inet6_opt(3SOCKET) Sockets Library Functions inet6_opt(3SOCKET)
NAME
inet6_opt - Option manipulation mechanism
SYNOPSIS
cc [ flag ... ] file ... -lsocket -lnsl [library...]
#include <netinet/in.h>
int inet_6_opt_init(void *extbuf, socklen_t extdlen);
int inet6_opt_append(void *extbuf, socklen_t extlen, int offset, uint8_t type, socklen_t len, uint_t align, void **databufp);
int inet_6_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, uint8_t *typep, socklen_t *lenp, void **databufp);
int inet6_opt_find(void *extbuf, socklen_t extlen, int offset, uint8_t type, socklen_t *lenp, void **databufp);
intinet6_opt_get_val(void *databuf, int offset, void *val, socklen_t *vallen);
DESCRIPTION
The inet6_opt functions enable users to manipulate options without having to know the structure of the option header.
The inet6_opt_init() function returns the number of bytes needed for the empty extension header, that is, without any options. If extbuf is
not NULL, it also initializes the extension header to the correct length field. If the extlen value is not a positive (or non-zero) multi-
ple of 8, the function fails and returns -1.
The inet6_opt_append() function returns the updated total length while adding an option with length len and alignment align. If extbuf is
not NULL, then, in addition to returning the length, the function inserts any needed Pad option, initializes the option (setting the type
and length fields) and returns a pointer to the location for the option content in databufp. If the option does not fit in the extension
header buffer, the function returns -1. type is the 8-bit option type. len is the length of the option data, excluding the option type and
option length fields. Once inet6_opt_append() is called, the application can use the databuf directly, or use inet6_opt_set_val() to spec-
ify the content of the option. The option type must have a value from 2 to 255, inclusive. (0 and 1 are reserved for the Pad1 and PadN
options, respectively.) The option data length must have a value between 0 and 255, inclusive, and is the length of the option data that
follows. The align parameter must have a value of 1, 2, 4, or 8. The align value cannot exceed the value of len.
The inet6_opt_finish() function returns the updated total length taking into account the final padding of the extension header to make it a
multiple of 8 bytes. If extbuf is not NULL, the function also initializes the option by inserting a Pad1 or PadN option of the proper
length. If the necessary pad does not fit in the extension header buffer, the function returns -1.
The inet6_opt_set_val() function inserts data items of various sizes in the data portion of the option. val should point to the data data
to be inserted. Offset specifies in which data portion of the option the value should be inserted. The first byte after the option type and
length is accessed by specifying an offset of zero.
The inet6_opt_next() function parses received option extension headers returning the next option. extbuf and extlen specify the extension
header. Offset should either be zero (for the first option) or the length returned by a previous call to inet6_opt_next() or
inet6_opt_find(), and specifies where to continue scanning the extension buffer. The subsequent option is returned by updating typep, lenp,
and databufp. typep stores the option type, lenp stores the length of the option data (that is, excluding the option type and option length
fields), and databufp points to the data field of the option.
The inet6_opt_find() function is similar to the inet6_opt_next() function. However, unlike inet6_opt_next(), this function enables the
caller to specify the option type to be searched for, instead of returning the next option in the extension header.
The inet6_opt_get_val() function extracts data items of various sizes in the portion of the option. val should point to the destination for
the extracted data. Offset specifies at which point in the option's data portion the value should be extracted. The first byte following
the option type and length is accessed by specifying an offset of zero.
RETURN VALUES
The inet6_opt_init() function returns the number of bytes needed for the empty extension header. If the extlen value is not a positive (or
non-zero) multiple of 8, the function fails and returns -1.
The inet6_opt_append() function returns the updated total length.
The inet6_opt_finish() function returns the updated total length.
The inet6_opt_set_val() function returns the offset for the subsequent field.
The inet6_opt_next() function returns the updated "previous" length computed by advancing past the option that was returned. When there are
no additional options or if the option extension header is malformed, the return value is -1.
The inet6_opt_find() function returns the updated "previous" total length. If an option of the specified type is not located, the return
value is -1. If the option extension header is malformed, the return value is -1.
The inet6_opt_get_val() function returns the offset for the next field (that is, offset + vallen) which can be used when extracting option
content with multiple fields.
ATTRIBUTES
See attributes(5) for descriptions of the following attributes:
+-----------------------------+-----------------------------+
| ATTRIBUTE TYPE | ATTRIBUTE VALUE |
+-----------------------------+-----------------------------+
|MT-Level |Safe |
+-----------------------------+-----------------------------+
|Interface Stability |Standard |
+-----------------------------+-----------------------------+
SEE ALSO
RFC 3542- Advanced Sockets Application Programming Interface (API) for IPv6, The Internet Society. May 2003
SunOS 5.10 13 Nov 2003 inet6_opt(3SOCKET)