com.github.kpavlov.jreactive8583.netty.codec.StringLengthFieldBasedFrameDecoder.kt Maven / Gradle / Ivy

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ISO8583 protocol client and server Netty connectors.

There is a newer version: 1.5.0

@file:JvmName("StringLengthFieldBasedFrameDecoder")

package com.github.kpavlov.jreactive8583.netty.codec

import io.netty.buffer.ByteBuf
import io.netty.handler.codec.LengthFieldBasedFrameDecoder
import io.netty.util.CharsetUtil
import java.nio.ByteOrder

/**
 * Netty's [LengthFieldBasedFrameDecoder] assumes the frame length header is a binary encoded
 * integer. This overrides it's frame length decoding to implement the case when the frame length
 * header is String encoded.
 *
 * Uses [CharsetUtil.US_ASCII] for decoding
 *
 * @param maxFrameLength the maximum length of the frame. If the length of the frame is greater than
 *    this value, `TooLongFrameException` will be thrown.
 * @param lengthFieldOffset the offset of the length field
 * @param lengthFieldLength the length of the length field
 * @param lengthAdjustment the compensation value to add to the value of the length field
 * @param initialBytesToStrip the number of first bytes to strip out from the decoded frame
 * @see LengthFieldBasedFrameDecoder
 */
public open class StringLengthFieldBasedFrameDecoder(
    maxFrameLength: Int,
    lengthFieldOffset: Int,
    lengthFieldLength: Int,
    lengthAdjustment: Int,
    initialBytesToStrip: Int,
) : LengthFieldBasedFrameDecoder(
        maxFrameLength,
        lengthFieldOffset,
        lengthFieldLength,
        lengthAdjustment,
        initialBytesToStrip,
    ) {
    public override fun getUnadjustedFrameLength(
        buf: ByteBuf,
        offset: Int,
        length: Int,
        order: ByteOrder,
    ): Long {
        var b = buf
        b = b.order(order)
        val lengthBytes = ByteArray(length)
        b.getBytes(offset, lengthBytes)
        val s = String(lengthBytes, CharsetUtil.US_ASCII)
        return s.toLong()
    }
}