8b565d64d9
In this commit, we add a fast-path optimization to the chain watcher's
closeObserver that immediately dispatches close events when only a single
confirmation is required (numConfs == 1). This addresses a timing issue
with integration tests that were designed around the old synchronous
blockbeat behavior, where close events were dispatched immediately upon
spend detection.
The recent async confirmation architecture (introduced in commit f6f716ab7)
properly handles reorgs by waiting for N confirmations before dispatching
close events. However, this created a race condition in integration tests
that mine blocks synchronously and expect immediate close notifications.
With the build tag setting numConfs to 1 for itests, the async confirmation
notification could arrive after the test already started waiting for the
close event, causing timeouts.
We introduce a new handleSpendDispatch method that checks if numConfs == 1
and, if so, immediately calls handleCommitSpend to dispatch the close event
synchronously, then returns true to skip the async state machine. This
preserves the old behavior for integration tests while maintaining the full
async reorg protection for production (where numConfs >= 3).
The implementation adds the fast-path check in both spend detection paths
(blockbeat and spend notification) to ensure consistent behavior regardless
of which detects the spend first. We also update the affected unit tests to
remove their expectation of confirmation registration, since the fast-path
bypasses that step entirely.
This approach optimizes for the integration test scenario without compromising
production safety, as the fast-path only activates when a single confirmation
is sufficient - a configuration that only exists in the controlled test
environment.
Lightning Network Daemon
The Lightning Network Daemon (lnd) - is a complete implementation of a
Lightning Network node. lnd has several pluggable back-end
chain services including btcd (a
full-node), bitcoind, and
neutrino (a new experimental light client). The project's codebase uses the
btcsuite set of Bitcoin libraries, and also
exports a large set of isolated re-usable Lightning Network related libraries
within it. In the current state lnd is capable of:
- Creating channels.
- Closing channels.
- Completely managing all channel states (including the exceptional ones!).
- Maintaining a fully authenticated+validated channel graph.
- Performing path finding within the network, passively forwarding incoming payments.
- Sending outgoing onion-encrypted payments through the network.
- Updating advertised fee schedules.
- Automatic channel management (
autopilot).
Lightning Network Specification Compliance
lnd fully conforms to the Lightning Network specification
(BOLTs). BOLT stands for:
Basis of Lightning Technology. The specifications are currently being drafted
by several groups of implementers based around the world including the
developers of lnd. The set of specification documents as well as our
implementation of the specification are still a work-in-progress. With that
said, the current status of lnd's BOLT compliance is:
- BOLT 1: Base Protocol
- BOLT 2: Peer Protocol for Channel Management
- BOLT 3: Bitcoin Transaction and Script Formats
- BOLT 4: Onion Routing Protocol
- BOLT 5: Recommendations for On-chain Transaction Handling
- BOLT 7: P2P Node and Channel Discovery
- BOLT 8: Encrypted and Authenticated Transport
- BOLT 9: Assigned Feature Flags
- BOLT 10: DNS Bootstrap and Assisted Node Location
- BOLT 11: Invoice Protocol for Lightning Payments
Developer Resources
The daemon has been designed to be as developer friendly as possible in order
to facilitate application development on top of lnd. Two primary RPC
interfaces are exported: an HTTP REST API, and a gRPC
service. The exported APIs are not yet stable, so be warned: they may change
drastically in the near future.
An automatically generated set of documentation for the RPC APIs can be found at api.lightning.community. A set of developer resources including guides, articles, example applications and community resources can be found at: docs.lightning.engineering.
Finally, we also have an active
Slack where protocol developers, application developers, testers and users gather to
discuss various aspects of lnd and also Lightning in general.
First-time contributors are highly encouraged to start with code review first, before creating their own Pull Requests.
Installation
In order to build from source, please see the installation instructions.
Docker
To run lnd from Docker, please see the main Docker instructions
IRC
- irc.libera.chat
- channel #lnd
- webchat
Safety
When operating a mainnet lnd node, please refer to our operational safety
guidelines. It is important to note that lnd is still
beta software and that ignoring these operational guidelines can lead to
loss of funds.
Security
The developers of lnd take security very seriously. The disclosure of
security vulnerabilities helps us secure the health of lnd, privacy of our
users, and also the health of the Lightning Network as a whole. If you find
any issues regarding security or privacy, please disclose the information
responsibly by sending an email to security at lightning dot engineering,
preferably encrypted using our designated PGP key
(91FE464CD75101DA6B6BAB60555C6465E5BCB3AF) which can be found
here.