Implementing AttachProperties

Network Monitor calls the AttachProperties function to map the properties that exist in a piece of recognized data. The AttachProperties function maps the properties to a specific location.

Network Monitor uses the following process to parse the data in a frame.

• First, Network Monitor calls RecognizeFrame to recognize all the protocols that exist in a frame.
• Then, Network Monitor calls AttachProperties for each parser that recognizes a piece of data.

When Network Monitor calls the AttachProperties function for the recognized data, the parser that is called must parse the data, and then map each existing property to a location in the recognized data. The parser determines which properties exist, and where each property is located in the data. The following figure shows parser-recognized data.

During the implementation of AttachProperties, you must call one of the following functions for each property that exists in a data frame.

• Call the AttachPropertyInstanceEx function when you want to modify the property data in a frame.
• Call the AttachPropertyInstance function when you do not want to modify the property data in a frame.

The following procedure identifies the steps necessary to implement AttachProperties.

To implement AttachProperties

1. Determine which properties exist, and the property location in the data.
2. Call AttachPropertyInstanceEx for each property with a value that you want to modify.
3. Call AttachPropertyInstance for each property with a value that you do not want to modify. Typically, this is the only function that you need to call.

The following is a basic implementation of AttachProperties. Be aware that the example does not include either the code to determine which properties exist, or the code to locate the properties.

#include <windows.h>

LPBYTE BHAPI MyProtocolAttachProperties( HFRAME   hFrame,
                                         LPBYTE   pMacFrame,
                                         LPBYTE   pBLRPLATEFrame,
                                         DWORD    MacType,
                                         DWORD    BytesLeft,
                                         HPROTOCOL  hPreviousProtocol,
                                         DWORD    nPrevProtocolOffset,
                                         DWORD    InstData)
{
  PBLRPLATEHDR pBLRPLATEHdr = (PBLRPLATEHDR)pBLRPLATEFrame;

  // Attach summary property.
  AttachPropertyInstance( hFrame,
                          BLRPLATEPropertyTable[BLRPLATE_SUMMARY].hProperty,
                          (WORD)BytesLeft,
                          (LPBYTE)pBLRPLATEFrame,
                          0,        // No Help file.
                          0,        // Indent level.
                          0);      // Data flag.

  // Attach signature property.
  AttachPropertyInstance( hFrame,
                          BLRPLATEPropertyTable[BLRPLATE_SIGNATURE].hProperty,
                          sizeof(DWORD),
                          &(pBLRPLATEHdr->Signature),
                          0,        // No Help file.
                          1,        // Indent level.
                          0);        // Data flag.


  // Attach opcode.
  AttachPropertyInstance( hFrame,
                          BLRPLATEPropertyTable[BLRPLATE_OPCODE].hProperty,
                          sizeof(WORD),
                          &(pBLRPLATEHdr->Opcode),
                          0,        // No Help file.
                          1,        // Indent level.
                          0);        // Data flag.

  // Attach flags summary.
  AttachPropertyInstance( hFrame,
                          BLRPLATEPropertyTable[BLRPLATE_FLAGS_SUMMARY].hProperty,
                          sizeof(BYTE),
                          &(pBLRPLATEHdr->Flags),
                          0,        // No Help file.
                          1,        // Indent level.
                          0);       // Data flag.

// Attach flags decode.
  AttachPropertyInstance( hFrame,
                          BLRPLATEPropertyTable[BLRPLATE_FLAGS_FLAGS].hProperty,
                          sizeof(BYTE),
                          &(pBLRPLATEHdr->Flags),
                          0,        // No Help file.
                          2,        // Indent level.
                          0);       // Data flag.

  RETURN null;

}