NAME    [Toc]    [Back]

     inet6_rth_space inet6_rth_init inet6_rth_add inet6_rth_reverse
     inet6_rth_segments inet6_rth_getaddr -- IPv6 Routing Header Options
     manipulation

SYNOPSIS    [Toc]    [Back]

     #include <netinet/in.h>

     socklen_t
     inet6_rth_space(int, int);

     void *
     inet6_rth_init(void *, socklen_t, int, int);

     int
     inet6_rth_add(void *, const struct in6_addr *);

     int
     inet6_rth_reverse(const void *, void *);

     int
     inet6_rth_segments(const void *);

     struct in6_addr *
     inet6_rth_getaddr(const void *, int);

DESCRIPTION    [Toc]    [Back]

     The IPv6 advanced API defines six functions that the application calls to
     build and examine a Routing header, and the ability to use sticky options
     or ancillary data to communicate this information between the application
     and the kernel using the IPV6_RTHDR option.

     Three functions build a Routing header:

     inet6_rth_space() returns #bytes required for Routing header

     inet6_rth_init() initializes buffer data for Routing header

     inet6_rth_add() adds one IPv6 address to the Routing header

     Three functions deal with a returned Routing header:

     inet6_rth_reverse() reverses a Routing header

     inet6_rth_segments() returns #segments in a Routing header

     inet6_rth_getaddr() fetches one address from a Routing header

     The function prototypes for these functions are defined as a result of
     including the <netinet/in.h> header.

   inet6_rth_space
     inet6_rth_space() returns the number of bytes required to hold a Routing
     header of the specified type containing the specified number of segments
     (addresses.) For an IPv6 Type 0 Routing header, the number of segments
     must be between 0 and 127, inclusive.  The return value is just the space
     for the Routing header.  When the application uses ancillary data it must
     pass the returned length to CMSG_LEN() to determine how much memory is
     needed for the ancillary data object (including the cmsghdr structure.)

     If the return value is 0, then either the type of the Routing header is
     not supported by this implementation or the number of segments is invalid
     for this type of Routing header.

     Note: This function returns the size but does not allocate the space
     required for the ancillary data.  This allows an application to allocate
     a larger buffer, if other ancillary data objects are desired, since all
     the ancillary data objects must be specified to sendmsg() as a single
     msg_control buffer.

   inet6_rth_init
     inet6_rth_init() initializes the buffer pointed to by bp to contain a
     Routing header of the specified type and sets ip6r_len based on the
     segments parameter.  bp_len is only used to verify that the buffer is
     large enough.  The ip6r_segleft field is set to zero; inet6_rth_add()
     will increment it.

     When the application uses ancillary data the application must initialize
     any cmsghdr fields.

     The caller must allocate the buffer and its size can be determined by
     calling inet6_rth_space().

     Upon success the return value is the pointer to the buffer bp, and this
     is then used as the first argument to the next two functions.  Upon an
     error the return value is NULL.

   inet6_rth_add
     inet6_rth_add() adds the IPv6 address pointed to by addr to the end of
     the Routing header being constructed.

     If successful, the segleft member of the Routing Header is updated to
     account for the new address in the Routing header and the return value of
     the function is 0.  Upon an error the return value of the function is -1.

   inet6_rth_reverse
     inet6_rth_reverse() takes a Routing header extension header (pointed to
     by the first argument in) and writes a new Routing header that sends
     datagrams along the reverse of that route.  Both arguments are allowed to
     point to the same buffer (that is, the reversal can occur in place.)

     The return value of the function is 0 on success, or -1 upon an error.

   inet6_rth_segments
     inet6_rth_segments() returns the number of segments (addresses) contained
     in the Routing header described by bp.  On success the return value is
     zero or greater.  The return value of the function is -1 upon an error.

   inet6_rth_getaddr
     inet6_rth_getaddr() returns a pointer to the IPv6 address specified by
     index (which must have a value between 0 and one less than the value
     returned by inet6_rth_segments()) in the Routing header described by bp.
     An application should first call inet6_rth_segments() to obtain the number
 of segments in the Routing header.

     Upon an error the return value of the function is NULL.

DIAGNOSTICS    [Toc]    [Back]

     inet6_rth_space() and return 0 on errors.

     inet6_rthdr_init() returns NULL on error.	inet6_rth_add() and
     inet6_rth_reverse() return0 on success, or -1 upon an error.

EXAMPLES    [Toc]    [Back]

     draft-ietf-ipngwg-rfc2292bis-08.txt gives comprehensive examples in Section
 22.

     KAME also provides examples in the advapitest directry of its kit.

SEE ALSO    [Toc]    [Back]

     W. Stevens, M. Thomas, E. Nordmark, and E. Jinmei, Advanced Sockets API
     for IPv6, draft-ietf-ipngwg-rfc2292bis-08, October 2002.

     S. Deering and R. Hinden, Internet Protocol, Version 6 (IPv6)
     Specification, RFC2460, December 1998.

HISTORY    [Toc]    [Back]

     The implementation first appeared in KAME advanced networking kit.

STANDARDS    [Toc]    [Back]

     The functions are documented in ``Advanced Sockets API for IPv6''
     (draft-ietf-ipngwg-rfc2292bis-08.txt).

BUGS    [Toc]    [Back]

     The text was shamelessly copied from internet-drafts for RFC2292bis.


FreeBSD 5.2.1		       February 5, 2000 		 FreeBSD 5.2.1