C# Signature:

[DllImport("httpapi.dll", SetLastError = true)]
static extern uint HttpQueryServiceConfiguration(
     IntPtr ServiceIntPtr,
     HTTP_SERVICE_CONFIG_ID ConfigId,
     IntPtr pInputConfigInfo,
     int InputConfigInfoLength,
     IntPtr pOutputConfigInfo,
     int OutputConfigInfoLength,
     [Optional()]
     out int pReturnLength,
     IntPtr pOverlapped);

VB Signature:

Declare Function HttpQueryServiceConfiguration Lib "httpapi.dll" (TODO) As TODO

User-Defined Types:

HTTP_SERVICE_CONFIG_ID

HTTP_SERVICE_CONFIG_SSL_QUERY

HTTP_SERVICE_CONFIG_URLACL_QUERY

HTTP_SERVICE_CONFIG_IP_LISTEN_QUERY

HTTP_SERVICE_CONFIG_SSL_SET

HTTP_SERVICE_CONFIG_URLACL_SET

Notes:

Depending on the value of ConfigId, both pInputConfigInfo and pOutputConfigInfo should point to a different type of structure. If it wasn't for this, I could redifine the PInvoke signature to explicitly specify the underlying structure type.

Tips & Tricks:

If your use of this API is focused around a single value of ConfigId, you may want to change the IntPtr (pConfigInformation) to point directly to a managed version of the correct underlying structure and let the default marshaller take care of the interop layer marshaling for you (and your memory management).

Sample Code:

HTTP_SERVICE_CONFIG_URLACL_SET QueryServiceConfig(string networkURL)
{
     HTTPAPI_VERSION httpApiVersion = new HTTPAPI_VERSION(1, 0);
     uint retVal = (uint) ErrorCodes.NOERROR; // NOERROR = 0

     retVal = HttpApi.HttpInitialize(httpApiVersion, HTTP_INITIALIZE_CONFIG, IntPtr.Zero);
     if ((uint) ErrorCodes.NOERROR == retVal)
     {
     HTTP_SERVICE_CONFIG_URLACL_KEY urlAclKey = new HTTP_SERVICE_CONFIG_URLACL_KEY(networkURL);

     HTTP_SERVICE_CONFIG_URLACL_QUERY inputConfigInfoQuery = new HTTP_SERVICE_CONFIG_URLACL_QUERY();
     inputConfigInfoQuery.QueryDesc = HTTP_SERVICE_CONFIG_QUERY_TYPE.HttpServiceConfigQueryExact;
     inputConfigInfoQuery.KeyDesc = keyDesc;
     inputConfigInfoQuery.dwToken = 0;

     int size = Marshal.SizeOf(typeof(HTTP_SERVICE_CONFIG_URLACL_QUERY));
     IntPtr pInputConfigInfo = Marshal.AllocCoTaskMem(Marshal.SizeOf(typeof(HTTP_SERVICE_CONFIG_URLACL_QUERY)));
     Marshal.StructureToPtr(inputConfigInfoQuery, pInputConfigInfo, true);

     HTTP_SERVICE_CONFIG_URLACL_SET outputConfigInfo = new HTTP_SERVICE_CONFIG_URLACL_SET();

     IntPtr pOutputConfigInfo = Marshal.AllocCoTaskMem(0);
     int returnLength = 0;

     size = Marshal.SizeOf(inputConfigInfoQuery);

     retVal = HttpApi.HttpQueryServiceConfiguration(IntPtr.Zero,
         HTTP_SERVICE_CONFIG_ID.HttpServiceConfigUrlAclInfo,
         pInputConfigInfo,
         Marshal.SizeOf(inputConfigInfoQuery),
         pOutputConfigInfo,
         returnLength,
         out returnLength,
         IntPtr.Zero);

     if (ErrorCodes.ERROR_INSUFFICIENT_BUFFER == retVal) // ERROR_INSUFFICIENT_BUFFER = 122
     {
         Marshal.FreeCoTaskMem(pOutputConfigInfo);
         pOutputConfigInfo = Marshal.AllocCoTaskMem(Convert.ToInt32(returnLength));

         retVal = HttpApi.HttpQueryServiceConfiguration(IntPtr.Zero,
         HTTP_SERVICE_CONFIG_ID.HttpServiceConfigUrlAclInfo,
         pInputConfigInfo,
         Marshal.SizeOf(inputConfigInfoQuery),
         pOutputConfigInfo,
         returnLength,
         out returnLength,
         IntPtr.Zero);
     }

     if (ErrorCodes.NOERROR == retVal)
     {
        outputConfigInfo = (HTTP_SERVICE_CONFIG_URLACL_SET)Marshal.PtrToStructure(pOutputConfigInfo, typeof(HTTP_SERVICE_CONFIG_URLACL_SET));
     }

     HttpApi.HttpTerminate(HttpApi.HTTP_INITIALIZE_CONFIG, IntPtr.Zero);
     }

     if ((uint) ErrorCodes.NOERROR != retVal)
     {
     throw new Win32Exception(Convert.ToInt32(retVal));
     }

     return outputConfigInfo;
}

Sample Code:

Here is the code sample to work with SSL certificate configuration records http://dotnetcodebox.blogspot.com/2012/01/how-to-work-with-ssl-certificate.html .

Alternative Managed API:

Do you know one? Please contribute it!