INET6_OPT_INIT(3) | Library Functions Manual | INET6_OPT_INIT(3) |
inet6_opt_init
,
inet6_opt_append
,
inet6_opt_finish
,
inet6_opt_set_val
,
inet6_opt_next
,
inet6_opt_find
,
inet6_opt_get_val
—
#include <netinet/in.h>
int
inet6_opt_init
(void
*extbuf, socklen_t
extlen);
int
inet6_opt_append
(void
*extbuf, socklen_t
extlen, int offset,
u_int8_t type,
socklen_t len,
u_int8_t align,
void **databufp);
int
inet6_opt_finish
(void
*extbuf, socklen_t
extlen, int
offset);
int
inet6_opt_set_val
(void
*databuf, int
offset, void *val,
socklen_t vallen);
int
inet6_opt_next
(void
*extbuf, socklen_t
extlen, int offset,
u_int8_t *typep,
socklen_t *lenp,
void **databufp);
int
inet6_opt_find
(void
*extbuf, socklen_t
extlen, int offset,
u_int8_t type,
socklen_t *lenp,
void **databufp);
int
inet6_opt_get_val
(void
*databuf, socklen_t
offset, void *val,
socklen_t vallen);
<netinet/in.h>
header file.
inet6_opt_init
() function returns the number of
bytes needed for an empty extension header, one without any options. If the
extbuf argument points to a valid section of memory then
the inet6_opt_init
() function also initializes the
extension header's length field. When attempting to initialize an extension
buffer passed in the extbuf argument
extlen must be a positive multiple of 8 or else the
function fails and returns -1 to the caller.
inet6_opt_append
() function can perform to different
jobs. When a valid extbuf argument is supplied it
appends an option to the extension buffer and returns the updated total length
as well as a pointer to the newly created option in
databufp. If the value of extbuf
is NULL
then the
inet6_opt_append
(function,
only, reports,
what, the,
total, length,
would) be if the option were actually appended. The
len and align arguments specify
the length of the option and the required data alignment which must be used
when appending the option. The offset argument should be
the length returned by the inet6_opt_init
() function
or a previous call to inet6_opt_append
().
The type argument is the 8-bit option type.
After inet6_opt_append
() has been called,
the application can use the buffer pointed to by
databufp directly, or use
inet6_opt_set_val
() to specify the data to be
contained in the option.
Option types of 0
and
1
are reserved for the Pad1
and PadN
options. All other values from 2 through
255 may be used by applications.
The length of the option data is contained in an 8-bit value and so may contain any value from 0 through 255.
The align parameter must have a value of 1, 2, 4, or 8 and cannot exceed the value of len. The alignment values represent no alignment, 16 bit, 32 bit and 64 bit alignments respectively.
inet6_opt_finish
() calculates the final padding
necessary to make the extension header a multiple of 8 bytes, as required by
the IPv6 extension header specification, and returns the extension header's
updated total length. The offset argument should be the
length returned by inet6_opt_init
() or
inet6_opt_append
(). When extbuf
is not NULL
the function also sets up the appropriate
padding bytes by inserting a Pad1 or PadN option of the proper length.
If the extension header is too small to contain the proper padding then an error of -1 is returned to the caller.
inet6_opt_set_val
() function inserts data items of
various sizes into the data portion of the option. The
databuf argument is a pointer to memory that was
returned by the inet6_opt_append
() call and the
offset argument specifies where the option should be placed in
the data buffer. The val argument points to an
area of memory containing the data to be inserted into the extension header,
and the vallen argument indicates how much data to copy.
The caller should ensure that each field is aligned on its natural boundaries as described in Appendix B of RFC2460.
The function returns the offset for the next field which is calculated as offset + vallen and is used when composing options with multiple fields.
inet6_opt_next
() function parses received extension
headers. The extbuf and extlen
arguments specify the location and length of the extension header being
parsed. The offset argument should either be zero, for
the first option, or the length value returned by a previous call to
inet6_opt_next
() or
inet6_opt_find
(). The return value specifies the
position where to continue scanning the extension buffer. The option is
returned in the arguments typep,
lenp, and databufp.
typep, lenp, and
databufp point to the 8-bit option type, the 8-bit
option length and the option data respectively. This function does not return
any PAD1 or PADN options. When an error occurs or there are no more options
the return value is -1.
inet6_opt_find
() function searches the extension
buffer for a particular option type, passed in through the
type argument. If the option is found then the
lenp and databufp arguments are
updated to point to the option's length and data respectively.
extbuf and extlen must point to a
valid extension buffer and give its length. The offset
argument can be used to search from a location anywhere in the extension
header.
inet6_opt_get_val
() function extracts data items of
various sizes in the data portion of the option. The
databuf is a pointer returned by the
inet6_opt_next
() or
inet6_opt_find
() functions. The
val argument points where the data will be extracted.
The offset argument specifies from where in the data
portion of the option the value should be extracted; the first byte of option
data is specified by an offset of zero.
It is expected that each field is aligned on its natural boundaries as described in Appendix B of RFC2460.
The function returns the offset for the next field by calculating offset + vallen which can be used when extracting option content with multiple fields. Robust receivers must verify alignment before calling this function.
KAME also provides examples in the advapitest directory of its kit.
W. Stevens, M. Thomas, E. Nordmark, and T. Jinmei, Advanced Sockets API for IPv6, RFC3542, October 2002.
S. Deering and R. Hinden, Internet Protocol, Version 6 (IPv6) Specification, RFC2460, December 1998.
December 23, 2004 | NetBSD 9.2 |