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// Package snitch implements a surveillance bot that watches for erratic |
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// behaviour across IRC channels and alerts operators via DM or a |
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// dedicated alert channel. |
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// |
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// Detected conditions: |
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// - Message flooding (burst above threshold in a rolling window) |
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// - Rapid join/part cycling |
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// - Repeated malformed / non-JSON messages from registered agents |
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package snitch |
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import ( |
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"context" |
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"fmt" |
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"log/slog" |
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"net" |
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"strconv" |
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"strings" |
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"sync" |
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"time" |
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"github.com/lrstanley/girc" |
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"github.com/conflicthq/scuttlebot/internal/bots/cmdparse" |
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) |
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const defaultNick = "snitch" |
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// Config controls snitch's thresholds and alert destination. |
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type Config struct { |
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// IRCAddr is host:port of the Ergo IRC server. |
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IRCAddr string |
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// Nick is the IRC nick for the bot. Default: "snitch". |
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Nick string |
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// Password is the SASL PLAIN passphrase for the bot's NickServ account. |
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Password string |
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// AlertChannel is the channel to post alerts to (e.g. "#ops"). |
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// If empty, alerts are sent only as DMs to AlertNicks. |
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AlertChannel string |
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// AlertNicks is the list of operator nicks to DM on an alert. |
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AlertNicks []string |
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// FloodMessages is the number of messages in FloodWindow that triggers |
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// a flood alert. Default: 10. |
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FloodMessages int |
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// FloodWindow is the rolling window for flood detection. Default: 5s. |
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FloodWindow time.Duration |
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// JoinPartThreshold is join+part events in JoinPartWindow to trigger alert. Default: 5. |
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JoinPartThreshold int |
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// JoinPartWindow is the rolling window for join/part cycling. Default: 30s. |
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JoinPartWindow time.Duration |
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// Channels is the list of channels to join on connect. |
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Channels []string |
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// MonitorNicks is the list of nicks to track via IRC MONITOR. |
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// Snitch will alert when a monitored nick goes offline unexpectedly. |
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MonitorNicks []string |
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} |
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func (c *Config) setDefaults() { |
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if c.Nick == "" { |
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c.Nick = defaultNick |
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} |
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if c.FloodMessages == 0 { |
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c.FloodMessages = 10 |
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} |
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if c.FloodWindow == 0 { |
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c.FloodWindow = 5 * time.Second |
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} |
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if c.JoinPartThreshold == 0 { |
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c.JoinPartThreshold = 5 |
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} |
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if c.JoinPartWindow == 0 { |
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c.JoinPartWindow = 30 * time.Second |
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} |
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} |
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// nickWindow tracks event timestamps for a single nick in a single channel. |
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type nickWindow struct { |
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msgs []time.Time |
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joinPart []time.Time |
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} |
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func (nw *nickWindow) trim(now time.Time, msgWindow, jpWindow time.Duration) { |
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cutMsg := now.Add(-msgWindow) |
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filtered := nw.msgs[:0] |
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for _, t := range nw.msgs { |
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if t.After(cutMsg) { |
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filtered = append(filtered, t) |
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} |
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} |
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nw.msgs = filtered |
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cutJP := now.Add(-jpWindow) |
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filteredJP := nw.joinPart[:0] |
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for _, t := range nw.joinPart { |
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if t.After(cutJP) { |
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filteredJP = append(filteredJP, t) |
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} |
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} |
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nw.joinPart = filteredJP |
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} |
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// Bot is the snitch bot. |
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type Bot struct { |
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cfg Config |
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log *slog.Logger |
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client *girc.Client |
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mu sync.Mutex |
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windows map[string]map[string]*nickWindow // channel → nick → window |
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alerted map[string]time.Time // key → last alert time (cooldown) |
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} |
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// New creates a snitch Bot. |
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func New(cfg Config, log *slog.Logger) *Bot { |
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cfg.setDefaults() |
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return &Bot{ |
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cfg: cfg, |
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log: log, |
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windows: make(map[string]map[string]*nickWindow), |
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alerted: make(map[string]time.Time), |
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} |
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} |
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// Start connects to IRC and begins surveillance. Blocks until ctx is done. |
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func (b *Bot) Start(ctx context.Context) error { |
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host, port, err := splitHostPort(b.cfg.IRCAddr) |
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if err != nil { |
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return fmt.Errorf("snitch: %w", err) |
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} |
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c := girc.New(girc.Config{ |
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Server: host, |
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Port: port, |
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Nick: b.cfg.Nick, |
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User: b.cfg.Nick, |
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Name: "scuttlebot snitch", |
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SASL: &girc.SASLPlain{User: b.cfg.Nick, Pass: b.cfg.Password}, |
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PingDelay: 30 * time.Second, |
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PingTimeout: 30 * time.Second, |
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}) |
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c.Handlers.AddBg(girc.CONNECTED, func(cl *girc.Client, _ girc.Event) { |
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cl.Cmd.Mode(cl.GetNick(), "+B") |
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for _, ch := range b.cfg.Channels { |
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cl.Cmd.Join(ch) |
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} |
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if b.cfg.AlertChannel != "" { |
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cl.Cmd.Join(b.cfg.AlertChannel) |
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} |
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if len(b.cfg.MonitorNicks) > 0 { |
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cl.Cmd.SendRawf("MONITOR + %s", strings.Join(b.cfg.MonitorNicks, ",")) |
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} |
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if b.log != nil { |
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b.log.Info("snitch connected", "channels", b.cfg.Channels, "monitor", b.cfg.MonitorNicks) |
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} |
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}) |
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// away-notify: track agents going idle or returning. |
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c.Handlers.AddBg(girc.AWAY, func(_ *girc.Client, e girc.Event) { |
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if e.Source == nil { |
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return |
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} |
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nick := e.Source.Name |
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reason := e.Last() |
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if reason != "" { |
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b.alert(fmt.Sprintf("agent away: %s (%s)", nick, reason)) |
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} |
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}) |
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c.Handlers.AddBg(girc.RPL_MONOFFLINE, func(_ *girc.Client, e girc.Event) { |
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nicks := e.Last() |
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for _, nick := range strings.Split(nicks, ",") { |
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nick = strings.TrimSpace(nick) |
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if nick == "" { |
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continue |
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} |
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b.alert(fmt.Sprintf("monitored nick offline: %s", nick)) |
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} |
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}) |
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c.Handlers.AddBg(girc.INVITE, func(cl *girc.Client, e girc.Event) { |
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if ch := e.Last(); strings.HasPrefix(ch, "#") { |
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cl.Cmd.Join(ch) |
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} |
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}) |
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c.Handlers.AddBg(girc.JOIN, func(_ *girc.Client, e girc.Event) { |
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if len(e.Params) < 1 || e.Source == nil || e.Source.Name == b.cfg.Nick { |
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return |
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} |
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b.recordJoinPart(e.Params[0], e.Source.Name) |
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}) |
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c.Handlers.AddBg(girc.PART, func(_ *girc.Client, e girc.Event) { |
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if len(e.Params) < 1 || e.Source == nil { |
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return |
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} |
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b.recordJoinPart(e.Params[0], e.Source.Name) |
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}) |
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router := cmdparse.NewRouter(b.cfg.Nick) |
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router.Register(cmdparse.Command{ |
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Name: "status", |
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Usage: "STATUS", |
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Description: "show current active alerts", |
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Handler: func(_ *cmdparse.Context, _ string) string { return "not implemented yet" }, |
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}) |
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router.Register(cmdparse.Command{ |
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Name: "acknowledge", |
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Usage: "ACKNOWLEDGE <alert-id>", |
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Description: "acknowledge an alert", |
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Handler: func(_ *cmdparse.Context, _ string) string { return "not implemented yet" }, |
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}) |
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c.Handlers.AddBg(girc.PRIVMSG, func(_ *girc.Client, e girc.Event) { |
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if len(e.Params) < 1 || e.Source == nil { |
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return |
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} |
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// Dispatch commands (DMs and channel messages). |
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if reply := router.Dispatch(e.Source.Name, e.Params[0], e.Last()); reply != nil { |
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c.Cmd.Message(reply.Target, reply.Text) |
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return |
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} |
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channel := e.Params[0] |
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nick := e.Source.Name |
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if nick == b.cfg.Nick { |
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return |
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} |
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b.recordMsg(channel, nick) |
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b.checkFlood(c, channel, nick) |
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}) |
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b.client = c |
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errCh := make(chan error, 1) |
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go func() { |
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if err := c.Connect(); err != nil && ctx.Err() == nil { |
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errCh <- err |
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} |
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}() |
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select { |
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case <-ctx.Done(): |
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c.Close() |
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return nil |
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case err := <-errCh: |
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return fmt.Errorf("snitch: irc: %w", err) |
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} |
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} |
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func (b *Bot) JoinChannel(channel string) { |
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if b.client != nil { |
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b.client.Cmd.Join(channel) |
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} |
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} |
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// MonitorAdd adds nicks to the MONITOR list at runtime. |
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func (b *Bot) MonitorAdd(nicks ...string) { |
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if b.client != nil && len(nicks) > 0 { |
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b.client.Cmd.SendRawf("MONITOR + %s", strings.Join(nicks, ",")) |
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} |
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} |
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// MonitorRemove removes nicks from the MONITOR list at runtime. |
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func (b *Bot) MonitorRemove(nicks ...string) { |
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if b.client != nil && len(nicks) > 0 { |
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b.client.Cmd.SendRawf("MONITOR - %s", strings.Join(nicks, ",")) |
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} |
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} |
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func (b *Bot) window(channel, nick string) *nickWindow { |
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if b.windows[channel] == nil { |
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b.windows[channel] = make(map[string]*nickWindow) |
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} |
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if b.windows[channel][nick] == nil { |
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b.windows[channel][nick] = &nickWindow{} |
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} |
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return b.windows[channel][nick] |
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} |
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func (b *Bot) recordMsg(channel, nick string) { |
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b.mu.Lock() |
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defer b.mu.Unlock() |
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now := time.Now() |
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w := b.window(channel, nick) |
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w.trim(now, b.cfg.FloodWindow, b.cfg.JoinPartWindow) |
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w.msgs = append(w.msgs, now) |
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} |
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func (b *Bot) recordJoinPart(channel, nick string) { |
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b.mu.Lock() |
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defer b.mu.Unlock() |
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now := time.Now() |
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w := b.window(channel, nick) |
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w.trim(now, b.cfg.FloodWindow, b.cfg.JoinPartWindow) |
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w.joinPart = append(w.joinPart, now) |
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if len(w.joinPart) >= b.cfg.JoinPartThreshold { |
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go b.alert(fmt.Sprintf("join/part cycling: %s in %s (%d events in %s)", |
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nick, channel, len(w.joinPart), b.cfg.JoinPartWindow)) |
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w.joinPart = nil |
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} |
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} |
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func (b *Bot) checkFlood(c *girc.Client, channel, nick string) { |
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b.mu.Lock() |
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defer b.mu.Unlock() |
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now := time.Now() |
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w := b.window(channel, nick) |
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w.trim(now, b.cfg.FloodWindow, b.cfg.JoinPartWindow) |
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if len(w.msgs) >= b.cfg.FloodMessages { |
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key := "flood:" + channel + ":" + nick |
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if last, ok := b.alerted[key]; !ok || now.Sub(last) > 60*time.Second { |
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b.alerted[key] = now |
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go b.alert(fmt.Sprintf("flood detected: %s in %s (%d msgs in %s)", |
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nick, channel, len(w.msgs), b.cfg.FloodWindow)) |
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} |
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} |
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} |
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func (b *Bot) alert(msg string) { |
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if b.client == nil { |
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return |
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} |
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if b.log != nil { |
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b.log.Warn("snitch alert", "msg", msg) |
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} |
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full := "[snitch] " + msg |
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if b.cfg.AlertChannel != "" { |
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b.client.Cmd.Message(b.cfg.AlertChannel, full) |
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} |
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for _, nick := range b.cfg.AlertNicks { |
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b.client.Cmd.Message(nick, full) |
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} |
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} |
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func splitHostPort(addr string) (string, int, error) { |
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host, portStr, err := net.SplitHostPort(addr) |
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if err != nil { |
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return "", 0, fmt.Errorf("invalid address %q: %w", addr, err) |
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} |
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port, err := strconv.Atoi(portStr) |
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if err != nil { |
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return "", 0, fmt.Errorf("invalid port in %q: %w", addr, err) |
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} |
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return host, port, nil |
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} |
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