I am learning WorkManager and wondering if following the correct way of setting network constraint for both Wifi and data (cellular):
val constraints = Constraints.Builder().run {
setRequiredNetworkType(NetworkType.UNMETERED) //Wifi
setRequiredNetworkType(NetworkType.METERED) //data
build()
}
That's exactly the use case for the NetworkType.CONNECTED type:
Any working network connection is required for this work.
I seem to be having a small problem with MulticastSocket on Android: writing an SSDP-related application. The socket works just fine when I set everything up the first time, but when I stop discovery, and try to restart things, I just get a SocketException: Socket Closed. I'm not closing the socket, I'm simply stopping the Kotlin Coroutine that is responsible for calling socket.receive() in a loop. Example:
fun listenForPackets(): Flow<DatagramPacket> {
return flow {
multicastSocket.use {
val incomingBuffer = ByteArray(MULTICAST_DATAGRAM_SIZE)
while (true) {
val incomingPacket = DatagramPacket(incomingBuffer, incomingBuffer.size)
it.receive(incomingPacket)
emit(incomingPacket)
incomingPacket.length = incomingBuffer.size
}
}
}
}
The problem
So the problem is that when I try to call that function again, I get a SocketException: Socket Closed. The socket initialization code is run once, meaning that toggling discovery on/off will use the same socket multiple times; the following code is run once throughout the whole application:
multicastSocket = MulticastSocket(MULTICAST_PORT)
multicastSocket.reuseAddress = true
multicastSocket.joinGroup(multicastGroup)
multicastLock.acquire()
What I have tried
My first thought was that I was not cancelling the Kotlin Coroutine correctly. As a result, I switched to using typical Java Threads, to no avail. Starting the thread the first time works, but, restarting discovery yields the same problem. I have also tried to not leave the group, and keep the multicastLock acquired - same problem.
What works
What works is having the initialization code (where I assign the socket, join the group, and acquire lock) run every time I need to start a scan. At the end of the scan, I reset all of the variables (leave group, release lock, close socket). So my question becomes - is this the correct approach? Or am I simply doing something else wrong?
Just to re-iterate, I'm discovering packets just fine, the issue is with restarting the discovery. Thank you in advance for any help!
Background
I've noticed that in WifiManager class there is a function called addNetwork, that might be useful if I want to restore or save networks information (network name AKA SSID, together with the password and the type), so that I could also connect to it.
The problem
I can't find much information about how to do such a thing. I've seen various examples on StackOverflow, and if I target Android API 28 (or below), I indeed succeed to make it add a network and even connect to it.
When targeting Android 29 (Android Q), however, it fails to add the network.
What I've found
Since I'm trying on Pixel 2 with Android Q beta 4, I think that maybe it's because addNetwork is deprecated, so the docs even say so, and that if I target Android Q, it won't work, and indeed it doesn't work:
Compatibility Note: For applications targeting Build.VERSION_CODES.Q
or above, this API will always return -1.
The way it seems it should work up till Android Q (excluding), is by preparing WifiConfiguration and adding it. Later I can also connect to it if I wish. On Android Q, it seems it was replaced by WifiNetworkSuggestion, but it doesn't seem like it's about adding a network at all:
The Network Suggestion object is used to provide a Wi-Fi network for
consideration when auto-connecting to networks. Apps cannot directly
create this object, they must use
WifiNetworkSuggestion.Builder#build() to obtain an instance of this
object.
Apps can provide a list of such networks to the platform using
WifiManager#addNetworkSuggestions(List).
Here's my current code, for pre-Android-Q
#WorkerThread
fun addNetwork(context: Context, networkName: String, networkPassword: String? = null, keyMgmt: Int = WifiConfiguration.KeyMgmt.NONE) {
val wifiManager = context.getSystemService(Context.WIFI_SERVICE) as WifiManager
val conf = WifiConfiguration()
conf.SSID = "\"$networkName\""
conf.preSharedKey = if (networkPassword.isNullOrEmpty()) "" else "\"$networkPassword\""
conf.allowedKeyManagement.set(keyMgmt)
when (keyMgmt) {
WifiConfiguration.KeyMgmt.WPA_PSK -> {
//WPA/WPA2
}
WifiConfiguration.KeyMgmt.IEEE8021X -> {
}
WifiConfiguration.KeyMgmt.WPA_EAP -> {
}
WifiConfiguration.KeyMgmt.NONE -> {
if (networkPassword.isNullOrEmpty()) {
//open network
conf.wepKeys[0] = "\"\""
} else {
//wep
conf.wepKeys[0] = "\"" + networkPassword + "\""
conf.wepTxKeyIndex = 0
conf.allowedGroupCiphers.set(WifiConfiguration.GroupCipher.WEP40)
}
}
}
if (networkPassword.isNullOrEmpty()) {
//open network
conf.allowedKeyManagement.set(WifiConfiguration.KeyMgmt.NONE)
} else {
}
wifiManager.isWifiEnabled = true
while (!wifiManager.pingSupplicant()) {
Log.d("AppLog", "waiting to be able to add network")
}
val networkId = wifiManager.addNetwork(conf)
if (networkId == -1)
Log.d("AppLog", "failed to add network")
else {
wifiManager.enableNetwork(networkId, false)
Log.d("AppLog", "success to add network")
}
}
Seems it requires only these permissions:
<uses-permission android:name="android.permission.ACCESS_WIFI_STATE"/>
<uses-permission android:name="android.permission.CHANGE_WIFI_STATE"/>
But in any case, this works as long as you don't target Android Q (API 29) and above. When you target it, I indeed always get "-1" as a result, meaning it fails.
I've also found an issue on the issue tracker (here and I wrote about it here), telling about someone that needs the API back, but I'm not sure it's about adding a network.
Looking at WifiNetworkSuggestion, I don't see that it has as many things to set as WifiConfiguration via its builder, so this is another reason for why I suspect it's not about adding a network.
But I tried anyway. Here's the code I've tried, for example, to add a normal WPA network:
#WorkerThread
fun addNetworkAndroidQ(context: Context, networkName: String, networkPassword: String? = null) {
val wifiManager = context.getSystemService(Context.WIFI_SERVICE) as WifiManager
val list = ArrayList<WifiNetworkSuggestion>()
val builder = WifiNetworkSuggestion.Builder().setSsid(networkName)
if (!networkPassword.isNullOrEmpty())
builder.setWpa2Passphrase(networkPassword)
list.add(builder.build())
val result = wifiManager.addNetworkSuggestions(list)
if (result == WifiManager.STATUS_NETWORK_SUGGESTIONS_SUCCESS)
Log.d("AppLog", "success")
else Log.d("AppLog", "failed")
}
When running (I gave it my Wifi network details, after making the OS forget about it), it says it succeeded, but nothing occurred on the OS's Wifi settings. The network doesn't exist there with the password I've added. So I really don't get what it did...
After a few long seconds, I've noticed a notification asking me if it's ok to connect to the suggested networks made by the app:
But still when I chose that I accept, it didn't do anything, as before.
I tried to make another POC, thinking I might have done it incorrectly, but then it didn't even show the notification. Since I think this whole behavior is a bug, I've reported about it here.
Not only that, but I've found out that if indeed it is supposed to add a network one way or another, it still has some serious restrictions, such as max added networks (here) and being removed upon uninstall of the app (here)
The questions
How should Android Q be handled exactly? Is there really no API anymore to add a network?
If WifiNetworkSuggestion is not about adding a network, what is it really used for exactly?
Since I'm not familiar enough with the tidbits of adding a network, is my code correct about all possible ways to add a network? I ask this because someone wrote here that people should enable Wifi and make sure pingSupplicant returns true. Is it true? Or would it be enough to just call addNetwork ?
If it's now impossible to add a network using the normal API, is there maybe a solution by using a rooted device instead? Maybe some adb command?
EDIT: Not sure how to do it officially, but using adb, you might be able to add Wifi-networks on Android 11 . Need to check adb shell cmd wifi help .
I stuck with same issue, but somehow I reached a reproducible state for connecting a desired network and I want to share my findings it may helps.
As a summary:
You have to disable all auto connection before applying WifiNetworkSuggestion logic
For more details, Please read the following:
I used the following code (Similar to what you use):
private fun connectUsingNetworkSuggestion(ssid: String, password: String) {
val wifiNetworkSuggestion = WifiNetworkSuggestion.Builder()
.setSsid(ssid)
.setWpa2Passphrase(password)
.build()
// Optional (Wait for post connection broadcast to one of your suggestions)
val intentFilter =
IntentFilter(WifiManager.ACTION_WIFI_NETWORK_SUGGESTION_POST_CONNECTION);
val broadcastReceiver = object : BroadcastReceiver() {
override fun onReceive(context: Context, intent: Intent) {
if (!intent.action.equals(WifiManager.ACTION_WIFI_NETWORK_SUGGESTION_POST_CONNECTION)) {
return
}
showToast("Connection Suggestion Succeeded")
// do post connect processing here
}
}
registerReceiver(broadcastReceiver, intentFilter)
lastSuggestedNetwork?.let {
val status = wifiManager.removeNetworkSuggestions(listOf(it))
Log.i("WifiNetworkSuggestion", "Removing Network suggestions status is $status")
}
val suggestionsList = listOf(wifiNetworkSuggestion)
var status = wifiManager.addNetworkSuggestions(suggestionsList)
Log.i("WifiNetworkSuggestion", "Adding Network suggestions status is $status")
if (status == WifiManager.STATUS_NETWORK_SUGGESTIONS_ERROR_ADD_DUPLICATE) {
showToast("Suggestion Update Needed")
status = wifiManager.removeNetworkSuggestions(suggestionsList)
Log.i("WifiNetworkSuggestion", "Removing Network suggestions status is $status")
status = wifiManager.addNetworkSuggestions(suggestionsList)
}
if (status == WifiManager.STATUS_NETWORK_SUGGESTIONS_SUCCESS) {
lastSuggestedNetwork = wifiNetworkSuggestion
lastSuggestedNetworkSSID = ssid
showToast("Suggestion Added")
}
}
So here are the steps:
Install fresh version / Or remove all suggestion you added before
Make sure that you forgot all surrounding networks so your device won't auto-connect
Add wifi network suggestions list
Go to Wifi Settings to scan networks Or wait until next scan is running
A notification prompt will appear :
6. When you Press "Yes" the system will auto-connect with it via your app and internet will work normally. See the following:
Please note the following:
If you disconnect the network from Wifi Settings (i.e press disconnect bin icon in the following image) your network will be blocked for 24 hours from auto-connect even if you removed the suggested network using wifiManager.removeNetworkSuggestions(listOf(it)) and add it again. And even if you uninstall and install your app again
Unfortunately, this is limitation added by Android System as described here:
If the user uses the Wi-Fi picker to explicitly disconnect from one of the network suggestions when connected to it, then that network is blacklisted for 24 hours. During the blacklist period, that network will not be considered for auto-connection, even if the app removes and re-adds the network suggestion corresponding to the network.
If you uninstall the application while connected to suggested WiFi, the system will close the connection automatically.
In case you have multiple suggestion you can priorities them by using WifiNetworkSuggestion.Builder().setPriority(<Priority Integer>) as mentioned here:
Specify the priority of this network among other network suggestions provided by the same app (priorities have no impact on suggestions by different apps). The higher the number, the higher the priority (i.e value of 0 = lowest priority).
In case you pressed "No" in notification prompt, you can change it from (Settings > Apps & notifications > Special App access > Wi-Fi Control > App name) as described here:
A user declining the network suggestion notification removes the CHANGE_WIFI_STATE permission from the app. The user can grant this approval later by going into the Wi-Fi control menu (Settings > Apps & notifications > Special App access > Wi-Fi Control > App name).
I wish I had answers to all of your questions because I'm currently struggling with similar issues.
After many hours I was finally able to connect to the desired network using this approach:
val wifiNetworkSpecifier = WifiNetworkSpecifier.Builder()
.setSsid(ssid)
.setWpa2Passphrase(passphrase)
.setBssid(mac)
.build()
val networkRequest = NetworkRequest.Builder()
.addTransportType(NetworkCapabilities.TRANSPORT_WIFI)
.setNetworkSpecifier(wifiNetworkSpecifier)
.build()
val connectivityManager = applicationContext.getSystemService(Context.CONNECTIVITY_SERVICE) as ConnectivityManager?
connectivityManager?.requestNetwork(networkRequest, ConnectivityManager.NetworkCallback())
You can receive a whole host of events through the ConnectivityManager.NetworkCallback().
Looks like they've added support in Android 11(API 30) for adding network configuration that persists outside of the application scope and is saved as a system network configuration just like it was done with the deprecated WiFiManager method addNetwork. All you need to do is to use ACTION_WIFI_ADD_NETWORKS to show a system dialog that asks a user if he wants to proceed with adding a new Wifi suggestion to the system. This is how we start that dialog:
// used imports
import android.provider.Settings.ACTION_WIFI_ADD_NETWORKS
import android.provider.Settings.EXTRA_WIFI_NETWORK_LIST
import android.app.Activity
import android.content.Intent
import android.net.wifi.WifiNetworkSuggestion
// show system dialog for adding new network configuration
val wifiSuggestionBuilder = WifiNetworkSuggestion.Builder()
.setSsid("network SSID")
.build()
val suggestionsList = arraylistOf(wifiSuggestionBuilder)
val intent = new Intent(ACTION_WIFI_ADD_NETWORKS)
intent.putParcelableArrayListExtra(EXTRA_WIFI_NETWORK_LIST, suggestionsList);
activity.startActivityForResult(intent, 1000)
The dialog looks like this:
And then we just need to handle a result in onActivityResult method like this:
override fun onActivityResult(requestCode: Int, resultCode: Int, data: Intent?) {
if (requestCode == 1000) {
if (resultCode == Activity.RESULT_OK) {
// network succesfully added - User pressed Save
} else if (resultCode == Activity.RESULT_CANCELED) {
// failed attempt of adding network to system - User pressed Cancel
}
}
}
But as I've tested this code on Android devices that have older Android versions(lower then API30) installed I've got a crash every time I want it to show that dialog for adding a new network configuration. This is the crash:
java.lang.RuntimeException: Unable to start activity: android.content.ActivityNotFoundException: No Activity found to handle Intent { act=android.settings.WIFI_ADD_NETWORKS (has extras) }
Looks like the new way is not back-supported out of the box. So, for API30 we can use a new Intent action, for API 28 and below we can still use the old way of adding Networks, but for API29 we have some kind of gray area where I was not able to find a good solution yet. If anyone has an idea what else to do please share it with me. ;)
#Sebastian Helzer's answer works for me. I use java in my application. This may help java users...
WifiNetworkSpecifier wifiNetworkSpecifier = new WifiNetworkSpecifier.Builder()
.setSsid(ssid)
.setWpa2Passphrase(password)
.build();
NetworkRequest networkRequest = new NetworkRequest.Builder()
.addTransportType(NetworkCapabilities.TRANSPORT_WIFI)
.setNetworkSpecifier(wifiNetworkSpecifier)
.build();
ConnectivityManager connectivityManager = (ConnectivityManager)this.getApplicationContext().getSystemService(Context.CONNECTIVITY_SERVICE);
connectivityManager.requestNetwork(networkRequest, new ConnectivityManager.NetworkCallback());
we work with xamarin android and visual studio 2015.
we have an app who works since several months fine :)
This app when it starts call a webservice for to retrieve some data in json format.
All work fine, but last week we have a problem and we are COMPLETY lost about it !
Since last week, for one device when it call the web service we receive this error in the catch exception :
unable to read data from the transport connection Connection reset by peer ...
Here is it the method on the device who call the WS:
public override HttpResult ExecuteGet(Uri target)
{
var client = new HttpClient();
client.MaxResponseContentBufferSize = 25600000;
try
{
var response = client.GetAsync(target).Result;
if (response.IsSuccessStatusCode)
{
var content = response.Content.ReadAsStringAsync().Result;
return new HttpResult(content, null, null);
}
return new HttpResult(null, " ERROR MESSAGE ", response.StatusCode.ToString());
}
catch (Exception e)
{
return new HttpResult(null, " ERROR MESSAGE", e.Message);
}
}
well, now with the same device if we stop the wifi and call the webservice in GPRS that work.
Also we have two wifi, we also have noticed if the device connect on the second wifi and try to call the web service => that's work !
After talk with some colleague, they tell me to look to update my android version of the device , or wifi app on the device but for me the first thing we need to do will be to compare wifi 1 and wifi 2.
My question is, how i can compare two wifi ?
All suggestion are welcome because we search and we find nothing ...
Thanks for all guys that's really great to share your knowledge ...
I have 2 Android devices using WiFi Direct. On one device I can get information about the other device using the WifiP2pManager class, and request a connection to the other device. However when I request a connection, the other device pops up a little window and asks the user if they want to accept the connection request.
Is it possible to auto-accept these connection requests? I.E to be able to connect to the other device without user confirmation?
It can be easily done with the help of Xposed framework. You just need to replace the single method inside one of android java classes (see the link from snihalani's answer). But of course to use Xposed your device must be rooted. The main idea can be expressed in the following code (using Xposed)
#Override
public void handleLoadPackage(LoadPackageParam lpparam) {
try {
Class<?> wifiP2pService = Class.forName("android.net.wifi.p2p.WifiP2pService", false, lpparam.classLoader);
for (Class<?> c : wifiP2pService.getDeclaredClasses()) {
//XposedBridge.log("inner class " + c.getSimpleName());
if ("P2pStateMachine".equals(c.getSimpleName())) {
XposedBridge.log("Class " + c.getName() + " found");
Method notifyInvitationReceived = c.getDeclaredMethod("notifyInvitationReceived");
final Method sendMessage = c.getMethod("sendMessage", int.class);
XposedBridge.hookMethod(notifyInvitationReceived, new XC_MethodReplacement() {
#Override
protected Object replaceHookedMethod(MethodHookParam param) throws Throwable {
final int PEER_CONNECTION_USER_ACCEPT = 0x00023000 + 2;
sendMessage.invoke(param.thisObject, PEER_CONNECTION_USER_ACCEPT);
return null;
}
});
break;
}
}
} catch (Throwable t) {
XposedBridge.log(t);
}
}
I tested it on SGS4 stock 4.2.2 ROM and it worked.
I guess the same could be done with the help of Substrate for android.
From my current understanding of the API, You cannot really accept connections automatically without user's intervention. You can initiate a connection, that doesn't require user intervention. If both of your devices are mobile devices, you will have to accept connection request on one end.
I have put this as a feature request in android project hosting.
You can monitor their response here: https://code.google.com/p/android/issues/detail?id=30880
Based on the comments, do you really need to connect to the devices if you just want to track and log the vehicles around you ?
I don't know the scope of the project, but you could simply use the WifiP2pDeviceList that you get when you request the peers in the WifiP2pManager. You could get the list of the devices (~= vehicles) around you and could log this.
Connection is useful if you want to send more detailed information I guess.
If you can modify the framework, you can ignore the accept window and direct send the "PEER_CONNECTION_USER_ACCEPT".
Base on Android 5.0, "frameworks/opt/net/wifi/service/java/com/android/server/wifi/p2p/WifiP2pServiceImpl.java".
You must find the "notifyInvitationReceived", and modify to ...
private void notifyInvitationReceived() {
/*Direct sends the accept message.*/
sendMessage(PEER_CONNECTION_USER_ACCEPT);
/*
... old code
*/
}