AndroidAPS/app/src/main/java/info/nightscout/androidaps/utils/SntpClient.kt
2021-02-25 17:43:20 +01:00

214 lines
8 KiB
Kotlin

package info.nightscout.androidaps.utils
import android.os.SystemClock
import javax.inject.Singleton
import javax.inject.Inject
import info.nightscout.androidaps.logging.AAPSLogger
import java.lang.Exception
import java.net.DatagramPacket
import java.net.DatagramSocket
import java.net.InetAddress
/*
* Copyright (C) 2008 The Android Open Source Project
*
* 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.
*/ /**
* {@hide}
*
*
* Simple SNTP client class for retrieving network time.
*
*
* Sample usage:
* <pre>SntpClient client = new SntpClient();
* if (client.requestTime("time.foo.com")) {
* long now = client.getNtpTime() + SystemClock.elapsedRealtime() - client.getNtpTimeReference();
* }
</pre> *
*/
@Singleton
class SntpClient @Inject constructor(
private val aapsLogger: AAPSLogger,
private val dateUtil: DateUtil
) {
companion object {
//private final int REFERENCE_TIME_OFFSET = 16;
private const val ORIGINATE_TIME_OFFSET = 24
private const val RECEIVE_TIME_OFFSET = 32
private const val TRANSMIT_TIME_OFFSET = 40
private const val NTP_PACKET_SIZE = 48
private const val NTP_PORT = 123
private const val NTP_MODE_CLIENT = 3
private const val NTP_VERSION = 3
// Number of seconds between Jan 1, 1900 and Jan 1, 1970
// 70 years plus 17 leap days
private const val OFFSET_1900_TO_1970 = (365L * 70L + 17L) * 24L * 60L * 60L
}
/**
* Returns the time computed from the NTP transaction.
*
* @return time value computed from NTP server response.
*/
// system time computed from NTP server response
private var ntpTime: Long = 0
/**
* Returns the reference clock value (value of SystemClock.elapsedRealtime())
* corresponding to the NTP time.
*
* @return reference clock corresponding to the NTP time.
*/
// value of SystemClock.elapsedRealtime() corresponding to mNtpTime
private var ntpTimeReference: Long = 0
/**
* Returns the round trip time of the NTP transaction
*
* @return round trip time in milliseconds.
*/
// round trip time in milliseconds
private var roundTripTime: Long = 0
abstract class Callback : Runnable {
var networkConnected = false
var success = false
var time: Long = 0
}
@Synchronized fun ntpTime(callback: Callback, isConnected: Boolean) {
callback.networkConnected = isConnected
if (callback.networkConnected) {
Thread { doNtpTime(callback) }.start()
} else {
callback.run()
}
}
fun doNtpTime(callback: Callback) {
aapsLogger.debug("Time detection started")
callback.success = requestTime("time.google.com", 5000)
callback.time = ntpTime + SystemClock.elapsedRealtime() - ntpTimeReference
aapsLogger.debug("Time detection ended: " + callback.success + " " + dateUtil.dateAndTimeString(ntpTime))
callback.run()
}
/**
* Sends an SNTP request to the given host and processes the response.
*
* @param host host name of the server.
* @param timeout network timeout in milliseconds.
* @return true if the transaction was successful.
*/
@Suppress("SameParameterValue")
@Synchronized private fun requestTime(host: String, timeout: Int): Boolean {
try {
val socket = DatagramSocket()
socket.soTimeout = timeout
val address = InetAddress.getByName(host)
val buffer = ByteArray(NTP_PACKET_SIZE)
val request = DatagramPacket(buffer, buffer.size, address, NTP_PORT)
// set mode = 3 (client) and version = 3
// mode is in low 3 bits of first byte
// version is in bits 3-5 of first byte
buffer[0] = (NTP_MODE_CLIENT or (NTP_VERSION shl 3)).toByte()
// get current time and write it to the request packet
val requestTime = System.currentTimeMillis()
val requestTicks = SystemClock.elapsedRealtime()
writeTimeStamp(buffer, TRANSMIT_TIME_OFFSET, requestTime)
socket.send(request)
// read the response
val response = DatagramPacket(buffer, buffer.size)
socket.receive(response)
val responseTicks = SystemClock.elapsedRealtime()
val responseTime = requestTime + (responseTicks - requestTicks)
socket.close()
// extract the results
val originateTime = readTimeStamp(buffer, ORIGINATE_TIME_OFFSET)
val receiveTime = readTimeStamp(buffer, RECEIVE_TIME_OFFSET)
val transmitTime = readTimeStamp(buffer, TRANSMIT_TIME_OFFSET)
val roundTripTime = responseTicks - requestTicks - (transmitTime - receiveTime)
val clockOffset = (receiveTime - originateTime + (transmitTime - responseTime)) / 2
// save our results - use the times on this side of the network latency
// (response rather than request time)
ntpTime = responseTime + clockOffset
ntpTimeReference = responseTicks
this.roundTripTime = roundTripTime
} catch (e: Exception) {
aapsLogger.debug("request time failed: $e")
return false
}
return true
}
/**
* Reads an unsigned 32 bit big endian number from the given offset in the buffer.
*/
private fun read32(buffer: ByteArray, offset: Int): Long {
val b0 = buffer[offset]
val b1 = buffer[offset + 1]
val b2 = buffer[offset + 2]
val b3 = buffer[offset + 3]
// convert signed bytes to unsigned values
val i0 = if (b0.toInt() and 0x80 == 0x80) (b0.toInt() and 0x7F) + 0x80 else b0.toInt()
val i1 = if (b1.toInt() and 0x80 == 0x80) (b1.toInt() and 0x7F) + 0x80 else b1.toInt()
val i2 = if (b2.toInt() and 0x80 == 0x80) (b2.toInt() and 0x7F) + 0x80 else b2.toInt()
val i3 = if (b3.toInt() and 0x80 == 0x80) (b3.toInt() and 0x7F) + 0x80 else b3.toInt()
return (i0.toLong() shl 24) + (i1.toLong() shl 16) + (i2.toLong() shl 8) + i3.toLong()
}
/**
* Reads the NTP time stamp at the given offset in the buffer and returns
* it as a system time (milliseconds since January 1, 1970).
*/
private fun readTimeStamp(buffer: ByteArray, offset: Int): Long {
val seconds = read32(buffer, offset)
val fraction = read32(buffer, offset + 4)
return (seconds - OFFSET_1900_TO_1970) * 1000 + fraction * 1000L / 0x100000000L
}
/**
* Writes system time (milliseconds since January 1, 1970) as an NTP time stamp
* at the given offset in the buffer.
*/
@Suppress("SameParameterValue")
private fun writeTimeStamp(buffer: ByteArray, offsetParam: Int, time: Long) {
var offset = offsetParam
var seconds = time / 1000L
val milliseconds = time - seconds * 1000L
seconds += OFFSET_1900_TO_1970
// write seconds in big endian format
buffer[offset++] = (seconds shr 24).toByte()
buffer[offset++] = (seconds shr 16).toByte()
buffer[offset++] = (seconds shr 8).toByte()
buffer[offset++] = (seconds shr 0).toByte()
val fraction = milliseconds * 0x100000000L / 1000L
// write fraction in big endian format
buffer[offset++] = (fraction shr 24).toByte()
buffer[offset++] = (fraction shr 16).toByte()
buffer[offset++] = (fraction shr 8).toByte()
// low order bits should be random data
buffer[offset] = (Math.random() * 255.0).toInt().toByte()
}
}