126 lines
4.2 KiB
Kotlin
126 lines
4.2 KiB
Kotlin
/*
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* Copyright 2017 Christian Basler
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*
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* Licensed under the Apache License, Version 2.0 (the "License");
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* you may not use this file except in compliance with the License.
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* You may obtain a copy of the License at
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*
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* http://www.apache.org/licenses/LICENSE-2.0
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*
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* Unless required by applicable law or agreed to in writing, software
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* distributed under the License is distributed on an "AS IS" BASIS,
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* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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* See the License for the specific language governing permissions and
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* limitations under the License.
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*/
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package ch.dissem.bitmessage.entity
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import ch.dissem.bitmessage.utils.Encode
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import ch.dissem.bitmessage.utils.Singleton.cryptography
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import java.io.IOException
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import java.io.OutputStream
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import java.nio.ByteBuffer
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/**
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* A network message is exchanged between two nodes.
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*/
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data class NetworkMessage(
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/**
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* The actual data, a message or an object. Not to be confused with objectPayload.
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*/
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val payload: MessagePayload
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) : Streamable {
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/**
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* First 4 bytes of sha512(payload)
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*/
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private fun getChecksum(bytes: ByteArray): ByteArray {
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val d = cryptography().sha512(bytes)
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return byteArrayOf(d[0], d[1], d[2], d[3])
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}
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override fun write(out: OutputStream) {
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// magic
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Encode.int32(MAGIC, out)
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// ASCII string identifying the packet content, NULL padded (non-NULL padding results in packet rejected)
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val command = payload.command.name.toLowerCase()
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out.write(command.toByteArray(charset("ASCII")))
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for (i in command.length..11) {
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out.write(0x0)
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}
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val payloadBytes = Encode.bytes(payload)
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// Length of payload in number of bytes. Because of other restrictions, there is no reason why this length would
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// ever be larger than 1600003 bytes. Some clients include a sanity-check to avoid processing messages which are
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// larger than this.
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Encode.int32(payloadBytes.size, out)
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// checksum
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out.write(getChecksum(payloadBytes))
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// message payload
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out.write(payloadBytes)
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}
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/**
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* A more efficient implementation of the write method, writing header data to the provided buffer and returning
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* a new buffer containing the payload.
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* @param headerBuffer where the header data is written to (24 bytes)
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* *
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* @return a buffer containing the payload, ready to be read.
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*/
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fun writeHeaderAndGetPayloadBuffer(headerBuffer: ByteBuffer): ByteBuffer {
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return ByteBuffer.wrap(writeHeader(headerBuffer))
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}
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/**
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* For improved memory efficiency, you should use [.writeHeaderAndGetPayloadBuffer]
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* and write the header buffer as well as the returned payload buffer into the channel.
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* @param buffer where everything gets written to. Needs to be large enough for the whole message
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* * to be written.
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*/
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override fun write(buffer: ByteBuffer) {
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val payloadBytes = writeHeader(buffer)
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buffer.put(payloadBytes)
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}
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private fun writeHeader(out: ByteBuffer): ByteArray {
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// magic
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Encode.int32(MAGIC, out)
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// ASCII string identifying the packet content, NULL padded (non-NULL padding results in packet rejected)
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val command = payload.command.name.toLowerCase()
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out.put(command.toByteArray(charset("ASCII")))
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for (i in command.length..11) {
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out.put(0.toByte())
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}
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val payloadBytes = Encode.bytes(payload)
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// Length of payload in number of bytes. Because of other restrictions, there is no reason why this length would
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// ever be larger than 1600003 bytes. Some clients include a sanity-check to avoid processing messages which are
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// larger than this.
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Encode.int32(payloadBytes.size, out)
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// checksum
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out.put(getChecksum(payloadBytes))
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// message payload
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return payloadBytes
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}
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companion object {
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/**
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* Magic value indicating message origin network, and used to seek to next message when stream state is unknown
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*/
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val MAGIC = 0xE9BEB4D9.toInt()
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val MAGIC_BYTES = ByteBuffer.allocate(4).putInt(MAGIC).array()
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}
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}
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