Skip to content

Fix key ratchet race condition during DAVE epoch transitions #5

New issue

Have a question about this project? Sign up for a free GitHub account to open an issue and contact its maintainers and the community.

Sign up for GitHub

By clicking “Sign up for GitHub”, you agree to our terms of service and privacy statement. We’ll occasionally send you account related emails.

Already on GitHub? Sign in to your account

Open
MohmmedAshraf wants to merge 2 commits into
base: master
Choose a base branch
from
Open

Fix key ratchet race condition during DAVE epoch transitions #5

Show file tree
Hide file tree
Changes from all commits
Commits
Show all changes
2 commits
Select commit Hold shift + click to select a range
745a318
Fix key ratchet race condition during DAVE epoch transitions
MohmmedAshraf Feb 23, 2026
8330512
Remove passthrough from prepareEpoch, add diagnostic logs for nil key…
MohmmedAshraf Feb 25, 2026
File filter

Filter by extension

Filter by extension
Conversations
Failed to load comments.
Loading
Jump to
Jump to file
Failed to load files.
Loading
Diff view
Diff view
24 changes: 22 additions & 2 deletions golibdave/golibdave.go
View file
Open in desktop
Original file line number Diff line number Diff line change
Expand Up @@ -192,6 +192,10 @@ func (s *session) prepareEpoch(epoch int, protocolVersion uint16) {
return
}

s.logger.Warn("prepareEpoch: resetting MLS session via Init",
slog.Int("epoch", epoch),
slog.Int("protocol_version", int(protocolVersion)),
)
s.session.Init(protocolVersion, uint64(s.channelID), string(s.selfUserID))
}

Expand Down Expand Up @@ -228,17 +232,33 @@ func (s *session) setupKeyRatchetForUser(userID godave.UserID, protocolVersion u
disabled := protocolVersion == disabledProtocolVersion

if userID == s.selfUserID {
kr := s.session.GetKeyRatchet(string(userID))
if !disabled && kr == nil {
s.logger.Warn("nil key ratchet for self after GetKeyRatchet",
slog.String("user_id", string(userID)),
slog.Int("protocol_version", int(protocolVersion)),
)
return
}
Comment on lines +235 to +242
Copy link
Copy Markdown
Contributor

@davfsa davfsa Feb 25, 2026

Choose a reason for hiding this comment

The reason will be displayed to describe this comment to others. Learn more.

This will never happen. If it did, we would be getting crashes everywhere due to newKeyRatchet.

Copy link
Copy Markdown
Author

@MohmmedAshraf MohmmedAshraf Feb 25, 2026

Choose a reason for hiding this comment

The reason will be displayed to describe this comment to others. Learn more.

that's literally how I found the bug lol. my bot was crashing nonstop with ErrMissingKeyRatchet every time someone joined/left a voice channel until I traced it back to this.

Copy link
Copy Markdown
Contributor

@davfsa davfsa Feb 25, 2026

Choose a reason for hiding this comment

The reason will be displayed to describe this comment to others. Learn more.

that's literally how I found the bug lol. my bot was crashing nonstop with ErrMissingKeyRatchet every time someone joined/left a voice channel until I traced it back to this.

That isn't a crash, thats just a warning/error raised by the underlying library.

I will take a look when I find some time, but thank you for raising this issue. I am bit skeptical on changing the current behaviour because this is a very finiky system and I don't want to break it when DAVE fully rolls out and it breaks because we are always sending unencrypted packets / being unable to decrypt any packages correctly

Copy link
Copy Markdown
Author

@MohmmedAshraf MohmmedAshraf Feb 25, 2026

Choose a reason for hiding this comment

The reason will be displayed to describe this comment to others. Learn more.

@davfsa honestly I'm glad you're pushing back, I'm not a Go developer so having someone who actually knows the internals review this properly is exactly what I need. switching from discordgo to disgo was the right move.

no rush, appreciate it 👍

s.encryptor.SetPassthroughMode(disabled)
if !disabled {
s.encryptor.SetKeyRatchet(s.session.GetKeyRatchet(string(userID)))
s.encryptor.SetKeyRatchet(kr)
}
return
}

decryptor := s.decryptors[userID]
kr := s.session.GetKeyRatchet(string(userID))
if !disabled && kr == nil {
s.logger.Warn("nil key ratchet for user after GetKeyRatchet",
slog.String("user_id", string(userID)),
slog.Int("protocol_version", int(protocolVersion)),
)
return
}
Comment on lines +251 to +258
Copy link
Copy Markdown
Contributor

@davfsa davfsa Feb 25, 2026

Choose a reason for hiding this comment

The reason will be displayed to describe this comment to others. Learn more.

Ditto the above

decryptor.TransitionToPassthroughMode(disabled)
if !disabled {
decryptor.TransitionToKeyRatchet(s.session.GetKeyRatchet(string(userID)))
decryptor.TransitionToKeyRatchet(kr)
}
}

Expand Down
4 changes: 4 additions & 0 deletions libdave/key_ratchet.go
View file
Open in desktop
Original file line number Diff line number Diff line change
Expand Up @@ -11,6 +11,10 @@ type KeyRatchet struct {
}

func newKeyRatchet(handle keyRatchetHandle) *KeyRatchet {
if handle == nil {
return nil
}

keyRatchet := &KeyRatchet{handle: handle}

runtime.SetFinalizer(keyRatchet, func(k *KeyRatchet) {
Expand Down