RFR 8024253: ThreadLocal random can use SecureRandom for the initial seed

[Chris Hegarty]

On some platforms, Windows, tunneling interfaces report a very "bad" mac 
address, e.g.  00-00-00-00-00-00-00-E0. I wonder if it is worth skipping 
all isVirtual() nifs?

-Chris.

On 16/09/2013 16:06, Peter Levart wrote:
> Hi Doug,
>
> This seems reasonable for majority of environments.
>
> Regards, Peter
>
> On 09/16/2013 04:50 PM, Doug Lea wrote:
>> On 09/16/2013 10:39 AM, Peter Levart wrote:
>>
>>> So perhaps the right strategy would be to get the hardware address of
>>> the 1st
>>> interface that has it, but don't bother to search more than N interfaces
>>
>> Where N==2 seems to be the best policy, since at most loopback is
>> legitimately null. Putting the suggestions together:
>>
>> private static long initialSeed() {
>> String pp = java.security.AccessController.doPrivileged(
>> new sun.security.action.GetPropertyAction(
>> "java.util.secureRandomSeed"));
>> if (pp != null && pp.equalsIgnoreCase("true")) {
>> byte[] seedBytes = java.security.SecureRandom.getSeed(8);
>> long s = (long)(seedBytes[0]) & 0xffL;
>> for (int i = 1; i < 8; ++i)
>> s = (s << 8) | ((long)(seedBytes[i]) & 0xffL);
>> return s;
>> }
>> long h = 0L;
>> try {
>> Enumeration<NetworkInterface> ifcs =
>> NetworkInterface.getNetworkInterfaces();
>> boolean retry = false; // retry once if getHardwareAddress is null
>> while (ifcs.hasMoreElements()) {
>> NetworkInterface ifc = ifcs.nextElement();
>> byte[] bs = ifc.getHardwareAddress();
>> if (bs != null) {
>> for (int i = 0; i < 8 && i < bs.length; ++i)
>> h = (h << 8) ^ bs[i];
>> break;
>> }
>> else if (!retry)
>> retry = true;
>> else
>> break;
>> }
>> } catch (Exception ignore) {
>> }
>> return (mix64(h ^ System.currentTimeMillis()) ^
>> mix64(System.nanoTime()));
>> }
>>
>>
>