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[dragonfly.git] / lib / libutil / realhostname.3
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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 1.4.2.2 2001/12/17 10:08:32 ru Exp $
44cb301e 26.\" $DragonFly: src/lib/libutil/realhostname.3,v 1.3 2006/05/26 19:39:38 swildner Exp $
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27.\"
28.Dd April 6, 1999
29.Os
30.Dt REALHOSTNAME 3
31.Sh NAME
32.Nm realhostname
33.Nd "convert an IP number to the real host name"
34.Sh LIBRARY
35.Lb libutil
36.Sh SYNOPSIS
37.In sys/types.h
38.In netinet/in.h
39.In libutil.h
40.Ft int
41.Fn realhostname "char *host" "size_t hsize" "const struct in_addr *ip"
42.Sh DESCRIPTION
43The function
44.Fn realhostname
45converts
46.Ar ip
47to the corresponding host name. This is done by resolving
48.Ar ip
49to a host name and then ensuring that the host name resolves
50back to
51.Ar ip .
52.Pp
53.Ar host
54must point to a buffer of at least
55.Ar hsize
56bytes, and will always be written to by this function.
57.Pp
58If the name resolution doesn't work both ways or if the host name is longer
59than
60.Ar hsize
61bytes,
62.Xr inet_ntoa 3
63is used to convert
64.Ar ip
65to an ASCII form.
66.Pp
67If the string written to
68.Ar host
69is
70.Ar hsize
71bytes long,
72.Ar host
73will not be NUL terminated.
74.Sh RETURN VALUES
75.Fn realhostname
76will return one of the following constants which are defined in
44cb301e 77.In libutil.h :
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78.Pp
79.Bl -tag -width XXX -offset XXX
80.It Li HOSTNAME_FOUND
81A valid host name was found.
82.It Li HOSTNAME_INCORRECTNAME
83A host name was found, but it did not resolve back to the passed
84.Ar ip .
85.Ar host
86now contains the numeric value of
87.Ar ip .
88.It Li HOSTNAME_INVALIDADDR
89.Ar ip
90could not be resolved.
91.Ar host
92now contains the numeric value of
93.Ar ip .
94.It Li HOSTNAME_INVALIDNAME
95A host name was found, but it could not be resolved back to any ip number.
96.Ar host
97now contains the numeric value of
98.Ar ip .
99.El
100.Sh SEE ALSO
101.Xr gethostbyaddr 3 ,
102.Xr gethostbyname 3 ,
103.Xr inet_ntoa 3 ,
104.Xr realhostname_sa 3