realhostname -- convert an IP number to the real host name
System Utilities Library (libutil, -lutil)
#include <sys/types.h>
#include <netinet/in.h>
#include <libutil.h>
int
realhostname(char *host, size_t hsize, const struct in_addr *ip);
The function realhostname() converts ip to the corresponding host name.
This is done by resolving ip to a host name and then ensuring that the
host name resolves back to ip.
host must point to a buffer of at least hsize bytes, and will always be
written to by this function.
If the name resolution doesn't work both ways or if the host name is
longer than hsize bytes, inet_ntoa(3) is used to convert ip to an ASCII
form.
If the string written to host is hsize bytes long, host will not be NUL
terminated.
The realhostname() function will return one of the following constants
which are defined in <libutil.h>:
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 numeric 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.
gethostbyaddr(3), gethostbyname(3), inet_ntoa(3), realhostname_sa(3)
FreeBSD 5.2.1 April 6, 1999 FreeBSD 5.2.1 [ Back ] |