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Kotlin Multiplatform Mobile framework for optimal code sharing between iOS and Android.
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/*
* Copyright (c) 2012, 2018, Oracle and/or its affiliates. All rights reserved.
* DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
*
* This code is free software; you can redistribute it and/or modify it
* under the terms of the GNU General Public License version 2 only, as
* published by the Free Software Foundation. Oracle designates this
* particular file as subject to the "Classpath" exception as provided
* by Oracle in the LICENSE file that accompanied this code.
*
* This code is distributed in the hope that it will be useful, but WITHOUT
* ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
* FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
* version 2 for more details (a copy is included in the LICENSE file that
* accompanied this code).
*
* You should have received a copy of the GNU General Public License version
* 2 along with this work; if not, write to the Free Software Foundation,
* Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
*
* Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
* or visit www.oracle.com if you need additional information or have any
* questions.
*/
package com.paoapps.fifi.utils
import kotlin.math.min
/**
* This class consists exclusively of static methods for obtaining
* encoders and decoders for the Base64 encoding scheme. The
* implementation of this class supports the following types of Base64
* as specified in
* [RFC 4648](http://www.ietf.org/rfc/rfc4648.txt) and
* [RFC 2045](http://www.ietf.org/rfc/rfc2045.txt).
*
*
* * **Basic**
*
* Uses "The Base64 Alphabet" as specified in Table 1 of
* RFC 4648 and RFC 2045 for encoding and decoding operation.
* The encoder does not add any line feed (line separator)
* character. The decoder rejects data that contains characters
* outside the base64 alphabet.
*
* * **URL and Filename safe**
*
* Uses the "URL and Filename safe Base64 Alphabet" as specified
* in Table 2 of RFC 4648 for encoding and decoding. The
* encoder does not add any line feed (line separator) character.
* The decoder rejects data that contains characters outside the
* base64 alphabet.
*
* * **MIME**
*
* Uses "The Base64 Alphabet" as specified in Table 1 of
* RFC 2045 for encoding and decoding operation. The encoded output
* must be represented in lines of no more than 76 characters each
* and uses a carriage return `'\r'` followed immediately by
* a linefeed `'\n'` as the line separator. No line separator
* is added to the end of the encoded output. All line separators
* or other characters not found in the base64 alphabet table are
* ignored in decoding operation.
*
*
*
* Unless otherwise noted, passing a `null` argument to a
* method of this class will cause a [ NullPointerException][java.lang.NullPointerException] to be thrown.
*
* @author Xueming Shen
* @since 1.8
*/
object Base64 {
fun ByteArray.encodeToBase64(): String {
return encoder.encode(this).decodeToString()
}
fun String.decodeFromBase64(): ByteArray {
return decoder.decode(this.encodeToByteArray())
}
/**
* Returns a [Encoder] that encodes using the
* [Basic](#basic) type base64 encoding scheme.
*
* @return A Base64 encoder.
*/
val encoder = Encoder(null, -1, true)
/**
* Returns a [Decoder] that decodes using the
* [Basic](#basic) type base64 encoding scheme.
*
* @return A Base64 decoder.
*/
val decoder = Decoder()
/**
* This class implements an encoder for encoding byte data using
* the Base64 encoding scheme as specified in RFC 4648 and RFC 2045.
*
*
* Instances of [Encoder] class are safe for use by
* multiple concurrent threads.
*
*
* Unless otherwise noted, passing a `null` argument to
* a method of this class will cause a
* [NullPointerException][java.lang.NullPointerException] to
* be thrown.
*
* @see Decoder
*
* @since 1.8
*/
class Encoder internal constructor(private val newline: ByteArray?, private val linemax: Int, private val doPadding: Boolean) {
private fun outLength(srclen: Int): Int {
var len = 0
len = if (doPadding) {
4 * ((srclen + 2) / 3)
} else {
val n = srclen % 3
4 * (srclen / 3) + if (n == 0) 0 else n + 1
}
if (linemax > 0) // line separators
len += (len - 1) / linemax * newline!!.size
return len
}
/**
* Encodes all bytes from the specified byte array into a newly-allocated
* byte array using the [Base64] encoding scheme. The returned byte
* array is of the length of the resulting bytes.
*
* @param src
* the byte array to encode
* @return A newly-allocated byte array containing the resulting
* encoded bytes.
*/
fun encode(src: ByteArray): ByteArray {
val len = outLength(src.size) // dst array size
val dst = ByteArray(len)
val ret = encode0(src, 0, src.size, dst)
return if (ret != dst.size) dst.copyOf(ret) else dst
}
private fun encodeBlock(src: ByteArray, sp: Int, sl: Int, dst: ByteArray, dp: Int) {
var sp0 = sp
var dp0 = dp
while (sp0 < sl) {
val bits: Int = src[sp0++].toInt() and 0xff shl 16 or (
src[sp0++].toInt() and 0xff shl 8) or
(src[sp0++].toInt() and 0xff)
dst[dp0++] = toBase64[bits ushr 18 and 0x3f].toByte()
dst[dp0++] = toBase64[bits ushr 12 and 0x3f].toByte()
dst[dp0++] = toBase64[bits ushr 6 and 0x3f].toByte()
dst[dp0++] = toBase64[bits and 0x3f].toByte()
}
}
private fun encode0(src: ByteArray, off: Int, end: Int, dst: ByteArray): Int {
val base64 = toBase64
var sp = off
var slen = (end - off) / 3 * 3
val sl = off + slen
if (linemax > 0 && slen > linemax / 4 * 3) slen = linemax / 4 * 3
var dp = 0
while (sp < sl) {
val sl0: Int = min(sp + slen, sl)
encodeBlock(src, sp, sl0, dst, dp)
val dlen = (sl0 - sp) / 3 * 4
dp += dlen
sp = sl0
if (dlen == linemax && sp < end) {
for (b in newline!!) {
dst[dp++] = b
}
}
}
if (sp < end) { // 1 or 2 leftover bytes
val b0: Int = src[sp++].toInt() and 0xff
dst[dp++] = base64[b0 shr 2].toByte()
if (sp == end) {
dst[dp++] = base64[b0 shl 4 and 0x3f].toByte()
if (doPadding) {
dst[dp++] = '='.toByte()
dst[dp++] = '='.toByte()
}
} else {
val b1: Int = src[sp++].toInt() and 0xff
dst[dp++] = base64[b0 shl 4 and 0x3f or (b1 shr 4)].toByte()
dst[dp++] = base64[b1 shl 2 and 0x3f].toByte()
if (doPadding) {
dst[dp++] = '='.toByte()
}
}
}
return dp
}
companion object {
/**
* This array is a lookup table that translates 6-bit positive integer
* index values into their "Base64 Alphabet" equivalents as specified
* in "Table 1: The Base64 Alphabet" of RFC 2045 (and RFC 4648).
*/
val toBase64 = charArrayOf(
'A', 'B', 'C', 'D', 'E', 'F', 'G', 'H', 'I', 'J', 'K', 'L', 'M',
'N', 'O', 'P', 'Q', 'R', 'S', 'T', 'U', 'V', 'W', 'X', 'Y', 'Z',
'a', 'b', 'c', 'd', 'e', 'f', 'g', 'h', 'i', 'j', 'k', 'l', 'm',
'n', 'o', 'p', 'q', 'r', 's', 't', 'u', 'v', 'w', 'x', 'y', 'z',
'0', '1', '2', '3', '4', '5', '6', '7', '8', '9', '+', '/'
)
/**
* It's the lookup table for "URL and Filename safe Base64" as specified
* in Table 2 of the RFC 4648, with the '+' and '/' changed to '-' and
* '_'. This table is used when BASE64_URL is specified.
*/
internal val toBase64URL = charArrayOf(
'A', 'B', 'C', 'D', 'E', 'F', 'G', 'H', 'I', 'J', 'K', 'L', 'M',
'N', 'O', 'P', 'Q', 'R', 'S', 'T', 'U', 'V', 'W', 'X', 'Y', 'Z',
'a', 'b', 'c', 'd', 'e', 'f', 'g', 'h', 'i', 'j', 'k', 'l', 'm',
'n', 'o', 'p', 'q', 'r', 's', 't', 'u', 'v', 'w', 'x', 'y', 'z',
'0', '1', '2', '3', '4', '5', '6', '7', '8', '9', '-', '_'
)
}
}
/**
* This class implements a decoder for decoding byte data using the
* Base64 encoding scheme as specified in RFC 4648 and RFC 2045.
*
*
* The Base64 padding character `'='` is accepted and
* interpreted as the end of the encoded byte data, but is not
* required. So if the final unit of the encoded byte data only has
* two or three Base64 characters (without the corresponding padding
* character(s) padded), they are decoded as if followed by padding
* character(s). If there is a padding character present in the
* final unit, the correct number of padding character(s) must be
* present, otherwise `IllegalArgumentException` (
* `IOException` when reading from a Base64 stream) is thrown
* during decoding.
*
*
* Instances of [Decoder] class are safe for use by
* multiple concurrent threads.
*
*
* Unless otherwise noted, passing a `null` argument to
* a method of this class will cause a
* [NullPointerException][java.lang.NullPointerException] to
* be thrown.
*
* @see Encoder
*
* @since 1.8
*/
class Decoder {
companion object {
/**
* Lookup table for decoding unicode characters drawn from the
* "Base64 Alphabet" (as specified in Table 1 of RFC 2045) into
* their 6-bit positive integer equivalents. Characters that
* are not in the Base64 alphabet but fall within the bounds of
* the array are encoded to -1.
*
*/
internal val fromBase64 = IntArray(256)
/**
* Lookup table for decoding "URL and Filename safe Base64 Alphabet"
* as specified in Table2 of the RFC 4648.
*/
private val fromBase64URL = IntArray(256)
init {
fromBase64.fill(-1)
for (i in Encoder.toBase64.indices) fromBase64[Encoder.toBase64[i].toInt()] = i
fromBase64['='.toInt()] = -2
}
init {
fromBase64URL.fill(-1)
for (i in Encoder.toBase64URL.indices) fromBase64URL[Encoder.toBase64URL[i].toInt()] = i
fromBase64URL['='.toInt()] = -2
}
}
/**
* Decodes all bytes from the input byte array using the [Base64]
* encoding scheme, writing the results into a newly-allocated output
* byte array. The returned byte array is of the length of the resulting
* bytes.
*
* @param src
* the byte array to decode
*
* @return A newly-allocated byte array containing the decoded bytes.
*
* @throws IllegalArgumentException
* if `src` is not in valid Base64 scheme
*/
fun decode(src: ByteArray): ByteArray {
var dst = ByteArray(outLength(src, 0, src.size))
val ret = decode0(src, 0, src.size, dst)
if (ret != dst.size) {
dst = dst.copyOf(ret)
}
return dst
}
private fun outLength(src: ByteArray, sp: Int, sl: Int): Int {
var sp = sp
var paddings = 0
var len = sl - sp
if (len == 0) return 0
if (len < 2) {
throw IllegalArgumentException(
"Input byte[] should at least have 2 bytes for base64 bytes"
)
}
if (src[sl - 1].toChar() == '=') {
paddings++
if (src[sl - 2].toChar() == '=') paddings++
}
if (paddings == 0 && len and 0x3 != 0) paddings = 4 - (len and 0x3)
return 3 * ((len + 3) / 4) - paddings
}
private fun decode0(src: ByteArray, sp: Int, sl: Int, dst: ByteArray): Int {
var sp = sp
val base64 = if (false) fromBase64URL else fromBase64
var dp = 0
var bits = 0
var shiftto = 18 // pos of first byte of 4-byte atom
while (sp < sl) {
if (shiftto == 18 && sp + 4 < sl) { // fast path
val sl0 = sp + (sl - sp and 3.inv())
while (sp < sl0) {
val b1 = base64[src[sp++].toInt() and 0xff]
val b2 = base64[src[sp++].toInt() and 0xff]
val b3 = base64[src[sp++].toInt() and 0xff]
val b4 = base64[src[sp++].toInt() and 0xff]
if (b1 or b2 or b3 or b4 < 0) { // non base64 byte
sp -= 4
break
}
val bits0 = b1 shl 18 or (b2 shl 12) or (b3 shl 6) or b4
dst[dp++] = (bits0 shr 16).toByte()
dst[dp++] = (bits0 shr 8).toByte()
dst[dp++] = bits0.toByte()
}
if (sp >= sl) break
}
var b: Int = src[sp++].toInt() and 0xff
if (base64[b].also { b = it } < 0) {
if (b == -2) { // padding byte '='
// = shiftto==18 unnecessary padding
// x= shiftto==12 a dangling single x
// x to be handled together with non-padding case
// xx= shiftto==6&&sp==sl missing last =
// xx=y shiftto==6 last is not =
require(
!(shiftto == 6 && (sp == sl || src[sp++].toChar() != '=') ||
shiftto == 18)
) { "Input byte array has wrong 4-byte ending unit" }
break
}
throw IllegalArgumentException("Illegal base64 character " + src[sp - 1].toInt().toString(16))
}
bits = bits or (b shl shiftto)
shiftto -= 6
if (shiftto < 0) {
dst[dp++] = (bits shr 16).toByte()
dst[dp++] = (bits shr 8).toByte()
dst[dp++] = bits.toByte()
shiftto = 18
bits = 0
}
}
// reached end of byte array or hit padding '=' characters.
when (shiftto) {
6 -> {
dst[dp++] = (bits shr 16).toByte()
}
0 -> {
dst[dp++] = (bits shr 16).toByte()
dst[dp++] = (bits shr 8).toByte()
}
else -> require(shiftto != 12) {
// dangling single "x", incorrectly encoded.
"Last unit does not have enough valid bits"
}
}
// anything left is invalid, if is not MIME.
// if MIME, ignore all non-base64 character
while (sp < sl) {
throw IllegalArgumentException(
"Input byte array has incorrect ending byte at $sp"
)
}
return dp
}
}
}