encrypt for invited users if history visibility allows.

fixes https://github.com/vector-im/riot-web/issues/2713

src/crypto/algorithms/megolm.js

@@ -536,8 +536,7 @@ MegolmEncryption.prototype._checkForUnknownDevices = function(devicesInRoom) {
  *     from userId to deviceId to deviceInfo
  */
 MegolmEncryption.prototype._getDevicesInRoom = function(room) {
-    // XXX what about rooms where invitees can see the content?
+    const roomMembers = utils.map(room.getEncryptionTargetMembers(), function(u) {
-    const roomMembers = utils.map(room.getJoinedMembers(), function(u) {
         return u.userId;
     });
 

src/crypto/algorithms/olm.js

@@ -89,7 +89,7 @@ OlmEncryption.prototype.encryptMessage = function(room, eventType, content) {
     // TODO: there is a race condition here! What if a new user turns up
     // just as you are sending a secret message?
 
-    const users = utils.map(room.getJoinedMembers(), function(u) {
+    const users = utils.map(room.getEncryptionTargetMembers(), function(u) {
         return u.userId;
     });
 

src/crypto/index.js

@@ -652,7 +652,7 @@ Crypto.prototype.setRoomEncryption = async function(roomId, config, inhibitDevic
         throw new Error(`Unable to enable encryption in unknown room ${roomId}`);
     }
 
-    const members = room.getJoinedMembers();
+    const members = room.getEncryptionTargetMembers();
     members.forEach((m) => {
         this._deviceList.startTrackingDeviceList(m.userId);
     });
@@ -986,7 +986,7 @@ Crypto.prototype._evalDeviceListChanges = async function(deviceLists) {
 Crypto.prototype._getE2eUsers = function() {
     const e2eUserIds = [];
     for (const room of this._getE2eRooms()) {
-        const members = room.getJoinedMembers();
+        const members = room.getEncryptionTargetMembers();
         for (const member of members) {
             e2eUserIds.push(member.userId);
         }
@@ -1086,6 +1086,11 @@ Crypto.prototype._onRoomMembership = function(event, member, oldMembership) {
         // make sure we are tracking the deviceList for this user
         this._deviceList.startTrackingDeviceList(member.userId);
     }
+    else if (member.membership == 'invite' &&
+             this._clientStore.getRoom(roomId).shouldEncryptForInvitedUsers()) {
+        console.log('Invite event for ' + member.userId + ' in ' + roomId);
+        this._deviceList.startTrackingDeviceList(member.userId);
+    }
 
     alg.onRoomMembership(event, member, oldMembership);
 };

src/models/room.js

@@ -456,6 +456,28 @@ Room.prototype.addEventsToTimeline = function(events, toStartOfTimeline,
     });
  };
 
+ /**
+  * Get a list of members we should be encrypting for in this room
+  * @return {RoomMember[]} A list of members who we should encrypt messages for
+  *                        in this room.
+  */
+ Room.prototype.getEncryptionTargetMembers = function() {
+    let members = this.getMembersWithMembership("join");
+    if (this.shouldEncryptForInvitedMembers()) {
+        members = members.concat(this.getMembersWithMembership("invite"));
+    }
+    return members;
+ };
+
+ /**
+  * Determine whether we should encrypt messages for invited users in this room
+  * @return {boolean} if we should encrypt messages for invited users
+  */
+ Room.prototype.shouldEncryptForInvitedMembers = function() {
+    const ev = this.currentState.getStateEvents("m.room.history_visibility", "");
+    return (ev && ev.getContent() && ev.getContent().history_visibility !== "joined");
+ };
+
  /**
   * Get the default room name (i.e. what a given user would see if the
   * room had no m.room.name)
@@ -950,7 +972,6 @@ Room.prototype.recalculate = function(userId) {
     }
 };
 
-
 /**
  * Get a list of user IDs who have <b>read up to</b> the given event.
  * @param {MatrixEvent} event the event to get read receipts for.