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. If the sin_port value passed to bind() is zero, the port number bound to the socket shall be one chosen by the implementation from an implementation-defined port range to produce an unused local address.
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.
[IP6] ![[Option Start]](../images/opt-start.gif)
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 sockaddr_in6 structure shall not include any additional members which have a floating-point type if an object of that
type with an all-bits-zero representation does not have the value 0.0. ![[Option End]](../images/opt-end.gif)
[IP6 MX] Implementations that define __STDC_IEC_559__ are required to treat the all-zero bit pattern for a floating point object as a
representation of 0.0, and may therefore have floating-point type members.
[IP6]
The sin6_port and sin6_addr members shall be in network byte order. If the sin6_port value passed to bind() is zero, the port number bound to the socket shall be one chosen by the implementation
from an implementation-defined port range to produce an unused local address.
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 shall 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 shall 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
- [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 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>.
[IP6]
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.
[IP6]
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.