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ISAPI Filter not getting invoked (or loaded)

Posted on 2000-04-05
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Last Modified: 2013-11-20
Platform:  Win NT Server 4.0 + SP6 with IIS4.0

I copied two sample ISAPI filter, one from the Visual C++ ISAPI programming book and the other from MSDN.  They are both created in VC++ projects.  They compiled successfully.

Based on the instructions, I am supposed to list the full path for each DLL in the registry at:
"HKEY_LOCAL_MACHINE\System\CurrentControlSet\Services\W3SVC\Parameters\FilterDLLs"

1. First, there was no such key, so I had to create FilterDLLs key.

2. I listed both DLLs as such:
D:\Books\Pro VC++ ISAPI\SimpleFilter\Debug\SimpleFilter.dll, D:\Program Files\Microsoft Visual Studio\MyProjects\Filter\Debug\Filter.dll
However, neither one gets invoked when I http to the server.  Both filters have OnUrlMap() and all the other methods so any http request should load and invoke the filter.  however, nothing is happening.

Here is SimpleFilter.dll

/////////////////////////////////////////////////
//  SimpleFilter.cpp


#include <windows.h>
#include <httpfilt.h>


//  DebugMsg() is used for debugging
#define DEST buff
#define DebugMsg(x)            \
   {                           \
      char buff[256];          \
      wsprintf x;              \
      OutputDebugString(buff); \
   }


BOOL WINAPI GetFilterVersion(HTTP_FILTER_VERSION* pVer)
{
   // The version of the web server this is running on
   DebugMsg(( DEST, "Web Server is version is %d.%d\n",
              HIWORD( pVer->dwServerFilterVersion ),
              LOWORD( pVer->dwServerFilterVersion ) ));

   // Our filter version nuumber.
   pVer->dwFilterVersion = MAKELONG( 1, 0 );   // Version 0.1

   // The description
   strcpy( pVer->lpszFilterDesc, "Simple Filter, 0.1" );

   // Requests Everything
   pVer->dwFlags = ( SF_NOTIFY_SECURE_PORT         |
                     SF_NOTIFY_NONSECURE_PORT      |
                     SF_NOTIFY_READ_RAW_DATA       |
                     SF_NOTIFY_PREPROC_HEADERS     |
                     SF_NOTIFY_URL_MAP             |
                     SF_NOTIFY_AUTHENTICATION      |
                     SF_NOTIFY_SEND_RAW_DATA       |
                     SF_NOTIFY_LOG                 |
                     SF_NOTIFY_END_OF_NET_SESSION  |
                     SF_NOTIFY_ORDER_DEFAULT );

   return TRUE;
}


DWORD OnReadRawData(HTTP_FILTER_CONTEXT *pfc,
                    HTTP_FILTER_RAW_DATA *pRawDataInfo)
{
   DebugMsg((DEST,"OnReadRawData\r\n"));
   return SF_STATUS_REQ_NEXT_NOTIFICATION;
}


DWORD OnPreprocHeaders(HTTP_FILTER_CONTEXT* pFC,
                       HTTP_FILTER_PREPROC_HEADERS* pHeaderInfo)
{
   DebugMsg((DEST,"OnPreprocHeaders\r\n"));

   CHAR achUrl[512];
   DWORD cbURL=512;

   pHeaderInfo->GetHeader(pFC, "url",achUrl,&cbURL);

   DebugMsg((DEST,"Requested URL is:%s.\r\n",achUrl));
   return SF_STATUS_REQ_NEXT_NOTIFICATION;
}


DWORD OnUrlMap(HTTP_FILTER_CONTEXT* pFC, HTTP_FILTER_URL_MAP* pUrlMapInfo)
{
   DebugMsg((DEST,"OnUrlMap\r\n"));
   DebugMsg((DEST,"PhysicalPath: %s\r\n",pUrlMapInfo->pszPhysicalPath));
   return SF_STATUS_REQ_NEXT_NOTIFICATION;
}


DWORD  OnAuthentication(HTTP_FILTER_CONTEXT* pFC,
                        HTTP_FILTER_AUTHENT* pAuthInfo)
{
   DebugMsg((DEST,"OnAuthentication\r\n"));
   DebugMsg((DEST,"UserName: %s\r\n",pAuthInfo->pszUser));
   return SF_STATUS_REQ_NEXT_NOTIFICATION;
}


DWORD OnSendRawData(HTTP_FILTER_CONTEXT* pFC,
                    HTTP_FILTER_RAW_DATA* pRawDataInfo)
{
   DebugMsg((DEST,"OnSendRawData\r\n"));
   return SF_STATUS_REQ_NEXT_NOTIFICATION;
}


DWORD OnLog(HTTP_FILTER_CONTEXT* pFC, HTTP_FILTER_LOG* pLogInfo)
{
   DebugMsg((DEST,"OnLog\r\n"));
   DebugMsg((DEST,"Target:%s\r\n",pLogInfo->pszTarget));
   return SF_STATUS_REQ_NEXT_NOTIFICATION;
}


DWORD OnEndOfNetSession(HTTP_FILTER_CONTEXT* pFC)
{
   DebugMsg((DEST,"OnEndOfNetSession\r\n"));
   return SF_STATUS_REQ_NEXT_NOTIFICATION;
}


DWORD WINAPI HttpFilterProc(HTTP_FILTER_CONTEXT* pFC,
                            DWORD NotificationType, VOID* pvData)
{
   DWORD dwRet;

   // Send this notification to the right function
   switch ( NotificationType )
   {
   case SF_NOTIFY_READ_RAW_DATA:
      dwRet = OnReadRawData( pFC, (PHTTP_FILTER_RAW_DATA) pvData );
      break;
   case SF_NOTIFY_PREPROC_HEADERS:
      dwRet = OnPreprocHeaders( pFC,
                                (PHTTP_FILTER_PREPROC_HEADERS) pvData );
      break;
   case SF_NOTIFY_URL_MAP:
      dwRet = OnUrlMap( pFC, (PHTTP_FILTER_URL_MAP) pvData );
      break;
   case SF_NOTIFY_AUTHENTICATION:
      dwRet = OnAuthentication( pFC, (PHTTP_FILTER_AUTHENT) pvData );
      break;
   case SF_NOTIFY_SEND_RAW_DATA:
      dwRet = OnSendRawData( pFC, (PHTTP_FILTER_RAW_DATA) pvData );
      break;
   case SF_NOTIFY_LOG:
      dwRet = OnLog( pFC, (PHTTP_FILTER_LOG) pvData );
      break;
   case SF_NOTIFY_END_OF_NET_SESSION:
      dwRet = OnEndOfNetSession(pFC);
      break;
   default:
      DebugMsg(( DEST,
                 "[HttpFilterProc] Unknown notification type, %d\r\n",
                 NotificationType ));
      dwRet = SF_STATUS_REQ_NEXT_NOTIFICATION;
      break;
   }
   return dwRet;
}


Thank you





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Question by:bustany
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3 Comments
 
LVL 9

Accepted Solution

by:
ShaunWilde earned 200 total points
ID: 2689111
whenevr I have loaded a filter I used the internet service manager and added the filter that way - the instructions come with the sample upcase which is avalable from the inetsdk

This sample works by monitoring requests for .htm files in a directory path that ends with /UC. It then strips the trailing /UC from the directory path and uppercases the body of the HTML text that goes by.
To install this filter, use the Internet Service Manager in the Start menu.

Start\
  Programs\
    Windows NT 4.0 Option Pack\
      Microsoft Internet Information Server\
        Internet Service Manager

Right mouse click on the Web Site you wish to install the filter on. Choose Properties. Click on the ISAPI Filters tab, and add the filter.

Like any ISAPI Filter, this DLL is loaded when the web server is started and it stays loaded until the server is stopped.

0
 
LVL 11

Expert Comment

by:mikeblas
ID: 2702432
Are you sure that you have IIS installed?  If you don't have it installed, some of the W3SVC keys get created by NT, but aren't populated.

Can you get plain webpages from your machine?

Have you tried debuggging? Is your DllMain() being executed?

..B ekiM
0
 

Author Comment

by:bustany
ID: 2753290
thank you.  it worked
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