source: code/trunk/user.go@ 771

package soju

import (
        "context"
        "crypto/sha256"
        "encoding/binary"
        "encoding/hex"
        "fmt"
        "math/big"
        "net"
        "sort"
        "time"

        "gopkg.in/irc.v3"
)

type event interface{}

type eventUpstreamMessage struct {
        msg *irc.Message
        uc  *upstreamConn
}

type eventUpstreamConnectionError struct {
        net *network
        err error
}

type eventUpstreamConnected struct {
        uc *upstreamConn
}

type eventUpstreamDisconnected struct {
        uc *upstreamConn
}

type eventUpstreamError struct {
        uc  *upstreamConn
        err error
}

type eventDownstreamMessage struct {
        msg *irc.Message
        dc  *downstreamConn
}

type eventDownstreamConnected struct {
        dc *downstreamConn
}

type eventDownstreamDisconnected struct {
        dc *downstreamConn
}

type eventChannelDetach struct {
        uc   *upstreamConn
        name string
}

type eventBroadcast struct {
        msg *irc.Message
}

type eventStop struct{}

type eventUserUpdate struct {
        password *string
        admin    *bool
        done     chan error
}

type deliveredClientMap map[string]string // client name -> msg ID

type deliveredStore struct {
        m deliveredCasemapMap
}

func newDeliveredStore() deliveredStore {
        return deliveredStore{deliveredCasemapMap{newCasemapMap(0)}}
}

func (ds deliveredStore) HasTarget(target string) bool {
        return ds.m.Value(target) != nil
}

func (ds deliveredStore) LoadID(target, clientName string) string {
        clients := ds.m.Value(target)
        if clients == nil {
                return ""
        }
        return clients[clientName]
}

func (ds deliveredStore) StoreID(target, clientName, msgID string) {
        clients := ds.m.Value(target)
        if clients == nil {
                clients = make(deliveredClientMap)
                ds.m.SetValue(target, clients)
        }
        clients[clientName] = msgID
}

func (ds deliveredStore) ForEachTarget(f func(target string)) {
        for _, entry := range ds.m.innerMap {
                f(entry.originalKey)
        }
}

func (ds deliveredStore) ForEachClient(f func(clientName string)) {
        clients := make(map[string]struct{})
        for _, entry := range ds.m.innerMap {
                delivered := entry.value.(deliveredClientMap)
                for clientName := range delivered {
                        clients[clientName] = struct{}{}
                }
        }

        for clientName := range clients {
                f(clientName)
        }
}

type network struct {
        Network
        user    *user
        logger  Logger
        stopped chan struct{}

        conn      *upstreamConn
        channels  channelCasemapMap
        delivered deliveredStore
        lastError error
        casemap   casemapping
}

func newNetwork(user *user, record *Network, channels []Channel) *network {
        logger := &prefixLogger{user.logger, fmt.Sprintf("network %q: ", record.GetName())}

        m := channelCasemapMap{newCasemapMap(0)}
        for _, ch := range channels {
                ch := ch
                m.SetValue(ch.Name, &ch)
        }

        return &network{
                Network:   *record,
                user:      user,
                logger:    logger,
                stopped:   make(chan struct{}),
                channels:  m,
                delivered: newDeliveredStore(),
                casemap:   casemapRFC1459,
        }
}

func (net *network) forEachDownstream(f func(*downstreamConn)) {
        net.user.forEachDownstream(func(dc *downstreamConn) {
                if dc.network == nil && !dc.isMultiUpstream {
                        return
                }
                if dc.network != nil && dc.network != net {
                        return
                }
                f(dc)
        })
}

func (net *network) isStopped() bool {
        select {
        case <-net.stopped:
                return true
        default:
                return false
        }
}

func userIdent(u *User) string {
        // The ident is a string we will send to upstream servers in clear-text.
        // For privacy reasons, make sure it doesn't expose any meaningful user
        // metadata. We just use the base64-encoded hashed ID, so that people don't
        // start relying on the string being an integer or following a pattern.
        var b [64]byte
        binary.LittleEndian.PutUint64(b[:], uint64(u.ID))
        h := sha256.Sum256(b[:])
        return hex.EncodeToString(h[:16])
}

func (net *network) run() {
        if !net.Enabled {
                return
        }

        var lastTry time.Time
        backoff := newBackoffer(retryConnectMinDelay, retryConnectMaxDelay, retryConnectJitter)
        for {
                if net.isStopped() {
                        return
                }

                delay := backoff.Next() - time.Now().Sub(lastTry)
                if delay > 0 {
                        net.logger.Printf("waiting %v before trying to reconnect to %q", delay.Truncate(time.Second), net.Addr)
                        time.Sleep(delay)
                }
                lastTry = time.Now()

                net.user.srv.metrics.upstreams.Add(1)

                uc, err := connectToUpstream(context.TODO(), net)
                if err != nil {
                        net.logger.Printf("failed to connect to upstream server %q: %v", net.Addr, err)
                        net.user.events <- eventUpstreamConnectionError{net, fmt.Errorf("failed to connect: %v", err)}
                        net.user.srv.metrics.upstreams.Add(-1)
                        net.user.srv.metrics.upstreamConnectErrorsTotal.Inc()
                        continue
                }

                if net.user.srv.Identd != nil {
                        net.user.srv.Identd.Store(uc.RemoteAddr().String(), uc.LocalAddr().String(), userIdent(&net.user.User))
                }

                uc.register()
                if err := uc.runUntilRegistered(); err != nil {
                        text := err.Error()
                        temp := true
                        if regErr, ok := err.(registrationError); ok {
                                text = regErr.Reason()
                                temp = regErr.Temporary()
                        }
                        uc.logger.Printf("failed to register: %v", text)
                        net.user.events <- eventUpstreamConnectionError{net, fmt.Errorf("failed to register: %v", text)}
                        uc.Close()
                        net.user.srv.metrics.upstreams.Add(-1)
                        net.user.srv.metrics.upstreamConnectErrorsTotal.Inc()
                        if !temp {
                                return
                        }
                        continue
                }

                // TODO: this is racy with net.stopped. If the network is stopped
                // before the user goroutine receives eventUpstreamConnected, the
                // connection won't be closed.
                net.user.events <- eventUpstreamConnected{uc}
                if err := uc.readMessages(net.user.events); err != nil {
                        uc.logger.Printf("failed to handle messages: %v", err)
                        net.user.events <- eventUpstreamError{uc, fmt.Errorf("failed to handle messages: %v", err)}
                }
                uc.Close()
                net.user.events <- eventUpstreamDisconnected{uc}

                if net.user.srv.Identd != nil {
                        net.user.srv.Identd.Delete(uc.RemoteAddr().String(), uc.LocalAddr().String())
                }

                net.user.srv.metrics.upstreams.Add(-1)
                backoff.Reset()
        }
}

func (net *network) stop() {
        if !net.isStopped() {
                close(net.stopped)
        }

        if net.conn != nil {
                net.conn.Close()
        }
}

func (net *network) detach(ch *Channel) {
        if ch.Detached {
                return
        }

        net.logger.Printf("detaching channel %q", ch.Name)

        ch.Detached = true

        if net.user.msgStore != nil {
                nameCM := net.casemap(ch.Name)
                lastID, err := net.user.msgStore.LastMsgID(&net.Network, nameCM, time.Now())
                if err != nil {
                        net.logger.Printf("failed to get last message ID for channel %q: %v", ch.Name, err)
                }
                ch.DetachedInternalMsgID = lastID
        }

        if net.conn != nil {
                uch := net.conn.channels.Value(ch.Name)
                if uch != nil {
                        uch.updateAutoDetach(0)
                }
        }

        net.forEachDownstream(func(dc *downstreamConn) {
                dc.SendMessage(&irc.Message{
                        Prefix:  dc.prefix(),
                        Command: "PART",
                        Params:  []string{dc.marshalEntity(net, ch.Name), "Detach"},
                })
        })
}

func (net *network) attach(ch *Channel) {
        if !ch.Detached {
                return
        }

        net.logger.Printf("attaching channel %q", ch.Name)

        detachedMsgID := ch.DetachedInternalMsgID
        ch.Detached = false
        ch.DetachedInternalMsgID = ""

        var uch *upstreamChannel
        if net.conn != nil {
                uch = net.conn.channels.Value(ch.Name)

                net.conn.updateChannelAutoDetach(ch.Name)
        }

        net.forEachDownstream(func(dc *downstreamConn) {
                dc.SendMessage(&irc.Message{
                        Prefix:  dc.prefix(),
                        Command: "JOIN",
                        Params:  []string{dc.marshalEntity(net, ch.Name)},
                })

                if uch != nil {
                        forwardChannel(dc, uch)
                }

                if detachedMsgID != "" {
                        dc.sendTargetBacklog(context.TODO(), net, ch.Name, detachedMsgID)
                }
        })
}

func (net *network) deleteChannel(ctx context.Context, name string) error {
        ch := net.channels.Value(name)
        if ch == nil {
                return fmt.Errorf("unknown channel %q", name)
        }
        if net.conn != nil {
                uch := net.conn.channels.Value(ch.Name)
                if uch != nil {
                        uch.updateAutoDetach(0)
                }
        }

        if err := net.user.srv.db.DeleteChannel(ctx, ch.ID); err != nil {
                return err
        }
        net.channels.Delete(name)
        return nil
}

func (net *network) updateCasemapping(newCasemap casemapping) {
        net.casemap = newCasemap
        net.channels.SetCasemapping(newCasemap)
        net.delivered.m.SetCasemapping(newCasemap)
        if uc := net.conn; uc != nil {
                uc.channels.SetCasemapping(newCasemap)
                for _, entry := range uc.channels.innerMap {
                        uch := entry.value.(*upstreamChannel)
                        uch.Members.SetCasemapping(newCasemap)
                }
                uc.monitored.SetCasemapping(newCasemap)
        }
        net.forEachDownstream(func(dc *downstreamConn) {
                dc.monitored.SetCasemapping(newCasemap)
        })
}

func (net *network) storeClientDeliveryReceipts(ctx context.Context, clientName string) {
        if !net.user.hasPersistentMsgStore() {
                return
        }

        var receipts []DeliveryReceipt
        net.delivered.ForEachTarget(func(target string) {
                msgID := net.delivered.LoadID(target, clientName)
                if msgID == "" {
                        return
                }
                receipts = append(receipts, DeliveryReceipt{
                        Target:        target,
                        InternalMsgID: msgID,
                })
        })

        if err := net.user.srv.db.StoreClientDeliveryReceipts(ctx, net.ID, clientName, receipts); err != nil {
                net.logger.Printf("failed to store delivery receipts for client %q: %v", clientName, err)
        }
}

func (net *network) isHighlight(msg *irc.Message) bool {
        if msg.Command != "PRIVMSG" && msg.Command != "NOTICE" {
                return false
        }

        text := msg.Params[1]

        nick := net.Nick
        if net.conn != nil {
                nick = net.conn.nick
        }

        // TODO: use case-mapping aware comparison here
        return msg.Prefix.Name != nick && isHighlight(text, nick)
}

func (net *network) detachedMessageNeedsRelay(ch *Channel, msg *irc.Message) bool {
        highlight := net.isHighlight(msg)
        return ch.RelayDetached == FilterMessage || ((ch.RelayDetached == FilterHighlight || ch.RelayDetached == FilterDefault) && highlight)
}

func (net *network) autoSaveSASLPlain(ctx context.Context, username, password string) {
        // User may have e.g. EXTERNAL mechanism configured. We do not want to
        // automatically erase the key pair or any other credentials.
        if net.SASL.Mechanism != "" && net.SASL.Mechanism != "PLAIN" {
                return
        }

        net.logger.Printf("auto-saving SASL PLAIN credentials with username %q", username)
        net.SASL.Mechanism = "PLAIN"
        net.SASL.Plain.Username = username
        net.SASL.Plain.Password = password
        if err := net.user.srv.db.StoreNetwork(ctx, net.user.ID, &net.Network); err != nil {
                net.logger.Printf("failed to save SASL PLAIN credentials: %v", err)
        }
}

type user struct {
        User
        srv    *Server
        logger Logger

        events chan event
        done   chan struct{}

        networks        []*network
        downstreamConns []*downstreamConn
        msgStore        messageStore
}

func newUser(srv *Server, record *User) *user {
        logger := &prefixLogger{srv.Logger, fmt.Sprintf("user %q: ", record.Username)}

        var msgStore messageStore
        if logPath := srv.Config().LogPath; logPath != "" {
                msgStore = newFSMessageStore(logPath, record.Username)
        } else {
                msgStore = newMemoryMessageStore()
        }

        return &user{
                User:     *record,
                srv:      srv,
                logger:   logger,
                events:   make(chan event, 64),
                done:     make(chan struct{}),
                msgStore: msgStore,
        }
}

func (u *user) forEachUpstream(f func(uc *upstreamConn)) {
        for _, network := range u.networks {
                if network.conn == nil {
                        continue
                }
                f(network.conn)
        }
}

func (u *user) forEachDownstream(f func(dc *downstreamConn)) {
        for _, dc := range u.downstreamConns {
                f(dc)
        }
}

func (u *user) getNetwork(name string) *network {
        for _, network := range u.networks {
                if network.Addr == name {
                        return network
                }
                if network.Name != "" && network.Name == name {
                        return network
                }
        }
        return nil
}

func (u *user) getNetworkByID(id int64) *network {
        for _, net := range u.networks {
                if net.ID == id {
                        return net
                }
        }
        return nil
}

func (u *user) run() {
        defer func() {
                if u.msgStore != nil {
                        if err := u.msgStore.Close(); err != nil {
                                u.logger.Printf("failed to close message store for user %q: %v", u.Username, err)
                        }
                }
                close(u.done)
        }()

        networks, err := u.srv.db.ListNetworks(context.TODO(), u.ID)
        if err != nil {
                u.logger.Printf("failed to list networks for user %q: %v", u.Username, err)
                return
        }

        sort.Slice(networks, func(i, j int) bool {
                return networks[i].ID < networks[j].ID
        })

        for _, record := range networks {
                record := record
                channels, err := u.srv.db.ListChannels(context.TODO(), record.ID)
                if err != nil {
                        u.logger.Printf("failed to list channels for user %q, network %q: %v", u.Username, record.GetName(), err)
                        continue
                }

                network := newNetwork(u, &record, channels)
                u.networks = append(u.networks, network)

                if u.hasPersistentMsgStore() {
                        receipts, err := u.srv.db.ListDeliveryReceipts(context.TODO(), record.ID)
                        if err != nil {
                                u.logger.Printf("failed to load delivery receipts for user %q, network %q: %v", u.Username, network.GetName(), err)
                                return
                        }

                        for _, rcpt := range receipts {
                                network.delivered.StoreID(rcpt.Target, rcpt.Client, rcpt.InternalMsgID)
                        }
                }

                go network.run()
        }

        for e := range u.events {
                switch e := e.(type) {
                case eventUpstreamConnected:
                        uc := e.uc

                        uc.network.conn = uc

                        uc.updateAway()
                        uc.updateMonitor()

                        netIDStr := fmt.Sprintf("%v", uc.network.ID)
                        uc.forEachDownstream(func(dc *downstreamConn) {
                                dc.updateSupportedCaps()

                                if !dc.caps["soju.im/bouncer-networks"] {
                                        sendServiceNOTICE(dc, fmt.Sprintf("connected to %s", uc.network.GetName()))
                                }

                                dc.updateNick()
                                dc.updateRealname()
                                dc.updateAccount()
                        })
                        u.forEachDownstream(func(dc *downstreamConn) {
                                if dc.caps["soju.im/bouncer-networks-notify"] {
                                        dc.SendMessage(&irc.Message{
                                                Prefix:  dc.srv.prefix(),
                                                Command: "BOUNCER",
                                                Params:  []string{"NETWORK", netIDStr, "state=connected"},
                                        })
                                }
                        })
                        uc.network.lastError = nil
                case eventUpstreamDisconnected:
                        u.handleUpstreamDisconnected(e.uc)
                case eventUpstreamConnectionError:
                        net := e.net

                        stopped := false
                        select {
                        case <-net.stopped:
                                stopped = true
                        default:
                        }

                        if !stopped && (net.lastError == nil || net.lastError.Error() != e.err.Error()) {
                                net.forEachDownstream(func(dc *downstreamConn) {
                                        sendServiceNOTICE(dc, fmt.Sprintf("failed connecting/registering to %s: %v", net.GetName(), e.err))
                                })
                        }
                        net.lastError = e.err
                case eventUpstreamError:
                        uc := e.uc

                        uc.forEachDownstream(func(dc *downstreamConn) {
                                sendServiceNOTICE(dc, fmt.Sprintf("disconnected from %s: %v", uc.network.GetName(), e.err))
                        })
                        uc.network.lastError = e.err
                case eventUpstreamMessage:
                        msg, uc := e.msg, e.uc
                        if uc.isClosed() {
                                uc.logger.Printf("ignoring message on closed connection: %v", msg)
                                break
                        }
                        if err := uc.handleMessage(context.TODO(), msg); err != nil {
                                uc.logger.Printf("failed to handle message %q: %v", msg, err)
                        }
                case eventChannelDetach:
                        uc, name := e.uc, e.name
                        c := uc.network.channels.Value(name)
                        if c == nil || c.Detached {
                                continue
                        }
                        uc.network.detach(c)
                        if err := uc.srv.db.StoreChannel(context.TODO(), uc.network.ID, c); err != nil {
                                u.logger.Printf("failed to store updated detached channel %q: %v", c.Name, err)
                        }
                case eventDownstreamConnected:
                        dc := e.dc

                        if dc.network != nil {
                                dc.monitored.SetCasemapping(dc.network.casemap)
                        }

                        if err := dc.welcome(context.TODO()); err != nil {
                                dc.logger.Printf("failed to handle new registered connection: %v", err)
                                break
                        }

                        u.downstreamConns = append(u.downstreamConns, dc)

                        dc.forEachNetwork(func(network *network) {
                                if network.lastError != nil {
                                        sendServiceNOTICE(dc, fmt.Sprintf("disconnected from %s: %v", network.GetName(), network.lastError))
                                }
                        })

                        u.forEachUpstream(func(uc *upstreamConn) {
                                uc.updateAway()
                        })
                case eventDownstreamDisconnected:
                        dc := e.dc

                        for i := range u.downstreamConns {
                                if u.downstreamConns[i] == dc {
                                        u.downstreamConns = append(u.downstreamConns[:i], u.downstreamConns[i+1:]...)
                                        break
                                }
                        }

                        dc.forEachNetwork(func(net *network) {
                                net.storeClientDeliveryReceipts(context.TODO(), dc.clientName)
                        })

                        u.forEachUpstream(func(uc *upstreamConn) {
                                uc.cancelPendingCommandsByDownstreamID(dc.id)
                                uc.updateAway()
                                uc.updateMonitor()
                        })
                case eventDownstreamMessage:
                        msg, dc := e.msg, e.dc
                        if dc.isClosed() {
                                dc.logger.Printf("ignoring message on closed connection: %v", msg)
                                break
                        }
                        err := dc.handleMessage(context.TODO(), msg)
                        if ircErr, ok := err.(ircError); ok {
                                ircErr.Message.Prefix = dc.srv.prefix()
                                dc.SendMessage(ircErr.Message)
                        } else if err != nil {
                                dc.logger.Printf("failed to handle message %q: %v", msg, err)
                                dc.Close()
                        }
                case eventBroadcast:
                        msg := e.msg
                        u.forEachDownstream(func(dc *downstreamConn) {
                                dc.SendMessage(msg)
                        })
                case eventUserUpdate:
                        // copy the user record because we'll mutate it
                        record := u.User

                        if e.password != nil {
                                record.Password = *e.password
                        }
                        if e.admin != nil {
                                record.Admin = *e.admin
                        }

                        e.done <- u.updateUser(context.TODO(), &record)

                        // If the password was updated, kill all downstream connections to
                        // force them to re-authenticate with the new credentials.
                        if e.password != nil {
                                u.forEachDownstream(func(dc *downstreamConn) {
                                        dc.Close()
                                })
                        }
                case eventStop:
                        u.forEachDownstream(func(dc *downstreamConn) {
                                dc.Close()
                        })
                        for _, n := range u.networks {
                                n.stop()

                                n.delivered.ForEachClient(func(clientName string) {
                                        n.storeClientDeliveryReceipts(context.TODO(), clientName)
                                })
                        }
                        return
                default:
                        panic(fmt.Sprintf("received unknown event type: %T", e))
                }
        }
}

func (u *user) handleUpstreamDisconnected(uc *upstreamConn) {
        uc.network.conn = nil

        uc.abortPendingCommands()

        for _, entry := range uc.channels.innerMap {
                uch := entry.value.(*upstreamChannel)
                uch.updateAutoDetach(0)
        }

        netIDStr := fmt.Sprintf("%v", uc.network.ID)
        uc.forEachDownstream(func(dc *downstreamConn) {
                dc.updateSupportedCaps()
        })

        // If the network has been removed, don't send a state change notification
        found := false
        for _, net := range u.networks {
                if net == uc.network {
                        found = true
                        break
                }
        }
        if !found {
                return
        }

        u.forEachDownstream(func(dc *downstreamConn) {
                if dc.caps["soju.im/bouncer-networks-notify"] {
                        dc.SendMessage(&irc.Message{
                                Prefix:  dc.srv.prefix(),
                                Command: "BOUNCER",
                                Params:  []string{"NETWORK", netIDStr, "state=disconnected"},
                        })
                }
        })

        if uc.network.lastError == nil {
                uc.forEachDownstream(func(dc *downstreamConn) {
                        if !dc.caps["soju.im/bouncer-networks"] {
                                sendServiceNOTICE(dc, fmt.Sprintf("disconnected from %s", uc.network.GetName()))
                        }
                })
        }
}

func (u *user) addNetwork(network *network) {
        u.networks = append(u.networks, network)

        sort.Slice(u.networks, func(i, j int) bool {
                return u.networks[i].ID < u.networks[j].ID
        })

        go network.run()
}

func (u *user) removeNetwork(network *network) {
        network.stop()

        u.forEachDownstream(func(dc *downstreamConn) {
                if dc.network != nil && dc.network == network {
                        dc.Close()
                }
        })

        for i, net := range u.networks {
                if net == network {
                        u.networks = append(u.networks[:i], u.networks[i+1:]...)
                        return
                }
        }

        panic("tried to remove a non-existing network")
}

func (u *user) checkNetwork(record *Network) error {
        url, err := record.URL()
        if err != nil {
                return err
        }
        if url.User != nil {
                return fmt.Errorf("%v:// URL must not have username and password information", url.Scheme)
        }
        if url.RawQuery != "" {
                return fmt.Errorf("%v:// URL must not have query values", url.Scheme)
        }
        if url.Fragment != "" {
                return fmt.Errorf("%v:// URL must not have a fragment", url.Scheme)
        }
        switch url.Scheme {
        case "ircs", "irc+insecure":
                if url.Host == "" {
                        return fmt.Errorf("%v:// URL must have a host", url.Scheme)
                }
                if url.Path != "" {
                        return fmt.Errorf("%v:// URL must not have a path", url.Scheme)
                }
        case "irc+unix", "unix":
                if url.Host != "" {
                        return fmt.Errorf("%v:// URL must not have a host", url.Scheme)
                }
                if url.Path == "" {
                        return fmt.Errorf("%v:// URL must have a path", url.Scheme)
                }
        default:
                return fmt.Errorf("unknown URL scheme %q", url.Scheme)
        }

        for _, net := range u.networks {
                if net.GetName() == record.GetName() && net.ID != record.ID {
                        return fmt.Errorf("a network with the name %q already exists", record.GetName())
                }
        }

        return nil
}

func (u *user) createNetwork(ctx context.Context, record *Network) (*network, error) {
        if record.ID != 0 {
                panic("tried creating an already-existing network")
        }

        if err := u.checkNetwork(record); err != nil {
                return nil, err
        }

        if max := u.srv.Config().MaxUserNetworks; max >= 0 && len(u.networks) >= max {
                return nil, fmt.Errorf("maximum number of networks reached")
        }

        network := newNetwork(u, record, nil)
        err := u.srv.db.StoreNetwork(ctx, u.ID, &network.Network)
        if err != nil {
                return nil, err
        }

        u.addNetwork(network)

        idStr := fmt.Sprintf("%v", network.ID)
        attrs := getNetworkAttrs(network)
        u.forEachDownstream(func(dc *downstreamConn) {
                if dc.caps["soju.im/bouncer-networks-notify"] {
                        dc.SendMessage(&irc.Message{
                                Prefix:  dc.srv.prefix(),
                                Command: "BOUNCER",
                                Params:  []string{"NETWORK", idStr, attrs.String()},
                        })
                }
        })

        return network, nil
}

func (u *user) updateNetwork(ctx context.Context, record *Network) (*network, error) {
        if record.ID == 0 {
                panic("tried updating a new network")
        }

        // If the realname is reset to the default, just wipe the per-network
        // setting
        if record.Realname == u.Realname {
                record.Realname = ""
        }

        if err := u.checkNetwork(record); err != nil {
                return nil, err
        }

        network := u.getNetworkByID(record.ID)
        if network == nil {
                panic("tried updating a non-existing network")
        }

        if err := u.srv.db.StoreNetwork(ctx, u.ID, record); err != nil {
                return nil, err
        }

        // Most network changes require us to re-connect to the upstream server

        channels := make([]Channel, 0, network.channels.Len())
        for _, entry := range network.channels.innerMap {
                ch := entry.value.(*Channel)
                channels = append(channels, *ch)
        }

        updatedNetwork := newNetwork(u, record, channels)

        // If we're currently connected, disconnect and perform the necessary
        // bookkeeping
        if network.conn != nil {
                network.stop()
                // Note: this will set network.conn to nil
                u.handleUpstreamDisconnected(network.conn)
        }

        // Patch downstream connections to use our fresh updated network
        u.forEachDownstream(func(dc *downstreamConn) {
                if dc.network != nil && dc.network == network {
                        dc.network = updatedNetwork
                }
        })

        // We need to remove the network after patching downstream connections,
        // otherwise they'll get closed
        u.removeNetwork(network)

        // The filesystem message store needs to be notified whenever the network
        // is renamed
        fsMsgStore, isFS := u.msgStore.(*fsMessageStore)
        if isFS && updatedNetwork.GetName() != network.GetName() {
                if err := fsMsgStore.RenameNetwork(&network.Network, &updatedNetwork.Network); err != nil {
                        network.logger.Printf("failed to update FS message store network name to %q: %v", updatedNetwork.GetName(), err)
                }
        }

        // This will re-connect to the upstream server
        u.addNetwork(updatedNetwork)

        // TODO: only broadcast attributes that have changed
        idStr := fmt.Sprintf("%v", updatedNetwork.ID)
        attrs := getNetworkAttrs(updatedNetwork)
        u.forEachDownstream(func(dc *downstreamConn) {
                if dc.caps["soju.im/bouncer-networks-notify"] {
                        dc.SendMessage(&irc.Message{
                                Prefix:  dc.srv.prefix(),
                                Command: "BOUNCER",
                                Params:  []string{"NETWORK", idStr, attrs.String()},
                        })
                }
        })

        return updatedNetwork, nil
}

func (u *user) deleteNetwork(ctx context.Context, id int64) error {
        network := u.getNetworkByID(id)
        if network == nil {
                panic("tried deleting a non-existing network")
        }

        if err := u.srv.db.DeleteNetwork(ctx, network.ID); err != nil {
                return err
        }

        u.removeNetwork(network)

        idStr := fmt.Sprintf("%v", network.ID)
        u.forEachDownstream(func(dc *downstreamConn) {
                if dc.caps["soju.im/bouncer-networks-notify"] {
                        dc.SendMessage(&irc.Message{
                                Prefix:  dc.srv.prefix(),
                                Command: "BOUNCER",
                                Params:  []string{"NETWORK", idStr, "*"},
                        })
                }
        })

        return nil
}

func (u *user) updateUser(ctx context.Context, record *User) error {
        if u.ID != record.ID {
                panic("ID mismatch when updating user")
        }

        realnameUpdated := u.Realname != record.Realname
        if err := u.srv.db.StoreUser(ctx, record); err != nil {
                return fmt.Errorf("failed to update user %q: %v", u.Username, err)
        }
        u.User = *record

        if realnameUpdated {
                // Re-connect to networks which use the default realname
                var needUpdate []Network
                for _, net := range u.networks {
                        if net.Realname == "" {
                                needUpdate = append(needUpdate, net.Network)
                        }
                }

                var netErr error
                for _, net := range needUpdate {
                        if _, err := u.updateNetwork(ctx, &net); err != nil {
                                netErr = err
                        }
                }
                if netErr != nil {
                        return netErr
                }
        }

        return nil
}

func (u *user) stop() {
        u.events <- eventStop{}
        <-u.done
}

func (u *user) hasPersistentMsgStore() bool {
        if u.msgStore == nil {
                return false
        }
        _, isMem := u.msgStore.(*memoryMessageStore)
        return !isMem
}

// localAddrForHost returns the local address to use when connecting to host.
// A nil address is returned when the OS should automatically pick one.
func (u *user) localTCPAddrForHost(ctx context.Context, host string) (*net.TCPAddr, error) {
        upstreamUserIPs := u.srv.Config().UpstreamUserIPs
        if len(upstreamUserIPs) == 0 {
                return nil, nil
        }

        ips, err := net.DefaultResolver.LookupIP(ctx, "ip", host)
        if err != nil {
                return nil, err
        }

        wantIPv6 := false
        for _, ip := range ips {
                if ip.To4() == nil {
                        wantIPv6 = true
                        break
                }
        }

        var ipNet *net.IPNet
        for _, in := range upstreamUserIPs {
                if wantIPv6 == (in.IP.To4() == nil) {
                        ipNet = in
                        break
                }
        }
        if ipNet == nil {
                return nil, nil
        }

        var ipInt big.Int
        ipInt.SetBytes(ipNet.IP)
        ipInt.Add(&ipInt, big.NewInt(u.ID+1))
        ip := net.IP(ipInt.Bytes())
        if !ipNet.Contains(ip) {
                return nil, fmt.Errorf("IP network %v too small", ipNet)
        }

        return &net.TCPAddr{IP: ip}, nil
}