script/dom/globalscope/
messageport.rs

1/* This Source Code Form is subject to the terms of the Mozilla Public
2 * License, v. 2.0. If a copy of the MPL was not distributed with this
3 * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
4
5use std::cell::{Cell, RefCell};
6use std::ptr;
7use std::rc::Rc;
8
9use dom_struct::dom_struct;
10use js::context::JSContext;
11use js::conversions::ToJSValConvertible;
12use js::jsapi::{Heap, JSObject};
13use js::jsval::UndefinedValue;
14use js::rust::wrappers2::JS_NewObject;
15use js::rust::{CustomAutoRooter, CustomAutoRooterGuard, HandleValue};
16use rustc_hash::FxHashMap;
17use script_bindings::reflector::reflect_weak_referenceable_dom_object;
18use servo_base::id::{MessagePortId, MessagePortIndex};
19use servo_constellation_traits::{MessagePortImpl, PortMessageTask};
20
21use crate::dom::bindings::codegen::Bindings::EventHandlerBinding::EventHandlerNonNull;
22use crate::dom::bindings::codegen::Bindings::MessagePortBinding::{
23    MessagePortMethods, StructuredSerializeOptions,
24};
25use crate::dom::bindings::conversions::root_from_object;
26use crate::dom::bindings::error::{Error, ErrorResult, ErrorToJsval, Fallible};
27use crate::dom::bindings::inheritance::Castable;
28use crate::dom::bindings::reflector::DomGlobal;
29use crate::dom::bindings::root::DomRoot;
30use crate::dom::bindings::structuredclone::{self, StructuredData};
31use crate::dom::bindings::trace::RootedTraceableBox;
32use crate::dom::bindings::transferable::Transferable;
33use crate::dom::bindings::utils::set_dictionary_property;
34use crate::dom::eventtarget::EventTarget;
35use crate::dom::globalscope::GlobalScope;
36
37#[dom_struct]
38/// The MessagePort used in the DOM.
39pub(crate) struct MessagePort {
40    eventtarget: EventTarget,
41    #[no_trace]
42    message_port_id: MessagePortId,
43    #[no_trace]
44    entangled_port: RefCell<Option<MessagePortId>>,
45    detached: Cell<bool>,
46}
47
48impl MessagePort {
49    fn new_inherited(message_port_id: MessagePortId) -> MessagePort {
50        MessagePort {
51            eventtarget: EventTarget::new_inherited(),
52            entangled_port: RefCell::new(None),
53            detached: Cell::new(false),
54            message_port_id,
55        }
56    }
57
58    /// <https://html.spec.whatwg.org/multipage/#create-a-new-messageport-object>
59    pub(crate) fn new(cx: &mut JSContext, owner: &GlobalScope) -> DomRoot<MessagePort> {
60        let port_id = MessagePortId::new();
61        reflect_weak_referenceable_dom_object(
62            cx,
63            Rc::new(MessagePort::new_inherited(port_id)),
64            owner,
65        )
66    }
67
68    /// Create a new port for an incoming transfer-received one.
69    pub(crate) fn new_transferred(
70        cx: &mut JSContext,
71        owner: &GlobalScope,
72        transferred_port: MessagePortId,
73        entangled_port: Option<MessagePortId>,
74    ) -> DomRoot<MessagePort> {
75        reflect_weak_referenceable_dom_object(
76            cx,
77            Rc::new(MessagePort {
78                message_port_id: transferred_port,
79                eventtarget: EventTarget::new_inherited(),
80                detached: Cell::new(false),
81                entangled_port: RefCell::new(entangled_port),
82            }),
83            owner,
84        )
85    }
86
87    /// <https://html.spec.whatwg.org/multipage/#entangle>
88    pub(crate) fn entangle(&self, other_id: MessagePortId) {
89        *self.entangled_port.borrow_mut() = Some(other_id);
90    }
91
92    /// <https://html.spec.whatwg.org/multipage/#disentangle>
93    pub(crate) fn disentangle(&self) -> Option<MessagePortId> {
94        // Disentangle initiatorPort and otherPort, so that they are no longer entangled or associated with each other.
95        // Note: called from `disentangle_port` in the global, where the rest happens.
96        self.entangled_port.borrow_mut().take()
97    }
98
99    /// Has the port been disentangled?
100    /// Used when starting the port to fire the `close` event,
101    /// to cover the case of a disentanglement while in transfer.
102    pub(crate) fn disentangled(&self) -> bool {
103        self.entangled_port.borrow().is_none()
104    }
105
106    pub(crate) fn message_port_id(&self) -> &MessagePortId {
107        &self.message_port_id
108    }
109
110    /// <https://html.spec.whatwg.org/multipage/#handler-messageport-onmessage>
111    fn set_onmessage(&self, cx: &mut JSContext, listener: Option<Rc<EventHandlerNonNull>>) {
112        let eventtarget = self.upcast::<EventTarget>();
113        eventtarget.set_event_handler_common(cx, "message", listener);
114    }
115
116    /// <https://html.spec.whatwg.org/multipage/#message-port-post-message-steps>
117    #[expect(unsafe_code)]
118    fn post_message_impl(
119        &self,
120        cx: &mut JSContext,
121        message: HandleValue,
122        transfer: CustomAutoRooterGuard<Vec<*mut JSObject>>,
123    ) -> ErrorResult {
124        if self.detached.get() {
125            return Ok(());
126        }
127
128        // Step 1 is the transfer argument.
129
130        let target_port = self.entangled_port.borrow();
131
132        // Step 3
133        let mut doomed = false;
134
135        let ports = transfer
136            .iter()
137            .filter_map(|&obj| unsafe { root_from_object::<MessagePort>(cx, obj).ok() });
138        for port in ports {
139            // Step 2
140            if port.message_port_id() == self.message_port_id() {
141                return Err(Error::DataClone(None));
142            }
143
144            // Step 4
145            if let Some(target_id) = target_port.as_ref() &&
146                port.message_port_id() == target_id
147            {
148                doomed = true;
149            }
150        }
151
152        // Step 5
153        let data = structuredclone::write(cx, message, Some(transfer))?;
154
155        if doomed {
156            // TODO: The spec says to optionally report such a case to a dev console.
157            return Ok(());
158        }
159
160        // Step 6, done in MessagePortImpl.
161
162        let incumbent = match GlobalScope::incumbent() {
163            None => unreachable!("postMessage called with no incumbent global"),
164            Some(incumbent) => incumbent,
165        };
166
167        // Step 7
168        let task = PortMessageTask {
169            origin: incumbent.origin().immutable().clone(),
170            data,
171        };
172
173        // Have the global proxy this call to the corresponding MessagePortImpl.
174        self.global()
175            .post_messageport_msg(*self.message_port_id(), task);
176        Ok(())
177    }
178
179    /// <https://streams.spec.whatwg.org/#abstract-opdef-crossrealmtransformsenderror>
180    pub(crate) fn cross_realm_transform_send_error(&self, cx: &mut JSContext, error: HandleValue) {
181        // Perform PackAndPostMessage(port, "error", error),
182        // discarding the result.
183        let _ = self.pack_and_post_message(cx, "error", error);
184    }
185
186    /// <https://streams.spec.whatwg.org/#abstract-opdef-packandpostmessagehandlingerror>
187    pub(crate) fn pack_and_post_message_handling_error(
188        &self,
189        cx: &mut JSContext,
190        type_: &str,
191        value: HandleValue,
192    ) -> ErrorResult {
193        // Let result be PackAndPostMessage(port, type, value).
194        let result = self.pack_and_post_message(cx, type_, value);
195
196        // If result is an abrupt completion,
197        if let Err(error) = result.as_ref() {
198            // Perform ! CrossRealmTransformSendError(port, result.[[Value]]).
199            rooted!(&in(cx) let mut rooted_error = UndefinedValue());
200            error
201                .clone()
202                .to_jsval(cx, &self.global(), rooted_error.handle_mut());
203            self.cross_realm_transform_send_error(cx, rooted_error.handle());
204        }
205
206        result
207    }
208
209    /// <https://streams.spec.whatwg.org/#abstract-opdef-packandpostmessage>
210    #[expect(unsafe_code)]
211    pub(crate) fn pack_and_post_message(
212        &self,
213        cx: &mut JSContext,
214        type_: &str,
215        value: HandleValue,
216    ) -> ErrorResult {
217        // Let message be OrdinaryObjectCreate(null).
218        rooted!(&in(cx) let mut message = unsafe { JS_NewObject(cx, ptr::null()) });
219        rooted!(&in(cx) let mut type_string = UndefinedValue());
220        type_.safe_to_jsval(cx, type_string.handle_mut());
221
222        // Perform ! CreateDataProperty(message, "type", type).
223        set_dictionary_property(cx, message.handle(), c"type", type_string.handle())
224            .expect("Setting the message type should not fail.");
225
226        // Perform ! CreateDataProperty(message, "value", value).
227        set_dictionary_property(cx, message.handle(), c"value", value)
228            .expect("Setting the message value should not fail.");
229
230        // Let targetPort be the port with which port is entangled, if any; otherwise let it be null.
231        // Done in `global.post_messageport_msg`.
232
233        // Let options be «[ "transfer" → « » ]».
234        let mut rooted = CustomAutoRooter::new(vec![]);
235        let transfer = unsafe { CustomAutoRooterGuard::new(cx.raw_cx(), &mut rooted) };
236
237        // Run the message port post message steps providing targetPort, message, and options.
238        rooted!(&in(cx) let mut message_val = UndefinedValue());
239        message.safe_to_jsval(cx, message_val.handle_mut());
240        self.post_message_impl(cx, message_val.handle(), transfer)
241    }
242}
243
244impl Transferable for MessagePort {
245    type Index = MessagePortIndex;
246    type Data = MessagePortImpl;
247
248    /// <https://html.spec.whatwg.org/multipage/#message-ports:transfer-steps>
249    fn transfer(
250        &self,
251        _cx: &mut js::context::JSContext,
252    ) -> Fallible<(MessagePortId, MessagePortImpl)> {
253        // <https://html.spec.whatwg.org/multipage/#structuredserializewithtransfer>
254        // Step 5.2. If transferable has a [[Detached]] internal slot and
255        // transferable.[[Detached]] is true, then throw a "DataCloneError"
256        // DOMException.
257        if self.detached.get() {
258            return Err(Error::DataClone(None));
259        }
260
261        self.detached.set(true);
262        let id = self.message_port_id();
263
264        // 1. Run local transfer logic, and return the object to be transferred.
265        let transferred_port = self.global().mark_port_as_transferred(id);
266
267        Ok((*id, transferred_port))
268    }
269
270    /// <https://html.spec.whatwg.org/multipage/#message-ports:transfer-receiving-steps>
271    fn transfer_receive(
272        cx: &mut js::context::JSContext,
273        owner: &GlobalScope,
274        id: MessagePortId,
275        port_impl: MessagePortImpl,
276    ) -> Result<DomRoot<Self>, ()> {
277        let transferred_port =
278            MessagePort::new_transferred(cx, owner, id, port_impl.entangled_port_id());
279        owner.track_message_port(&transferred_port, Some(port_impl));
280        Ok(transferred_port)
281    }
282
283    fn serialized_storage<'a>(
284        data: StructuredData<'a, '_>,
285    ) -> &'a mut Option<FxHashMap<MessagePortId, Self::Data>> {
286        match data {
287            StructuredData::Reader(r) => &mut r.port_impls,
288            StructuredData::Writer(w) => &mut w.ports,
289        }
290    }
291}
292
293impl MessagePortMethods<crate::DomTypeHolder> for MessagePort {
294    /// <https://html.spec.whatwg.org/multipage/#dom-messageport-postmessage>
295    fn PostMessage(
296        &self,
297        cx: &mut JSContext,
298        message: HandleValue,
299        transfer: CustomAutoRooterGuard<Vec<*mut JSObject>>,
300    ) -> ErrorResult {
301        if self.detached.get() {
302            return Ok(());
303        }
304        self.post_message_impl(cx, message, transfer)
305    }
306
307    /// <https://html.spec.whatwg.org/multipage/#dom-messageport-postmessage>
308    fn PostMessage_(
309        &self,
310        cx: &mut JSContext,
311        message: HandleValue,
312        options: RootedTraceableBox<StructuredSerializeOptions>,
313    ) -> ErrorResult {
314        if self.detached.get() {
315            return Ok(());
316        }
317        let mut rooted = CustomAutoRooter::new(
318            options
319                .transfer
320                .iter()
321                .map(|js: &RootedTraceableBox<Heap<*mut JSObject>>| js.get())
322                .collect(),
323        );
324        #[expect(unsafe_code)]
325        let guard = unsafe { CustomAutoRooterGuard::new(cx.raw_cx(), &mut rooted) };
326        self.post_message_impl(cx, message, guard)
327    }
328
329    /// <https://html.spec.whatwg.org/multipage/#dom-messageport-start>
330    fn Start(&self, cx: &mut JSContext) {
331        if self.detached.get() {
332            return;
333        }
334        self.global().start_message_port(cx, self.message_port_id());
335    }
336
337    /// <https://html.spec.whatwg.org/multipage/#dom-messageport-close>
338    fn Close(&self, cx: &mut JSContext) {
339        // Set this's [[Detached]] internal slot value to true.
340        self.detached.set(true);
341
342        let global = self.global();
343        global.close_message_port(self.message_port_id());
344
345        // If this is entangled, disentangle it.
346        global.disentangle_port(cx, self);
347    }
348
349    /// <https://html.spec.whatwg.org/multipage/#handler-messageport-onmessage>
350    fn GetOnmessage(&self, cx: &mut JSContext) -> Option<Rc<EventHandlerNonNull>> {
351        if self.detached.get() {
352            return None;
353        }
354        let eventtarget = self.upcast::<EventTarget>();
355        eventtarget.get_event_handler_common(cx, "message")
356    }
357
358    /// <https://html.spec.whatwg.org/multipage/#handler-messageport-onmessage>
359    fn SetOnmessage(&self, cx: &mut JSContext, listener: Option<Rc<EventHandlerNonNull>>) {
360        if self.detached.get() {
361            return;
362        }
363        self.set_onmessage(cx, listener);
364        // Note: we cannot use the event_handler macro, due to the need to start the port.
365        self.global().start_message_port(cx, self.message_port_id());
366    }
367
368    // <https://html.spec.whatwg.org/multipage/#handler-messageport-onmessageerror>
369    event_handler!(messageerror, GetOnmessageerror, SetOnmessageerror);
370
371    // <https://html.spec.whatwg.org/multipage/#handler-messageport-onclose>
372    event_handler!(close, GetOnclose, SetOnclose);
373}
script/dom/globalscope/messageport.rs

script/dom/globalscope/
messageport.rs
