44f83731bc
This reworks the locking behavior of the Gossiper so that a race condition on channel updates and block notifications doesn't cause any loss of messages. This fixes an issue that manifested mostly as flakes on itests during WaitForNetworkChannelOpen calls. The previous behavior allowed ChannelUpdates to be missed if they happened concurrently to block notifications. The processNetworkAnnoucement call would check for the current block height, then lock the gossiper and add the msg to the prematureAnnoucements list. New blocks would trigger an update to the current block height then a lock and check of the aforementioned list. However, specially during itests it could happen that the missing lock before checking the height could case a race condition if the following sequence of events happened: - A new ChannelUpdate message was received and started processing on a separate goroutine - The isPremature() call was made and verified that the ChannelUpdate was in fact premature - The goroutine was scheduled out - A new block started processing in the gossiper. It updated the block height, asked and was granted the lock for the gossiper and verified there was zero premature announcements. The lock was released. - The goroutine processing the ChannelUpdate asked for the gossiper lock and was granted it. It added the ChannelUpdate in the prematureAnnoucements list. This can never be processed now. The way to fix this behavior is to ensure that both isPremature checks done inside processNetworkAnnoucement and best block updates are made inside the same critical section (i.e. while holding the same lock) so that they can't both check and update the prematureAnnoucements list concurrently.
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 API's 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 talks, articles, and example applications can be found at: dev.lightning.community.
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.
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.freenode.net
- channel #lnd
- webchat
Safety
When operating a mainnet lnd node, please refer to our operational safety
guildelines. 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.