getipnodebyname,  getipnodebyaddr,  freehostent - get net­
       work host names and addresses

SYNOPSIS

       #include <sys/types.h>
       #include <sys/socket.h>
       #include <netdb.h>

       struct hostent *ip=getipnodebyname(const char *name,
                                int af, int flags,
                                int *error_num);

       struct hostent *ip=getipnodebyaddr(const void *addr,
                                size_t len, int af,
                                int flags, int *error_num);

       void freehostent(struct hostent *ip);

DESCRIPTION

       The getipnodebyname(3)  and  getipnodebyaddr(3)  functions
       return  the  names and addresses of a network host.  These
       functions return a pointer to the following structure:

       struct  hostent {
               char    *h_name;
               char    **h_aliases;
               int     h_addrtype;
               int     h_length;
               char    **h_addr_list;
       };

       These functions replace the gethostbyname(3) and  gethost­
       byaddr(3) functions, which could only access the IPv4 net­
       work address family.  The getipnodebyname(3)  and  getipn­
       odebyaddr(3) functions can access multiple network address
       families.

       Unlike the gethostby  functions,  these  functions  return
       pointers  to  dynamically  allocated memory.  The freehos­
       tent(3) function is used to release the dynamically  allo­
       cated  memory after the caller no longer needs the hostent
       structure.

   getipnodebyname parameters
       The getipnodebyname(3) function looks up network addresses
       for  the  host  specified  by  the name parameter.  The af
       parameter specifies one of the following values:

       AF_INET       The name parameter points to  a  dotted-quad
                     IPv4  address  or  a name of an IPv4 network
                     host.

                     host.

       The flags parameter specifies  additional  options.   More
       than  one option can be specified by logically OR-ing them
       together.  flags should be set to  0  if  no  options  are
       desired.

       AI_V4MAPPED   This flag is used with AF_INET6 to request a
                     query for IPv4  addresses  instead  of  IPv6
                     addresses; the IPv4 addresses will be mapped
                     to IPv6 addresses.

       AI_ALL        This  flag  is  used  with  AI_V4MAPPED   to
                     request  a  query  for  both  IPv4  and IPv6
                     addresses.  Any IPv4 address found  will  be
                     mapped to an IPv6 address.

       AI_ADDRCONFIG This  flag  is used with AF_INET6 to further
                     request  that  queries  for  IPv6  addresses
                     should  not be made unless the system has at
                     least one IPv6 address assigned to a network
                     interface,   and   that   queries  for  IPv4
                     addresses should not be made unless the sys­
                     tem  has  at least one IPv4 address assigned
                     to a network interface.  This  flag  may  be
                     used by itself or with the AI_V4MAPPED flag.

       AI_ALL        This flag is equivalent to (AI_ADDRCONFIG  |
                     AI_V4MAPPED).

   getipnodebyaddr parameters
       The  getipnodebyaddr(3)  function looks up the name of the
       host whose network address is specified by the addr param­
       eter.   The  af  parameter  specifies one of the following
       values:

       AF_INET       The  addr  parameter  points  to  a   struct
                     in_addr and len must be set to sizeof(struct
                     in_addr).

       AF_INET6      The  addr  parameter  points  to  a   struct
                     in6_addr    and   len   must   be   set   to
                     sizeof(struct in6_addr).

RETURN VALUES

       A null pointer is  returned  if  an  error  occurred,  and
       error_num  will  contain  an error code from the following
       list:

       HOST_NOT_FOUND
                     The host name or  network  address  was  not
                     found.
                     work address or  name,  but  no  answer  was
                     returned.   This  can  happen if the network
                     host has only IPv4 addresses and  a  request
                     has  been made for IPv6 information only, or
                     vice versa.

       NO_RECOVERY   The domain name server returned a  permanent
                     failure response.

       TRY_AGAIN     The  domain name server returned a temporary
                     failure response.   You  might  have  better
                     luck next time.

       A  successful  query returns a pointer to a hostent struc­
       ture that contains the following fields:

       h_name        This is the official name  of  this  network
                     host.   h_aliases This is an array of point­
                     ers to unofficial aliases for the same host.
                     The  array  is terminated by a null pointer.
                     h_addrtype This is a copy of the af  parame­
                     ter   to  getipnodebyname(3)  or  getipnode­
                     byaddr(3).   h_addrtype   will   always   be
                     AF_INET  if  the  af  parameter was AF_INET.
                     h_addrtype will always be AF_INET6 if the af
                     parameter was AF_INET6.

       h_length      This  field  will  be  set  to sizeof(struct
                     in_addr) if h_addrtype is  AF_INET,  and  to
                     sizeof(struct  in6_addr)  if  h_addrtype  is
                     AF_INET6.

       h_addr_list   This is an array of one or more pointers  to
                     network  address  structures for the network
                     host.  The array is  terminated  by  a  null
                     pointer.

SEE ALSO

       getaddrinfo(3), inet_ntop(3), inet_pton(3)