tst_inet6_opt_init_calc - Calculate the needed buffer size for the empty extension header
To check that inet6_opt_init_calc() can be used to calculate the needed buffer size for the empty extension header while extbuf is NULL.
./tst_inet6_opt_init_calc [-tooloption ...] -tooloption : v6api tool option
1. Calculate the needed buffer size if extlen is 0 2. Check A: The needed buffer size is 2 3. Calculate the needed buffer size if extlen is 8 4. Check B: The needed buffer size is 2 5. Calculate the needed buffer size if extlen is 100 6. Check C: The needed buffer size is 2
None
RFC 3542
10.1. inet6_opt_init
int inet6_opt_init(void *extbuf, socklen_t extlen);
This function returns the number of bytes needed for the empty extension header i.e., without any options. If extbuf is not NULL it also initializes the extension header to have the correct length field. In that case if the extlen value is not a positive (i.e., non-zero) multiple of 8 the function fails and returns -1.
(Note: since the return value on success is based on a "constant" parameter, i.e., the empty extension header, an implementation may return a constant value. However, this specification does not require the value be constant, and leaves it as implementation dependent. The application should not assume a particular constant value as a successful return value of this function.)