Win2K redirector issues

NTFSD
1

Does anyone know if MS have now changed things so that network redirectors
registering themselves as file systems now cause a notification to be sent
out which can be picked up by IoRegisterFsRegistrationChange()? My filter
driver uses the normal NT 4 method of using a timer to wait for redirectors
coming online, whereupon it then attaches itself to them in order to filter
requests. However, I noticed that on Win2k, after a time of the system being
up on booting, it would eventually BSOD with an UNEXPECTED_KERNEL_MODE_TRAP
exception. This normally happened after about 10 or 12 minutes.

When I then commented out the code which actually attached to the redirector
when the timer callback found the device, the BSODs no longer happened. I
assumed that my filter would then be unable to filter network access, but to
my surprise, this was not the case.

Assuming that 2000 was already notifying my filter of the redirector via my
registration callback (and that by using the timer, my filter was attaching
to the device twice), I then added code to only attempt to attach to the
redirector if the redirector’s device object was not present in my filter’s
linked list of devices. This appeared to solve the problem, and the system
stayed up for a number of hours. But this afternoon I came to do more work,
and discovered that the machine had died. Stepping through the filer code
with SoftICE, I realised that the timer callback was, in fact, still
responsible for the filter attaching to the redirector.

I am now confused; how are redirectors now handled in Win2k, and how should
NT 4 code be rewritten to cope with this (assuming that compatibility with
both OSes it to be maintained)?

i.

Ivan Lewis-Coker
Software Developer
AppSense Technologies
Europa Way
Bird Hall Lane
Cheadle Heath
Stockport
SK3 0WY

Tel: +44 (0) 161 610 4200
Fax:+44 (0) 161 610 4242

email: xxxxx@appsense.net
www: http://www.appsense.net

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2

IoRegisterFsRegistrationChange is not called when new redirectors
register with the system in Windows 2000.

Neal Christiansen

-----Original Message-----
From: xxxxx@appsense.co.uk
[mailto:xxxxx@appsense.co.uk]
Sent: Saturday, April 15, 2000 5:32 AM
To: File Systems Developers
Subject: [ntfsd] Win2K redirector issues

Does anyone know if MS have now changed things so that network
redirectors
registering themselves as file systems now cause a notification to be
sent
out which can be picked up by IoRegisterFsRegistrationChange()? My
filter
driver uses the normal NT 4 method of using a timer to wait for
redirectors
coming online, whereupon it then attaches itself to them in order to
filter
requests. However, I noticed that on Win2k, after a time of the system
being
up on booting, it would eventually BSOD with an
UNEXPECTED_KERNEL_MODE_TRAP
exception. This normally happened after about 10 or 12 minutes.

When I then commented out the code which actually attached to the
redirector
when the timer callback found the device, the BSODs no longer happened.
I
assumed that my filter would then be unable to filter network access,
but to
my surprise, this was not the case.

Assuming that 2000 was already notifying my filter of the redirector via
my
registration callback (and that by using the timer, my filter was
attaching
to the device twice), I then added code to only attempt to attach to the
redirector if the redirector’s device object was not present in my
filter’s
linked list of devices. This appeared to solve the problem, and the
system
stayed up for a number of hours. But this afternoon I came to do more
work,
and discovered that the machine had died. Stepping through the filer
code
with SoftICE, I realised that the timer callback was, in fact, still
responsible for the filter attaching to the redirector.

I am now confused; how are redirectors now handled in Win2k, and how
should
NT 4 code be rewritten to cope with this (assuming that compatibility
with
both OSes it to be maintained)?

i.

Ivan Lewis-Coker
Software Developer
AppSense Technologies
Europa Way
Bird Hall Lane
Cheadle Heath
Stockport
SK3 0WY

Tel: +44 (0) 161 610 4200
Fax:+44 (0) 161 610 4242

email: xxxxx@appsense.net
www: http://www.appsense.net

CONFIDENTIAL
The contents of this email and any attachments may be
confidential. It is intended for the named recipient(s).
If you are not the named recipient please notify the sender
immediately and do not disclose the contents to any other
person or make any copies.

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3

may i know how did u used timers to wait for redirectors?

Ho Mun Chuen
@@ “Not everything that counts can be counted;
<” )~ and not everything that can be counted counts"
//\ … Albert Einstein
----- Original Message -----
From:
To: File Systems Developers
Sent: Saturday, April 15, 2000 8:31 PM
Subject: [ntfsd] Win2K redirector issues

Does anyone know if MS have now changed things so that network redirectors
registering themselves as file systems now cause a notification to be sent
out which can be picked up by IoRegisterFsRegistrationChange()? My filter
driver uses the normal NT 4 method of using a timer to wait for redirectors
coming online, whereupon it then attaches itself to them in order to filter
requests. However, I noticed that on Win2k, after a time of the system being
up on booting, it would eventually BSOD with an UNEXPECTED_KERNEL_MODE_TRAP
exception. This normally happened after about 10 or 12 minutes.

When I then commented out the code which actually attached to the redirector
when the timer callback found the device, the BSODs no longer happened. I
assumed that my filter would then be unable to filter network access, but to
my surprise, this was not the case.

Assuming that 2000 was already notifying my filter of the redirector via my
registration callback (and that by using the timer, my filter was attaching
to the device twice), I then added code to only attempt to attach to the
redirector if the redirector’s device object was not present in my filter’s
linked list of devices. This appeared to solve the problem, and the system
stayed up for a number of hours. But this afternoon I came to do more work,
and discovered that the machine had died. Stepping through the filer code
with SoftICE, I realised that the timer callback was, in fact, still
responsible for the filter attaching to the redirector.

I am now confused; how are redirectors now handled in Win2k, and how should
NT 4 code be rewritten to cope with this (assuming that compatibility with
both OSes it to be maintained)?

i.

Ivan Lewis-Coker
Software Developer
AppSense Technologies
Europa Way
Bird Hall Lane
Cheadle Heath
Stockport
SK3 0WY

Tel: +44 (0) 161 610 4200
Fax:+44 (0) 161 610 4242

email: xxxxx@appsense.net
www: http://www.appsense.net

CONFIDENTIAL
The contents of this email and any attachments may be
confidential. It is intended for the named recipient(s).
If you are not the named recipient please notify the sender
immediately and do not disclose the contents to any other
person or make any copies.

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4

it’s ok, i have solved it with a system thread waiting on a timer.

Ho Mun Chuen
@@ “Not everything that counts can be counted;
<” )~ and not everything that can be counted counts"
//\ … Albert Einstein
----- Original Message -----
From: Ho Mun Chuen
To: File Systems Developers
Sent: Thursday, May 04, 2000 5:43 PM
Subject: [ntfsd] Re: Win2K redirector issues

may i know how did u used timers to wait for redirectors?

Ho Mun Chuen
@@ “Not everything that counts can be counted;
<” )~ and not everything that can be counted counts"
//\ … Albert Einstein
----- Original Message -----
From:
To: File Systems Developers
Sent: Saturday, April 15, 2000 8:31 PM
Subject: [ntfsd] Win2K redirector issues

Does anyone know if MS have now changed things so that network redirectors
registering themselves as file systems now cause a notification to be sent
out which can be picked up by IoRegisterFsRegistrationChange()? My filter
driver uses the normal NT 4 method of using a timer to wait for redirectors
coming online, whereupon it then attaches itself to them in order to filter
requests. However, I noticed that on Win2k, after a time of the system being
up on booting, it would eventually BSOD with an UNEXPECTED_KERNEL_MODE_TRAP
exception. This normally happened after about 10 or 12 minutes.

When I then commented out the code which actually attached to the redirector
when the timer callback found the device, the BSODs no longer happened. I
assumed that my filter would then be unable to filter network access, but to
my surprise, this was not the case.

Assuming that 2000 was already notifying my filter of the redirector via my
registration callback (and that by using the timer, my filter was attaching
to the device twice), I then added code to only attempt to attach to the
redirector if the redirector’s device object was not present in my filter’s
linked list of devices. This appeared to solve the problem, and the system
stayed up for a number of hours. But this afternoon I came to do more work,
and discovered that the machine had died. Stepping through the filer code
with SoftICE, I realised that the timer callback was, in fact, still
responsible for the filter attaching to the redirector.

I am now confused; how are redirectors now handled in Win2k, and how should
NT 4 code be rewritten to cope with this (assuming that compatibility with
both OSes it to be maintained)?

i.

Ivan Lewis-Coker
Software Developer
AppSense Technologies
Europa Way
Bird Hall Lane
Cheadle Heath
Stockport
SK3 0WY

Tel: +44 (0) 161 610 4200
Fax:+44 (0) 161 610 4242

email: xxxxx@appsense.net
www: http://www.appsense.net

CONFIDENTIAL
The contents of this email and any attachments may be
confidential. It is intended for the named recipient(s).
If you are not the named recipient please notify the sender
immediately and do not disclose the contents to any other
person or make any copies.

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You are currently subscribed to ntfsd as: xxxxx@pmail.ntu.edu.sg
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