x/sys/unix: expose Setsockopt for CAN Filtering #29638
Description
Currently the support for AF_CAN sockets in x/sys/unix is not very useful, because kernel message filtering is not supported due to missing availability of the relevant sockopt. This sadly defeats the purpose of using go for CAN over other languages.
It also can not be worked around easily, as the unsafe setsockopt is only available in private. (Which is reasonable, but one needs unsafe to do ioctl SIOCGIFINDEX anyway when working with CAN sockets)
This comment comment on the original Request for AF_CAN sockets hints at the issue.
So I can see this being solved either with exposition of raw Setsockopt with unsafe pointers or introduction of a separate SetSockoptCanRawFilter function:
type CanFilter struct {
Id uint32
Mask uint32
}
func SetsockoptCanRawFilter(fd, level, opt int, rfilter []CanFilter) error {
...
}Which could be used as follows:
func main() {
...
fd, _ := unix.Socket(unix.AF_CAN, unix.SOCK_RAW, unix.CAN_RAW)
rfilter := make([]unix.CanFilter, 2)
rfilter[0].Id = 0x123
rfilter[0].Mask = unix.CAN_SFF_MASK
rfilter[1].Id = 0x124
rfilter[1].Mask = unix.CAN_SFF_MASK
SetsockoptCanRawFilter(fd, unix.SOL_CAN_RAW, unix.CAN_RAW_FILTER, rfilter)
...
}