c4d9468ea0
Avoid using parenthesis enclosure macros (.Pq and .Po/.Pc) with plain text. Not only this slows down the mdoc(7) processing significantly, but it also has an undesired (in this case) effect of disabling hyphenation within the entire enclosed block.
446 lines
10 KiB
Groff
446 lines
10 KiB
Groff
.\" Copyright (c) 1983, 1987, 1991, 1993
|
|
.\" The Regents of the University of California. All rights reserved.
|
|
.\"
|
|
.\" Redistribution and use in source and binary forms, with or without
|
|
.\" modification, are permitted provided that the following conditions
|
|
.\" are met:
|
|
.\" 1. Redistributions of source code must retain the above copyright
|
|
.\" notice, this list of conditions and the following disclaimer.
|
|
.\" 2. Redistributions in binary form must reproduce the above copyright
|
|
.\" notice, this list of conditions and the following disclaimer in the
|
|
.\" documentation and/or other materials provided with the distribution.
|
|
.\" 3. All advertising materials mentioning features or use of this software
|
|
.\" must display the following acknowledgement:
|
|
.\" This product includes software developed by the University of
|
|
.\" California, Berkeley and its contributors.
|
|
.\" 4. Neither the name of the University nor the names of its contributors
|
|
.\" may be used to endorse or promote products derived from this software
|
|
.\" without specific prior written permission.
|
|
.\"
|
|
.\" THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
|
|
.\" ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
|
|
.\" IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
|
|
.\" ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
|
|
.\" FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
|
|
.\" DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
|
|
.\" OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
|
|
.\" HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
|
|
.\" LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
|
|
.\" OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
|
|
.\" SUCH DAMAGE.
|
|
.\"
|
|
.\" $Id: inet6_option_space.3,v 1.4 2000/02/05 10:32:24 jinmei Exp $
|
|
.\" $FreeBSD$
|
|
.\"
|
|
.Dd December 10, 1999
|
|
.Dt INET6_OPTION_SPACE 3
|
|
.Os
|
|
.\"
|
|
.Sh NAME
|
|
.Nm inet6_option_space ,
|
|
.Nm inet6_option_init ,
|
|
.Nm inet6_option_append ,
|
|
.Nm inet6_option_alloc ,
|
|
.Nm inet6_option_next ,
|
|
.Nm inet6_option_find
|
|
.Nd IPv6 Hop-by-Hop and Destination Options manipulation
|
|
.\"
|
|
.Sh LIBRARY
|
|
.Lb libc
|
|
.Sh SYNOPSIS
|
|
.Fd #include <sys/types.h>
|
|
.Fd #include <netinet/in.h>
|
|
.Ft "int"
|
|
.Fn inet6_option_space "int nbytes"
|
|
.Ft "int"
|
|
.Fn inet6_option_init "void *bp" "struct cmsghdr **cmsgp" "int type"
|
|
.Ft "int"
|
|
.Fn inet6_option_append "struct cmsghdr *cmsg" "const u_int8_t *typep" "int multx" "int plusy"
|
|
.Ft "u_int8_t *"
|
|
.Fn inet6_option_alloc "struct cmsghdr *cmsg" "int datalen" "int multx" "int plusy"
|
|
.Ft "int"
|
|
.Fn inet6_option_next "const struct cmsghdr *cmsg" "u_int8_t **tptrp"
|
|
.Ft "int"
|
|
.Fn inet6_option_find "const struct cmsghdr *cmsg" "u_int8_t **tptrp" "int type"
|
|
.\"
|
|
.Sh DESCRIPTION
|
|
.\"
|
|
Building and parsing the Hop-by-Hop and Destination options is
|
|
complicated due to alignment constranints, padding and
|
|
ancillary data manipulation.
|
|
RFC2292 defines a set of functions to help the application.
|
|
The function prototypes for
|
|
these functions are all in the
|
|
.Aq Li netinet/in.h
|
|
header.
|
|
.\"
|
|
.Ss inet6_option_space
|
|
.Fn inet6_option_space
|
|
returns the number of bytes required to hold an option when it is stored as
|
|
ancillary data, including the
|
|
.Li cmsghdr
|
|
structure at the beginning,
|
|
and any padding at the end
|
|
(to make its size a multiple of 8 bytes).
|
|
The argument is the size of the structure defining the option,
|
|
which must include any pad bytes at the beginning
|
|
(the value
|
|
.Li y
|
|
in the alignment term
|
|
.Dq Li "xn + y" ) ,
|
|
the type byte, the length byte, and the option data.
|
|
.Pp
|
|
Note: If multiple options are stored in a single ancillary data
|
|
object, which is the recommended technique, this function
|
|
overestimates the amount of space required by the size of
|
|
.Li N-1
|
|
.Li cmsghdr
|
|
structures,
|
|
where
|
|
.Li N
|
|
is the number of options to be stored in the object.
|
|
This is of little consequence, since it is assumed that most
|
|
Hop-by-Hop option headers and Destination option headers carry only
|
|
one option
|
|
(appendix B of [RFC-2460]).
|
|
.\"
|
|
.Ss inet6_option_init
|
|
.Fn inet6_option_init
|
|
is called once per ancillary data object that will
|
|
contain either Hop-by-Hop or Destination options.
|
|
It returns
|
|
.Li 0
|
|
on success or
|
|
.Li -1
|
|
on an error.
|
|
.Pp
|
|
.Fa bp
|
|
is a pointer to previously allocated space that will contain the
|
|
ancillary data object.
|
|
It must be large enough to contain all the
|
|
individual options to be added by later calls to
|
|
.Fn inet6_option_append
|
|
and
|
|
.Fn inet6_option_alloc .
|
|
.Pp
|
|
.Fa cmsgp
|
|
is a pointer to a pointer to a
|
|
.Li cmsghdr
|
|
structure.
|
|
.Fa *cmsgp
|
|
is initialized by this function to point to the
|
|
.Li cmsghdr
|
|
structure constructed by this function in the buffer pointed to by
|
|
.Fa bp .
|
|
.Pp
|
|
.Fa type
|
|
is either
|
|
.Dv IPV6_HOPOPTS
|
|
or
|
|
.Dv IPV6_DSTOPTS .
|
|
This
|
|
.Fa type
|
|
is stored in the
|
|
.Li cmsg_type
|
|
member of the
|
|
.Li cmsghdr
|
|
structure pointed to by
|
|
.Fa *cmsgp .
|
|
.\"
|
|
.Ss inet6_option_append
|
|
This function appends a Hop-by-Hop option or a Destination option
|
|
into an ancillary data object that has been initialized by
|
|
.Fn inet6_option_init .
|
|
This function returns
|
|
.Li 0
|
|
if it succeeds or
|
|
.Li -1
|
|
on an error.
|
|
.Pp
|
|
.Fa cmsg
|
|
is a pointer to the
|
|
.Li cmsghdr
|
|
structure that must have been
|
|
initialized by
|
|
.Fn inet6_option_init .
|
|
.Pp
|
|
.Fa typep
|
|
is a pointer to the 8-bit option type.
|
|
It is assumed that this
|
|
field is immediately followed by the 8-bit option data length field,
|
|
which is then followed immediately by the option data.
|
|
The caller
|
|
initializes these three fields
|
|
(the type-length-value, or TLV)
|
|
before calling this function.
|
|
.Pp
|
|
The option type must have a value from
|
|
.Li 2
|
|
to
|
|
.Li 255 ,
|
|
inclusive.
|
|
.Li ( 0
|
|
and
|
|
.Li 1
|
|
are reserved for the
|
|
.Li Pad1
|
|
and
|
|
.Li PadN
|
|
options, respectively.)
|
|
.Pp
|
|
The option data length must have a value between
|
|
.Li 0
|
|
and
|
|
.Li 255 ,
|
|
inclusive, and is the length of the option data that follows.
|
|
.Pp
|
|
.Fa multx
|
|
is the value
|
|
.Li x
|
|
in the alignment term
|
|
.Dq Li xn + y .
|
|
It must have a value of
|
|
.Li 1 ,
|
|
.Li 2 ,
|
|
.Li 4 ,
|
|
or
|
|
.Li 8 .
|
|
.Pp
|
|
.Fa plusy
|
|
is the value
|
|
.Li y
|
|
in the alignment term
|
|
.Dq Li xn + y .
|
|
It must have a value between
|
|
.Li 0
|
|
and
|
|
.Li 7 ,
|
|
inclusive.
|
|
.\"
|
|
.Ss inet6_option_alloc
|
|
This function appends a Hop-by-Hop option or a Destination option
|
|
into an ancillary data object that has been initialized by
|
|
.Fn inet6_option_init .
|
|
This function returns a pointer to the 8-bit
|
|
option type field that starts the option on success, or
|
|
.Dv NULL
|
|
on an error.
|
|
.Pp
|
|
The difference between this function and
|
|
.Fn inet6_option_append
|
|
is that the latter copies the contents of a previously built option into
|
|
the ancillary data object while the current function returns a
|
|
pointer to the space in the data object where the option's TLV must
|
|
then be built by the caller.
|
|
.Pp
|
|
.Fa cmsg
|
|
is a pointer to the
|
|
.Li cmsghdr
|
|
structure that must have been
|
|
initialized by
|
|
.Fn inet6_option_init .
|
|
.Pp
|
|
.Fa datalen
|
|
is the value of the option data length byte for this option.
|
|
This value is required as an argument to allow the function to
|
|
determine if padding must be appended at the end of the option.
|
|
(The
|
|
.Fn inet6_option_append
|
|
function does not need a data length argument
|
|
since the option data length must already be stored by the caller.)
|
|
.Pp
|
|
.Fa multx
|
|
is the value
|
|
.Li x
|
|
in the alignment term
|
|
.Dq Li xn + y .
|
|
It must have a value of
|
|
.Li 1 ,
|
|
.Li 2 ,
|
|
.Li 4 ,
|
|
or
|
|
.Li 8 .
|
|
.Pp
|
|
.Fa plusy
|
|
is the value
|
|
.Li y
|
|
in the alignment term
|
|
.Dq Li xn + y .
|
|
It must have a value between
|
|
.Li 0
|
|
and
|
|
.Li 7 ,
|
|
inclusive.
|
|
.\"
|
|
.Ss inet6_option_next
|
|
This function processes the next Hop-by-Hop option or Destination
|
|
option in an ancillary data object.
|
|
If another option remains to be
|
|
processed, the return value of the function is
|
|
.Li 0
|
|
and
|
|
.Fa *tptrp
|
|
points to
|
|
the 8-bit option type field
|
|
(which is followed by the 8-bit option
|
|
data length, followed by the option data).
|
|
If no more options remain
|
|
to be processed, the return value is
|
|
.Li -1
|
|
and
|
|
.Fa *tptrp
|
|
is
|
|
.Dv NULL .
|
|
If an error occurs, the return value is
|
|
.Li -1
|
|
and
|
|
.Fa *tptrp
|
|
is not
|
|
.Dv NULL .
|
|
.Pp
|
|
.Fa cmsg
|
|
is a pointer to
|
|
.Li cmsghdr
|
|
structure of which
|
|
.Li cmsg_level
|
|
equals
|
|
.Dv IPPROTO_IPV6
|
|
and
|
|
.Li cmsg_type
|
|
equals either
|
|
.Dv IPV6_HOPOPTS
|
|
or
|
|
.Dv IPV6_DSTOPTS .
|
|
.Pp
|
|
.Fa tptrp
|
|
is a pointer to a pointer to an 8-bit byte and
|
|
.Fa *tptrp
|
|
is used
|
|
by the function to remember its place in the ancillary data object
|
|
each time the function is called.
|
|
The first time this function is
|
|
called for a given ancillary data object,
|
|
.Fa *tptrp
|
|
must be set to
|
|
.Dv NULL .
|
|
.Pp
|
|
Each time this function returns success,
|
|
.Fa *tptrp
|
|
points to the 8-bit
|
|
option type field for the next option to be processed.
|
|
.\"
|
|
.Ss inet6_option_find
|
|
This function is similar to the previously described
|
|
.Fn inet6_option_next
|
|
function, except this function lets the caller
|
|
specify the option type to be searched for, instead of always
|
|
returning the next option in the ancillary data object.
|
|
.Fa cmsg
|
|
is a
|
|
pointer to
|
|
.Li cmsghdr
|
|
structure of which
|
|
.Li cmsg_level
|
|
equals
|
|
.Dv IPPROTO_IPV6
|
|
and
|
|
.Li cmsg_type
|
|
equals either
|
|
.Dv IPV6_HOPOPTS
|
|
or
|
|
.Dv IPV6_DSTOPTS .
|
|
.Pp
|
|
.Fa tptrp
|
|
is a pointer to a pointer to an 8-bit byte and
|
|
.Fa *tptrp
|
|
is used
|
|
by the function to remember its place in the ancillary data object
|
|
each time the function is called.
|
|
The first time this function is
|
|
called for a given ancillary data object,
|
|
.Fa *tptrp
|
|
must be set to
|
|
.Dv NULL .
|
|
.Pa
|
|
This function starts searching for an option of the specified type
|
|
beginning after the value of
|
|
.Fa *tptrp .
|
|
If an option of the specified
|
|
type is located, this function returns
|
|
.Li 0
|
|
and
|
|
.Fa *tptrp
|
|
points to the 8-
|
|
bit option type field for the option of the specified type.
|
|
If an
|
|
option of the specified type is not located, the return value is
|
|
.Li -1
|
|
and
|
|
.Fa *tptrp
|
|
is
|
|
.Dv NULL .
|
|
If an error occurs, the return value is
|
|
.Li -1
|
|
and
|
|
.Fa *tptrp
|
|
is not
|
|
.Dv NULL .
|
|
.\"
|
|
.Sh DIAGNOSTICS
|
|
.Fn inet6_option_init
|
|
and
|
|
.Fn inet6_option_append
|
|
return
|
|
.Li 0
|
|
on success or
|
|
.Li -1
|
|
on an error.
|
|
.Pp
|
|
.Fn inet6_option_alloc
|
|
returns
|
|
.Dv NULL
|
|
on an error.
|
|
.Pp
|
|
On errors,
|
|
.Fn inet6_option_next
|
|
and
|
|
.Fn inet6_option_find
|
|
return
|
|
.Li -1
|
|
setting
|
|
.Fa *tptrp
|
|
to non
|
|
.Dv NULL
|
|
value.
|
|
.\"
|
|
.Sh EXAMPLES
|
|
RFC2292 gives comprehensive examples in chapter 6.
|
|
.\"
|
|
.Sh SEE ALSO
|
|
.Rs
|
|
.%A W. Stevens
|
|
.%A M. Thomas
|
|
.%T "Advanced Sockets API for IPv6"
|
|
.%N RFC2292
|
|
.%D February 1998
|
|
.Re
|
|
.Rs
|
|
.%A S. Deering
|
|
.%A R. Hinden
|
|
.%T "Internet Protocol, Version 6 (IPv6) Specification"
|
|
.%N RFC2460
|
|
.%D December 1998
|
|
.Re
|
|
.\"
|
|
.Sh HISTORY
|
|
The implementation first appeared in KAME advanced networking kit.
|
|
.\"
|
|
.Sh STANDARDS
|
|
The functions
|
|
are documented in
|
|
.Dq Advanced Sockets API for IPv6
|
|
(RFC2292).
|
|
.\"
|
|
.Sh BUGS
|
|
The text was shamelessly copied from RFC2292.
|