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/*
* 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 CipherSink(
private val sink: BufferedSink,
val cipher: Cipher,
) : Sink {
private val blockSize = cipher.blockSize
private var closed = false
init {
// Require block cipher
require(blockSize > 0) { "Block cipher required $cipher" }
}
@Throws(IOException::class)
override fun write(source: Buffer, byteCount: Long) {
checkOffsetAndCount(source.size, 0, byteCount)
check(!closed) { "closed" }
var remaining = byteCount
while (remaining > 0) {
val size = update(source, remaining)
remaining -= size
}
}
private fun update(source: Buffer, remaining: Long): Int {
val head = source.head!!
var size = minOf(remaining, head.limit - head.pos).toInt()
val buffer = sink.buffer
// 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 perform the update operation without using a pre-allocated segment
sink.write(cipher.update(source.readByteArray(remaining)))
return remaining.toInt()
}
size -= blockSize
outputSize = cipher.getOutputSize(size)
}
val s = buffer.writableSegment(outputSize)
val ciphered = cipher.update(head.data, head.pos, size, s.data, s.limit)
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)
}
sink.emitCompleteSegments()
// Mark those bytes as read.
source.size -= size
head.pos += size
if (head.pos == head.limit) {
source.head = head.pop()
SegmentPool.recycle(head)
}
return size
}
override fun flush() = sink.flush()
override fun timeout() = sink.timeout()
@Throws(IOException::class)
override fun close() {
if (closed) return
closed = true
var thrown = doFinal()
try {
sink.close()
} catch (e: Throwable) {
if (thrown == null) thrown = e
}
if (thrown != null) throw thrown
}
private fun doFinal(): Throwable? {
val outputSize = cipher.getOutputSize(0)
if (outputSize == 0) return null
if (outputSize > Segment.SIZE) {
// Bug: For AES-GCM on Android `update` method never outputs any data
// As a consequence, `doFinal` returns the fully encrypted data, which may be arbitrarily large
// When that happens, the fallback is to perform the `doFinal` operation without using a pre-allocated segment
try {
sink.write(cipher.doFinal())
} catch (t: Throwable) {
return t
}
return null
}
var thrown: Throwable? = null
val buffer = sink.buffer
// For block cipher, output size cannot exceed block size in doFinal
val s = buffer.writableSegment(outputSize)
try {
val ciphered = cipher.doFinal(s.data, s.limit)
s.limit += ciphered
buffer.size += ciphered
} catch (e: Throwable) {
thrown = e
}
if (s.pos == s.limit) {
buffer.head = s.pop()
SegmentPool.recycle(s)
}
return thrown
}
}
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