[iOS] Fix L2CAP crash issue.

PiperOrigin-RevId: 765077236

internal/platform/implementation/apple/ble_l2cap_server_socket.h

@@ -30,7 +30,7 @@ class BleL2capServerSocket : public api::ble_v2::BleL2capServerSocket {
 
   // Gets PSM value has been published by the server.
   int GetPSM() const override;
-  
+
   // Sets PSM value has been published by the server.
   void SetPSM(int psm);
 
@@ -52,6 +52,12 @@ class BleL2capServerSocket : public api::ble_v2::BleL2capServerSocket {
   // Adds a pending socket to the server socket.
   bool AddPendingSocket(std::unique_ptr<BleL2capSocket> socket);
 
+  // Called by the server side of a connection before accessing the server
+  // socket pointer at the callback of l2cap channel creation, to track validity
+  // of a pointer to this server socket.
+  void SetCloseNotifier(absl::AnyInvocable<void()> notifier)
+      ABSL_LOCKS_EXCLUDED(mutex_);
+
  private:
   Exception DoClose() ABSL_EXCLUSIVE_LOCKS_REQUIRED(mutex_);
 

internal/platform/implementation/apple/ble_l2cap_server_socket.mm

@@ -57,6 +57,11 @@ bool BleL2capServerSocket::AddPendingSocket(std::unique_ptr<BleL2capSocket> sock
   return !closed_;
 }
 
+void BleL2capServerSocket::SetCloseNotifier(absl::AnyInvocable<void()> notifier) {
+  absl::MutexLock lock(&mutex_);
+  close_notifier_ = std::move(notifier);
+}
+
 Exception BleL2capServerSocket::Close() {
   absl::MutexLock lock(&mutex_);
   return DoClose();

internal/platform/implementation/apple/ble_medium.h

@@ -29,7 +29,7 @@
 #include "internal/platform/implementation/ble_v2.h"
 #include "internal/platform/implementation/bluetooth_adapter.h"
 #include "internal/platform/uuid.h"
-
+#import "internal/platform/implementation/apple/ble_l2cap_server_socket.h"
 #import "internal/platform/implementation/apple/ble_server_socket.h"
 #import "internal/platform/implementation/apple/bluetooth_adapter_v2.h"
 
@@ -219,6 +219,9 @@ class BleMedium : public api::ble_v2::BleMedium {
   // Used for the async version of StartAdvertising and has both an advertisement found and result
   // callback.
   api::ble_v2::BleMedium::ScanningCallback scanning_cb_;
+
+  absl::Mutex l2cap_server_socket_mutex_;
+  BleL2capServerSocket *l2cap_server_socket_ptr_ = nullptr;
 };
 
 }  // namespace apple

internal/platform/implementation/apple/ble_medium.mm

@@ -423,7 +423,14 @@ std::unique_ptr<api::ble_v2::BleL2capServerSocket> BleMedium::OpenL2capServerSoc
   dispatch_semaphore_t semaphore = dispatch_semaphore_create(0);
   __block NSError *blockPSMPublishedError = nil;
   auto l2cap_server_socket = std::make_unique<BleL2capServerSocket>();
-  __block auto l2cap_server_socket_ptr = l2cap_server_socket.get();
+  l2cap_server_socket->SetCloseNotifier([this]() {
+    absl::MutexLock lock(&l2cap_server_socket_mutex_);
+    l2cap_server_socket_ptr_ = nullptr;
+  });
+  {
+    absl::MutexLock lock(&l2cap_server_socket_mutex_);
+    l2cap_server_socket_ptr_ = l2cap_server_socket.get();
+  }
   std::string service_id_str = service_id;
   [medium_
       openL2CAPServerWithPSMPublishedCompletionHandler:^(uint16_t PSM, NSError *_Nullable error) {
@@ -432,7 +439,12 @@ std::unique_ptr<api::ble_v2::BleL2capServerSocket> BleMedium::OpenL2capServerSoc
           dispatch_semaphore_signal(semaphore);
           return;
         }
-        l2cap_server_socket_ptr->SetPSM(PSM);
+        {
+          absl::MutexLock lock(&l2cap_server_socket_mutex_);
+          if (l2cap_server_socket_ptr_) {
+            l2cap_server_socket_ptr_->SetPSM(PSM);
+          }
+        }
         dispatch_semaphore_signal(semaphore);
       }
       channelOpenedCompletionHandler:^(GNCBLEL2CAPStream *_Nullable stream,
@@ -447,8 +459,11 @@ std::unique_ptr<api::ble_v2::BleL2capServerSocket> BleMedium::OpenL2capServerSoc
                                      incomingConnection:YES
                                           callbackQueue:dispatch_get_main_queue()];
         auto socket = std::make_unique<BleL2capSocket>(connection);
-        if (l2cap_server_socket_ptr) {
-          l2cap_server_socket_ptr->AddPendingSocket(std::move(socket));
+        {
+          absl::MutexLock lock(&l2cap_server_socket_mutex_);
+          if (l2cap_server_socket_ptr_) {
+            l2cap_server_socket_ptr_->AddPendingSocket(std::move(socket));
+          }
         }
       }
       peripheralManager:nil];