334 lines
8.9 KiB
Groff
334 lines
8.9 KiB
Groff
.\" Copyright (c) 1983, 1987, 1991, 1993
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.\" The Regents of the University of California. 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. All advertising materials mentioning features or use of this software
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.\" must display the following acknowledgement:
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.\" This product includes software developed by the University of
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.\" California, Berkeley and its contributors.
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.\" 4. Neither the name of the University 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 REGENTS 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 REGENTS 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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.\" $Id: inet6_rthdr_space.3,v 1.5 2000/02/05 13:19:07 jinmei Exp $
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.\" $FreeBSD$
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.\"
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.Dd December 10, 1999
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.Dt INET6_RTHDR_SPACE 3
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.Os
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.\"
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.Sh NAME
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.Nm inet6_rthdr_space ,
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.Nm inet6_rthdr_init ,
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.Nm inet6_rthdr_add ,
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.Nm inet6_rthdr_lasthop ,
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.Nm inet6_rthdr_reverse ,
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.Nm inet6_rthdr_segments ,
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.Nm inet6_rthdr_getaddr ,
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.Nm inet6_rthdr_getflags
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.Nd IPv6 Routing Header Options manipulation
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.\"
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.Sh LIBRARY
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.Lb libc
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.Sh SYNOPSIS
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.In sys/types.h
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.In netinet/in.h
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.Ft size_t
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.Fn inet6_rthdr_space "int type" "int segments"
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.Ft "struct cmsghdr *"
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.Fn inet6_rthdr_init "void *bp" "int type"
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.Ft int
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.Fn inet6_rthdr_add "struct cmsghdr *cmsg" "const struct in6_addr *addr" "unsigned int flags"
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.Ft int
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.Fn inet6_rthdr_lasthop "struct cmsghdr *cmsg" "unsigned int flags"
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.Ft int
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.Fn inet6_rthdr_reverse "const struct cmsghdr *in" "struct cmsghdr *out"
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.Ft int
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.Fn inet6_rthdr_segments "const struct cmsghdr *cmsg"
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.Ft "struct in6_addr *"
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.Fn inet6_rthdr_getaddr "struct cmsghdr *cmsg" "int index"
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.Ft int
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.Fn inet6_rthdr_getflags "const struct cmsghdr *cmsg" "int index"
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.\"
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.Sh DESCRIPTION
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RFC2292 IPv6 advanced API defines eight
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functions that the application calls to build and examine a Routing
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header. Four functions build a Routing header:
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.Bl -hang
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.It Fn inet6_rthdr_space
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return #bytes required for ancillary data
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.It Fn inet6_rthdr_init
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initialize ancillary data for Routing header
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.It Fn inet6_rthdr_add
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add IPv6 address & flags to Routing header
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.It Fn inet6_rthdr_lasthop
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specify the flags for the final hop
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.El
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.Pp
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Four functions deal with a returned Routing header:
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.Bl -hang
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.It Fn inet6_rthdr_reverse
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reverse a Routing header
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.It Fn inet6_rthdr_segments
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return #segments in a Routing header
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.It Fn inet6_rthdr_getaddr
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fetch one address from a Routing header
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.It Fn inet6_rthdr_getflags
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fetch one flag 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 all in the
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.In netinet/in.h
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header.
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.\"
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.Ss inet6_rthdr_space
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This function returns the number of bytes required to hold a Routing
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header of the specified
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.Fa type
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containing the specified number of
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.Fa segments
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(addresses).
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For an IPv6 Type 0 Routing header, the number
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of segments must be between 1 and 23, inclusive. The return value
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includes the size of the cmsghdr structure that precedes the Routing
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header, and any required padding.
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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
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.Li msg_control
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buffer.
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.\"
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.Ss inet6_rthdr_init
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This function initializes the buffer pointed to by
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.Fa bp
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to contain a
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.Li cmsghdr
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structure followed by a Routing header of the specified
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.Fa type .
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The
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.Li cmsg_len
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member of the
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.Li cmsghdr
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structure is initialized to the
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size of the structure plus the amount of space required by the
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Routing header.
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The
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.Li cmsg_level
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and
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.Li cmsg_type
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members are also initialized as required.
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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_rthdr_space .
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.Pp
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Upon success the return value is the pointer to the
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.Li cmsghdr
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structure, and this is then used as the first argument to the next
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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_rthdr_add
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This function adds the address pointed to by
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.Fa addr
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to the end of the
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Routing header being constructed and sets the type of this hop to the
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value of
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.Fa flags .
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For an IPv6 Type 0 Routing header,
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.Fa flags
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must be
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either
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.Dv IPV6_RTHDR_LOOSE
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or
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.Dv IPV6_RTHDR_STRICT .
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.Pp
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If successful, the
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.Li cmsg_len
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member of the
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.Li cmsghdr
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structure is
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updated to account for the new address in the Routing header and the
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return value of the function is 0.
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Upon an error the return value of
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the function is -1.
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.\"
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.Ss inet6_rthdr_lasthop
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This function specifies the Strict/Loose flag for the final hop of a
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Routing header.
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For an IPv6 Type 0 Routing header,
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.Fa flags
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must be either
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.Dv IPV6_RTHDR_LOOSE
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or
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.Dv IPV6_RTHDR_STRICT .
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.Pp
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The return value of the function is 0 upon success, or -1 upon an error.
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.Pp
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Notice that a Routing header specifying
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.Li N
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intermediate nodes requires
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.Li N+1
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Strict/Loose flags.
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This requires
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.Li N
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calls to
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.Fn inet6_rthdr_add
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followed by one call to
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.Fn inet6_rthdr_lasthop .
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.\"
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.Ss inet6_rthdr_reverse
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This function is not yet implemented.
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When implemented, this should behave as follows.
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.Pp
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This function takes a Routing header that was received as ancillary
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data
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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
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header that sends datagrams along the reverse of that route.
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Both
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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
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error.
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.\"
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.Ss inet6_rthdr_segments
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This function returns the number of segments
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(addresses)
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contained in
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the Routing header described by
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.Fa cmsg .
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On success the return value is
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between 1 and 23, inclusive.
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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_rthdr_getaddr
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This function 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 1 and the value returned by
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.Fn inet6_rthdr_segments )
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in the Routing header described by
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.Fa cmsg .
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An
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application should first call
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.Fn inet6_rthdr_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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.Ss inet6_rthdr_getflags
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This function returns the flags value specified by
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.Fa index
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(which must
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have a value between 0 and the value returned by
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.Fn inet6_rthdr_segments )
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in the Routing header described by
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.Fa cmsg .
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For an IPv6 Type 0 Routing header the return value will be either
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.Dv IPV6_RTHDR_LOOSE
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or
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.Dv IPV6_RTHDR_STRICT .
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.Pp
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Upon an error the return value of the function is -1.
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.Pp
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Note: Addresses are indexed starting at 1, and flags starting at 0,
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to maintain consistency with the terminology and figures in RFC2460.
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.\"
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.Sh DIAGNOSTICS
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The
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.Fn inet6_rthdr_space
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function
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returns 0 on errors.
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.Pp
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The
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.Fn inet6_rthdr_add ,
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.Fn inet6_rthdr_lasthop
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and
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.Fn inet6_rthdr_reverse
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functions
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return 0 on success, and returns -1 on error.
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.Pp
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The
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.Fn inet6_rthdr_init
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and
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.Fn inet6_rthdr_getaddr
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functions
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return
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.Dv NULL
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on error.
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.Pp
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The
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.Fn inet6_rthdr_segments
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and
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.Fn inet6_rthdr_getflags
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functions
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return -1 on error.
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.\"
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.Sh EXAMPLES
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RFC2292 gives comprehensive examples in chapter 8.
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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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.%T "Advanced Sockets API for IPv6"
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.%N RFC2292
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.%D February 1998
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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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.\"
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.Sh HISTORY
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The implementation first appeared in KAME advanced networking kit.
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.\"
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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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(RFC2292).
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.\"
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.Sh BUGS
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The text was shamelessly copied from RFC2292.
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.Pp
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The
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.Fn inet6_rthdr_reverse
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function
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is not implemented yet.
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