lnrpc: add peersrpc subsever

lnrpc/peersrpc/config_active.go

@@ -0,0 +1,6 @@
+//go:build peersrpc
+// +build peersrpc
+
+package peersrpc
+
+type Config struct{}

lnrpc/peersrpc/config_default.go

@@ -0,0 +1,7 @@
+//go:build !peersrpc
+// +build !peersrpc
+
+package peersrpc
+
+// Config is empty for non-peersrpc builds.
+type Config struct{}

lnrpc/peersrpc/driver.go

@@ -0,0 +1,55 @@
+//go:build peersrpc
+// +build peersrpc
+
+package peersrpc
+
+import (
+	"fmt"
+
+	"github.com/lightningnetwork/lnd/lnrpc"
+)
+
+// createNewSubServer is a helper method that will create the new 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) (
+	*Server, 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.
+	subServerConf, 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 := subServerConf.(*Config)
+	if !ok {
+		return nil, nil, fmt.Errorf("wrong type of config for "+
+			"subserver %s, expected %T got %T", subServerName,
+			&Config{}, subServerConf)
+	}
+
+	return New(config)
+}
+
+func init() {
+	subServer := &lnrpc.SubServerDriver{
+		SubServerName: subServerName,
+		NewGrpcHandler: func() lnrpc.GrpcHandler {
+			return &ServerShell{}
+		},
+	}
+
+	// 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/peersrpc/log.go

@@ -0,0 +1,48 @@
+package peersrpc
+
+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
+
+// Subsystem defines the logging code for this subsystem.
+const Subsystem = "PRPC"
+
+// The default amount of logging is none.
+func init() {
+	UseLogger(build.NewSubLogger(Subsystem, 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 // nolint:unused
+
+// 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 { // nolint:unused
+	return logClosure(c)
+}

lnrpc/peersrpc/peers_server.go

@@ -0,0 +1,142 @@
+//go:build peersrpc
+// +build peersrpc
+
+package peersrpc
+
+import (
+	"context"
+	"sync/atomic"
+
+	"github.com/grpc-ecosystem/grpc-gateway/v2/runtime"
+	"github.com/lightningnetwork/lnd/lnrpc"
+	"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 tt as the name of our
+	// RPC service.
+	subServerName = "PeersRPC"
+)
+
+var (
+	// macPermissions maps RPC calls to the permissions they require.
+	macPermissions = map[string][]bakery.Op{}
+)
+
+// ServerShell is a shell struct holding a reference to the actual sub-server.
+// It is used to register the gRPC sub-server with the root server before we
+// have the necessary dependencies to populate the actual sub-server.
+type ServerShell struct {
+	PeersServer
+}
+
+// Server is a sub-server of the main RPC server: the peers RPC. This sub
+// RPC server allows to intereact with our Peers in the Lightning Network.
+type Server struct {
+	started  int32 // To be used atomically.
+	shutdown int32 // To be used atomically.
+
+	// Required by the grpc-gateway/v2 library for forward compatibility.
+	// Must be after the atomically used variables to not break struct
+	// alignment.
+	UnimplementedPeersServer
+
+	cfg *Config
+}
+
+// A compile time check to ensure that Server fully implements the PeersServer
+// gRPC service.
+var _ PeersServer = (*Server)(nil)
+
+// New returns a new instance of the peersrpc Peers sub-server. We also
+// return the set of permissions for the macaroons that we may create within
+// this method. If the macaroons we need aren't found in the filepath, then
+// we'll create them on start up. If we're unable to locate, or create the
+// macaroons we need, then we'll return with an error.
+func New(cfg *Config) (*Server, lnrpc.MacaroonPerms, error) {
+	server := &Server{
+		cfg: cfg,
+	}
+
+	return server, macPermissions, nil
+}
+
+// Start launches any helper goroutines required for the Server to function.
+//
+// NOTE: This is part of the lnrpc.SubServer interface.
+func (s *Server) Start() error {
+	if atomic.AddInt32(&s.started, 1) != 1 {
+		return nil
+	}
+
+	return nil
+}
+
+// Stop signals any active goroutines for a graceful closure.
+//
+// NOTE: This is part of the lnrpc.SubServer interface.
+func (s *Server) Stop() error {
+	if atomic.AddInt32(&s.shutdown, 1) != 1 {
+		return nil
+	}
+
+	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 (s *Server) 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.GrpcHandler interface.
+func (r *ServerShell) 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.
+	RegisterPeersServer(grpcServer, r)
+
+	log.Debugf("Peers RPC server successfully register with root " +
+		"gRPC server")
+
+	return nil
+}
+
+// RegisterWithRestServer will be called by the root REST mux to direct a sub
+// RPC server to register itself with the main REST mux 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.GrpcHandler interface.
+func (r *ServerShell) RegisterWithRestServer(ctx context.Context,
+	mux *runtime.ServeMux, dest string, opts []grpc.DialOption) error {
+
+	return nil
+}
+
+// CreateSubServer populates the subserver's dependencies using the passed
+// SubServerConfigDispatcher. This method should fully initialize the
+// sub-server instance, making it ready for action. It returns the macaroon
+// permissions that the sub-server wishes to pass on to the root server for all
+// methods routed towards it.
+//
+// NOTE: This is part of the lnrpc.GrpcHandler interface.
+func (r *ServerShell) CreateSubServer(configRegistry lnrpc.SubServerConfigDispatcher) (
+	lnrpc.SubServer, lnrpc.MacaroonPerms, error) {
+
+	subServer, macPermissions, err := createNewSubServer(configRegistry)
+	if err != nil {
+		return nil, nil, err
+	}
+
+	r.PeersServer = subServer
+	return subServer, macPermissions, nil
+}