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Caution: This version of this document is no longer maintained. For the latest documentation, see http://www.qnx.com/developers/docs.


Find the next IPv6 hop-by-hop or destination option


#include <netinet/in.h>

int inet6_option_next(const struct cmsghdr *cmsg, 
                      u_int8_t **tptrp);


A pointer to the cmsghdr structure that must have been initialized by inet6_option_init().
A pointer to a pointer to an 8-bit byte.



Use the -l socket option to qcc to link against this library.


This inet6_option_next() function finds 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 0 and *tptrp points to the 8-bit option type field the option data.

The cmsg variable is a pointer to cmsghdr structure for which cmsg_level equals IPPROTO_IPV6 and cmsg_type equals either IPV6_HOPOPTS or IPV6_DSTOPTS.

The tptrp is a pointer to a pointer to an 8-bit byte and *tptrp is used by the function to remember its place in the ancillary data object each time the function is called. The first time you call this function for a given ancillary data object, you must set *tptrp to NULL.

Each time this function returns success, *tptrp points to the 8-bit option type field for the next option to be processed.


The option is located and the *tptrp points to the 8-bit option type field.
-1 with *tptrp pointing to NULL
No more options to process.
-1 with *tptrp pointing to non-NULL
An error has occurred.


RFC 2292

Cancellation point No
Interrupt handler No
Signal handler Yes
Thread Yes

See also:

inet6_option_alloc(), inet6_option_append(), inet6_option_find(), inet6_option_init(), inet6_option_space()

W. Stevens and M. Thomas, Advanced Sockets API for IPv6, RFC 2292, February 1998. Contains examples.

S. Deering and R. Hinden, Internet Protocol, Version 6 (IPv6) Specification, RFC 2460, December 1998.

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