jvmMain.okio.CipherSource.kt Maven / Gradle / Ivy
/*
* Copyright (C) 2020 Square, Inc. and others.
*
* 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 okio
import java.io.IOException
import javax.crypto.Cipher
class CipherSource(
private val source: BufferedSource,
val cipher: Cipher,
) : Source {
private val blockSize = cipher.blockSize
private val buffer = Buffer()
private var final = false
private var closed = false
init {
// Require block cipher
require(blockSize > 0) { "Block cipher required $cipher" }
}
@Throws(IOException::class)
override fun read(sink: Buffer, byteCount: Long): Long {
require(byteCount >= 0L) { "byteCount < 0: $byteCount" }
check(!closed) { "closed" }
if (byteCount == 0L) return 0L
refill()
return buffer.read(sink, byteCount)
}
private fun refill() {
while (buffer.size == 0L && !final) {
if (source.exhausted()) {
final = true
doFinal()
break
} else {
update()
}
}
}
private fun update() {
val head = source.buffer.head!!
var size = head.limit - head.pos
// Shorten input until output is guaranteed to fit within a segment
var outputSize = cipher.getOutputSize(size)
while (outputSize > Segment.SIZE) {
if (size <= blockSize) {
// Bug: For AES-GCM on Android `update` method never outputs any data
// As a consequence, `getOutputSize` just keeps increasing indefinitely after each update
// When that happens, the fallback is to break the streaming implementation and just cipher the rest of the data all at once
final = true
buffer.write(cipher.doFinal(source.readByteArray()))
return
}
size -= blockSize
outputSize = cipher.getOutputSize(size)
}
val s = buffer.writableSegment(outputSize)
val ciphered =
cipher.update(head.data, head.pos, size, s.data, s.pos)
source.skip(size.toLong())
s.limit += ciphered
buffer.size += ciphered
// We allocated a tail segment, but didn't end up needing it. Recycle!
if (s.pos == s.limit) {
buffer.head = s.pop()
SegmentPool.recycle(s)
}
}
private fun doFinal() {
val outputSize = cipher.getOutputSize(0)
if (outputSize == 0) return
// For block cipher, output size cannot exceed block size in doFinal.
val s = buffer.writableSegment(outputSize)
val ciphered = cipher.doFinal(s.data, s.pos)
s.limit += ciphered
buffer.size += ciphered
// We allocated a tail segment, but didn't end up needing it. Recycle!
if (s.pos == s.limit) {
buffer.head = s.pop()
SegmentPool.recycle(s)
}
}
override fun timeout() = source.timeout()
@Throws(IOException::class)
override fun close() {
closed = true
source.close()
}
}