The <netinet/in.h> header shall define the following types:
in_port_t Equivalent to the type uint16_t as described in
<inttypes.h>.
in_addr_t Equivalent to the type uint32_t as described in
<inttypes.h>.
The <netinet_in.h> header shall define the sa_family_t type as
described in <sys/socket.h>.
The <netinet_in.h> header shall define the uint8_t and uint32_t
types as described in <inttypes.h>. Inclusion of the
<netinet/in.h> header may also make visible all symbols from
<inttypes.h> and <sys/socket.h>.
The <netinet/in.h> header shall define the in_addr structure,
which shall include at least the following member:
in_addr_t s_addr
The <netinet/in.h> header shall define the sockaddr_in structure,
which shall include at least the following members:
sa_family_t sin_family AF_INET.
in_port_t sin_port Port number.
struct in_addr sin_addr IP address.
The sin_port and sin_addr members shall be in network byte order.
The sockaddr_in structure is used to store addresses for the
Internet address family. Pointers to this type shall be cast by
applications to struct sockaddr * for use with socket functions.
The <netinet/in.h> header shall define the in6_addr structure,
which shall include at least the following member:
uint8_t s6_addr[16]
This array is used to contain a 128-bit IPv6 address, stored in
network byte order.
The <netinet/in.h> header shall define the sockaddr_in6
structure, which shall include at least the following members:
sa_family_t sin6_family AF_INET6.
in_port_t sin6_port Port number.
uint32_t sin6_flowinfo IPv6 traffic class and flow information.
struct in6_addr sin6_addr IPv6 address.
uint32_t sin6_scope_id Set of interfaces for a scope.
The sin6_port and sin6_addr members shall be in network byte
order.
Prior to calling a function in this standard which reads values
from a sockaddr_in6 structure (for example, bind() or connect()),
the application shall ensure that all members of the structure,
including any additional non-standard members, if any, are
initialized. If the sockaddr_in6 structure has a non-standard
member, and that member has a value other than the value that
would result from default initialization, the behavior of any
function in this standard that reads values from the sockaddr_in6
structure is implementation-defined. All functions in this
standard that return data in a sockaddr_in6 structure (for
example, getaddrinfo() or accept()) shall initialize the
structure in a way that meets the above requirements, and shall
ensure that each non-standard member, if any, has a value that
produces the same behavior as default initialization would in all
functions in this standard which read values from a sockaddr_in6
structure.
The sin6_scope_id field is a 32-bit integer that identifies a set
of interfaces as appropriate for the scope of the address carried
in the sin6_addr field. For a link scope sin6_addr, the
application shall ensure that sin6_scope_id is a link index. For
a site scope sin6_addr, the application shall ensure that
sin6_scope_id is a site index. The mapping of sin6_scope_id to an
interface or set of interfaces is implementation-defined.
The <netinet/in.h> header shall declare the following external
variable:
const struct in6_addr in6addr_any
This variable is initialized by the system to contain the
wildcard IPv6 address. The <netinet/in.h> header also defines the
IN6ADDR_ANY_INIT macro. This macro must be constant at compile
time and can be used to initialize a variable of type struct
in6_addr to the IPv6 wildcard address.
The <netinet/in.h> header shall declare the following external
variable:
const struct in6_addr in6addr_loopback
This variable is initialized by the system to contain the
loopback IPv6 address. The <netinet/in.h> header also defines the
IN6ADDR_LOOPBACK_INIT macro. This macro must be constant at
compile time and can be used to initialize a variable of type
struct in6_addr to the IPv6 loopback address.
The <netinet/in.h> header shall define the ipv6_mreq structure,
which shall include at least the following members:
struct in6_addr ipv6mr_multiaddr IPv6 multicast address.
unsigned ipv6mr_interface Interface index.
The <netinet/in.h> header shall define the following symbolic
constants for use as values of the level argument of getsockopt()
and setsockopt():
IPPROTO_IP Internet protocol.
IPPROTO_IPV6 Internet Protocol Version 6.
IPPROTO_ICMP Control message protocol.
IPPROTO_RAW Raw IP Packets Protocol.
IPPROTO_TCP Transmission control protocol.
IPPROTO_UDP User datagram protocol.
The <netinet/in.h> header shall define the following symbolic
constant for use as a local address in the structure passed to
bind():
INADDR_ANY IPv4 wildcard address.
The <netinet/in.h> header shall define the following symbolic
constant for use as a destination address in the structures
passed to connect(), sendmsg(), and sendto():
INADDR_BROADCAST
IPv4 broadcast address.
The <netinet/in.h> header shall define the following symbolic
constant, with the value specified, to help applications declare
buffers of the proper size to store IPv4 addresses in string
form:
INET_ADDRSTRLEN 16. Length of the string form for IP.
The htonl(), htons(), ntohl(), and ntohs() functions shall be
available as described in <arpa/inet.h>. Inclusion of the
<netinet/in.h> header may also make visible all symbols from
<arpa/inet.h>.
The <netinet/in.h> header shall define the following symbolic
constant, with the value specified, to help applications declare
buffers of the proper size to store IPv6 addresses in string
form:
INET6_ADDRSTRLEN
46. Length of the string form for IPv6.
The <netinet/in.h> header shall define the following symbolic
constants, with distinct integer values, for use in the
option_name argument in the getsockopt() or setsockopt()
functions at protocol level IPPROTO_IPV6:
IPV6_JOIN_GROUP Join a multicast group.
IPV6_LEAVE_GROUP
Quit a multicast group.
IPV6_MULTICAST_HOPS
Multicast hop limit.
IPV6_MULTICAST_IF
Interface to use for outgoing multicast packets.
IPV6_MULTICAST_LOOP
Multicast packets are delivered back to the local
application.
IPV6_UNICAST_HOPS
Unicast hop limit.
IPV6_V6ONLY Restrict AF_INET6 socket to IPv6 communications
only.
The <netinet/in.h> header shall define the following macros that
test for special IPv6 addresses. Each macro is of type int and
takes a single argument of type const struct in6_addr *:
IN6_IS_ADDR_UNSPECIFIED
Unspecified address.
IN6_IS_ADDR_LOOPBACK
Loopback address.
IN6_IS_ADDR_MULTICAST
Multicast address.
IN6_IS_ADDR_LINKLOCAL
Unicast link-local address.
IN6_IS_ADDR_SITELOCAL
Unicast site-local address.
IN6_IS_ADDR_V4MAPPED
IPv4 mapped address.
IN6_IS_ADDR_V4COMPAT
IPv4-compatible address.
IN6_IS_ADDR_MC_NODELOCAL
Multicast node-local address.
IN6_IS_ADDR_MC_LINKLOCAL
Multicast link-local address.
IN6_IS_ADDR_MC_SITELOCAL
Multicast site-local address.
IN6_IS_ADDR_MC_ORGLOCAL
Multicast organization-local address.
IN6_IS_ADDR_MC_GLOBAL
Multicast global address.
The following sections are informative.
