Signal-iOS/SignalServiceKit/src/Account/TSPreKeyManager.m
2021-03-25 09:24:27 -03:00

398 lines
15 KiB
Objective-C

//
// Copyright (c) 2021 Open Whisper Systems. All rights reserved.
//
#import "TSPreKeyManager.h"
#import "AppContext.h"
#import "NSURLSessionDataTask+OWS_HTTP.h"
#import "OWSIdentityManager.h"
#import "SSKEnvironment.h"
#import "SSKSignedPreKeyStore.h"
#import "TSNetworkManager.h"
#import <SignalCoreKit/NSDate+OWS.h>
#import <SignalServiceKit/SSKPreKeyStore.h>
#import <SignalServiceKit/SignalServiceKit-Swift.h>
#import <SignalServiceKit/SignedPreKeyRecord.h>
NS_ASSUME_NONNULL_BEGIN
// Time before deletion of signed prekeys (measured in seconds)
#define kSignedPreKeysDeletionTime (30 * kDayInterval)
// Time before rotation of signed prekeys (measured in seconds)
#define kSignedPreKeyRotationTime (2 * kDayInterval)
// How often we check prekey state on app activation.
#define kPreKeyCheckFrequencySeconds (12 * kHourInterval)
// Maximum number of failures while updating signed prekeys
// before the message sending is disabled.
static const NSUInteger kMaxPrekeyUpdateFailureCount = 5;
// Maximum amount of time that can elapse without updating signed prekeys
// before the message sending is disabled.
#define kSignedPreKeyUpdateFailureMaxFailureDuration (10 * kDayInterval)
#pragma mark -
@interface TSPreKeyManager ()
@property (atomic, nullable) NSDate *lastPreKeyCheckTimestamp;
@end
#pragma mark -
@implementation TSPreKeyManager
+ (instancetype)shared
{
static TSPreKeyManager *instance = nil;
static dispatch_once_t onceToken;
dispatch_once(&onceToken, ^{
instance = [self new];
});
return instance;
}
#pragma mark - State Tracking
+ (BOOL)isAppLockedDueToPreKeyUpdateFailures
{
// PERF TODO use a single transaction / take in a transaction
// Only disable message sending if we have failed more than N times
// over a period of at least M days.
return ([self.signedPreKeyStore prekeyUpdateFailureCount] >= kMaxPrekeyUpdateFailureCount &&
[self.signedPreKeyStore firstPrekeyUpdateFailureDate] != nil
&& fabs([[self.signedPreKeyStore firstPrekeyUpdateFailureDate] timeIntervalSinceNow])
>= kSignedPreKeyUpdateFailureMaxFailureDuration);
}
+ (void)incrementPreKeyUpdateFailureCount
{
// PERF TODO use a single transaction / take in a transaction
// Record a prekey update failure.
NSInteger failureCount = [self.signedPreKeyStore incrementPrekeyUpdateFailureCount];
OWSLogInfo(@"new failureCount: %ld", (unsigned long)failureCount);
if (failureCount == 1 || ![self.signedPreKeyStore firstPrekeyUpdateFailureDate]) {
// If this is the "first" failure, record the timestamp of that
// failure.
[self.signedPreKeyStore setFirstPrekeyUpdateFailureDate:[NSDate new]];
}
}
+ (void)clearPreKeyUpdateFailureCount
{
[self.signedPreKeyStore clearFirstPrekeyUpdateFailureDate];
[self.signedPreKeyStore clearPrekeyUpdateFailureCount];
}
+ (void)refreshPreKeysDidSucceed
{
TSPreKeyManager.shared.lastPreKeyCheckTimestamp = [NSDate new];
}
#pragma mark - Check/Request Initiation
+ (NSOperationQueue *)operationQueue
{
static dispatch_once_t onceToken;
static NSOperationQueue *operationQueue;
// PreKey state lives in two places - on the client and on the service.
// Some of our pre-key operations depend on the service state, e.g. we need to check our one-time-prekey count
// before we decide to upload new ones. This potentially entails multiple async operations, all of which should
// complete before starting any other pre-key operation. That's why a dispatch_queue is insufficient for
// coordinating PreKey operations and instead we use NSOperation's on a serial NSOperationQueue.
dispatch_once(&onceToken, ^{
operationQueue = [NSOperationQueue new];
operationQueue.name = @"TSPreKeyManager";
operationQueue.maxConcurrentOperationCount = 1;
});
return operationQueue;
}
+ (void)checkPreKeysIfNecessary
{
[self checkPreKeysWithShouldThrottle:YES];
}
#if TESTABLE_BUILD
+ (void)checkPreKeysImmediately
{
[self checkPreKeysWithShouldThrottle:NO];
}
#endif
+ (void)checkPreKeysWithShouldThrottle:(BOOL)shouldThrottle
{
if (!CurrentAppContext().isMainAppAndActive) {
return;
}
if (!self.tsAccountManager.isRegisteredAndReady) {
return;
}
// Order matters here - if we rotated *before* refreshing, we'd risk uploading
// two SPK's in a row since RefreshPreKeysOperation can also upload a new SPK.
NSMutableArray<NSOperation *> *operations = [NSMutableArray new];
// Don't rotate or clean up prekeys until all incoming messages
// have been drained, decrypted and processed.
MessageProcessingOperation *messageProcessingOperation = [MessageProcessingOperation new];
[operations addObject:messageProcessingOperation];
SSKRefreshPreKeysOperation *refreshOperation = [SSKRefreshPreKeysOperation new];
if (shouldThrottle) {
__weak SSKRefreshPreKeysOperation *weakRefreshOperation = refreshOperation;
NSBlockOperation *checkIfRefreshNecessaryOperation = [NSBlockOperation blockOperationWithBlock:^{
NSDate *_Nullable lastPreKeyCheckTimestamp = TSPreKeyManager.shared.lastPreKeyCheckTimestamp;
BOOL shouldCheck = (lastPreKeyCheckTimestamp == nil
|| fabs([lastPreKeyCheckTimestamp timeIntervalSinceNow]) >= kPreKeyCheckFrequencySeconds);
if (!shouldCheck) {
[weakRefreshOperation cancel];
}
}];
[operations addObject:checkIfRefreshNecessaryOperation];
}
[operations addObject:refreshOperation];
SSKRotateSignedPreKeyOperation *rotationOperation = [SSKRotateSignedPreKeyOperation new];
if (shouldThrottle) {
__weak SSKRotateSignedPreKeyOperation *weakRotationOperation = rotationOperation;
NSBlockOperation *checkIfRotationNecessaryOperation = [NSBlockOperation blockOperationWithBlock:^{
SignedPreKeyRecord *_Nullable signedPreKey = [self.signedPreKeyStore currentSignedPreKey];
BOOL shouldCheck
= !signedPreKey || fabs(signedPreKey.generatedAt.timeIntervalSinceNow) >= kSignedPreKeyRotationTime;
if (!shouldCheck) {
[weakRotationOperation cancel];
}
}];
[operations addObject:checkIfRotationNecessaryOperation];
}
[operations addObject:rotationOperation];
// Set up dependencies; we want to perform these operations serially.
NSOperation *_Nullable lastOperation;
for (NSOperation *operation in operations) {
if (lastOperation != nil) {
[operation addDependency:lastOperation];
}
lastOperation = operation;
}
[self.operationQueue addOperations:operations waitUntilFinished:NO];
}
+ (void)createPreKeysWithSuccess:(void (^)(void))successHandler failure:(void (^)(NSError *error))failureHandler
{
OWSAssertDebug(!self.tsAccountManager.isRegisteredAndReady);
dispatch_async(dispatch_get_global_queue(DISPATCH_QUEUE_PRIORITY_DEFAULT, 0), ^{
SSKCreatePreKeysOperation *operation = [SSKCreatePreKeysOperation new];
[self.operationQueue addOperations:@[ operation ] waitUntilFinished:YES];
NSError *_Nullable error = operation.failingError;
if (error) {
dispatch_async(dispatch_get_main_queue(), ^{
failureHandler(error);
});
} else {
dispatch_async(dispatch_get_main_queue(), ^{
successHandler();
});
}
});
}
+ (void)rotateSignedPreKeyWithSuccess:(void (^)(void))successHandler failure:(void (^)(NSError *error))failureHandler
{
OWSAssertDebug(self.tsAccountManager.isRegisteredAndReady);
dispatch_async(dispatch_get_global_queue(DISPATCH_QUEUE_PRIORITY_DEFAULT, 0), ^{
SSKRotateSignedPreKeyOperation *operation = [SSKRotateSignedPreKeyOperation new];
[self.operationQueue addOperations:@[ operation ] waitUntilFinished:YES];
NSError *_Nullable error = operation.failingError;
if (error) {
dispatch_async(dispatch_get_main_queue(), ^{
failureHandler(error);
});
} else {
dispatch_async(dispatch_get_main_queue(), ^{
successHandler();
});
}
});
}
+ (void)clearSignedPreKeyRecords {
NSNumber *_Nullable currentSignedPrekeyId = [self.signedPreKeyStore currentSignedPrekeyId];
[self clearSignedPreKeyRecordsWithKeyId:currentSignedPrekeyId];
}
+ (void)clearSignedPreKeyRecordsWithKeyId:(NSNumber *_Nullable)keyId
{
if (!keyId) {
// currentSignedPreKeyId should only be nil before we've completed registration.
// We have this guard here for robustness, but we should never get here.
OWSFailDebug(@"Ignoring request to clear signed preKeys since no keyId was specified");
return;
}
__block SignedPreKeyRecord *_Nullable currentRecord;
__block NSArray *allSignedPrekeys;
[self.databaseStorage readWithBlock:^(SDSAnyReadTransaction *transaction) {
currentRecord = [self.signedPreKeyStore loadSignedPreKey:keyId.intValue transaction:transaction];
allSignedPrekeys = [self.signedPreKeyStore loadSignedPreKeysWithTransaction:transaction];
}];
if (!currentRecord) {
OWSFailDebug(@"Couldn't find signed prekey for id: %@", keyId);
return;
}
NSArray *oldSignedPrekeys
= (currentRecord != nil ? [self removeCurrentRecord:currentRecord fromRecords:allSignedPrekeys]
: allSignedPrekeys);
// Sort the signed prekeys in ascending order of generation time.
oldSignedPrekeys = [oldSignedPrekeys sortedArrayUsingComparator:^NSComparisonResult(
SignedPreKeyRecord *left, SignedPreKeyRecord *right) { return [left.generatedAt compare:right.generatedAt]; }];
NSUInteger oldSignedPreKeyCount = oldSignedPrekeys.count;
int oldAcceptedSignedPreKeyCount = 0;
for (SignedPreKeyRecord *signedPrekey in oldSignedPrekeys) {
if (signedPrekey.wasAcceptedByService) {
oldAcceptedSignedPreKeyCount++;
}
}
OWSLogInfo(@"oldSignedPreKeyCount: %lu., oldAcceptedSignedPreKeyCount: %lu",
(unsigned long)oldSignedPreKeyCount,
(unsigned long)oldAcceptedSignedPreKeyCount);
// Iterate the signed prekeys in ascending order so that we try to delete older keys first.
for (SignedPreKeyRecord *signedPrekey in oldSignedPrekeys) {
OWSLogInfo(@"Considering signed prekey id: %lu., generatedAt: %@, createdAt: %@, wasAcceptedByService: %d",
(unsigned long)signedPrekey.Id,
[self formatDate:signedPrekey.generatedAt],
[self formatDate:signedPrekey.createdAt],
signedPrekey.wasAcceptedByService);
// Always keep at least 3 keys, accepted or otherwise.
if (oldSignedPreKeyCount <= 3) {
break;
}
// Never delete signed prekeys until they are N days old.
if (fabs([signedPrekey.generatedAt timeIntervalSinceNow]) < kSignedPreKeysDeletionTime) {
break;
}
// We try to keep a minimum of 3 "old, accepted" signed prekeys.
if (signedPrekey.wasAcceptedByService) {
if (oldAcceptedSignedPreKeyCount <= 3) {
break;
} else {
oldAcceptedSignedPreKeyCount--;
}
}
if (signedPrekey.wasAcceptedByService) {
OWSProdInfo([OWSAnalyticsEvents prekeysDeletedOldAcceptedSignedPrekey]);
} else {
OWSProdInfo([OWSAnalyticsEvents prekeysDeletedOldUnacceptedSignedPrekey]);
}
oldSignedPreKeyCount--;
DatabaseStorageWrite(self.databaseStorage, ^(SDSAnyWriteTransaction *transaction) {
[self.signedPreKeyStore removeSignedPreKey:signedPrekey.Id transaction:transaction];
});
}
}
+ (void)cullPreKeyRecords {
NSTimeInterval expirationInterval = kDayInterval * 30;
DatabaseStorageWrite(self.databaseStorage, ^(SDSAnyWriteTransaction *transaction) {
NSMutableArray<NSString *> *keys = [[self.preKeyStore.keyStore allKeysWithTransaction:transaction] mutableCopy];
NSMutableSet<NSString *> *keysToRemove = [NSMutableSet new];
[Batching loopObjcWithBatchSize:Batching.kDefaultBatchSize
loopBlock:^(BOOL *stop) {
NSString *_Nullable key = [keys lastObject];
if (key == nil) {
*stop = YES;
return;
}
[keys removeLastObject];
PreKeyRecord *_Nullable record =
[self.preKeyStore.keyStore getObjectForKey:key transaction:transaction];
if (![record isKindOfClass:[PreKeyRecord class]]) {
OWSFailDebug(@"Unexpected value: %@", [record class]);
return;
}
if (record.createdAt == nil) {
OWSFailDebug(@"Missing createdAt.");
[keysToRemove addObject:key];
return;
}
BOOL shouldRemove = fabs(record.createdAt.timeIntervalSinceNow) > expirationInterval;
if (shouldRemove) {
OWSLogInfo(@"Removing prekey id: %lu., createdAt: %@",
(unsigned long)record.Id,
[self formatDate:record.createdAt]);
[keysToRemove addObject:key];
}
}];
if (keysToRemove.count < 1) {
return;
}
OWSLogInfo(@"Culling prekeys: %lu", (unsigned long) keysToRemove.count);
for (NSString *key in keysToRemove) {
[self.preKeyStore.keyStore removeValueForKey:key
transaction:transaction];
}
});
}
+ (NSArray *)removeCurrentRecord:(SignedPreKeyRecord *)currentRecord fromRecords:(NSArray *)allRecords {
NSMutableArray *oldRecords = [NSMutableArray array];
for (SignedPreKeyRecord *record in allRecords) {
if (currentRecord.Id != record.Id) {
[oldRecords addObject:record];
}
}
return oldRecords;
}
+ (NSString *)formatDate:(nullable NSDate *)date
{
return (date != nil ? [self.dateFormatter stringFromDate:date] : @"Unknown");
}
+ (NSDateFormatter *)dateFormatter
{
static NSDateFormatter *formatter;
static dispatch_once_t onceToken;
dispatch_once(&onceToken, ^{
formatter = [NSDateFormatter new];
[formatter setLocale:[NSLocale currentLocale]];
[formatter setTimeStyle:NSDateFormatterShortStyle];
[formatter setDateStyle:NSDateFormatterShortStyle];
});
return formatter;
}
@end
NS_ASSUME_NONNULL_END