Code Doesn't Compile - pointer "@" syntax error

[David Gwillim]

Pierre,

Thanks for taking a look at this HostEntStru TYPE change. I am always eager to learn something new.

Trying "google.com" as the hostname in your code, it generates Google's three IP addresses, the same ones as are reported by the Window's command line utility NSLOOKUP. IP addresses beyond the 3rd are garbage in memory I guess.

David

[Pierre Bellisle]

Seem's that the newer HostEntStru definition is more appropriate
becose h_alias is an array of pointers to aliasses names, in fact it's Microsoft way.

It would be appreciated if anybody can test the following code
with a host that have one or many aliasses names and give feedback
so we can know if code is valid or need corection...

#COMPILE EXE '#Win 8.04# 
#DIM ALL
#INCLUDE "WIN32API.INC" '#2005-01-27#
#INCLUDE "WSOCK32.INC"
 
TYPE HostEntStru 'PowerBASIC 7+ definition
  h_name  AS ASCIIZ PTR  'Official name of the host
  h_alias AS DWORD       'A NULL-terminated array of alternate names.
  h_addr  AS INTEGER     'The type of address being returned.
  h_len   AS INTEGER     'The length, in bytes, of each address.
  h_list  AS DWORD       'A NULL-terminated list of addresses for the host.
END TYPE
 
%MAX_HostName_LEN = 128
'______________________________________________________________________________
 
FUNCTION AddrTypeString(AddrType AS INTEGER)AS STRING
 
 SELECT CASE AddrType
   CASE %AF_UNSPEC       : FUNCTION = "AF_UNSPEC"       ' 0       unspecified
   CASE %AF_UNIX         : FUNCTION = "AF_UNIX"         ' 1       local to host (pipes, portals)
   CASE %AF_INET         : FUNCTION = "AF_INET"         ' 2       internetwork: UDP, TCP, etc.
   CASE %AF_IMPLINK      : FUNCTION = "AF_IMPLINK"      ' 3       arpanet imp addresses
   CASE %AF_PUP          : FUNCTION = "AF_PUP"          ' 4       pup protocols: e.g. BSP
   CASE %AF_CHAOS        : FUNCTION = "AF_CHAOS"        ' 5       mit CHAOS protocols
   CASE %AF_IPX, %AF_NS  : FUNCTION = "F_IPX - AF_NS"   ' 6       IPX and SPX, XEROX NS protocols
   CASE %AF_ISO, %AF_OSI : FUNCTION = "AF_ISO - AF_OSI" ' 7       ISO protocols
   CASE %AF_ECMA         : FUNCTION = "AF_ECMA"         ' 8       european computer manufacturers
   CASE %AF_DATAKIT      : FUNCTION = "AF_DATAKIT"      ' 9       datakit protocols
   CASE %AF_CCITT        : FUNCTION = "AF_CCITT"        '10       CCITT protocols, X.25 etc
   CASE %AF_SNA          : FUNCTION = "AF_SNA"          '11       IBM SNA
   CASE %AF_DECnet       : FUNCTION = "AF_DECnet"       '12       DECnet
   CASE %AF_DLI          : FUNCTION = "AF_DLI"          '13       Direct data link interface
   CASE %AF_LAT          : FUNCTION = "AF_LAT"          '14       LAT
   CASE %AF_HYLINK       : FUNCTION = "AF_HYLINK"       '15       NSC Hyperchannel
   CASE %AF_APPLETALK    : FUNCTION = "AF_APPLETALK"    '16       AppleTalk
   CASE %AF_NETBIOS      : FUNCTION = "AF_NETBIOS"      '17       NetBios-style addresses
 END SELECT
 
END FUNCTION
'______________________________________________________________________________
 
FUNCTION PBMAIN()
 LOCAL sBuffer           AS STRING
 LOCAL WinSock           AS WsaData
 LOCAL HostName          AS ASCIIZ * %MAX_HostName_LEN
 LOCAL HostEntry         AS HostEntStru PTR
 LOCAL ipPointer         AS ASCIIZ PTR
 LOCAL AliasPointer      AS ASCIIZ PTR
 LOCAL ListArrayPointer  AS DWORD POINTER
 LOCAL AliasArrayPointer AS DWORD POINTER
 LOCAL RetVal            AS LONG
 
 RetVal = WsaStartup(&H101, WinSock) 'Initiates Windows Sockets
 IF RetVal = %NOERROR THEN
 
   HOST NAME TO HostName 'Set HostName to your machine name...
   HostEntry = GetHostByName(HostName) 'Returns a pointer to the hostent structure
 
   IF HostEntry THEN 'GetHostByName was successfull
 
     sBuffer = "IP addresses assignement..." & $CRLF  & $CRLF
     sBuffer = sBuffer & "Host name: " & @[email protected]_name & $CRLF
 
     AliasArrayPointer = @HostEntry.h_alias 'We'll use AliasArrayPointer instead of .h_alias
     DO WHILE @AliasArrayPointer 'If pointer is zero then no more data
       AliasPointer = @AliasArrayPointer
       sBuffer = sBuffer & "Alias: " & @AliasPointer & $CRLF
       @AliasArrayPointer = @AliasArrayPointer + 4 '4 is dword lenght
     LOOP
 
     sBuffer = sBuffer & "Adress type: " & AddrTypeString(@HostEntry.h_addr) & $CRLF
 
     sBuffer = sBuffer & "Adress lenght:" & STR$(@HostEntry.h_len) & $CRLF & $CRLF
 
     ListArrayPointer = @HostEntry.h_list 'We'll use ListArrayPointer instead of .h_list
     DO WHILE @@ListArrayPointer 'If pointer is zero then no more data
       ipPointer = inet_ntoa(@@ListArrayPointer) 'Converts network address into a dotted string
       sBuffer = sBuffer & "ip : " & @ipPointer & $CRLF
       @ListArrayPointer = @ListArrayPointer + @HostEntry.h_len 'Move to next entry
     LOOP
 
     WSACleanup
     MessageBox %HWND_DESKTOP, BYCOPY sBuffer, "GetHostByName", 64
 
   END IF
 END IF
 
END FUNCTION
'______________________________________________________________________________

[David Gwillim]

Thanks for the references Fred. I took a brief look and will have to return to them later on a more studied level.

David

[Fred Harris]

Pointer Examples

Maybe this will help David...

C To PowerBASIC Pointer Conversions

http://www.powerbasic.com/support/pbforums/showthread.php?t=25165&highlight=Pointers

Pointers, Dynamic Memory Allocation, and Instance Data

http://www.jose.it-berater.org/smfforum/index.php?topic=1292.0

They include real short programs along with output showing how to get started with pointers.

[Michael Mattias]

> do wish though that I understood why the structure in wsock32.inc was changed

That would be PwerBASIC Inc's Windows' Header Information Management system.

aka "WHIM"

MCM

[David Gwillim]

As an immediate work around I simply created the same hostentStru I found in the wsock32.inc for PB/DLL 6.1 with a change for the name of the structure.

TYPE hostentStru2
  h_name     AS ASCIIZ PTR
  h_alias    AS ASCIIZ PTR
  h_addr     AS INTEGER
  h_len      AS INTEGER
  h_list     AS LONG PTR
END TYPE

I then went through the source and replaced hostentStru with hostentStru2 in all the DIMs. Now Florent's DNS Query compiles and runs just fine.

I do wish though that I understood why the structure in wsock32.inc was changed. I also wish I had more experience with pointers.

David

[David Gwillim]

OK I did a bit more digging and it seems that the definition for the structure TYPE hostentStru in wsock32.inc changed from this in PB/DLL 6.1:

TYPE hostentStru
  h_name     AS ASCIIZ PTR
  h_alias    AS ASCIIZ PTR
  h_addr     AS INTEGER
  h_len      AS INTEGER
  h_list     AS LONG PTR
END TYPE

to this in PBwin 7.04 and later

TYPE hostentStru
    h_name  AS ASCIIZ PTR   ' official name of host
    h_alias AS DWORD        ' alias list (pointer to ASCIIZ PTR list)
    h_addr  AS INTEGER      ' host address type
    h_len   AS INTEGER      ' length of address
    h_list  AS DWORD        ' list of addresses (pointer to ASCIIZ PTR list)
END TYPE

Now how do I restructure the code in Florent's DNS Query program to match the new structure definition?

David

[David Gwillim]

I retrieved the following from the Source Code forum and found that it doesn't compile in PBWin 7.04 and later, but does compile in PBDLL 6.1.

It's some code by Florent Heyworth for DNS Query.

http://powerbasic.com/support/pbforums/showthread.php?t=24950&highlight=DNS+RECORDS

The problem code uses pointers and any line containing

@[email protected]@h_list

triggers a compiler syntax error at the "@@".

I have never used pointers and am not familiar with what changes occurred in the allowed syntax for their use. Could someone help me please? I would like to get the code to compile.

Thanks,

David