kitetorrent/io.github.yuroyami.kitetorrent.protocol/Handshake/Companion

Companion

object Companion

Properties

const val DHT_FLAG: Int = 1

DHT-support flag, OR'd into reserved byte 7 (BEP-5).

const val EXTENSION_FLAG: Int = 16

Extension-protocol flag, OR'd into reserved byte 5 (BEP-10).

const val FAST_FLAG: Int = 4

Fast-extension flag, OR'd into reserved byte 7 (BEP-6).

const val LENGTH: Int

Total on-the-wire size of a handshake: 1 + 19 + 8 + 20 + 20.

PROTOCOL_STRING

const val PROTOCOL_STRING: String

The BitTorrent v1 protocol identifier string ("pstr").

const val PSTRLEN: Int = 19

The single length-prefix byte: the length of PROTOCOL_STRING.

const val V2_FLAG: Int = 16

v2-upgrade flag, OR'd into reserved byte 7 (BEP-52).

Functions

fun buildReserved(dht: Boolean = true, fast: Boolean = true, extended: Boolean = true, v2: Boolean = false): ByteArray

Build an 8-byte reserved block advertising exactly the chosen capabilities. Mirrors the OR-into-reserved logic of write_handshake():

fun decode(bytes: ByteArray): Handshake?

Parse a 68-byte handshake. Returns null if bytes is shorter than LENGTH, if the length prefix is not 19, or if the protocol string does not match, which means the peer is not speaking BitTorrent v1. Bytes beyond LENGTH are ignored (they belong to subsequent messages on the stream).

defaultReserved

fun defaultReserved(v2: Boolean = false): ByteArray

Build the 8-byte reserved block libtorrent emits by default: DHT + Fast + Extension-protocol bits set (matching write_handshake() with all features compiled in, minus the v2-upgrade bit which depends on torrent state).

fun encode(infoHash: Sha1Hash, peerId: Sha1Hash, reserved: ByteArray = defaultReserved()): ByteArray

Encode a handshake. reserved must be exactly 8 bytes; it defaults to defaultReserved. Mirrors the byte order written by write_handshake().