commonMain.io.ktor.util.Base64.kt Maven / Gradle / Ivy
/*
* Copyright 2014-2021 JetBrains s.r.o and contributors. Use of this source code is governed by the Apache 2.0 license.
*/
package io.ktor.util
import io.ktor.utils.io.charsets.*
import io.ktor.utils.io.core.*
import kotlin.experimental.*
private const val BASE64_ALPHABET = "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+/"
private const val BASE64_MASK: Byte = 0x3f
private const val BASE64_MASK_INT: Int = 0x3f
private const val BASE64_PAD = '='
private val BASE64_INVERSE_ALPHABET = IntArray(256) {
BASE64_ALPHABET.indexOf(it.toChar())
}
/**
* Encode [String] in base64 format and UTF-8 character encoding.
*/
public fun String.encodeBase64(): String = buildPacket {
writeText(this@encodeBase64)
}.encodeBase64()
/**
* Encode [ByteArray] in base64 format
*/
public fun ByteArray.encodeBase64(): String {
val array = this@encodeBase64
var position = 0
var writeOffset = 0
val charArray = CharArray(size * 8 / 6 + 3)
while (position + 3 <= array.size) {
val first = array[position].toInt()
val second = array[position + 1].toInt()
val third = array[position + 2].toInt()
position += 3
val chunk = ((first and 0xFF) shl 16) or ((second and 0xFF) shl 8) or (third and 0xFF)
for (index in 3 downTo 0) {
val char = (chunk shr (6 * index)) and BASE64_MASK_INT
charArray[writeOffset++] = (char.toBase64())
}
}
val remaining = array.size - position
if (remaining == 0) return charArray.concatToString(0, writeOffset)
val chunk = if (remaining == 1) {
((array[position].toInt() and 0xFF) shl 16) or ((0 and 0xFF) shl 8) or (0 and 0xFF)
} else {
((array[position].toInt() and 0xFF) shl 16) or ((array[position + 1].toInt() and 0xFF) shl 8) or (0 and 0xFF)
}
val padSize = (3 - remaining) * 8 / 6
for (index in 3 downTo padSize) {
val char = (chunk shr (6 * index)) and BASE64_MASK_INT
charArray[writeOffset++] = char.toBase64()
}
repeat(padSize) { charArray[writeOffset++] = BASE64_PAD }
return charArray.concatToString(0, writeOffset)
}
/**
* Encode [ByteReadPacket] in base64 format
*/
public fun ByteReadPacket.encodeBase64(): String = readBytes().encodeBase64()
/**
* Decode [String] from base64 format encoded in UTF-8.
*/
public fun String.decodeBase64String(): String = String(decodeBase64Bytes(), charset = Charsets.UTF_8)
/**
* Decode [String] from base64 format
*/
public fun String.decodeBase64Bytes(): ByteArray = buildPacket {
writeText(dropLastWhile { it == BASE64_PAD })
}.decodeBase64Bytes().readBytes()
/**
* Decode [ByteReadPacket] from base64 format
*/
public fun ByteReadPacket.decodeBase64Bytes(): Input = buildPacket {
val data = ByteArray(4)
while (remaining > 0) {
val read = readAvailable(data)
val chunk = data.foldIndexed(0) { index, result, current ->
result or (current.fromBase64().toInt() shl ((3 - index) * 6))
}
for (index in data.size - 2 downTo (data.size - read)) {
val origin = (chunk shr (8 * index)) and 0xff
writeByte(origin.toByte())
}
}
}
@Suppress("NOTHING_TO_INLINE")
internal inline fun Int.toBase64(): Char = BASE64_ALPHABET[this]
@Suppress("NOTHING_TO_INLINE")
internal inline fun Byte.fromBase64(): Byte = BASE64_INVERSE_ALPHABET[toInt() and 0xff].toByte() and BASE64_MASK