78 lines
3.3 KiB
Kotlin
78 lines
3.3 KiB
Kotlin
package be.mygod.vpnhotspot.net
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import android.util.Log
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import java.io.File
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import java.io.IOException
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data class IpNeighbour(val ip: String, val dev: String, val lladdr: String, val state: State) {
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enum class State {
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INCOMPLETE, VALID, FAILED, DELETING
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}
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companion object {
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private const val TAG = "IpNeighbour"
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/**
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* Parser based on:
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* https://android.googlesource.com/platform/external/iproute2/+/ad0a6a2/ip/ipneigh.c#194
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* https://people.cs.clemson.edu/~westall/853/notes/arpstate.pdf
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* Assumptions: IP addr (key) always present, RTM_GETNEIGH is never used and show_stats = 0
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*/
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private val parser = ("^(Deleted )?(.+?) (dev (.+?) )?(lladdr (.+?))?( router)?( proxy)?" +
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"( ([INCOMPLET,RAHBSDYF]+))?\$").toRegex()
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private fun checkLladdrNotLoopback(lladdr: String) = if (lladdr == "00:00:00:00:00:00") "" else lladdr
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fun parse(line: String): IpNeighbour? {
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val match = parser.matchEntire(line)
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if (match == null) {
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if (line.isNotEmpty()) Log.w(TAG, line)
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return null
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}
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val ip = match.groupValues[2]
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val dev = match.groupValues[4]
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var lladdr = checkLladdrNotLoopback(match.groupValues[6])
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// use ARP as fallback
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if (dev.isNotEmpty() && lladdr.isEmpty()) lladdr = checkLladdrNotLoopback(arp()
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.filter { it[ARP_IP_ADDRESS] == ip && it[ARP_DEVICE] == dev }
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.map { it[ARP_HW_ADDRESS] }
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.singleOrNull() ?: "")
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val state = if (match.groupValues[1].isNotEmpty() || lladdr.isEmpty()) State.DELETING else
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when (match.groupValues[10]) {
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"", "INCOMPLETE" -> State.INCOMPLETE
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"REACHABLE", "DELAY", "STALE", "PROBE", "PERMANENT" -> State.VALID
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"FAILED" -> State.FAILED
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"NOARP" -> return null // skip
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else -> {
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Log.w(TAG, "Unknown state encountered: ${match.groupValues[10]}")
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return null
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}
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}
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return IpNeighbour(ip, dev, lladdr, state)
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}
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private val spaces = " +".toPattern()
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private val mac = "^([0-9a-f]{2}:){5}[0-9a-f]{2}$".toPattern()
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// IP address HW type Flags HW address Mask Device
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private const val ARP_IP_ADDRESS = 0
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private const val ARP_HW_ADDRESS = 3
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private const val ARP_DEVICE = 5
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private const val ARP_CACHE_EXPIRE = 1L * 1000 * 1000 * 1000
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private var arpCache = emptyList<List<String>>()
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private var arpCacheTime = -ARP_CACHE_EXPIRE
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private fun arp(): List<List<String>> {
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if (System.nanoTime() - arpCacheTime >= ARP_CACHE_EXPIRE) try {
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arpCache = File("/proc/net/arp").bufferedReader().useLines {
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it.map { it.split(spaces) }
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.drop(1)
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.filter { it.size >= 6 && mac.matcher(it[ARP_HW_ADDRESS]).matches() }
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.toList()
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}
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} catch (e: IOException) {
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e.printStackTrace()
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}
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return arpCache
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}
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}
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}
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