Implement Oplock Break Acknowledgement handler (MS-SMB2 §2.2.24)

- Parse client's OPLOCK_BREAK_ACK
- Update Open.oplock_level in Open struct
- Update OplockManager entry via update_oplock_level()
- Return confirmation response

All 229 tests pass.

vendor/smb-server/src/handlers/oplock_break.rs

@@ -1,27 +1,57 @@
-//! OPLOCK_BREAK handler — acknowledge breaks without granting oplocks.
+//! OPLOCK_BREAK handler — acknowledge breaks and update oplock state.
 
 use std::sync::Arc;
 
 use crate::proto::header::Smb2Header;
-use crate::proto::messages::FileId;
+use crate::proto::messages::{FileId, OplockBreakAck};
 
 use crate::conn::state::Connection;
 use crate::dispatch::HandlerResponse;
+use crate::handlers::shared::lookup_session_tree;
+use crate::ntstatus;
 use crate::server::ServerState;
 
 pub async fn handle(
-    _server: &Arc<ServerState>,
-    _conn: &Arc<Connection>,
-    _hdr: &Smb2Header,
-    _body: &[u8],
+    server: &Arc<ServerState>,
+    conn: &Arc<Connection>,
+    hdr: &Smb2Header,
+    body: &[u8],
 ) -> HandlerResponse {
-    // Echo back the same shape as the notification — structure_size=24, level=0.
+    // Parse client's ACK (MS-SMB2 §2.2.24)
+    let ack = match OplockBreakAck::parse(body) {
+        Ok(a) => a,
+        Err(_) => return HandlerResponse::err(ntstatus::STATUS_INVALID_PARAMETER),
+    };
+    
+    // Lookup tree to get path for oplock manager
+    let tree_arc = match lookup_session_tree(conn, hdr).await {
+        Ok(t) => t,
+        Err(s) => return HandlerResponse::err(s),
+    };
+    
+    // Update oplock level in the open
+    let path = {
+        // Find the open by file_id
+        let tree = tree_arc.read().await;
+        let opens = tree.opens.read().await;
+        if let Some(open_arc) = opens.get(&ack.file_id) {
+            let mut open = open_arc.write().await;
+            open.oplock_level = ack.oplock_level;
+            open.last_path.clone()
+        } else {
+            return HandlerResponse::err(ntstatus::STATUS_FILE_CLOSED);
+        }
+    };
+    
+    // Update OplockManager entry
+    server.oplock_manager.update_oplock_level(
+        &path,
+        ack.file_id,
+        ack.oplock_level,
+    ).await;
+    
+    // Echo back the ACK as confirmation (MS-SMB2 §2.2.24)
     let mut buf = Vec::new();
-    buf.extend_from_slice(&24u16.to_le_bytes()); // structure_size
-    buf.push(0); // OplockLevel
-    buf.push(0); // Reserved
-    buf.extend_from_slice(&0u32.to_le_bytes()); // Reserved2
-    buf.extend_from_slice(&FileId::any().persistent.to_le_bytes());
-    buf.extend_from_slice(&FileId::any().volatile.to_le_bytes());
+    ack.write_to(&mut buf).expect("encode ack response");
     HandlerResponse::ok(buf)
 }

vendor/smb-server/src/oplock.rs

@@ -191,6 +191,21 @@ pub struct LockRange {
     pub tree_id: u32,
 }
 
+impl OplockManager {
+    /// Update oplock level after client acknowledges a break (MS-SMB2 §2.2.24).
+    pub async fn update_oplock_level(&self, path: &SmbPath, file_id: FileId, new_level: u8) {
+        let mut file_opens = self.file_opens.write().await;
+        if let Some(entries) = file_opens.get_mut(path) {
+            for entry in entries.iter_mut() {
+                if entry.file_id == file_id {
+                    entry.oplock_level = new_level;
+                    break;
+                }
+            }
+        }
+    }
+}
+
 /// Global byte-range lock manager (MS-SMB2 §3.3.1.9).
 pub struct LockManager {
     /// FileId → active locks on that file.