LWRES_GETADDRINFO(3)          BIND9          LWRES_GETADDRINFO(3)



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

SYNOPSIS
       #include 

       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 NULLlwres_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).



BIND9                      Jun 30, 2000      LWRES_GETADDRINFO(3)