lnd.xprv/feature/manager.go

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package feature
import (
"fmt"
"github.com/lightningnetwork/lnd/lnwire"
)
// Config houses any runtime modifications to the default set descriptors. For
// our purposes, this typically means disabling certain features to test legacy
// protocol interoperability or functionality.
type Config struct {
// NoTLVOnion unsets any optional or required TLVOnionPaylod bits from
// all feature sets.
NoTLVOnion bool
// NoStaticRemoteKey unsets any optional or required StaticRemoteKey
// bits from all feature sets.
NoStaticRemoteKey bool
}
// Manager is responsible for generating feature vectors for different requested
// feature sets.
type Manager struct {
// fsets is a static map of feature set to raw feature vectors. Requests
// are fulfilled by cloning these interal feature vectors.
fsets map[Set]*lnwire.RawFeatureVector
}
// NewManager creates a new feature Manager, applying any custom modifications
// to its feature sets before returning.
func NewManager(cfg Config) (*Manager, error) {
return newManager(cfg, defaultSetDesc)
}
// newManager creates a new feeature Manager, applying any custom modifications
// to its feature sets before returning. This method accepts the setDesc as its
// own parameter so that it can be unit tested.
func newManager(cfg Config, desc setDesc) (*Manager, error) {
// First build the default feature vector for all known sets.
fsets := make(map[Set]*lnwire.RawFeatureVector)
for bit, sets := range desc {
for set := range sets {
// Fetch the feature vector for this set, allocating a
// new one if it doesn't exist.
fv, ok := fsets[set]
if !ok {
fv = lnwire.NewRawFeatureVector()
}
// Set the configured bit on the feature vector,
// ensuring that we don't set two feature bits for the
// same pair.
err := fv.SafeSet(bit)
if err != nil {
return nil, fmt.Errorf("unable to set "+
"%v in %v: %v", bit, set, err)
}
// Write the updated feature vector under its set.
fsets[set] = fv
}
}
// Now, remove any features as directed by the config.
for set, raw := range fsets {
if cfg.NoTLVOnion {
raw.Unset(lnwire.TLVOnionPayloadOptional)
raw.Unset(lnwire.TLVOnionPayloadRequired)
raw.Unset(lnwire.PaymentAddrOptional)
raw.Unset(lnwire.PaymentAddrRequired)
raw.Unset(lnwire.MPPOptional)
raw.Unset(lnwire.MPPRequired)
}
if cfg.NoStaticRemoteKey {
raw.Unset(lnwire.StaticRemoteKeyOptional)
raw.Unset(lnwire.StaticRemoteKeyRequired)
}
// Ensure that all of our feature sets properly set any
// dependent features.
fv := lnwire.NewFeatureVector(raw, lnwire.Features)
err := ValidateDeps(fv)
if err != nil {
return nil, fmt.Errorf("invalid feature set %v: %v",
set, err)
}
}
return &Manager{
fsets: fsets,
}, nil
}
// GetRaw returns a raw feature vector for the passed set. If no set is known,
// an empty raw feature vector is returned.
func (m *Manager) GetRaw(set Set) *lnwire.RawFeatureVector {
if fv, ok := m.fsets[set]; ok {
return fv.Clone()
}
return lnwire.NewRawFeatureVector()
}
// Get returns a feature vector for the passed set. If no set is known, an empty
// feature vector is returned.
func (m *Manager) Get(set Set) *lnwire.FeatureVector {
raw := m.GetRaw(set)
return lnwire.NewFeatureVector(raw, lnwire.Features)
}