Search code examples
javaandroidudpandroid-permissions

java.net.BindException: bind failed: EACCES (Permission denied) when trying to create DatagramSocket for UDP connection

I'm trying to send UDP packets to a remote host in android studio. But this error showed up:

java.net.BindException: bind failed: EACCES (Permission denied)
    at libcore.io.IoBridge.bind(IoBridge.java:103)
    at java.net.PlainDatagramSocketImpl.bind0(PlainDatagramSocketImpl.java:104)
    at java.net.AbstractPlainDatagramSocketImpl.bind(AbstractPlainDatagramSocketImpl.java:110)
    at java.net.DatagramSocket.bind(DatagramSocket.java:412)
    at java.net.DatagramSocket.<init>(DatagramSocket.java:262)
    at java.net.DatagramSocket.<init>(DatagramSocket.java:319)
    at com.genean.dronecontroller.PacketSender.sendConnectionPacket(PacketSender.java:55)
    at com.genean.dronecontroller.PacketSender.access$000(PacketSender.java:20)
    at com.genean.dronecontroller.PacketSender$1.run(PacketSender.java:45)
    at java.lang.Thread.run(Thread.java:784)
 Caused by: android.system.ErrnoException: bind failed: EACCES (Permission denied)
    at libcore.io.Linux.bind(Native Method)
    at libcore.io.ForwardingOs.bind(ForwardingOs.java:60)
    at libcore.io.IoBridge.bind(IoBridge.java:99)
    at java.net.PlainDatagramSocketImpl.bind0(PlainDatagramSocketImpl.java:104) 
    at java.net.AbstractPlainDatagramSocketImpl.bind(AbstractPlainDatagramSocketImpl.java:110) 
    at java.net.DatagramSocket.bind(DatagramSocket.java:412) 
    at java.net.DatagramSocket.<init>(DatagramSocket.java:262) 
    at java.net.DatagramSocket.<init>(DatagramSocket.java:319) 
    at com.genean.dronecontroller.PacketSender.sendConnectionPacket(PacketSender.java:55) 
    at com.genean.dronecontroller.PacketSender.access$000(PacketSender.java:20) 
    at com.genean.dronecontroller.PacketSender$1.run(PacketSender.java:45) 
    at java.lang.Thread.run(Thread.java:784) 

Here's line 55 of PacketSender:

socket = new DatagramSocket(HOST_PORT);

I've tried adding android.permission.INTERNET and even checked for it with

if (ContextCompat.checkSelfPermission(activity, Manifest.permission.INTERNET)
            != PackageManager.PERMISSION_GRANTED) {
        Toast toast = Toast.makeText(activity.getApplicationContext(),
                activity.getString(R.string.no_internet_perms), Toast.LENGTH_LONG);
        toast.show();
    }

However it still gives me a permission error.

EDIT: suspect it might be the port im using which is 333.

Solution

  • Apparently, I realised that it is impossible to use a specific local port to establish the socket despite having android.permission.INTERNET. Either you get a permission error or the port has been occupied by another app. Hence, I fixed it by initiating my DatagramSocket without any parameters to allow Android to set an arbitrary port number instead.