/*
* Copyright 2023 The Android Open Source Project
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
package androidx.credentials.webauthn
import androidx.annotation.RestrictTo
import java.lang.IllegalArgumentException
@RestrictTo(RestrictTo.Scope.LIBRARY)
class Cbor {
data class Item(val item: Any, val len: Int)
data class Arg(val arg: Long, val len: Int)
val TYPE_UNSIGNED_INT = 0x00
val TYPE_NEGATIVE_INT = 0x01
val TYPE_BYTE_STRING = 0x02
val TYPE_TEXT_STRING = 0x03
val TYPE_ARRAY = 0x04
val TYPE_MAP = 0x05
val TYPE_TAG = 0x06
val TYPE_FLOAT = 0x07
fun decode(data: ByteArray): Any {
val ret = parseItem(data, 0)
return ret.item
}
fun encode(data: Any): ByteArray {
if (data is Number) {
if (data is Double) {
throw IllegalArgumentException("Don't support doubles yet")
} else {
val value = data.toLong()
if (value >= 0) {
return createArg(TYPE_UNSIGNED_INT, value)
} else {
return createArg(TYPE_NEGATIVE_INT, -1 - value)
}
}
}
if (data is ByteArray) {
return createArg(TYPE_BYTE_STRING, data.size.toLong()) + data
}
if (data is String) {
return createArg(TYPE_TEXT_STRING, data.length.toLong()) + data.encodeToByteArray()
}
if (data is List<*>) {
var ret = createArg(TYPE_ARRAY, data.size.toLong())
for (i in data) {
ret += encode(i!!)
}
return ret
}
if (data is Map<*, *>) {
// See:
// https://fidoalliance.org/specs/fido-v2.1-ps-20210615/fido-client-to-authenticator-protocol-v2.1-ps-20210615.html#ctap2-canonical-cbor-encoding-form
var ret = createArg(TYPE_MAP, data.size.toLong())
var byteMap: MutableMap<ByteArray, ByteArray> = mutableMapOf()
for (i in data) {
// Convert to byte arrays so we can sort them.
byteMap.put(encode(i.key!!), encode(i.value!!))
}
var keysList = ArrayList<ByteArray>(byteMap.keys)
keysList.sortedWith(
Comparator<ByteArray> { a, b ->
// If two keys have different lengths, the shorter one sorts earlier;
// If two keys have the same length, the one with the lower value in (byte-wise)
// lexical order sorts earlier.
var aBytes = byteMap.get(a)!!
var bBytes = byteMap.get(b)!!
when {
a.size > b.size -> 1
a.size < b.size -> -1
aBytes.size > bBytes.size -> 1
aBytes.size < bBytes.size -> -1
else -> 0
}
}
)
for (key in keysList) {
ret += key
ret += byteMap.get(key)!!
}
return ret
}
throw IllegalArgumentException("Bad type")
}
private fun getType(data: ByteArray, offset: Int): Int {
val d = data[offset].toInt()
return (d and 0xFF) shr 5
}
private fun getArg(data: ByteArray, offset: Int): Arg {
val arg = data[offset].toLong() and 0x1F
if (arg < 24) {
return Arg(arg, 1)
}
if (arg == 24L) {
return Arg(data[offset + 1].toLong() and 0xFF, 2)
}
if (arg == 25L) {
var ret = (data[offset + 1].toLong() and 0xFF) shl 8
ret = ret or (data[offset + 2].toLong() and 0xFF)
return Arg(ret, 3)
}
if (arg == 26L) {
var ret = (data[offset + 1].toLong() and 0xFF) shl 24
ret = ret or ((data[offset + 2].toLong() and 0xFF) shl 16)
ret = ret or ((data[offset + 3].toLong() and 0xFF) shl 8)
ret = ret or (data[offset + 4].toLong() and 0xFF)
return Arg(ret, 5)
}
throw IllegalArgumentException("Bad arg")
}
private fun parseItem(data: ByteArray, offset: Int): Item {
val itemType = getType(data, offset)
val arg = getArg(data, offset)
println("Type $itemType ${arg.arg} ${arg.len}")
when (itemType) {
TYPE_UNSIGNED_INT -> {
return Item(arg.arg, arg.len)
}
TYPE_NEGATIVE_INT -> {
return Item(-1 - arg.arg, arg.len)
}
TYPE_BYTE_STRING -> {
val ret =
data.sliceArray(offset + arg.len.toInt() until offset + arg.len.toInt() + arg.arg.toInt())
return Item(ret, arg.len + arg.arg.toInt())
}
TYPE_TEXT_STRING -> {
val ret =
data.sliceArray(offset + arg.len.toInt() until offset + arg.len.toInt() + arg.arg.toInt())
return Item(ret.toString(Charsets.UTF_8), arg.len + arg.arg.toInt())
}
TYPE_ARRAY -> {
val ret = mutableListOf<Any>()
var consumed = arg.len
for (i in 0 until arg.arg.toInt()) {
val item = parseItem(data, offset + consumed)
ret.add(item.item)
consumed += item.len
}
return Item(ret.toList(), consumed)
}
TYPE_MAP -> {
val ret = mutableMapOf<Any, Any>()
var consumed = arg.len
for (i in 0 until arg.arg.toInt()) {
val key = parseItem(data, offset + consumed)
consumed += key.len
val value = parseItem(data, offset + consumed)
consumed += value.len
ret[key.item] = value.item
}
return Item(ret.toMap(), consumed)
}
else -> {
throw IllegalArgumentException("Bad type")
}
}
}
private fun createArg(type: Int, arg: Long): ByteArray {
val t = type shl 5
val a = arg.toInt()
if (arg < 24) {
return byteArrayOf(((t or a) and 0xFF).toByte())
}
if (arg <= 0xFF) {
return byteArrayOf(((t or 24) and 0xFF).toByte(), (a and 0xFF).toByte())
}
if (arg <= 0xFFFF) {
return byteArrayOf(
((t or 25) and 0xFF).toByte(),
((a shr 8) and 0xFF).toByte(),
(a and 0xFF).toByte()
)
}
if (arg <= 0xFFFFFFFF) {
return byteArrayOf(
((t or 26) and 0xFF).toByte(),
((a shr 24) and 0xFF).toByte(),
((a shr 16) and 0xFF).toByte(),
((a shr 8) and 0xFF).toByte(),
(a and 0xFF).toByte()
)
}
throw IllegalArgumentException("bad Arg")
}
}