fix

Tun/Punchnet/Context/SDLPacketReaderService.swift

@@ -7,6 +7,7 @@ actor SDLPacketReaderService {
     }
 
     typealias EventHandler = @Sendable (Event) async -> Void
+    private typealias PacketReadResult = (packets: [Data], protocols: [NSNumber])?
 
     private final class CancellationToken: @unchecked Sendable {
         private let lock = NSLock()
@@ -27,45 +28,6 @@ actor SDLPacketReaderService {
         }
     }
 
-    private final class PacketReadContinuation: @unchecked Sendable {
-        typealias Result = (packets: [Data], protocols: [NSNumber])?
-
-        private let lock = NSLock()
-        private var continuation: CheckedContinuation<Result, Never>?
-        private var finished: Bool = false
-
-        func set(_ continuation: CheckedContinuation<Result, Never>) {
-            lock.lock()
-            if finished {
-                lock.unlock()
-                continuation.resume(returning: nil)
-                return
-            }
-
-            self.continuation = continuation
-            lock.unlock()
-        }
-
-        func resume(returning result: Result) {
-            lock.lock()
-            guard !finished else {
-                lock.unlock()
-                return
-            }
-
-            finished = true
-            let continuation = self.continuation
-            self.continuation = nil
-            lock.unlock()
-
-            continuation?.resume(returning: result)
-        }
-
-        func cancel() {
-            resume(returning: nil)
-        }
-    }
-
     private let provider: NEPacketTunnelProvider
     private let onEvent: EventHandler
     private var readTask: Task<Void, Never>?
@@ -119,8 +81,8 @@ actor SDLPacketReaderService {
         readTask?.cancel()
     }
 
-    private static func readPackets(from provider: NEPacketTunnelProvider) async -> PacketReadContinuation.Result {
-        let readContinuation = PacketReadContinuation()
+    private static func readPackets(from provider: NEPacketTunnelProvider) async -> PacketReadResult {
+        let readContinuation = OnceContinuation<PacketReadResult, Never>()
 
         return await withTaskCancellationHandler {
             await withCheckedContinuation { continuation in
@@ -130,7 +92,7 @@ actor SDLPacketReaderService {
                 }
             }
         } onCancel: {
-            readContinuation.cancel()
+            readContinuation.resume(returning: nil)
         }
     }
 }

Tun/Punchnet/OnceContinuation.swift

@@ -0,0 +1,56 @@
+//
+//  OnceContinuation.swift
+//  Tun
+//
+//  Created by Codex on 2026/5/7.
+//
+
+import Foundation
+
+final class OnceContinuation<Value, Failure: Error>: @unchecked Sendable {
+    private let lock = NSLock()
+    private var continuation: CheckedContinuation<Value, Failure>?
+    private var result: Result<Value, Failure>?
+
+    func set(_ continuation: CheckedContinuation<Value, Failure>) {
+        lock.lock()
+        if let result {
+            lock.unlock()
+            continuation.resume(with: result)
+            return
+        }
+
+        let hasPendingContinuation = self.continuation != nil
+        if !hasPendingContinuation {
+            self.continuation = continuation
+        }
+        lock.unlock()
+
+        if hasPendingContinuation {
+            preconditionFailure("OnceContinuation can only store one pending continuation")
+        }
+    }
+
+    func resume(returning value: Value) {
+        resume(with: .success(value))
+    }
+
+    func resume(throwing error: Failure) {
+        resume(with: .failure(error))
+    }
+
+    func resume(with result: Result<Value, Failure>) {
+        lock.lock()
+        guard self.result == nil else {
+            lock.unlock()
+            return
+        }
+
+        self.result = result
+        let continuation = self.continuation
+        self.continuation = nil
+        lock.unlock()
+
+        continuation?.resume(with: result)
+    }
+}