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

use std::io;
use tokio_io::codec::{Decoder, Encoder};

use bytes::{BufMut, BytesMut};
use futures::{Async, AsyncSink, Poll, Sink, StartSend, Stream};
use socket::SocketAddr;
use socket::TokioSocket;

pub struct NetlinkFramed<C> {
    socket: TokioSocket,
    codec: C,
    reader: BytesMut,
    writer: BytesMut,
    out_addr: SocketAddr,
    in_addr: SocketAddr,
    flushed: bool,
}

impl<C: Decoder> Stream for NetlinkFramed<C> {
    type Item = (C::Item, SocketAddr);
    type Error = C::Error;

    fn poll(&mut self) -> Poll<Option<(Self::Item)>, Self::Error> {
        if let Some(item) = self.codec.decode(&mut self.reader)? {
            return Ok(Async::Ready(Some((item, self.in_addr))));
        }

        // There should not be byte left in the buffer. Message oriented protocols guarantee that
        // complete datagrams are being delivered.
        if !self.reader.is_empty() {
            error!(
                "{} bytes left in the buffer that could not be decoded",
                self.reader.len()
            );
        }

        self.reader.clear();
        self.reader.reserve(INITIAL_READER_CAPACITY);

        self.in_addr = unsafe {
            // Read into the buffer without having to initialize the memory.
            let (n, addr) = try_ready!(self.socket.poll_recv_from(self.reader.bytes_mut()));
            self.reader.advance_mut(n);
            addr
        };

        if let Some(item) = self.codec.decode(&mut self.reader)? {
            return Ok(Async::Ready(Some((item, self.in_addr))));
        } else {
            // FIXME: I think that is impossible, unless 0 bytes were read.
            //
            // But then we would have returned NotReady I think?
            //
            // Or does this means EOF? But if it's EOF, we should already have return an io::Err
            // in try_ready! no?
            panic!("I'm not sure how to handle this")
        }
    }
}

impl<C: Encoder> Sink for NetlinkFramed<C> {
    type SinkItem = (C::Item, SocketAddr);
    type SinkError = C::Error;

    fn start_send(&mut self, item: Self::SinkItem) -> StartSend<Self::SinkItem, Self::SinkError> {
        trace!("sending frame");

        if !self.flushed {
            trace!("flushing the sink, before sending the frame");
            match self.poll_complete()? {
                Async::Ready(()) => trace!("sink flushed"),
                Async::NotReady => {
                    trace!("could not flush the sink entirely");
                    return Ok(AsyncSink::NotReady(item));
                }
            }
        }

        let (frame, out_addr) = item;
        self.codec.encode(frame, &mut self.writer)?;
        self.out_addr = out_addr;
        self.flushed = false;
        trace!("frame encoded; length={}", self.writer.len());

        Ok(AsyncSink::Ready)
    }

    fn poll_complete(&mut self) -> Poll<(), C::Error> {
        if self.flushed {
            return Ok(Async::Ready(()));
        }

        trace!("flushing frame; length={}", self.writer.len());
        let n = try_ready!(self.socket.poll_send_to(&self.writer, &self.out_addr));
        trace!("written {}", n);

        let wrote_all = n == self.writer.len();
        self.writer.clear();
        self.flushed = true;

        if wrote_all {
            Ok(Async::Ready(()))
        } else {
            Err(io::Error::new(
                io::ErrorKind::Other,
                "failed to write entire datagram to socket",
            ).into())
        }
    }

    fn close(&mut self) -> Poll<(), C::Error> {
        try_ready!(self.poll_complete());
        Ok(().into())
    }
}

const INITIAL_READER_CAPACITY: usize = 64 * 1024;
const INITIAL_WRITER_CAPACITY: usize = 8 * 1024;

impl<C> NetlinkFramed<C> {
    /// Create a new `NetlinkFramed` backed by the given socket and codec.
    ///
    /// See struct level documentation for more details.
    pub fn new(socket: TokioSocket, codec: C) -> NetlinkFramed<C> {
        NetlinkFramed {
            socket,
            codec,
            out_addr: SocketAddr::new(0, 0),
            in_addr: SocketAddr::new(0, 0),
            reader: BytesMut::with_capacity(INITIAL_READER_CAPACITY),
            writer: BytesMut::with_capacity(INITIAL_WRITER_CAPACITY),
            flushed: true,
        }
    }

    /// Returns a reference to the underlying I/O stream wrapped by `Framed`.
    ///
    /// # Note
    ///
    /// Care should be taken to not tamper with the underlying stream of data
    /// coming in as it may corrupt the stream of frames otherwise being worked
    /// with.
    pub fn get_ref(&self) -> &TokioSocket {
        &self.socket
    }

    /// Returns a mutable reference to the underlying I/O stream wrapped by
    /// `Framed`.
    ///
    /// # Note
    ///
    /// Care should be taken to not tamper with the underlying stream of data
    /// coming in as it may corrupt the stream of frames otherwise being worked
    /// with.
    pub fn get_mut(&mut self) -> &mut TokioSocket {
        &mut self.socket
    }

    /// Consumes the `Framed`, returning its underlying I/O stream.
    pub fn into_inner(self) -> TokioSocket {
        self.socket
    }
}