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

use std::collections::VecDeque;
use std::io;

use crate::msgs::codec;
use crate::msgs::message::{Message, MessageError};

/// This deframer works to reconstruct TLS messages
/// from arbitrary-sized reads, buffering as necessary.
/// The input is `read()`, the output is the `frames` deque.
pub struct MessageDeframer {
    /// Completed frames for output.
    pub frames: VecDeque<Message>,

    /// Set to true if the peer is not talking TLS, but some other
    /// protocol.  The caller should abort the connection, because
    /// the deframer cannot recover.
    pub desynced: bool,

    /// A fixed-size buffer containing the currently-accumulating
    /// TLS message.
    buf: Box<[u8; Message::MAX_WIRE_SIZE]>,

    /// What size prefix of `buf` is used.
    used: usize,
}

enum BufferContents {
    /// Contains an invalid message as a header.
    Invalid,

    /// Might contain a valid message if we receive more.
    /// Perhaps totally empty!
    Partial,

    /// Contains a valid frame as a prefix.
    Valid,
}

impl Default for MessageDeframer {
    fn default() -> Self { Self::new() }
}

impl MessageDeframer {
    pub fn new() -> MessageDeframer {
        MessageDeframer {
            frames: VecDeque::new(),
            desynced: false,
            buf: Box::new([0u8; Message::MAX_WIRE_SIZE]),
            used: 0,
        }
    }

    /// Read some bytes from `rd`, and add them to our internal
    /// buffer.  If this means our internal buffer contains
    /// full messages, decode them all.
    pub fn read(&mut self, rd: &mut dyn io::Read) -> io::Result<usize> {
        // Try to do the largest reads possible.  Note that if
        // we get a message with a length field out of range here,
        // we do a zero length read.  That looks like an EOF to
        // the next layer up, which is fine.
        debug_assert!(self.used <= Message::MAX_WIRE_SIZE);
        let new_bytes = rd.read(&mut self.buf[self.used..])?;

        self.used += new_bytes;

        loop {
            match self.try_deframe_one() {
                BufferContents::Invalid => {
                    self.desynced = true;
                    break;
                }
                BufferContents::Valid => continue,
                BufferContents::Partial => break,
            }
        }

        Ok(new_bytes)
    }

    /// Returns true if we have messages for the caller
    /// to process, either whole messages in our output
    /// queue or partial messages in our buffer.
    pub fn has_pending(&self) -> bool {
        !self.frames.is_empty() || self.used > 0
    }

    /// Does our `buf` contain a full message?  It does if it is big enough to
    /// contain a header, and that header has a length which falls within `buf`.
    /// If so, deframe it and place the message onto the frames output queue.
    fn try_deframe_one(&mut self) -> BufferContents {
        // Try to decode a message off the front of buf.
        let mut rd = codec::Reader::init(&self.buf[..self.used]);

        match Message::read_with_detailed_error(&mut rd) {
            Ok(m) => {
                let used = rd.used();
                self.frames.push_back(m);
                self.buf_consume(used);
                BufferContents::Valid
            },
            Err(MessageError::TooShortForHeader) | Err(MessageError::TooShortForLength) => {
                BufferContents::Partial
            },
            Err(_) => BufferContents::Invalid
        }
    }

    fn buf_consume(&mut self, taken: usize) {
        if taken < self.used {
            /* Before:
             * +----------+----------+----------+
             * | taken    | pending  |xxxxxxxxxx|
             * +----------+----------+----------+
             * 0          ^ taken    ^ self.used
             *
             * After:
             * +----------+----------+----------+
             * | pending  |xxxxxxxxxxxxxxxxxxxxx|
             * +----------+----------+----------+
             * 0          ^ self.used
             */

            self.buf.copy_within(taken..self.used, 0);
            self.used = self.used - taken;
        } else if taken == self.used {
            self.used = 0;
        }
    }
}

#[cfg(test)]
mod tests {
    use super::MessageDeframer;
    use std::io;
    use crate::msgs;

    const FIRST_MESSAGE: &'static [u8] = include_bytes!("../testdata/deframer-test.1.bin");
    const SECOND_MESSAGE: &'static [u8] = include_bytes!("../testdata/deframer-test.2.bin");

    struct ByteRead<'a> {
        buf: &'a [u8],
        offs: usize,
    }

    impl<'a> ByteRead<'a> {
        fn new(bytes: &'a [u8]) -> ByteRead {
            ByteRead {
                buf: bytes,
                offs: 0,
            }
        }
    }

    impl<'a> io::Read for ByteRead<'a> {
        fn read(&mut self, buf: &mut [u8]) -> io::Result<usize> {
            let mut len = 0;

            while len < buf.len() && len < self.buf.len() - self.offs {
                buf[len] = self.buf[self.offs + len];
                len += 1;
            }

            self.offs += len;

            Ok(len)
        }
    }

    fn input_bytes(d: &mut MessageDeframer, bytes: &[u8]) -> io::Result<usize> {
        let mut rd = ByteRead::new(bytes);
        d.read(&mut rd)
    }

    fn input_bytes_concat(d: &mut MessageDeframer, bytes1: &[u8], bytes2: &[u8]) -> io::Result<usize> {
        let mut bytes = vec![0u8; bytes1.len() + bytes2.len()];
        bytes[..bytes1.len()].clone_from_slice(bytes1);
        bytes[bytes1.len()..].clone_from_slice(bytes2);
        let mut rd = ByteRead::new(&bytes);
        d.read(&mut rd)
    }

    struct ErrorRead {
        error: Option<io::Error>,
    }

    impl ErrorRead {
        fn new(error: io::Error) -> ErrorRead {
            ErrorRead { error: Some(error) }
        }
    }

    impl io::Read for ErrorRead {
        fn read(&mut self, buf: &mut [u8]) -> io::Result<usize> {
            for (i, b) in buf.iter_mut().enumerate() {
                *b = i as u8;
            }

            let error = self.error.take()
                .unwrap();
            Err(error)
        }
    }

    fn input_error(d: &mut MessageDeframer) {
        let error = io::Error::from(io::ErrorKind::TimedOut);
        let mut rd = ErrorRead::new(error);
        d.read(&mut rd)
            .expect_err("error not propagated");
    }

    fn input_whole_incremental(d: &mut MessageDeframer, bytes: &[u8]) {
        let frames_before = d.frames.len();

        for i in 0..bytes.len() {
            assert_len(1, input_bytes(d, &bytes[i..i + 1]));
            assert_eq!(d.has_pending(), true);

            if i < bytes.len() - 1 {
                assert_eq!(frames_before, d.frames.len());
            }
        }

        assert_eq!(frames_before + 1, d.frames.len());
    }

    fn assert_len(want: usize, got: io::Result<usize>) {
        if let Ok(gotval) = got {
            assert_eq!(gotval, want);
        } else {
            assert!(false, "read failed, expected {:?} bytes", want);
        }
    }

    fn pop_first(d: &mut MessageDeframer) {
        let mut m = d.frames.pop_front().unwrap();
        m.decode_payload();
        assert_eq!(m.typ, msgs::enums::ContentType::Handshake);
    }

    fn pop_second(d: &mut MessageDeframer) {
        let mut m = d.frames.pop_front().unwrap();
        m.decode_payload();
        assert_eq!(m.typ, msgs::enums::ContentType::Alert);
    }

    #[test]
    fn check_incremental() {
        let mut d = MessageDeframer::new();
        assert_eq!(d.has_pending(), false);
        input_whole_incremental(&mut d, FIRST_MESSAGE);
        assert_eq!(d.has_pending(), true);
        assert_eq!(1, d.frames.len());
        pop_first(&mut d);
        assert_eq!(d.has_pending(), false);
    }

    #[test]
    fn check_incremental_2() {
        let mut d = MessageDeframer::new();
        assert_eq!(d.has_pending(), false);
        input_whole_incremental(&mut d, FIRST_MESSAGE);
        assert_eq!(d.has_pending(), true);
        input_whole_incremental(&mut d, SECOND_MESSAGE);
        assert_eq!(d.has_pending(), true);
        assert_eq!(2, d.frames.len());
        pop_first(&mut d);
        assert_eq!(d.has_pending(), true);
        pop_second(&mut d);
        assert_eq!(d.has_pending(), false);
    }

    #[test]
    fn check_whole() {
        let mut d = MessageDeframer::new();
        assert_eq!(d.has_pending(), false);
        assert_len(FIRST_MESSAGE.len(), input_bytes(&mut d, FIRST_MESSAGE));
        assert_eq!(d.has_pending(), true);
        assert_eq!(d.frames.len(), 1);
        pop_first(&mut d);
        assert_eq!(d.has_pending(), false);
    }

    #[test]
    fn check_whole_2() {
        let mut d = MessageDeframer::new();
        assert_eq!(d.has_pending(), false);
        assert_len(FIRST_MESSAGE.len(), input_bytes(&mut d, FIRST_MESSAGE));
        assert_len(SECOND_MESSAGE.len(), input_bytes(&mut d, SECOND_MESSAGE));
        assert_eq!(d.frames.len(), 2);
        pop_first(&mut d);
        pop_second(&mut d);
        assert_eq!(d.has_pending(), false);
    }

    #[test]
    fn test_two_in_one_read() {
        let mut d = MessageDeframer::new();
        assert_eq!(d.has_pending(), false);
        assert_len(FIRST_MESSAGE.len() + SECOND_MESSAGE.len(),
                   input_bytes_concat(&mut d, FIRST_MESSAGE, SECOND_MESSAGE));
        assert_eq!(d.frames.len(), 2);
        pop_first(&mut d);
        pop_second(&mut d);
        assert_eq!(d.has_pending(), false);
    }

    #[test]
    fn test_two_in_one_read_shortest_first() {
        let mut d = MessageDeframer::new();
        assert_eq!(d.has_pending(), false);
        assert_len(FIRST_MESSAGE.len() + SECOND_MESSAGE.len(),
                   input_bytes_concat(&mut d, SECOND_MESSAGE, FIRST_MESSAGE));
        assert_eq!(d.frames.len(), 2);
        pop_second(&mut d);
        pop_first(&mut d);
        assert_eq!(d.has_pending(), false);
    }

    #[test]
    fn test_incremental_with_nonfatal_read_error() {
        let mut d = MessageDeframer::new();
        assert_len(3, input_bytes(&mut d, &FIRST_MESSAGE[..3]));
        input_error(&mut d);
        assert_len(FIRST_MESSAGE.len() - 3,
                   input_bytes(&mut d, &FIRST_MESSAGE[3..]));
        assert_eq!(d.frames.len(), 1);
        pop_first(&mut d);
        assert_eq!(d.has_pending(), false);
    }
}