins change");
sendTx.AddOutput(new TransactionOutput(_params, sendTx, (ulong) change, changeAddress));
}
foreach (var output in gathered)
{
sendTx.AddInput(output);
}
// Now sign the inputs, thus proving that we are entitled to redeem the connected outputs.
sendTx.SignInputs(Transaction.SigHash.All, this);
_log.InfoFormat(" created {0}", sendTx.HashAsString);
return sendTx;
}
}
/// <summary>
/// Call this when we have successfully transmitted the send tx to the network, to update the wallet.
/// </summary>
internal void ConfirmSend(Transaction tx)
{
lock (this)
{
Debug.Assert(!Pending.ContainsKey(tx.Hash), "confirmSend called on the same transaction twice");
_log.InfoFormat("confirmSend of {0}", tx.HashAsString);
// Mark the outputs of the used transactions as spent, so we don't try and spend it again.
foreach (var input in tx.Inputs)
{
var connectedOutput = input.Outpoint.ConnectedOutput;
var connectedTx = connectedOutput.ParentTransaction;
connectedOutput.MarkAsSpent(input);
MaybeMoveTxToSpent(connectedTx, "spent tx");
}
// Add to the pending pool. It'll be moved out once we receive this transaction on the best chain.
Pending[tx.Hash] = tx;
}
}
/// <param name="deadTx">The transaction that is newly dead.</param>
/// <param name="replacementTx">The transaction that killed it.</param>
public WalletDeadTransactionEventArgs(Transaction deadTx, Transaction replacementTx)
{
DeadTx = deadTx;
ReplacementTx = replacementTx;
}
/// <param name="tx">The transaction which sent us the coins.</param>
/// <param name="prevBalance">Balance before the coins were received.</param>
/// <param name="newBalance">Current balance of the wallet.</param>
public WalletCoinsReceivedEventArgs(Transaction tx, ulong prevBalance, ulong newBalance)
{
Tx = tx;
PrevBalance = prevBalance;
NewBalance = newBalance;
}
/// <summary>
/// Updates the wallet by checking if this TX spends any of our outputs. This is not used normally because
/// when we receive our own spends, we've already marked the outputs as spent previously (during tx creation) so
/// there's no need to go through and do it again.
/// </summary>
/// <exception cref="VerificationException"/>
private void UpdateForSpends(Transaction tx)
{
// tx is on the best chain by this point.
foreach (var input in tx.Inputs)
{
var result = input.Connect(Unspent, false);
if (result == TransactionInput.ConnectionResult.NoSuchTx)
{
// Not found in the unspent map. Try again with the spent map.
result = input.Connect(Spent, false);
if (result == TransactionInput.ConnectionResult.NoSuchTx)
{
// Doesn't spend any of our outputs or is coinbase.
continue;
}
}
if (result == TransactionInput.ConnectionResult.AlreadySpent)
{
// Double spend! This must have overridden a pending tx, or the block is bad (contains transactions
// that illegally double spend: should never occur if we are connected to an honest node).
//
// Work backwards like so:
//
// A -> spent by B [pending]
// \-> spent by C [chain]
var doubleSpent = input.Outpoint.FromTx; // == A
Debug.Assert(doubleSpent != null);
var index = input.Outpoint.Index;
var output = doubleSpent.Outputs[index];
var spentBy = output.SpentBy;
Debug.Assert(spentBy != null);
var connected = spentBy.ParentTransaction;
Debug.Assert(connected != null);
if (Pending.Remove(connected.Hash))
{
_log.InfoFormat("Saw double spend from chain override pending tx {0}", connected.HashAsString);
_log.Info(" <-pending ->dead");
_dead[connected.Hash] = connected;
// Now forcibly change the connection.
input.Connect(Unspent, true);
// Inform the event listeners of the newly dead tx.
if (DeadTransaction != null)
{
lock (DeadTransaction)
{
DeadTransaction(this, new WalletDeadTransactionEventArgs(connected, tx));
}
}
}
}
else if (result == TransactionInput.ConnectionResult.Success)
{
// Otherwise we saw a transaction spend our coins, but we didn't try and spend them ourselves yet.
// The outputs are already marked as spent by the connect call above, so check if there are any more for
// us to use. Move if not.
var connected = input.Outpoint.FromTx;
MaybeMoveTxToSpent(connected, "prevtx");
}
}
}
/// <summary>
/// Handle when a transaction becomes newly active on the best chain, either due to receiving a new block or a
/// re-org making inactive transactions active.
/// </summary>
/// <exception cref="VerificationException"/>
private void ProcessTxFromBestChain(Transaction tx)
{
// This TX may spend our existing outputs even though it was not pending. This can happen in unit
// tests and if keys are moved between wallets.
UpdateForSpends(tx);
if (!tx.GetValueSentToMe(this).Equals(0))
{
// It's sending us coins.
_log.Info(" new tx ->unspent");
Debug.Assert(!Unspent.ContainsKey(tx.Hash), "TX was received twice");
Unspent[tx.Hash] = tx;
}
else
{
// It spent some of our coins and did not send us any.
_log.Info(" new tx ->spent");
Debug.Assert(!Spent.ContainsKey(tx.Hash), "TX was received twice");
Spent[tx.Hash] = tx;
}
}
/// <exception cref="ProtocolException"/>
protected override void Parse()
{
_version = ReadUint32();
_prevBlockHash = ReadHash();
_merkleRoot = ReadHash();
_time = ReadUint32();
_difficultyTarget = ReadUint32();
_nonce = ReadUint32();
_hash = new Sha256Hash(Utils.ReverseBytes(Utils.DoubleDigest(Bytes, 0, Cursor)));
if (Cursor == Bytes.Length)
{
// This message is just a header, it has no transactions.
return;
}
var numTransactions = (int) ReadVarInt();
Transactions = new List<Transaction>(numTransactions);
for (var i = 0; i < numTransactions; i++)
{
var tx = new Transaction(Params, Bytes, Cursor);
Transactions.Add(tx);
Cursor += tx.MessageSize;
}
}
/// <summary>
/// Returns a solved block that builds on top of this one. This exists for unit tests.
/// </summary>
internal Block CreateNextBlock(Address to, uint time)
{
var b = new Block(Params);
b.DifficultyTarget = _difficultyTarget;
b.AddCoinbaseTransaction(_emptyBytes);
// Add a transaction paying 50 coins to the "to" address.
var t = new Transaction(Params);
t.AddOutput(new TransactionOutput(Params, t, Utils.ToNanoCoins(50, 0), to));
// The input does not really need to be a valid signature, as long as it has the right general form.
var input = new TransactionInput(Params, t, Script.CreateInputScript(_emptyBytes, _emptyBytes));
// Importantly the outpoint hash cannot be zero as that's how we detect a coinbase transaction in isolation
// but it must be unique to avoid 'different' transactions looking the same.
var counter = new byte[32];
counter[0] = (byte) _txCounter++;
input.Outpoint.Hash = new Sha256Hash(counter);
t.AddInput(input);
b.AddTransaction(t);
b.PrevBlockHash = Hash;
b.TimeSeconds = time;
b.Solve();
b.VerifyHeader();
return b;
}
/// <summary>
/// Adds a transaction to this block.
/// </summary>
internal void AddTransaction(Transaction t)
{
if (Transactions == null)
{
Transactions = new List<Transaction>();
}
Transactions.Add(t);
// Force a recalculation next time the values are needed.
_merkleRoot = null;
_hash = null;
}
/// <summary>
/// Adds a coinbase transaction to the block. This exists for unit tests.
/// </summary>
internal void AddCoinbaseTransaction(byte[] pubKeyTo)
{
Transactions = new List<Transaction>();
var coinbase = new Transaction(Params);
// A real coinbase transaction has some stuff in the scriptSig like the extraNonce and difficulty. The
// transactions are distinguished by every TX output going to a different key.
//
// Here we will do things a bit differently so a new address isn't needed every time. We'll put a simple
// counter in the scriptSig so every transaction has a different hash.
coinbase.AddInput(new TransactionInput(Params, coinbase, new[] {(byte) _txCounter++}));
coinbase.AddOutput(new TransactionOutput(Params, coinbase, Script.CreateOutputScript(pubKeyTo)));
Transactions.Add(coinbase);
}
private static Block CreateGenesis(NetworkParameters n)
{
var genesisBlock = new Block(n);
var t = new Transaction(n);
// A script containing the difficulty bits and the following message:
//
// "The Times 03/Jan/2009 Chancellor on brink of second bailout for banks"
var bytes = Hex.Decode("04ffff001d0104455468652054696d65732030332f4a616e2f32303039204368616e63656c6c6f72206f6e206272696e6b206f66207365636f6e64206261696c6f757420666f722062616e6b73");
t.AddInput(new TransactionInput(n, t, bytes));
using (var scriptPubKeyBytes = new MemoryStream())
{
Script.WriteBytes(scriptPubKeyBytes, Hex.Decode("04678afdb0fe5548271967f1a67130b7105cd6a828e03909a67962e0ea1f61deb649f6bc3f4cef38c4f35504e51ec112de5c384df7ba0b8d578a4c702b6bf11d5f"));
scriptPubKeyBytes.Write(Script.OpCheckSig);
t.AddOutput(new TransactionOutput(n, t, scriptPubKeyBytes.ToArray()));
}
genesisBlock.AddTransaction(t);
return genesisBlock;
}
/// <summary>
/// Called by the <see cref="BlockChain"/> when we receive a new block that sends coins to one of our addresses or
/// spends coins from one of our addresses (note that a single transaction can do both).
/// </summary>
/// <remarks>
/// This is necessary for the internal book-keeping Wallet does. When a transaction is received that sends us
/// coins it is added to a pool so we can use it later to create spends. When a transaction is received that
/// consumes outputs they are marked as spent so they won't be used in future.<p/>
/// A transaction that spends our own coins can be received either because a spend we created was accepted by the
/// network and thus made it into a block, or because our keys are being shared between multiple instances and
/// some other node spent the coins instead. We still have to know about that to avoid accidentally trying to
/// double spend.<p/>
/// A transaction may be received multiple times if is included into blocks in parallel chains. The blockType
/// parameter describes whether the containing block is on the main/best chain or whether it's on a presently
/// inactive side chain. We must still record these transactions and the blocks they appear in because a future
/// block might change which chain is best causing a reorganize. A re-org can totally change our balance!
/// </remarks>
/// <exception cref="VerificationException"/>
/// <exception cref="ScriptException"/>
internal void Receive(Transaction tx, StoredBlock block, BlockChain.NewBlockType blockType)
{
lock (this)
{
Receive(tx, block, blockType, false);
}
}
/// <summary>
/// Broadcast a transaction to all connected peers.
/// </summary>
/// <returns>Whether we sent to at least one peer.</returns>
public bool BroadcastTransaction(Transaction tx)
{
var success = false;
lock (_peers)
{
foreach (var peer in _peers)
{
try
{
peer.BroadcastTransaction(tx);
success = true;
}
catch (IOException e)
{
_log.Error("failed to broadcast to " + peer, e);
}
}
}
return success;
}
/// <summary>
/// If the transactions outputs are all marked as spent, and it's in the unspent map, move it.
/// </summary>
private void MaybeMoveTxToSpent(Transaction tx, String context)
{
if (tx.IsEveryOutputSpent())
{
// There's nothing left I can spend in this transaction.
if (Unspent.Remove(tx.Hash))
{
if (_log.IsInfoEnabled)
{
_log.Info(" " + context + " <-unspent");
_log.Info(" " + context + " ->spent");
}
Spent[tx.Hash] = tx;
}
}
}
private void ReprocessTxAfterReorg(IDictionary<Sha256Hash, Transaction> pool, Transaction tx)
{
_log.InfoFormat(" TX {0}", tx.HashAsString);
var numInputs = tx.Inputs.Count;
var noSuchTx = 0;
var success = 0;
var isDead = false;
foreach (var input in tx.Inputs)
{
if (input.IsCoinBase)
{
// Input is not in our wallet so there is "no such input tx", bit of an abuse.
noSuchTx++;
continue;
}
var result = input.Connect(pool, false);
if (result == TransactionInput.ConnectionResult.Success)
{
success++;
}
else if (result == TransactionInput.ConnectionResult.NoSuchTx)
{
noSuchTx++;
}
else if (result == TransactionInput.ConnectionResult.AlreadySpent)
{
isDead = true;
// This transaction was replaced by a double spend on the new chain. Did you just reverse
// your own transaction? I hope not!!
_log.Info(" ->dead, will not confirm now unless there's another re-org");
var doubleSpent = input.GetConnectedOutput(pool);
var replacement = doubleSpent.SpentBy.ParentTransaction;
_dead[tx.Hash] = tx;
Pending.Remove(tx.Hash);
// Inform the event listeners of the newly dead tx.
if (DeadTransaction != null)
{
lock (DeadTransaction)
{
DeadTransaction(this, new WalletDeadTransactionEventArgs(tx, replacement));
}
}
break;
}
}
if (isDead) return;
if (noSuchTx == numInputs)
{
_log.Info(" ->inactive");
_inactive[tx.Hash] = tx;
}
else if (success == numInputs - noSuchTx)
{
// All inputs are either valid for spending or don't come from us. Miners are trying to re-include it.
_log.Info(" ->pending");
Pending[tx.Hash] = tx;
_dead.Remove(tx.Hash);
}
}
/// <exception cref="VerificationException"/>
/// <exception cref="ScriptException"/>
private void Receive(Transaction tx, StoredBlock block, BlockChain.NewBlockType blockType, bool reorg)
{
lock (this)
{
// Runs in a peer thread.
var prevBalance = GetBalance();
var txHash = tx.Hash;
var bestChain = blockType == BlockChain.NewBlockType.BestChain;
var sideChain = blockType == BlockChain.NewBlockType.SideChain;
var valueSentFromMe = tx.GetValueSentFromMe(this);
var valueSentToMe = tx.GetValueSentToMe(this);
var valueDifference = (long) (valueSentToMe - valueSentFromMe);
if (!reorg)
{
_log.InfoFormat("Received tx{0} for {1} BTC: {2}", sideChain ? " on a side chain" : "",
Utils.BitcoinValueToFriendlyString(valueDifference), tx.HashAsString);
}
// If this transaction is already in the wallet we may need to move it into a different pool. At the very
// least we need to ensure we're manipulating the canonical object rather than a duplicate.
Transaction wtx;
if (Pending.TryGetValue(txHash, out wtx))
{
Pending.Remove(txHash);
_log.Info(" <-pending");
// A transaction we created appeared in a block. Probably this is a spend we broadcast that has been
// accepted by the network.
//
// Mark the tx as appearing in this block so we can find it later after a re-org.
wtx.AddBlockAppearance(block);
if (bestChain)
{
if (valueSentToMe.Equals(0))
{
// There were no change transactions so this tx is fully spent.
_log.Info(" ->spent");
Debug.Assert(!Spent.ContainsKey(wtx.Hash), "TX in both pending and spent pools");
Spent[wtx.Hash] = wtx;
}
else
{
// There was change back to us, or this tx was purely a spend back to ourselves (perhaps for
// anonymization purposes).
_log.Info(" ->unspent");
Debug.Assert(!Unspent.ContainsKey(wtx.Hash), "TX in both pending and unspent pools");
Unspent[wtx.Hash] = wtx;
}
}
else if (sideChain)
{
// The transaction was accepted on an inactive side chain, but not yet by the best chain.
_log.Info(" ->inactive");
// It's OK for this to already be in the inactive pool because there can be multiple independent side
// chains in which it appears:
//
// b1 --> b2
// \-> b3
// \-> b4 (at this point it's already present in 'inactive'
if (_inactive.ContainsKey(wtx.Hash))
_log.Info("Saw a transaction be incorporated into multiple independent side chains");
_inactive[wtx.Hash] = wtx;
// Put it back into the pending pool, because 'pending' means 'waiting to be included in best chain'.
Pending[wtx.Hash] = wtx;
}
}
else
{
if (!reorg)
{
// Mark the tx as appearing in this block so we can find it later after a re-org.
tx.AddBlockAppearance(block);
}
// This TX didn't originate with us. It could be sending us coins and also spending our own coins if keys
// are being shared between different wallets.
if (sideChain)
{
_log.Info(" ->inactive");
_inactive[tx.Hash] = tx;
}
else if (bestChain)
{
ProcessTxFromBestChain(tx);
}
}
_log.InfoFormat("Balance is now: {0}", Utils.BitcoinValueToFriendlyString(GetBalance()));
// Inform anyone interested that we have new coins. Note: we may be re-entered by the event listener,
// so we must not make assumptions about our state after this loop returns! For example,
// the balance we just received might already be spent!
if (!reorg && bestChain && valueDifference > 0 && CoinsReceived != null)
{
lock (CoinsReceived)
{
CoinsReceived(this, new WalletCoinsReceivedEventArgs(tx, prevBalance, GetBalance()));
}
}
}
}
/// <summary>
/// Deserializes an input message. This is usually part of a transaction message.
/// </summary>
/// <exception cref="ProtocolException"/>
public TransactionInput(NetworkParameters @params, Transaction parentTransaction, byte[] payload, int offset)
: base(@params, payload, offset)
{
ParentTransaction = parentTransaction;
}