Package org.bitcoinj.core

Class UTXOsMessage

java.lang.Object

org.bitcoinj.core.Message

org.bitcoinj.core.UTXOsMessage

public class UTXOsMessage
extends Message

Message representing a list of unspent transaction outputs ("utxos"), returned in response to sending a GetUTXOsMessage ("getutxos"). Note that both this message and the query that generates it are not supported by Bitcoin Core. An implementation is available in Bitcoin XT, a patch set on top of Core. Thus if you want to use it, you must find some XT peers to connect to. This can be done using a HttpDiscovery class combined with an HTTP/Cartographer seed.

The getutxos/utxos protocol is defined in BIP 65. In that document you can find a discussion of the security of this protocol (briefly, there is none). Because the data found in this message is not authenticated it should be used carefully. Places where it can be useful are if you're querying your own trusted node, if you're comparing answers from multiple nodes simultaneously and don't believe there is a MITM on your connection, or if you're only using the returned data as a UI hint and it's OK if the data is occasionally wrong. Bear in mind that the answer can be wrong even in the absence of malicious intent just through the nature of querying an ever changing data source: the UTXO set may be updated by a new transaction immediately after this message is returned.

Instances of this class are not safe for use by multiple threads.

Field Summary

Fields

Modifier and Type	Field	Description
static long	MEMPOOL_HEIGHT	This is a special sentinel value that can appear in the heights field if the given tx is in the mempool.

Fields inherited from class org.bitcoinj.core.Message

cursor, length, MAX_SIZE, offset, params, payload, recached, serializer, UNKNOWN_LENGTH

Constructor Summary

Constructors

Constructor	Description
UTXOsMessage(NetworkParameters params, byte[] payloadBytes)
UTXOsMessage(NetworkParameters params, List<TransactionOutput> outputs, long[] heights, Sha256Hash chainHead, long height)	Provide an array of output objects, with nulls indicating that the output was missing.

Method Summary

Modifier and Type	Method	Description
protected void	bitcoinSerializeToStream(OutputStream stream)	Serializes this message to the provided stream.
boolean	equals(Object o)
long[]	getHeights()	Returns the block heights of each output returned in getOutputs(), or MEMPOOL_HEIGHT if not confirmed yet.
byte[]	getHitMap()	Returns a bit map indicating which of the queried outputs were found in the UTXO set.
List<TransactionOutput>	getOutputs()	Returns the list of outputs that matched the query.
int	hashCode()
protected void	parse()
String	toString()

Methods inherited from class org.bitcoinj.core.Message

adjustLength, bitcoinSerialize, bitcoinSerialize, getHash, getMessageSize, getParams, hasMoreBytes, isCached, isRecached, readByte, readByteArray, readBytes, readHash, readInt64, readStr, readUint32, readUint64, readVarInt, readVarInt, setSerializer, unCache, unsafeBitcoinSerialize

Methods inherited from class java.lang.Object

clone, finalize, getClass, notify, notifyAll, wait, wait, wait

Field Details

MEMPOOL_HEIGHT

public static long MEMPOOL_HEIGHT

This is a special sentinel value that can appear in the heights field if the given tx is in the mempool.

Constructor Details

UTXOsMessage

public UTXOsMessage(NetworkParameters params,
 byte[] payloadBytes)

UTXOsMessage

public UTXOsMessage(NetworkParameters params,
 List<TransactionOutput> outputs,
 long[] heights,
 Sha256Hash chainHead,
 long height)

Provide an array of output objects, with nulls indicating that the output was missing. The bitset will be calculated from this.

Method Details

bitcoinSerializeToStream

protected void bitcoinSerializeToStream(OutputStream stream)
                                 throws IOException

Description copied from class: Message

Serializes this message to the provided stream. If you just want the raw bytes use bitcoinSerialize().

Overrides:

bitcoinSerializeToStream in class Message

Throws:

IOException

parse

protected void parse()
              throws ProtocolException

Specified by:

parse in class Message

Throws:

ProtocolException

getHitMap

public byte[] getHitMap()

Returns a bit map indicating which of the queried outputs were found in the UTXO set.

getOutputs

public List<TransactionOutput> getOutputs()

Returns the list of outputs that matched the query.

getHeights

public long[] getHeights()

Returns the block heights of each output returned in getOutputs(), or MEMPOOL_HEIGHT if not confirmed yet.

toString

public String toString()

Overrides:

toString in class Object

equals

public boolean equals(Object o)

Overrides:

equals in class Object

hashCode

public int hashCode()

Overrides:

hashCode in class Object