I'm having a little trouble here, on one hand I have a server listening on port 23000 and on the other an Android App acting as the client. While connection seems to work in the Emulator (this is built for 2.3.3 by the way) using the typical 10.2....IP, when trying on a Samsung Galaxy Tab I keep on getting the famous:
"Address family not supported by protocol exception"
Eventually, code looks like this:
InetSocketAddress inetAddress;
//this is done to keep backward compatibility prior 2.0.4 release
if(host == null || host.equals("")) {
//check if defaultIp is also empty
if (defaultIPAddress == null || defaultIPAddress.equals(""))
throw new UnknownHostException();
//otherwise start listening on defaultIp
else
{
inetAddress = new InetSocketAddress(defaultIPAddress, port);
}
}
//start listening on host
else
{
inetAddress = new InetSocketAddress(host, port);
}
// open the socket channel
this.channel = SocketChannel.open(inetAddress);
this.channel.configureBlocking(false);
this.channel.socket().setTcpNoDelay(true);
It fails when trying to open the socket at
this.channel = SocketChannel.open(inetAddress);
Needless to say, I have the required permissions in my Manifest, as said previously, this is working fine in the Emulator.
Besides, this is no network issue, both machines are connected to a Wireless Wifi created using a router I have at hand, with no firewalls, proxys, completely open, to put it that way...
Any ideas?
Thanks!
Alex
If anybody lands on this question and is having the same issue, this was caused because I was trying to open the Socket in the same thread of the main Activity. Looks like this is a) not advisable and b) not permitter any longer. Thus, move your connecting code to a separate thread and you should be safe.
Related
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.
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!
I am developing a google glass/android application. It is a video streaming application that has a server/client setup where the phone/glasses is the server and hooks the pc up with the session description for playing the video. It works great on the android and everything runs fine but as soon as I try to test it on the google glass it throws an error at this line
sSocket = new ServerSocket(sPort);
The exception message says "EADDRINUSE" which I'm assuming means the port is already opened but I never opened it. Even if I had opened it and my program didn't close it I changed the port a couple of times and it still says it's in use.
Thanks
Tyler,
Google Glass, like android, consistently will have many of it's ports occupied by applications running in the background. When creating a socket for your server to listen on, you have two choices:
1) Have a predetermined list of ports you can choose to have your server listen on.
If you choose to do this, then you can simply have a datastructure (list, queue, heap [if you have some priority of which ports you would like to use], etc) which contain all of your ports, then you can simply traverse them until you find an open port.
This can be achieved in the following manner:
private ServerSocket allocatePort(List<Integer> myArray) throws IOException {
for (int individualPort : myArray) {
try {
return new ServerSocket(individualPort);
} catch (IOException io) {
continue; // An exception will be thrown if this port is currently in use. It's OK, let's try another port.
}
}
// When no ports are available, let's throw an exception stating we were unable to find an open port.
throw new IOException("we were unable to find an open port");
}
Then simply invoke this method within your as follows:
int[] arrayOfPorts = {5000, 5001, 5002, 8000, 8001, 8002, 8003};
List<Integer> myArray = new ArrayList<>();
myArray = IntStream.of(arrayOfPorts).boxed().collect(Collectors.toList());
ServerSocket sSocket = allocatePort(myArray);
2) If you don't mind which port to listen in on, you can use the constructor to pick any available port.
This can be achieved as follows:
ServerSocket sSocket = new ServerSocket(0);
You can read up more on ServerSocket's Javadocs. Notice under the parameter's subsection:
port - the port number, or 0 to use a port number that is automatically allocated.
Please let me know if you have any questions!
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.
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
*/
}