NAME
inet_aton, inet_addr, inet_network, inet_ntoa, inet_makeaddr, inet_lnaof,
inet_netof - Internet address manipulation routines
SYNOPSIS
#include <sys/socket.h>
#include <netinet/in.h>
#include <arpa/inet.h>
I int inet_aton(const char * cp , struct in_addr * inp );
I in_addr_t inet_addr(const char * cp );
I in_addr_t inet_network(const char * cp );
I char *inet_ntoa(struct in_addr in );
I struct in_addr inet_makeaddr(int net , int host );
I in_addr_t inet_lnaof(struct in_addr in );
I in_addr_t inet_netof(struct in_addr in );
DESCRIPTION
R inet_aton ()
converts the Internet host address cp from the
standard numbers-and-dots notation into binary data and stores it in
the structure that inp points to.
R inet_aton ()
returns
non-zero if the address is valid, zero if not.
The
R inet_addr ()
function converts the Internet host address
cp from numbers-and-dots notation into binary data in network
byte order.
If the input is invalid,
INADDR_NONE
(usually -1) is returned.
This is an obsolete interface to
R inet_aton (),
described
immediately above; it is obsolete because -1 is a valid address
(255.255.255.255), and
R inet_aton ()
provides a cleaner way
to indicate error return.
The
R inet_network ()
function extracts
a number in host byte order suitable for use as an Internet address
from cp, which is a string in numbers-and-dots notation.
If the input is invalid, -1 is returned.
The
R inet_ntoa ()
function converts the Internet host address
in given in network byte order to a string in standard
numbers-and-dots notation.
The string is returned in a statically
allocated buffer, which subsequent calls will overwrite.
The
R inet_makeaddr ()
function makes an Internet host address
in network byte order by combining the network number net
with the local address host in network net, both in
local host byte order.
The
R inet_lnaof ()
function returns the local host address part
of the Internet address in.
The local host address is returned
in local host byte order.
The
R inet_netof ()
function returns the network number part of
the Internet Address in.
The network number is returned in
local host byte order.
The structure
in_addr as used in
R inet_ntoa (),
R inet_makeaddr (),
R inet_lnoaf ()
and
R inet_netof ()
is defined in
netinet/in.h as:
struct in_addr {
unsigned long int s_addr;
}
Note that on the i80x86 the host byte order is Least Significant Byte
first (little endian), whereas the network byte order, as used on the
Internet, is Most Significant Byte first (big endian).
CONFORMING TO
4.3BSD.
R inet_addr (),
R inet_aton (),
and
R inet_ntoa ()
are specified in POSIX.1-2001.
NOTES
When you using numbers-and-dots notation for addresses,
be aware that each number will be interpreted as octal
if preceded by a 0 and as hexadecimal if preceded by 0x.
For example,
inet_aton("226.000.000.037", &t) will
interpret the address as
226.0.0.31 and not
226.0.0.37.
Glibc Notes
In order to expose the declaration of
R inet_aton (),
one of the feature test macros
R _BSD_SOURCE ,
R _SVID_SOURCE ,
or
_GNU_SOURCE
must be defined.
SEE ALSO
ČLÁNKY DO MAILU