Add support for debuglevel RPC command.

Also include the supported subsystems in the error message if an invalid
subsystem is specified.

Closes #15.

config.go

@@ -121,15 +121,10 @@ func supportedSubsystems() []string {
 	return subsystems
 }
 
-// parseDebugLevel attempt to parse the specified debug level and set the levels
-// accordingly.  An appropriate error is returned if anything is invalid.
-func parseDebugLevel(debugLevel string) error {
-	// Special show command to list supported subsystems.
-	if debugLevel == "show" {
-		fmt.Println("Supported subsystems", supportedSubsystems())
-		os.Exit(0)
-	}
-
+// parseAndSetDebugLevels attempts to parse the specified debug level and set
+// the levels accordingly.  An appropriate error is returned if anything is
+// invalid.
+func parseAndSetDebugLevels(debugLevel string) error {
 	// When the specified string doesn't have any delimters, treat it as
 	// the log level for all subsystems.
 	if !strings.Contains(debugLevel, ",") && !strings.Contains(debugLevel, "=") {
@@ -162,8 +157,9 @@ func parseDebugLevel(debugLevel string) error {
 
 		// Validate subsystem.
 		if _, exists := subsystemLoggers[subsysID]; !exists {
-			str := "The specified subsystem [%v] is invalid"
-			return fmt.Errorf(str, subsysID)
+			str := "The specified subsystem [%v] is invalid -- " +
+				"supported subsytems %v"
+			return fmt.Errorf(str, subsysID, supportedSubsystems())
 		}
 
 		// Validate log level.
@@ -326,8 +322,14 @@ func loadConfig() (*config, []string, error) {
 		activeNetParams = netParams(btcwire.TestNet)
 	}
 
+	// Special show command to list supported subsystems and exit.
+	if cfg.DebugLevel == "show" {
+		fmt.Println("Supported subsystems", supportedSubsystems())
+		os.Exit(0)
+	}
+
 	// Parse, validate, and set debug log level(s).
-	if err := parseDebugLevel(cfg.DebugLevel); err != nil {
+	if err := parseAndSetDebugLevels(cfg.DebugLevel); err != nil {
 		err := fmt.Errorf("%s: %v", "loadConfig", err.Error())
 		fmt.Fprintln(os.Stderr, err)
 		parser.WriteHelp(os.Stderr)

rpcserver.go

@@ -547,6 +547,7 @@ var handlers = map[string]commandHandler{
 	"backupwallet":           handleAskWallet,
 	"createmultisig":         handleAskWallet,
 	"createrawtransaction":   handleUnimplemented,
+	"debuglevel":             handleDebugLevel,
 	"decoderawtransaction":   handleDecodeRawTransaction,
 	"decodescript":           handleUnimplemented,
 	"dumpprivkey":            handleAskWallet,
@@ -662,6 +663,29 @@ func handleAddNode(s *rpcServer, cmd btcjson.Cmd,
 	return nil, err
 }
 
+// handleDebugLevel handles debuglevel commands.
+func handleDebugLevel(s *rpcServer, cmd btcjson.Cmd,
+	walletNotification chan []byte) (interface{}, error) {
+	c := cmd.(*btcjson.DebugLevelCmd)
+
+	// Special show command to list supported subsystems.
+	if c.LevelSpec == "show" {
+		return fmt.Sprintf("Supported subsystems %v",
+			supportedSubsystems()), nil
+	}
+
+	err := parseAndSetDebugLevels(c.LevelSpec)
+	if err != nil {
+		jsonErr := btcjson.Error{
+			Code:    btcjson.ErrInvalidParams.Code,
+			Message: err.Error(),
+		}
+		return nil, jsonErr
+	}
+
+	return "Done.", nil
+}
+
 // handleDecodeRawTransaction handles decoderawtransaction commands.
 func handleDecodeRawTransaction(s *rpcServer, cmd btcjson.Cmd,
 	walletNotification chan []byte) (interface{}, error) {

util/btcctl/btcctl.go

@@ -44,6 +44,7 @@ var (
 // to validate correctness and perform the command.
 var commandHandlers = map[string]*handlerData{
 	"addnode":              &handlerData{2, 0, displaySpewDump, nil, makeAddNode, "<ip> <add/remove/onetry>"},
+	"debuglevel":           &handlerData{1, 0, displayGeneric, nil, makeDebugLevel, "<levelspec>"},
 	"decoderawtransaction": &handlerData{1, 0, displaySpewDump, nil, makeDecodeRawTransaction, "<txhash>"},
 	"dumpprivkey":          &handlerData{1, 0, displayGeneric, nil, makeDumpPrivKey, "<bitcoinaddress>"},
 	"getbestblockhash":     &handlerData{0, 0, displayGeneric, nil, makeGetBestBlockHash, ""},
@@ -127,6 +128,11 @@ func makeAddNode(args []interface{}) (btcjson.Cmd, error) {
 		args[1].(string))
 }
 
+// makeDebugLevel generates the cmd structure for debuglevel commands.
+func makeDebugLevel(args []interface{}) (btcjson.Cmd, error) {
+	return btcjson.NewDebugLevelCmd("btcctl", args[0].(string))
+}
+
 // makeDecodeRawTransaction generates the cmd structure for
 // decoderawtransaction comands.
 func makeDecodeRawTransaction(args []interface{}) (btcjson.Cmd, error) {