inet6_option_next()

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);

Arguments:

cmsg

A pointer to the cmsghdr structure that must have been initialized by inet6_option_init().

tptrp

A pointer to a pointer to an 8-bit byte.

Library:

libsocket

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

Description:

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.

Based on:

• 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.

Returns:

0

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.

Classification:

RFC 2292