INET6_RTH_SPACE(3)      NetBSD Library Functions Manual     INET6_RTH_SPACE(3)

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

SYNOPSIS
     #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
     The IPv6 Advanced API, RFC 3542, defines the functions that an applica-
     tion calls to build and examine IPv6 Routing headers.  Routing headers
     are used to perform source routing in IPv6 networks.  The RFC uses the
     word ``segments'' to describe addresses and that is the term used here as
     well.  All of the functions are defined in the <netinet/in.h> header
     file.  The functions described in this manual page all operate on routing
     header structures which are defined in <netinet/ip6.h> but which should
     not need to be modified outside the use of this API.  The size and shape
     of the route header structures may change, so using the APIs is a more
     portable, long term, solution.

     The functions in the API are split into two groups, those that build a
     routing header and those that parse a received routing header.  We will
     describe the builder functions followed by the parser functions.

   inet6_rth_space
     The inet6_rth_space() function returns the number of bytes required to
     hold a Routing Header of the type, specified in the type argument and
     containing the number of addresses specified in the segments argumment.
     When the type is IPV6_RTHDR_TYPE_0 the number of segments must be from 0
     through 127.  Routing headers of type IPV6_RTHDR_TYPE_2 contain only one
     segment, and are only used with Mobile IPv6.  The return value from this
     function is the number of bytes required to store the routing header.  If
     the value 0 is returned then either the route header type was not recog-
     nized or another error occurred.

   inet6_rth_init
     The inet6_rth_init() function initializes the pre-allocated buffer
     pointed to by bp to contain a routing header of the specified type The
     bp_len argument is used to verify that the buffer is large enough.  The
     caller must allocate the buffer pointed to by bp.  The necessary buffer
     size should be determined by calling inet6_rth_space() described in the
     previous sections.

     The inet6_rth_init() function returns a pointer to bp on success and NULL
     when there is an error.

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

     A successful addition results in the function returning 0, otherwise -1
     is returned.

   inet6_rth_reverse
     The inet6_rth_reverse() function takes a routing header, pointed to by
     the argument in, and writes a new routing header into the argument
     pointed to by out.  The routing header at that sends datagrams along the
     reverse of that route.  Both arguments are allowed to point to the same
     buffer meaning that the reversal can occur in place.

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

     The next set of functions operate on a routing header that the applica-
     tion wants to parse.  In the usual case such a routing header is received
     from the network, although these functions can also be used with routing
     headers that the application itself created.

   inet6_rth_segments
     The inet6_rth_segments() function returns the number of segments con-
     tained in the routing header pointed to by bp.  The return value is the
     number of segments contained in the routing header, or -1 if an error
     occurred.  It is not an error for 0 to be returned as a routing header
     may contain 0 segments.

   inet6_rth_getaddr
     The inet6_rth_getaddr() function is used to retrieve a single address
     from a routing header.  The index is the location in the routing header
     from which the application wants to retrieve an address.  The index
     parameter must have a value between 0 and one less than the number of
     segments present in the routing header.  The inet6_rth_segments() func-
     tion, described in the last section, should be used to determine the
     total number of segments in the routing header.  The inet6_rth_getaddr()
     function returns a pointer to an IPv6 address on success or NULL when an
     error has occurred.

DIAGNOSTICS
     The inet6_rth_space() and inet6_rth_getaddr() functions return 0 on
     errors.

     The inet6_rthdr_init() function returns NULL on error.  The
     inet6_rth_add() and inet6_rth_reverse() functions return 0 on success, or
     -1 upon an error.

EXAMPLES
     RFC 3542 gives extensive examples in Section 21, Appendix B.

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

SEE ALSO
     W. Stevens, M. Thomas, E. Nordmark, and T. Jinmei, Advanced Sockets API
     for IPv6, RFC 3542, May 2003.

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

HISTORY
     The implementation first appeared in KAME advanced networking kit.

NetBSD 5.0_STABLE              December 24, 2004             NetBSD 5.0_STABLE
