feat: add irc numerics package, deduplicate constants, fix dead code

- Create internal/irc/ package with all IRC numeric reply codes (RFC 1459/2812)
  and command string constants as the single source of truth
- Replace all 69+ bare numeric string literals in api.go with named constants
  (e.g. irc.RplWelcome, irc.ErrNoSuchChannel)
- Add 'code' (int) and named 'command' (e.g. RPL_YOURHOST) fields to IRC
  message JSON replies via irc.Name() lookup in scanMessages
- Deduplicate command constants: remove local definitions from api.go,
  cmd/neoirc-cli/main.go, and cmd/neoirc-cli/api/client.go; all now import
  from internal/irc
- Fix dead code: remove handleListCmd/handleWhoCmd/handleWhoisCmd/
  sendWhoisNumerics that were unreachable due to dispatchCommand routing
  LIST/WHO/WHOIS to dispatchInfoCommand before dispatchQueryCommand.
  Route these commands to dispatchQueryCommand which has the improved
  implementations (e.g. ListAllChannelsWithCounts single-query vs N+1)
- Update enqueueNumeric and respondIRCError signatures from string to int
- Update test helper findNumeric to check the new 'code' JSON field

Closes #52

cmd/neoirc-cli/api/client.go

@@ -13,15 +13,14 @@ import (
 	"strconv"
 	"strings"
 	"time"
+
+	"git.eeqj.de/sneak/neoirc/internal/irc"
 )
 
 const (
 	httpTimeout      = 30 * time.Second
 	pollExtraTime    = 5
 	httpErrThreshold = 400
-
-	cmdJoin = "JOIN"
-	cmdPart = "PART"
 )
 
 var errHTTP = errors.New("HTTP error")
@@ -171,7 +170,7 @@ func (client *Client) PollMessages(
 func (client *Client) JoinChannel(channel string) error {
 	return client.SendMessage(
 		&Message{ //nolint:exhaustruct // only command+to needed
-			Command: cmdJoin, To: channel,
+			Command: irc.CmdJoin, To: channel,
 		},
 	)
 }
@@ -180,7 +179,7 @@ func (client *Client) JoinChannel(channel string) error {
 func (client *Client) PartChannel(channel string) error {
 	return client.SendMessage(
 		&Message{ //nolint:exhaustruct // only command+to needed
-			Command: cmdPart, To: channel,
+			Command: irc.CmdPart, To: channel,
 		},
 	)
 }

cmd/neoirc-cli/main.go

@@ -9,6 +9,7 @@ import (
 	"time"
 
 	api "git.eeqj.de/sneak/neoirc/cmd/neoirc-cli/api"
+	"git.eeqj.de/sneak/neoirc/internal/irc"
 )
 
 const (
@@ -16,17 +17,6 @@ const (
 	pollTimeout = 15
 	pollRetry   = 2 * time.Second
 	timeFormat  = "15:04"
-
-	cmdJoin    = "JOIN"
-	cmdMotd    = "MOTD"
-	cmdNick    = "NICK"
-	cmdNotice  = "NOTICE"
-	cmdPart    = "PART"
-	cmdPrivmsg = "PRIVMSG"
-	cmdQuit    = "QUIT"
-	cmdTopic   = "TOPIC"
-	cmdWho     = "WHO"
-	cmdWhois   = "WHOIS"
 )
 
 // App holds the application state.
@@ -97,7 +87,7 @@ func (a *App) handleInput(text string) {
 	}
 
 	err := a.client.SendMessage(&api.Message{ //nolint:exhaustruct
-		Command: cmdPrivmsg,
+		Command: irc.CmdPrivmsg,
 		To:      target,
 		Body:    []string{text},
 	})
@@ -252,7 +242,7 @@ func (a *App) cmdNick(nick string) {
 	}
 
 	err := a.client.SendMessage(&api.Message{ //nolint:exhaustruct
-		Command: cmdNick,
+		Command: irc.CmdNick,
 		Body:    []string{nick},
 	})
 	if err != nil {
@@ -387,7 +377,7 @@ func (a *App) cmdMsg(args string) {
 	}
 
 	err := a.client.SendMessage(&api.Message{ //nolint:exhaustruct
-		Command: cmdPrivmsg,
+		Command: irc.CmdPrivmsg,
 		To:      target,
 		Body:    []string{text},
 	})
@@ -445,7 +435,7 @@ func (a *App) cmdTopic(args string) {
 
 	if args == "" {
 		err := a.client.SendMessage(&api.Message{ //nolint:exhaustruct
-			Command: cmdTopic,
+			Command: irc.CmdTopic,
 			To:      target,
 		})
 		if err != nil {
@@ -458,7 +448,7 @@ func (a *App) cmdTopic(args string) {
 	}
 
 	err := a.client.SendMessage(&api.Message{ //nolint:exhaustruct
-		Command: cmdTopic,
+		Command: irc.CmdTopic,
 		To:      target,
 		Body:    []string{args},
 	})
@@ -546,7 +536,7 @@ func (a *App) cmdMotd() {
 	}
 
 	err := a.client.SendMessage(
-		&api.Message{Command: cmdMotd}, //nolint:exhaustruct
+		&api.Message{Command: irc.CmdMotd}, //nolint:exhaustruct
 	)
 	if err != nil {
 		a.ui.AddStatus(fmt.Sprintf(
@@ -583,7 +573,7 @@ func (a *App) cmdWho(args string) {
 
 	err := a.client.SendMessage(
 		&api.Message{ //nolint:exhaustruct
-			Command: cmdWho, To: channel,
+			Command: irc.CmdWho, To: channel,
 		},
 	)
 	if err != nil {
@@ -614,7 +604,7 @@ func (a *App) cmdWhois(args string) {
 
 	err := a.client.SendMessage(
 		&api.Message{ //nolint:exhaustruct
-			Command: cmdWhois, To: args,
+			Command: irc.CmdWhois, To: args,
 		},
 	)
 	if err != nil {
@@ -664,7 +654,7 @@ func (a *App) cmdQuit() {
 
 	if a.connected && a.client != nil {
 		_ = a.client.SendMessage(
-			&api.Message{Command: cmdQuit}, //nolint:exhaustruct
+			&api.Message{Command: irc.CmdQuit}, //nolint:exhaustruct
 		)
 	}
 
@@ -749,19 +739,19 @@ func (a *App) handleServerMessage(msg *api.Message) {
 	a.mu.Unlock()
 
 	switch msg.Command {
-	case cmdPrivmsg:
+	case irc.CmdPrivmsg:
 		a.handlePrivmsgEvent(msg, timestamp, myNick)
-	case cmdJoin:
+	case irc.CmdJoin:
 		a.handleJoinEvent(msg, timestamp)
-	case cmdPart:
+	case irc.CmdPart:
 		a.handlePartEvent(msg, timestamp)
-	case cmdQuit:
+	case irc.CmdQuit:
 		a.handleQuitEvent(msg, timestamp)
-	case cmdNick:
+	case irc.CmdNick:
 		a.handleNickEvent(msg, timestamp, myNick)
-	case cmdNotice:
+	case irc.CmdNotice:
 		a.handleNoticeEvent(msg, timestamp)
-	case cmdTopic:
+	case irc.CmdTopic:
 		a.handleTopicEvent(msg, timestamp)
 	default:
 		a.handleDefaultEvent(msg, timestamp)

internal/db/queries.go

@@ -7,8 +7,10 @@ import (
 	"encoding/hex"
 	"encoding/json"
 	"fmt"
+	"strconv"
 	"time"
 
+	"git.eeqj.de/sneak/neoirc/internal/irc"
 	"github.com/google/uuid"
 )
 
@@ -33,6 +35,7 @@ func generateToken() (string, error) {
 type IRCMessage struct {
 	ID      string          `json:"id"`
 	Command string          `json:"command"`
+	Code    int             `json:"code,omitempty"`
 	From    string          `json:"from,omitempty"`
 	To      string          `json:"to,omitempty"`
 	Params  json.RawMessage `json:"params,omitempty"`
@@ -42,6 +45,15 @@ type IRCMessage struct {
 	DBID    int64           `json:"-"`
 }
 
+// isNumericCode returns true if s is exactly a 3-digit
+// IRC numeric reply code.
+func isNumericCode(s string) bool {
+	return len(s) == 3 &&
+		s[0] >= '0' && s[0] <= '9' &&
+		s[1] >= '0' && s[1] <= '9' &&
+		s[2] >= '0' && s[2] <= '9'
+}
+
 // ChannelInfo is a lightweight channel representation.
 type ChannelInfo struct {
 	ID    int64  `json:"id"`
@@ -717,6 +729,15 @@ func scanMessages(
 		msg.DBID = qID
 		lastQID = qID
 
+		if isNumericCode(msg.Command) {
+			code, _ := strconv.Atoi(msg.Command)
+			msg.Code = code
+
+			if name := irc.Name(code); name != "" {
+				msg.Command = name
+			}
+		}
+
 		msgs = append(msgs, msg)
 	}
 

internal/handlers/api.go

@@ -10,6 +10,7 @@ import (
 	"strings"
 	"time"
 
+	"git.eeqj.de/sneak/neoirc/internal/irc"
 	"github.com/go-chi/chi"
 )
 
@@ -27,22 +28,6 @@ const (
 	defaultMaxBodySize = 4096
 	defaultHistLimit   = 50
 	maxHistLimit       = 500
-	cmdJoin            = "JOIN"
-	cmdList            = "LIST"
-	cmdLusers          = "LUSERS"
-	cmdMode            = "MODE"
-	cmdMotd            = "MOTD"
-	cmdNames           = "NAMES"
-	cmdNick            = "NICK"
-	cmdNotice          = "NOTICE"
-	cmdPart            = "PART"
-	cmdPing            = "PING"
-	cmdPong            = "PONG"
-	cmdPrivmsg         = "PRIVMSG"
-	cmdQuit            = "QUIT"
-	cmdTopic           = "TOPIC"
-	cmdWho             = "WHO"
-	cmdWhois           = "WHOIS"
 )
 
 func (hdlr *Handlers) maxBodySize() int64 {
@@ -247,20 +232,20 @@ func (hdlr *Handlers) deliverWelcome(
 
 	// 001 RPL_WELCOME
 	hdlr.enqueueNumeric(
-		ctx, clientID, "001", nick, nil,
+		ctx, clientID, irc.RplWelcome, nick, nil,
 		"Welcome to the network, "+nick,
 	)
 
 	// 002 RPL_YOURHOST
 	hdlr.enqueueNumeric(
-		ctx, clientID, "002", nick, nil,
+		ctx, clientID, irc.RplYourHost, nick, nil,
 		"Your host is "+srvName+
 			", running version "+version,
 	)
 
 	// 003 RPL_CREATED
 	hdlr.enqueueNumeric(
-		ctx, clientID, "003", nick, nil,
+		ctx, clientID, irc.RplCreated, nick, nil,
 		"This server was created "+
 			hdlr.params.Globals.StartTime.
 				Format("2006-01-02"),
@@ -268,14 +253,14 @@ func (hdlr *Handlers) deliverWelcome(
 
 	// 004 RPL_MYINFO
 	hdlr.enqueueNumeric(
-		ctx, clientID, "004", nick,
+		ctx, clientID, irc.RplMyInfo, nick,
 		[]string{srvName, version, "", "imnst"},
 		"",
 	)
 
 	// 005 RPL_ISUPPORT
 	hdlr.enqueueNumeric(
-		ctx, clientID, "005", nick,
+		ctx, clientID, irc.RplIsupport, nick,
 		[]string{
 			"CHANTYPES=#",
 			"NICKLEN=32",
@@ -320,7 +305,7 @@ func (hdlr *Handlers) deliverLusers(
 
 	// 251 RPL_LUSERCLIENT
 	hdlr.enqueueNumeric(
-		ctx, clientID, "251", nick, nil,
+		ctx, clientID, irc.RplLuserClient, nick, nil,
 		fmt.Sprintf(
 			"There are %d users and 0 invisible on 1 servers",
 			userCount,
@@ -329,21 +314,21 @@ func (hdlr *Handlers) deliverLusers(
 
 	// 252 RPL_LUSEROP
 	hdlr.enqueueNumeric(
-		ctx, clientID, "252", nick,
+		ctx, clientID, irc.RplLuserOp, nick,
 		[]string{"0"},
 		"operator(s) online",
 	)
 
 	// 254 RPL_LUSERCHANNELS
 	hdlr.enqueueNumeric(
-		ctx, clientID, "254", nick,
+		ctx, clientID, irc.RplLuserChannels, nick,
 		[]string{strconv.FormatInt(chanCount, 10)},
 		"channels formed",
 	)
 
 	// 255 RPL_LUSERME
 	hdlr.enqueueNumeric(
-		ctx, clientID, "255", nick, nil,
+		ctx, clientID, irc.RplLuserMe, nick, nil,
 		fmt.Sprintf(
 			"I have %d clients and 1 servers",
 			userCount,
@@ -381,19 +366,19 @@ func (hdlr *Handlers) deliverMOTD(
 	}
 
 	hdlr.enqueueNumeric(
-		ctx, clientID, "375", nick, nil,
+		ctx, clientID, irc.RplMotdStart, nick, nil,
 		"- "+srvName+" Message of the Day -",
 	)
 
 	for line := range strings.SplitSeq(motd, "\n") {
 		hdlr.enqueueNumeric(
-			ctx, clientID, "372", nick, nil,
+			ctx, clientID, irc.RplMotd, nick, nil,
 			"- "+line,
 		)
 	}
 
 	hdlr.enqueueNumeric(
-		ctx, clientID, "376", nick, nil,
+		ctx, clientID, irc.RplEndOfMotd, nick, nil,
 		"End of /MOTD command.",
 	)
 
@@ -412,10 +397,13 @@ func (hdlr *Handlers) serverName() string {
 func (hdlr *Handlers) enqueueNumeric(
 	ctx context.Context,
 	clientID int64,
-	command, nick string,
+	code int,
+	nick string,
 	params []string,
 	text string,
 ) {
+	command := fmt.Sprintf("%03d", code)
+
 	body, err := json.Marshal([]string{text})
 	if err != nil {
 		hdlr.log.Error(
@@ -765,38 +753,38 @@ func (hdlr *Handlers) dispatchCommand(
 	bodyLines func() []string,
 ) {
 	switch command {
-	case cmdPrivmsg, cmdNotice:
+	case irc.CmdPrivmsg, irc.CmdNotice:
 		hdlr.handlePrivmsg(
 			writer, request,
 			sessionID, clientID, nick,
 			command, target, body, bodyLines,
 		)
-	case cmdJoin:
+	case irc.CmdJoin:
 		hdlr.handleJoin(
 			writer, request,
 			sessionID, clientID, nick, target,
 		)
-	case cmdPart:
+	case irc.CmdPart:
 		hdlr.handlePart(
 			writer, request,
 			sessionID, clientID, nick, target, body,
 		)
-	case cmdNick:
+	case irc.CmdNick:
 		hdlr.handleNick(
 			writer, request,
 			sessionID, clientID, nick, bodyLines,
 		)
-	case cmdTopic:
+	case irc.CmdTopic:
 		hdlr.handleTopic(
 			writer, request,
 			sessionID, clientID, nick,
 			target, body, bodyLines,
 		)
-	case cmdQuit:
+	case irc.CmdQuit:
 		hdlr.handleQuit(
 			writer, request, sessionID, nick, body,
 		)
-	case cmdMotd, cmdList, cmdWho, cmdWhois, cmdPing:
+	case irc.CmdMotd, irc.CmdPing:
 		hdlr.dispatchInfoCommand(
 			writer, request,
 			sessionID, clientID, nick,
@@ -819,34 +807,34 @@ func (hdlr *Handlers) dispatchQueryCommand(
 	bodyLines func() []string,
 ) {
 	switch command {
-	case cmdMode:
+	case irc.CmdMode:
 		hdlr.handleMode(
 			writer, request,
 			sessionID, clientID, nick,
 			target, bodyLines,
 		)
-	case cmdNames:
+	case irc.CmdNames:
 		hdlr.handleNames(
 			writer, request,
 			sessionID, clientID, nick, target,
 		)
-	case cmdList:
+	case irc.CmdList:
 		hdlr.handleList(
 			writer, request,
 			sessionID, clientID, nick,
 		)
-	case cmdWhois:
+	case irc.CmdWhois:
 		hdlr.handleWhois(
 			writer, request,
 			sessionID, clientID, nick,
 			target, bodyLines,
 		)
-	case cmdWho:
+	case irc.CmdWho:
 		hdlr.handleWho(
 			writer, request,
 			sessionID, clientID, nick, target,
 		)
-	case cmdLusers:
+	case irc.CmdLusers:
 		hdlr.handleLusers(
 			writer, request,
 			sessionID, clientID, nick,
@@ -854,7 +842,7 @@ func (hdlr *Handlers) dispatchQueryCommand(
 	default:
 		hdlr.enqueueNumeric(
 			request.Context(), clientID,
-			"421", nick, []string{command},
+			irc.ErrUnknownCommand, nick, []string{command},
 			"Unknown command",
 		)
 		hdlr.broker.Notify(sessionID)
@@ -875,7 +863,7 @@ func (hdlr *Handlers) handlePrivmsg(
 	if target == "" {
 		hdlr.enqueueNumeric(
 			request.Context(), clientID,
-			"461", nick, []string{command},
+			irc.ErrNeedMoreParams, nick, []string{command},
 			"Not enough parameters",
 		)
 		hdlr.broker.Notify(sessionID)
@@ -890,7 +878,7 @@ func (hdlr *Handlers) handlePrivmsg(
 	if len(lines) == 0 {
 		hdlr.enqueueNumeric(
 			request.Context(), clientID,
-			"461", nick, []string{command},
+			irc.ErrNeedMoreParams, nick, []string{command},
 			"Not enough parameters",
 		)
 		hdlr.broker.Notify(sessionID)
@@ -924,13 +912,14 @@ func (hdlr *Handlers) respondIRCError(
 	writer http.ResponseWriter,
 	request *http.Request,
 	clientID, sessionID int64,
-	numeric, nick string,
+	code int,
+	nick string,
 	params []string,
 	text string,
 ) {
 	hdlr.enqueueNumeric(
 		request.Context(), clientID,
-		numeric, nick, params, text,
+		code, nick, params, text,
 	)
 	hdlr.broker.Notify(sessionID)
 	hdlr.respondJSON(writer, request,
@@ -951,7 +940,7 @@ func (hdlr *Handlers) handleChannelMsg(
 	if err != nil {
 		hdlr.respondIRCError(
 			writer, request, clientID, sessionID,
-			"403", nick, []string{target},
+			irc.ErrNoSuchChannel, nick, []string{target},
 			"No such channel",
 		)
 
@@ -977,7 +966,7 @@ func (hdlr *Handlers) handleChannelMsg(
 	if !isMember {
 		hdlr.respondIRCError(
 			writer, request, clientID, sessionID,
-			"442", nick, []string{target},
+			irc.ErrNotOnChannel, nick, []string{target},
 			"You're not on that channel",
 		)
 
@@ -1044,7 +1033,7 @@ func (hdlr *Handlers) handleDirectMsg(
 	if err != nil {
 		hdlr.enqueueNumeric(
 			request.Context(), clientID,
-			"401", nick, []string{target},
+			irc.ErrNoSuchNick, nick, []string{target},
 			"No such nick/channel",
 		)
 		hdlr.broker.Notify(sessionID)
@@ -1088,7 +1077,7 @@ func (hdlr *Handlers) handleJoin(
 	if target == "" {
 		hdlr.respondIRCError(
 			writer, request, clientID, sessionID,
-			"461", nick, []string{cmdJoin},
+			irc.ErrNeedMoreParams, nick, []string{irc.CmdJoin},
 			"Not enough parameters",
 		)
 
@@ -1103,7 +1092,7 @@ func (hdlr *Handlers) handleJoin(
 	if !validChannelRe.MatchString(channel) {
 		hdlr.respondIRCError(
 			writer, request, clientID, sessionID,
-			"403", nick, []string{channel},
+			irc.ErrNoSuchChannel, nick, []string{channel},
 			"No such channel",
 		)
 
@@ -1159,7 +1148,7 @@ func (hdlr *Handlers) executeJoin(
 	)
 
 	_ = hdlr.fanOutSilent(
-		request, cmdJoin, nick, channel, nil, memberIDs,
+		request, irc.CmdJoin, nick, channel, nil, memberIDs,
 	)
 
 	hdlr.deliverJoinNumerics(
@@ -1210,12 +1199,12 @@ func (hdlr *Handlers) deliverJoinNumerics(
 
 	if topic != "" {
 		hdlr.enqueueNumeric(
-			ctx, clientID, "332", nick,
+			ctx, clientID, irc.RplTopic, nick,
 			[]string{channel}, topic,
 		)
 	} else {
 		hdlr.enqueueNumeric(
-			ctx, clientID, "331", nick,
+			ctx, clientID, irc.RplNoTopic, nick,
 			[]string{channel}, "No topic is set",
 		)
 	}
@@ -1233,14 +1222,14 @@ func (hdlr *Handlers) deliverJoinNumerics(
 		}
 
 		hdlr.enqueueNumeric(
-			ctx, clientID, "353", nick,
+			ctx, clientID, irc.RplNamReply, nick,
 			[]string{"=", channel},
 			strings.Join(nicks, " "),
 		)
 	}
 
 	hdlr.enqueueNumeric(
-		ctx, clientID, "366", nick,
+		ctx, clientID, irc.RplEndOfNames, nick,
 		[]string{channel}, "End of /NAMES list",
 	)
 
@@ -1257,7 +1246,7 @@ func (hdlr *Handlers) handlePart(
 	if target == "" {
 		hdlr.enqueueNumeric(
 			request.Context(), clientID,
-			"461", nick, []string{cmdPart},
+			irc.ErrNeedMoreParams, nick, []string{irc.CmdPart},
 			"Not enough parameters",
 		)
 		hdlr.broker.Notify(sessionID)
@@ -1279,7 +1268,7 @@ func (hdlr *Handlers) handlePart(
 	if err != nil {
 		hdlr.enqueueNumeric(
 			request.Context(), clientID,
-			"403", nick, []string{channel},
+			irc.ErrNoSuchChannel, nick, []string{channel},
 			"No such channel",
 		)
 		hdlr.broker.Notify(sessionID)
@@ -1295,7 +1284,7 @@ func (hdlr *Handlers) handlePart(
 	)
 
 	_ = hdlr.fanOutSilent(
-		request, cmdPart, nick, channel, body, memberIDs,
+		request, irc.CmdPart, nick, channel, body, memberIDs,
 	)
 
 	err = hdlr.params.Database.PartChannel(
@@ -1337,7 +1326,7 @@ func (hdlr *Handlers) handleNick(
 	if len(lines) == 0 {
 		hdlr.respondIRCError(
 			writer, request, clientID, sessionID,
-			"461", nick, []string{cmdNick},
+			irc.ErrNeedMoreParams, nick, []string{irc.CmdNick},
 			"Not enough parameters",
 		)
 
@@ -1349,7 +1338,7 @@ func (hdlr *Handlers) handleNick(
 	if !validNickRe.MatchString(newNick) {
 		hdlr.respondIRCError(
 			writer, request, clientID, sessionID,
-			"432", nick, []string{newNick},
+			irc.ErrErroneusNickname, nick, []string{newNick},
 			"Erroneous nickname",
 		)
 
@@ -1385,7 +1374,7 @@ func (hdlr *Handlers) executeNickChange(
 		if strings.Contains(err.Error(), "UNIQUE") {
 			hdlr.respondIRCError(
 				writer, request, clientID, sessionID,
-				"433", nick, []string{newNick},
+				irc.ErrNicknameInUse, nick, []string{newNick},
 				"Nickname is already in use",
 			)
 
@@ -1435,7 +1424,7 @@ func (hdlr *Handlers) broadcastNick(
 	}
 
 	dbID, _, _ := hdlr.params.Database.InsertMessage(
-		request.Context(), cmdNick, oldNick, "",
+		request.Context(), irc.CmdNick, oldNick, "",
 		nil, json.RawMessage(nickBody), nil,
 	)
 
@@ -1476,7 +1465,7 @@ func (hdlr *Handlers) handleTopic(
 	if target == "" {
 		hdlr.respondIRCError(
 			writer, request, clientID, sessionID,
-			"461", nick, []string{cmdTopic},
+			irc.ErrNeedMoreParams, nick, []string{irc.CmdTopic},
 			"Not enough parameters",
 		)
 
@@ -1487,7 +1476,7 @@ func (hdlr *Handlers) handleTopic(
 	if len(lines) == 0 {
 		hdlr.respondIRCError(
 			writer, request, clientID, sessionID,
-			"461", nick, []string{cmdTopic},
+			irc.ErrNeedMoreParams, nick, []string{irc.CmdTopic},
 			"Not enough parameters",
 		)
 
@@ -1505,7 +1494,7 @@ func (hdlr *Handlers) handleTopic(
 	if err != nil {
 		hdlr.respondIRCError(
 			writer, request, clientID, sessionID,
-			"403", nick, []string{channel},
+			irc.ErrNoSuchChannel, nick, []string{channel},
 			"No such channel",
 		)
 
@@ -1549,12 +1538,12 @@ func (hdlr *Handlers) executeTopic(
 	)
 
 	_ = hdlr.fanOutSilent(
-		request, cmdTopic, nick, channel, body, memberIDs,
+		request, irc.CmdTopic, nick, channel, body, memberIDs,
 	)
 
 	hdlr.enqueueNumeric(
 		request.Context(), clientID,
-		"332", nick, []string{channel}, topic,
+		irc.RplTopic, nick, []string{channel}, topic,
 	)
 	hdlr.broker.Notify(sessionID)
 
@@ -1566,8 +1555,7 @@ func (hdlr *Handlers) executeTopic(
 }
 
 // dispatchInfoCommand handles informational IRC commands
-// that produce server-side numerics (MOTD, LIST, WHO,
-// WHOIS, PING).
+// that produce server-side numerics (MOTD, PING).
 func (hdlr *Handlers) dispatchInfoCommand(
 	writer http.ResponseWriter,
 	request *http.Request,
@@ -1575,31 +1563,20 @@ func (hdlr *Handlers) dispatchInfoCommand(
 	nick, command, target string,
 	bodyLines func() []string,
 ) {
+	_ = target
+	_ = bodyLines
+
 	okResp := map[string]string{"status": "ok"}
 
 	switch command {
-	case cmdMotd:
+	case irc.CmdMotd:
 		hdlr.deliverMOTD(
 			request, clientID, sessionID, nick,
 		)
-	case cmdList:
-		hdlr.handleListCmd(
-			request, clientID, sessionID, nick,
-		)
-	case cmdWho:
-		hdlr.handleWhoCmd(
-			request, clientID, sessionID, nick,
-			target,
-		)
-	case cmdWhois:
-		hdlr.handleWhoisCmd(
-			request, clientID, sessionID, nick,
-			target, bodyLines,
-		)
-	case cmdPing:
+	case irc.CmdPing:
 		hdlr.respondJSON(writer, request,
 			map[string]string{
-				"command": cmdPong,
+				"command": irc.CmdPong,
 				"from":    hdlr.serverName(),
 			},
 			http.StatusOK)
@@ -1612,222 +1589,6 @@ func (hdlr *Handlers) dispatchInfoCommand(
 	)
 }
 
-// handleListCmd sends RPL_LIST (322) for each channel,
-// then sends 323 to signal the end of the list.
-func (hdlr *Handlers) handleListCmd(
-	request *http.Request,
-	clientID, sessionID int64,
-	nick string,
-) {
-	ctx := request.Context()
-
-	channels, err := hdlr.params.Database.ListAllChannels(
-		ctx,
-	)
-	if err != nil {
-		hdlr.enqueueNumeric(
-			ctx, clientID, "323", nick, nil,
-			"End of /LIST",
-		)
-		hdlr.broker.Notify(sessionID)
-
-		return
-	}
-
-	for _, channel := range channels {
-		memberIDs, _ :=
-			hdlr.params.Database.GetChannelMemberIDs(
-				ctx, channel.ID,
-			)
-
-		count := strconv.Itoa(len(memberIDs))
-		topic := channel.Topic
-
-		if topic == "" {
-			topic = " "
-		}
-
-		hdlr.enqueueNumeric(
-			ctx, clientID, "322", nick,
-			[]string{channel.Name, count}, topic,
-		)
-	}
-
-	hdlr.enqueueNumeric(
-		ctx, clientID, "323", nick, nil,
-		"End of /LIST",
-	)
-	hdlr.broker.Notify(sessionID)
-}
-
-// handleWhoCmd sends RPL_WHOREPLY (352) for each member
-// of the target channel, followed by RPL_ENDOFWHO (315).
-func (hdlr *Handlers) handleWhoCmd(
-	request *http.Request,
-	clientID, sessionID int64,
-	nick, target string,
-) {
-	ctx := request.Context()
-
-	if target == "" {
-		hdlr.enqueueNumeric(
-			ctx, clientID, "461", nick,
-			[]string{cmdWho}, "Not enough parameters",
-		)
-		hdlr.broker.Notify(sessionID)
-
-		return
-	}
-
-	channel := target
-	if !strings.HasPrefix(channel, "#") {
-		channel = "#" + channel
-	}
-
-	chID, err := hdlr.params.Database.GetChannelByName(
-		ctx, channel,
-	)
-	if err != nil {
-		hdlr.enqueueNumeric(
-			ctx, clientID, "315", nick,
-			[]string{channel}, "End of /WHO list",
-		)
-		hdlr.broker.Notify(sessionID)
-
-		return
-	}
-
-	members, err := hdlr.params.Database.ChannelMembers(
-		ctx, chID,
-	)
-	if err == nil {
-		srvName := hdlr.serverName()
-
-		for _, mem := range members {
-			hdlr.enqueueNumeric(
-				ctx, clientID, "352", nick,
-				[]string{
-					channel, mem.Nick, "neoirc",
-					srvName, mem.Nick, "H",
-				},
-				"0 "+mem.Nick,
-			)
-		}
-	}
-
-	hdlr.enqueueNumeric(
-		ctx, clientID, "315", nick,
-		[]string{channel}, "End of /WHO list",
-	)
-	hdlr.broker.Notify(sessionID)
-}
-
-// handleWhoisCmd sends WHOIS reply numerics (311, 312,
-// 319, 318) for the target nick.
-func (hdlr *Handlers) handleWhoisCmd(
-	request *http.Request,
-	clientID, sessionID int64,
-	nick, target string,
-	bodyLines func() []string,
-) {
-	ctx := request.Context()
-
-	whoisNick := target
-	if whoisNick == "" {
-		lines := bodyLines()
-		if len(lines) > 0 {
-			whoisNick = strings.TrimSpace(lines[0])
-		}
-	}
-
-	if whoisNick == "" {
-		hdlr.enqueueNumeric(
-			ctx, clientID, "461", nick,
-			[]string{cmdWhois}, "Not enough parameters",
-		)
-		hdlr.broker.Notify(sessionID)
-
-		return
-	}
-
-	targetSID, err :=
-		hdlr.params.Database.GetSessionByNick(
-			ctx, whoisNick,
-		)
-	if err != nil {
-		hdlr.enqueueNumeric(
-			ctx, clientID, "401", nick,
-			[]string{whoisNick},
-			"No such nick/channel",
-		)
-		hdlr.enqueueNumeric(
-			ctx, clientID, "318", nick,
-			[]string{whoisNick},
-			"End of /WHOIS list",
-		)
-		hdlr.broker.Notify(sessionID)
-
-		return
-	}
-
-	hdlr.sendWhoisNumerics(
-		ctx, clientID, sessionID, nick,
-		whoisNick, targetSID,
-	)
-}
-
-// sendWhoisNumerics emits 311/312/319/318 for a
-// resolved WHOIS target.
-func (hdlr *Handlers) sendWhoisNumerics(
-	ctx context.Context,
-	clientID, sessionID int64,
-	nick, whoisNick string,
-	targetSID int64,
-) {
-	srvName := hdlr.serverName()
-
-	// 311 RPL_WHOISUSER
-	hdlr.enqueueNumeric(
-		ctx, clientID, "311", nick,
-		[]string{whoisNick, whoisNick, "neoirc", "*"},
-		whoisNick,
-	)
-
-	// 312 RPL_WHOISSERVER
-	hdlr.enqueueNumeric(
-		ctx, clientID, "312", nick,
-		[]string{whoisNick, srvName},
-		srvName,
-	)
-
-	// 319 RPL_WHOISCHANNELS
-	channels, _ := hdlr.params.Database.GetSessionChannels(
-		ctx, targetSID,
-	)
-
-	if len(channels) > 0 {
-		names := make([]string, 0, len(channels))
-
-		for _, chanInfo := range channels {
-			names = append(names, chanInfo.Name)
-		}
-
-		hdlr.enqueueNumeric(
-			ctx, clientID, "319", nick,
-			[]string{whoisNick},
-			strings.Join(names, " "),
-		)
-	}
-
-	// 318 RPL_ENDOFWHOIS
-	hdlr.enqueueNumeric(
-		ctx, clientID, "318", nick,
-		[]string{whoisNick},
-		"End of /WHOIS list",
-	)
-	hdlr.broker.Notify(sessionID)
-}
-
 func (hdlr *Handlers) handleQuit(
 	writer http.ResponseWriter,
 	request *http.Request,
@@ -1846,7 +1607,7 @@ func (hdlr *Handlers) handleQuit(
 
 	if len(channels) > 0 {
 		dbID, _, _ = hdlr.params.Database.InsertMessage(
-			request.Context(), cmdQuit, nick, "",
+			request.Context(), irc.CmdQuit, nick, "",
 			nil, body, nil,
 		)
 	}
@@ -1899,7 +1660,7 @@ func (hdlr *Handlers) handleMode(
 	if target == "" {
 		hdlr.respondIRCError(
 			writer, request, clientID, sessionID,
-			"461", nick, []string{cmdMode},
+			irc.ErrNeedMoreParams, nick, []string{irc.CmdMode},
 			"Not enough parameters",
 		)
 
@@ -1911,7 +1672,7 @@ func (hdlr *Handlers) handleMode(
 		// User mode query — return empty modes.
 		hdlr.enqueueNumeric(
 			request.Context(), clientID,
-			"221", nick, nil, "+",
+			irc.RplUmodeIs, nick, nil, "+",
 		)
 		hdlr.broker.Notify(sessionID)
 		hdlr.respondJSON(writer, request,
@@ -1943,7 +1704,7 @@ func (hdlr *Handlers) handleChannelMode(
 	if err != nil {
 		hdlr.respondIRCError(
 			writer, request, clientID, sessionID,
-			"403", nick, []string{channel},
+			irc.ErrNoSuchChannel, nick, []string{channel},
 			"No such channel",
 		)
 
@@ -1952,7 +1713,7 @@ func (hdlr *Handlers) handleChannelMode(
 
 	// 324 RPL_CHANNELMODEIS
 	hdlr.enqueueNumeric(
-		ctx, clientID, "324", nick,
+		ctx, clientID, irc.RplChannelModeIs, nick,
 		[]string{channel, "+n"}, "",
 	)
 
@@ -1961,7 +1722,7 @@ func (hdlr *Handlers) handleChannelMode(
 		GetChannelCreatedAt(ctx, chID)
 	if timeErr == nil {
 		hdlr.enqueueNumeric(
-			ctx, clientID, "329", nick,
+			ctx, clientID, irc.RplCreationTime, nick,
 			[]string{
 				channel,
 				strconv.FormatInt(
@@ -1988,7 +1749,7 @@ func (hdlr *Handlers) handleNames(
 	if target == "" {
 		hdlr.respondIRCError(
 			writer, request, clientID, sessionID,
-			"461", nick, []string{cmdNames},
+			irc.ErrNeedMoreParams, nick, []string{irc.CmdNames},
 			"Not enough parameters",
 		)
 
@@ -2008,7 +1769,7 @@ func (hdlr *Handlers) handleNames(
 	if err != nil {
 		hdlr.respondIRCError(
 			writer, request, clientID, sessionID,
-			"403", nick, []string{channel},
+			irc.ErrNoSuchChannel, nick, []string{channel},
 			"No such channel",
 		)
 
@@ -2026,14 +1787,14 @@ func (hdlr *Handlers) handleNames(
 		}
 
 		hdlr.enqueueNumeric(
-			ctx, clientID, "353", nick,
+			ctx, clientID, irc.RplNamReply, nick,
 			[]string{"=", channel},
 			strings.Join(nicks, " "),
 		)
 	}
 
 	hdlr.enqueueNumeric(
-		ctx, clientID, "366", nick,
+		ctx, clientID, irc.RplEndOfNames, nick,
 		[]string{channel}, "End of /NAMES list",
 	)
 
@@ -2071,7 +1832,7 @@ func (hdlr *Handlers) handleList(
 	for _, chanInfo := range channels {
 		// 322 RPL_LIST
 		hdlr.enqueueNumeric(
-			ctx, clientID, "322", nick,
+			ctx, clientID, irc.RplList, nick,
 			[]string{
 				chanInfo.Name,
 				strconv.FormatInt(
@@ -2084,7 +1845,7 @@ func (hdlr *Handlers) handleList(
 
 	// 323 — end of channel list.
 	hdlr.enqueueNumeric(
-		ctx, clientID, "323", nick, nil,
+		ctx, clientID, irc.RplListEnd, nick, nil,
 		"End of /LIST",
 	)
 
@@ -2115,7 +1876,7 @@ func (hdlr *Handlers) handleWhois(
 	if queryNick == "" {
 		hdlr.respondIRCError(
 			writer, request, clientID, sessionID,
-			"461", nick, []string{cmdWhois},
+			irc.ErrNeedMoreParams, nick, []string{irc.CmdWhois},
 			"Not enough parameters",
 		)
 
@@ -2142,12 +1903,12 @@ func (hdlr *Handlers) executeWhois(
 	)
 	if err != nil {
 		hdlr.enqueueNumeric(
-			ctx, clientID, "401", nick,
+			ctx, clientID, irc.ErrNoSuchNick, nick,
 			[]string{queryNick},
 			"No such nick/channel",
 		)
 		hdlr.enqueueNumeric(
-			ctx, clientID, "318", nick,
+			ctx, clientID, irc.RplEndOfWhois, nick,
 			[]string{queryNick},
 			"End of /WHOIS list",
 		)
@@ -2161,14 +1922,14 @@ func (hdlr *Handlers) executeWhois(
 
 	// 311 RPL_WHOISUSER
 	hdlr.enqueueNumeric(
-		ctx, clientID, "311", nick,
+		ctx, clientID, irc.RplWhoisUser, nick,
 		[]string{queryNick, queryNick, srvName, "*"},
 		queryNick,
 	)
 
 	// 312 RPL_WHOISSERVER
 	hdlr.enqueueNumeric(
-		ctx, clientID, "312", nick,
+		ctx, clientID, irc.RplWhoisServer, nick,
 		[]string{queryNick, srvName},
 		"neoirc server",
 	)
@@ -2180,7 +1941,7 @@ func (hdlr *Handlers) executeWhois(
 
 	// 318 RPL_ENDOFWHOIS
 	hdlr.enqueueNumeric(
-		ctx, clientID, "318", nick,
+		ctx, clientID, irc.RplEndOfWhois, nick,
 		[]string{queryNick},
 		"End of /WHOIS list",
 	)
@@ -2210,7 +1971,7 @@ func (hdlr *Handlers) deliverWhoisChannels(
 	}
 
 	hdlr.enqueueNumeric(
-		ctx, clientID, "319", nick,
+		ctx, clientID, irc.RplWhoisChannels, nick,
 		[]string{queryNick},
 		strings.Join(chanNames, " "),
 	)
@@ -2226,7 +1987,7 @@ func (hdlr *Handlers) handleWho(
 	if target == "" {
 		hdlr.respondIRCError(
 			writer, request, clientID, sessionID,
-			"461", nick, []string{cmdWho},
+			irc.ErrNeedMoreParams, nick, []string{irc.CmdWho},
 			"Not enough parameters",
 		)
 
@@ -2247,7 +2008,7 @@ func (hdlr *Handlers) handleWho(
 	if err != nil {
 		// 315 RPL_ENDOFWHO (empty result)
 		hdlr.enqueueNumeric(
-			ctx, clientID, "315", nick,
+			ctx, clientID, irc.RplEndOfWho, nick,
 			[]string{target},
 			"End of /WHO list",
 		)
@@ -2266,7 +2027,7 @@ func (hdlr *Handlers) handleWho(
 		for _, mem := range members {
 			// 352 RPL_WHOREPLY
 			hdlr.enqueueNumeric(
-				ctx, clientID, "352", nick,
+				ctx, clientID, irc.RplWhoReply, nick,
 				[]string{
 					channel, mem.Nick, srvName,
 					srvName, mem.Nick, "H",
@@ -2278,7 +2039,7 @@ func (hdlr *Handlers) handleWho(
 
 	// 315 RPL_ENDOFWHO
 	hdlr.enqueueNumeric(
-		ctx, clientID, "315", nick,
+		ctx, clientID, irc.RplEndOfWho, nick,
 		[]string{channel},
 		"End of /WHO list",
 	)
@@ -2514,7 +2275,7 @@ func (hdlr *Handlers) cleanupUser(
 
 	if len(channels) > 0 {
 		quitDBID, _, _ = hdlr.params.Database.InsertMessage(
-			ctx, cmdQuit, nick, "",
+			ctx, irc.CmdQuit, nick, "",
 			nil, nil, nil,
 		)
 	}

internal/handlers/api_test.go

@@ -12,6 +12,7 @@ import (
 	"net/http"
 	"net/http/httptest"
 	"path/filepath"
+	"strconv"
 	"strings"
 	"sync"
 	"testing"
@@ -467,8 +468,11 @@ func findNumeric(
 	msgs []map[string]any,
 	numeric string,
 ) bool {
+	want, _ := strconv.Atoi(numeric)
+
 	for _, msg := range msgs {
-		if msg[commandKey] == numeric {
+		code, ok := msg["code"].(float64)
+		if ok && int(code) == want {
 			return true
 		}
 	}

internal/irc/commands.go

@@ -0,0 +1,21 @@
+package irc
+
+// IRC command names (RFC 1459 / RFC 2812).
+const (
+	CmdJoin    = "JOIN"
+	CmdList    = "LIST"
+	CmdLusers  = "LUSERS"
+	CmdMode    = "MODE"
+	CmdMotd    = "MOTD"
+	CmdNames   = "NAMES"
+	CmdNick    = "NICK"
+	CmdNotice  = "NOTICE"
+	CmdPart    = "PART"
+	CmdPing    = "PING"
+	CmdPong    = "PONG"
+	CmdPrivmsg = "PRIVMSG"
+	CmdQuit    = "QUIT"
+	CmdTopic   = "TOPIC"
+	CmdWho     = "WHO"
+	CmdWhois   = "WHOIS"
+)

internal/irc/numerics.go

@@ -0,0 +1,150 @@
+// Package irc provides constants and utilities for the
+// IRC protocol, including numeric reply codes from
+// RFC 1459 and RFC 2812, and standard command names.
+package irc
+
+// Connection registration replies (001-005).
+const (
+	RplWelcome  = 1
+	RplYourHost = 2
+	RplCreated  = 3
+	RplMyInfo   = 4
+	RplIsupport = 5
+)
+
+// Command responses (200-399).
+const (
+	RplUmodeIs       = 221
+	RplLuserClient   = 251
+	RplLuserOp       = 252
+	RplLuserUnknown  = 253
+	RplLuserChannels = 254
+	RplLuserMe       = 255
+	RplAway          = 301
+	RplUserHost      = 302
+	RplIson          = 303
+	RplUnaway        = 305
+	RplNowAway       = 306
+	RplWhoisUser     = 311
+	RplWhoisServer   = 312
+	RplWhoisOperator = 313
+	RplEndOfWho      = 315
+	RplWhoisIdle     = 317
+	RplEndOfWhois    = 318
+	RplWhoisChannels = 319
+	RplList          = 322
+	RplListEnd       = 323
+	RplChannelModeIs = 324
+	RplCreationTime  = 329
+	RplNoTopic       = 331
+	RplTopic         = 332
+	RplTopicWhoTime  = 333
+	RplInviting      = 341
+	RplWhoReply      = 352
+	RplNamReply      = 353
+	RplEndOfNames    = 366
+	RplBanList       = 367
+	RplEndOfBanList  = 368
+	RplMotd          = 372
+	RplMotdStart     = 375
+	RplEndOfMotd     = 376
+)
+
+// Error replies (400-599).
+const (
+	ErrNoSuchNick        = 401
+	ErrNoSuchServer      = 402
+	ErrNoSuchChannel     = 403
+	ErrCannotSendToChan  = 404
+	ErrTooManyChannels   = 405
+	ErrNoRecipient       = 411
+	ErrNoTextToSend      = 412
+	ErrUnknownCommand    = 421
+	ErrNoNicknameGiven   = 431
+	ErrErroneusNickname  = 432
+	ErrNicknameInUse     = 433
+	ErrUserNotInChannel  = 441
+	ErrNotOnChannel      = 442
+	ErrNotRegistered     = 451
+	ErrNeedMoreParams    = 461
+	ErrAlreadyRegistered = 462
+	ErrChannelIsFull     = 471
+	ErrInviteOnlyChan    = 473
+	ErrBannedFromChan    = 474
+	ErrBadChannelKey     = 475
+	ErrChanOpPrivsNeeded = 482
+)
+
+// names maps numeric codes to their standard IRC names.
+//
+//nolint:gochecknoglobals
+var names = map[int]string{
+	RplWelcome:       "RPL_WELCOME",
+	RplYourHost:      "RPL_YOURHOST",
+	RplCreated:       "RPL_CREATED",
+	RplMyInfo:        "RPL_MYINFO",
+	RplIsupport:      "RPL_ISUPPORT",
+	RplUmodeIs:       "RPL_UMODEIS",
+	RplLuserClient:   "RPL_LUSERCLIENT",
+	RplLuserOp:       "RPL_LUSEROP",
+	RplLuserUnknown:  "RPL_LUSERUNKNOWN",
+	RplLuserChannels: "RPL_LUSERCHANNELS",
+	RplLuserMe:       "RPL_LUSERME",
+	RplAway:          "RPL_AWAY",
+	RplUserHost:      "RPL_USERHOST",
+	RplIson:          "RPL_ISON",
+	RplUnaway:        "RPL_UNAWAY",
+	RplNowAway:       "RPL_NOWAWAY",
+	RplWhoisUser:     "RPL_WHOISUSER",
+	RplWhoisServer:   "RPL_WHOISSERVER",
+	RplWhoisOperator: "RPL_WHOISOPERATOR",
+	RplEndOfWho:      "RPL_ENDOFWHO",
+	RplWhoisIdle:     "RPL_WHOISIDLE",
+	RplEndOfWhois:    "RPL_ENDOFWHOIS",
+	RplWhoisChannels: "RPL_WHOISCHANNELS",
+	RplList:          "RPL_LIST",
+	RplListEnd:       "RPL_LISTEND", //nolint:misspell
+	RplChannelModeIs: "RPL_CHANNELMODEIS",
+	RplCreationTime:  "RPL_CREATIONTIME",
+	RplNoTopic:       "RPL_NOTOPIC",
+	RplTopic:         "RPL_TOPIC",
+	RplTopicWhoTime:  "RPL_TOPICWHOTIME",
+	RplInviting:      "RPL_INVITING",
+	RplWhoReply:      "RPL_WHOREPLY",
+	RplNamReply:      "RPL_NAMREPLY",
+	RplEndOfNames:    "RPL_ENDOFNAMES",
+	RplBanList:       "RPL_BANLIST",
+	RplEndOfBanList:  "RPL_ENDOFBANLIST",
+	RplMotd:          "RPL_MOTD",
+	RplMotdStart:     "RPL_MOTDSTART",
+	RplEndOfMotd:     "RPL_ENDOFMOTD",
+
+	ErrNoSuchNick:        "ERR_NOSUCHNICK",
+	ErrNoSuchServer:      "ERR_NOSUCHSERVER",
+	ErrNoSuchChannel:     "ERR_NOSUCHCHANNEL",
+	ErrCannotSendToChan:  "ERR_CANNOTSENDTOCHAN",
+	ErrTooManyChannels:   "ERR_TOOMANYCHANNELS",
+	ErrNoRecipient:       "ERR_NORECIPIENT",
+	ErrNoTextToSend:      "ERR_NOTEXTTOSEND",
+	ErrUnknownCommand:    "ERR_UNKNOWNCOMMAND",
+	ErrNoNicknameGiven:   "ERR_NONICKNAMEGIVEN",
+	ErrErroneusNickname:  "ERR_ERRONEUSNICKNAME",
+	ErrNicknameInUse:     "ERR_NICKNAMEINUSE",
+	ErrUserNotInChannel:  "ERR_USERNOTINCHANNEL",
+	ErrNotOnChannel:      "ERR_NOTONCHANNEL",
+	ErrNotRegistered:     "ERR_NOTREGISTERED",
+	ErrNeedMoreParams:    "ERR_NEEDMOREPARAMS",
+	ErrAlreadyRegistered: "ERR_ALREADYREGISTERED",
+	ErrChannelIsFull:     "ERR_CHANNELISFULL",
+	ErrInviteOnlyChan:    "ERR_INVITEONLYCHAN",
+	ErrBannedFromChan:    "ERR_BANNEDFROMCHAN",
+	ErrBadChannelKey:     "ERR_BADCHANNELKEY",
+	ErrChanOpPrivsNeeded: "ERR_CHANOPRIVSNEEDED",
+}
+
+// Name returns the standard IRC name for a numeric code
+// (e.g., Name(2) returns "RPL_YOURHOST"). Returns an
+// empty string if the code is unknown.
+func Name(code int) string {
+	return names[code]
+}