Internet dialup program

bool GetPhonebookEntries()
{
   RASENTRYNAME* first_ras_entry; // really a buffer of [num_entries]
   DWORD buf_size, entry_size;
   DWORD num_entries = 1;
   DWORD retval;
   UINT  ndx;
   char  szMessage[256];

   entry_size = sizeof(RASENTRYNAME);
   buf_size = entry_size * num_entries;
   first_ras_entry = (LPRASENTRYNAME) new char[buf_size];

   // check for a malloc() failure
   if (NULL == first_ras_entry) return FALSE;

   // clear the whole buffer, rather than a single entry
   ZeroMemory(first_ras_entry, buf_size); // AKA bzero() or memset(0)
   first_ras_entry->dwSize = entry_size; // initialize the dwSize member
   retval = RasEnumEntries(NULL, NULL, first_ras_entry, &buf_size, &num_entries);

   if (
          (ERROR_BUFFER_TOO_SMALL == retval) // entry size OK, but too many entries
       || (ERROR_INVALID_SIZE == retval) // entry size wrong
      )
   {
      entry_size = buf_size / num_entries; // recalculate the correct entry size
      
      // reallocate the buffer:
      delete first_ras_entry;
      first_ras_entry = NULL;
      first_ras_entry = (LPRASENTRYNAME) new char[buf_size];
      
      if (NULL != first_ras_entry) // if buffer OK, try again
      {
         ZeroMemory(first_ras_entry, buf_size);
         first_ras_entry->dwSize = entry_size;
         retval = RasEnumEntries(NULL, NULL, first_ras_entry, &buf_size, &num_entries);
      }
      else
         retval = ERROR_NOT_ENOUGH_MEMORY;
   }

   if (0 != retval) // other error
   {
      long int tmp_retval;
      tmp_retval = RasGetErrorString((UINT)retval, szMessage, 256);
      if (0 == tmp_retval)
      {
         printf("%s\n", szMessage);
      }
      else
         printf("Couldn't get a verbose err. message. RasGetErrorString() = %ld", tmp_retval);
   }

   if (0 == num_entries)
   {
      delete first_ras_entry ;
      return FALSE;
   }

   if (0 == retval)  // No errors
   {
      for (ndx = 0; ndx < num_entries; ndx++)
      {
         printf("Found a RAS entry: %s\n", first_ras_entry[ndx].szEntryName);
      }
   }

   delete first_ras_entry;
   return TRUE;
}