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.Dd March 13, 1997

.Dt GETNETENT 3

.Os

.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 "char *name"

.Ft struct netent *

.Fn getnetbyaddr "in_addr_t 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 database,

.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 */

        in_addr_t       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

.Dv 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 database 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

and

.Fn getnetbyaddr

functions search the domain name server if the system is configured to use one.

If the search fails, or no name server is configured, they 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.

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 resolver 3 ,

.Xr networks 5

.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 naive.