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.Os 56.Dt REALHOSTNAME_SA 3 57.Sh NAME 58.Nm realhostname_sa 59.Nd "convert an struct sockaddr to the real host name" 60.Sh SYNOPSIS 61.Fd #include <sys/types.h> 62.Fd #include <netinet/in.h> 63.Fd #include <libutil.h> 64.Ft int 65.Fn realhostname_sa "char *host" "size_t hsize" "struct sockaddr *addr" "int addrlen" 66.Pp 67Link with 68.Va -lutil 69on the 70.Xr cc 1 71command line. 72.Sh DESCRIPTION 73The function 74.Fn realhostname_sa 75converts 76.Ar addr 77to the corresponding host name. This is done by resolving 78.Ar addr 79to a host name and then ensuring that the host name resolves 80back to 81.Ar addr . 82.Pp 83.Ar host 84must point to a buffer of at least 85.Ar hsize 86bytes, and will always be written to by this function. 87.Pp 88If the name resolution doesn't work both ways or if the host name is longer 89than 90.Ar hsize 91bytes, 92.Xr getnameinfo 3 93with NI_NUMERICHOST specified, is used to convert 94.Ar addr 95to an ASCII form. 96.Pp 97If the string written to 98.Ar host 99is 100.Ar hsize 101bytes long, 102.Ar host 103will not be NUL terminated. 104.Sh RETURN VALUES 105.Fn realhostname_sa 106will return one of the following constants which are defined in 107.Pa libutil.h : 108.Pp 109.Bl -tag -width XXX -offset XXX 110.It Li HOSTNAME_FOUND 111A valid host name was found. 112.It Li HOSTNAME_INCORRECTNAME 113A host name was found, but it did not resolve back to the passed 114.Ar ip . 115.Ar host 116now contains the numeric value of 117.Ar ip . 118.It Li HOSTNAME_INVALIDADDR 119.Ar ip 120could not be resolved. 121.Ar host 122now contains the numeric value of 123.Ar ip . 124.It Li HOSTNAME_INVALIDNAME 125A host name was found, but it could not be resolved back to any ip number. 126.Ar host 127now 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 3 134 135