Send an "oh hai" message to other e2e users

When we first complete an initial sync on a new device, send out an
m.new_device message for each user we share an e2e room with

lib/crypto/index.js

@@ -88,6 +88,15 @@ function Crypto(baseApis, eventEmitter, sessionStore, userId, deviceId) {
 }
 
 function _registerEventHandlers(crypto, eventEmitter) {
+    eventEmitter.on("sync", function(syncState, oldState, data) {
+        if (syncState == "PREPARED") {
+            // XXX ugh. we're assuming the eventEmitter is a MatrixClient.
+            // how can we avoid doing so?
+            var rooms = eventEmitter.getRooms();
+            crypto._onInitialSyncCompleted(rooms);
+        }
+    });
+
     eventEmitter.on(
         "RoomMember.membership",
         crypto._onRoomMembership.bind(crypto)
@@ -815,6 +824,73 @@ Crypto.prototype._onCryptoEvent = function(event) {
     }
 };
 
+/**
+ * handle the completion of the initial sync.
+ *
+ * Announces the new device.
+ *
+ * @private
+ * @param {module:models/room[]} rooms list of rooms the client knows about
+ */
+Crypto.prototype._onInitialSyncCompleted = function(rooms) {
+    if (this._sessionStore.getDeviceAnnounced()) {
+        return;
+    }
+
+    // we need to tell all the devices in all the rooms we are members of that
+    // we have arrived.
+    // build a list of rooms for each user.
+    var roomsByUser = {};
+    for (var i = 0; i < rooms.length; i++) {
+        var room = rooms[i];
+
+        // check for rooms with encryption enabled
+        var alg = this._roomAlgorithms[room.roomId];
+        if (!alg) {
+            continue;
+        }
+
+        // ignore any rooms which we have left
+        var me = room.getMember(this._userId);
+        if (!me || (
+            me.membership !== "join" && me.membership !== "invite"
+        )) {
+            continue;
+        }
+
+        var members = room.getJoinedMembers();
+        for (var j = 0; j < members.length; j++) {
+            var m = members[j];
+            if (!roomsByUser[m.userId]) {
+                roomsByUser[m.userId] = [];
+            }
+            roomsByUser[m.userId].push(room.roomId);
+        }
+    }
+
+    // build a per-device message for each user
+    var content = {};
+    for (var userId in roomsByUser) {
+        if (!roomsByUser.hasOwnProperty(userId)) {
+            continue;
+        }
+        content[userId] = {
+            "*": {
+                device_id: this._deviceId,
+                rooms: roomsByUser[userId],
+            },
+        };
+    }
+
+    var self = this;
+    this._baseApis.sendToDevice(
+        "m.new_device", // OH HAI!
+        content
+    ).done(function() {
+        self._sessionStore.setDeviceAnnounced();
+    });
+};
+
 /**
  * Handle a key event
  *

lib/store/session/webstorage.js

@@ -62,6 +62,22 @@ WebStorageSessionStore.prototype = {
         return this.store.getItem(KEY_END_TO_END_ACCOUNT);
     },
 
+    /**
+     * Store a flag indicating that we have announced the new device.
+     */
+    setDeviceAnnounced: function() {
+        this.store.setItem(KEY_END_TO_END_ANNOUNCED, "true");
+    },
+
+    /**
+     * Check if the "device announced" flag is set
+     *
+     * @return {boolean} true if the "device announced" flag has been set.
+     */
+    getDeviceAnnounced: function() {
+        return this.store.getItem(KEY_END_TO_END_ANNOUNCED) == "true";
+    },
+
     /**
      * Stores the known devices for a user.
      * @param {string} userId The user's ID.
@@ -134,6 +150,7 @@ WebStorageSessionStore.prototype = {
 };
 
 var KEY_END_TO_END_ACCOUNT = E2E_PREFIX + "account";
+var KEY_END_TO_END_ANNOUNCED = E2E_PREFIX + "announced";
 
 function keyEndToEndDevicesForUser(userId) {
     return E2E_PREFIX + "devices/" + userId;