Merge pull request #2093 from Roasbeef/walletkit-service

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.pb.go

@@ -66,10 +66,14 @@ func (m *KeyLocator) GetKeyIndex() int32 {
 }
 
 type KeyDescriptor struct {
-	// Types that are valid to be assigned to Key:
+	// *
-	//	*KeyDescriptor_RawKeyBytes
+	// The raw bytes of the key being identified. Either this or the KeyLocator
-	//	*KeyDescriptor_KeyLoc
+	// must be specified.
-	Key isKeyDescriptor_Key `protobuf_oneof:"key"`
+	RawKeyBytes []byte `protobuf:"bytes,1,opt,name=raw_key_bytes,json=rawKeyBytes,proto3" json:"raw_key_bytes,omitempty"`
+	// *
+	// The key locator that identifies which key to use for signing. Either this
+	// or the raw bytes of the target key must be specified.
+	KeyLoc *KeyLocator `protobuf:"bytes,2,opt,name=key_loc,json=keyLoc" json:"key_loc,omitempty"`
 }
 
 func (m *KeyDescriptor) Reset()                    { *m = KeyDescriptor{} }
@@ -77,111 +81,20 @@ func (m *KeyDescriptor) String() string            { return proto.CompactTextStr
 func (*KeyDescriptor) ProtoMessage()               {}
 func (*KeyDescriptor) Descriptor() ([]byte, []int) { return fileDescriptor0, []int{1} }
 
-type isKeyDescriptor_Key interface {
-	isKeyDescriptor_Key()
-}
-
-type KeyDescriptor_RawKeyBytes struct {
-	RawKeyBytes []byte `protobuf:"bytes,1,opt,name=raw_key_bytes,json=rawKeyBytes,proto3,oneof"`
-}
-type KeyDescriptor_KeyLoc struct {
-	KeyLoc *KeyLocator `protobuf:"bytes,2,opt,name=key_loc,json=keyLoc,oneof"`
-}
-
-func (*KeyDescriptor_RawKeyBytes) isKeyDescriptor_Key() {}
-func (*KeyDescriptor_KeyLoc) isKeyDescriptor_Key()      {}
-
-func (m *KeyDescriptor) GetKey() isKeyDescriptor_Key {
-	if m != nil {
-		return m.Key
-	}
-	return nil
-}
-
 func (m *KeyDescriptor) GetRawKeyBytes() []byte {
-	if x, ok := m.GetKey().(*KeyDescriptor_RawKeyBytes); ok {
+	if m != nil {
-		return x.RawKeyBytes
+		return m.RawKeyBytes
 	}
 	return nil
 }
 
 func (m *KeyDescriptor) GetKeyLoc() *KeyLocator {
-	if x, ok := m.GetKey().(*KeyDescriptor_KeyLoc); ok {
+	if m != nil {
-		return x.KeyLoc
+		return m.KeyLoc
 	}
 	return nil
 }
 
-// XXX_OneofFuncs is for the internal use of the proto package.
-func (*KeyDescriptor) XXX_OneofFuncs() (func(msg proto.Message, b *proto.Buffer) error, func(msg proto.Message, tag, wire int, b *proto.Buffer) (bool, error), func(msg proto.Message) (n int), []interface{}) {
-	return _KeyDescriptor_OneofMarshaler, _KeyDescriptor_OneofUnmarshaler, _KeyDescriptor_OneofSizer, []interface{}{
-		(*KeyDescriptor_RawKeyBytes)(nil),
-		(*KeyDescriptor_KeyLoc)(nil),
-	}
-}
-
-func _KeyDescriptor_OneofMarshaler(msg proto.Message, b *proto.Buffer) error {
-	m := msg.(*KeyDescriptor)
-	// key
-	switch x := m.Key.(type) {
-	case *KeyDescriptor_RawKeyBytes:
-		b.EncodeVarint(1<<3 | proto.WireBytes)
-		b.EncodeRawBytes(x.RawKeyBytes)
-	case *KeyDescriptor_KeyLoc:
-		b.EncodeVarint(2<<3 | proto.WireBytes)
-		if err := b.EncodeMessage(x.KeyLoc); err != nil {
-			return err
-		}
-	case nil:
-	default:
-		return fmt.Errorf("KeyDescriptor.Key has unexpected type %T", x)
-	}
-	return nil
-}
-
-func _KeyDescriptor_OneofUnmarshaler(msg proto.Message, tag, wire int, b *proto.Buffer) (bool, error) {
-	m := msg.(*KeyDescriptor)
-	switch tag {
-	case 1: // key.raw_key_bytes
-		if wire != proto.WireBytes {
-			return true, proto.ErrInternalBadWireType
-		}
-		x, err := b.DecodeRawBytes(true)
-		m.Key = &KeyDescriptor_RawKeyBytes{x}
-		return true, err
-	case 2: // key.key_loc
-		if wire != proto.WireBytes {
-			return true, proto.ErrInternalBadWireType
-		}
-		msg := new(KeyLocator)
-		err := b.DecodeMessage(msg)
-		m.Key = &KeyDescriptor_KeyLoc{msg}
-		return true, err
-	default:
-		return false, nil
-	}
-}
-
-func _KeyDescriptor_OneofSizer(msg proto.Message) (n int) {
-	m := msg.(*KeyDescriptor)
-	// key
-	switch x := m.Key.(type) {
-	case *KeyDescriptor_RawKeyBytes:
-		n += proto.SizeVarint(1<<3 | proto.WireBytes)
-		n += proto.SizeVarint(uint64(len(x.RawKeyBytes)))
-		n += len(x.RawKeyBytes)
-	case *KeyDescriptor_KeyLoc:
-		s := proto.Size(x.KeyLoc)
-		n += proto.SizeVarint(2<<3 | proto.WireBytes)
-		n += proto.SizeVarint(uint64(s))
-		n += s
-	case nil:
-	default:
-		panic(fmt.Sprintf("proto: unexpected type %T in oneof", x))
-	}
-	return n
-}
-
 type TxOut struct {
 	// / The value of the output being spent.
 	Value int64 `protobuf:"varint,1,opt,name=value" json:"value,omitempty"`
@@ -376,6 +289,7 @@ func (m *InputScript) GetSigScript() []byte {
 }
 
 type InputScriptResp struct {
+	// / The set of fully valid input scripts requested.
 	InputScripts []*InputScript `protobuf:"bytes,1,rep,name=input_scripts,json=inputScripts" json:"input_scripts,omitempty"`
 }
 
@@ -550,39 +464,38 @@ var _Signer_serviceDesc = grpc.ServiceDesc{
 func init() { proto.RegisterFile("signrpc/signer.proto", fileDescriptor0) }
 
 var fileDescriptor0 = []byte{
-	// 536 bytes of a gzipped FileDescriptorProto
+	// 526 bytes of a gzipped FileDescriptorProto
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-	0x49, 0xa0, 0x51, 0x54, 0x5f, 0x87, 0xf6, 0xf3, 0x64, 0xa1, 0xb4, 0xff, 0xa7, 0x0d, 0x83, 0x05,
+	0xb9, 0xc1, 0xf1, 0xaf, 0x13, 0x38, 0x9b, 0x8b, 0xac, 0x38, 0x30, 0xf8, 0x06, 0xd0, 0x7d, 0xb2,
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+	0xfe, 0xdc, 0x3c, 0x1d, 0xf2, 0x0e, 0x42, 0xfc, 0xba, 0x36, 0x5b, 0xa7, 0xac, 0x21, 0xf7, 0x8e,
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+	0x2e, 0x4f, 0xf9, 0xdd, 0x93, 0xfb, 0x7f, 0x30, 0x4a, 0x92, 0x4f, 0x40, 0xbe, 0x94, 0xb7, 0xb2,
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+	0xfb, 0x3b, 0x00, 0x00, 0xff, 0xff, 0xe8, 0x77, 0xc6, 0x62, 0xcb, 0x03, 0x00, 0x00,
-	0x7b, 0x48, 0x93, 0x2a, 0xd6, 0x03, 0x00, 0x00,
 }

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
-         The raw bytes of the key being identified. Either this or the KeyLocator
+     must be specified.
-         must be specified.
+     */
-         */
+     bytes raw_key_bytes = 1;
-         bytes raw_key_bytes = 1;
 
-         /** 
+     /** 
-         The key locator that identifies which key to use for signing. Either this
+     The key locator that identifies which key to use for signing. Either this
-         or the raw bytes of the target key must be specified.
+     or the raw bytes of the target key must be specified.
-         */
+     */
-         KeyLocator key_loc = 2;
+     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))
+	}
+}

lnrpc/walletrpc/gen_protos.sh

@@ -0,0 +1,6 @@
+#!/bin/sh
+
+protoc -I/usr/local/include -I. \
+       -I$GOPATH/src \
+       --go_out=plugins=grpc:. \
+       walletkit.proto

lnrpc/walletrpc/log.go

@@ -0,0 +1,45 @@
+package walletrpc
+
+import (
+	"github.com/btcsuite/btclog"
+	"github.com/lightningnetwork/lnd/build"
+)
+
+// log is a logger that is initialized with no output filters.  This means the
+// package will not perform any logging by default until the caller requests
+// it.
+var log btclog.Logger
+
+// The default amount of logging is none.
+func init() {
+	UseLogger(build.NewSubLogger("WLKT", nil))
+}
+
+// DisableLog disables all library log output.  Logging output is disabled by
+// by default until UseLogger is called.
+func DisableLog() {
+	UseLogger(btclog.Disabled)
+}
+
+// UseLogger uses a specified Logger to output package logging info.  This
+// should be used in preference to SetLogWriter if the caller is also using
+// btclog.
+func UseLogger(logger btclog.Logger) {
+	log = logger
+}
+
+// logClosure is used to provide a closure over expensive logging operations so
+// don't have to be performed when the logging level doesn't warrant it.
+type logClosure func() string
+
+// String invokes the underlying function and returns the result.
+func (c logClosure) String() string {
+	return c()
+}
+
+// newLogClosure returns a new closure over a function that returns a string
+// which itself provides a Stringer interface so that it can be used with the
+// logging system.
+func newLogClosure(c func() string) logClosure {
+	return logClosure(c)
+}

lnrpc/walletrpc/walletkit.pb.go

@@ -0,0 +1,555 @@
+// Code generated by protoc-gen-go. DO NOT EDIT.
+// source: walletrpc/walletkit.proto
+
+/*
+Package walletrpc is a generated protocol buffer package.
+
+It is generated from these files:
+	walletrpc/walletkit.proto
+
+It has these top-level messages:
+	KeyReq
+	AddrRequest
+	AddrResponse
+	Transaction
+	PublishResponse
+	SendOutputsRequest
+	SendOutputsResponse
+	EstimateFeeRequest
+	EstimateFeeResponse
+*/
+package walletrpc
+
+import proto "github.com/golang/protobuf/proto"
+import fmt "fmt"
+import math "math"
+import signrpc "github.com/lightningnetwork/lnd/lnrpc/signrpc"
+
+import (
+	context "golang.org/x/net/context"
+	grpc "google.golang.org/grpc"
+)
+
+// Reference imports to suppress errors if they are not otherwise used.
+var _ = proto.Marshal
+var _ = fmt.Errorf
+var _ = math.Inf
+
+// This is a compile-time assertion to ensure that this generated file
+// is compatible with the proto package it is being compiled against.
+// A compilation error at this line likely means your copy of the
+// proto package needs to be updated.
+const _ = proto.ProtoPackageIsVersion2 // please upgrade the proto package
+
+type KeyReq struct {
+	// *
+	// Is the key finger print of the root pubkey that this request is targeting.
+	// This allows the WalletKit to possibly serve out keys for multiple HD chains
+	// via public derivation.
+	KeyFingerPrint int32 `protobuf:"varint,1,opt,name=key_finger_print,json=keyFingerPrint" json:"key_finger_print,omitempty"`
+	// *
+	// The target key family to derive a key from. In other contexts, this is
+	// known as the "account".
+	KeyFamily int32 `protobuf:"varint,2,opt,name=key_family,json=keyFamily" json:"key_family,omitempty"`
+}
+
+func (m *KeyReq) Reset()                    { *m = KeyReq{} }
+func (m *KeyReq) String() string            { return proto.CompactTextString(m) }
+func (*KeyReq) ProtoMessage()               {}
+func (*KeyReq) Descriptor() ([]byte, []int) { return fileDescriptor0, []int{0} }
+
+func (m *KeyReq) GetKeyFingerPrint() int32 {
+	if m != nil {
+		return m.KeyFingerPrint
+	}
+	return 0
+}
+
+func (m *KeyReq) GetKeyFamily() int32 {
+	if m != nil {
+		return m.KeyFamily
+	}
+	return 0
+}
+
+type AddrRequest struct {
+}
+
+func (m *AddrRequest) Reset()                    { *m = AddrRequest{} }
+func (m *AddrRequest) String() string            { return proto.CompactTextString(m) }
+func (*AddrRequest) ProtoMessage()               {}
+func (*AddrRequest) Descriptor() ([]byte, []int) { return fileDescriptor0, []int{1} }
+
+type AddrResponse struct {
+	// *
+	// The address encoded using a bech32 format.
+	Addr string `protobuf:"bytes,1,opt,name=addr" json:"addr,omitempty"`
+}
+
+func (m *AddrResponse) Reset()                    { *m = AddrResponse{} }
+func (m *AddrResponse) String() string            { return proto.CompactTextString(m) }
+func (*AddrResponse) ProtoMessage()               {}
+func (*AddrResponse) Descriptor() ([]byte, []int) { return fileDescriptor0, []int{2} }
+
+func (m *AddrResponse) GetAddr() string {
+	if m != nil {
+		return m.Addr
+	}
+	return ""
+}
+
+type Transaction struct {
+	// *
+	// The raw serialized transaction.
+	TxHex []byte `protobuf:"bytes,1,opt,name=tx_hex,json=txHex,proto3" json:"tx_hex,omitempty"`
+}
+
+func (m *Transaction) Reset()                    { *m = Transaction{} }
+func (m *Transaction) String() string            { return proto.CompactTextString(m) }
+func (*Transaction) ProtoMessage()               {}
+func (*Transaction) Descriptor() ([]byte, []int) { return fileDescriptor0, []int{3} }
+
+func (m *Transaction) GetTxHex() []byte {
+	if m != nil {
+		return m.TxHex
+	}
+	return nil
+}
+
+type PublishResponse struct {
+	// *
+	// If blank, then no error occurred and the transaction was successfully
+	// published. If not the empty string, then a string representation of the
+	// broadcast error.
+	//
+	// TODO(roasbeef): map to a proper enum type
+	PublishError string `protobuf:"bytes,1,opt,name=publish_error,json=publishError" json:"publish_error,omitempty"`
+}
+
+func (m *PublishResponse) Reset()                    { *m = PublishResponse{} }
+func (m *PublishResponse) String() string            { return proto.CompactTextString(m) }
+func (*PublishResponse) ProtoMessage()               {}
+func (*PublishResponse) Descriptor() ([]byte, []int) { return fileDescriptor0, []int{4} }
+
+func (m *PublishResponse) GetPublishError() string {
+	if m != nil {
+		return m.PublishError
+	}
+	return ""
+}
+
+type SendOutputsRequest struct {
+	// *
+	// The number of satoshis per kilo weight that should be used when crafting
+	// this transaction.
+	SatPerKw int64 `protobuf:"varint,1,opt,name=sat_per_kw,json=satPerKw" json:"sat_per_kw,omitempty"`
+	// *
+	// A slice of the outputs that should be created in the transaction produced.
+	Outputs []*signrpc.TxOut `protobuf:"bytes,2,rep,name=outputs" json:"outputs,omitempty"`
+}
+
+func (m *SendOutputsRequest) Reset()                    { *m = SendOutputsRequest{} }
+func (m *SendOutputsRequest) String() string            { return proto.CompactTextString(m) }
+func (*SendOutputsRequest) ProtoMessage()               {}
+func (*SendOutputsRequest) Descriptor() ([]byte, []int) { return fileDescriptor0, []int{5} }
+
+func (m *SendOutputsRequest) GetSatPerKw() int64 {
+	if m != nil {
+		return m.SatPerKw
+	}
+	return 0
+}
+
+func (m *SendOutputsRequest) GetOutputs() []*signrpc.TxOut {
+	if m != nil {
+		return m.Outputs
+	}
+	return nil
+}
+
+type SendOutputsResponse struct {
+	// *
+	// The serialized transaction sent out on the network.
+	RawTx []byte `protobuf:"bytes,1,opt,name=raw_tx,json=rawTx,proto3" json:"raw_tx,omitempty"`
+}
+
+func (m *SendOutputsResponse) Reset()                    { *m = SendOutputsResponse{} }
+func (m *SendOutputsResponse) String() string            { return proto.CompactTextString(m) }
+func (*SendOutputsResponse) ProtoMessage()               {}
+func (*SendOutputsResponse) Descriptor() ([]byte, []int) { return fileDescriptor0, []int{6} }
+
+func (m *SendOutputsResponse) GetRawTx() []byte {
+	if m != nil {
+		return m.RawTx
+	}
+	return nil
+}
+
+type EstimateFeeRequest struct {
+	// *
+	// The number of confirmations to shoot for when estimating the fee.
+	ConfTarget int32 `protobuf:"varint,1,opt,name=conf_target,json=confTarget" json:"conf_target,omitempty"`
+}
+
+func (m *EstimateFeeRequest) Reset()                    { *m = EstimateFeeRequest{} }
+func (m *EstimateFeeRequest) String() string            { return proto.CompactTextString(m) }
+func (*EstimateFeeRequest) ProtoMessage()               {}
+func (*EstimateFeeRequest) Descriptor() ([]byte, []int) { return fileDescriptor0, []int{7} }
+
+func (m *EstimateFeeRequest) GetConfTarget() int32 {
+	if m != nil {
+		return m.ConfTarget
+	}
+	return 0
+}
+
+type EstimateFeeResponse struct {
+	// *
+	// The amount of satoshis per kw that should be used in order to reach the
+	// confirmation target in the request.
+	SatPerKw int64 `protobuf:"varint,1,opt,name=sat_per_kw,json=satPerKw" json:"sat_per_kw,omitempty"`
+}
+
+func (m *EstimateFeeResponse) Reset()                    { *m = EstimateFeeResponse{} }
+func (m *EstimateFeeResponse) String() string            { return proto.CompactTextString(m) }
+func (*EstimateFeeResponse) ProtoMessage()               {}
+func (*EstimateFeeResponse) Descriptor() ([]byte, []int) { return fileDescriptor0, []int{8} }
+
+func (m *EstimateFeeResponse) GetSatPerKw() int64 {
+	if m != nil {
+		return m.SatPerKw
+	}
+	return 0
+}
+
+func init() {
+	proto.RegisterType((*KeyReq)(nil), "walletrpc.KeyReq")
+	proto.RegisterType((*AddrRequest)(nil), "walletrpc.AddrRequest")
+	proto.RegisterType((*AddrResponse)(nil), "walletrpc.AddrResponse")
+	proto.RegisterType((*Transaction)(nil), "walletrpc.Transaction")
+	proto.RegisterType((*PublishResponse)(nil), "walletrpc.PublishResponse")
+	proto.RegisterType((*SendOutputsRequest)(nil), "walletrpc.SendOutputsRequest")
+	proto.RegisterType((*SendOutputsResponse)(nil), "walletrpc.SendOutputsResponse")
+	proto.RegisterType((*EstimateFeeRequest)(nil), "walletrpc.EstimateFeeRequest")
+	proto.RegisterType((*EstimateFeeResponse)(nil), "walletrpc.EstimateFeeResponse")
+}
+
+// Reference imports to suppress errors if they are not otherwise used.
+var _ context.Context
+var _ grpc.ClientConn
+
+// This is a compile-time assertion to ensure that this generated file
+// is compatible with the grpc package it is being compiled against.
+const _ = grpc.SupportPackageIsVersion4
+
+// Client API for WalletKit service
+
+type WalletKitClient interface {
+	// *
+	// DeriveNextKey attempts to derive the *next* key within the key family
+	// (account in BIP43) specified. This method should return the next external
+	// child within this branch.
+	DeriveNextKey(ctx context.Context, in *KeyReq, opts ...grpc.CallOption) (*signrpc.KeyDescriptor, error)
+	// *
+	// DeriveKey attempts to derive an arbitrary key specified by the passed
+	// KeyLocator.
+	DeriveKey(ctx context.Context, in *signrpc.KeyLocator, opts ...grpc.CallOption) (*signrpc.KeyDescriptor, error)
+	// *
+	// NextAddr returns the next unused address within the wallet.
+	NextAddr(ctx context.Context, in *AddrRequest, opts ...grpc.CallOption) (*AddrResponse, error)
+	// *
+	// PublishTransaction attempts to publish the passed transaction to the
+	// network. Once this returns without an error, the wallet will continually
+	// attempt to re-broadcast the transaction on start up, until it enters the
+	// chain.
+	PublishTransaction(ctx context.Context, in *Transaction, opts ...grpc.CallOption) (*PublishResponse, error)
+	// *
+	// SendOutputs is similar to the existing sendmany call in Bitcoind, and
+	// allows the caller to create a transaction that sends to several outputs at
+	// once. This is ideal when wanting to batch create a set of transactions.
+	SendOutputs(ctx context.Context, in *SendOutputsRequest, opts ...grpc.CallOption) (*SendOutputsResponse, error)
+	// *
+	// EstimateFee attempts to query the internal fee estimator of the wallet to
+	// determine the fee (in sat/kw) to attach to a transaction in order to
+	// achieve the confirmation target.
+	EstimateFee(ctx context.Context, in *EstimateFeeRequest, opts ...grpc.CallOption) (*EstimateFeeResponse, error)
+}
+
+type walletKitClient struct {
+	cc *grpc.ClientConn
+}
+
+func NewWalletKitClient(cc *grpc.ClientConn) WalletKitClient {
+	return &walletKitClient{cc}
+}
+
+func (c *walletKitClient) DeriveNextKey(ctx context.Context, in *KeyReq, opts ...grpc.CallOption) (*signrpc.KeyDescriptor, error) {
+	out := new(signrpc.KeyDescriptor)
+	err := grpc.Invoke(ctx, "/walletrpc.WalletKit/DeriveNextKey", in, out, c.cc, opts...)
+	if err != nil {
+		return nil, err
+	}
+	return out, nil
+}
+
+func (c *walletKitClient) DeriveKey(ctx context.Context, in *signrpc.KeyLocator, opts ...grpc.CallOption) (*signrpc.KeyDescriptor, error) {
+	out := new(signrpc.KeyDescriptor)
+	err := grpc.Invoke(ctx, "/walletrpc.WalletKit/DeriveKey", in, out, c.cc, opts...)
+	if err != nil {
+		return nil, err
+	}
+	return out, nil
+}
+
+func (c *walletKitClient) NextAddr(ctx context.Context, in *AddrRequest, opts ...grpc.CallOption) (*AddrResponse, error) {
+	out := new(AddrResponse)
+	err := grpc.Invoke(ctx, "/walletrpc.WalletKit/NextAddr", in, out, c.cc, opts...)
+	if err != nil {
+		return nil, err
+	}
+	return out, nil
+}
+
+func (c *walletKitClient) PublishTransaction(ctx context.Context, in *Transaction, opts ...grpc.CallOption) (*PublishResponse, error) {
+	out := new(PublishResponse)
+	err := grpc.Invoke(ctx, "/walletrpc.WalletKit/PublishTransaction", in, out, c.cc, opts...)
+	if err != nil {
+		return nil, err
+	}
+	return out, nil
+}
+
+func (c *walletKitClient) SendOutputs(ctx context.Context, in *SendOutputsRequest, opts ...grpc.CallOption) (*SendOutputsResponse, error) {
+	out := new(SendOutputsResponse)
+	err := grpc.Invoke(ctx, "/walletrpc.WalletKit/SendOutputs", in, out, c.cc, opts...)
+	if err != nil {
+		return nil, err
+	}
+	return out, nil
+}
+
+func (c *walletKitClient) EstimateFee(ctx context.Context, in *EstimateFeeRequest, opts ...grpc.CallOption) (*EstimateFeeResponse, error) {
+	out := new(EstimateFeeResponse)
+	err := grpc.Invoke(ctx, "/walletrpc.WalletKit/EstimateFee", in, out, c.cc, opts...)
+	if err != nil {
+		return nil, err
+	}
+	return out, nil
+}
+
+// Server API for WalletKit service
+
+type WalletKitServer interface {
+	// *
+	// DeriveNextKey attempts to derive the *next* key within the key family
+	// (account in BIP43) specified. This method should return the next external
+	// child within this branch.
+	DeriveNextKey(context.Context, *KeyReq) (*signrpc.KeyDescriptor, error)
+	// *
+	// DeriveKey attempts to derive an arbitrary key specified by the passed
+	// KeyLocator.
+	DeriveKey(context.Context, *signrpc.KeyLocator) (*signrpc.KeyDescriptor, error)
+	// *
+	// NextAddr returns the next unused address within the wallet.
+	NextAddr(context.Context, *AddrRequest) (*AddrResponse, error)
+	// *
+	// PublishTransaction attempts to publish the passed transaction to the
+	// network. Once this returns without an error, the wallet will continually
+	// attempt to re-broadcast the transaction on start up, until it enters the
+	// chain.
+	PublishTransaction(context.Context, *Transaction) (*PublishResponse, error)
+	// *
+	// SendOutputs is similar to the existing sendmany call in Bitcoind, and
+	// allows the caller to create a transaction that sends to several outputs at
+	// once. This is ideal when wanting to batch create a set of transactions.
+	SendOutputs(context.Context, *SendOutputsRequest) (*SendOutputsResponse, error)
+	// *
+	// EstimateFee attempts to query the internal fee estimator of the wallet to
+	// determine the fee (in sat/kw) to attach to a transaction in order to
+	// achieve the confirmation target.
+	EstimateFee(context.Context, *EstimateFeeRequest) (*EstimateFeeResponse, error)
+}
+
+func RegisterWalletKitServer(s *grpc.Server, srv WalletKitServer) {
+	s.RegisterService(&_WalletKit_serviceDesc, srv)
+}
+
+func _WalletKit_DeriveNextKey_Handler(srv interface{}, ctx context.Context, dec func(interface{}) error, interceptor grpc.UnaryServerInterceptor) (interface{}, error) {
+	in := new(KeyReq)
+	if err := dec(in); err != nil {
+		return nil, err
+	}
+	if interceptor == nil {
+		return srv.(WalletKitServer).DeriveNextKey(ctx, in)
+	}
+	info := &grpc.UnaryServerInfo{
+		Server:     srv,
+		FullMethod: "/walletrpc.WalletKit/DeriveNextKey",
+	}
+	handler := func(ctx context.Context, req interface{}) (interface{}, error) {
+		return srv.(WalletKitServer).DeriveNextKey(ctx, req.(*KeyReq))
+	}
+	return interceptor(ctx, in, info, handler)
+}
+
+func _WalletKit_DeriveKey_Handler(srv interface{}, ctx context.Context, dec func(interface{}) error, interceptor grpc.UnaryServerInterceptor) (interface{}, error) {
+	in := new(signrpc.KeyLocator)
+	if err := dec(in); err != nil {
+		return nil, err
+	}
+	if interceptor == nil {
+		return srv.(WalletKitServer).DeriveKey(ctx, in)
+	}
+	info := &grpc.UnaryServerInfo{
+		Server:     srv,
+		FullMethod: "/walletrpc.WalletKit/DeriveKey",
+	}
+	handler := func(ctx context.Context, req interface{}) (interface{}, error) {
+		return srv.(WalletKitServer).DeriveKey(ctx, req.(*signrpc.KeyLocator))
+	}
+	return interceptor(ctx, in, info, handler)
+}
+
+func _WalletKit_NextAddr_Handler(srv interface{}, ctx context.Context, dec func(interface{}) error, interceptor grpc.UnaryServerInterceptor) (interface{}, error) {
+	in := new(AddrRequest)
+	if err := dec(in); err != nil {
+		return nil, err
+	}
+	if interceptor == nil {
+		return srv.(WalletKitServer).NextAddr(ctx, in)
+	}
+	info := &grpc.UnaryServerInfo{
+		Server:     srv,
+		FullMethod: "/walletrpc.WalletKit/NextAddr",
+	}
+	handler := func(ctx context.Context, req interface{}) (interface{}, error) {
+		return srv.(WalletKitServer).NextAddr(ctx, req.(*AddrRequest))
+	}
+	return interceptor(ctx, in, info, handler)
+}
+
+func _WalletKit_PublishTransaction_Handler(srv interface{}, ctx context.Context, dec func(interface{}) error, interceptor grpc.UnaryServerInterceptor) (interface{}, error) {
+	in := new(Transaction)
+	if err := dec(in); err != nil {
+		return nil, err
+	}
+	if interceptor == nil {
+		return srv.(WalletKitServer).PublishTransaction(ctx, in)
+	}
+	info := &grpc.UnaryServerInfo{
+		Server:     srv,
+		FullMethod: "/walletrpc.WalletKit/PublishTransaction",
+	}
+	handler := func(ctx context.Context, req interface{}) (interface{}, error) {
+		return srv.(WalletKitServer).PublishTransaction(ctx, req.(*Transaction))
+	}
+	return interceptor(ctx, in, info, handler)
+}
+
+func _WalletKit_SendOutputs_Handler(srv interface{}, ctx context.Context, dec func(interface{}) error, interceptor grpc.UnaryServerInterceptor) (interface{}, error) {
+	in := new(SendOutputsRequest)
+	if err := dec(in); err != nil {
+		return nil, err
+	}
+	if interceptor == nil {
+		return srv.(WalletKitServer).SendOutputs(ctx, in)
+	}
+	info := &grpc.UnaryServerInfo{
+		Server:     srv,
+		FullMethod: "/walletrpc.WalletKit/SendOutputs",
+	}
+	handler := func(ctx context.Context, req interface{}) (interface{}, error) {
+		return srv.(WalletKitServer).SendOutputs(ctx, req.(*SendOutputsRequest))
+	}
+	return interceptor(ctx, in, info, handler)
+}
+
+func _WalletKit_EstimateFee_Handler(srv interface{}, ctx context.Context, dec func(interface{}) error, interceptor grpc.UnaryServerInterceptor) (interface{}, error) {
+	in := new(EstimateFeeRequest)
+	if err := dec(in); err != nil {
+		return nil, err
+	}
+	if interceptor == nil {
+		return srv.(WalletKitServer).EstimateFee(ctx, in)
+	}
+	info := &grpc.UnaryServerInfo{
+		Server:     srv,
+		FullMethod: "/walletrpc.WalletKit/EstimateFee",
+	}
+	handler := func(ctx context.Context, req interface{}) (interface{}, error) {
+		return srv.(WalletKitServer).EstimateFee(ctx, req.(*EstimateFeeRequest))
+	}
+	return interceptor(ctx, in, info, handler)
+}
+
+var _WalletKit_serviceDesc = grpc.ServiceDesc{
+	ServiceName: "walletrpc.WalletKit",
+	HandlerType: (*WalletKitServer)(nil),
+	Methods: []grpc.MethodDesc{
+		{
+			MethodName: "DeriveNextKey",
+			Handler:    _WalletKit_DeriveNextKey_Handler,
+		},
+		{
+			MethodName: "DeriveKey",
+			Handler:    _WalletKit_DeriveKey_Handler,
+		},
+		{
+			MethodName: "NextAddr",
+			Handler:    _WalletKit_NextAddr_Handler,
+		},
+		{
+			MethodName: "PublishTransaction",
+			Handler:    _WalletKit_PublishTransaction_Handler,
+		},
+		{
+			MethodName: "SendOutputs",
+			Handler:    _WalletKit_SendOutputs_Handler,
+		},
+		{
+			MethodName: "EstimateFee",
+			Handler:    _WalletKit_EstimateFee_Handler,
+		},
+	},
+	Streams:  []grpc.StreamDesc{},
+	Metadata: "walletrpc/walletkit.proto",
+}
+
+func init() { proto.RegisterFile("walletrpc/walletkit.proto", fileDescriptor0) }
+
+var fileDescriptor0 = []byte{
+	// 514 bytes of a gzipped FileDescriptorProto
+	0x1f, 0x8b, 0x08, 0x00, 0x00, 0x00, 0x00, 0x00, 0x02, 0xff, 0x7c, 0x53, 0x4d, 0x6f, 0xd3, 0x40,
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+	0xad, 0xda, 0xab, 0xc0, 0xcb, 0x1c, 0x33, 0x7f, 0x00, 0xfb, 0x86, 0xd2, 0xbb, 0x8d, 0x29, 0x8c,
+	0x29, 0xaa, 0xfa, 0x62, 0x2f, 0x01, 0x22, 0x4e, 0x4e, 0x88, 0xda, 0x59, 0x26, 0x45, 0x5e, 0xcb,
+	0xde, 0x8f, 0x38, 0x4d, 0x51, 0x4f, 0x12, 0x36, 0x82, 0xc7, 0xaa, 0xe4, 0x0f, 0x77, 0x4f, 0x5a,
+	0xa3, 0xee, 0xe9, 0x81, 0x55, 0xdd, 0x9f, 0x35, 0x4b, 0x6f, 0x63, 0xb2, 0xd7, 0x61, 0xf3, 0x1d,
+	0x0c, 0x36, 0xd4, 0xab, 0xce, 0x0e, 0xa1, 0xad, 0x79, 0xe2, 0x50, 0x3d, 0x83, 0xe6, 0xc9, 0x2c,
+	0x35, 0xdf, 0x03, 0xbb, 0x8c, 0x48, 0xac, 0x38, 0xe1, 0x15, 0xe2, 0xba, 0x97, 0xd7, 0xd0, 0x75,
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+	0x1b, 0x69, 0x55, 0x91, 0xff, 0xce, 0x70, 0xfa, 0xab, 0x05, 0x9d, 0xef, 0x85, 0x4b, 0x26, 0x82,
+	0xd8, 0x39, 0xf4, 0x2f, 0x50, 0x8b, 0x9f, 0xf8, 0x05, 0x53, 0x9a, 0x60, 0xc6, 0x9e, 0x59, 0xb5,
+	0x85, 0xac, 0xd2, 0x03, 0xc6, 0x51, 0x3d, 0xe4, 0x04, 0xb3, 0x0b, 0x8c, 0x5c, 0x2d, 0x42, 0x52,
+	0x9a, 0x7d, 0x84, 0x4e, 0x99, 0x9b, 0xe7, 0x0d, 0x9a, 0xa4, 0x1b, 0xe5, 0x72, 0x52, 0xfa, 0xc1,
+	0xcc, 0x4f, 0xb0, 0x9f, 0xd7, 0xcb, 0x1d, 0xc0, 0x8e, 0x1a, 0x05, 0x1b, 0x0e, 0x31, 0x9e, 0x6f,
+	0xe1, 0xd5, 0x78, 0xd7, 0xc0, 0xaa, 0x85, 0x37, 0xdd, 0xd1, 0x94, 0x69, 0xe0, 0x86, 0xd1, 0xc0,
+	0xff, 0xf6, 0xc9, 0x0d, 0x74, 0x1b, 0x4b, 0x62, 0xc7, 0x0d, 0xea, 0xb6, 0x35, 0x8c, 0x57, 0x0f,
+	0x85, 0xff, 0xa8, 0x35, 0xb6, 0xb1, 0xa1, 0xb6, 0xbd, 0xdc, 0x0d, 0xb5, 0x7f, 0x2c, 0x71, 0xde,
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+	0x00, 0x00,
+}

lnrpc/walletrpc/walletkit.proto

@@ -0,0 +1,122 @@
+syntax = "proto3";
+
+import "github.com/lightningnetwork/lnd/lnrpc/signrpc/signer.proto";
+
+package walletrpc;
+
+message KeyReq {
+    /**
+    Is the key finger print of the root pubkey that this request is targeting.
+    This allows the WalletKit to possibly serve out keys for multiple HD chains
+    via public derivation.
+    */
+    int32 key_finger_print = 1;
+
+    /**
+    The target key family to derive a key from. In other contexts, this is
+    known as the "account".
+    */
+    int32 key_family = 2;
+}
+
+message AddrRequest{
+    // No fields, as we always give out a p2wkh address.
+}
+message AddrResponse {
+    /**
+    The address encoded using a bech32 format.
+    */
+    string addr = 1;
+}
+
+message Transaction {
+    /**
+    The raw serialized transaction.
+    */
+    bytes tx_hex = 1;
+}
+message PublishResponse {
+    /**
+    If blank, then no error occurred and the transaction was successfully
+    published. If not the empty string, then a string representation of the
+    broadcast error.
+
+    TODO(roasbeef): map to a proper enum type
+    */
+    string publish_error = 1;
+}
+
+message SendOutputsRequest {
+    /**
+    The number of satoshis per kilo weight that should be used when crafting
+    this transaction.
+    */
+    int64 sat_per_kw = 1;
+
+    /**
+    A slice of the outputs that should be created in the transaction produced.
+    */
+    repeated signrpc.TxOut outputs = 2;
+}
+message SendOutputsResponse {
+    /**
+    The serialized transaction sent out on the network.
+    */
+    bytes raw_tx = 1;
+}
+
+message EstimateFeeRequest {
+    /**
+    The number of confirmations to shoot for when estimating the fee.
+    */
+    int32 conf_target = 1;
+}
+message EstimateFeeResponse {
+    /**
+    The amount of satoshis per kw that should be used in order to reach the
+    confirmation target in the request.
+    */
+    int64 sat_per_kw = 1;
+}
+
+service WalletKit {
+    /**
+    DeriveNextKey attempts to derive the *next* key within the key family
+    (account in BIP43) specified. This method should return the next external
+    child within this branch.
+    */
+    rpc DeriveNextKey(KeyReq) returns (signrpc.KeyDescriptor);
+
+    /**
+    DeriveKey attempts to derive an arbitrary key specified by the passed
+    KeyLocator. 
+    */
+    rpc DeriveKey(signrpc.KeyLocator) returns (signrpc.KeyDescriptor);
+
+    /**
+    NextAddr returns the next unused address within the wallet.
+    */
+    rpc NextAddr(AddrRequest) returns (AddrResponse);
+
+    /**
+    PublishTransaction attempts to publish the passed transaction to the
+    network. Once this returns without an error, the wallet will continually
+    attempt to re-broadcast the transaction on start up, until it enters the
+    chain.
+    */
+    rpc PublishTransaction(Transaction) returns (PublishResponse);
+
+    /**
+    SendOutputs is similar to the existing sendmany call in Bitcoind, and
+    allows the caller to create a transaction that sends to several outputs at
+    once. This is ideal when wanting to batch create a set of transactions.
+    */
+    rpc SendOutputs(SendOutputsRequest) returns (SendOutputsResponse);
+
+    /**
+    EstimateFee attempts to query the internal fee estimator of the wallet to
+    determine the fee (in sat/kw) to attach to a transaction in order to
+    achieve the confirmation target.
+    */
+    rpc EstimateFee(EstimateFeeRequest) returns (EstimateFeeResponse);
+}

lnrpc/walletrpc/walletkit_server.go

@@ -0,0 +1,343 @@
+// +build walletrpc
+
+package walletrpc
+
+import (
+	"bytes"
+	fmt "fmt"
+	"io/ioutil"
+	"os"
+	"path/filepath"
+
+	"github.com/btcsuite/btcd/wire"
+	"github.com/lightningnetwork/lnd/keychain"
+	"github.com/lightningnetwork/lnd/lnrpc"
+	signrpc "github.com/lightningnetwork/lnd/lnrpc/signrpc"
+	"github.com/lightningnetwork/lnd/lnwallet"
+	context "golang.org/x/net/context"
+	grpc "google.golang.org/grpc"
+	"gopkg.in/macaroon-bakery.v2/bakery"
+)
+
+const (
+	// subServerName is the name of the sub rpc server. We'll use this name
+	// to register ourselves, and we also require that the main
+	// SubServerConfigDispatcher instance recognize as the name of our
+	subServerName = "WalletKitRPC"
+)
+
+var (
+	// macaroonOps are the set of capabilities that our minted macaroon (if
+	// it doesn't already exist) will have.
+	macaroonOps = []bakery.Op{
+		{
+			Entity: "address",
+			Action: "write",
+		},
+		{
+			Entity: "address",
+			Action: "read",
+		},
+		{
+			Entity: "onchain",
+			Action: "write",
+		},
+		{
+			Entity: "onchain",
+			Action: "read",
+		},
+	}
+
+	// macPermissions maps RPC calls to the permissions they require.
+	macPermissions = map[string][]bakery.Op{
+		"/walletrpc.WalletKit/DeriveNextKey": {{
+			Entity: "address",
+			Action: "read",
+		}},
+		"/walletrpc.WalletKit/DeriveKey": {{
+			Entity: "address",
+			Action: "read",
+		}},
+		"/walletrpc.WalletKit/NextAddr": {{
+			Entity: "address",
+			Action: "read",
+		}},
+		"/walletrpc.WalletKit/PublishTransaction": {{
+			Entity: "onchain",
+			Action: "write",
+		}},
+		"/walletrpc.WalletKit/SendOutputs": {{
+			Entity: "onchain",
+			Action: "write",
+		}},
+		"/walletrpc.WalletKit/EstimateFee": {{
+			Entity: "onchain",
+			Action: "read",
+		}},
+	}
+
+	// DefaultWalletKitMacFilename is the default name of the wallet kit
+	// macaroon that we expect to find via a file handle within the main
+	// configuration file in this package.
+	DefaultWalletKitMacFilename = "walletkit.macaroon"
+)
+
+// WalletKit is a sub-RPC server that exposes a tool kit which allows clients
+// to execute common wallet operations. This includes requesting new addresses,
+// keys (for contracts!), and publishing transactions.
+type WalletKit struct {
+	cfg *Config
+}
+
+// A compile time check to ensure that WalletKit fully implements the
+// WalletKitServer gRPC service.
+var _ WalletKitServer = (*WalletKit)(nil)
+
+// fileExists reports whether the named file or directory exists.
+func fileExists(name string) bool {
+	if _, err := os.Stat(name); err != nil {
+		if os.IsNotExist(err) {
+			return false
+		}
+	}
+	return true
+}
+
+// New creates a new instance of the WalletKit sub-RPC server.
+func New(cfg *Config) (*WalletKit, lnrpc.MacaroonPerms, error) {
+	// If the path of the wallet kit macaroon wasn't specified, then we'll
+	// assume that it's found at the default network directory.
+	if cfg.WalletKitMacPath == "" {
+		cfg.WalletKitMacPath = filepath.Join(
+			cfg.NetworkDir, DefaultWalletKitMacFilename,
+		)
+	}
+
+	// Now that we know the full path of the wallet kit macaroon, we can
+	// check to see if we need to create it or not.
+	macFilePath := cfg.WalletKitMacPath
+	if !fileExists(macFilePath) && cfg.MacService != nil {
+		log.Infof("Baking macaroons for WaleltKit RPC Server at: %v",
+			macFilePath)
+
+		// At this point, we know that the wallet kit macaroon doesn't
+		// yet, exist, so we need to create it with the help of the
+		// main macaroon service.
+		walletKitMac, err := cfg.MacService.Oven.NewMacaroon(
+			context.Background(), bakery.LatestVersion, nil,
+			macaroonOps...,
+		)
+		if err != nil {
+			return nil, nil, err
+		}
+		walletKitMacBytes, err := walletKitMac.M().MarshalBinary()
+		if err != nil {
+			return nil, nil, err
+		}
+		err = ioutil.WriteFile(macFilePath, walletKitMacBytes, 0644)
+		if err != nil {
+			os.Remove(macFilePath)
+			return nil, nil, err
+		}
+	}
+
+	walletKit := &WalletKit{
+		cfg: cfg,
+	}
+
+	return walletKit, macPermissions, nil
+}
+
+// Start launches any helper goroutines required for the sub-server to function.
+//
+// NOTE: This is part of the lnrpc.SubServer interface.
+func (w *WalletKit) Start() error {
+	return nil
+}
+
+// Stop signals any active goroutines for a graceful closure.
+//
+// NOTE: This is part of the lnrpc.SubServer interface.
+func (w *WalletKit) Stop() error {
+	return nil
+}
+
+// Name returns a unique string representation of the sub-server. This can be
+// used to identify the sub-server and also de-duplicate them.
+//
+// NOTE: This is part of the lnrpc.SubServer interface.
+func (w *WalletKit) Name() string {
+	return subServerName
+}
+
+// RegisterWithRootServer will be called by the root gRPC server to direct a
+// sub RPC server to register itself with the main gRPC root server. Until this
+// is called, each sub-server won't be able to have requests routed towards it.
+//
+// NOTE: This is part of the lnrpc.SubServer interface.
+func (w *WalletKit) RegisterWithRootServer(grpcServer *grpc.Server) error {
+	// We make sure that we register it with the main gRPC server to ensure
+	// all our methods are routed properly.
+	RegisterWalletKitServer(grpcServer, w)
+
+	log.Debugf("WalletKit RPC server successfully registered with " +
+		"root gRPC server")
+
+	return nil
+}
+
+// DeriveNextKey attempts to derive the *next* key within the key family
+// (account in BIP43) specified. This method should return the next external
+// child within this branch.
+func (w *WalletKit) DeriveNextKey(ctx context.Context,
+	req *KeyReq) (*signrpc.KeyDescriptor, error) {
+
+	nextKeyDesc, err := w.cfg.KeyRing.DeriveNextKey(
+		keychain.KeyFamily(req.KeyFamily),
+	)
+	if err != nil {
+		return nil, err
+	}
+
+	return &signrpc.KeyDescriptor{
+		KeyLoc: &signrpc.KeyLocator{
+			KeyFamily: int32(nextKeyDesc.Family),
+			KeyIndex:  int32(nextKeyDesc.Index),
+		},
+		RawKeyBytes: nextKeyDesc.PubKey.SerializeCompressed(),
+	}, nil
+}
+
+// DeriveKey attempts to derive an arbitrary key specified by the passed
+// KeyLocator.
+func (w *WalletKit) DeriveKey(ctx context.Context,
+	req *signrpc.KeyLocator) (*signrpc.KeyDescriptor, error) {
+
+	keyDesc, err := w.cfg.KeyRing.DeriveKey(keychain.KeyLocator{
+		Family: keychain.KeyFamily(req.KeyFamily),
+		Index:  uint32(req.KeyIndex),
+	})
+	if err != nil {
+		return nil, err
+	}
+
+	return &signrpc.KeyDescriptor{
+		KeyLoc: &signrpc.KeyLocator{
+			KeyFamily: int32(keyDesc.Family),
+			KeyIndex:  int32(keyDesc.Index),
+		},
+		RawKeyBytes: keyDesc.PubKey.SerializeCompressed(),
+	}, nil
+}
+
+// NextAddr returns the next unused address within the wallet.
+func (w *WalletKit) NextAddr(ctx context.Context,
+	req *AddrRequest) (*AddrResponse, error) {
+
+	addr, err := w.cfg.Wallet.NewAddress(lnwallet.WitnessPubKey, false)
+	if err != nil {
+		return nil, err
+	}
+
+	return &AddrResponse{
+		Addr: addr.String(),
+	}, nil
+}
+
+// Attempts to publish the passed transaction to the network. Once this returns
+// without an error, the wallet will continually attempt to re-broadcast the
+// transaction on start up, until it enters the chain.
+func (w *WalletKit) PublishTransaction(ctx context.Context,
+	req *Transaction) (*PublishResponse, error) {
+
+	switch {
+	// If the client doesn't specify a transaction, then there's nothing to
+	// publish.
+	case len(req.TxHex) == 0:
+		return nil, fmt.Errorf("must provide a transaction to " +
+			"publish")
+	}
+
+	tx := &wire.MsgTx{}
+	txReader := bytes.NewReader(req.TxHex)
+	if err := tx.Deserialize(txReader); err != nil {
+		return nil, err
+	}
+
+	err := w.cfg.Wallet.PublishTransaction(tx)
+	if err != nil {
+		return nil, err
+	}
+
+	return &PublishResponse{}, nil
+}
+
+// SendOutputs is similar to the existing sendmany call in Bitcoind, and allows
+// the caller to create a transaction that sends to several outputs at once.
+// This is ideal when wanting to batch create a set of transactions.
+func (w *WalletKit) SendOutputs(ctx context.Context,
+	req *SendOutputsRequest) (*SendOutputsResponse, error) {
+
+	switch {
+	// If the client didn't specify any outputs to create, then  we can't
+	// proceed .
+	case len(req.Outputs) == 0:
+		return nil, fmt.Errorf("must specify at least one output " +
+			"to create")
+	}
+
+	// Before we can request this transaction to be created, we'll need to
+	// amp the protos back into the format that the internal wallet will
+	// recognize.
+	outputsToCreate := make([]*wire.TxOut, 0, len(req.Outputs))
+	for _, output := range req.Outputs {
+		outputsToCreate = append(outputsToCreate, &wire.TxOut{
+			Value:    output.Value,
+			PkScript: output.PkScript,
+		})
+	}
+
+	// Now that we have the outputs mapped, we can request that the wallet
+	// attempt to create this transaction.
+	tx, err := w.cfg.Wallet.SendOutputs(
+		outputsToCreate, lnwallet.SatPerKWeight(req.SatPerKw),
+	)
+	if err != nil {
+		return nil, err
+	}
+
+	var b bytes.Buffer
+	if err := tx.Serialize(&b); err != nil {
+		return nil, err
+	}
+
+	return &SendOutputsResponse{
+		RawTx: b.Bytes(),
+	}, nil
+}
+
+// EstimateFee attempts to query the internal fee estimator of the wallet to
+// determine the fee (in sat/kw) to attach to a transaction in order to achieve
+// the confirmation target.
+func (w *WalletKit) EstimateFee(ctx context.Context,
+	req *EstimateFeeRequest) (*EstimateFeeResponse, error) {
+
+	switch {
+	// A confirmation target of zero doesn't make any sense. Similarly, we
+	// reject confirmation targets of 1 as they're unreasonable.
+	case req.ConfTarget == 0 || req.ConfTarget == 1:
+		return nil, fmt.Errorf("confirmation target must be greater " +
+			"than 1")
+	}
+
+	satPerKw, err := w.cfg.FeeEstimator.EstimateFeePerKW(
+		uint32(req.ConfTarget),
+	)
+	if err != nil {
+		return nil, err
+	}
+
+	return &EstimateFeeResponse{
+		SatPerKw: int64(satPerKw),
+	}, nil
+}

log.go

@@ -20,6 +20,7 @@ import (
 	"github.com/lightningnetwork/lnd/discovery"
 	"github.com/lightningnetwork/lnd/htlcswitch"
 	"github.com/lightningnetwork/lnd/lnrpc/signrpc"
+	"github.com/lightningnetwork/lnd/lnrpc/walletrpc"
 	"github.com/lightningnetwork/lnd/lnwallet"
 	"github.com/lightningnetwork/lnd/routing"
 	"github.com/lightningnetwork/lnd/signal"
@@ -67,6 +68,7 @@ var (
 	sphxLog = build.NewSubLogger("SPHX", backendLog.Logger)
 	swprLog = build.NewSubLogger("SWPR", backendLog.Logger)
 	sgnrLog = build.NewSubLogger("SGNR", backendLog.Logger)
+	wlktLog = build.NewSubLogger("WLKT", backendLog.Logger)
 )
 
 // Initialize package-global logger variables.
@@ -85,6 +87,7 @@ func init() {
 	signal.UseLogger(ltndLog)
 	sweep.UseLogger(swprLog)
 	signrpc.UseLogger(sgnrLog)
+	walletrpc.UseLogger(wlktLog)
 }
 
 // subsystemLoggers maps each subsystem identifier to its associated logger.
@@ -109,6 +112,7 @@ var subsystemLoggers = map[string]btclog.Logger{
 	"SPHX": sphxLog,
 	"SWPR": swprLog,
 	"SGNR": sgnrLog,
+	"WLKT": wlktLog,
 }
 
 // initLogRotator initializes the logging rotator to write logs to logFile and

rpcserver.go

@@ -129,6 +129,10 @@ var (
 			Entity: "invoices",
 			Action: "write",
 		},
+		{
+			Entity: "signer",
+			Action: "generate",
+		},
 	}
 
 	// invoicePermissions is a slice of all the entities that allows a user

subrpcserver_config.go

@@ -5,6 +5,7 @@ import (
 	"reflect"
 
 	"github.com/lightningnetwork/lnd/lnrpc/signrpc"
+	"github.com/lightningnetwork/lnd/lnrpc/walletrpc"
 	"github.com/lightningnetwork/lnd/macaroons"
 )
 
@@ -18,6 +19,12 @@ type subRPCServerConfigs struct {
 	// SignRPC is a sub-RPC server that exposes signing of arbitrary inputs
 	// as a gRPC service.
 	SignRPC *signrpc.Config `group:"signrpc" namespace:"signrpc"`
+
+	// WalletKitRPC is a sub-RPC server that exposes functionality allowing
+	// a client to send transactions through a wallet, publish them, and
+	// also requests keys and addresses under control of the backing
+	// wallet.
+	WalletKitRPC *walletrpc.Config `group:"walletrpc" namespace:"walletrpc"`
 }
 
 // PopulateDependencies attempts to iterate through all the sub-server configs
@@ -66,6 +73,25 @@ func (s *subRPCServerConfigs) PopulateDependencies(cc *chainControl,
 				reflect.ValueOf(cc.signer),
 			)
 
+		case *walletrpc.Config:
+			subCfgValue := extractReflectValue(cfg)
+
+			subCfgValue.FieldByName("NetworkDir").Set(
+				reflect.ValueOf(networkDir),
+			)
+			subCfgValue.FieldByName("MacService").Set(
+				reflect.ValueOf(macService),
+			)
+			subCfgValue.FieldByName("FeeEstimator").Set(
+				reflect.ValueOf(cc.feeEstimator),
+			)
+			subCfgValue.FieldByName("Wallet").Set(
+				reflect.ValueOf(cc.wallet),
+			)
+			subCfgValue.FieldByName("KeyRing").Set(
+				reflect.ValueOf(cc.keyRing),
+			)
+
 		default:
 			return fmt.Errorf("unknown field: %v, %T", fieldName,
 				cfg)
@@ -88,7 +114,6 @@ func (s *subRPCServerConfigs) FetchConfig(subServerName string) (interface{}, bo
 	// Now that we have the value of the struct, we can check to see if it
 	// has an attribute with the same name as the subServerName.
 	configVal := selfVal.FieldByName(subServerName)
-	configValElem := configVal.Elem()
 
 	// We'll now ensure that this field actually exists in this value. If
 	// not, then we'll return false for the ok value to indicate to the
@@ -97,6 +122,8 @@ func (s *subRPCServerConfigs) FetchConfig(subServerName string) (interface{}, bo
 		return nil, false
 	}
 
+	configValElem := configVal.Elem()
+
 	// If a config of this type is found, it doesn't have any fields, then
 	// it's the same as if it wasn't present. This can happen if the build
 	// tag for the sub-server is inactive.