implement draft/resume-0.4

gencapdefs.py

@@ -113,7 +113,7 @@ CAPDEFS = [
     ),
     CapDef(
         identifier="Resume",
-        name="draft/resume-0.3",
+        name="draft/resume-0.4",
         url="https://github.com/DanielOaks/ircv3-specifications/blob/master+resume/extensions/resume.md",
         standard="proposed IRCv3",
     ),

irc/accounts.go

@@ -931,7 +931,7 @@ func (am *AccountManager) Unregister(account string) error {
 		if config.Accounts.RequireSasl.Enabled {
 			client.Quit(client.t("You are no longer authorized to be on this server"), nil)
 			// destroy acquires a semaphore so we can't call it while holding a lock
-			go client.destroy(false, nil)
+			go client.destroy(nil)
 		} else {
 			am.logoutOfAccount(client)
 		}

irc/caps/defs.go

@@ -77,7 +77,7 @@ const (
 	// https://github.com/SaberUK/ircv3-specifications/blob/rename/extensions/rename.md
 	Rename Capability = iota
 
-	// Resume is the proposed IRCv3 capability named "draft/resume-0.3":
+	// Resume is the proposed IRCv3 capability named "draft/resume-0.4":
 	// https://github.com/DanielOaks/ircv3-specifications/blob/master+resume/extensions/resume.md
 	Resume Capability = iota
 
@@ -133,7 +133,7 @@ var (
 		"message-tags",
 		"multi-prefix",
 		"draft/rename",
-		"draft/resume-0.3",
+		"draft/resume-0.4",
 		"sasl",
 		"server-time",
 		"draft/setname",

irc/channel.go

@@ -20,6 +20,10 @@ import (
 	"github.com/oragono/oragono/irc/utils"
 )
 
+const (
+	histServMask = "HistServ!HistServ@localhost"
+)
+
 // Channel represents a channel that clients can join.
 type Channel struct {
 	flags             modes.ModeSet
@@ -695,46 +699,30 @@ func (channel *Channel) Part(client *Client, message string, rb *ResponseBuffer)
 // 1. Replace the old client with the new in the channel's data structures
 // 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(newClient, oldClient *Client, timestamp time.Time) {
+func (channel *Channel) Resume(session *Session, timestamp time.Time) {
 	now := time.Now().UTC()
-	channel.resumeAndAnnounce(newClient, oldClient)
+	channel.resumeAndAnnounce(session)
 	if !timestamp.IsZero() {
-		channel.replayHistoryForResume(newClient, timestamp, now)
+		channel.replayHistoryForResume(session, timestamp, now)
 	}
 }
 
-func (channel *Channel) resumeAndAnnounce(newClient, oldClient *Client) {
+func (channel *Channel) resumeAndAnnounce(session *Session) {
-	var oldModeSet *modes.ModeSet
+	channel.stateMutex.RLock()
-
+	modeSet := channel.members[session.client]
-	func() {
+	channel.stateMutex.RUnlock()
-		channel.joinPartMutex.Lock()
+	if modeSet == nil {
-		defer channel.joinPartMutex.Unlock()
+		return
-
-		defer channel.regenerateMembersCache()
-
-		channel.stateMutex.Lock()
-		defer channel.stateMutex.Unlock()
-
-		newClient.channels[channel] = true
-		oldModeSet = channel.members[oldClient]
-		if oldModeSet == nil {
-			oldModeSet = modes.NewModeSet()
 	}
-		channel.members.Remove(oldClient)
+	oldModes := modeSet.String()
-		channel.members[newClient] = oldModeSet
-	}()
-
-	// construct fake modestring if necessary
-	oldModes := oldModeSet.String()
 	if 0 < len(oldModes) {
 		oldModes = "+" + oldModes
 	}
 
 	// send join for old clients
-	nick := newClient.Nick()
+	chname := channel.Name()
-	nickMask := newClient.NickMaskString()
+	details := session.client.Details()
-	accountName := newClient.AccountName()
+	realName := session.client.Realname()
-	realName := newClient.Realname()
 	for _, member := range channel.Members() {
 		for _, session := range member.Sessions() {
 			if session.capabilities.Has(caps.Resume) {
@@ -742,39 +730,36 @@ func (channel *Channel) resumeAndAnnounce(newClient, oldClient *Client) {
 			}
 
 			if session.capabilities.Has(caps.ExtendedJoin) {
-				session.Send(nil, nickMask, "JOIN", channel.name, accountName, realName)
+				session.Send(nil, details.nickMask, "JOIN", chname, details.accountName, realName)
 			} else {
-				session.Send(nil, nickMask, "JOIN", channel.name)
+				session.Send(nil, details.nickMask, "JOIN", chname)
 			}
 
 			if 0 < len(oldModes) {
-				session.Send(nil, channel.server.name, "MODE", channel.name, oldModes, nick)
+				session.Send(nil, channel.server.name, "MODE", chname, oldModes, details.nick)
 			}
 		}
 	}
 
-	rb := NewResponseBuffer(newClient.Sessions()[0])
+	rb := NewResponseBuffer(session)
 	// use blocking i/o to synchronize with the later history replay
 	if rb.session.capabilities.Has(caps.ExtendedJoin) {
-		rb.Add(nil, nickMask, "JOIN", channel.name, accountName, realName)
+		rb.Add(nil, details.nickMask, "JOIN", channel.name, details.accountName, realName)
 	} else {
-		rb.Add(nil, nickMask, "JOIN", channel.name)
+		rb.Add(nil, details.nickMask, "JOIN", channel.name)
-	}
-	channel.SendTopic(newClient, rb, false)
-	channel.Names(newClient, rb)
-	if 0 < len(oldModes) {
-		rb.Add(nil, newClient.server.name, "MODE", channel.name, oldModes, nick)
 	}
+	channel.SendTopic(session.client, rb, false)
+	channel.Names(session.client, rb)
 	rb.Send(true)
 }
 
-func (channel *Channel) replayHistoryForResume(newClient *Client, after time.Time, before time.Time) {
+func (channel *Channel) replayHistoryForResume(session *Session, after time.Time, before time.Time) {
 	items, complete := channel.history.Between(after, before, false, 0)
-	rb := NewResponseBuffer(newClient.Sessions()[0])
+	rb := NewResponseBuffer(session)
 	channel.replayHistoryItems(rb, items, false)
-	if !complete && !newClient.resumeDetails.HistoryIncomplete {
+	if !complete && !session.resumeDetails.HistoryIncomplete {
 		// warn here if we didn't warn already
-		rb.Add(nil, "HistServ", "NOTICE", channel.Name(), newClient.t("Some additional message history may have been lost"))
+		rb.Add(nil, histServMask, "NOTICE", channel.Name(), session.client.t("Some additional message history may have been lost"))
 	}
 	rb.Send(true)
 }
@@ -828,7 +813,7 @@ func (channel *Channel) replayHistoryItems(rb *ResponseBuffer, items []history.I
 				} else {
 					message = fmt.Sprintf(client.t("%[1]s [account: %[2]s] joined the channel"), nick, item.AccountName)
 				}
-				rb.AddFromClient(item.Message.Time, utils.MungeSecretToken(item.Message.Msgid), "HistServ", "*", nil, "PRIVMSG", chname, message)
+				rb.AddFromClient(item.Message.Time, utils.MungeSecretToken(item.Message.Msgid), histServMask, "*", nil, "PRIVMSG", chname, message)
 			}
 		case history.Part:
 			if eventPlayback {
@@ -838,14 +823,14 @@ func (channel *Channel) replayHistoryItems(rb *ResponseBuffer, items []history.I
 					continue // #474
 				}
 				message := fmt.Sprintf(client.t("%[1]s left the channel (%[2]s)"), nick, item.Message.Message)
-				rb.AddFromClient(item.Message.Time, utils.MungeSecretToken(item.Message.Msgid), "HistServ", "*", nil, "PRIVMSG", chname, message)
+				rb.AddFromClient(item.Message.Time, utils.MungeSecretToken(item.Message.Msgid), histServMask, "*", nil, "PRIVMSG", chname, message)
 			}
 		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)
 			} 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), "HistServ", "*", nil, "PRIVMSG", chname, message)
+				rb.AddFromClient(item.Message.Time, utils.MungeSecretToken(item.Message.Msgid), histServMask, "*", nil, "PRIVMSG", chname, message)
 			}
 		case history.Quit:
 			if eventPlayback {
@@ -855,14 +840,14 @@ func (channel *Channel) replayHistoryItems(rb *ResponseBuffer, items []history.I
 					continue // #474
 				}
 				message := fmt.Sprintf(client.t("%[1]s quit (%[2]s)"), nick, item.Message.Message)
-				rb.AddFromClient(item.Message.Time, utils.MungeSecretToken(item.Message.Msgid), "HistServ", "*", nil, "PRIVMSG", chname, message)
+				rb.AddFromClient(item.Message.Time, utils.MungeSecretToken(item.Message.Msgid), histServMask, "*", nil, "PRIVMSG", chname, message)
 			}
 		case history.Nick:
 			if eventPlayback {
 				rb.AddFromClient(item.Message.Time, item.Message.Msgid, item.Nick, item.AccountName, nil, "HEVENT", "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), "HistServ", "*", nil, "PRIVMSG", chname, message)
+				rb.AddFromClient(item.Message.Time, utils.MungeSecretToken(item.Message.Msgid), histServMask, "*", nil, "PRIVMSG", chname, message)
 			}
 		}
 	}

irc/client.go

@@ -36,11 +36,8 @@ const (
 // the resume process: when handling the RESUME command itself,
 // when completing the registration, and when rejoining channels.
 type ResumeDetails struct {
-	OldClient         *Client
 	PresentedToken    string
 	Timestamp         time.Time
-	ResumedAt         time.Time
-	Channels          []string
 	HistoryIncomplete bool
 }
 
@@ -52,6 +49,7 @@ type Client struct {
 	atime              time.Time
 	away               bool
 	awayMessage        string
+	brbTimer           BrbTimer
 	certfp             string
 	channels           ChannelSet
 	ctime              time.Time
@@ -75,7 +73,6 @@ type Client struct {
 	realname           string
 	realIP             net.IP
 	registered         bool
-	resumeDetails      *ResumeDetails
 	resumeID           string
 	saslInProgress     bool
 	saslMechanism      string
@@ -87,7 +84,7 @@ type Client struct {
 	stateMutex         sync.RWMutex // tier 1
 	username           string
 	vhost              string
-	history            *history.Buffer
+	history            history.Buffer
 }
 
 // Session is an individual client connection to the server (TCP connection
@@ -113,6 +110,9 @@ type Session struct {
 	maxlenRest   uint32
 	capState     caps.State
 	capVersion   caps.Version
+
+	resumeID      string
+	resumeDetails *ResumeDetails
 }
 
 // sets the session quit message, if there isn't one already
@@ -207,8 +207,9 @@ func (server *Server) RunClient(conn clientConn) {
 		nick:           "*", // * is used until actual nick is given
 		nickCasefolded: "*",
 		nickMaskString: "*", // * is used until actual nick is given
-		history:        history.NewHistoryBuffer(config.History.ClientLength),
 	}
+	client.history.Initialize(config.History.ClientLength)
+	client.brbTimer.Initialize(client)
 	session := &Session{
 		client:     client,
 		socket:     socket,
@@ -339,7 +340,7 @@ func (client *Client) run(session *Session) {
 			}
 		}
 		// ensure client connection gets closed
-		client.destroy(false, session)
+		client.destroy(session)
 	}()
 
 	session.idletimer.Initialize(session)
@@ -347,7 +348,13 @@ func (client *Client) run(session *Session) {
 
 	isReattach := client.Registered()
 	if isReattach {
+		if session.resumeDetails != nil {
+			session.playResume()
+			session.resumeDetails = nil
+			client.brbTimer.Disable()
+		} else {
 			client.playReattachMessages(session)
+		}
 	} else {
 		// don't reset the nick timer during a reattach
 		client.nickTimer.Initialize(client)
@@ -365,6 +372,9 @@ func (client *Client) run(session *Session) {
 				quitMessage = "readQ exceeded"
 			}
 			client.Quit(quitMessage, session)
+			// since the client did not actually send us a QUIT,
+			// give them a chance to resume or reattach if applicable:
+			client.brbTimer.Enable()
 			break
 		}
 
@@ -443,83 +453,66 @@ func (session *Session) Ping() {
 }
 
 // tryResume tries to resume if the client asked us to.
-func (client *Client) tryResume() (success bool) {
+func (session *Session) tryResume() (success bool) {
-	server := client.server
+	var oldResumeID string
-	config := server.Config()
 
 	defer func() {
-		if !success {
+		if success {
-			client.resumeDetails = nil
+			// "On a successful request, the server [...] terminates the old client's connection"
+			oldSession := session.client.GetSessionByResumeID(oldResumeID)
+			if oldSession != nil {
+				session.client.destroy(oldSession)
+			}
+		} else {
+			session.resumeDetails = nil
 		}
 	}()
 
-	timestamp := client.resumeDetails.Timestamp
+	client := session.client
-	var timestampString string
+	server := client.server
-	if !timestamp.IsZero() {
+	config := server.Config()
-		timestampString = timestamp.UTC().Format(IRCv3TimestampFormat)
-	}
 
-	oldClient := server.resumeManager.VerifyToken(client.resumeDetails.PresentedToken)
+	oldClient, oldResumeID := server.resumeManager.VerifyToken(client, session.resumeDetails.PresentedToken)
 	if oldClient == nil {
-		client.Send(nil, server.name, "RESUME", "ERR", client.t("Cannot resume connection, token is not valid"))
+		session.Send(nil, server.name, "FAIL", "RESUME", "INVALID_TOKEN", client.t("Cannot resume connection, token is not valid"))
 		return
 	}
-	oldNick := oldClient.Nick()
-	oldNickmask := oldClient.NickMaskString()
 
 	resumeAllowed := config.Server.AllowPlaintextResume || (oldClient.HasMode(modes.TLS) && client.HasMode(modes.TLS))
 	if !resumeAllowed {
-		client.Send(nil, server.name, "RESUME", "ERR", client.t("Cannot resume connection, old and new clients must have TLS"))
+		session.Send(nil, server.name, "FAIL", "RESUME", "INSECURE_SESSION", client.t("Cannot resume connection, old and new clients must have TLS"))
 		return
 	}
 
 	if oldClient.isTor != client.isTor {
-		client.Send(nil, server.name, "RESUME", "ERR", client.t("Cannot resume connection from Tor to non-Tor or vice versa"))
+		session.Send(nil, server.name, "FAIL", "RESUME", "INSECURE_SESSION", client.t("Cannot resume connection from Tor to non-Tor or vice versa"))
 		return
 	}
 
-	if 1 < len(oldClient.Sessions()) {
+	err := server.clients.Resume(oldClient, session)
-		client.Send(nil, server.name, "RESUME", "ERR", client.t("Cannot resume a client with multiple attached sessions"))
-		return
-	}
-
-	err := server.clients.Resume(client, oldClient)
 	if err != nil {
-		client.Send(nil, server.name, "RESUME", "ERR", client.t("Cannot resume connection"))
+		session.Send(nil, server.name, "FAIL", "RESUME", "CANNOT_RESUME", client.t("Cannot resume connection"))
 		return
 	}
 
 	success = true
+	client.server.logger.Debug("quit", fmt.Sprintf("%s is being resumed", oldClient.Nick()))
 
-	// this is a bit racey
+	return
-	client.resumeDetails.ResumedAt = time.Now().UTC()
-
-	client.nickTimer.Touch(nil)
-
-	// resume successful, proceed to copy client state (nickname, flags, etc.)
-	// after this, the server thinks that `newClient` owns the nickname
-
-	client.resumeDetails.OldClient = oldClient
-
-	// transfer monitor stuff
-	server.monitorManager.Resume(client, oldClient)
-
-	// record the names, not the pointers, of the channels,
-	// to avoid dumb annoying race conditions
-	channels := oldClient.Channels()
-	client.resumeDetails.Channels = make([]string, len(channels))
-	for i, channel := range channels {
-		client.resumeDetails.Channels[i] = channel.Name()
 }
 
-	username := client.Username()
+// playResume is called from the session's fresh goroutine after a resume;
-	hostname := client.Hostname()
+// it sends notifications to friends, then plays the registration burst and replays
+// stored history to the session
+func (session *Session) playResume() {
+	client := session.client
+	server := client.server
 
 	friends := make(ClientSet)
 	oldestLostMessage := time.Now().UTC()
 
 	// work out how much time, if any, is not covered by history buffers
-	for _, channel := range channels {
+	for _, channel := range client.Channels() {
 		for _, member := range channel.Members() {
 			friends.Add(member)
 			lastDiscarded := channel.history.LastDiscarded()
@@ -531,8 +524,8 @@ func (client *Client) tryResume() (success bool) {
 	privmsgMatcher := func(item history.Item) bool {
 		return item.Type == history.Privmsg || item.Type == history.Notice || item.Type == history.Tagmsg
 	}
-	privmsgHistory := oldClient.history.Match(privmsgMatcher, false, 0)
+	privmsgHistory := client.history.Match(privmsgMatcher, false, 0)
-	lastDiscarded := oldClient.history.LastDiscarded()
+	lastDiscarded := client.history.LastDiscarded()
 	if lastDiscarded.Before(oldestLostMessage) {
 		oldestLostMessage = lastDiscarded
 	}
@@ -543,60 +536,61 @@ func (client *Client) tryResume() (success bool) {
 		}
 	}
 
+	timestamp := session.resumeDetails.Timestamp
 	gap := lastDiscarded.Sub(timestamp)
-	client.resumeDetails.HistoryIncomplete = gap > 0
+	session.resumeDetails.HistoryIncomplete = gap > 0
 	gapSeconds := int(gap.Seconds()) + 1 // round up to avoid confusion
 
+	details := client.Details()
+	oldNickmask := details.nickMask
+	client.SetRawHostname(session.rawHostname)
+	hostname := client.Hostname() // may be a vhost
+	timestampString := session.resumeDetails.Timestamp.Format(IRCv3TimestampFormat)
+
 	// send quit/resume messages to friends
 	for friend := range friends {
-		for _, session := range friend.Sessions() {
+		if friend == client {
-			if session.capabilities.Has(caps.Resume) {
-				if timestamp.IsZero() {
-					session.Send(nil, oldNickmask, "RESUMED", username, hostname)
-				} else {
-					session.Send(nil, oldNickmask, "RESUMED", username, hostname, timestampString)
-				}
-			} else {
-				if client.resumeDetails.HistoryIncomplete {
-					session.Send(nil, oldNickmask, "QUIT", fmt.Sprintf(friend.t("Client reconnected (up to %d seconds of history lost)"), gapSeconds))
-				} else {
-					session.Send(nil, oldNickmask, "QUIT", fmt.Sprintf(friend.t("Client reconnected")))
-				}
-			}
-		}
-	}
-
-	if client.resumeDetails.HistoryIncomplete {
-		client.Send(nil, client.server.name, "RESUME", "WARN", fmt.Sprintf(client.t("Resume may have lost up to %d seconds of history"), gapSeconds))
-	}
-
-	client.Send(nil, client.server.name, "RESUME", "SUCCESS", oldNick)
-
-	// after we send the rest of the registration burst, we'll try rejoining channels
-	return
-}
-
-func (client *Client) tryResumeChannels() {
-	details := client.resumeDetails
-
-	for _, name := range details.Channels {
-		channel := client.server.channels.Get(name)
-		if channel == nil {
 			continue
 		}
-		channel.Resume(client, details.OldClient, details.Timestamp)
+		for _, fSession := range friend.Sessions() {
+			if fSession.capabilities.Has(caps.Resume) {
+				if timestamp.IsZero() {
+					fSession.Send(nil, oldNickmask, "RESUMED", hostname)
+				} else {
+					fSession.Send(nil, oldNickmask, "RESUMED", hostname, timestampString)
+				}
+			} else {
+				if session.resumeDetails.HistoryIncomplete {
+					fSession.Send(nil, oldNickmask, "QUIT", fmt.Sprintf(friend.t("Client reconnected (up to %d seconds of history lost)"), gapSeconds))
+				} else {
+					fSession.Send(nil, oldNickmask, "QUIT", fmt.Sprintf(friend.t("Client reconnected")))
+				}
+			}
+		}
+	}
+
+	if session.resumeDetails.HistoryIncomplete {
+		session.Send(nil, client.server.name, "RESUME", "WARN", "HISTORY_LOST", fmt.Sprintf(client.t("Resume may have lost up to %d seconds of history"), gapSeconds))
+	}
+
+	session.Send(nil, client.server.name, "RESUME", details.nick)
+
+	server.playRegistrationBurst(session)
+
+	for _, channel := range client.Channels() {
+		channel.Resume(session, timestamp)
 	}
 
 	// replay direct PRIVSMG history
-	if !details.Timestamp.IsZero() {
+	if !timestamp.IsZero() {
 		now := time.Now().UTC()
-		items, complete := client.history.Between(details.Timestamp, now, false, 0)
+		items, complete := client.history.Between(timestamp, now, false, 0)
 		rb := NewResponseBuffer(client.Sessions()[0])
 		client.replayPrivmsgHistory(rb, items, complete)
 		rb.Send(true)
 	}
 
-	details.OldClient.destroy(true, nil)
+	session.resumeDetails = nil
 }
 
 func (client *Client) replayPrivmsgHistory(rb *ResponseBuffer, items []history.Item, complete bool) {
@@ -644,41 +638,6 @@ func (client *Client) replayPrivmsgHistory(rb *ResponseBuffer, items []history.I
 	}
 }
 
-// copy applicable state from oldClient to client as part of a resume
-func (client *Client) copyResumeData(oldClient *Client) {
-	oldClient.stateMutex.RLock()
-	history := oldClient.history
-	nick := oldClient.nick
-	nickCasefolded := oldClient.nickCasefolded
-	vhost := oldClient.vhost
-	account := oldClient.account
-	accountName := oldClient.accountName
-	skeleton := oldClient.skeleton
-	oldClient.stateMutex.RUnlock()
-
-	// copy all flags, *except* TLS (in the case that the admins enabled
-	// resume over plaintext)
-	hasTLS := client.flags.HasMode(modes.TLS)
-	temp := modes.NewModeSet()
-	temp.Copy(&oldClient.flags)
-	temp.SetMode(modes.TLS, hasTLS)
-	client.flags.Copy(temp)
-
-	client.stateMutex.Lock()
-	defer client.stateMutex.Unlock()
-
-	// reuse the old client's history buffer
-	client.history = history
-	// copy other data
-	client.nick = nick
-	client.nickCasefolded = nickCasefolded
-	client.vhost = vhost
-	client.account = account
-	client.accountName = accountName
-	client.skeleton = skeleton
-	client.updateNickMaskNoMutex()
-}
-
 // IdleTime returns how long this client's been idle.
 func (client *Client) IdleTime() time.Duration {
 	client.stateMutex.RLock()
@@ -956,12 +915,13 @@ func (client *Client) Quit(message string, session *Session) {
 // if `session` is nil, destroys the client unconditionally, removing all sessions;
 // otherwise, destroys one specific session, only destroying the client if it
 // has no more sessions.
-func (client *Client) destroy(beingResumed bool, session *Session) {
+func (client *Client) destroy(session *Session) {
 	var sessionsToDestroy []*Session
 
 	// allow destroy() to execute at most once
 	client.stateMutex.Lock()
 	details := client.detailsNoMutex()
+	brbState := client.brbTimer.state
 	wasReattach := session != nil && session.client != client
 	sessionRemoved := false
 	var remainingSessions int
@@ -977,10 +937,6 @@ func (client *Client) destroy(beingResumed bool, session *Session) {
 	}
 	client.stateMutex.Unlock()
 
-	if len(sessionsToDestroy) == 0 {
-		return
-	}
-
 	// destroy all applicable sessions:
 	var quitMessage string
 	for _, session := range sessionsToDestroy {
@@ -1010,8 +966,8 @@ func (client *Client) destroy(beingResumed bool, session *Session) {
 		client.server.logger.Info("localconnect-ip", fmt.Sprintf("disconnecting session of %s from %s", details.nick, source))
 	}
 
-	// ok, now destroy the client, unless it still has sessions:
+	// do not destroy the client if it has either remaining sessions, or is BRB'ed
-	if remainingSessions != 0 {
+	if remainingSessions != 0 || brbState == BrbEnabled || brbState == BrbSticky {
 		return
 	}
 
@@ -1020,14 +976,12 @@ func (client *Client) destroy(beingResumed bool, session *Session) {
 	client.server.semaphores.ClientDestroy.Acquire()
 	defer client.server.semaphores.ClientDestroy.Release()
 
-	if beingResumed {
+	if !wasReattach {
-		client.server.logger.Debug("quit", fmt.Sprintf("%s is being resumed", details.nick))
-	} else if !wasReattach {
 		client.server.logger.Debug("quit", fmt.Sprintf("%s is no longer on the server", details.nick))
 	}
 
 	registered := client.Registered()
-	if !beingResumed && registered {
+	if registered {
 		client.server.whoWas.Append(client.WhoWas())
 	}
 
@@ -1045,7 +999,6 @@ func (client *Client) destroy(beingResumed bool, session *Session) {
 	// (note that if this is a reattach, client has no channels and therefore no friends)
 	friends := make(ClientSet)
 	for _, channel := range client.Channels() {
-		if !beingResumed {
 		channel.Quit(client)
 		channel.history.Add(history.Item{
 			Type:        history.Quit,
@@ -1053,7 +1006,6 @@ func (client *Client) destroy(beingResumed bool, session *Session) {
 			AccountName: details.accountName,
 			Message:     splitQuitMessage,
 		})
-		}
 		for _, member := range channel.Members() {
 			friends.Add(member)
 		}
@@ -1061,17 +1013,15 @@ func (client *Client) destroy(beingResumed bool, session *Session) {
 	friends.Remove(client)
 
 	// clean up server
-	if !beingResumed {
 	client.server.clients.Remove(client)
-	}
 
 	// clean up self
 	client.nickTimer.Stop()
+	client.brbTimer.Disable()
 
 	client.server.accounts.Logout(client)
 
 	// send quit messages to friends
-	if !beingResumed {
 	if registered {
 		client.server.stats.ChangeTotal(-1)
 	}
@@ -1088,15 +1038,11 @@ func (client *Client) destroy(beingResumed bool, session *Session) {
 		}
 		friend.sendFromClientInternal(false, splitQuitMessage.Time, splitQuitMessage.Msgid, details.nickMask, details.accountName, nil, "QUIT", quitMessage)
 	}
-	}
+
-	if !client.exitedSnomaskSent {
+	if !client.exitedSnomaskSent && registered {
-		if beingResumed {
-			client.server.snomasks.Send(sno.LocalQuits, fmt.Sprintf(ircfmt.Unescape("%s$r is resuming their connection, old client has been destroyed"), client.nick))
-		} else if registered {
 		client.server.snomasks.Send(sno.LocalQuits, fmt.Sprintf(ircfmt.Unescape("%s$r exited the network"), details.nick))
 	}
 }
-}
 
 // SendSplitMsgFromClient sends an IRC PRIVMSG/NOTICE coming from a specific client.
 // Adds account-tag to the line as well.

irc/client_lookup_set.go

@@ -108,26 +108,21 @@ func (clients *ClientManager) Remove(client *Client) error {
 	return clients.removeInternal(client)
 }
 
-// Resume atomically replaces `oldClient` with `newClient`, updating
+// Handles a RESUME by attaching a session to a designated client. It is the
-// newClient's data to match. It is the caller's responsibility first
+// caller's responsibility to verify that the resume is allowed (checking tokens,
-// to verify that the resume is allowed, and then later to call oldClient.destroy().
+// TLS status, etc.) before calling this.
-func (clients *ClientManager) Resume(newClient, oldClient *Client) (err error) {
+func (clients *ClientManager) Resume(oldClient *Client, session *Session) (err error) {
 	clients.Lock()
 	defer clients.Unlock()
 
-	// atomically grant the new client the old nick
+	cfnick := oldClient.NickCasefolded()
-	err = clients.removeInternal(oldClient)
+	if _, ok := clients.byNick[cfnick]; !ok {
-	if err != nil {
+		return errNickMissing
-		// oldClient no longer owns its nick, fail out
-		return err
 	}
-	// nick has been reclaimed, grant it to the new client
-	clients.removeInternal(newClient)
-	oldcfnick, oldskeleton := oldClient.uniqueIdentifiers()
-	clients.byNick[oldcfnick] = newClient
-	clients.bySkeleton[oldskeleton] = newClient
 
-	newClient.copyResumeData(oldClient)
+	if !oldClient.AddSession(session) {
+		return errNickMissing
+	}
 
 	return nil
 }
@@ -256,27 +251,6 @@ func (clients *ClientManager) FindAll(userhost string) (set ClientSet) {
 	return set
 }
 
-// Find returns the first client that matches the given userhost mask.
-func (clients *ClientManager) Find(userhost string) *Client {
-	userhost, err := Casefold(ExpandUserHost(userhost))
-	if err != nil {
-		return nil
-	}
-	matcher := ircmatch.MakeMatch(userhost)
-	var matchedClient *Client
-
-	clients.RLock()
-	defer clients.RUnlock()
-	for _, client := range clients.byNick {
-		if matcher.Match(client.NickMaskCasefolded()) {
-			matchedClient = client
-			break
-		}
-	}
-
-	return matchedClient
-}
-
 //
 // usermask to regexp
 //

irc/commands.go

@@ -88,6 +88,10 @@ func init() {
 			handler:   awayHandler,
 			minParams: 0,
 		},
+		"BRB": {
+			handler:   brbHandler,
+			minParams: 0,
+		},
 		"CAP": {
 			handler:      capHandler,
 			usablePreReg: true,

irc/getters.go

@@ -65,6 +65,18 @@ func (client *Client) Sessions() (sessions []*Session) {
 	return
 }
 
+func (client *Client) GetSessionByResumeID(resumeID string) (result *Session) {
+	client.stateMutex.RLock()
+	defer client.stateMutex.RUnlock()
+
+	for _, session := range client.sessions {
+		if session.resumeID == resumeID {
+			return session
+		}
+	}
+	return
+}
+
 type SessionData struct {
 	ctime    time.Time
 	atime    time.Time
@@ -100,9 +112,17 @@ func (client *Client) AddSession(session *Session) (success bool) {
 	client.stateMutex.Lock()
 	defer client.stateMutex.Unlock()
 
+	// client may be dying and ineligible to receive another session
+	switch client.brbTimer.state {
+	case BrbDisabled:
 		if len(client.sessions) == 0 {
 			return false
 		}
+	case BrbDead:
+		return false
+		// default: BrbEnabled or BrbSticky, proceed
+	}
+	// success, attach the new session to the client
 	session.client = client
 	client.sessions = append(client.sessions, session)
 	return true
@@ -125,6 +145,12 @@ func (client *Client) removeSession(session *Session) (success bool, length int)
 	return
 }
 
+func (session *Session) SetResumeID(resumeID string) {
+	session.client.stateMutex.Lock()
+	session.resumeID = resumeID
+	session.client.stateMutex.Unlock()
+}
+
 func (client *Client) Nick() string {
 	client.stateMutex.RLock()
 	defer client.stateMutex.RUnlock()
@@ -233,6 +259,14 @@ func (client *Client) RawHostname() (result string) {
 	return
 }
 
+func (client *Client) SetRawHostname(rawHostname string) {
+	client.stateMutex.Lock()
+	defer client.stateMutex.Unlock()
+
+	client.rawHostname = rawHostname
+	client.updateNickMaskNoMutex()
+}
+
 func (client *Client) AwayMessage() (result string) {
 	client.stateMutex.RLock()
 	result = client.awayMessage

irc/handlers.go

@@ -502,6 +502,31 @@ func awayHandler(server *Server, client *Client, msg ircmsg.IrcMessage, rb *Resp
 	return false
 }
 
+// BRB [message]
+func brbHandler(server *Server, client *Client, msg ircmsg.IrcMessage, rb *ResponseBuffer) bool {
+	success, duration := client.brbTimer.Enable()
+	if !success {
+		rb.Add(nil, server.name, "FAIL", "BRB", "CANNOT_BRB", client.t("Your client does not support BRB"))
+		return false
+	} else {
+		rb.Add(nil, server.name, "BRB", strconv.Itoa(int(duration.Seconds())))
+	}
+
+	var message string
+	if 0 < len(msg.Params) {
+		message = msg.Params[0]
+	} else {
+		message = client.t("I'll be right back")
+	}
+
+	if len(client.Sessions()) == 1 {
+		// true BRB
+		client.SetAway(true, message)
+	}
+
+	return true
+}
+
 // CAP <subcmd> [<caps>]
 func capHandler(server *Server, client *Client, msg ircmsg.IrcMessage, rb *ResponseBuffer) bool {
 	subCommand := strings.ToUpper(msg.Params[0])
@@ -568,9 +593,10 @@ func capHandler(server *Server, client *Client, msg ircmsg.IrcMessage, rb *Respo
 		// if this is the first time the client is requesting a resume token,
 		// send it to them
 		if toAdd.Has(caps.Resume) {
-			token := server.resumeManager.GenerateToken(client)
+			token, id := server.resumeManager.GenerateToken(client)
 			if token != "" {
 				rb.Add(nil, server.name, "RESUME", "TOKEN", token)
+				rb.session.SetResumeID(id)
 			}
 		}
 
@@ -638,7 +664,7 @@ func chathistoryHandler(server *Server, client *Client, msg ircmsg.IrcMessage, r
 			myAccount := client.Account()
 			targetAccount := targetClient.Account()
 			if myAccount != "" && targetAccount != "" && myAccount == targetAccount {
-				hist = targetClient.history
+				hist = &targetClient.history
 			}
 		}
 	}
@@ -1024,7 +1050,7 @@ func dlineHandler(server *Server, client *Client, msg ircmsg.IrcMessage, rb *Res
 				killClient = true
 			} else {
 				// if mcl == client, we kill them below
-				mcl.destroy(false, nil)
+				mcl.destroy(nil)
 			}
 		}
 
@@ -1087,13 +1113,13 @@ func historyHandler(server *Server, client *Client, msg ircmsg.IrcMessage, rb *R
 		hist = &channel.history
 	} else {
 		if strings.ToLower(target) == "me" {
-			hist = client.history
+			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
+					hist = &targetClient.history
 				}
 			}
 		}
@@ -1331,7 +1357,7 @@ func killHandler(server *Server, client *Client, msg ircmsg.IrcMessage, rb *Resp
 	target.exitedSnomaskSent = true
 
 	target.Quit(quitMsg, nil)
-	target.destroy(false, nil)
+	target.destroy(nil)
 	return false
 }
 
@@ -1461,7 +1487,7 @@ func klineHandler(server *Server, client *Client, msg ircmsg.IrcMessage, rb *Res
 				killClient = true
 			} else {
 				// if mcl == client, we kill them below
-				mcl.destroy(false, nil)
+				mcl.destroy(nil)
 			}
 		}
 
@@ -2326,28 +2352,25 @@ func renameHandler(server *Server, client *Client, msg ircmsg.IrcMessage, rb *Re
 
 // RESUME <token> [timestamp]
 func resumeHandler(server *Server, client *Client, msg ircmsg.IrcMessage, rb *ResponseBuffer) bool {
-	token := msg.Params[0]
+	details := ResumeDetails{
+		PresentedToken: msg.Params[0],
+	}
 
 	if client.registered {
-		rb.Add(nil, server.name, "RESUME", "ERR", client.t("Cannot resume connection, connection registration has already been completed"))
+		rb.Add(nil, server.name, "FAIL", "RESUME", "REGISTRATION_IS_COMPLETED", client.t("Cannot resume connection, connection registration has already been completed"))
 		return false
 	}
 
-	var timestamp time.Time
 	if 1 < len(msg.Params) {
 		ts, err := time.Parse(IRCv3TimestampFormat, msg.Params[1])
 		if err == nil {
-			timestamp = ts
+			details.Timestamp = ts
 		} else {
-			rb.Add(nil, server.name, "RESUME", "WARN", client.t("Timestamp is not in 2006-01-02T15:04:05.999Z format, ignoring it"))
+			rb.Add(nil, server.name, "WARN", "RESUME", "HISTORY_LOST", client.t("Timestamp is not in 2006-01-02T15:04:05.999Z format, ignoring it"))
 		}
 	}
 
-	client.resumeDetails = &ResumeDetails{
+	rb.session.resumeDetails = &details
-		Timestamp:      timestamp,
-		PresentedToken: token,
-	}
-
 	return false
 }
 

irc/help.go

@@ -120,6 +120,14 @@ http://ircv3.net/specs/extensions/sasl-3.1.html`,
 
 If [message] is sent, marks you away. If [message] is not sent, marks you no
 longer away.`,
+	},
+	"brb": {
+		text: `BRB [message]
+
+Disconnects you from the server, while instructing the server to keep you
+present for a short time window. During this window, you can either resume
+or reattach to your nickname. If [message] is sent, it is used as your away
+message (and as your quit message if you don't return in time).`,
 	},
 	"cap": {
 		text: `CAP <subcommand> [:<capabilities>]

irc/idletimer.go

@@ -126,7 +126,7 @@ func (it *IdleTimer) processTimeout() {
 		it.session.Ping()
 	} else {
 		it.session.client.Quit(it.quitMessage(previousState), it.session)
-		it.session.client.destroy(false, it.session)
+		it.session.client.destroy(it.session)
 	}
 }
 
@@ -157,8 +157,12 @@ func (it *IdleTimer) resetTimeout() {
 	case TimerDead:
 		return
 	}
+	if it.timer != nil {
+		it.timer.Reset(nextTimeout)
+	} else {
 		it.timer = time.AfterFunc(nextTimeout, it.processTimeout)
 	}
+}
 
 func (it *IdleTimer) quitMessage(state TimerState) string {
 	switch state {
@@ -300,3 +304,134 @@ func (nt *NickTimer) processTimeout() {
 	nt.client.Notice(fmt.Sprintf(nt.client.t(baseMsg), nt.Timeout()))
 	nt.client.server.RandomlyRename(nt.client)
 }
+
+// BrbTimer is a timer on the client as a whole (not an individual session) for implementing
+// the BRB command and related functionality (where a client can remain online without
+// having any connected sessions).
+
+type BrbState uint
+
+const (
+	// BrbDisabled is the default state; the client will be disconnected if it has no sessions
+	BrbDisabled BrbState = iota
+	// BrbEnabled allows the client to remain online without sessions; if a timeout is
+	// reached, it will be removed
+	BrbEnabled
+	// 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 {
+	// XXX we use client.stateMutex for synchronization, so we can atomically test
+	// conditions that use both brbTimer.state and client.sessions. This code
+	// is tightly coupled with the rest of Client.
+	client *Client
+
+	state    BrbState
+	duration time.Duration
+	timer    *time.Timer
+}
+
+func (bt *BrbTimer) Initialize(client *Client) {
+	bt.client = client
+}
+
+// attempts to enable BRB for a client, returns whether it succeeded
+func (bt *BrbTimer) Enable() (success bool, duration time.Duration) {
+	// BRB only makes sense if a new connection can attach to the session;
+	// this can happen either via RESUME or via bouncer reattach
+	if bt.client.Account() == "" && bt.client.ResumeID() == "" {
+		return
+	}
+
+	// TODO make this configurable
+	duration = ResumeableTotalTimeout
+
+	bt.client.stateMutex.Lock()
+	defer bt.client.stateMutex.Unlock()
+
+	switch bt.state {
+	case BrbDisabled, BrbEnabled:
+		bt.state = BrbEnabled
+		bt.duration = duration
+		bt.resetTimeout()
+		success = true
+	case BrbSticky:
+		success = true
+	default:
+		// BrbDead
+		success = false
+	}
+	return
+}
+
+// turns off BRB for a client and stops the timer; used on resume and during
+// client teardown
+func (bt *BrbTimer) Disable() {
+	bt.client.stateMutex.Lock()
+	defer bt.client.stateMutex.Unlock()
+
+	if bt.state == BrbEnabled {
+		bt.state = BrbDisabled
+	}
+	bt.resetTimeout()
+}
+
+func (bt *BrbTimer) resetTimeout() {
+	if bt.timer != nil {
+		bt.timer.Stop()
+	}
+	if bt.state != BrbEnabled {
+		return
+	}
+	if bt.timer == nil {
+		bt.timer = time.AfterFunc(bt.duration, bt.processTimeout)
+	} else {
+		bt.timer.Reset(bt.duration)
+	}
+}
+
+func (bt *BrbTimer) processTimeout() {
+	dead := false
+	defer func() {
+		if dead {
+			bt.client.Quit(bt.client.AwayMessage(), nil)
+			bt.client.destroy(nil)
+		}
+	}()
+
+	bt.client.stateMutex.Lock()
+	defer bt.client.stateMutex.Unlock()
+
+	switch bt.state {
+	case BrbDisabled, BrbEnabled:
+		if len(bt.client.sessions) == 0 {
+			// client never returned, quit them
+			bt.state = BrbDead
+			dead = true
+		} else {
+			// client resumed, reattached, or has another active session
+			bt.state = BrbDisabled
+		}
+	case BrbDead:
+		dead = true // shouldn't be possible but whatever
+	}
+	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/monitor.go

@@ -77,24 +77,6 @@ func (manager *MonitorManager) Remove(client *Client, nick string) error {
 	return nil
 }
 
-func (manager *MonitorManager) Resume(newClient, oldClient *Client) error {
-	manager.Lock()
-	defer manager.Unlock()
-
-	// newClient is now watching everyone oldClient was watching
-	oldTargets := manager.watching[oldClient]
-	delete(manager.watching, oldClient)
-	manager.watching[newClient] = oldTargets
-
-	// update watchedby as well
-	for watchedNick := range oldTargets {
-		delete(manager.watchedby[watchedNick], oldClient)
-		manager.watchedby[watchedNick][newClient] = true
-	}
-
-	return nil
-}
-
 // RemoveAll unregisters `client` from receiving notifications about *all* nicks.
 func (manager *MonitorManager) RemoveAll(client *Client) {
 	manager.Lock()

irc/nickserv.go

@@ -475,7 +475,7 @@ func nsGhostHandler(server *Server, client *Client, command string, params []str
 	}
 
 	ghost.Quit(fmt.Sprintf(ghost.t("GHOSTed by %s"), client.Nick()), nil)
-	ghost.destroy(false, nil)
+	ghost.destroy(nil)
 }
 
 func nsGroupHandler(server *Server, client *Client, command string, params []string, rb *ResponseBuffer) {

irc/resume.go

@@ -9,7 +9,7 @@ import (
 	"github.com/oragono/oragono/irc/utils"
 )
 
-// implements draft/resume-0.3, in particular the issuing, management, and verification
+// implements draft/resume, in particular the issuing, management, and verification
 // of resume tokens with two components: a unique ID and a secret key
 
 type resumeTokenPair struct {
@@ -31,8 +31,8 @@ func (rm *ResumeManager) Initialize(server *Server) {
 
 // GenerateToken generates a resume token for a client. If the client has
 // already been assigned one, it returns "".
-func (rm *ResumeManager) GenerateToken(client *Client) (token string) {
+func (rm *ResumeManager) GenerateToken(client *Client) (token string, id string) {
-	id := utils.GenerateSecretToken()
+	id = utils.GenerateSecretToken()
 	secret := utils.GenerateSecretToken()
 
 	rm.Lock()
@@ -48,13 +48,13 @@ func (rm *ResumeManager) GenerateToken(client *Client) (token string) {
 		secret: secret,
 	}
 
-	return id + secret
+	return id + secret, id
 }
 
 // VerifyToken looks up the client corresponding to a resume token, returning
 // nil if there is no such client or the token is invalid. If successful,
 // the token is consumed and cannot be used to resume again.
-func (rm *ResumeManager) VerifyToken(token string) (client *Client) {
+func (rm *ResumeManager) VerifyToken(newClient *Client, token string) (oldClient *Client, id string) {
 	if len(token) != 2*utils.SecretTokenLength {
 		return
 	}
@@ -62,18 +62,32 @@ func (rm *ResumeManager) VerifyToken(token string) (client *Client) {
 	rm.Lock()
 	defer rm.Unlock()
 
-	id := token[:utils.SecretTokenLength]
+	id = token[:utils.SecretTokenLength]
 	pair, ok := rm.resumeIDtoCreds[id]
-	if ok {
+	if !ok {
-		if utils.SecretTokensMatch(pair.secret, token[utils.SecretTokenLength:]) {
+		return
+	}
 	// disallow resume of an unregistered client; this prevents the use of
 	// resume as an auth bypass
-			if pair.client.Registered() {
+	if !pair.client.Registered() {
+		return
+	}
+
+	if utils.SecretTokensMatch(pair.secret, token[utils.SecretTokenLength:]) {
+		oldClient = pair.client // success!
 		// consume the token, ensuring that at most one resume can succeed
 		delete(rm.resumeIDtoCreds, id)
-				return pair.client
+		// old client is henceforth resumeable under new client's creds (possibly empty)
+		newResumeID := newClient.ResumeID()
+		oldClient.SetResumeID(newResumeID)
+		if newResumeID != "" {
+			if newResumeCreds, ok := rm.resumeIDtoCreds[newResumeID]; ok {
+				newResumeCreds.client = oldClient
+				rm.resumeIDtoCreds[newResumeID] = newResumeCreds
 			}
 		}
+		// new client no longer "owns" newResumeID, remove the association
+		newClient.SetResumeID("")
 	}
 	return
 }

irc/server.go

@@ -331,14 +331,13 @@ func (server *Server) createListener(addr string, tlsConfig *tls.Config, isTor b
 //
 
 func (server *Server) tryRegister(c *Client, session *Session) {
-	resumed := false
+	// if the session just sent us a RESUME line, try to resume
-	// try to complete registration, either via RESUME token or normally
+	if session.resumeDetails != nil {
-	if c.resumeDetails != nil {
+		session.tryResume()
-		if !c.tryResume() {
+		return // whether we succeeded or failed, either way `c` is not getting registered
-			return
 	}
-		resumed = true
+
-	} else {
+	// try to complete registration normally
 	if c.preregNick == "" || !c.HasUsername() || session.capState == caps.NegotiatingState {
 		return
 	}
@@ -348,7 +347,7 @@ func (server *Server) tryRegister(c *Client, session *Session) {
 	config := server.Config()
 	if !c.isAuthorized(config) {
 		c.Quit(c.t("Bad password"), nil)
-			c.destroy(false, nil)
+		c.destroy(nil)
 		return
 	}
 
@@ -364,10 +363,9 @@ func (server *Server) tryRegister(c *Client, session *Session) {
 	isBanned, info := server.klines.CheckMasks(c.AllNickmasks()...)
 	if isBanned {
 		c.Quit(info.BanMessage(c.t("You are banned from this server (%s)")), nil)
-			c.destroy(false, nil)
+		c.destroy(nil)
 		return
 	}
-	}
 
 	if session.client != c {
 		// reattached, bail out.
@@ -384,12 +382,8 @@ func (server *Server) tryRegister(c *Client, session *Session) {
 
 	server.playRegistrationBurst(session)
 
-	if resumed {
-		c.tryResumeChannels()
-	} else {
 	server.monitorManager.AlertAbout(c, true)
 }
-}
 
 func (server *Server) playRegistrationBurst(session *Session) {
 	c := session.client