Simplify the protocol and the protocol interface.

Split the id field into id and source, where source indicates the sender
of the message and id the entity being sent.  Remove the label request,
just use the offerer's username.  Maintain the username within the
ServerConnection, this removes a parameter from some methods.

README.FRONTEND

@@ -105,7 +105,6 @@ serverConnection.ondownstream = function(stream) {
     stream.onclose = ...;
     stream.onerror = ...;
     stream.ondowntrack = ...;
-    stream.onlabel = ...;
     stream.onstatus = ...;
 }
 ```
@@ -115,10 +114,6 @@ The `stream.labels` dictionary maps each track's id to one of `audio`,
 this point, you may set up an `audio` or `video` component straight away,
 or you may choose to wait until the `ondowntrack` callback is called.
 
-The server will usually invoke the `onlabel` callback in order to set
-a user-readable label on the stream; this is currently just the
-originating client's username.
-
 After a new stream is created, `ondowntrack` will be called whenever
 a track is added.  If the `MediaStream` passed to `ondowntrack` differs
 from the one previously received, then the stream has been torn down and

conn/conn.go

@@ -16,7 +16,7 @@ type Up interface {
 	AddLocal(Down) error
 	DelLocal(Down) bool
 	Id() string
-	Label() string
+	User() (string, string)
 	Codecs() []webrtc.RTPCodecCapability
 }
 

diskwriter/diskwriter.go

@@ -89,7 +89,7 @@ func (client *Client) Kick(id, user, message string) error {
 	return err
 }
 
-func (client *Client) PushConn(g *group.Group, id string, up conn.Up, tracks []conn.UpTrack, label string) error {
+func (client *Client) PushConn(g *group.Group, id string, up conn.Up, tracks []conn.UpTrack) error {
 	if client.group != g {
 		return nil
 	}
@@ -122,7 +122,7 @@ func (client *Client) PushConn(g *group.Group, id string, up conn.Up, tracks []c
 		client.down = make(map[string]*diskConn)
 	}
 
-	down, err := newDiskConn(client, directory, label, up, tracks)
+	down, err := newDiskConn(client, directory, up, tracks)
 	if err != nil {
 		g.WallOps("Write to disk: " + err.Error())
 		return err
@@ -135,7 +135,7 @@ func (client *Client) PushConn(g *group.Group, id string, up conn.Up, tracks []c
 type diskConn struct {
 	client    *Client
 	directory string
-	label     string
+	username  string
 	hasVideo  bool
 
 	mu            sync.Mutex
@@ -167,7 +167,7 @@ func (conn *diskConn) reopen() error {
 	}
 	conn.file = nil
 
-	file, err := openDiskFile(conn.directory, conn.label)
+	file, err := openDiskFile(conn.directory, conn.username)
 	if err != nil {
 		return err
 	}
@@ -196,15 +196,15 @@ func (conn *diskConn) Close() error {
 	return nil
 }
 
-func openDiskFile(directory, label string) (*os.File, error) {
+func openDiskFile(directory, username string) (*os.File, error) {
 	filenameFormat := "2006-01-02T15:04:05.000"
 	if runtime.GOOS == "windows" {
 		filenameFormat = "2006-01-02T15-04-05-000"
 	}
 
 	filename := time.Now().Format(filenameFormat)
-	if label != "" {
-		filename = filename + "-" + label
+	if username != "" {
+		filename = filename + "-" + username
 	}
 	for counter := 0; counter < 100; counter++ {
 		var fn string
@@ -240,11 +240,12 @@ type diskTrack struct {
 	lastKf uint32
 }
 
-func newDiskConn(client *Client, directory, label string, up conn.Up, remoteTracks []conn.UpTrack) (*diskConn, error) {
+func newDiskConn(client *Client, directory string, up conn.Up, remoteTracks []conn.UpTrack) (*diskConn, error) {
+	_, username := up.User()
 	conn := diskConn{
 		client:    client,
 		directory: directory,
-		label:     label,
+		username:  username,
 		tracks:    make([]*diskTrack, 0, len(remoteTracks)),
 		remote:    up,
 	}

group/client.go

@@ -98,7 +98,7 @@ type Client interface {
 	Challengeable
 	SetPermissions(ClientPermissions)
 	OverridePermissions(*Group) bool
-	PushConn(g *Group, id string, conn conn.Up, tracks []conn.UpTrack, label string) error
+	PushConn(g *Group, id string, conn conn.Up, tracks []conn.UpTrack) error
 	PushClient(id, username string, add bool) error
 }
 

rtpconn/rtpconn.go

@@ -308,7 +308,8 @@ func (up *rtpUpTrack) hasRtcpFb(tpe, parameter string) bool {
 
 type rtpUpConnection struct {
 	id            string
-	label         string
+	userId        string
+	username      string
 	pc            *webrtc.PeerConnection
 	labels        map[string]string
 	iceCandidates []*webrtc.ICECandidateInit
@@ -331,8 +332,8 @@ func (up *rtpUpConnection) Id() string {
 	return up.id
 }
 
-func (up *rtpUpConnection) Label() string {
-	return up.label
+func (up *rtpUpConnection) User() (string, string) {
+	return up.userId, up.username
 }
 
 func (up *rtpUpConnection) Codecs() []webrtc.RTPCodecCapability {
@@ -430,7 +431,7 @@ func pushConnNow(up *rtpUpConnection, g *group.Group, cs []group.Client) {
 	up.mu.Unlock()
 
 	for _, c := range cs {
-		c.PushConn(g, up.id, up, tracks, up.label)
+		c.PushConn(g, up.id, up, tracks)
 	}
 }
 

rtpconn/webclient.go

@@ -165,6 +165,7 @@ type clientMessage struct {
 	Type             string                     `json:"type"`
 	Kind             string                     `json:"kind,omitempty"`
 	Id               string                     `json:"id,omitempty"`
+	Source           string                     `json:"source,omitempty"`
 	Dest             string                     `json:"dest,omitempty"`
 	Username         string                     `json:"username,omitempty"`
 	Password         string                     `json:"password,omitempty"`
@@ -259,7 +260,7 @@ func delUpConn(c *webClient, id string) bool {
 	if g != nil {
 		go func(clients []group.Client) {
 			for _, c := range clients {
-				err := c.PushConn(g, conn.id, nil, nil, "")
+				err := c.PushConn(g, conn.id, nil, nil)
 				if err != nil {
 					log.Printf("PushConn: %v", err)
 				}
@@ -455,12 +456,16 @@ func negotiate(c *webClient, down *rtpDownConnection, renegotiate, restartIce bo
 		kind = "renegotiate"
 	}
 
+	source, username := down.remote.User()
+
 	return c.write(clientMessage{
-		Type:   "offer",
-		Kind:   kind,
-		Id:     down.id,
-		Offer:  &offer,
-		Labels: labels,
+		Type:     "offer",
+		Kind:     kind,
+		Id:       down.id,
+		Source:   source,
+		Username: username,
+		Offer:    &offer,
+		Labels:   labels,
 	})
 }
 
@@ -488,9 +493,9 @@ func gotOffer(c *webClient, id string, offer webrtc.SessionDescription, renegoti
 		return err
 	}
 
-	if u := c.Username(); u != "" {
-		up.label = u
-	}
+	up.userId = c.Id()
+	up.username = c.Username()
+
 	err = up.pc.SetRemoteDescription(offer)
 	if err != nil {
 		if renegotiate && !isnew {
@@ -644,17 +649,11 @@ func addDownConnTracks(c *webClient, remote conn.Up, tracks []conn.UpTrack) (*rt
 	return down, nil
 }
 
-func (c *webClient) PushConn(g *group.Group, id string, up conn.Up, tracks []conn.UpTrack, label string) error {
+func (c *webClient) PushConn(g *group.Group, id string, up conn.Up, tracks []conn.UpTrack) error {
 	err := c.action(pushConnAction{g, id, up, tracks})
 	if err != nil {
 		return err
 	}
-	if up != nil && label != "" {
-		err := c.action(addLabelAction{up.Id(), up.Label()})
-		if err != nil {
-			return err
-		}
-	}
 	return nil
 }
 
@@ -723,11 +722,6 @@ type pushConnAction struct {
 	tracks []conn.UpTrack
 }
 
-type addLabelAction struct {
-	id    string
-	label string
-}
-
 type pushConnsAction struct {
 	group  *group.Group
 	client group.Client
@@ -756,6 +750,13 @@ func clientLoop(c *webClient, ws *websocket.Conn) error {
 	ticker := time.NewTicker(10 * time.Second)
 	defer ticker.Stop()
 
+	err := c.write(clientMessage{
+		Type: "handshake",
+	})
+	if err != nil {
+		return err
+	}
+
 	for {
 		select {
 		case m, ok := <-read:
@@ -808,12 +809,6 @@ func clientLoop(c *webClient, ws *websocket.Conn) error {
 						continue
 					}
 				}
-			case addLabelAction:
-				c.write(clientMessage{
-					Type:  "label",
-					Id:    a.id,
-					Value: a.label,
-				})
 			case pushConnsAction:
 				g := c.group
 				if g == nil || a.group != g {
@@ -830,7 +825,7 @@ func clientLoop(c *webClient, ws *websocket.Conn) error {
 					}
 					go func(u *rtpUpConnection, ts []conn.UpTrack) {
 						err := a.client.PushConn(
-							g, u.id, u, ts, u.label,
+							g, u.id, u, ts,
 						)
 						if err != nil {
 							log.Printf(
@@ -855,7 +850,7 @@ func clientLoop(c *webClient, ws *websocket.Conn) error {
 					go c.PushConn(
 						c.group,
 						down.remote.Id(), down.remote,
-						tracks, down.remote.Label(),
+						tracks,
 					)
 				} else if up := getUpConn(c, a.id); up != nil {
 					c.write(clientMessage{
@@ -877,6 +872,7 @@ func clientLoop(c *webClient, ws *websocket.Conn) error {
 					Type:             "joined",
 					Kind:             "change",
 					Group:            g.Name(),
+					Username:         c.username,
 					Permissions:      &perms,
 					RTCConfiguration: ice.ICEConfiguration(),
 				})
@@ -1020,6 +1016,20 @@ func kickClient(g *group.Group, id, user, dest string, message string) error {
 }
 
 func handleClientMessage(c *webClient, m clientMessage) error {
+	if m.Source != "" {
+		if m.Source != c.Id() {
+			return group.ProtocolError("spoofed client id")
+		}
+	}
+
+	if m.Type != "join" {
+		if m.Username != "" {
+			if m.Username != c.Username() {
+				return group.ProtocolError("spoofed username")
+			}
+		}
+	}
+
 	switch m.Type {
 	case "join":
 		if m.Kind == "leave" {
@@ -1032,6 +1042,7 @@ func handleClientMessage(c *webClient, m clientMessage) error {
 				Type:        "joined",
 				Kind:        "leave",
 				Group:       m.Group,
+				Username:    c.username,
 				Permissions: &perms,
 			})
 		}
@@ -1063,6 +1074,7 @@ func handleClientMessage(c *webClient, m clientMessage) error {
 				Type:        "joined",
 				Kind:        "fail",
 				Group:       m.Group,
+				Username:    c.username,
 				Permissions: &group.ClientPermissions{},
 				Value:       s,
 			})
@@ -1074,6 +1086,7 @@ func handleClientMessage(c *webClient, m clientMessage) error {
 				Type:        "joined",
 				Kind:        "redirect",
 				Group:       m.Group,
+				Username:    c.username,
 				Permissions: &group.ClientPermissions{},
 				Value:       redirect,
 			})
@@ -1084,6 +1097,7 @@ func handleClientMessage(c *webClient, m clientMessage) error {
 			Type:             "joined",
 			Kind:             "join",
 			Group:            m.Group,
+			Username:         c.username,
 			Permissions:      &perms,
 			RTCConfiguration: ice.ICEConfiguration(),
 		})
@@ -1171,12 +1185,6 @@ func handleClientMessage(c *webClient, m clientMessage) error {
 			log.Printf("ICE: %v", err)
 		}
 	case "chat", "usermessage":
-		if m.Id != c.id {
-			return group.ProtocolError("wrong sender id")
-		}
-		if m.Username != "" && m.Username != c.username {
-			return group.ProtocolError("wrong sender username")
-		}
 		g := c.group
 		if g == nil {
 			return c.error(group.UserError("join a group first"))
@@ -1187,13 +1195,13 @@ func handleClientMessage(c *webClient, m clientMessage) error {
 		if m.Type == "chat" {
 			if m.Dest == "" {
 				g.AddToChatHistory(
-					m.Id, m.Username, tm, m.Kind, m.Value,
+					m.Source, m.Username, tm, m.Kind, m.Value,
 				)
 			}
 		}
 		mm := clientMessage{
 			Type:       m.Type,
-			Id:         m.Id,
+			Source:     m.Source,
 			Dest:       m.Dest,
 			Username:   m.Username,
 			Privileged: c.permissions.Op,
@@ -1221,12 +1229,6 @@ func handleClientMessage(c *webClient, m clientMessage) error {
 			ccc.write(mm)
 		}
 	case "groupaction":
-		if m.Id != c.id {
-			return group.ProtocolError("wrong sender id")
-		}
-		if m.Username != "" && m.Username != c.username {
-			return group.ProtocolError("wrong sender username")
-		}
 		g := c.group
 		if g == nil {
 			return c.error(group.UserError("join a group first"))
@@ -1304,12 +1306,6 @@ func handleClientMessage(c *webClient, m clientMessage) error {
 			return group.ProtocolError("unknown group action")
 		}
 	case "useraction":
-		if m.Id != c.id {
-			return group.ProtocolError("wrong sender id")
-		}
-		if m.Username != "" && m.Username != c.username {
-			return group.ProtocolError("wrong sender username")
-		}
 		g := c.group
 		if g == nil {
 			return c.error(group.UserError("join a group first"))
@@ -1332,7 +1328,7 @@ func handleClientMessage(c *webClient, m clientMessage) error {
 			if ok {
 				message = v
 			}
-			err := kickClient(g, m.Id, m.Username, m.Dest, message)
+			err := kickClient(g, m.Source, m.Username, m.Dest, message)
 			if err != nil {
 				return c.error(err)
 			}

static/galene.js

@@ -73,18 +73,6 @@ function getUserPass() {
     return userpass || null;
 }
 
-/**
- * Return null if the user hasn't logged in yet.
- *
- * @returns {string}
- */
-function getUsername() {
-    let userpass = getUserPass();
-    if(!userpass)
-        return null;
-    return userpass.username;
-}
-
 /**
  * @typedef {Object} settings
  * @property {boolean} [localMute]
@@ -332,9 +320,6 @@ function gotDownStream(c) {
     c.ondowntrack = function(track, transceiver, label, stream) {
         setMedia(c, false);
     }
-    c.onlabel = function(label) {
-        setLabel(c);
-    }
     c.onstatus = function(status) {
         setMediaStatus(c);
     }
@@ -1324,7 +1309,7 @@ function setLabel(c, fallback) {
     let label = document.getElementById('label-' + c.id);
     if(!label)
         return;
-    let l = c.label;
+    let l = c.username;
     if(l) {
         label.textContent = l;
         label.classList.remove('label-fallback');
@@ -1856,7 +1841,7 @@ commands.clear = {
     predicate: operatorPredicate,
     description: 'clear the chat history',
     f: (c, r) => {
-        serverConnection.groupAction(getUsername(), 'clearchat');
+        serverConnection.groupAction('clearchat');
     }
 };
 
@@ -1865,7 +1850,7 @@ commands.lock = {
     description: 'lock this group',
     parameters: '[message]',
     f: (c, r) => {
-        serverConnection.groupAction(getUsername(), 'lock', r);
+        serverConnection.groupAction('lock', r);
     }
 };
 
@@ -1873,7 +1858,7 @@ commands.unlock = {
     predicate: operatorPredicate,
     description: 'unlock this group, revert the effect of /lock',
     f: (c, r) => {
-        serverConnection.groupAction(getUsername(), 'unlock');
+        serverConnection.groupAction('unlock');
     }
 };
 
@@ -1881,7 +1866,7 @@ commands.record = {
     predicate: recordingPredicate,
     description: 'start recording',
     f: (c, r) => {
-        serverConnection.groupAction(getUsername(), 'record');
+        serverConnection.groupAction('record');
     }
 };
 
@@ -1889,7 +1874,7 @@ commands.unrecord = {
     predicate: recordingPredicate,
     description: 'stop recording',
     f: (c, r) => {
-        serverConnection.groupAction(getUsername(), 'unrecord');
+        serverConnection.groupAction('unrecord');
     }
 };
 
@@ -1897,7 +1882,7 @@ commands.subgroups = {
     predicate: operatorPredicate,
     description: 'list subgroups',
     f: (c, r) => {
-        serverConnection.groupAction(getUsername(), 'subgroups');
+        serverConnection.groupAction('subgroups');
     }
 };
 
@@ -1969,9 +1954,8 @@ commands.msg = {
         let id = findUserId(p[0]);
         if(!id)
             throw new Error(`Unknown user ${p[0]}`);
-        let username = getUsername();
-        serverConnection.chat(username, '', id, p[1]);
-        addToChatbox(serverConnection.id, id, username,
+        serverConnection.chat('', id, p[1]);
+        addToChatbox(serverConnection.id, id, serverConnection.username,
                      Date.now(), false, '', p[1]);
     }
 };
@@ -1987,7 +1971,7 @@ function userCommand(c, r) {
     let id = findUserId(p[0]);
     if(!id)
         throw new Error(`Unknown user ${p[0]}`);
-    serverConnection.userAction(getUsername(), c, id, p[1]);
+    serverConnection.userAction(c, id, p[1]);
 }
 
 function userMessage(c, r) {
@@ -1997,7 +1981,7 @@ function userMessage(c, r) {
     let id = findUserId(p[0]);
     if(!id)
         throw new Error(`Unknown user ${p[0]}`);
-    serverConnection.userMessage(getUsername(), c, id, p[1]);
+    serverConnection.userMessage(c, id, p[1]);
 }
 
 commands.kick = {
@@ -2058,7 +2042,7 @@ commands.wall = {
     f: (c, r) => {
         if(!r)
             throw new Error('empty message');
-        serverConnection.userMessage(getUsername(), 'warning', '', r);
+        serverConnection.userMessage('warning', '', r);
     },
 };
 
@@ -2122,9 +2106,8 @@ function handleInput() {
         return;
     }
 
-    let username = getUsername();
     try {
-        serverConnection.chat(username, me ? 'me' : '', '', message);
+        serverConnection.chat(me ? 'me' : '', '', message);
     } catch(e) {
         console.error(e);
         displayError(e);

static/protocol.js

@@ -59,11 +59,15 @@ function ServerConnection() {
      */
     this.id = randomid();
     /**
-     * The group that we have joined, or nil if we haven't joined yet.
+     * The group that we have joined, or null if we haven't joined yet.
      *
      * @type {string}
      */
     this.group = null;
+    /**
+     * The username we joined as.
+     */
+    this.username = null;
     /**
      * The underlying websocket.
      *
@@ -171,6 +175,7 @@ function ServerConnection() {
   * @property {string} type
   * @property {string} [kind]
   * @property {string} [id]
+  * @property {string} [source]
   * @property {string} [dest]
   * @property {string} [username]
   * @property {string} [password]
@@ -248,6 +253,7 @@ ServerConnection.prototype.connect = async function(url) {
             if(sc.group && sc.onjoined)
                 sc.onjoined.call(sc, 'leave', sc.group, {}, '');
             sc.group = null;
+            sc.username = null;
             if(sc.onclose)
                 sc.onclose.call(sc, e.code, e.reason);
             reject(new Error('websocket close ' + e.code + ' ' + e.reason));
@@ -255,8 +261,11 @@ ServerConnection.prototype.connect = async function(url) {
         this.socket.onmessage = function(e) {
             let m = JSON.parse(e.data);
             switch(m.type) {
+            case 'handshake':
+                break;
             case 'offer':
-                sc.gotOffer(m.id, m.labels, m.offer, m.kind === 'renegotiate');
+                sc.gotOffer(m.id, m.labels, m.source, m.username,
+                            m.offer, m.kind === 'renegotiate');
                 break;
             case 'answer':
                 sc.gotAnswer(m.id, m.answer);
@@ -273,9 +282,6 @@ ServerConnection.prototype.connect = async function(url) {
             case 'ice':
                 sc.gotRemoteIce(m.id, m.candidate);
                 break;
-            case 'label':
-                sc.gotLabel(m.id, m.value);
-                break;
             case 'joined':
                 if(sc.group) {
                     if(m.group !== sc.group) {
@@ -284,6 +290,7 @@ ServerConnection.prototype.connect = async function(url) {
                 } else {
                     sc.group = m.group;
                 }
+                sc.username = m.username;
                 sc.permissions = m.permissions || [];
                 sc.rtcConfiguration = m.rtcConfiguration || null;
                 if(sc.onjoined)
@@ -298,14 +305,14 @@ ServerConnection.prototype.connect = async function(url) {
             case 'chat':
                 if(sc.onchat)
                     sc.onchat.call(
-                        sc, m.id, m.dest, m.username, m.time,
+                        sc, m.source, m.dest, m.username, m.time,
                         m.privileged, m.kind, m.value,
                     );
                 break;
             case 'usermessage':
                 if(sc.onusermessage)
                     sc.onusermessage.call(
-                        sc, m.id, m.dest, m.username, m.time,
+                        sc, m.source, m.dest, m.username, m.time,
                         m.privileged, m.kind, m.value,
                     );
                 break;
@@ -441,18 +448,17 @@ ServerConnection.prototype.newUpStream = function(id) {
  * chat sends a chat message to the server.  The server will normally echo
  * the message back to the client.
  *
- * @param {string} username - The sender's username.
  * @param {string} kind
  *     -  The kind of message, either '', 'me' or an application-specific type.
  * @param {string} dest - The id to send the message to, empty for broadcast.
  * @param {string} value - The text of the message.
  */
-ServerConnection.prototype.chat = function(username, kind, dest, value) {
+ServerConnection.prototype.chat = function(kind, dest, value) {
     this.send({
         type: 'chat',
-        id: this.id,
+        source: this.id,
         dest: dest,
-        username: username,
+        username: this.username,
         kind: kind,
         value: value,
     });
@@ -461,17 +467,16 @@ ServerConnection.prototype.chat = function(username, kind, dest, value) {
 /**
  * userAction sends a request to act on a user.
  *
- * @param {string} username - The sender's username.
  * @param {string} kind - One of "op", "unop", "kick", "present", "unpresent".
  * @param {string} dest - The id of the user to act upon.
  * @param {string} [value] - An optional user-readable message.
  */
-ServerConnection.prototype.userAction = function(username, kind, dest, value) {
+ServerConnection.prototype.userAction = function(kind, dest, value) {
     this.send({
         type: 'useraction',
-        id: this.id,
+        source: this.id,
         dest: dest,
-        username: username,
+        username: this.username,
         kind: kind,
         value: value,
     });
@@ -481,17 +486,16 @@ ServerConnection.prototype.userAction = function(username, kind, dest, value) {
  * userMessage sends an application-specific message to a user.
  * This is similar to a chat message, but is not saved in the chat history.
  *
- * @param {string} username - The sender's username.
  * @param {string} kind - The kind of application-specific message.
  * @param {string} dest - The id to send the message to, empty for broadcast.
  * @param {string} [value] - An optional parameter.
  */
-ServerConnection.prototype.userMessage = function(username, kind, dest, value) {
+ServerConnection.prototype.userMessage = function(kind, dest, value) {
     this.send({
         type: 'usermessage',
-        id: this.id,
+        source: this.id,
         dest: dest,
-        username: username,
+        username: this.username,
         kind: kind,
         value: value,
     });
@@ -500,17 +504,16 @@ ServerConnection.prototype.userMessage = function(username, kind, dest, value) {
 /**
  * groupAction sends a request to act on the current group.
  *
- * @param {string} username - The sender's username.
  * @param {string} kind
  *     - One of 'clearchat', 'lock', 'unlock', 'record' or 'unrecord'.
  * @param {string} [message] - An optional user-readable message.
  */
-ServerConnection.prototype.groupAction = function(username, kind, message) {
+ServerConnection.prototype.groupAction = function(kind, message) {
     this.send({
         type: 'groupaction',
-        id: this.id,
+        source: this.id,
         kind: kind,
-        username: username,
+        username: this.username,
         value: message,
     });
 };
@@ -520,11 +523,13 @@ ServerConnection.prototype.groupAction = function(username, kind, message) {
  *
  * @param {string} id
  * @param {Object<string, string>} labels
+ * @param {string} source
+ * @param {string} username
  * @param {RTCSessionDescriptionInit} offer
  * @param {boolean} renegotiate
  * @function
  */
-ServerConnection.prototype.gotOffer = async function(id, labels, offer, renegotiate) {
+ServerConnection.prototype.gotOffer = async function(id, labels, source, username, offer, renegotiate) {
     let sc = this;
     let c = sc.down[id];
     if(c && !renegotiate) {
@@ -586,6 +591,8 @@ ServerConnection.prototype.gotOffer = async function(id, labels, offer, renegoti
     }
 
     c.labelsByMid = labels;
+    c.source = source;
+    c.username = username;
 
     if(sc.ondownstream)
         sc.ondownstream.call(sc, c);
@@ -620,22 +627,6 @@ ServerConnection.prototype.gotOffer = async function(id, labels, offer, renegoti
         c.onnegotiationcompleted.call(c);
 };
 
-/**
- * Called when we receive a stream label from the server.  Don't call this.
- *
- * @param {string} id
- * @param {string} label
- */
-ServerConnection.prototype.gotLabel = function(id, label) {
-    let c = this.down[id];
-    if(!c)
-        throw new Error('Got label for unknown id');
-
-    c.label = label;
-    if(c.onlabel)
-        c.onlabel.call(c, label);
-};
-
 /**
  * Called when we receive an answer from the server.  Don't call this.
  *
@@ -765,13 +756,19 @@ function Stream(sc, id, pc, up) {
      */
     this.kind = null;
     /**
-     * For down streams, a user-readable label.
+     * For down streams, the id of the client that created the stream.
+     *
+     * @type {string}
+     */
+    this.source = null;
+    /**
+     * For down streams, the username of the client who created the stream.
      *
      * @type {string}
      */
-    this.label = null;
+    this.username = null;
     /**
-     * The associated RTCPeerConnectoin.  This is null before the stream
+     * The associated RTCPeerConnection.  This is null before the stream
      * is connected, and may change over time.
      *
      * @type {RTCPeerConnection}
@@ -1036,6 +1033,8 @@ Stream.prototype.negotiate = async function (restartIce) {
 
     c.sc.send({
         type: 'offer',
+        source: c.sc.id,
+        username: c.sc.username,
         kind: this.localDescriptionSent ? 'renegotiate' : '',
         id: c.id,
         labels: c.labelsByMid,