Package org.bitcoinj.core

Class VersionMessage

  • public class VersionMessage
extends Message

    A VersionMessage holds information exchanged during connection setup with another peer. Most of the fields are not particularly interesting. The subVer field, since BIP 14, acts as a User-Agent string would. You can and should append to or change the subVer for your own software so other implementations can identify it, and you can look at the subVer field received from other nodes to see what they are running.

    After creating yourself a VersionMessage, you can pass it to PeerGroup.setVersionMessage(VersionMessage) to ensure it will be used for each new connection.

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

    • Field Detail

      • BITCOINJ_VERSION

        public static final java.lang.String BITCOINJ_VERSION
        The version of this library release, as a string.
        See Also:
        Constant Field Values

      • LIBRARY_SUBVER

        public static final java.lang.String LIBRARY_SUBVER
        The value that is prepended to the subVer field of this application.
        See Also:
        Constant Field Values

      • NODE_NETWORK

        public static final int NODE_NETWORK
        A service bit that denotes whether the peer has a full copy of the block chain or not.
        See Also:
        Constant Field Values

      • NODE_BLOOM

        public static final int NODE_BLOOM
        A service bit that denotes whether the peer supports BIP37 bloom filters or not. The service bit is defined in BIP111.
        See Also:
        Constant Field Values

      • NODE_WITNESS

        public static final int NODE_WITNESS
        Indicates that a node can be asked for blocks and transactions including witness data.
        See Also:
        Constant Field Values

      • NODE_NETWORK_LIMITED

        public static final int NODE_NETWORK_LIMITED
        A service bit that denotes whether the peer has at least the last two days worth of blockchain (BIP159).
        See Also:
        Constant Field Values

      • NODE_BITCOIN_CASH

        public static final int NODE_BITCOIN_CASH
        A service bit used by Bitcoin-ABC to announce Bitcoin Cash nodes.
        See Also:
        Constant Field Values

      • clientVersion

        public int clientVersion
        The version number of the protocol spoken.

      • localServices

        public long localServices
        Flags defining what optional services are supported.

      • time

        public java.time.Instant time
        What the other side believes the current time to be.

      • receivingAddr

        public PeerAddress receivingAddr
        The network address of the node receiving this message.

      • fromAddr

        public PeerAddress fromAddr
        The network address of the node emitting this message. Not used.

      • subVer

        public java.lang.String subVer
        User-Agent as defined in BIP 14. Bitcoin Core sets it to something like "/Satoshi:0.9.1/".

      • bestHeight

        public long bestHeight
        How many blocks are in the chain, according to the other side.

      • relayTxesBeforeFilter

        public boolean relayTxesBeforeFilter
        Whether or not to relay tx invs before a filter is received. See BIP 37.

    • Method Detail

      • bitcoinSerializeToStream

        public void bitcoinSerializeToStream​(java.io.OutputStream buf)
                              throws java.io.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:
        java.io.IOException

      • equals

        public boolean equals​(java.lang.Object o)
        Overrides:
        equals in class java.lang.Object

      • hashCode

        public int hashCode()
        Overrides:
        hashCode in class java.lang.Object

      • toString

        public java.lang.String toString()
        Overrides:
        toString in class java.lang.Object

      • appendToSubVer

        public void appendToSubVer​(java.lang.String name,
                           java.lang.String version,
                           @Nullable
                           java.lang.String comments)

        Appends the given user-agent information to the subVer field. The subVer is composed of a series of name:version pairs separated by slashes in the form of a path. For example a typical subVer field for bitcoinj users might look like "/bitcoinj:0.13/MultiBit:1.2/" where libraries come further to the left.

        There can be as many components as you feel a need for, and the version string can be anything, but it is recommended to use A.B.C where A = major, B = minor and C = revision for software releases, and dates for auto-generated source repository snapshots. A valid subVer begins and ends with a slash, therefore name and version are not allowed to contain such characters.

        Anything put in the "comments" field will appear in brackets and may be used for platform info, or anything else. For example, calling appendToSubVer("MultiBit", "1.0", "Windows") will result in a subVer being set of "/bitcoinj:1.0/MultiBit:1.0(Windows)/". Therefore the / ( and ) characters are reserved in all these components. If you don't want to add a comment (recommended), pass null.

        See BIP 14 for more information.

        Parameters:
        comments - Optional (can be null) platform or other node specific information.
        Throws:
        java.lang.IllegalArgumentException - if name, version or comments contains invalid characters.

      • isBloomFilteringSupported

        public boolean isBloomFilteringSupported()
        Returns true if the peer supports bloom filtering according to BIP37 and BIP111.

      • isWitnessSupported

        public boolean isWitnessSupported()
        Returns true if a peer can be asked for blocks and transactions including witness data.

      • hasBlockChain

        public boolean hasBlockChain()
        Returns true if the version message indicates the sender has a full copy of the block chain, or false if it's running in client mode (only has the headers).

      • hasLimitedBlockChain

        public boolean hasLimitedBlockChain()
        Returns true if the peer has at least the last two days worth of blockchain (BIP159).

      • toStringServices

        public static java.lang.String toStringServices​(long services)