Yanick This is a bit confused!
Why do you suppose that the address space where the main z/OS Communications Server IP program runs should contain a table mapping all IP addresses you might happen to have in your program to the corresponding names? If the IP address you have is one of those corresponding to one of the interfaces of the instance of the main z/OS Communications Server IP program, then the corresponding "hostname" is that of the IP node on which the program is running. If that is so, you can retrieve a value using the GETHOSTNAME API call - and there need be no reference to the value of whichever IP address you happen to have. However, the value returned is the value, specified or default, of the HOSTNAME statement in the generically named TCPIP.DATA data set. This is *not* the "fully qualified domain name" - the flavour of the "hostname" where the last token is "COM" or "ORG" or "CA". In order to obtain the "fully qualified domain name" you need to use the GETHOSTBYNAME API call or the GETHOSTBYADDR API call. If you use the GETHOSTBYNAME API call, you will need to use a name as an input argument. That name can be the name obtained by the GETHOSTNAME API call or any other possibly truncated name. If you use the GETHOSTBYADDR API call, you will need to use an IP address as an input argument. Obviously that IP address can be the IP address you already know whether it happens to be one of the interfaces of the instance of the main z/OS Communications Server IP program or any other IP address. For the GETHOSTBYNAME or GETHOSTBYADDR call to return a result, you will need to have your generically named TCPIP.DATA data set specified so that the possibly truncated name to "fully qualified domain name" translation or the IP address to "fully qualified domain name" translation can can be performed using information in a local data set or a, possibly "the", name server system. > I'm wondering if it is possible to do an assembler cross-memory program to > talk to the address space of TCP/IP and only retrieve the hostname associate > with IP address. It may be that you suffer from a misunderstanding here. It is possible for any address space supported by a z/OS which also supports a "resolver" address space - which obviously has a dependency on a z/OS Communications Server IP main address space if a name server system needs to be accessed and may have a less obvious dependency on a z/OS Communications Server IP main address space generally - to use the mentioned API calls. Thus there is no need for your program to refer to the z/OS Communications Server IP main address space. > How do I do to issue an DNS query to retrieve only the hostname and return > the result to the caller. In principle, this question has already been answered! Before passing to the next point, I should mention yet another API call, GETHOSTID. This may be how you obtained your IP address - or maybe not! The GETHOSTID API call returns the IP address of the interface of the instance of the main z/OS Communications Server IP program which is identified, specified or default, by the PRIMARYINTERFACE statement of the PROFILE data set. - We now need to concern ourselves with any prerequisites there may be which you might need to consider before being able to use any of the mentioned calls. I have only ever actually used the old C sockets library, the one which has been deprecated ever since OpenEdition - called z/OS UNIX System Services this week! - burst upon the scene in the mid-1990s. Checking the manuals briefly, for example, the "z/OS Communications Server IP CICS Sockets Guide" manual: http://publibz.boulder.ibm.com/cgi-bin/bookmgr_OS390/BOOKS/f1a1g170/ I can't see any dependencies. However you know your CICS (and IDMS) products way better than I do. The reason I would not expect there to be any dependencies on other calls related to "sockets programming" is that all the mentioned API calls, GETHOSTNAME, GETHOSTID, GETHOSTBYNAME and GETHOSTBYADDR, do *not* rely upon having established any sockets communication.[1] The calls themselves perform some sort of "cross-memory" trick, to the z/OS Communications Server IP main address space in order to obtain the values returned by the GETHOSTNAME[2] and GETHOSTID calls, and to the "resolver" main address space in order to obtain the values returned by the GETHOSTBYNAME and GETHOSTBYADDR calls. - For advice on how to make the API calls in a CICS environment, you might like to try the CICS-L list: http://www.listserv.uga.edu/archives/cics-l.html For advice on how to make the API calls in an IDMS environment, I hope someone reading this might be able to provide you with the necessary assistance, perhaps to point you to a relevant list or other type of "forum". - [1] Clearly the "resolver" address space needs to use the sockets API if it is to communicate with an external name server system via "adjacent" name server nodes but that is a matter for the "resolver" program to manage. [2] Only earlier this year courtesy of Anson Ye in a thread in IBM-MAIN I discovered that the GETHOSTNAME API call retrieves the value of the HOSTNAME statement in the generically named TCPIP.DATA data set which is identified to the z/OS Communications Server IP main address space and *not* the generically named TCPIP.DATA data set which is identified to the address space from which originated the call. - Chris Mason On Wed, 21 Dec 2011 09:36:15 -0600, Yanick Jacques <yanick.jacq...@saaq.gouv.qc.ca> wrote: >Hi, > We run application in IDMS and CICS and we have the IP address in one > storage. Now we need more, I need the hostname. I'm wondering if it is > possible to do an assembler cross-memory program to talk to the adress space > of TCP/IP and only retrieve the hostname associate with IP address.How do I > do to issue an DNS query to retrieve only the hostname and return the result > to the caller. ---------------------------------------------------------------------- For IBM-MAIN subscribe / signoff / archive access instructions, send email to lists...@bama.ua.edu with the message: INFO IBM-MAIN
