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Auto merge of #85379 - mdaverde:uds-abstract, r=joshtriplett 

Add abstract namespace support for Unix domain sockets

Hello! The other day I wanted to mess around with UDS in Rust and found that abstract namespaces ([unix(7)](https://man7.org/linux/man-pages/man7/unix.7.html)) 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

```rust
#![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](https://github.com/nix-rust/nix/blob/master/src/sys/socket/addr.rs#L558) crate but there are also other [historical](c4db0685b1) [attempts](https://github.com/tormol/uds/blob/master/src/addr.rs#L324) 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!
This commit is contained in:
bors 2021-10-15 22:31:53 +00:00
parent c1026539bd 15b119897c
commit 6cc0a764e0
5 changed files with 416 additions and 4 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

88
library/std/src/os/unix/net/addr.rs
View File

@ -92,8 +92,8 @@ impl<'a> fmt::Display for AsciiEscaped<'a> {
#[derive(Clone)]
#[stable(feature = "unix_socket", since = "1.10.0")]
pub struct SocketAddr {
addr: libc::sockaddr_un,
len: libc::socklen_t,
pub(super) addr: libc::sockaddr_un,
pub(super) len: libc::socklen_t,
}
impl SocketAddr {
@ -198,6 +198,31 @@ impl SocketAddr {
if let AddressKind::Pathname(path) = self.address() { Some(path) } else { None }
}
/// Returns the contents of this address if it is an abstract namespace
/// without the leading null byte.
///
/// # Examples
///
/// ```no_run
/// #![feature(unix_socket_abstract)]
/// use std::os::unix::net::{UnixListener, SocketAddr};
///
/// fn main() -> std::io::Result<()> {
/// let namespace = b"hidden";
/// let namespace_addr = SocketAddr::from_abstract_namespace(&namespace[..])?;
/// let socket = UnixListener::bind_addr(&namespace_addr)?;
/// let local_addr = socket.local_addr().expect("Couldn't get local address");
/// assert_eq!(local_addr.as_abstract_namespace(), Some(&namespace[..]));
/// Ok(())
/// }
/// ```
#[doc(cfg(any(target_os = "android", target_os = "linux")))]
#[cfg(any(doc, target_os = "android", target_os = "linux",))]
#[unstable(feature = "unix_socket_abstract", issue = "85410")]
pub fn as_abstract_namespace(&self) -> Option<&[u8]> {
if let AddressKind::Abstract(name) = self.address() { Some(name) } else { None }
}
fn address(&self) -> AddressKind<'_> {
let len = self.len as usize - sun_path_offset(&self.addr);
let path = unsafe { mem::transmute::<&[libc::c_char], &[u8]>(&self.addr.sun_path) };
@ -214,6 +239,65 @@ impl SocketAddr {
AddressKind::Pathname(OsStr::from_bytes(&path[..len - 1]).as_ref())
}
}
/// Creates an abstract domain socket address from a namespace
///
/// An abstract address does not create a file unlike traditional path-based
/// Unix sockets. The advantage of this is that the address will disappear when
/// the socket bound to it is closed, so no filesystem clean up is required.
///
/// The leading null byte for the abstract namespace is automatically added.
///
/// This is a Linux-specific extension. See more at [`unix(7)`].
///
/// [`unix(7)`]: https://man7.org/linux/man-pages/man7/unix.7.html
///
/// # Errors
///
/// This will return an error if the given namespace is too long
///
/// # Examples
///
/// ```no_run
/// #![feature(unix_socket_abstract)]
/// use std::os::unix::net::{UnixListener, SocketAddr};
///
/// fn main() -> std::io::Result<()> {
/// let addr = SocketAddr::from_abstract_namespace(b"hidden")?;
/// let listener = match UnixListener::bind_addr(&addr) {
/// Ok(sock) => sock,
/// Err(err) => {
/// println!("Couldn't bind: {:?}", err);
/// return Err(err);
/// }
/// };
/// Ok(())
/// }
/// ```
#[doc(cfg(any(target_os = "android", target_os = "linux")))]
#[cfg(any(doc, target_os = "android", target_os = "linux",))]
#[unstable(feature = "unix_socket_abstract", issue = "85410")]
pub fn from_abstract_namespace(namespace: &[u8]) -> io::Result<SocketAddr> {
unsafe {
let mut addr: libc::sockaddr_un = mem::zeroed();
addr.sun_family = libc::AF_UNIX as libc::sa_family_t;
if namespace.len() + 1 > addr.sun_path.len() {
return Err(io::Error::new_const(
io::ErrorKind::InvalidInput,
&"namespace must be shorter than SUN_LEN",
));
}
crate::ptr::copy_nonoverlapping(
namespace.as_ptr(),
addr.sun_path.as_mut_ptr().offset(1) as *mut u8,
namespace.len(),
);
let len = (sun_path_offset(&addr) + 1 + namespace.len()) as libc::socklen_t;
SocketAddr::from_parts(addr, len)
}
}
}
#[stable(feature = "unix_socket", since = "1.10.0")]

108
library/std/src/os/unix/net/datagram.rs
View File

@ -112,6 +112,41 @@ impl UnixDatagram {
}
}
/// Creates a Unix datagram socket bound to an address.
///
/// # Examples
///
/// ```no_run
/// #![feature(unix_socket_abstract)]
/// use std::os::unix::net::{UnixDatagram};
///
/// fn main() -> std::io::Result<()> {
/// let sock1 = UnixDatagram::bind("path/to/socket")?;
/// let addr = sock1.local_addr()?;
///
/// let sock2 = match UnixDatagram::bind_addr(&addr) {
/// Ok(sock) => sock,
/// Err(err) => {
/// println!("Couldn't bind: {:?}", err);
/// return Err(err);
/// }
/// };
/// Ok(())
/// }
/// ```
#[unstable(feature = "unix_socket_abstract", issue = "85410")]
pub fn bind_addr(socket_addr: &SocketAddr) -> io::Result<UnixDatagram> {
unsafe {
let socket = UnixDatagram::unbound()?;
cvt(libc::bind(
socket.as_raw_fd(),
&socket_addr.addr as *const _ as *const _,
socket_addr.len as _,
))?;
Ok(socket)
}
}
/// Creates a Unix Datagram socket which is not bound to any address.
///
/// # Examples
@ -156,7 +191,7 @@ impl UnixDatagram {
Ok((UnixDatagram(i1), UnixDatagram(i2)))
}
/// Connects the socket to the specified address.
/// Connects the socket to the specified path address.
///
/// The [`send`] method may be used to send data to the specified address.
/// [`recv`] and [`recv_from`] will only receive data from that address.
@ -192,6 +227,41 @@ impl UnixDatagram {
Ok(())
}
/// Connects the socket to an address.
///
/// # Examples
///
/// ```no_run
/// #![feature(unix_socket_abstract)]
/// use std::os::unix::net::{UnixDatagram};
///
/// fn main() -> std::io::Result<()> {
/// let bound = UnixDatagram::bind("/path/to/socket")?;
/// let addr = bound.local_addr()?;
///
/// let sock = UnixDatagram::unbound()?;
/// match sock.connect_addr(&addr) {
/// Ok(sock) => sock,
/// Err(e) => {
/// println!("Couldn't connect: {:?}", e);
/// return Err(e)
/// }
/// };
/// Ok(())
/// }
/// ```
#[unstable(feature = "unix_socket_abstract", issue = "85410")]
pub fn connect_addr(&self, socket_addr: &SocketAddr) -> io::Result<()> {
unsafe {
cvt(libc::connect(
self.as_raw_fd(),
&socket_addr.addr as *const _ as *const _,
socket_addr.len,
))?;
}
Ok(())
}
/// Creates a new independently owned handle to the underlying socket.
///
/// The returned `UnixDatagram` is a reference to the same socket that this
@ -473,6 +543,42 @@ impl UnixDatagram {
}
}
/// Sends data on the socket to the specified [SocketAddr].
///
/// On success, returns the number of bytes written.
///
/// [SocketAddr]: crate::os::unix::net::SocketAddr
///
/// # Examples
///
/// ```no_run
/// #![feature(unix_socket_abstract)]
/// use std::os::unix::net::{UnixDatagram};
///
/// fn main() -> std::io::Result<()> {
/// let bound = UnixDatagram::bind("/path/to/socket")?;
/// let addr = bound.local_addr()?;
///
/// let sock = UnixDatagram::unbound()?;
/// sock.send_to_addr(b"bacon egg and cheese", &addr).expect("send_to_addr function failed");
/// Ok(())
/// }
/// ```
#[unstable(feature = "unix_socket_abstract", issue = "85410")]
pub fn send_to_addr(&self, buf: &[u8], socket_addr: &SocketAddr) -> io::Result<usize> {
unsafe {
let count = cvt(libc::sendto(
self.as_raw_fd(),
buf.as_ptr() as *const _,
buf.len(),
MSG_NOSIGNAL,
&socket_addr.addr as *const _ as *const _,
socket_addr.len,
))?;
Ok(count as usize)
}
}
/// Sends data on the socket to the socket's peer.
///
/// The peer address may be set by the `connect` method, and this method

38
library/std/src/os/unix/net/listener.rs
View File

@ -81,6 +81,44 @@ impl UnixListener {
}
}
/// Creates a new `UnixListener` bound to the specified [`socket address`].
///
/// [`socket address`]: crate::os::unix::net::SocketAddr
///
/// # Examples
///
/// ```no_run
/// #![feature(unix_socket_abstract)]
/// use std::os::unix::net::{UnixListener};
///
/// fn main() -> std::io::Result<()> {
/// let listener1 = UnixListener::bind("path/to/socket")?;
/// let addr = listener1.local_addr()?;
///
/// let listener2 = match UnixListener::bind_addr(&addr) {
/// Ok(sock) => sock,
/// Err(err) => {
/// println!("Couldn't bind: {:?}", err);
/// return Err(err);
/// }
/// };
/// Ok(())
/// }
/// ```
#[unstable(feature = "unix_socket_abstract", issue = "85410")]
pub fn bind_addr(socket_addr: &SocketAddr) -> io::Result<UnixListener> {
unsafe {
let inner = Socket::new_raw(libc::AF_UNIX, libc::SOCK_STREAM)?;
cvt(libc::bind(
inner.as_raw_fd(),
&socket_addr.addr as *const _ as *const _,
socket_addr.len as _,
))?;
cvt(libc::listen(inner.as_raw_fd(), 128))?;
Ok(UnixListener(inner))
}
}
/// Accepts a new incoming connection to this listener.
///
/// This function will block the calling thread until a new Unix connection

37
library/std/src/os/unix/net/stream.rs
View File

@ -106,6 +106,43 @@ impl UnixStream {
}
}
/// Connects to the socket specified by [`address`].
///
/// [`address`]: crate::os::unix::net::SocketAddr
///
/// # Examples
///
/// ```no_run
/// #![feature(unix_socket_abstract)]
/// use std::os::unix::net::{UnixListener, UnixStream};
///
/// fn main() -> std::io::Result<()> {
/// let listener = UnixListener::bind("/path/to/the/socket")?;
/// let addr = listener.local_addr()?;
///
/// let sock = match UnixStream::connect_addr(&addr) {
/// Ok(sock) => sock,
/// Err(e) => {
/// println!("Couldn't connect: {:?}", e);
/// return Err(e)
/// }
/// };
/// Ok(())
/// }
/// ````
#[unstable(feature = "unix_socket_abstract", issue = "85410")]
pub fn connect_addr(socket_addr: &SocketAddr) -> io::Result<UnixStream> {
unsafe {
let inner = Socket::new_raw(libc::AF_UNIX, libc::SOCK_STREAM)?;
cvt(libc::connect(
inner.as_raw_fd(),
&socket_addr.addr as *const _ as *const _,
socket_addr.len,
))?;
Ok(UnixStream(inner))
}
}
/// Creates an unnamed pair of connected sockets.
///
/// Returns two `UnixStream`s which are connected to each other.

149
library/std/src/os/unix/net/tests.rs
View File

@ -303,6 +303,30 @@ fn test_unnamed_unix_datagram() {
assert_eq!(msg, &buf[..]);
}
#[test]
fn test_unix_datagram_connect_to_recv_addr() {
let dir = tmpdir();
let path1 = dir.path().join("sock1");
let path2 = dir.path().join("sock2");
let sock1 = or_panic!(UnixDatagram::bind(&path1));
let sock2 = or_panic!(UnixDatagram::bind(&path2));
let msg = b"hello world";
let sock1_addr = or_panic!(sock1.local_addr());
or_panic!(sock2.send_to_addr(msg, &sock1_addr));
let mut buf = [0; 11];
let (_, addr) = or_panic!(sock1.recv_from(&mut buf));
let new_msg = b"hello back";
let mut new_buf = [0; 10];
or_panic!(sock2.connect_addr(&addr));
or_panic!(sock2.send(new_msg)); // set by connect_addr
let usize = or_panic!(sock2.recv(&mut new_buf));
assert_eq!(usize, 10);
assert_eq!(new_msg, &new_buf[..]);
}
#[test]
fn test_connect_unix_datagram() {
let dir = tmpdir();
@ -388,10 +412,133 @@ fn test_unix_datagram_timeout_zero_duration() {
}
#[test]
fn abstract_namespace_not_allowed() {
fn abstract_namespace_not_allowed_connect() {
assert!(UnixStream::connect("\0asdf").is_err());
}
#[cfg(any(target_os = "android", target_os = "linux"))]
#[test]
fn test_abstract_stream_connect() {
let msg1 = b"hello";
let msg2 = b"world";
let socket_addr = or_panic!(SocketAddr::from_abstract_namespace(b"namespace"));
let listener = or_panic!(UnixListener::bind_addr(&socket_addr));
let thread = thread::spawn(move || {
let mut stream = or_panic!(listener.accept()).0;
let mut buf = [0; 5];
or_panic!(stream.read(&mut buf));
assert_eq!(&msg1[..], &buf[..]);
or_panic!(stream.write_all(msg2));
});
let mut stream = or_panic!(UnixStream::connect_addr(&socket_addr));
let peer = or_panic!(stream.peer_addr());
assert_eq!(peer.as_abstract_namespace().unwrap(), b"namespace");
or_panic!(stream.write_all(msg1));
let mut buf = vec![];
or_panic!(stream.read_to_end(&mut buf));
assert_eq!(&msg2[..], &buf[..]);
drop(stream);
thread.join().unwrap();
}
#[cfg(any(target_os = "android", target_os = "linux"))]
#[test]
fn test_abstract_stream_iter() {
let addr = or_panic!(SocketAddr::from_abstract_namespace(b"hidden"));
let listener = or_panic!(UnixListener::bind_addr(&addr));
let thread = thread::spawn(move || {
for stream in listener.incoming().take(2) {
let mut stream = or_panic!(stream);
let mut buf = [0];
or_panic!(stream.read(&mut buf));
}
});
for _ in 0..2 {
let mut stream = or_panic!(UnixStream::connect_addr(&addr));
or_panic!(stream.write_all(&[0]));
}
thread.join().unwrap();
}
#[cfg(any(target_os = "android", target_os = "linux"))]
#[test]
fn test_abstract_datagram_bind_send_to_addr() {
let addr1 = or_panic!(SocketAddr::from_abstract_namespace(b"ns1"));
let sock1 = or_panic!(UnixDatagram::bind_addr(&addr1));
let local = or_panic!(sock1.local_addr());
assert_eq!(local.as_abstract_namespace().unwrap(), b"ns1");
let addr2 = or_panic!(SocketAddr::from_abstract_namespace(b"ns2"));
let sock2 = or_panic!(UnixDatagram::bind_addr(&addr2));
let msg = b"hello world";
or_panic!(sock1.send_to_addr(msg, &addr2));
let mut buf = [0; 11];
let (len, addr) = or_panic!(sock2.recv_from(&mut buf));
assert_eq!(msg, &buf[..]);
assert_eq!(len, 11);
assert_eq!(addr.as_abstract_namespace().unwrap(), b"ns1");
}
#[cfg(any(target_os = "android", target_os = "linux"))]
#[test]
fn test_abstract_datagram_connect_addr() {
let addr1 = or_panic!(SocketAddr::from_abstract_namespace(b"ns3"));
let bsock1 = or_panic!(UnixDatagram::bind_addr(&addr1));
let sock = or_panic!(UnixDatagram::unbound());
or_panic!(sock.connect_addr(&addr1));
let msg = b"hello world";
or_panic!(sock.send(msg));
let mut buf = [0; 11];
let (len, addr) = or_panic!(bsock1.recv_from(&mut buf));
assert_eq!(len, 11);
assert_eq!(addr.is_unnamed(), true);
assert_eq!(msg, &buf[..]);
let addr2 = or_panic!(SocketAddr::from_abstract_namespace(b"ns4"));
let bsock2 = or_panic!(UnixDatagram::bind_addr(&addr2));
or_panic!(sock.connect_addr(&addr2));
or_panic!(sock.send(msg));
or_panic!(bsock2.recv_from(&mut buf));
}
#[cfg(any(target_os = "android", target_os = "linux"))]
#[test]
fn test_abstract_namespace_too_long() {
match SocketAddr::from_abstract_namespace(
b"abcdefghijklmnopqrstuvwxyzabcdefghijklmn\
opqrstuvwxyzabcdefghijklmnopqrstuvwxyzabcdefghi\
jklmnopqrstuvwxyzabcdefghijklmnopqrstuvwxyz",
) {
Err(ref e) if e.kind() == io::ErrorKind::InvalidInput => {}
Err(e) => panic!("unexpected error {}", e),
Ok(_) => panic!("unexpected success"),
}
}
#[cfg(any(target_os = "android", target_os = "linux"))]
#[test]
fn test_abstract_namespace_no_pathname_and_not_unnamed() {
let namespace = b"local";
let addr = or_panic!(SocketAddr::from_abstract_namespace(&namespace[..]));
assert_eq!(addr.as_pathname(), None);
assert_eq!(addr.as_abstract_namespace(), Some(&namespace[..]));
assert_eq!(addr.is_unnamed(), false);
}
#[test]
fn test_unix_stream_peek() {
let (txdone, rxdone) = crate::sync::mpsc::channel();