signalapp/Signal-iOS
signalapp/Signal-iOS
1
0
Fork 0
Code Issues Pull Requests Actions 1 Packages Projects Releases 4 Wiki Activity

Add kill switch for automatic session reset

Browse Source
This commit is contained in:
Nora Trapp 2021-01-16 11:25:23 -08:00
parent 9bffa761be
commit 449b596e95
2 changed files with 94 additions and 22 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

100
SignalServiceKit/src/Messages/OWSMessageDecrypter.m
View File

@ -82,7 +82,7 @@ NSError *EnsureDecryptError(NSError *_Nullable error, NSString *fallbackErrorDes
@interface OWSMessageDecrypter ()
@property (atomic, readonly) NSMutableSet<NSString *> *recentlyResetSenderIds;
@property (atomic, readonly) NSMutableSet<NSString *> *senderIdsResetDuringCurrentBatch;
@end
@ -98,7 +98,7 @@ NSError *EnsureDecryptError(NSError *_Nullable error, NSString *fallbackErrorDes
OWSSingletonAssert();
_recentlyResetSenderIds = [NSMutableSet new];
_senderIdsResetDuringCurrentBatch = [NSMutableSet new];
[[NSNotificationCenter defaultCenter] addObserver:self
selector:@selector(messageDecryptJobQueueDidFlush)
@ -170,6 +170,11 @@ NSError *EnsureDecryptError(NSError *_Nullable error, NSString *fallbackErrorDes
return SSKEnvironment.shared.messageProcessing;
}
- (SDSKeyValueStore *)keyValueStore
{
return [[SDSKeyValueStore alloc] initWithCollection:@"OWSMessageDecrypter"];
}
#pragma mark - Blocking
- (BOOL)isEnvelopeSenderBlocked:(SSKProtoEnvelope *)envelope
@ -193,7 +198,7 @@ NSError *EnsureDecryptError(NSError *_Nullable error, NSString *fallbackErrorDes
// We clear all recently reset sender ids any time the
// decryption queue has drained, so that any new messages
// that fail to decrypt will reset the session again.
[self.recentlyResetSenderIds removeAllObjects];
[self.senderIdsResetDuringCurrentBatch removeAllObjects];
}
- (void)decryptEnvelope:(SSKProtoEnvelope *)envelope
@ -723,29 +728,80 @@ NSError *EnsureDecryptError(NSError *_Nullable error, NSString *fallbackErrorDes
// reset IDs is cleared.
NSString *senderId = [NSString stringWithFormat:@"%@.%d", envelope.sourceUuid, envelope.sourceDevice];
if (![self.recentlyResetSenderIds containsObject:senderId]) {
OWSLogWarn(@"Resetting session for undecryptable message from %@", senderId);
[self.recentlyResetSenderIds addObject:senderId];
BOOL hasResetDuringThisBatch = [self.senderIdsResetDuringCurrentBatch containsObject:senderId];
// We only ever want to archive sessions outside of a given "batch"
// of message decryption. In practice, this means we:
// 1. Only archive at max once per sender while draining the initial
// queue after establishing the websocket connection, until we
// receive the empty response.
// 2. Only archive once if we get a quick burst of messages that
// cannot decrypt in the decryption queue while the app is running.
//
// Outside of these cases, we *always* archive your current session
// when we encounter a decryption error, so that your next message
// send to that device should send a prekey message and establish
// a new, healthy, session.
if (!hasResetDuringThisBatch) {
[self.senderIdsResetDuringCurrentBatch addObject:senderId];
OWSLogWarn(@"Archiving session for undecryptable message from %@", senderId);
[self.sessionStore archiveSessionForAddress:envelope.sourceAddress
deviceId:envelope.sourceDevice
transaction:transaction];
OWSOutgoingNullMessage *nullMessage =
[[OWSOutgoingNullMessage alloc] initWithContactThread:contactThread];
[self.messageSender sendMessage:nullMessage.asPreparer
success:^{
OWSLogInfo(
@"Successfully sent null message after session reset for undecryptable message from %@",
senderId);
}
failure:^(NSError *error) {
OWSFailDebug(
@"Failed to send null message after session reset for undecryptable message from %@ (%@)",
senderId,
error.localizedDescription);
}];
}
errorMessage = [TSErrorMessage sessionRefreshWithEnvelope:envelope withTransaction:transaction];
// Always notify the user that we have performed an automatic archive.
errorMessage = [TSErrorMessage sessionRefreshWithEnvelope:envelope withTransaction:transaction];
NSDate *_Nullable lastNullMessageDate = [self.keyValueStore getDate:senderId transaction:transaction];
BOOL hasRecentlySentNullMessage = NO;
if (lastNullMessageDate) {
hasRecentlySentNullMessage = fabs([lastNullMessageDate timeIntervalSinceNow])
<= RemoteConfig.automaticSessionResetAttemptInterval;
}
// In order to quickly get both devices into a healthy state, we
// try and send a null message immediately to establish the new
// session. However, we only do this at max once per a given time
// interval so in the case the other client is continually
// responding to our message with another message we can't decrypt,
// we don't get in a loop where we keep responding to them.
// In general, this should never happen because the other
// client should be able to decrypt a prekey message.
if (RemoteConfig.automaticSessionResetKillSwitch) {
OWSLogWarn(
@"Skipping null message after undecryptable message from %@ due to kill switch.", senderId);
} else if (hasRecentlySentNullMessage) {
OWSLogWarn(
@"Skipping null message after undecryptable message from %@, last null message sent %llu",
senderId,
[lastNullMessageDate ows_millisecondsSince1970]);
} else {
OWSLogInfo(@"Sending null message to reset session after undecryptable message from: %@", senderId);
[self.keyValueStore setDate:[NSDate new] key:senderId transaction:transaction];
OWSOutgoingNullMessage *nullMessage =
[[OWSOutgoingNullMessage alloc] initWithContactThread:contactThread];
[self.messageSender sendMessage:nullMessage.asPreparer
success:^{
OWSLogInfo(
@"Successfully sent null message after session reset for undecryptable message from %@",
senderId);
}
failure:^(NSError *error) {
OWSFailDebug(@"Failed to send null message after session reset for undecryptable message "
@"from %@ (%@)",
senderId,
error.localizedDescription);
}];
}
} else {
OWSLogWarn(@"Skipping session reset for undecryptable message from %@, already reset during this batch",
senderId);
}
} else {
OWSFailDebug(@"Received envelope missing UUID %@.%d", envelope.sourceAddress, envelope.sourceDevice);
errorMessage = [TSErrorMessage corruptedMessageWithEnvelope:envelope withTransaction:transaction];

16
SignalServiceKit/src/Util/RemoteConfigManager.swift
View File

@ -148,6 +148,20 @@ public class RemoteConfig: BaseFlags {
return cdsSyncInterval
}
@objc
public static var automaticSessionResetKillSwitch: Bool {
return isEnabled(.automaticSessionResetKillSwitch)
}
@objc
public static var automaticSessionResetAttemptInterval: TimeInterval {
guard let automaticSessionResetAttemptIntervalString: String = value(.automaticSessionResetAttemptInterval),
let automaticSessionResetAttemptInterval = TimeInterval(automaticSessionResetAttemptIntervalString) else {
return kHourInterval
}
return automaticSessionResetAttemptInterval
}
@objc
public static var researchMegaphone: Bool {
guard let remoteConfig = SSKEnvironment.shared.remoteConfigManager.cachedConfig else { return false }
@ -330,6 +344,7 @@ private struct Flags {
case groupsV2manualMigrations
case groupsV2blockingMigrations
case groupCallingKillSwitch
case automaticSessionResetKillSwitch
}
// Values defined in this array remain set once they are
@ -349,6 +364,7 @@ private struct Flags {
case clientExpiration
case researchMegaphone
case cdsSyncInterval
case automaticSessionResetAttemptInterval
}
}