inet_net(3)

NAME

inet_net_ntop, inet_net_pton - Internet network number ma

nipulation routines

LIBRARY

Standard C Library (libc, -lc)

SYNOPSIS

#include <sys/types.h>
#include <sys/socket.h>
#include <netinet/in.h>
#include <arpa/inet.h>
char *
inet_net_ntop(int  af, const void *src, int bits, char *dst,
size_t size);
int
inet_net_pton(int af, const char  *src,  void  *dst,  size_t
size);

DESCRIPTION

The inet_net_ntop() function converts an Internet network

number from
network format (usually a struct in_addr or some other bina

ry form, in
network byte order) to CIDR presentation format (suitable

for external
display purposes). The bits argument is the number of bits

in src that
are the network number. It returns NULL if a system error

occurs (in
which case, errno will have been set), or it returns a

pointer to the
destination string.

The inet_net_pton() function converts a presentation format

Internet network number (that is, printable form as held in a character

string) to
network format (usually a struct in_addr or some other in

ternal binary
representation, in network byte order). It returns the num

ber of bits
(either computed based on the class, or specified with

/CIDR), or -1 if a
failure occurred (in which case errno will have been set.

It will be set
to ENOENT if the Internet network number was not valid).

The currently supported values for af are AF_INET and AF_IN

ET6. The size
argument is the size of the result buffer dst.

NETWORK NUMBERS (IP VERSION 4)

Internet network numbers may be specified in one of the fol

lowing forms:

a.b.c.d/bits
a.b.c.d
a.b.c
a.b
a

When four parts are specified, each is interpreted as a byte

of data and
assigned, from left to right, to the four bytes of an Inter

net network
number. Note that when an Internet network number is viewed

as a 32-bit
integer quantity on a system that uses little-endian byte

order (such as
the Intel 386, 486, and Pentium processors) the bytes re

ferred to above
appear as ``d.c.b.a''. That is, little-endian bytes are or

dered from
right to left.

When a three part number is specified, the last part is in

terpreted as a
16-bit quantity and placed in the rightmost two bytes of the

Internet
network number. This makes the three part number format

convenient for
specifying Class B network numbers as ``128.net.host''.

When a two part number is supplied, the last part is inter

preted as a
24-bit quantity and placed in the rightmost three bytes of

the Internet
network number. This makes the two part number format con

venient for
specifying Class A network numbers as ``net.host''.

When only one part is given, the value is stored directly in

the Internet
network number without any byte rearrangement.

All numbers supplied as ``parts'' in a `.' notation may be

decimal,
octal, or hexadecimal, as specified in the C language (i.e.,

a leading 0x
or 0X implies hexadecimal; otherwise, a leading 0 implies

octal; otherwise, the number is interpreted as decimal).

SEE ALSO

byteorder(3), inet(3), networks(5)

HISTORY

The inet_net_ntop() and inet_net_pton() functions appeared

in BIND 4.9.4.

BSD February 26, 2006

BSD