lnrpc/verrpc: add Versioner RPC server

lnrpc/verrpc/server.go

@@ -0,0 +1,75 @@
+package verrpc
+
+import (
+	"context"
+
+	"github.com/lightningnetwork/lnd/build"
+	"google.golang.org/grpc"
+	"gopkg.in/macaroon-bakery.v2/bakery"
+)
+
+const subServerName = "VersionRPC"
+
+var macPermissions = map[string][]bakery.Op{
+	"/verrpc.Versioner/GetVersion": {{
+		Entity: "info",
+		Action: "read",
+	}},
+}
+
+// Server is an rpc server that supports querying for information about the
+// running binary.
+type Server struct{}
+
+// Start launches any helper goroutines required for the rpcServer to function.
+//
+// NOTE: This is part of the lnrpc.SubServer interface.
+func (s *Server) Start() error {
+	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 {
+	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.SubServer interface.
+func (s *Server) RegisterWithRootServer(grpcServer *grpc.Server) error {
+	RegisterVersionerServer(grpcServer, s)
+
+	log.Debugf("Versioner RPC server successfully registered with root " +
+		"gRPC server")
+
+	return nil
+}
+
+// GetVersion returns information about the compiled binary.
+func (s *Server) GetVersion(_ context.Context,
+	_ *VersionRequest) (*Version, error) {
+
+	return &Version{
+		Commit:        build.Commit,
+		CommitHash:    build.CommitHash,
+		Version:       build.Version(),
+		AppMajor:      uint32(build.AppMajor),
+		AppMinor:      uint32(build.AppMinor),
+		AppPatch:      uint32(build.AppPatch),
+		AppPreRelease: build.AppPreRelease,
+		BuildTags:     build.Tags(),
+		GoVersion:     build.GoVersion,
+	}, nil
+}