[apple/libutil.git] / realhostname.3

.\" Copyright (c) 1999 Brian Somers <brian@Awfulhak.org>
.\" All rights reserved.
.\"
.\" Redistribution and use in source and binary forms, with or without
.\" modification, are permitted provided that the following conditions
.\" are met:
.\" 1. Redistributions of source code must retain the above copyright
.\"    notice, this list of conditions and the following disclaimer.
.\" 2. Redistributions in binary form must reproduce the above copyright
.\"    notice, this list of conditions and the following disclaimer in the
.\"    documentation and/or other materials provided with the distribution.
.\"
.\" THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
.\" ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
.\" IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
.\" ARE DISCLAIMED.  IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
.\" FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
.\" DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
.\" OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
.\" HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
.\" LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
.\" OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
.\" SUCH DAMAGE.
.\"
.\" $FreeBSD: src/lib/libutil/realhostname.3,v 1.10 2005/02/13 22:25:14 ru Exp $
.\"
.Dd April 6, 1999
.Os
.Dt REALHOSTNAME 3
.Sh NAME
.Nm realhostname
.Nd "convert an IP number to the real host name"
.Sh LIBRARY
.Lb libutil
.Sh SYNOPSIS
.In sys/types.h
.In netinet/in.h
.In libutil.h
.Ft int
.Fn realhostname "char *host" "size_t hsize" "const struct in_addr *ip"
.Sh DESCRIPTION
The function
.Fn realhostname
converts
.Ar ip
to the corresponding host name.
This is done by resolving
.Ar ip
to a host name and then ensuring that the host name resolves
back to
.Ar ip .
.Pp
.Ar host
must point to a buffer of at least
.Ar hsize
bytes, and will always be written to by this function.
.Pp
If the name resolution does not work both ways or if the host name is longer
than
.Ar hsize
bytes,
.Xr inet_ntoa 3
is used to convert
.Ar ip
to an ASCII form.
.Pp
If the string written to
.Ar host
is
.Ar hsize
bytes long,
.Ar host
will not be NUL terminated.
.Sh RETURN VALUES
The
.Fn realhostname
function will return one of the following constants which are defined in
.In libutil.h :
.Pp
.Bl -tag -width XXX -offset XXX
.It Li HOSTNAME_FOUND
A valid host name was found.
.It Li HOSTNAME_INCORRECTNAME
A host name was found, but it did not resolve back to the passed
.Ar ip .
.Ar host
now contains the numeric value of
.Ar ip .
.It Li HOSTNAME_INVALIDADDR
.Ar ip
could not be resolved.
.Ar host
now contains the numeric value of
.Ar ip .
.It Li HOSTNAME_INVALIDNAME
A host name was found, but it could not be resolved back to any ip number.
.Ar host
now contains the numeric value of
.Ar ip .
.El
.Sh SEE ALSO
.Xr gethostbyaddr 3 ,
.Xr gethostbyname 3 ,
.Xr inet_ntoa 3 ,
.Xr realhostname_sa 3
Commit	Line	Data
3f2457aa A	1	.\" Copyright (c) 1999 Brian Somers <brian@Awfulhak.org>
	2	.\" All rights reserved.
	3	.\"
	4	.\" Redistribution and use in source and binary forms, with or without
	5	.\" modification, are permitted provided that the following conditions
	6	.\" are met:
	7	.\" 1. Redistributions of source code must retain the above copyright
	8	.\" notice, this list of conditions and the following disclaimer.
	9	.\" 2. Redistributions in binary form must reproduce the above copyright
	10	.\" notice, this list of conditions and the following disclaimer in the
	11	.\" documentation and/or other materials provided with the distribution.
	12	.\"
	13	.\" THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
	14	.\" ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
	15	.\" IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
	16	.\" ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
	17	.\" FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
	18	.\" DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
	19	.\" OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
	20	.\" HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
	21	.\" LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
	22	.\" OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
	23	.\" SUCH DAMAGE.
	24	.\"
	25	.\" $FreeBSD: src/lib/libutil/realhostname.3,v 1.10 2005/02/13 22:25:14 ru Exp $
	26	.\"
	27	.Dd April 6, 1999
	28	.Os
	29	.Dt REALHOSTNAME 3
	30	.Sh NAME
	31	.Nm realhostname
	32	.Nd "convert an IP number to the real host name"
	33	.Sh LIBRARY
	34	.Lb libutil
	35	.Sh SYNOPSIS
	36	.In sys/types.h
	37	.In netinet/in.h
	38	.In libutil.h
	39	.Ft int
	40	.Fn realhostname "char host" "size_t hsize" "const struct in_addr ip"
	41	.Sh DESCRIPTION
	42	The function
	43	.Fn realhostname
	44	converts
	45	.Ar ip
	46	to the corresponding host name.
	47	This is done by resolving
	48	.Ar ip
	49	to a host name and then ensuring that the host name resolves
	50	back to
	51	.Ar ip .
	52	.Pp
	53	.Ar host
	54	must point to a buffer of at least
	55	.Ar hsize
	56	bytes, and will always be written to by this function.
	57	.Pp
	58	If the name resolution does not work both ways or if the host name is longer
	59	than
	60	.Ar hsize
	61	bytes,
	62	.Xr inet_ntoa 3
	63	is used to convert
	64	.Ar ip
65	to an ASCII form.
66	.Pp
67	If the string written to
68	.Ar host
69	is
70	.Ar hsize
71	bytes long,
72	.Ar host
73	will not be NUL terminated.
74	.Sh RETURN VALUES
75	The
76	.Fn realhostname
77	function will return one of the following constants which are defined in
78	.In libutil.h :
79	.Pp
80	.Bl -tag -width XXX -offset XXX
81	.It Li HOSTNAME_FOUND
82	A valid host name was found.
83	.It Li HOSTNAME_INCORRECTNAME
84	A host name was found, but it did not resolve back to the passed
85	.Ar ip .
86	.Ar host
87	now contains the numeric value of
88	.Ar ip .
89	.It Li HOSTNAME_INVALIDADDR
90	.Ar ip
91	could not be resolved.
92	.Ar host
93	now contains the numeric value of
94	.Ar ip .
95	.It Li HOSTNAME_INVALIDNAME
96	A host name was found, but it could not be resolved back to any ip number.
97	.Ar host
98	now contains the numeric value of
99	.Ar ip .
100	.El
101	.Sh SEE ALSO
102	.Xr gethostbyaddr 3 ,
103	.Xr gethostbyname 3 ,
104	.Xr inet_ntoa 3 ,
105	.Xr realhostname_sa 3