Merge branch 'develop' into valere/swiftify_decryption_tracker

Riot/Modules/Analytics/DecryptionFailureTracker.m

@@ -0,0 +1,174 @@
+/*
+ Copyright 2018 New Vector Ltd
+
+ 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
+
+ http://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 "DecryptionFailureTracker.h"
+#import "GeneratedInterface-Swift.h"
+
+
+// Call `checkFailures` every `CHECK_INTERVAL`
+#define CHECK_INTERVAL 10
+
+// Give events a chance to be decrypted by waiting `GRACE_PERIOD` before counting
+// and reporting them as failures
+#define GRACE_PERIOD 30
+
+// E2E failures analytics category.
+NSString *const kDecryptionFailureTrackerAnalyticsCategory = @"e2e.failure";
+
+@interface DecryptionFailureTracker()
+{
+    // Reported failures
+    // Every `CHECK_INTERVAL`, this list is checked for failures that happened
+    // more than`GRACE_PERIOD` ago. Those that did are reported to the delegate.
+    NSMutableDictionary<NSString* /* eventId */, DecryptionFailure*> *reportedFailures;
+
+    // Event ids of failures that were tracked previously
+    NSMutableSet<NSString*> *trackedEvents;
+
+    // Timer for periodic check
+    NSTimer *checkFailuresTimer;
+}
+@end
+
+@implementation DecryptionFailureTracker
+
++ (instancetype)sharedInstance
+{
+    static DecryptionFailureTracker *sharedInstance = nil;
+    static dispatch_once_t onceToken;
+
+    dispatch_once(&onceToken, ^{
+        sharedInstance = [[DecryptionFailureTracker alloc] init];
+    });
+
+    return sharedInstance;
+}
+
+- (instancetype)init
+{
+    self = [super init];
+    if (self)
+    {
+        reportedFailures = [NSMutableDictionary dictionary];
+        trackedEvents = [NSMutableSet set];
+
+        [[NSNotificationCenter defaultCenter] addObserver:self selector:@selector(eventDidDecrypt:) name:kMXEventDidDecryptNotification object:nil];
+
+        checkFailuresTimer = [NSTimer scheduledTimerWithTimeInterval:CHECK_INTERVAL
+                                         target:self
+                                       selector:@selector(checkFailures)
+                                       userInfo:nil
+                                        repeats:YES];
+    }
+    return self;
+}
+
+- (void)reportUnableToDecryptErrorForEvent:(MXEvent *)event withRoomState:(MXRoomState *)roomState myUser:(NSString *)userId
+{
+    if (reportedFailures[event.eventId] || [trackedEvents containsObject:event.eventId])
+    {
+        return;
+    }
+
+    // Filter out "expected" UTDs
+    // We cannot decrypt messages sent before the user joined the room
+    MXRoomMember *myUser = [roomState.members memberWithUserId:userId];
+    if (!myUser || myUser.membership != MXMembershipJoin)
+    {
+        return;
+    }
+
+    NSString *failedEventId = event.eventId;
+    DecryptionFailureReason reason;
+
+    // Categorise the error
+    switch (event.decryptionError.code)
+    {
+        case MXDecryptingErrorUnknownInboundSessionIdCode:
+            reason = DecryptionFailureReasonOlmKeysNotSent;
+            break;
+
+        case MXDecryptingErrorOlmCode:
+            reason = DecryptionFailureReasonOlmIndexError;
+            break;
+
+        default:
+            // All other error codes will be tracked as `OlmUnspecifiedError` and will include `context` containing
+            // the actual error code and localized description
+            reason = DecryptionFailureReasonUnspecified;
+            break;
+    }
+
+    NSString *context = [NSString stringWithFormat:@"code: %ld, description: %@", event.decryptionError.code, event.decryptionError.localizedDescription];
+    reportedFailures[event.eventId] = [[DecryptionFailure alloc] initWithFailedEventId:failedEventId
+                                                                                reason:reason
+                                                                               context:context];
+}
+
+- (void)dispatch
+{
+    [self checkFailures];
+}
+
+#pragma mark - Private methods
+
+/**
+ Mark reported failures that occured before tsNow - GRACE_PERIOD as failures that should be
+ tracked.
+ */
+- (void)checkFailures
+{
+    if (!_delegate)
+    {
+        return;
+    }
+    
+    NSTimeInterval tsNow = [NSDate date].timeIntervalSince1970;
+
+    NSMutableArray *failuresToTrack = [NSMutableArray array];
+
+    for (DecryptionFailure *reportedFailure in reportedFailures.allValues)
+    {
+        if (reportedFailure.ts < tsNow - GRACE_PERIOD)
+        {
+            [failuresToTrack addObject:reportedFailure];
+            [reportedFailures removeObjectForKey:reportedFailure.failedEventId];
+            [trackedEvents addObject:reportedFailure.failedEventId];
+        }
+    }
+
+    if (failuresToTrack.count)
+    {
+        // Sort failures by error reason
+        NSMutableDictionary<NSNumber*, NSNumber*> *failuresCounts = [NSMutableDictionary dictionary];
+        for (DecryptionFailure *failure in failuresToTrack)
+        {
+            failuresCounts[@(failure.reason)] = @(failuresCounts[@(failure.reason)].unsignedIntegerValue + 1);
+            [self.delegate trackE2EEError:failure.reason context:failure.context];
+        }
+
+        MXLogDebug(@"[DecryptionFailureTracker] trackFailures: %@", failuresCounts);
+    }
+}
+
+- (void)eventDidDecrypt:(NSNotification *)notif
+{
+    // Could be an event in the reportedFailures, remove it
+    MXEvent *event = notif.object;
+    [reportedFailures removeObjectForKey:event.eventId];
+}
+
+@end