Develop Reference

Flutter/Dart UDP multicast send from iOS not receiving on Android

With this setup, I've been able to get two android phones to send and receive UDP broadcasts. I can also use this setup to send a UDP broadcast from a physical Android device to an iPhone.
However, my problem is that it doesn't seem to work the other way around. The send function is ran on the iPhone, and the receive function is being run on the Android phone. The Android phone never gets the broadcast. It seems like something is wrong with the iPhone's sending function. Here's the setup:
The Android side that has worked for me before:
const port = 37069;
const address = '224.0.0.1';
void receive() async {
final socket = await RawDatagramSocket.bind(address, port);
socket.multicastHops = 1;
socket.broadcastEnabled = true;
socket.writeEventsEnabled = true;
socket.listen((RawSocketEvent event) {
print("still listening...");
final packet = socket.receive();
print("The packet was $packet");
print("It came from ${packet?.address}");
});
}
and this is the iPhone side, that seems to be the problem. I'm not getting errors, so I'm wondering if there are any permissions in the Info.plist file that need to be added?
void broadcast() {
// for the iphone
RawDatagramSocket.bind(address, port).then((RawDatagramSocket socket) {
socket.multicastLoopback = false;
socket.broadcastEnabled = true;
socket.readEventsEnabled = true;
for (int i = 0; i < 150; i++) {
socket.send("Sent #$i".codeUnits, InternetAddress(address), port);
print("sent $i");
}
socket.close();
});
}
I've tested this same setup in my project, and it has worked in the following situations:
Android -> Android
Android -> iOS
but, iOS -> Android doesn't work. When I run the app, I can see that the iPhone is indeed sending the data, but the Android isn't receiving anything. Is the Android side the problem? What am I doing wrong?

I ended up using a package called Bonsoir to achieve what I wanted to.
It lets you broadcast and receive network services, and I'm pretty sure its the same underlying technology as household programs like Airplay and Google Casting. It's also very reliable and simple to use.
To send a certain string, I passed in a string argument in the form of a dictionary into the attributes attribute within the BonsoirService class.
The package can be found here.

How to connect to Bluetooth SPP using dot42?

After reading the dot42 comments and trolling Java examples I managed to setup a Bluetooth connection but fail to open the connection. I cannot determine the problem. I followed the docs step by step.
My target device is a HTC Explorer running on 2.3 Gingerbread. Here is my code.
//Target 2.3 (Gingerbread)
[assembly: Application("dot42Application1")]
[assembly: UsesPermission(Android.Manifest.Permission.BLUETOOTH)]
[assembly: UsesPermission(Android.Manifest.Permission.BLUETOOTH_ADMIN)]
namespace dot42Application1
{
[Activity]
public class MainActivity : Activity
{
private TextView txStatus;
protected override void OnCreate(Bundle savedInstance)
{
base.OnCreate(savedInstance);
SetContentView(R.Layouts.MainLayout);
// Find UI controls
txStatus = FindViewById<TextView>(R.Ids.txStatus);
Intent enableIntent = new Intent(BluetoothAdapter.ACTION_REQUEST_ENABLE);
var bt = BluetoothAdapter.GetDefaultAdapter();
if (bt != null) //If device has not Bluetooth this will be null
{
if (bt.IsEnabled()) //Is Bluetooth device enabled?
{
var BT_My_Addr = bt.Address; //Get the devices MAC
var BT_Bonded = bt.GetBondedDevices().ToList(); //Get a list of bonded devices- I bonded to a BT2TTL Board earlier.
txStatus.Text = BT_My_Addr + System.Environment.NewLine; //Shows my MAC on screen.
string BT_Remote_Address = string.Empty;
foreach (var BTDevice in BT_Bonded) //Just searchging for string in bonded list
{
if (BTDevice.Name.Contains("linvor"))
{
BT_Remote_Address = BTDevice.Address;
}
}
//Gets remote device
var BT_Remote_Device = bt.GetRemoteDevice(BT_Remote_Address);
//Create a RFCOMM Socket to remote device using popular UUID ofr BT Serial boards
var BTsocket = BT_Remote_Device.CreateInsecureRfcommSocketToServiceRecord(Java.Util.UUID.FromString("00001101-0000-1000-8000-00805F9B34FB"));
//Call anyway to make sure there is no discvoerry in the backgorund. It slows stuff down.
bt.CancelDiscovery();
//Exception here? Dont know why :(
BTsocket.Connect();
//Suppsoed to dump 0 to 99999 to my listening serial device but I never get this far.
var BT_Out = BTsocket.GetOutputStream();
for (int i = 0; i < 99999; i++)
{
BT_Out.Write(Encoding.ASCII.GetBytes(i.ToString()));
}
}
else
{
txStatus.Text = "Bluetooth is disabled :(";
}
}
}
}
And this is what it shows after the socket creation
and the error...
What am I doing wrong? :(

I seem to have solved the problem by analysing various code snippets on the internet. I think the problem was trying to do everything in the OnCreate method. The steps I followed are the following:
Created a button on the main view (MainActivity.xml) and attached a onClick method.
Moved all the code OUT of the OnCreate method. (I think this allows the application to fully initialise.) Created an event handler for the button with two methods.
The two methods are the same as the code I posted in my original question. Just they are separated out and called when the user clicks the button.
findBT() Gets the default adapter. Checks if Bluetooth is enabled if not does the intent filter. Or if it is it will cycle through the bonded list and match a device name and store the BluetoohDevice in a variable. This is another thing that is different from my code. I do not use GetRemoteDevice I just assign the device from the BondedList to my global variable.
openBT() creates the RFCOMM socket (this did not work with unsecure - it threw an exception but using the secure method worked!)
You have to pair to the remote device using the Androids Bluetooth control panel. This code will not scan or connect to devices that are not paired. It will just throw null exceptions.
Also I left the target SDK 2.3.x but I am using the 4.x API.
-Disclosure. I am not a seasoned Android developer and just learning about the life cycle of Java applications in the Android context. I hope this can help other C# developers trying to do the same.

getUidRxBytes() and getUidTxBytes() always return 0 in Android 4.3

I feel like I am on crazy pills right now. A specific part of my application has been working just fine for several days, and today it just stopped working and I can not figure out why. This part of my code used to output the total data since boot that each specific app has sent and received. Now, the values always show up as 0.
A couple things that may or may not be affecting this:
1.) My Nexus 4 was just updated to Android 4.3 today, but I doubt this is an issue because this worked just fine right after I updated.
2.) With the Android API 18 update, some methods from the Traffic Stats API are now deprecated, but these are methods I am not even using, so this should have no effect.
http://developer.android.com/reference/android/net/TrafficStats.html
All help is greatly appreciated.
PackageManager packageManager=this.getPackageManager();
List<ApplicationInfo> appList=packageManager.getInstalledApplications(0);
for (ApplicationInfo appInfo : appList) {
String appLabel = (String) packageManager.getApplicationLabel(appInfo);
int uid = appInfo.uid;
Log.d("data", String.valueOf(TrafficStats.getUidRxBytes(uid) + TrafficStats.getUidTxBytes(uid)));
Update[January 23, 2014]: Testing the getUidRxBytes() and getUidTxBytes() on my Nexus 4 running Android 4.4.2 shows that the values are no longer 0, but are reporting the correct statistics.

I have reported the issue to the AOSP issue tracker: here
I have also created an alternate solution to the problem which I have pasted below:
private Long getTotalBytesManual(int localUid){
File dir = new File("/proc/uid_stat/");
String[] children = dir.list();
if(!Arrays.asList(children).contains(String.valueOf(localUid))){
return 0L;
}
File uidFileDir = new File("/proc/uid_stat/"+String.valueOf(localUid));
File uidActualFileReceived = new File(uidFileDir,"tcp_rcv");
File uidActualFileSent = new File(uidFileDir,"tcp_snd");
String textReceived = "0";
String textSent = "0";
try {
BufferedReader brReceived = new BufferedReader(new FileReader(uidActualFileReceived));
BufferedReader brSent = new BufferedReader(new FileReader(uidActualFileSent));
String receivedLine;
String sentLine;
if ((receivedLine = brReceived.readLine()) != null) {
textReceived = receivedLine;
}
if ((sentLine = brSent.readLine()) != null) {
textSent = sentLine;
}
}
catch (IOException e) {
}
return Long.valueOf(textReceived).longValue() + Long.valueOf(textReceived).longValue();
}

The TrafficStats class get the information about network traffic from the /proc/uid_stat/<uid> directory. This contains information about the tcp, udp bytes and packets sent and received. If the files are not present the TrafficStats class can't get the network stats. You can check if the files are present, If not you are out of luck and should look for other way.
If the files are present you can try to read it yourself.
Also the getUidTxBytes() and getUIDRxBytes() report only the TCP traffic and miss UDP traffic. So if your app is doing lots of UDP traffic (like voip) then you'll not get any info.
There is already a bug filed for this : https://code.google.com/p/android/issues/detail?id=32410

I have done some detailed research about this, and to clarify some details, since Android 4.3 the TrafficStats API has changed in the way it extracts details from the device.
Prior to Android 4.3 the UID traffic stats were available for TCP and UDP and included API for bytes and packets & sent and received. That data was extracted from the /proc/uid_stat/[pid]/* files.
In Android 4.3, the developers has decided to switch to a better and more safe API, using the xt_qtaguid UID statistics, which is part of the netfilter kernel module in Linux.
This API (procfs) allows access based on process UID, and this is why when you try to access to TrafficStats API in Android=>4.3 you will get zero information for not-own UID.
btw, the commit that caused the issue is the following:
https://github.com/android/platform_frameworks_base/commit/92be93a94edafb5906e8bc48e6fee9dd07f5049e
*Improve TrafficStats UID APIs.
Deprecate transport layer statistics, leaving only the summarized
network layer statistics.
Improve documentation to be clear about layers where measurements
occur, and their behavior since boot. Under the hood, move to using
xt_qtaguid UID statistics.
Bug: 6818637, 7013662
Change-Id: I9f26992e5fcdebd88c671e5765bd91229e7b0016*

How to detect a mobile device manufacturer and model programmatically in Android?

I want to find device specification of a mobile phone for examples, the device manufacturer, model no ( and may be types of sensors in the device, wifi chipset etc..). I want to get the device manufacture/model number (eg. Samsung GT-I9100 i.e Galaxy S2) programmatically. The manufacture/model number is also used in Google Play when installing an app. I want to use this information to make some configuration changes in my hardware dependent app (for eg. power measurement).

You can get as below:
String deviceName = android.os.Build.MODEL;
String deviceMan = android.os.Build.MANUFACTURER;
For more other device details, Please refer this document: android.os.Build

I just wanna elaborate on how to use the built in Attribute for the future visitors. You can use this method in identifying a Kindle Device(s)
public static boolean isKindle(){
final String AMAZON = "Amazon";
final String KINDLE_FIRE = "Kindle Fire";
return (Build.MANUFACTURER.equals(AMAZON) && Build.MODEL.equals(KINDLE_FIRE) ) || Build.MODEL.startsWith("KF");
}

String deviceName = android.os.Build.MODEL;
String deviceMan = android.os.Build.MANUFACTURER;
The original solution will work fine, however it will not detect a custom ROM (non OEM) in call cases. You may want to also evaluate the android.os.Build.PRODUCT string or other strings from the Build class.
String build = android.os.Build.PRODUCT;

How do I get the UUID of a bluetooth device?

I need to know UUID on API 8 (2.2) or possibly 2.3.3.
As I understand the documentation, this should be allowed:
phoneDevice = blueAdapter.getRemoteDevice(phoneAddress);
ParcelUuid[] phoneUuids = phoneDevice.getUuids(); // Won't compile
Eclipse gives me:
"The method getUuids() is undefined for the type BluetoothDevice."
But see:
http://developer.android.com/reference/android/bluetooth/BluetoothDevice.html#getUuids()
Also, I would like to know how the UUIDs are "parceled" inside the ParcelUuid[]. In case I ever manage to get there, how do I retrieve a UUID from a parcelUuid[]? Documentation for Android bluetooth seems to be very poor, in my opinion.
What a joke!
Now I try to get it from the intent, but this too gives: *"EXTRA_UUID cannot be resolved or is not a field"*:
intent.getParcelableExtra(BluetoothDevice.EXTRA_UUID);

You have to use reflection to use the getUuids() and fetchUuidsWithSdp() on android version < 3. So, try the code:
Method method = phoneDevice.getClass().getMethod("getUuids", null);
ParcelUuid[] phoneUuids = (ParcelUuid[]) method.invoke(phoneDevice, null);

//this will support from API level 15 and above.
Broadcast Action: This intent is used to broadcast the UUID wrapped as a ParcelUuid of the remote device after it has been fetched. This intent is sent only when the UUIDs of the remote device are requested to be fetched using Service Discovery Protocol
Always contains the extra field EXTRA_DEVICE
Always contains the extra field EXTRA_UUID
Requires BLUETOOTH to receive.
Constant Value: "android.bluetooth.device.action.UUID"
//no way to degrade its hardware related. there is no supporting jar also. http://developer.android.com/sdk/compatibility-library.html

Unfortunately, I don't think there is any good way to get the UUID's supported by a BluetoothDevice with API level < 15. I guess that's why they added the new functions in API 15.
Note, from the docs for BluetoothClass
BluetoothClass is useful as a hint to roughly describe a device (for
example to show an icon in the UI), but does not reliably describe
which Bluetooth profiles or services are actually supported by a
device. Accurate service discovery is done through SDP requests, which
are automatically performed when creating an RFCOMM socket with
createRfcommSocketToServiceRecord(UUID) and
listenUsingRfcommWithServiceRecord(String, UUID).
So, perhaps the device class could be used as a hint as to what services will be available until you perform one of the listed functions. Certainly it doesn't hurt to check the class since this won't require any additional bluetooth operations.
Note that the service class is also available (it is part of the device class) but this is just a general class, not a listing of specific services (like from SDP).

try BluetoothAdapter class
any question, read: http://developer.android.com/reference/android/bluetooth/BluetoothAdapter.html

In case you can not get UUID from getUuids() method. Please try the other way.
After scanned successfully, you should receive byte[] (scanRecord), so from this result, if you can recognize UUID format you can split step by step to get correct UUID as these codes.
P/s : Important thing, you should know UUID format to get from index correctly.
// Put item into hash map
// UUID from index 10 to 24 : 12233445566778899aabbccddeeff0
StringBuilder mSbUUID = new StringBuilder();
for (int i = 0; i < scanRecord.length; i++) {
// UUID
if (i >= 10 & i <= 24) {
if (Integer.toHexString(
scanRecord[i]).contains("ffffff")) {
mSbUUID.append(Integer.toHexString(scanRecord[i]).replace("ffffff", "") + "-");
} else {
mSbUUID.append(Integer.toHexString(scanRecord[i]) + "-");
}
}
}