Merge pull request #25 from vi/abstract_zero_byte

Do not add trailing zero byte for abstract paths.

CHANGELOG.md

@@ -1,3 +1,7 @@
+main:
+  * Do not add a trailing null byte to abstract namespace socket paths on Linux and Android in `bind()` and `connect()`.
+  * Do not strip a traling null byte from abstract namespace socket paths on Linux and Android in `local_addr()`.
+
 v0.7.1 - 2023-11-15:
   * Ensure proper alginment of control message buffer in the writer.
   * Fix compilation on Illumos and Solaris platforms.

src/sys.rs

@@ -261,7 +261,13 @@ fn path_to_sockaddr(path: &Path) -> std::io::Result<(libc::sockaddr_un, usize)>
 		core::ptr::copy_nonoverlapping(path.as_ptr(), sockaddr.sun_path.as_mut_ptr() as *mut u8, path.len());
 		sockaddr.sun_path[path.len()] = 0;
 		let path_offset = sockaddr.sun_path.as_ptr() as usize - (&sockaddr as *const _ as usize);
-		Ok((sockaddr, path_offset + path.len() + 1))
+
+		// Do not add trailing zero byte to abstract UNIX socket paths on Linux and Android.
+		if cfg!(any(target_os = "linux", target_os = "android")) && path.first() == Some(&0) {
+			Ok((sockaddr, path_offset + path.len()))
+		} else {
+			Ok((sockaddr, path_offset + path.len() + 1))
+		}
 	}
 }
 
@@ -284,13 +290,13 @@ fn sockaddr_to_path(address: &libc::sockaddr_un, len: libc::socklen_t) -> std::i
 			let offset = sun_path.offset_from(address as *const _ as *const u8);
 			let path = core::slice::from_raw_parts(sun_path, len as usize - offset as usize);
 
-			// Some platforms include a trailing null byte in the path length.
-			let path = if path.last() == Some(&0) {
-				&path[..path.len() - 1]
+			// Do not strip trailing zero byte from abstract UNIX socket paths on Linux and Android.
+			if cfg!(any(target_os = "linux", target_os = "android")) && path.first() == Some(&0) {
+				Ok(Path::new(OsStr::from_bytes(path)))
 			} else {
-				path
-			};
-			Ok(Path::new(OsStr::from_bytes(path)))
+				let path = path.strip_suffix(&[0]).unwrap_or(path);
+				Ok(Path::new(OsStr::from_bytes(path)))
+			}
 		}
 	}
 }

tests/abstract_namespace.rs

@@ -0,0 +1,82 @@
+#![cfg(any(target_os = "linux", target_os = "android"))]
+
+use std::path::PathBuf;
+
+use assert2::{assert, let_assert};
+use tokio_seqpacket::{UnixSeqpacket, UnixSeqpacketListener};
+
+#[track_caller]
+fn random_abstract_name(suffix: &str) -> PathBuf {
+	use std::io::Read;
+	use std::ffi::OsString;
+	use std::os::unix::ffi::OsStringExt;
+
+	let_assert!(Ok(mut urandom) = std::fs::File::open("/dev/urandom"));
+	let mut buffer = Vec::with_capacity(63 + suffix.len());
+	buffer.resize(63, 0);
+	assert!(let Ok(()) = urandom.read_exact(&mut buffer[1..]));
+	for byte in &mut buffer[1..] {
+		let c = *byte % (10 + 26 + 26);
+		if c < 10 {
+			*byte = b'0' + c;
+		} else if c < 10 + 26 {
+			*byte = b'A' + c - 10;
+		} else {
+			*byte = b'a' + c - 10 - 26;
+		}
+	}
+	buffer.extend(suffix.bytes());
+	OsString::from_vec(buffer).into()
+}
+
+/// Create a listening socket with an abstract name, connect to it and exchange a message.
+///
+/// Use an abstract socket path without terminating null byte.
+#[tokio::test]
+async fn address_without_null_byte() {
+	let name = random_abstract_name("\x01");
+	assert!(name.as_os_str().as_encoded_bytes().ends_with(&[1]), "{name:?}");
+
+	let_assert!(Ok(mut listener) = UnixSeqpacketListener::bind(&name));
+	let_assert!(Ok(local_addr) = listener.local_addr());
+	assert!(local_addr == name);
+
+	let (server_socket, client_socket) = tokio::join!(
+		listener.accept(),
+		UnixSeqpacket::connect(name),
+	);
+	let_assert!(Ok(server_socket) = server_socket);
+	let_assert!(Ok(client_socket) = client_socket);
+
+	assert!(let Ok(12) = client_socket.send(b"Hello world!").await);
+
+	let mut buffer = [0u8; 128];
+	assert!(let Ok(12) = server_socket.recv(&mut buffer).await);
+	assert!(&buffer[..12] == b"Hello world!");
+}
+
+/// Create a listening socket with an abstract name, connect to it and exchange a message.
+///
+/// Use an abstract socket path with terminating null byte.
+#[tokio::test]
+async fn address_ending_with_null_byte() {
+	let name = random_abstract_name("\x00");
+	assert!(name.as_os_str().as_encoded_bytes().ends_with(&[0]), "{name:?}");
+
+	let_assert!(Ok(mut listener) = UnixSeqpacketListener::bind(&name));
+	let_assert!(Ok(local_addr) = listener.local_addr());
+	assert!(local_addr == name);
+
+	let (server_socket, client_socket) = tokio::join!(
+		listener.accept(),
+		UnixSeqpacket::connect(name),
+	);
+	let_assert!(Ok(server_socket) = server_socket);
+	let_assert!(Ok(client_socket) = client_socket);
+
+	assert!(let Ok(12) = client_socket.send(b"Hello world!").await);
+
+	let mut buffer = [0u8; 128];
+	assert!(let Ok(12) = server_socket.recv(&mut buffer).await);
+	assert!(&buffer[..12] == b"Hello world!");
+}