Implement 'noecho' field in client messages.

README.PROTOCOL

@@ -233,6 +233,7 @@ A chat message may be sent using a `chat` message.
     username: username,
     dest: dest-id,
     privileged: boolean,
+    noecho: false,
     value: message
 }
 ```
@@ -242,7 +243,9 @@ the clients in the group.  If `source` is empty, then the message was
 originated by the server.  The message is forwarded by the server without
 interpretation, the server only validates that the `source` and `username`
 fields are authentic.  The field `privileged` is set to true by the server
-if the message was originated by a client with the `op` permission.
+if the message was originated by a client with the `op` permission.  The
+field `noecho` is set by the client if it doesn't wish to receive a copy
+of its own message.
 
 A user message is similar to a chat message, but is not conserved in the
 chat history, and is not expected to contain user-visible content.

rtpconn/webclient.go

@@ -173,6 +173,7 @@ type clientMessage struct {
 	Permissions      *group.ClientPermissions `json:"permissions,omitempty"`
 	Group            string                   `json:"group,omitempty"`
 	Value            interface{}              `json:"value,omitempty"`
+	NoEcho           bool                     `json:"noecho,omitempty"`
 	Time             int64                    `json:"time,omitempty"`
 	SDP              string                   `json:"sdp,omitempty"`
 	Candidate        *webrtc.ICECandidateInit `json:"candidate,omitempty"`
@@ -1209,10 +1210,15 @@ func handleClientMessage(c *webClient, m clientMessage) error {
 			Privileged: c.permissions.Op,
 			Time:       tm,
 			Kind:       m.Kind,
+			NoEcho:     m.NoEcho,
 			Value:      m.Value,
 		}
 		if m.Dest == "" {
-			err := broadcast(g.GetClients(nil), mm)
+			var except group.Client
+			if m.NoEcho {
+				except = c
+			}
+			err := broadcast(g.GetClients(except), mm)
 			if err != nil {
 				log.Printf("broadcast(chat): %v", err)
 			}

static/protocol.js

@@ -176,6 +176,7 @@ function ServerConnection() {
   * @property {Object<string,boolean>} [permissions]
   * @property {string} [group]
   * @property {unknown} [value]
+  * @property {boolean} [noecho]
   * @property {string} [sdp]
   * @property {RTCIceCandidate} [candidate]
   * @property {Object<string,string>} [labels]
@@ -477,8 +478,9 @@ ServerConnection.prototype.userAction = function(kind, dest, value) {
  * @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.
+ * @param {boolean} [noecho] - If set, don't echo back the message to the sender.
  */
-ServerConnection.prototype.userMessage = function(kind, dest, value) {
+ServerConnection.prototype.userMessage = function(kind, dest, value, noecho) {
     this.send({
         type: 'usermessage',
         source: this.id,
@@ -486,6 +488,7 @@ ServerConnection.prototype.userMessage = function(kind, dest, value) {
         username: this.username,
         kind: kind,
         value: value,
+        noecho: noecho,
     });
 };