realhostname(3) [freebsd man page]

REALHOSTNAME(3) 					   BSD Library Functions Manual 					   REALHOSTNAME(3)

NAME

     realhostname -- convert an IP number to the real host name

LIBRARY

     System Utilities Library (libutil, -lutil)

SYNOPSIS

     #include <libutil.h>

     int
     realhostname(char *host, size_t hsize, const struct in_addr *ip);

DESCRIPTION

     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 does not 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.

RETURN VALUES

     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.

SEE ALSO

     gethostbyaddr(3), gethostbyname(3), inet_ntoa(3), realhostname_sa(3)

BSD
								   April 6, 1999							       BSD

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

NAME

       inet_aton, inet_addr, inet_network, inet_ntoa, inet_makeaddr, inet_lnaof, inet_netof - Internet address manipulation routines

SYNOPSIS

       #include <sys/socket.h>
       #include <netinet/in.h>
       #include <arpa/inet.h>

       int inet_aton(const char *cp, struct in_addr *inp);

       in_addr_t inet_addr(const char *cp);

       in_addr_t inet_network(const char *cp);

       char *inet_ntoa(struct in_addr in);

       struct in_addr inet_makeaddr(int net, int host);

       in_addr_t inet_lnaof(struct in_addr in);

       in_addr_t inet_netof(struct in_addr in);

DESCRIPTION

       inet_aton()  converts the Internet host address cp from the standard numbers-and-dots notation into binary data and stores it in the struc-
       ture that inp points to. inet_aton returns nonzero if the address is valid, zero if not.

       The inet_addr() function converts the Internet host address cp from numbers-and-dots notation into binary data in network byte  order.	If
       the input is invalid, INADDR_NONE (usually -1) is returned.  This is an obsolete interface to inet_aton, described immediately above; it is
       obsolete because -1 is a valid address (255.255.255.255), and inet_aton provides a cleaner way to indicate error return.

       The inet_network() function extracts the network number in host byte order from the address cp in numbers-and-dots notation.  If the  input
       is invalid, -1 is returned.

       The  inet_ntoa()  function converts the Internet host address in given in network byte order to a string in standard numbers-and-dots nota-
       tion.  The string is returned in a statically allocated buffer, which subsequent calls will overwrite.

       The inet_makeaddr() function makes an Internet host address in network byte order by combining  the  network  number  net  with	the  local
       address host in network net, both in local host byte order.

       The inet_lnaof() function returns the local host address part of the Internet address in.  The local host address is returned in local host
       byte order.

       The inet_netof() function returns the network number part of the Internet Address in.  The network number is returned in  local	host  byte
       order.

       The structure in_addr as used in inet_ntoa(), inet_makeaddr(), inet_lnoaf() and inet_netof() is defined in netinet/in.h as:

	      struct in_addr {
		      unsigned long int s_addr;
	      }

       Note  that  on  the i80x86 the host byte order is Least Significant Byte first, whereas the network byte order, as used on the Internet, is
       Most Significant Byte first.

CONFORMING TO

       BSD 4.3

SEE ALSO

       gethostbyname(3), getnetent(3), inet_ntop(3), inet_pton(3), hosts(5), networks(5)

BSD
								    2001-07-25								   INET(3)