wntUserSetDat and Logon Hours

Keywords: 	  wntUserSetDat  Logon Hours

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Question:

I'm trying to figure out how the logon hours attribute in the wntUserSetDat function works. It seems really funky, but I'm sure there's a logical explanation for how it works.

Example:

An account has all logon hours set to "deny" except Thursday, 12:00am to 5:00pm. When I get the "logon_hours" attribute using wntUserGetDat, I get:

000000000000000000000000C0FF7F000000000000

Converted to binary, I get (without the line breaks of course):

000000000000000000000000
000000000000000000000000
000000000000000000000000
000000000000000000000000
110000001111111101111111
000000000000000000000000
000000000000000000000000

Why are the 1s nonconsecutive? The logon hours are. I previously thought that it was a time zone matter, but there's no way to shift the bits around to make them contiguous. Help?

Answer:

Looks like a little-endian big endian disaster,

So take your binary representation...

000000000000000000000000
000000000000000000000000
000000000000000000000000
000000000000000000000000
110000001111111101111111
000000000000000000000000
000000000000000000000000

write each group of 8 in reverse order

000000000000000000000000
000000000000000000000000
000000000000000000000000
000000000000000000000000
000000111111111111111110
000000000000000000000000
000000000000000000000000

now they are contigious in this representation.

so umm that would be thurs
GMT time
6AM to 11 PM

so applying say a -6 bias
that would be
CST 12 PM to 5 PM

There is widespread confusion about what time 12AM is and what time 12 PM is

12:00 PM is midnight
12:00 AM is noon

12:01 AM is 1 sec past midnight
12:01 PM is 1 sec past noon

However there are widespread variances to this in practice, so often you will see 12AM as midnight and 12PM as noon, confusing *everything*.

There is no need to really reverse it, just check the byte in the opposite order.

To "visualize" this, write the bytes (as is) down in reverse order.