The OpenEdge Hive

by Bill Prew

The following procedure returns the ip adress and the host name for the local computer.

&SCOPED-DEFINE WSADESCRIPTION_LEN       256
&SCOPED-DEFINE WSASYS_STATUS_LEN        128
 
&SCOPED-DEFINE WSADATA_VERSION_LOW        1    /* WORD(2)  */
&SCOPED-DEFINE WSADATA_VERSION_HIGH       3    /* WORD(2)  */
&SCOPED-DEFINE WSADATA_DESCRIPTION        5    /* CHAR(WSADESCRIPTION_LEN + 1) */ 
&SCOPED-DEFINE WSADATA_SYSTEM_STATUS    262    /* CHAR(WSASYS_STATUS_LEN + 1)  */ 
&SCOPED-DEFINE WSADATA_MAX_SOCKETS      391    /* SHORT(4) */ 
&SCOPED-DEFINE WSADATA_MAX_UDP          395    /* SHORT(4) */ 
&SCOPED-DEFINE WSADATA_VENDOR_INFO      399    /* CHAR*(4) */ 
&SCOPED-DEFINE WSADATA_LENGTH           403   
 
&SCOPED-DEFINE HOSTENT_NAME               1    /* CHAR*(4)  */
&SCOPED-DEFINE HOSTENT_ALIASES            5    /* CHAR**(4) */ 
&SCOPED-DEFINE HOSTENT_ADDR_TYPE          9    /* SHORT(2)  */ 
&SCOPED-DEFINE HOSTENT_ADDR_LENGTH       11    /* SHORT(2)  */ 
&SCOPED-DEFINE HOSTENT_ADDR_LIST         13    /* CHAR**(4) */ 
&SCOPED-DEFINE HOSTENT_LENGTH            16
 
 
PROCEDURE i-GetTcpInfo:
/*------------------------------------------------------------------------
  Procedure   : i-GetTcpInfo
 
  Description : Return the windows TCP host name and address of this PC.
 
  Parms       : - Host name. (OUTPUT, CHARACTER)
                - Host address. (OUTPUT, CHARACTER):
 
  Sample usage: RUN i-GetTcpInfo (OUTPUT w-TcpName,
                                  OUTPUT w-TcpAddr).
 
  Notes       : -
------------------------------------------------------------------------*/
  DEFINE OUTPUT PARAMETER p-TcpName      AS CHARACTER NO-UNDO.
  DEFINE OUTPUT PARAMETER p-TcpAddr      AS CHARACTER NO-UNDO.
 
  DEFINE VARIABLE         w-TcpName      AS CHARACTER NO-UNDO.
  DEFINE VARIABLE         w-Length       AS INTEGER   NO-UNDO.
  DEFINE VARIABLE         w-Return       AS INTEGER   NO-UNDO.
  DEFINE VARIABLE         ptr-WsaData    AS MEMPTR    NO-UNDO.
  DEFINE VARIABLE         w-Hostent      AS INTEGER   NO-UNDO.
  DEFINE VARIABLE         ptr-Hostent    AS MEMPTR    NO-UNDO.
  DEFINE VARIABLE         ptr-AddrString AS MEMPTR    NO-UNDO.
  DEFINE VARIABLE         ptr-AddrList   AS MEMPTR    NO-UNDO.
  DEFINE VARIABLE         ptr-ListEntry  AS MEMPTR    NO-UNDO.
  DEFINE VARIABLE         w-TcpLong      AS INTEGER   NO-UNDO.
 
  /* Initialize return values */
  ASSIGN p-TcpName = ?
         p-TcpAddr = ?
         .
 
  /* Allocate work structure for WSADATA */
  SET-SIZE(ptr-WsaData) = {&WSADATA_LENGTH}.
 
  /* Ask Win32 for winsock usage */
  RUN WSAStartup (INPUT  257,        /* requested version 1.1 */
                  INPUT  GET-POINTER-VALUE(ptr-WsaData),
                  OUTPUT w-Return).
 
  /* Release allocated memory */
  SET-SIZE(ptr-WsaData) = 0.
 
  /* Check for errors */
  IF w-Return NE 0 THEN DO:
    MESSAGE "Error accessing WINSOCK support." VIEW-AS ALERT-BOX.
    RETURN.
  END.
 
  /* Set up variables */
  ASSIGN w-Length  = 100
         w-TcpName = FILL(" ", w-Length)
         .
 
  /* Call Win32 routine to get host name */
  RUN gethostname (OUTPUT w-TcpName,
                   INPUT  w-Length,
                   OUTPUT w-Return).
 
  /* Check for errors */
  IF w-Return NE 0 THEN DO:
    MESSAGE "Error getting tcp name." VIEW-AS ALERT-BOX.
    RUN WSACleanup (OUTPUT w-Return).
    RETURN.
  END.
 
  /* Pass back gathered info */
  /* remember: the string is null-terminated so there is a CHR(0)
               inside w-TcpName. We have to trim it:  */
  p-TcpName = ENTRY(1,w-TcpName,CHR(0)).
 
  /* Call Win32 routine to get host address */
  RUN gethostbyname (INPUT  w-TcpName,
                     OUTPUT w-Hostent).
 
  /* Check for errors */
  IF w-Hostent EQ 0 THEN DO:
    MESSAGE "Error resolving host name." VIEW-AS ALERT-BOX.
    RUN WSACleanup (OUTPUT w-Return).
    RETURN.
  END.
 
  /* Set pointer to HostEnt data structure */
  SET-POINTER-VALUE(ptr-Hostent) = w-Hostent.
 
  /* "Chase" pointers to get to first address list entry */
  SET-POINTER-VALUE(ptr-AddrList)  = GET-LONG(ptr-Hostent, 
                                              {&HOSTENT_ADDR_LIST}).
  SET-POINTER-VALUE(ptr-ListEntry) = GET-LONG(ptr-AddrList, 1).
  w-TcpLong                        = GET-LONG(ptr-ListEntry, 1).
 
  RUN inet_ntoa (INPUT  w-TcpLong,
                 OUTPUT ptr-AddrString).
 
  /* Pass back gathered info */
  p-TcpAddr = GET-STRING(ptr-AddrString, 1).
 
  /* Terminate winsock usage */
  RUN WSACleanup (OUTPUT w-Return).
 
END PROCEDURE.

Definitions used in this procedure, not listed in windows.p :

PROCEDURE gethostname EXTERNAL "wsock32.dll" :
  DEFINE OUTPUT       PARAMETER p-Hostname      AS CHARACTER.
  DEFINE INPUT        PARAMETER p-Length        AS LONG.
  DEFINE RETURN       PARAMETER p-Return        AS LONG.
END PROCEDURE.
 
PROCEDURE gethostbyname EXTERNAL "wsock32.dll" :
  DEFINE INPUT        PARAMETER p-Name          AS CHARACTER.
  DEFINE RETURN       PARAMETER p-Hostent       AS LONG.
END PROCEDURE.
 
PROCEDURE inet_ntoa EXTERNAL "wsock32.dll" :
  DEFINE INPUT        PARAMETER p-AddrStruct    AS LONG.
  DEFINE RETURN       PARAMETER p-AddrString    AS MEMPTR.
END PROCEDURE.
 
PROCEDURE WSAStartup EXTERNAL "wsock32.dll" :
  DEFINE INPUT        PARAMETER p-VersionReq    AS SHORT.
  DEFINE INPUT        PARAMETER ptr-WsaData     AS LONG.
  DEFINE RETURN       PARAMETER p-Return        AS LONG.
END PROCEDURE.
 
PROCEDURE WSACleanup EXTERNAL "wsock32":
  DEFINE RETURN       PARAMETER p-Return        AS LONG.
END PROCEDURE.

Notes

On Windows 98 and perhaps other versions of Windows you may prefer to use "ws32_2.dll" instead "wsock32.dll".

bugfix

June 22, 1999

Joern Winther found and solved the following bug:

   p-TcpName = w-TcpName. 

should be

   p-TcpName = ENTRY(1,w-TcpName,CHR(0)).

to get rid of the terminating null.