[apple/libutil.git] / realhostname_sa.3

.\" Copyright (C) 1995, 1996, 1997, 1998, 1999, and 2000 WIDE Project.
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.\" 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_sa.3,v 1.11 2005/02/13 22:25:14 ru Exp $
.\"
.Dd January 11, 2000
.Os
.Dt REALHOSTNAME_SA 3
.Sh NAME
.Nm realhostname_sa
.Nd "convert a"
.Vt "struct sockaddr"
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_sa "char *host" "size_t hsize" "struct sockaddr *addr" "int addrlen"
.Sh DESCRIPTION
The function
.Fn realhostname_sa
converts
.Ar addr
to the corresponding host name.
This is done by resolving
.Ar addr
to a host name and then ensuring that the host name resolves
back to
.Ar addr .
.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 getnameinfo 3
with NI_NUMERICHOST specified, is used to convert
.Ar addr
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_sa
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 getaddrinfo 3 ,
.Xr getnameinfo 3 ,
.Xr realhostname 3
Commit	Line	Data
3f2457aa A	1	.\" Copyright (C) 1995, 1996, 1997, 1998, 1999, and 2000 WIDE Project.
	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	.\" 3. Neither the name of the project nor the names of its contributors
	13	.\" may be used to endorse or promote products derived from this software
	14	.\" without specific prior written permission.
	15	.\"
	16	.\" THIS SOFTWARE IS PROVIDED BY THE PROJECT AND CONTRIBUTORS ``AS IS'' AND
	17	.\" ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
	18	.\" IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
	19	.\" ARE DISCLAIMED. IN NO EVENT SHALL THE PROJECT OR CONTRIBUTORS BE LIABLE
	20	.\" FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
	21	.\" DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
	22	.\" OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
	23	.\" HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
	24	.\" LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
	25	.\" OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
	26	.\" SUCH DAMAGE.
	27	.\"
	28	.\" Copyright (c) 1999 Brian Somers <brian@Awfulhak.org>
	29	.\" All rights reserved.
	30	.\"
	31	.\" Redistribution and use in source and binary forms, with or without
	32	.\" modification, are permitted provided that the following conditions
	33	.\" are met:
	34	.\" 1. Redistributions of source code must retain the above copyright
	35	.\" notice, this list of conditions and the following disclaimer.
	36	.\" 2. Redistributions in binary form must reproduce the above copyright
	37	.\" notice, this list of conditions and the following disclaimer in the
	38	.\" documentation and/or other materials provided with the distribution.
	39	.\"
	40	.\" THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
	41	.\" ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
	42	.\" IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
	43	.\" ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
	44	.\" FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
	45	.\" DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
	46	.\" OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
	47	.\" HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
	48	.\" LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
	49	.\" OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
	50	.\" SUCH DAMAGE.
	51	.\"
	52	.\" $FreeBSD: src/lib/libutil/realhostname_sa.3,v 1.11 2005/02/13 22:25:14 ru Exp $
	53	.\"
	54	.Dd January 11, 2000
	55	.Os
	56	.Dt REALHOSTNAME_SA 3
	57	.Sh NAME
	58	.Nm realhostname_sa
	59	.Nd "convert a"
	60	.Vt "struct sockaddr"
	61	to the real host name
	62	.Sh LIBRARY
	63	.Lb libutil
	64	.Sh SYNOPSIS
65	.In sys/types.h
66	.In netinet/in.h
67	.In libutil.h
68	.Ft int
69	.Fn realhostname_sa "char host" "size_t hsize" "struct sockaddr addr" "int addrlen"
70	.Sh DESCRIPTION
71	The function
72	.Fn realhostname_sa
73	converts
74	.Ar addr
75	to the corresponding host name.
76	This is done by resolving
77	.Ar addr
78	to a host name and then ensuring that the host name resolves
79	back to
80	.Ar addr .
81	.Pp
82	.Ar host
83	must point to a buffer of at least
84	.Ar hsize
85	bytes, and will always be written to by this function.
86	.Pp
87	If the name resolution does not work both ways or if the host name is longer
88	than
89	.Ar hsize
90	bytes,
91	.Xr getnameinfo 3
92	with NI_NUMERICHOST specified, is used to convert
93	.Ar addr
94	to an ASCII form.
95	.Pp
96	If the string written to
97	.Ar host
98	is
99	.Ar hsize
100	bytes long,
101	.Ar host
102	will not be NUL terminated.
103	.Sh RETURN VALUES
104	The
105	.Fn realhostname_sa
106	function will return one of the following constants which are defined in
107	.In libutil.h :
108	.Pp
109	.Bl -tag -width XXX -offset XXX
110	.It Li HOSTNAME_FOUND
111	A valid host name was found.
112	.It Li HOSTNAME_INCORRECTNAME
113	A host name was found, but it did not resolve back to the passed
114	.Ar ip .
115	.Ar host
116	now contains the numeric value of
117	.Ar ip .
118	.It Li HOSTNAME_INVALIDADDR
119	.Ar ip
120	could not be resolved.
121	.Ar host
122	now contains the numeric value of
123	.Ar ip .
124	.It Li HOSTNAME_INVALIDNAME
125	A host name was found, but it could not be resolved back to any ip number.
126	.Ar host
127	now contains the numeric value of
128	.Ar ip .
129	.El
130	.Sh SEE ALSO
131	.Xr getaddrinfo 3 ,
132	.Xr getnameinfo 3 ,
133	.Xr realhostname 3