Merge branch 'persistent.14'

irc/accounts.go

@@ -33,7 +33,9 @@ const (
 	keyAccountSettings         = "account.settings %s"
 	keyAccountVHost            = "account.vhost %s"
 	keyCertToAccount           = "account.creds.certfp %s"
-	keyAccountChannels         = "account.channels %s"
+	keyAccountChannels         = "account.channels %s" // channels registered to the account
+	keyAccountJoinedChannels   = "account.joinedto %s" // channels a persistent client has joined
+	keyAccountLastSignoff      = "account.lastsignoff %s"
 
 	keyVHostQueueAcctToId = "vhostQueue %s"
 	vhostRequestIdx       = "vhostQueue"
@@ -71,6 +73,40 @@ func (am *AccountManager) Initialize(server *Server) {
 	config := server.Config()
 	am.buildNickToAccountIndex(config)
 	am.initVHostRequestQueue(config)
+	am.createAlwaysOnClients(config)
+}
+
+func (am *AccountManager) createAlwaysOnClients(config *Config) {
+	if config.Accounts.Multiclient.AlwaysOn == PersistentDisabled {
+		return
+	}
+
+	verifiedPrefix := fmt.Sprintf(keyAccountVerified, "")
+
+	am.serialCacheUpdateMutex.Lock()
+	defer am.serialCacheUpdateMutex.Unlock()
+
+	var accounts []string
+
+	am.server.store.View(func(tx *buntdb.Tx) error {
+		err := tx.AscendGreaterOrEqual("", verifiedPrefix, func(key, value string) bool {
+			if !strings.HasPrefix(key, verifiedPrefix) {
+				return false
+			}
+			account := strings.TrimPrefix(key, verifiedPrefix)
+			accounts = append(accounts, account)
+			return true
+		})
+		return err
+	})
+
+	for _, accountName := range accounts {
+		account, err := am.LoadAccount(accountName)
+		if err == nil && account.Verified &&
+			persistenceEnabled(config.Accounts.Multiclient.AlwaysOn, account.Settings.AlwaysOn) {
+			am.server.AddAlwaysOnClient(account, am.loadChannels(accountName), am.loadLastSignoff(accountName))
+		}
+	}
 }
 
 func (am *AccountManager) buildNickToAccountIndex(config *Config) {
@@ -346,7 +382,7 @@ func (am *AccountManager) Register(client *Client, account string, callbackNames
 	callbackSpec := fmt.Sprintf("%s:%s", callbackNamespace, callbackValue)
 
 	var setOptions *buntdb.SetOptions
-	ttl := config.Registration.VerifyTimeout
+	ttl := time.Duration(config.Registration.VerifyTimeout)
 	if ttl != 0 {
 		setOptions = &buntdb.SetOptions{Expires: true, TTL: ttl}
 	}
@@ -477,6 +513,58 @@ func (am *AccountManager) setPassword(account string, password string, hasPrivs
 	return err
 }
 
+func (am *AccountManager) saveChannels(account string, channels []string) {
+	channelsStr := strings.Join(channels, ",")
+	key := fmt.Sprintf(keyAccountJoinedChannels, account)
+	am.server.store.Update(func(tx *buntdb.Tx) error {
+		tx.Set(key, channelsStr, nil)
+		return nil
+	})
+}
+
+func (am *AccountManager) loadChannels(account string) (channels []string) {
+	key := fmt.Sprintf(keyAccountJoinedChannels, account)
+	var channelsStr string
+	am.server.store.View(func(tx *buntdb.Tx) error {
+		channelsStr, _ = tx.Get(key)
+		return nil
+	})
+	if channelsStr != "" {
+		return strings.Split(channelsStr, ",")
+	}
+	return
+}
+
+func (am *AccountManager) saveLastSignoff(account string, lastSignoff time.Time) {
+	key := fmt.Sprintf(keyAccountLastSignoff, account)
+	var val string
+	if !lastSignoff.IsZero() {
+		val = strconv.FormatInt(lastSignoff.UnixNano(), 10)
+	}
+	am.server.store.Update(func(tx *buntdb.Tx) error {
+		if val != "" {
+			tx.Set(key, val, nil)
+		} else {
+			tx.Delete(key)
+		}
+		return nil
+	})
+}
+
+func (am *AccountManager) loadLastSignoff(account string) (lastSignoff time.Time) {
+	key := fmt.Sprintf(keyAccountLastSignoff, account)
+	var lsText string
+	am.server.store.View(func(tx *buntdb.Tx) error {
+		lsText, _ = tx.Get(key)
+		return nil
+	})
+	lsNum, err := strconv.ParseInt(lsText, 10, 64)
+	if err != nil {
+		return time.Unix(0, lsNum).UTC()
+	}
+	return
+}
+
 func (am *AccountManager) addRemoveCertfp(account, certfp string, add bool, hasPrivs bool) (err error) {
 	certfp, err = utils.NormalizeCertfp(certfp)
 	if err != nil {
@@ -685,7 +773,7 @@ func (am *AccountManager) Verify(client *Client, account string, code string) er
 	}
 	am.server.logger.Info("accounts", "client", nick, "registered account", casefoldedAccount)
 	raw.Verified = true
-	clientAccount, err := am.deserializeRawAccount(raw)
+	clientAccount, err := am.deserializeRawAccount(raw, casefoldedAccount)
 	if err != nil {
 		return err
 	}
@@ -892,13 +980,13 @@ func (am *AccountManager) LoadAccount(accountName string) (result ClientAccount,
 		return
 	}
 
-	result, err = am.deserializeRawAccount(raw)
-	result.NameCasefolded = casefoldedAccount
+	result, err = am.deserializeRawAccount(raw, casefoldedAccount)
 	return
 }
 
-func (am *AccountManager) deserializeRawAccount(raw rawClientAccount) (result ClientAccount, err error) {
+func (am *AccountManager) deserializeRawAccount(raw rawClientAccount, cfName string) (result ClientAccount, err error) {
 	result.Name = raw.Name
+	result.NameCasefolded = cfName
 	regTimeInt, _ := strconv.ParseInt(raw.RegisteredAt, 10, 64)
 	result.RegisteredAt = time.Unix(regTimeInt, 0).UTC()
 	e := json.Unmarshal([]byte(raw.Credentials), &result.Credentials)
@@ -976,6 +1064,8 @@ func (am *AccountManager) Unregister(account string) error {
 	vhostKey := fmt.Sprintf(keyAccountVHost, casefoldedAccount)
 	vhostQueueKey := fmt.Sprintf(keyVHostQueueAcctToId, casefoldedAccount)
 	channelsKey := fmt.Sprintf(keyAccountChannels, casefoldedAccount)
+	joinedChannelsKey := fmt.Sprintf(keyAccountJoinedChannels, casefoldedAccount)
+	lastSignoffKey := fmt.Sprintf(keyAccountLastSignoff, casefoldedAccount)
 
 	var clients []*Client
 
@@ -1011,6 +1101,8 @@ func (am *AccountManager) Unregister(account string) error {
 		tx.Delete(vhostKey)
 		channelsStr, _ = tx.Get(channelsKey)
 		tx.Delete(channelsKey)
+		tx.Delete(joinedChannelsKey)
+		tx.Delete(lastSignoffKey)
 
 		_, err := tx.Delete(vhostQueueKey)
 		am.decrementVHostQueueCount(casefoldedAccount, err)
@@ -1087,13 +1179,13 @@ func (am *AccountManager) ChannelsForAccount(account string) (channels []string)
 	return unmarshalRegisteredChannels(channelStr)
 }
 
-func (am *AccountManager) AuthenticateByCertFP(client *Client, authzid string) error {
-	if client.certfp == "" {
+func (am *AccountManager) AuthenticateByCertFP(client *Client, certfp, authzid string) error {
+	if certfp == "" {
 		return errAccountInvalidCredentials
 	}
 
 	var account string
-	certFPKey := fmt.Sprintf(keyCertToAccount, client.certfp)
+	certFPKey := fmt.Sprintf(keyCertToAccount, certfp)
 
 	err := am.server.store.View(func(tx *buntdb.Tx) error {
 		account, _ = tx.Get(certFPKey)
@@ -1455,10 +1547,7 @@ func (am *AccountManager) applyVhostToClients(account string, result VHostInfo)
 }
 
 func (am *AccountManager) Login(client *Client, account ClientAccount) {
-	changed := client.SetAccountName(account.Name)
-	if !changed {
-		return
-	}
+	client.Login(account)
 
 	client.nickTimer.Touch(nil)
 
@@ -1468,9 +1557,6 @@ func (am *AccountManager) Login(client *Client, account ClientAccount) {
 	am.Lock()
 	defer am.Unlock()
 	am.accountToClients[casefoldedAccount] = append(am.accountToClients[casefoldedAccount], client)
-	for _, client := range am.accountToClients[casefoldedAccount] {
-		client.SetAccountSettings(account.Settings)
-	}
 }
 
 func (am *AccountManager) Logout(client *Client) {
@@ -1590,12 +1676,12 @@ func (ac *AccountCredentials) RemoveCertfp(certfp string) (err error) {
 	return nil
 }
 
-type BouncerAllowedSetting int
+type MulticlientAllowedSetting int
 
 const (
-	BouncerAllowedServerDefault BouncerAllowedSetting = iota
-	BouncerDisallowedByUser
-	BouncerAllowedByUser
+	MulticlientAllowedServerDefault MulticlientAllowedSetting = iota
+	MulticlientDisallowedByUser
+	MulticlientAllowedByUser
 )
 
 // controls whether/when clients without event-playback support see fake
@@ -1622,11 +1708,16 @@ func replayJoinsSettingFromString(str string) (result ReplayJoinsSetting, err er
 	return
 }
 
+// XXX: AllowBouncer cannot be renamed AllowMulticlient because it is stored in
+// persistent JSON blobs in the database
 type AccountSettings struct {
-	AutoreplayLines *int
-	NickEnforcement NickEnforcementMethod
-	AllowBouncer    BouncerAllowedSetting
-	ReplayJoins     ReplayJoinsSetting
+	AutoreplayLines  *int
+	NickEnforcement  NickEnforcementMethod
+	AllowBouncer     MulticlientAllowedSetting
+	ReplayJoins      ReplayJoinsSetting
+	AlwaysOn         PersistentStatus
+	AutoreplayMissed bool
+	DMHistory        HistoryStatus
 }
 
 // ClientAccount represents a user account.
@@ -1661,7 +1752,7 @@ func (am *AccountManager) logoutOfAccount(client *Client) {
 		return
 	}
 
-	client.SetAccountName("")
+	client.Logout()
 	go client.nickTimer.Touch(nil)
 
 	// dispatch account-notify

irc/caps/defs.go

@@ -37,6 +37,10 @@ const (
 	// https://ircv3.net/specs/extensions/chghost-3.2.html
 	ChgHost Capability = iota
 
+	// Chathistory is the proposed IRCv3 capability named "draft/chathistory":
+	// https://github.com/ircv3/ircv3-specifications/pull/393
+	Chathistory Capability = iota
+
 	// EventPlayback is the proposed IRCv3 capability named "draft/event-playback":
 	// https://github.com/ircv3/ircv3-specifications/pull/362
 	EventPlayback Capability = iota
@@ -85,10 +89,6 @@ const (
 	// https://ircv3.net/specs/extensions/multi-prefix-3.1.html
 	MultiPrefix Capability = iota
 
-	// Bouncer is the Oragono-specific capability named "oragono.io/bnc":
-	// https://oragono.io/bnc
-	Bouncer Capability = iota
-
 	// Nope is the Oragono vendor capability named "oragono.io/nope":
 	// https://oragono.io/nope
 	Nope Capability = iota
@@ -127,6 +127,7 @@ var (
 		"batch",
 		"cap-notify",
 		"chghost",
+		"draft/chathistory",
 		"draft/event-playback",
 		"draft/languages",
 		"draft/multiline",
@@ -139,7 +140,6 @@ var (
 		"labeled-response",
 		"message-tags",
 		"multi-prefix",
-		"oragono.io/bnc",
 		"oragono.io/nope",
 		"sasl",
 		"server-time",

irc/channel.go

@@ -24,6 +24,10 @@ const (
 	histServMask = "HistServ!HistServ@localhost"
 )
 
+type ChannelSettings struct {
+	History HistoryStatus
+}
+
 // Channel represents a channel that clients can join.
 type Channel struct {
 	flags             modes.ModeSet
@@ -49,6 +53,7 @@ type Channel struct {
 	joinPartMutex     sync.Mutex      // tier 3
 	ensureLoaded      utils.Once      // manages loading stored registration info from the database
 	dirtyBits         uint
+	settings          ChannelSettings
 }
 
 // NewChannel creates a new channel from a `Server` and a `name`
@@ -66,9 +71,10 @@ func NewChannel(s *Server, name, casefoldedName string, registered bool) *Channe
 
 	channel.initializeLists()
 	channel.writerSemaphore.Initialize(1)
-	channel.history.Initialize(config.History.ChannelLength, config.History.AutoresizeWindow)
+	channel.history.Initialize(0, 0)
 
 	if !registered {
+		channel.resizeHistory(config)
 		for _, mode := range config.Channels.defaultModes {
 			channel.flags.SetMode(mode, true)
 		}
@@ -106,8 +112,19 @@ func (channel *Channel) IsLoaded() bool {
 	return channel.ensureLoaded.Done()
 }
 
+func (channel *Channel) resizeHistory(config *Config) {
+	_, ephemeral, _ := channel.historyStatus(config)
+	if ephemeral {
+		channel.history.Resize(config.History.ChannelLength, config.History.AutoresizeWindow)
+	} else {
+		channel.history.Resize(0, 0)
+	}
+}
+
 // read in channel state that was persisted in the DB
 func (channel *Channel) applyRegInfo(chanReg RegisteredChannel) {
+	defer channel.resizeHistory(channel.server.Config())
+
 	channel.stateMutex.Lock()
 	defer channel.stateMutex.Unlock()
 
@@ -120,6 +137,7 @@ func (channel *Channel) applyRegInfo(chanReg RegisteredChannel) {
 	channel.createdTime = chanReg.RegisteredAt
 	channel.key = chanReg.Key
 	channel.userLimit = chanReg.UserLimit
+	channel.settings = chanReg.Settings
 
 	for _, mode := range chanReg.Modes {
 		channel.flags.SetMode(mode, true)
@@ -164,6 +182,10 @@ func (channel *Channel) ExportRegistration(includeFlags uint) (info RegisteredCh
 		}
 	}
 
+	if includeFlags&IncludeSettings != 0 {
+		info.Settings = channel.settings
+	}
+
 	return
 }
 
@@ -434,7 +456,7 @@ func (channel *Channel) Names(client *Client, rb *ResponseBuffer) {
 			if modeSet == nil {
 				continue
 			}
-			if !isJoined && target.flags.HasMode(modes.Invisible) && !isOper {
+			if !isJoined && target.HasMode(modes.Invisible) && !isOper {
 				continue
 			}
 			prefix := modeSet.Prefixes(isMultiPrefix)
@@ -564,6 +586,48 @@ func (channel *Channel) IsEmpty() bool {
 	return len(channel.members) == 0
 }
 
+// figure out where history is being stored: persistent, ephemeral, or neither
+// target is only needed if we're doing persistent history
+func (channel *Channel) historyStatus(config *Config) (persistent, ephemeral bool, target string) {
+	if !config.History.Persistent.Enabled {
+		return false, config.History.Enabled, ""
+	}
+
+	channel.stateMutex.RLock()
+	target = channel.nameCasefolded
+	historyStatus := channel.settings.History
+	registered := channel.registeredFounder != ""
+	channel.stateMutex.RUnlock()
+
+	historyStatus = historyEnabled(config.History.Persistent.RegisteredChannels, historyStatus)
+
+	// ephemeral history: either the channel owner explicitly set the ephemeral preference,
+	// or persistent history is disabled for unregistered channels
+	if registered {
+		ephemeral = (historyStatus == HistoryEphemeral)
+		persistent = (historyStatus == HistoryPersistent)
+	} else {
+		ephemeral = config.History.Enabled && !config.History.Persistent.UnregisteredChannels
+		persistent = config.History.Persistent.UnregisteredChannels
+	}
+	return
+}
+
+func (channel *Channel) AddHistoryItem(item history.Item) (err error) {
+	if !item.IsStorable() {
+		return
+	}
+
+	persistent, ephemeral, target := channel.historyStatus(channel.server.Config())
+	if ephemeral {
+		channel.history.Add(item)
+	}
+	if persistent {
+		return channel.server.historyDB.AddChannelItem(target, item)
+	}
+	return nil
+}
+
 // Join joins the given client to this channel (if they can be joined).
 func (channel *Channel) Join(client *Client, key string, isSajoin bool, rb *ResponseBuffer) {
 	details := client.Details()
@@ -618,8 +682,6 @@ func (channel *Channel) Join(client *Client, key string, isSajoin bool, rb *Resp
 
 	client.server.logger.Debug("join", fmt.Sprintf("%s joined channel %s", details.nick, chname))
 
-	var message utils.SplitMessage
-
 	givenMode := func() (givenMode modes.Mode) {
 		channel.joinPartMutex.Lock()
 		defer channel.joinPartMutex.Unlock()
@@ -643,6 +705,12 @@ func (channel *Channel) Join(client *Client, key string, isSajoin bool, rb *Resp
 
 		channel.regenerateMembersCache()
 
+		return
+	}()
+
+	var message utils.SplitMessage
+	// no history item for fake persistent joins
+	if rb != nil {
 		message = utils.MakeMessage("")
 		histItem := history.Item{
 			Type:        history.Join,
@@ -651,13 +719,15 @@ func (channel *Channel) Join(client *Client, key string, isSajoin bool, rb *Resp
 			Message:     message,
 		}
 		histItem.Params[0] = details.realname
-		channel.history.Add(histItem)
-
-		return
-	}()
+		channel.AddHistoryItem(histItem)
+	}
 
 	client.addChannel(channel)
 
+	if rb == nil {
+		return
+	}
+
 	var modestr string
 	if givenMode != 0 {
 		modestr = fmt.Sprintf("+%v", givenMode)
@@ -702,10 +772,22 @@ func (channel *Channel) Join(client *Client, key string, isSajoin bool, rb *Resp
 
 func (channel *Channel) autoReplayHistory(client *Client, rb *ResponseBuffer, skipMsgid string) {
 	// autoreplay any messages as necessary
-	config := channel.server.Config()
 	var items []history.Item
+
+	var after, before time.Time
 	if rb.session.zncPlaybackTimes != nil && (rb.session.zncPlaybackTimes.targets == nil || rb.session.zncPlaybackTimes.targets.Has(channel.NameCasefolded())) {
-		items, _ = channel.history.Between(rb.session.zncPlaybackTimes.after, rb.session.zncPlaybackTimes.before, false, config.History.ChathistoryMax)
+		after, before = rb.session.zncPlaybackTimes.after, rb.session.zncPlaybackTimes.before
+	} else if !rb.session.lastSignoff.IsZero() {
+		// we already checked for history caps in `playReattachMessages`
+		after = rb.session.lastSignoff
+	}
+
+	if !after.IsZero() || !before.IsZero() {
+		_, seq, _ := channel.server.GetHistorySequence(channel, client, "")
+		if seq != nil {
+			zncMax := channel.server.Config().History.ZNCMax
+			items, _, _ = seq.Between(history.Selector{Time: after}, history.Selector{Time: before}, zncMax)
+		}
 	} else if !rb.session.HasHistoryCaps() {
 		var replayLimit int
 		customReplayLimit := client.AccountSettings().AutoreplayLines
@@ -719,7 +801,10 @@ func (channel *Channel) autoReplayHistory(client *Client, rb *ResponseBuffer, sk
 			replayLimit = channel.server.Config().History.AutoreplayOnJoin
 		}
 		if 0 < replayLimit {
-			items = channel.history.Latest(replayLimit)
+			_, seq, _ := channel.server.GetHistorySequence(channel, client, "")
+			if seq != nil {
+				items, _, _ = seq.Between(history.Selector{}, history.Selector{}, replayLimit)
+			}
 		}
 	}
 	// remove the client's own JOIN line from the replay
@@ -784,7 +869,7 @@ func (channel *Channel) Part(client *Client, message string, rb *ResponseBuffer)
 		}
 	}
 
-	channel.history.Add(history.Item{
+	channel.AddHistoryItem(history.Item{
 		Type:        history.Part,
 		Nick:        details.nickMask,
 		AccountName: details.accountName,
@@ -799,10 +884,9 @@ func (channel *Channel) Part(client *Client, message string, rb *ResponseBuffer)
 // 2. Send JOIN and MODE lines to channel participants (including the new client)
 // 3. Replay missed message history to the client
 func (channel *Channel) Resume(session *Session, timestamp time.Time) {
-	now := time.Now().UTC()
 	channel.resumeAndAnnounce(session)
 	if !timestamp.IsZero() {
-		channel.replayHistoryForResume(session, timestamp, now)
+		channel.replayHistoryForResume(session, timestamp, time.Time{})
 	}
 }
 
@@ -852,9 +936,17 @@ func (channel *Channel) resumeAndAnnounce(session *Session) {
 }
 
 func (channel *Channel) replayHistoryForResume(session *Session, after time.Time, before time.Time) {
-	items, complete := channel.history.Between(after, before, false, 0)
+	var items []history.Item
+	var complete bool
+	afterS, beforeS := history.Selector{Time: after}, history.Selector{Time: before}
+	_, seq, _ := channel.server.GetHistorySequence(channel, session.client, "")
+	if seq != nil {
+		items, complete, _ = seq.Between(afterS, beforeS, channel.server.Config().History.ZNCMax)
+	}
 	rb := NewResponseBuffer(session)
-	channel.replayHistoryItems(rb, items, false)
+	if len(items) != 0 {
+		channel.replayHistoryItems(rb, items, false)
+	}
 	if !complete && !session.resumeDetails.HistoryIncomplete {
 		// warn here if we didn't warn already
 		rb.Add(nil, histServMask, "NOTICE", channel.Name(), session.client.t("Some additional message history may have been lost"))
@@ -871,10 +963,7 @@ func stripMaskFromNick(nickMask string) (nick string) {
 }
 
 func (channel *Channel) replayHistoryItems(rb *ResponseBuffer, items []history.Item, autoreplay bool) {
-	if len(items) == 0 {
-		return
-	}
-
+	// send an empty batch if necessary, as per the CHATHISTORY spec
 	chname := channel.Name()
 	client := rb.target
 	eventPlayback := rb.session.capabilities.Has(caps.EventPlayback)
@@ -908,9 +997,9 @@ func (channel *Channel) replayHistoryItems(rb *ResponseBuffer, items []history.I
 		case history.Join:
 			if eventPlayback {
 				if extendedJoin {
-					rb.AddFromClient(item.Message.Time, item.Message.Msgid, item.Nick, item.AccountName, nil, "HEVENT", "JOIN", chname, item.AccountName, item.Params[0])
+					rb.AddFromClient(item.Message.Time, item.Message.Msgid, item.Nick, item.AccountName, nil, "JOIN", chname, item.AccountName, item.Params[0])
 				} else {
-					rb.AddFromClient(item.Message.Time, item.Message.Msgid, item.Nick, item.AccountName, nil, "HEVENT", "JOIN", chname)
+					rb.AddFromClient(item.Message.Time, item.Message.Msgid, item.Nick, item.AccountName, nil, "JOIN", chname)
 				}
 			} else {
 				if !playJoinsAsPrivmsg {
@@ -926,7 +1015,7 @@ func (channel *Channel) replayHistoryItems(rb *ResponseBuffer, items []history.I
 			}
 		case history.Part:
 			if eventPlayback {
-				rb.AddFromClient(item.Message.Time, item.Message.Msgid, item.Nick, item.AccountName, nil, "HEVENT", "PART", chname, item.Message.Message)
+				rb.AddFromClient(item.Message.Time, item.Message.Msgid, item.Nick, item.AccountName, nil, "PART", chname, item.Message.Message)
 			} else {
 				if !playJoinsAsPrivmsg {
 					continue // #474
@@ -936,14 +1025,14 @@ func (channel *Channel) replayHistoryItems(rb *ResponseBuffer, items []history.I
 			}
 		case history.Kick:
 			if eventPlayback {
-				rb.AddFromClient(item.Message.Time, item.Message.Msgid, item.Nick, item.AccountName, nil, "HEVENT", "KICK", chname, item.Params[0], item.Message.Message)
+				rb.AddFromClient(item.Message.Time, item.Message.Msgid, item.Nick, item.AccountName, nil, "KICK", chname, item.Params[0], item.Message.Message)
 			} else {
 				message := fmt.Sprintf(client.t("%[1]s kicked %[2]s (%[3]s)"), nick, item.Params[0], item.Message.Message)
 				rb.AddFromClient(item.Message.Time, utils.MungeSecretToken(item.Message.Msgid), histServMask, "*", nil, "PRIVMSG", chname, message)
 			}
 		case history.Quit:
 			if eventPlayback {
-				rb.AddFromClient(item.Message.Time, item.Message.Msgid, item.Nick, item.AccountName, nil, "HEVENT", "QUIT", item.Message.Message)
+				rb.AddFromClient(item.Message.Time, item.Message.Msgid, item.Nick, item.AccountName, nil, "QUIT", item.Message.Message)
 			} else {
 				if !playJoinsAsPrivmsg {
 					continue // #474
@@ -953,7 +1042,7 @@ func (channel *Channel) replayHistoryItems(rb *ResponseBuffer, items []history.I
 			}
 		case history.Nick:
 			if eventPlayback {
-				rb.AddFromClient(item.Message.Time, item.Message.Msgid, item.Nick, item.AccountName, nil, "HEVENT", "NICK", item.Params[0])
+				rb.AddFromClient(item.Message.Time, item.Message.Msgid, item.Nick, item.AccountName, nil, "NICK", item.Params[0])
 			} else {
 				message := fmt.Sprintf(client.t("%[1]s changed nick to %[2]s"), nick, item.Params[0])
 				rb.AddFromClient(item.Message.Time, utils.MungeSecretToken(item.Message.Msgid), histServMask, "*", nil, "PRIVMSG", chname, message)
@@ -1124,11 +1213,12 @@ func (channel *Channel) SendSplitMessage(command string, minPrefixMode modes.Mod
 			// STATUSMSG
 			continue
 		}
-		if isCTCP && member.isTor {
-			continue // #753
-		}
 
 		for _, session := range member.Sessions() {
+			if isCTCP && session.isTor {
+				continue // #753
+			}
+
 			var tagsToUse map[string]string
 			if session.capabilities.Has(caps.MessageTags) {
 				tagsToUse = clientOnlyTags
@@ -1144,7 +1234,7 @@ func (channel *Channel) SendSplitMessage(command string, minPrefixMode modes.Mod
 		}
 	}
 
-	channel.history.Add(history.Item{
+	channel.AddHistoryItem(history.Item{
 		Type:        histType,
 		Message:     message,
 		Nick:        nickmask,
@@ -1266,7 +1356,7 @@ func (channel *Channel) Kick(client *Client, target *Client, comment string, rb
 		Message:     message,
 	}
 	histItem.Params[0] = targetNick
-	channel.history.Add(histItem)
+	channel.AddHistoryItem(histItem)
 
 	channel.Quit(target)
 }

irc/channelreg.go

@@ -33,6 +33,7 @@ const (
 	keyChannelModes          = "channel.modes %s"
 	keyChannelAccountToUMode = "channel.accounttoumode %s"
 	keyChannelUserLimit      = "channel.userlimit %s"
+	keyChannelSettings       = "channel.settings %s"
 
 	keyChannelPurged = "channel.purged %s"
 )
@@ -53,6 +54,7 @@ var (
 		keyChannelModes,
 		keyChannelAccountToUMode,
 		keyChannelUserLimit,
+		keyChannelSettings,
 	}
 )
 
@@ -63,6 +65,7 @@ const (
 	IncludeTopic
 	IncludeModes
 	IncludeLists
+	IncludeSettings
 )
 
 // this is an OR of all possible flags
@@ -100,6 +103,8 @@ type RegisteredChannel struct {
 	Excepts map[string]MaskInfo
 	// Invites represents the invite exceptions set on the channel.
 	Invites map[string]MaskInfo
+	// Settings are the chanserv-modifiable settings
+	Settings ChannelSettings
 }
 
 type ChannelPurgeRecord struct {
@@ -203,6 +208,7 @@ func (reg *ChannelRegistry) LoadChannel(nameCasefolded string) (info RegisteredC
 		exceptlistString, _ := tx.Get(fmt.Sprintf(keyChannelExceptlist, channelKey))
 		invitelistString, _ := tx.Get(fmt.Sprintf(keyChannelInvitelist, channelKey))
 		accountToUModeString, _ := tx.Get(fmt.Sprintf(keyChannelAccountToUMode, channelKey))
+		settingsString, _ := tx.Get(fmt.Sprintf(keyChannelSettings, channelKey))
 
 		modeSlice := make([]modes.Mode, len(modeString))
 		for i, mode := range modeString {
@@ -220,6 +226,9 @@ func (reg *ChannelRegistry) LoadChannel(nameCasefolded string) (info RegisteredC
 		accountToUMode := make(map[string]modes.Mode)
 		_ = json.Unmarshal([]byte(accountToUModeString), &accountToUMode)
 
+		var settings ChannelSettings
+		_ = json.Unmarshal([]byte(settingsString), &settings)
+
 		info = RegisteredChannel{
 			Name:           name,
 			RegisteredAt:   time.Unix(regTimeInt, 0).UTC(),
@@ -234,6 +243,7 @@ func (reg *ChannelRegistry) LoadChannel(nameCasefolded string) (info RegisteredC
 			Invites:        invitelist,
 			AccountToUMode: accountToUMode,
 			UserLimit:      int(userLimit),
+			Settings:       settings,
 		}
 		return nil
 	})
@@ -261,7 +271,7 @@ func (reg *ChannelRegistry) deleteChannel(tx *buntdb.Tx, key string, info Regist
 	if err == nil {
 		regTime, _ := tx.Get(fmt.Sprintf(keyChannelRegTime, key))
 		regTimeInt, _ := strconv.ParseInt(regTime, 10, 64)
-		registeredAt := time.Unix(regTimeInt, 0)
+		registeredAt := time.Unix(regTimeInt, 0).UTC()
 		founder, _ := tx.Get(fmt.Sprintf(keyChannelFounder, key))
 
 		// to see if we're deleting the right channel, confirm the founder and the registration time
@@ -357,6 +367,11 @@ func (reg *ChannelRegistry) saveChannel(tx *buntdb.Tx, channelInfo RegisteredCha
 		accountToUModeString, _ := json.Marshal(channelInfo.AccountToUMode)
 		tx.Set(fmt.Sprintf(keyChannelAccountToUMode, channelKey), string(accountToUModeString), nil)
 	}
+
+	if includeFlags&IncludeSettings != 0 {
+		settingsString, _ := json.Marshal(channelInfo.Settings)
+		tx.Set(fmt.Sprintf(keyChannelSettings, channelKey), string(settingsString), nil)
+	}
 }
 
 // PurgeChannel records a channel purge.

irc/chanserv.go

@@ -135,6 +135,35 @@ INFO displays info about a registered channel.`,
 			enabled:   chanregEnabled,
 			minParams: 1,
 		},
+		"get": {
+			handler: csGetHandler,
+			help: `Syntax: $bGET #channel <setting>$b
+
+GET queries the current values of the channel settings. For more information
+on the settings and their possible values, see HELP SET.`,
+			helpShort: `$bGET$b queries the current values of a channel's settings`,
+			enabled:   chanregEnabled,
+			minParams: 2,
+		},
+		"set": {
+			handler:   csSetHandler,
+			helpShort: `$bSET$b modifies a channel's settings`,
+			// these are broken out as separate strings so they can be translated separately
+			helpStrings: []string{
+				`Syntax $bSET #channel <setting> <value>$b
+
+SET modifies a channel's settings. The following settings are available:`,
+
+				`$bHISTORY$b
+'history' lets you control how channel history is stored. Your options are:
+1. 'off'        [no history]
+2. 'ephemeral'  [a limited amount of temporary history, not stored on disk]
+3. 'on'         [history stored in a permanent database, if available]
+4. 'default'    [use the server default]`,
+			},
+			enabled:   chanregEnabled,
+			minParams: 3,
+		},
 	}
 )
 
@@ -318,6 +347,22 @@ func checkChanLimit(client *Client, rb *ResponseBuffer) (ok bool) {
 	return
 }
 
+func csPrivsCheck(channel RegisteredChannel, client *Client, rb *ResponseBuffer) (success bool) {
+	founder := channel.Founder
+	if founder == "" {
+		csNotice(rb, client.t("That channel is not registered"))
+		return false
+	}
+	if client.HasRoleCapabs("chanreg") {
+		return true
+	}
+	if founder != client.Account() {
+		csNotice(rb, client.t("Insufficient privileges"))
+		return false
+	}
+	return true
+}
+
 func csUnregisterHandler(server *Server, client *Client, command string, params []string, rb *ResponseBuffer) {
 	channelName := params[0]
 	var verificationCode string
@@ -325,31 +370,18 @@ func csUnregisterHandler(server *Server, client *Client, command string, params
 		verificationCode = params[1]
 	}
 
-	channelKey, err := CasefoldChannel(channelName)
-	if channelKey == "" || err != nil {
-		csNotice(rb, client.t("Channel name is not valid"))
-		return
-	}
-
-	channel := server.channels.Get(channelKey)
+	channel := server.channels.Get(channelName)
 	if channel == nil {
 		csNotice(rb, client.t("No such channel"))
 		return
 	}
 
-	founder := channel.Founder()
-	if founder == "" {
-		csNotice(rb, client.t("That channel is not registered"))
-		return
-	}
-
-	hasPrivs := client.HasRoleCapabs("chanreg") || founder == client.Account()
-	if !hasPrivs {
-		csNotice(rb, client.t("Insufficient privileges"))
-		return
-	}
-
 	info := channel.ExportRegistration(0)
+	channelKey := info.NameCasefolded
+	if !csPrivsCheck(info, client, rb) {
+		return
+	}
+
 	expectedCode := utils.ConfirmationCode(info.Name, info.RegisteredAt)
 	if expectedCode != verificationCode {
 		csNotice(rb, ircfmt.Unescape(client.t("$bWarning: unregistering this channel will remove all stored channel attributes.$b")))
@@ -357,7 +389,7 @@ func csUnregisterHandler(server *Server, client *Client, command string, params
 		return
 	}
 
-	server.channels.SetUnregistered(channelKey, founder)
+	server.channels.SetUnregistered(channelKey, info.Founder)
 	csNotice(rb, fmt.Sprintf(client.t("Channel %s is now unregistered"), channelKey))
 }
 
@@ -367,9 +399,7 @@ func csClearHandler(server *Server, client *Client, command string, params []str
 		csNotice(rb, client.t("Channel does not exist"))
 		return
 	}
-	account := client.Account()
-	if !(client.HasRoleCapabs("chanreg") || (account != "" && account == channel.Founder())) {
-		csNotice(rb, client.t("Insufficient privileges"))
+	if !csPrivsCheck(channel.ExportRegistration(0), client, rb) {
 		return
 	}
 
@@ -563,3 +593,68 @@ func csInfoHandler(server *Server, client *Client, command string, params []stri
 	csNotice(rb, fmt.Sprintf(client.t("Founder: %s"), chinfo.Founder))
 	csNotice(rb, fmt.Sprintf(client.t("Registered at: %s"), chinfo.RegisteredAt.Format(time.RFC1123)))
 }
+
+func displayChannelSetting(settingName string, settings ChannelSettings, client *Client, rb *ResponseBuffer) {
+	config := client.server.Config()
+
+	switch strings.ToLower(settingName) {
+	case "history":
+		effectiveValue := historyEnabled(config.History.Persistent.RegisteredChannels, settings.History)
+		csNotice(rb, fmt.Sprintf(client.t("The stored channel history setting is: %s"), historyStatusToString(settings.History)))
+		csNotice(rb, fmt.Sprintf(client.t("Given current server settings, the channel history setting is: %s"), historyStatusToString(effectiveValue)))
+	default:
+		csNotice(rb, client.t("Invalid params"))
+	}
+}
+
+func csGetHandler(server *Server, client *Client, command string, params []string, rb *ResponseBuffer) {
+	chname, setting := params[0], params[1]
+	channel := server.channels.Get(chname)
+	if channel == nil {
+		csNotice(rb, client.t("No such channel"))
+		return
+	}
+	info := channel.ExportRegistration(IncludeSettings)
+	if !csPrivsCheck(info, client, rb) {
+		return
+	}
+
+	displayChannelSetting(setting, info.Settings, client, rb)
+}
+
+func csSetHandler(server *Server, client *Client, command string, params []string, rb *ResponseBuffer) {
+	chname, setting, value := params[0], params[1], params[2]
+	channel := server.channels.Get(chname)
+	if channel == nil {
+		csNotice(rb, client.t("No such channel"))
+		return
+	}
+	info := channel.ExportRegistration(IncludeSettings)
+	settings := info.Settings
+	if !csPrivsCheck(info, client, rb) {
+		return
+	}
+
+	var err error
+	switch strings.ToLower(setting) {
+	case "history":
+		settings.History, err = historyStatusFromString(value)
+		if err != nil {
+			err = errInvalidParams
+			break
+		}
+		channel.SetSettings(settings)
+		channel.resizeHistory(server.Config())
+	}
+
+	switch err {
+	case nil:
+		csNotice(rb, client.t("Successfully changed the channel settings"))
+		displayChannelSetting(setting, settings, client, rb)
+	case errInvalidParams:
+		csNotice(rb, client.t("Invalid parameters"))
+	default:
+		server.logger.Error("internal", "CS SET error:", err.Error())
+		csNotice(rb, client.t("An error occurred"))
+	}
+}

irc/client.go

@@ -29,7 +29,7 @@ import (
 const (
 	// IdentTimeoutSeconds is how many seconds before our ident (username) check times out.
 	IdentTimeoutSeconds  = 1.5
-	IRCv3TimestampFormat = "2006-01-02T15:04:05.000Z"
+	IRCv3TimestampFormat = utils.IRCv3TimestampFormat
 )
 
 // ResumeDetails is a place to stash data at various stages of
@@ -45,22 +45,22 @@ type ResumeDetails struct {
 type Client struct {
 	account            string
 	accountName        string // display name of the account: uncasefolded, '*' if not logged in
+	accountRegDate     time.Time
 	accountSettings    AccountSettings
 	atime              time.Time
 	away               bool
 	awayMessage        string
 	brbTimer           BrbTimer
-	certfp             string
 	channels           ChannelSet
 	ctime              time.Time
 	destroyed          bool
 	exitedSnomaskSent  bool
-	flags              modes.ModeSet
+	modes              modes.ModeSet
 	hostname           string
 	invitedTo          map[string]bool
 	isSTSOnly          bool
-	isTor              bool
 	languages          []string
+	lastSignoff        time.Time // for always-on clients, the time their last session quit
 	loginThrottle      connection_limits.GenericThrottle
 	nick               string
 	nickCasefolded     string
@@ -76,17 +76,25 @@ type Client struct {
 	realIP             net.IP
 	registered         bool
 	resumeID           string
-	saslInProgress     bool
-	saslMechanism      string
-	saslValue          string
-	sentPassCommand    bool
 	server             *Server
 	skeleton           string
 	sessions           []*Session
 	stateMutex         sync.RWMutex // tier 1
+	alwaysOn           bool
 	username           string
 	vhost              string
 	history            history.Buffer
+	dirtyBits          uint
+	writerSemaphore    utils.Semaphore // tier 1.5
+}
+
+type saslStatus struct {
+	mechanism string
+	value     string
+}
+
+func (s *saslStatus) Clear() {
+	*s = saslStatus{}
 }
 
 // Session is an individual client connection to the server (TCP connection
@@ -102,11 +110,16 @@ type Session struct {
 	realIP      net.IP
 	proxiedIP   net.IP
 	rawHostname string
+	isTor       bool
 
 	idletimer IdleTimer
 	fakelag   Fakelag
 	destroyed uint32
 
+	certfp          string
+	sasl            saslStatus
+	sentPassCommand bool
+
 	batchCounter uint32
 
 	quitMessage string
@@ -120,6 +133,7 @@ type Session struct {
 	resumeID         string
 	resumeDetails    *ResumeDetails
 	zncPlaybackTimes *zncPlaybackTimes
+	lastSignoff      time.Time
 
 	batch MultilineBatch
 }
@@ -147,6 +161,13 @@ func (sd *Session) SetQuitMessage(message string) (set bool) {
 	}
 }
 
+func (s *Session) IP() net.IP {
+	if s.proxiedIP != nil {
+		return s.proxiedIP
+	}
+	return s.realIP
+}
+
 // returns whether the session was actively destroyed (for example, by ping
 // timeout or NS GHOST).
 // avoids a race condition between asynchronous idle-timing-out of sessions,
@@ -164,8 +185,7 @@ func (session *Session) SetDestroyed() {
 // returns whether the client supports a smart history replay cap,
 // and therefore autoreplay-on-join and similar should be suppressed
 func (session *Session) HasHistoryCaps() bool {
-	// TODO the chathistory cap will go here as well
-	return session.capabilities.Has(caps.ZNCPlayback)
+	return session.capabilities.Has(caps.Chathistory) || session.capabilities.Has(caps.ZNCPlayback)
 }
 
 // generates a batch ID. the uniqueness requirements for this are fairly weak:
@@ -231,7 +251,6 @@ func (server *Server) RunClient(conn clientConn, proxyLine string) {
 		channels:  make(ChannelSet),
 		ctime:     now,
 		isSTSOnly: conn.Config.STSOnly,
-		isTor:     conn.Config.Tor,
 		languages: server.Languages().Default(),
 		loginThrottle: connection_limits.GenericThrottle{
 			Duration: config.Accounts.LoginThrottling.Duration,
@@ -253,13 +272,14 @@ func (server *Server) RunClient(conn clientConn, proxyLine string) {
 		ctime:      now,
 		atime:      now,
 		realIP:     realIP,
+		isTor:      conn.Config.Tor,
 	}
 	client.sessions = []*Session{session}
 
 	if conn.Config.TLSConfig != nil {
 		client.SetMode(modes.TLS, true)
 		// error is not useful to us here anyways so we can ignore it
-		client.certfp, _ = socket.CertFP()
+		session.certfp, _ = socket.CertFP()
 	}
 
 	if conn.Config.Tor {
@@ -272,7 +292,7 @@ func (server *Server) RunClient(conn clientConn, proxyLine string) {
 		client.rawHostname = session.rawHostname
 	} else {
 		remoteAddr := conn.Conn.RemoteAddr()
-		if utils.AddrIsLocal(remoteAddr) {
+		if realIP.IsLoopback() || utils.IPInNets(realIP, config.Server.secureNets) {
 			// treat local connections as secure (may be overridden later by WEBIRC)
 			client.SetMode(modes.TLS, true)
 		}
@@ -286,10 +306,66 @@ func (server *Server) RunClient(conn clientConn, proxyLine string) {
 	client.run(session, proxyLine)
 }
 
+func (server *Server) AddAlwaysOnClient(account ClientAccount, chnames []string, lastSignoff time.Time) {
+	now := time.Now().UTC()
+	config := server.Config()
+
+	client := &Client{
+		atime:     now,
+		channels:  make(ChannelSet),
+		ctime:     now,
+		languages: server.Languages().Default(),
+		server:    server,
+
+		// TODO figure out how to set these on reattach?
+		username:    "~user",
+		rawHostname: server.name,
+		realIP:      utils.IPv4LoopbackAddress,
+
+		alwaysOn:    true,
+		lastSignoff: lastSignoff,
+	}
+
+	client.SetMode(modes.TLS, true)
+	client.writerSemaphore.Initialize(1)
+	client.history.Initialize(0, 0)
+	client.brbTimer.Initialize(client)
+
+	server.accounts.Login(client, account)
+
+	client.resizeHistory(config)
+
+	_, err := server.clients.SetNick(client, nil, account.Name)
+	if err != nil {
+		server.logger.Error("internal", "could not establish always-on client", account.Name, err.Error())
+		return
+	} else {
+		server.logger.Debug("accounts", "established always-on client", account.Name)
+	}
+
+	// XXX set this last to avoid confusing SetNick:
+	client.registered = true
+
+	for _, chname := range chnames {
+		// XXX we're using isSajoin=true, to make these joins succeed even without channel key
+		// this is *probably* ok as long as the persisted memberships are accurate
+		server.channels.Join(client, chname, "", true, nil)
+	}
+}
+
+func (client *Client) resizeHistory(config *Config) {
+	_, ephemeral, _ := client.historyStatus(config)
+	if ephemeral {
+		client.history.Resize(config.History.ClientLength, config.History.AutoresizeWindow)
+	} else {
+		client.history.Resize(0, 0)
+	}
+}
+
 // resolve an IP to an IRC-ready hostname, using reverse DNS, forward-confirming if necessary,
 // and sending appropriate notices to the client
 func (client *Client) lookupHostname(session *Session, overwrite bool) {
-	if client.isTor {
+	if session.isTor {
 		return
 	} // else: even if cloaking is enabled, look up the real hostname to show to operators
 
@@ -384,18 +460,18 @@ const (
 	authFailSaslRequired
 )
 
-func (client *Client) isAuthorized(config *Config) AuthOutcome {
+func (client *Client) isAuthorized(config *Config, session *Session) AuthOutcome {
 	saslSent := client.account != ""
 	// PASS requirement
-	if (config.Server.passwordBytes != nil) && !client.sentPassCommand && !(config.Accounts.SkipServerPassword && saslSent) {
+	if (config.Server.passwordBytes != nil) && !session.sentPassCommand && !(config.Accounts.SkipServerPassword && saslSent) {
 		return authFailPass
 	}
 	// Tor connections may be required to authenticate with SASL
-	if client.isTor && config.Server.TorListeners.RequireSasl && !saslSent {
+	if session.isTor && config.Server.TorListeners.RequireSasl && !saslSent {
 		return authFailTorSaslRequired
 	}
 	// finally, enforce require-sasl
-	if config.Accounts.RequireSasl.Enabled && !saslSent && !utils.IPInNets(client.IP(), config.Accounts.RequireSasl.exemptedNets) {
+	if config.Accounts.RequireSasl.Enabled && !saslSent && !utils.IPInNets(session.IP(), config.Accounts.RequireSasl.exemptedNets) {
 		return authFailSaslRequired
 	}
 	return authSuccess
@@ -572,9 +648,13 @@ func (client *Client) run(session *Session, proxyLine string) {
 
 func (client *Client) playReattachMessages(session *Session) {
 	client.server.playRegistrationBurst(session)
+	hasHistoryCaps := session.HasHistoryCaps()
 	for _, channel := range session.client.Channels() {
 		channel.playJoinForSession(session)
-		// clients should receive autoreplay-on-join lines, if applicable;
+		// clients should receive autoreplay-on-join lines, if applicable:
+		if hasHistoryCaps {
+			continue
+		}
 		// if they negotiated znc.in/playback or chathistory, they will receive nothing,
 		// because those caps disable autoreplay-on-join and they haven't sent the relevant
 		// *playback PRIVMSG or CHATHISTORY command yet
@@ -582,6 +662,12 @@ func (client *Client) playReattachMessages(session *Session) {
 		channel.autoReplayHistory(client, rb, "")
 		rb.Send(true)
 	}
+	if !session.lastSignoff.IsZero() && !hasHistoryCaps {
+		rb := NewResponseBuffer(session)
+		zncPlayPrivmsgs(client, rb, session.lastSignoff, time.Time{})
+		rb.Send(true)
+	}
+	session.lastSignoff = time.Time{}
 }
 
 //
@@ -634,11 +720,6 @@ func (session *Session) tryResume() (success bool) {
 		return
 	}
 
-	if oldClient.isTor != client.isTor {
-		session.Send(nil, server.name, "FAIL", "RESUME", "INSECURE_SESSION", client.t("Cannot resume connection from Tor to non-Tor or vice versa"))
-		return
-	}
-
 	err := server.clients.Resume(oldClient, session)
 	if err != nil {
 		session.Send(nil, server.name, "FAIL", "RESUME", "CANNOT_RESUME", client.t("Cannot resume connection"))
@@ -657,37 +738,45 @@ func (session *Session) tryResume() (success bool) {
 func (session *Session) playResume() {
 	client := session.client
 	server := client.server
+	config := server.Config()
 
 	friends := make(ClientSet)
-	oldestLostMessage := time.Now().UTC()
+	var oldestLostMessage time.Time
 
 	// work out how much time, if any, is not covered by history buffers
+	// assume that a persistent buffer covers the whole resume period
 	for _, channel := range client.Channels() {
 		for _, member := range channel.Members() {
 			friends.Add(member)
+		}
+		_, ephemeral, _ := channel.historyStatus(config)
+		if ephemeral {
 			lastDiscarded := channel.history.LastDiscarded()
-			if lastDiscarded.Before(oldestLostMessage) {
+			if oldestLostMessage.Before(lastDiscarded) {
 				oldestLostMessage = lastDiscarded
 			}
 		}
 	}
-	privmsgMatcher := func(item history.Item) bool {
-		return item.Type == history.Privmsg || item.Type == history.Notice || item.Type == history.Tagmsg
+	_, cEphemeral, _ := client.historyStatus(config)
+	if cEphemeral {
+		lastDiscarded := client.history.LastDiscarded()
+		if oldestLostMessage.Before(lastDiscarded) {
+			oldestLostMessage = lastDiscarded
+		}
 	}
-	privmsgHistory := client.history.Match(privmsgMatcher, false, 0)
-	lastDiscarded := client.history.LastDiscarded()
-	if lastDiscarded.Before(oldestLostMessage) {
-		oldestLostMessage = lastDiscarded
-	}
-	for _, item := range privmsgHistory {
-		sender := server.clients.Get(stripMaskFromNick(item.Nick))
-		if sender != nil {
-			friends.Add(sender)
+	_, privmsgSeq, _ := server.GetHistorySequence(nil, client, "*")
+	if privmsgSeq != nil {
+		privmsgs, _, _ := privmsgSeq.Between(history.Selector{}, history.Selector{}, config.History.ClientLength)
+		for _, item := range privmsgs {
+			sender := server.clients.Get(stripMaskFromNick(item.Nick))
+			if sender != nil {
+				friends.Add(sender)
+			}
 		}
 	}
 
 	timestamp := session.resumeDetails.Timestamp
-	gap := lastDiscarded.Sub(timestamp)
+	gap := oldestLostMessage.Sub(timestamp)
 	session.resumeDetails.HistoryIncomplete = gap > 0 || timestamp.IsZero()
 	gapSeconds := int(gap.Seconds()) + 1 // round up to avoid confusion
 
@@ -723,10 +812,12 @@ func (session *Session) playResume() {
 		}
 	}
 
-	if session.resumeDetails.HistoryIncomplete && !timestamp.IsZero() {
-		session.Send(nil, client.server.name, "WARN", "RESUME", "HISTORY_LOST", fmt.Sprintf(client.t("Resume may have lost up to %d seconds of history"), gapSeconds))
-	} else {
-		session.Send(nil, client.server.name, "WARN", "RESUME", "HISTORY_LOST", client.t("Resume may have lost some message history"))
+	if session.resumeDetails.HistoryIncomplete {
+		if !timestamp.IsZero() {
+			session.Send(nil, client.server.name, "WARN", "RESUME", "HISTORY_LOST", fmt.Sprintf(client.t("Resume may have lost up to %d seconds of history"), gapSeconds))
+		} else {
+			session.Send(nil, client.server.name, "WARN", "RESUME", "HISTORY_LOST", client.t("Resume may have lost some message history"))
+		}
 	}
 
 	session.Send(nil, client.server.name, "RESUME", "SUCCESS", details.nick)
@@ -738,24 +829,27 @@ func (session *Session) playResume() {
 	}
 
 	// replay direct PRIVSMG history
-	if !timestamp.IsZero() {
-		now := time.Now().UTC()
-		items, complete := client.history.Between(timestamp, now, false, 0)
-		rb := NewResponseBuffer(client.Sessions()[0])
-		client.replayPrivmsgHistory(rb, items, complete)
-		rb.Send(true)
+	if !timestamp.IsZero() && privmsgSeq != nil {
+		after := history.Selector{Time: timestamp}
+		items, complete, _ := privmsgSeq.Between(after, history.Selector{}, config.History.ZNCMax)
+		if len(items) != 0 {
+			rb := NewResponseBuffer(session)
+			client.replayPrivmsgHistory(rb, items, "", complete)
+			rb.Send(true)
+		}
 	}
 
 	session.resumeDetails = nil
 }
 
-func (client *Client) replayPrivmsgHistory(rb *ResponseBuffer, items []history.Item, complete bool) {
+func (client *Client) replayPrivmsgHistory(rb *ResponseBuffer, items []history.Item, target string, complete bool) {
 	var batchID string
 	details := client.Details()
 	nick := details.nick
-	if 0 < len(items) {
-		batchID = rb.StartNestedHistoryBatch(nick)
+	if target == "" {
+		target = nick
 	}
+	batchID = rb.StartNestedHistoryBatch(target)
 
 	allowTags := rb.session.capabilities.Has(caps.MessageTags)
 	for _, item := range items {
@@ -778,12 +872,16 @@ func (client *Client) replayPrivmsgHistory(rb *ResponseBuffer, items []history.I
 		if allowTags {
 			tags = item.Tags
 		}
-		if item.Params[0] == "" {
-			// this message was sent *to* the client from another nick
+		// XXX: Params[0] is the message target. if the source of this message is an in-memory
+		// buffer, then it's "" for an incoming message and the recipient's nick for an outgoing
+		// message. if the source of the message is mysql, then mysql only sees one copy of the
+		// message, and it's the version with the recipient's nick filled in. so this is an
+		// incoming message if Params[0] (the recipient's nick) equals the client's nick:
+		if item.Params[0] == "" || item.Params[0] == nick {
 			rb.AddSplitMessageFromClient(item.Nick, item.AccountName, tags, command, nick, item.Message)
 		} else {
 			// this message was sent *from* the client to another nick; the target is item.Params[0]
-			// substitute the client's current nickmask in case they changed nick
+			// substitute client's current nickmask in case client changed nick
 			rb.AddSplitMessageFromClient(details.nickMask, item.AccountName, tags, command, item.Params[0], item.Message)
 		}
 	}
@@ -875,7 +973,7 @@ func (client *Client) HasRoleCapabs(capabs ...string) bool {
 
 // ModeString returns the mode string for this client.
 func (client *Client) ModeString() (str string) {
-	return "+" + client.flags.String()
+	return "+" + client.modes.String()
 }
 
 // Friends refers to clients that share a channel with this client.
@@ -1053,6 +1151,12 @@ func (client *Client) Quit(message string, session *Session) {
 // has no more sessions.
 func (client *Client) destroy(session *Session) {
 	var sessionsToDestroy []*Session
+	var lastSignoff time.Time
+	if session != nil {
+		lastSignoff = session.idletimer.LastTouch()
+	} else {
+		lastSignoff = time.Now().UTC()
+	}
 
 	client.stateMutex.Lock()
 	details := client.detailsNoMutex()
@@ -1060,6 +1164,8 @@ func (client *Client) destroy(session *Session) {
 	brbAt := client.brbTimer.brbAt
 	wasReattach := session != nil && session.client != client
 	sessionRemoved := false
+	registered := client.registered
+	alwaysOn := client.alwaysOn
 	var remainingSessions int
 	if session == nil {
 		sessionsToDestroy = client.sessions
@@ -1074,15 +1180,25 @@ func (client *Client) destroy(session *Session) {
 
 	// should we destroy the whole client this time?
 	// BRB is not respected if this is a destroy of the whole client (i.e., session == nil)
-	brbEligible := session != nil && (brbState == BrbEnabled || brbState == BrbSticky)
+	brbEligible := session != nil && (brbState == BrbEnabled || alwaysOn)
 	shouldDestroy := !client.destroyed && remainingSessions == 0 && !brbEligible
 	if shouldDestroy {
 		// if it's our job to destroy it, don't let anyone else try
 		client.destroyed = true
 	}
+	if alwaysOn && remainingSessions == 0 {
+		client.lastSignoff = lastSignoff
+		client.dirtyBits |= IncludeLastSignoff
+	} else {
+		lastSignoff = time.Time{}
+	}
 	exitedSnomaskSent := client.exitedSnomaskSent
 	client.stateMutex.Unlock()
 
+	if !lastSignoff.IsZero() {
+		client.wakeWriter()
+	}
+
 	// destroy all applicable sessions:
 	var quitMessage string
 	for _, session := range sessionsToDestroy {
@@ -1099,7 +1215,7 @@ func (client *Client) destroy(session *Session) {
 
 		// remove from connection limits
 		var source string
-		if client.isTor {
+		if session.isTor {
 			client.server.torLimiter.RemoveClient()
 			source = "tor"
 		} else {
@@ -1113,11 +1229,33 @@ func (client *Client) destroy(session *Session) {
 		client.server.logger.Info("localconnect-ip", fmt.Sprintf("disconnecting session of %s from %s", details.nick, source))
 	}
 
+	// decrement stats if we have no more sessions, even if the client will not be destroyed
+	if shouldDestroy || remainingSessions == 0 {
+		invisible := client.HasMode(modes.Invisible)
+		operator := client.HasMode(modes.LocalOperator) || client.HasMode(modes.Operator)
+		client.server.stats.Remove(registered, invisible, operator)
+	}
+
 	// do not destroy the client if it has either remaining sessions, or is BRB'ed
 	if !shouldDestroy {
 		return
 	}
 
+	splitQuitMessage := utils.MakeMessage(quitMessage)
+	quitItem := history.Item{
+		Type:        history.Quit,
+		Nick:        details.nickMask,
+		AccountName: details.accountName,
+		Message:     splitQuitMessage,
+	}
+	var channels []*Channel
+	// use a defer here to avoid writing to mysql while holding the destroy semaphore:
+	defer func() {
+		for _, channel := range channels {
+			channel.AddHistoryItem(quitItem)
+		}
+	}()
+
 	// see #235: deduplicating the list of PART recipients uses (comparatively speaking)
 	// a lot of RAM, so limit concurrency to avoid thrashing
 	client.server.semaphores.ClientDestroy.Acquire()
@@ -1127,7 +1265,6 @@ func (client *Client) destroy(session *Session) {
 		client.server.logger.Debug("quit", fmt.Sprintf("%s is no longer on the server", details.nick))
 	}
 
-	registered := client.Registered()
 	if registered {
 		client.server.whoWas.Append(client.WhoWas())
 	}
@@ -1141,18 +1278,12 @@ func (client *Client) destroy(session *Session) {
 	// clean up monitor state
 	client.server.monitorManager.RemoveAll(client)
 
-	splitQuitMessage := utils.MakeMessage(quitMessage)
 	// clean up channels
 	// (note that if this is a reattach, client has no channels and therefore no friends)
 	friends := make(ClientSet)
-	for _, channel := range client.Channels() {
+	channels = client.Channels()
+	for _, channel := range channels {
 		channel.Quit(client)
-		channel.history.Add(history.Item{
-			Type:        history.Quit,
-			Nick:        details.nickMask,
-			AccountName: details.accountName,
-			Message:     splitQuitMessage,
-		})
 		for _, member := range channel.Members() {
 			friends.Add(member)
 		}
@@ -1168,9 +1299,6 @@ func (client *Client) destroy(session *Session) {
 
 	client.server.accounts.Logout(client)
 
-	client.server.stats.Remove(registered, client.HasMode(modes.Invisible),
-		client.HasMode(modes.Operator) || client.HasMode(modes.LocalOperator))
-
 	// this happens under failure to return from BRB
 	if quitMessage == "" {
 		if brbState == BrbDead && !brbAt.IsZero() {
@@ -1196,11 +1324,10 @@ func (client *Client) destroy(session *Session) {
 // SendSplitMsgFromClient sends an IRC PRIVMSG/NOTICE coming from a specific client.
 // Adds account-tag to the line as well.
 func (session *Session) sendSplitMsgFromClientInternal(blocking bool, nickmask, accountName string, tags map[string]string, command, target string, message utils.SplitMessage) {
-	// TODO no maxline support
 	if message.Is512() {
 		session.sendFromClientInternal(blocking, message.Time, message.Msgid, nickmask, accountName, tags, command, target, message.Message)
 	} else {
-		if message.IsMultiline() && session.capabilities.Has(caps.Multiline) {
+		if session.capabilities.Has(caps.Multiline) {
 			for _, msg := range session.composeMultilineBatch(nickmask, accountName, tags, command, target, message) {
 				session.SendRawMessage(msg, blocking)
 			}
@@ -1366,13 +1493,23 @@ func (session *Session) Notice(text string) {
 func (client *Client) addChannel(channel *Channel) {
 	client.stateMutex.Lock()
 	client.channels[channel] = true
+	alwaysOn := client.alwaysOn
 	client.stateMutex.Unlock()
+
+	if alwaysOn {
+		client.markDirty(IncludeChannels)
+	}
 }
 
 func (client *Client) removeChannel(channel *Channel) {
 	client.stateMutex.Lock()
 	delete(client.channels, channel)
+	alwaysOn := client.alwaysOn
 	client.stateMutex.Unlock()
+
+	if alwaysOn {
+		client.markDirty(IncludeChannels)
+	}
 }
 
 // Records that the client has been invited to join an invite-only channel
@@ -1401,11 +1538,11 @@ func (client *Client) CheckInvited(casefoldedChannel string) (invited bool) {
 // Implements auto-oper by certfp (scans for an auto-eligible operator block that matches
 // the client's cert, then applies it).
 func (client *Client) attemptAutoOper(session *Session) {
-	if client.certfp == "" || client.HasMode(modes.Operator) {
+	if session.certfp == "" || client.HasMode(modes.Operator) {
 		return
 	}
 	for _, oper := range client.server.Config().operators {
-		if oper.Auto && oper.Pass == nil && oper.Fingerprint != "" && oper.Fingerprint == client.certfp {
+		if oper.Auto && oper.Pass == nil && oper.Fingerprint != "" && oper.Fingerprint == session.certfp {
 			rb := NewResponseBuffer(session)
 			applyOper(client, oper, rb)
 			rb.Send(true)
@@ -1413,3 +1550,96 @@ func (client *Client) attemptAutoOper(session *Session) {
 		}
 	}
 }
+
+func (client *Client) historyStatus(config *Config) (persistent, ephemeral bool, target string) {
+	if !config.History.Enabled {
+		return
+	} else if !config.History.Persistent.Enabled {
+		ephemeral = true
+		return
+	}
+
+	client.stateMutex.RLock()
+	alwaysOn := client.alwaysOn
+	historyStatus := client.accountSettings.DMHistory
+	target = client.nickCasefolded
+	client.stateMutex.RUnlock()
+
+	if !alwaysOn {
+		ephemeral = true
+		return
+	}
+
+	historyStatus = historyEnabled(config.History.Persistent.DirectMessages, historyStatus)
+	ephemeral = (historyStatus == HistoryEphemeral)
+	persistent = (historyStatus == HistoryPersistent)
+	return
+}
+
+// these are bit flags indicating what part of the client status is "dirty"
+// and needs to be read from memory and written to the db
+// TODO add a dirty flag for lastSignoff
+const (
+	IncludeChannels uint = 1 << iota
+	IncludeLastSignoff
+)
+
+func (client *Client) markDirty(dirtyBits uint) {
+	client.stateMutex.Lock()
+	alwaysOn := client.alwaysOn
+	client.dirtyBits = client.dirtyBits | dirtyBits
+	client.stateMutex.Unlock()
+
+	if alwaysOn {
+		client.wakeWriter()
+	}
+}
+
+func (client *Client) wakeWriter() {
+	if client.writerSemaphore.TryAcquire() {
+		go client.writeLoop()
+	}
+}
+
+func (client *Client) writeLoop() {
+	for {
+		client.performWrite()
+		client.writerSemaphore.Release()
+
+		client.stateMutex.RLock()
+		isDirty := client.dirtyBits != 0
+		client.stateMutex.RUnlock()
+
+		if !isDirty || !client.writerSemaphore.TryAcquire() {
+			return
+		}
+	}
+}
+
+func (client *Client) performWrite() {
+	client.stateMutex.Lock()
+	dirtyBits := client.dirtyBits
+	client.dirtyBits = 0
+	account := client.account
+	client.stateMutex.Unlock()
+
+	if account == "" {
+		client.server.logger.Error("internal", "attempting to persist logged-out client", client.Nick())
+		return
+	}
+
+	if (dirtyBits & IncludeChannels) != 0 {
+		channels := client.Channels()
+		channelNames := make([]string, len(channels))
+		for i, channel := range channels {
+			channelNames[i] = channel.Name()
+		}
+		client.server.accounts.saveChannels(account, channelNames)
+	}
+	if (dirtyBits & IncludeLastSignoff) != 0 {
+		client.stateMutex.RLock()
+		lastSignoff := client.lastSignoff
+		client.stateMutex.RUnlock()
+		client.server.accounts.saveLastSignoff(account, lastSignoff)
+	}
+}

irc/client_lookup_set.go

@@ -105,7 +105,8 @@ func (clients *ClientManager) Resume(oldClient *Client, session *Session) (err e
 		return errNickMissing
 	}
 
-	if !oldClient.AddSession(session) {
+	success, _, _ := oldClient.AddSession(session)
+	if !success {
 		return errNickMissing
 	}
 
@@ -113,35 +114,51 @@ func (clients *ClientManager) Resume(oldClient *Client, session *Session) (err e
 }
 
 // SetNick sets a client's nickname, validating it against nicknames in use
-func (clients *ClientManager) SetNick(client *Client, session *Session, newNick string) error {
-	if len(newNick) > client.server.Config().Limits.NickLen {
-		return errNicknameInvalid
-	}
+func (clients *ClientManager) SetNick(client *Client, session *Session, newNick string) (setNick string, err error) {
+	config := client.server.Config()
 	newcfnick, err := CasefoldName(newNick)
 	if err != nil {
-		return errNicknameInvalid
+		return "", errNicknameInvalid
+	}
+	if len(newNick) > config.Limits.NickLen || len(newcfnick) > config.Limits.NickLen {
+		return "", errNicknameInvalid
 	}
 	newSkeleton, err := Skeleton(newNick)
 	if err != nil {
-		return errNicknameInvalid
+		return "", errNicknameInvalid
 	}
 
 	if restrictedCasefoldedNicks[newcfnick] || restrictedSkeletons[newSkeleton] {
-		return errNicknameInvalid
+		return "", errNicknameInvalid
 	}
 
 	reservedAccount, method := client.server.accounts.EnforcementStatus(newcfnick, newSkeleton)
-	account := client.Account()
-	config := client.server.Config()
+	client.stateMutex.RLock()
+	account := client.account
+	accountName := client.accountName
+	settings := client.accountSettings
+	registered := client.registered
+	realname := client.realname
+	client.stateMutex.RUnlock()
+
+	// recompute this (client.alwaysOn is not set for unregistered clients):
+	alwaysOn := account != "" && persistenceEnabled(config.Accounts.Multiclient.AlwaysOn, settings.AlwaysOn)
+
+	if alwaysOn && registered {
+		return "", errCantChangeNick
+	}
+
 	var bouncerAllowed bool
-	if config.Accounts.Bouncer.Enabled {
-		if session != nil && session.capabilities.Has(caps.Bouncer) {
+	if config.Accounts.Multiclient.Enabled {
+		if alwaysOn {
+			// ignore the pre-reg nick, force a reattach
+			newNick = accountName
+			newcfnick = account
 			bouncerAllowed = true
 		} else {
-			settings := client.AccountSettings()
-			if config.Accounts.Bouncer.AllowedByDefault && settings.AllowBouncer != BouncerDisallowedByUser {
+			if config.Accounts.Multiclient.AllowedByDefault && settings.AllowBouncer != MulticlientDisallowedByUser {
 				bouncerAllowed = true
-			} else if settings.AllowBouncer == BouncerAllowedByUser {
+			} else if settings.AllowBouncer == MulticlientAllowedByUser {
 				bouncerAllowed = true
 			}
 		}
@@ -154,28 +171,41 @@ func (clients *ClientManager) SetNick(client *Client, session *Session, newNick
 	// the client may just be changing case
 	if currentClient != nil && currentClient != client && session != nil {
 		// these conditions forbid reattaching to an existing session:
-		if client.Registered() || !bouncerAllowed || account == "" || account != currentClient.Account() || client.HasMode(modes.TLS) != currentClient.HasMode(modes.TLS) {
-			return errNicknameInUse
+		if registered || !bouncerAllowed || account == "" || account != currentClient.Account() || client.HasMode(modes.TLS) != currentClient.HasMode(modes.TLS) {
+			return "", errNicknameInUse
 		}
-		if !currentClient.AddSession(session) {
-			return errNicknameInUse
+		reattachSuccessful, numSessions, lastSignoff := currentClient.AddSession(session)
+		if !reattachSuccessful {
+			return "", errNicknameInUse
 		}
+		if numSessions == 1 {
+			invisible := client.HasMode(modes.Invisible)
+			operator := client.HasMode(modes.Operator) || client.HasMode(modes.LocalOperator)
+			client.server.stats.AddRegistered(invisible, operator)
+		}
+		session.lastSignoff = lastSignoff
+		// XXX SetNames only changes names if they are unset, so the realname change only
+		// takes effect on first attach to an always-on client (good), but the user/ident
+		// change is always a no-op (bad). we could make user/ident act the same way as
+		// realname, but then we'd have to send CHGHOST and i don't want to deal with that
+		// for performance reasons
+		currentClient.SetNames("user", realname, true)
 		// successful reattach!
-		return nil
+		return newNick, nil
 	}
 	// analogous checks for skeletons
 	skeletonHolder := clients.bySkeleton[newSkeleton]
 	if skeletonHolder != nil && skeletonHolder != client {
-		return errNicknameInUse
+		return "", errNicknameInUse
 	}
 	if method == NickEnforcementStrict && reservedAccount != "" && reservedAccount != account {
-		return errNicknameReserved
+		return "", errNicknameReserved
 	}
 	clients.removeInternal(client)
 	clients.byNick[newcfnick] = client
 	clients.bySkeleton[newSkeleton] = client
 	client.updateNick(newNick, newcfnick, newSkeleton)
-	return nil
+	return newNick, nil
 }
 
 func (clients *ClientManager) AllClients() (result []*Client) {

irc/commands.go

@@ -54,6 +54,12 @@ func (cmd *Command) Run(server *Server, client *Client, session *Session, msg ir
 		return cmd.handler(server, client, msg, rb)
 	}()
 
+	// most servers do this only for PING/PONG, but we'll do it for any command:
+	if client.registered {
+		// touch even if `exiting`, so we record the time of a QUIT accurately
+		session.idletimer.Touch()
+	}
+
 	if exiting {
 		return
 	}
@@ -63,11 +69,6 @@ func (cmd *Command) Run(server *Server, client *Client, session *Session, msg ir
 		exiting = server.tryRegister(client, session)
 	}
 
-	// most servers do this only for PING/PONG, but we'll do it for any command:
-	if client.registered {
-		session.idletimer.Touch()
-	}
-
 	if client.registered && !cmd.leaveClientIdle {
 		client.Active(session)
 	}
@@ -109,7 +110,7 @@ func init() {
 		},
 		"CHATHISTORY": {
 			handler:   chathistoryHandler,
-			minParams: 3,
+			minParams: 4,
 		},
 		"DEBUG": {
 			handler:   debugHandler,

irc/config.go

@@ -28,6 +28,7 @@ import (
 	"github.com/oragono/oragono/irc/ldap"
 	"github.com/oragono/oragono/irc/logger"
 	"github.com/oragono/oragono/irc/modes"
+	"github.com/oragono/oragono/irc/mysql"
 	"github.com/oragono/oragono/irc/passwd"
 	"github.com/oragono/oragono/irc/utils"
 	"gopkg.in/yaml.v2"
@@ -61,6 +62,157 @@ type listenerConfig struct {
 	ProxyBeforeTLS bool
 }
 
+type PersistentStatus uint
+
+const (
+	PersistentUnspecified PersistentStatus = iota
+	PersistentDisabled
+	PersistentOptIn
+	PersistentOptOut
+	PersistentMandatory
+)
+
+func persistentStatusToString(status PersistentStatus) string {
+	switch status {
+	case PersistentUnspecified:
+		return "default"
+	case PersistentDisabled:
+		return "disabled"
+	case PersistentOptIn:
+		return "opt-in"
+	case PersistentOptOut:
+		return "opt-out"
+	case PersistentMandatory:
+		return "mandatory"
+	default:
+		return ""
+	}
+}
+
+func persistentStatusFromString(status string) (PersistentStatus, error) {
+	switch strings.ToLower(status) {
+	case "default":
+		return PersistentUnspecified, nil
+	case "":
+		return PersistentDisabled, nil
+	case "opt-in":
+		return PersistentOptIn, nil
+	case "opt-out":
+		return PersistentOptOut, nil
+	case "mandatory":
+		return PersistentMandatory, nil
+	default:
+		b, err := utils.StringToBool(status)
+		if b {
+			return PersistentMandatory, err
+		} else {
+			return PersistentDisabled, err
+		}
+	}
+}
+
+func (ps *PersistentStatus) UnmarshalYAML(unmarshal func(interface{}) error) error {
+	var orig string
+	var err error
+	if err = unmarshal(&orig); err != nil {
+		return err
+	}
+	result, err := persistentStatusFromString(orig)
+	if err == nil {
+		if result == PersistentUnspecified {
+			result = PersistentDisabled
+		}
+		*ps = result
+	}
+	return err
+}
+
+func persistenceEnabled(serverSetting, clientSetting PersistentStatus) (enabled bool) {
+	if serverSetting == PersistentDisabled {
+		return false
+	} else if serverSetting == PersistentMandatory {
+		return true
+	} else if clientSetting == PersistentDisabled {
+		return false
+	} else if clientSetting == PersistentMandatory {
+		return true
+	} else if serverSetting == PersistentOptOut {
+		return true
+	} else {
+		return false
+	}
+}
+
+type HistoryStatus uint
+
+const (
+	HistoryDefault HistoryStatus = iota
+	HistoryDisabled
+	HistoryEphemeral
+	HistoryPersistent
+)
+
+func historyStatusFromString(str string) (status HistoryStatus, err error) {
+	switch strings.ToLower(str) {
+	case "default":
+		return HistoryDefault, nil
+	case "ephemeral":
+		return HistoryEphemeral, nil
+	case "persistent":
+		return HistoryPersistent, nil
+	default:
+		b, err := utils.StringToBool(str)
+		if b {
+			return HistoryPersistent, err
+		} else {
+			return HistoryDisabled, err
+		}
+	}
+}
+
+func historyStatusToString(status HistoryStatus) string {
+	switch status {
+	case HistoryDefault:
+		return "default"
+	case HistoryDisabled:
+		return "disabled"
+	case HistoryEphemeral:
+		return "ephemeral"
+	case HistoryPersistent:
+		return "persistent"
+	default:
+		return ""
+	}
+}
+
+func historyEnabled(serverSetting PersistentStatus, localSetting HistoryStatus) (result HistoryStatus) {
+	if serverSetting == PersistentDisabled {
+		return HistoryDisabled
+	} else if serverSetting == PersistentMandatory {
+		return HistoryPersistent
+	} else if serverSetting == PersistentOptOut {
+		if localSetting == HistoryDefault {
+			return HistoryPersistent
+		} else {
+			return localSetting
+		}
+	} else if serverSetting == PersistentOptIn {
+		if localSetting >= HistoryEphemeral {
+			return localSetting
+		} else {
+			return HistoryDisabled
+		}
+	} else {
+		return HistoryDisabled
+	}
+}
+
+type MulticlientConfig struct {
+	Enabled          bool
+	AllowedByDefault bool             `yaml:"allowed-by-default"`
+	AlwaysOn         PersistentStatus `yaml:"always-on"`
+}
+
 type AccountConfig struct {
 	Registration          AccountRegistrationConfig
 	AuthenticationEnabled bool `yaml:"authentication-enabled"`
@@ -77,19 +229,17 @@ type AccountConfig struct {
 	} `yaml:"login-throttling"`
 	SkipServerPassword bool                  `yaml:"skip-server-password"`
 	NickReservation    NickReservationConfig `yaml:"nick-reservation"`
-	Bouncer            struct {
-		Enabled          bool
-		AllowedByDefault bool `yaml:"allowed-by-default"`
-	}
-	VHosts VHostConfig
+	Multiclient        MulticlientConfig
+	Bouncer            *MulticlientConfig // # handle old name for 'multiclient'
+	VHosts             VHostConfig
 }
 
 // AccountRegistrationConfig controls account registration.
 type AccountRegistrationConfig struct {
 	Enabled                bool
-	EnabledCallbacks       []string      `yaml:"enabled-callbacks"`
-	EnabledCredentialTypes []string      `yaml:"-"`
-	VerifyTimeout          time.Duration `yaml:"verify-timeout"`
+	EnabledCallbacks       []string         `yaml:"enabled-callbacks"`
+	EnabledCredentialTypes []string         `yaml:"-"`
+	VerifyTimeout          custime.Duration `yaml:"verify-timeout"`
 	Callbacks              struct {
 		Mailto struct {
 			Server string
@@ -117,7 +267,7 @@ type VHostConfig struct {
 	UserRequests   struct {
 		Enabled  bool
 		Channel  string
-		Cooldown time.Duration
+		Cooldown custime.Duration
 	} `yaml:"user-requests"`
 	OfferList []string `yaml:"offer-list"`
 }
@@ -260,18 +410,17 @@ type Limits struct {
 
 // STSConfig controls the STS configuration/
 type STSConfig struct {
-	Enabled        bool
-	Duration       time.Duration `yaml:"duration-real"`
-	DurationString string        `yaml:"duration"`
-	Port           int
-	Preload        bool
-	STSOnlyBanner  string `yaml:"sts-only-banner"`
-	bannerLines    []string
+	Enabled       bool
+	Duration      custime.Duration
+	Port          int
+	Preload       bool
+	STSOnlyBanner string `yaml:"sts-only-banner"`
+	bannerLines   []string
 }
 
 // Value returns the STS value to advertise in CAP
 func (sts *STSConfig) Value() string {
-	val := fmt.Sprintf("duration=%d", int(sts.Duration.Seconds()))
+	val := fmt.Sprintf("duration=%d", int(time.Duration(sts.Duration).Seconds()))
 	if sts.Enabled && sts.Port > 0 {
 		val += fmt.Sprintf(",port=%d", sts.Port)
 	}
@@ -337,6 +486,8 @@ type Config struct {
 		isupport      isupport.List
 		IPLimits      connection_limits.LimiterConfig `yaml:"ip-limits"`
 		Cloaks        cloaks.CloakConfig              `yaml:"ip-cloaking"`
+		SecureNetDefs []string                        `yaml:"secure-nets"`
+		secureNets    []net.IPNet
 		supportedCaps *caps.Set
 		capValues     caps.Values
 		Casemapping   Casemapping
@@ -353,6 +504,7 @@ type Config struct {
 	Datastore struct {
 		Path        string
 		AutoUpgrade bool
+		MySQL       mysql.Config
 	}
 
 	Accounts AccountConfig
@@ -392,6 +544,18 @@ type Config struct {
 		AutoresizeWindow time.Duration `yaml:"autoresize-window"`
 		AutoreplayOnJoin int           `yaml:"autoreplay-on-join"`
 		ChathistoryMax   int           `yaml:"chathistory-maxmessages"`
+		ZNCMax           int           `yaml:"znc-maxmessages"`
+		Restrictions     struct {
+			ExpireTime              custime.Duration `yaml:"expire-time"`
+			EnforceRegistrationDate bool             `yaml:"enforce-registration-date"`
+			GracePeriod             custime.Duration `yaml:"grace-period"`
+		}
+		Persistent struct {
+			Enabled              bool
+			UnregisteredChannels bool             `yaml:"unregistered-channels"`
+			RegisteredChannels   PersistentStatus `yaml:"registered-channels"`
+			DirectMessages       PersistentStatus `yaml:"direct-messages"`
+		}
 	}
 
 	Filename string
@@ -626,6 +790,11 @@ func LoadConfig(filename string) (config *Config, err error) {
 	if config.Limits.RegistrationMessages == 0 {
 		config.Limits.RegistrationMessages = 1024
 	}
+	if config.Datastore.MySQL.Enabled {
+		if config.Limits.NickLen > mysql.MaxTargetLength || config.Limits.ChannelLen > mysql.MaxTargetLength {
+			return nil, fmt.Errorf("to use MySQL, nick and channel length limits must be %d or lower", mysql.MaxTargetLength)
+		}
+	}
 
 	config.Server.supportedCaps = caps.NewCompleteSet()
 	config.Server.capValues = make(caps.Values)
@@ -636,10 +805,6 @@ func LoadConfig(filename string) (config *Config, err error) {
 	}
 
 	if config.Server.STS.Enabled {
-		config.Server.STS.Duration, err = custime.ParseDuration(config.Server.STS.DurationString)
-		if err != nil {
-			return nil, fmt.Errorf("Could not parse STS duration: %s", err.Error())
-		}
 		if config.Server.STS.Port < 0 || config.Server.STS.Port > 65535 {
 			return nil, fmt.Errorf("STS port is incorrect, should be 0 if disabled: %d", config.Server.STS.Port)
 		}
@@ -692,8 +857,15 @@ func LoadConfig(filename string) (config *Config, err error) {
 		config.Server.capValues[caps.Multiline] = multilineCapValue
 	}
 
-	if !config.Accounts.Bouncer.Enabled {
-		config.Server.supportedCaps.Disable(caps.Bouncer)
+	// handle legacy name 'bouncer' for 'multiclient' section:
+	if config.Accounts.Bouncer != nil {
+		config.Accounts.Multiclient = *config.Accounts.Bouncer
+	}
+
+	if !config.Accounts.Multiclient.Enabled {
+		config.Accounts.Multiclient.AlwaysOn = PersistentDisabled
+	} else if config.Accounts.Multiclient.AlwaysOn >= PersistentOptOut {
+		config.Accounts.Multiclient.AllowedByDefault = true
 	}
 
 	var newLogConfigs []logger.LoggingConfig
@@ -762,6 +934,11 @@ func LoadConfig(filename string) (config *Config, err error) {
 		return nil, fmt.Errorf("Could not parse proxy-allowed-from nets: %v", err.Error())
 	}
 
+	config.Server.secureNets, err = utils.ParseNetList(config.Server.SecureNetDefs)
+	if err != nil {
+		return nil, fmt.Errorf("Could not parse secure-nets: %v\n", err.Error())
+	}
+
 	rawRegexp := config.Accounts.VHosts.ValidRegexpRaw
 	if rawRegexp != "" {
 		regexp, err := regexp.Compile(rawRegexp)
@@ -858,6 +1035,18 @@ func LoadConfig(filename string) (config *Config, err error) {
 		config.History.ClientLength = 0
 	}
 
+	if !config.History.Enabled || !config.History.Persistent.Enabled {
+		config.History.Persistent.UnregisteredChannels = false
+		config.History.Persistent.RegisteredChannels = PersistentDisabled
+		config.History.Persistent.DirectMessages = PersistentDisabled
+	}
+
+	if config.History.ZNCMax == 0 {
+		config.History.ZNCMax = config.History.ChathistoryMax
+	}
+
+	config.Datastore.MySQL.ExpireTime = time.Duration(config.History.Restrictions.ExpireTime)
+
 	config.Server.Cloaks.Initialize()
 	if config.Server.Cloaks.Enabled {
 		if config.Server.Cloaks.Secret == "" || config.Server.Cloaks.Secret == "siaELnk6Kaeo65K3RCrwJjlWaZ-Bt3WuZ2L8MXLbNb4" {
@@ -942,12 +1131,6 @@ func (config *Config) Diff(oldConfig *Config) (addedCaps, removedCaps *caps.Set)
 		removedCaps.Add(caps.SASL)
 	}
 
-	if !oldConfig.Accounts.Bouncer.Enabled && config.Accounts.Bouncer.Enabled {
-		addedCaps.Add(caps.Bouncer)
-	} else if oldConfig.Accounts.Bouncer.Enabled && !config.Accounts.Bouncer.Enabled {
-		removedCaps.Add(caps.Bouncer)
-	}
-
 	if oldConfig.Limits.Multiline.MaxBytes != 0 && config.Limits.Multiline.MaxBytes == 0 {
 		removedCaps.Add(caps.Multiline)
 	} else if oldConfig.Limits.Multiline.MaxBytes == 0 && config.Limits.Multiline.MaxBytes != 0 {

irc/custime/parseduration.go

@@ -75,8 +75,9 @@ var unitMap = map[string]int64{
 	"m":  int64(time.Minute),
 	"h":  int64(time.Hour),
 	"d":  int64(time.Hour * 24),
+	"w":  int64(time.Hour * 24 * 7),
 	"mo": int64(time.Hour * 24 * 30),
-	"y":  int64(time.Hour * 24 * 265),
+	"y":  int64(time.Hour * 24 * 365),
 }
 
 // ParseDuration parses a duration string.
@@ -181,3 +182,18 @@ func ParseDuration(s string) (time.Duration, error) {
 	}
 	return time.Duration(d), nil
 }
+
+type Duration time.Duration
+
+func (d *Duration) UnmarshalYAML(unmarshal func(interface{}) error) error {
+	var orig string
+	var err error
+	if err = unmarshal(&orig); err != nil {
+		return err
+	}
+	result, err := ParseDuration(orig)
+	if err == nil {
+		*d = Duration(result)
+	}
+	return err
+}

irc/database.go

@@ -36,22 +36,6 @@ type SchemaChange struct {
 // maps an initial version to a schema change capable of upgrading it
 var schemaChanges map[string]SchemaChange
 
-type incompatibleSchemaError struct {
-	currentVersion  string
-	requiredVersion string
-}
-
-func IncompatibleSchemaError(currentVersion string) (result *incompatibleSchemaError) {
-	return &incompatibleSchemaError{
-		currentVersion:  currentVersion,
-		requiredVersion: latestDbSchema,
-	}
-}
-
-func (err *incompatibleSchemaError) Error() string {
-	return fmt.Sprintf("Database requires update. Expected schema v%s, got v%s", err.requiredVersion, err.currentVersion)
-}
-
 // InitDB creates the database, implementing the `oragono initdb` command.
 func InitDB(path string) {
 	_, err := os.Stat(path)
@@ -129,7 +113,7 @@ func openDatabaseInternal(config *Config, allowAutoupgrade bool) (db *buntdb.DB,
 		// successful autoupgrade, let's try this again:
 		return openDatabaseInternal(config, false)
 	} else {
-		err = IncompatibleSchemaError(version)
+		err = &utils.IncompatibleSchemaError{CurrentVersion: version, RequiredVersion: latestDbSchema}
 		return
 	}
 }
@@ -179,7 +163,7 @@ func UpgradeDB(config *Config) (err error) {
 					break
 				}
 				// unable to upgrade to the desired version, roll back
-				return IncompatibleSchemaError(version)
+				return &utils.IncompatibleSchemaError{CurrentVersion: version, RequiredVersion: latestDbSchema}
 			}
 			log.Println("attempting to update schema from version " + version)
 			err := change.Changer(config, tx)
@@ -509,14 +493,14 @@ func schemaChangeV6ToV7(config *Config, tx *buntdb.Tx) error {
 type accountSettingsLegacyV7 struct {
 	AutoreplayLines *int
 	NickEnforcement NickEnforcementMethod
-	AllowBouncer    BouncerAllowedSetting
+	AllowBouncer    MulticlientAllowedSetting
 	AutoreplayJoins bool
 }
 
 type accountSettingsLegacyV8 struct {
 	AutoreplayLines *int
 	NickEnforcement NickEnforcementMethod
-	AllowBouncer    BouncerAllowedSetting
+	AllowBouncer    MulticlientAllowedSetting
 	ReplayJoins     ReplayJoinsSetting
 }
 

irc/errors.go

@@ -33,6 +33,7 @@ var (
 	errChannelNotOwnedByAccount       = errors.New("Channel not owned by the specified account")
 	errChannelTransferNotOffered      = errors.New(`You weren't offered ownership of that channel`)
 	errChannelAlreadyRegistered       = errors.New("Channel is already registered")
+	errChannelNotRegistered           = errors.New("Channel is not registered")
 	errChannelNameInUse               = errors.New(`Channel name in use`)
 	errInvalidChannelName             = errors.New(`Invalid channel name`)
 	errMonitorLimitExceeded           = errors.New("Monitor limit exceeded")
@@ -40,6 +41,7 @@ var (
 	errNicknameInvalid                = errors.New("invalid nickname")
 	errNicknameInUse                  = errors.New("nickname in use")
 	errNicknameReserved               = errors.New("nickname is reserved")
+	errCantChangeNick                 = errors.New(`Always-on clients can't change nicknames`)
 	errNoExistingBan                  = errors.New("Ban does not exist")
 	errNoSuchChannel                  = errors.New(`No such channel`)
 	errChannelPurged                  = errors.New(`This channel was purged by the server operators and cannot be used`)

irc/gateways.go

@@ -61,7 +61,7 @@ func (wc *webircConfig) Populate() (err error) {
 func (client *Client) ApplyProxiedIP(session *Session, proxiedIP string, tls bool) (err error, quitMsg string) {
 	// PROXY and WEBIRC are never accepted from a Tor listener, even if the address itself
 	// is whitelisted:
-	if client.isTor {
+	if session.isTor {
 		return errBadProxyLine, ""
 	}
 
@@ -88,7 +88,7 @@ func (client *Client) ApplyProxiedIP(session *Session, proxiedIP string, tls boo
 	session.proxiedIP = parsedProxiedIP
 	// nickmask will be updated when the client completes registration
 	// set tls info
-	client.certfp = ""
+	session.certfp = ""
 	client.SetMode(modes.TLS, tls)
 
 	return nil, ""

irc/getters.go

@@ -65,6 +65,7 @@ type SessionData struct {
 	atime    time.Time
 	ip       net.IP
 	hostname string
+	certfp   string
 }
 
 func (client *Client) AllSessionData(currentSession *Session) (data []SessionData, currentIndex int) {
@@ -81,6 +82,7 @@ func (client *Client) AllSessionData(currentSession *Session) (data []SessionDat
 			atime:    session.atime,
 			ctime:    session.ctime,
 			hostname: session.rawHostname,
+			certfp:   session.certfp,
 		}
 		if session.proxiedIP != nil {
 			data[i].ip = session.proxiedIP
@@ -91,21 +93,34 @@ func (client *Client) AllSessionData(currentSession *Session) (data []SessionDat
 	return
 }
 
-func (client *Client) AddSession(session *Session) (success bool) {
+func (client *Client) AddSession(session *Session) (success bool, numSessions int, lastSignoff time.Time) {
+	defer func() {
+		if !lastSignoff.IsZero() {
+			client.wakeWriter()
+		}
+	}()
+
 	client.stateMutex.Lock()
 	defer client.stateMutex.Unlock()
 
 	// client may be dying and ineligible to receive another session
 	if client.destroyed {
-		return false
+		return
 	}
 	// success, attach the new session to the client
 	session.client = client
 	newSessions := make([]*Session, len(client.sessions)+1)
 	copy(newSessions, client.sessions)
 	newSessions[len(newSessions)-1] = session
+	if len(client.sessions) == 0 && client.accountSettings.AutoreplayMissed {
+		// n.b. this is only possible if client is persistent and remained
+		// on the server with no sessions:
+		lastSignoff = client.lastSignoff
+		client.lastSignoff = time.Time{}
+		client.dirtyBits |= IncludeLastSignoff
+	}
 	client.sessions = newSessions
-	return true
+	return true, len(client.sessions), lastSignoff
 }
 
 func (client *Client) removeSession(session *Session) (success bool, length int) {
@@ -189,6 +204,13 @@ func (client *Client) SetExitedSnomaskSent() {
 	client.stateMutex.Unlock()
 }
 
+func (client *Client) AlwaysOn() (alwaysOn bool) {
+	client.stateMutex.Lock()
+	alwaysOn = client.alwaysOn
+	client.stateMutex.Unlock()
+	return
+}
+
 // uniqueIdentifiers returns the strings for which the server enforces per-client
 // uniqueness/ownership; no two clients can have colliding casefolded nicks or
 // skeletons.
@@ -264,23 +286,43 @@ func (client *Client) AccountName() string {
 	return client.accountName
 }
 
-func (client *Client) SetAccountName(account string) (changed bool) {
-	var casefoldedAccount string
-	var err error
-	if account != "" {
-		if casefoldedAccount, err = CasefoldName(account); err != nil {
-			return
-		}
-	}
-
+func (client *Client) Login(account ClientAccount) {
+	alwaysOn := persistenceEnabled(client.server.Config().Accounts.Multiclient.AlwaysOn, account.Settings.AlwaysOn)
 	client.stateMutex.Lock()
 	defer client.stateMutex.Unlock()
-	changed = client.account != casefoldedAccount
-	client.account = casefoldedAccount
-	client.accountName = account
+	client.account = account.NameCasefolded
+	client.accountName = account.Name
+	client.accountSettings = account.Settings
+	// check `registered` to avoid incorrectly marking a temporary (pre-reattach),
+	// SASL'ing client as always-on
+	if client.registered {
+		client.alwaysOn = alwaysOn
+	}
+	client.accountRegDate = account.RegisteredAt
 	return
 }
 
+func (client *Client) historyCutoff() (cutoff time.Time) {
+	client.stateMutex.Lock()
+	if client.account != "" {
+		cutoff = client.accountRegDate
+	} else {
+		cutoff = client.ctime
+	}
+	client.stateMutex.Unlock()
+	return
+}
+
+func (client *Client) Logout() {
+	client.stateMutex.Lock()
+	client.account = ""
+	client.accountName = ""
+	client.alwaysOn = false
+	client.accountRegDate = time.Time{}
+	client.accountSettings = AccountSettings{}
+	client.stateMutex.Unlock()
+}
+
 func (client *Client) AccountSettings() (result AccountSettings) {
 	client.stateMutex.RLock()
 	result = client.accountSettings
@@ -289,8 +331,12 @@ func (client *Client) AccountSettings() (result AccountSettings) {
 }
 
 func (client *Client) SetAccountSettings(settings AccountSettings) {
+	alwaysOn := persistenceEnabled(client.server.Config().Accounts.Multiclient.AlwaysOn, settings.AlwaysOn)
 	client.stateMutex.Lock()
 	client.accountSettings = settings
+	if client.registered {
+		client.alwaysOn = alwaysOn
+	}
 	client.stateMutex.Unlock()
 }
 
@@ -309,11 +355,17 @@ func (client *Client) SetLanguages(languages []string) {
 
 func (client *Client) HasMode(mode modes.Mode) bool {
 	// client.flags has its own synch
-	return client.flags.HasMode(mode)
+	return client.modes.HasMode(mode)
 }
 
 func (client *Client) SetMode(mode modes.Mode, on bool) bool {
-	return client.flags.SetMode(mode, on)
+	return client.modes.SetMode(mode, on)
+}
+
+func (client *Client) SetRealname(realname string) {
+	client.stateMutex.Lock()
+	client.realname = realname
+	client.stateMutex.Unlock()
 }
 
 func (client *Client) Channels() (result []*Channel) {
@@ -410,3 +462,17 @@ func (channel *Channel) HighestUserMode(client *Client) (result modes.Mode) {
 	channel.stateMutex.RUnlock()
 	return clientModes.HighestChannelUserMode()
 }
+
+func (channel *Channel) Settings() (result ChannelSettings) {
+	channel.stateMutex.RLock()
+	result = channel.settings
+	channel.stateMutex.RUnlock()
+	return result
+}
+
+func (channel *Channel) SetSettings(settings ChannelSettings) {
+	channel.stateMutex.Lock()
+	channel.settings = settings
+	channel.stateMutex.Unlock()
+	channel.MarkDirty(IncludeSettings)
+}

irc/handlers.go

@@ -112,6 +112,7 @@ func sendSuccessfulAccountAuth(client *Client, rb *ResponseBuffer, forNS, forSAS
 
 // AUTHENTICATE [<mechanism>|<data>|*]
 func authenticateHandler(server *Server, client *Client, msg ircmsg.IrcMessage, rb *ResponseBuffer) bool {
+	session := rb.session
 	config := server.Config()
 	details := client.Details()
 
@@ -128,20 +129,17 @@ func authenticateHandler(server *Server, client *Client, msg ircmsg.IrcMessage,
 	// sasl abort
 	if !server.AccountConfig().AuthenticationEnabled || len(msg.Params) == 1 && msg.Params[0] == "*" {
 		rb.Add(nil, server.name, ERR_SASLABORTED, details.nick, client.t("SASL authentication aborted"))
-		client.saslInProgress = false
-		client.saslMechanism = ""
-		client.saslValue = ""
+		session.sasl.Clear()
 		return false
 	}
 
 	// start new sasl session
-	if !client.saslInProgress {
+	if session.sasl.mechanism == "" {
 		mechanism := strings.ToUpper(msg.Params[0])
 		_, mechanismIsEnabled := EnabledSaslMechanisms[mechanism]
 
 		if mechanismIsEnabled {
-			client.saslInProgress = true
-			client.saslMechanism = mechanism
+			session.sasl.mechanism = mechanism
 			if !config.Server.Compatibility.SendUnprefixedSasl {
 				// normal behavior
 				rb.Add(nil, server.name, "AUTHENTICATE", "+")
@@ -162,58 +160,46 @@ func authenticateHandler(server *Server, client *Client, msg ircmsg.IrcMessage,
 
 	if len(rawData) > 400 {
 		rb.Add(nil, server.name, ERR_SASLTOOLONG, details.nick, client.t("SASL message too long"))
-		client.saslInProgress = false
-		client.saslMechanism = ""
-		client.saslValue = ""
+		session.sasl.Clear()
 		return false
 	} else if len(rawData) == 400 {
-		client.saslValue += rawData
 		// allow 4 'continuation' lines before rejecting for length
-		if len(client.saslValue) > 400*4 {
+		if len(session.sasl.value) >= 400*4 {
 			rb.Add(nil, server.name, ERR_SASLFAIL, details.nick, client.t("SASL authentication failed: Passphrase too long"))
-			client.saslInProgress = false
-			client.saslMechanism = ""
-			client.saslValue = ""
+			session.sasl.Clear()
 			return false
 		}
+		session.sasl.value += rawData
 		return false
 	}
 	if rawData != "+" {
-		client.saslValue += rawData
+		session.sasl.value += rawData
 	}
 
 	var data []byte
 	var err error
-	if client.saslValue != "+" {
-		data, err = base64.StdEncoding.DecodeString(client.saslValue)
+	if session.sasl.value != "+" {
+		data, err = base64.StdEncoding.DecodeString(session.sasl.value)
 		if err != nil {
 			rb.Add(nil, server.name, ERR_SASLFAIL, details.nick, client.t("SASL authentication failed: Invalid b64 encoding"))
-			client.saslInProgress = false
-			client.saslMechanism = ""
-			client.saslValue = ""
+			session.sasl.Clear()
 			return false
 		}
 	}
 
 	// call actual handler
-	handler, handlerExists := EnabledSaslMechanisms[client.saslMechanism]
+	handler, handlerExists := EnabledSaslMechanisms[session.sasl.mechanism]
 
 	// like 100% not required, but it's good to be safe I guess
 	if !handlerExists {
 		rb.Add(nil, server.name, ERR_SASLFAIL, details.nick, client.t("SASL authentication failed"))
-		client.saslInProgress = false
-		client.saslMechanism = ""
-		client.saslValue = ""
+		session.sasl.Clear()
 		return false
 	}
 
 	// let the SASL handler do its thing
-	exiting := handler(server, client, client.saslMechanism, data, rb)
-
-	// wait 'til SASL is done before emptying the sasl vars
-	client.saslInProgress = false
-	client.saslMechanism = ""
-	client.saslValue = ""
+	exiting := handler(server, client, session.sasl.mechanism, data, rb)
+	session.sasl.Clear()
 
 	return exiting
 }
@@ -270,7 +256,7 @@ func authErrorToMessage(server *Server, err error) (msg string) {
 
 // AUTHENTICATE EXTERNAL
 func authExternalHandler(server *Server, client *Client, mechanism string, value []byte, rb *ResponseBuffer) bool {
-	if client.certfp == "" {
+	if rb.session.certfp == "" {
 		rb.Add(nil, server.name, ERR_SASLFAIL, client.nick, client.t("SASL authentication failed, you are not connecting with a certificate"))
 		return false
 	}
@@ -287,7 +273,7 @@ func authExternalHandler(server *Server, client *Client, mechanism string, value
 	}
 
 	if err == nil {
-		err = server.accounts.AuthenticateByCertFP(client, authzid)
+		err = server.accounts.AuthenticateByCertFP(client, rb.session.certfp, authzid)
 	}
 
 	if err != nil {
@@ -531,64 +517,49 @@ func capHandler(server *Server, client *Client, msg ircmsg.IrcMessage, rb *Respo
 // CHATHISTORY <target> BETWEEN <query> <query> <direction> [<limit>]
 // e.g., CHATHISTORY #ircv3 BETWEEN timestamp=YYYY-MM-DDThh:mm:ss.sssZ timestamp=YYYY-MM-DDThh:mm:ss.sssZ + 100
 func chathistoryHandler(server *Server, client *Client, msg ircmsg.IrcMessage, rb *ResponseBuffer) (exiting bool) {
-	config := server.Config()
-
 	var items []history.Item
-	success := false
-	var hist *history.Buffer
+	unknown_command := false
+	var target string
 	var channel *Channel
+	var sequence history.Sequence
+	var err error
 	defer func() {
 		// successful responses are sent as a chathistory or history batch
-		if success && 0 < len(items) {
-			if channel == nil {
-				client.replayPrivmsgHistory(rb, items, true)
-			} else {
+		if err == nil {
+			if channel != nil {
 				channel.replayHistoryItems(rb, items, false)
+			} else {
+				client.replayPrivmsgHistory(rb, items, target, true)
 			}
 			return
 		}
 
 		// errors are sent either without a batch, or in a draft/labeled-response batch as usual
-		// TODO: send `WARN CHATHISTORY MAX_MESSAGES_EXCEEDED` when appropriate
-		if hist == nil {
-			rb.Add(nil, server.name, "ERR", "CHATHISTORY", "NO_SUCH_CHANNEL")
-		} else if len(items) == 0 {
-			rb.Add(nil, server.name, "ERR", "CHATHISTORY", "NO_TEXT_TO_SEND")
-		} else if !success {
-			rb.Add(nil, server.name, "ERR", "CHATHISTORY", "NEED_MORE_PARAMS")
+		if unknown_command {
+			rb.Add(nil, server.name, "FAIL", "CHATHISTORY", "UNKNOWN_COMMAND", utils.SafeErrorParam(msg.Params[0]), client.t("Unknown command"))
+		} else if err == utils.ErrInvalidParams {
+			rb.Add(nil, server.name, "FAIL", "CHATHISTORY", "INVALID_PARAMETERS", msg.Params[0], client.t("Invalid parameters"))
+		} else if err != nil {
+			rb.Add(nil, server.name, "FAIL", "CHATHISTORY", "MESSAGE_ERROR", msg.Params[0], client.t("Messages could not be retrieved"))
+		} else if sequence == nil {
+			rb.Add(nil, server.name, "FAIL", "CHATHISTORY", "NO_SUCH_CHANNEL", utils.SafeErrorParam(msg.Params[1]), client.t("No such channel"))
 		}
 	}()
 
-	target := msg.Params[0]
-	channel = server.channels.Get(target)
-	if channel != nil && channel.hasClient(client) {
-		// "If [...] the user does not have permission to view the requested content, [...]
-		// NO_SUCH_CHANNEL SHOULD be returned"
-		hist = &channel.history
-	} else {
-		targetClient := server.clients.Get(target)
-		if targetClient != nil {
-			myAccount := client.Account()
-			targetAccount := targetClient.Account()
-			if myAccount != "" && targetAccount != "" && myAccount == targetAccount {
-				hist = &targetClient.history
-			}
-		}
-	}
-	if hist == nil {
+	config := server.Config()
+	maxChathistoryLimit := config.History.ChathistoryMax
+	if maxChathistoryLimit == 0 {
 		return
 	}
 
-	preposition := strings.ToLower(msg.Params[1])
-
 	parseQueryParam := func(param string) (msgid string, timestamp time.Time, err error) {
-		err = errInvalidParams
+		err = utils.ErrInvalidParams
 		pieces := strings.SplitN(param, "=", 2)
 		if len(pieces) < 2 {
 			return
 		}
 		identifier, value := strings.ToLower(pieces[0]), pieces[1]
-		if identifier == "id" {
+		if identifier == "msgid" {
 			msgid, err = value, nil
 			return
 		} else if identifier == "timestamp" {
@@ -598,10 +569,6 @@ func chathistoryHandler(server *Server, client *Client, msg ircmsg.IrcMessage, r
 		return
 	}
 
-	maxChathistoryLimit := config.History.ChathistoryMax
-	if maxChathistoryLimit == 0 {
-		return
-	}
 	parseHistoryLimit := func(paramIndex int) (limit int) {
 		if len(msg.Params) < (paramIndex + 1) {
 			return maxChathistoryLimit
@@ -613,140 +580,74 @@ func chathistoryHandler(server *Server, client *Client, msg ircmsg.IrcMessage, r
 		return
 	}
 
-	// TODO: as currently implemented, almost all of thes queries are worst-case O(n)
-	// in the number of stored history entries. Every one of them can be made O(1)
-	// if necessary, without too much difficulty. Some ideas:
-	// * Ensure that the ring buffer is sorted by time, enabling binary search for times
-	// * Maintain a map from msgid to position in the ring buffer
-
-	if preposition == "between" {
-		if len(msg.Params) >= 5 {
-			startMsgid, startTimestamp, startErr := parseQueryParam(msg.Params[2])
-			endMsgid, endTimestamp, endErr := parseQueryParam(msg.Params[3])
-			ascending := msg.Params[4] == "+"
-			limit := parseHistoryLimit(5)
-			if startErr != nil || endErr != nil {
-				success = false
-			} else if startMsgid != "" && endMsgid != "" {
-				inInterval := false
-				matches := func(item history.Item) (result bool) {
-					result = inInterval
-					if item.HasMsgid(startMsgid) {
-						if ascending {
-							inInterval = true
-						} else {
-							inInterval = false
-							return false // interval is exclusive
-						}
-					} else if item.HasMsgid(endMsgid) {
-						if ascending {
-							inInterval = false
-							return false
-						} else {
-							inInterval = true
-						}
-					}
-					return
-				}
-				items = hist.Match(matches, ascending, limit)
-				success = true
-			} else if !startTimestamp.IsZero() && !endTimestamp.IsZero() {
-				items, _ = hist.Between(startTimestamp, endTimestamp, ascending, limit)
-				if !ascending {
-					history.Reverse(items)
-				}
-				success = true
-			}
-			// else: mismatched params, success = false, fail
-		}
+	preposition := strings.ToLower(msg.Params[0])
+	target = msg.Params[1]
+	channel, sequence, err = server.GetHistorySequence(nil, client, target)
+	if err != nil || sequence == nil {
 		return
 	}
 
-	// before, after, latest, around
-	queryParam := msg.Params[2]
-	msgid, timestamp, err := parseQueryParam(queryParam)
-	limit := parseHistoryLimit(3)
-	before := false
-	switch preposition {
-	case "before":
-		before = true
-		fallthrough
-	case "after":
-		var matches history.Predicate
-		if err != nil {
-			break
-		} else if msgid != "" {
-			inInterval := false
-			matches = func(item history.Item) (result bool) {
-				result = inInterval
-				if item.HasMsgid(msgid) {
-					inInterval = true
-				}
-				return
-			}
-		} else {
-			matches = func(item history.Item) bool {
-				return before == item.Message.Time.Before(timestamp)
-			}
-		}
-		items = hist.Match(matches, !before, limit)
-		success = true
-	case "latest":
-		if queryParam == "*" {
-			items = hist.Latest(limit)
-		} else if err != nil {
-			break
-		} else {
-			var matches history.Predicate
-			if msgid != "" {
-				shouldStop := false
-				matches = func(item history.Item) bool {
-					if shouldStop {
-						return false
-					}
-					shouldStop = item.HasMsgid(msgid)
-					return !shouldStop
-				}
-			} else {
-				matches = func(item history.Item) bool {
-					return item.Message.Time.After(timestamp)
-				}
-			}
-			items = hist.Match(matches, false, limit)
-		}
-		success = true
-	case "around":
-		if err != nil {
-			break
-		}
-		var initialMatcher history.Predicate
-		if msgid != "" {
-			inInterval := false
-			initialMatcher = func(item history.Item) (result bool) {
-				if inInterval {
-					return true
-				} else {
-					inInterval = item.HasMsgid(msgid)
-					return inInterval
-				}
-			}
-		} else {
-			initialMatcher = func(item history.Item) (result bool) {
-				return item.Message.Time.Before(timestamp)
-			}
-		}
-		var halfLimit int
-		halfLimit = (limit + 1) / 2
-		firstPass := hist.Match(initialMatcher, false, halfLimit)
-		if len(firstPass) > 0 {
-			timeWindowStart := firstPass[0].Message.Time
-			items = hist.Match(func(item history.Item) bool {
-				return item.Message.Time.Equal(timeWindowStart) || item.Message.Time.After(timeWindowStart)
-			}, true, limit)
-		}
-		success = true
+	roundUp := func(endpoint time.Time) (result time.Time) {
+		return endpoint.Truncate(time.Millisecond).Add(time.Millisecond)
 	}
 
+	var start, end history.Selector
+	var limit int
+	switch preposition {
+	case "between":
+		start.Msgid, start.Time, err = parseQueryParam(msg.Params[2])
+		if err != nil {
+			return
+		}
+		end.Msgid, end.Time, err = parseQueryParam(msg.Params[3])
+		if err != nil {
+			return
+		}
+		// XXX preserve the ordering of the two parameters, since we might be going backwards,
+		// but round up the chronologically first one, whichever it is, to make it exclusive
+		if !start.Time.IsZero() && !end.Time.IsZero() {
+			if start.Time.Before(end.Time) {
+				start.Time = roundUp(start.Time)
+			} else {
+				end.Time = roundUp(end.Time)
+			}
+		}
+		limit = parseHistoryLimit(4)
+	case "before", "after", "around":
+		start.Msgid, start.Time, err = parseQueryParam(msg.Params[2])
+		if err != nil {
+			return
+		}
+		if preposition == "after" && !start.Time.IsZero() {
+			start.Time = roundUp(start.Time)
+		}
+		if preposition == "before" {
+			end = start
+			start = history.Selector{}
+		}
+		limit = parseHistoryLimit(3)
+	case "latest":
+		if msg.Params[2] != "*" {
+			end.Msgid, end.Time, err = parseQueryParam(msg.Params[2])
+			if err != nil {
+				return
+			}
+			if !end.Time.IsZero() {
+				end.Time = roundUp(end.Time)
+			}
+			start.Time = time.Now().UTC()
+		}
+		limit = parseHistoryLimit(3)
+	default:
+		unknown_command = true
+		return
+	}
+
+	if preposition == "around" {
+		items, err = sequence.Around(start, limit)
+	} else {
+		items, _, err = sequence.Between(start, end, limit)
+	}
 	return
 }
 
@@ -1026,6 +927,7 @@ Get an explanation of <argument>, or "index" for a list of help topics.`), rb)
 // HISTORY <target> [<limit>]
 // e.g., HISTORY #ubuntu 10
 // HISTORY me 15
+// HISTORY #darwin 1h
 func historyHandler(server *Server, client *Client, msg ircmsg.IrcMessage, rb *ResponseBuffer) bool {
 	config := server.Config()
 	if !config.History.Enabled {
@@ -1034,53 +936,55 @@ func historyHandler(server *Server, client *Client, msg ircmsg.IrcMessage, rb *R
 	}
 
 	target := msg.Params[0]
-	var hist *history.Buffer
-	channel := server.channels.Get(target)
-	if channel != nil && channel.hasClient(client) {
-		hist = &channel.history
-	} else {
-		if strings.ToLower(target) == "me" {
-			hist = &client.history
-		} else {
-			targetClient := server.clients.Get(target)
-			if targetClient != nil {
-				myAccount, targetAccount := client.Account(), targetClient.Account()
-				if myAccount != "" && targetAccount != "" && myAccount == targetAccount {
-					hist = &targetClient.history
-				}
+	if strings.ToLower(target) == "me" {
+		target = "*"
+	}
+	channel, sequence, err := server.GetHistorySequence(nil, client, target)
+
+	if sequence == nil || err != nil {
+		// whatever
+		rb.Add(nil, server.name, ERR_NOSUCHCHANNEL, client.Nick(), utils.SafeErrorParam(target), client.t("No such channel"))
+		return false
+	}
+
+	var duration time.Duration
+	maxChathistoryLimit := config.History.ChathistoryMax
+	limit := 100
+	if maxChathistoryLimit < limit {
+		limit = maxChathistoryLimit
+	}
+	if len(msg.Params) > 1 {
+		providedLimit, err := strconv.Atoi(msg.Params[1])
+		if err == nil && providedLimit != 0 {
+			limit = providedLimit
+			if maxChathistoryLimit < limit {
+				limit = maxChathistoryLimit
+			}
+		} else if err != nil {
+			duration, err = time.ParseDuration(msg.Params[1])
+			if err == nil {
+				limit = maxChathistoryLimit
 			}
 		}
 	}
 
-	if hist == nil {
-		if channel == nil {
-			rb.Add(nil, server.name, ERR_NOSUCHCHANNEL, client.Nick(), utils.SafeErrorParam(target), client.t("No such channel"))
-		} else {
-			rb.Add(nil, server.name, ERR_NOTONCHANNEL, client.Nick(), target, client.t("You're not on that channel"))
-		}
-		return false
-	}
-
-	limit := 10
-	maxChathistoryLimit := config.History.ChathistoryMax
-	if len(msg.Params) > 1 {
-		providedLimit, err := strconv.Atoi(msg.Params[1])
-		if providedLimit > maxChathistoryLimit {
-			providedLimit = maxChathistoryLimit
-		}
-		if err == nil && providedLimit != 0 {
-			limit = providedLimit
-		}
-	}
-
-	items := hist.Latest(limit)
-
-	if channel != nil {
-		channel.replayHistoryItems(rb, items, false)
+	var items []history.Item
+	if duration == 0 {
+		items, _, err = sequence.Between(history.Selector{}, history.Selector{}, limit)
 	} else {
-		client.replayPrivmsgHistory(rb, items, true)
+		now := time.Now().UTC()
+		start := history.Selector{Time: now}
+		end := history.Selector{Time: now.Add(-duration)}
+		items, _, err = sequence.Between(start, end, limit)
 	}
 
+	if err == nil && len(items) != 0 {
+		if channel != nil {
+			channel.replayHistoryItems(rb, items, false)
+		} else {
+			client.replayPrivmsgHistory(rb, items, "", true)
+		}
+	}
 	return false
 }
 
@@ -1964,7 +1868,7 @@ func messageHandler(server *Server, client *Client, msg ircmsg.IrcMessage, rb *R
 		return false
 	}
 
-	if client.isTor && utils.IsRestrictedCTCPMessage(message) {
+	if rb.session.isTor && utils.IsRestrictedCTCPMessage(message) {
 		// note that error replies are never sent for NOTICE
 		if histType != history.Notice {
 			rb.Notice(client.t("CTCP messages are disabled over Tor"))
@@ -2021,46 +1925,34 @@ func dispatchMessageToTarget(client *Client, tags map[string]string, histType hi
 			}
 			return
 		}
-		tnick := user.Nick()
+		tDetails := user.Details()
+		tnick := tDetails.nick
 
-		nickMaskString := client.NickMaskString()
-		accountName := client.AccountName()
+		details := client.Details()
+		nickMaskString := details.nickMask
+		accountName := details.accountName
+		var deliverySessions []*Session
 		// restrict messages appropriately when +R is set
 		// intentionally make the sending user think the message went through fine
-		allowedPlusR := !user.HasMode(modes.RegisteredOnly) || client.LoggedIntoAccount()
-		allowedTor := !user.isTor || !message.IsRestrictedCTCPMessage()
-		if allowedPlusR && allowedTor {
-			for _, session := range user.Sessions() {
-				hasTagsCap := session.capabilities.Has(caps.MessageTags)
-				// don't send TAGMSG at all if they don't have the tags cap
-				if histType == history.Tagmsg && hasTagsCap {
-					session.sendFromClientInternal(false, message.Time, message.Msgid, nickMaskString, accountName, tags, command, tnick)
-				} else if histType != history.Tagmsg {
-					tagsToSend := tags
-					if !hasTagsCap {
-						tagsToSend = nil
-					}
-					session.sendSplitMsgFromClientInternal(false, nickMaskString, accountName, tagsToSend, command, tnick, message)
+		allowedPlusR := details.account != "" || !user.HasMode(modes.RegisteredOnly)
+		if allowedPlusR {
+			deliverySessions = append(deliverySessions, user.Sessions()...)
+		}
+		// all sessions of the sender, except the originating session, get a copy as well:
+		if client != user {
+			for _, session := range client.Sessions() {
+				if session != rb.session {
+					deliverySessions = append(deliverySessions, session)
 				}
 			}
 		}
-		// an echo-message may need to be included in the response:
-		if rb.session.capabilities.Has(caps.EchoMessage) {
-			if histType == history.Tagmsg && rb.session.capabilities.Has(caps.MessageTags) {
-				rb.AddFromClient(message.Time, message.Msgid, nickMaskString, accountName, tags, command, tnick)
-			} else {
-				rb.AddSplitMessageFromClient(nickMaskString, accountName, tags, command, tnick, message)
-			}
-		}
-		// an echo-message may need to go out to other client sessions:
-		for _, session := range client.Sessions() {
-			if session == rb.session {
-				continue
-			}
+
+		for _, session := range deliverySessions {
 			hasTagsCap := session.capabilities.Has(caps.MessageTags)
+			// don't send TAGMSG at all if they don't have the tags cap
 			if histType == history.Tagmsg && hasTagsCap {
 				session.sendFromClientInternal(false, message.Time, message.Msgid, nickMaskString, accountName, tags, command, tnick)
-			} else if histType != history.Tagmsg {
+			} else if histType != history.Tagmsg && !(session.isTor && message.IsRestrictedCTCPMessage()) {
 				tagsToSend := tags
 				if !hasTagsCap {
 					tagsToSend = nil
@@ -2068,22 +1960,56 @@ func dispatchMessageToTarget(client *Client, tags map[string]string, histType hi
 				session.sendSplitMsgFromClientInternal(false, nickMaskString, accountName, tagsToSend, command, tnick, message)
 			}
 		}
+
+		// the originating session may get an echo message:
+		if rb.session.capabilities.Has(caps.EchoMessage) {
+			hasTagsCap := rb.session.capabilities.Has(caps.MessageTags)
+			if histType == history.Tagmsg && hasTagsCap {
+				rb.AddFromClient(message.Time, message.Msgid, nickMaskString, accountName, tags, command, tnick)
+			} else {
+				tagsToSend := tags
+				if !hasTagsCap {
+					tagsToSend = nil
+				}
+				rb.AddSplitMessageFromClient(nickMaskString, accountName, tagsToSend, command, tnick, message)
+			}
+		}
 		if histType != history.Notice && user.Away() {
 			//TODO(dan): possibly implement cooldown of away notifications to users
 			rb.Add(nil, server.name, RPL_AWAY, client.Nick(), tnick, user.AwayMessage())
 		}
 
+		config := server.Config()
+		if !config.History.Enabled {
+			return
+		}
 		item := history.Item{
 			Type:        histType,
 			Message:     message,
 			Nick:        nickMaskString,
 			AccountName: accountName,
+			Tags:        tags,
+		}
+		if !item.IsStorable() {
+			return
+		}
+		targetedItem := item
+		targetedItem.Params[0] = tnick
+		cPersistent, cEphemeral, _ := client.historyStatus(config)
+		tPersistent, tEphemeral, _ := user.historyStatus(config)
+		// add to ephemeral history
+		if cEphemeral {
+			targetedItem.CfCorrespondent = tDetails.nickCasefolded
+			client.history.Add(targetedItem)
+		}
+		if tEphemeral && client != user {
+			item.CfCorrespondent = details.nickCasefolded
+			user.history.Add(item)
+		}
+		if cPersistent || tPersistent {
+			item.CfCorrespondent = ""
+			server.historyDB.AddDirectMessage(details.nickCasefolded, user.NickCasefolded(), cPersistent, tPersistent, targetedItem)
 		}
-		// add to the target's history:
-		user.history.Add(item)
-		// add this to the client's history as well, recording the target:
-		item.Params[0] = tnick
-		client.history.Add(item)
 	}
 }
 
@@ -2136,7 +2062,7 @@ func operHandler(server *Server, client *Client, msg ircmsg.IrcMessage, rb *Resp
 	oper := server.GetOperator(msg.Params[0])
 	if oper != nil {
 		if oper.Fingerprint != "" {
-			if oper.Fingerprint == client.certfp {
+			if oper.Fingerprint == rb.session.certfp {
 				checkPassed = true
 			} else {
 				checkFailed = true
@@ -2239,7 +2165,7 @@ func passHandler(server *Server, client *Client, msg ircmsg.IrcMessage, rb *Resp
 
 	// check the provided password
 	password := []byte(msg.Params[0])
-	client.sentPassCommand = bcrypt.CompareHashAndPassword(serverPassword, password) == nil
+	rb.session.sentPassCommand = bcrypt.CompareHashAndPassword(serverPassword, password) == nil
 
 	// if they failed the check, we'll bounce them later when they try to complete registration
 	return false
@@ -2409,11 +2335,7 @@ func sceneHandler(server *Server, client *Client, msg ircmsg.IrcMessage, rb *Res
 // SETNAME <realname>
 func setnameHandler(server *Server, client *Client, msg ircmsg.IrcMessage, rb *ResponseBuffer) bool {
 	realname := msg.Params[0]
-
-	client.stateMutex.Lock()
-	client.realname = realname
-	client.stateMutex.Unlock()
-
+	client.SetRealname(realname)
 	details := client.Details()
 
 	// alert friends
@@ -2622,7 +2544,7 @@ func webircHandler(server *Server, client *Client, msg ircmsg.IrcMessage, rb *Re
 			if 0 < len(info.Password) && bcrypt.CompareHashAndPassword(info.Password, givenPassword) != nil {
 				continue
 			}
-			if info.Fingerprint != "" && info.Fingerprint != client.certfp {
+			if info.Fingerprint != "" && info.Fingerprint != rb.session.certfp {
 				continue
 			}
 

irc/help.go

@@ -145,9 +145,9 @@ http://ircv3.net/specs/core/capability-negotiation-3.2.html`,
 	"chathistory": {
 		text: `CHATHISTORY [params]
 
-CHATHISTORY is an experimental history replay command. See these documents:
-https://github.com/MuffinMedic/ircv3-specifications/blob/chathistory/extensions/chathistory.md
-https://gist.github.com/DanielOaks/c104ad6e8759c01eb5c826d627caf80d`,
+CHATHISTORY is a history replay command associated with the IRCv3
+specification draft/chathistory. See this document:
+https://github.com/ircv3/ircv3-specifications/pull/393`,
 	},
 	"debug": {
 		oper: true,
@@ -213,8 +213,9 @@ Get an explanation of <argument>, or "index" for a list of help topics.`,
 
 Replay message history. <target> can be a channel name, "me" to replay direct
 message history, or a nickname to replay another client's direct message
-history (they must be logged into the same account as you). At most [limit]
-messages will be replayed.`,
+history (they must be logged into the same account as you). [limit] can be
+either an integer (the maximum number of messages to replay), or a time
+duration like 10m or 1h (the time window within which to replay messages).`,
 	},
 	"info": {
 		text: `INFO

irc/history/history.go

@@ -6,7 +6,6 @@ package history
 import (
 	"github.com/oragono/oragono/irc/utils"
 	"sync"
-	"sync/atomic"
 	"time"
 )
 
@@ -46,6 +45,10 @@ type Item struct {
 	Message utils.SplitMessage
 	Tags    map[string]string
 	Params  [1]string
+	// for a DM, this is the casefolded nickname of the other party (whether this is
+	// an incoming or outgoing message). this lets us emulate the "query buffer" functionality
+	// required by CHATHISTORY:
+	CfCorrespondent string
 }
 
 // HasMsgid tests whether a message has the message id `msgid`.
@@ -53,20 +56,30 @@ func (item *Item) HasMsgid(msgid string) bool {
 	return item.Message.Msgid == msgid
 }
 
-func (item *Item) isStorable() bool {
-	if item.Type == Tagmsg {
+func (item *Item) IsStorable() bool {
+	switch item.Type {
+	case Tagmsg:
 		for name := range item.Tags {
 			if !transientTags[name] {
 				return true
 			}
 		}
 		return false // all tags were blacklisted
-	} else {
+	case Privmsg, Notice:
+		// don't store CTCP other than ACTION
+		return !item.Message.IsRestrictedCTCPMessage()
+	default:
 		return true
 	}
 }
 
-type Predicate func(item Item) (matches bool)
+type Predicate func(item *Item) (matches bool)
+
+func Reverse(results []Item) {
+	for i, j := 0, len(results)-1; i < j; i, j = i+1, j-1 {
+		results[i], results[j] = results[j], results[i]
+	}
+}
 
 // Buffer is a ring buffer holding message/event history for a channel or user
 type Buffer struct {
@@ -81,8 +94,6 @@ type Buffer struct {
 
 	lastDiscarded time.Time
 
-	enabled uint32
-
 	nowFunc func() time.Time
 }
 
@@ -99,8 +110,6 @@ func (hist *Buffer) Initialize(size int, window time.Duration) {
 	hist.window = window
 	hist.maximumSize = size
 	hist.nowFunc = time.Now
-
-	hist.setEnabled(size)
 }
 
 // compute the initial size for the buffer, taking into account autoresize
@@ -115,31 +124,8 @@ func (hist *Buffer) initialSize(size int, window time.Duration) (result int) {
 	return
 }
 
-func (hist *Buffer) setEnabled(size int) {
-	var enabled uint32
-	if size != 0 {
-		enabled = 1
-	}
-	atomic.StoreUint32(&hist.enabled, enabled)
-}
-
-// Enabled returns whether the buffer is currently storing messages
-// (a disabled buffer blackholes everything it sees)
-func (list *Buffer) Enabled() bool {
-	return atomic.LoadUint32(&list.enabled) != 0
-}
-
 // Add adds a history item to the buffer
 func (list *Buffer) Add(item Item) {
-	// fast path without a lock acquisition for when we are not storing history
-	if !list.Enabled() {
-		return
-	}
-
-	if !item.isStorable() {
-		return
-	}
-
 	if item.Message.Time.IsZero() {
 		item.Message.Time = time.Now().UTC()
 	}
@@ -147,6 +133,10 @@ func (list *Buffer) Add(item Item) {
 	list.Lock()
 	defer list.Unlock()
 
+	if len(list.buffer) == 0 {
+		return
+	}
+
 	list.maybeExpand()
 
 	var pos int
@@ -170,55 +160,100 @@ func (list *Buffer) Add(item Item) {
 	list.buffer[pos] = item
 }
 
-// Reverse reverses an []Item, in-place.
-func Reverse(results []Item) {
-	for i, j := 0, len(results)-1; i < j; i, j = i+1, j-1 {
-		results[i], results[j] = results[j], results[i]
+func (list *Buffer) lookup(msgid string) (result Item, found bool) {
+	predicate := func(item *Item) bool {
+		return item.HasMsgid(msgid)
 	}
+	results := list.matchInternal(predicate, false, 1)
+	if len(results) != 0 {
+		return results[0], true
+	}
+	return
 }
 
 // Between returns all history items with a time `after` <= time <= `before`,
 // with an indication of whether the results are complete or are missing items
 // because some of that period was discarded. A zero value of `before` is considered
 // higher than all other times.
-func (list *Buffer) Between(after, before time.Time, ascending bool, limit int) (results []Item, complete bool) {
-	if !list.Enabled() {
-		return
-	}
+func (list *Buffer) betweenHelper(start, end Selector, cutoff time.Time, pred Predicate, limit int) (results []Item, complete bool, err error) {
+	var ascending bool
+
+	defer func() {
+		if !ascending {
+			Reverse(results)
+		}
+	}()
 
 	list.RLock()
 	defer list.RUnlock()
 
+	if len(list.buffer) == 0 {
+		return
+	}
+
+	after := start.Time
+	if start.Msgid != "" {
+		item, found := list.lookup(start.Msgid)
+		if !found {
+			return
+		}
+		after = item.Message.Time
+	}
+	before := end.Time
+	if end.Msgid != "" {
+		item, found := list.lookup(end.Msgid)
+		if !found {
+			return
+		}
+		before = item.Message.Time
+	}
+
+	after, before, ascending = MinMaxAsc(after, before, cutoff)
+
 	complete = after.Equal(list.lastDiscarded) || after.After(list.lastDiscarded)
 
-	satisfies := func(item Item) bool {
-		return (after.IsZero() || item.Message.Time.After(after)) && (before.IsZero() || item.Message.Time.Before(before))
+	satisfies := func(item *Item) bool {
+		return (after.IsZero() || item.Message.Time.After(after)) &&
+			(before.IsZero() || item.Message.Time.Before(before)) &&
+			(pred == nil || pred(item))
 	}
 
-	return list.matchInternal(satisfies, ascending, limit), complete
+	return list.matchInternal(satisfies, ascending, limit), complete, nil
 }
 
-// Match returns all history items such that `predicate` returns true for them.
-// Items are considered in reverse insertion order if `ascending` is false, or
-// in insertion order if `ascending` is true, up to a total of `limit` matches
-// if `limit` > 0 (unlimited otherwise).
-// `predicate` MAY be a closure that maintains its own state across invocations;
-// it MUST NOT acquire any locks or otherwise do anything weird.
-// Results are always returned in insertion order.
-func (list *Buffer) Match(predicate Predicate, ascending bool, limit int) (results []Item) {
-	if !list.Enabled() {
-		return
+// implements history.Sequence, emulating a single history buffer (for a channel,
+// a single user's DMs, or a DM conversation)
+type bufferSequence struct {
+	list   *Buffer
+	pred   Predicate
+	cutoff time.Time
+}
+
+func (list *Buffer) MakeSequence(correspondent string, cutoff time.Time) Sequence {
+	var pred Predicate
+	if correspondent != "" {
+		pred = func(item *Item) bool {
+			return item.CfCorrespondent == correspondent
+		}
 	}
+	return &bufferSequence{
+		list:   list,
+		pred:   pred,
+		cutoff: cutoff,
+	}
+}
 
-	list.RLock()
-	defer list.RUnlock()
+func (seq *bufferSequence) Between(start, end Selector, limit int) (results []Item, complete bool, err error) {
+	return seq.list.betweenHelper(start, end, seq.cutoff, seq.pred, limit)
+}
 
-	return list.matchInternal(predicate, ascending, limit)
+func (seq *bufferSequence) Around(start Selector, limit int) (results []Item, err error) {
+	return GenericAround(seq, start, limit)
 }
 
 // you must be holding the read lock to call this
 func (list *Buffer) matchInternal(predicate Predicate, ascending bool, limit int) (results []Item) {
-	if list.start == -1 {
+	if list.start == -1 || len(list.buffer) == 0 {
 		return
 	}
 
@@ -232,7 +267,7 @@ func (list *Buffer) matchInternal(predicate Predicate, ascending bool, limit int
 	}
 
 	for {
-		if predicate(list.buffer[pos]) {
+		if predicate(&list.buffer[pos]) {
 			results = append(results, list.buffer[pos])
 		}
 		if pos == stop || (limit != 0 && len(results) == limit) {
@@ -245,18 +280,14 @@ func (list *Buffer) matchInternal(predicate Predicate, ascending bool, limit int
 		}
 	}
 
-	// TODO sort by time instead?
-	if !ascending {
-		Reverse(results)
-	}
 	return
 }
 
-// Latest returns the items most recently added, up to `limit`. If `limit` is 0,
+// latest returns the items most recently added, up to `limit`. If `limit` is 0,
 // it returns all items.
-func (list *Buffer) Latest(limit int) (results []Item) {
-	matchAll := func(item Item) bool { return true }
-	return list.Match(matchAll, false, limit)
+func (list *Buffer) latest(limit int) (results []Item) {
+	results, _, _ = list.betweenHelper(Selector{}, Selector{}, time.Time{}, nil, limit)
+	return
 }
 
 // LastDiscarded returns the latest time of any entry that was evicted
@@ -355,8 +386,6 @@ func (list *Buffer) Resize(maximumSize int, window time.Duration) {
 func (list *Buffer) resize(size int) {
 	newbuffer := make([]Item, size)
 
-	list.setEnabled(size)
-
 	if list.start == -1 {
 		// indices are already correct and nothing needs to be copied
 	} else if size == 0 {

irc/history/history_test.go

@@ -14,19 +14,21 @@ const (
 	timeFormat = "2006-01-02 15:04:05Z"
 )
 
+func betweenTimestamps(buf *Buffer, start, end time.Time, limit int) (result []Item, complete bool) {
+	result, complete, _ = buf.betweenHelper(Selector{Time: start}, Selector{Time: end}, time.Time{}, nil, limit)
+	return
+}
+
 func TestEmptyBuffer(t *testing.T) {
 	pastTime := easyParse(timeFormat)
 
 	buf := NewHistoryBuffer(0, 0)
-	if buf.Enabled() {
-		t.Error("the buffer of size 0 must be considered disabled")
-	}
 
 	buf.Add(Item{
 		Nick: "testnick",
 	})
 
-	since, complete := buf.Between(pastTime, time.Now(), false, 0)
+	since, complete := betweenTimestamps(buf, pastTime, time.Now(), 0)
 	if len(since) != 0 {
 		t.Error("shouldn't be able to add to disabled buf")
 	}
@@ -35,16 +37,13 @@ func TestEmptyBuffer(t *testing.T) {
 	}
 
 	buf.Resize(1, 0)
-	if !buf.Enabled() {
-		t.Error("the buffer of size 1 must be considered enabled")
-	}
-	since, complete = buf.Between(pastTime, time.Now(), false, 0)
+	since, complete = betweenTimestamps(buf, pastTime, time.Now(), 0)
 	assertEqual(complete, true, t)
 	assertEqual(len(since), 0, t)
 	buf.Add(Item{
 		Nick: "testnick",
 	})
-	since, complete = buf.Between(pastTime, time.Now(), false, 0)
+	since, complete = betweenTimestamps(buf, pastTime, time.Now(), 0)
 	if len(since) != 1 {
 		t.Error("should be able to store items in a nonempty buffer")
 	}
@@ -58,7 +57,7 @@ func TestEmptyBuffer(t *testing.T) {
 	buf.Add(Item{
 		Nick: "testnick2",
 	})
-	since, complete = buf.Between(pastTime, time.Now(), false, 0)
+	since, complete = betweenTimestamps(buf, pastTime, time.Now(), 0)
 	if len(since) != 1 {
 		t.Error("expect exactly 1 item")
 	}
@@ -68,8 +67,7 @@ func TestEmptyBuffer(t *testing.T) {
 	if since[0].Nick != "testnick2" {
 		t.Error("retrieved junk data")
 	}
-	matchAll := func(item Item) bool { return true }
-	assertEqual(toNicks(buf.Match(matchAll, false, 0)), []string{"testnick2"}, t)
+	assertEqual(toNicks(buf.latest(0)), []string{"testnick2"}, t)
 }
 
 func toNicks(items []Item) (result []string) {
@@ -110,27 +108,27 @@ func TestBuffer(t *testing.T) {
 
 	buf.Add(easyItem("testnick2", "2006-01-03 15:04:05Z"))
 
-	since, complete := buf.Between(start, time.Now(), false, 0)
+	since, complete := betweenTimestamps(buf, start, time.Now(), 0)
 	assertEqual(complete, true, t)
 	assertEqual(toNicks(since), []string{"testnick0", "testnick1", "testnick2"}, t)
 
 	// add another item, evicting the first
 	buf.Add(easyItem("testnick3", "2006-01-04 15:04:05Z"))
 
-	since, complete = buf.Between(start, time.Now(), false, 0)
+	since, complete = betweenTimestamps(buf, start, time.Now(), 0)
 	assertEqual(complete, false, t)
 	assertEqual(toNicks(since), []string{"testnick1", "testnick2", "testnick3"}, t)
 	// now exclude the time of the discarded entry; results should be complete again
-	since, complete = buf.Between(easyParse("2006-01-02 00:00:00Z"), time.Now(), false, 0)
+	since, complete = betweenTimestamps(buf, easyParse("2006-01-02 00:00:00Z"), time.Now(), 0)
 	assertEqual(complete, true, t)
 	assertEqual(toNicks(since), []string{"testnick1", "testnick2", "testnick3"}, t)
-	since, complete = buf.Between(easyParse("2006-01-02 00:00:00Z"), easyParse("2006-01-03 00:00:00Z"), false, 0)
+	since, complete = betweenTimestamps(buf, easyParse("2006-01-02 00:00:00Z"), easyParse("2006-01-03 00:00:00Z"), 0)
 	assertEqual(complete, true, t)
 	assertEqual(toNicks(since), []string{"testnick1"}, t)
 
 	// shrink the buffer, cutting off testnick1
 	buf.Resize(2, 0)
-	since, complete = buf.Between(easyParse("2006-01-02 00:00:00Z"), time.Now(), false, 0)
+	since, complete = betweenTimestamps(buf, easyParse("2006-01-02 00:00:00Z"), time.Now(), 0)
 	assertEqual(complete, false, t)
 	assertEqual(toNicks(since), []string{"testnick2", "testnick3"}, t)
 
@@ -138,18 +136,19 @@ func TestBuffer(t *testing.T) {
 	buf.Add(easyItem("testnick4", "2006-01-05 15:04:05Z"))
 	buf.Add(easyItem("testnick5", "2006-01-06 15:04:05Z"))
 	buf.Add(easyItem("testnick6", "2006-01-07 15:04:05Z"))
-	since, complete = buf.Between(easyParse("2006-01-03 00:00:00Z"), time.Now(), false, 0)
+	since, complete = betweenTimestamps(buf, easyParse("2006-01-03 00:00:00Z"), time.Now(), 0)
 	assertEqual(complete, true, t)
 	assertEqual(toNicks(since), []string{"testnick2", "testnick3", "testnick4", "testnick5", "testnick6"}, t)
 
 	// test ascending order
-	since, _ = buf.Between(easyParse("2006-01-03 00:00:00Z"), time.Now(), true, 2)
+	since, _ = betweenTimestamps(buf, easyParse("2006-01-03 00:00:00Z"), time.Time{}, 2)
 	assertEqual(toNicks(since), []string{"testnick2", "testnick3"}, t)
 }
 
 func autoItem(id int, t time.Time) (result Item) {
 	result.Message.Time = t
 	result.Nick = strconv.Itoa(id)
+	result.Message.Msgid = result.Nick
 	return
 }
 
@@ -181,7 +180,7 @@ func TestAutoresize(t *testing.T) {
 		now = now.Add(time.Minute * 10)
 		id += 1
 	}
-	items := buf.Latest(0)
+	items := buf.latest(0)
 	assertEqual(len(items), initialAutoSize, t)
 	assertEqual(atoi(items[0].Nick), 40, t)
 	assertEqual(atoi(items[len(items)-1].Nick), 71, t)
@@ -195,7 +194,7 @@ func TestAutoresize(t *testing.T) {
 	// ok, 5 items from the first batch are still in the 1-hour window;
 	// we should overwrite until only those 5 are left, then start expanding
 	// the buffer so that it retains those 5 and the 100 new items
-	items = buf.Latest(0)
+	items = buf.latest(0)
 	assertEqual(len(items), 105, t)
 	assertEqual(atoi(items[0].Nick), 67, t)
 	assertEqual(atoi(items[len(items)-1].Nick), 171, t)
@@ -207,7 +206,7 @@ func TestAutoresize(t *testing.T) {
 		id += 1
 	}
 	// should fill up to the maximum size of 128 and start overwriting
-	items = buf.Latest(0)
+	items = buf.latest(0)
 	assertEqual(len(items), 128, t)
 	assertEqual(atoi(items[0].Nick), 144, t)
 	assertEqual(atoi(items[len(items)-1].Nick), 271, t)
@@ -222,7 +221,7 @@ func TestEnabledByResize(t *testing.T) {
 	buf.Resize(128, time.Hour)
 	// add an item and test that it is stored and retrievable
 	buf.Add(autoItem(0, now))
-	items := buf.Latest(0)
+	items := buf.latest(0)
 	assertEqual(len(items), 1, t)
 	assertEqual(atoi(items[0].Nick), 0, t)
 }
@@ -232,13 +231,13 @@ func TestDisabledByResize(t *testing.T) {
 	// enabled autoresizing buffer
 	buf := NewHistoryBuffer(128, time.Hour)
 	buf.Add(autoItem(0, now))
-	items := buf.Latest(0)
+	items := buf.latest(0)
 	assertEqual(len(items), 1, t)
 	assertEqual(atoi(items[0].Nick), 0, t)
 
 	// disable as during a rehash, confirm that nothing can be retrieved
 	buf.Resize(0, time.Hour)
-	items = buf.Latest(0)
+	items = buf.latest(0)
 	assertEqual(len(items), 0, t)
 }
 
@@ -252,3 +251,25 @@ func TestRoundUp(t *testing.T) {
 	assertEqual(roundUpToPowerOfTwo(1025), 2048, t)
 	assertEqual(roundUpToPowerOfTwo(269435457), 536870912, t)
 }
+
+func BenchmarkInsert(b *testing.B) {
+	buf := NewHistoryBuffer(1024, 0)
+	b.ResetTimer()
+	for i := 0; i < b.N; i++ {
+		buf.Add(Item{})
+	}
+}
+
+func BenchmarkMatch(b *testing.B) {
+	buf := NewHistoryBuffer(1024, 0)
+	var now time.Time
+	for i := 0; i < 1024; i += 1 {
+		buf.Add(autoItem(i, now))
+		now = now.Add(time.Second)
+	}
+
+	b.ResetTimer()
+	for i := 0; i < b.N; i++ {
+		buf.lookup("512")
+	}
+}

irc/history/queries.go

@@ -0,0 +1,71 @@
+// Copyright (c) 2020 Shivaram Lingamneni <slingamn@cs.stanford.edu>
+// released under the MIT license
+
+package history
+
+import (
+	"time"
+)
+
+// Selector represents a parameter to a CHATHISTORY command;
+// at most one of Msgid or Time may be nonzero
+type Selector struct {
+	Msgid string
+	Time  time.Time
+}
+
+// Sequence is an abstract sequence of history entries that can be queried;
+// it encapsulates restrictions such as registration time cutoffs, or
+// only looking at a single "query buffer" (DMs with a particular correspondent)
+type Sequence interface {
+	Between(start, end Selector, limit int) (results []Item, complete bool, err error)
+	Around(start Selector, limit int) (results []Item, err error)
+}
+
+// This is a bad, slow implementation of CHATHISTORY AROUND using the BETWEEN semantics
+func GenericAround(seq Sequence, start Selector, limit int) (results []Item, err error) {
+	var halfLimit int
+	halfLimit = (limit + 1) / 2
+	initialResults, _, err := seq.Between(Selector{}, start, halfLimit)
+	if err != nil {
+		return
+	} else if len(initialResults) == 0 {
+		// TODO: this fails if we're doing an AROUND on the first message in the buffer
+		// would be nice to fix this but whatever
+		return
+	}
+	newStart := Selector{Time: initialResults[0].Message.Time}
+	results, _, err = seq.Between(newStart, Selector{}, limit)
+	return
+}
+
+// MinMaxAsc converts CHATHISTORY arguments into time intervals, handling the most
+// general case (BETWEEN going forwards or backwards) natively and the other ordering
+// queries (AFTER, BEFORE, LATEST) as special cases.
+func MinMaxAsc(after, before, cutoff time.Time) (min, max time.Time, ascending bool) {
+	startIsZero, endIsZero := after.IsZero(), before.IsZero()
+	if !startIsZero && endIsZero {
+		// AFTER
+		ascending = true
+	} else if startIsZero && !endIsZero {
+		// BEFORE
+		ascending = false
+	} else if !startIsZero && !endIsZero {
+		if before.Before(after) {
+			// BETWEEN going backwards
+			before, after = after, before
+			ascending = false
+		} else {
+			// BETWEEN going forwards
+			ascending = true
+		}
+	} else if startIsZero && endIsZero {
+		// LATEST
+		ascending = false
+	}
+	if after.IsZero() || after.Before(cutoff) {
+		// this may result in an impossible query, which is fine
+		after = cutoff
+	}
+	return after, before, ascending
+}

irc/hostserv.go

@@ -7,6 +7,7 @@ import (
 	"errors"
 	"fmt"
 	"regexp"
+	"time"
 
 	"github.com/oragono/oragono/irc/sno"
 )
@@ -214,7 +215,7 @@ func hsRequestHandler(server *Server, client *Client, command string, params []s
 	}
 
 	accountName := client.Account()
-	_, err := server.accounts.VHostRequest(accountName, vhost, server.Config().Accounts.VHosts.UserRequests.Cooldown)
+	_, err := server.accounts.VHostRequest(accountName, vhost, time.Duration(server.Config().Accounts.VHosts.UserRequests.Cooldown))
 	if err != nil {
 		if throttled, ok := err.(*vhostThrottleExceeded); ok {
 			hsNotice(rb, fmt.Sprintf(client.t("You must wait an additional %v before making another request"), throttled.timeRemaining))
@@ -411,7 +412,7 @@ func hsTakeHandler(server *Server, client *Client, command string, params []stri
 	}
 
 	account := client.Account()
-	_, err := server.accounts.VHostTake(account, vhost, config.Accounts.VHosts.UserRequests.Cooldown)
+	_, err := server.accounts.VHostTake(account, vhost, time.Duration(config.Accounts.VHosts.UserRequests.Cooldown))
 	if err != nil {
 		if throttled, ok := err.(*vhostThrottleExceeded); ok {
 			hsNotice(rb, fmt.Sprintf(client.t("You must wait an additional %v before taking a vhost"), throttled.timeRemaining))

irc/idletimer.go

@@ -52,6 +52,7 @@ type IdleTimer struct {
 	quitTimeout time.Duration
 	state       TimerState
 	timer       *time.Timer
+	lastTouch   time.Time
 }
 
 // Initialize sets up an IdleTimer and starts counting idle time;
@@ -61,9 +62,11 @@ func (it *IdleTimer) Initialize(session *Session) {
 	it.registerTimeout = RegisterTimeout
 	it.idleTimeout, it.quitTimeout = it.recomputeDurations()
 	registered := session.client.Registered()
+	now := time.Now().UTC()
 
 	it.Lock()
 	defer it.Unlock()
+	it.lastTouch = now
 	if registered {
 		it.state = TimerActive
 	} else {
@@ -82,7 +85,7 @@ func (it *IdleTimer) recomputeDurations() (idleTimeout, quitTimeout time.Duratio
 	}
 
 	idleTimeout = DefaultIdleTimeout
-	if it.session.client.isTor {
+	if it.session.isTor {
 		idleTimeout = TorIdleTimeout
 	}
 
@@ -92,10 +95,12 @@ func (it *IdleTimer) recomputeDurations() (idleTimeout, quitTimeout time.Duratio
 
 func (it *IdleTimer) Touch() {
 	idleTimeout, quitTimeout := it.recomputeDurations()
+	now := time.Now().UTC()
 
 	it.Lock()
 	defer it.Unlock()
 	it.idleTimeout, it.quitTimeout = idleTimeout, quitTimeout
+	it.lastTouch = now
 	// a touch transitions TimerUnregistered or TimerIdle into TimerActive
 	if it.state != TimerDead {
 		it.state = TimerActive
@@ -103,6 +108,13 @@ func (it *IdleTimer) Touch() {
 	}
 }
 
+func (it *IdleTimer) LastTouch() (result time.Time) {
+	it.Lock()
+	result = it.lastTouch
+	it.Unlock()
+	return
+}
+
 func (it *IdleTimer) processTimeout() {
 	idleTimeout, quitTimeout := it.recomputeDurations()
 
@@ -322,9 +334,6 @@ const (
 	// BrbDead is the state of a client after its timeout has expired; it will be removed
 	// and therefore new sessions cannot be attached to it
 	BrbDead
-	// BrbSticky allows a client to remain online without sessions, with no timeout.
-	// This is not used yet.
-	BrbSticky
 )
 
 type BrbTimer struct {
@@ -345,16 +354,16 @@ func (bt *BrbTimer) Initialize(client *Client) {
 
 // attempts to enable BRB for a client, returns whether it succeeded
 func (bt *BrbTimer) Enable() (success bool, duration time.Duration) {
-	if !bt.client.Registered() || bt.client.ResumeID() == "" {
-		return
-	}
-
 	// TODO make this configurable
 	duration = ResumeableTotalTimeout
 
 	bt.client.stateMutex.Lock()
 	defer bt.client.stateMutex.Unlock()
 
+	if !bt.client.registered || bt.client.alwaysOn || bt.client.resumeID == "" {
+		return
+	}
+
 	switch bt.state {
 	case BrbDisabled, BrbEnabled:
 		bt.state = BrbEnabled
@@ -366,8 +375,6 @@ func (bt *BrbTimer) Enable() (success bool, duration time.Duration) {
 			bt.brbAt = time.Now().UTC()
 		}
 		success = true
-	case BrbSticky:
-		success = true
 	default:
 		// BrbDead
 		success = false
@@ -416,6 +423,10 @@ func (bt *BrbTimer) processTimeout() {
 	bt.client.stateMutex.Lock()
 	defer bt.client.stateMutex.Unlock()
 
+	if bt.client.alwaysOn {
+		return
+	}
+
 	switch bt.state {
 	case BrbDisabled, BrbEnabled:
 		if len(bt.client.sessions) == 0 {
@@ -432,16 +443,3 @@ func (bt *BrbTimer) processTimeout() {
 	}
 	bt.resetTimeout()
 }
-
-// sets a client to be "sticky", i.e., indefinitely exempt from removal for
-// lack of sessions
-func (bt *BrbTimer) SetSticky() (success bool) {
-	bt.client.stateMutex.Lock()
-	defer bt.client.stateMutex.Unlock()
-	if bt.state != BrbDead {
-		success = true
-		bt.state = BrbSticky
-	}
-	bt.resetTimeout()
-	return
-}

irc/misc_test.go

@@ -9,9 +9,9 @@ import (
 )
 
 func TestZncTimestampParser(t *testing.T) {
-	assertEqual(zncWireTimeToTime("1558338348.988"), time.Unix(1558338348, 988000000), t)
-	assertEqual(zncWireTimeToTime("1558338348.9"), time.Unix(1558338348, 900000000), t)
-	assertEqual(zncWireTimeToTime("1558338348"), time.Unix(1558338348, 0), t)
-	assertEqual(zncWireTimeToTime(".988"), time.Unix(0, 988000000), t)
-	assertEqual(zncWireTimeToTime("garbage"), time.Unix(0, 0), t)
+	assertEqual(zncWireTimeToTime("1558338348.988"), time.Unix(1558338348, 988000000).UTC(), t)
+	assertEqual(zncWireTimeToTime("1558338348.9"), time.Unix(1558338348, 900000000).UTC(), t)
+	assertEqual(zncWireTimeToTime("1558338348"), time.Unix(1558338348, 0).UTC(), t)
+	assertEqual(zncWireTimeToTime(".988"), time.Unix(0, 988000000).UTC(), t)
+	assertEqual(zncWireTimeToTime("garbage"), time.Unix(0, 0).UTC(), t)
 }

irc/mysql/config.go

@@ -0,0 +1,22 @@
+// Copyright (c) 2020 Shivaram Lingamneni
+// released under the MIT license
+
+package mysql
+
+import (
+	"time"
+)
+
+type Config struct {
+	// these are intended to be written directly into the config file:
+	Enabled         bool
+	Host            string
+	Port            int
+	User            string
+	Password        string
+	HistoryDatabase string `yaml:"history-database"`
+	Timeout         time.Duration
+
+	// XXX these are copied from elsewhere in the config:
+	ExpireTime time.Duration
+}

irc/mysql/history.go

@@ -0,0 +1,557 @@
+// Copyright (c) 2020 Shivaram Lingamneni
+// released under the MIT license
+
+package mysql
+
+import (
+	"bytes"
+	"context"
+	"database/sql"
+	"fmt"
+	"runtime/debug"
+	"sync"
+	"sync/atomic"
+	"time"
+
+	_ "github.com/go-sql-driver/mysql"
+	"github.com/oragono/oragono/irc/history"
+	"github.com/oragono/oragono/irc/logger"
+	"github.com/oragono/oragono/irc/utils"
+)
+
+const (
+	// maximum length in bytes of any message target (nickname or channel name) in its
+	// canonicalized (i.e., casefolded) state:
+	MaxTargetLength = 64
+
+	// latest schema of the db
+	latestDbSchema   = "1"
+	keySchemaVersion = "db.version"
+	cleanupRowLimit  = 50
+	cleanupPauseTime = 10 * time.Minute
+)
+
+type MySQL struct {
+	timeout int64
+	db      *sql.DB
+	logger  *logger.Manager
+
+	insertHistory      *sql.Stmt
+	insertSequence     *sql.Stmt
+	insertConversation *sql.Stmt
+
+	stateMutex sync.Mutex
+	config     Config
+}
+
+func (mysql *MySQL) Initialize(logger *logger.Manager, config Config) {
+	mysql.logger = logger
+	mysql.SetConfig(config)
+}
+
+func (mysql *MySQL) SetConfig(config Config) {
+	atomic.StoreInt64(&mysql.timeout, int64(config.Timeout))
+	mysql.stateMutex.Lock()
+	mysql.config = config
+	mysql.stateMutex.Unlock()
+}
+
+func (mysql *MySQL) getExpireTime() (expireTime time.Duration) {
+	mysql.stateMutex.Lock()
+	expireTime = mysql.config.ExpireTime
+	mysql.stateMutex.Unlock()
+	return
+}
+
+func (m *MySQL) Open() (err error) {
+	var address string
+	if m.config.Port != 0 {
+		address = fmt.Sprintf("tcp(%s:%d)", m.config.Host, m.config.Port)
+	}
+
+	m.db, err = sql.Open("mysql", fmt.Sprintf("%s:%s@%s/%s", m.config.User, m.config.Password, address, m.config.HistoryDatabase))
+	if err != nil {
+		return err
+	}
+
+	err = m.fixSchemas()
+	if err != nil {
+		return err
+	}
+
+	err = m.prepareStatements()
+	if err != nil {
+		return err
+	}
+
+	go m.cleanupLoop()
+
+	return nil
+}
+
+func (mysql *MySQL) fixSchemas() (err error) {
+	_, err = mysql.db.Exec(`CREATE TABLE IF NOT EXISTS metadata (
+		key_name VARCHAR(32) primary key,
+		value VARCHAR(32) NOT NULL
+	) CHARSET=ascii COLLATE=ascii_bin;`)
+	if err != nil {
+		return err
+	}
+
+	var schema string
+	err = mysql.db.QueryRow(`select value from metadata where key_name = ?;`, keySchemaVersion).Scan(&schema)
+	if err == sql.ErrNoRows {
+		err = mysql.createTables()
+		if err != nil {
+			return
+		}
+		_, err = mysql.db.Exec(`insert into metadata (key_name, value) values (?, ?);`, keySchemaVersion, latestDbSchema)
+		if err != nil {
+			return
+		}
+	} else if err == nil && schema != latestDbSchema {
+		// TODO figure out what to do about schema changes
+		return &utils.IncompatibleSchemaError{CurrentVersion: schema, RequiredVersion: latestDbSchema}
+	} else {
+		return err
+	}
+
+	return nil
+}
+
+func (mysql *MySQL) createTables() (err error) {
+	_, err = mysql.db.Exec(`CREATE TABLE history (
+		id BIGINT UNSIGNED NOT NULL AUTO_INCREMENT PRIMARY KEY,
+		data BLOB NOT NULL,
+		msgid BINARY(16) NOT NULL,
+		KEY (msgid(4))
+	) CHARSET=ascii COLLATE=ascii_bin;`)
+	if err != nil {
+		return err
+	}
+
+	_, err = mysql.db.Exec(fmt.Sprintf(`CREATE TABLE sequence (
+		id BIGINT UNSIGNED NOT NULL AUTO_INCREMENT PRIMARY KEY,
+		target VARBINARY(%[1]d) NOT NULL,
+		nanotime BIGINT UNSIGNED NOT NULL,
+		history_id BIGINT NOT NULL,
+		KEY (target, nanotime),
+		KEY (history_id)
+	) CHARSET=ascii COLLATE=ascii_bin;`, MaxTargetLength))
+	if err != nil {
+		return err
+	}
+
+	_, err = mysql.db.Exec(fmt.Sprintf(`CREATE TABLE conversations (
+		id BIGINT UNSIGNED NOT NULL AUTO_INCREMENT PRIMARY KEY,
+		lower_target VARBINARY(%[1]d) NOT NULL,
+		upper_target VARBINARY(%[1]d) NOT NULL,
+		nanotime BIGINT UNSIGNED NOT NULL,
+		history_id BIGINT NOT NULL,
+		KEY (lower_target, upper_target, nanotime),
+		KEY (history_id)
+	) CHARSET=ascii COLLATE=ascii_bin;`, MaxTargetLength))
+	if err != nil {
+		return err
+	}
+
+	return nil
+}
+
+func (mysql *MySQL) cleanupLoop() {
+	defer func() {
+		if r := recover(); r != nil {
+			mysql.logger.Error("mysql",
+				fmt.Sprintf("Panic in cleanup routine: %v\n%s", r, debug.Stack()))
+			time.Sleep(cleanupPauseTime)
+			go mysql.cleanupLoop()
+		}
+	}()
+
+	for {
+		expireTime := mysql.getExpireTime()
+		if expireTime != 0 {
+			for {
+				startTime := time.Now()
+				rowsDeleted, err := mysql.doCleanup(expireTime)
+				elapsed := time.Now().Sub(startTime)
+				mysql.logError("error during row cleanup", err)
+				// keep going as long as we're accomplishing significant work
+				// (don't busy-wait on small numbers of rows expiring):
+				if rowsDeleted < (cleanupRowLimit / 10) {
+					break
+				}
+				// crude backpressure mechanism: if the database is slow,
+				// give it time to process other queries
+				time.Sleep(elapsed)
+			}
+		}
+		time.Sleep(cleanupPauseTime)
+	}
+}
+
+func (mysql *MySQL) doCleanup(age time.Duration) (count int, err error) {
+	ids, maxNanotime, err := mysql.selectCleanupIDs(age)
+	if len(ids) == 0 {
+		mysql.logger.Debug("mysql", "found no rows to clean up")
+		return
+	}
+
+	mysql.logger.Debug("mysql", fmt.Sprintf("deleting %d history rows, max age %s", len(ids), utils.NanoToTimestamp(maxNanotime)))
+
+	// can't use ? binding for a variable number of arguments, build the IN clause manually
+	var inBuf bytes.Buffer
+	inBuf.WriteByte('(')
+	for i, id := range ids {
+		if i != 0 {
+			inBuf.WriteRune(',')
+		}
+		fmt.Fprintf(&inBuf, "%d", id)
+	}
+	inBuf.WriteRune(')')
+
+	_, err = mysql.db.Exec(fmt.Sprintf(`DELETE FROM conversations WHERE history_id in %s;`, inBuf.Bytes()))
+	if err != nil {
+		return
+	}
+	_, err = mysql.db.Exec(fmt.Sprintf(`DELETE FROM sequence WHERE history_id in %s;`, inBuf.Bytes()))
+	if err != nil {
+		return
+	}
+	_, err = mysql.db.Exec(fmt.Sprintf(`DELETE FROM history WHERE id in %s;`, inBuf.Bytes()))
+	if err != nil {
+		return
+	}
+
+	count = len(ids)
+	return
+}
+
+func (mysql *MySQL) selectCleanupIDs(age time.Duration) (ids []uint64, maxNanotime int64, err error) {
+	rows, err := mysql.db.Query(`
+		SELECT history.id, sequence.nanotime
+		FROM history
+		LEFT JOIN sequence ON history.id = sequence.history_id
+		ORDER BY history.id LIMIT ?;`, cleanupRowLimit)
+	if err != nil {
+		return
+	}
+	defer rows.Close()
+
+	// a history ID may have 0-2 rows in sequence: 1 for a channel entry,
+	// 2 for a DM, 0 if the data is inconsistent. therefore, deduplicate
+	// and delete anything that doesn't have a sequence entry:
+	idset := make(map[uint64]struct{}, cleanupRowLimit)
+	threshold := time.Now().Add(-age).UnixNano()
+	for rows.Next() {
+		var id uint64
+		var nanotime sql.NullInt64
+		err = rows.Scan(&id, &nanotime)
+		if err != nil {
+			return
+		}
+		if !nanotime.Valid || nanotime.Int64 < threshold {
+			idset[id] = struct{}{}
+			if nanotime.Valid && nanotime.Int64 > maxNanotime {
+				maxNanotime = nanotime.Int64
+			}
+		}
+	}
+	ids = make([]uint64, len(idset))
+	i := 0
+	for id := range idset {
+		ids[i] = id
+		i++
+	}
+	return
+}
+
+func (mysql *MySQL) prepareStatements() (err error) {
+	mysql.insertHistory, err = mysql.db.Prepare(`INSERT INTO history
+		(data, msgid) VALUES (?, ?);`)
+	if err != nil {
+		return
+	}
+	mysql.insertSequence, err = mysql.db.Prepare(`INSERT INTO sequence
+		(target, nanotime, history_id) VALUES (?, ?, ?);`)
+	if err != nil {
+		return
+	}
+	mysql.insertConversation, err = mysql.db.Prepare(`INSERT INTO conversations
+		(lower_target, upper_target, nanotime, history_id) VALUES (?, ?, ?, ?);`)
+	if err != nil {
+		return
+	}
+
+	return
+}
+
+func (mysql *MySQL) getTimeout() time.Duration {
+	return time.Duration(atomic.LoadInt64(&mysql.timeout))
+}
+
+func (mysql *MySQL) logError(context string, err error) (quit bool) {
+	if err != nil {
+		mysql.logger.Error("mysql", context, err.Error())
+		return true
+	}
+	return false
+}
+
+func (mysql *MySQL) AddChannelItem(target string, item history.Item) (err error) {
+	if mysql.db == nil {
+		return
+	}
+
+	if target == "" {
+		return utils.ErrInvalidParams
+	}
+
+	ctx, cancel := context.WithTimeout(context.Background(), mysql.getTimeout())
+	defer cancel()
+
+	id, err := mysql.insertBase(ctx, item)
+	if err != nil {
+		return
+	}
+
+	err = mysql.insertSequenceEntry(ctx, target, item.Message.Time, id)
+	return
+}
+
+func (mysql *MySQL) insertSequenceEntry(ctx context.Context, target string, messageTime time.Time, id int64) (err error) {
+	_, err = mysql.insertSequence.ExecContext(ctx, target, messageTime.UnixNano(), id)
+	mysql.logError("could not insert sequence entry", err)
+	return
+}
+
+func (mysql *MySQL) insertConversationEntry(ctx context.Context, sender, recipient string, messageTime time.Time, id int64) (err error) {
+	lower, higher := stringMinMax(sender, recipient)
+	_, err = mysql.insertConversation.ExecContext(ctx, lower, higher, messageTime.UnixNano(), id)
+	mysql.logError("could not insert conversations entry", err)
+	return
+}
+
+func (mysql *MySQL) insertBase(ctx context.Context, item history.Item) (id int64, err error) {
+	value, err := marshalItem(&item)
+	if mysql.logError("could not marshal item", err) {
+		return
+	}
+
+	msgidBytes, err := decodeMsgid(item.Message.Msgid)
+	if mysql.logError("could not decode msgid", err) {
+		return
+	}
+
+	result, err := mysql.insertHistory.ExecContext(ctx, value, msgidBytes)
+	if mysql.logError("could not insert item", err) {
+		return
+	}
+	id, err = result.LastInsertId()
+	if mysql.logError("could not insert item", err) {
+		return
+	}
+
+	return
+}
+
+func stringMinMax(first, second string) (min, max string) {
+	if first < second {
+		return first, second
+	} else {
+		return second, first
+	}
+}
+
+func (mysql *MySQL) AddDirectMessage(sender, recipient string, senderPersistent, recipientPersistent bool, item history.Item) (err error) {
+	if mysql.db == nil {
+		return
+	}
+
+	if !(senderPersistent || recipientPersistent) {
+		return
+	}
+
+	if sender == "" || recipient == "" {
+		return utils.ErrInvalidParams
+	}
+
+	ctx, cancel := context.WithTimeout(context.Background(), mysql.getTimeout())
+	defer cancel()
+
+	id, err := mysql.insertBase(ctx, item)
+	if err != nil {
+		return
+	}
+
+	if senderPersistent {
+		mysql.insertSequenceEntry(ctx, sender, item.Message.Time, id)
+		if err != nil {
+			return
+		}
+	}
+
+	if recipientPersistent && sender != recipient {
+		err = mysql.insertSequenceEntry(ctx, recipient, item.Message.Time, id)
+		if err != nil {
+			return
+		}
+	}
+
+	err = mysql.insertConversationEntry(ctx, sender, recipient, item.Message.Time, id)
+
+	return
+}
+
+func (mysql *MySQL) msgidToTime(ctx context.Context, msgid string) (result time.Time, err error) {
+	// in theory, we could optimize out a roundtrip to the database by using a subquery instead:
+	// sequence.nanotime > (
+	//     SELECT sequence.nanotime FROM sequence, history
+	//     WHERE sequence.history_id = history.id AND history.msgid = ?
+	//     LIMIT 1)
+	// however, this doesn't handle the BETWEEN case with one or two msgids, where we
+	// don't initially know whether the interval is going forwards or backwards. to simplify
+	// the logic,  resolve msgids to timestamps "manually" in all cases, using a separate query.
+	decoded, err := decodeMsgid(msgid)
+	if err != nil {
+		return
+	}
+	row := mysql.db.QueryRowContext(ctx, `
+		SELECT sequence.nanotime FROM sequence
+		INNER JOIN history ON history.id = sequence.history_id
+		WHERE history.msgid = ? LIMIT 1;`, decoded)
+	var nanotime int64
+	err = row.Scan(&nanotime)
+	if mysql.logError("could not resolve msgid to time", err) {
+		return
+	}
+	result = time.Unix(0, nanotime).UTC()
+	return
+}
+
+func (mysql *MySQL) selectItems(ctx context.Context, query string, args ...interface{}) (results []history.Item, err error) {
+	rows, err := mysql.db.QueryContext(ctx, query, args...)
+	if mysql.logError("could not select history items", err) {
+		return
+	}
+
+	defer rows.Close()
+
+	for rows.Next() {
+		var blob []byte
+		var item history.Item
+		err = rows.Scan(&blob)
+		if mysql.logError("could not scan history item", err) {
+			return
+		}
+		err = unmarshalItem(blob, &item)
+		if mysql.logError("could not unmarshal history item", err) {
+			return
+		}
+		results = append(results, item)
+	}
+	return
+}
+
+func (mysql *MySQL) betweenTimestamps(ctx context.Context, sender, recipient string, after, before, cutoff time.Time, limit int) (results []history.Item, err error) {
+	useSequence := true
+	var lowerTarget, upperTarget string
+	if sender != "" {
+		lowerTarget, upperTarget = stringMinMax(sender, recipient)
+		useSequence = false
+	}
+
+	table := "sequence"
+	if !useSequence {
+		table = "conversations"
+	}
+
+	after, before, ascending := history.MinMaxAsc(after, before, cutoff)
+	direction := "ASC"
+	if !ascending {
+		direction = "DESC"
+	}
+
+	var queryBuf bytes.Buffer
+
+	args := make([]interface{}, 0, 6)
+	fmt.Fprintf(&queryBuf,
+		"SELECT history.data from history INNER JOIN %[1]s ON history.id = %[1]s.history_id WHERE", table)
+	if useSequence {
+		fmt.Fprintf(&queryBuf, " sequence.target = ?")
+		args = append(args, recipient)
+	} else {
+		fmt.Fprintf(&queryBuf, " conversations.lower_target = ? AND conversations.upper_target = ?")
+		args = append(args, lowerTarget)
+		args = append(args, upperTarget)
+	}
+	if !after.IsZero() {
+		fmt.Fprintf(&queryBuf, " AND %s.nanotime > ?", table)
+		args = append(args, after.UnixNano())
+	}
+	if !before.IsZero() {
+		fmt.Fprintf(&queryBuf, " AND %s.nanotime < ?", table)
+		args = append(args, before.UnixNano())
+	}
+	fmt.Fprintf(&queryBuf, " ORDER BY %[1]s.nanotime %[2]s LIMIT ?;", table, direction)
+	args = append(args, limit)
+
+	results, err = mysql.selectItems(ctx, queryBuf.String(), args...)
+	if err == nil && !ascending {
+		history.Reverse(results)
+	}
+	return
+}
+
+func (mysql *MySQL) Close() {
+	// closing the database will close our prepared statements as well
+	if mysql.db != nil {
+		mysql.db.Close()
+	}
+	mysql.db = nil
+}
+
+// implements history.Sequence, emulating a single history buffer (for a channel,
+// a single user's DMs, or a DM conversation)
+type mySQLHistorySequence struct {
+	mysql     *MySQL
+	sender    string
+	recipient string
+	cutoff    time.Time
+}
+
+func (s *mySQLHistorySequence) Between(start, end history.Selector, limit int) (results []history.Item, complete bool, err error) {
+	ctx, cancel := context.WithTimeout(context.Background(), s.mysql.getTimeout())
+	defer cancel()
+
+	startTime := start.Time
+	if start.Msgid != "" {
+		startTime, err = s.mysql.msgidToTime(ctx, start.Msgid)
+		if err != nil {
+			return nil, false, err
+		}
+	}
+	endTime := end.Time
+	if end.Msgid != "" {
+		endTime, err = s.mysql.msgidToTime(ctx, end.Msgid)
+		if err != nil {
+			return nil, false, err
+		}
+	}
+
+	results, err = s.mysql.betweenTimestamps(ctx, s.sender, s.recipient, startTime, endTime, s.cutoff, limit)
+	return results, (err == nil), err
+}
+
+func (s *mySQLHistorySequence) Around(start history.Selector, limit int) (results []history.Item, err error) {
+	return history.GenericAround(s, start, limit)
+}
+
+func (mysql *MySQL) MakeSequence(sender, recipient string, cutoff time.Time) history.Sequence {
+	return &mySQLHistorySequence{
+		sender:    sender,
+		recipient: recipient,
+		mysql:     mysql,
+		cutoff:    cutoff,
+	}
+}

irc/mysql/serialization.go

@@ -0,0 +1,23 @@
+package mysql
+
+import (
+	"encoding/json"
+
+	"github.com/oragono/oragono/irc/history"
+	"github.com/oragono/oragono/irc/utils"
+)
+
+// 123 / '{' is the magic number that means JSON;
+// if we want to do a binary encoding later, we just have to add different magic version numbers
+
+func marshalItem(item *history.Item) (result []byte, err error) {
+	return json.Marshal(item)
+}
+
+func unmarshalItem(data []byte, result *history.Item) (err error) {
+	return json.Unmarshal(data, result)
+}
+
+func decodeMsgid(msgid string) ([]byte, error) {
+	return utils.B32Encoder.DecodeString(msgid)
+}

irc/nickname.go

@@ -43,13 +43,15 @@ func performNickChange(server *Server, client *Client, target *Client, session *
 	hadNick := target.HasNick()
 	origNickMask := target.NickMaskString()
 	details := target.Details()
-	err := client.server.clients.SetNick(target, session, nickname)
+	assignedNickname, err := client.server.clients.SetNick(target, session, nickname)
 	if err == errNicknameInUse {
 		rb.Add(nil, server.name, ERR_NICKNAMEINUSE, currentNick, nickname, client.t("Nickname is already in use"))
 	} else if err == errNicknameReserved {
 		rb.Add(nil, server.name, ERR_NICKNAMEINUSE, currentNick, nickname, client.t("Nickname is reserved by a different account"))
 	} else if err == errNicknameInvalid {
 		rb.Add(nil, server.name, ERR_ERRONEUSNICKNAME, currentNick, utils.SafeErrorParam(nickname), client.t("Erroneous nickname"))
+	} else if err == errCantChangeNick {
+		rb.Add(nil, server.name, ERR_NICKNAMEINUSE, currentNick, utils.SafeErrorParam(nickname), client.t(err.Error()))
 	} else if err != nil {
 		rb.Add(nil, server.name, ERR_UNKNOWNERROR, currentNick, "NICK", fmt.Sprintf(client.t("Could not set or change nickname: %s"), err.Error()))
 	}
@@ -64,26 +66,26 @@ func performNickChange(server *Server, client *Client, target *Client, session *
 		AccountName: details.accountName,
 		Message:     message,
 	}
-	histItem.Params[0] = nickname
+	histItem.Params[0] = assignedNickname
 
-	client.server.logger.Debug("nick", fmt.Sprintf("%s changed nickname to %s [%s]", origNickMask, nickname, client.NickCasefolded()))
+	client.server.logger.Debug("nick", fmt.Sprintf("%s changed nickname to %s [%s]", origNickMask, assignedNickname, client.NickCasefolded()))
 	if hadNick {
 		if client == target {
-			target.server.snomasks.Send(sno.LocalNicks, fmt.Sprintf(ircfmt.Unescape("$%s$r changed nickname to %s"), details.nick, nickname))
+			target.server.snomasks.Send(sno.LocalNicks, fmt.Sprintf(ircfmt.Unescape("$%s$r changed nickname to %s"), details.nick, assignedNickname))
 		} else {
-			target.server.snomasks.Send(sno.LocalNicks, fmt.Sprintf(ircfmt.Unescape("Operator %s changed nickname of $%s$r to %s"), client.Nick(), details.nick, nickname))
+			target.server.snomasks.Send(sno.LocalNicks, fmt.Sprintf(ircfmt.Unescape("Operator %s changed nickname of $%s$r to %s"), client.Nick(), details.nick, assignedNickname))
 		}
 		target.server.whoWas.Append(details.WhoWas)
-		rb.AddFromClient(message.Time, message.Msgid, origNickMask, details.accountName, nil, "NICK", nickname)
+		rb.AddFromClient(message.Time, message.Msgid, origNickMask, details.accountName, nil, "NICK", assignedNickname)
 		for session := range target.Friends() {
 			if session != rb.session {
-				session.sendFromClientInternal(false, message.Time, message.Msgid, origNickMask, details.accountName, nil, "NICK", nickname)
+				session.sendFromClientInternal(false, message.Time, message.Msgid, origNickMask, details.accountName, nil, "NICK", assignedNickname)
 			}
 		}
 	}
 
 	for _, channel := range client.Channels() {
-		channel.history.Add(histItem)
+		channel.AddHistoryItem(histItem)
 	}
 
 	if target.Registered() {

irc/nickserv.go

@@ -31,7 +31,7 @@ func servCmdRequiresNickRes(config *Config) bool {
 }
 
 func servCmdRequiresBouncerEnabled(config *Config) bool {
-	return config.Accounts.Bouncer.Enabled
+	return config.Accounts.Multiclient.Enabled
 }
 
 const (
@@ -147,7 +147,7 @@ an administrator can set use this command to set up user accounts.`,
 			help: `Syntax: $bSESSIONS [nickname]$b
 
 SESSIONS lists information about the sessions currently attached, via
-the server's bouncer functionality, to your nickname. An administrator
+the server's multiclient functionality, to your nickname. An administrator
 can use this command to list another user's sessions.`,
 			helpShort: `$bSESSIONS$b lists the sessions attached to a nickname.`,
 			enabled:   servCmdRequiresBouncerEnabled,
@@ -217,7 +217,7 @@ information on the settings and their possible values, see HELP SET.`,
 			helpStrings: []string{
 				`Syntax $bSET <setting> <value>$b
 
-Set modifies your account settings. The following settings are available:`,
+SET modifies your account settings. The following settings are available:`,
 
 				`$bENFORCE$b
 'enforce' lets you specify a custom enforcement mechanism for your registered
@@ -228,8 +228,8 @@ nicknames. Your options are:
 3. 'strict'  [you must already be authenticated to use the nick]
 4. 'default' [use the server default]`,
 
-				`$bBOUNCER$b
-If 'bouncer' is enabled and you are already logged in and using a nick, a
+				`$bMULTICLIENT$b
+If 'multiclient' is enabled and you are already logged in and using a nick, a
 second client of yours that authenticates with SASL and requests the same nick
 is allowed to attach to the nick as well (this is comparable to the behavior
 of IRC "bouncers" like ZNC). Your options are 'on' (allow this behavior),
@@ -247,6 +247,22 @@ lines for join and part. This provides more information about the context of
 messages, but may be spammy. Your options are 'always', 'never', and the default
 of 'commands-only' (the messages will be replayed in /HISTORY output, but not
 during autoreplay).`,
+				`$bALWAYS-ON$b
+'always-on' controls whether your nickname/identity will remain active
+even while you are disconnected from the server. Your options are 'true',
+'false', and 'default' (use the server default value).`,
+				`$bAUTOREPLAY-MISSED$b
+'autoreplay-missed' is only effective for always-on clients. If enabled,
+if you have at most one active session, the server will remember the time
+you disconnect and then replay missed messages to you when you reconnect.
+Your options are 'on' and 'off'.`,
+				`$bDM-HISTORY$b
+'dm-history' is only effective for always-on clients. It lets you control
+how the history of your direct messages is stored. Your options are:
+1. 'off'        [no history]
+2. 'ephemeral'  [a limited amount of temporary history, not stored on disk]
+3. 'on'         [history stored in a permanent database, if available]
+4. 'default'    [use the server default]`,
 			},
 			authRequired: true,
 			enabled:      servCmdRequiresAccreg,
@@ -332,23 +348,48 @@ func displaySetting(settingName string, settings AccountSettings, client *Client
 		case ReplayJoinsNever:
 			nsNotice(rb, client.t("You will not see JOINs and PARTs in /HISTORY output or in autoreplay"))
 		}
-	case "bouncer":
-		if !config.Accounts.Bouncer.Enabled {
+	case "multiclient":
+		if !config.Accounts.Multiclient.Enabled {
 			nsNotice(rb, client.t("This feature has been disabled by the server administrators"))
 		} else {
 			switch settings.AllowBouncer {
-			case BouncerAllowedServerDefault:
-				if config.Accounts.Bouncer.AllowedByDefault {
-					nsNotice(rb, client.t("Bouncer functionality is currently enabled for your account, but you can opt out"))
+			case MulticlientAllowedServerDefault:
+				if config.Accounts.Multiclient.AllowedByDefault {
+					nsNotice(rb, client.t("Multiclient functionality is currently enabled for your account, but you can opt out"))
 				} else {
-					nsNotice(rb, client.t("Bouncer functionality is currently disabled for your account, but you can opt in"))
+					nsNotice(rb, client.t("Multiclient functionality is currently disabled for your account, but you can opt in"))
 				}
-			case BouncerDisallowedByUser:
-				nsNotice(rb, client.t("Bouncer functionality is currently disabled for your account"))
-			case BouncerAllowedByUser:
-				nsNotice(rb, client.t("Bouncer functionality is currently enabled for your account"))
+			case MulticlientDisallowedByUser:
+				nsNotice(rb, client.t("Multiclient functionality is currently disabled for your account"))
+			case MulticlientAllowedByUser:
+				nsNotice(rb, client.t("Multiclient functionality is currently enabled for your account"))
 			}
 		}
+	case "always-on":
+		stored := settings.AlwaysOn
+		actual := client.AlwaysOn()
+		nsNotice(rb, fmt.Sprintf(client.t("Your stored always-on setting is: %s"), persistentStatusToString(stored)))
+		if actual {
+			nsNotice(rb, client.t("Given current server settings, your client is always-on"))
+		} else {
+			nsNotice(rb, client.t("Given current server settings, your client is not always-on"))
+		}
+	case "autoreplay-missed":
+		stored := settings.AutoreplayMissed
+		if stored {
+			if client.AlwaysOn() {
+				nsNotice(rb, client.t("Autoreplay of missed messages is enabled"))
+			} else {
+				nsNotice(rb, client.t("You have enabled autoreplay of missed messages, but you can't receive them because your client isn't set to always-on"))
+			}
+		} else {
+			nsNotice(rb, client.t("Your account is not configured to receive autoreplayed missed messages"))
+		}
+	case "dm-history":
+		effectiveValue := historyEnabled(config.History.Persistent.DirectMessages, settings.DMHistory)
+		csNotice(rb, fmt.Sprintf(client.t("Your stored direct message history setting is: %s"), historyStatusToString(settings.DMHistory)))
+		csNotice(rb, fmt.Sprintf(client.t("Given current server settings, your direct message history setting is: %s"), historyStatusToString(effectiveValue)))
+
 	default:
 		nsNotice(rb, client.t("No such setting"))
 	}
@@ -399,17 +440,17 @@ func nsSetHandler(server *Server, client *Client, command string, params []strin
 			out.AutoreplayLines = newValue
 			return
 		}
-	case "bouncer":
-		var newValue BouncerAllowedSetting
+	case "multiclient":
+		var newValue MulticlientAllowedSetting
 		if strings.ToLower(params[1]) == "default" {
-			newValue = BouncerAllowedServerDefault
+			newValue = MulticlientAllowedServerDefault
 		} else {
 			var enabled bool
 			enabled, err = utils.StringToBool(params[1])
 			if enabled {
-				newValue = BouncerAllowedByUser
+				newValue = MulticlientAllowedByUser
 			} else {
-				newValue = BouncerDisallowedByUser
+				newValue = MulticlientDisallowedByUser
 			}
 		}
 		if err == nil {
@@ -429,6 +470,37 @@ func nsSetHandler(server *Server, client *Client, command string, params []strin
 				return
 			}
 		}
+	case "always-on":
+		var newValue PersistentStatus
+		newValue, err = persistentStatusFromString(params[1])
+		// "opt-in" and "opt-out" don't make sense as user preferences
+		if err == nil && newValue != PersistentOptIn && newValue != PersistentOptOut {
+			munger = func(in AccountSettings) (out AccountSettings, err error) {
+				out = in
+				out.AlwaysOn = newValue
+				return
+			}
+		}
+	case "autoreplay-missed":
+		var newValue bool
+		newValue, err = utils.StringToBool(params[1])
+		if err == nil {
+			munger = func(in AccountSettings) (out AccountSettings, err error) {
+				out = in
+				out.AutoreplayMissed = newValue
+				return
+			}
+		}
+	case "dm-history":
+		var newValue HistoryStatus
+		newValue, err = historyStatusFromString(params[1])
+		if err == nil {
+			munger = func(in AccountSettings) (out AccountSettings, err error) {
+				out = in
+				out.DMHistory = newValue
+				return
+			}
+		}
 	default:
 		err = errInvalidParams
 	}
@@ -480,6 +552,9 @@ func nsGhostHandler(server *Server, client *Client, command string, params []str
 	} else if ghost == client {
 		nsNotice(rb, client.t("You can't GHOST yourself (try /QUIT instead)"))
 		return
+	} else if ghost.AlwaysOn() {
+		nsNotice(rb, client.t("You can't GHOST an always-on client"))
+		return
 	}
 
 	authorized := false
@@ -530,7 +605,7 @@ func nsIdentifyHandler(server *Server, client *Client, command string, params []
 
 	var username, passphrase string
 	if len(params) == 1 {
-		if client.certfp != "" {
+		if rb.session.certfp != "" {
 			username = params[0]
 		} else {
 			// XXX undocumented compatibility mode with other nickservs, allowing
@@ -553,8 +628,8 @@ func nsIdentifyHandler(server *Server, client *Client, command string, params []
 	}
 
 	// try certfp
-	if !loginSuccessful && client.certfp != "" {
-		err := server.accounts.AuthenticateByCertFP(client, "")
+	if !loginSuccessful && rb.session.certfp != "" {
+		err := server.accounts.AuthenticateByCertFP(client, rb.session.certfp, "")
 		loginSuccessful = (err == nil)
 	}
 
@@ -618,7 +693,7 @@ func nsRegisterHandler(server *Server, client *Client, command string, params []
 		email = params[1]
 	}
 
-	certfp := client.certfp
+	certfp := rb.session.certfp
 	if passphrase == "*" {
 		if certfp == "" {
 			nsNotice(rb, client.t("You must be connected with TLS and a client certificate to do this"))
@@ -658,7 +733,7 @@ func nsRegisterHandler(server *Server, client *Client, command string, params []
 		}
 	}
 
-	err := server.accounts.Register(client, account, callbackNamespace, callbackValue, passphrase, client.certfp)
+	err := server.accounts.Register(client, account, callbackNamespace, callbackValue, passphrase, rb.session.certfp)
 	if err == nil {
 		if callbackNamespace == "*" {
 			err = server.accounts.Verify(client, account, "")
@@ -876,6 +951,9 @@ func nsSessionsHandler(server *Server, client *Client, command string, params []
 		nsNotice(rb, fmt.Sprintf(client.t("Hostname:    %s"), session.hostname))
 		nsNotice(rb, fmt.Sprintf(client.t("Created at:  %s"), session.ctime.Format(time.RFC1123)))
 		nsNotice(rb, fmt.Sprintf(client.t("Last active: %s"), session.atime.Format(time.RFC1123)))
+		if session.certfp != "" {
+			nsNotice(rb, fmt.Sprintf(client.t("Certfp:      %s"), session.certfp))
+		}
 	}
 }
 

irc/responsebuffer.go

@@ -121,7 +121,7 @@ func (rb *ResponseBuffer) AddSplitMessageFromClient(fromNickMask string, fromAcc
 	if message.Is512() {
 		rb.AddFromClient(message.Time, message.Msgid, fromNickMask, fromAccount, tags, command, target, message.Message)
 	} else {
-		if message.IsMultiline() && rb.session.capabilities.Has(caps.Multiline) {
+		if rb.session.capabilities.Has(caps.Multiline) {
 			batch := rb.session.composeMultilineBatch(fromNickMask, fromAccount, tags, command, target, message)
 			rb.setNestedBatchTag(&batch[0])
 			rb.setNestedBatchTag(&batch[len(batch)-1])
@@ -292,5 +292,5 @@ func (rb *ResponseBuffer) flushInternal(final bool, blocking bool) error {
 
 // Notice sends the client the given notice from the server.
 func (rb *ResponseBuffer) Notice(text string) {
-	rb.Add(nil, rb.target.server.name, "NOTICE", rb.target.nick, text)
+	rb.Add(nil, rb.target.server.name, "NOTICE", rb.target.Nick(), text)
 }

irc/server.go

@@ -24,8 +24,10 @@ import (
 	"github.com/goshuirc/irc-go/ircfmt"
 	"github.com/oragono/oragono/irc/caps"
 	"github.com/oragono/oragono/irc/connection_limits"
+	"github.com/oragono/oragono/irc/history"
 	"github.com/oragono/oragono/irc/logger"
 	"github.com/oragono/oragono/irc/modes"
+	"github.com/oragono/oragono/irc/mysql"
 	"github.com/oragono/oragono/irc/sno"
 	"github.com/tidwall/buntdb"
 )
@@ -84,6 +86,7 @@ type Server struct {
 	signals           chan os.Signal
 	snomasks          SnoManager
 	store             *buntdb.DB
+	historyDB         mysql.MySQL
 	torLimiter        connection_limits.TorLimiter
 	whoWas            WhoWasList
 	stats             Stats
@@ -122,7 +125,7 @@ func NewServer(config *Config, logger *logger.Manager) (*Server, error) {
 	server.monitorManager.Initialize()
 	server.snomasks.Initialize()
 
-	if err := server.applyConfig(config, true); err != nil {
+	if err := server.applyConfig(config); err != nil {
 		return nil, err
 	}
 
@@ -143,6 +146,8 @@ func (server *Server) Shutdown() {
 	if err := server.store.Close(); err != nil {
 		server.logger.Error("shutdown", fmt.Sprintln("Could not close datastore:", err))
 	}
+
+	server.historyDB.Close()
 }
 
 // Run starts the server.
@@ -316,7 +321,7 @@ 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())
+	authOutcome := c.isAuthorized(server.Config(), session)
 	var quitMessage string
 	switch authOutcome {
 	case authFailPass:
@@ -376,7 +381,7 @@ func (server *Server) playRegistrationBurst(session *Session) {
 	// continue registration
 	d := c.Details()
 	server.logger.Info("localconnect", fmt.Sprintf("Client connected [%s] [u:%s] [r:%s]", d.nick, d.username, d.realname))
-	server.snomasks.Send(sno.LocalConnects, fmt.Sprintf("Client connected [%s] [u:%s] [h:%s] [ip:%s] [r:%s]", d.nick, d.username, c.RawHostname(), c.IPString(), d.realname))
+	server.snomasks.Send(sno.LocalConnects, fmt.Sprintf("Client connected [%s] [u:%s] [h:%s] [ip:%s] [r:%s]", d.nick, d.username, session.rawHostname, session.IP().String(), d.realname))
 
 	// send welcome text
 	//NOTE(dan): we specifically use the NICK here instead of the nickmask
@@ -503,8 +508,12 @@ func (client *Client) getWhoisOf(target *Client, rb *ResponseBuffer) {
 		rb.Add(nil, client.server.name, RPL_WHOISBOT, cnick, tnick, ircfmt.Unescape(fmt.Sprintf(client.t("is a $bBot$b on %s"), client.server.Config().Network.Name)))
 	}
 
-	if target.certfp != "" && (client.HasMode(modes.Operator) || client == target) {
-		rb.Add(nil, client.server.name, RPL_WHOISCERTFP, cnick, tnick, fmt.Sprintf(client.t("has client certificate fingerprint %s"), target.certfp))
+	if client == target || client.HasMode(modes.Operator) {
+		for _, session := range target.Sessions() {
+			if session.certfp != "" {
+				rb.Add(nil, client.server.name, RPL_WHOISCERTFP, cnick, tnick, fmt.Sprintf(client.t("has client certificate fingerprint %s"), session.certfp))
+			}
+		}
 	}
 	rb.Add(nil, client.server.name, RPL_WHOISIDLE, cnick, tnick, strconv.FormatUint(target.IdleSeconds(), 10), strconv.FormatInt(target.SignonTime(), 10), client.t("seconds idle, signon time"))
 }
@@ -550,7 +559,7 @@ func (server *Server) rehash() error {
 		return fmt.Errorf("Error loading config file config: %s", err.Error())
 	}
 
-	err = server.applyConfig(config, false)
+	err = server.applyConfig(config)
 	if err != nil {
 		return fmt.Errorf("Error applying config changes: %s", err.Error())
 	}
@@ -558,7 +567,10 @@ func (server *Server) rehash() error {
 	return nil
 }
 
-func (server *Server) applyConfig(config *Config, initial bool) (err error) {
+func (server *Server) applyConfig(config *Config) (err error) {
+	oldConfig := server.Config()
+	initial := oldConfig == nil
+
 	if initial {
 		server.configFilename = config.Filename
 		server.name = config.Server.Name
@@ -568,7 +580,7 @@ func (server *Server) applyConfig(config *Config, initial bool) (err error) {
 		// enforce configs that can't be changed after launch:
 		if server.name != config.Server.Name {
 			return fmt.Errorf("Server name cannot be changed after launching the server, rehash aborted")
-		} else if server.Config().Datastore.Path != config.Datastore.Path {
+		} else if oldConfig.Datastore.Path != config.Datastore.Path {
 			return fmt.Errorf("Datastore path cannot be changed after launching the server, rehash aborted")
 		} else if globalCasemappingSetting != config.Server.Casemapping {
 			return fmt.Errorf("Casemapping cannot be changed after launching the server, rehash aborted")
@@ -576,7 +588,6 @@ func (server *Server) applyConfig(config *Config, initial bool) (err error) {
 	}
 
 	server.logger.Info("server", "Using config file", server.configFilename)
-	oldConfig := server.Config()
 
 	// first, reload config sections for functionality implemented in subpackages:
 	wasLoggingRawIO := !initial && server.logger.IsLoggingRawIO()
@@ -609,14 +620,13 @@ func (server *Server) applyConfig(config *Config, initial bool) (err error) {
 		if !oldConfig.Channels.Registration.Enabled {
 			server.channels.loadRegisteredChannels(config)
 		}
-
 		// resize history buffers as needed
 		if oldConfig.History != config.History {
 			for _, channel := range server.channels.Channels() {
-				channel.history.Resize(config.History.ChannelLength, config.History.AutoresizeWindow)
+				channel.resizeHistory(config)
 			}
 			for _, client := range server.clients.AllClients() {
-				client.history.Resize(config.History.ClientLength, config.History.AutoresizeWindow)
+				client.resizeHistory(config)
 			}
 		}
 	}
@@ -658,6 +668,10 @@ func (server *Server) applyConfig(config *Config, initial bool) (err error) {
 		if err := server.loadDatastore(config); err != nil {
 			return err
 		}
+	} else {
+		if config.Datastore.MySQL.Enabled && config.Datastore.MySQL != oldConfig.Datastore.MySQL {
+			server.historyDB.SetConfig(config.Datastore.MySQL)
+		}
 	}
 
 	server.setupPprofListener(config)
@@ -778,6 +792,15 @@ func (server *Server) loadDatastore(config *Config) error {
 	server.channels.Initialize(server)
 	server.accounts.Initialize(server)
 
+	if config.Datastore.MySQL.Enabled {
+		server.historyDB.Initialize(server.logger, config.Datastore.MySQL)
+		err = server.historyDB.Open()
+		if err != nil {
+			server.logger.Error("internal", "could not connect to mysql", err.Error())
+			return err
+		}
+	}
+
 	return nil
 }
 
@@ -835,6 +858,75 @@ func (server *Server) setupListeners(config *Config) (err error) {
 	return
 }
 
+// Gets the abstract sequence from which we're going to query history;
+// we may already know the channel we're querying, or we may have
+// to look it up via a string target. This function is responsible for
+// privilege checking.
+func (server *Server) GetHistorySequence(providedChannel *Channel, client *Client, target string) (channel *Channel, sequence history.Sequence, err error) {
+	config := server.Config()
+	var sender, recipient string
+	var hist *history.Buffer
+	if target == "*" {
+		persistent, ephemeral, target := client.historyStatus(config)
+		if persistent {
+			recipient = target
+		} else if ephemeral {
+			hist = &client.history
+		} else {
+			return
+		}
+	} else {
+		channel = providedChannel
+		if channel == nil {
+			channel = server.channels.Get(target)
+		}
+		if channel != nil {
+			if !channel.hasClient(client) {
+				err = errInsufficientPrivs
+				return
+			}
+			persistent, ephemeral, cfTarget := channel.historyStatus(config)
+			if persistent {
+				recipient = cfTarget
+			} else if ephemeral {
+				hist = &channel.history
+			} else {
+				return
+			}
+		} else {
+			sender = client.NickCasefolded()
+			var cfTarget string
+			cfTarget, err = CasefoldName(target)
+			if err != nil {
+				return
+			}
+			recipient = cfTarget
+			if !client.AlwaysOn() {
+				hist = &client.history
+			}
+		}
+	}
+
+	var cutoff time.Time
+	if config.History.Restrictions.ExpireTime != 0 {
+		cutoff = time.Now().UTC().Add(-time.Duration(config.History.Restrictions.ExpireTime))
+	}
+	if config.History.Restrictions.EnforceRegistrationDate {
+		regCutoff := client.historyCutoff()
+		regCutoff.Add(-time.Duration(config.History.Restrictions.GracePeriod))
+		// take the earlier of the two cutoffs
+		if regCutoff.After(cutoff) {
+			cutoff = regCutoff
+		}
+	}
+	if hist != nil {
+		sequence = hist.MakeSequence(recipient, cutoff)
+	} else if recipient != "" {
+		sequence = server.historyDB.MakeSequence(sender, recipient, cutoff)
+	}
+	return
+}
+
 // elistMatcher takes and matches ELIST conditions
 type elistMatcher struct {
 	MinClientsActive bool

irc/stats.go

@@ -26,15 +26,33 @@ func (s *Stats) Add() {
 	s.mutex.Unlock()
 }
 
+// Activates a registered client, e.g., for the initial attach to a persistent client
+func (s *Stats) AddRegistered(invisible, operator bool) {
+	s.mutex.Lock()
+	if invisible {
+		s.Invisible += 1
+	}
+	if operator {
+		s.Operators += 1
+	}
+	s.Total += 1
+	s.setMax()
+	s.mutex.Unlock()
+}
+
 // Transition a client from unregistered to registered
 func (s *Stats) Register() {
 	s.mutex.Lock()
 	s.Unknown -= 1
 	s.Total += 1
+	s.setMax()
+	s.mutex.Unlock()
+}
+
+func (s *Stats) setMax() {
 	if s.Max < s.Total {
 		s.Max = s.Total
 	}
-	s.mutex.Unlock()
 }
 
 // Modify the Invisible count

irc/utils/args.go

@@ -5,7 +5,13 @@ package utils
 
 import (
 	"errors"
+	"fmt"
 	"strings"
+	"time"
+)
+
+const (
+	IRCv3TimestampFormat = "2006-01-02T15:04:05.000Z"
 )
 
 var (
@@ -45,9 +51,9 @@ func ArgsToStrings(maxLength int, arguments []string, delim string) []string {
 
 func StringToBool(str string) (result bool, err error) {
 	switch strings.ToLower(str) {
-	case "on", "true", "t", "yes", "y":
+	case "on", "true", "t", "yes", "y", "enabled":
 		result = true
-	case "off", "false", "f", "no", "n":
+	case "off", "false", "f", "no", "n", "disabled":
 		result = false
 	default:
 		err = ErrInvalidParams
@@ -63,3 +69,16 @@ func SafeErrorParam(param string) string {
 	}
 	return param
 }
+
+type IncompatibleSchemaError struct {
+	CurrentVersion  string
+	RequiredVersion string
+}
+
+func (err *IncompatibleSchemaError) Error() string {
+	return fmt.Sprintf("Database requires update. Expected schema v%s, got v%s", err.RequiredVersion, err.CurrentVersion)
+}
+
+func NanoToTimestamp(nanotime int64) string {
+	return time.Unix(0, nanotime).UTC().Format(IRCv3TimestampFormat)
+}

irc/utils/net.go

@@ -18,14 +18,6 @@ var (
 	validHostnameLabelRegexp = regexp.MustCompile(`^[0-9A-Za-z.\-]+$`)
 )
 
-// AddrIsLocal returns whether the address is from a trusted local connection (loopback or unix).
-func AddrIsLocal(addr net.Addr) bool {
-	if tcpaddr, ok := addr.(*net.TCPAddr); ok {
-		return tcpaddr.IP.IsLoopback()
-	}
-	return AddrIsUnix(addr)
-}
-
 // AddrToIP returns the IP address for a net.Addr; unix domain sockets are treated as IPv4 loopback
 func AddrToIP(addr net.Addr) net.IP {
 	if tcpaddr, ok := addr.(*net.TCPAddr); ok {

irc/utils/text.go

@@ -23,9 +23,9 @@ type MessagePair struct {
 // SplitMessage represents a message that's been split for sending.
 // Two possibilities:
 // (a) Standard message that can be relayed on a single 512-byte line
-//     (MessagePair contains the message, Wrapped == nil)
+//     (MessagePair contains the message, Split == nil)
 // (b) multiline message that was split on the client side
-//     (Message == "", Wrapped contains the split lines)
+//     (Message == "", Split contains the split lines)
 type SplitMessage struct {
 	Message string
 	Msgid   string
@@ -36,7 +36,7 @@ type SplitMessage struct {
 func MakeMessage(original string) (result SplitMessage) {
 	result.Message = original
 	result.Msgid = GenerateSecretToken()
-	result.Time = time.Now().UTC()
+	result.SetTime()
 
 	return
 }
@@ -52,7 +52,8 @@ func (sm *SplitMessage) Append(message string, concat bool) {
 }
 
 func (sm *SplitMessage) SetTime() {
-	sm.Time = time.Now().UTC()
+	// strip the monotonic time, it's a potential source of problems:
+	sm.Time = time.Now().UTC().Round(0)
 }
 
 func (sm *SplitMessage) LenLines() int {
@@ -88,10 +89,6 @@ func (sm *SplitMessage) IsRestrictedCTCPMessage() bool {
 	return false
 }
 
-func (sm *SplitMessage) IsMultiline() bool {
-	return sm.Message == "" && len(sm.Split) != 0
-}
-
 func (sm *SplitMessage) Is512() bool {
 	return sm.Message != ""
 }

irc/znc.go

@@ -8,6 +8,8 @@ import (
 	"strconv"
 	"strings"
 	"time"
+
+	"github.com/oragono/oragono/irc/history"
 )
 
 type zncCommandHandler func(client *Client, command string, params []string, rb *ResponseBuffer)
@@ -43,7 +45,7 @@ func zncWireTimeToTime(str string) (result time.Time) {
 	}
 	seconds, _ := strconv.ParseInt(secondsPortion, 10, 64)
 	fraction, _ := strconv.ParseFloat(fracPortion, 64)
-	return time.Unix(seconds, int64(fraction*1000000000))
+	return time.Unix(seconds, int64(fraction*1000000000)).UTC()
 }
 
 type zncPlaybackTimes struct {
@@ -89,10 +91,8 @@ func zncPlaybackHandler(client *Client, command string, params []string, rb *Res
 	//     3.3  When the client sends a subsequent redundant JOIN line for those
 	//          channels; redundant JOIN is a complete no-op so we won't replay twice
 
-	config := client.server.Config()
 	if params[1] == "*" {
-		items, _ := client.history.Between(after, before, false, config.History.ChathistoryMax)
-		client.replayPrivmsgHistory(rb, items, true)
+		zncPlayPrivmsgs(client, rb, after, before)
 	} else {
 		targets = make(StringSet)
 		// TODO actually handle nickname targets
@@ -116,3 +116,15 @@ func zncPlaybackHandler(client *Client, command string, params []string, rb *Res
 		}
 	}
 }
+
+func zncPlayPrivmsgs(client *Client, rb *ResponseBuffer, after, before time.Time) {
+	_, sequence, _ := client.server.GetHistorySequence(nil, client, "*")
+	if sequence == nil {
+		return
+	}
+	zncMax := client.server.Config().History.ZNCMax
+	items, _, err := sequence.Between(history.Selector{Time: after}, history.Selector{Time: before}, zncMax)
+	if err == nil && len(items) != 0 {
+		client.replayPrivmsgHistory(rb, items, "", true)
+	}
+}