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man:freehostent

GETIPNODEBYNAME(3) Linux Programmer's Manual GETIPNODEBYNAME(3)

NAME

     getipnodebyname,  getipnodebyaddr,  freehostent - get network hostnames
     and addresses

SYNOPSIS

     #include <sys/types.h>
     #include <sys/socket.h>
     #include <netdb.h>
     struct hostent *getipnodebyname(const char *name, int af,
                                     int flags, int *error_num);
     struct hostent *getipnodebyaddr(const void *addr, size_t len,
                                     int af, int *error_num);
     void freehostent(struct hostent *ip);

DESCRIPTION

     These functions are deprecated (and unavailable in glibc).  Use  getad-
     drinfo(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) func-
     tions, 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 net-
     work address is specified by the addr argument.  The af argument speci-
     fies 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 con-
     tains 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.

CONFORMING TO

     RFC 2553.

NOTES

     These functions were present  in  glibc  2.1.91-95,  but  were  removed
     again.   Several UNIX-like systems support them, but all call them dep-
     recated.

SEE ALSO

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

COLOPHON

     This page is part of release 4.16 of the Linux  man-pages  project.   A
     description  of  the project, information about reporting bugs, and the
     latest    version    of    this    page,    can     be     found     at
     https://www.kernel.org/doc/man-pages/.

Linux 2017-09-15 GETIPNODEBYNAME(3)

/data/webs/external/dokuwiki/data/pages/man/freehostent.txt · Last modified: 2019/05/17 09:47 by 127.0.0.1

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