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.\"     @(#)getnetent.3 8.1 (Berkeley) 6/4/93

.\"     $Id: getnetent.3,v 1.2 2001-09-27 12:01:53 chris Exp $

.\"

.Dd June 4, 1993

.Dt GETNETENT 3

.Os BSD 4.2

.Sh NAME

.Nm getnetent ,

.Nm getnetbyaddr ,

.Nm getnetbyname ,

.Nm setnetent ,

.Nm endnetent

.Nd get network entry

.Sh SYNOPSIS

.Fd #include 

.Ft struct netent *

.Fn getnetent void

.Ft struct netent *

.Fn getnetbyname "const char *name"

.Ft struct netent *

.Fn getnetbyaddr "unsigned long net" "int type"

.Ft void

.Fn setnetent "int stayopen"

.Ft void

.Fn endnetent void

.Sh DESCRIPTION

The

.Fn getnetent ,

.Fn getnetbyname ,

and

.Fn getnetbyaddr

functions

each return a pointer to an object with the

following structure

containing the broken-out

fields of a line in the network data base,

.Pa /etc/networks .

.Bd -literal -offset indent

struct  netent {

        char            *n_name;        /* official name of net */

        char            **n_aliases;    /* alias list */

        int             n_addrtype;     /* net number type */

        unsigned long   n_net;          /* net number */

};

.Ed

.Pp

The members of this structure are:

.Bl -tag -width n_addrtype

.It Fa n_name

The official name of the network.

.It Fa n_aliases

A zero terminated list of alternate names for the network.

.It Fa n_addrtype

The type of the network number returned; currently only AF_INET.

.It Fa n_net

The network number.  Network numbers are returned in machine byte

order.

.El

.Pp

The

.Fn getnetent

function

reads the next line of the file, opening the file if necessary.

.Pp

The

.Fn setnetent

function

opens and rewinds the file.  If the

.Fa stayopen

flag is non-zero,

the net data base will not be closed after each call to

.Fn getnetbyname

or

.Fn getnetbyaddr .

.Pp

The

.Fn endnetent

function

closes the file.

.Pp

The

.Fn getnetbyname

function

and

.Fn getnetbyaddr

sequentially search from the beginning

of the file until a matching

net name or

net address and type is found,

or until

.Dv EOF

is encountered. The

.Fa type

must be

.Dv AF_INET .

Network numbers are supplied in host order.

.Sh FILES

.Bl -tag -width /etc/networks -compact

.It Pa /etc/networks

.El

.Sh DIAGNOSTICS

Null pointer

(0) returned on

.Dv EOF

or error.

.Sh SEE ALSO

.Xr networks 5

.Pp

.%T RFC 1101

.Sh HISTORY

The

.Fn getnetent ,

.Fn getnetbyaddr ,

.Fn getnetbyname ,

.Fn setnetent ,

and

.Fn endnetent

functions appeared in

.Bx 4.2 .

.Sh BUGS

The data space used by

these functions is static; if future use requires the data, it should be

copied before any subsequent calls to these functions overwrite it.

Only Internet network

numbers are currently understood.

Expecting network numbers to fit

in no more than 32 bits is probably

naive.