Date: Wed, 10 Jan 2001 10:10:03 -0800 (PST) From: Ben Smithurst <ben@freebsd.org> To: freebsd-doc@freebsd.org Subject: Re: docs/24225: Useless gethostbyaddr man page Message-ID: <200101101810.f0AIA3g10009@freefall.freebsd.org>
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The following reply was made to PR docs/24225; it has been noted by GNATS.
From: Ben Smithurst <ben@FreeBSD.org>
To: Joakim Henriksson <murduth@ludd.luth.se>
Cc: FreeBSD-gnats-submit@freebsd.org
Subject: Re: docs/24225: Useless gethostbyaddr man page
Date: Wed, 10 Jan 2001 16:17:26 +0000
Joakim Henriksson wrote:
> The manual page for gethostbyaddr does not even describe what the arguments
> should be.
ok, what do you (and everyone else) think of this patch?
Index: gethostbyname.3
===================================================================
RCS file: /usr/cvs/src/lib/libc/net/gethostbyname.3,v
retrieving revision 1.14
diff -u -r1.14 gethostbyname.3
--- gethostbyname.3 2000/09/06 18:16:40 1.14
+++ gethostbyname.3 2001/01/10 16:14:20
@@ -76,7 +76,34 @@
each return a pointer to an object with the
following structure describing an internet host
referenced by name or by address, respectively.
-This structure contains either the information obtained from the name server,
+.Pp
+The
+.Fa name
+parameter passed to
+.Fn gethostbyname
+or
+.Fn gethostbyname2
+should point to a NUL-terminated hostname.
+The
+.Fa addr
+parameter passed to
+.Fn gethostbyaddr
+should point to an address which is
+.Fa len
+bytes long,
+in binary form
+(i.e. not an IP address in human readable ASCII form).
+The
+.Fa type
+parameter specifies the address family
+(e.g.
+.Dv AF_INET ,
+.Dv AF_INET6 ,
+etc)
+of this address.
+.Pp
+The structure returned contains either the information obtained from the name
+server,
.Xr named 8 ,
broken-out fields from a line in
.Pa /etc/hosts ,
@@ -198,6 +225,23 @@
.It Pa /etc/nsswitch.conf
.It Pa /etc/resolv.conf
.El
+.Sh EXAMPLES
+Print out the hostname associated with a specific IP address:
+.Pp
+.Bd -literal
+ const char *ipstr = "127.0.0.1";
+ struct in_addr ip;
+ struct hostent *hp;
+
+ if (!inet_aton(ipstr, &ip))
+ errx(1, "can't parse IP address %s", ipstr);
+
+ if ((hp = gethostbyaddr((const char *)&ip,
+ sizeof ip, AF_INET)) == NULL)
+ errx(1, "no name associated with %s", ipstr);
+
+ printf("name associated with %s is %s\en", ipstr, hp->h_name);
+.Ed -literal
.Sh DIAGNOSTICS
Error return status from
.Fn gethostbyname ,
@@ -243,6 +287,7 @@
for example, a mail-forwarder may be registered for this domain.
.El
.Sh SEE ALSO
+.Xr inet_aton 3 ,
.Xr resolver 3 ,
.Xr hosts 5 ,
.Xr hostname 7 ,
--
Ben Smithurst / ben@FreeBSD.org / PGP: 0x99392F7D
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