lwres_getipnodebyname(3)

LWRES_GETIPNODE(3)            BIND9            LWRES_GETIPNODE(3)

NAME

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

SYNOPSIS

     #include <lwres/netdb.h>

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

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

     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.

ISC                  Last change: 2007-06-18                    1

LWRES_GETIPNODE(3)            BIND9            LWRES_GETIPNODE(3)

     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
     <lwres/netdb.h>:

     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

ISC                  Last change: 2007-06-18                    2

LWRES_GETIPNODE(3)            BIND9            LWRES_GETIPNODE(3)

         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).

AUTHOR

     Internet Systems Consortium, Inc.

COPYRIGHT

     Copyright 8c9 2004, 2005, 2007, 2014-2016 Internet Systems
     Consortium, Inc. ("ISC")
     Copyright 8c9 2000, 2001, 2003 Internet Software Consortium.

ISC                  Last change: 2007-06-18                    3