getnetent
Section: C Library Functions (3)
Updated: 202-0-08
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NAME
getnetent, getnetbyname, getnetbyaddr, setnetent, endnetent -
get network entry
LIBRARY
Standard C library
(
libc,~
-lc)
SYNOPSIS
#include <netdb.h>
struct netent *getnetent(void);
struct netent *getnetbyname(const char *name);
struct netent *getnetbyaddr(uint32_t net, int type);
void setnetent(int stayopen);
void endnetent(void);
DESCRIPTION
The
getnetent()
function reads the next entry from the networks database
and returns a
netent
structure containing
the broke-out fields from the entry.
A connection is opened to the database if necessary.
The
getnetbyname()
function returns a
netent
structure
for the entry from the database
that matches the network
name.
The
getnetbyaddr()
function returns a
netent
structure
for the entry from the database
that matches the network number
net
of type
type.
The
net
argument must be in host byte order.
The
setnetent()
function opens a connection to the database,
and sets the next entry to the first entry.
If
stayopen
is nonzero,
then the connection to the database
will not be closed between calls to one of the
getnet*()
functions.
The
endnetent()
function closes the connection to the database.
The
netent
structure is defined in
<netdb.h>
as follows:
struct netent {
char *n_name; /* official network name */
char **n_aliases; /* alias list */
int n_addrtype; /* net address type */
uint32_t n_net; /* network number */
}
The members of the
netent
structure are:
- n_name
-
The official name of the network.
- n_aliases
-
A NUL-terminated list of alternative names for the network.
- n_addrtype
-
The type of the network number;
always
AF_INET.
- n_net
-
The network number in host byte order.
RETURN VALUE
The
getnetent(),
getnetbyname(),
and
getnetbyaddr()
functions return a pointer to a
statically allocated
netent
structure, or a null pointer if an
error occurs or the end of the file is reached.
FILES
- /etc/networks
-
networks database file
ATTRIBUTES
For an explanation of the terms used in this section, see
attributes(7).
| Interface | Attribute | Value
|
|
getnetent()
| Thread safety |
M-Unsafe race:netent
race:netentbuf env locale
|
|
getnetbyname()
| Thread safety |
M-Unsafe race:netbyname
env locale
|
|
getnetbyaddr()
| Thread safety |
M-Unsafe race:netbyaddr
locale
|
|
setnetent(),
endnetent()
| Thread safety |
M-Unsafe race:netent env
locale
|
In the above table,
netent
in
race:netent
signifies that if any of the functions
setnetent(),
getnetent(),
or
endnetent()
are used in parallel in different threads of a program,
then data races could occur.
STANDARDS
POSIX.-2008.
HISTORY
POSIX.-2001, 4.3BSD.
Before glibc 2.2, the
net
argument of
getnetbyaddr()
was of type
long.
SEE ALSO
getnetent_r(3),
getprotoent(3),
getservent(3)
RFC 1101
Index
- NAME
-
- LIBRARY
-
- SYNOPSIS
-
- DESCRIPTION
-
- RETURN VALUE
-
- FILES
-
- ATTRIBUTES
-
- STANDARDS
-
- HISTORY
-
- SEE ALSO
-
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|
- Running on 
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