From ee6b804804215276f35c56afc34093ef2a134355 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Damir=20Jeli=C4=87?= <poljar@termina.org.uk>
Date: Mon, 28 Jun 2021 15:28:30 +0200
Subject: [PATCH] crypto: Allow QR code verifications to get into the cancelled
 state as well.

---
 matrix_sdk_crypto/src/verification/machine.rs | 13 ++++++--
 matrix_sdk_crypto/src/verification/qrcode.rs  | 31 ++++++++++++++++++-
 2 files changed, 40 insertions(+), 4 deletions(-)

diff --git a/matrix_sdk_crypto/src/verification/machine.rs b/matrix_sdk_crypto/src/verification/machine.rs
index 494f9b65..a2a4abab 100644
--- a/matrix_sdk_crypto/src/verification/machine.rs
+++ b/matrix_sdk_crypto/src/verification/machine.rs
@@ -287,9 +287,16 @@ impl VerificationMachine {
                         verification.receive_cancel(event.sender(), c);
                     }
 
-                    if let Some(sas) = self.get_sas(event.sender(), flow_id.as_str()) {
-                        // This won't produce an outgoing content
-                        let _ = sas.receive_any_event(event.sender(), &content);
+                    if let Some(verification) =
+                        self.get_verification(event.sender(), flow_id.as_str())
+                    {
+                        match verification {
+                            Verification::SasV1(sas) => {
+                                // This won't produce an outgoing content
+                                let _ = sas.receive_any_event(event.sender(), &content);
+                            }
+                            Verification::QrV1(qr) => qr.receive_cancel(event.sender(), c),
+                        }
                     }
                 }
                 AnyVerificationContent::Ready(c) => {
diff --git a/matrix_sdk_crypto/src/verification/qrcode.rs b/matrix_sdk_crypto/src/verification/qrcode.rs
index b1e7adfd..0dd4b576 100644
--- a/matrix_sdk_crypto/src/verification/qrcode.rs
+++ b/matrix_sdk_crypto/src/verification/qrcode.rs
@@ -36,9 +36,10 @@ use ruma::{
     DeviceId, DeviceIdBox, DeviceKeyAlgorithm, RoomId, UserId,
 };
 use thiserror::Error;
+use tracing::trace;
 
 use super::{
-    event_enums::{DoneContent, OutgoingContent, OwnedStartContent, StartContent},
+    event_enums::{CancelContent, DoneContent, OutgoingContent, OwnedStartContent, StartContent},
     Cancelled, Done, FlowId, IdentitiesBeingVerified, VerificationResult,
 };
 use crate::{
@@ -393,6 +394,28 @@ impl QrVerification {
         }
     }
 
+    pub(crate) fn receive_cancel(&self, sender: &UserId, content: &CancelContent<'_>) {
+        if sender == self.other_user_id() {
+            let mut state = self.state.lock().unwrap();
+
+            let new_state = match &*state {
+                InnerState::Created(s) => s.clone().into_cancelled(content),
+                InnerState::Scanned(s) => s.clone().into_cancelled(content),
+                InnerState::Confirmed(s) => s.clone().into_cancelled(content),
+                InnerState::Reciprocated(s) => s.clone().into_cancelled(content),
+                InnerState::Done(_) | InnerState::Cancelled(_) => return,
+            };
+
+            trace!(
+                sender = sender.as_str(),
+                code = content.cancel_code().as_str(),
+                "Cancelling a QR verification, other user has cancelled"
+            );
+
+            *state = InnerState::Cancelled(new_state);
+        }
+    }
+
     fn generate_secret() -> String {
         let mut shared_secret = [0u8; SECRET_SIZE];
         getrandom::getrandom(&mut shared_secret)
@@ -609,6 +632,12 @@ struct QrState<S: Clone> {
     state: S,
 }
 
+impl<S: Clone> QrState<S> {
+    pub fn into_cancelled(self, content: &CancelContent<'_>) -> QrState<Cancelled> {
+        QrState { state: Cancelled::new(false, content.cancel_code().to_owned()) }
+    }
+}
+
 #[derive(Clone, Debug)]
 struct Created {
     secret: String,