socket set_mark addition.

[devnexen]

to be able to set a marker/id on the socket for network filtering
(iptables/ipfw here) purpose.

[rust-highfive]

Hey! It looks like you've submitted a new PR for the library teams!

If this PR contains changes to any rust-lang/rust public library APIs then please comment with r? rust-lang/libs-api @rustbot label +T-libs-api -T-libs to request review from a libs-api team reviewer. If you're unsure where your change falls no worries, just leave it as is and the reviewer will take a look and make a decision to forward on if necessary.

Examples of T-libs-api changes:

• Stabilizing library features
• Introducing insta-stable changes such as new implementations of existing stable traits on existing stable types
• Introducing new or changing existing unstable library APIs (excluding permanently unstable features / features without a tracking issue)
• Changing public documentation in ways that create new stability guarantees
• Changing observable runtime behavior of library APIs

[rust-highfive]

r? @thomcc

(rust-highfive has picked a reviewer for you, use r? to override)

[thomcc]

r? rust-lang/libs-api @rustbot label +T-libs-api -T-libs

[dtolnay]

This seems okay to me. Needs documentation and a tracking issue; I assume that's why the PR is still marked Draft.

[devnexen]

Not only that but waited to see if the idea itself would get traction. ok will do these.

[JohnCSimon]

ping from triage:
@devnexen
Can you post the status of this PR?

FYI: when a PR is ready for review, send a message containing
@rustbot ready to switch to S-waiting-on-review so the PR is in the reviewer's backlog.

[devnexen]

@rustbot ready

[dtolnay]

It's not clear to me what useful information "and is only a setter" is meant to convey here. Can this sentence be just the following?—

Set the id of the socket for network filtering purposes.

[dtolnay]

It's odd to see expect here in a function that returns io::Result anyway. How about returning the error?

Suggested change

	/// fn main() -> std::io::Result<()> {
	/// let sock = UnixDatagram::unbound()?;
	/// sock.set_mark(32 as u32).expect("set_mark function failed");
	/// fn main() -> std::io::Result<()> {
	/// let sock = UnixDatagram::unbound()?;
	/// sock.set_mark(32 as u32)?;

[dtolnay]

Thanks for opening the tracking issue. You need to put the issue number here inside the issue attribute. Check out the other unstable attributes in this file.

Same applies to the other new unstable attribute below.

[dtolnay]

32 as u32 is redundant. This can just be sock.set_mark(32) and the integer will be of type u32 automatically.

[dtolnay]

The signature is identical across all of these platforms, and the implementation is nearly identical. How about deduplicating it this way?—

pub fn set_mark(&self, mark: u32) -> io::Result<()> {
    #[cfg(target_os = "linux")]
    let option = libc::SO_MARK;
    #[cfg(target_os = "linux")]
    let option = libc::SO_USER_COOKIE;
    #[cfg(target_os = "linux")]
    let option = libc::SO_RTABLE;
    setsockopt(self, libc::SOL_SOCKET, option, mark as libc::c_int)
}

or maybe this:

pub fn set_mark(&self, mark: u32) -> io::Result<()> {
    setsockopt(
        self,
        libc::SOL_SOCKET,
        #[cfg(target_os = "linux")]
        libc::SO_MARK,
        #[cfg(target_os = "freebsd")]
        libc::SO_USER_COOKIE,
        #[cfg(target_os = "openbsd")]
        libc::SO_RTABLE,
        mark as libc::c_int,
    )
}

[JohnCSimon]

@devnexen devnexen requested a review from dtolnay last month

Triage:
@devnexen I'm assuming you meant for this to be ready for review

FYI: when a PR is ready for review, send a message containing
@rustbot ready to switch to S-waiting-on-review so the PR is in the reviewer's backlog.

@rustbot ready

[dtolnay]

Thanks!

[dtolnay]

@bors r+

[bors]

📌 Commit f6efb0b has been approved by dtolnay

It is now in the queue for this repository.