multi: only allow specifying towers to TowerClient through RPC

With the introduction of the WatchtowerClient RPC subserver, the lnd
configuration flag to specify private watchtowers for the client is no
longer needed and can lead to confusion upon users. Therefore, we remove
the flag completely, and only rely on the watchtower client being active
through a new --wtclient.active flag.

lncfg/wtclient.go

@@ -1,65 +1,38 @@
 package lncfg
 
-import (
-	"fmt"
-	"strconv"
-
-	"github.com/lightningnetwork/lnd/lnwire"
-)
+import "errors"
 
 // WtClient holds the configuration options for the daemon's watchtower client.
 type WtClient struct {
+	// Active determines whether a watchtower client should be created to
+	// back up channel states with registered watchtowers.
+	Active bool `long:"active" description:"Whether the daemon should use private watchtowers to back up revoked channel states."`
+
 	// PrivateTowerURIs specifies the lightning URIs of the towers the
 	// watchtower client should send new backups to.
-	PrivateTowerURIs []string `long:"private-tower-uris" description:"Specifies the URIs of private watchtowers to use in backing up revoked states. URIs must be of the form <pubkey>@<addr>. Only 1 URI is supported at this time, if none are provided the tower will not be enabled."`
-
-	// PrivateTowers is the list of towers parsed from the URIs provided in
-	// PrivateTowerURIs.
-	PrivateTowers []*lnwire.NetAddress
+	PrivateTowerURIs []string `long:"private-tower-uris" description:"(Deprecated) Specifies the URIs of private watchtowers to use in backing up revoked states. URIs must be of the form <pubkey>@<addr>. Only 1 URI is supported at this time, if none are provided the tower will not be enabled."`
 
 	// SweepFeeRate specifies the fee rate in sat/byte to be used when
 	// constructing justice transactions sent to the tower.
 	SweepFeeRate uint64 `long:"sweep-fee-rate" description:"Specifies the fee rate in sat/byte to be used when constructing justice transactions sent to the watchtower."`
 }
 
-// Validate asserts that at most 1 private watchtower is requested.
+// Validate ensures the user has provided a valid configuration.
 //
 // NOTE: Part of the Validator interface.
 func (c *WtClient) Validate() error {
-	if len(c.PrivateTowerURIs) > 1 {
-		return fmt.Errorf("at most 1 private watchtower is supported, "+
-			"found %d", len(c.PrivateTowerURIs))
+	if len(c.PrivateTowerURIs) > 0 {
+		return errors.New("`wtclient.private-tower-uris` is " +
+			"deprecated and will be removed in the v0.8.0 " +
+			"release, to specify watchtowers remove " +
+			"`wtclient.private-tower-uris`, set " +
+			"`wtclient.active`, and check out `lncli wtclient -h` " +
+			"for more information on how to manage towers")
 	}
 
 	return nil
 }
 
-// IsActive returns true if the watchtower client should be active.
-func (c *WtClient) IsActive() bool {
-	return len(c.PrivateTowerURIs) > 0
-}
-
-// ParsePrivateTowers parses any private tower URIs held PrivateTowerURIs. The
-// value of port should be the default port to use when a URI does not have one.
-func (c *WtClient) ParsePrivateTowers(port int, resolver TCPResolver) error {
-	towers := make([]*lnwire.NetAddress, 0, len(c.PrivateTowerURIs))
-	for _, uri := range c.PrivateTowerURIs {
-		addr, err := ParseLNAddressString(
-			uri, strconv.Itoa(port), resolver,
-		)
-		if err != nil {
-			return fmt.Errorf("unable to parse private "+
-				"watchtower address: %v", err)
-		}
-
-		towers = append(towers, addr)
-	}
-
-	c.PrivateTowers = towers
-
-	return nil
-}
-
 // Compile-time constraint to ensure WtClient implements the Validator
 // interface.
 var _ Validator = (*WtClient)(nil)