DatagramChannel.receive() causes an IndexOutOfBoundsException

Question

First of akk, I know that there is an almost the same question here, but it has no answer. So I'm asking again.

In my Android app, I use a non-blocking UDP socket to do some broadcast job, so I choose DatagramChannel. As I ran the following code on Samsung GT-P7510(with Android 4.0.4), I get an IndexOutOfBoundsException which says the buffer is not long enough. But clearly I have already allocate large enough space. Does anyone knows the reason? Any help is appreciated.

Code causes exception:

ByteBuffer bytebuf = ByteBuffer.allocateDirect(1024);
bytebuf.clear();

try {
    // LINE causes the Exception!
    SocketAddress addr = socketDiscoverChannel.receive(bytebuf);
    if (addr != null) {
        bytebuf.flip();

        InetSocketAddress remoteAddr = (InetSocketAddress) addr;
        String remoteIP = remoteAddr.getAddress().getHostAddress();
        ......
        ......
} finally {
        ......
}

Log:

02-26 16:58:22.209: E/AndroidRuntime(4695): FATAL EXCEPTION: IntentService[DaemonListeningService]
02-26 16:58:22.209: E/AndroidRuntime(4695): java.lang.IndexOutOfBoundsException: length=36, offset=0, buffer size=0
02-26 16:58:22.209: E/AndroidRuntime(4695):     at java.net.DatagramPacket.setLengthOnly(DatagramPacket.java:234)
02-26 16:58:22.209: E/AndroidRuntime(4695):     at java.net.DatagramPacket.setLength(DatagramPacket.java:222)
02-26 16:58:22.209: E/AndroidRuntime(4695):     at libcore.io.IoBridge.postRecvfrom(IoBridge.java:528)
02-26 16:58:22.209: E/AndroidRuntime(4695):     at libcore.io.IoBridge.recvfrom(IoBridge.java:516)
02-26 16:58:22.209: E/AndroidRuntime(4695):     at java.nio.DatagramChannelImpl.receiveDirectImpl(DatagramChannelImpl. java:232)
02-26 16:58:22.209: E/AndroidRuntime(4695):     at java.nio.DatagramChannelImpl.receive(DatagramChannelImpl.java:185)
02-26 16:58:22.209: E/AndroidRuntime(4695):     at com.zisync.daemon.DaemonListeningService.startListening(    DaemonListeningService.java:261)
02-26 16:58:22.209: E/AndroidRuntime(4695):     at com.zisync.daemon.DaemonListeningService.onHandleIntent(    DaemonListeningService.java:98)
02-26 16:58:22.209: E/AndroidRuntime(4695):     at android.app.IntentService$ServiceHandler.handleMessage(IntentService.   java:65)
02-26 16:58:22.209: E/AndroidRuntime(4695):     at android.os.Handler.dispatchMessage(Handler.java:99)
02-26 16:58:22.209: E/AndroidRuntime(4695):     at android.os.Looper.loop(Looper.java:137)
02-26 16:58:22.209: E/AndroidRuntime(4695):     at android.os.HandlerThread.run(HandlerThread.java:60)

the `.flip()` is after the exception happens, actually it does not get excuted even once...BTW, the .flip() is quite what I want. — J Jiang, Feb 27 '14 at 09:09
@EJP seems so! I just post an answer but don't know if it is right. — J Jiang, Feb 27 '14 at 09:22

score 3 · Accepted Answer · answered Feb 27 '14 at 09:21

This is quite a disappointing question. After a few tries, I seem to know the reason.
It is a bug of some specific version of Android.
In fact, I'm not that sure, but I get some support here.

I ran exactly the same code on another Android device(Samsung GT-I9220 with Android 4.1.4), it just works fine.

And after I change the ByteBuffer.allocateDirect(1024) to ByteBuffer.allocate(1024)(without the direct), it works on the previous device which causes the exception. I really don't know the reason but this is the situation.

I'll leave this question open for some more time, just in case someone knows the reason or confirms if this is really a bug of Android(of some version).

DatagramChannel.receive() causes an IndexOutOfBoundsException

1 Answers1