Feature gate the new RPC server.

Instead of replacing the legacy server, implement but do not enable
the new experimental gRPC server by default.  This can only be enabled
by setting a listen address (and one that does not conflict with any
of the legacy server's addresses) for the new server.

config.go

@@ -1,5 +1,5 @@
 /*
- * Copyright (c) 2013-2015 The btcsuite developers
+ * Copyright (c) 2013-2016 The btcsuite developers
  *
  * Permission to use, copy, modify, and distribute this software for any
  * purpose with or without fee is hereby granted, provided that the above
@@ -85,18 +85,28 @@ type config struct {
 	ProxyPass        string `long:"proxypass" default-mask:"-" description:"Password for proxy server"`
 
 	// RPC server options
-	RPCListeners     []string `long:"rpclisten" description:"Listen for RPC connections on this interface/port (default port: 18332, mainnet: 8332, simnet: 18554)"`
-	RPCCert          string   `long:"rpccert" description:"File containing the certificate file"`
-	RPCKey           string   `long:"rpckey" description:"File containing the certificate key"`
-	DisableServerTLS bool     `long:"noservertls" description:"Disable TLS for the RPC server -- NOTE: This is only allowed if the RPC server is bound to localhost"`
-
-	// Options specific to the legacy JSON-RPC server
-	LegacyRPCListeners     []string `long:"legacyrpclisten" description:"Listen for legacy RPC connections on this interface/port"`
-	LegacyRPCMaxClients    int64    `long:"legacyrpcmaxclients" description:"Max number of legacy RPC clients for standard connections"`
-	LegacyRPCMaxWebsockets int64    `long:"legacyrpcmaxwebsockets" description:"Max number of legacy RPC websocket connections"`
+	//
+	// The legacy server is still enabled by default (and eventually will be
+	// replaced with the experimental server) so prepare for that change by
+	// renaming the struct fields (but not the configuration options).
+	//
+	// Usernames can also be used for the consensus RPC client, so they
+	// aren't considered legacy.
+	RPCCert                string   `long:"rpccert" description:"File containing the certificate file"`
+	RPCKey                 string   `long:"rpckey" description:"File containing the certificate key"`
+	DisableServerTLS       bool     `long:"noservertls" description:"Disable TLS for the RPC server -- NOTE: This is only allowed if the RPC server is bound to localhost"`
+	LegacyRPCListeners     []string `long:"rpclisten" description:"Listen for legacy RPC connections on this interface/port (default port: 18332, mainnet: 8332, simnet: 18554)"`
+	LegacyRPCMaxClients    int64    `long:"rpcmaxclients" description:"Max number of legacy RPC clients for standard connections"`
+	LegacyRPCMaxWebsockets int64    `long:"rpcmaxwebsockets" description:"Max number of legacy RPC websocket connections"`
 	Username               string   `short:"u" long:"username" description:"Username for legacy RPC and btcd authentication (if btcdusername is unset)"`
 	Password               string   `short:"P" long:"password" default-mask:"-" description:"Password for legacy RPC and btcd authentication (if btcdpassword is unset)"`
 
+	// EXPERIMENTAL RPC server options
+	//
+	// These options will change (and require changes to config files, etc.)
+	// when the new gRPC server is enabled.
+	ExperimentalRPCListeners []string `long:"experimentalrpclisten" description:"Listen for RPC connections on this interface/port"`
+
 	// Deprecated options
 	KeypoolSize uint `short:"k" long:"keypoolsize" description:"DEPRECATED -- Maximum number of addresses in keypool"`
 }
@@ -501,46 +511,46 @@ func loadConfig() (*config, []string, error) {
 	}
 
 	// Only set default RPC listeners when there are no listeners set for
-	// the legacy RPC server.  This is required to prevent the new RPC
+	// the experimental RPC server.  This is required to prevent the old RPC
 	// server from sharing listen addresses, since it is impossible to
 	// remove defaults from go-flags slice options without assigning
 	// specific behavior to a particular string.
-	if len(cfg.RPCListeners) == 0 && len(cfg.LegacyRPCListeners) == 0 {
+	if len(cfg.ExperimentalRPCListeners) == 0 && len(cfg.LegacyRPCListeners) == 0 {
 		addrs, err := net.LookupHost("localhost")
 		if err != nil {
 			return nil, nil, err
 		}
-		cfg.RPCListeners = make([]string, 0, len(addrs))
+		cfg.LegacyRPCListeners = make([]string, 0, len(addrs))
 		for _, addr := range addrs {
 			addr = net.JoinHostPort(addr, activeNet.RPCServerPort)
-			cfg.RPCListeners = append(cfg.RPCListeners, addr)
+			cfg.LegacyRPCListeners = append(cfg.LegacyRPCListeners, addr)
 		}
 	}
 
 	// Add default port to all rpc listener addresses if needed and remove
 	// duplicate addresses.
-	cfg.RPCListeners, err = cfgutil.NormalizeAddresses(cfg.RPCListeners,
-		activeNet.RPCServerPort)
+	cfg.LegacyRPCListeners, err = cfgutil.NormalizeAddresses(
+		cfg.LegacyRPCListeners, activeNet.RPCServerPort)
 	if err != nil {
 		fmt.Fprintf(os.Stderr,
-			"Invalid network address in RPC listeners: %v\n", err)
+			"Invalid network address in legacy RPC listeners: %v\n", err)
 		return nil, nil, err
 	}
-	cfg.LegacyRPCListeners, err = cfgutil.NormalizeAddresses(
-		cfg.LegacyRPCListeners, activeNet.RPCServerPort)
+	cfg.ExperimentalRPCListeners, err = cfgutil.NormalizeAddresses(
+		cfg.ExperimentalRPCListeners, activeNet.RPCServerPort)
 	if err != nil {
 		fmt.Fprintf(os.Stderr,
-			"Invalid network address in legacy RPC listeners: %v\n", err)
+			"Invalid network address in RPC listeners: %v\n", err)
 		return nil, nil, err
 	}
 
 	// Both RPC servers may not listen on the same interface/port.
-	if len(cfg.RPCListeners) > 0 && len(cfg.LegacyRPCListeners) > 0 {
-		seenAddresses := make(map[string]struct{}, len(cfg.RPCListeners))
-		for _, addr := range cfg.RPCListeners {
+	if len(cfg.LegacyRPCListeners) > 0 && len(cfg.ExperimentalRPCListeners) > 0 {
+		seenAddresses := make(map[string]struct{}, len(cfg.LegacyRPCListeners))
+		for _, addr := range cfg.LegacyRPCListeners {
 			seenAddresses[addr] = struct{}{}
 		}
-		for _, addr := range cfg.LegacyRPCListeners {
+		for _, addr := range cfg.ExperimentalRPCListeners {
 			_, seen := seenAddresses[addr]
 			if seen {
 				err := fmt.Errorf("Address `%s` may not be "+
@@ -555,7 +565,8 @@ func loadConfig() (*config, []string, error) {
 	// Only allow server TLS to be disabled if the RPC server is bound to
 	// localhost addresses.
 	if cfg.DisableServerTLS {
-		allListeners := append(cfg.RPCListeners, cfg.LegacyRPCListeners...)
+		allListeners := append(cfg.LegacyRPCListeners,
+			cfg.ExperimentalRPCListeners...)
 		for _, addr := range allListeners {
 			host, _, err := net.SplitHostPort(addr)
 			if err != nil {

log.go

@@ -51,7 +51,7 @@ var subsystemLoggers = map[string]btclog.Logger{
 	"TMGR": txmgrLog,
 	"CHNS": chainLog,
 	"GRPC": grpcLog,
-	"LRPC": legacyRPCLog,
+	"RPCS": legacyRPCLog,
 }
 
 // logClosure is used to provide a closure over expensive logging operations
@@ -94,7 +94,7 @@ func useLogger(subsystemID string, logger btclog.Logger) {
 	case "GRPC":
 		grpcLog = logger
 		rpcserver.UseLogger(logger)
-	case "LRPC":
+	case "RPCS":
 		legacyRPCLog = logger
 		legacyrpc.UseLogger(logger)
 	}

rpcserver.go

@@ -123,8 +123,8 @@ func startRPCServers(walletLoader *wallet.Loader) (*grpc.Server, *legacyrpc.Serv
 			return tls.Listen(net, laddr, tlsConfig)
 		}
 
-		if len(cfg.RPCListeners) != 0 {
-			listeners := makeListeners(cfg.RPCListeners, net.Listen)
+		if len(cfg.ExperimentalRPCListeners) != 0 {
+			listeners := makeListeners(cfg.ExperimentalRPCListeners, net.Listen)
 			if len(listeners) == 0 {
 				err := errors.New("failed to create listeners for RPC server")
 				return nil, nil, err
@@ -135,9 +135,11 @@ func startRPCServers(walletLoader *wallet.Loader) (*grpc.Server, *legacyrpc.Serv
 			for _, lis := range listeners {
 				lis := lis
 				go func() {
-					log.Infof("RPC server listening on %s", lis.Addr())
+					log.Infof("Experimental RPC server listening on %s",
+						lis.Addr())
 					err := server.Serve(lis)
-					log.Tracef("Finished serving RPC: %v", err)
+					log.Tracef("Finished serving expimental RPC: %v",
+						err)
 				}()
 			}
 		}