channeldb+funding: move policy encoding into channel DB

channeldb/forwarding_policy.go

@@ -1,6 +1,10 @@
 package channeldb
 
-import "github.com/lightningnetwork/lnd/kvdb"
+import (
+	"github.com/lightningnetwork/lnd/channeldb/models"
+	"github.com/lightningnetwork/lnd/kvdb"
+	"github.com/lightningnetwork/lnd/lnwire"
+)
 
 var (
 	// initialChannelForwardingPolicyBucket is the database bucket used to
@@ -13,8 +17,18 @@ var (
 
 // SaveInitialForwardingPolicy saves the serialized forwarding policy for the
 // provided permanent channel id to the initialChannelForwardingPolicyBucket.
-func (c *ChannelStateDB) SaveInitialForwardingPolicy(chanID,
-	forwardingPolicy []byte) error {
+func (c *ChannelStateDB) SaveInitialForwardingPolicy(chanID lnwire.ChannelID,
+	forwardingPolicy *models.ForwardingPolicy) error {
+
+	chanIDCopy := make([]byte, 32)
+	copy(chanIDCopy, chanID[:])
+
+	scratch := make([]byte, 36)
+	byteOrder.PutUint64(scratch[:8], uint64(forwardingPolicy.MinHTLCOut))
+	byteOrder.PutUint64(scratch[8:16], uint64(forwardingPolicy.MaxHTLC))
+	byteOrder.PutUint64(scratch[16:24], uint64(forwardingPolicy.BaseFee))
+	byteOrder.PutUint64(scratch[24:32], uint64(forwardingPolicy.FeeRate))
+	byteOrder.PutUint32(scratch[32:], forwardingPolicy.TimeLockDelta)
 
 	return kvdb.Update(c.backend, func(tx kvdb.RwTx) error {
 		bucket, err := tx.CreateTopLevelBucket(
@@ -24,17 +38,20 @@ func (c *ChannelStateDB) SaveInitialForwardingPolicy(chanID,
 			return err
 		}
 
-		return bucket.Put(chanID, forwardingPolicy)
+		return bucket.Put(chanIDCopy, scratch)
 	}, func() {})
 }
 
 // GetInitialForwardingPolicy fetches the serialized forwarding policy for the
 // provided channel id from the database, or returns ErrChannelNotFound if
 // a forwarding policy for this channel id is not found.
-func (c *ChannelStateDB) GetInitialForwardingPolicy(chanID []byte) ([]byte,
-	error) {
+func (c *ChannelStateDB) GetInitialForwardingPolicy(
+	chanID lnwire.ChannelID) (*models.ForwardingPolicy, error) {
 
-	var serializedState []byte
+	chanIDCopy := make([]byte, 32)
+	copy(chanIDCopy, chanID[:])
+
+	var forwardingPolicy *models.ForwardingPolicy
 	err := kvdb.View(c.backend, func(tx kvdb.RTx) error {
 		bucket := tx.ReadBucket(initialChannelForwardingPolicyBucket)
 		if bucket == nil {
@@ -44,23 +61,43 @@ func (c *ChannelStateDB) GetInitialForwardingPolicy(chanID []byte) ([]byte,
 			return ErrChannelNotFound
 		}
 
-		stateBytes := bucket.Get(chanID)
+		stateBytes := bucket.Get(chanIDCopy)
 		if stateBytes == nil {
 			return ErrChannelNotFound
 		}
 
-		serializedState = append(serializedState, stateBytes...)
+		forwardingPolicy = &models.ForwardingPolicy{
+			MinHTLCOut: lnwire.MilliSatoshi(
+				byteOrder.Uint64(stateBytes[:8]),
+			),
+			MaxHTLC: lnwire.MilliSatoshi(
+				byteOrder.Uint64(stateBytes[8:16]),
+			),
+			BaseFee: lnwire.MilliSatoshi(
+				byteOrder.Uint64(stateBytes[16:24]),
+			),
+			FeeRate: lnwire.MilliSatoshi(
+				byteOrder.Uint64(stateBytes[24:32]),
+			),
+			TimeLockDelta: byteOrder.Uint32(stateBytes[32:36]),
+		}
 
 		return nil
 	}, func() {
-		serializedState = nil
+		forwardingPolicy = nil
 	})
-	return serializedState, err
+
+	return forwardingPolicy, err
 }
 
 // DeleteInitialForwardingPolicy removes the forwarding policy for a given
 // channel from the database.
-func (c *ChannelStateDB) DeleteInitialForwardingPolicy(chanID []byte) error {
+func (c *ChannelStateDB) DeleteInitialForwardingPolicy(
+	chanID lnwire.ChannelID) error {
+
+	chanIDCopy := make([]byte, 32)
+	copy(chanIDCopy, chanID[:])
+
 	return kvdb.Update(c.backend, func(tx kvdb.RwTx) error {
 		bucket := tx.ReadWriteBucket(
 			initialChannelForwardingPolicyBucket,
@@ -69,6 +106,6 @@ func (c *ChannelStateDB) DeleteInitialForwardingPolicy(chanID []byte) error {
 			return ErrChannelNotFound
 		}
 
-		return bucket.Delete(chanID)
+		return bucket.Delete(chanIDCopy)
 	}, func() {})
 }

channeldb/models/channel.go

@@ -90,3 +90,41 @@ func (k *CircuitKey) Decode(r io.Reader) error {
 func (k CircuitKey) String() string {
 	return fmt.Sprintf("(Chan ID=%s, HTLC ID=%d)", k.ChanID, k.HtlcID)
 }
+
+// ForwardingPolicy describes the set of constraints that a given ChannelLink
+// is to adhere to when forwarding HTLC's. For each incoming HTLC, this set of
+// constraints will be consulted in order to ensure that adequate fees are
+// paid, and our time-lock parameters are respected. In the event that an
+// incoming HTLC violates any of these constraints, it is to be _rejected_ with
+// the error possibly carrying along a ChannelUpdate message that includes the
+// latest policy.
+type ForwardingPolicy struct {
+	// MinHTLCOut is the smallest HTLC that is to be forwarded.
+	MinHTLCOut lnwire.MilliSatoshi
+
+	// MaxHTLC is the largest HTLC that is to be forwarded.
+	MaxHTLC lnwire.MilliSatoshi
+
+	// BaseFee is the base fee, expressed in milli-satoshi that must be
+	// paid for each incoming HTLC. This field, combined with FeeRate is
+	// used to compute the required fee for a given HTLC.
+	BaseFee lnwire.MilliSatoshi
+
+	// FeeRate is the fee rate, expressed in milli-satoshi that must be
+	// paid for each incoming HTLC. This field combined with BaseFee is
+	// used to compute the required fee for a given HTLC.
+	FeeRate lnwire.MilliSatoshi
+
+	// TimeLockDelta is the absolute time-lock value, expressed in blocks,
+	// that will be subtracted from an incoming HTLC's timelock value to
+	// create the time-lock value for the forwarded outgoing HTLC. The
+	// following constraint MUST hold for an HTLC to be forwarded:
+	//
+	//  * incomingHtlc.timeLock - timeLockDelta = fwdInfo.OutgoingCTLV
+	//
+	// where fwdInfo is the forwarding information extracted from the
+	// per-hop payload of the incoming HTLC's onion packet.
+	TimeLockDelta uint32
+
+	// TODO(roasbeef): add fee module inside of switch
+}

funding/manager.go

@@ -20,6 +20,7 @@ import (
 	"github.com/lightningnetwork/lnd/chainreg"
 	"github.com/lightningnetwork/lnd/chanacceptor"
 	"github.com/lightningnetwork/lnd/channeldb"
+	"github.com/lightningnetwork/lnd/channeldb/models"
 	"github.com/lightningnetwork/lnd/discovery"
 	"github.com/lightningnetwork/lnd/htlcswitch"
 	"github.com/lightningnetwork/lnd/input"
@@ -4636,62 +4637,45 @@ func (f *Manager) defaultForwardingPolicy(
 
 // saveInitialForwardingPolicy saves the forwarding policy for the provided
 // chanPoint in the channelOpeningStateBucket.
-func (f *Manager) saveInitialForwardingPolicy(permChanID lnwire.ChannelID,
+func (f *Manager) saveInitialForwardingPolicy(chanID lnwire.ChannelID,
 	forwardingPolicy *htlcswitch.ForwardingPolicy) error {
 
-	chanID := make([]byte, 32)
-	copy(chanID, permChanID[:])
-
-	scratch := make([]byte, 36)
-	byteOrder.PutUint64(scratch[:8], uint64(forwardingPolicy.MinHTLCOut))
-	byteOrder.PutUint64(scratch[8:16], uint64(forwardingPolicy.MaxHTLC))
-	byteOrder.PutUint64(scratch[16:24], uint64(forwardingPolicy.BaseFee))
-	byteOrder.PutUint64(scratch[24:32], uint64(forwardingPolicy.FeeRate))
-	byteOrder.PutUint32(scratch[32:], forwardingPolicy.TimeLockDelta)
-
-	return f.cfg.ChannelDB.SaveInitialForwardingPolicy(chanID, scratch)
+	return f.cfg.ChannelDB.SaveInitialForwardingPolicy(
+		chanID, &models.ForwardingPolicy{
+			MinHTLCOut:    forwardingPolicy.MinHTLCOut,
+			MaxHTLC:       forwardingPolicy.MaxHTLC,
+			BaseFee:       forwardingPolicy.BaseFee,
+			FeeRate:       forwardingPolicy.FeeRate,
+			TimeLockDelta: forwardingPolicy.TimeLockDelta,
+		},
+	)
 }
 
 // getInitialForwardingPolicy fetches the initial forwarding policy for a given
 // channel id from the database which will be applied during the channel
 // announcement phase.
 func (f *Manager) getInitialForwardingPolicy(
-	permChanID lnwire.ChannelID) (*htlcswitch.ForwardingPolicy, error) {
+	chanID lnwire.ChannelID) (*htlcswitch.ForwardingPolicy, error) {
 
-	chanID := make([]byte, 32)
-	copy(chanID, permChanID[:])
-
-	value, err := f.cfg.ChannelDB.GetInitialForwardingPolicy(chanID)
+	dbPolicy, err := f.cfg.ChannelDB.GetInitialForwardingPolicy(
+		chanID,
+	)
 	if err != nil {
 		return nil, err
 	}
 
-	var forwardingPolicy htlcswitch.ForwardingPolicy
-	forwardingPolicy.MinHTLCOut = lnwire.MilliSatoshi(
-		byteOrder.Uint64(value[:8]),
-	)
-	forwardingPolicy.MaxHTLC = lnwire.MilliSatoshi(
-		byteOrder.Uint64(value[8:16]),
-	)
-	forwardingPolicy.BaseFee = lnwire.MilliSatoshi(
-		byteOrder.Uint64(value[16:24]),
-	)
-	forwardingPolicy.FeeRate = lnwire.MilliSatoshi(
-		byteOrder.Uint64(value[24:32]),
-	)
-	forwardingPolicy.TimeLockDelta = byteOrder.Uint32(value[32:36])
-
-	return &forwardingPolicy, nil
+	return &htlcswitch.ForwardingPolicy{
+		MinHTLCOut:    dbPolicy.MinHTLCOut,
+		MaxHTLC:       dbPolicy.MaxHTLC,
+		BaseFee:       dbPolicy.BaseFee,
+		FeeRate:       dbPolicy.FeeRate,
+		TimeLockDelta: dbPolicy.TimeLockDelta,
+	}, nil
 }
 
 // deleteInitialForwardingPolicy removes channel fees for this chanID from
 // the database.
-func (f *Manager) deleteInitialForwardingPolicy(
-	permChanID lnwire.ChannelID) error {
-
-	chanID := make([]byte, 32)
-	copy(chanID, permChanID[:])
-
+func (f *Manager) deleteInitialForwardingPolicy(chanID lnwire.ChannelID) error {
 	return f.cfg.ChannelDB.DeleteInitialForwardingPolicy(chanID)
 }