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: head/lib/libutil/realhostname_sa.3 213573 2010-10-08 12:40:16Z uqs $ 53.\" 54.Dd January 11, 2000 55.Dt REALHOSTNAME_SA 3 56.Os 57.Sh NAME 58.Nm realhostname_sa 59.Nd "convert a" 60.Vt "struct sockaddr" 61to 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 71The function 72.Fn realhostname_sa 73converts 74.Ar addr 75to the corresponding host name. 76This is done by resolving 77.Ar addr 78to a host name and then ensuring that the host name resolves 79back to 80.Ar addr . 81.Pp 82.Ar host 83must point to a buffer of at least 84.Ar hsize 85bytes, and will always be written to by this function. 86.Pp 87If the name resolution does not work both ways or if the host name is longer 88than 89.Ar hsize 90bytes, 91.Xr getnameinfo 3 92with 93.Dv NI_NUMERICHOST 94specified, is used to convert 95.Ar addr 96to an ASCII form. 97.Pp 98If the string written to 99.Ar host 100is 101.Ar hsize 102bytes long, 103.Ar host 104will not be NUL terminated. 105.Sh RETURN VALUES 106The 107.Fn realhostname_sa 108function will return one of the following constants which are defined in 109.In libutil.h : 110.Bl -tag -width ".Dv HOSTNAME_INCORRECTNAME" -offset indent 111.It Dv HOSTNAME_FOUND 112A valid host name was found. 113.It Dv HOSTNAME_INCORRECTNAME 114A host name was found, but it did not resolve back to the passed 115.Ar ip . 116.Ar host 117now contains the numeric value of 118.Ar ip . 119.It Dv HOSTNAME_INVALIDADDR 120.Ar ip 121could not be resolved. 122.Ar host 123now contains the numeric value of 124.Ar ip . 125.It Dv HOSTNAME_INVALIDNAME 126A host name was found, but it could not be resolved back to any ip number. 127.Ar host 128now contains the numeric value of 129.Ar ip . 130.El 131.Sh SEE ALSO 132.Xr getaddrinfo 3 , 133.Xr getnameinfo 3 , 134.Xr realhostname 3 135