kotlinx-serialization-bencode

A Kotlin serialization codec for bencoding format. (Bittorrent)

Reference: https://www.bittorrent.org/beps/bep_0003.html

Usage

Add the dependency to your build.gradle.kts

dependencies {
  implementation("space.iseki.bencoding:kotlinx-serialization-bencoding:0.2.8")
}

@Serialization
data class Meta(val announce: String) // The torrent file format

fun foo(input: InputStream) {
    println(Bencode.decodeFromStream<Meta>(data.inputStream()))
}

Bencoding Format

The following content is copied from https://www.bittorrent.org/beps/bep_0003.html for a memo.

• Strings are length-prefixed base ten followed by a colon and the string. For example 4:spam corresponds to 'spam'.
• Integers are represented by an 'i' followed by the number in base 10 followed by an 'e'. For example i3e corresponds to 3 and i-3e corresponds to -3. Integers have no size limitation. i-0e is invalid. All encodings with a leading zero, such as i03e, are invalid, other than i0e, which of course corresponds to 0.
• Lists are encoded as an 'l' followed by their elements (also bencoded) followed by an 'e'. For example l4:spam4:eggse corresponds to ['spam', 'eggs'].
• Dictionaries are encoded as a 'd' followed by a list of alternating keys and their corresponding values followed by an 'e'. For example, d3:cow3:moo4:spam4:eggse corresponds to {'cow': 'moo', 'spam': 'eggs'} and d4:spaml1:a1:bee corresponds to {'spam': ['a', 'b']}. Keys must be strings and appear in sorted order (sorted as raw strings, not alphanumerics).