script/dom/event/

eventsource.rs

/* This Source Code Form is subject to the terms of the Mozilla Public
 * License, v. 2.0. If a copy of the MPL was not distributed with this
 * file, You can obtain one at https://mozilla.org/MPL/2.0/. */

use std::cell::Cell;
use std::mem;
use std::str::{Chars, FromStr};
use std::time::Duration;

use dom_struct::dom_struct;
use encoding_rs::{Decoder, UTF_8};
use headers::ContentType;
use http::StatusCode;
use http::header::{self, HeaderName, HeaderValue};
use js::jsval::UndefinedValue;
use js::rust::HandleObject;
use mime::{self, Mime};
use net_traits::request::{CacheMode, CorsSettings, Destination, RequestBuilder, RequestId};
use net_traits::{FetchMetadata, FilteredMetadata, NetworkError, ResourceFetchTiming};
use script_bindings::conversions::SafeToJSValConvertible;
use servo_url::ServoUrl;
use stylo_atoms::Atom;

use crate::dom::bindings::cell::DomRefCell;
use crate::dom::bindings::codegen::Bindings::EventSourceBinding::{
    EventSourceInit, EventSourceMethods,
};
use crate::dom::bindings::error::{Error, Fallible};
use crate::dom::bindings::inheritance::Castable;
use crate::dom::bindings::refcounted::Trusted;
use crate::dom::bindings::reflector::{DomGlobal, reflect_dom_object_with_proto};
use crate::dom::bindings::root::DomRoot;
use crate::dom::bindings::str::DOMString;
use crate::dom::csp::{GlobalCspReporting, Violation};
use crate::dom::event::Event;
use crate::dom::eventtarget::EventTarget;
use crate::dom::globalscope::GlobalScope;
use crate::dom::messageevent::MessageEvent;
use crate::dom::performance::performanceresourcetiming::InitiatorType;
use crate::fetch::{FetchCanceller, RequestWithGlobalScope, create_a_potential_cors_request};
use crate::network_listener::{self, FetchResponseListener, ResourceTimingListener};
use crate::realms::enter_realm;
use crate::script_runtime::CanGc;
use crate::timers::OneshotTimerCallback;

const DEFAULT_RECONNECTION_TIME: Duration = Duration::from_millis(5000);

#[derive(Clone, Copy, Debug, JSTraceable, MallocSizeOf, PartialEq)]
struct GenerationId(u32);

#[derive(Clone, Copy, Debug, JSTraceable, MallocSizeOf, PartialEq)]
/// <https://html.spec.whatwg.org/multipage/#dom-eventsource-readystate>
enum ReadyState {
    Connecting = 0,
    Open = 1,
    Closed = 2,
}

#[derive(JSTraceable, MallocSizeOf)]
struct DroppableEventSource {
    canceller: DomRefCell<FetchCanceller>,
}

impl DroppableEventSource {
    pub(crate) fn new(canceller: DomRefCell<FetchCanceller>) -> Self {
        DroppableEventSource { canceller }
    }

    pub(crate) fn cancel(&self) {
        self.canceller.borrow_mut().abort();
    }

    pub(crate) fn set_canceller(&self, data: FetchCanceller) {
        *self.canceller.borrow_mut() = data;
    }
}

// https://html.spec.whatwg.org/multipage/#garbage-collection-2
impl Drop for DroppableEventSource {
    fn drop(&mut self) {
        // If an EventSource object is garbage collected while its connection is still open,
        // the user agent must abort any instance of the fetch algorithm opened by this EventSource.
        self.cancel();
    }
}

#[dom_struct]
pub(crate) struct EventSource {
    eventtarget: EventTarget,
    #[no_trace]
    url: ServoUrl,
    #[no_trace]
    request: DomRefCell<Option<RequestBuilder>>,
    last_event_id: DomRefCell<DOMString>,
    reconnection_time: Cell<Duration>,
    generation_id: Cell<GenerationId>,

    ready_state: Cell<ReadyState>,
    with_credentials: bool,
    droppable: DroppableEventSource,
}

#[derive(Clone, MallocSizeOf)]
enum ParserState {
    Field,
    Comment,
    Value,
    Eol,
}

#[derive(MallocSizeOf)]
struct EventSourceContext {
    decoder: Decoder,
    event_source: Trusted<EventSource>,
    gen_id: GenerationId,
    parser_state: ParserState,
    field: String,
    value: String,
    origin: String,
    event_type: String,
    data: String,
    last_event_id: String,
}

impl Clone for EventSourceContext {
    fn clone(&self) -> Self {
        EventSourceContext {
            decoder: UTF_8.new_decoder_with_bom_removal(),
            event_source: self.event_source.clone(),
            gen_id: self.gen_id,
            parser_state: self.parser_state.clone(),
            field: self.field.clone(),
            value: self.value.clone(),
            origin: self.origin.clone(),
            event_type: self.event_type.clone(),
            data: self.data.clone(),
            last_event_id: self.last_event_id.clone(),
        }
    }
}

impl EventSourceContext {
    /// <https://html.spec.whatwg.org/multipage/#announce-the-connection>
    fn announce_the_connection(&self) {
        let event_source = self.event_source.root();
        if self.gen_id != event_source.generation_id.get() {
            return;
        }
        let global = event_source.global();
        let event_source = self.event_source.clone();
        global.task_manager().remote_event_task_source().queue(
            task!(announce_the_event_source_connection: move || {
                let event_source = event_source.root();
                if event_source.ready_state.get() != ReadyState::Closed {
                    event_source.ready_state.set(ReadyState::Open);
                    event_source.upcast::<EventTarget>().fire_event(atom!("open"), CanGc::note());
                }
            }),
        );
    }

    /// <https://html.spec.whatwg.org/multipage/#fail-the-connection>
    fn fail_the_connection(&self) {
        let event_source = self.event_source.root();
        if self.gen_id != event_source.generation_id.get() {
            return;
        }
        event_source.fail_the_connection();
    }

    /// <https://html.spec.whatwg.org/multipage/#reestablish-the-connection>
    fn reestablish_the_connection(&self) {
        let event_source = self.event_source.root();

        if self.gen_id != event_source.generation_id.get() {
            return;
        }

        let trusted_event_source = self.event_source.clone();
        let global = event_source.global();
        let event_source_context = EventSourceContext {
            decoder: UTF_8.new_decoder_with_bom_removal(),
            event_source: self.event_source.clone(),
            gen_id: self.gen_id,
            parser_state: ParserState::Eol,
            field: String::new(),
            value: String::new(),
            origin: self.origin.clone(),
            event_type: String::new(),
            data: String::new(),
            last_event_id: String::from(event_source.last_event_id.borrow().clone()),
        };
        global.task_manager().remote_event_task_source().queue(
            task!(reestablish_the_event_source_onnection: move || {
                let event_source = trusted_event_source.root();

                // Step 1.1.
                if event_source.ready_state.get() == ReadyState::Closed {
                    return;
                }

                // Step 1.2.
                event_source.ready_state.set(ReadyState::Connecting);

                // Step 1.3.
                event_source.upcast::<EventTarget>().fire_event(atom!("error"), CanGc::note());

                // Step 2.
                let duration = event_source.reconnection_time.get();

                // Step 3.
                // TODO: Optionally wait some more.

                // Steps 4-5.
                let callback = OneshotTimerCallback::EventSourceTimeout(
                    EventSourceTimeoutCallback {
                        event_source: trusted_event_source,
                        event_source_context,
                    }
                );
                event_source.global().schedule_callback(callback, duration);
            }),
        );
    }

    /// <https://html.spec.whatwg.org/multipage/#processField>
    fn process_field(&mut self) {
        match &*self.field {
            "event" => mem::swap(&mut self.event_type, &mut self.value),
            "data" => {
                self.data.push_str(&self.value);
                self.data.push('\n');
            },
            "id" if !self.value.contains('\0') => {
                mem::swap(&mut self.last_event_id, &mut self.value);
            },
            "retry" => {
                if let Ok(time) = u64::from_str(&self.value) {
                    self.event_source
                        .root()
                        .reconnection_time
                        .set(Duration::from_millis(time));
                }
            },
            _ => (),
        }

        self.field.clear();
        self.value.clear();
    }

    /// <https://html.spec.whatwg.org/multipage/#dispatchMessage>
    fn dispatch_event(&mut self, cx: &mut js::context::JSContext) {
        let event_source = self.event_source.root();
        // Step 1
        *event_source.last_event_id.borrow_mut() = DOMString::from(self.last_event_id.clone());
        // Step 2
        if self.data.is_empty() {
            self.data.clear();
            self.event_type.clear();
            return;
        }
        // Step 3
        if let Some(last) = self.data.pop() {
            if last != '\n' {
                self.data.push(last);
            }
        }
        // Step 6
        let type_ = if !self.event_type.is_empty() {
            Atom::from(self.event_type.clone())
        } else {
            atom!("message")
        };
        // Steps 4-5
        let event = {
            let _ac = enter_realm(&*event_source);
            rooted!(&in(cx) let mut data = UndefinedValue());
            self.data
                .safe_to_jsval(cx.into(), data.handle_mut(), CanGc::from_cx(cx));
            MessageEvent::new(
                &event_source.global(),
                type_,
                false,
                false,
                data.handle(),
                DOMString::from(self.origin.clone()),
                None,
                event_source.last_event_id.borrow().clone(),
                Vec::with_capacity(0),
                CanGc::from_cx(cx),
            )
        };
        // Step 7
        self.event_type.clear();
        self.data.clear();

        // Step 8.
        let global = event_source.global();
        let event_source = self.event_source.clone();
        let event = Trusted::new(&*event);
        global.task_manager().remote_event_task_source().queue(
            task!(dispatch_the_event_source_event: move |cx| {
                let event_source = event_source.root();
                if event_source.ready_state.get() != ReadyState::Closed {
                    event.root().upcast::<Event>().fire(event_source.upcast(), CanGc::from_cx(cx));
                }
            }),
        );
    }

    /// <https://html.spec.whatwg.org/multipage/#event-stream-interpretation>
    fn parse(&mut self, cx: &mut js::context::JSContext, stream: Chars) {
        let mut stream = stream.peekable();

        while let Some(ch) = stream.next() {
            match (ch, &self.parser_state) {
                (':', &ParserState::Eol) => self.parser_state = ParserState::Comment,
                (':', &ParserState::Field) => {
                    self.parser_state = ParserState::Value;
                    if let Some(&' ') = stream.peek() {
                        stream.next();
                    }
                },

                ('\n', &ParserState::Value) => {
                    self.parser_state = ParserState::Eol;
                    self.process_field();
                },
                ('\r', &ParserState::Value) => {
                    if let Some(&'\n') = stream.peek() {
                        continue;
                    }
                    self.parser_state = ParserState::Eol;
                    self.process_field();
                },

                ('\n', &ParserState::Field) => {
                    self.parser_state = ParserState::Eol;
                    self.process_field();
                },
                ('\r', &ParserState::Field) => {
                    if let Some(&'\n') = stream.peek() {
                        continue;
                    }
                    self.parser_state = ParserState::Eol;
                    self.process_field();
                },

                ('\n', &ParserState::Eol) => self.dispatch_event(cx),
                ('\r', &ParserState::Eol) => {
                    if let Some(&'\n') = stream.peek() {
                        continue;
                    }
                    self.dispatch_event(cx);
                },

                ('\n', &ParserState::Comment) => self.parser_state = ParserState::Eol,
                ('\r', &ParserState::Comment) => {
                    if let Some(&'\n') = stream.peek() {
                        continue;
                    }
                    self.parser_state = ParserState::Eol;
                },

                (_, &ParserState::Field) => self.field.push(ch),
                (_, &ParserState::Value) => self.value.push(ch),
                (_, &ParserState::Eol) => {
                    self.parser_state = ParserState::Field;
                    self.field.push(ch);
                },
                (_, &ParserState::Comment) => (),
            }
        }
    }
}

impl FetchResponseListener for EventSourceContext {
    fn should_invoke(&self) -> bool {
        self.event_source.root().generation_id.get() == self.gen_id
    }

    fn process_request_body(&mut self, _: RequestId) {
        // TODO
    }

    fn process_response(
        &mut self,
        _: &mut js::context::JSContext,
        _: RequestId,
        metadata: Result<FetchMetadata, NetworkError>,
    ) {
        match metadata {
            Ok(fm) => {
                let meta = match fm {
                    FetchMetadata::Unfiltered(m) => m,
                    FetchMetadata::Filtered { unsafe_, filtered } => match filtered {
                        FilteredMetadata::Opaque | FilteredMetadata::OpaqueRedirect(_) => {
                            return self.fail_the_connection();
                        },
                        _ => unsafe_,
                    },
                };
                // Step 15.3 if res's status is not 200, or if res's `Content-Type` is not
                // `text/event-stream`, then fail the connection.
                if meta.status.code() != StatusCode::OK {
                    return self.fail_the_connection();
                }
                let mime = match meta.content_type {
                    None => return self.fail_the_connection(),
                    Some(ct) => <ContentType as Into<Mime>>::into(ct.into_inner()),
                };
                if (mime.type_(), mime.subtype()) != (mime::TEXT, mime::EVENT_STREAM) {
                    return self.fail_the_connection();
                }
                self.origin = meta.final_url.origin().ascii_serialization();
                // Step 15.4 announce the connection and interpret res's body line by line.
                self.announce_the_connection();
            },
            Err(error) => {
                // Step 15.2 if res is a network error, then reestablish the connection, unless
                // the user agent knows that to be futile, in which case the user agent may
                // fail the connection.
                if error.is_permanent_failure() {
                    self.fail_the_connection()
                } else {
                    self.reestablish_the_connection()
                }
            },
        }
    }

    fn process_response_chunk(
        &mut self,
        cx: &mut js::context::JSContext,
        _: RequestId,
        chunk: Vec<u8>,
    ) {
        let mut output = String::with_capacity(chunk.len());
        let mut input = &chunk[..];

        loop {
            if input.is_empty() {
                return;
            }
            let (result, bytes_read) =
                self.decoder
                    .decode_to_string_without_replacement(input, &mut output, false);
            match result {
                encoding_rs::DecoderResult::InputEmpty => {
                    self.parse(cx, output.chars());
                    return;
                },
                encoding_rs::DecoderResult::Malformed(_, _) => {
                    self.parse(cx, output.chars());
                    self.parse(cx, "\u{FFFD}".chars());
                    output.clear();
                    input = &input[bytes_read..];
                },
                encoding_rs::DecoderResult::OutputFull => {
                    self.parse(cx, output.chars());
                    output.clear();
                    input = &input[bytes_read..];
                },
            }
        }
    }

    fn process_response_eof(
        mut self,
        cx: &mut js::context::JSContext,
        _: RequestId,
        response: Result<(), NetworkError>,
        timing: ResourceFetchTiming,
    ) {
        let mut output = String::new();
        let (result, _) = self
            .decoder
            .decode_to_string_without_replacement(&[], &mut output, true);
        if !output.is_empty() {
            self.parse(cx, "\u{FFFD}".chars());
        }
        if matches!(result, encoding_rs::DecoderResult::Malformed(_, _)) {
            self.parse(cx, "\u{FFFD}".chars());
        }
        if response.is_ok() {
            self.reestablish_the_connection();
        }

        network_listener::submit_timing(cx, &self, &response, &timing);
    }

    fn process_csp_violations(&mut self, _request_id: RequestId, violations: Vec<Violation>) {
        let global = &self.resource_timing_global();
        global.report_csp_violations(violations, None, None);
    }
}

impl ResourceTimingListener for EventSourceContext {
    fn resource_timing_information(&self) -> (InitiatorType, ServoUrl) {
        (InitiatorType::Other, self.event_source.root().url().clone())
    }

    fn resource_timing_global(&self) -> DomRoot<GlobalScope> {
        self.event_source.root().global()
    }
}

impl EventSource {
    fn new_inherited(url: ServoUrl, with_credentials: bool) -> EventSource {
        EventSource {
            eventtarget: EventTarget::new_inherited(),
            url,
            request: DomRefCell::new(None),
            last_event_id: DomRefCell::new(DOMString::from("")),
            reconnection_time: Cell::new(DEFAULT_RECONNECTION_TIME),
            generation_id: Cell::new(GenerationId(0)),

            ready_state: Cell::new(ReadyState::Connecting),
            with_credentials,
            droppable: DroppableEventSource::new(DomRefCell::new(Default::default())),
        }
    }

    fn new(
        global: &GlobalScope,
        proto: Option<HandleObject>,
        url: ServoUrl,
        with_credentials: bool,
        can_gc: CanGc,
    ) -> DomRoot<EventSource> {
        reflect_dom_object_with_proto(
            Box::new(EventSource::new_inherited(url, with_credentials)),
            global,
            proto,
            can_gc,
        )
    }

    // https://html.spec.whatwg.org/multipage/#sse-processing-model:fail-the-connection-3
    pub(crate) fn cancel(&self) {
        self.droppable.cancel();
        self.fail_the_connection();
    }

    /// <https://html.spec.whatwg.org/multipage/#fail-the-connection>
    pub(crate) fn fail_the_connection(&self) {
        let global = self.global();
        let event_source = Trusted::new(self);
        global.task_manager().remote_event_task_source().queue(
            task!(fail_the_event_source_connection: move || {
                let event_source = event_source.root();
                if event_source.ready_state.get() != ReadyState::Closed {
                    event_source.ready_state.set(ReadyState::Closed);
                    event_source.upcast::<EventTarget>().fire_event(atom!("error"), CanGc::note());
                }
            }),
        );
    }

    pub(crate) fn request(&self) -> RequestBuilder {
        self.request.borrow().clone().unwrap()
    }

    pub(crate) fn url(&self) -> &ServoUrl {
        &self.url
    }
}

impl EventSourceMethods<crate::DomTypeHolder> for EventSource {
    /// <https://html.spec.whatwg.org/multipage/#dom-eventsource>
    fn Constructor(
        global: &GlobalScope,
        proto: Option<HandleObject>,
        can_gc: CanGc,
        url: DOMString,
        event_source_init: &EventSourceInit,
    ) -> Fallible<DomRoot<EventSource>> {
        // Step 2. Let settings be the relevant settings object for the `EventSource` constructor.
        // Bindings pass that environment as `global`.
        // Step 3. Let urlRecord be the result of encoding-parsing a URL given url, relative to settings.
        let url_record = match global.encoding_parse_a_url(&url.str()) {
            Ok(u) => u,
            // Step 4 If urlRecord is failure, then throw a "SyntaxError" DOMException.
            Err(_) => return Err(Error::Syntax(None)),
        };
        // Step 1 Let ev be a new EventSource object.
        let event_source = EventSource::new(
            global,
            proto,
            // Step 5 Set ev's url to urlRecord.
            url_record.clone(),
            event_source_init.withCredentials,
            can_gc,
        );
        global.track_event_source(&event_source);
        let cors_attribute_state = if event_source_init.withCredentials {
            // Step 7 If the value of eventSourceInitDict's withCredentials member is true,
            // then set corsAttributeState to Use Credentials and set ev's withCredentials
            // attribute to true.
            CorsSettings::UseCredentials
        } else {
            // Step 6 Let corsAttributeState be Anonymous.
            CorsSettings::Anonymous
        };
        // Step 8 Let request be the result of creating a potential-CORS request
        // given urlRecord, the empty string, and corsAttributeState.
        // Step 9. Set request's client to the environment settings object and other state;
        // `with_global_scope` supplies client, origin, policy container, etc.
        let mut request = create_a_potential_cors_request(
            global.webview_id(),
            url_record,
            Destination::None,
            Some(cors_attribute_state),
            Some(true),
            global.get_referrer(),
        )
        .with_global_scope(global);

        // Step 10 User agents may set (`Accept`, `text/event-stream`) in request's header list.
        // TODO(eijebong): Replace once typed headers allow it
        request.headers.insert(
            header::ACCEPT,
            HeaderValue::from_static("text/event-stream"),
        );
        // Step 11 Set request's cache mode to "no-store".
        request.cache_mode = CacheMode::NoStore;
        // Step 13 Set ev's request to request.
        *event_source.request.borrow_mut() = Some(request.clone());
        // Step 14 Let processEventSourceEndOfBody given response res be the following step:
        // if res is not a network error, then reestablish the connection.

        event_source.droppable.set_canceller(FetchCanceller::new(
            request.id,
            false,
            global.core_resource_thread(),
        ));

        let context = EventSourceContext {
            decoder: UTF_8.new_decoder_with_bom_removal(),
            event_source: Trusted::new(&event_source),
            gen_id: event_source.generation_id.get(),
            parser_state: ParserState::Eol,
            field: String::new(),
            value: String::new(),
            origin: String::new(),

            event_type: String::new(),
            data: String::new(),
            last_event_id: String::new(),
        };

        let task_source = global.task_manager().networking_task_source().into();
        global.fetch(request, context, task_source);

        // Step 16 Return ev.
        Ok(event_source)
    }

    // https://html.spec.whatwg.org/multipage/#handler-eventsource-onopen
    event_handler!(open, GetOnopen, SetOnopen);

    // https://html.spec.whatwg.org/multipage/#handler-eventsource-onmessage
    event_handler!(message, GetOnmessage, SetOnmessage);

    // https://html.spec.whatwg.org/multipage/#handler-eventsource-onerror
    event_handler!(error, GetOnerror, SetOnerror);

    /// <https://html.spec.whatwg.org/multipage/#dom-eventsource-url>
    fn Url(&self) -> DOMString {
        DOMString::from(self.url.as_str())
    }

    /// <https://html.spec.whatwg.org/multipage/#dom-eventsource-withcredentials>
    fn WithCredentials(&self) -> bool {
        self.with_credentials
    }

    /// <https://html.spec.whatwg.org/multipage/#dom-eventsource-readystate>
    fn ReadyState(&self) -> u16 {
        self.ready_state.get() as u16
    }

    /// <https://html.spec.whatwg.org/multipage/#dom-eventsource-close>
    fn Close(&self) {
        let GenerationId(prev_id) = self.generation_id.get();
        self.generation_id.set(GenerationId(prev_id + 1));
        self.droppable.cancel();
        self.ready_state.set(ReadyState::Closed);
    }
}

#[derive(JSTraceable, MallocSizeOf)]
pub(crate) struct EventSourceTimeoutCallback {
    #[ignore_malloc_size_of = "Because it is non-owning"]
    event_source: Trusted<EventSource>,
    #[no_trace]
    event_source_context: EventSourceContext,
}

impl EventSourceTimeoutCallback {
    /// <https://html.spec.whatwg.org/multipage/#reestablish-the-connection>
    pub(crate) fn invoke(self) {
        let event_source = self.event_source.root();
        let global = event_source.global();

        // Step 5.1: If the EventSource object's readyState attribute is not set to CONNECTING, then return.
        if event_source.ready_state.get() != ReadyState::Connecting {
            return;
        }

        // Step 5.2: Let request be the EventSource object's request.
        let mut request = event_source.request();

        // Step 5.3: If the EventSource object's last event ID string is not the empty string, then:
        //  - Let lastEventIDValue be the EventSource object's last event ID string, encoded as UTF-8.
        //  - Set (`Last-Event-ID`, lastEventIDValue) in request's header list.
        if !event_source.last_event_id.borrow().is_empty() {
            // TODO(eijebong): Change this once typed header support custom values
            request.headers.insert(
                HeaderName::from_static("last-event-id"),
                HeaderValue::from_str(&String::from(event_source.last_event_id.borrow().clone()))
                    .unwrap(),
            );
        }

        // Step 5.4: Fetch request and process the response obtained in this fashion, if
        // any, as described earlier in this section.
        let task_source = global.task_manager().networking_task_source().into();
        global.fetch(request, self.event_source_context, task_source);
    }
}