274 lines
7.3 KiB
Groff
274 lines
7.3 KiB
Groff
.\" $KAME: kame/kame/kame/libinet6/inet6_rth_space.3,v 1.4 2002/10/17 14:13:48 jinmei Exp $
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.\"
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.\" Copyright (C) 2000 WIDE Project.
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.\" All rights reserved.
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.\"
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.\" Redistribution and use in source and binary forms, with or without
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.\" modification, are permitted provided that the following conditions
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.\" are met:
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.\" 1. Redistributions of source code must retain the above copyright
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.\" notice, this list of conditions and the following disclaimer.
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.\" 2. Redistributions in binary form must reproduce the above copyright
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.\" notice, this list of conditions and the following disclaimer in the
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.\" documentation and/or other materials provided with the distribution.
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.\" 3. Neither the name of the project nor the names of its contributors
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.\" may be used to endorse or promote products derived from this software
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.\" without specific prior written permission.
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.\"
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.\" THIS SOFTWARE IS PROVIDED BY THE PROJECT AND CONTRIBUTORS ``AS IS'' AND
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.\" ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
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.\" IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
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.\" ARE DISCLAIMED. IN NO EVENT SHALL THE PROJECT OR CONTRIBUTORS BE LIABLE
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.\" FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
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.\" DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
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.\" OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
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.\" HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
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.\" LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
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.\" OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
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.\" SUCH DAMAGE.
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.\"
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.\" $FreeBSD$
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.\"
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.Dd February 5, 2000
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.Dt INET6_RTH_SPACE 3
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.Os
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.\"
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.Sh NAME
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.Nm inet6_rth_space ,
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.Nm inet6_rth_init ,
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.Nm inet6_rth_add ,
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.Nm inet6_rth_reverse ,
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.Nm inet6_rth_segments ,
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.Nm inet6_rth_getaddr
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.Nd IPv6 Routing Header Options manipulation
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.\"
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.Sh SYNOPSIS
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.In netinet/in.h
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.Ft socklen_t
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.Fn inet6_rth_space "int" "int"
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.Ft "void *"
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.Fn inet6_rth_init "void *" "socklen_t" "int" "int"
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.Ft int
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.Fn inet6_rth_add "void *" "const struct in6_addr *"
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.Ft int
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.Fn inet6_rth_reverse "const void *" "void *"
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.Ft int
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.Fn inet6_rth_segments "const void *"
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.Ft "struct in6_addr *"
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.Fn inet6_rth_getaddr "const void *" "int"
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.\"
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.Sh DESCRIPTION
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The IPv6 advanced API defines six
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functions that the application calls to build and examine a Routing
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header, and the ability to use sticky options or ancillary data to
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communicate this information between the application and the kernel
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using the IPV6_RTHDR option.
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.Pp
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Three functions build a Routing header:
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.Bl -hang
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.It Fn inet6_rth_space
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returns #bytes required for Routing header
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.It Fn inet6_rth_init
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initializes buffer data for Routing header
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.It Fn inet6_rth_add
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adds one IPv6 address to the Routing header
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.El
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.Pp
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Three functions deal with a returned Routing header:
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.Bl -hang
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.It Fn inet6_rth_reverse
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reverses a Routing header
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.It Fn inet6_rth_segments
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returns #segments in a Routing header
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.It Fn inet6_rth_getaddr
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fetches one address from a Routing header
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.El
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.Pp
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The function prototypes for these functions are defined as a result
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of including the
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.In netinet/in.h
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header.
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.\"
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.Ss inet6_rth_space
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The
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.Fn inet6_rth_space
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function
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returns the number of bytes required to hold a Routing
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header of the specified type containing the specified number of
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segments (addresses).
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For an IPv6 Type 0 Routing header, the number
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of
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segments
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must be between 0 and 127, inclusive.
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The return value is just the space for the Routing header.
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When the application uses
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ancillary data it must pass the returned length to
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.Fn CMSG_LEN
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to determine how much memory is needed for the ancillary data object
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(including the
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.Vt cmsghdr
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structure).
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.Pp
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If the return value is 0, then either the type of the Routing header
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is not supported by this implementation or the number of segments is
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invalid for this type of Routing header.
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.Pp
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Note: this function returns the size but does not allocate the space
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required for the ancillary data.
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This allows an application to
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allocate a larger buffer, if other ancillary data objects are
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desired, since all the ancillary data objects must be specified to
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.Xr sendmsg 2
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as a single msg_control buffer.
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.Ss inet6_rth_init
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The
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.Fn inet6_rth_init
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function
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initializes the buffer pointed to by
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.Fa bp
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to contain a
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Routing header of the specified type and sets
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.Va ip6r_len
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based on the
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.Fa segments
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parameter.
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The
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.Fa bp_len
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argument
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is only used to verify that the buffer is
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large enough.
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The
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.Va ip6r_segleft
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field is set to zero;
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.Fn inet6_rth_add
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will increment it.
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.Pp
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When the application uses ancillary data the application must
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initialize any
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.Vt cmsghdr
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fields.
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.Pp
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The caller must allocate the buffer and its size can be determined by
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calling
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.Fn inet6_rth_space .
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.Pp
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Upon success the return value is the pointer to the buffer
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.Fa bp ,
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and this is then used as the first argument to the next two functions.
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Upon an error the return value is
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.Dv NULL .
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.\"
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.Ss inet6_rth_add
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The
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.Fn inet6_rth_add
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function
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adds the IPv6 address pointed to by
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.Fa addr
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to the end of the Routing header being constructed.
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.Pp
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If successful, the
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.Va segleft
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member of the Routing Header is updated to
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account for the new address in the Routing header and the return
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value of the function is 0.
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Upon an error the return value of the function is \-1.
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.\"
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.Ss inet6_rth_reverse
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The
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.Fn inet6_rth_reverse
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function
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takes a Routing header extension header
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(pointed to by the first argument
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.Fa in )
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and writes a new Routing header that sends
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datagrams along the reverse of that route.
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Both arguments are allowed to point to the same buffer
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(that is, the reversal can occur in place).
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.Pp
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The return value of the function is 0 on success, or \-1 upon an error.
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.\"
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.Ss inet6_rth_segments
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The
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.Fn inet6_rth_segments
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function
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returns the number of segments
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(addresses)
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contained in the Routing header described by
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.Fa bp .
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On success the return value is
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zero or greater.
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The return value of the function is \-1 upon an error.
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.\"
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.Ss inet6_rth_getaddr
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The
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.Fn inet6_rth_getaddr
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function
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returns a pointer to the IPv6 address specified by
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.Fa index
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(which must have a value between 0 and one less than the value
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returned by
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.Fn inet6_rth_segments )
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in the Routing header described by
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.Fa bp .
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An application should first call
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.Fn inet6_rth_segments
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to obtain the number of segments in the Routing header.
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.Pp
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Upon an error the return value of the function is
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.Dv NULL .
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.\"
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.Sh DIAGNOSTICS
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The
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.Fn inet6_rth_space
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and
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.Fn inet6_rth_getaddr
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functions
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return 0 on errors.
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.Pp
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The
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.Fn inet6_rthdr_init
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function
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returns
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.Dv NULL
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on error.
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The
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.Fn inet6_rth_add
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and
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.Fn inet6_rth_reverse
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functions
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return 0 on success, or \-1 upon an error.
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.\"
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.Sh EXAMPLES
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draft-ietf-ipngwg-rfc2292bis-08.txt
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gives comprehensive examples in Section 22.
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.Pp
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KAME also provides examples in the advapitest directory of its kit.
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.\"
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.Sh SEE ALSO
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.Rs
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.%A W. Stevens
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.%A M. Thomas
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.%A E. Nordmark
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.%A E. Jinmei
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.%T "Advanced Sockets API for IPv6"
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.%N draft-ietf-ipngwg-rfc2292bis-08
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.%D October 2002
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.Re
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.Rs
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.%A S. Deering
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.%A R. Hinden
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.%T "Internet Protocol, Version 6 (IPv6) Specification"
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.%N RFC2460
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.%D December 1998
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.Re
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.Sh HISTORY
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The implementation first appeared in KAME advanced networking kit.
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.Sh STANDARDS
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The functions
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are documented in
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.Dq Advanced Sockets API for IPv6
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.Pq draft-ietf-ipngwg-rfc2292bis-08.txt .
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.\"
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.Sh BUGS
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The text was shamelessly copied from internet-drafts for RFC2292bis.
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