From 85e0ddf518ec9c91f5c9e9e66cfdcf260040da2b Mon Sep 17 00:00:00 2001
From: Richard van der Hoff <richard@matrix.org>
Date: Fri, 23 Jun 2023 16:12:37 +0100
Subject: [PATCH] Implement `VerificationRequest.cancel`

---
 spec/integ/crypto/verification.spec.ts | 36 +++++++++++++++++++++++++-
 src/crypto-api/verification.ts         |  2 +-
 src/rust-crypto/verification.ts        |  9 ++++---
 3 files changed, 42 insertions(+), 5 deletions(-)

diff --git a/spec/integ/crypto/verification.spec.ts b/spec/integ/crypto/verification.spec.ts
index 11be866b85b..e95a82fccbe 100644
--- a/spec/integ/crypto/verification.spec.ts
+++ b/spec/integ/crypto/verification.spec.ts
@@ -290,6 +290,10 @@ describe.each(Object.entries(CRYPTO_BACKENDS))("verification (%s)", (backend: st
             await verificationPromise;
             expect(request.phase).toEqual(VerificationPhase.Done);
 
+            // at this point, cancelling should do nothing.
+            await request.cancel();
+            expect(request.phase).toEqual(VerificationPhase.Done);
+
             // we're done with the temporary keypair
             olmSAS.free();
         });
@@ -406,11 +410,41 @@ describe.each(Object.entries(CRYPTO_BACKENDS))("verification (%s)", (backend: st
             await verificationPromise;
             expect(request.phase).toEqual(VerificationPhase.Done);
         });
+    });
+
+    describe("cancellation", () => {
+        beforeEach(async () => {
+            // pretend that we have another device, which we will start verifying
+            e2eKeyResponder.addDeviceKeys(TEST_USER_ID, TEST_DEVICE_ID, SIGNED_TEST_DEVICE_DATA);
 
-        it("can cancel during the SAS phase", async () => {
             aliceClient = await startTestClient();
             await waitForDeviceList();
+        });
+
+        it("can cancel during the Ready phase", async () => {
+            // have alice initiate a verification. She should send a m.key.verification.request
+            const [, request] = await Promise.all([
+                expectSendToDeviceMessage("m.key.verification.request"),
+                aliceClient.getCrypto()!.requestDeviceVerification(TEST_USER_ID, TEST_DEVICE_ID),
+            ]);
+            const transactionId = request.transactionId!;
 
+            // The dummy device replies with an m.key.verification.ready...
+            returnToDeviceMessageFromSync(buildReadyMessage(transactionId, ["m.sas.v1"]));
+            await waitForVerificationRequestChanged(request);
+
+            // now alice changes her mind
+            const [requestBody] = await Promise.all([
+                expectSendToDeviceMessage("m.key.verification.cancel"),
+                request.cancel(),
+            ]);
+            const toDeviceMessage = requestBody.messages[TEST_USER_ID][TEST_DEVICE_ID];
+            expect(toDeviceMessage.transaction_id).toEqual(transactionId);
+            expect(toDeviceMessage.code).toEqual("m.user");
+            expect(request.phase).toEqual(VerificationPhase.Cancelled);
+        });
+
+        it("can cancel during the SAS phase", async () => {
             // have alice initiate a verification. She should send a m.key.verification.request
             const [, request] = await Promise.all([
                 expectSendToDeviceMessage("m.key.verification.request"),
diff --git a/src/crypto-api/verification.ts b/src/crypto-api/verification.ts
index daaf405b1d1..fc5c75bc7a0 100644
--- a/src/crypto-api/verification.ts
+++ b/src/crypto-api/verification.ts
@@ -108,7 +108,7 @@ export interface VerificationRequest
      * Cancels the request, sending a cancellation to the other party
      *
      * @param params - Details for the cancellation, including `reason` (defaults to "User declined"), and `code`
-     *    (defaults to `m.user`).
+     *    (defaults to `m.user`). **Deprecated**: this parameter is ignored by the Rust cryptography implementation.
      *
      * @returns Promise which resolves when the event has been sent.
      */
diff --git a/src/rust-crypto/verification.ts b/src/rust-crypto/verification.ts
index f4c8f3697fd..7fb314c78d9 100644
--- a/src/rust-crypto/verification.ts
+++ b/src/rust-crypto/verification.ts
@@ -42,7 +42,7 @@ export class RustVerificationRequest
 
     public constructor(
         private readonly inner: RustSdkCryptoJs.VerificationRequest,
-        outgoingRequestProcessor: OutgoingRequestProcessor,
+        private readonly outgoingRequestProcessor: OutgoingRequestProcessor,
     ) {
         super();
 
@@ -210,8 +210,11 @@ export class RustVerificationRequest
      *
      * @returns Promise which resolves when the event has been sent.
      */
-    public cancel(params?: { reason?: string; code?: string }): Promise<void> {
-        throw new Error("not implemented");
+    public async cancel(params?: { reason?: string; code?: string }): Promise<void> {
+        const req: undefined | OutgoingRequest = this.inner.cancel();
+        if (req) {
+            await this.outgoingRequestProcessor.makeOutgoingRequest(req);
+        }
     }
 
     /**