LWRES_GETADDRINFO(3)                 BIND9                LWRES_GETADDRINFO(3)

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

       #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 */

       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

       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:

           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.

           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.

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

           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

           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

       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().

       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 NULLlwres_getaddrinfo() returns EAI_NONAME.

       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).

       Internet Systems Consortium, Inc.

       Copyright © 2000, 2001, 2003-2005, 2007, 2014-2016 Internet Systems
       Consortium, Inc. ("ISC")

ISC                               2007-06-18              LWRES_GETADDRINFO(3)