REALHOSTNAME_SA(3)     FreeBSD Library Functions Manual     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 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 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 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)

FreeBSD 13.1-RELEASE-p6        January 11, 2000        FreeBSD 13.1-RELEASE-p6