Add abstract namespace support for Unix domain sockets

[mdaverde]

Hello! The other day I wanted to mess around with UDS in Rust and found that abstract namespaces (unix(7)) on Linux still needed development. I took the approach of adding _addr specific public functions to reduce conflicts.

Feature name: unix_socket_abstract
Tracking issue: #85410
Further context: #42048

Non-platform specific additions

UnixListener::bind_addr(&SocketAddr) -> Result<UnixListener>

UnixStream::connect_addr(&SocketAddr) -> Result<()>

UnixDatagram::bind_addr(&SocketAddr) -> Result<UnixDatagram>

UnixDatagram::connect_addr(&SocketAddr) -> Result<()>

UnixDatagram::send_to_addr(&self, &[u8], &SocketAddr) -> Result<usize>

Platform-specific (Linux) additions

SocketAddr::from_abstract_namespace(&[u8]) -> SocketAddr

SockerAddr::as_abstract_namespace() -> Option<&[u8]>

Example

#![feature(unix_socket_abstract)]
use std::os::unix::net::{UnixListener, SocketAddr};

fn main() -> std::io::Result<()> {
    let addr = SocketAddr::from_abstract_namespace(b"namespace")?; // Linux only
    let listener = match UnixListener::bind_addr(&addr) {
        Ok(sock) => sock,
        Err(err) => {
            println!("Couldn't bind: {:?}", err);
            return Err(err);
        }
    };
    Ok(())
}

Further Details

The main inspiration for the implementation came from the nix-rust crate but there are also other historical attempts with similar approaches.

A comment I did have was with this change, we now allow a SocketAddr to be constructed explicitly rather than just used almost as a handle for the return of peer_addr and local_addr. We could consider adding other explicit constructors (e.g. SocketAddr::from_pathname, SockerAddr::from_unnamed).

Cheers!

[rust-highfive]

Thanks for the pull request, and welcome! The Rust team is excited to review your changes, and you should hear from @kennytm (or someone else) soon.

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[joshtriplett]

This looks reasonable to me!

You need to create a tracking issue, and change the issue number in the stability attributes to reference that tracking issue.

With that fixed, if CI passes and a try build passes, r=me.

[mdaverde]

Updated the stability attributes to a new tracking issue! Although, I think I need maintainer approval to rerun the build?

[joshtriplett]

@bors try

[bors]

⌛ Trying commit a4d0489 with merge 1c03bdf6c40e17f64fa452dd50a3e41fcd70fb69...

[bors]

☀️ Try build successful - checks-actions
Build commit: 1c03bdf6c40e17f64fa452dd50a3e41fcd70fb69 (1c03bdf6c40e17f64fa452dd50a3e41fcd70fb69)

[joshtriplett]

@bors r+

[bors]

📌 Commit a4d0489 has been approved by joshtriplett

[GuillaumeGomez]

Failed in CI:

[RUSTC-TIMING] object test:false 10.149
error: unused import: `ptr`
 --> library/std/src/os/./unix/net/addr.rs:5:40
  |
5 | use crate::{ascii, fmt, io, iter, mem, ptr};
  |
  |
  = note: `-D unused-imports` implied by `-D warnings`
error: aborting due to previous error

[RUSTC-TIMING] std test:false 2.398
error: could not compile `std`

@bors: r-

[mdaverde]

Hmm is that an allowable import? I believe I am using it on line :288 of /unix/net/addr.rs but maybe something changed:

            ptr::copy_nonoverlapping(
                namespace.as_ptr(),
                addr.sun_path.as_mut_ptr().offset(1) as *mut u8,
                namespace.len(),
            );

[GuillaumeGomez]

Is it behind a cfg by any chance? Worst case, simply replace ptr with std::ptr and you're good to go. :)

[mdaverde]

Ah yes, that was it. Went ahead and moved the use declaration within the fn block. Thank you!

[GuillaumeGomez]

@bors: r=joshtriplett,GuillaumeGomez

[bors]

📌 Commit b0b0267 has been approved by joshtriplett,GuillaumeGomez

[bors]

⌛ Testing commit 3b441c8 with merge 1aa771d03efaa4bcb086adbf0e9e38fb98a6f428...

[bors]

💔 Test failed - checks-actions

[mdaverde]

Integrated the I/O safety changes and did a rebase 🙏

r? @joshtriplett

[joshtriplett]

@bors r+

[bors]

📌 Commit 15b1198 has been approved by joshtriplett

[bors]

⌛ Testing commit 15b1198 with merge 6cc0a76...

[bors]

☀️ Test successful - checks-actions
Approved by: joshtriplett
Pushing 6cc0a76 to master...

[rust-timer]

Finished benchmarking commit (6cc0a76): comparison url.

Summary: This benchmark run did not return any relevant changes.

If you disagree with this performance assessment, please file an issue in rust-lang/rustc-perf.

@rustbot label: -perf-regression