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\" Id: getnetent.man3,v 1.2 2009/01/21 00:12:34 each Exp
\"
Dd May 20, 1996
Dt GETNETENT 3
Os BSD 4
Sh NAME
Nm getnetent ,
Nm getnetbyaddr ,
Nm getnetbyname ,
Nm setnetent ,
Nm endnetent
Nd get networks entry
Sh SYNOPSIS
Fd #include <netdb.h>
Ft struct netent *
Fn getnetent
Ft struct netent *
Fn getnetbyname "char name"
Ft struct netent *
Fn getnetbyaddr "unsigned long net" "int type"
Ft void
Fn setnetent "int stayopen"
Ft void
Fn endnetent
Sh DESCRIPTION
The
Fn getnetent ,
Fn getnetbyname ,
and
Fn getnetbyaddr
subroutines
each return a pointer to an object with the following structure
containing the broken-out fields of a line in the
Pa networks
database.
Bd -literal -offset indent
struct netent {
char *n_name; /* official name of net */
char **n_aliases; /* alias list */
int n_addrtype; /* net number type */
long n_net; /* net number */
};
Ed
Pp
The members of this structure are:
Bl -tag -width "n_addrtype"
It n_name
The official name of the network.
It n_aliases
A zero-terminated list of alternate names for the network.
It n_addrtype
The type of the network number returned:
Dv AF_INET .
It n_net
The network number. Network numbers are returned in machine byte
order.
El
Pp
If the
Fa stayopen
flag on a
Fn setnetent
subroutine is NULL, the
Pa networks
database is opened. Otherwise, the
Fn setnetent
has the effect of rewinding the
Pa networks
database.
The
Fn endnetent
subroutine may be called to
close the
Pa networks
database when processing is complete.
Pp
The
Fn getnetent
subroutine simply reads the next
line while
Fn getnetbyname
and
Fn getnetbyaddr
search until a matching
Fa name
or
Fa net
number is found
(or until
Dv EOF
is encountered). The
Fa type must be
Dv AF_INET .
The
Fn getnetent
subroutine keeps a pointer in the database, allowing
successive calls to be used to search the entire file.
Pp
Before a
Ic while
loop using
Fn getnetent ,
a call to
Fn setnetent
must be made
in order to perform initialization; a call to
Fn endnetent
must be used after the loop. Both
Fn getnetbyname
and
Fn getnetbyaddr
make calls to
Fn setnetent
and
Fn endnetent .
Sh FILES
Pa /etc/networks
Sh DIAGNOSTICS
Null pointer (0) returned on
Dv EOF
or error.
Sh SEE ALSO
Xr networks 5 ,
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.
