NAME
endnetent, getnetbyaddr, getnetbyname, getnetent, setnetent - network
database functions
SYNOPSIS
#include <netdb.h>
void endnetent(void);
struct netent *getnetbyaddr(uint32_t net, int type);
struct netent *getnetbyname(const char *name);
struct netent *getnetent(void);
void setnetent(int stayopen);
DESCRIPTION
These functions shall retrieve information about networks. This
information is considered to be stored in a database that can be
accessed sequentially or randomly. The implementation of this database
is unspecified.
The setnetent() function shall open and rewind the database. If the
stayopen argument is non-zero, the connection to the net database shall
not be closed after each call to getnetent() (either directly, or
indirectly through one of the other getnet*() functions), and the
implementation may maintain an open file descriptor to the database.
The getnetent() function shall read the next entry of the database,
opening and closing a connection to the database as necessary.
The getnetbyaddr() function shall search the database from the
beginning, and find the first entry for which the address family
specified by type matches the n_addrtype member and the network number
net matches the n_net member, opening and closing a connection to the
database as necessary. The net argument shall be the network number in
host byte order.
The getnetbyname() function shall search the database from the
beginning and find the first entry for which the network name specified
by name matches the n_name member, opening and closing a connection to
the database as necessary.
The getnetbyaddr(), getnetbyname(), and getnetent() functions shall
each return a pointer to a netent structure, the members of which shall
contain the fields of an entry in the network database.
The endnetent() function shall close the database, releasing any open
file descriptor.
These functions need not be reentrant. A function that is not required
to be reentrant is not required to be thread-safe.
RETURN VALUE
Upon successful completion, getnetbyaddr(), getnetbyname(), and
getnetent() shall return a pointer to a netent structure if the
requested entry was found, and a null pointer if the end of the
database was reached or the requested entry was not found. Otherwise, a
null pointer shall be returned.
ERRORS
No errors are defined.
The following sections are informative.
EXAMPLES
None.
APPLICATION USAGE
The getnetbyaddr(), getnetbyname(), and getnetent() functions may
return pointers to static data, which may be overwritten by subsequent
calls to any of these functions.
RATIONALE
None.
FUTURE DIRECTIONS
None.
SEE ALSO
The Base Definitions volume of IEEE Std 1003.1-2001, <netdb.h>
COPYRIGHT
Portions of this text are reprinted and reproduced in electronic form
from IEEE Std 1003.1, 2003 Edition, Standard for Information Technology
-- Portable Operating System Interface (POSIX), The Open Group Base
Specifications Issue 6, Copyright (C) 2001-2003 by the Institute of
Electrical and Electronics Engineers, Inc and The Open Group. In the
event of any discrepancy between this version and the original IEEE and
The Open Group Standard, the original IEEE and The Open Group Standard
is the referee document. The original Standard can be obtained online
at http://www.opengroup.org/unix/online.html .