No `channel_reestablish` before funding tx is confirmed

[pm47]

Exact scenario:

1. eclair opens a channel to lnd
2. eclair publishes the funding tx
3. shutdown and restart eclair
4. eclair reconnects to lnd, handshake successful, but no channel_reestablish is received

If we remove step 3), channel establishment goes fine, and subsequent disconnections/reconnections work without any problem.

@cdecker was able to reproduce with c-lightning funding the channel.

[Roasbeef]

See #457

In this case, were enough confirmations reached to send the FundingLocked?

[pm47]

No, we disconnect as soon as the channel is funded (frequent use case on the mobile app)

[Roasbeef]

I see. Atm we don't consider a channel "active" until the channel has received a sufficient number of confirmations. So from the PoV of the current code, it doesn't send channel_reestablish as the channel isn't yet active (no confs, no FundingLocked). This can be added to that PR I linked by loading a channel even if it's pending.

Looking at the spec, why would a node send the FundingLocked message if the channel hasn't yet reached a sufficient number of confirmations? That's contradictory...

[pm47]

Looking at the spec, why would a node send the FundingLocked message if the channel hasn't yet reached a sufficient number of confirmations? That's contradictory...

I don't see where the specs says that?

To be clear expected behavior in my scenario is that if I reconnect immediately I just receive a channel_reestablish, no funding_locked.

[Roasbeef]

See the fragment above I pasted. IMO it should be amended to say only send funding locked iff the channel has reached the num confs.

I'll amend that PR I sent above to also address this case (always send channel_reestablish even if the channel isn't open yet). Though IMO sending it does no purpose as neither sides can actually operate the channel yet.

[pm47]

IMO it should be amended to say only send funding locked iff the channel has reached the num confs.

Gotcha, agree!

Though IMO sending it does no purpose as neither sides can actually operate the channel yet.

I think channel_reestablish is related to the presence of commitments, not to the state of the channel. From that PoV it kind of makes sense to send channel_reestablish as soon as the first commitment has been exchanged.

[Roasbeef]

Test myself with that PR, can we'll now properly always send the chan sync message. Should also fix some issues users have reported when using the eclair app with lnd.