feat: re-add bencode utility and fix tests to use bytearray instead of assuming utf-8 encoding for strings
0x330a
3 years ago
parent
7762d534bb
commit
d2e80c3157
@ -0,0 +1,169 @@
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package org.session.libsession.utilities.bencode
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import java.util.LinkedList
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object Bencode {
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class Decoder(source: ByteArray) {
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private val iterator = LinkedList<Byte>().apply {
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addAll(source.asIterable())
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}
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/**
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* Decode an element based on next marker assumed to be string/int/list/dict or return null
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*/
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fun decode(): BencodeElement? {
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val result = when (iterator.peek()?.toInt()?.toChar()) {
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in NUMBERS -> decodeString()
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INT_INDICATOR -> decodeInt()
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LIST_INDICATOR -> decodeList()
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DICT_INDICATOR -> decodeDict()
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else -> {
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null
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}
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}
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return result
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}
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/**
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* Decode a string element from iterator assumed to have structure `{length}:{data}`
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*/
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private fun decodeString(): BencodeString? {
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val lengthStrings = buildString {
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while (iterator.isNotEmpty() && iterator.peek()?.toInt()?.toChar() != SEPARATOR) {
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append(iterator.pop().toInt().toChar())
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}
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}
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iterator.pop() // drop `:`
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val length = lengthStrings.toIntOrNull(10) ?: return null
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val remaining = (0 until length).map { iterator.pop() }.toByteArray()
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return BencodeString(remaining)
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}
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/**
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* Decode an int element from iterator assumed to have structure `i{int}e`
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*/
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private fun decodeInt(): BencodeElement? {
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iterator.pop() // drop `i`
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val intString = buildString {
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while (iterator.isNotEmpty() && iterator.peek()?.toInt()?.toChar() != END_INDICATOR) {
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append(iterator.pop().toInt().toChar())
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}
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}
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val asInt = intString.toIntOrNull(10) ?: return null
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iterator.pop() // drop `e`
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return BencodeInteger(asInt)
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}
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/**
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* Decode a list element from iterator assumed to have structure `l{data}e`
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*/
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private fun decodeList(): BencodeElement {
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iterator.pop() // drop `l`
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val listElements = mutableListOf<BencodeElement>()
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while (iterator.isNotEmpty() && iterator.peek()?.toInt()?.toChar() != END_INDICATOR) {
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decode()?.let { nextElement ->
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listElements += nextElement
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}
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}
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iterator.pop() // drop `e`
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return BencodeList(listElements)
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}
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/**
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* Decode a dict element from iterator assumed to have structure `d{data}e`
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*/
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private fun decodeDict(): BencodeElement? {
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iterator.pop() // drop `d`
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val dictElements = mutableMapOf<String,BencodeElement>()
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while (iterator.isNotEmpty() && iterator.peek()?.toInt()?.toChar() != END_INDICATOR) {
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val key = decodeString() ?: return null
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val value = decode() ?: return null
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dictElements += key.value.decodeToString() to value
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}
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iterator.pop() // drop `e`
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return BencodeDict(dictElements)
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}
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companion object {
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private val NUMBERS = arrayOf('0', '1', '2', '3', '4', '5', '6', '7', '8', '9')
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private const val INT_INDICATOR = 'i'
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private const val LIST_INDICATOR = 'l'
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private const val DICT_INDICATOR = 'd'
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private const val END_INDICATOR = 'e'
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private const val SEPARATOR = ':'
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}
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}
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}
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sealed class BencodeElement {
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abstract fun encode(): ByteArray
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}
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fun String.bencode() = BencodeString(this.encodeToByteArray())
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fun Int.bencode() = BencodeInteger(this)
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data class BencodeString(val value: ByteArray): BencodeElement() {
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override fun encode(): ByteArray = buildString {
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append(value.size.toString())
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append(':')
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}.toByteArray() + value
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override fun equals(other: Any?): Boolean {
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if (this === other) return true
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if (javaClass != other?.javaClass) return false
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other as BencodeString
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if (!value.contentEquals(other.value)) return false
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return true
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}
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override fun hashCode(): Int {
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return value.contentHashCode()
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}
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}
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data class BencodeInteger(val value: Int): BencodeElement() {
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override fun encode(): ByteArray = buildString {
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append('i')
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append(value.toString())
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append('e')
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}.toByteArray()
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}
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data class BencodeList(val values: List<BencodeElement>): BencodeElement() {
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constructor(vararg values: BencodeElement) : this(values.toList())
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override fun encode(): ByteArray = "l".toByteArray() +
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values.fold(byteArrayOf()) { array, element -> array + element.encode() } +
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"e".toByteArray()
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}
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data class BencodeDict(val values: Map<String, BencodeElement>): BencodeElement() {
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constructor(vararg values: Pair<String, BencodeElement>) : this(values.toMap())
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override fun encode(): ByteArray = "d".toByteArray() +
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values.entries.fold(byteArrayOf()) { array, (key, value) ->
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array + key.bencode().encode() + value.encode()
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} + "e".toByteArray()
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override fun equals(other: Any?): Boolean {
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if (this === other) return true
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if (javaClass != other?.javaClass) return false
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other as BencodeDict
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if (values != other.values) return false
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return true
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}
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override fun hashCode(): Int {
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return values.hashCode()
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}
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}
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@ -0,0 +1,107 @@
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package org.session.libsession.utilities
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import org.junit.Assert.assertArrayEquals
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import org.junit.Assert.assertEquals
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import org.junit.Test
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import org.session.libsession.utilities.bencode.Bencode
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import org.session.libsession.utilities.bencode.BencodeDict
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import org.session.libsession.utilities.bencode.BencodeInteger
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import org.session.libsession.utilities.bencode.BencodeList
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import org.session.libsession.utilities.bencode.bencode
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class BencoderTest {
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@Test
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fun `it should decode a basic string`() {
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val basicString = "5:howdy".toByteArray()
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val bencoder = Bencode.Decoder(basicString)
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val result = bencoder.decode()
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assertEquals("howdy".bencode(), result)
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}
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@Test
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fun `it should decode a basic integer`() {
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val basicInteger = "i3e".toByteArray()
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val bencoder = Bencode.Decoder(basicInteger)
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val result = bencoder.decode()
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assertEquals(BencodeInteger(3), result)
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}
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@Test
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fun `it should decode a list of integers`() {
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val basicIntList = "li1ei2ee".toByteArray()
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val bencoder = Bencode.Decoder(basicIntList)
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val result = bencoder.decode()
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assertEquals(
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BencodeList(
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1.bencode(),
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2.bencode()
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),
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result
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)
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}
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@Test
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fun `it should decode a basic dict`() {
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val basicDict = "d4:spaml1:a1:bee".toByteArray()
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val bencoder = Bencode.Decoder(basicDict)
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val result = bencoder.decode()
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assertEquals(
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BencodeDict(
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"spam" to BencodeList(
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"a".bencode(),
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"b".bencode()
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)
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),
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result
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)
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}
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@Test
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fun `it should encode a basic string`() {
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val basicString = "5:howdy".toByteArray()
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val element = "howdy".bencode()
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assertArrayEquals(basicString, element.encode())
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}
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@Test
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fun `it should encode a basic int`() {
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val basicInt = "i3e".toByteArray()
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val element = 3.bencode()
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assertArrayEquals(basicInt, element.encode())
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}
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@Test
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fun `it should encode a basic list`() {
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val basicList = "li1ei2ee".toByteArray()
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val element = BencodeList(1.bencode(),2.bencode())
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assertArrayEquals(basicList, element.encode())
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}
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@Test
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fun `it should encode a basic dict`() {
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val basicDict = "d4:spaml1:a1:bee".toByteArray()
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val element = BencodeDict(
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"spam" to BencodeList(
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"a".bencode(),
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"b".bencode()
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)
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)
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assertArrayEquals(basicDict, element.encode())
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}
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@Test
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fun `it should encode a more complex real world case`() {
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val source = "d15:lastReadMessaged66:031122334455667788990011223344556677889900112233445566778899001122i1234568790e66:051122334455667788990011223344556677889900112233445566778899001122i1234568790ee5:seqNoi1ee".toByteArray()
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val result = Bencode.Decoder(source).decode()
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val expected = BencodeDict(
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"lastReadMessage" to BencodeDict(
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"051122334455667788990011223344556677889900112233445566778899001122" to 1234568790.bencode(),
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"031122334455667788990011223344556677889900112233445566778899001122" to 1234568790.bencode()
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),
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"seqNo" to BencodeInteger(1)
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)
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assertEquals(expected, result)
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}
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}
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