lwres_getipnode

LWRES_GETIPNODE(3)					   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, 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 net-
	      work 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_getipnode-
       byaddr() 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	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 mes-
       sages.

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



BIND9				 Jun 30, 2000		   LWRES_GETIPNODE(3)