Share historical room keys when inviting

src/components/views/dialogs/InviteDialog.tsx

@@ -42,6 +42,10 @@ import {UIFeature} from "../../../settings/UIFeature";
 import CountlyAnalytics from "../../../CountlyAnalytics";
 import {Room} from "matrix-js-sdk/src/models/room";
 import { MatrixCall } from 'matrix-js-sdk/src/webrtc/call';
+import {EventTimeline} from "matrix-js-sdk/src/models/event-timeline";
+import {MatrixEvent} from "matrix-js-sdk/src/models/event";
+import {getAddressType} from "../../../UserAddress";
+import {sleep} from "../../../utils/promise";
 
 // we have a number of types defined from the Matrix spec which can't reasonably be altered here.
 /* eslint-disable camelcase */
@@ -53,6 +57,70 @@ export const KIND_CALL_TRANSFER = "call_transfer";
 const INITIAL_ROOMS_SHOWN = 3; // Number of rooms to show at first
 const INCREMENT_ROOMS_SHOWN = 5; // Number of rooms to add when 'show more' is clicked
 
+/**
+ * Iterate backwards through the message history, returning messages that are
+ * visible to all members of the room (`m.room.history_visibility` is
+ * `world_readable` or `shared`), until the most recent message that is not.
+ *
+ * This function is intended to be used with MatrixClient.shareKeysForMessages.
+ */
+function iterateShareableHistoryForRoom(client, room) {
+    let timeline = room.getLiveTimeline();
+    const visibilityEvent = timeline.getState(EventTimeline.FORWARDS)
+        .getStateEvents("m.room.history_visibility", "");
+    let visibility = visibilityEvent && visibilityEvent.getContent() &&
+        visibilityEvent.getContent().history_visibility;
+    let events = timeline.getEvents();
+    let index = events.length;
+    let paginationToken;
+    const next = async () => {
+        if (index === 0) {
+            // get prev chunk
+            if (!paginationToken) {
+                const prevTimeline = timeline.getNeighbouringTimeline(EventTimeline.BACKWARDS);
+                if (prevTimeline) {
+                    timeline = prevTimeline;
+                    events = timeline.getEvents();
+                } else {
+                    paginationToken = timeline.getPaginationToken(EventTimeline.BACKWARDS);
+                    timeline = undefined;
+                }
+            }
+            if (!timeline && !paginationToken) {
+                return;
+            } else if (paginationToken) {
+                await sleep(1000);
+                const res = await client._createMessagesRequest(
+                    room.roomId, paginationToken, 30, "b",
+                );
+                if (res.end === paginationToken || res.chunk.length === 0) {
+                    // no new messages
+                    paginationToken = undefined;
+                    return;
+                } else {
+                    paginationToken = res.end;
+                    events = res.chunk.reverse().map(e => new MatrixEvent(e));
+                }
+            }
+            index = events.length;
+        }
+        index--;
+        const event = events[index];
+        if (event.isState()) {
+            if (event.getType() === "m.room.history_visibility") {
+                visibility = event.getPrevContent() &&
+                    event.getPrevContent().history_visibility;
+            }
+            return next();
+        }
+        if (visibility !== "world_readable" && visibility !== "shared") {
+            return;
+        }
+        return event;
+    };
+    return next;
+}
+
 // This is the interface that is expected by various components in this file. It is a bit
 // awkward because it also matches the RoomMember class from the js-sdk with some extra support
 // for 3PIDs/email addresses.
@@ -676,14 +744,15 @@ export default class InviteDialog extends React.PureComponent<IInviteDialogProps
         });
     };
 
-    _inviteUsers = () => {
+    _inviteUsers = async () => {
         const startTime = CountlyAnalytics.getTimestamp();
         this.setState({busy: true});
         this._convertFilter();
         const targets = this._convertFilter();
         const targetIds = targets.map(t => t.userId);
 
-        const room = MatrixClientPeg.get().getRoom(this.props.roomId);
+        const cli = MatrixClientPeg.get();
+        const room = cli.getRoom(this.props.roomId);
         if (!room) {
             console.error("Failed to find the room to invite users to");
             this.setState({
@@ -693,20 +762,43 @@ export default class InviteDialog extends React.PureComponent<IInviteDialogProps
             return;
         }
 
-        inviteMultipleToRoom(this.props.roomId, targetIds).then(result => {
+        try {
+            const res = await inviteMultipleToRoom(this.props.roomId, targetIds)
             CountlyAnalytics.instance.trackSendInvite(startTime, this.props.roomId, targetIds.length);
-            if (!this._shouldAbortAfterInviteError(result)) { // handles setting error message too
+            if (!this._shouldAbortAfterInviteError(res)) { // handles setting error message too
                 this.props.onFinished();
             }
-        }).catch(err => {
+
+            if (cli.isRoomEncrypted(this.props.roomId) &&
+                SettingsStore.getValue("feature_room_history_key_sharing")) {
+                const visibilityEvent = room.currentState.getStateEvents(
+                    "m.room.history_visibility", "",
+                );
+                const visibility = visibilityEvent && visibilityEvent.getContent() &&
+                    visibilityEvent.getContent().history_visibility;
+                if (visibility == "world_readable" || visibility == "shared") {
+                    const invitedUsers = [];
+                    for (const [addr, state] of Object.entries(res.states)) {
+                        if (state === "invited" && getAddressType(addr) === "mx-user-id") {
+                            invitedUsers.push(addr);
+                        }
+                    }
+                    console.log("Sharing history with", invitedUsers);
+                    cli.shareKeysForMessages(
+                        this.props.roomId, invitedUsers,
+                        iterateShareableHistoryForRoom(cli, room),
+                    );
+                }
+            }
+        } catch (err) {
             console.error(err);
             this.setState({
                 busy: false,
                 errorText: _t(
                     "We couldn't invite those users. Please check the users you want to invite and try again.",
                 ),
             });
-        });
+        }
     };
 
     _transferCall = async () => {
@@ -1187,10 +1279,12 @@ export default class InviteDialog extends React.PureComponent<IInviteDialogProps
         let helpText;
         let buttonText;
         let goButtonFn;
+        let keySharingWarning = <span />;
 
         const identityServersEnabled = SettingsStore.getValue(UIFeature.IdentityServer);
 
-        const userId = MatrixClientPeg.get().getUserId();
+        const cli = MatrixClientPeg.get();
+        const userId = cli.getUserId();
         if (this.props.kind === KIND_DM) {
             title = _t("Direct Messages");
 
@@ -1281,6 +1375,22 @@ export default class InviteDialog extends React.PureComponent<IInviteDialogProps
 
             buttonText = _t("Invite");
             goButtonFn = this._inviteUsers;
+
+            if (SettingsStore.getValue("feature_room_history_key_sharing") &&
+                cli.isRoomEncrypted(this.props.roomId)) {
+                const room = cli.getRoom(this.props.roomId);
+                const visibilityEvent = room.currentState.getStateEvents(
+                    "m.room.history_visibility", "",
+                );
+                const visibility = visibilityEvent && visibilityEvent.getContent() &&
+                    visibilityEvent.getContent().history_visibility;
+                if (visibility == "world_readable" || visibility == "shared") {
+                    keySharingWarning =
+                        <div>
+                            {_t("Note: Decryption keys for old messages will be shared with invited users.")}
+                        </div>;
+                }
+            }
         } else if (this.props.kind === KIND_CALL_TRANSFER) {
             title = _t("Transfer");
             buttonText = _t("Transfer");
@@ -1314,6 +1424,7 @@ export default class InviteDialog extends React.PureComponent<IInviteDialogProps
                             {spinner}
                         </div>
                     </div>
+                    {keySharingWarning}
                     {this._renderIdentityServerWarning()}
                     <div className='error'>{this.state.errorText}</div>
                     <div className='mx_InviteDialog_userSections'>

src/i18n/strings/en_EN.json

@@ -791,6 +791,7 @@
     "Show message previews for reactions in DMs": "Show message previews for reactions in DMs",
     "Show message previews for reactions in all rooms": "Show message previews for reactions in all rooms",
     "Offline encrypted messaging using dehydrated devices": "Offline encrypted messaging using dehydrated devices",
+    "Share decryption keys for room history when inviting users": "Share decryption keys for room history when inviting users",
     "Enable advanced debugging for the room list": "Enable advanced debugging for the room list",
     "Show info about bridges in room settings": "Show info about bridges in room settings",
     "Font size": "Font size",
@@ -2153,6 +2154,7 @@
     "Go": "Go",
     "Invite someone using their name, email address, username (like <userId/>) or <a>share this room</a>.": "Invite someone using their name, email address, username (like <userId/>) or <a>share this room</a>.",
     "Invite someone using their name, username (like <userId/>) or <a>share this room</a>.": "Invite someone using their name, username (like <userId/>) or <a>share this room</a>.",
+    "Note: Decryption keys for old messages will be shared with invited users.": "Note: Decryption keys for old messages will be shared with invited users.",
     "Transfer": "Transfer",
     "a new master key signature": "a new master key signature",
     "a new cross-signing key signature": "a new cross-signing key signature",

src/settings/Settings.ts

@@ -214,6 +214,12 @@ export const SETTINGS: {[setting: string]: ISetting} = {
         supportedLevels: LEVELS_FEATURE,
         default: false,
     },
+    "feature_room_history_key_sharing": {
+        isFeature: true,
+        displayName: _td("Share decryption keys for room history when inviting users"),
+        supportedLevels: LEVELS_FEATURE,
+        default: false,
+    },
     "advancedRoomListLogging": {
         // TODO: Remove flag before launch: https://github.com/vector-im/element-web/issues/14231
         displayName: _td("Enable advanced debugging for the room list"),