socketcan_alt/
cmsg.rs

1use std::mem::{align_of, size_of};
2
3#[non_exhaustive]
4pub enum Cmsg<'a> {
5    Timestamping(&'a [libc::timespec; 3]),
6    #[doc(hidden)]
7    Other(&'a libc::cmsghdr),
8}
9
10impl<'a> Cmsg<'a> {
11    pub fn space() -> usize {
12        [size_of::<[libc::timespec; 3]>()]
13            .iter()
14            .map(|&size| unsafe { libc::CMSG_SPACE(size as _) })
15            .max()
16            .unwrap_or_default() as _
17    }
18}
19
20pub struct CmsgIter<'a> {
21    msg: libc::msghdr,
22    cmsg: Option<&'a libc::cmsghdr>,
23}
24
25impl CmsgIter<'_> {
26    pub(crate) unsafe fn from_raw(msg: libc::msghdr) -> Option<Self> {
27        if msg.msg_flags & libc::MSG_CTRUNC == 0 {
28            Some(Self {
29                msg,
30                cmsg: libc::CMSG_FIRSTHDR(&msg).as_ref(),
31            })
32        } else {
33            None
34        }
35    }
36}
37
38impl<'a> Iterator for CmsgIter<'a> {
39    type Item = Cmsg<'a>;
40
41    fn next(&mut self) -> Option<Self::Item> {
42        let cmsg = self.cmsg?;
43        self.cmsg = unsafe { libc::CMSG_NXTHDR(&self.msg, cmsg).as_ref() };
44        Some(match (cmsg.cmsg_level, cmsg.cmsg_type) {
45            (libc::SOL_SOCKET, libc::SCM_TIMESTAMPING) => {
46                Cmsg::Timestamping(unsafe { cmsg_data(cmsg) })
47            }
48            _ => Cmsg::Other(cmsg),
49        })
50    }
51}
52
53unsafe fn cmsg_data<T>(cmsg: &libc::cmsghdr) -> &T {
54    assert_eq!(cmsg.cmsg_len, libc::CMSG_LEN(size_of::<T>() as _) as _);
55    let data = libc::CMSG_DATA(cmsg);
56    assert_eq!(data.align_offset(align_of::<T>()), 0);
57    &*(data as *const T)
58}
socketcan_alt/cmsg.rs

socketcan_alt/
cmsg.rs
