getipnodebyname(3) — Linux manual page

NAME | SYNOPSIS | DESCRIPTION | RETURN VALUE | CONFORMING TO | NOTES | SEE ALSO | COLOPHON

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

NAME         top

       getipnodebyname, getipnodebyaddr, freehostent - get network
       hostnames and addresses

SYNOPSIS         top

       #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         top

       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         top

       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.

CONFORMING TO         top

       RFC 2553.

NOTES         top

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

SEE ALSO         top

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

COLOPHON         top

       This page is part of release 5.10 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)