/**
* Copyright 2011 Google Inc.
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
package com.google.digitalcoin.core;
import com.google.common.base.Preconditions;
import java.io.IOException;
import java.io.ObjectOutputStream;
import java.io.OutputStream;
import java.io.Serializable;
import java.util.Map;
import static com.google.common.base.Preconditions.checkElementIndex;
import static com.google.common.base.Preconditions.checkNotNull;
/**
* A transfer of coins from one address to another creates a transaction in which the outputs
* can be claimed by the recipient in the input of another transaction. You can imagine a
* transaction as being a module which is wired up to others, the inputs of one have to be wired
* to the outputs of another. The exceptions are coinbase transactions, which create new coins.
*/
public class TransactionInput extends ChildMessage implements Serializable {
public static final long NO_SEQUENCE = 0xFFFFFFFFL;
private static final long serialVersionUID = 2;
public static final byte[] EMPTY_ARRAY = new byte[0];
// Allows for altering transactions after they were broadcast. Tx replacement is currently disabled in the C++
// client so this is always the UINT_MAX.
// TODO: Document this in more detail and build features that use it.
private long sequence;
// Data needed to connect to the output of the transaction we're gathering coins from.
private TransactionOutPoint outpoint;
// The "script bytes" might not actually be a script. In coinbase transactions where new coins are minted there
// is no input transaction, so instead the scriptBytes contains some extra stuff (like a rollover nonce) that we
// don't care about much. The bytes are turned into a Script object (cached below) on demand via a getter.
private byte[] scriptBytes;
// The Script object obtained from parsing scriptBytes. Only filled in on demand and if the transaction is not
// coinbase.
transient private Script scriptSig;
// A pointer to the transaction that owns this input.
private Transaction parentTransaction;
/**
* Creates an input that connects to nothing - used only in creation of coinbase transactions.
*/
public TransactionInput(NetworkParameters params, Transaction parentTransaction, byte[] scriptBytes) {
super(params);
this.scriptBytes = scriptBytes;
this.outpoint = new TransactionOutPoint(params, NO_SEQUENCE, (Transaction)null);
this.sequence = NO_SEQUENCE;
this.parentTransaction = parentTransaction;
length = 40 + (scriptBytes == null ? 1 : VarInt.sizeOf(scriptBytes.length) + scriptBytes.length);
}
public TransactionInput(NetworkParameters params, Transaction parentTransaction,
byte[] scriptBytes,
TransactionOutPoint outpoint) {
super(params);
this.scriptBytes = scriptBytes;
this.outpoint = outpoint;
this.sequence = NO_SEQUENCE;
this.parentTransaction = parentTransaction;
length = 40 + (scriptBytes == null ? 1 : VarInt.sizeOf(scriptBytes.length) + scriptBytes.length);
}
/**
* Creates an UNSIGNED input that links to the given output
*/
TransactionInput(NetworkParameters params, Transaction parentTransaction, TransactionOutput output) {
super(params);
long outputIndex = output.getIndex();
outpoint = new TransactionOutPoint(params, outputIndex, output.parentTransaction);
scriptBytes = EMPTY_ARRAY;
sequence = NO_SEQUENCE;
this.parentTransaction = parentTransaction;
length = 41;
}
/**
* Deserializes an input message. This is usually part of a transaction message.
*/
public TransactionInput(NetworkParameters params, Transaction parentTransaction,
byte[] payload, int offset) throws ProtocolException {
super(params, payload, offset);
this.parentTransaction = parentTransaction;
}
/**
* Deserializes an input message. This is usually part of a transaction message.
* @param params NetworkParameters object.
* @param msg Digitalcoin protocol formatted byte array containing message content.
* @param offset The location of the first msg byte within the array.
* @param parseLazy Whether to perform a full parse immediately or delay until a read is requested.
* @param parseRetain Whether to retain the backing byte array for quick reserialization.
* If true and the backing byte array is invalidated due to modification of a field then
* the cached bytes may be repopulated and retained if the message is serialized again in the future.
* as the length will be provided as part of the header. If unknown then set to Message.UNKNOWN_LENGTH
* @throws ProtocolException
*/
public TransactionInput(NetworkParameters params, Transaction parentTransaction, byte[] msg, int offset,
boolean parseLazy, boolean parseRetain)
throws ProtocolException {
super(params, msg, offset, parentTransaction, parseLazy, parseRetain, UNKNOWN_LENGTH);
this.parentTransaction = parentTransaction;
}
protected void parseLite() {
int curs = cursor;
int scriptLen = (int) readVarInt(36);
length = cursor - offset + scriptLen + 4;
cursor = curs;
}
void parse() throws ProtocolException {
outpoint = new TransactionOutPoint(params, bytes, cursor, this, parseLazy, parseRetain);
cursor += outpoint.getMessageSize();
int scriptLen = (int) readVarInt();
scriptBytes = readBytes(scriptLen);
sequence = readUint32();
}
@Override
protected void digitalcoinSerializeToStream(OutputStream stream) throws IOException {
outpoint.digitalcoinSerialize(stream);
stream.write(new VarInt(scriptBytes.length).encode());
stream.write(scriptBytes);
Utils.uint32ToByteStreamLE(sequence, stream);
}
/**
* Coinbase transactions have special inputs with hashes of zero. If this is such an input, returns true.
*/
public boolean isCoinBase() {
maybeParse();
return outpoint.getHash().equals(Sha256Hash.ZERO_HASH) &&
outpoint.getIndex() == NO_SEQUENCE;
}
/**
* Returns the input script.
*/
public Script getScriptSig() throws ScriptException {
// Transactions that generate new coins don't actually have a script. Instead this
// parameter is overloaded to be something totally different.
if (scriptSig == null) {
maybeParse();
scriptSig = new Script(params, Preconditions.checkNotNull(scriptBytes), 0, scriptBytes.length);
}
return scriptSig;
}
/**
* Convenience method that returns the from address of this input by parsing the scriptSig.
*
* @throws ScriptException if the scriptSig could not be understood (eg, if this is a coinbase transaction).
*/
public Address getFromAddress() throws ScriptException {
if (isCoinBase()) {
throw new ScriptException(
"This is a coinbase transaction which generates new coins. It does not have a from address.");
}
return getScriptSig().getFromAddress();
}
/**
* Sequence numbers allow participants in a multi-party transaction signing protocol to create new versions of the
* transaction independently of each other. Newer versions of a transaction can replace an existing version that's
* in nodes memory pools if the existing version is time locked. See the Contracts page on the Digitalcoin wiki for
* examples of how you can use this feature to build contract protocols. Note that as of 2012 the tx replacement
* feature is disabled so sequence numbers are unusable.
*/
public long getSequenceNumber() {
maybeParse();
return sequence;
}
/**
* Sequence numbers allow participants in a multi-party transaction signing protocol to create new versions of the
* transaction independently of each other. Newer versions of a transaction can replace an existing version that's
* in nodes memory pools if the existing version is time locked. See the Contracts page on the Digitalcoin wiki for
* examples of how you can use this feature to build contract protocols. Note that as of 2012 the tx replacement
* feature is disabled so sequence numbers are unusable.
*/
public void setSequenceNumber(long sequence) {
unCache();
this.sequence = sequence;
}
/**
* @return The previous output transaction reference, as an OutPoint structure. This contains the
* data needed to connect to the output of the transaction we're gathering coins from.
*/
public TransactionOutPoint getOutpoint() {
maybeParse();
return outpoint;
}
/**
* The "script bytes" might not actually be a script. In coinbase transactions where new coins are minted there
* is no input transaction, so instead the scriptBytes contains some extra stuff (like a rollover nonce) that we
* don't care about much. The bytes are turned into a Script object (cached below) on demand via a getter.
* @return the scriptBytes
*/
public byte[] getScriptBytes() {
maybeParse();
return scriptBytes;
}
/**
* @param scriptBytes the scriptBytes to set
*/
void setScriptBytes(byte[] scriptBytes) {
unCache();
int oldLength = length;
this.scriptBytes = scriptBytes;
// 40 = previous_outpoint (36) + sequence (4)
int newLength = 40 + (scriptBytes == null ? 1 : VarInt.sizeOf(scriptBytes.length) + scriptBytes.length);
adjustLength(newLength - oldLength);
}
/**
* @return The Transaction that owns this input.
*/
public Transaction getParentTransaction() {
return parentTransaction;
}
/**
* Returns a human readable debug string.
*/
public String toString() {
if (isCoinBase())
return "TxIn: COINBASE";
try {
return "TxIn from tx " + outpoint + " (pubkey: " + Utils.bytesToHexString(getScriptSig().getPubKey()) +
") script:" +
getScriptSig().toString();
} catch (ScriptException e) {
throw new RuntimeException(e);
}
}
enum ConnectionResult {
NO_SUCH_TX,
ALREADY_SPENT,
SUCCESS
}
// TODO: Clean all this up once TransactionOutPoint disappears.
/**
* Locates the referenced output from the given pool of transactions.
*
* @return The TransactionOutput or null if the transactions map doesn't contain the referenced tx.
*/
TransactionOutput getConnectedOutput(Map<Sha256Hash, Transaction> transactions) {
Transaction tx = transactions.get(outpoint.getHash());
if (tx == null)
return null;
TransactionOutput out = tx.getOutputs().get((int) outpoint.getIndex());
return out;
}
enum ConnectMode {
DISCONNECT_ON_CONFLICT,
ABORT_ON_CONFLICT
}
/**
* Connects this input to the relevant output of the referenced transaction if it's in the given map.
* Connecting means updating the internal pointers and spent flags. If the mode is to ABORT_ON_CONFLICT then
* the spent output won't be changed, but the outpoint.fromTx pointer will still be updated.
*
* @param transactions Map of txhash->transaction.
* @param mode Whether to abort if there's a pre-existing connection or not.
* @return NO_SUCH_TX if the prevtx wasn't found, ALREADY_SPENT if there was a conflict, SUCCESS if not.
*/
public ConnectionResult connect(Map<Sha256Hash, Transaction> transactions, ConnectMode mode) {
Transaction tx = transactions.get(outpoint.getHash());
if (tx == null) {
return TransactionInput.ConnectionResult.NO_SUCH_TX;
}
return connect(tx, mode);
}
/**
* Connects this input to the relevant output of the referenced transaction.
* Connecting means updating the internal pointers and spent flags. If the mode is to ABORT_ON_CONFLICT then
* the spent output won't be changed, but the outpoint.fromTx pointer will still be updated.
*
* @param transaction The transaction to try.
* @param mode Whether to abort if there's a pre-existing connection or not.
* @return NO_SUCH_TX if transaction is not the prevtx, ALREADY_SPENT if there was a conflict, SUCCESS if not.
*/
public ConnectionResult connect(Transaction transaction, ConnectMode mode) {
if (!transaction.getHash().equals(outpoint.getHash()) && mode != ConnectMode.DISCONNECT_ON_CONFLICT)
return ConnectionResult.NO_SUCH_TX;
checkElementIndex((int) outpoint.getIndex(), transaction.getOutputs().size(), "Corrupt transaction");
TransactionOutput out = transaction.getOutput((int) outpoint.getIndex());
if (!out.isAvailableForSpending()) {
if (mode == ConnectMode.DISCONNECT_ON_CONFLICT) {
out.markAsUnspent();
} else if (mode == ConnectMode.ABORT_ON_CONFLICT) {
outpoint.fromTx = checkNotNull(out.parentTransaction);
return TransactionInput.ConnectionResult.ALREADY_SPENT;
}
}
connect(out);
return TransactionInput.ConnectionResult.SUCCESS;
}
/** Internal use only: connects this TransactionInput to the given output (updates pointers and spent flags) */
public void connect(TransactionOutput out) {
outpoint.fromTx = checkNotNull(out.parentTransaction);
out.markAsSpent(this);
}
/**
* If this input is connected, check the output is connected back to this input and release it if so, making
* it spendable once again.
*
* @return true if the disconnection took place, false if it was not connected.
*/
boolean disconnect() {
if (outpoint.fromTx == null) return false;
TransactionOutput output = outpoint.fromTx.getOutput((int) outpoint.getIndex());
if (output.getSpentBy() == this) {
output.markAsUnspent();
outpoint.fromTx = null;
return true;
} else {
return false;
}
}
/**
* Ensure object is fully parsed before invoking java serialization. The backing byte array
* is transient so if the object has parseLazy = true and hasn't invoked checkParse yet
* then data will be lost during serialization.
*/
private void writeObject(ObjectOutputStream out) throws IOException {
maybeParse();
out.defaultWriteObject();
}
public boolean hasSequence() {
return sequence != NO_SEQUENCE;
}
/**
* For a connected transaction, runs the script against the connected pubkey and verifies they are correct.
* @throws ScriptException if the script did not verify.
*/
public void verify() throws ScriptException {
Preconditions.checkNotNull(getOutpoint().fromTx, "Not connected");
long spendingIndex = getOutpoint().getIndex();
Script pubKey = getOutpoint().fromTx.getOutputs().get((int) spendingIndex).getScriptPubKey();
Script sig = getScriptSig();
int myIndex = parentTransaction.getInputs().indexOf(this);
sig.correctlySpends(parentTransaction, myIndex, pubKey, true);
}
}