matrix_sdk/widget/
capabilities.rs

1// Copyright 2023 The Matrix.org Foundation C.I.C.
2//
3// Licensed under the Apache License, Version 2.0 (the "License");
4// you may not use this file except in compliance with the License.
5// You may obtain a copy of the License at
6//
7//     http://www.apache.org/licenses/LICENSE-2.0
8//
9// Unless required by applicable law or agreed to in writing, software
10// distributed under the License is distributed on an "AS IS" BASIS,
11// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
12// See the License for the specific language governing permissions and
13// limitations under the License.
14
15//! Types and traits related to the capabilities that a widget can request from
16//! a client.
17
18use std::{fmt, future::Future};
19
20use matrix_sdk_common::{SendOutsideWasm, SyncOutsideWasm};
21use serde::{Deserialize, Deserializer, Serialize, Serializer, ser::SerializeSeq};
22use tracing::{debug, warn};
23
24use super::{
25    MessageLikeEventFilter, StateEventFilter,
26    filter::{Filter, FilterInput, ToDeviceEventFilter},
27};
28
29/// Must be implemented by a component that provides functionality of deciding
30/// whether a widget is allowed to use certain capabilities (typically by
31/// providing a prompt to the user).
32pub trait CapabilitiesProvider: SendOutsideWasm + SyncOutsideWasm + 'static {
33    /// Receives a request for given capabilities and returns the actual
34    /// capabilities that the clients grants to a given widget (usually by
35    /// prompting the user).
36    fn acquire_capabilities(
37        &self,
38        capabilities: Capabilities,
39    ) -> impl Future<Output = Capabilities> + SendOutsideWasm;
40}
41
42/// Capabilities that a widget can request from a client.
43#[derive(Clone, Debug, Default)]
44#[cfg_attr(test, derive(PartialEq))]
45pub struct Capabilities {
46    /// Types of the messages that a widget wants to be able to fetch.
47    pub read: Vec<Filter>,
48    /// Types of the messages that a widget wants to be able to send.
49    pub send: Vec<Filter>,
50    /// If this capability is requested by the widget, it can not operate
51    /// separately from the Matrix client.
52    ///
53    /// This means clients should not offer to open the widget in a separate
54    /// browser/tab/webview that is not connected to the postmessage widget-api.
55    pub requires_client: bool,
56    /// This allows the widget to ask the client to update delayed events.
57    pub update_delayed_event: bool,
58    /// This allows the widget to send events with a delay.
59    pub send_delayed_event: bool,
60
61    /// This allows the widget to download files as per MSC4039.
62    pub download_file: bool,
63
64    /// This allows the widget to discover the RTC transports advertised by the
65    /// homeserver as per MSC4515.
66    pub rtc_transports: bool,
67}
68
69impl Capabilities {
70    /// Checks if a given event is allowed to be forwarded to the widget.
71    ///
72    /// - `event_filter_input` is a minimized event representation that contains
73    ///   only the information needed to check if the widget is allowed to
74    ///   receive the event. (See [`FilterInput`])
75    pub(super) fn allow_reading<'a>(
76        &self,
77        event_filter_input: impl TryInto<FilterInput<'a>>,
78    ) -> bool {
79        match &event_filter_input.try_into() {
80            Err(_) => {
81                warn!("Failed to convert event into filter input for `allow_reading`.");
82                false
83            }
84            Ok(filter_input) => self.read.iter().any(|f| f.matches(filter_input)),
85        }
86    }
87
88    /// Checks if a given event is allowed to be sent by the widget.
89    ///
90    /// - `event_filter_input` is a minimized event representation that contains
91    ///   only the information needed to check if the widget is allowed to send
92    ///   the event to a matrix room. (See [`FilterInput`])
93    pub(super) fn allow_sending<'a>(
94        &self,
95        event_filter_input: impl TryInto<FilterInput<'a>>,
96    ) -> bool {
97        match &event_filter_input.try_into() {
98            Err(_) => {
99                warn!("Failed to convert event into filter input for `allow_sending`.");
100                false
101            }
102            Ok(filter_input) => self.send.iter().any(|f| f.matches(filter_input)),
103        }
104    }
105
106    /// Checks if a filter exists for the given event type, useful for
107    /// optimization. Avoids unnecessary read event requests when no matching
108    /// filter is present.
109    pub(super) fn has_read_filter_for_type(&self, event_type: &str) -> bool {
110        self.read.iter().any(|f| f.filter_event_type() == event_type)
111    }
112}
113
114pub(super) const SEND_EVENT: &str = "org.matrix.msc2762.send.event";
115pub(super) const READ_EVENT: &str = "org.matrix.msc2762.receive.event";
116pub(super) const SEND_STATE: &str = "org.matrix.msc2762.send.state_event";
117pub(super) const READ_STATE: &str = "org.matrix.msc2762.receive.state_event";
118pub(super) const SEND_TODEVICE: &str = "org.matrix.msc3819.send.to_device";
119pub(super) const READ_TODEVICE: &str = "org.matrix.msc3819.receive.to_device";
120pub(super) const REQUIRES_CLIENT: &str = "io.element.requires_client";
121pub(super) const SEND_DELAYED_EVENT: &str = "org.matrix.msc4157.send.delayed_event";
122pub(super) const UPDATE_DELAYED_EVENT: &str = "org.matrix.msc4157.update_delayed_event";
123
124pub(super) const DOWNLOAD_FILE: &str = "org.matrix.msc4039.download_file";
125
126pub(super) const RTC_TRANSPORTS: &str = "org.matrix.msc4515.rtc_transports";
127
128impl Serialize for Capabilities {
129    fn serialize<S>(&self, serializer: S) -> Result<S::Ok, S::Error>
130    where
131        S: Serializer,
132    {
133        struct PrintEventFilter<'a>(&'a Filter);
134        impl fmt::Display for PrintEventFilter<'_> {
135            fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
136                match self.0 {
137                    Filter::MessageLike(filter) => PrintMessageLikeEventFilter(filter).fmt(f),
138                    Filter::State(filter) => PrintStateEventFilter(filter).fmt(f),
139                    Filter::ToDevice(filter) => {
140                        // As per MSC 3819 https://github.com/matrix-org/matrix-spec-proposals/pull/3819
141                        // ToDevice capabilities is in the form of `m.send.to_device:<event type>`
142                        // or `m.receive.to_device:<event type>`
143                        write!(f, "{}", filter.event_type)
144                    }
145                }
146            }
147        }
148
149        struct PrintMessageLikeEventFilter<'a>(&'a MessageLikeEventFilter);
150        impl fmt::Display for PrintMessageLikeEventFilter<'_> {
151            fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
152                match self.0 {
153                    MessageLikeEventFilter::WithType(event_type) => {
154                        // TODO: escape `#` as `\#` and `\` as `\\` in event_type
155                        write!(f, "{event_type}")
156                    }
157                    MessageLikeEventFilter::RoomMessageWithMsgtype(msgtype) => {
158                        write!(f, "m.room.message#{msgtype}")
159                    }
160                }
161            }
162        }
163
164        struct PrintStateEventFilter<'a>(&'a StateEventFilter);
165        impl fmt::Display for PrintStateEventFilter<'_> {
166            fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
167                // TODO: escape `#` as `\#` and `\` as `\\` in event_type
168                match self.0 {
169                    StateEventFilter::WithType(event_type) => write!(f, "{event_type}"),
170                    StateEventFilter::WithTypeAndStateKey(event_type, state_key) => {
171                        write!(f, "{event_type}#{state_key}")
172                    }
173                }
174            }
175        }
176
177        let mut seq = serializer.serialize_seq(None)?;
178
179        if self.requires_client {
180            seq.serialize_element(REQUIRES_CLIENT)?;
181        }
182        if self.update_delayed_event {
183            seq.serialize_element(UPDATE_DELAYED_EVENT)?;
184        }
185        if self.send_delayed_event {
186            seq.serialize_element(SEND_DELAYED_EVENT)?;
187        }
188        if self.download_file {
189            seq.serialize_element(DOWNLOAD_FILE)?;
190        }
191        if self.rtc_transports {
192            seq.serialize_element(RTC_TRANSPORTS)?;
193        }
194        for filter in &self.read {
195            let name = match filter {
196                Filter::MessageLike(_) => READ_EVENT,
197                Filter::State(_) => READ_STATE,
198                Filter::ToDevice(_) => READ_TODEVICE,
199            };
200            seq.serialize_element(&format!("{name}:{}", PrintEventFilter(filter)))?;
201        }
202        for filter in &self.send {
203            let name = match filter {
204                Filter::MessageLike(_) => SEND_EVENT,
205                Filter::State(_) => SEND_STATE,
206                Filter::ToDevice(_) => SEND_TODEVICE,
207            };
208            seq.serialize_element(&format!("{name}:{}", PrintEventFilter(filter)))?;
209        }
210
211        seq.end()
212    }
213}
214
215impl<'de> Deserialize<'de> for Capabilities {
216    fn deserialize<D>(deserializer: D) -> Result<Self, D::Error>
217    where
218        D: Deserializer<'de>,
219    {
220        enum Permission {
221            RequiresClient,
222            UpdateDelayedEvent,
223            SendDelayedEvent,
224            DownloadFile,
225            RtcTransports,
226            Read(Filter),
227            Send(Filter),
228            Unknown,
229        }
230
231        impl<'de> Deserialize<'de> for Permission {
232            fn deserialize<D>(deserializer: D) -> Result<Self, D::Error>
233            where
234                D: Deserializer<'de>,
235            {
236                let s = ruma::serde::deserialize_cow_str(deserializer)?;
237                if s == REQUIRES_CLIENT {
238                    return Ok(Self::RequiresClient);
239                }
240                if s == UPDATE_DELAYED_EVENT {
241                    return Ok(Self::UpdateDelayedEvent);
242                }
243                if s == SEND_DELAYED_EVENT {
244                    return Ok(Self::SendDelayedEvent);
245                }
246                if s == DOWNLOAD_FILE {
247                    return Ok(Self::DownloadFile);
248                }
249                if s == RTC_TRANSPORTS {
250                    return Ok(Self::RtcTransports);
251                }
252
253                match s.split_once(':') {
254                    Some((READ_EVENT, filter_s)) => Ok(Permission::Read(Filter::MessageLike(
255                        parse_message_event_filter(filter_s),
256                    ))),
257                    Some((SEND_EVENT, filter_s)) => Ok(Permission::Send(Filter::MessageLike(
258                        parse_message_event_filter(filter_s),
259                    ))),
260                    Some((READ_STATE, filter_s)) => {
261                        Ok(Permission::Read(Filter::State(parse_state_event_filter(filter_s))))
262                    }
263                    Some((SEND_STATE, filter_s)) => {
264                        Ok(Permission::Send(Filter::State(parse_state_event_filter(filter_s))))
265                    }
266                    Some((READ_TODEVICE, filter_s)) => Ok(Permission::Read(Filter::ToDevice(
267                        parse_to_device_event_filter(filter_s),
268                    ))),
269                    Some((SEND_TODEVICE, filter_s)) => Ok(Permission::Send(Filter::ToDevice(
270                        parse_to_device_event_filter(filter_s),
271                    ))),
272                    _ => {
273                        debug!("Unknown capability `{s}`");
274                        Ok(Self::Unknown)
275                    }
276                }
277            }
278        }
279
280        fn parse_message_event_filter(s: &str) -> MessageLikeEventFilter {
281            match s.strip_prefix("m.room.message#") {
282                Some(msgtype) => MessageLikeEventFilter::RoomMessageWithMsgtype(msgtype.to_owned()),
283                // TODO: Replace `\\` by `\` and `\#` by `#`, enforce no unescaped `#`
284                None => MessageLikeEventFilter::WithType(s.into()),
285            }
286        }
287
288        fn parse_state_event_filter(s: &str) -> StateEventFilter {
289            // TODO: Search for un-escaped `#` only, replace `\\` by `\` and `\#` by `#`
290            match s.split_once('#') {
291                Some((event_type, state_key)) => {
292                    StateEventFilter::WithTypeAndStateKey(event_type.into(), state_key.to_owned())
293                }
294                None => StateEventFilter::WithType(s.into()),
295            }
296        }
297
298        fn parse_to_device_event_filter(s: &str) -> ToDeviceEventFilter {
299            ToDeviceEventFilter::new(s.into())
300        }
301
302        let mut capabilities = Capabilities::default();
303        for capability in Vec::<Permission>::deserialize(deserializer)? {
304            match capability {
305                Permission::RequiresClient => capabilities.requires_client = true,
306                Permission::Read(filter) => capabilities.read.push(filter),
307                Permission::Send(filter) => capabilities.send.push(filter),
308                // ignore unknown capabilities
309                Permission::Unknown => {}
310                Permission::UpdateDelayedEvent => capabilities.update_delayed_event = true,
311                Permission::SendDelayedEvent => capabilities.send_delayed_event = true,
312                Permission::DownloadFile => capabilities.download_file = true,
313                Permission::RtcTransports => capabilities.rtc_transports = true,
314            }
315        }
316
317        Ok(capabilities)
318    }
319}
320
321#[cfg(test)]
322mod tests {
323    use ruma::events::StateEventType;
324
325    use super::*;
326    use crate::widget::filter::ToDeviceEventFilter;
327
328    #[test]
329    fn deserialization_of_no_capabilities() {
330        let capabilities_str = r#"[]"#;
331
332        let parsed = serde_json::from_str::<Capabilities>(capabilities_str).unwrap();
333        let expected = Capabilities::default();
334
335        assert_eq!(parsed, expected);
336    }
337
338    #[test]
339    fn deserialization_of_capabilities() {
340        let capabilities_str = r#"[
341            "m.always_on_screen",
342            "io.element.requires_client",
343            "org.matrix.msc2762.receive.event:org.matrix.rageshake_request",
344            "org.matrix.msc2762.receive.state_event:m.room.member",
345            "org.matrix.msc2762.receive.state_event:org.matrix.msc3401.call.member",
346            "org.matrix.msc3819.receive.to_device:io.element.call.encryption_keys",
347            "org.matrix.msc2762.send.event:org.matrix.rageshake_request",
348            "org.matrix.msc2762.send.state_event:org.matrix.msc3401.call.member#@user:matrix.server",
349            "org.matrix.msc3819.send.to_device:io.element.call.encryption_keys",
350            "org.matrix.msc4157.send.delayed_event",
351            "org.matrix.msc4157.update_delayed_event",
352            "org.matrix.msc4039.download_file",
353            "org.matrix.msc4515.rtc_transports"
354        ]"#;
355
356        let parsed = serde_json::from_str::<Capabilities>(capabilities_str).unwrap();
357        let expected = Capabilities {
358            read: vec![
359                Filter::MessageLike(MessageLikeEventFilter::WithType(
360                    "org.matrix.rageshake_request".into(),
361                )),
362                Filter::State(StateEventFilter::WithType(StateEventType::RoomMember)),
363                Filter::State(StateEventFilter::WithType("org.matrix.msc3401.call.member".into())),
364                Filter::ToDevice(ToDeviceEventFilter::new(
365                    "io.element.call.encryption_keys".into(),
366                )),
367            ],
368            send: vec![
369                Filter::MessageLike(MessageLikeEventFilter::WithType(
370                    "org.matrix.rageshake_request".into(),
371                )),
372                Filter::State(StateEventFilter::WithTypeAndStateKey(
373                    "org.matrix.msc3401.call.member".into(),
374                    "@user:matrix.server".into(),
375                )),
376                Filter::ToDevice(ToDeviceEventFilter::new(
377                    "io.element.call.encryption_keys".into(),
378                )),
379            ],
380            requires_client: true,
381            update_delayed_event: true,
382            send_delayed_event: true,
383            download_file: true,
384            rtc_transports: true,
385        };
386
387        assert_eq!(parsed, expected);
388    }
389
390    #[test]
391    fn serialization_and_deserialization_are_symmetrical() {
392        let capabilities = Capabilities {
393            read: vec![
394                Filter::MessageLike(MessageLikeEventFilter::WithType("io.element.custom".into())),
395                Filter::State(StateEventFilter::WithType(StateEventType::RoomMember)),
396                Filter::State(StateEventFilter::WithTypeAndStateKey(
397                    "org.matrix.msc3401.call.member".into(),
398                    "@user:matrix.server".into(),
399                )),
400                Filter::ToDevice(ToDeviceEventFilter::new(
401                    "io.element.call.encryption_keys".into(),
402                )),
403            ],
404            send: vec![
405                Filter::MessageLike(MessageLikeEventFilter::WithType("io.element.custom".into())),
406                Filter::State(StateEventFilter::WithTypeAndStateKey(
407                    "org.matrix.msc3401.call.member".into(),
408                    "@user:matrix.server".into(),
409                )),
410                Filter::ToDevice(ToDeviceEventFilter::new("my.org.other.to_device_event".into())),
411            ],
412            requires_client: true,
413            update_delayed_event: false,
414            send_delayed_event: false,
415            download_file: false,
416            rtc_transports: true,
417        };
418
419        let capabilities_str = serde_json::to_string(&capabilities).unwrap();
420        let parsed = serde_json::from_str::<Capabilities>(&capabilities_str).unwrap();
421        assert_eq!(parsed, capabilities);
422    }
423}
matrix_sdk/widget/capabilities.rs

matrix_sdk/widget/
capabilities.rs
