Odd InetAddress.isReachable() issue

Question

My work is developing software for network capable cameras for retail enviroments. One of the peices of software my team is developing is a webserver that retrieves various

Answer 1

Thanks everyone, but I never did figure out or pinpoint why this oddity was happening. Everything I checked for was not the cause, so this question can be closed.

In any case, I ended up working around it completely. Instead of using InetAddress, I just went native and built my own ICMP ping class instead, via JNA, invoking Windows libraries IPHLPAPI.DLL and WSOCK32.DLL. Here is what I used...

public interface InetAddr extends StdCallLibrary {
    InetAddr INSTANCE = (InetAddr) 
            Native.loadLibrary("wsock32.dll", InetAddr.class);

    ULONG inet_addr(String cp);                     //in_addr creator. Creates the in_addr C struct used below
}

public interface IcmpEcho extends StdCallLibrary {
    IcmpEcho INSTANCE = (IcmpEcho)
            Native.loadLibrary("iphlpapi.dll", IcmpEcho.class);

    int IcmpSendEcho(
            HANDLE IcmpHandle,                      //Handle to the ICMP
            ULONG DestinationAddress,               //Destination address, in the form of an in_addr C Struct defaulted to ULONG
            Pointer RequestData,                    //Pointer to the buffer where my Message to be sent is
            short RequestSize,                      //size of the above buffer. sizeof(Message)
            byte[] RequestOptions,                  //OPTIONAL!! Can set this to NULL
            Pointer ReplyBuffer,                    //Pointer to the buffer where the replied echo is written to
            int ReplySize,                          //size of the above buffer. Normally its set to the sizeof(ICMP_ECHO_REPLY), but arbitrarily set it to 256 bytes
            int Timeout);                           //time, as int, for timeout

    HANDLE IcmpCreateFile();                        //win32 ICMP Handle creator

    boolean IcmpCloseHandle(HANDLE IcmpHandle);     //win32 ICMP Handle destroyer
}

And then using those to create the following method...

public void SendReply(String ipAddress) {
    final IcmpEcho icmpecho = IcmpEcho.INSTANCE;
    final InetAddr inetAddr = InetAddr.INSTANCE;
    HANDLE icmpHandle = icmpecho.IcmpCreateFile();
    byte[] message = new String("thisIsMyMessage!".toCharArray()).getBytes();
    Memory messageData = new Memory(32);                    //In C/C++ this would be: void *messageData = (void*) malloc(message.length);
    messageData.write(0, message, 0, message.length);       //but ignored the length and set it to 32 bytes instead for now
    Pointer requestData = messageData;
    Pointer replyBuffer = new Memory(256);
    replyBuffer.clear(256);

    // HERE IS THE NATIVE CALL!!
    reply = icmpecho.IcmpSendEcho(icmpHandle, 
            inetAddr.inet_addr(ipAddress), 
            requestData, 
            (short) 32, 
            null, 
            replyBuffer, 
            256, 
            timeout);
    // NATIVE CALL DONE, CHECK REPLY!!

    icmpecho.IcmpCloseHandle(icmpHandle);
}

public boolean IsReachable () {
    return (reply > 0);
}