NAME

       getipnodebyname, getipnodebyaddr, freehostent - get network hostnames and addresses

LIBRARY

       Standard C library (libc, -lc)

SYNOPSIS

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

       [[deprecated]] struct hostent *getipnodebyname(const char *name, int af,
                                                   int flags, int *error_num);
       [[deprecated]] struct hostent *getipnodebyaddr(const void addr[.len],
                                                   size_t len, int af,
                                                   int *error_num);
       [[deprecated]] void freehostent(struct hostent *ip);

DESCRIPTION

       These  functions  are  deprecated  (and  unavailable  in  glibc).   Use getaddrinfo(3) and
       getnameinfo(3) instead.

       The getipnodebyname() and getipnodebyaddr() 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 gethostbyaddr(3) functions, which could
       access only the IPv4 network address family.  The getipnodebyname() and  getipnodebyaddr()
       functions can access multiple network address families.

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

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

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

       AF_INET6
              The name argument points to a hexadecimal IPv6 address or a name of an IPv6 network
              host.

       The flags argument specifies additional options.  More than one option can be specified by
       bitwise 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 system 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_DEFAULT
              This flag is equivalent to (AI_ADDRCONFIG | AI_V4MAPPED).

   getipnodebyaddr() arguments
       The  getipnodebyaddr()  function  looks  up  the name of the host whose network address is
       specified by the addr argument.  The af argument specifies one of the following values:

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

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

RETURN VALUE

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

       HOST_NOT_FOUND
              The hostname or network address was not found.

       NO_ADDRESS
              The  domain  name  server recognized the network 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 structure that  contains  the  following
       fields:

       h_name This is the official name of this network host.

       h_aliases
              This is an array of pointers to unofficial aliases for the same host.  The array is
              terminated by a null pointer.

       h_addrtype
              This is a copy of  the  af  argument  to  getipnodebyname()  or  getipnodebyaddr().
              h_addrtype  will always be AF_INET if the af argument was AF_INET.  h_addrtype will
              always be AF_INET6 if the af argument 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.

STANDARDS

       None.

HISTORY

       RFC 2553.

       Present in glibc 2.1.91-95, but removed again.  Several UNIX-like  systems  support  them,
       but all call them deprecated.

SEE ALSO

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