package server import ( "errors" "fmt" "heckel.io/ntfy/log" "heckel.io/ntfy/user" "net/netip" "sync" "time" "golang.org/x/time/rate" "heckel.io/ntfy/util" ) const ( // oneDay is an approximation of a day as a time.Duration oneDay = 24 * time.Hour // visitorExpungeAfter defines how long a visitor is active before it is removed from memory. This number // has to be very high to prevent e-mail abuse, but it doesn't really affect the other limits anyway, since // they are replenished faster (typically). visitorExpungeAfter = oneDay // visitorDefaultReservationsLimit is the amount of topic names a user without a tier is allowed to reserve. // This number is zero, and changing it may have unintended consequences in the web app, or otherwise visitorDefaultReservationsLimit = int64(0) ) // Constants used to convert a tier-user's MessageLimit (see user.Tier) into adequate request limiter // values (token bucket). // // Example: Assuming a user.Tier's MessageLimit is 10,000: // - the allowed burst is 500 (= 10,000 * 5%), which is < 1000 (the max) // - the replenish rate is 2 * 10,000 / 24 hours const ( visitorMessageToRequestLimitBurstRate = 0.05 visitorMessageToRequestLimitBurstMax = 1000 visitorMessageToRequestLimitReplenishFactor = 2 ) // Constants used to convert a tier-user's EmailLimit (see user.Tier) into adequate email limiter // values (token bucket). Example: Assuming a user.Tier's EmailLimit is 200, the allowed burst is // 40 (= 200 * 20%), which is <150 (the max). const ( visitorEmailLimitBurstRate = 0.2 visitorEmailLimitBurstMax = 150 ) var ( errVisitorLimitReached = errors.New("limit reached") ) // visitor represents an API user, and its associated rate.Limiter used for rate limiting type visitor struct { config *Config messageCache *messageCache userManager *user.Manager // May be nil ip netip.Addr // Visitor IP address user *user.User // Only set if authenticated user, otherwise nil requestLimiter *rate.Limiter // Rate limiter for (almost) all requests (including messages) messagesLimiter *util.FixedLimiter // Rate limiter for messages emailsLimiter *util.RateLimiter // Rate limiter for emails subscriptionLimiter *util.FixedLimiter // Fixed limiter for active subscriptions (ongoing connections) bandwidthLimiter *util.RateLimiter // Limiter for attachment bandwidth downloads accountLimiter *rate.Limiter // Rate limiter for account creation, may be nil firebase time.Time // Next allowed Firebase message seen time.Time // Last seen time of this visitor (needed for removal of stale visitors) mu sync.Mutex } type visitorInfo struct { Limits *visitorLimits Stats *visitorStats } type visitorLimits struct { Basis visitorLimitBasis RequestLimitBurst int RequestLimitReplenish rate.Limit MessageLimit int64 MessageExpiryDuration time.Duration EmailLimit int64 EmailLimitBurst int EmailLimitReplenish rate.Limit ReservationsLimit int64 AttachmentTotalSizeLimit int64 AttachmentFileSizeLimit int64 AttachmentExpiryDuration time.Duration AttachmentBandwidthLimit int64 } type visitorStats struct { Messages int64 MessagesRemaining int64 Emails int64 EmailsRemaining int64 Reservations int64 ReservationsRemaining int64 AttachmentTotalSize int64 AttachmentTotalSizeRemaining int64 } // visitorLimitBasis describes how the visitor limits were derived, either from a user's // IP address (default config), or from its tier type visitorLimitBasis string const ( visitorLimitBasisIP = visitorLimitBasis("ip") visitorLimitBasisTier = visitorLimitBasis("tier") ) func newVisitor(conf *Config, messageCache *messageCache, userManager *user.Manager, ip netip.Addr, user *user.User) *visitor { var messages, emails int64 if user != nil { messages = user.Stats.Messages emails = user.Stats.Emails } v := &visitor{ config: conf, messageCache: messageCache, userManager: userManager, // May be nil ip: ip, user: user, firebase: time.Unix(0, 0), seen: time.Now(), subscriptionLimiter: util.NewFixedLimiter(int64(conf.VisitorSubscriptionLimit)), requestLimiter: nil, // Set in resetLimiters messagesLimiter: nil, // Set in resetLimiters, may be nil emailsLimiter: nil, // Set in resetLimiters bandwidthLimiter: nil, // Set in resetLimiters accountLimiter: nil, // Set in resetLimiters, may be nil } v.resetLimitersNoLock(messages, emails, false) return v } func (v *visitor) Context() log.Context { v.mu.Lock() defer v.mu.Unlock() return v.contextNoLock() } func (v *visitor) contextNoLock() log.Context { info := v.infoLightNoLock() fields := log.Context{ "visitor_ip": v.ip.String(), "visitor_messages": info.Stats.Messages, "visitor_messages_limit": info.Limits.MessageLimit, "visitor_messages_remaining": info.Stats.MessagesRemaining, "visitor_emails": info.Stats.Emails, "visitor_emails_limit": info.Limits.EmailLimit, "visitor_emails_remaining": info.Stats.EmailsRemaining, "visitor_request_limiter_limit": v.requestLimiter.Limit(), "visitor_request_limiter_tokens": v.requestLimiter.Tokens(), } if v.user != nil { fields["user_id"] = v.user.ID fields["user_name"] = v.user.Name if v.user.Tier != nil { fields["tier_id"] = v.user.Tier.ID fields["tier_name"] = v.user.Tier.Name } if v.user.Billing.StripeCustomerID != "" { fields["stripe_customer_id"] = v.user.Billing.StripeCustomerID } if v.user.Billing.StripeSubscriptionID != "" { fields["stripe_subscription_id"] = v.user.Billing.StripeSubscriptionID } } return fields } func visitorExtendedInfoContext(info *visitorInfo) log.Context { return log.Context{ "visitor_reservations": info.Stats.Reservations, "visitor_reservations_limit": info.Limits.ReservationsLimit, "visitor_reservations_remaining": info.Stats.ReservationsRemaining, "visitor_attachment_total_size": info.Stats.AttachmentTotalSize, "visitor_attachment_total_size_limit": info.Limits.AttachmentTotalSizeLimit, "visitor_attachment_total_size_remaining": info.Stats.AttachmentTotalSizeRemaining, } } func (v *visitor) RequestAllowed() error { v.mu.Lock() // limiters could be replaced! defer v.mu.Unlock() if !v.requestLimiter.Allow() { return errVisitorLimitReached } return nil } func (v *visitor) RequestLimiter() *rate.Limiter { v.mu.Lock() // limiters could be replaced! defer v.mu.Unlock() return v.requestLimiter } func (v *visitor) FirebaseAllowed() error { v.mu.Lock() defer v.mu.Unlock() if time.Now().Before(v.firebase) { return errVisitorLimitReached } return nil } func (v *visitor) FirebaseTemporarilyDeny() { v.mu.Lock() defer v.mu.Unlock() v.firebase = time.Now().Add(v.config.FirebaseQuotaExceededPenaltyDuration) } func (v *visitor) MessageAllowed() bool { v.mu.Lock() // limiters could be replaced! defer v.mu.Unlock() return v.messagesLimiter.Allow() } func (v *visitor) EmailAllowed() bool { v.mu.Lock() // limiters could be replaced! defer v.mu.Unlock() return v.emailsLimiter.Allow() } func (v *visitor) SubscriptionAllowed() bool { v.mu.Lock() // limiters could be replaced! defer v.mu.Unlock() return v.subscriptionLimiter.Allow() } func (v *visitor) AccountCreationAllowed() bool { v.mu.Lock() // limiters could be replaced! defer v.mu.Unlock() if v.accountLimiter == nil || (v.accountLimiter != nil && !v.accountLimiter.Allow()) { return false } return true } func (v *visitor) BandwidthAllowed(bytes int64) bool { v.mu.Lock() // limiters could be replaced! defer v.mu.Unlock() return v.bandwidthLimiter.AllowN(bytes) } func (v *visitor) RemoveSubscription() { v.mu.Lock() defer v.mu.Unlock() v.subscriptionLimiter.AllowN(-1) } func (v *visitor) Keepalive() { v.mu.Lock() defer v.mu.Unlock() v.seen = time.Now() } func (v *visitor) BandwidthLimiter() util.Limiter { v.mu.Lock() // limiters could be replaced! defer v.mu.Unlock() return v.bandwidthLimiter } func (v *visitor) Stale() bool { v.mu.Lock() defer v.mu.Unlock() return time.Since(v.seen) > visitorExpungeAfter } func (v *visitor) Stats() *user.Stats { v.mu.Lock() // limiters could be replaced! defer v.mu.Unlock() return &user.Stats{ Messages: v.messagesLimiter.Value(), Emails: v.emailsLimiter.Value(), } } func (v *visitor) ResetStats() { v.mu.Lock() // limiters could be replaced! defer v.mu.Unlock() v.emailsLimiter.Reset() v.messagesLimiter.Reset() } // User returns the visitor user, or nil if there is none func (v *visitor) User() *user.User { v.mu.Lock() defer v.mu.Unlock() return v.user // May be nil } // IP returns the visitor IP address func (v *visitor) IP() netip.Addr { v.mu.Lock() defer v.mu.Unlock() return v.ip } // Authenticated returns true if a user successfully authenticated func (v *visitor) Authenticated() bool { v.mu.Lock() defer v.mu.Unlock() return v.user != nil } // SetUser sets the visitors user to the given value func (v *visitor) SetUser(u *user.User) { v.mu.Lock() defer v.mu.Unlock() shouldResetLimiters := v.user.TierID() != u.TierID() // TierID works with nil receiver v.user = u if shouldResetLimiters { v.resetLimitersNoLock(0, 0, true) } } // MaybeUserID returns the user ID of the visitor (if any). If this is an anonymous visitor, // an empty string is returned. func (v *visitor) MaybeUserID() string { v.mu.Lock() defer v.mu.Unlock() if v.user != nil { return v.user.ID } return "" } func (v *visitor) resetLimitersNoLock(messages, emails int64, enqueueUpdate bool) { limits := v.limitsNoLock() v.requestLimiter = rate.NewLimiter(limits.RequestLimitReplenish, limits.RequestLimitBurst) v.messagesLimiter = util.NewFixedLimiterWithValue(limits.MessageLimit, messages) v.emailsLimiter = util.NewRateLimiterWithValue(limits.EmailLimitReplenish, limits.EmailLimitBurst, emails) v.bandwidthLimiter = util.NewBytesLimiter(int(limits.AttachmentBandwidthLimit), oneDay) if v.user == nil { v.accountLimiter = rate.NewLimiter(rate.Every(v.config.VisitorAccountCreationLimitReplenish), v.config.VisitorAccountCreationLimitBurst) } else { v.accountLimiter = nil // Users cannot create accounts when logged in } if enqueueUpdate && v.user != nil { go v.userManager.EnqueueStats(v.user.ID, &user.Stats{ Messages: messages, Emails: emails, }) } log.Fields(v.contextNoLock()).Debug("Rate limiters reset for visitor") // Must be after function, because contextNoLock() describes rate limiters } func (v *visitor) Limits() *visitorLimits { v.mu.Lock() defer v.mu.Unlock() return v.limitsNoLock() } func (v *visitor) limitsNoLock() *visitorLimits { if v.user != nil && v.user.Tier != nil { return tierBasedVisitorLimits(v.config, v.user.Tier) } return configBasedVisitorLimits(v.config) } func tierBasedVisitorLimits(conf *Config, tier *user.Tier) *visitorLimits { return &visitorLimits{ Basis: visitorLimitBasisTier, RequestLimitBurst: util.MinMax(int(float64(tier.MessageLimit)*visitorMessageToRequestLimitBurstRate), conf.VisitorRequestLimitBurst, visitorMessageToRequestLimitBurstMax), RequestLimitReplenish: util.Max(rate.Every(conf.VisitorRequestLimitReplenish), dailyLimitToRate(tier.MessageLimit*visitorMessageToRequestLimitReplenishFactor)), MessageLimit: tier.MessageLimit, MessageExpiryDuration: tier.MessageExpiryDuration, EmailLimit: tier.EmailLimit, EmailLimitBurst: util.MinMax(int(float64(tier.EmailLimit)*visitorEmailLimitBurstRate), conf.VisitorEmailLimitBurst, visitorEmailLimitBurstMax), EmailLimitReplenish: dailyLimitToRate(tier.EmailLimit), ReservationsLimit: tier.ReservationLimit, AttachmentTotalSizeLimit: tier.AttachmentTotalSizeLimit, AttachmentFileSizeLimit: tier.AttachmentFileSizeLimit, AttachmentExpiryDuration: tier.AttachmentExpiryDuration, AttachmentBandwidthLimit: tier.AttachmentBandwidthLimit, } } func configBasedVisitorLimits(conf *Config) *visitorLimits { messagesLimit := replenishDurationToDailyLimit(conf.VisitorRequestLimitReplenish) // Approximation! if conf.VisitorMessageDailyLimit > 0 { messagesLimit = int64(conf.VisitorMessageDailyLimit) } return &visitorLimits{ Basis: visitorLimitBasisIP, RequestLimitBurst: conf.VisitorRequestLimitBurst, RequestLimitReplenish: rate.Every(conf.VisitorRequestLimitReplenish), MessageLimit: messagesLimit, MessageExpiryDuration: conf.CacheDuration, EmailLimit: replenishDurationToDailyLimit(conf.VisitorEmailLimitReplenish), // Approximation! EmailLimitBurst: conf.VisitorEmailLimitBurst, EmailLimitReplenish: rate.Every(conf.VisitorEmailLimitReplenish), ReservationsLimit: visitorDefaultReservationsLimit, AttachmentTotalSizeLimit: conf.VisitorAttachmentTotalSizeLimit, AttachmentFileSizeLimit: conf.AttachmentFileSizeLimit, AttachmentExpiryDuration: conf.AttachmentExpiryDuration, AttachmentBandwidthLimit: conf.VisitorAttachmentDailyBandwidthLimit, } } func (v *visitor) Info() (*visitorInfo, error) { v.mu.Lock() info := v.infoLightNoLock() v.mu.Unlock() // Attachment stats from database var attachmentsBytesUsed int64 var err error u := v.User() if u != nil { attachmentsBytesUsed, err = v.messageCache.AttachmentBytesUsedByUser(u.ID) } else { attachmentsBytesUsed, err = v.messageCache.AttachmentBytesUsedBySender(v.IP().String()) } if err != nil { return nil, err } info.Stats.AttachmentTotalSize = attachmentsBytesUsed info.Stats.AttachmentTotalSizeRemaining = zeroIfNegative(info.Limits.AttachmentTotalSizeLimit - attachmentsBytesUsed) // Reservation stats from database var reservations int64 if v.userManager != nil && u != nil { reservations, err = v.userManager.ReservationsCount(u.Name) if err != nil { return nil, err } } info.Stats.Reservations = reservations info.Stats.ReservationsRemaining = zeroIfNegative(info.Limits.ReservationsLimit - reservations) return info, nil } func (v *visitor) infoLightNoLock() *visitorInfo { messages := v.messagesLimiter.Value() emails := v.emailsLimiter.Value() limits := v.limitsNoLock() stats := &visitorStats{ Messages: messages, MessagesRemaining: zeroIfNegative(limits.MessageLimit - messages), Emails: emails, EmailsRemaining: zeroIfNegative(limits.EmailLimit - emails), } return &visitorInfo{ Limits: limits, Stats: stats, } } func zeroIfNegative(value int64) int64 { if value < 0 { return 0 } return value } func replenishDurationToDailyLimit(duration time.Duration) int64 { return int64(oneDay / duration) } func dailyLimitToRate(limit int64) rate.Limit { return rate.Limit(limit) * rate.Every(oneDay) } func visitorID(ip netip.Addr, u *user.User) string { if u != nil && u.Tier != nil { return fmt.Sprintf("user:%s", u.ID) } return fmt.Sprintf("ip:%s", ip.String()) }