wtdb: add TowerStatus to Tower

This is added as a TLV record meaning that all the towers currently on
disk that don't have this new field will be seen as Active.

watchtower/wtdb/codec_test.go

@@ -179,6 +179,7 @@ func TestCodec(tt *testing.T) {
 			obj := wtdb.Tower{
 				IdentityKey: pk,
 				Addresses:   addrs,
+				Status:      wtdb.TowerStatus(r.Uint32()),
 			}
 
 			v[0] = reflect.ValueOf(obj)

watchtower/wtdb/tower.go

@@ -7,6 +7,26 @@ import (
 	"net"
 
 	"github.com/btcsuite/btcd/btcec/v2"
+	"github.com/lightningnetwork/lnd/tlv"
+)
+
+// TowerStatus represents the state of the tower as set by the tower client.
+type TowerStatus uint8
+
+const (
+	// TowerStatusActive is the default state of the tower, and it indicates
+	// that this tower should be used to attempt session creation.
+	TowerStatusActive TowerStatus = 0
+
+	// TowerStatusInactive indicates that the tower should not be used to
+	// attempt session creation.
+	TowerStatusInactive TowerStatus = 1
+)
+
+const (
+	// TowerStatusTLVType is the TLV type number that will be used to store
+	// the tower's status.
+	TowerStatusTLVType = tlv.Type(0)
 )
 
 // TowerID is a unique 64-bit identifier allocated to each unique watchtower.
@@ -41,6 +61,9 @@ type Tower struct {
 
 	// Addresses is a list of possible addresses to reach the tower.
 	Addresses []net.Addr
+
+	// Status is the status of this tower as set by the client.
+	Status TowerStatus
 }
 
 // AddAddress adds the given address to the tower's in-memory list of addresses.
@@ -88,17 +111,56 @@ func (t *Tower) String() string {
 // Encode writes the Tower to the passed io.Writer. The TowerID is not
 // serialized, since it acts as the key.
 func (t *Tower) Encode(w io.Writer) error {
-	return WriteElements(w,
+	err := WriteElements(w,
 		t.IdentityKey,
 		t.Addresses,
 	)
+	if err != nil {
+		return err
+	}
+
+	status := uint8(t.Status)
+	tlvRecords := []tlv.Record{
+		tlv.MakePrimitiveRecord(TowerStatusTLVType, &status),
+	}
+
+	tlvStream, err := tlv.NewStream(tlvRecords...)
+	if err != nil {
+		return err
+	}
+
+	return tlvStream.Encode(w)
 }
 
 // Decode reads a Tower from the passed io.Reader. The TowerID is meant to be
 // decoded from the key.
 func (t *Tower) Decode(r io.Reader) error {
-	return ReadElements(r,
+	err := ReadElements(r,
 		&t.IdentityKey,
 		&t.Addresses,
 	)
+	if err != nil {
+		return err
+	}
+
+	var status uint8
+	tlvRecords := []tlv.Record{
+		tlv.MakePrimitiveRecord(TowerStatusTLVType, &status),
+	}
+
+	tlvStream, err := tlv.NewStream(tlvRecords...)
+	if err != nil {
+		return err
+	}
+
+	typeMap, err := tlvStream.DecodeWithParsedTypes(r)
+	if err != nil {
+		return err
+	}
+
+	if _, ok := typeMap[TowerStatusTLVType]; ok {
+		t.Status = TowerStatus(status)
+	}
+
+	return nil
 }