- use_recoverable_channel is a user setting, available
only in standard wallets with a 'segwit' seed_type
- if enabled, 'lightning_xprv' is derived from seed
- otherwise, wallets use the existing 'lightning_privkey2'
Recoverable channels:
- channel recovery data is added funding tx using an OP_RETURN
- recovery data = 4 magic bytes + node id[0:16]
- recovery data is chacha20 encrypted using funding_address as nonce.
(this will allow to fund multiple channels in the same tx)
GUI:
- whether channels are recoverable is shown in wallet info dialog.
- if the wallet can have recoverable channels but has an old node_id,
users are told to close their channels and restore from seed
to have that feature.
Now that the checkbox is hidden behind an advanced option, there is
no need to be brief about it, better to be explicit.
(terminology unchanged for kivy.)
- trampoline is enabled by default in config, to prevent download of `gossip_db`.
(if disabled, `gossip_db` will be downloaded, regardless of the existence of channels)
- if trampoline is enabled:
- the wallet can only open channels with trampoline nodes
- already-existing channels with non-trampoline nodes are frozen for sending.
- there are two types of trampoline payments: legacy and end-to-end (e2e).
- we decide to perform legacy or e2e based on the invoice:
- we use trampoline_routing_opt in features to detect Eclair and Phoenix invoices
- we use trampoline_routing_hints to detect Electrum invoices
- when trying a legacy payment, we add a second trampoline to the path to preserve privacy.
(we fall back to a single trampoline if the payment fails for all trampolines)
- the trampoline list is hardcoded, it will remain so until `trampoline_routing_opt` feature flag is in INIT.
- there are currently only two nodes in the hardcoded list, it would be nice to have more.
- similar to Phoenix, we find the fee/cltv by trial-and-error.
- if there is a second trampoline in the path, we use the same fee for both.
- the final spec should add fee info in error messages, so we will be able to fine-tune fees
- LNWorker is notified about htlc events and creates payment events.
- LNWorker._pay is a while loop that calls create_routes_from_invoice.
- create_route_from_invoices should decide whether to split the payment,
using graph knowledge and feedback from previous attempts (not in this commit)
- data structures for payment logs are simplified into a single type, HtlcLog
