fix #328 (implement DEFCON)

conventional.yaml

@@ -553,6 +553,7 @@ oper-classes:
             - "vhosts"
             - "chanreg"
             - "history"
+            - "defcon"
 
 # ircd operators
 opers:

default.yaml

@@ -579,6 +579,7 @@ oper-classes:
             - "vhosts"
             - "chanreg"
             - "history"
+            - "defcon"
 
 # ircd operators
 opers:

irc/accounts.go

@@ -380,8 +380,8 @@ func (am *AccountManager) Register(client *Client, account string, callbackNames
 
 	config := am.server.Config()
 
-	// final "is registration allowed" check, probably redundant:
+	// final "is registration allowed" check:
-	if !(config.Accounts.Registration.Enabled || callbackNamespace == "admin") {
+	if !(config.Accounts.Registration.Enabled || callbackNamespace == "admin") || am.server.Defcon() <= 4 {
 		return errFeatureDisabled
 	}
 
@@ -1642,6 +1642,11 @@ func (am *AccountManager) performVHostChange(account string, munger vhostMunger)
 		return
 	}
 
+	if am.server.Defcon() <= 3 {
+		err = errFeatureDisabled
+		return
+	}
+
 	am.vHostUpdateMutex.Lock()
 	defer am.vHostUpdateMutex.Unlock()
 

irc/channel.go

@@ -706,7 +706,8 @@ func (channel *Channel) Join(client *Client, key string, isSajoin bool, rb *Resp
 			return errBanned
 		}
 
-		if channel.flags.HasMode(modes.RegisteredOnly) && details.account == "" {
+		if details.account == "" &&
+			(channel.flags.HasMode(modes.RegisteredOnly) || channel.server.Defcon() <= 3) {
 			return errRegisteredOnly
 		}
 	}

irc/channelmanager.go

@@ -187,6 +187,10 @@ func (cm *ChannelManager) Cleanup(channel *Channel) {
 }
 
 func (cm *ChannelManager) SetRegistered(channelName string, account string) (err error) {
+	if cm.server.Defcon() <= 4 {
+		return errFeatureDisabled
+	}
+
 	var channel *Channel
 	cfname, err := CasefoldChannel(channelName)
 	if err != nil {

irc/client.go

@@ -529,7 +529,7 @@ const (
 	authFailSaslRequired
 )
 
-func (client *Client) isAuthorized(config *Config, session *Session) AuthOutcome {
+func (client *Client) isAuthorized(server *Server, config *Config, session *Session) AuthOutcome {
 	saslSent := client.account != ""
 	// PASS requirement
 	if (config.Server.passwordBytes != nil) && session.passStatus != serverPassSuccessful && !(config.Accounts.SkipServerPassword && saslSent) {
@@ -540,7 +540,8 @@ func (client *Client) isAuthorized(config *Config, session *Session) AuthOutcome
 		return authFailTorSaslRequired
 	}
 	// finally, enforce require-sasl
-	if config.Accounts.RequireSasl.Enabled && !saslSent && !utils.IPInNets(session.IP(), config.Accounts.RequireSasl.exemptedNets) {
+	if !saslSent && (config.Accounts.RequireSasl.Enabled || server.Defcon() <= 2) &&
+		!utils.IPInNets(session.IP(), config.Accounts.RequireSasl.exemptedNets) {
 		return authFailSaslRequired
 	}
 	return authSuccess

irc/commands.go

@@ -124,6 +124,10 @@ func init() {
 			minParams: 1,
 			oper:      true,
 		},
+		"DEFCON": {
+			handler: defconHandler,
+			capabs:  []string{"defcon"},
+		},
 		"DEOPER": {
 			handler:   deoperHandler,
 			minParams: 0,

irc/getters.go

@@ -37,6 +37,14 @@ func (server *Server) Languages() (lm *languages.Manager) {
 	return server.Config().languageManager
 }
 
+func (server *Server) Defcon() uint32 {
+	return atomic.LoadUint32(&server.defcon)
+}
+
+func (server *Server) SetDefcon(defcon uint32) {
+	atomic.StoreUint32(&server.defcon, defcon)
+}
+
 func (client *Client) Sessions() (sessions []*Session) {
 	client.stateMutex.RLock()
 	sessions = client.sessions

irc/handlers.go

@@ -759,6 +759,21 @@ func debugHandler(server *Server, client *Client, msg ircmsg.IrcMessage, rb *Res
 	return false
 }
 
+func defconHandler(server *Server, client *Client, msg ircmsg.IrcMessage, rb *ResponseBuffer) bool {
+	if len(msg.Params) > 0 {
+		level, err := strconv.Atoi(msg.Params[0])
+		if err == nil && 1 <= level && level <= 5 {
+			server.SetDefcon(uint32(level))
+			server.snomasks.Send(sno.LocalAnnouncements, fmt.Sprintf("%s [%s] set DEFCON level to %d", client.Nick(), client.Oper().Name, level))
+		} else {
+			rb.Add(nil, server.name, ERR_UNKNOWNERROR, client.Nick(), msg.Command, client.t("Invalid DEFCON parameter"))
+			return false
+		}
+	}
+	rb.Notice(fmt.Sprintf(client.t("Current DEFCON level is %d"), server.Defcon()))
+	return false
+}
+
 // helper for parsing the reason args to DLINE and KLINE
 func getReasonsFromParams(params []string, currentArg int) (reason, operReason string) {
 	reason = "No reason given"

irc/help.go

@@ -164,6 +164,20 @@ Provides various debugging commands for the IRCd. <option> can be one of:
 * STOPCPUPROFILE: Stops the CPU profiler.
 * PROFILEHEAP: Writes a memory profile.
 * CRASHSERVER: Crashes the server (for use in failover testing)`,
+	},
+	"defcon": {
+		oper: true,
+		text: `DEFCON [level]
+
+The DEFCON system can disable server features at runtime, to mitigate
+spam or other hostile activity. It has five levels, which are cumulative
+(i.e., level 3 includes all restrictions from level 4 and so on):
+
+5: Normal operation
+4: No new account or channel registrations
+3: All channels are +R; no changes to vhosts
+2: No new unauthenticated connections
+1: No new connections except from localhost or other trusted IPs`,
 	},
 	"deoper": {
 		oper: true,

irc/server.go

@@ -80,6 +80,7 @@ type Server struct {
 	whoWas            WhoWasList
 	stats             Stats
 	semaphores        ServerSemaphores
+	defcon            uint32
 }
 
 // NewServer returns a new Oragono server.
@@ -91,6 +92,7 @@ func NewServer(config *Config, logger *logger.Manager) (*Server, error) {
 		logger:       logger,
 		rehashSignal: make(chan os.Signal, 1),
 		signals:      make(chan os.Signal, len(ServerExitSignals)),
+		defcon:       5,
 	}
 
 	server.clients.Initialize()
@@ -149,6 +151,12 @@ func (server *Server) Run() {
 }
 
 func (server *Server) checkBans(ipaddr net.IP) (banned bool, message string) {
+	if server.Defcon() == 1 {
+		if !(ipaddr.IsLoopback() || utils.IPInNets(ipaddr, server.Config().Server.secureNets)) {
+			return true, "New connections to this server are temporarily restricted"
+		}
+	}
+
 	// check DLINEs
 	isBanned, info := server.dlines.CheckIP(ipaddr)
 	if isBanned {
@@ -220,7 +228,8 @@ func (server *Server) tryRegister(c *Client, session *Session) (exiting bool) {
 
 	// client MUST send PASS if necessary, or authenticate with SASL if necessary,
 	// before completing the other registration commands
-	authOutcome := c.isAuthorized(server.Config(), session)
+	config := server.Config()
+	authOutcome := c.isAuthorized(server, config, session)
 	var quitMessage string
 	switch authOutcome {
 	case authFailPass:
@@ -270,7 +279,7 @@ func (server *Server) tryRegister(c *Client, session *Session) (exiting bool) {
 	// Apply default user modes (without updating the invisible counter)
 	// The number of invisible users will be updated by server.stats.Register
 	// if we're using default user mode +i.
-	for _, defaultMode := range server.Config().Accounts.defaultUserModes {
+	for _, defaultMode := range config.Accounts.defaultUserModes {
 		c.SetMode(defaultMode, true)
 	}