I have an app that's custom built for a client and not available in the Play Store that basically makes some network calls when it detects that the device is connected to their WiFi. This should happen even if it has no internet connection, every request that the app makes is to a local address.
The problem comes with the new batch of tablets that the client has purchased (Galaxy Tab Active 2, Android 8.1.0, Build number M1AJQ.T395XXU3BRJ5), which will always prefer a connection with internet access over whatever network I'm telling it to bind to.
WiFi -> Advanced -> Switch to mobile data is already disabled, so that should not be it.
Here's the code I'm using that has been working until now:
ConnectivityManager cm = (ConnectivityManager) getApplication().getSystemService(Context.CONNECTIVITY_SERVICE);
Network[] networks = cm.getAllNetworks();
for (int i = 0, networksLength = networks.length; !bound && i < networksLength; i++) {
Network network = networks[i];
if (correctNetwork(network)) { //SSID check
bound = cm.bindProcessToNetwork(network);
Log.i(TAG, "Bound? " + bound);
}
}
On all their previous devices, my own phone and even a Galaxy Tab Active 1 this is working: we see "Bound? true" in the logs and every connection is made through the right network. On the Active 2 we always see "Bound? false" and it will use the 4G connection. Disabling data is not an option.
If this is a Samsung bug, is there a workaround for it? Or maybe an alternative way of forcing an HttpURLConnection to use a specific network?
Related
My app needs to use a wifi network (without internet, thus android avoids it by default). And I want it to be simple to use (like Grandma doesn't have to be manually changing settings). This is just an personal IoT device so I want to use ConnectivityManager.BindProcessToNetwork(Android.Net.Network network). How do I get the Android.Net.Network associated with the currently connected wifi network so I can use BindProcessToNetwork?
//c#(Xamarin)
//my rudimentary attempt to get the connected wifi network:
var networks = ConnectivityManager.GetAllNetworks();
foreach (Network network in networks) {
NetworkCapabilities networkCability =ConnectivityManager.GetNetworkCapabilities(network);
if (networkCability.HasTransport(TransportType.Wifi))
{
currentWifiNetwork = network; // this is never reached
}
}
ConnectivityManager.BindProcessToNetwork( currentWifiNetwork );
Is there not a distinct Network object for all the phones currently in use WiFi, cellular, etc... networks?
This blog got me close: https://android-developers.googleblog.com/2016/07/connecting-your-app-to-wi-fi-device.html.
A binding socket method would work too (except the wifi network isn't an available network until the use network without internet box is checked). I just need to the App to use urls that are on port 8080 via the wifi.
I want to avoid having to manually telling Android to "use the network with no internet".
Cheers
Update
When I run this, there are only two Networks returned by ConnectivityManager.GetAllNetworks(), and looking at them in the debugger, one is the Cellular network with internet and mms, and the other is another Cellular network without internet and mms. So no ConnectivityManager.GetAllNetworks() doesn't get the wifi network as it appears android won't even add the wifi network unless it has internet! If the phones data is disabled Android will switch and use the internet-less wifi for all traffic (without having to check use the network anyways box).So their must be a way to get the WiFi network bound to the app! or...
How does one programmatically check the use network anyways box!?
I have not seen a solution to this. Just a bunch of open questions all over the web. At this rate I might just use dnsmasq on the iot device and a spoofing web server to make android think it has internet.
I also see that API 29 has NetworkBuilder and that you can specify a request for a WiFi network without internet capabilities...but I need lower API support.
Update:
Android now supports requesting local only wifi networks (networks without the NetworkCapabilities#NET_CAPABILITY_INTERNET capability) check out :
https://developer.android.com/reference/android/net/wifi/WifiNetworkSpecifier.Builder
Original Answer:
This is the solution that I came up with (for Api 28 ). It prioritizes WiFi over 4G/5G (Data) regardless of internet capability via a NetworkRequest, and then allows for both internet over 4G/5G (Data) and the app to use its local WiFi services:
public static WifiManager WifiManager { get; } = (WifiManager)Android.App.Application.Context.GetSystemService(Context.WifiService);
public static ConnectivityManager ConnectivityManager { get; set; } = (ConnectivityManager)Android.App.Application.Context.GetSystemService(Context.ConnectivityService);
public bool ConnectToWifi(string ssid, string password, bool previouslyConnected = true)
{
if (!WifiManager.IsWifiEnabled)
WifiManager.SetWifiEnabled(true); //turn on wifi if not on
var formattedSsid = $"\"{ssid}\"";
var formattedPassword = $"\"{password}\"";
var wifiConfig = new WifiConfiguration
{
Ssid = formattedSsid,
PreSharedKey = formattedPassword,
Priority = 0
};
_NetworkId = WifiManager.AddNetwork(wifiConfig);
WifiManager.Disconnect();
bool enableNetwork = WifiManager.EnableNetwork(_NetworkId, true);
NetworkRequest.Builder builder = new NetworkRequest.Builder(); //request that WiFi be prioritized over the 4G internet capable network.
builder.AddTransportType(TransportType.Wifi);
ConnectivityManager.RequestNetwork(builder.Build(), new BindNetworkCallBack ());
return enableNetwork;
}
This call back then binds the appropriate WIFI network to the app(process)! Allowing for the user to both simultaneously use the app with the local server over WIFI, and other apps that still require internet, as Android OS can allow other processes to access the internet via the 4G/5G data connection!
public class BindNetworkCallBack : ConnectivityManager.NetworkCallback
{
public override void OnAvailable(Network network)
{
if (WifiManager.ConnectionInfo.BSSID == NetworkBSSID) /*
The only way on Android (API 28+) to check if the acquired network is
the one you want is to use the BSSID (MAC address) of the network.
You can omit the if statement if you want to presume the acquired network is correct/
cannot know the MAC address...
*/
{
try
{
ConnectivityManager.BindProcessToNetwork(network);
}
catch (Exception ex)
{
Debug.WriteLine(#"\tERROR Unable to Bind process to network {0}", ex.Message);
}
}
}
}
"bindProcessToNetwork Binds the current process to network. All Sockets created in the future (and not explicitly bound via a bound SocketFactory from Network.getSocketFactory()) will be bound to network. All host name resolutions will be limited to network as well." - Android Docs
I wrote an app that is triggering a Sony qx smartphone attachable camera over wifi. However I need to transfer the images off the phone over another local network in real time. Since the wifi card is being used for qx connection I need to be able to use ethernet over usb for transferring images off the phone. Http requests will be used to trigger the camera and send the images off the phone.
Is it possible in one android app on a phone with two network interfaces setup to specify for certain http requests to use one network interface and for others to use another network interface ? Does this need to be done through routing tables, not java?
The phone I'm using is a rooted nexus 6p.
Update:
Currently, I was able to get an Ethernet adapter working with the device (Nexus 6P). The device is connected to a local network over Ethernet. When the Wi-Fi interface is off, I can ping all devices on the local network the device is connected to over Ethernet. However, I am unable to access the web servers (Not using DNS) of any of the devices on that network (which I know they are running), i.e. Http via a browser app. The nexus 6p is connected to the network over Ethernet via a Ubiquiti Station. This seems to be a routing issue.
I can tether(usb interface) and use Wi-Fi in one app, so that leads me to believe it is possible to use Ethernet and Wi-Fi.
Update2:
After more testing, it seems to be that it is a permissions issue. Since when I ping the network the device is connected to over Ethernet without first running su in the terminal the network doesn't exist. However, when I run su then ping, I can ping the network. Thus it seems my app needs to get superuser permission before accessing Ethernet. I've granted it superuser access, but nothing has changed. I read that simply running su isn't enough from one of the comments in this post. This is because su just spawns a root shell that dies. This also explains why I couldn't access any of the web servers on this network via a browser app. Is it possible to grant my app access to the Ethernet interface when making HTTP calls like give HttpURLConnection root access, if that makes any sense (running su doesn't work)? There seems to definitely be a solution since HttpURLConnection can make calls over the USB tethering interface (Nexus 6P calls it rndis0) fine.
Update 3:
I found online here , that I can make my app a System app (thought this might grant the app eth0 access). I just moved my app to /system/app and then rebooted. However, this didn't seem to give the app anymore privileges (thus not solving the problem) , or there is something else required to make the app system than just copying it to /system/app.
Update 4:
So I was able to get Ethernet working on every app without root permissions! It seemed to be that it only works over DHCP and does not like static connections, which I was using. It works with Wi-Fi enabled, however, I cannot contact any of the devices on the Wi-Fi network when Ethernet is enabled. Is there a way around this? Does it have to do with setting two default gateways?
Since you were programming in Nexus 6P, you can try to use the new API added in ConnectivityManager to select the ethernet as your preferred network connection for your process.
Since I can't build the similar environment like yours, I am not sure if it works. It's just a suggested solution, totally not tested and verified.
ConnectivityManager connectivityManager = (ConnectivityManager) getSystemService(CONNECTIVITY_SERVICE);
Network etherNetwork = null;
for (Network network : connectivityManager.getAllNetworks()) {
NetworkInfo networkInfo = connectivityManager.getNetworkInfo(network);
if (networkInfo.getType() == ConnectivityManager.TYPE_ETHERNET) {
etherNetwork = network;
}
}
Network boundNetwork = connectivityManager.getBoundNetworkForProcess();
if (boundNetwork != null) {
NetworkInfo boundNetworkInfo = connectivityManager.getNetworkInfo(boundNetwork);
if (boundNetworkInfo.getType() != ConnectivityManager.TYPE_ETHERNET) {
if (etherNetwork != null) {
connectivityManager.bindProcessToNetwork(etherNetwork);
}
}
}
Just to give a little more explanation on how this finally got solved.
Utilizing #alijandro's answer I was able to switch back and forth between Ethernet and Wi-Fi in one app. For some reason for the Ethernet to work it required the network gateway to supply DHCP address, not static. Then since the bindProcessToNetwork, used in #alijandro's answer is per-process, I decided to split communications with the QX camera into a Service that runs in a separate Process. The main Application (another process) would post images over Ethernet to a local network. I was successfully able to contact the devices on the local network via HTTP over Ethernet while simultaneously triggering the QX over Wi-Fi. Currently, I used Messenger to communicate using IPC to tell the QX triggering Service what methods to call.
Most of android tv boxes can use wifi and ethernet together. In my device, i can enable ethernet from this path ---
Settings -> More ... > Ethernet ---
But your device wont have a menu like that as i understand. So you should make an app to do that. This application needs to access some system specific resources so your device needs to be rooted or application needs to signed with system signature.
Also this topic can help you link
There is an easy way to do this that will answer the OP's original question about how to do this with a single application (not two separate app processes) using ConnectivityManager.requestNetwork().
The docs for ConnectivityManager.requestNetwork() allude to this:
... For example, an application could use this method to obtain a
connected cellular network even if the device currently has a data
connection over Ethernet. This may cause the cellular radio to consume
additional power. Or, an application could inform the system that it
wants a network supporting sending MMSes and have the system let it
know about the currently best MMS-supporting network through the
provided NetworkCallback. ...
For OP's scenario of using Wi-Fi for some traffic and ethernet for other traffic one only needs to call ConnectivityManager.requestNetwork() twice with two separate requests. One for TRANSPORT_WIFI and one for TRANSPORT_ETHERNET. The operative item here is we need a way to uniquely identify these networks. For OP's scenario, we can use transport type.
final NetworkRequest requestForWifi =
new NetworkRequest.Builder()
.addTransportType(NetworkCapabilities.TRANSPORT_WIFI)
.build();
final NetworkRequest requestForEthernet =
new NetworkRequest.Builder()
.addTransportType(NetworkCapabilities.TRANSPORT_ETHERNET)
.build();
final ConnectivityManager connectivityManager = (ConnectivityManager)
context.getSystemService(Context.CONNECTIVITY_SERVICE);
final NetworkCallback networkCallbackWifi = new NetworkCallback() {
#Override
void onAvailable(Network network) {
// Triggers when this network is available so you can bind to it.
}
#Override
void onLost(Network network) {
// Triggers when this network is lost.
}
};
final NetworkCallback networkCallbackEthernet = new NetworkCallback() {
#Override
void onAvailable(Network network) {
// Triggers when this network is available so you can bind to it.
}
#Override
void onLost(Network network) {
// Triggers when this network is lost.
}
};
connectivityManager.requestNetwork(requestForWifi, networkCallbackWifi);
connectivityManager.requestNetwork(requestForEthernet, networkCallbackEthernet);
Then, once the callbacks trigger, you can then in the pertinent code (e.g. OP's code for transferring images), listen for onAvailable(Network network) and use the provided Network with Network.OpenConnection() to connect to an HTTP server using that network.
This would allow you to connect to two separate Networks from the same application.
I'm encountering this issue on my Samsung devices running KitKat. It doesn't seem to affect my Nexus devices running Lollipop.
I use this code to switch between Wi-Fi networks:
private void switchToNetwork(String ssid) {
WifiConfiguration configuration = new WifiConfiguration();
configuration.SSID = String.format(Locale.US, "\"%s\"", ssid);
// ... other configuration changes such as password and cipher
manager.disconnect();
manager.enableNetwork(params[0].configuration.networkId, true);
manager.reconnect();
}
However, I'm noticing that if I was previously connected to a Wi-Fi network before running this code, these Samsung devices change the state of that previous network to "Turned off." This happens because the second parameter in my call to enableNetwork, disableOthers, was set to true.
The "turned off" state means that the network will not automatically be switched-to if the other network turns off. For my purposes, I'm manually switching back to the network, but there are certain cases (e.g. an app crash) where it might be desirable for the network to be switched automatically.
When I change disableOthers to false, however, it doesn't always change me to the SSID I asked for in switchToNetwork(). It'll often stay on the previous SSID.
So: How do I guarantee that I'm switching to a new network without disabling the previous network?
One way of doing it is by caching the current Network ID.
You can store the currently connected network ID using getConnectionInfo.getNetworkId API and store it temporarily.
Now connect to your desired network and when you are done connect back to previous network using ID you stored before.
Is there a way to access Android's broadcast that the WiFi connection is currently a captive portal (requires web login)? Android seems to do have this built in. If not a broadcast receiver, is there a way to check for the result of the captive portal check? I believe it's using this class, which is hidden from the API:
http://grepcode.com/file/repository.grepcode.com/java/ext/com.google.android/android/5.L_preview/android/net/CaptivePortalTracker.java
Prior to 4.2, it was probably using:
http://grepcode.com/file/repository.grepcode.com/java/ext/com.google.android/android/4.1.2_r1/android/net/wifi/WifiWatchdogStateMachine.java
Background:
I had been using my own method to detect whether WiFi likely required a login. I would wait for a WiFi connected state, then ping a site and make sure there was a response. This seemed to work great in most cases. Another strategy is to do a HttpRequest and check for a redirect or the response body you receive back, similar to Android's strategy in the classes listed above.
However, new to Lollipop is that the mobile data connection is used when WiFi does not have connectivity. This means my ping method will still return results, and that a redirect would not happen, as the request would be routed over the mobile data.
Is there a way to get Android's current status of a WiFi captive portal? If not, can we make sure a request goes over WiFi even when there's no connectivity as seen by Android?
You'd have to use the new ConnectivityManager.setProcessDefaultNetwork API to force your app to communicate over the captive portal. See https://github.com/pawitp/muwifi-autologin/commit/f045fe36f1fd98a106ea652e2d56f7ddfc871760 for an example.
Complete code added:
final ConnectivityManager cm = (ConnectivityManager) getSystemService(Context.CONNECTIVITY_SERVICE);
for (Network net : cm.getAllNetworks()) {
if (cm.getNetworkInfo(net).getType() == ConnectivityManager.TYPE_WIFI) {
Utils.logDebug(TAG, "Seting process network to " + net);
/*Since API 23 ConnectivityManager.setProcessDefaultNetwork(net);
is deprecated, use: */
cm.bindProcessToNetwork(net);
}
}
As of Android 4.1, your device can detect if it's connected to a mobile hotspot (given that the mobile hotspot is also running Android 4.1 or higher). Also, you have the option to flag networks as mobile hotspots (under Settings / Data Usage / Overflow menu / Mobile Hotspots).
But how do I detect this as a -user- I meant developer? It's not stored in the WifiConfiguration, so where is it?
Some context: I want to build a simple tool for Android that checks if you are connected to a network that you or Android has flagged as a mobile hotspot. If so, it will check if no other (non-hotspot) networks are available. If so, it should connect to these other networks since those should be much faster and have no data cap. Why? Because my phones and tablets connect to (mobile) hotspots quite often, even when a better network is available.
Here is some pseudo code of what I'm looking for:
// Check if android has detected mobile hotspot
WifiManager wifiMgr = getSystemService(Context.WIFI_SERVICE);
WifiInfo wifiInfo = wifiMgr .getConnectionInfo();
boolean isMobileHotspot = wifiInfo.isMobileHotspot;
UPDATE Jul 3rd 2014
Okay so Matiash' answer is good but ConnectivityManager.isActiveNetworkMetered() will only return the value for the current network. I do need that, so it helped me along, but it bring me to the next part in my tool/app:
IF the device is connected to a mobile hotspot (or a 'metered network' as Android calls it) I want to check if any of the nearby access points is a better option. So I need to know whether any of the known AP's (WifiManager.getConfiguredNetworks()) is also flagged as such before I connect to it...
I have a List<ScanResult> and a List<WifiConfiguration>, looks like neither of them has this information.
Which bring me back to my initial question: Is there a way to retrieve the Mobile Hotspots (as configured by Android and/or user) under Data Usage? And this time I mean ALL of them.
UPDATE Jul 7th 2014
I've posted a feature request in the AOSP Issue Tracker for access (readonly) to the NetworkPolicyManager. Plz vote on it here: https://code.google.com/p/android/issues/detail?id=73206&thanks=73206&ts=1404719243
You can access this information by calling ConnectivityManager.isActiveNetworkMetered().
This will return whether the active connection is a hotspot (as defined in Data Usage -> Mobile Hotspots).
About the second part, I'm sorry but I don't think that's possible. The flag is not public, and even if you get the object that could be used to retrieve it (android.net.NetworkPolicyManager) by reflection:
Object npm = Class.forName("android.net.NetworkPolicyManager").getDeclaredMethod("from", Context.class).invoke(null, this);
Object policies = npm.getClass().getDeclaredMethod("getNetworkPolicies").invoke(npm);
calling getNetworkPolicies() requires the MANAGE_NETWORK_POLICY permission, which cannot be obtained by non-system apps, because it has a "signature" protection level.
I hope to be proved incorrect though. :) Maybe looking at the source code of the Android activity that manages this information (https://github.com/android/platform_packages_apps_settings/blob/master/src/com/android/settings/net/DataUsageMeteredSettings.java), in particular the buildWifiPref() method, will provide some clue.
I do not know if what you want is possible but you can check whether your device is connected to a network by checking the ip.
You can use the tool below to see if you has ip, and shalt know if he is connected to a network or not.
public static Boolean check_connection(final Context _context)
{
boolean connected;
ConnectivityManager conectivtyManager = (ConnectivityManager) _context
.getSystemService(Context.CONNECTIVITY_SERVICE);
if (conectivtyManager.getActiveNetworkInfo() != null
&& conectivtyManager.getActiveNetworkInfo().isAvailable()
&& conectivtyManager.getActiveNetworkInfo().isConnected())
{
connected = true;
} else
{
connected = false;
}
return connected;
}
//Check if hotspot tethering is enabled
try {
ConnectivityManager connectivityManager = (ConnectivityManager)getSystemService(Context.CONNECTIVITY_SERVICE);
boolean isMobileData = connectivityManager.isActiveNetworkMetered();
if(isMobileData) {
List<NetworkInterface> interfaces = Collections.list(NetworkInterface.getNetworkInterfaces());
for (NetworkInterface networkInterface : interfaces) {
if (networkInterface.getName().equals("ap0")) {
//Tethering is enabled
SendHotspotEnabledHandler sendHotspotEnabledHandler = new SendHotspotEnabledHandler(new WeakReference<Context>(SendInstalledAppsService.this));
sendHotspotEnabledHandler.execute();
break;
}
}
}
} catch (SocketException e) {
}