feat(widget): Support for avatars in calls via msc4039 (#6354)

Allows to get the avatars in Element Call widget !
Using
[MSC4039](https://github.com/nordeck/matrix-spec-proposals/blob/nic/feat/widgetapi-upload-files/proposals/4039-widget-api-media.md)

Counter part of web support:
- element-hq/element-web#32755
- element-hq/element-call#3780

Needs a EC PR to support passing data as base64 via the widget json API
- element-hq/element-call#3818

Author: BillCarsonFr

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

@@ -266,6 +266,7 @@ pub fn get_element_call_required_permissions(
         requires_client: true,
         update_delayed_event: true,
         send_delayed_event: true,
+        download_files: true,
     }
 }
 
@@ -331,6 +332,8 @@ pub struct WidgetCapabilities {
     pub update_delayed_event: bool,
     /// This allows the widget to send events with a delay.
     pub send_delayed_event: bool,
+    /// This allows the widget to download files (avatars)
+    pub download_files: bool,
 }
 
 impl From<WidgetCapabilities> for matrix_sdk::widget::Capabilities {
@@ -341,6 +344,7 @@ impl From<WidgetCapabilities> for matrix_sdk::widget::Capabilities {
             requires_client: value.requires_client,
             update_delayed_event: value.update_delayed_event,
             send_delayed_event: value.send_delayed_event,
+            download_file: value.download_files,
         }
     }
 }
@@ -353,6 +357,7 @@ impl From<matrix_sdk::widget::Capabilities> for WidgetCapabilities {
             requires_client: value.requires_client,
             update_delayed_event: value.update_delayed_event,
             send_delayed_event: value.send_delayed_event,
+            download_files: value.download_file,
         }
     }
 }
@@ -553,5 +558,8 @@ mod tests {
         // RTC decline
         cap_assert("org.matrix.msc2762.receive.event:org.matrix.msc4310.rtc.decline");
         cap_assert("org.matrix.msc2762.send.event:org.matrix.msc4310.rtc.decline");
+
+        // Download avatars
+        cap_assert("org.matrix.msc4039.download_file");
     }
 }

crates/matrix-sdk/CHANGELOG.md

@@ -89,6 +89,9 @@ All notable changes to this project will be documented in this file.
   to true will now trigger a download of all historical keys for the room in
   question from the client's key backup.
   ([#6017](https://github.com/matrix-org/matrix-rust-sdk/pull/6017))
+- Add widget partial support for MSC4039. Allows widgets to download non-encrypted files from the
+  content repository (like avatars).
+  ([#6354](https://github.com/matrix-org/matrix-rust-sdk/pull/6354))
 
 ### Bugfix
 

crates/matrix-sdk/src/widget/capabilities.rs

@@ -57,6 +57,9 @@ pub struct Capabilities {
     pub update_delayed_event: bool,
     /// This allows the widget to send events with a delay.
     pub send_delayed_event: bool,
+
+    /// This allows the widget to download files as per MSC4039.
+    pub download_file: bool,
 }
 
 impl Capabilities {
@@ -114,6 +117,8 @@ pub(super) const REQUIRES_CLIENT: &str = "io.element.requires_client";
 pub(super) const SEND_DELAYED_EVENT: &str = "org.matrix.msc4157.send.delayed_event";
 pub(super) const UPDATE_DELAYED_EVENT: &str = "org.matrix.msc4157.update_delayed_event";
 
+pub(super) const DOWNLOAD_FILE: &str = "org.matrix.msc4039.download_file";
+
 impl Serialize for Capabilities {
     fn serialize<S>(&self, serializer: S) -> Result<S::Ok, S::Error>
     where
@@ -174,6 +179,9 @@ impl Serialize for Capabilities {
         if self.send_delayed_event {
             seq.serialize_element(SEND_DELAYED_EVENT)?;
         }
+        if self.download_file {
+            seq.serialize_element(DOWNLOAD_FILE)?;
+        }
         for filter in &self.read {
             let name = match filter {
                 Filter::MessageLike(_) => READ_EVENT,
@@ -204,6 +212,7 @@ impl<'de> Deserialize<'de> for Capabilities {
             RequiresClient,
             UpdateDelayedEvent,
             SendDelayedEvent,
+            DownloadFile,
             Read(Filter),
             Send(Filter),
             Unknown,
@@ -224,6 +233,9 @@ impl<'de> Deserialize<'de> for Capabilities {
                 if s == SEND_DELAYED_EVENT {
                     return Ok(Self::SendDelayedEvent);
                 }
+                if s == DOWNLOAD_FILE {
+                    return Ok(Self::DownloadFile);
+                }
 
                 match s.split_once(':') {
                     Some((READ_EVENT, filter_s)) => Ok(Permission::Read(Filter::MessageLike(
@@ -284,6 +296,7 @@ impl<'de> Deserialize<'de> for Capabilities {
                 Permission::Unknown => {}
                 Permission::UpdateDelayedEvent => capabilities.update_delayed_event = true,
                 Permission::SendDelayedEvent => capabilities.send_delayed_event = true,
+                Permission::DownloadFile => capabilities.download_file = true,
             }
         }
 
@@ -321,7 +334,8 @@ mod tests {
             "org.matrix.msc2762.send.state_event:org.matrix.msc3401.call.member#@user:matrix.server",
             "org.matrix.msc3819.send.to_device:io.element.call.encryption_keys",
             "org.matrix.msc4157.send.delayed_event",
-            "org.matrix.msc4157.update_delayed_event"
+            "org.matrix.msc4157.update_delayed_event",
+            "org.matrix.msc4039.download_file"
         ]"#;
 
         let parsed = serde_json::from_str::<Capabilities>(capabilities_str).unwrap();
@@ -351,6 +365,7 @@ mod tests {
             requires_client: true,
             update_delayed_event: true,
             send_delayed_event: true,
+            download_file: true,
         };
 
         assert_eq!(parsed, expected);
@@ -381,6 +396,7 @@ mod tests {
             requires_client: true,
             update_delayed_event: false,
             send_delayed_event: false,
+            download_file: false,
         };
 
         let capabilities_str = serde_json::to_string(&capabilities).unwrap();

crates/matrix-sdk/src/widget/machine/driver_req.rs

@@ -17,7 +17,7 @@
 use std::{collections::BTreeMap, marker::PhantomData};
 
 use ruma::{
-    OwnedUserId,
+    OwnedMxcUri, OwnedUserId,
     api::client::{account::request_openid_token, delayed_events::update_delayed_event},
     events::{AnyStateEvent, AnyTimelineEvent, AnyToDeviceEventContent},
     serde::Raw,
@@ -31,7 +31,7 @@ use super::{
     Action, MatrixDriverRequestMeta, SendToDeviceEventResponse, WidgetMachine,
     from_widget::SendEventResponse, incoming::MatrixDriverResponse,
 };
-use crate::widget::{Capabilities, StateKeySelector};
+use crate::widget::{Capabilities, StateKeySelector, machine::from_widget::DownloadFileResponse};
 
 #[derive(Clone, Debug)]
 pub(crate) enum MatrixDriverRequestData {
@@ -59,6 +59,9 @@ pub(crate) enum MatrixDriverRequestData {
 
     /// Data for sending a UpdateDelayedEvent client server api request.
     UpdateDelayedEvent(UpdateDelayedEventRequest),
+
+    /// Request a download of a file.
+    DownloadFile(DownloadFileRequest),
 }
 
 /// A handle to a pending `toWidget` request.
@@ -339,3 +342,19 @@ impl FromMatrixDriverResponse for update_delayed_event::unstable::Response {
         }
     }
 }
+
+#[derive(Deserialize, Debug, Clone)]
+pub(crate) struct DownloadFileRequest {
+    // The MXC url of the file to download.
+    pub(crate) content_uri: OwnedMxcUri,
+}
+
+impl MatrixDriverRequest for DownloadFileRequest {
+    type Response = DownloadFileResponse;
+}
+
+impl From<DownloadFileRequest> for MatrixDriverRequestData {
+    fn from(req: DownloadFileRequest) -> Self {
+        MatrixDriverRequestData::DownloadFile(req)
+    }
+}

crates/matrix-sdk/src/widget/machine/from_widget.rs

@@ -22,7 +22,7 @@ use ruma::{
         error::{ErrorBody, StandardErrorBody},
     },
     events::AnyTimelineEvent,
-    serde::Raw,
+    serde::{Base64, Raw},
 };
 use serde::{Deserialize, Serialize};
 use tracing::error;
@@ -33,7 +33,10 @@ use super::{
 };
 use crate::{
     Error, HttpError, RumaApiError,
-    widget::{StateKeySelector, machine::driver_req::FromMatrixDriverResponse},
+    widget::{
+        StateKeySelector,
+        machine::driver_req::{DownloadFileRequest, FromMatrixDriverResponse},
+    },
 };
 
 #[derive(Deserialize, Debug)]
@@ -49,6 +52,8 @@ pub(super) enum FromWidgetRequest {
     SendToDevice(SendToDeviceRequest),
     #[serde(rename = "org.matrix.msc4157.update_delayed_event")]
     DelayedEventUpdate(UpdateDelayedEventRequest),
+    #[serde(rename = "org.matrix.msc4039.download_file")]
+    DownloadFile(DownloadFileRequest),
 }
 
 /// The full response a client sends to a [`FromWidgetRequest`] in case of an
@@ -145,6 +150,7 @@ impl SupportedApiVersionsResponse {
                 ApiVersion::MSC2762UpdateState,
                 ApiVersion::MSC2871,
                 ApiVersion::MSC3819,
+                ApiVersion::MSC4039,
             ],
         }
     }
@@ -192,6 +198,9 @@ pub(super) enum ApiVersion {
     /// Supports access to the TURN servers.
     #[serde(rename = "town.robin.msc3846")]
     MSC3846,
+
+    #[serde(rename = "org.matrix.msc4039")]
+    MSC4039,
 }
 
 #[derive(Deserialize, Debug)]
@@ -276,3 +285,27 @@ impl FromMatrixDriverResponse for SendToDeviceEventResponse {
         }
     }
 }
+
+/// Response for a download file request.
+/// https://github.com/matrix-org/matrix-spec-proposals/pull/4039
+#[derive(Serialize, Debug)]
+pub(crate) struct DownloadFileResponse {
+    // The binary file content in a format that can cross the
+    // widget-driver-api boundary.
+    #[serde(rename = "file")]
+    pub(crate) file_data_base64: Base64,
+}
+
+impl FromMatrixDriverResponse for DownloadFileResponse {
+    fn from_response(matrix_driver_response: MatrixDriverResponse) -> Option<Self> {
+        match matrix_driver_response {
+            MatrixDriverResponse::FileDownloaded(resp) => {
+                Some(Self { file_data_base64: resp.file_data_base64 })
+            }
+            _ => {
+                error!("bug in MatrixDriver, received wrong event response");
+                None
+            }
+        }
+    }
+}

crates/matrix-sdk/src/widget/machine/incoming.rs

@@ -28,7 +28,7 @@ use super::{
     from_widget::{FromWidgetRequest, SendEventResponse},
     to_widget::ToWidgetResponse,
 };
-use crate::widget::Capabilities;
+use crate::widget::{Capabilities, machine::from_widget::DownloadFileResponse};
 
 /// Incoming message for the widget client side module that it must process.
 pub(crate) enum IncomingMessage {
@@ -87,6 +87,8 @@ pub(crate) enum MatrixDriverResponse {
     /// Client updated a delayed event.
     /// A response to a [`MatrixDriverRequestData::UpdateDelayedEvent`] command.
     DelayedEventUpdated(delayed_events::update_delayed_event::unstable::Response),
+    /// The client successfully downloaded a file from a widget action.
+    FileDownloaded(DownloadFileResponse),
 }
 
 pub(super) struct IncomingWidgetMessage {
@@ -136,3 +138,58 @@ impl<'de> Deserialize<'de> for IncomingWidgetMessage {
         Ok(Self { widget_id, request_id, kind })
     }
 }
+
+#[cfg(test)]
+mod tests {
+    use assert_matches2::assert_let;
+
+    use crate::widget::machine::{
+        from_widget::FromWidgetRequest,
+        incoming::{IncomingWidgetMessage, IncomingWidgetMessageKind},
+    };
+
+    #[test]
+    fn parse_download_file_widget_action() {
+        let raw = r#"
+        {
+            "api": "fromWidget",
+            "widgetId": "aGNStSuL3hhIISSCXgpt15j2",
+            "requestId": "generated-id-1234",
+            "action": "org.matrix.msc4039.download_file",
+            "data": {
+                "content_uri": "mxc://server/id"
+            }
+        }
+        "#;
+
+        assert_let!(
+            IncomingWidgetMessageKind::Request(incoming_request) =
+                serde_json::from_str::<IncomingWidgetMessage>(raw).unwrap().kind
+        );
+        assert_let!(FromWidgetRequest::DownloadFile(req) = incoming_request.deserialize().unwrap());
+
+        assert_eq!(req.content_uri, "mxc://server/id");
+    }
+    #[test]
+    fn parse_download_file_request_with_non_mxc_url() {
+        let raw = r#"
+        {
+            "api": "fromWidget",
+            "widgetId": "aGNStSuL3hhIISSCXgpt15j2",
+            "requestId": "generated-id-1234",
+            "action": "org.matrix.msc4039.download_file",
+            "data": {
+                "content_uri": "https://server/id"
+            }
+        }
+        "#;
+
+        assert_let!(
+            IncomingWidgetMessageKind::Request(incoming_request) =
+                serde_json::from_str::<IncomingWidgetMessage>(raw).unwrap().kind
+        );
+        assert_let!(FromWidgetRequest::DownloadFile(req) = incoming_request.deserialize().unwrap());
+
+        assert!(!req.content_uri.is_valid());
+    }
+}