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_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 approriate 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)