NAME
getnetent,
getnetbyaddr, getnetbyname,
setnetent, endnetent
— get network entry
SYNOPSIS
#include
<netdb.h>
struct netent *
getnetent(void);
struct netent *
getnetbyname(const
char *name);
struct netent *
getnetbyaddr(in_addr_t
net, int type);
void
setnetent(int
stayopen);
void
endnetent(void);
DESCRIPTION
The
getnetent(),
getnetbyname(), and
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, /etc/networks.
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 */
};
The members of this structure are:
- n_name
- The official name of the network.
- n_aliases
- A null-terminated list of alternate names for the network.
- n_addrtype
- The type of the network number returned; currently only
AF_INET. - 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 stayopen
flag is non-zero, the net database will not be closed after each call to
getnetbyname() or
getnetbyaddr().
The
endnetent()
function closes the file.
The
getnetbyname()
and
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 EOF is
encountered. Network numbers are supplied in host order.
FILES
- /etc/networks
DIAGNOSTICS
Null pointer (0) returned on EOF or
error.
SEE ALSO
HISTORY
The getnetent(),
getnetbyaddr(),
getnetbyname(), setnetent(),
and endnetent() functions appeared in
4.2BSD.
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.