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.Dd January 11, 2000 53.Dt REALHOSTNAME_SA 3 54.Os 55.Sh NAME 56.Nm realhostname_sa 57.Nd "convert a" 58.Vt "struct sockaddr" 59to the real host name 60.Sh LIBRARY 61.Lb libutil 62.Sh SYNOPSIS 63.In sys/types.h 64.In netinet/in.h 65.In libutil.h 66.Ft int 67.Fn realhostname_sa "char *host" "size_t hsize" "struct sockaddr *addr" "int addrlen" 68.Sh DESCRIPTION 69The function 70.Fn realhostname_sa 71converts 72.Ar addr 73to the corresponding host name. 74This is done by resolving 75.Ar addr 76to a host name and then ensuring that the host name resolves 77back to 78.Ar addr . 79.Pp 80.Ar host 81must point to a buffer of at least 82.Ar hsize 83bytes, and will always be written to by this function. 84.Pp 85If the name resolution does not work both ways or if the host name is longer 86than 87.Ar hsize 88bytes, 89.Xr getnameinfo 3 90with NI_NUMERICHOST specified, is used to convert 91.Ar addr 92to an ASCII form. 93.Pp 94If the string written to 95.Ar host 96is 97.Ar hsize 98bytes long, 99.Ar host 100will not be NUL terminated. 101.Sh RETURN VALUES 102The 103.Fn realhostname_sa 104function will return one of the following constants which are defined in 105.In libutil.h : 106.Bl -tag -width XXX -offset XXX 107.It Li HOSTNAME_FOUND 108A valid host name was found. 109.It Li HOSTNAME_INCORRECTNAME 110A host name was found, but it did not resolve back to the passed 111.Ar ip . 112.Ar host 113now contains the numeric value of 114.Ar ip . 115.It Li HOSTNAME_INVALIDADDR 116.Ar ip 117could not be resolved. 118.Ar host 119now contains the numeric value of 120.Ar ip . 121.It Li HOSTNAME_INVALIDNAME 122A host name was found, but it could not be resolved back to any ip number. 123.Ar host 124now contains the numeric value of 125.Ar ip . 126.El 127.Sh SEE ALSO 128.Xr getaddrinfo 3 , 129.Xr getnameinfo 3 , 130.Xr realhostname 3 131