getnameinfo(3XNET)				   X/Open Networking Services Library Functions 				getnameinfo(3XNET)

NAME

       getnameinfo - get name information

SYNOPSIS

       cc [ flag ... ] file ... -lxnet [ library ... ]
       #include <sys/socket.h>
       #include <netdb.h>

       int getnameinfo(const struct sockaddr *restrict sa, socklen_t salen,
	    char *restrict node, socklen_t nodelen, char *restrict service,
	    socklen_t servicelen, unsigned flags);

DESCRIPTION

       The  getnameinfo()  function  translates  a  socket  address  to  a  node  name and service location, all of which are defined as in getad-
       drinfo(3XNET).

       The sa argument points to a socket address structure to be translated. If the socket address structure contains an IPv4-mapped IPv6 address
       or an IPv4-compatible IPv6 address, the implementation extracts the embedded IPv4 address and lookup the node name for that IPv4 address.

       If  the	node  argument	is  non-NULL and the nodelen argument is non-zero, then the node argument points to a buffer able to contain up to
       nodelen characters that receives the node name as a null-terminated string. If the node argument is NULL or the nodelen argument  is  zero,
       the  node  name	is  not  returned. If the node's name cannot be located, the numeric form of the node's address is returned instead of its
       name.

       If the service argument is non-NULL and the servicelen argument is non-zero, then the service argument points to a buffer able  to  contain
       up  to servicelen bytes that receives the service name as a null-terminated string. If the service argument is NULL or the servicelen argu-
       ment is zero, the service name is not returned. If the service's name cannot be located, the numeric form of the service address (for exam-
       ple, its port number) is returned instead of its name.

       The  flags  argument  is a flag that changes the default actions of the function. By default the fully-qualified domain name (FQDN) for the
       host is returned, but:

	   o	  If the flag bit NI_NOFQDN is set, only the node name portion of the FQDN is returned for local hosts.

	   o	  If the flag bit NI_NUMERICHOST is set, the numeric form of the host's address is returned instead of its name, under all circum-
		  stances.

	   o	  If the flag bit NI_NAMEREQD is set, an error is returned if the host's name cannot be located.

	   o	  If  the  flag  bit  NI_NUMERICSERV  is  set,	the numeric form of the service address is returned (for example, its port number)
		  instead of its name, under all circumstances.

	   o	  If the flag bit NI_DGRAM is set, this indicates that the service is  a  datagram  service  (SOCK_DGRAM).  The  default  behavior
		  assumes that the service is a stream service (SOCK_STREAM).

RETURN VALUES

       A  0 return value for getnameinfo() indicates successful completion; a non-zero return value indicates failure. The possible values for the
       failures are listed in the ERRORS section.

       Upon successful completion, getnameinfo() returns the node and service names, if requested, in the buffers provided. The returned names are
       always null-terminated strings.

ERRORS

       The getnameinfo() function will fail if:

       EAI_AGAIN       The name could not be resolved at this time. Future attempts might succeed.

       EAI_BADFLAGS    The flags argument had an invalid value.

       EAI_FAIL        A non-recoverable error occurred.

       EAI_FAMILY      The address family was not recognized or the address length was invalid for the specified family.

       EAI_MEMORY      There was a memory allocation failure.

       EAI_NONAME      The  name  does not resolve for the supplied parameters.       NI_NAMEREQD is set and the host's name cannot be located, or
		       both nodename and servname were NULL.

       EAI_SYSTEM      A system error occurred. The error code can be found in errno.

USAGE

       If the returned values are to be used as part of any further name resolution (for example, passed to  getaddrinfo()),  applications  should
       provide buffers large enough to store any result possible on the system.

       Given  the  IPv4-mapped IPv6 address "::ffff:1.2.3.4", the implementation performs a lookup as if the socket address structure contains the
       IPv4 address "1.2.3.4".

ATTRIBUTES

       See attributes(5) for descriptions of the following attributes:

       +-----------------------------+-----------------------------+
       |      ATTRIBUTE TYPE	     |	    ATTRIBUTE VALUE	   |
       +-----------------------------+-----------------------------+
       |Interface Stability	     |Standard			   |
       +-----------------------------+-----------------------------+
       |MT-Level		     |MT-Safe			   |
       +-----------------------------+-----------------------------+

SEE ALSO

       gai_strerror(3XNET), getaddrinfo(3XNET), getservbyname(3XNET), socket(3XNET), attributes(5), standards(5)

NOTES

       The IPv6 unspecified address ("::") and the IPv6 loopback address ("::1") are not IPv4-compatible addresses. If the  address  is  the  IPv6
       unspecified address ("::"), a lookup is not performed, and the EAI_NONAME error is returned.

       The two NI_NUMERICxxx flags are required to support the -n flag that many commands provide.

       The  NI_DGRAM flag is required for the few AF_INET and AF_INET6 port numbers (for example, [512,514]) that represent different services for
       UDP and TCP.

SunOS 5.11							    1 Nov 2003							getnameinfo(3XNET)