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
62impl Capabilities {
63    /// Checks if a given event is allowed to be forwarded to the widget.
64    ///
65    /// - `event_filter_input` is a minimized event representation that contains
66    ///   only the information needed to check if the widget is allowed to
67    ///   receive the event. (See [`FilterInput`])
68    pub(super) fn allow_reading<'a>(
69        &self,
70        event_filter_input: impl TryInto<FilterInput<'a>>,
71    ) -> bool {
72        match &event_filter_input.try_into() {
73            Err(_) => {
74                warn!("Failed to convert event into filter input for `allow_reading`.");
75                false
76            }
77            Ok(filter_input) => self.read.iter().any(|f| f.matches(filter_input)),
78        }
79    }
80
81    /// Checks if a given event is allowed to be sent by the widget.
82    ///
83    /// - `event_filter_input` is a minimized event representation that contains
84    ///   only the information needed to check if the widget is allowed to send
85    ///   the event to a matrix room. (See [`FilterInput`])
86    pub(super) fn allow_sending<'a>(
87        &self,
88        event_filter_input: impl TryInto<FilterInput<'a>>,
89    ) -> bool {
90        match &event_filter_input.try_into() {
91            Err(_) => {
92                warn!("Failed to convert event into filter input for `allow_sending`.");
93                false
94            }
95            Ok(filter_input) => self.send.iter().any(|f| f.matches(filter_input)),
96        }
97    }
98
99    /// Checks if a filter exists for the given event type, useful for
100    /// optimization. Avoids unnecessary read event requests when no matching
101    /// filter is present.
102    pub(super) fn has_read_filter_for_type(&self, event_type: &str) -> bool {
103        self.read.iter().any(|f| f.filter_event_type() == event_type)
104    }
105}
106
107pub(super) const SEND_EVENT: &str = "org.matrix.msc2762.send.event";
108pub(super) const READ_EVENT: &str = "org.matrix.msc2762.receive.event";
109pub(super) const SEND_STATE: &str = "org.matrix.msc2762.send.state_event";
110pub(super) const READ_STATE: &str = "org.matrix.msc2762.receive.state_event";
111pub(super) const SEND_TODEVICE: &str = "org.matrix.msc3819.send.to_device";
112pub(super) const READ_TODEVICE: &str = "org.matrix.msc3819.receive.to_device";
113pub(super) const REQUIRES_CLIENT: &str = "io.element.requires_client";
114pub(super) const SEND_DELAYED_EVENT: &str = "org.matrix.msc4157.send.delayed_event";
115pub(super) const UPDATE_DELAYED_EVENT: &str = "org.matrix.msc4157.update_delayed_event";
116
117impl Serialize for Capabilities {
118    fn serialize<S>(&self, serializer: S) -> Result<S::Ok, S::Error>
119    where
120        S: Serializer,
121    {
122        struct PrintEventFilter<'a>(&'a Filter);
123        impl fmt::Display for PrintEventFilter<'_> {
124            fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
125                match self.0 {
126                    Filter::MessageLike(filter) => PrintMessageLikeEventFilter(filter).fmt(f),
127                    Filter::State(filter) => PrintStateEventFilter(filter).fmt(f),
128                    Filter::ToDevice(filter) => {
129                        // As per MSC 3819 https://github.com/matrix-org/matrix-spec-proposals/pull/3819
130                        // ToDevice capabilities is in the form of `m.send.to_device:<event type>`
131                        // or `m.receive.to_device:<event type>`
132                        write!(f, "{}", filter.event_type)
133                    }
134                }
135            }
136        }
137
138        struct PrintMessageLikeEventFilter<'a>(&'a MessageLikeEventFilter);
139        impl fmt::Display for PrintMessageLikeEventFilter<'_> {
140            fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
141                match self.0 {
142                    MessageLikeEventFilter::WithType(event_type) => {
143                        // TODO: escape `#` as `\#` and `\` as `\\` in event_type
144                        write!(f, "{event_type}")
145                    }
146                    MessageLikeEventFilter::RoomMessageWithMsgtype(msgtype) => {
147                        write!(f, "m.room.message#{msgtype}")
148                    }
149                }
150            }
151        }
152
153        struct PrintStateEventFilter<'a>(&'a StateEventFilter);
154        impl fmt::Display for PrintStateEventFilter<'_> {
155            fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
156                // TODO: escape `#` as `\#` and `\` as `\\` in event_type
157                match self.0 {
158                    StateEventFilter::WithType(event_type) => write!(f, "{event_type}"),
159                    StateEventFilter::WithTypeAndStateKey(event_type, state_key) => {
160                        write!(f, "{event_type}#{state_key}")
161                    }
162                }
163            }
164        }
165
166        let mut seq = serializer.serialize_seq(None)?;
167
168        if self.requires_client {
169            seq.serialize_element(REQUIRES_CLIENT)?;
170        }
171        if self.update_delayed_event {
172            seq.serialize_element(UPDATE_DELAYED_EVENT)?;
173        }
174        if self.send_delayed_event {
175            seq.serialize_element(SEND_DELAYED_EVENT)?;
176        }
177        for filter in &self.read {
178            let name = match filter {
179                Filter::MessageLike(_) => READ_EVENT,
180                Filter::State(_) => READ_STATE,
181                Filter::ToDevice(_) => READ_TODEVICE,
182            };
183            seq.serialize_element(&format!("{name}:{}", PrintEventFilter(filter)))?;
184        }
185        for filter in &self.send {
186            let name = match filter {
187                Filter::MessageLike(_) => SEND_EVENT,
188                Filter::State(_) => SEND_STATE,
189                Filter::ToDevice(_) => SEND_TODEVICE,
190            };
191            seq.serialize_element(&format!("{name}:{}", PrintEventFilter(filter)))?;
192        }
193
194        seq.end()
195    }
196}
197
198impl<'de> Deserialize<'de> for Capabilities {
199    fn deserialize<D>(deserializer: D) -> Result<Self, D::Error>
200    where
201        D: Deserializer<'de>,
202    {
203        enum Permission {
204            RequiresClient,
205            UpdateDelayedEvent,
206            SendDelayedEvent,
207            Read(Filter),
208            Send(Filter),
209            Unknown,
210        }
211
212        impl<'de> Deserialize<'de> for Permission {
213            fn deserialize<D>(deserializer: D) -> Result<Self, D::Error>
214            where
215                D: Deserializer<'de>,
216            {
217                let s = ruma::serde::deserialize_cow_str(deserializer)?;
218                if s == REQUIRES_CLIENT {
219                    return Ok(Self::RequiresClient);
220                }
221                if s == UPDATE_DELAYED_EVENT {
222                    return Ok(Self::UpdateDelayedEvent);
223                }
224                if s == SEND_DELAYED_EVENT {
225                    return Ok(Self::SendDelayedEvent);
226                }
227
228                match s.split_once(':') {
229                    Some((READ_EVENT, filter_s)) => Ok(Permission::Read(Filter::MessageLike(
230                        parse_message_event_filter(filter_s),
231                    ))),
232                    Some((SEND_EVENT, filter_s)) => Ok(Permission::Send(Filter::MessageLike(
233                        parse_message_event_filter(filter_s),
234                    ))),
235                    Some((READ_STATE, filter_s)) => {
236                        Ok(Permission::Read(Filter::State(parse_state_event_filter(filter_s))))
237                    }
238                    Some((SEND_STATE, filter_s)) => {
239                        Ok(Permission::Send(Filter::State(parse_state_event_filter(filter_s))))
240                    }
241                    Some((READ_TODEVICE, filter_s)) => Ok(Permission::Read(Filter::ToDevice(
242                        parse_to_device_event_filter(filter_s),
243                    ))),
244                    Some((SEND_TODEVICE, filter_s)) => Ok(Permission::Send(Filter::ToDevice(
245                        parse_to_device_event_filter(filter_s),
246                    ))),
247                    _ => {
248                        debug!("Unknown capability `{s}`");
249                        Ok(Self::Unknown)
250                    }
251                }
252            }
253        }
254
255        fn parse_message_event_filter(s: &str) -> MessageLikeEventFilter {
256            match s.strip_prefix("m.room.message#") {
257                Some(msgtype) => MessageLikeEventFilter::RoomMessageWithMsgtype(msgtype.to_owned()),
258                // TODO: Replace `\\` by `\` and `\#` by `#`, enforce no unescaped `#`
259                None => MessageLikeEventFilter::WithType(s.into()),
260            }
261        }
262
263        fn parse_state_event_filter(s: &str) -> StateEventFilter {
264            // TODO: Search for un-escaped `#` only, replace `\\` by `\` and `\#` by `#`
265            match s.split_once('#') {
266                Some((event_type, state_key)) => {
267                    StateEventFilter::WithTypeAndStateKey(event_type.into(), state_key.to_owned())
268                }
269                None => StateEventFilter::WithType(s.into()),
270            }
271        }
272
273        fn parse_to_device_event_filter(s: &str) -> ToDeviceEventFilter {
274            ToDeviceEventFilter::new(s.into())
275        }
276
277        let mut capabilities = Capabilities::default();
278        for capability in Vec::<Permission>::deserialize(deserializer)? {
279            match capability {
280                Permission::RequiresClient => capabilities.requires_client = true,
281                Permission::Read(filter) => capabilities.read.push(filter),
282                Permission::Send(filter) => capabilities.send.push(filter),
283                // ignore unknown capabilities
284                Permission::Unknown => {}
285                Permission::UpdateDelayedEvent => capabilities.update_delayed_event = true,
286                Permission::SendDelayedEvent => capabilities.send_delayed_event = true,
287            }
288        }
289
290        Ok(capabilities)
291    }
292}
293
294#[cfg(test)]
295mod tests {
296    use ruma::events::StateEventType;
297
298    use super::*;
299    use crate::widget::filter::ToDeviceEventFilter;
300
301    #[test]
302    fn deserialization_of_no_capabilities() {
303        let capabilities_str = r#"[]"#;
304
305        let parsed = serde_json::from_str::<Capabilities>(capabilities_str).unwrap();
306        let expected = Capabilities::default();
307
308        assert_eq!(parsed, expected);
309    }
310
311    #[test]
312    fn deserialization_of_capabilities() {
313        let capabilities_str = r#"[
314            "m.always_on_screen",
315            "io.element.requires_client",
316            "org.matrix.msc2762.receive.event:org.matrix.rageshake_request",
317            "org.matrix.msc2762.receive.state_event:m.room.member",
318            "org.matrix.msc2762.receive.state_event:org.matrix.msc3401.call.member",
319            "org.matrix.msc3819.receive.to_device:io.element.call.encryption_keys",
320            "org.matrix.msc2762.send.event:org.matrix.rageshake_request",
321            "org.matrix.msc2762.send.state_event:org.matrix.msc3401.call.member#@user:matrix.server",
322            "org.matrix.msc3819.send.to_device:io.element.call.encryption_keys",
323            "org.matrix.msc4157.send.delayed_event",
324            "org.matrix.msc4157.update_delayed_event"
325        ]"#;
326
327        let parsed = serde_json::from_str::<Capabilities>(capabilities_str).unwrap();
328        let expected = Capabilities {
329            read: vec![
330                Filter::MessageLike(MessageLikeEventFilter::WithType(
331                    "org.matrix.rageshake_request".into(),
332                )),
333                Filter::State(StateEventFilter::WithType(StateEventType::RoomMember)),
334                Filter::State(StateEventFilter::WithType("org.matrix.msc3401.call.member".into())),
335                Filter::ToDevice(ToDeviceEventFilter::new(
336                    "io.element.call.encryption_keys".into(),
337                )),
338            ],
339            send: vec![
340                Filter::MessageLike(MessageLikeEventFilter::WithType(
341                    "org.matrix.rageshake_request".into(),
342                )),
343                Filter::State(StateEventFilter::WithTypeAndStateKey(
344                    "org.matrix.msc3401.call.member".into(),
345                    "@user:matrix.server".into(),
346                )),
347                Filter::ToDevice(ToDeviceEventFilter::new(
348                    "io.element.call.encryption_keys".into(),
349                )),
350            ],
351            requires_client: true,
352            update_delayed_event: true,
353            send_delayed_event: true,
354        };
355
356        assert_eq!(parsed, expected);
357    }
358
359    #[test]
360    fn serialization_and_deserialization_are_symmetrical() {
361        let capabilities = Capabilities {
362            read: vec![
363                Filter::MessageLike(MessageLikeEventFilter::WithType("io.element.custom".into())),
364                Filter::State(StateEventFilter::WithType(StateEventType::RoomMember)),
365                Filter::State(StateEventFilter::WithTypeAndStateKey(
366                    "org.matrix.msc3401.call.member".into(),
367                    "@user:matrix.server".into(),
368                )),
369                Filter::ToDevice(ToDeviceEventFilter::new(
370                    "io.element.call.encryption_keys".into(),
371                )),
372            ],
373            send: vec![
374                Filter::MessageLike(MessageLikeEventFilter::WithType("io.element.custom".into())),
375                Filter::State(StateEventFilter::WithTypeAndStateKey(
376                    "org.matrix.msc3401.call.member".into(),
377                    "@user:matrix.server".into(),
378                )),
379                Filter::ToDevice(ToDeviceEventFilter::new("my.org.other.to_device_event".into())),
380            ],
381            requires_client: true,
382            update_delayed_event: false,
383            send_delayed_event: false,
384        };
385
386        let capabilities_str = serde_json::to_string(&capabilities).unwrap();
387        let parsed = serde_json::from_str::<Capabilities>(&capabilities_str).unwrap();
388        assert_eq!(parsed, capabilities);
389    }
390}
matrix_sdk/widget/capabilities.rs

matrix_sdk/widget/
capabilities.rs
