1.\" $OpenBSD: getnetent.3,v 1.15 2007/05/31 19:19:30 jmc Exp $ 2.\" 3.\" Copyright (c) 1983, 1991, 1993 4.\" The Regents of the University of California. All rights reserved. 5.\" 6.\" Redistribution and use in source and binary forms, with or without 7.\" modification, are permitted provided that the following conditions 8.\" are met: 9.\" 1. Redistributions of source code must retain the above copyright 10.\" notice, this list of conditions and the following disclaimer. 11.\" 2. Redistributions in binary form must reproduce the above copyright 12.\" notice, this list of conditions and the following disclaimer in the 13.\" documentation and/or other materials provided with the distribution. 14.\" 3. Neither the name of the University nor the names of its contributors 15.\" may be used to endorse or promote products derived from this software 16.\" without specific prior written permission. 17.\" 18.\" THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND 19.\" ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 20.\" IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 21.\" ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE 22.\" FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 23.\" DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 24.\" OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 25.\" HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 26.\" LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 27.\" OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 28.\" SUCH DAMAGE. 29.\" 30.Dd $Mdocdate: May 31 2007 $ 31.Dt GETNETENT 3 32.Os 33.Sh NAME 34.Nm getnetent , 35.Nm getnetbyaddr , 36.Nm getnetbyname , 37.Nm setnetent , 38.Nm endnetent 39.Nd get network entry 40.Sh SYNOPSIS 41.Fd #include <netdb.h> 42.Ft struct netent * 43.Fn getnetent "void" 44.Ft struct netent * 45.Fn getnetbyname "const char *name" 46.Ft struct netent * 47.Fn getnetbyaddr "in_addr_t net" "int type" 48.Ft void 49.Fn setnetent "int stayopen" 50.Ft void 51.Fn endnetent "void" 52.Sh DESCRIPTION 53The 54.Fn getnetent , 55.Fn getnetbyname , 56and 57.Fn getnetbyaddr 58functions each return a pointer to an object with the following structure 59containing the broken-out fields of a line in the network database, 60.Pa /etc/networks . 61.Bd -literal -offset indent 62struct netent { 63 char *n_name; /* official name of net */ 64 char **n_aliases; /* alias list */ 65 int n_addrtype; /* net number type */ 66 in_addr_t n_net; /* net number */ 67}; 68.Ed 69.Pp 70The members of this structure are: 71.Bl -tag -width n_addrtype 72.It Fa n_name 73The official name of the network. 74.It Fa n_aliases 75A null-terminated list of alternate names for the network. 76.It Fa n_addrtype 77The type of the network number returned; currently only 78.Dv AF_INET . 79.It Fa n_net 80The network number. 81Network numbers are returned in machine byte order. 82.El 83.Pp 84The 85.Fn getnetent 86function reads the next line of the file, opening the file if necessary. 87.Pp 88The 89.Fn setnetent 90function opens and rewinds the file. 91If the 92.Fa stayopen 93flag is non-zero, 94the net database will not be closed after each call to 95.Fn getnetbyname 96or 97.Fn getnetbyaddr . 98.Pp 99The 100.Fn endnetent 101function closes the file. 102.Pp 103The 104.Fn getnetbyname 105and 106.Fn getnetbyaddr 107functions search the domain name server if the system is configured to use one. 108If the search fails, or no name server is configured, they sequentially 109search from the beginning of the file until a matching net name or 110net address and type is found, or until 111.Dv EOF 112is encountered. 113Network numbers are supplied in host order. 114.Sh FILES 115.Bl -tag -width /etc/networks -compact 116.It Pa /etc/networks 117.El 118.Sh DIAGNOSTICS 119Null pointer (0) returned on 120.Dv EOF 121or error. 122.Sh SEE ALSO 123.Xr resolver 3 , 124.Xr networks 5 125.Sh HISTORY 126The 127.Fn getnetent , 128.Fn getnetbyaddr , 129.Fn getnetbyname , 130.Fn setnetent , 131and 132.Fn endnetent 133functions appeared in 134.Bx 4.2 . 135.Sh BUGS 136The data space used by these functions is static; if future use 137requires the data, it should be copied before any subsequent calls 138to these functions overwrite it. 139Only Internet network numbers are currently understood. 140Expecting network numbers to fit in no more than 32 bits is naive. 141