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.\" $FreeBSD$ 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 NI_NUMERICHOST specified, is used to convert 93.Ar addr 94to an ASCII form. 95.Pp 96If the string written to 97.Ar host 98is 99.Ar hsize 100bytes long, 101.Ar host 102will not be NUL terminated. 103.Sh RETURN VALUES 104The 105.Fn realhostname_sa 106function will return one of the following constants which are defined in 107.In libutil.h : 108.Bl -tag -width XXX -offset XXX 109.It Li HOSTNAME_FOUND 110A valid host name was found. 111.It Li HOSTNAME_INCORRECTNAME 112A host name was found, but it did not resolve back to the passed 113.Ar ip . 114.Ar host 115now contains the numeric value of 116.Ar ip . 117.It Li HOSTNAME_INVALIDADDR 118.Ar ip 119could not be resolved. 120.Ar host 121now contains the numeric value of 122.Ar ip . 123.It Li HOSTNAME_INVALIDNAME 124A host name was found, but it could not be resolved back to any ip number. 125.Ar host 126now contains the numeric value of 127.Ar ip . 128.El 129.Sh SEE ALSO 130.Xr getaddrinfo 3 , 131.Xr getnameinfo 3 , 132.Xr realhostname 3 133