Add Darwin API for starting multiple controllers on the same fabric.

Fixes project-chip#27394

src/darwin/Framework/CHIP/MTRDeviceController.mm

@@ -374,6 +374,7 @@ - (BOOL)startup:(MTRDeviceControllerStartupParamsInternal *)startupParams
  // bring-up.
  commissionerParams.removeFromFabricTableOnShutdown = false;
  commissionerParams.deviceAttestationVerifier = _factory.deviceAttestationVerifier;
+ commissionerParams.permitMultiControllerFabrics = startupParams.isAdditionalController;
 
  auto & factory = chip::Controller::DeviceControllerFactory::GetInstance();
 

src/darwin/Framework/CHIP/MTRDeviceControllerFactory.h

@@ -149,6 +149,22 @@ API_AVAILABLE(ios(16.4), macos(13.3), watchos(9.4), tvos(16.4))
 - (MTRDeviceController * _Nullable)createControllerOnExistingFabric:(MTRDeviceControllerStartupParams *)startupParams
  error:(NSError * __autoreleasing *)error;
 
+/**
+ * Create an additional MTRDeviceController on an existing fabric. Returns nil on failure.
+ *
+ * The fabric is identified by the root public key and fabric id in
+ * the startupParams.
+ *
+ * This method will fail if there is no such fabric.
+ *
+ * This method will fail if the MTRDeviceControllerStartupParams don't follow
+ * the rules for creating a controller on a new fabric. In particular, the
+ * vendor ID must not be nil.
+ */
+- (MTRDeviceController * _Nullable)createAdditionalControllerOnExistingFabric:(MTRDeviceControllerStartupParams *)startupParams
+ error:(NSError * __autoreleasing *)error
+ MTR_NEWLY_AVAILABLE;
+
 /**
  * Create a MTRDeviceController on a new fabric. Returns nil on failure.
  *

src/darwin/Framework/CHIP/MTRDeviceControllerFactory.mm

@@ -619,8 +619,21 @@ - (MTRDeviceController * _Nullable)_startDeviceController:(MTRDeviceControllerSt
  return controller;
 }
 
+- (MTRDeviceController * _Nullable)createAdditionalControllerOnExistingFabric:(MTRDeviceControllerStartupParams *)startupParams
+ error:(NSError * __autoreleasing *)error
+{
+ return [self _createControllerOnExistingFabric:startupParams isAdditional:YES error:error];
+}
+
 - (MTRDeviceController * _Nullable)createControllerOnExistingFabric:(MTRDeviceControllerStartupParams *)startupParams
  error:(NSError * __autoreleasing *)error
+{
+ return [self _createControllerOnExistingFabric:startupParams isAdditional:NO error:error];
+}
+
+- (MTRDeviceController * _Nullable)_createControllerOnExistingFabric:(MTRDeviceControllerStartupParams *)startupParams
+ isAdditional:(BOOL)isAdditional
+ error:(NSError * __autoreleasing *)error
 {
  [self _assertCurrentQueueIsNotMatterQueue];
 
@@ -643,28 +656,37 @@ - (MTRDeviceController * _Nullable)createControllerOnExistingFabric:(MTRDeviceCo
 
  auto * controllersCopy = [self getRunningControllers];
 
- for (MTRDeviceController * existing in controllersCopy) {
- BOOL isRunning = YES; // assume the worst
- if ([existing isRunningOnFabric:fabricTable fabricIndex:fabric->GetFabricIndex() isRunning:&isRunning]
- != CHIP_NO_ERROR) {
- MTR_LOG_ERROR("Can't tell what fabric a controller is running on. Not safe to start.");
- fabricError = CHIP_ERROR_INTERNAL;
- return nil;
+ MTRDeviceControllerStartupParamsInternal * params;
+ if (!isAdditional) {
+ for (MTRDeviceController * existing in controllersCopy) {
+ BOOL isRunning = YES; // assume the worst
+ if ([existing isRunningOnFabric:fabricTable fabricIndex:fabric->GetFabricIndex() isRunning:&isRunning]
+ != CHIP_NO_ERROR) {
+ MTR_LOG_ERROR("Can't tell what fabric a controller is running on. Not safe to start.");
+ fabricError = CHIP_ERROR_INTERNAL;
+ return nil;
+ }
+
+ if (isRunning) {
+ MTR_LOG_ERROR("Can't start on existing fabric: another controller is running on it");
+ fabricError = CHIP_ERROR_INCORRECT_STATE;
+ return nil;
+ }
  }
 
- if (isRunning) {
- MTR_LOG_ERROR("Can't start on existing fabric: another controller is running on it");
- fabricError = CHIP_ERROR_INCORRECT_STATE;
- return nil;
- }
+ params =
+ [[MTRDeviceControllerStartupParamsInternal alloc] _initForExistingFabricEntry:fabricTable
+ fabricIndex:fabric->GetFabricIndex()
+ keystore:self->_keystore
+ advertiseOperational:self.advertiseOperational
+ params:startupParams];
+ } else {
+ params = [[MTRDeviceControllerStartupParamsInternal alloc] _initForNewFabricEntry:fabricTable
+ keystore:self->_keystore
+ advertiseOperational:self.advertiseOperational
+ params:startupParams
+ isAdditionalController:YES];
  }
-
- auto * params =
- [[MTRDeviceControllerStartupParamsInternal alloc] initForExistingFabric:fabricTable
- fabricIndex:fabric->GetFabricIndex()
- keystore:self->_keystore
- advertiseOperational:self.advertiseOperational
- params:startupParams];
  if (params == nil) {
  fabricError = CHIP_ERROR_NO_MEMORY;
  }
@@ -679,22 +701,6 @@ - (MTRDeviceController * _Nullable)createControllerOnNewFabric:(MTRDeviceControl
 {
  [self _assertCurrentQueueIsNotMatterQueue];
 
- if (startupParams.vendorID == nil) {
- MTR_LOG_ERROR("Must provide vendor id when starting controller on new fabric");
- if (error != nil) {
- *error = [MTRError errorForCHIPErrorCode:CHIP_ERROR_INVALID_ARGUMENT];
- }
- return nil;
- }
-
- if (startupParams.intermediateCertificate != nil && startupParams.rootCertificate == nil) {
- MTR_LOG_ERROR("Must provide a root certificate when using an intermediate certificate");
- if (error != nil) {
- *error = [MTRError errorForCHIPErrorCode:CHIP_ERROR_INVALID_ARGUMENT];
- }
- return nil;
- }
-
  return [self
  _startDeviceController:startupParams
  fabricChecker:^MTRDeviceControllerStartupParamsInternal *(FabricTable * fabricTable, CHIP_ERROR & fabricError) {
@@ -712,10 +718,12 @@ - (MTRDeviceController * _Nullable)createControllerOnNewFabric:(MTRDeviceControl
  return nil;
  }
 
- auto * params = [[MTRDeviceControllerStartupParamsInternal alloc] initForNewFabric:fabricTable
- keystore:self->_keystore
- advertiseOperational:self.advertiseOperational
- params:startupParams];
+ auto * params =
+ [[MTRDeviceControllerStartupParamsInternal alloc] _initForNewFabricEntry:fabricTable
+ keystore:self->_keystore
+ advertiseOperational:self.advertiseOperational
+ params:startupParams
+ isAdditionalController:NO];
  if (params == nil) {
  fabricError = CHIP_ERROR_NO_MEMORY;
  }

src/darwin/Framework/CHIP/MTRDeviceControllerStartupParams.mm

@@ -211,15 +211,26 @@ - (instancetype)initWithParams:(MTRDeviceControllerStartupParams *)params
  return self;
 }
 
-- (instancetype)initForNewFabric:(chip::FabricTable *)fabricTable
- keystore:(chip::Crypto::OperationalKeystore *)keystore
- advertiseOperational:(BOOL)advertiseOperational
- params:(MTRDeviceControllerStartupParams *)params
+- (instancetype)_initForNewFabricEntry:(chip::FabricTable *)fabricTable
+ keystore:(chip::Crypto::OperationalKeystore *)keystore
+ advertiseOperational:(BOOL)advertiseOperational
+ params:(MTRDeviceControllerStartupParams *)params
+ isAdditionalController:(BOOL)isAdditionalController
 {
  if (!(self = [self initWithParams:params])) {
  return nil;
  }
 
+ if (self.vendorID == nil) {
+ MTR_LOG_ERROR("Must provide vendor id when starting controller on new fabric");
+ return nil;
+ }
+
+ if (self.intermediateCertificate != nil && self.rootCertificate == nil) {
+ MTR_LOG_ERROR("Must provide a root certificate when using an intermediate certificate");
+ return nil;
+ }
+
  if (self.nocSigner == nil && self.operationalCertificate == nil) {
  MTR_LOG_ERROR("No way to get an operational certificate: nocSigner and operationalCertificate are both nil");
  return nil;
@@ -248,15 +259,16 @@ - (instancetype)initForNewFabric:(chip::FabricTable *)fabricTable
  _fabricTable = fabricTable;
  _keystore = keystore;
  _advertiseOperational = advertiseOperational;
+ _isAdditionalController = isAdditionalController;
 
  return self;
 }
 
-- (instancetype)initForExistingFabric:(FabricTable *)fabricTable
- fabricIndex:(FabricIndex)fabricIndex
- keystore:(chip::Crypto::OperationalKeystore *)keystore
- advertiseOperational:(BOOL)advertiseOperational
- params:(MTRDeviceControllerStartupParams *)params
+- (instancetype)_initForExistingFabricEntry:(FabricTable *)fabricTable
+  fabricIndex:(FabricIndex)fabricIndex
+  keystore:(chip::Crypto::OperationalKeystore *)keystore
+  advertiseOperational:(BOOL)advertiseOperational
+  params:(MTRDeviceControllerStartupParams *)params
 {
  if (!(self = [self initWithParams:params])) {
  return nil;
@@ -384,6 +396,7 @@ - (instancetype)initForExistingFabric:(FabricTable *)fabricTable
  _fabricIndex.Emplace(fabricIndex);
  _keystore = keystore;
  _advertiseOperational = advertiseOperational;
+ _isAdditionalController = NO;
 
  return self;
 }

src/darwin/Framework/CHIP/MTRDeviceControllerStartupParams_Internal.h

@@ -58,6 +58,8 @@ MTR_HIDDEN
 
 @property (nonatomic, assign, readonly) BOOL advertiseOperational;
 
+@property (nonatomic, assign, readonly) BOOL isAdditionalController;
+
 /**
  * Helper method that checks that our keypairs match our certificates.
  * Specifically:
@@ -73,21 +75,24 @@ MTR_HIDDEN
 - (BOOL)keypairsMatchCertificates;
 
 /**
- * Initialize for controller bringup on a new fabric.
+ * Initialize for controller bringup on a new fabric entry (which might be a new
+ * fabric or an additional controller on an existing fabric).
  */
-- (instancetype)initForNewFabric:(chip::FabricTable *)fabricTable
- keystore:(chip::Crypto::OperationalKeystore *)keystore
- advertiseOperational:(BOOL)advertiseOperational
- params:(MTRDeviceControllerStartupParams *)params;
+- (instancetype)_initForNewFabricEntry:(chip::FabricTable *)fabricTable
+ keystore:(chip::Crypto::OperationalKeystore *)keystore
+ advertiseOperational:(BOOL)advertiseOperational
+ params:(MTRDeviceControllerStartupParams *)params
+ isAdditionalController:(BOOL)isAdditionalController;
 
 /**
- * Initialize for controller bringup on an existing fabric.
+ * Initialize for controller bringup on an existing fabric entry, identified by
+ * the provided fabricIndex.
  */
-- (instancetype)initForExistingFabric:(chip::FabricTable *)fabricTable
- fabricIndex:(chip::FabricIndex)fabricIndex
- keystore:(chip::Crypto::OperationalKeystore *)keystore
- advertiseOperational:(BOOL)advertiseOperational
- params:(MTRDeviceControllerStartupParams *)params;
+- (instancetype)_initForExistingFabricEntry:(chip::FabricTable *)fabricTable
+  fabricIndex:(chip::FabricIndex)fabricIndex
+  keystore:(chip::Crypto::OperationalKeystore *)keystore
+  advertiseOperational:(BOOL)advertiseOperational
+  params:(MTRDeviceControllerStartupParams *)params;
 
 /**
  * Should use initForExistingFabric or initForNewFabric to initialize