[cifs-protocol] detecting failed DCs in the KCC (MS-ADTS 6.2.2.3.4.4)
Douglas Bagnall
douglas.bagnall at catalyst.net.nz
Wed May 13 16:43:34 MDT 2015
MS-ADTS 6.2.2.3.4.4 (v20140502, page 569) defines BridgeheadDCFailed
thus:
/***** BridgeheadDCFailed *****/
/* Determine whether a given DC is known to be in a failed state.
* IN: objectGUID - objectGUID of the DC's nTDSDSA object.
* IN: detectFailedDCs - TRUE if and only failed DC detection is
* enabled.
* RETURNS: TRUE if and only if the DC should be considered to be in a
* failed state.
*/
BridgeheadDCFailed(IN GUID objectGUID, IN bool detectFailedDCs) : bool
{
IF bit NTDSSETTINGS_OPT_IS_TOPL_DETECT_STALE_DISABLED is set in
the options attribute of the site settings object for the local
DC's site
RETURN FALSE
ELSEIF a tuple z exists in the kCCFailedLinks or
kCCFailedConnections variables such that z.UUIDDsa =
objectGUID, z.FailureCount > 1, and the current time -
z.TimeFirstFailure > 2 hours
RETURN TRUE
ELSE
RETURN detectFailedDCs
ENDIF
The way the detectFailedDCs parameter is used in the pseudo-code seems
at odds with its description in the comments (which is consistent with
comments elsewhere in the stack). The pseudo-code is using
detectFailedDCs as a default value in the case a failure is not
detected, not as a switch turning detection on or off. As written, you
can only actually detect a failed DC if detectFailedDCs is *false* --
when it is true, the return value merely reflects the
NTDSSETTINGS_OPT_IS_TOPL_DETECT_STALE_DISABLED bit.
Shouldn't it look more like this:
IF detectFailedDCs is FALSE or
bit NTDSSETTINGS_OPT_IS_TOPL_DETECT_STALE_DISABLED is set [...]
RETURN FALSE
ELSEIF a tuple z exists [...]
RETURN TRUE
ELSE
RETURN FALSE
ENDIF
or is it the comments that need fixing?
cheers,
Douglas Bagnall
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