Funding Tx finalized for channel in AWAITING_UNILATERAL status

[theRescuer]

Issue and Steps to Reproduce

I've executed a funding transactions to establish a channel with peer 0234227bdcd0361622f39447f961618480e7347ab1cfe6e74f561b976135343b31
The transaction has remained "unconfirmed" in the mempool (due to low fee rates)for several days .
Today, eventually it went through.
In the meantime the request for channel moved to AWAITING_UNILATERAL state

state_changes:
          - timestamp: '2021-04-27T12:29:48.672Z'
            old_state: CHANNELD_AWAITING_LOCKIN
            new_state: AWAITING_UNILATERAL
            cause: protocol
            message: >-
              channeld: received ERROR channel
              ae169b356c7eeb905ea6b0d6e705be8626209e0aac5a315cb80400288d143098:
              funding failed due to internal error
        status:
          - 'AWAITING_UNILATERAL:Attempting to reconnect'
        in_payments_offered: 0
        in_msatoshi_offered: 0
        in_offered_msat: 0msat
        in_payments_fulfilled: 0
        in_msatoshi_fulfilled: 0
        in_fulfilled_msat: 0msat
        out_payments_offered: 0
        out_msatoshi_offered: 0
        out_offered_msat: 0msat
        out_payments_fulfilled: 0
        out_msatoshi_fulfilled: 0
        out_fulfilled_msat: 0msat
        htlcs: []

listpeers with debug parameter shows

log: >-
          Funding tx
          9830148d280004b85c315aac0a9e202686be05e7d6b0a65e90eb7e6c359b16ae
          confirmed, but peer disconnected

I do not understand why the request for closure was raised.
Any suggestion on how to get the funds back (even enforcing a real unilateral channel closure if no other option is available)

getinfo output

id: 023808f558a644d786cb9071ea22f2afcd7329326170eded00dd2ce0b4e377ed2f
alias: ANGRYSOURCE
color: 023808
num_peers: 7
num_pending_channels: 0
num_active_channels: 5
num_inactive_channels: 0
address:
  - type: ipv4
    address: 51.68.5.193
    port: 9735
  - type: torv3
    address: y5osgenmyzhlohcnkbxl4swwhkrk4hbggrpgkvzyd5mj6ocgqoohqpqd.onion
    port: 9735
binding:
  - type: ipv4
    address: 0.0.0.0
    port: 9735
version: basedon-v0.9.3-1
blockheight: 682235
network: bitcoin
msatoshi_fees_collected: 5700
fees_collected_msat: 5700msat
lightning-dir: /root/.lightning/bitcoin

[cdecker]

This sounds like the peer gave up waiting for the funding to confirm, which it is allowed to do after 2016 blocks or two weeks. In that case we have to rely on the unilateral close transaction to recover the funds if we're unlucky and the funding transaction confirms in a feerate drop.

We have a proposal pending on the spec (lightning/bolts#854) that'll make this much more user friendly, by having the peer that abandons the channel keep just enough information to help the funder recover the funds without having to pay the higher fees and the long penalty timeout that comes with unilateral closes. Let's hope that makes it in before the next feerate spike :-)

[cdecker]

Any suggestion on how to get the funds back (even enforcing a real unilateral channel closure if no other option is available)

Your c-lightning should have sent out the unilateral close already, since that step is automated. Looking at blockexplorers it appears that that close however was dropped, so lightning-cli listtransactions should get you the close transaction, and then you can use bitcoin-cli sendrawtransaction [rawtx] to re-submit it. If there is no such transaction we might have to dig deeper.

[theRescuer]

Hi,
I've broadcasted the closing TX as per your suggestion.
The included fee is much lower than the average shown by mempool. So I guess I have to keep it alive for a while.
Thanks a lot for your support.

[cdecker]

Let us know how things are going. The close tx should go through ok, if not simply rebroadcast during low fee windows until it does

[theRescuer]

Hi,
Finally, the close transaction got confirmed.
The close transaction seems bouncing between FUNDING_SPEND_SEEN and ONCHAIN continuosly.
I had to wait 144 blocks until outputs were resolved.
Now I'm waiting for the channel to be forgotten.
But funds are still not back

listpeers shows the following output
---snip
state_changes:
- timestamp: '2021-04-27T12:29:48.672Z'
old_state: CHANNELD_AWAITING_LOCKIN
new_state: AWAITING_UNILATERAL
cause: protocol
message: >-
channeld: received ERROR channel
ae169b356c7eeb905ea6b0d6e705be8626209e0aac5a315cb80400288d143098:
funding failed due to internal error
- timestamp: '2021-05-29T16:05:43.180Z'
old_state: AWAITING_UNILATERAL
new_state: FUNDING_SPEND_SEEN
cause: onchain
message: Onchain funding spend
- timestamp: '2021-05-29T16:05:43.722Z'
old_state: FUNDING_SPEND_SEEN
new_state: ONCHAIN
cause: onchain
message: Onchain init reply
- timestamp: '2021-05-29T16:29:34.047Z'
old_state: ONCHAIN
new_state: FUNDING_SPEND_SEEN
cause: onchain
message: Onchain funding spend
- timestamp: '2021-05-29T16:29:34.188Z'
old_state: FUNDING_SPEND_SEEN
new_state: ONCHAIN
cause: onchain
message: Onchain init reply
- timestamp: '2021-05-29T16:50:56.629Z'
old_state: ONCHAIN
new_state: FUNDING_SPEND_SEEN
cause: onchain
message: Onchain funding spend
- timestamp: '2021-05-29T16:50:56.931Z'
old_state: FUNDING_SPEND_SEEN
new_state: ONCHAIN
cause: onchain
message: Onchain init reply
- timestamp: '2021-05-29T17:26:48.708Z'
old_state: ONCHAIN
new_state: FUNDING_SPEND_SEEN
cause: onchain
message: Onchain funding spend
- timestamp: '2021-05-29T17:26:48.804Z'
old_state: FUNDING_SPEND_SEEN
new_state: ONCHAIN
cause: onchain
message: Onchain init reply
- timestamp: '2021-05-29T19:47:59.254Z'
old_state: ONCHAIN
new_state: FUNDING_SPEND_SEEN
cause: onchain
message: Onchain funding spend
- timestamp: '2021-05-29T19:47:59.483Z'
old_state: FUNDING_SPEND_SEEN
new_state: ONCHAIN
cause: onchain
message: Onchain init reply
- timestamp: '2021-05-30T00:15:49.734Z'
old_state: ONCHAIN
new_state: FUNDING_SPEND_SEEN
cause: onchain
message: Onchain funding spend
- timestamp: '2021-05-30T00:15:49.906Z'
old_state: FUNDING_SPEND_SEEN
new_state: ONCHAIN
cause: onchain
message: Onchain init reply
- timestamp: '2021-05-30T16:04:24.114Z'
old_state: ONCHAIN
new_state: FUNDING_SPEND_SEEN
cause: onchain
message: Onchain funding spend
- timestamp: '2021-05-30T16:04:24.268Z'
old_state: FUNDING_SPEND_SEEN
new_state: ONCHAIN
cause: onchain
message: Onchain init reply
status:
- 'ONCHAIN:Tracking our own unilateral close'
- >-
ONCHAIN:All outputs resolved: waiting 93 more blocks before
forgetting channel
in_payments_offered: 0
in_msatoshi_offered: 0
in_offered_msat: 0msat
in_payments_fulfilled: 0
in_msatoshi_fulfilled: 0
in_fulfilled_msat: 0msat
out_payments_offered: 0
out_msatoshi_offered: 0
out_offered_msat: 0msat
out_payments_fulfilled: 0
out_msatoshi_fulfilled: 0
out_fulfilled_msat: 0msat
htlcs: []
---snip

[theRescuer]

Funds came back: 2021-05-30 19:44:54 GMT +2