man/man3/getnetent.3

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.\"     @(#)getnetent.3 6.4 (Berkeley) 2/14/89
.\"
.TH GETNETENT 3 "February 14, 1989"
.UC 5
.SH NAME
getnetent, getnetbyaddr, getnetbyname, setnetent, endnetent \- get network entry
.SH SYNOPSIS
.nf
.ft B
#include <netdb.h>
.PP
.ft B
struct netent *getnetent()
.PP
.ft B
struct netent *getnetbyname(name)
char *name;
.PP
.ft B
struct netent *getnetbyaddr(net, type)
long net;
int type;
.PP
.ft B
setnetent(stayopen)
int stayopen;
.PP
.ft B
endnetent()
.fi
.SH DESCRIPTION
.IR Getnetent ,
.IR getnetbyname ,
and
.I getnetbyaddr
each return a pointer to an object with the
following structure
containing the broken-out
fields of a line in the network data base,
.IR /etc/networks .
.RS
.PP
.nf
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 */
};
.ft R
.ad
.fi
.RE
.PP
The members of this structure are:
.TP \w'n_addrtype'u+2n
n_name
The official name of the network.
.TP \w'n_addrtype'u+2n
n_aliases
A zero terminated list of alternate names for the network.
.TP \w'n_addrtype'u+2n
n_addrtype
The type of the network number returned; currently only AF_INET.
.TP \w'n_addrtype'u+2n
n_net
The network number.  Network numbers are returned in machine byte
order.
.PP
.I Getnetent
reads the next line of the file, opening the file if necessary.
.PP
.I Setnetent
opens and rewinds the file.  If the
.I stayopen
flag is non-zero,
the net data base will not be closed after each call to
.I getnetbyname
or
.IR getnetbyaddr .
.PP
.I Endnetent
closes the file.
.PP
.I Getnetbyname
and
.I getnetbyaddr
sequentially search from the beginning
of the file until a matching
net name or
net address and type is found,
or until EOF is encountered.
Network numbers are supplied in host order.
.SH FILES
/etc/networks
.SH "SEE ALSO"
networks(5)
.SH DIAGNOSTICS
Null pointer
(0) returned on EOF or error.
.SH BUGS
All information
is contained in a static area
so it must be copied if it is
to be saved.  Only Internet network
numbers are currently understood.
Expecting network numbers to fit
in no more than 32 bits is probably
naive.