lnd.xprv/watchtower/standalone.go

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package watchtower
import (
"net"
"sync/atomic"
"github.com/lightningnetwork/lnd/brontide"
"github.com/lightningnetwork/lnd/watchtower/lookout"
"github.com/lightningnetwork/lnd/watchtower/wtserver"
)
// Standalone encapsulates the server-side functionality required by watchtower
// clients. A Standalone couples the two primary subsystems such that, as a
// unit, this instance can negotiate sessions with clients, accept state updates
// for active sessions, monitor the chain for breaches matching known breach
// hints, publish reconstructed justice transactions on behalf of tower clients.
type Standalone struct {
started uint32 // to be used atomically
stopped uint32 // to be used atomically
cfg *Config
// server is the client endpoint, used for negotiating sessions and
// uploading state updates.
server wtserver.Interface
// lookout is a service that monitors the chain and inspects the
// transactions found in new blocks against the state updates received
// by the server.
lookout lookout.Service
}
// New validates the passed Config and returns a fresh Standalone instance if
// the tower's subsystems could be properly initialized.
func New(cfg *Config) (*Standalone, error) {
// The tower must have listening address in order to accept new updates
// from clients.
if len(cfg.ListenAddrs) == 0 {
return nil, ErrNoListeners
}
// Assign the default read timeout if none is provided.
if cfg.ReadTimeout == 0 {
cfg.ReadTimeout = DefaultReadTimeout
}
// Assign the default write timeout if none is provided.
if cfg.WriteTimeout == 0 {
cfg.WriteTimeout = DefaultWriteTimeout
}
punisher := lookout.NewBreachPunisher(&lookout.PunisherConfig{
PublishTx: cfg.PublishTx,
})
// Initialize the lookout service with its required resources.
lookout := lookout.New(&lookout.Config{
BlockFetcher: cfg.BlockFetcher,
DB: cfg.DB,
EpochRegistrar: cfg.EpochRegistrar,
Punisher: punisher,
})
// Create a brontide listener on each of the provided listening
// addresses. Client should be able to connect to any of open ports to
// communicate with this Standalone instance.
listeners := make([]net.Listener, 0, len(cfg.ListenAddrs))
for _, listenAddr := range cfg.ListenAddrs {
listener, err := brontide.NewListener(
cfg.NodePrivKey, listenAddr.String(),
)
if err != nil {
return nil, err
}
listeners = append(listeners, listener)
}
// Initialize the server with its required resources.
server, err := wtserver.New(&wtserver.Config{
DB: cfg.DB,
NodePrivKey: cfg.NodePrivKey,
Listeners: listeners,
ReadTimeout: cfg.ReadTimeout,
WriteTimeout: cfg.WriteTimeout,
NewAddress: cfg.NewAddress,
})
if err != nil {
return nil, err
}
return &Standalone{
cfg: cfg,
server: server,
lookout: lookout,
}, nil
}
// Start idempotently starts the Standalone, an error is returned if the
// subsystems could not be initialized.
func (w *Standalone) Start() error {
if !atomic.CompareAndSwapUint32(&w.started, 0, 1) {
return nil
}
log.Infof("Starting watchtower")
if err := w.lookout.Start(); err != nil {
return err
}
if err := w.server.Start(); err != nil {
w.lookout.Stop()
return err
}
log.Infof("Watchtower started successfully")
return nil
}
// Stop idempotently stops the Standalone and blocks until the subsystems have
// completed their shutdown.
func (w *Standalone) Stop() error {
if !atomic.CompareAndSwapUint32(&w.stopped, 0, 1) {
return nil
}
log.Infof("Stopping watchtower")
w.server.Stop()
w.lookout.Stop()
log.Infof("Watchtower stopped successfully")
return nil
}