CKKSSynchronizeOperation.m   [plain text]

/*
* Copyright (c) 2016 Apple Inc. All Rights Reserved.
*
* @APPLE_LICENSE_HEADER_START@
*
* This file contains Original Code and/or Modifications of Original Code
* as defined in and that are subject to the Apple Public Source License
* Version 2.0 (the 'License'). You may not use this file except in
* compliance with the License. Please obtain a copy of the License at
* http://www.opensource.apple.com/apsl/ and read it before using this
* file.
*
* The Original Code and all software distributed under the License are
* distributed on an 'AS IS' basis, WITHOUT WARRANTY OF ANY KIND, EITHER
* EXPRESS OR IMPLIED, AND APPLE HEREBY DISCLAIMS ALL SUCH WARRANTIES,
* INCLUDING WITHOUT LIMITATION, ANY WARRANTIES OF MERCHANTABILITY,
* FITNESS FOR A PARTICULAR PURPOSE, QUIET ENJOYMENT OR NON-INFRINGEMENT.
* Please see the License for the specific language governing rights and
* limitations under the License.
*
* @APPLE_LICENSE_HEADER_END@
*/

#import "CKKSKeychainView.h"
#import "CKKSGroupOperation.h"
#import "CKKSSynchronizeOperation.h"
#import "CKKSFetchAllRecordZoneChangesOperation.h"
#import "CKKSScanLocalItemsOperation.h"
#import "keychain/ckks/CloudKitCategories.h"
#import "keychain/categories/NSError+UsefulConstructors.h"

#if OCTAGON

@interface CKKSSynchronizeOperation ()
@property int32_t restartCount;
@end

@implementation CKKSSynchronizeOperation

- (instancetype)init {
return nil;
}
- (instancetype)initWithCKKSKeychainView:(CKKSKeychainView*)ckks {
if(self = [super init]) {
_ckks = ckks;
_restartCount = 0;
}
return self;
}

- (void)groupStart {
__weak __typeof(self) weakSelf = self;

/*
* Synchronizations (or resynchronizations) are complicated beasts. We will:
*
* 1. Finish processing the outgoing queue. You can't be in-sync with cloudkit if you have an update that hasn't propagated.
* 2. Kick off a normal CloudKit fetch.
* 3. Process the incoming queue as normal.
* (Note that this requires the keybag to be unlocked.)
*
* So far, this is normal operation. Now:
*
* 4. Start another CloudKit fetch, giving it the nil change tag. This fetches all objects in CloudKit.
* 4a. Compare those objects against our local mirror. If any discrepancies, this is a bug.
* 4b. All conflicts: CloudKit data wins.
* 4c. All items we have that CloudKit doesn't: delete locally.
*
* 5. Process the incoming queue again. This should be empty.
* 6. Scan the local keychain for items which exist locally but are not in CloudKit. Upload them.
* 7. If there are any such items in 6, restart the sync.
*/

// Promote to strong reference
CKKSKeychainView* ckks = self.ckks;

// Synchronous, on some thread. Get back on the CKKS queue for SQL thread-safety.
[ckks dispatchSync: ^bool{
if(self.cancelled) {
ckksnotice("ckksresync", ckks, "CKKSSynchronizeOperation cancelled, quitting");
return false;
}

ckks.lastSynchronizeOperation = self;

uint32_t steps = 7;

ckksinfo("ckksresync", ckks, "Beginning resynchronize (attempt %u)", self.restartCount);

CKOperationGroup* operationGroup = [CKOperationGroup CKKSGroupWithName:@"ckks-resync"];

// Step 1
CKKSOutgoingQueueOperation* outgoingOp = [ckks processOutgoingQueue: operationGroup];
outgoingOp.name = [NSString stringWithFormat: @"resync-step%u-outgoing", self.restartCount * steps + 1];
[self dependOnBeforeGroupFinished:outgoingOp];

// Step 2
CKKSFetchAllRecordZoneChangesOperation* fetchOp = [[CKKSFetchAllRecordZoneChangesOperation alloc] initWithContainer:ckks.container
fetchClass:ckks.fetchRecordZoneChangesOperationClass
clients:@[ckks]
fetchReasons:[NSSet setWithObject:CKKSFetchBecauseResync]
apnsPushes:nil
forceResync:true
ckoperationGroup:operationGroup];
fetchOp.name = [NSString stringWithFormat: @"resync-step%u-fetch", self.restartCount * steps + 2];
[fetchOp addSuccessDependency: outgoingOp];
[self runBeforeGroupFinished: fetchOp];

// Step 3
CKKSIncomingQueueOperation* incomingOp = [[CKKSIncomingQueueOperation alloc] initWithCKKSKeychainView:ckks errorOnClassAFailure:true];
incomingOp.name = [NSString stringWithFormat: @"resync-step%u-incoming", self.restartCount * steps + 3];
[incomingOp addSuccessDependency:fetchOp];
[self runBeforeGroupFinished:incomingOp];

// Now, get serious:

// Step 4
CKKSFetchAllRecordZoneChangesOperation* fetchAllOp = [[CKKSFetchAllRecordZoneChangesOperation alloc] initWithContainer:ckks.container
fetchClass:ckks.fetchRecordZoneChangesOperationClass
clients:@[ckks]
fetchReasons:[NSSet setWithObject:CKKSFetchBecauseResync]
apnsPushes:nil
forceResync:true
ckoperationGroup:operationGroup];
fetchAllOp.resync = true;
fetchAllOp.name = [NSString stringWithFormat: @"resync-step%u-fetchAll", self.restartCount * steps + 4];
[fetchAllOp addSuccessDependency: incomingOp];
[self runBeforeGroupFinished: fetchAllOp];

// Step 5
CKKSIncomingQueueOperation* incomingResyncOp = [[CKKSIncomingQueueOperation alloc] initWithCKKSKeychainView:ckks errorOnClassAFailure:true];
incomingResyncOp.name = [NSString stringWithFormat: @"resync-step%u-incoming", self.restartCount * steps + 5];
[incomingResyncOp addSuccessDependency: fetchAllOp];
[self runBeforeGroupFinished:incomingResyncOp];

// Step 6
CKKSScanLocalItemsOperation* scan = [[CKKSScanLocalItemsOperation alloc] initWithCKKSKeychainView:ckks ckoperationGroup:operationGroup];
scan.name = [NSString stringWithFormat: @"resync-step%u-scan", self.restartCount * steps + 6];
[scan addSuccessDependency: incomingResyncOp];
[self runBeforeGroupFinished: scan];

// Step 7:
CKKSResultOperation* restart = [[CKKSResultOperation alloc] init];
restart.name = [NSString stringWithFormat: @"resync-step%u-consider-restart", self.restartCount * steps + 7];
[restart addExecutionBlock:^{
__strong __typeof(weakSelf) strongSelf = weakSelf;
if(!strongSelf) {
secerror("ckksresync: received callback for released object");
return;
}

if(scan.recordsFound > 0) {
if(strongSelf.restartCount >= 3) {
// we've restarted too many times. Fail and stop.
ckkserror("ckksresync", ckks, "restarted synchronization too often; Failing");
strongSelf.error = [NSError errorWithDomain:@"securityd"
code:2
userInfo:@{NSLocalizedDescriptionKey: @"resynchronization restarted too many times; churn in database?"}];
} else {
// restart the sync operation.
strongSelf.restartCount += 1;
ckkserror("ckksresync", ckks, "restarting synchronization operation due to new local items");
[strongSelf groupStart];
}
}
}];

[restart addSuccessDependency: scan];
[self runBeforeGroupFinished: restart];

return true;
}];
}

@end;

#endif