Various bugfix for Wi-Fi direct mode

mobile/src/main/java/be/mygod/vpnhotspot/HotspotService.kt

@@ -63,23 +63,11 @@ class HotspotService : Service(), WifiP2pManager.ChannelListener {
         val service get() = this@HotspotService
         var data: MainActivity.Data? = null
 
-        fun shutdown() {
-            when (status) {
-                Status.ACTIVE_P2P -> p2pManager.removeGroup(channel, object : WifiP2pManager.ActionListener {
-                    override fun onSuccess() = clean()
-                    override fun onFailure(reason: Int) {
-                        if (reason == WifiP2pManager.BUSY) clean() else {   // assuming it's already gone
-                            Toast.makeText(this@HotspotService, "Failed to remove P2P group (${formatReason(reason)})",
-                                    Toast.LENGTH_SHORT).show()
-                            LocalBroadcastManager.getInstance(this@HotspotService)
-                                    .sendBroadcast(Intent(STATUS_CHANGED))
-                        }
-                    }
-                })
+        fun shutdown() = when (status) {
+            Status.ACTIVE_P2P -> removeGroup()
             else -> clean()
         }
     }
-    }
 
     private val wifiManager by lazy { getSystemService(Context.WIFI_SERVICE) as WifiManager }
     private val p2pManager by lazy { getSystemService(Context.WIFI_P2P_SERVICE) as WifiP2pManager }
@@ -199,10 +187,10 @@ class HotspotService : Service(), WifiP2pManager.ChannelListener {
         return START_NOT_STICKY
     }
 
-    private fun startFailure(msg: String) {
+    private fun startFailure(msg: String, group: WifiP2pGroup? = null) {
         Toast.makeText(this@HotspotService, msg, Toast.LENGTH_SHORT).show()
         showNotification()
-        clean()
+        if (group != null) removeGroup() else clean()
     }
     private fun doStart() = p2pManager.createGroup(channel, object : WifiP2pManager.ActionListener {
         override fun onFailure(reason: Int) = startFailure("Failed to create P2P group (${formatReason(reason)})")
@@ -234,15 +222,28 @@ class HotspotService : Service(), WifiP2pManager.ChannelListener {
         val routing = try {
             Routing(upstream, downstream, owner)
         } catch (_: Routing.InterfaceNotFoundException) {
-            startFailure(getString(R.string.exception_interface_not_found))
+            startFailure(getString(R.string.exception_interface_not_found), group)
             return
         }.p2pRule().forward().dnsRedirect(dns)
         if (routing.start()) {
             this.routing = routing
             doStart(group)
-        } else startFailure("Something went wrong, please check logcat.")
+        } else startFailure("Something went wrong, please check logcat.", group)
     }
 
+    private fun removeGroup() {
+        p2pManager.removeGroup(channel, object : WifiP2pManager.ActionListener {
+            override fun onSuccess() = clean()
+            override fun onFailure(reason: Int) {
+                if (reason == WifiP2pManager.BUSY) clean() else {   // assuming it's already gone
+                    Toast.makeText(this@HotspotService, "Failed to remove P2P group (${formatReason(reason)})",
+                            Toast.LENGTH_SHORT).show()
+                    status = Status.ACTIVE_P2P
+                    LocalBroadcastManager.getInstance(this@HotspotService).sendBroadcast(Intent(STATUS_CHANGED))
+                }
+            }
+        })
+    }
     private fun unregisterReceiver() {
         if (receiverRegistered) {
             unregisterReceiver(receiver)

mobile/src/main/java/be/mygod/vpnhotspot/MainActivity.kt

@@ -87,7 +87,7 @@ class MainActivity : AppCompatActivity(), ServiceConnection, Toolbar.OnMenuItemC
             }
             holder.binding.device = device
             holder.binding.ipAddress = when (position) {
-                0 -> binder?.service?.routing?.hostAddress
+                0 -> binder?.service?.routing?.hostAddress?.hostAddress
                 else -> arpCache[device?.deviceAddress]
             }
             holder.binding.executePendingBindings()

mobile/src/main/java/be/mygod/vpnhotspot/Routing.kt

@@ -20,7 +20,7 @@ class Routing(private val upstream: String, val downstream: String, ownerAddress
 
     class InterfaceNotFoundException : IOException()
 
-    val hostAddress: String
+    val hostAddress: InetAddress
     private val subnetPrefixLength: Short
     private val startScript = LinkedList<String>()
     private val stopScript = LinkedList<String>()
@@ -28,19 +28,28 @@ class Routing(private val upstream: String, val downstream: String, ownerAddress
         val address = NetworkInterface.getByName(downstream)?.interfaceAddresses
                 ?.singleOrNull { if (ownerAddress == null) it.address is Inet4Address else it.address == ownerAddress }
                 ?: throw InterfaceNotFoundException()
-        hostAddress = address.address.hostAddress
+        hostAddress = address.address
         subnetPrefixLength = address.networkPrefixLength
     }
 
     fun p2pRule(): Routing {
+        // clear suffix bits
+        val address = hostAddress.address
+        var done = subnetPrefixLength.toInt()
+        while (done < address.size shl 3) {
+            val index = done shr 3
+            address[index] = (address[index].toInt() and (0x7f00 shr (done and 7))).toByte()
+            done = (index + 1) shl 3
+        }
+        val hostAddress = InetAddress.getByAddress(address).hostAddress
         startScript.add("echo 1 >/proc/sys/net/ipv4/ip_forward")    // Wi-Fi direct doesn't enable ip_forward
         startScript.add("ip route add default dev $upstream scope link table 62")
         startScript.add("ip route add $hostAddress/$subnetPrefixLength dev $downstream scope link table 62")
         startScript.add("ip route add broadcast 255.255.255.255 dev $downstream scope link table 62")
         startScript.add("ip rule add iif $downstream lookup 62")
         stopScript.addFirst("ip route del default dev $upstream scope link table 62")
-        stopScript.addFirst("ip route del $hostAddress/$subnetPrefixLength dev $downstream scope link table 62")
-        stopScript.addFirst("ip route del broadcast 255.255.255.255 dev $downstream scope link table 62")
+        // removing each rule may fail if downstream is already removed
+        stopScript.addFirst("ip route flush table 62")
         stopScript.addFirst("ip rule del iif $downstream lookup 62")
         return this
     }
@@ -65,6 +74,7 @@ class Routing(private val upstream: String, val downstream: String, ownerAddress
     }
 
     fun dnsRedirect(dns: String): Routing {
+        val hostAddress = hostAddress.hostAddress
         startScript.add("iptables -t nat -A PREROUTING -i $downstream -p tcp -d $hostAddress --dport 53 -j DNAT --to-destination $dns")
         startScript.add("iptables -t nat -A PREROUTING -i $downstream -p udp -d $hostAddress --dport 53 -j DNAT --to-destination $dns")
         stopScript.addFirst("iptables -t nat -D PREROUTING -i $downstream -p tcp -d $hostAddress --dport 53 -j DNAT --to-destination $dns")

mobile/src/main/java/be/mygod/vpnhotspot/Utils.kt

@@ -23,8 +23,8 @@ fun Bundle.put(key: String, map: Array<String>): Bundle {
     return this
 }
 
-const val NOISYSU_TAG = "NoisySU"
-const val NOISYSU_SUFFIX = "SUCCESS\n"
+private const val NOISYSU_TAG = "NoisySU"
+private const val NOISYSU_SUFFIX = "SUCCESS\n"
 fun loggerSuStream(command: String): InputStream {
     val process = ProcessBuilder("su", "-c", command)
             .redirectErrorStream(true)