From 353d6bab47ab928aab089e897f5475942fcfa0ac Mon Sep 17 00:00:00 2001
From: Robert Long <robert@robertlong.me>
Date: Fri, 18 Feb 2022 11:35:56 -0800
Subject: [PATCH] Fix and add a test for toDevice ordering

---
 spec/unit/webrtc/callEventHandler.spec.ts | 83 +++++++++++++++++++++++
 src/webrtc/callEventHandler.ts            | 13 +++-
 2 files changed, 93 insertions(+), 3 deletions(-)
 create mode 100644 spec/unit/webrtc/callEventHandler.spec.ts

diff --git a/spec/unit/webrtc/callEventHandler.spec.ts b/spec/unit/webrtc/callEventHandler.spec.ts
new file mode 100644
index 000000000..f1e9bcbaa
--- /dev/null
+++ b/spec/unit/webrtc/callEventHandler.spec.ts
@@ -0,0 +1,83 @@
+import { TestClient } from '../../TestClient';
+import { CallEventHandler } from '../../../src/webrtc/callEventHandler';
+import { MatrixEvent } from '../../../src/models/event';
+import { EventType } from '../../../src/@types/event';
+
+describe('CallEventHandler', function() {
+    let client;
+
+    beforeEach(function() {
+        client = new TestClient("@alice:foo", "somedevice", "token", undefined, {});
+    });
+
+    afterEach(function() {
+        client.stop();
+    });
+
+    it('should enforce inbound toDevice message ordering', async function() {
+        const callEventHandler = new CallEventHandler(client);
+
+        const event1 = new MatrixEvent({
+            type: EventType.CallInvite,
+            content: {
+                call_id: "123",
+                seq: 0,
+            },
+        });
+        callEventHandler["onToDeviceEvent"](event1);
+
+        expect(callEventHandler.callEventBuffer.length).toBe(1);
+        expect(callEventHandler.callEventBuffer[0]).toBe(event1);
+
+        const event2 = new MatrixEvent({
+            type: EventType.CallCandidates,
+            content: {
+                call_id: "123",
+                seq: 1,
+            },
+        });
+        callEventHandler["onToDeviceEvent"](event2);
+
+        expect(callEventHandler.callEventBuffer.length).toBe(2);
+        expect(callEventHandler.callEventBuffer[1]).toBe(event2);
+
+        const event3 = new MatrixEvent({
+            type: EventType.CallCandidates,
+            content: {
+                call_id: "123",
+                seq: 3,
+            },
+        });
+        callEventHandler["onToDeviceEvent"](event3);
+
+        expect(callEventHandler.callEventBuffer.length).toBe(2);
+        expect(callEventHandler.nextSeqByCall.get("123")).toBe(2);
+        expect(callEventHandler.toDeviceEventBuffers.get("123").length).toBe(1);
+
+        const event4 = new MatrixEvent({
+            type: EventType.CallCandidates,
+            content: {
+                call_id: "123",
+                seq: 4,
+            },
+        });
+        callEventHandler["onToDeviceEvent"](event4);
+
+        expect(callEventHandler.callEventBuffer.length).toBe(2);
+        expect(callEventHandler.nextSeqByCall.get("123")).toBe(2);
+        expect(callEventHandler.toDeviceEventBuffers.get("123").length).toBe(2);
+
+        const event5 = new MatrixEvent({
+            type: EventType.CallCandidates,
+            content: {
+                call_id: "123",
+                seq: 2,
+            },
+        });
+        callEventHandler["onToDeviceEvent"](event5);
+
+        expect(callEventHandler.callEventBuffer.length).toBe(5);
+        expect(callEventHandler.nextSeqByCall.get("123")).toBe(5);
+        expect(callEventHandler.toDeviceEventBuffers.get("123").length).toBe(0);
+    });
+});
diff --git a/src/webrtc/callEventHandler.ts b/src/webrtc/callEventHandler.ts
index ea454a4bd..6c2c126bb 100644
--- a/src/webrtc/callEventHandler.ts
+++ b/src/webrtc/callEventHandler.ts
@@ -107,7 +107,12 @@ export class CallEventHandler {
 
             const buffer = this.toDeviceEventBuffers.get(content.call_id);
             const index = buffer.findIndex((e) => e.getContent().seq > content.seq);
-            buffer.splice(index, 0, event);
+
+            if (index === -1) {
+                buffer.push(event);
+            } else {
+                buffer.splice(index, 0, event);
+            }
         } else {
             const callId = content.call_id;
             this.callEventBuffer.push(event);
@@ -115,10 +120,12 @@ export class CallEventHandler {
 
             const buffer = this.toDeviceEventBuffers.get(callId);
 
-            while (buffer.length > 0 && buffer[0].getContent().seq === content.seq + 1) {
-                const nextEvent = buffer.pop();
+            let nextEvent = buffer && buffer.shift();
+
+            while (nextEvent && nextEvent.getContent().seq === this.nextSeqByCall.get(callId)) {
                 this.callEventBuffer.push(nextEvent);
                 this.nextSeqByCall.set(callId, nextEvent.getContent().seq + 1);
+                nextEvent = buffer.shift();
             }
         }
     };