RtClientFilter

Description

RtClientFilter can be used in conjunction with the RtxTcpServer and client samples. RtxTcpServer must be run on the same machine on which the RtClientFilter RTDLL was registered and enabled. RtClientFilter filters UDP frames received on the machine where RtClientFilter is running. The server sample must run on the default port for the sample 9999, with the default data size.

Client sample considerations:

The client sample should run in UDP mode with the /filter option.
In this mode, client inserts a new frame after every 500 frames. The added frame includes the text DELETE at 5th UDP data byte.
Client also expects the filter driver to add frames.

RtClientFilter considerations:

Receive filter deletes every frame that is inserted by a client running with the /filter option.
The receive filter of RtClientFilter adds a frame after every 50th frame.
For every 100th frame, the receive filter of RtClientFilter modifies the data in the frame and forwards it to RtxTcpServer. On the return trip, the transmit filter of RtClientFilter determines if the returning frame contains the modified data, then changes the data back to its original state.

RtClientFilter will also print the following messages to the server window as it performs its functions:

RtClientFilter: DELETING a frame.
If frame deletion fails, RtClientFilter will print RtClientFilter: Delete frame failed
RtClientFilter: Change frame passed.
RtClientFilter: Add frame passed.

NOTE: RtClientFilter and RtxTcpServer must be run in User Datagram Protocol (UDP) for the filter to work.

Source Files

RtClientFilter project source files:

RtClientFilter.c contains the DllMain for the RtClientFilter RtDLL functions.
RtClientFilterFuncs.c contains the following functions:

RtndReceiveFilter reads the frame & determines if it will be sent or dropped.
RtndTransmitFilter is called when the stack wants to transmit a frame.
RtndUpDownFilter is called when the stack requires that the driver start (or stop) a particular NIC card.
RtndIoctlFilter is called when the stack requires that the driver configure certain NIC modes or characteristics.
RtndConfigurationFilter is called for each instance of the driver when the driver should configure the NIC hardware.

Building the Sample

Open the solution in the desired Visual Studio version you wish to build.
Once Visual Studio is open, build the sample in any desired configuration that is available.

Running the sample

Run the server on the Network Interface Card (NIC) associated with the filter. Run the client on any NIC on the same Subnet Mask (RTX or Windows) as the server NIC.

Remarks

The RtClientFilter library can be built as a Win32 DLL or an RtDLL.

APIs Referenced

RTAPI

Real Time Network APIs