realhostname_sa(3)

NAME

realhostname_sa - convert a struct sockaddr to the real host

name

LIBRARY

System Utilities Library (libutil, -lutil)

SYNOPSIS

#include <sys/types.h>
#include <netinet/in.h>
#include <libutil.h>
int
realhostname_sa(char  *host,  size_t  hsize, struct sockaddr
*addr,
        int addrlen);

DESCRIPTION

The function realhostname_sa() converts addr to the corre

sponding host
name. This is done by resolving addr to a host name and

then ensuring
that the host name resolves back to addr.

host must point to a buffer of at least hsize bytes, and

will always be
written to by this function.

If the name resolution does not work both ways or if the

host name is
longer than hsize bytes, getnameinfo(3) with NI_NUMERICHOST

specified, is
used to convert addr to an ASCII form.

If the string written to host is hsize bytes long, host will

not be NUL
terminated.

RETURN VALUES

The realhostname_sa() function will return one of the fol

lowing constants
which are defined in

HOSTNAME_FOUND

A valid host name was found.

HOSTNAME_INCORRECTNAME

A host name was found, but it did not resolve back

to the passed
ip. host now contains the numeric value of ip.

HOSTNAME_INVALIDADDR

ip could not be resolved. host now contains the nu

meric value of
ip.

HOSTNAME_INVALIDNAME

A host name was found, but it could not be resolved

back to any
ip number. host now contains the numeric value of

ip.

SEE ALSO

getaddrinfo(3), getnameinfo(3), realhostname(3)

BSD January 11, 2000

BSD