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)