The application may also occasionally query the driver for statistics information. Finally, FilterPacket does a binary search of that list and says to drop the packet if the packet is for Send and the destination IP address matches or if the packet is for Receive and the source IP address matches. This display is hardly human readable. The driver’s DevIoControl dispatcher will call a function that will fill the user’s output buffer with an array of binding name strings.. Now that handling of request completion is taken care of we can implement the rest of the driver code for making the Wininitiated requests:.

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If the associated ADAPT structure is freed before the user-mode handle is closed, then the system can crash. Simply copy the two.

NDIS resources

You can reach him at antognini mindspring. Thus, for a given adapter, a consistent picture of the IP addresses is obtained or created.

To get statistics information use the commend:. It would be used in the PtRequestComplete handler like this:. There are three errors reported when you initially attempt to build the PassThru Mdis 2 driver. We will also develop a companion Win32 application to illustrate use of the extended functions.


But for a given adapter, updating or copying the IP address list is an atomic operation. When the DeviceIoControl call returns the user-mode application will have the driver’s binding names.

Extending the PassThru NDIS IM Driver – Part 1

There is one additional problem concerning adapter handles that must be iim with. Setting the filter values and providing statistics are based on WMI.

The baseline PassThru consists of these key files:. It would be desirable to use case-insensitive string comparison functions. Do understand that you will need to enumerate the PassThru bindings and edit the NDIS adapter name in the address blocking list file.

As packets enter the FltFilterXYZ routines sanity checks are performed and then the IP header is accessed to fetch the packet source or destination address, as appropriate. The baseline PassThru consists of these key files: However, the debugging of bit user-mode applications can be performed standalone on the bit host.

It is necessary to account for the possibility that the adapter list could change while we were walking the list and copying binding names into the user’s buffer.

Here is one example:. The binding names that are returned by this query identify the bindings that can be used in other binding-specific functions. The decision to forward or to drop is made by FilterPacket in FilterRtns.


Indeed, PnP can initiate unloading of the PassThru driver at any time. If successful, it returns a buffer that has been filled with the driver binding names. You will see the usual “unsigned driver” warnings, and the driver should installed successfully. To accommodate this we add function DevOnUnbindAdapter that notifies the open handle logic about the unbind.

It is certainly intended that you should be able to incorporate the ideas and code presented in this article into your own code.

extendjng Portions Copyright c Microsoft Corporation; used by permission. One trivial approach to this problem is to only open Win32 handles to the PassThru driver for brief intervals.

Implementation of this function is straightforward.

Networking driver samples

A little memory is not released as soon as desired, but the system should not crash. The user-space programs ik class names resource information corresponding to values in PassThru.

Increment the adapter reference count. Later articles in this series will describe additional extensions to PassThru. A fairly frequent topic on the newsgroups is: You will see the techniques in miniport.