From: jukkao@sulo.otol.fi (Jukka Oraj{rvi)
Newsgroups: comp.sys.sun.admin
Subject: Re: DNS without NIS
Date: 11 Jan 93 17:37:27 GMT
Organization: Oulu Institute of Technology, Finland

From article <1is18lINNrje@rave.larc.nasa.gov>, by tony@longstreet.noname (tony calabrase):
> 	Is anyone out there running DNS with out NIS on a SUN under SunOS 4.1.3.  If so, would you let us know how you did.
> 
> 			Thanks,
> 
> 
> 			tony@longstreet.larc.nasa.gov
> 
> 

SUN-SPOTS DIGEST         Wednesday, 25 April 1990     Volume 9 : Issue 136
  Creating a libc.so with DNS resolver support (+ no YP) under SunOS 4.1

Date:    Tue, 24 Apr 90 22:03:04 -0700
From:    earle@poseur.jpl.nasa.gov (Greg Earle)
Subject: Creating a libc.so with DNS resolver support (+ no YP) under SunOS 4.1
X-Art:   Usenet #9

As it appears that SunOS 4.1 is now reaching our users in reasonable
quantities, we offer the following announcement for our Internet
customers:

Background:

As you may know, the normal /usr/lib/libc.so.* that ships with SunOS 4.x
contains the library routines gethostbyname(3) and gethostbyaddr(3) to do
host name and address resolution.  These routines normally reference the
`hosts' NIS (nee YP) map first, and then fall back to looking in the
/etc/hosts file.  By changing the NIS Makefile to invoke `makedbm' with
the `-b' option, one can arrange things so that NIS does lookups first to
a DNS (Domain Name Service) name server, via the resolver routines.  This
is the Sun supported way of doing things.

But many of Sun's Internet customers want to be able to use resolver-based
lookups without having to run NIS/YP.  In order to fill this void under
SunOS 4.0.x, Sun created `libc_resolv.so' versions of the shared C library
with the gethostbyname()/gethostbyaddr() routines replaced by the
equivalent functions from the BIND nameserver distribution's resolver
library (plus supporting functions).  These were made available via
anonymous FTP on the host `uunet.UU.NET', in the `sun-fixes' directory.

Now SunOS 4.1 has arrived, but there is no equivalent `libc_resolv.so'
available via this mechanism (anonymous FTP from `uunet.UU.NET').  This
message addresses this situation.

Fortunately, 2 things in SunOS 4.1 have come to the rescue:

(1) There is a selectable software category in the 4.1 Full Install called
    `Shlib Custom' that enables one to build custom shared libraries.  This
    software gets installed in /usr/lib/shlib.etc, with a README file
    containing instructions on how to build your own custom shared C library.
    If you wish to build a version of libc.so with the resolver routines, make
    sure to select this category when installing SunOS 4.1.

(2) The version of /usr/lib/libresolv.a in 4.1 has been compiled with `cc
    -pic', thus producing position-independant code.

Thus, what follows is an additional set of comments that can be *directly*
*appended* (i.e., `cat <remainder-of-this-message> >> README') to the file
`/usr/lib/shlib.etc/README' which provides instructions on how to build a
libc.so.X.NN.1 that will use the resolver for hostname/hostaddr
resolution.

Sun can make no guarantees on this, but this method has been in use on
Internet hosts running SunOS 4.1FCS for 3 weeks now, doing telnet, rlogin,
ftp, etc. to hosts that are not in the hosts table (on hosts that do not
run NIS/YP), and it works without any known problems.

One final note: the method described below applies to Sun's supported
SunOS 4.1 version of the resolver library (libresolv.a), which is based on
BIND 4.8.  As many of you are aware, there are `post-4.8' versions of BIND
floating around out there.  We are aware of versions from UC Berkeley,
University of Toronto, and University of Michigan, among others.  Although
these versions cannot be supported, it is our opinion that if the code for
these customized versions of the resolver library adheres to proper shared
library conventions, then if the modules in these libraries are compiled
with `cc -pic', the resulting object modules should be usable in the
manner described below for the shipped /usr/lib/libresolv.a.  A simple
test will confirm whether this will work:

	% mkdir tmp ; cd tmp ; ar xv /path/to/your/custom/libresolv.a
	% ld -assert pure-text *.o

If there are non-PIC constructs in these objects, the assertion would tell
you about them.  For more information about position-independant code and
shared libraries, please read Chapter 1 in the "Programming Utilities and
Libraries" manual that is included in the SunOS 4.1 documentation set.  It
is contained in the binder labelled "Programmer's Overview - Utilities and
Libraries" on the spine.

Without further ado, here it is.  As mentioned, cut off below the line,
save to a file, and then append that file to /usr/lib/shlib.etc/README.

	Greg Earle
	Sun Microsystems, Inc. - JPL on-site Software Support
	earle@poseur.JPL.NASA.GOV	(direct)
	earle@Sun.COM			(indirect)

-------------------------------- >8 Cut here 8< ------------------------------

Supplemental instructions for building a shared libc.so that uses the resolver
for hostname/addr resolution:

10. Extract the contents of libc_pic.a and /usr/lib/libresolv.a into the
    tmp directory:
	% cd tmp
	% ar x ../libc_pic.a
	% ar x /usr/lib/libresolv.a

    The libresolv.a (apparently) contains object modules that are position
    independant, so they can be added to the libc_pic modules without fear.

11. Remove the old routine to do the hostname/addr resolution:
	% rm gethostent.o

12. Remove the libresolv module that contains `strncasecmp' (which is now
    in the main C library, so it is redundant):
	% rm strcasecmp.o

13. As mentioned in step 5 above, edit the file `lorder-sparc' in the ..
    directory.  Remove the reference to `gethostent.o' and add the
    references to the resolver library routines by applying this patch:

	% diff -rc2 lorder-sparc.orig lorder-sparc
	*** lorder-sparc.orig   Thu Feb  8 05:27:46 1990
	--- lorder-sparc	Mon Apr  9 12:58:59 1990
	***************
	*** 150,154 ****
	  getwd.o
	  getnetgrent.o
	! gethostent.o
	  ypxdr.o
	  ttyname.o
	--- 150,161 ----
	  getwd.o
	  getnetgrent.o
	! gethostnamadr.o
	! sethostent.o
	! res_query.o
	! res_mkquery.o
	! res_send.o
	! res_debug.o
	! res_comp.o
	! res_init.o
	  ypxdr.o
	  ttyname.o

14. Continue as above, from steps 6 to 9.

	- Greg Earle			| It takes up to 40 dumb animals to
	  Sun Los Angeles		| make one fur coat ... but only one
	  JPL on-site Software Support	| to wear it.
	  sun!poseur!earle		| Fur - the look that kills.

-- 
#  Jukka Oraj{rvi, Oulu Institute of Technology, Finland                #
#  X.400: g=jukka/s=orajarvi/o=otol/p=sapina/a=mailnet/c=fi             #