NAME
inet_net_ntop,
inet_net_pton —
Internet network number manipulation routines
LIBRARY
Standard C Library (libc, -lc)
SYNOPSIS
#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 binary 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 an 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 internal binary representation, in network byte order). It returns
the number 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).
The currently supported values for
af are
AF_INET
and
AF_INET6
. 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 following 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 Internet 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 referred to above appear as
“
d.c.b.a
”. That is, little-endian bytes
are ordered from right to left.
When a three part number is specified, the last part is interpreted 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 interpreted as a 24-bit
quantity and placed in the rightmost three bytes of the Internet network
number. This makes the two part number format convenient 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).
ERRORS
The
inet_net_ntop() and
inet_net_pton()
functions may fail with
-
-
- [
EAFNOSUPPORT
]
- The value of af was not
AF_INET
or AF_INET6
.
-
-
- [
EMSGSIZE
]
- The conversion of src overflows
size of dst.
The
inet_net_ntop() function may fail with
-
-
- [
EINVAL
]
- The bits argument contains an invalid
number of bits for the requested address family.
The
inet_net_pton() function may fail with
-
-
- [
ENOENT
]
- The src was not a valid Internet
network number.
SEE ALSO
byteorder(3),
inet(3),
networks(5)
HISTORY
The
inet_net_ntop() and
inet_net_pton()
functions appeared in BIND 4.9.4 and thence
NetBSD
1.3. Support for
AF_INET6
appeared in
NetBSD 1.6.