Returned MatrixRTC encryption key is undefined is not known

This changes the return type of some public functions
matrix-org · Sep 23, 2024 · 4ae5471 · 4ae5471
1 parent dbd7d26
commit 4ae5471
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Showing 2 changed files with 17 additions and 5 deletions.
diff --git a/spec/unit/matrixrtc/MatrixRTCSession.spec.ts b/spec/unit/matrixrtc/MatrixRTCSession.spec.ts
@@ -1274,6 +1274,9 @@ describe("MatrixRTCSession", () => {
 
         bobKeys = sess.getKeysForParticipant("@bob:example.org", "bobsphone")!;
         expect(bobKeys).toHaveLength(5);
+        expect(bobKeys[1]).toBeUndefined();
+        expect(bobKeys[2]).toBeUndefined();
+        expect(bobKeys[3]).toBeUndefined();
         expect(bobKeys[4]).toEqual(Buffer.from("this is the key", "utf-8"));
         expect(sess!.statistics.counters.roomEventEncryptionKeysReceived).toEqual(2);
     });

diff --git a/src/matrixrtc/MatrixRTCSession.ts b/src/matrixrtc/MatrixRTCSession.ts
@@ -137,7 +137,7 @@ export class MatrixRTCSession extends TypedEventEmitter<MatrixRTCSessionEvent, M
     private manageMediaKeys = false;
     private useLegacyMemberEvents = true;
     // userId:deviceId => array of (key, timestamp)
-    private encryptionKeys = new Map<string, Array<{ key: Uint8Array; timestamp: number }>>();
+    private encryptionKeys = new Map<string, Array<{ key: Uint8Array; timestamp: number } | undefined>>();
     private lastEncryptionKeyUpdateRequest?: number;
 
     // We use this to store the last membership fingerprints we saw, so we can proactively re-send encryption keys
@@ -412,18 +412,21 @@ export class MatrixRTCSession extends TypedEventEmitter<MatrixRTCSessionEvent, M
      * @param deviceId the device ID of the participant
      * @returns The encryption keys for the given participant, or undefined if they are not known.
      */
-    public getKeysForParticipant(userId: string, deviceId: string): Array<Uint8Array> | undefined {
-        return this.encryptionKeys.get(getParticipantId(userId, deviceId))?.map((entry) => entry.key);
+    public getKeysForParticipant(userId: string, deviceId: string): Array<Uint8Array | undefined> | undefined {
+        return this.encryptionKeys.get(getParticipantId(userId, deviceId))?.map((entry) => entry?.key);
     }
 
     /**
      * A map of keys used to encrypt and decrypt (we are using a symmetric
      * cipher) given participant's media. This also includes our own key
      */
-    public getEncryptionKeys(): IterableIterator<[string, Array<Uint8Array>]> {
+    public getEncryptionKeys(): IterableIterator<[string, Array<Uint8Array | undefined>]> {
         // the returned array doesn't contain the timestamps
         return Array.from(this.encryptionKeys.entries())
-            .map(([participantId, keys]): [string, Uint8Array[]] => [participantId, keys.map((k) => k.key)])
+            .map(([participantId, keys]): [string, (Uint8Array | undefined)[]] => [
+                participantId,
+                keys.map((k) => k?.key),
+            ])
             .values();
     }
 
@@ -483,6 +486,7 @@ export class MatrixRTCSession extends TypedEventEmitter<MatrixRTCSessionEvent, M
             }
         }
 
+        // n.b. this will extend the array if necessary and fill in the gaps with undefined
         participantKeys[encryptionKeyIndex] = {
             key: keyBin,
             timestamp,
@@ -582,6 +586,11 @@ export class MatrixRTCSession extends TypedEventEmitter<MatrixRTCSessionEvent, M
         const keyIndexToSend = indexToSend ?? this.currentEncryptionKeyIndex;
         const keyToSend = myKeys[keyIndexToSend];
 
+        if (!keyToSend) {
+            logger.warn(`Tried to send encryption key at index ${indexToSend} but no key found`);
+            return;
+        }
+
         try {
             const content: EncryptionKeysEventContent = {
                 keys: [