Support editing native Wi-Fi AP configurations

Support for repeater channel on Android 5 has been dropped because I am lazy.
2019-04-04 16:43:48 +08:00
parent 834498b1ff
commit 1145b0f23b
21 changed files with 488 additions and 295 deletions
--- a/mobile/src/main/java/be/mygod/vpnhotspot/RepeaterService.kt
+++ b/mobile/src/main/java/be/mygod/vpnhotspot/RepeaterService.kt
@@ -52,10 +52,12 @@ class RepeaterService : Service(), WifiP2pManager.ChannelListener, SharedPrefere
        val supported get() = p2pManager != null
        var persistentSupported = false

-        val operatingChannel: Int get() {
-            val result = app.pref.getString(KEY_OPERATING_CHANNEL, null)?.toIntOrNull() ?: 0
-            return if (result in 1..165) result else 0
-        }
+        var operatingChannel: Int
+            get() {
+                val result = app.pref.getString(KEY_OPERATING_CHANNEL, null)?.toIntOrNull() ?: 0
+                return if (result in 1..165) result else 0
+            }
+            set(value) = app.pref.edit().putString(RepeaterService.KEY_OPERATING_CHANNEL, value.toString()).apply()
    }

    enum class Status {
--- a/mobile/src/main/java/be/mygod/vpnhotspot/manage/LocalOnlyHotspotManager.kt
+++ b/mobile/src/main/java/be/mygod/vpnhotspot/manage/LocalOnlyHotspotManager.kt
@@ -7,14 +7,10 @@ import android.content.ComponentName
 import android.content.Intent
 import android.content.ServiceConnection
 import android.content.pm.PackageManager
-import android.graphics.Typeface
 import android.location.LocationManager
 import android.os.Build
 import android.os.IBinder
 import android.provider.Settings
-import android.text.SpannableStringBuilder
-import android.text.Spanned
-import android.text.style.TypefaceSpan
 import android.view.View
 import android.widget.Toast
 import androidx.core.content.getSystemService
@@ -24,7 +20,6 @@ import be.mygod.vpnhotspot.DebugHelper
 import be.mygod.vpnhotspot.LocalOnlyHotspotService
 import be.mygod.vpnhotspot.R
 import be.mygod.vpnhotspot.databinding.ListitemInterfaceBinding
-import be.mygod.vpnhotspot.net.TetherType
 import be.mygod.vpnhotspot.util.ServiceForegroundConnector
 import be.mygod.vpnhotspot.util.formatAddresses
 import be.mygod.vpnhotspot.widget.SmartSnackbar
@@ -76,15 +71,7 @@ class LocalOnlyHotspotManager(private val parent: TetheringFragment) : Manager()
        private val lookup: Map<String, NetworkInterface> get() = parent.ifaceLookup

        override val icon get() = R.drawable.ic_action_perm_scan_wifi
-        override val title: CharSequence get() {
-            val configuration = binder?.configuration ?: return parent.getString(R.string.tethering_temp_hotspot)
-            return SpannableStringBuilder("${configuration.SSID} - ").apply {
-                val start = length
-                append(configuration.preSharedKey)
-                setSpan(if (Build.VERSION.SDK_INT >= 28) TypefaceSpan(Typeface.MONOSPACE) else
-                    TypefaceSpan("monospace"), start, length, Spanned.SPAN_EXCLUSIVE_EXCLUSIVE)
-            }
-        }
+        override val title: CharSequence get() = parent.getString(R.string.tethering_temp_hotspot)
        override val text: CharSequence get() {
            return lookup[binder?.iface ?: return ""]?.formatAddresses() ?: ""
        }
@@ -99,7 +86,7 @@ class LocalOnlyHotspotManager(private val parent: TetheringFragment) : Manager()

    override val type get() = VIEW_TYPE_LOCAL_ONLY_HOTSPOT
    private val data = Data()
-    private var binder: LocalOnlyHotspotService.Binder? = null
+    internal var binder: LocalOnlyHotspotService.Binder? = null

    override fun bindTo(viewHolder: RecyclerView.ViewHolder) {
        viewHolder as ViewHolder
--- a/mobile/src/main/java/be/mygod/vpnhotspot/manage/RepeaterManager.kt
+++ b/mobile/src/main/java/be/mygod/vpnhotspot/manage/RepeaterManager.kt
@@ -6,6 +6,7 @@ import android.content.Intent
 import android.content.ServiceConnection
 import android.net.wifi.WifiConfiguration
 import android.net.wifi.p2p.WifiP2pGroup
+import android.os.Build
 import android.os.Bundle
 import android.os.IBinder
 import android.os.Parcelable
@@ -21,10 +22,8 @@ import androidx.lifecycle.ViewModelProviders
 import androidx.lifecycle.get
 import androidx.recyclerview.widget.RecyclerView
 import be.mygod.vpnhotspot.*
-import be.mygod.vpnhotspot.App.Companion.app
 import be.mygod.vpnhotspot.databinding.ListitemRepeaterBinding
-import be.mygod.vpnhotspot.net.wifi.P2pSupplicantConfiguration
-import be.mygod.vpnhotspot.net.wifi.WifiP2pDialogFragment
+import be.mygod.vpnhotspot.net.wifi.configuration.*
 import be.mygod.vpnhotspot.util.ServiceForegroundConnector
 import be.mygod.vpnhotspot.util.formatAddresses
 import be.mygod.vpnhotspot.widget.SmartSnackbar
@@ -51,7 +50,6 @@ class RepeaterManager(private val parent: TetheringFragment) : Manager(), Servic
                else -> false
            }

-        val ssid @Bindable get() = binder?.group?.networkName ?: ""
        val addresses: CharSequence @Bindable get() {
            return try {
                NetworkInterface.getByName(p2pInterface ?: return "")?.formatAddresses() ?: ""
@@ -59,12 +57,6 @@ class RepeaterManager(private val parent: TetheringFragment) : Manager(), Servic
                ""
            }
        }
-        var oc: CharSequence
-            @Bindable get() {
-                val oc = RepeaterService.operatingChannel
-                return if (oc in 1..165) oc.toString() else ""
-            }
-            set(value) = app.pref.edit().putString(RepeaterService.KEY_OPERATING_CHANNEL, value.toString()).apply()

        fun onStatusChanged() {
            notifyPropertyChanged(BR.switchEnabled)
@@ -72,7 +64,6 @@ class RepeaterManager(private val parent: TetheringFragment) : Manager(), Servic
            notifyPropertyChanged(BR.addresses)
        }
        fun onGroupChanged(group: WifiP2pGroup? = null) {
-            notifyPropertyChanged(BR.ssid)
            p2pInterface = group?.`interface`
            notifyPropertyChanged(BR.addresses)
        }
@@ -92,22 +83,6 @@ class RepeaterManager(private val parent: TetheringFragment) : Manager(), Servic
        fun wps() {
            if (binder?.active == true) WpsDialogFragment().show(parent, TetheringFragment.REPEATER_WPS)
        }
-
-        fun editConfigurations() {
-            val group = binder?.group
-            if (group != null) try {
-                val config = P2pSupplicantConfiguration(group, binder?.thisDevice?.deviceAddress)
-                holder.config = config
-                WifiP2pDialogFragment().withArg(WifiP2pDialogFragment.Arg(WifiConfiguration().apply {
-                    SSID = group.networkName
-                    preSharedKey = config.psk
-                })).show(parent, TetheringFragment.REPEATER_EDIT_CONFIGURATION)
-                return
-            } catch (e: RuntimeException) {
-                Timber.w(e)
-            }
-            SmartSnackbar.make(R.string.repeater_configure_failure).show()
-        }
    }

    @Parcelize
@@ -168,16 +143,35 @@ class RepeaterManager(private val parent: TetheringFragment) : Manager(), Servic
        }
    }

-    fun onEditResult(data: Intent?) {
-        val master = holder.config ?: return
-        try {
-            val config = AlertDialogFragment.getRet<WifiP2pDialogFragment.Arg>(data!!).configuration
-            master.update(config.SSID, config.preSharedKey)
-            binder!!.group = null
-        } catch (e: Exception) {
+    val configuration: WifiConfiguration? get() {
+        val group = binder?.group
+        if (group != null) try {
+            val config = P2pSupplicantConfiguration(group, binder?.thisDevice?.deviceAddress)
+            holder.config = config
+            return newWifiApConfiguration(group.networkName, config.psk).apply {
+                allowedKeyManagement.set(WifiConfiguration.KeyMgmt.WPA_PSK) // is not actually used
+                if (Build.VERSION.SDK_INT >= 23) {
+                    apBand = AP_BAND_ANY
+                    apChannel = RepeaterService.operatingChannel
+                }
+            }
+        } catch (e: RuntimeException) {
            Timber.w(e)
-            SmartSnackbar.make(e).show()
        }
-        holder.config = null
+        SmartSnackbar.make(R.string.repeater_configure_failure).show()
+        return null
+    }
+    fun updateConfiguration(config: WifiConfiguration) {
+        holder.config?.let { master ->
+            if (binder?.group?.networkName != config.SSID || master.psk != config.preSharedKey) try {
+                master.update(config.SSID, config.preSharedKey)
+                binder!!.group = null
+            } catch (e: Exception) {
+                Timber.w(e)
+                SmartSnackbar.make(e).show()
+            }
+            holder.config = null
+        }
+        RepeaterService.operatingChannel = config.apChannel
    }
 }
--- a/mobile/src/main/java/be/mygod/vpnhotspot/manage/TetheringFragment.kt
+++ b/mobile/src/main/java/be/mygod/vpnhotspot/manage/TetheringFragment.kt
@@ -1,15 +1,16 @@
 package be.mygod.vpnhotspot.manage

 import android.annotation.TargetApi
-import android.content.ComponentName
-import android.content.Intent
-import android.content.IntentFilter
-import android.content.ServiceConnection
+import android.content.*
 import android.content.pm.PackageManager
 import android.os.Build
 import android.os.Bundle
 import android.os.IBinder
-import android.view.*
+import android.view.LayoutInflater
+import android.view.MenuItem
+import android.view.View
+import android.view.ViewGroup
+import androidx.appcompat.widget.Toolbar
 import androidx.core.content.ContextCompat
 import androidx.databinding.DataBindingUtil
 import androidx.fragment.app.Fragment
@@ -23,24 +24,30 @@ import be.mygod.vpnhotspot.net.TetherType
 import be.mygod.vpnhotspot.net.TetheringManager
 import be.mygod.vpnhotspot.net.TetheringManager.localOnlyTetheredIfaces
 import be.mygod.vpnhotspot.net.TetheringManager.tetheredIfaces
+import be.mygod.vpnhotspot.net.wifi.WifiApManager
+import be.mygod.vpnhotspot.net.wifi.configuration.WifiApDialogFragment
 import be.mygod.vpnhotspot.util.ServiceForegroundConnector
 import be.mygod.vpnhotspot.util.broadcastReceiver
 import be.mygod.vpnhotspot.util.isNotGone
+import be.mygod.vpnhotspot.widget.SmartSnackbar
 import kotlinx.android.synthetic.main.activity_main.*
 import timber.log.Timber
+import java.lang.IllegalArgumentException
+import java.lang.reflect.InvocationTargetException
 import java.net.NetworkInterface
 import java.net.SocketException

-class TetheringFragment : Fragment(), ServiceConnection, MenuItem.OnMenuItemClickListener {
+class TetheringFragment : Fragment(), ServiceConnection, Toolbar.OnMenuItemClickListener {
    companion object {
        const val START_LOCAL_ONLY_HOTSPOT = 1
-        const val REPEATER_EDIT_CONFIGURATION = 2
        const val REPEATER_WPS = 3
+        const val CONFIGURE_REPEATER = 2
+        const val CONFIGURE_AP = 4
    }

    inner class ManagerAdapter : ListAdapter<Manager, RecyclerView.ViewHolder>(Manager) {
        internal val repeaterManager by lazy { RepeaterManager(this@TetheringFragment) }
-        private val localOnlyHotspotManager by lazy @TargetApi(26) { LocalOnlyHotspotManager(this@TetheringFragment) }
+        internal val localOnlyHotspotManager by lazy @TargetApi(26) { LocalOnlyHotspotManager(this@TetheringFragment) }
        private val tetherManagers by lazy @TargetApi(24) {
            listOf(TetherManager.Wifi(this@TetheringFragment),
                    TetherManager.Usb(this@TetheringFragment),
@@ -100,13 +107,47 @@ class TetheringFragment : Fragment(), ServiceConnection, MenuItem.OnMenuItemClic
        item.isNotGone = canMonitor.isNotEmpty()
        item.subMenu.apply {
            clear()
-            canMonitor.sorted().forEach { add(it).setOnMenuItemClickListener(this@TetheringFragment) }
+            for (iface in canMonitor.sorted()) add(iface).setOnMenuItemClickListener {
+                ContextCompat.startForegroundService(requireContext(), Intent(context, TetheringService::class.java)
+                        .putExtra(TetheringService.EXTRA_ADD_INTERFACE_MONITOR, iface))
+                true
+            }
        }
    }
    override fun onMenuItemClick(item: MenuItem?): Boolean {
-        ContextCompat.startForegroundService(requireContext(), Intent(context, TetheringService::class.java)
-                .putExtra(TetheringService.EXTRA_ADD_INTERFACE_MONITOR, item?.title ?: return false))
-        return true
+        return when (item?.itemId) {
+            R.id.configuration -> item.subMenu.run {
+                findItem(R.id.configuration_repeater).isNotGone = RepeaterService.supported
+                findItem(R.id.configuration_temp_hotspot).isNotGone =
+                        adapter.localOnlyHotspotManager.binder?.configuration != null
+                true
+            }
+            R.id.configuration_repeater -> {
+                WifiApDialogFragment().withArg(WifiApDialogFragment.Arg(
+                        adapter.repeaterManager.configuration ?: return false,
+                        p2pMode = true
+                )).show(this, CONFIGURE_REPEATER)
+                true
+            }
+            R.id.configuration_temp_hotspot -> {
+                WifiApDialogFragment().withArg(WifiApDialogFragment.Arg(
+                        adapter.localOnlyHotspotManager.binder?.configuration ?: return false,
+                        readOnly = true
+                )).show(this, 0)    // read-only, no callback needed
+                true
+            }
+            R.id.configuration_ap -> try {
+                WifiApDialogFragment().withArg(WifiApDialogFragment.Arg(
+                        WifiApManager.configuration
+                )).show(this, CONFIGURE_AP)
+                true
+            } catch (e: InvocationTargetException) {
+                if (e.targetException !is SecurityException) Timber.w(e)
+                SmartSnackbar.make(e.targetException).show()
+                false
+            }
+            else -> false
+        }
    }

    override fun onCreateView(inflater: LayoutInflater, container: ViewGroup?, savedInstanceState: Bundle?): View? {
@@ -117,13 +158,19 @@ class TetheringFragment : Fragment(), ServiceConnection, MenuItem.OnMenuItemClic
        binding.interfaces.adapter = adapter
        adapter.update(emptyList(), emptyList(), emptyList())
        ServiceForegroundConnector(this, this, TetheringService::class)
-        requireActivity().toolbar.inflateMenu(R.menu.toolbar_tethering)
+        requireActivity().toolbar.apply {
+            inflateMenu(R.menu.toolbar_tethering)
+            setOnMenuItemClickListener(this@TetheringFragment)
+        }
        return binding.root
    }

    override fun onDestroyView() {
        super.onDestroyView()
-        requireActivity().toolbar.menu.clear()
+        requireActivity().toolbar.apply {
+            menu.clear()
+            setOnMenuItemClickListener(null)
+        }
    }

    override fun onResume() {
@@ -131,10 +178,20 @@ class TetheringFragment : Fragment(), ServiceConnection, MenuItem.OnMenuItemClic
        if (Build.VERSION.SDK_INT >= 27) ManageBar.Data.notifyChange()
    }

-    override fun onActivityResult(requestCode: Int, resultCode: Int, data: Intent?) = when (requestCode) {
-        REPEATER_WPS -> adapter.repeaterManager.onWpsResult(resultCode, data)
-        REPEATER_EDIT_CONFIGURATION -> adapter.repeaterManager.onEditResult(data)
-        else -> super.onActivityResult(requestCode, resultCode, data)
+    override fun onActivityResult(requestCode: Int, resultCode: Int, data: Intent?) {
+        val configuration by lazy { AlertDialogFragment.getRet<WifiApDialogFragment.Arg>(data!!).configuration }
+        when (requestCode) {
+            REPEATER_WPS -> adapter.repeaterManager.onWpsResult(resultCode, data)
+            CONFIGURE_REPEATER -> if (resultCode == DialogInterface.BUTTON_POSITIVE) {
+                adapter.repeaterManager.updateConfiguration(configuration)
+            }
+            CONFIGURE_AP -> if (resultCode == DialogInterface.BUTTON_POSITIVE) try {
+                WifiApManager.configuration = configuration
+            } catch (e: IllegalArgumentException) {
+                SmartSnackbar.make(R.string.configuration_rejected).show()
+            }
+            else -> super.onActivityResult(requestCode, resultCode, data)
+        }
    }

    override fun onRequestPermissionsResult(requestCode: Int, permissions: Array<out String>, grantResults: IntArray) {
--- a/mobile/src/main/java/be/mygod/vpnhotspot/net/wifi/WifiApManager.kt
+++ b/mobile/src/main/java/be/mygod/vpnhotspot/net/wifi/WifiApManager.kt
@@ -3,15 +3,23 @@ package be.mygod.vpnhotspot.net.wifi
 import android.net.wifi.WifiConfiguration
 import android.net.wifi.WifiManager
 import be.mygod.vpnhotspot.App.Companion.app
+import java.lang.IllegalArgumentException

-/**
- * Although the functionalities were removed in API 26, it is already not functioning correctly on API 25.
- *
- * See also: https://android.googlesource.com/platform/frameworks/base/+/5c0b10a4a9eecc5307bb89a271221f2b20448797%5E%21/
- */
 object WifiApManager {
-    private val setWifiApEnabled = WifiManager::class.java.getDeclaredMethod("setWifiApEnabled",
-            WifiConfiguration::class.java, Boolean::class.java)
+    private val getWifiApConfiguration by lazy { WifiManager::class.java.getDeclaredMethod("getWifiApConfiguration") }
+    private val setWifiApConfiguration by lazy {
+        WifiManager::class.java.getDeclaredMethod("setWifiApConfiguration", WifiConfiguration::class.java)
+    }
+    var configuration: WifiConfiguration
+        get() = getWifiApConfiguration.invoke(app.wifi) as WifiConfiguration
+        set(value) {
+            if (setWifiApConfiguration.invoke(app.wifi, value) as? Boolean != true) throw IllegalArgumentException()
+        }
+
+    private val setWifiApEnabled by lazy {
+        WifiManager::class.java.getDeclaredMethod("setWifiApEnabled",
+                WifiConfiguration::class.java, Boolean::class.java)
+    }
    /**
     * Start AccessPoint mode with the specified
     * configuration. If the radio is already running in
@@ -25,6 +33,11 @@ object WifiApManager {
    private fun WifiManager.setWifiApEnabled(wifiConfig: WifiConfiguration?, enabled: Boolean) =
            setWifiApEnabled.invoke(this, wifiConfig, enabled) as Boolean

+    /**
+     * Although the functionalities were removed in API 26, it is already not functioning correctly on API 25.
+     *
+     * See also: https://android.googlesource.com/platform/frameworks/base/+/5c0b10a4a9eecc5307bb89a271221f2b20448797%5E%21/
+     */
    @Deprecated("Not usable since API 26, malfunctioning on API 25")
    fun start(wifiConfig: WifiConfiguration? = null) {
        app.wifi.isWifiEnabled = false
--- a/mobile/src/main/java/be/mygod/vpnhotspot/net/wifi/WifiP2pDialogFragment.kt
+++ b/mobile/src/main/java/be/mygod/vpnhotspot/net/wifi/WifiP2pDialogFragment.kt
@@ -1,74 +0,0 @@
-package be.mygod.vpnhotspot.net.wifi
-
-import android.content.DialogInterface
-import android.net.wifi.WifiConfiguration
-import android.net.wifi.WifiConfiguration.AuthAlgorithm
-import android.os.Parcelable
-import android.text.Editable
-import android.text.TextWatcher
-import android.view.View
-import android.widget.EditText
-import android.widget.TextView
-import androidx.appcompat.app.AlertDialog
-import be.mygod.vpnhotspot.AlertDialogFragment
-import be.mygod.vpnhotspot.R
-import kotlinx.android.parcel.Parcelize
-import kotlinx.android.synthetic.main.dialog_wifi_ap.view.*
-import java.nio.charset.Charset
-
-/**
- * Based on: https://android.googlesource.com/platform/packages/apps/Settings/+/39b4674/src/com/android/settings/wifi/WifiApDialog.java
- *
- * This dialog has been deprecated in API 28, but we are still using it since it works better for our purposes.
- * Related: https://android.googlesource.com/platform/packages/apps/Settings/+/defb1183ecb00d6231bac7d934d07f58f90261ea
- */
-class WifiP2pDialogFragment : AlertDialogFragment<WifiP2pDialogFragment.Arg, WifiP2pDialogFragment.Arg>(), TextWatcher {
-    @Parcelize
-    data class Arg(val configuration: WifiConfiguration) : Parcelable
-
-    private lateinit var mView: View
-    private lateinit var mSsid: TextView
-    private lateinit var mPassword: EditText
-    override val ret: Arg? get() {
-        val config = WifiConfiguration()
-        config.SSID = mSsid.text.toString()
-        config.allowedAuthAlgorithms.set(AuthAlgorithm.OPEN)
-        if (mPassword.length() != 0) {
-            val password = mPassword.text.toString()
-            config.preSharedKey = password
-        }
-        return Arg(config)
-    }
-
-    override fun AlertDialog.Builder.prepare(listener: DialogInterface.OnClickListener) {
-        mView = requireActivity().layoutInflater.inflate(R.layout.dialog_wifi_ap, null)
-        setView(mView)
-        setTitle(R.string.repeater_configure)
-        mSsid = mView.ssid
-        mPassword = mView.password
-        setPositiveButton(context.getString(R.string.wifi_save), listener)
-        setNegativeButton(context.getString(R.string.wifi_cancel), null)
-        mSsid.text = arg.configuration.SSID
-        mSsid.addTextChangedListener(this@WifiP2pDialogFragment)
-        mPassword.setText(arg.configuration.preSharedKey)
-        mPassword.addTextChangedListener(this@WifiP2pDialogFragment)
-    }
-
-    override fun onStart() {
-        super.onStart()
-        validate()
-    }
-
-    private fun validate() {
-        val mSsidString = mSsid.text.toString()
-        val ssidValid = mSsid.length() != 0 && Charset.forName("UTF-8").encode(mSsidString).limit() <= 32
-        val passwordValid = mPassword.length() >= 8
-        mView.password_wrapper.error =
-                if (passwordValid) null else requireContext().getString(R.string.credentials_password_too_short)
-        (dialog as AlertDialog).getButton(DialogInterface.BUTTON_POSITIVE).isEnabled = ssidValid && passwordValid
-    }
-
-    override fun onTextChanged(s: CharSequence, start: Int, before: Int, count: Int) { }
-    override fun beforeTextChanged(s: CharSequence, start: Int, count: Int, after: Int) { }
-    override fun afterTextChanged(editable: Editable) = validate()
-}
--- a/mobile/src/main/java/be/mygod/vpnhotspot/net/wifi/configuration/P2pSupplicantConfiguration.kt
+++ b/mobile/src/main/java/be/mygod/vpnhotspot/net/wifi/configuration/P2pSupplicantConfiguration.kt
@@ -1,4 +1,4 @@
-package be.mygod.vpnhotspot.net.wifi
+package be.mygod.vpnhotspot.net.wifi.configuration

 import android.net.wifi.p2p.WifiP2pGroup
 import android.os.Build
--- a/mobile/src/main/java/be/mygod/vpnhotspot/net/wifi/configuration/WifiApDialogFragment.kt
+++ b/mobile/src/main/java/be/mygod/vpnhotspot/net/wifi/configuration/WifiApDialogFragment.kt
@@ -0,0 +1,149 @@
+package be.mygod.vpnhotspot.net.wifi.configuration
+
+import android.annotation.TargetApi
+import android.content.DialogInterface
+import android.net.wifi.WifiConfiguration
+import android.net.wifi.WifiConfiguration.AuthAlgorithm
+import android.os.Build
+import android.os.Parcelable
+import android.text.Editable
+import android.text.TextWatcher
+import android.view.View
+import android.widget.AdapterView
+import android.widget.ArrayAdapter
+import androidx.appcompat.app.AlertDialog
+import androidx.core.view.isGone
+import be.mygod.vpnhotspot.AlertDialogFragment
+import be.mygod.vpnhotspot.App.Companion.app
+import be.mygod.vpnhotspot.R
+import kotlinx.android.parcel.Parcelize
+import kotlinx.android.synthetic.main.dialog_wifi_ap.view.*
+import java.lang.IllegalStateException
+import java.nio.charset.Charset
+
+/**
+ * Based on: https://android.googlesource.com/platform/packages/apps/Settings/+/39b4674/src/com/android/settings/wifi/WifiApDialog.java
+ *
+ * This dialog has been deprecated in API 28, but we are still using it since it works better for our purposes.
+ * Related: https://android.googlesource.com/platform/packages/apps/Settings/+/defb1183ecb00d6231bac7d934d07f58f90261ea
+ */
+class WifiApDialogFragment : AlertDialogFragment<WifiApDialogFragment.Arg, WifiApDialogFragment.Arg>(), TextWatcher {
+    @Parcelize
+    data class Arg(val configuration: WifiConfiguration,
+                   val readOnly: Boolean = false,
+                   /**
+                    * KeyMgmt is enforced to WPA_PSK.
+                    * Various values for apBand are allowed according to different rules.
+                    */
+                   val p2pMode: Boolean = false) : Parcelable
+
+    @TargetApi(23)
+    private sealed class BandOption {
+        open val apBand get() = AP_BAND_2GHZ
+        open val apChannel get() = 0
+
+        object BandAny : BandOption() {
+            override val apBand get() = AP_BAND_ANY
+            override fun toString() = app.getString(R.string.wifi_ap_choose_auto)
+        }
+        object Band2GHz : BandOption() {
+            override fun toString() = app.getString(R.string.wifi_ap_choose_2G)
+        }
+        object Band5GHz : BandOption() {
+            override val apBand get() = AP_BAND_5GHZ
+            override fun toString() = app.getString(R.string.wifi_ap_choose_5G)
+        }
+        class Channel(override val apChannel: Int) : BandOption() {
+            override fun toString() = "${channelToFrequency(apChannel)} MHz ($apChannel)"
+        }
+    }
+
+    private lateinit var dialogView: View
+    override val ret: Arg? get() {
+        return Arg(WifiConfiguration().apply {
+            SSID = dialogView.ssid.text.toString()
+            allowedKeyManagement.set(
+                    if (arg.p2pMode) WifiConfiguration.KeyMgmt.WPA_PSK else dialogView.security.selectedItemPosition)
+            allowedAuthAlgorithms.set(AuthAlgorithm.OPEN)
+            if (dialogView.password.length() != 0) preSharedKey = dialogView.password.text.toString()
+            if (Build.VERSION.SDK_INT >= 23) {
+                val bandOption = dialogView.band.selectedItem as BandOption
+                apBand = bandOption.apBand
+                apChannel = bandOption.apChannel
+            }
+        })
+    }
+
+    override fun AlertDialog.Builder.prepare(listener: DialogInterface.OnClickListener) {
+        val activity = requireActivity()
+        dialogView = activity.layoutInflater.inflate(R.layout.dialog_wifi_ap, null)
+        setView(dialogView)
+        setTitle(R.string.configuration_view)
+        if (!arg.readOnly) setPositiveButton(R.string.wifi_save, listener)
+        setNegativeButton(R.string.donations__button_close, null)
+        dialogView.ssid.setText(arg.configuration.SSID)
+        if (!arg.readOnly) dialogView.ssid.addTextChangedListener(this@WifiApDialogFragment)
+        if (arg.p2pMode) dialogView.security_wrapper.isGone = true else dialogView.security.apply {
+            adapter = ArrayAdapter(activity, android.R.layout.simple_spinner_item, 0,
+                    WifiConfiguration.KeyMgmt.strings).apply {
+                setDropDownViewResource(android.R.layout.simple_spinner_dropdown_item)
+            }
+            onItemSelectedListener = object : AdapterView.OnItemSelectedListener {
+                override fun onNothingSelected(parent: AdapterView<*>?) =
+                        throw IllegalStateException("Must select something")
+                override fun onItemSelected(parent: AdapterView<*>?, view: View?, position: Int, id: Long) {
+                    dialogView.password_wrapper.isGone = position == WifiConfiguration.KeyMgmt.NONE
+                }
+            }
+            val selected = arg.configuration.allowedKeyManagement.nextSetBit(0)
+            check(selected >= 0) { "No key management selected" }
+            check(arg.configuration.allowedKeyManagement.nextSetBit(selected + 1) < 0) {
+                "More than 1 key managements supplied"
+            }
+            setSelection(selected)
+        }
+        dialogView.password.setText(arg.configuration.preSharedKey)
+        if (!arg.readOnly) dialogView.password.addTextChangedListener(this@WifiApDialogFragment)
+        if (Build.VERSION.SDK_INT >= 23) dialogView.band.apply {
+            val options = mutableListOf<BandOption>().apply {
+                if (arg.p2pMode) add(BandOption.BandAny) else {
+                    if (Build.VERSION.SDK_INT >= 28) add(BandOption.BandAny)
+                    add(BandOption.Band2GHz)
+                    add(BandOption.Band5GHz)
+                }
+                addAll((1..165).map { BandOption.Channel(it) })
+            }
+            adapter = ArrayAdapter(activity, android.R.layout.simple_spinner_item, 0, options).apply {
+                setDropDownViewResource(android.R.layout.simple_spinner_dropdown_item)
+            }
+            setSelection(if (arg.configuration.apChannel in 1..165) {
+                options.indexOfFirst { it.apChannel == arg.configuration.apChannel }
+            } else options.indexOfFirst { it.apBand == arg.configuration.apBand })
+        } else dialogView.band_wrapper.isGone = true
+    }
+
+    override fun onResume() {
+        super.onResume()
+        if (!arg.readOnly) validate()
+    }
+
+    /**
+     * This function is reached only if not arg.readOnly.
+     */
+    private fun validate() {
+        val ssidValid = dialogView.ssid.length() != 0 &&
+                Charset.forName("UTF-8").encode(dialogView.ssid.text.toString()).limit() <= 32
+        val passwordValid = when (dialogView.security.selectedItemPosition) {
+            WifiConfiguration.KeyMgmt.WPA_PSK, WPA2_PSK -> dialogView.password.length() >= 8
+            else -> true    // do not try to validate
+        }
+        dialogView.password_wrapper.error = if (passwordValid) null else {
+            requireContext().getString(R.string.credentials_password_too_short)
+        }
+        (dialog as AlertDialog).getButton(DialogInterface.BUTTON_POSITIVE).isEnabled = ssidValid && passwordValid
+    }
+
+    override fun onTextChanged(s: CharSequence, start: Int, before: Int, count: Int) { }
+    override fun beforeTextChanged(s: CharSequence, start: Int, count: Int, after: Int) { }
+    override fun afterTextChanged(editable: Editable) = validate()
+}
--- a/mobile/src/main/java/be/mygod/vpnhotspot/net/wifi/configuration/WifiConfiguration.kt
+++ b/mobile/src/main/java/be/mygod/vpnhotspot/net/wifi/configuration/WifiConfiguration.kt
@@ -0,0 +1,84 @@
+package be.mygod.vpnhotspot.net.wifi.configuration
+
+import android.net.wifi.WifiConfiguration
+import androidx.annotation.RequiresApi
+import be.mygod.vpnhotspot.net.wifi.WifiApManager
+import timber.log.Timber
+import java.lang.reflect.InvocationTargetException
+
+val WPA2_PSK = WifiConfiguration.KeyMgmt.strings.indexOf("WPA2_PSK")
+
+/**
+ * apBand and apChannel is available since API 23.
+ *
+ * https://android.googlesource.com/platform/frameworks/base/+/android-6.0.0_r1/wifi/java/android/net/wifi/WifiConfiguration.java#242
+ */
+private val apBandField by lazy { WifiConfiguration::class.java.getDeclaredField("apBand") }
+private val apChannelField by lazy { WifiConfiguration::class.java.getDeclaredField("apChannel") }
+
+/**
+ * 2GHz band.
+ *
+ * https://android.googlesource.com/platform/frameworks/base/+/android-7.0.0_r1/wifi/java/android/net/wifi/WifiConfiguration.java#241
+ */
+@RequiresApi(23)
+const val AP_BAND_2GHZ = 0
+/**
+ * 5GHz band.
+ */
+@RequiresApi(23)
+const val AP_BAND_5GHZ = 1
+/**
+ * Device is allowed to choose the optimal band (2Ghz or 5Ghz) based on device capability,
+ * operating country code and current radio conditions.
+ *
+ * Introduced in 9.0, but we will abuse this constant anyway.
+ * https://android.googlesource.com/platform/frameworks/base/+/android-9.0.0_r1/wifi/java/android/net/wifi/WifiConfiguration.java#295
+ */
+@RequiresApi(23)
+const val AP_BAND_ANY = -1
+
+/**
+ * The band which AP resides on
+ * -1:Any 0:2G 1:5G
+ * By default, 2G is chosen
+ */
+var WifiConfiguration.apBand: Int
+    @RequiresApi(23) get() = apBandField.get(this) as Int
+    @RequiresApi(23) set(value) = apBandField.set(this, value)
+/**
+ * The channel which AP resides on
+ * 2G  1-11
+ * 5G  36,40,44,48,149,153,157,161,165
+ * 0 - find a random available channel according to the apBand
+ */
+var WifiConfiguration.apChannel: Int
+    @RequiresApi(23) get() = apChannelField.get(this) as Int
+    @RequiresApi(23) set(value) = apChannelField.set(this, value)
+
+/**
+ * The frequency which AP resides on (MHz). Resides in range [2412, 5815].
+ */
+fun channelToFrequency(channel: Int) = when (channel) {
+    in 1..14 -> 2407 + 5 * channel
+    in 15..165 -> 5000 + 5 * channel
+    else -> throw IllegalArgumentException("Invalid channel $channel")
+}
+
+/**
+ * Based on:
+ * https://android.googlesource.com/platform/packages/apps/Settings/+/android-5.0.0_r1/src/com/android/settings/wifi/WifiApDialog.java#88
+ * https://android.googlesource.com/platform/packages/apps/Settings/+/b1af85d/src/com/android/settings/wifi/tether/WifiTetherSettings.java#162
+ */
+fun newWifiApConfiguration(ssid: String, passphrase: String?) = try {
+    WifiApManager.configuration
+} catch (e: InvocationTargetException) {
+    if (e.targetException !is SecurityException) Timber.w(e)
+    WifiConfiguration()
+}.apply {
+    SSID = ssid
+    preSharedKey = passphrase
+    allowedKeyManagement.clear()
+    allowedAuthAlgorithms.clear()
+    allowedAuthAlgorithms.set(WifiConfiguration.AuthAlgorithm.OPEN)
+}
--- a/mobile/src/main/java/be/mygod/vpnhotspot/room/Converters.kt
+++ b/mobile/src/main/java/be/mygod/vpnhotspot/room/Converters.kt
@@ -1,8 +1,8 @@
 package be.mygod.vpnhotspot.room

-import android.os.Parcel
 import android.text.TextUtils
 import androidx.room.TypeConverter
+import be.mygod.vpnhotspot.util.useParcel
 import java.net.InetAddress
 import java.nio.ByteBuffer
 import java.nio.ByteOrder
@@ -10,27 +10,17 @@ import java.nio.ByteOrder
 object Converters {
    @JvmStatic
    @TypeConverter
-    fun persistCharSequence(cs: CharSequence): ByteArray {
-        val p = Parcel.obtain()
-        try {
-            TextUtils.writeToParcel(cs, p, 0)
-            return p.marshall()
-        } finally {
-            p.recycle()
-        }
+    fun persistCharSequence(cs: CharSequence) = useParcel { p ->
+        TextUtils.writeToParcel(cs, p, 0)
+        p.marshall()
    }

    @JvmStatic
    @TypeConverter
-    fun unpersistCharSequence(data: ByteArray): CharSequence {
-        val p = Parcel.obtain()
-        try {
-            p.unmarshall(data, 0, data.size)
-            p.setDataPosition(0)
-            return TextUtils.CHAR_SEQUENCE_CREATOR.createFromParcel(p)
-        } finally {
-            p.recycle()
-        }
+    fun unpersistCharSequence(data: ByteArray) = useParcel { p ->
+        p.unmarshall(data, 0, data.size)
+        p.setDataPosition(0)
+        TextUtils.CHAR_SEQUENCE_CREATOR.createFromParcel(p)
    }

    @JvmStatic
--- a/mobile/src/main/java/be/mygod/vpnhotspot/util/Utils.kt
+++ b/mobile/src/main/java/be/mygod/vpnhotspot/util/Utils.kt
@@ -1,7 +1,9 @@
 package be.mygod.vpnhotspot.util

+import android.annotation.SuppressLint
 import android.content.*
 import android.os.Build
+import android.os.Parcel
 import android.text.Spannable
 import android.text.SpannableString
 import android.text.SpannableStringBuilder
@@ -15,7 +17,6 @@ import androidx.databinding.BindingAdapter
 import be.mygod.vpnhotspot.App.Companion.app
 import be.mygod.vpnhotspot.room.macToString
 import be.mygod.vpnhotspot.widget.SmartSnackbar
-import java.lang.RuntimeException
 import java.net.InetAddress
 import java.net.NetworkInterface
 import java.net.SocketException
@@ -32,6 +33,15 @@ fun Long.toPluralInt(): Int {
    return (this % 1000000000).toInt() + 1000000000
 }

+@SuppressLint("Recycle")
+fun <T> useParcel(block: (Parcel) -> T) = Parcel.obtain().run {
+    try {
+        block(this)
+    } finally {
+        recycle()
+    }
+}
+
 fun broadcastReceiver(receiver: (Context, Intent) -> Unit) = object : BroadcastReceiver() {
    override fun onReceive(context: Context, intent: Intent) = receiver(context, intent)
 }