CKDKVSProxy.m   [plain text]

/*
 * Copyright (c) 2012-2013 Apple Computer, 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@
 */

//
//  CKDKVSProxy.m
//  ckd-xpc
//

#import <Foundation/NSUbiquitousKeyValueStore.h>
#import <Foundation/NSUbiquitousKeyValueStore_Private.h>
#import <Foundation/NSArray.h>
#import <Foundation/Foundation.h>

#import <Security/SecBasePriv.h>
#import <Security/SecItemPriv.h>
#import <utilities/debugging.h>
#import <notify.h>

#import "CKDKVSProxy.h"
#import "CKDPersistentState.h"
#import "CKDUserInteraction.h"

#import "SOSARCDefines.h"

#include <SecureObjectSync/SOSAccount.h>
#include <SecureObjectSync/SOSCloudCircleInternal.h>
#include "SOSCloudKeychainConstants.h"

#include <utilities/SecAKSWrappers.h>
#include <utilities/SecCFRelease.h>

#define SOSCKCSCOPE "sync"

/*
    The total space available in your app’s iCloud key-value storage is 1 MB.
    The maximum number of keys you can specify is 1024, and the size limit for
    each value associated with a key is 1 MB. So, for example, if you store a
    single large value of 1 MB for a single key, that consumes your total
    available storage. If you store 1 KB of data for each key, you can use
    1,000 key-value pairs.
*/

static const char *kStreamName = "com.apple.notifyd.matching";


static NSString *kKeyAlwaysKeys = @"AlwaysKeys";
static NSString *kKeyFirstUnlockKeys = @"FirstUnlockKeys";
static NSString *kKeyUnlockedKeys = @"UnlockedKeys";
static NSString *kKeyPendingKeys = @"PendingKeys";
static NSString *kKeyUnsentChangedKeys = @"unsentChangedKeys";
static NSString *kKeyUnlockNotificationRequested = @"unlockNotificationRequested";
static NSString *kKeySyncWithPeersPending = @"SyncWithPeersPending";

enum
{
    kCallbackMethodSecurityd = 0,
    kCallbackMethodXPC = 1,
};

static const int64_t kMinSyncDelay = (NSEC_PER_MSEC * 500);
static const int64_t kMaxSyncDelay = (NSEC_PER_SEC * 5);
static const int64_t kMinSyncInterval = (NSEC_PER_SEC * 15);
static const int64_t kSyncTimerLeeway = (NSEC_PER_MSEC * 250);

@interface NSUbiquitousKeyValueStore (NSUbiquitousKeyValueStore_PrivateZ)
- (void) _synchronizeWithCompletionHandler:(void (^)(NSError *error))completionHandler;

/*
// SPI For Security
- (void) synchronizeWithCompletionHandler:(void (^)(NSError *error))completionHandler;
 */

@end

@implementation UbiqitousKVSProxy


- (void)persistState
{
    [SOSPersistentState setRegisteredKeys:[self exportKeyInterests]];
}

+ (UbiqitousKVSProxy *) sharedKVSProxy
{
    static UbiqitousKVSProxy *sharedKVSProxy;
    if (!sharedKVSProxy) {
        static dispatch_once_t onceToken;
        dispatch_once(&onceToken, ^{
            sharedKVSProxy = [[self alloc] init];
        });
    }
    return sharedKVSProxy;
}

- (id)init
{
    if (self = [super init])
    {
        secnotice("event", "%@ start", self);

        _syncTimer = dispatch_source_create(DISPATCH_SOURCE_TYPE_TIMER, 0, 0, dispatch_get_main_queue());
        dispatch_source_set_timer(_syncTimer, DISPATCH_TIME_FOREVER, DISPATCH_TIME_FOREVER, kSyncTimerLeeway);
        dispatch_source_set_event_handler(_syncTimer, ^{
            [self timerFired];
        });
        dispatch_resume(_syncTimer);

        [[NSNotificationCenter defaultCenter]
            addObserver: self
               selector: @selector (iCloudAccountAvailabilityChanged:)
                   name: NSUbiquityIdentityDidChangeNotification
                 object: nil];
        
        [[NSNotificationCenter defaultCenter] addObserver:self 
                selector:@selector(cloudChanged:)
                name:NSUbiquitousKeyValueStoreDidChangeExternallyNotification 
                object:nil];

        [self importKeyInterests: [SOSPersistentState registeredKeys]];

        // Register for lock state changes
        xpc_set_event_stream_handler(kStreamName, dispatch_get_main_queue(),
                                     ^(xpc_object_t notification){
                                         [self streamEvent:notification];
                                     });

        [self updateUnlockedSinceBoot];
        [self updateIsLocked];
        if (!_isLocked)
            [self keybagDidUnlock];

        secdebug(XPROXYSCOPE, "%@ done", self);
    }
    return self;
}

- (NSString *)description
{
    return [NSString stringWithFormat:@"<%s%s%s%s%s%s%s%s%s>",
            _isLocked ? "L" : "U",
            _unlockedSinceBoot ? "B" : "-",
            _seenKVSStoreChange ? "K" : "-",
            _syncTimerScheduled ? "T" : "-",
            _syncWithPeersPending ? "s" : "-",
            [_pendingKeys count] ? "p" : "-",
            _inCallout ? "C" : "-",
            _shadowSyncWithPeersPending ? "S" : "-",
            [_shadowPendingKeys count] ? "P" : "-"];
}

- (void)processAllItems
{
    NSDictionary *allItems = [self getAll];
    if (allItems)
    {
        secnotice("event", "%@ sending: %@", self, [[allItems allKeys] componentsJoinedByString: @" "]);
        [self processKeyChangedEvent:allItems];
    }
    else
        secdebug(XPROXYSCOPE, "%@ No items in KVS", self);
}

- (void)setItemsChangedBlock:(CloudItemsChangedBlock)itemsChangedBlock
{
    self->itemsChangedCallback = itemsChangedBlock;
}

- (void)dealloc
{
    secdebug(XPROXYSCOPE, "%@", self);
    [[NSNotificationCenter defaultCenter] removeObserver:self
        name:NSUbiquitousKeyValueStoreDidChangeExternallyNotification object:nil];

    [[NSNotificationCenter defaultCenter] removeObserver:self 
        name:NSUbiquityIdentityDidChangeNotification object:nil];
}

// MARK: ----- Client Interface -----

- (void)setObject:(id)obj forKey:(id)key
{
    secdebug("keytrace", "%@ key: %@, obj: %@", self, key, obj);
    NSUbiquitousKeyValueStore *store = [self cloudStore];
    if (store)
    {
        id value = [store objectForKey:key];
        if (value)
            secdebug("keytrace", "%@ Current value (before set) for key %@ is: %@", self, key, value);
        else
            secdebug("keytrace", "%@ No current value for key %@", self, key);
    }
    else
        secdebug("keytrace", "Can't get store");
    
    [[self cloudStore] setObject:obj forKey:key];
    [self requestSynchronization:NO];
}

- (void)setObjectsFromDictionary:(NSDictionary *)values
{
    secdebug(XPROXYSCOPE, "%@ start: %lu values to put", self, (unsigned long)[values count]);

    NSUbiquitousKeyValueStore *store = [self cloudStore];
    if (store && values)
    {
        [values enumerateKeysAndObjectsUsingBlock: ^(id key, id obj, BOOL *stop)
        {
            if (obj == NULL || obj == [NSNull null])
                [store removeObjectForKey:key];
            else
                [store setObject:obj forKey:key];
        }];

        [self requestSynchronization:NO];
    }
    else
        secdebug(XPROXYSCOPE, "%@ NULL? store: %@, values: %@", self, store, values);
}

- (void)requestSynchronization:(bool)force
{
    if (force)
    {
        secdebug(XPROXYSCOPE, "%@ synchronize (forced)", self);
        [[self cloudStore] synchronize];
    }
    else
    {
        secdebug(XPROXYSCOPE, "%@ synchronize (soon)", self);
        [[self cloudStore] synchronize];
    }
}

- (NSUbiquitousKeyValueStore *)cloudStore
{
    NSUbiquitousKeyValueStore *iCloudStore = [NSUbiquitousKeyValueStore defaultStore];
//    secdebug(XPROXYSCOPE, "cloudStore: %@", iCloudStore);
    return iCloudStore;
}

// try to synchronize asap, and invoke the handler on completion to take incoming changes.
- (void)waitForSynchronization:(NSArray *)keys handler:(void (^)(NSDictionary *values, NSError *err))handler
{
    secdebug(XPROXYSCOPE, "%@ synchronize and wait", self);

    if (!keys)
    {
        NSError *err = [NSError errorWithDomain:(NSString *)NSPOSIXErrorDomain code:(NSInteger)ENOPROTOOPT userInfo:nil];
        handler(@{}, err);
        return;
    }

    secdebug(XPROXYSCOPE, "%@ Requesting synchronizeWithCompletionHandler", self);

    [[self cloudStore] synchronizeWithCompletionHandler:^(NSError *error) {
        [[self cloudStore] synchronize]; // Per olivier in <rdar://problem/13412631>, sync before getting values

        NSDictionary * changedKeys = error ? @{} : [self copyChangedValues:[NSSet setWithArray:keys]];

        secdebug(XPROXYSCOPE, "%@ Got synchronize completion %@ (error %@)", self, changedKeys, error);
        handler(changedKeys, error);
    }];
}

- (void)dumpStore
{
    NSDictionary *dict = [[self cloudStore] dictionaryRepresentation];
    [dict enumerateKeysAndObjectsUsingBlock:^(id key, id obj, BOOL *stop) {
        secdebug(XPROXYSCOPE, "%@ Dump: value for key %@ is: %@", self, key, obj);
    }];
}

- (void)removeObjectForKey:(NSString *)keyToRemove
{
    [[self cloudStore] removeObjectForKey:keyToRemove];
}

- (void)clearStore
{
    secdebug(XPROXYSCOPE, "%@ clearStore", self);
    NSDictionary *dict = [[self cloudStore] dictionaryRepresentation];
    NSArray *allKeys = [dict allKeys];
    [allKeys enumerateObjectsUsingBlock:^(id key, NSUInteger idx, BOOL *stop)
    {
        secdebug(XPROXYSCOPE, "%@ Clearing value for key %@", self, key);
        [[self cloudStore] removeObjectForKey:(NSString *)key];
    }];

    [self requestSynchronization:YES];
}


//
// MARK: ----- KVS key lists -----
//

- (id)get:(id)key
{
    return [[self cloudStore] objectForKey:key];
}

- (NSDictionary *)getAll
{
    return [[self cloudStore] dictionaryRepresentation];
}

- (NSDictionary*) exportKeyInterests
{
    return @{ kKeyAlwaysKeys:[_alwaysKeys allObjects],
              kKeyFirstUnlockKeys:[_firstUnlockKeys allObjects],
              kKeyUnlockedKeys:[_unlockedKeys allObjects],
              kKeyPendingKeys:[_pendingKeys allObjects],
              kKeySyncWithPeersPending:[NSNumber numberWithBool:_syncWithPeersPending]
              };
}

- (void) importKeyInterests: (NSDictionary*) interests
{
    _alwaysKeys = [NSSet setWithArray: interests[kKeyAlwaysKeys]];
    _firstUnlockKeys = [NSSet setWithArray: interests[kKeyFirstUnlockKeys]];
    _unlockedKeys = [NSSet setWithArray: interests[kKeyUnlockedKeys]];
    _pendingKeys = [NSMutableSet setWithArray: interests[kKeyPendingKeys]];
    _syncWithPeersPending = [interests[kKeySyncWithPeersPending] boolValue];
}

- (NSMutableSet *)copyAllKeys
{
    NSMutableSet *allKeys = [NSMutableSet setWithSet: _alwaysKeys];
    [allKeys unionSet: _firstUnlockKeys];
    [allKeys unionSet: _unlockedKeys];
    return allKeys;
}

- (NSDictionary *)registerKeysAndGet:(BOOL)getNewKeysOnly always:(NSArray *)keysToRegister reqFirstUnlock:(NSArray *)reqFirstUnlock reqUnlocked:(NSArray *)reqUnlocked
{
    NSMutableSet *allOldKeys = [self copyAllKeys];
    _alwaysKeys = [NSSet setWithArray: keysToRegister];
    _firstUnlockKeys = [NSSet setWithArray: reqFirstUnlock];
    _unlockedKeys = [NSSet setWithArray: reqUnlocked];
    NSMutableSet *allNewKeys = [self copyAllKeys];

    [_pendingKeys intersectSet:allNewKeys];

    NSSet* keysToGet = nil;
    if (getNewKeysOnly) {
        [allNewKeys minusSet:allOldKeys];
        keysToGet = allNewKeys;
    } else {
        keysToGet = [self keysForCurrentLockState];
    }

    // Mark keysToGet for the current lockState as pending
    NSSet *filteredKeys = [self filterKeySetWithLockState:keysToGet];
    [self persistState];
    NSMutableDictionary *returnedValues = [self copyChangedValues: filteredKeys];

    secnotice("keytrace", "%@ [%s] always: %@ firstUnlock: %@ unlocked: %@ got: %@", self, getNewKeysOnly ? "new only " : "", [keysToRegister componentsJoinedByString: @" "], [reqFirstUnlock componentsJoinedByString: @" "], [reqUnlocked componentsJoinedByString: @" "], [[returnedValues allKeys] componentsJoinedByString: @" "]);

    [self processKeyChangedEvent:returnedValues];
    [returnedValues removeAllObjects];

    return returnedValues;
}

- (NSDictionary *)localNotification:(NSDictionary *)localNotificationDict outFlags:(int64_t *)outFlags
{
    __block bool done = false;
    __block int64_t returnedFlags = 0;
    __block NSDictionary *responses = NULL;
    typedef bool (^CKDUserInteractionBlock) (CFDictionaryRef responses);

    CKDUserInteraction *cui = [CKDUserInteraction sharedInstance];
    [cui requestShowNotification:localNotificationDict completion:^ bool (CFDictionaryRef userResponses, int64_t flags)
        {
            responses = [NSDictionary dictionaryWithDictionary:(__bridge NSDictionary *)userResponses];
            returnedFlags = flags;
            secdebug(XPROXYSCOPE, "%@ requestShowNotification: dict: %@, flags: %#llx", self, responses, returnedFlags);
            done = true;
            return true;
        }];

    // TODO: replace with e.g. dispatch calls to wait, or semaphore
    while (!done)
        sleep(1);
    if (outFlags)
    {
        secdebug(XPROXYSCOPE, "%@ outFlags: %#llx", self, returnedFlags);
        *outFlags = returnedFlags;
    }
    return responses;
}

- (void)setParams:(NSDictionary *)paramsDict
{
    secdebug(XPROXYSCOPE, "%@ setParams: %@ ", self, paramsDict);
    NSString *cbmethod = [paramsDict objectForKey:(__bridge id)kParamCallbackMethod];
    if (!cbmethod)
        return;

    if ([cbmethod isEqualToString:(__bridge NSString *)kParamCallbackMethodSecurityd])
        callbackMethod = kCallbackMethodSecurityd;
    else if ([cbmethod isEqualToString:(__bridge NSString *)kParamCallbackMethodXPC])
        callbackMethod = kCallbackMethodXPC;
}

- (void)saveToUbiquitousStore
{
    [self requestSynchronization:NO];
}

// MARK: ----- Event Handling -----

- (void)streamEvent:(xpc_object_t)notification
{
#if (!TARGET_IPHONE_SIMULATOR)
    const char *notificationName = xpc_dictionary_get_string(notification, "Notification");
    if (!notificationName) {
    } else if (strcmp(notificationName, kUserKeybagStateChangeNotification)==0) {
        return [self keybagStateChange];
    } else if (strcmp(notificationName, kCloudKeychainStorechangeChangeNotification)==0) {
        return [self kvsStoreChange];
    } else if (strcmp(notificationName, kNotifyTokenForceUpdate)==0) {
        // DEBUG -- Possibly remove in future
        return [self processAllItems];
    }
    const char *eventName = xpc_dictionary_get_string(notification, "XPCEventName");
    char *desc = xpc_copy_description(notification);
    secerror("%@ event: %s name: %s desc: %s", self, eventName, notificationName, desc);
    if (desc)
        free((void *)desc);
#endif
}

- (void)iCloudAccountAvailabilityChanged:(NSNotification*)notification
{
    /*
        Continuing this example, you’d then implement an iCloudAccountAvailabilityChanged: method that would:

        Call the ubiquityIdentityToken method and store its return value.
        Compare the new value to the previous value, to find out if the user logged out of their account or 
        logged in to a different account. If the previously-used account is now unavailable, save the current 
        state locally as needed, empty your iCloud-related data caches, and refresh all iCloud-related user interface elements.
    */
    id previCloudToken = currentiCloudToken;
    currentiCloudToken = [[NSFileManager defaultManager] ubiquityIdentityToken];
    if (previCloudToken != currentiCloudToken)
        secnotice("event", "%@ iCloud account changed!", self);
    else
        secnotice("event", "%@ %@", self, notification);
}

- (void)cloudChanged:(NSNotification*)notification
{
    /*
        Posted when the value of one or more keys in the local key-value store
        changed due to incoming data pushed from iCloud. This notification is
        sent only upon a change received from iCloud; it is not sent when your
        app sets a value.

        The user info dictionary can contain the reason for the notification as
        well as a list of which values changed, as follows:

        The value of the NSUbiquitousKeyValueStoreChangeReasonKey key, when
        present, indicates why the key-value store changed. Its value is one of
        the constants in "Change Reason Values."
        
        The value of the NSUbiquitousKeyValueStoreChangedKeysKey, when present, 
        is an array of strings, each the name of a key whose value changed. The
        notification object is the NSUbiquitousKeyValueStore object whose contents
        changed.
     
        NSUbiquitousKeyValueStoreInitialSyncChange is only posted if there is any 
        local value that has been overwritten by a distant value. If there is no 
        conflict between the local and the distant values when doing the initial
        sync (e.g. if the cloud has no data stored or the client has not stored 
        any data yet), you'll never see that notification.
     
        NSUbiquitousKeyValueStoreInitialSyncChange implies an initial round trip
        with server but initial round trip with server does not imply 
        NSUbiquitousKeyValueStoreInitialSyncChange.
    */

    secdebug(XPROXYSCOPE, "%@ cloudChanged notification: %@", self, notification);

    NSDictionary *userInfo = [notification userInfo];
    NSNumber *reason = [userInfo objectForKey:NSUbiquitousKeyValueStoreChangeReasonKey];
    if (reason) switch ([reason integerValue]) {
        case NSUbiquitousKeyValueStoreInitialSyncChange:
        case NSUbiquitousKeyValueStoreServerChange:
        {
            _seenKVSStoreChange = YES;
            NSSet *keysChangedInCloud = [NSSet setWithArray:[userInfo objectForKey:NSUbiquitousKeyValueStoreChangedKeysKey]];
            NSSet *keysOfInterestThatChanged = [self filterKeySetWithLockState:keysChangedInCloud];
            NSMutableDictionary *changedValues = [self copyChangedValues:keysOfInterestThatChanged];
            if ([reason integerValue] == NSUbiquitousKeyValueStoreInitialSyncChange)
                changedValues[(__bridge NSString*)kSOSKVSInitialSyncKey] =  @"true";

            secnotice("event", "%@ keysChangedInCloud: %@ keysOfInterest: %@", self, [[keysChangedInCloud allObjects] componentsJoinedByString: @" "], [[changedValues allKeys] componentsJoinedByString: @" "]);
            if ([changedValues count])
                [self processKeyChangedEvent:changedValues];
            break;
        }
        case NSUbiquitousKeyValueStoreQuotaViolationChange:
            seccritical("%@ event received NSUbiquitousKeyValueStoreQuotaViolationChange", self);
            break;
        case NSUbiquitousKeyValueStoreAccountChange:
            // The primary account changed. We do not get this for password changes on the same account
            secnotice("event", "%@ NSUbiquitousKeyValueStoreAccountChange", self);
            if ([reason integerValue] == NSUbiquitousKeyValueStoreInitialSyncChange)
            {
                NSDictionary *changedValues = @{ (__bridge NSString*)kSOSKVSAccountChangedKey:  @"true" };
                [self processKeyChangedEvent:changedValues];
            }
            break;
    }
}

- (void) calloutWith: (void(^)(NSSet *pending, bool syncWithPeersPending, dispatch_queue_t queue, void(^done)(NSSet *handledKeys, bool handledSyncWithPeers))) callout
{
    // In CKDKVSProxy's serial queue
    NSSet *myPending = [_pendingKeys copy];
    bool mySyncWithPeersPending = _syncWithPeersPending;
    bool wasLocked = _isLocked;
    _inCallout = YES;
    _shadowPendingKeys = [NSMutableSet set];
    _shadowSyncWithPeersPending = NO;
    dispatch_async(dispatch_get_global_queue(DISPATCH_QUEUE_PRIORITY_DEFAULT, 0), ^{
        callout(myPending, mySyncWithPeersPending, dispatch_get_main_queue(), ^(NSSet *handledKeys, bool handledSyncWithPeers) {
            // In CKDKVSProxy's serial queue
            _inCallout = NO;

            // Update SyncWithPeers stuff.
            _syncWithPeersPending = (mySyncWithPeersPending && (!handledSyncWithPeers)) || _shadowSyncWithPeersPending;
            _shadowSyncWithPeersPending = NO;
            if (handledSyncWithPeers)
                _lastSyncTime = dispatch_time(DISPATCH_TIME_NOW, 0);

            // Update pendingKeys and handle them
            [_pendingKeys minusSet: handledKeys];
            bool hadShadowPendingKeys = [_shadowPendingKeys count];
            NSSet *filteredKeys = [self filterKeySetWithLockState:_shadowPendingKeys];
            _shadowPendingKeys = nil;

            // Write state to disk
            [self persistState];

            // Handle shadow pended stuff
            if (_syncWithPeersPending && !_isLocked)
                [self scheduleSyncRequestTimer];
            /* We don't want to call processKeyChangedEvent if we failed to
               handle pending keys and the device didn't unlock nor receive
               any kvs changes while we were in our callout.
               Doing so will lead to securityd and CloudKeychainProxy
               talking to each other forever in a tight loop if securityd
               repeatedly returns an error processing the same message.
               Instead we leave any old pending keys until the next event. */
            if (hadShadowPendingKeys || (!_isLocked && wasLocked))
                [self processKeyChangedEvent:[self copyChangedValues:filteredKeys]];
        });
    });
}

- (void) doSyncWithAllPeers
{
    [self calloutWith:^(NSSet *pending, bool syncWithPeersPending, dispatch_queue_t queue, void(^done)(NSSet *, bool)) {
        CFErrorRef error = NULL;
        SyncWithAllPeersReason reason = SOSCCProcessSyncWithAllPeers(&error);
        dispatch_async(queue, ^{
            bool handledSyncWithPeers = NO;
            if (reason == kSyncWithAllPeersSuccess) {
                handledSyncWithPeers = YES;
                secnotice("event", "%@ syncWithAllPeers succeeded", self);
            } else if (reason == kSyncWithAllPeersLocked) {
                secnotice("event", "%@ syncWithAllPeers attempted while locked - waiting for unlock", self);
                handledSyncWithPeers = YES;
            } else if (reason == kSyncWithAllPeersOtherFail) {
                // Pretend we handled syncWithPeers, by pushing out the _lastSyncTime
                // This will cause us to wait for kMinSyncInterval seconds before
                // retrying, so we don't spam securityd if sync is failing
                secerror("%@ syncWithAllPeers %@, rescheduling timer", self, error);
                _lastSyncTime = dispatch_time(DISPATCH_TIME_NOW, 0);
            } else {
                secerror("%@ syncWithAllPeers %@, unknown reason: %d", self, error, reason);
            }

            done(nil, handledSyncWithPeers);
            CFReleaseSafe(error);
        });
    }];
}

- (void)timerFired
{
    secnotice("event", "%@ syncWithPeersPending: %d inCallout: %d isLocked: %d", self, _syncWithPeersPending, _inCallout, _isLocked);
    _syncTimerScheduled = NO;
    if (_syncWithPeersPending && !_inCallout && !_isLocked)
        [self doSyncWithAllPeers];
}

- (dispatch_time_t) nextSyncTime
{
    dispatch_time_t nextSync = dispatch_time(DISPATCH_TIME_NOW, kMinSyncDelay);

    // Don't sync again unless we waited at least kMinSyncInterval
    if (_lastSyncTime) {
        dispatch_time_t soonest = dispatch_time(_lastSyncTime, kMinSyncInterval);
        if (nextSync < soonest || _deadline < soonest) {
            secdebug("timer", "%@ backing off", self);
            return soonest;
        }
    }

    // Don't delay more than kMaxSyncDelay after the first request.
    if (nextSync > _deadline) {
        secdebug("timer", "%@ hit deadline", self);
        return _deadline;
    }

    // Bump the timer by kMinSyncDelay
    if (_syncTimerScheduled)
        secdebug("timer", "%@ bumped timer", self);
    else
        secdebug("timer", "%@ scheduled timer", self);

    return nextSync;
}

- (void)scheduleSyncRequestTimer
{
    dispatch_source_set_timer(_syncTimer, [self nextSyncTime], DISPATCH_TIME_FOREVER, kSyncTimerLeeway);
    _syncTimerScheduled = YES;
}

- (void)requestSyncWithAllPeers // secd calling SOSCCSyncWithAllPeers invokes this
{
    secdebug("event", "%@ _syncWithPeersPending: %d _inCallout: %d _shadowSyncWithPeersPending: %d _isLocked: %d", self, _syncWithPeersPending, _inCallout, _shadowSyncWithPeersPending, _isLocked);

    if (!_syncWithPeersPending || (_inCallout && !_shadowSyncWithPeersPending))
        _deadline = dispatch_time(DISPATCH_TIME_NOW, kMaxSyncDelay);

    if (!_syncWithPeersPending) {
        _syncWithPeersPending = YES;
        [self persistState];
    }

    if (_inCallout)
        _shadowSyncWithPeersPending = YES;

    if (!_isLocked)
        [self scheduleSyncRequestTimer];
}

- (BOOL) updateUnlockedSinceBoot
{
    CFErrorRef aksError = NULL;
    if (!SecAKSGetHasBeenUnlocked(&_unlockedSinceBoot, &aksError)) {
        secerror("%@ Got error from SecAKSGetHasBeenUnlocked: %@", self, aksError);
        CFReleaseSafe(aksError);
        return NO;
    }
    return YES;
}

- (BOOL) updateIsLocked
{
    CFErrorRef aksError = NULL;
    if (!SecAKSGetIsLocked(&_isLocked, &aksError)) {
        secerror("%@ Got error querying lock state: %@", self, aksError);
        CFReleaseSafe(aksError);
        return NO;
    }
    if (!_isLocked)
        _unlockedSinceBoot = YES;
    return YES;
}

- (void) keybagStateChange
{
    BOOL wasLocked = _isLocked;
    if ([self updateIsLocked]) {
        if (wasLocked == _isLocked)
            secdebug("event", "%@ still %s ignoring", self, _isLocked ? "locked" : "unlocked");
        else if (_isLocked)
            [self keybagDidLock];
        else
            [self keybagDidUnlock];
    }
}

- (void) keybagDidLock
{
    secnotice("event", "%@", self);
}

- (void) keybagDidUnlock
{
    secnotice("event", "%@", self);
    // First send changed keys to securityd so it can proccess updates
    NSSet *filteredKeys = [self filterKeySetWithLockState:nil];
    [self processKeyChangedEvent:[self copyChangedValues:filteredKeys]];

    // Then, tickle securityd to perform a sync if needed.
    if (_syncWithPeersPending && !_syncTimerScheduled) {
        [self doSyncWithAllPeers];
    }
}

- (void) kvsStoreChange {
    if (!_seenKVSStoreChange) {
        _seenKVSStoreChange = YES; // Only do this once
        secnotice("event", "%@ received darwin notification before first NSNotification", self);
        // TODO This might not be needed if we always get the NSNotification
        // deleived even if we were launched due to a kvsStoreChange
        // Send all keys for current lock state to securityd so it can proccess them
        NSSet *filteredKeys = [self filterKeySetWithLockState:[self copyAllKeys]];
        [self processKeyChangedEvent:[self copyChangedValues:filteredKeys]];
    } else {
        secdebug("event", "%@ ignored, waiting for NSNotification", self);
    }
}

//
// MARK: ----- Key Filtering -----
//

- (NSSet*) keysForCurrentLockState
{
    secdebug("keytrace", "%@ Filtering: unlockedSinceBoot: %d\n unlocked: %d\n, _keysOfInterest: %@", self, (int) _unlockedSinceBoot, (int) !_isLocked, [self exportKeyInterests]);

    NSMutableSet *currentStateKeys = [NSMutableSet setWithSet: _alwaysKeys];
    if (_unlockedSinceBoot)
        [currentStateKeys unionSet: _firstUnlockKeys];

    if (!_isLocked)
        [currentStateKeys unionSet: _unlockedKeys];

    return currentStateKeys;
}

- (NSSet*) filterKeySetWithLockState: (NSSet*) startingSet
{
    NSSet* availableKeys = [self keysForCurrentLockState];
    NSSet *allKeys = [self copyAllKeys];
    if (_inCallout) {
        [_shadowPendingKeys unionSet:startingSet];
        [_shadowPendingKeys intersectSet:allKeys];
    }
    [_pendingKeys unionSet:startingSet];
    [_pendingKeys intersectSet:allKeys];

    NSMutableSet *filtered =[_pendingKeys mutableCopy];
    [filtered intersectSet:availableKeys];

    return filtered;
}

- (NSMutableDictionary *)copyChangedValues:(NSSet*)keysOfInterest
{
    // Grab values from KVS.
    NSUbiquitousKeyValueStore *store = [self cloudStore];
    NSMutableDictionary *changedValues = [NSMutableDictionary dictionaryWithCapacity:0];
    [keysOfInterest enumerateObjectsUsingBlock:^(id obj, BOOL *stop)
    {
        NSString* key = (NSString*) obj;
        id objval = [store objectForKey:key];
        if (!objval) objval = [NSNull null];

        [changedValues setObject:objval forKey:key];
        secdebug(XPROXYSCOPE, "%@ storeChanged updated value for %@", self, key);
    }];
    return changedValues;
}

/*
    During RegisterKeys, separate keys-of-interest into three disjoint sets:
    - keys that we always want to be notified about; this means we can get the
        value at any time
    - keys that require the device to have been unlocked at least once
    - keys that require the device to be unlocked now
    
    Typically, the sets of keys will be:
    
    - Dk: alwaysKeys
    - Ck: firstUnlock
    - Ak: unlocked
    
    The caller is responsible for making sure that the keys in e.g. alwaysKeys are
    values that can be handled at any time (that is, not when unlocked)

    Each time we get a notification from ubiquity that keys have changed, we need to
    see if anything of interest changed. If we don't care, then done.
    
    For each key-of-interest that changed, we either notify the client that things
    changed, or add it to a pendingNotifications list. If the notification to the
    client fails, also add it to the pendingNotifications list. This pending list
    should be written to persistent storage and consulted any time we either get an
    item changed notification, or get a stream event signalling a change in lock state.
    
    We can notify the client either through XPC if a connection is set up, or call a
    routine in securityd to launch it.
    
*/

- (void)processKeyChangedEvent:(NSDictionary *)changedValues
{
    NSMutableDictionary* filtered = [NSMutableDictionary dictionary];
    NSMutableArray* nullKeys = [NSMutableArray array];
    // Remove nulls because we don't want them in securityd.
    [changedValues enumerateKeysAndObjectsUsingBlock:^(id key, id obj, BOOL *stop) {
        if (obj == [NSNull null])
            [nullKeys addObject:key];
        else
            filtered[key] = obj;
    }];
    if ([filtered count]) {
        [self calloutWith:^(NSSet *pending, bool syncWithPeersPending, dispatch_queue_t queue, void(^done)(NSSet *, bool)) {
            CFErrorRef error = NULL;
            bool bx = [filtered count] && _SecKeychainSyncUpdate((__bridge CFDictionaryRef)filtered, &error);
            // TODO: Make SecKeychainSyncUpdate return handled keys, for now we
            // record that we handled everything when _SecKeychainSyncUpdate succeeds.
            NSSet* handledKeys = [NSSet setWithArray: bx ? [changedValues allKeys] : nullKeys];
            dispatch_async(queue, ^{
                done(handledKeys, NO);
                if (bx)
                    secnotice("keytrace", "%@ handled: %@ null: %@ pending: %@", self,
                              [[filtered allKeys] componentsJoinedByString: @" "],
                              [nullKeys componentsJoinedByString: @" "],
                              [[_pendingKeys allObjects] componentsJoinedByString: @" "]);
                else
                    secerror("%@ failed: %@ not handled: %@ null: %@ pending: %@", self, error,
                             [[filtered allKeys] componentsJoinedByString: @" "],
                             [nullKeys componentsJoinedByString: @" "],
                             [[_pendingKeys allObjects] componentsJoinedByString: @" "]);
                CFReleaseSafe(error);
            });
        }];
    } else {
        if ([nullKeys count])
            [_pendingKeys minusSet: [NSSet setWithArray: nullKeys]];

        secnotice("keytrace", "%@ handled: %@ null: %@ pending: %@", self,
                  [[filtered allKeys] componentsJoinedByString: @" "],
                  [nullKeys componentsJoinedByString: @" "],
                  [[_pendingKeys allObjects] componentsJoinedByString: @" "]);
    }
}

@end