Add the tier 3 utility IRC commands (closes #87)

USERHOST, VERSION, ADMIN, INFO, TIME, KILL and WALLOPS on both the
HTTP API and the IRC listener, and user mode +w.

Model: opus-5-5

internal/ircserver/commands.go

@@ -345,7 +345,10 @@ func (c *Conn) handleQuit(msg *Message) {
 
 	c.send("ERROR :Closing Link: " + c.hostname +
 		" (Quit: " + reason + ")")
+
+	c.mu.Lock()
 	c.closed = true
+	c.mu.Unlock()
 }
 
 // handleTopic gets or sets a channel topic via the shared
@@ -427,7 +430,7 @@ func (c *Conn) handleMode(
 	if strings.HasPrefix(target, "#") {
 		c.handleChannelMode(ctx, msg)
 	} else {
-		c.handleUserMode(msg)
+		c.handleUserMode(ctx, msg)
 	}
 }
 
@@ -687,10 +690,13 @@ func (c *Conn) applyChannelModes(
 }
 
 // handleUserMode handles MODE for users.
-func (c *Conn) handleUserMode(msg *Message) {
+func (c *Conn) handleUserMode(
+	ctx context.Context,
+	msg *Message,
+) {
 	target := msg.Params[0]
 
-	if !strings.EqualFold(target, c.nick) {
+	if !strings.EqualFold(target, c.currentNick()) {
 		c.sendNumeric(
 			irc.ErrUsersDoNotMatch,
 			"Can't change mode for other users",
@@ -699,8 +705,48 @@ func (c *Conn) handleUserMode(msg *Message) {
 		return
 	}
 
-	// We don't support user modes beyond the basics.
-	c.sendNumeric(irc.RplUmodeIs, "+")
+	// Mode query (no mode string).
+	if len(msg.Params) < 2 { //nolint:mnd
+		modes, err := c.svc.QueryUserMode(
+			ctx, c.sessionID,
+		)
+		if err != nil {
+			c.log.Error(
+				"query user mode failed", "error", err,
+			)
+			c.sendNumeric(
+				irc.ErrUmodeUnknownFlag,
+				"Unable to read user modes",
+			)
+
+			return
+		}
+
+		c.sendNumeric(irc.RplUmodeIs, modes)
+
+		return
+	}
+
+	newModes, err := c.svc.ApplyUserMode(
+		ctx, c.sessionID, msg.Params[1],
+	)
+	if err != nil {
+		var ircErr *service.IRCError
+		if errors.As(err, &ircErr) {
+			c.sendNumeric(ircErr.Code, ircErr.Message)
+
+			return
+		}
+
+		c.sendNumeric(
+			irc.ErrUmodeUnknownFlag,
+			"Unknown MODE flag",
+		)
+
+		return
+	}
+
+	c.sendNumeric(irc.RplUmodeIs, newModes)
 }
 
 // handleNames replies with channel member list.
@@ -1292,3 +1338,180 @@ func (c *Conn) handleUserhost(
 		strings.Join(replies, " "),
 	)
 }
+
+// handleVersion replies with the server version string.
+func (c *Conn) handleVersion() {
+	c.sendNumeric(
+		irc.RplVersion,
+		c.svc.ServerVersion()+".", c.serverSfx,
+		"",
+	)
+}
+
+// handleAdmin replies with server admin info.
+func (c *Conn) handleAdmin() {
+	srvName := c.serverSfx
+
+	c.sendNumeric(
+		irc.RplAdminMe,
+		srvName, "Administrative info",
+	)
+
+	c.sendNumeric(
+		irc.RplAdminLoc1,
+		"neoirc server",
+	)
+
+	c.sendNumeric(
+		irc.RplAdminLoc2,
+		"IRC over HTTP",
+	)
+
+	c.sendNumeric(
+		irc.RplAdminEmail,
+		"admin@"+srvName,
+	)
+}
+
+// handleInfo replies with server software info.
+func (c *Conn) handleInfo() {
+	for _, line := range c.svc.InfoLines() {
+		c.sendNumeric(irc.RplInfo, line)
+	}
+
+	c.sendNumeric(
+		irc.RplEndOfInfo,
+		"End of /INFO list",
+	)
+}
+
+// handleTime replies with the server's current time.
+func (c *Conn) handleTime() {
+	srvName := c.serverSfx
+
+	c.sendNumeric(
+		irc.RplTime,
+		srvName, time.Now().Format(time.RFC1123),
+	)
+}
+
+// handleKillCmd forcibly disconnects a target user (oper
+// only).
+func (c *Conn) handleKillCmd(
+	ctx context.Context,
+	msg *Message,
+) {
+	isOper, err := c.database.IsSessionOper(
+		ctx, c.sessionID,
+	)
+	if err != nil || !isOper {
+		c.sendNumeric(
+			irc.ErrNoPrivileges,
+			"Permission Denied- "+
+				"You're not an IRC operator",
+		)
+
+		return
+	}
+
+	if len(msg.Params) < 1 {
+		c.sendNumeric(
+			irc.ErrNeedMoreParams,
+			"KILL", "Not enough parameters",
+		)
+
+		return
+	}
+
+	targetNick := msg.Params[0]
+
+	reason := "KILLed"
+	if len(msg.Params) > 1 {
+		reason = msg.Params[1]
+	}
+
+	killerNick := c.currentNick()
+
+	if strings.EqualFold(targetNick, killerNick) {
+		c.sendNumeric(
+			irc.ErrCantKillServer,
+			"You cannot KILL yourself",
+		)
+
+		return
+	}
+
+	targetSID, lookupErr := c.database.GetSessionByNick(
+		ctx, targetNick,
+	)
+	if lookupErr != nil {
+		c.sendNumeric(
+			irc.ErrNoSuchNick,
+			targetNick, "No such nick/channel",
+		)
+
+		return
+	}
+
+	quitReason := "Killed (" + killerNick +
+		" (" + reason + "))"
+
+	// KillSession broadcasts the QUIT, deletes the session
+	// and disconnects the victim's wire connection.
+	c.svc.KillSession(
+		ctx, targetSID, targetNick, quitReason,
+	)
+}
+
+// handleWallopsCmd broadcasts to all +w users (oper only).
+func (c *Conn) handleWallopsCmd(
+	ctx context.Context,
+	msg *Message,
+) {
+	isOper, err := c.database.IsSessionOper(
+		ctx, c.sessionID,
+	)
+	if err != nil || !isOper {
+		c.sendNumeric(
+			irc.ErrNoPrivileges,
+			"Permission Denied- "+
+				"You're not an IRC operator",
+		)
+
+		return
+	}
+
+	if len(msg.Params) < 1 {
+		c.sendNumeric(
+			irc.ErrNeedMoreParams,
+			"WALLOPS", "Not enough parameters",
+		)
+
+		return
+	}
+
+	message := msg.Params[0]
+
+	wallopsSIDs, wallErr := c.database.
+		GetWallopsSessionIDs(ctx)
+	if wallErr != nil {
+		c.log.Error(
+			"get wallops sessions failed",
+			"error", wallErr,
+		)
+
+		return
+	}
+
+	if len(wallopsSIDs) > 0 {
+		body, mErr := json.Marshal([]string{message})
+		if mErr != nil {
+			return
+		}
+
+		_, _, _ = c.svc.FanOut(
+			ctx, irc.CmdWallops, c.currentNick(), "*",
+			nil, body, nil, wallopsSIDs,
+		)
+	}
+}