crypto: Notify when the identity status of a user changes

bindings/matrix-sdk-ffi/src/identity_status_change.rs

@@ -0,0 +1,31 @@
+// Copyright 2024 The Matrix.org Foundation C.I.C.
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+#[derive(uniffi::Record)]
+pub struct IdentityStatusChange {
+    /// The user ID of the user whose identity status changed
+    pub user_id: String,
+
+    /// The new state of the identity of the user. One of:
+    ///
+    /// * Verified
+    /// * Pinned
+    /// * PinViolation
+    /// * PreviouslyVerified
+    ///
+    /// See
+    /// [`matrix_sdk_crypto::identities::room_identity_state::RoomIdentityState`]
+    /// for details.
+    pub changed_to: String,
+}

bindings/matrix-sdk-ffi/src/lib.rs

@@ -29,6 +29,7 @@ mod encryption;
 mod error;
 mod event;
 mod helpers;
+mod identity_status_change;
 mod notification;
 mod notification_settings;
 mod platform;

bindings/matrix-sdk-ffi/src/room.rs

@@ -1,6 +1,7 @@
 use std::{collections::HashMap, sync::Arc};
 
 use anyhow::{Context, Result};
+use futures_util::StreamExt;
 use matrix_sdk::{
     crypto::LocalTrust,
     event_cache::paginator::PaginatorError,
@@ -35,6 +36,7 @@ use crate::{
     chunk_iterator::ChunkIterator,
     error::{ClientError, MediaInfoError, RoomError},
     event::{MessageLikeEventType, StateEventType},
+    identity_status_change::IdentityStatusChange,
     room_info::RoomInfo,
     room_member::RoomMember,
     ruma::{ImageInfo, Mentions, NotifyType},
@@ -582,6 +584,41 @@ impl Room {
         })))
     }
 
+    pub fn subscribe_to_identity_status_changes(
+        &self,
+        listener: Box<dyn IdentityStatusChangeListener>,
+    ) -> Arc<TaskHandle> {
+        let room = self.inner.clone();
+        Arc::new(TaskHandle::new(RUNTIME.spawn(async move {
+            let status_changes = room.subscribe_to_identity_status_changes().await;
+            if let Ok(mut status_changes) = status_changes {
+                // TODO: what to do with failures?
+                while let Some(identity_status_changes) = status_changes.next().await {
+                    listener.call(
+                        identity_status_changes
+                            .iter()
+                            .map(|change| {
+                                let user_id = change.user_id.to_string();
+                                let changed_to = match change.changed_to {
+                                    matrix_sdk::crypto::IdentityState::Verified => "Verified",
+                                    matrix_sdk::crypto::IdentityState::Pinned => "Pinned",
+                                    matrix_sdk::crypto::IdentityState::PinViolation => {
+                                        "PinViolation"
+                                    }
+                                    matrix_sdk::crypto::IdentityState::PreviouslyVerified => {
+                                        "PreviouslyVerified"
+                                    }
+                                }
+                                .to_owned();
+                                IdentityStatusChange { user_id, changed_to }
+                            })
+                            .collect(),
+                    );
+                }
+            }
+        })))
+    }
+
     /// Set (or unset) a flag on the room to indicate that the user has
     /// explicitly marked it as unread.
     pub async fn set_unread_flag(&self, new_value: bool) -> Result<(), ClientError> {
@@ -898,6 +935,11 @@ pub trait TypingNotificationsListener: Sync + Send {
     fn call(&self, typing_user_ids: Vec<String>);
 }
 
+#[uniffi::export(callback_interface)]
+pub trait IdentityStatusChangeListener: Sync + Send {
+    fn call(&self, identity_status_change: Vec<IdentityStatusChange>);
+}
+
 #[derive(uniffi::Object)]
 pub struct RoomMembersIterator {
     chunk_iterator: ChunkIterator<matrix_sdk::room::RoomMember>,

crates/matrix-sdk-crypto/src/identities/mod.rs

@@ -42,6 +42,7 @@
 //! `/keys/query` API call.
 pub(crate) mod device;
 pub(crate) mod manager;
+pub(crate) mod room_identity_state;
 pub(crate) mod user;
 
 use std::sync::{