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
413
414
415
416
417
418
419
420
421
422
423
424
425
426
427
428
429
430
431
432
433
434
435
436
437
438
439
440
441
442
443
444
445
446
447
448
449
450
451
452
453
454
455
456
457
458
459
460
461
462
463
464
465
466
467
468
469
470
471
472
473
474
475
476
477
478
479
480
481
482
483
484
485
486
487
488
489
490
491
492
493
494
495
496
497
498
499
500
501
502
503
504
505
506
507
508
509
510
511
512
513
514
515
516
517
518
519
520
521
522
523
524
525
526
527
528
529
530
531
532
533
534
535
536
537
538
539
540
541
542
543
544
545
546
547
548
549
550
551
552
553
554
555
556
557
558
559
560
561
562
563
564
565
566
567
568
569
570
571
572
573
574
575
576
577
578
579
580
581
582
583
584
585
586
587
588
589
590
591
592
593
594
595
596
597
598
599
600
601
602
603
604
605
606
607
608
609
610
611
612
613
614
615
616
617
618
619
620
621
622
623
624
625
626
627
628
629
630
631
632
633
634
635
636
637
638
639
640
641
642
643
644
645
646
647
648
649
650
651
652
653
654
655
656
657
658
659
660
661
//! Wayland socket manipulation

use std::os::unix::io::{AsRawFd, FromRawFd, IntoRawFd, RawFd};

use nix::sys::socket;
use nix::sys::uio;
use nix::Result as NixResult;

use wire::{ArgumentType, Message, MessageParseError, MessageWriteError};

/// Maximum number of FD that can be sent in a single socket message
pub const MAX_FDS_OUT: usize = 28;
/// Maximum number of bytes that can be sent in a single socket message
pub const MAX_BYTES_OUT: usize = 4096;

/*
 * Socket
 */

/// A wayland socket
pub struct Socket {
    fd: RawFd,
}

impl Socket {
    /// Send a single message to the socket
    ///
    /// A single socket message can contain several wayland messages
    ///
    /// The `fds` slice should not be longer than `MAX_FDS_OUT`, and the `bytes`
    /// slice should not be longer than `MAX_BYTES_OUT` otherwise the receiving
    /// end may lose some data.
    pub fn send_msg(&self, bytes: &[u8], fds: &[RawFd]) -> NixResult<()> {
        let iov = [uio::IoVec::from_slice(bytes)];
        if fds.len() > 0 {
            let cmsgs = [socket::ControlMessage::ScmRights(fds)];
            socket::sendmsg(self.fd, &iov, &cmsgs, socket::MsgFlags::MSG_DONTWAIT, None)?;
        } else {
            socket::sendmsg(self.fd, &iov, &[], socket::MsgFlags::MSG_DONTWAIT, None)?;
        };
        Ok(())
    }

    /// Receive a single message from the socket
    ///
    /// Return the number of bytes received and the number of Fds received.
    ///
    /// Errors with `WouldBlock` is no message is available.
    ///
    /// A single socket message can contain several wayland messages.
    ///
    /// The `buffer` slice should be at least `MAX_BYTES_OUT` long and the `fds`
    /// slice `MAX_FDS_OUT` long, otherwise some data of the received message may
    /// be lost.
    pub fn rcv_msg(&self, buffer: &mut [u8], fds: &mut [RawFd]) -> NixResult<(usize, usize)> {
        let mut cmsg = cmsg_space!([RawFd; MAX_FDS_OUT]);
        let iov = [uio::IoVec::from_mut_slice(buffer)];

        let msg = socket::recvmsg(self.fd, &iov[..], Some(&mut cmsg), socket::MsgFlags::MSG_DONTWAIT)?;

        let mut fd_count = 0;
        let received_fds = msg.cmsgs().flat_map(|cmsg| {
            match cmsg {
                socket::ControlMessageOwned::ScmRights(s) => s,
                _ => Vec::new(),
            }
        });
        for (fd, place) in received_fds.zip(fds.iter_mut()) {
            fd_count += 1;
            *place = fd;
        }
        Ok((msg.bytes, fd_count))
    }
}

impl FromRawFd for Socket {
    unsafe fn from_raw_fd(fd: RawFd) -> Socket {
        Socket { fd }
    }
}

impl AsRawFd for Socket {
    fn as_raw_fd(&self) -> RawFd {
        self.fd
    }
}

impl IntoRawFd for Socket {
    fn into_raw_fd(self) -> RawFd {
        self.fd
    }
}

impl Drop for Socket {
    fn drop(&mut self) {
        let _ = ::nix::unistd::close(self.fd);
    }
}

/*
 * BufferedSocket
 */

/// An adapter around a raw Socket that directly handles buffering and
/// conversion from/to wayland messages
pub struct BufferedSocket {
    socket: Socket,
    in_data: Buffer<u32>,
    in_fds: Buffer<RawFd>,
    out_data: Buffer<u32>,
    out_fds: Buffer<RawFd>,
}

impl BufferedSocket {
    /// Wrap a Socket into a Buffered Socket
    pub fn new(socket: Socket) -> BufferedSocket {
        BufferedSocket {
            socket: socket,
            in_data: Buffer::new(2 * MAX_BYTES_OUT / 4), // Incoming buffers are twice as big in order to be
            in_fds: Buffer::new(2 * MAX_FDS_OUT),        // able to store leftover data if needed
            out_data: Buffer::new(MAX_BYTES_OUT / 4),
            out_fds: Buffer::new(MAX_FDS_OUT),
        }
    }

    /// Get direct access to the underlying socket
    pub fn get_socket(&mut self) -> &mut Socket {
        &mut self.socket
    }

    /// Retrieve ownership of the underlying Socket
    ///
    /// Any leftover content in the internal buffers will be lost
    pub fn into_socket(self) -> Socket {
        self.socket
    }

    /// Flush the contents of the outgoing buffer into the socket
    pub fn flush(&mut self) -> NixResult<()> {
        {
            let words = self.out_data.get_contents();
            let bytes = unsafe { ::std::slice::from_raw_parts(words.as_ptr() as *const u8, words.len() * 4) };
            let fds = self.out_fds.get_contents();
            self.socket.send_msg(bytes, fds)?;
        }
        self.out_data.clear();
        self.out_fds.clear();
        Ok(())
    }

    // internal method
    //
    // attempts to write a message in the internal out buffers,
    // returns true if successful
    //
    // if false is returned, it means there is not enough space
    // in the buffer
    fn attempt_write_message(&mut self, msg: &Message) -> NixResult<bool> {
        match msg.write_to_buffers(
            self.out_data.get_writable_storage(),
            self.out_fds.get_writable_storage(),
        ) {
            Ok((bytes_out, fds_out)) => {
                self.out_data.advance(bytes_out);
                self.out_fds.advance(fds_out);
                Ok(true)
            }
            Err(MessageWriteError::BufferTooSmall) => Ok(false),
            Err(MessageWriteError::DupFdFailed(e)) => Err(e),
        }
    }

    /// Write a message to the outgoing buffer
    ///
    /// This method may flush the internal buffer if necessary (if it is full).
    ///
    /// If the message is too big to fit in the buffer, the error `Error::Sys(E2BIG)`
    /// will be returned.
    pub fn write_message(&mut self, msg: &Message) -> NixResult<()> {
        if !self.attempt_write_message(msg)? {
            // the attempt failed, there is not enough space in the buffer
            // we need to flush it
            self.flush()?;
            if !self.attempt_write_message(msg)? {
                // If this fails again, this means the message is too big
                // to be transmitted at all
                return Err(::nix::Error::Sys(::nix::errno::Errno::E2BIG));
            }
        }
        Ok(())
    }

    /// Try to fill the incoming buffers of this socket, to prepare
    /// a new round of parsing.
    pub fn fill_incoming_buffers(&mut self) -> NixResult<()> {
        // clear the buffers if they have no content
        if !self.in_data.has_content() {
            self.in_data.clear();
        }
        if !self.in_fds.has_content() {
            self.in_fds.clear();
        }
        // receive a message
        let (in_bytes, in_fds) = {
            let words = self.in_data.get_writable_storage();
            let bytes =
                unsafe { ::std::slice::from_raw_parts_mut(words.as_ptr() as *mut u8, words.len() * 4) };
            let fds = self.in_fds.get_writable_storage();
            self.socket.rcv_msg(bytes, fds)?
        };
        if in_bytes == 0 {
            // the other end of the socket was closed
            return Err(::nix::Error::Sys(::nix::errno::Errno::EPIPE));
        }
        // advance the storage
        self.in_data
            .advance(in_bytes / 4 + if in_bytes % 4 > 0 { 1 } else { 0 });
        self.in_fds.advance(in_fds);
        Ok(())
    }

    /// Read and deserialize a single message from the incoming buffers socket
    ///
    /// This method requires one closure that given an object id and an opcode,
    /// must provide the signature of the associated request/event, in the form of
    /// a `&'static [ArgumentType]`. If it returns `None`, meaning that
    /// the couple object/opcode does not exist, an error will be returned.
    ///
    /// There are 3 possibilities of return value:
    ///
    /// - `Ok(Ok(msg))`: no error occurred, this is the message
    /// - `Ok(Err(e))`: either a malformed message was encountered or we need more data,
    ///    in the latter case you need to try calling `fill_incoming_buffers()`.
    /// - `Err(e)`: an I/O error occurred reading from the socked, details are in `e`
    ///   (this can be a "wouldblock" error, which just means that no message is available
    ///   to read)
    pub fn read_one_message<F>(&mut self, mut signature: F) -> Result<Message, MessageParseError>
    where
        F: FnMut(u32, u16) -> Option<&'static [ArgumentType]>,
    {
        let (msg, read_data, read_fd) = {
            let data = self.in_data.get_contents();
            let fds = self.in_fds.get_contents();
            if data.len() < 2 {
                return Err(MessageParseError::MissingData);
            }
            let object_id = data[0];
            let opcode = (data[1] & 0x0000FFFF) as u16;
            if let Some(sig) = signature(object_id, opcode) {
                match Message::from_raw(data, sig, fds) {
                    Ok((msg, rest_data, rest_fds)) => {
                        (msg, data.len() - rest_data.len(), fds.len() - rest_fds.len())
                    }
                    // TODO: gracefully handle wayland messages split across unix messages ?
                    Err(e) => return Err(e),
                }
            } else {
                // no signature found ?
                return Err(MessageParseError::Malformed);
            }
        };

        self.in_data.offset(read_data);
        self.in_fds.offset(read_fd);

        Ok(msg)
    }

    /// Read and deserialize messages from the socket
    ///
    /// This method requires two closures:
    ///
    /// - The first one, given an object id and an opcode, must provide
    ///   the signature of the associated request/event, in the form of
    ///   a `&'static [ArgumentType]`. If it returns `None`, meaning that
    ///   the couple object/opcode does not exist, the parsing will be
    ///   prematurely interrupted and this method will return a
    ///   `MessageParseError::Malformed` error.
    /// - The second closure is charged to process the parsed message. If it
    ///   returns `false`, the iteration will be prematurely stopped.
    ///
    /// In both cases of early stopping, the remaining unused data will be left
    /// in the buffers, and will start to be processed at the next call of this
    /// method.
    ///
    /// There are 3 possibilities of return value:
    ///
    /// - `Ok(Ok(n))`: no error occurred, `n` messages where processed
    /// - `Ok(Err(MessageParseError::Malformed))`: a malformed message was encountered
    ///   (this is a protocol error and is supposed to be fatal to the connection).
    /// - `Err(e)`: an I/O error occurred reading from the socked, details are in `e`
    ///   (this can be a "wouldblock" error, which just means that no message is available
    ///   to read)
    pub fn read_messages<F1, F2>(
        &mut self,
        mut signature: F1,
        mut callback: F2,
    ) -> NixResult<Result<usize, MessageParseError>>
    where
        F1: FnMut(u32, u16) -> Option<&'static [ArgumentType]>,
        F2: FnMut(Message) -> bool,
    {
        // message parsing
        let mut dispatched = 0;

        loop {
            let mut err = None;
            // first parse any leftover messages
            loop {
                match self.read_one_message(&mut signature) {
                    Ok(msg) => {
                        let keep_going = callback(msg);
                        dispatched += 1;
                        if !keep_going {
                            break;
                        }
                    }
                    Err(e) => {
                        err = Some(e);
                        break;
                    }
                }
            }

            // copy back any leftover content to the front of the buffer
            self.in_data.move_to_front();
            self.in_fds.move_to_front();

            if let Some(MessageParseError::Malformed) = err {
                // early stop here
                return Ok(Err(MessageParseError::Malformed));
            }

            if err.is_none() && self.in_data.has_content() {
                // we stopped reading without error while there is content? That means
                // the user requested an early stopping
                return Ok(Ok(dispatched));
            }

            // now, try to get more data
            match self.fill_incoming_buffers() {
                Ok(()) => (),
                Err(e @ ::nix::Error::Sys(::nix::errno::Errno::EAGAIN)) => {
                    // stop looping, returning Ok() or EAGAIN depending on whether messages
                    // were dispatched
                    if dispatched == 0 {
                        return Err(e);
                    } else {
                        break;
                    }
                }
                Err(e) => return Err(e),
            }
        }

        Ok(Ok(dispatched))
    }
}

/*
 * Buffer
 */

struct Buffer<T: Copy> {
    storage: Vec<T>,
    occupied: usize,
    offset: usize,
}

impl<T: Copy + Default> Buffer<T> {
    fn new(size: usize) -> Buffer<T> {
        Buffer {
            storage: vec![T::default(); size],
            occupied: 0,
            offset: 0,
        }
    }

    /// Check if this buffer has content to read
    fn has_content(&self) -> bool {
        self.occupied > self.offset
    }

    /// Advance the internal counter of occupied space
    fn advance(&mut self, bytes: usize) {
        self.occupied += bytes;
    }

    /// Advance the read offset of current occupied space
    fn offset(&mut self, bytes: usize) {
        self.offset += bytes;
    }

    /// Clears the contents of the buffer
    ///
    /// This only sets the counter of occupied space back to zero,
    /// allowing previous content to be overwritten.
    fn clear(&mut self) {
        self.occupied = 0;
        self.offset = 0;
    }

    /// Get the current contents of the occupied space of the buffer
    fn get_contents(&self) -> &[T] {
        &self.storage[(self.offset)..(self.occupied)]
    }

    /// Get mutable access to the unoccupied space of the buffer
    fn get_writable_storage(&mut self) -> &mut [T] {
        &mut self.storage[(self.occupied)..]
    }

    /// Move the unread contents of the buffer to the front, to ensure
    /// maximal write space availability
    fn move_to_front(&mut self) {
        unsafe {
            ::std::ptr::copy(
                &self.storage[self.offset] as *const T,
                &mut self.storage[0] as *mut T,
                self.occupied - self.offset,
            );
        }
        self.occupied -= self.offset;
        self.offset = 0;
    }
}

#[cfg(test)]
mod tests {
    use super::*;
    use wire::{Argument, ArgumentType, Message};

    use std::ffi::CString;

    fn same_file(a: RawFd, b: RawFd) -> bool {
        let stat1 = ::nix::sys::stat::fstat(a).unwrap();
        let stat2 = ::nix::sys::stat::fstat(b).unwrap();
        stat1.st_dev == stat2.st_dev && stat1.st_ino == stat2.st_ino
    }

    // check if two messages are equal
    //
    // if arguments contain FDs, check that the fd point to
    // the same file, rather than are the same number.
    fn assert_eq_msgs(msg1: &Message, msg2: &Message) {
        assert_eq!(msg1.sender_id, msg2.sender_id);
        assert_eq!(msg1.opcode, msg2.opcode);
        assert_eq!(msg1.args.len(), msg2.args.len());
        for (arg1, arg2) in msg1.args.iter().zip(msg2.args.iter()) {
            if let (&Argument::Fd(fd1), &Argument::Fd(fd2)) = (arg1, arg2) {
                assert!(same_file(fd1, fd2));
            } else {
                assert_eq!(arg1, arg2);
            }
        }
    }

    #[test]
    fn write_read_cycle() {
        let msg = Message {
            sender_id: 42,
            opcode: 7,
            args: vec![
                Argument::Uint(3),
                Argument::Fixed(-89),
                Argument::Str(CString::new(&b"I like trains!"[..]).unwrap()),
                Argument::Array(vec![1, 2, 3, 4, 5, 6, 7, 8, 9]),
                Argument::Object(88),
                Argument::NewId(56),
                Argument::Int(-25),
            ],
        };

        let (client, server) = ::std::os::unix::net::UnixStream::pair().unwrap();
        let mut client = BufferedSocket::new(unsafe { Socket::from_raw_fd(client.into_raw_fd()) });
        let mut server = BufferedSocket::new(unsafe { Socket::from_raw_fd(server.into_raw_fd()) });

        client.write_message(&msg).unwrap();
        client.flush().unwrap();

        static SIGNATURE: &'static [ArgumentType] = &[
            ArgumentType::Uint,
            ArgumentType::Fixed,
            ArgumentType::Str,
            ArgumentType::Array,
            ArgumentType::Object,
            ArgumentType::NewId,
            ArgumentType::Int,
        ];

        let ret = server
            .read_messages(
                |sender_id, opcode| {
                    if sender_id == 42 && opcode == 7 {
                        Some(SIGNATURE)
                    } else {
                        None
                    }
                },
                |message| {
                    assert_eq_msgs(&message, &msg);
                    true
                },
            )
            .unwrap()
            .unwrap();

        assert_eq!(ret, 1);
    }

    #[test]
    fn write_read_cycle_fd() {
        let msg = Message {
            sender_id: 42,
            opcode: 7,
            args: vec![
                Argument::Fd(1), // stdin
                Argument::Fd(0), // stdout
            ],
        };

        let (client, server) = ::std::os::unix::net::UnixStream::pair().unwrap();
        let mut client = BufferedSocket::new(unsafe { Socket::from_raw_fd(client.into_raw_fd()) });
        let mut server = BufferedSocket::new(unsafe { Socket::from_raw_fd(server.into_raw_fd()) });

        client.write_message(&msg).unwrap();
        client.flush().unwrap();

        static SIGNATURE: &'static [ArgumentType] = &[ArgumentType::Fd, ArgumentType::Fd];

        let ret = server
            .read_messages(
                |sender_id, opcode| {
                    if sender_id == 42 && opcode == 7 {
                        Some(SIGNATURE)
                    } else {
                        None
                    }
                },
                |message| {
                    assert_eq_msgs(&message, &msg);
                    true
                },
            )
            .unwrap()
            .unwrap();

        assert_eq!(ret, 1);
    }

    #[test]
    fn write_read_cycle_multiple() {
        let messages = [
            Message {
                sender_id: 42,
                opcode: 0,
                args: vec![
                    Argument::Int(42),
                    Argument::Str(CString::new(&b"I like trains"[..]).unwrap()),
                ],
            },
            Message {
                sender_id: 42,
                opcode: 1,
                args: vec![
                    Argument::Fd(1), // stdin
                    Argument::Fd(0), // stdout
                ],
            },
            Message {
                sender_id: 42,
                opcode: 2,
                args: vec![
                    Argument::Uint(3),
                    Argument::Fd(2), // stderr
                ],
            },
        ];

        static SIGNATURES: &'static [&'static [ArgumentType]] = &[
            &[ArgumentType::Int, ArgumentType::Str],
            &[ArgumentType::Fd, ArgumentType::Fd],
            &[ArgumentType::Uint, ArgumentType::Fd],
        ];

        let (client, server) = ::std::os::unix::net::UnixStream::pair().unwrap();
        let mut client = BufferedSocket::new(unsafe { Socket::from_raw_fd(client.into_raw_fd()) });
        let mut server = BufferedSocket::new(unsafe { Socket::from_raw_fd(server.into_raw_fd()) });

        for msg in &messages {
            client.write_message(msg).unwrap();
        }
        client.flush().unwrap();

        let mut recv_msgs = Vec::new();
        let ret = server
            .read_messages(
                |sender_id, opcode| {
                    if sender_id == 42 {
                        Some(SIGNATURES[opcode as usize])
                    } else {
                        None
                    }
                },
                |message| {
                    recv_msgs.push(message);
                    true
                },
            )
            .unwrap()
            .unwrap();

        assert_eq!(ret, 3);
        assert_eq!(recv_msgs.len(), 3);
        for (msg1, msg2) in messages.iter().zip(recv_msgs.iter()) {
            assert_eq_msgs(msg1, msg2);
        }
    }

    #[test]
    fn parse_with_string_len_multiple_of_4() {
        let msg = Message {
            sender_id: 2,
            opcode: 0,
            args: vec![
                Argument::Uint(18),
                Argument::Str(CString::new(&b"wl_shell"[..]).unwrap()),
                Argument::Uint(1),
            ],
        };

        let (client, server) = ::std::os::unix::net::UnixStream::pair().unwrap();
        let mut client = BufferedSocket::new(unsafe { Socket::from_raw_fd(client.into_raw_fd()) });
        let mut server = BufferedSocket::new(unsafe { Socket::from_raw_fd(server.into_raw_fd()) });

        client.write_message(&msg).unwrap();
        client.flush().unwrap();

        static SIGNATURE: &'static [ArgumentType] =
            &[ArgumentType::Uint, ArgumentType::Str, ArgumentType::Uint];

        let ret = server
            .read_messages(
                |sender_id, opcode| {
                    if sender_id == 2 && opcode == 0 {
                        Some(SIGNATURE)
                    } else {
                        None
                    }
                },
                |message| {
                    assert_eq_msgs(&message, &msg);
                    true
                },
            )
            .unwrap()
            .unwrap();

        assert_eq!(ret, 1);
    }
}