LWRES_GETIPNODE(3)            BIND9            LWRES_GETIPNODE(3)



NAME
       lwres_getipnodebyname, lwres_getipnodebyaddr,
       lwres_freehostent - lightweight resolver nodename /
       address translation API

SYNOPSIS
       #include 

       struct hostent * lwres_getipnodebyname(const char *name,
                                              int af, int flags,
                                              int *error_num);

       struct hostent * lwres_getipnodebyaddr(const void *src,
                                              size_t len, int af,
                                              int *error_num);

       void lwres_freehostent(struct hostent *he);

DESCRIPTION
       These functions perform thread safe, protocol independent
       nodename-to-address and address-to-nodename translation as
       defined in RFC2553.

       They use a struct hostent which is defined in namedb.h:

       struct  hostent {
               char    *h_name;        /* official name of host */
               char    **h_aliases;    /* alias list */
               int     h_addrtype;     /* host address type */
               int     h_length;       /* length of address */
               char    **h_addr_list;  /* list of addresses from name server */
       };
       #define h_addr  h_addr_list[0]  /* address, for backward compatibility */


       The members of this structure are:

       h_name The official (canonical) name of the host.

       h_aliases
              A NULL-terminated array of alternate names
              (nicknames) for the host.

       h_addrtype
              The type of address being returned - usually
              PF_INET or PF_INET6.

       h_length
              The length of the address in bytes.

       h_addr_list
              A NULL terminated array of network addresses for
              the host. Host addresses are returned in network
              byte order.

       lwres_getipnodebyname() looks up addresses of protocol
       family af for the hostname name. The flags parameter
       contains ORed flag bits to specify the types of addresses
       that are searched for, and the types of addresses that are
       returned. The flag bits are:

       AI_V4MAPPED
              This is used with an af of AF_INET6, and causes
              IPv4 addresses to be returned as IPv4-mapped IPv6
              addresses.

       AI_ALL This is used with an af of AF_INET6, and causes all
              known addresses (IPv6 and IPv4) to be returned. If
              AI_V4MAPPED is also set, the IPv4 addresses are
              return as mapped IPv6 addresses.

       AI_ADDRCONFIG
              Only return an IPv6 or IPv4 address if here is an
              active network interface of that type. This is not
              currently implemented in the BIND 9 lightweight
              resolver, and the flag is ignored.

       AI_DEFAULT
              This default sets the AI_V4MAPPED and AI_ADDRCONFIG
              flag bits.

       lwres_getipnodebyaddr() performs a reverse lookup of
       address src which is len bytes long.  af denotes the
       protocol family, typically PF_INET or PF_INET6.

       lwres_freehostent() releases all the memory associated
       with the struct hostent pointer he. Any memory allocated
       for the h_name, h_addr_list and h_aliases is freed, as is
       the memory for the hostent structure itself.

RETURN VALUES
       If an error occurs, lwres_getipnodebyname() and
       lwres_getipnodebyaddr() set *error_num to an appropriate
       error code and the function returns a NULL pointer. The
       error codes and their meanings are defined in
       :

       HOST_NOT_FOUND
              No such host is known.

       NO_ADDRESS
              The server recognised the request and the name but
              no address is available. Another type of request to
              the name server for the domain might return an
              answer.

       TRY_AGAIN
              A temporary and possibly transient error occurred,
              such as a failure of a server to respond. The
              request may succeed if retried.

       NO_RECOVERY
              An unexpected failure occurred, and retrying the
              request is pointless.

       lwres_hstrerror(3 ) translates these error codes to
       suitable error messages.

SEE ALSO
       RFC2553(), lwres(3), lwres_gethostent(3),
       lwres_getaddrinfo(3), lwres_getnameinfo(3),
       lwres_hstrerror(3).



BIND9                      Jun 30, 2000        LWRES_GETIPNODE(3)