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