Use read receipt envelope to infer startExpirationTime

Avoids display of phantom messages that are only received and marked
read locally long after they have expired on another linked device.

js/background.js

@@ -247,10 +247,15 @@
     }
 
     function onReadReceipt(ev) {
-        var timestamp = ev.timestamp.toNumber();
-        var sender    = ev.sender;
+        var read_at   = ev.timestamp;
+        var timestamp = ev.read.timestamp;
+        var sender    = ev.read.sender;
         console.log('read receipt ', sender, timestamp);
-        Whisper.ReadReceipts.add({sender: sender, timestamp: timestamp});
+        Whisper.ReadReceipts.add({
+            sender    : sender,
+            timestamp : timestamp,
+            read_at   : read_at
+        });
     }
 
     // lazy hack

js/libtextsecure.js

@@ -38325,16 +38325,19 @@ MessageReceiver.prototype.extend({
         } else if (syncMessage.read) {
             console.log('read messages',
                     'from', envelope.source + '.' + envelope.sourceDevice);
-            this.handleRead(syncMessage.read);
+            this.handleRead(syncMessage.read, envelope.timestamp);
         } else {
             throw new Error('Got empty SyncMessage');
         }
     },
-    handleRead: function(read) {
+    handleRead: function(read, timestamp) {
         for (var i = 0; i < read.length; ++i) {
             var ev = new Event('read');
-            ev.timestamp = read[i].timestamp;
-            ev.sender = read[i].sender;
+            ev.timestamp = timestamp.toNumber();
+            ev.read = {
+              timestamp : read[i].timestamp.toNumber(),
+              sender    : read[i].sender
+            }
             this.dispatchEvent(ev);
         }
     },

js/models/messages.js

@@ -374,10 +374,10 @@
                 });
             });
         },
-        markRead: function() {
+        markRead: function(read_at) {
             this.unset('unread');
             if (this.get('expireTimer') && !this.get('expirationStartTimestamp')) {
-                this.set('expirationStartTimestamp', Date.now());
+                this.set('expirationStartTimestamp', read_at || Date.now());
             }
             Whisper.Notifications.remove(Whisper.Notifications.where({
                 messageId: this.id

js/read_receipts.js

@@ -28,7 +28,7 @@
                 });
                 if (message) {
                     this.remove(receipt);
-                    message.markRead().then(function() {
+                    message.markRead(receipt.get('read_at')).then(function() {
                         var conversation = ConversationController.get({
                             id: message.get('conversationId')
                         });

libtextsecure/message_receiver.js

@@ -254,16 +254,19 @@ MessageReceiver.prototype.extend({
         } else if (syncMessage.read) {
             console.log('read messages',
                     'from', envelope.source + '.' + envelope.sourceDevice);
-            this.handleRead(syncMessage.read);
+            this.handleRead(syncMessage.read, envelope.timestamp);
         } else {
             throw new Error('Got empty SyncMessage');
         }
     },
-    handleRead: function(read) {
+    handleRead: function(read, timestamp) {
         for (var i = 0; i < read.length; ++i) {
             var ev = new Event('read');
-            ev.timestamp = read[i].timestamp;
-            ev.sender = read[i].sender;
+            ev.timestamp = timestamp.toNumber();
+            ev.read = {
+              timestamp : read[i].timestamp.toNumber(),
+              sender    : read[i].sender
+            }
             this.dispatchEvent(ev);
         }
     },