The <netinet/in.h> header shall define the following types:
- in_port_t
- Equivalent to the type uint16_t as defined in <inttypes.h> .
- in_addr_t
- Equivalent to the type uint32_t as defined in <inttypes.h> .
The sa_family_t type shall be defined as described in <sys/socket.h>.
The uint8_t and uint32_t type shall be defined 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 that includes at least the following member:
in_addr_t s_addr
The <netinet/in.h> header shall define the sockaddr_in structure that includes 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. Values of this type shall be cast by applications to struct sockaddr for use with socket functions.
[IP6] ![[Option Start]](http://image48.360doc.com/DownloadImg/2011/12/1422/20034710_1.gif)
The <netinet/in.h> header shall define the in6_addr structure that contains 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 that includes 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.
The sockaddr_in6 structure shall be set to zero by an application prior to using it, since implementations are free to have additional, implementation-defined fields in sockaddr_in6.
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 that includes at least the following members:
struct in6_addr ipv6mr_multiaddr IPv6 multicast address.
unsigned ipv6mr_interface Interface index.
![[Option End]](http://image48.360doc.com/DownloadImg/2011/12/1422/20034710_2.gif)
The <netinet/in.h> header shall define the following macros for use as values of the level argument of getsockopt() and setsockopt():
- IPPROTO_IP
- Internet protocol.
- IPPROTO_IPV6
- [IP6] Internet Protocol Version 6.
- IPPROTO_ICMP
- Control message protocol.
- IPPROTO_RAW
- [RS] Raw IP Packets Protocol.
- IPPROTO_TCP
- Transmission control protocol.
- IPPROTO_UDP
- User datagram protocol.
The <netinet/in.h> header shall define the following macros for use as destination addresses for connect(), sendmsg(), and sendto():
- INADDR_ANY
- IPv4 local host address.
- INADDR_BROADCAST
- IPv4 broadcast address.
The <netinet/in.h> header shall define the following macro 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 defined in <arpa/inet.h>. Inclusion of the <netinet/in.h> header may also make visible all symbols from <arpa/inet.h>.
[IP6] The <netinet/in.h> header shall define the following macro 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 macros, 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.
