jvmMain.io.ktor.util.EncodersJvm.kt Maven / Gradle / Ivy
/*
* Copyright 2014-2019 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.util.cio.*
import io.ktor.utils.io.*
import io.ktor.utils.io.core.*
import kotlinx.coroutines.*
import java.nio.*
import java.util.zip.*
private const val GZIP_HEADER_SIZE: Int = 10
// GZIP header flags bits
private object GzipHeaderFlags {
// Is ASCII
const val FTEXT = 1 shl 0
// Has header CRC16
const val FHCRC = 1 shl 1
// Extra fields present
const val EXTRA = 1 shl 2
// File name present
const val FNAME = 1 shl 3
// File comment present
const val FCOMMENT = 1 shl 4
}
private infix fun Int.has(flag: Int) = this and flag != 0
/**
* Implementation of Deflate [Encoder].
*/
public val Deflate: Encoder = object : Encoder {
override fun CoroutineScope.encode(source: ByteReadChannel): ByteReadChannel =
source.deflated(gzip = true, coroutineContext = coroutineContext)
override fun CoroutineScope.decode(source: ByteReadChannel): ByteReadChannel =
inflate(source, gzip = false)
}
/**
* Implementation of GZip [Encoder].
*/
public val GZip: Encoder = object : Encoder {
override fun CoroutineScope.encode(source: ByteReadChannel): ByteReadChannel =
source.deflated(gzip = true, coroutineContext = coroutineContext)
override fun CoroutineScope.decode(source: ByteReadChannel): ByteReadChannel = inflate(source)
}
private fun CoroutineScope.inflate(
source: ByteReadChannel,
gzip: Boolean = true
): ByteReadChannel = writer {
val readBuffer = KtorDefaultPool.borrow()
val writeBuffer = KtorDefaultPool.borrow()
val inflater = Inflater(true)
val checksum = CRC32()
if (gzip) {
val header = source.readPacket(GZIP_HEADER_SIZE)
val magic = header.readShortLittleEndian()
val format = header.readByte()
val flags = header.readByte().toInt()
// Next parts of the header are not used for now,
// uncomment the following lines once you need them
// val time = header.readInt()
// val extraFlags = header.readByte()
// val osType = header.readByte()
// however we have to discard them to prevent a memory leak
header.discard()
// skip the extra header if present
if (flags and GzipHeaderFlags.EXTRA != 0) {
val extraLen = source.readShort().toLong()
source.discardExact(extraLen)
}
check(magic == GZIP_MAGIC) { "GZIP magic invalid: $magic" }
check(format.toInt() == Deflater.DEFLATED) { "Deflater method unsupported: $format." }
check(!(flags has GzipHeaderFlags.FNAME)) { "Gzip file name not supported" }
check(!(flags has GzipHeaderFlags.FCOMMENT)) { "Gzip file comment not supported" }
// skip the header CRC if present
if (flags has GzipHeaderFlags.FHCRC) {
source.discardExact(2)
}
}
try {
var totalSize = 0
while (!source.isClosedForRead) {
if (source.readAvailable(readBuffer) <= 0) continue
readBuffer.flip()
inflater.setInput(readBuffer.array(), readBuffer.position(), readBuffer.remaining())
while (!inflater.needsInput() && !inflater.finished()) {
totalSize += inflater.inflateTo(channel, writeBuffer, checksum)
readBuffer.position(readBuffer.limit() - inflater.remaining)
}
readBuffer.compact()
}
source.closedCause?.let { throw it }
readBuffer.flip()
while (!inflater.finished()) {
totalSize += inflater.inflateTo(channel, writeBuffer, checksum)
readBuffer.position(readBuffer.limit() - inflater.remaining)
}
if (gzip) {
check(readBuffer.remaining() == 8) {
"Expected 8 bytes in the trailer. Actual: ${readBuffer.remaining()} $"
}
readBuffer.order(java.nio.ByteOrder.LITTLE_ENDIAN)
val expectedChecksum = readBuffer.getInt(readBuffer.position())
val expectedSize = readBuffer.getInt(readBuffer.position() + 4)
check(checksum.value.toInt() == expectedChecksum) { "Gzip checksum invalid." }
check(totalSize == expectedSize) { "Gzip size invalid. Expected $expectedSize, actual $totalSize" }
} else {
check(!readBuffer.hasRemaining())
}
} catch (cause: Throwable) {
throw cause
} finally {
inflater.end()
KtorDefaultPool.recycle(readBuffer)
KtorDefaultPool.recycle(writeBuffer)
}
}.channel
private suspend fun Inflater.inflateTo(channel: ByteWriteChannel, buffer: ByteBuffer, checksum: Checksum): Int {
buffer.clear()
val inflated = inflate(buffer.array(), buffer.position(), buffer.remaining())
buffer.position(buffer.position() + inflated)
buffer.flip()
checksum.updateKeepPosition(buffer)
channel.writeFully(buffer)
return inflated
}