inet.3n (2010 09)

i
inet(3N) inet(3N)
NAME
inet: inet_addr(), inet_lnaof(), inet_makeaddr(), inet_netof(), inet_network(), inet_ntoa(), inet_ntoa_r() -
Internet address manipulation routines
SYNOPSIS
#include <sys/socket.h>
#include <netinet/in.h>
#include <arpa/inet.h>
in_addr_t inet_addr(const char *
cp);
in_addr_t inet_lnaof(struct in_addr
in);
struct in_addr inet_makeaddr(in_addr_t
net, in_addr_t lna );
in_addr_t inet_netof(struct in_addr
in);
in_addr_t inet_network(const char *
cp);
char *inet_ntoa(struct in_addr
in);
Remarks
The routine inet_ntoa_r()
is described in the Obsolescent Interfaces section below.
DESCRIPTION
inet_addr() and inet_network()
Interpret character strings representing numbers expressed in the Internet stan-
dard "dot" notation.
inet_addr() returns numbers suitable for use as Internet addresses.
inet_network() returns numbers suitable for use as Internet network numbers.
Return values can be assigned to a
struct in_addr (defined in
/usr/include/netinet/in.h
) by using a technique similar to the following:
struct in_addr addr;
char *cp;
addr.s_addr = inet_addr(cp);
inet_ntoa() Take an Internet address and return an ASCII string representing the address in
dot (.)notation.
inet_makeaddr()
Take an Internet network number and a local network address and construct an
Internet address from it.
inet_netof() Break apart Internet host addresses, returning the network number part.
inet_lnaof() Break apart Internet host addresses, returning the local network address part.
All Internet addresses are returned in network order (bytes ordered from left to right). All network
numbers and local address parts are returned as machine-format integer values. Bytes in HP-UX sys-
tems are ordered from left to right.
Internet Addresses
Values specified using dot notation take one of the following forms:
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 address.
When a three-part address is specified, the last part is interpreted as a 16-bit quantity and placed in the
right-most two bytes of the network address. This makes the three-part address format convenient for
specifying Class B network addresses, as in
128.net.host.
When a two-part address is supplied, the last part is interpreted as a 24-bit quantity and placed in the
right-most three bytes of the network address. This makes the two-part address format convenient for
HP-UX 11i Version 3: September 2010 − 1 − Hewlett-Packard Company 1