From 561e4f734e2b286e1c12cec6945986a4418805bc Mon Sep 17 00:00:00 2001
From: David Baker <dave@matrix.org>
Date: Wed, 18 May 2022 18:32:49 +0100
Subject: [PATCH] Handle other members having no e2e keys

Fetch the device info once at the start of the cal and cache it
rather than fetching every time, and throw if we're supposed to be
using e2e but the other end has no e2e keys.
---
 src/webrtc/call.ts      | 23 ++++++++++++++++++++---
 src/webrtc/groupCall.ts | 24 ++++++++++++++++++++----
 2 files changed, 40 insertions(+), 7 deletions(-)

diff --git a/src/webrtc/call.ts b/src/webrtc/call.ts
index cbc6390d15..cfe94976d7 100644
--- a/src/webrtc/call.ts
+++ b/src/webrtc/call.ts
@@ -47,6 +47,7 @@ import { CallFeed } from './callFeed';
 import { MatrixClient } from "../client";
 import { ISendEventResponse } from "../@types/requests";
 import { EventEmitterEvents, TypedEventEmitter } from "../models/typed-event-emitter";
+import { DeviceInfo } from '../crypto/deviceinfo';
 
 // events: hangup, error(err), replaced(call), state(state, oldState)
 
@@ -343,6 +344,7 @@ export class MatrixCall extends TypedEventEmitter<CallEvent, CallEventHandlerMap
     private callLength = 0;
 
     private opponentDeviceId: string;
+    private opponentDeviceInfo: DeviceInfo;
     private opponentSessionId: string;
     public groupCallId: string;
 
@@ -508,6 +510,17 @@ export class MatrixCall extends TypedEventEmitter<CallEvent, CallEventHandlerMap
         return this.feeds.filter((feed) => !feed.isLocal());
     }
 
+    private async initOpponentCrypto() {
+        if (!this.opponentDeviceId) return;
+
+        const userId = this.invitee || this.getOpponentMember().userId;
+        const deviceInfoMap = await this.client.crypto.deviceList.downloadKeys([userId], false);
+        this.opponentDeviceInfo = deviceInfoMap[userId][this.opponentDeviceId];
+        if (this.opponentDeviceInfo === undefined) {
+            throw new Error(`No keys found for opponent device ${this.opponentDeviceId}!`);
+        }
+    }
+
     /**
      * Generates and returns localSDPStreamMetadata
      * @returns {SDPStreamMetadata} localSDPStreamMetadata
@@ -792,6 +805,7 @@ export class MatrixCall extends TypedEventEmitter<CallEvent, CallEventHandlerMap
         // handler will start giving us more call events (eg. candidates) so if
         // we haven't set the party ID, we'll ignore them.
         this.chooseOpponent(event);
+        await this.initOpponentCrypto();
         try {
             await this.peerConn.setRemoteDescription(invite.offer);
             await this.addBufferedIceCandidates();
@@ -2052,9 +2066,10 @@ export class MatrixCall extends TypedEventEmitter<CallEvent, CallEventHandlerMap
                 },
             };
             const userId = this.invitee || this.getOpponentMember().userId;
-            const deviceInfoMap = await this.client.crypto.deviceList.downloadKeys([userId], false);
-            const deviceInfo = deviceInfoMap[userId][this.opponentDeviceId];
-            return this.client.crypto.encryptAndSendToDevices([{ userId, deviceInfo }], payload);
+            return this.client.crypto.encryptAndSendToDevices([{
+                userId,
+                deviceInfo: this.opponentDeviceInfo,
+            }], payload);
         } else {
             this.emit(CallEvent.SendVoipEvent, {
                 type: "sendEvent",
@@ -2351,6 +2366,8 @@ export class MatrixCall extends TypedEventEmitter<CallEvent, CallEventHandlerMap
         this.checkForErrorListener();
         this.direction = CallDirection.Outbound;
 
+        await this.initOpponentCrypto();
+
         // XXX Find a better way to do this
         this.client.callEventHandler.calls.set(this.callId, this);
 
diff --git a/src/webrtc/groupCall.ts b/src/webrtc/groupCall.ts
index fbcc3a8cf0..f30b13447d 100644
--- a/src/webrtc/groupCall.ts
+++ b/src/webrtc/groupCall.ts
@@ -58,7 +58,8 @@ export type GroupCallEventHandlerMap = {
 
 export enum GroupCallErrorCode {
     NoUserMedia = "no_user_media",
-    UnknownDevice = "unknown_device"
+    UnknownDevice = "unknown_device",
+    PlaceCallFailed = "place_call_failed"
 }
 
 export class GroupCallError extends Error {
@@ -653,7 +654,7 @@ export class GroupCall extends TypedEventEmitter<GroupCallEvent, GroupCallEventH
         return this.client.sendStateEvent(this.room.roomId, EventType.GroupCallMemberPrefix, content, localUserId);
     }
 
-    public onMemberStateChanged = (event: MatrixEvent) => {
+    public onMemberStateChanged = async (event: MatrixEvent) => {
         // The member events may be received for another room, which we will ignore.
         if (event.getRoomId() !== this.room.roomId) {
             return;
@@ -751,8 +752,23 @@ export class GroupCall extends TypedEventEmitter<GroupCallEvent, GroupCallEventH
         const requestScreenshareFeed = opponentDevice.feeds.some(
             (feed) => feed.purpose === SDPStreamMetadataPurpose.Screenshare);
 
-        // Safari can't send a MediaStream to multiple sources, so clone it
-        newCall.placeCallWithCallFeeds(this.getLocalFeeds().map(feed => feed.clone()), requestScreenshareFeed);
+        try {
+            // Safari can't send a MediaStream to multiple sources, so clone it
+            await newCall.placeCallWithCallFeeds(
+                this.getLocalFeeds().map(feed => feed.clone()),
+                requestScreenshareFeed,
+            );
+        } catch (e) {
+            logger.warn(`Failed to place call to ${member.userId}!`, e);
+            this.emit(
+                GroupCallEvent.Error,
+                new GroupCallError(
+                    GroupCallErrorCode.PlaceCallFailed,
+                    `Failed to place call to ${member.userId}.`,
+                ),
+            );
+            return;
+        }
 
         if (this.dataChannelsEnabled) {
             newCall.createDataChannel("datachannel", this.dataChannelOptions);