🚑️ Fix a few recent regressions

zbus/src/connection/handshake/client.rs

@@ -95,21 +95,16 @@ impl Client {
     #[instrument(skip(self))]
     #[cfg(any(target_os = "freebsd", target_os = "dragonfly"))]
     async fn send_zero_byte(&mut self) -> Result<()> {
-        let written = self
-            .common
-            .socket_mut()
-            .write_mut()
-            .send_zero_byte()
-            .await
-            .map_err(|e| {
-                Error::Handshake(format!("Could not send zero byte with credentials: {}", e))
-            })
-            .and_then(|n| match n {
-                None => Err(Error::Handshake(
-                    "Could not send zero byte with credentials".to_string(),
-                )),
-                Some(n) => Ok(n),
-            })?;
+        let write = self.common.socket_mut().write_mut();
+
+        let written = match write.send_zero_byte().await.map_err(|e| {
+            Error::Handshake(format!("Could not send zero byte with credentials: {}", e))
+        })? {
+            // This likely means that the socket type is unable to send SCM_CREDS.
+            // Let's try to send the 0 byte as a regular message.
+            None => write.sendmsg(&[0], &[]).await?,
+            Some(n) => n,
+        };
 
         if written != 1 {
             return Err(Error::Handshake(

zbus/src/connection/handshake/common.rs

@@ -122,17 +122,13 @@ impl Common {
                 if self.first_command {
                     // The first command is sent by the client so we can assume it's the server.
                     self.first_command = false;
-                    // leading 0 is sent separately for `freebsd` and `dragonfly`.
-                    #[cfg(not(any(target_os = "freebsd", target_os = "dragonfly")))]
-                    {
-                        if self.recv_buffer[0] != b'\0' {
-                            return Err(Error::Handshake(
-                                "First client byte is not NUL!".to_string(),
-                            ));
-                        }
-
-                        start_index = 1;
+                    if self.recv_buffer[0] != b'\0' {
+                        return Err(Error::Handshake(
+                            "First client byte is not NUL!".to_string(),
+                        ));
                     }
+
+                    start_index = 1;
                 };
 
                 let line_bytes = self.recv_buffer.drain(..=lf_index);

zbus/src/connection/socket/tcp.rs

@@ -26,32 +26,25 @@ impl ReadHalf for Arc<Async<TcpStream>> {
         }
     }
 
+    #[cfg(windows)]
     async fn peer_credentials(&mut self) -> io::Result<crate::fdo::ConnectionCredentials> {
-        #[cfg(windows)]
-        let creds = {
-            let stream = self.clone();
-            crate::Task::spawn_blocking(
-                move || {
-                    use crate::win32::{tcp_stream_get_peer_pid, ProcessToken};
-
-                    let pid = tcp_stream_get_peer_pid(stream.get_ref())? as _;
-                    let sid = ProcessToken::open(if pid != 0 { Some(pid as _) } else { None })
-                        .and_then(|process_token| process_token.sid())?;
-                    io::Result::Ok(
-                        crate::fdo::ConnectionCredentials::default()
-                            .set_process_id(pid)
-                            .set_windows_sid(sid),
-                    )
-                },
-                "peer credentials",
-            )
-            .await
-        }?;
-
-        #[cfg(not(windows))]
-        let creds = crate::fdo::ConnectionCredentials::default();
-
-        Ok(creds)
+        let stream = self.clone();
+        crate::Task::spawn_blocking(
+            move || {
+                use crate::win32::{tcp_stream_get_peer_pid, ProcessToken};
+
+                let pid = tcp_stream_get_peer_pid(stream.get_ref())? as _;
+                let sid = ProcessToken::open(if pid != 0 { Some(pid as _) } else { None })
+                    .and_then(|process_token| process_token.sid())?;
+                io::Result::Ok(
+                    crate::fdo::ConnectionCredentials::default()
+                        .set_process_id(pid)
+                        .set_windows_sid(sid),
+                )
+            },
+            "peer credentials",
+        )
+        .await
     }
 }