Re: Input IPv4 address - return DNS name -- MIDRANGE-L

IBM i has "resolver" routines built-in that do this sort of thing. Ifall you need is IPv4, you could call the gethostbyaddr() API. There arenewer/better routines available that support IPv6 (though, I must admit,it'd take a bit of research for me to find this.)

I wonder if it'd make sense for you to use these routines instead ofcalling the DIG program? Nothing wrong with using DIG, I guess... butcalling the APIs directly would be faster, no need to output to a fileand read a file, it'd return the result directly. But, it does involvesome pointer work...


Want a code sample?  (If so, is RPG alright, or does it need to be CL?)

-SK

On 5/18/2015 3:36 PM, Steinmetz, Paul wrote:

I've created a utility that inputs an IPv4 address and returns the DNS name.
It uses the DIG command with the out file option.
Does anything exist that does something similar?

I'm planning on using this as part of a larger project to create and populate a log file of all external communications, (FTP, SSL, SSH, etc)

0008.00              PGM        PARM(&IPV4 &DNSNAM)
0009.00
0010.00              /* VARIABLE DECLARATIONS                */
0011.00
0012.00              DCL        VAR(&IPV4) TYPE(*CHAR) LEN(30)
0013.00              DCL        VAR(&DNSNAM) TYPE(*CHAR) LEN(256 )
0014.00
0015.00              RMVLNK     OBJLNK('/DIGOUT')
0016.00
0017.00              DIG        HOSTNAME(&IPV4) REVERSE(*YES) +
0018.00                           IPVSN(*IPV4ONLY) SHORT(*YES) +
0019.00                           IDENTIFY(*YES) TOSTMF(DIGOUT)
0020.00
0021.00              CPYFRMIMPF FROMSTMF('/DIGOUT') TOFILE(QGPL/DIGOUT) +
0022.00                           MBROPT(*REPLACE) RCDDLM(*LF) +
0023.00                           RPLNULLVAL(*FLDDFT)
0024.00
0025.00              CALL       PGM(DIGCONV) PARM(&DNSNAM) /* Search DIG +
0026.00                           outfile, find and return DNS name */
0027.00
0028.00              DMPCLPGM
0029.00
0030.00  END:        ENDPGM


0001.00 H DEBUG
0009.00  **************************************************************************
0010.00 Fdigout    ipe  f 3965        disk
0011.00  **************************************************************************
0012.00 dsearchfor        s             12
0013.00  **************************************************************************
0014.00  * Input Parameters
0015.00 idigout    AA  01
0016.00
0017.00  * Record type
0018.00
0019.00 i                                  1 3965  irec
0020.00  **************************************************************************
0021.00 C     *entry        plist
0022.00 C                   parm                    dnsfnd          256
0023.00
0024.00 c                   eval      searchfor = 'from server '
0025.00 c                   exsr      search
0026.00  **************************************************************************
0027.00 C     search        begsr
0028.00  **************************************************************************
0029.00  /free
0030.00                     pos = %scan(searchfor: irec :1);
0031.00                     if        pos <> 0;
0032.00                     dnsfnd = %Subst(irec:1 :pos-3);
0033.00                     endif;
0034.00  /end-free
0035.00 c                   endsr

Thank You
_____
Paul Steinmetz
IBM i Systems Administrator

Pencor Services, Inc.
462 Delaware Ave
Palmerton Pa 18071

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