/**
* 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.devcoin.core;
import com.google.devcoin.script.Script;
import com.google.devcoin.script.ScriptBuilder;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
import javax.annotation.Nullable;
import java.io.IOException;
import java.io.ObjectOutputStream;
import java.io.OutputStream;
import java.io.Serializable;
import java.math.BigInteger;
import static com.google.common.base.Preconditions.checkArgument;
import static com.google.common.base.Preconditions.checkNotNull;
import static com.google.common.base.Preconditions.checkState;
/**
* A TransactionOutput message contains a scriptPubKey that controls who is able to spend its value. It is a sub-part
* of the Transaction message.
*/
public class TransactionOutput extends ChildMessage implements Serializable {
private static final Logger log = LoggerFactory.getLogger(TransactionOutput.class);
private static final long serialVersionUID = -590332479859256824L;
// A transaction output has some value and a script used for authenticating that the redeemer is allowed to spend
// this output.
private BigInteger value;
private byte[] scriptBytes;
// The script bytes are parsed and turned into a Script on demand.
private transient Script scriptPubKey;
// These fields are Java serialized but not Bitcoin serialized. They are used for tracking purposes in our wallet
// only. If set to true, this output is counted towards our balance. If false and spentBy is null the tx output
// was owned by us and was sent to somebody else. If false and spentBy is set it means this output was owned by
// us and used in one of our own transactions (eg, because it is a change output).
private boolean availableForSpending;
private TransactionInput spentBy;
// A reference to the transaction which holds this output.
Transaction parentTransaction;
private transient int scriptLen;
/**
* Deserializes a transaction output message. This is usually part of a transaction message.
*/
public TransactionOutput(NetworkParameters params, Transaction parent, byte[] payload,
int offset) throws ProtocolException {
super(params, payload, offset);
parentTransaction = parent;
availableForSpending = true;
}
/**
* Deserializes a transaction output message. This is usually part of a transaction message.
*
* @param params NetworkParameters object.
* @param msg Bitcoin 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.
* @throws ProtocolException
*/
public TransactionOutput(NetworkParameters params, Transaction parent, byte[] msg, int offset,
boolean parseLazy, boolean parseRetain) throws ProtocolException {
super(params, msg, offset, parent, parseLazy, parseRetain, UNKNOWN_LENGTH);
parentTransaction = parent;
availableForSpending = true;
}
/**
* Creates an output that sends 'value' to the given address (public key hash). The amount should be created with
* something like {@link Utils#toNanoCoins(int, int)}. Typically you would use
* {@link Transaction#addOutput(java.math.BigInteger, Address)} instead of creating a TransactionOutput directly.
*/
public TransactionOutput(NetworkParameters params, Transaction parent, BigInteger value, Address to) {
this(params, parent, value, ScriptBuilder.createOutputScript(to).getProgram());
}
/**
* Creates an output that sends 'value' to the given public key using a simple CHECKSIG script (no addresses). The
* amount should be created with something like {@link Utils#toNanoCoins(int, int)}. Typically you would use
* {@link Transaction#addOutput(java.math.BigInteger, ECKey)} instead of creating an output directly.
*/
public TransactionOutput(NetworkParameters params, Transaction parent, BigInteger value, ECKey to) {
this(params, parent, value, ScriptBuilder.createOutputScript(to).getProgram());
}
public TransactionOutput(NetworkParameters params, Transaction parent, BigInteger 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.compareTo(BigInteger.ZERO) >= 0 || value.equals(Utils.NEGATIVE_ONE), "Negative values not allowed");
checkArgument(value.compareTo(NetworkParameters.MAX_MONEY) < 0, "Values larger than MAX_MONEY not allowed");
this.value = value;
this.scriptBytes = scriptBytes;
parentTransaction = parent;
availableForSpending = true;
length = 8 + VarInt.sizeOf(scriptBytes.length) + scriptBytes.length;
}
public Script getScriptPubKey() throws ScriptException {
if (scriptPubKey == null) {
maybeParse();
scriptPubKey = new Script(scriptBytes);
}
return scriptPubKey;
}
protected void parseLite() throws ProtocolException {
// TODO: There is no reason to use BigInteger for values, they are always smaller than 21 million * COIN
// The only reason to use BigInteger would be to properly read values from the reference implementation, however
// the reference implementation uses signed 64-bit integers for its values as well (though it probably shouldn't)
long outputValue = readInt64();
value = BigInteger.valueOf(outputValue);
scriptLen = (int) readVarInt();
length = cursor - offset + scriptLen;
}
void parse() throws ProtocolException {
scriptBytes = readBytes(scriptLen);
}
@Override
protected void bitcoinSerializeToStream(OutputStream stream) throws IOException {
checkNotNull(scriptBytes);
Utils.int64ToByteStreamLE(getValue().longValue(), stream);
// TODO: Move script serialization into the Script class, where it belongs.
stream.write(new VarInt(scriptBytes.length).encode());
stream.write(scriptBytes);
}
/**
* Returns the value of this output in nanocoins. This is the amount of currency that the destination address
* receives.
*/
public BigInteger getValue() {
maybeParse();
return value;
}
/**
* Sets the value of this output in nanocoins.
*/
public void setValue(BigInteger value) {
checkNotNull(value);
unCache();
this.value = value;
}
int getIndex() {
checkNotNull(parentTransaction);
for (int i = 0; i < parentTransaction.getOutputs().size(); i++) {
if (parentTransaction.getOutputs().get(i) == this)
return i;
}
// Should never happen.
throw new RuntimeException("Output linked to wrong parent transaction?");
}
/**
* <p>Gets the minimum value for a txout of this size to be considered non-dust by a reference client
* (and thus relayed). See: CTxOut::IsDust() in the reference client. The assumption is that any output that would
* consume more than a third of its value in fees is not something the Bitcoin system wants to deal with right now,
* so we call them "dust outputs" and they're made non standard. The choice of one third is somewhat arbitrary and
* may change in future.</p>
*
* <p>You probably should use {@link com.google.devcoin.core.TransactionOutput#getMinNonDustValue()} which uses
* a safe fee-per-kb by default.</p>
*
* @param feePerKbRequired The fee required per kilobyte. Note that this is the same as the reference client's -minrelaytxfee * 3
* If you want a safe default, use {@link Transaction#REFERENCE_DEFAULT_MIN_TX_FEE}*3
*/
public BigInteger getMinNonDustValue(BigInteger feePerKbRequired) {
// A typical output is 33 bytes (pubkey hash + opcodes) and requires an input of 148 bytes to spend so we add
// that together to find out the total amount of data used to transfer this amount of value. Note that this
// formula is wrong for anything that's not a pay-to-address output, unfortunately, we must follow the reference
// clients wrongness in order to ensure we're considered standard. A better formula would either estimate the
// size of data needed to satisfy all different script types, or just hard code 33 below.
final BigInteger size = BigInteger.valueOf(this.bitcoinSerialize().length + 148);
BigInteger[] nonDustAndRemainder = feePerKbRequired.multiply(size).divideAndRemainder(BigInteger.valueOf(1000));
return nonDustAndRemainder[1].equals(BigInteger.ZERO) ? nonDustAndRemainder[0] : nonDustAndRemainder[0].add(BigInteger.ONE);
}
/**
* Returns the minimum value for this output to be considered "not dust", i.e. the transaction will be relayable
* and mined by default miners. For normal pay to address outputs, this is 5460 satoshis, the same as
* {@link Transaction#MIN_NONDUST_OUTPUT}.
*/
public BigInteger getMinNonDustValue() {
return getMinNonDustValue(BigInteger.valueOf(10000).multiply(BigInteger.valueOf(3)));
}
/**
* Sets this objects availableForSpending flag to false and the spentBy pointer to the given input.
* If the input is null, it means this output was signed over to somebody else rather than one of our own keys.
* @throws IllegalStateException if the transaction was already marked as spent.
*/
public void markAsSpent(TransactionInput input) {
checkState(availableForSpending);
availableForSpending = false;
spentBy = input;
}
/**
* Resets the spent pointer / availableForSpending flag to null.
*/
public void markAsUnspent() {
availableForSpending = true;
spentBy = null;
}
/**
* Returns whether {@link TransactionOutput#markAsSpent(TransactionInput)} has been called on this class. A
* {@link Wallet} will mark a transaction output as spent once it sees a transaction input that is connected to it.
* Note that this flag can be false when an output has in fact been spent according to the rest of the network if
* the spending transaction wasn't downloaded yet, and it can be marked as spent when in reality the rest of the
* network believes it to be unspent if the signature or script connecting to it was not actually valid.
*/
public boolean isAvailableForSpending() {
return availableForSpending;
}
/**
* The backing script bytes which can be turned into a Script object.
* @return the scriptBytes
*/
public byte[] getScriptBytes() {
maybeParse();
return scriptBytes;
}
/**
* Returns true if this output is to a key, or an address we have the keys for, in the wallet.
*/
public boolean isMine(Wallet wallet) {
try {
Script script = getScriptPubKey();
if (script.isSentToRawPubKey()) {
byte[] pubkey = script.getPubKey();
return wallet.isPubKeyMine(pubkey);
} else {
byte[] pubkeyHash = script.getPubKeyHash();
return wallet.isPubKeyHashMine(pubkeyHash);
}
} catch (ScriptException e) {
// Just means we didn't understand the output of this transaction: ignore it.
log.debug("Could not parse tx output script: {}", e.toString());
return false;
}
}
/**
* Returns a human readable debug string.
*/
public String toString() {
try {
return "TxOut of " + Utils.bitcoinValueToFriendlyString(value) + " to " +
getScriptPubKey().getToAddress(params).toString() + " script:" + getScriptPubKey().toString();
} catch (ScriptException e) {
throw new RuntimeException(e);
}
}
/**
* Returns the connected input.
*/
public TransactionInput getSpentBy() {
return spentBy;
}
/**
* Returns the transaction that owns this output, or null if this is a free standing object.
*/
@Nullable
public Transaction getParentTransaction() {
return parentTransaction;
}
/**
* 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();
}
}