Use DCT flag to control BLE encoding

PiperOrigin-RevId: 756496067

Package.swift

@@ -423,6 +423,7 @@ let package = Package(
         "internal/weave/sockets/BUILD",
         "internal/platform/flags/BUILD",
         "internal/platform/implementation/shared/BUILD",
+        "internal/platform/implementation/apple/Flags/BUILD",
         "internal/platform/implementation/apple/Mediums/BUILD",
         "internal/platform/implementation/apple/Mediums/Ble/Sockets/BUILD",
         "internal/platform/implementation/apple/Tests/BUILD",

internal/platform/implementation/apple/BUILD

@@ -118,6 +118,7 @@ objc_library(
         "//internal/platform:cancellation_flag",
         "//internal/platform:uuid",
         "//internal/platform/implementation:comm",
+        "//internal/platform/implementation/apple/Flags",
         "//internal/platform/implementation/apple/Mediums",
         "//internal/platform/implementation/apple/Mediums/Ble/Sockets:Central",
         "//internal/platform/implementation/apple/Mediums/Ble/Sockets:Peripheral",

internal/platform/implementation/apple/Flags/BUILD

@@ -0,0 +1,29 @@
+# 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.
+licenses(["notice"])
+
+package(default_visibility = [
+    "//internal/platform/implementation/apple:__subpackages__",
+])
+
+objc_library(
+    name = "Flags",
+    srcs = ["GNCFeatureFlags.mm"],
+    hdrs = ["GNCFeatureFlags.h"],
+    deps = [
+        "//connections/implementation/flags:connections_flags",
+        "//internal/flags:nearby_flags",
+        "//third_party/apple_frameworks:Foundation",
+    ],
+)

internal/platform/implementation/apple/Flags/GNCFeatureFlags.h

@@ -0,0 +1,23 @@
+// 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 <Foundation/Foundation.h>
+
+/** A utility class for accessing and overriding Nearby feature flags. */
+@interface GNCFeatureFlags : NSObject
+
+/** Checks whether DCT is enabled in the Nearby Connections SDK. */
+@property(nonatomic, class, readonly) BOOL dctEnabled;
+
+@end

internal/platform/implementation/apple/Flags/GNCFeatureFlags.mm

@@ -0,0 +1,27 @@
+// 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/Flags/GNCFeatureFlags.h"
+
+#include "connections/implementation/flags/nearby_connections_feature_flags.h"
+#include "internal/flags/nearby_flags.h"
+
+@implementation GNCFeatureFlags
+
++ (BOOL)dctEnabled {
+  return nearby::NearbyFlags::GetInstance().GetBoolFlag(
+      nearby::connections::config_package_nearby::nearby_connections_feature::kEnableDct);
+}
+
+@end

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

@@ -17,6 +17,7 @@
 #import <CoreBluetooth/CoreBluetooth.h>
 #import <Foundation/Foundation.h>
 
+#import "internal/platform/implementation/apple/Flags/GNCFeatureFlags.h"
 #import "internal/platform/implementation/apple/Mediums/BLEv2/GNCBLEError.h"
 #import "internal/platform/implementation/apple/Mediums/BLEv2/GNCBLEGATTCharacteristic.h"
 #import "internal/platform/implementation/apple/Mediums/BLEv2/GNCPeripheralManager.h"
@@ -204,11 +205,8 @@ static char *const kGNCBLEGATTServerQueueLabel = "com.nearby.GNCBLEGATTServer";
     // data is unavailable.
     CBUUID *serviceUUID = [serviceData.allKeys objectAtIndex:0];
     NSData *value = [serviceData objectForKey:serviceUUID];
-#if defined(NC_IOS_SDK)
-    NSString *encoded = [value base85EncodedString];
-#else
-    NSString *encoded = [value webSafeBase64EncodedString];
-#endif  // defined(NC_IOS_SDK)
+    NSString *encoded = GNCFeatureFlags.dctEnabled ? [value base85EncodedString]
+                                                   : [value webSafeBase64EncodedString];
 
     // 23 bytes is the standard length which we used in the NC protocol with PSM. The BLE v2
     // advertisement header is default with psm value included so the length is always 23 bytes.

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

@@ -17,6 +17,7 @@
 #import <CoreBluetooth/CoreBluetooth.h>
 #import <Foundation/Foundation.h>
 
+#import "internal/platform/implementation/apple/Flags/GNCFeatureFlags.h"
 #import "internal/platform/implementation/apple/Mediums/BLEv2/GNCBLEError.h"
 #import "internal/platform/implementation/apple/Mediums/BLEv2/GNCBLEGATTClient.h"
 #import "internal/platform/implementation/apple/Mediums/BLEv2/GNCBLEGATTServer.h"
@@ -283,11 +284,10 @@ static GNCBLEL2CAPServer *_Nonnull CreateL2CapServer(
   if (!localName) {
     return @{};
   }
-#if defined(NC_IOS_SDK)
-  NSData *data = [[NSData alloc] initWithBase85EncodedString:localName];
-#else
-  NSData *data = [[NSData alloc] initWithWebSafeBase64EncodedString:localName];
-#endif  // defined(NC_IOS_SDK)
+
+  NSData *data = GNCFeatureFlags.dctEnabled
+                     ? [[NSData alloc] initWithBase85EncodedString:localName]
+                     : [[NSData alloc] initWithWebSafeBase64EncodedString:localName];
 
   // A Nearby Apple advertisement should only have a single service, so simply grab the first one if
   // it exists.

internal/platform/implementation/apple/Mediums/BUILD

@@ -79,6 +79,7 @@ objc_library(
     deps = [
         "//internal/encoding:base85",
         "//internal/platform/implementation/apple:Shared",
+        "//internal/platform/implementation/apple/Flags",
         "//internal/platform/implementation/apple/Mediums/Ble/Sockets:Shared",
         "//proto/mediums:ble_frames_cc_proto",
         "//third_party/apple_frameworks:CoreBluetooth",

internal/platform/implementation/apple/ble_gatt_client.mm

@@ -23,6 +23,7 @@
 
 #include "internal/platform/implementation/ble_v2.h"
 
+#import "internal/platform/implementation/apple/Flags/GNCFeatureFlags.h"
 #import "internal/platform/implementation/apple/Mediums/BLEv2/GNCBLEGATTClient.h"
 #import "internal/platform/implementation/apple/ble_utils.h"
 #import "GoogleToolboxForMac/GTMLogger.h"
@@ -128,15 +129,15 @@ bool GattClient::SetCharacteristicSubscription(
 }
 
 void GattClient::Disconnect() {
-// There seems to be an issue between some iOS<>Android device pairs where the Android device will
-// not connect to the iOS device if the iOS device disconnects and then attempts to reconnect.
-// Because of this, we no-op here instead of calling `[gatt_client_ disconnect]`.
-// See: b/375176623
-#if defined(NC_IOS_SDK)
-  // Avoid to impact GTV functionality, put the disconnect for NC iOS SDK only, so thatGATT client
-  // can reconnect to the GATT server.
-  [gatt_client_ disconnect];
-#endif
+  // There seems to be an issue between some iOS<>Android device pairs where the Android device will
+  // not connect to the iOS device if the iOS device disconnects and then attempts to reconnect.
+  // Because of this, we no-op here instead of calling `[gatt_client_ disconnect]`.
+  // See: b/375176623
+  if (GNCFeatureFlags.dctEnabled) {
+    // Avoid to impact GTV functionality, put the disconnect for NC iOS SDK only, so thatGATT client
+    // can reconnect to the GATT server.
+    [gatt_client_ disconnect];
+  }
 }
 
 }  // namespace apple