1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
352
353
354
355
356
357
358
359
360
361
362
363
364
365
366
367
368
369
370
371
372
373
374
375
376
377
378
379
380
381
382
383
384
385
386
387
388
389
390
391
392
393
394
395
396
397
398
399
400
401
402
403
404
405
406
407
408
409
410
411
412
/* 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/. */

//! This module implements structured cloning, as defined by [HTML](https://html.spec.whatwg.org/multipage/#safe-passing-of-structured-data).

use std::collections::HashMap;
use std::os::raw;
use std::ptr;

use base::id::{BlobId, MessagePortId};
use js::glue::{
    CopyJSStructuredCloneData, DeleteJSAutoStructuredCloneBuffer, GetLengthOfJSStructuredCloneData,
    NewJSAutoStructuredCloneBuffer, WriteBytesToJSStructuredCloneData,
};
use js::jsapi::{
    CloneDataPolicy, HandleObject as RawHandleObject, JSContext, JSObject,
    JSStructuredCloneCallbacks, JSStructuredCloneReader, JSStructuredCloneWriter,
    JS_ClearPendingException, JS_ReadUint32Pair, JS_WriteUint32Pair,
    MutableHandleObject as RawMutableHandleObject, StructuredCloneScope, TransferableOwnership,
    JS_STRUCTURED_CLONE_VERSION,
};
use js::jsval::UndefinedValue;
use js::rust::wrappers::{JS_ReadStructuredClone, JS_WriteStructuredClone};
use js::rust::{CustomAutoRooterGuard, HandleValue, MutableHandleValue};
use script_traits::serializable::BlobImpl;
use script_traits::transferable::MessagePortImpl;
use script_traits::StructuredSerializedData;

use crate::dom::bindings::conversions::{root_from_object, ToJSValConvertible};
use crate::dom::bindings::error::{Error, Fallible};
use crate::dom::bindings::reflector::DomObject;
use crate::dom::bindings::root::DomRoot;
use crate::dom::bindings::serializable::{Serializable, StorageKey};
use crate::dom::bindings::transferable::Transferable;
use crate::dom::blob::Blob;
use crate::dom::globalscope::GlobalScope;
use crate::dom::messageport::MessagePort;
use crate::realms::{enter_realm, AlreadyInRealm, InRealm};
use crate::script_runtime::JSContext as SafeJSContext;

// TODO: Should we add Min and Max const to https://github.com/servo/rust-mozjs/blob/master/src/consts.rs?
// TODO: Determine for sure which value Min and Max should have.
// NOTE: Current values found at https://dxr.mozilla.org/mozilla-central/
// rev/ff04d410e74b69acfab17ef7e73e7397602d5a68/js/public/StructuredClone.h#323
#[repr(u32)]
pub(super) enum StructuredCloneTags {
    /// To support additional types, add new tags with values incremented from the last one before Max.
    Min = 0xFFFF8000,
    DomBlob = 0xFFFF8001,
    MessagePort = 0xFFFF8002,
    Principals = 0xFFFF8003,
    Max = 0xFFFFFFFF,
}

unsafe fn read_blob(
    owner: &GlobalScope,
    r: *mut JSStructuredCloneReader,
    sc_holder: &mut StructuredDataHolder,
) -> *mut JSObject {
    let mut name_space: u32 = 0;
    let mut index: u32 = 0;
    assert!(JS_ReadUint32Pair(
        r,
        &mut name_space as *mut u32,
        &mut index as *mut u32
    ));
    let storage_key = StorageKey { index, name_space };
    if <Blob as Serializable>::deserialize(owner, sc_holder, storage_key).is_ok() {
        let blobs = match sc_holder {
            StructuredDataHolder::Read { blobs, .. } => blobs,
            _ => panic!("Unexpected variant of StructuredDataHolder"),
        };
        if let Some(blobs) = blobs {
            let blob = blobs
                .get(&storage_key)
                .expect("No blob found at storage key.");
            return blob.reflector().get_jsobject().get();
        }
    }
    warn!(
        "Reading structured data for a blob failed in {:?}.",
        owner.get_url()
    );
    ptr::null_mut()
}

unsafe fn write_blob(
    owner: &GlobalScope,
    blob: DomRoot<Blob>,
    w: *mut JSStructuredCloneWriter,
    sc_holder: &mut StructuredDataHolder,
) -> bool {
    if let Ok(storage_key) = blob.serialize(sc_holder) {
        assert!(JS_WriteUint32Pair(
            w,
            StructuredCloneTags::DomBlob as u32,
            0
        ));
        assert!(JS_WriteUint32Pair(
            w,
            storage_key.name_space,
            storage_key.index
        ));
        return true;
    }
    warn!(
        "Writing structured data for a blob failed in {:?}.",
        owner.get_url()
    );
    false
}

unsafe extern "C" fn read_callback(
    cx: *mut JSContext,
    r: *mut JSStructuredCloneReader,
    _policy: *const CloneDataPolicy,
    tag: u32,
    _data: u32,
    closure: *mut raw::c_void,
) -> *mut JSObject {
    assert!(
        tag < StructuredCloneTags::Max as u32,
        "tag should be lower than StructuredCloneTags::Max"
    );
    assert!(
        tag > StructuredCloneTags::Min as u32,
        "tag should be higher than StructuredCloneTags::Min"
    );
    if tag == StructuredCloneTags::DomBlob as u32 {
        let in_realm_proof = AlreadyInRealm::assert_for_cx(SafeJSContext::from_ptr(cx));
        return read_blob(
            &GlobalScope::from_context(cx, InRealm::Already(&in_realm_proof)),
            r,
            &mut *(closure as *mut StructuredDataHolder),
        );
    }
    ptr::null_mut()
}

unsafe extern "C" fn write_callback(
    cx: *mut JSContext,
    w: *mut JSStructuredCloneWriter,
    obj: RawHandleObject,
    _same_process_scope_required: *mut bool,
    closure: *mut raw::c_void,
) -> bool {
    if let Ok(blob) = root_from_object::<Blob>(*obj, cx) {
        let in_realm_proof = AlreadyInRealm::assert_for_cx(SafeJSContext::from_ptr(cx));
        return write_blob(
            &GlobalScope::from_context(cx, InRealm::Already(&in_realm_proof)),
            blob,
            w,
            &mut *(closure as *mut StructuredDataHolder),
        );
    }
    false
}

unsafe extern "C" fn read_transfer_callback(
    cx: *mut JSContext,
    _r: *mut JSStructuredCloneReader,
    tag: u32,
    _content: *mut raw::c_void,
    extra_data: u64,
    closure: *mut raw::c_void,
    return_object: RawMutableHandleObject,
) -> bool {
    if tag == StructuredCloneTags::MessagePort as u32 {
        let sc_holder = &mut *(closure as *mut StructuredDataHolder);
        let in_realm_proof = AlreadyInRealm::assert_for_cx(SafeJSContext::from_ptr(cx));
        let owner = GlobalScope::from_context(cx, InRealm::Already(&in_realm_proof));
        if <MessagePort as Transferable>::transfer_receive(
            &owner,
            sc_holder,
            extra_data,
            return_object,
        )
        .is_ok()
        {
            return true;
        }
    }
    false
}

/// <https://html.spec.whatwg.org/multipage/#structuredserializewithtransfer>
unsafe extern "C" fn write_transfer_callback(
    cx: *mut JSContext,
    obj: RawHandleObject,
    closure: *mut raw::c_void,
    tag: *mut u32,
    ownership: *mut TransferableOwnership,
    _content: *mut *mut raw::c_void,
    extra_data: *mut u64,
) -> bool {
    if let Ok(port) = root_from_object::<MessagePort>(*obj, cx) {
        *tag = StructuredCloneTags::MessagePort as u32;
        *ownership = TransferableOwnership::SCTAG_TMO_CUSTOM;
        let sc_holder = &mut *(closure as *mut StructuredDataHolder);
        if let Ok(data) = port.transfer(sc_holder) {
            *extra_data = data;
            return true;
        }
    }
    false
}

unsafe extern "C" fn free_transfer_callback(
    _tag: u32,
    _ownership: TransferableOwnership,
    _content: *mut raw::c_void,
    _extra_data: u64,
    _closure: *mut raw::c_void,
) {
}

unsafe extern "C" fn can_transfer_callback(
    cx: *mut JSContext,
    obj: RawHandleObject,
    _same_process_scope_required: *mut bool,
    _closure: *mut raw::c_void,
) -> bool {
    if let Ok(_port) = root_from_object::<MessagePort>(*obj, cx) {
        return true;
    }
    false
}

unsafe extern "C" fn report_error_callback(
    _cx: *mut JSContext,
    _errorid: u32,
    _closure: *mut ::std::os::raw::c_void,
    _error_message: *const ::std::os::raw::c_char,
) {
}

unsafe extern "C" fn sab_cloned_callback(
    _cx: *mut JSContext,
    _receiving: bool,
    _closure: *mut ::std::os::raw::c_void,
) -> bool {
    false
}

static STRUCTURED_CLONE_CALLBACKS: JSStructuredCloneCallbacks = JSStructuredCloneCallbacks {
    read: Some(read_callback),
    write: Some(write_callback),
    reportError: Some(report_error_callback),
    readTransfer: Some(read_transfer_callback),
    writeTransfer: Some(write_transfer_callback),
    freeTransfer: Some(free_transfer_callback),
    canTransfer: Some(can_transfer_callback),
    sabCloned: Some(sab_cloned_callback),
};

/// A data holder for results from, and inputs to, structured-data read/write operations.
/// <https://html.spec.whatwg.org/multipage/#safe-passing-of-structured-data>
pub enum StructuredDataHolder {
    Read {
        /// A map of deserialized blobs, stored temporarily here to keep them rooted.
        blobs: Option<HashMap<StorageKey, DomRoot<Blob>>>,
        /// A vec of transfer-received DOM ports,
        /// to be made available to script through a message event.
        message_ports: Option<Vec<DomRoot<MessagePort>>>,
        /// A map of port implementations,
        /// used as part of the "transfer-receiving" steps of ports,
        /// to produce the DOM ports stored in `message_ports` above.
        port_impls: Option<HashMap<MessagePortId, MessagePortImpl>>,
        /// A map of blob implementations,
        /// used as part of the "deserialize" steps of blobs,
        /// to produce the DOM blobs stored in `blobs` above.
        blob_impls: Option<HashMap<BlobId, BlobImpl>>,
    },
    /// A data holder for transferred and serialized objects.
    Write {
        /// Transferred ports.
        ports: Option<HashMap<MessagePortId, MessagePortImpl>>,
        /// Serialized blobs.
        blobs: Option<HashMap<BlobId, BlobImpl>>,
    },
}

/// Writes a structured clone. Returns a `DataClone` error if that fails.
pub fn write(
    cx: SafeJSContext,
    message: HandleValue,
    transfer: Option<CustomAutoRooterGuard<Vec<*mut JSObject>>>,
) -> Fallible<StructuredSerializedData> {
    unsafe {
        rooted!(in(*cx) let mut val = UndefinedValue());
        if let Some(transfer) = transfer {
            transfer.to_jsval(*cx, val.handle_mut());
        }
        let mut sc_holder = StructuredDataHolder::Write {
            ports: None,
            blobs: None,
        };
        let sc_holder_ptr = &mut sc_holder as *mut _;

        let scbuf = NewJSAutoStructuredCloneBuffer(
            StructuredCloneScope::DifferentProcess,
            &STRUCTURED_CLONE_CALLBACKS,
        );
        let scdata = &mut ((*scbuf).data_);
        let policy = CloneDataPolicy {
            allowIntraClusterClonableSharedObjects_: false,
            allowSharedMemoryObjects_: false,
        };
        let result = JS_WriteStructuredClone(
            *cx,
            message,
            scdata,
            StructuredCloneScope::DifferentProcess,
            &policy,
            &STRUCTURED_CLONE_CALLBACKS,
            sc_holder_ptr as *mut raw::c_void,
            val.handle(),
        );
        if !result {
            JS_ClearPendingException(*cx);
            return Err(Error::DataClone);
        }

        let nbytes = GetLengthOfJSStructuredCloneData(scdata);
        let mut data = Vec::with_capacity(nbytes);
        CopyJSStructuredCloneData(scdata, data.as_mut_ptr());
        data.set_len(nbytes);

        DeleteJSAutoStructuredCloneBuffer(scbuf);

        let (mut blob_impls, mut port_impls) = match sc_holder {
            StructuredDataHolder::Write { blobs, ports } => (blobs, ports),
            _ => panic!("Unexpected variant of StructuredDataHolder"),
        };

        let data = StructuredSerializedData {
            serialized: data,
            ports: port_impls.take(),
            blobs: blob_impls.take(),
        };

        Ok(data)
    }
}

/// Read structured serialized data, possibly containing transferred objects.
/// Returns a vec of rooted transfer-received ports, or an error.
pub fn read(
    global: &GlobalScope,
    mut data: StructuredSerializedData,
    rval: MutableHandleValue,
) -> Result<Vec<DomRoot<MessagePort>>, ()> {
    let cx = GlobalScope::get_cx();
    let _ac = enter_realm(global);
    let mut sc_holder = StructuredDataHolder::Read {
        blobs: None,
        message_ports: None,
        port_impls: data.ports.take(),
        blob_impls: data.blobs.take(),
    };
    let sc_holder_ptr = &mut sc_holder as *mut _;
    unsafe {
        let scbuf = NewJSAutoStructuredCloneBuffer(
            StructuredCloneScope::DifferentProcess,
            &STRUCTURED_CLONE_CALLBACKS,
        );
        let scdata = &mut ((*scbuf).data_);

        WriteBytesToJSStructuredCloneData(
            data.serialized.as_mut_ptr() as *const u8,
            data.serialized.len(),
            scdata,
        );

        let result = JS_ReadStructuredClone(
            *cx,
            scdata,
            JS_STRUCTURED_CLONE_VERSION,
            StructuredCloneScope::DifferentProcess,
            rval,
            &CloneDataPolicy {
                allowIntraClusterClonableSharedObjects_: false,
                allowSharedMemoryObjects_: false,
            },
            &STRUCTURED_CLONE_CALLBACKS,
            sc_holder_ptr as *mut raw::c_void,
        );

        DeleteJSAutoStructuredCloneBuffer(scbuf);

        if result {
            let (mut message_ports, port_impls) = match sc_holder {
                StructuredDataHolder::Read {
                    message_ports,
                    port_impls,
                    ..
                } => (message_ports, port_impls),
                _ => panic!("Unexpected variant of StructuredDataHolder"),
            };

            // Any transfer-received port-impls should have been taken out.
            assert!(port_impls.is_none());

            match message_ports.take() {
                Some(ports) => return Ok(ports),
                None => return Ok(Vec::with_capacity(0)),
            }
        }
        Err(())
    }
}