Add support for detached channels

Channels can now be detached by leaving them with the reason "detach",
and re-attached by joining them again. Upon detaching the channel is
no longer forwarded to downstream connections. Upon re-attaching the
history buffer is sent.

db.go

@@ -46,6 +46,7 @@ type Channel struct {
 	ID       int64
 	Name     string
 	Key      string
+	Detached bool
 }
 
 const schema = `
@@ -76,6 +77,7 @@ CREATE TABLE Channel (
 	network INTEGER NOT NULL,
 	name VARCHAR(255) NOT NULL,
 	key VARCHAR(255),
+	detached INTEGER NOT NULL DEFAULT 0,
 	FOREIGN KEY(network) REFERENCES Network(id),
 	UNIQUE(network, name)
 );
@@ -84,6 +86,7 @@ CREATE TABLE Channel (
 var migrations = []string{
 	"", // migration #0 is reserved for schema initialization
 	"ALTER TABLE Network ADD COLUMN connect_commands VARCHAR(1023)",
+	"ALTER TABLE Channel ADD COLUMN detached INTEGER NOT NULL DEFAULT 0",
 }
 
 type DB struct {
@@ -346,7 +349,9 @@ func (db *DB) ListChannels(networkID int64) ([]Channel, error) {
 	db.lock.RLock()
 	defer db.lock.RUnlock()
 
-	rows, err := db.db.Query("SELECT id, name, key FROM Channel WHERE network = ?", networkID)
+	rows, err := db.db.Query(`SELECT id, name, key, detached
+		FROM Channel
+		WHERE network = ?`, networkID)
 	if err != nil {
 		return nil, err
 	}
@@ -356,7 +361,7 @@ func (db *DB) ListChannels(networkID int64) ([]Channel, error) {
 	for rows.Next() {
 		var ch Channel
 		var key *string
-		if err := rows.Scan(&ch.ID, &ch.Name, &key); err != nil {
+		if err := rows.Scan(&ch.ID, &ch.Name, &key, &ch.Detached); err != nil {
 			return nil, err
 		}
 		ch.Key = fromStringPtr(key)
@@ -378,12 +383,14 @@ func (db *DB) StoreChannel(networkID int64, ch *Channel) error {
 	var err error
 	if ch.ID != 0 {
 		_, err = db.db.Exec(`UPDATE Channel
-			SET network = ?, name = ?, key = ?
+			SET network = ?, name = ?, key = ?, detached = ?
-			WHERE id = ?`, networkID, ch.Name, key, ch.ID)
+			WHERE id = ?`,
+			networkID, ch.Name, key, ch.Detached, ch.ID)
 	} else {
 		var res sql.Result
-		res, err = db.db.Exec(`INSERT INTO Channel(network, name, key)
+		res, err = db.db.Exec(`INSERT INTO Channel(network, name, key, detached)
-			VALUES (?, ?, ?)`, networkID, ch.Name, key)
+			VALUES (?, ?, ?, ?)`,
+			networkID, ch.Name, key, ch.Detached)
 		if err != nil {
 			return err
 		}

doc/soju.1.scd

@@ -23,7 +23,8 @@ behalf of the user to provide extra features.
 When joining a channel, the channel will be saved and automatically joined on
 the next connection. When registering or authenticating with NickServ, the
 credentials will be saved and automatically used on the next connection if the
-server supports SASL.
+server supports SASL. When parting a channel with the reason "detach", the
+channel will be detached instead of being left.
 
 When all clients are disconnected from the bouncer, the user is automatically
 marked as away.

downstream.go

@@ -767,7 +767,13 @@ func (dc *downstreamConn) welcome() error {
 
 	dc.forEachUpstream(func(uc *upstreamConn) {
 		for _, ch := range uc.channels {
-			if ch.complete {
+			if !ch.complete {
+				continue
+			}
+			if record, ok := uc.network.channels[ch.Name]; ok && record.Detached {
+				continue
+			}
+
 			dc.SendMessage(&irc.Message{
 				Prefix:  dc.prefix(),
 				Command: "JOIN",
@@ -776,7 +782,6 @@ func (dc *downstreamConn) welcome() error {
 
 			forwardChannel(dc, ch)
 		}
-		}
 	})
 
 	dc.forEachNetwork(func(net *network) {
@@ -793,6 +798,10 @@ func (dc *downstreamConn) welcome() error {
 
 func (dc *downstreamConn) sendNetworkHistory(net *network) {
 	for target, history := range net.history {
+		if ch, ok := net.channels[target]; ok && ch.Detached {
+			continue
+		}
+
 		seq, ok := history.offlineClients[dc.clientName]
 		if !ok {
 			continue
@@ -945,7 +954,7 @@ func (dc *downstreamConn) handleMessageRegistered(msg *irc.Message) error {
 				Params:  params,
 			})
 
-			ch := &Channel{Name: upstreamName, Key: key}
+			ch := &Channel{Name: upstreamName, Key: key, Detached: false}
 			if err := uc.network.createUpdateChannel(ch); err != nil {
 				dc.logger.Printf("failed to create or update channel %q: %v", upstreamName, err)
 			}
@@ -967,6 +976,12 @@ func (dc *downstreamConn) handleMessageRegistered(msg *irc.Message) error {
 				return err
 			}
 
+			if strings.EqualFold(reason, "detach") {
+				ch := &Channel{Name: upstreamName, Detached: true}
+				if err := uc.network.createUpdateChannel(ch); err != nil {
+					dc.logger.Printf("failed to detach channel %q: %v", upstreamName, err)
+				}
+			} else {
 				params := []string{upstreamName}
 				if reason != "" {
 					params = append(params, reason)
@@ -980,6 +995,7 @@ func (dc *downstreamConn) handleMessageRegistered(msg *irc.Message) error {
 					dc.logger.Printf("failed to delete channel %q: %v", upstreamName, err)
 				}
 			}
+		}
 	case "KICK":
 		var channelStr, userStr string
 		if err := parseMessageParams(msg, &channelStr, &userStr); err != nil {

upstream.go

@@ -1405,8 +1405,13 @@ func (uc *upstreamConn) appendLog(entity string, msg *irc.Message) {
 
 // appendHistory appends a message to the history. entity can be empty.
 func (uc *upstreamConn) appendHistory(entity string, msg *irc.Message) {
+	detached := false
+	if ch, ok := uc.network.channels[entity]; ok {
+		detached = ch.Detached
+	}
+
 	// If no client is offline, no need to append the message to the buffer
-	if len(uc.network.offlineClients) == 0 {
+	if len(uc.network.offlineClients) == 0 && !detached {
 		return
 	}
 
@@ -1421,6 +1426,14 @@ func (uc *upstreamConn) appendHistory(entity string, msg *irc.Message) {
 		for clientName, _ := range uc.network.offlineClients {
 			history.offlineClients[clientName] = 0
 		}
+
+		if detached {
+			// If the channel is detached, online clients act as offline
+			// clients too
+			uc.forEachDownstream(func(dc *downstreamConn) {
+				history.offlineClients[dc.clientName] = 0
+			})
+		}
 	}
 
 	history.ring.Produce(msg)
@@ -1438,6 +1451,11 @@ func (uc *upstreamConn) produce(target string, msg *irc.Message, origin *downstr
 
 	uc.appendHistory(target, msg)
 
+	// Don't forward messages if it's a detached channel
+	if ch, ok := uc.network.channels[target]; ok && ch.Detached {
+		return
+	}
+
 	uc.forEachDownstream(func(dc *downstreamConn) {
 		if dc != origin || dc.caps["echo-message"] {
 			dc.SendMessage(dc.marshalMessage(msg, uc.network))

user.go

@@ -150,7 +150,51 @@ func (net *network) createUpdateChannel(ch *Channel) error {
 	if err := net.user.srv.db.StoreChannel(net.ID, ch); err != nil {
 		return err
 	}
+	prev := net.channels[ch.Name]
 	net.channels[ch.Name] = ch
+
+	if prev != nil && prev.Detached != ch.Detached {
+		history := net.history[ch.Name]
+		if ch.Detached {
+			net.user.srv.Logger.Printf("network %q: detaching channel %q", net.GetName(), ch.Name)
+			net.forEachDownstream(func(dc *downstreamConn) {
+				net.offlineClients[dc.clientName] = struct{}{}
+				if history != nil {
+					history.offlineClients[dc.clientName] = history.ring.Cur()
+				}
+
+				dc.SendMessage(&irc.Message{
+					Prefix:  dc.prefix(),
+					Command: "PART",
+					Params:  []string{dc.marshalEntity(net, ch.Name), "Detach"},
+				})
+			})
+		} else {
+			net.user.srv.Logger.Printf("network %q: attaching channel %q", net.GetName(), ch.Name)
+
+			var uch *upstreamChannel
+			if net.conn != nil {
+				uch = net.conn.channels[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 history != nil {
+					dc.sendNetworkHistory(net)
+				}
+			})
+		}
+	}
+
 	return nil
 }
 
@@ -342,7 +386,10 @@ func (u *user) run() {
 				}
 
 				net.offlineClients[dc.clientName] = struct{}{}
-				for _, history := range net.history {
+				for target, history := range net.history {
+					if ch, ok := net.channels[target]; ok && ch.Detached {
+						continue
+					}
 					history.offlineClients[dc.clientName] = history.ring.Cur()
 				}
 			})