Search for IPv6 hop-by-hop and destination options
#include <netinet/in.h> int inet6_option_find(const struct cmsghdr *cmsg, u_int8_t **tptrp, int type);
- A pointer to the cmsghdr structure that must have been initialized by inet6_option_init().
- The type of option to search for. Either IPV6_HOPOPTS or IPV6_DSTOPTS. This type is stored in the cmsg_type member of the cmsghdr structure pointed to by *cmsgp.
- 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_find() function is similar to inet6_option_next(). It however, lets the caller specify the option type to be searched for, instead of always returning the next option in the ancillary data object. The cmsg is a pointer to the cmsghdr structure of 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 that the function uses 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 must be set to NULL. This function starts searching for an option of the specified type beginning after the value of *tptrp pointer.
- 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.
- 0 with *tptrp pointing to the 8-bit option
- The option was found.
- -1 with *tptrp pointing to NULL
- The option wasn't found.
- -1 with *tptrp pointing to non-NULL
- An error has occurred.