LWRES_GETADDRINFO(3)						       BIND9						      LWRES_GETADDRINFO(3)

NAME

       lwres_getaddrinfo, lwres_freeaddrinfo - socket address structure to host and service name

SYNOPSIS

       #include <lwres/netdb.h>

       int lwres_getaddrinfo(const char *hostname, const char *servname, const struct addrinfo *hints, struct addrinfo **res);

       void lwres_freeaddrinfo(struct addrinfo *ai);

       If the operating system does not provide a struct addrinfo, the following structure is used:

	   struct  addrinfo {
		   int		   ai_flags;	   /* AI_PASSIVE, AI_CANONNAME */
		   int		   ai_family;	   /* PF_xxx */
		   int		   ai_socktype;    /* SOCK_xxx */
		   int		   ai_protocol;    /* 0 or IPPROTO_xxx for IPv4 and IPv6 */
		   size_t	   ai_addrlen;	   /* length of ai_addr */
		   char 	   *ai_canonname;  /* canonical name for hostname */
		   struct sockaddr *ai_addr;	   /* binary address */
		   struct addrinfo *ai_next;	   /* next structure in linked list */
	   };

DESCRIPTION

       lwres_getaddrinfo() is used to get a list of IP addresses and port numbers for host hostname and service servname. The function is the
       lightweight resolver's implementation of getaddrinfo() as defined in RFC2133.  hostname and servname are pointers to null-terminated
       strings or NULL.  hostname is either a host name or a numeric host address string: a dotted decimal IPv4 address or an IPv6 address.
       servname is either a decimal port number or a service name as listed in /etc/services.

       hints is an optional pointer to a struct addrinfo. This structure can be used to provide hints concerning the type of socket that the
       caller supports or wishes to use. The caller can supply the following structure elements in *hints:

       ai_family
	   The protocol family that should be used. When ai_family is set to PF_UNSPEC, it means the caller will accept any protocol family
	   supported by the operating system.

       ai_socktype
	   denotes the type of socket -- SOCK_STREAM, SOCK_DGRAM or SOCK_RAW -- that is wanted. When ai_socktype is zero the caller will accept
	   any socket type.

       ai_protocol
	   indicates which transport protocol is wanted: IPPROTO_UDP or IPPROTO_TCP. If ai_protocol is zero the caller will accept any protocol.

       ai_flags
	   Flag bits. If the AI_CANONNAME bit is set, a successful call to lwres_getaddrinfo() will return a null-terminated string containing the
	   canonical name of the specified hostname in ai_canonname of the first addrinfo structure returned. Setting the AI_PASSIVE bit indicates
	   that the returned socket address structure is intended for used in a call to bind(2). In this case, if the hostname argument is a NULL
	   pointer, then the IP address portion of the socket address structure will be set to INADDR_ANY for an IPv4 address or IN6ADDR_ANY_INIT
	   for an IPv6 address.

	   When ai_flags does not set the AI_PASSIVE bit, the returned socket address structure will be ready for use in a call to connect(2) for
	   a connection-oriented protocol or connect(2), sendto(2), or sendmsg(2) if a connectionless protocol was chosen. The IP address portion
	   of the socket address structure will be set to the loopback address if hostname is a NULL pointer and AI_PASSIVE is not set in
	   ai_flags.

	   If ai_flags is set to AI_NUMERICHOST it indicates that hostname should be treated as a numeric string defining an IPv4 or IPv6 address
	   and no name resolution should be attempted.

       All other elements of the struct addrinfo passed via hints must be zero.

       A hints of NULL is treated as if the caller provided a struct addrinfo initialized to zero with ai_familyset to PF_UNSPEC.

       After a successful call to lwres_getaddrinfo(), *res is a pointer to a linked list of one or more addrinfo structures. Each struct addrinfo
       in this list cn be processed by following the ai_next pointer, until a NULL pointer is encountered. The three members ai_family,
       ai_socktype, and ai_protocol in each returned addrinfo structure contain the corresponding arguments for a call to socket(2). For each
       addrinfo structure in the list, the ai_addr member points to a filled-in socket address structure of length ai_addrlen.

       All of the information returned by lwres_getaddrinfo() is dynamically allocated: the addrinfo structures, and the socket address structures
       and canonical host name strings pointed to by the addrinfostructures. Memory allocated for the dynamically allocated structures created by
       a successful call to lwres_getaddrinfo() is released by lwres_freeaddrinfo().  ai is a pointer to a struct addrinfo created by a call to
       lwres_getaddrinfo().

RETURN VALUES

       lwres_getaddrinfo() returns zero on success or one of the error codes listed in gai_strerror(3) if an error occurs. If both hostname and
       servname are NULL lwres_getaddrinfo() returns EAI_NONAME.

SEE ALSO

       lwres(3), lwres_getaddrinfo(3), lwres_freeaddrinfo(3), lwres_gai_strerror(3), RFC2133(), getservbyname(3), bind(2), connect(2), sendto(2),
       sendmsg(2), socket(2).

COPYRIGHT

       Copyright (C) 2004, 2005, 2007 Internet Systems Consortium, Inc. ("ISC")
       Copyright (C) 2000, 2001, 2003 Internet Software Consortium.

BIND9								   Jun 30, 2000 					      LWRES_GETADDRINFO(3)