NAME
inet_net_ntop,
inet_net_pton —
Internet network number manipulation
routines
LIBRARY
Standard C Library (libc, -lc)
SYNOPSIS
#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 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 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. 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_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).
LEGACY SYNOPSIS
#include
<sys/types.h> #include
<sys/socket.h> #include
<netinet/in.h> #include
<arpa/inet.h>
These include files were necessary for all functions.
SEE ALSO
HISTORY
The inet_net_ntop() and
inet_net_pton() functions appeared in BIND
4.9.4.