lnrpc: add new WalletKit sub-RPC server

chainregistry.go

@@ -107,6 +107,10 @@ type chainControl struct {
 
 	signer lnwallet.Signer
 
+	keyRing keychain.KeyRing
+
+	wc lnwallet.WalletController
+
 	msgSigner lnwallet.MessageSigner
 
 	chainNotifier chainntnfs.ChainNotifier
@@ -502,6 +506,7 @@ func newChainControlFromConfig(cfg *config, chanDB *channeldb.DB,
 	cc.msgSigner = wc
 	cc.signer = wc
 	cc.chainIO = wc
+	cc.wc = wc
 
 	// Select the default channel constraints for the primary chain.
 	channelConstraints := defaultBtcChannelConstraints
@@ -512,6 +517,7 @@ func newChainControlFromConfig(cfg *config, chanDB *channeldb.DB,
 	keyRing := keychain.NewBtcWalletKeyRing(
 		wc.InternalWallet(), activeNetParams.CoinType,
 	)
+	cc.keyRing = keyRing
 
 	// Create, and start the lnwallet, which handles the core payment
 	// channel logic, and exposes control via proxy state machines.

lnrpc/signrpc/signer.proto

@@ -11,19 +11,17 @@ message KeyLocator {
 }
 
 message KeyDescriptor {
-     oneof key {
-         /**
-         The raw bytes of the key being identified. Either this or the KeyLocator
-         must be specified.
-         */
-         bytes raw_key_bytes = 1;
-
-         /** 
-         The key locator that identifies which key to use for signing. Either this
-         or the raw bytes of the target key must be specified.
-         */
-         KeyLocator key_loc = 2;
-     }
+     /**
+     The raw bytes of the key being identified. Either this or the KeyLocator
+     must be specified.
+     */
+     bytes raw_key_bytes = 1;
+
+     /** 
+     The key locator that identifies which key to use for signing. Either this
+     or the raw bytes of the target key must be specified.
+     */
+     KeyLocator key_loc = 2;
 }
 
 message TxOut {

lnrpc/walletrpc/config_active.go

@@ -0,0 +1,41 @@
+// +build walletrpc
+
+package walletrpc
+
+import (
+	"github.com/lightningnetwork/lnd/keychain"
+	"github.com/lightningnetwork/lnd/lnwallet"
+	"github.com/lightningnetwork/lnd/macaroons"
+)
+
+// Config is the primary configuration struct for the WalletKit RPC server. It
+// contains all the items required for the signer rpc server to carry out its
+// duties. The fields with struct tags are meant to be parsed as normal
+// configuration options, while if able to be populated, the latter fields MUST
+// also be specified.
+type Config struct {
+	// WalletKitMacPath is the path for the signer macaroon. If unspecified
+	// then we assume that the macaroon will be found under the network
+	// directory, named DefaultWalletKitMacFilename.
+	WalletKitMacPath string `long:"walletkitmacaroonpath" description:"Path to the wallet kit macaroon"`
+
+	// NetworkDir is the main network directory wherein the signer rpc
+	// server will find the macaroon named DefaultWalletKitMacFilename.
+	NetworkDir string
+
+	// MacService is the main macaroon service that we'll use to handle
+	// authentication for the signer rpc server.
+	MacService *macaroons.Service
+
+	// FeeEstimator is an instance of the primary fee estimator instance
+	// the WalletKit will use to respond to fee estimation requests.
+	FeeEstimator lnwallet.FeeEstimator
+
+	// Wallet is the primary wallet that the WalletKit will use to proxy
+	// any relevant requests to.
+	Wallet lnwallet.WalletController
+
+	// KeyRing is an interface that the WalletKit will use to derive any
+	// keys due to incoming client requests.
+	KeyRing keychain.KeyRing
+}

lnrpc/walletrpc/config_default.go

@@ -0,0 +1,8 @@
+// +build !walletrpc
+
+package walletrpc
+
+// Config is the primary configuration struct for the WalletKit RPC server.
+// When the server isn't active (via the build flag), callers outside this
+// package will see this shell of a config file.
+type Config struct{}

lnrpc/walletrpc/driver.go

@@ -0,0 +1,73 @@
+// +build walletrpc
+
+package walletrpc
+
+import (
+	"fmt"
+
+	"github.com/lightningnetwork/lnd/lnrpc"
+)
+
+// createNewSubServer is a helper method that will create the new WalletKit RPC
+// sub server given the main config dispatcher method. If we're unable to find
+// the config that is meant for us in the config dispatcher, then we'll exit
+// with an error.
+func createNewSubServer(configRegistry lnrpc.SubServerConfigDispatcher) (lnrpc.SubServer, lnrpc.MacaroonPerms, error) {
+	// We'll attempt to look up the config that we expect, according to our
+	// subServerName name. If we can't find this, then we'll exit with an
+	// error, as we're unable to properly initialize ourselves without this
+	// config.
+	walletKitServerConf, ok := configRegistry.FetchConfig(subServerName)
+	if !ok {
+		return nil, nil, fmt.Errorf("unable to find config for "+
+			"subserver type %s", subServerName)
+	}
+
+	// Now that we've found an object mapping to our service name, we'll
+	// ensure that it's the type we need.
+	config, ok := walletKitServerConf.(*Config)
+	if !ok {
+		return nil, nil, fmt.Errorf("wrong type of config for "+
+			"subserver %s, expected %T got %T", subServerName,
+			&Config{}, walletKitServerConf)
+	}
+
+	// Before we try to make the new WalletKit service instance, we'll
+	// perform some sanity checks on the arguments to ensure that they're
+	// useable.
+	switch {
+	case config.MacService != nil && config.NetworkDir == "":
+		return nil, nil, fmt.Errorf("NetworkDir must be set to " +
+			"create WalletKit RPC server")
+
+	case config.FeeEstimator == nil:
+		return nil, nil, fmt.Errorf("FeeEstimator must be set to " +
+			"create WalletKit RPC server")
+
+	case config.Wallet == nil:
+		return nil, nil, fmt.Errorf("Wallet must be set to create " +
+			"WalletKit RPC server")
+
+	case config.KeyRing == nil:
+		return nil, nil, fmt.Errorf("KeyRing must be set to create " +
+			"WalletKit RPC server")
+	}
+
+	return New(config)
+}
+
+func init() {
+	subServer := &lnrpc.SubServerDriver{
+		SubServerName: subServerName,
+		New: func(c lnrpc.SubServerConfigDispatcher) (lnrpc.SubServer, lnrpc.MacaroonPerms, error) {
+			return createNewSubServer(c)
+		},
+	}
+
+	// If the build tag is active, then we'll register ourselves as a
+	// sub-RPC server within the global lnrpc package namespace.
+	if err := lnrpc.RegisterSubServer(subServer); err != nil {
+		panic(fmt.Sprintf("failed to register sub server driver '%s': %v",
+			subServerName, err))
+	}
+}