Implement L2CAPServer

PiperOrigin-RevId: 733593766

internal/platform/implementation/apple/Mediums/BLEv2/GNCBLEL2CAPServer.h

@@ -0,0 +1,39 @@
+// Copyright 2025 Google LLC
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     https://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+#import <CoreBluetooth/CoreBluetooth.h>
+#import <Foundation/Foundation.h>
+
+NS_ASSUME_NONNULL_BEGIN
+
+/**
+ * An object that publishes the @c PSM value.
+ *
+ * @note The public APIs of this class are thread safe.
+ */
+@interface GNCBLEL2CAPServer : NSObject
+
+// Represents a PSM (Protocol/Service Multiplexer) value for an L2CAP channel.
+@property(atomic, readonly) CBL2CAPPSM PSM;
+
+/**
+ * Retrieves the L2CAP channel.
+ *
+ * @return The L2CAP channel, or nil if the channel is not available.
+ */
+- (nullable CBL2CAPChannel *)getChannel;
+
+@end
+
+NS_ASSUME_NONNULL_END

internal/platform/implementation/apple/Mediums/BLEv2/GNCBLEL2CAPServer.m

@@ -0,0 +1,158 @@
+// Copyright 2025 Google LLC
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     https://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+#import "internal/platform/implementation/apple/Mediums/BLEv2/GNCBLEL2CAPServer.h"
+
+#import <CoreBluetooth/CoreBluetooth.h>
+#import <Foundation/Foundation.h>
+
+#import "internal/platform/implementation/apple/Mediums/BLEv2/GNCBLEError.h"
+#import "internal/platform/implementation/apple/Mediums/BLEv2/GNCPeripheralManager.h"
+#import "GoogleToolboxForMac/GTMLogger.h"
+
+NS_ASSUME_NONNULL_BEGIN
+
+static char *const kGNCBLEL2CAPServerQueueLabel = "com.nearby.GNCBLEL2CAPServer";
+
+@interface GNCBLEL2CAPServer () <GNCPeripheralManagerDelegate>
+@property(atomic, readwrite) CBL2CAPPSM PSM;
+@end
+
+@implementation GNCBLEL2CAPServer {
+  dispatch_queue_t _queue;
+  id<GNCPeripheralManager> _peripheralManager;
+
+  // The L2CAP channel that is used to send and receive data.
+  CBL2CAPChannel *_channel;
+}
+
+- (instancetype)init {
+  self = [super init];
+  if (self) {
+    _queue = dispatch_queue_create(kGNCBLEL2CAPServerQueueLabel, DISPATCH_QUEUE_SERIAL);
+    _peripheralManager = [[CBPeripheralManager alloc] initWithDelegate:nil queue:_queue];
+    // Set for @c GNCPeripheralManager to be able to forward callbacks.
+    _peripheralManager.peripheralDelegate = self;
+  }
+  return self;
+}
+
+// This is private and should only be used for tests. The provided peripheral manager must call
+// delegate methods on the main queue.
+- (instancetype)initWithPeripheralManager:(nullable id<GNCPeripheralManager>)peripheralManager {
+  self = [super init];
+  if (self) {
+    _queue = dispatch_get_main_queue();
+    _peripheralManager = peripheralManager;
+    // Set for @c GNCPeripheralManager to be able to forward callbacks.
+    _peripheralManager.peripheralDelegate = self;
+  }
+  return self;
+}
+
+- (nullable CBL2CAPChannel *)getChannel {
+  return _channel;
+}
+
+#pragma mark - GNCPeripheralManagerDelegate
+
+- (void)gnc_peripheralManagerDidUpdateState:(id<GNCPeripheralManager>)peripheral {
+  dispatch_assert_queue(_queue);
+  if (_peripheralManager.state == CBManagerStatePoweredOn) {
+    [_peripheralManager publishL2CAPChannelWithEncryption:NO];
+  }
+  if (_peripheralManager.state == CBManagerStatePoweredOff) {
+    [_peripheralManager unpublishL2CAPChannel:_PSM];
+  }
+}
+
+- (void)gnc_peripheralManager:(id<GNCPeripheralManager>)peripheral
+       didPublishL2CAPChannel:(CBL2CAPPSM)PSM
+                        error:(nullable NSError *)error {
+  dispatch_assert_queue(_queue);
+  if (error) {
+    GTMLoggerError(@"Failed to publish L2CAP channel: %@", error);
+  }
+  GTMLoggerInfo(@"Published L2CAP channel with PSM: %d", PSM);
+  _PSM = PSM;
+}
+
+- (void)gnc_peripheralManager:(id<GNCPeripheralManager>)peripheral
+     didUnpublishL2CAPChannel:(CBL2CAPPSM)PSM
+                        error:(NSError *)error {
+  dispatch_assert_queue(_queue);
+  if (error) {
+    GTMLoggerError(@"Failed to unpublish L2CAP channel: %@", error);
+  }
+  _PSM = 0;
+}
+
+- (void)gnc_peripheralManager:(id<GNCPeripheralManager>)peripheral
+          didOpenL2CAPChannel:(nullable CBL2CAPChannel *)channel
+                        error:(nullable NSError *)error {
+  dispatch_assert_queue(_queue);
+  if (error) {
+    GTMLoggerError(@"Failed to open L2CAP channel: %@", error);
+    return;
+  }
+  GTMLoggerInfo(@"Opened L2CAP channel with PSM: %d", channel.PSM);
+  _channel = channel;
+  // TODO: b/399815436 - Implement to wrap up l2cap channel.
+}
+
+#pragma mark - CBPeripheralManagerDelegate
+
+- (void)peripheralManagerDidUpdateState:(CBPeripheralManager *)peripheral {
+  dispatch_async(_queue, ^{
+    [self gnc_peripheralManagerDidUpdateState:peripheral];
+  });
+}
+
+- (void)peripheralManager:(CBPeripheralManager *)peripheral
+    didPublishL2CAPChannel:(CBL2CAPPSM)PSM
+                     error:(nullable NSError *)error {
+  dispatch_async(_queue, ^{
+    [self gnc_peripheralManager:peripheral didPublishL2CAPChannel:PSM error:error];
+  });
+}
+
+- (void)peripheralManager:(CBPeripheralManager *)peripheral
+    didUnpublishL2CAPChannel:(CBL2CAPPSM)PSM
+                       error:(nullable NSError *)error {
+  dispatch_async(_queue, ^{
+    [self gnc_peripheralManager:peripheral didUnpublishL2CAPChannel:PSM error:error];
+  });
+}
+
+- (void)peripheralManager:(CBPeripheralManager *)peripheral
+      didOpenL2CAPChannel:(nullable CBL2CAPChannel *)channel
+                    error:(nullable NSError *)error {
+  dispatch_async(_queue, ^{
+    [self gnc_peripheralManager:peripheral didOpenL2CAPChannel:channel error:error];
+  });
+}
+
+#pragma mark Private
+
+- (void)tearDown {
+  if (_PSM > 0) {
+    [_peripheralManager unpublishL2CAPChannel:_PSM];
+  }
+  _peripheralManager.peripheralDelegate = nil;
+  _peripheralManager = nil;
+}
+
+@end
+
+NS_ASSUME_NONNULL_END

internal/platform/implementation/apple/Mediums/BLEv2/GNCPeripheralManager.h

@@ -118,6 +118,20 @@ NS_ASSUME_NONNULL_BEGIN
  */
 - (void)stopAdvertising;
 
+/**
+ * Publishes an L2CAP channel with optional encryption.
+ *
+ * @param encryptionRequired A boolean value indicating whether encryption is required for the L2CAP channel.
+ */
+- (void)publishL2CAPChannelWithEncryption:(BOOL)encryptionRequired;
+
+/**
+ * Unpublishes an L2CAP channel.
+ *
+ * @param PSM The @c PSM (Protocol/Service Multiplexer) value assigned to the published channel.
+ */
+- (void)unpublishL2CAPChannel:(CBL2CAPPSM)PSM;
+
 @end
 
 /**
@@ -156,6 +170,7 @@ NS_ASSUME_NONNULL_BEGIN
  * @param peripheral The peripheral manager that is starting advertising.
  * @param error The reason the call failed, or @c nil if no error occurred.
  */
+@optional
 - (void)gnc_peripheralManagerDidStartAdvertising:(id<GNCPeripheralManager>)peripheral
                                            error:(nullable NSError *)error;
 
@@ -171,6 +186,7 @@ NS_ASSUME_NONNULL_BEGIN
  * @param service The service added to the local GATT database.
  * @param error The reason the call failed, or @c nil if no error occurred.
  */
+@optional
 - (void)gnc_peripheralManager:(id<GNCPeripheralManager>)peripheral
                 didAddService:(CBService *)service
                         error:(nullable NSError *)error;
@@ -186,9 +202,49 @@ NS_ASSUME_NONNULL_BEGIN
  * @param request A @c CBATTRequest object that represents a request to read a characteristic’s
  *                value.
  */
+@optional
 - (void)gnc_peripheralManager:(id<GNCPeripheralManager>)peripheral
         didReceiveReadRequest:(CBATTRequest *)request;
 
+/**
+ * Called when an L2CAP channel has been published by the peripheral.
+ *
+ * @param peripheral The peripheral that published the L2CAP channel.
+ * @param PSM The @c PSM (Protocol/Service Multiplexer) value assigned to the published channel.
+ * @param error An error object indicating why the channel failed to publish, or @c nil if
+ * successful.
+ */
+@optional
+- (void)gnc_peripheralManager:(id<GNCPeripheralManager>)peripheral
+       didPublishL2CAPChannel:(CBL2CAPPSM)PSM
+                        error:(nullable NSError *)error;
+
+/**
+ * Called when an L2CAP channel has been unpublished by the peripheral.
+ *
+ * @param peripheral The peripheral that unpublished the L2CAP channel.
+ * @param PSM The @c PSM (Protocol/Service Multiplexer) value assigned to the unpublished channel.
+ * @param error An error object indicating why the channel failed to unpublish, or @c nil if
+ * successful.
+ */
+@optional
+- (void)gnc_peripheralManager:(id<GNCPeripheralManager>)peripheral
+     didUnpublishL2CAPChannel:(CBL2CAPPSM)PSM
+                        error:(NSError *)error;
+
+/**
+ * Called when an L2CAP channel has been opened by the peripheral.
+ *
+ * @param peripheral The peripheral that opened the L2CAP channel.
+ * @param channel The opened L2CAP channel, or nil if an error occurred.
+ * @param error An error object indicating why the channel failed to
+ * open, or @c nil if successful.
+ */
+@optional
+- (void)gnc_peripheralManager:(id<GNCPeripheralManager>)peripheral
+          didOpenL2CAPChannel:(nullable CBL2CAPChannel *)channel
+                        error:(nullable NSError *)error;
+
 @end
 
 @interface CBPeripheralManager () <GNCPeripheralManager>

internal/platform/implementation/apple/Mediums/BUILD

@@ -25,6 +25,7 @@ objc_library(
         "BLEv2/GNCBLEGATTCharacteristic.m",
         "BLEv2/GNCBLEGATTClient.m",
         "BLEv2/GNCBLEGATTServer.m",
+        "BLEv2/GNCBLEL2CAPServer.m",
         "BLEv2/GNCBLEMedium.m",
         "BLEv2/GNCCentralManager.m",
         "BLEv2/GNCPeripheral.m",
@@ -48,6 +49,7 @@ objc_library(
         "BLEv2/GNCBLEGATTCharacteristic.h",
         "BLEv2/GNCBLEGATTClient.h",
         "BLEv2/GNCBLEGATTServer.h",
+        "BLEv2/GNCBLEL2CAPServer.h",
         "BLEv2/GNCBLEMedium.h",
         "BLEv2/GNCCentralManager.h",
         "BLEv2/GNCPeripheral.h",

internal/platform/implementation/apple/Tests/BUILD

@@ -28,6 +28,8 @@ objc_library(
         "GNCBLEGATTClientTest.m",
         "GNCBLEGATTServer+Testing.h",
         "GNCBLEGATTServerTest.m",
+        "GNCBLEL2CAPServer+Testing.h",
+        "GNCBLEL2CAPServerTest.m",
         "GNCBLEMedium+Testing.h",
         "GNCBLEMediumTest.m",
         "GNCBLEUtilsTest.mm",

internal/platform/implementation/apple/Tests/GNCBLEL2CAPServer+Testing.h

@@ -0,0 +1,36 @@
+// Copyright 2025 Google LLC
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     https://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+#import "internal/platform/implementation/apple/Mediums/BLEv2/GNCBLEL2CAPServer.h"
+
+#import <Foundation/Foundation.h>
+
+@protocol GNCPeripheralManager;
+
+NS_ASSUME_NONNULL_BEGIN
+
+@interface GNCBLEL2CAPServer (Testing)
+
+/**
+ * Creates a L2CAP server with a provided peripheral manager.
+ *
+ * This is only exposed for testing and can be used to inject a fake peripheral manager.
+ *
+ * @param peripheralManager The peripheral manager instance.
+ */
+- (instancetype)initWithPeripheralManager:(id<GNCPeripheralManager>)peripheralManager;
+
+@end
+
+NS_ASSUME_NONNULL_END

internal/platform/implementation/apple/Tests/GNCBLEL2CAPServerTest.m

@@ -0,0 +1,75 @@
+// Copyright 2025 Google LLC
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     https://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+#import "internal/platform/implementation/apple/Mediums/BLEv2/GNCBLEL2CAPServer.h"
+
+#import <CoreBluetooth/CoreBluetooth.h>
+#import <Foundation/Foundation.h>
+#import <XCTest/XCTest.h>
+
+#import "internal/platform/implementation/apple/Tests/GNCBLEL2CAPServer+Testing.h"
+#import "internal/platform/implementation/apple/Tests/GNCFakePeripheralManager.h"
+
+static const int kPSM = 192;
+
+@interface GNCBLEL2CAPServerTest : XCTestCase
+@end
+
+@implementation GNCBLEL2CAPServerTest
+
+#pragma mark - Publish L2CAP channel
+
+- (void)testPublishL2CAPChannel {
+  GNCFakePeripheralManager *fakePeripheralManager = [[GNCFakePeripheralManager alloc] init];
+
+  fakePeripheralManager.PSM = kPSM;
+  GNCBLEL2CAPServer *l2capServer =
+      [[GNCBLEL2CAPServer alloc] initWithPeripheralManager:fakePeripheralManager];
+
+  [fakePeripheralManager simulatePeripheralManagerDidUpdateState:CBManagerStatePoweredOn];
+
+  XCTAssertEqual([l2capServer PSM], kPSM);
+  XCTAssertNotNil([l2capServer getChannel]);
+}
+
+- (void)testFailedToPublishL2CAPChannel {
+  GNCFakePeripheralManager *fakePeripheralManager = [[GNCFakePeripheralManager alloc] init];
+
+  fakePeripheralManager.didPublishL2CAPChannelError = [NSError errorWithDomain:@"fake"
+                                                                          code:0
+                                                                      userInfo:nil];
+  fakePeripheralManager.PSM = kPSM;
+  GNCBLEL2CAPServer *l2capServer =
+      [[GNCBLEL2CAPServer alloc] initWithPeripheralManager:fakePeripheralManager];
+
+  [fakePeripheralManager simulatePeripheralManagerDidUpdateState:CBManagerStatePoweredOn];
+
+  XCTAssertNotEqual([l2capServer PSM], kPSM);
+  XCTAssertNil([l2capServer getChannel]);
+}
+
+- (void)testUnPublishL2CAPChannel {
+  GNCFakePeripheralManager *fakePeripheralManager = [[GNCFakePeripheralManager alloc] init];
+
+  fakePeripheralManager.PSM = kPSM;
+  GNCBLEL2CAPServer *l2capServer =
+      [[GNCBLEL2CAPServer alloc] initWithPeripheralManager:fakePeripheralManager];
+
+  [fakePeripheralManager simulatePeripheralManagerDidUpdateState:CBManagerStatePoweredOn];
+  [fakePeripheralManager simulatePeripheralManagerDidUpdateState:CBManagerStatePoweredOff];
+
+  XCTAssertEqual([l2capServer PSM], 0);
+}
+
+@end

internal/platform/implementation/apple/Tests/GNCFakePeripheralManager.h

@@ -35,6 +35,9 @@ NS_ASSUME_NONNULL_BEGIN
 /** The data being advertised. */
 @property(nonatomic, nullable, readonly) NSDictionary<NSString *, id> *advertisementData;
 
+/** The PSM of the L2CAP channel. */
+@property(nonatomic) CBL2CAPPSM PSM;
+
 /** Expectation fulfilled when peripheral responds to a request with success. */
 @property(nonatomic, readonly) XCTestExpectation *respondToRequestSuccessExpectation;
 
@@ -59,6 +62,24 @@ NS_ASSUME_NONNULL_BEGIN
  */
 @property(nonatomic, nullable, readwrite) NSError *didStartAdvertisingError;
 
+/**
+ * Similates a @c publishL2CAPChannel: error.
+ *
+ * Setting this error to a value other than @c nil will simulate a failure when calling @c
+ * publishL2CAPChannel: and will call the @c gnc_peripheralManager:didPublishL2CAPChannel:error:
+ * delegate method with the provided error.
+ */
+@property(nonatomic, nullable, readwrite) NSError *didPublishL2CAPChannelError;
+
+/**
+ * Similates a @c unpublishL2CAPChannel: error.
+ *
+ * Setting this error to a value other than @c nil will simulate a failure when calling @c
+ * unpublishL2CAPChannel: and will call the @c gnc_peripheralManager:didUnpublishL2CAPChannel:error:
+ * delegate method with the provided error.
+ */
+@property(nonatomic, nullable, readwrite) NSError *didUnPublishL2CAPChannelError;
+
 /**
  * Simulates a state update event.
  *

internal/platform/implementation/apple/Tests/GNCFakePeripheralManager.m

@@ -122,6 +122,27 @@
   _isAdvertising = false;
 }
 
+- (void)publishL2CAPChannelWithEncryption:(BOOL)encryptionRequired {
+  CBL2CAPPSM localPSM = 0;
+  if (!_didPublishL2CAPChannelError) {
+    localPSM = _PSM;
+  }
+  [peripheralDelegate gnc_peripheralManager:self
+                     didPublishL2CAPChannel:localPSM
+                                      error:_didPublishL2CAPChannelError];
+  if (!_didPublishL2CAPChannelError) {
+    [peripheralDelegate gnc_peripheralManager:self
+                          didOpenL2CAPChannel:[[CBL2CAPChannel alloc] init]
+                                        error:nil];
+  }
+}
+
+- (void)unpublishL2CAPChannel:(CBL2CAPPSM)PSM {
+  [peripheralDelegate gnc_peripheralManager:self
+                   didUnpublishL2CAPChannel:_PSM
+                                      error:_didUnPublishL2CAPChannelError];
+}
+
 #pragma mark - Testing Helpers
 
 - (NSArray<CBService *> *)services {