REALHOSTNAME_SA(3)

NAME
realhostname_sa - convert an struct sockaddr to the real host name

LIBRARY
libutil

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 corresponding 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 doesn't 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
realhostname_sa() 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.

SEE ALSO
getaddrinfo(3), getnameinfo(3), realhostname(3)