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 5.10							    1 Nov 2003							getnameinfo(3XNET)