The
getnetent (,);
getnetbyname (,);
and
getnetbyaddr ();
functions
each return a pointer to an object with the
following structure describing an internet network.
This structure contains either the information obtained
from the nameserver,
named(8),
broken-out fields of a line in the network data base
/etc/networks
or entries supplied by the
yp(8)
system.
The order of the lookups is controlled by the
`networks' entry in
nsswitch.conf5.
struct netent {
char *n_name; /* official name of net */
char **n_aliases; /* alias list */
int n_addrtype; /* net number type */
uint32_t n_net; /* net number */
};
The members of this structure are:
Fa n_name
The official name of the network.
Fa n_aliases
A zero terminated list of alternate names for the network.
Fa n_addrtype
The type of the network number returned; currently only AF_INET.
Fa n_net
The network number.
Network numbers are returned in machine byte
order.
The
getnetent ();
function
reads the next line of the file, opening the file if necessary.
The
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
getnetbyname ();
or
getnetbyaddr (.);
The
endnetent ();
function
closes the file.
The
getnetbyname ();
function
and
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.
The
Fa type
argument
must be
AF_INET
Network numbers are supplied in host order.
The
getnetent (,);
getnetbyaddr (,);
getnetbyname (,);
setnetent (,);
and
endnetent ();
functions appeared in
BSD 4.2
BUGS
The data space used by
these functions is thread-specific; 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.
