ble ltk: implement encryption and message parsing
This commit is contained in:
Andrei Vereha
parent
ddfbd2e7bd
commit
ddb1c18349
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@ -0,0 +1,5 @@
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package info.nightscout.androidaps.plugins.pump.omnipod.dash.driver.comm.exceptions
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import info.nightscout.androidaps.utils.extensions.toHex
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class CouldNotParseMessageException(val payload: ByteArray): Exception("Could not parse message payload: ${payload.toHex()}")
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@ -1,3 +1,6 @@
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package info.nightscout.androidaps.plugins.pump.omnipod.dash.driver.comm.exceptions
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class MessageIOException(override val cause: Throwable) : Exception(cause)
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class MessageIOException : Exception {
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constructor(msg: String): super(msg)
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constructor(cause: Throwable): super(cause)
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}
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@ -1,9 +1,6 @@
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package info.nightscout.androidaps.plugins.pump.omnipod.dash.driver.comm.ltk
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import com.google.crypto.tink.mac.AesCmacKeyManager
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import com.google.crypto.tink.proto.AesCmac
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import com.google.crypto.tink.subtle.X25519
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import info.nightscout.androidaps.logging.AAPSLogger
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import info.nightscout.androidaps.logging.LTag
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import info.nightscout.androidaps.plugins.pump.omnipod.dash.driver.comm.Id
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@ -15,6 +12,8 @@ import info.nightscout.androidaps.plugins.pump.omnipod.dash.driver.comm.message.
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import info.nightscout.androidaps.utils.extensions.hexStringToByteArray
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import info.nightscout.androidaps.utils.extensions.toHex
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import org.spongycastle.crypto.engines.AESEngine
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import org.spongycastle.crypto.macs.CMac
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import org.spongycastle.crypto.params.KeyParameter
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import java.security.SecureRandom
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internal class LTKExchanger(private val aapsLogger: AAPSLogger, private val msgIO: MessageIO) {
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@ -30,7 +29,7 @@ internal class LTKExchanger(private val aapsLogger: AAPSLogger, private val msgI
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private val controllerId = Id.fromInt(OmnipodDashBleManagerImpl.CONTROLLER_ID)
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val nodeId = controllerId.increment()
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private var seq: Byte = 1
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private var ltk = ByteArray(0)
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private var ltk = ByteArray(CMAC_SIZE)
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private var noncePrefix = ByteArray(0)
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init {
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@ -98,7 +97,7 @@ internal class LTKExchanger(private val aapsLogger: AAPSLogger, private val msgI
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val publicKey = X25519.publicFromPrivate(pdmPrivate)
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val payload = StringLengthPrefixEncoding.formatKeys(
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arrayOf("SPS1="),
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arrayOf(publicKey + nonce),
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arrayOf(publicKey + pdmNonce),
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)
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return PairMessage(
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sequenceNumber = seq,
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@ -111,10 +110,10 @@ internal class LTKExchanger(private val aapsLogger: AAPSLogger, private val msgI
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private fun processSps1FromPod(msg: MessagePacket) {
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aapsLogger.debug(LTag.PUMPBTCOMM, "Received SPS1 from pod: ${msg.payload.toHex()}")
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if (msg.payload.size != 48) {
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throw MessageIOException()
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throw MessageIOException("Invalid payload size")
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}
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podPublic = msg.payload.copyOfRange(0, PUBLIC_KEY_SIZE)
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podNonce = msg.payload.copyOfRange(PUBLIC_KEY_SIZE, PUBLIC_KEY_SIZE+ NONCE_SIZE)
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podNonce = msg.payload.copyOfRange(PUBLIC_KEY_SIZE, PUBLIC_KEY_SIZE + NONCE_SIZE)
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}
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private fun sps2(): PairMessage {
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@ -144,19 +143,36 @@ internal class LTKExchanger(private val aapsLogger: AAPSLogger, private val msgI
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fun generateKeys() {
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val curveLTK = X25519.computeSharedSecret(pdmPrivate, podPublic)
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aapsLogger.debug(LTag.PUMPBTCOMM, "LTK, donna key: ${curveLTK.toHex()}")
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//first_key = data.pod_public[-4:] + data.pdm_public[-4:] + data.pod_nonce[-4:] + data.pdm_nonce[-4:]
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val firstKey = podPublic.copyOfRange(podPublic.size-4, podPublic.size)
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+ pdmPublic.copyOfRange(pdmPublic.size-4, pdmPublic.size)
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+ podNonce.copyOfRange(podNonce.size-4, podNonce.size)
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+ pdmNonce.copyOfRange(pdmNonce.size-4, pdmNonce.size)
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//first_key = data.pod_public[-4:] + data.pdm_public[-4:] + data.pod_nonce[-4:] + data.pdm_nonce[-4:]
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val firstKey = podPublic.copyOfRange(podPublic.size - 4, podPublic.size) +
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pdmPublic.copyOfRange(pdmPublic.size - 4, pdmPublic.size)+
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podNonce.copyOfRange(podNonce.size - 4, podNonce.size)+
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pdmNonce.copyOfRange(pdmNonce.size - 4, pdmNonce.size)
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aapsLogger.debug(LTag.PUMPBTCOMM, "LTK, first key: ${firstKey.toHex()}")
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val aesEngine = AESEngine()
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val intermediateMac = CMac(aesEngine)
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intermediateMac.init(KeyParameter(firstKey))
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intermediateMac.update(curveLTK, 0, curveLTK.size)
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val intermediateKey = ByteArray(CMAC_SIZE)
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intermediateMac.doFinal(intermediateKey, 0)
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aapsLogger.debug(LTag.PUMPBTCOMM, "Intermediate key: ${intermediateKey.toHex()}")
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val ltkMac = CMac(aesEngine)
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ltkMac.init(KeyParameter(firstKey))
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ltkMac.update(curveLTK, 0, curveLTK.size)
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intermediateMac.doFinal(ltk, 0)
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aapsLogger.debug(LTag.PUMPBTCOMM, "LTK: ${ltk.toHex()}")
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}
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companion object {
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private val PUBLIC_KEY_SIZE = 32
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private val NONCE_SIZE = 16
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private val CONF_SIZE = 16
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private val CMAC_SIZE = 16
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private val GET_POD_STATUS_HEX_COMMAND = "ffc32dbd08030e0100008a" // TODO for now we are assuming this command is build out of constant parameters, use a proper command builder for that.
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}
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}
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@ -36,7 +36,6 @@ class MessageIO(private val aapsLogger: AAPSLogger, private val bleIO: BleIO) {
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bleIO.flushIncomingQueues()
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}
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@kotlin.ExperimentalUnsignedTypes
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fun receiveMessage(): MessagePacket {
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val expectRTS = bleIO.receivePacket(CharacteristicType.CMD)
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if (BleCommand(expectRTS) != BleCommandRTS()) {
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@ -1,6 +1,7 @@
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package info.nightscout.androidaps.plugins.pump.omnipod.dash.driver.comm.message
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import info.nightscout.androidaps.plugins.pump.omnipod.dash.driver.comm.Id
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import info.nightscout.androidaps.plugins.pump.omnipod.dash.driver.comm.exceptions.CouldNotParseMessageException
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import java.nio.ByteBuffer
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/***
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@ -69,9 +70,56 @@ data class MessagePacket(
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companion object {
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private val MAGIC_PATTERN = "TW" // all messages start with this string
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private val HEADER_SIZE = 16
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fun parse(payload: ByteArray): MessagePacket {
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TODO("implement message header parsing")
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if (payload.size < HEADER_SIZE) {
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throw CouldNotParseMessageException(payload)
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}
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if (payload.copyOfRange(0, 2).toString() != "TW") {
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throw info.nightscout.androidaps.plugins.pump.omnipod.dash.driver.comm.exceptions.CouldNotParseMessageException(payload)
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}
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val f1 = Flag(payload[2].toInt())
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val sas = f1.get(3) != 0
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val tfs = f1.get(4) != 0
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val version = ((f1.get(0) shl 2) or (f1.get(1) shl 1) or (f1.get(2) shl 0)).toShort()
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val eqos = (f1.get(7) or (f1.get(6) shl 1) or (f1.get(5) shl 2)).toShort()
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val f2 = Flag(payload[3].toInt())
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val ack = f2.get(0) != 0
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val priority = f2.get(1) != 0
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val lastMessage = f2.get(2) != 0
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val gateway = f2.get(3) != 0
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val type = MessageType.byValue((f1.get(7) or (f1.get(6) shl 1) or (f1.get(5) shl 2) or (f1.get(4) shl 3)).toByte())
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if (version.toInt() != 0) {
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throw CouldNotParseMessageException(payload)
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}
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val sequenceNumber = payload[4]
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val ackNumber = payload[5]
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val size = (payload[6].toInt() shl 3) or (payload[7].toInt() ushr 5)
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if (size + HEADER_SIZE > payload.size) {
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throw CouldNotParseMessageException(payload)
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}
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val payloadEnd = 16 + size +
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if (type == MessageType.ENCRYPTED) 8
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else 0
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return MessagePacket(
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type = type,
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ack = ack,
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eqos = eqos,
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priority = priority,
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lastMessage = lastMessage,
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gateway = gateway,
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sas = sas,
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tfs = tfs,
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version = version,
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sequenceNumber = payload[4],
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ackNumber = payload[5],
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source = Id(payload.copyOfRange(8, 12)),
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destination = Id(payload.copyOfRange(12, 16)),
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payload = payload.copyOfRange(16, payloadEnd),
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)
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}
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}
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}
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@ -85,8 +133,12 @@ private class Flag(var value: Int = 0) {
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value = value or mask
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}
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fun get(idx: Byte): Boolean {
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fun get(idx: Byte): Int {
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val mask = 1 shl (7 - idx)
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return value and mask != 0
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if (value and mask == 0) {
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return 0
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}
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return 1
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}
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}
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@ -11,7 +11,6 @@ import java.lang.Integer.min
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import java.nio.ByteBuffer
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import java.util.*
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@ExperimentalUnsignedTypes
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class PayloadJoiner(private val firstPacket: ByteArray) {
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var oneExtra: Boolean = false
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@ -31,7 +30,7 @@ class PayloadJoiner(private val firstPacket: ByteArray) {
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throw IncorrectPacketException(0, firstPacket)
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fullFragments == 0 -> {
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crc = ByteBuffer.wrap(firstPacket.copyOfRange(2, 6)).int.toUInt().toLong()
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crc = ByteBuffer.wrap(firstPacket.copyOfRange(2, 6)).int.toUnsignedLong()
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val rest = firstPacket[6]
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val end = min(rest + 7, BlePacket.MAX_LEN)
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oneExtra = rest + 7 > end
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@ -72,7 +71,7 @@ class PayloadJoiner(private val firstPacket: ByteArray) {
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if (packet.size < LastBlePacket.HEADER_SIZE) {
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throw IncorrectPacketException(idx.toByte(), packet)
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}
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crc = ByteBuffer.wrap(packet.copyOfRange(2, 6)).int.toUInt().toLong()
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crc = ByteBuffer.wrap(packet.copyOfRange(2, 6)).int.toUnsignedLong()
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val rest = packet[1].toInt()
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val end = min(rest, BlePacket.MAX_LEN)
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if (packet.size < end) {
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@ -106,3 +105,5 @@ class PayloadJoiner(private val firstPacket: ByteArray) {
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}
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}
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private fun Int.toUnsignedLong() = this.toLong() and 0xffffffffL
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