bip_peer 0.5.0

Communication with bittorrent peers via peer wire protocol
Documentation 
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

#![allow(deprecated)]

use std::io;

use manager::builder::PeerManagerBuilder;
use manager::peer_info::PeerInfo;
use manager::future::{PersistentError, PersistentStream, RecurringTimeoutStream, RecurringTimeoutError};
use manager::{IPeerManagerMessage, OPeerManagerMessage, ManagedMessage};

use tokio_core::reactor::Handle;
use tokio_timer::{Timer};
use futures::sync::mpsc::{self, Sender};
use futures::stream::{Stream, MergedItem};
use futures::sink::Sink;
use futures::future::{self, Loop, Future};

// Separated from MergedError to 
enum PeerError {
    // We need to send a heartbeat (no messages sent from manager for a while)
    ManagerHeartbeatInterval,
    // Manager error (or expected shutdown)
    ManagerDisconnect,
    // Peer errors
    PeerDisconnect,
    PeerError(io::Error),
    PeerNoHeartbeat
}

enum MergedError<A, B, C> {
    Peer(PeerError),
    // Fake error types (used to stash future "futures" into an error type to be
    // executed in a different future transformation, so we dont have to box them)
    StageOne(A),
    StageTwo(B),
    StageThree(C)
}

//----------------------------------------------------------------------------//

pub fn run_peer<P>(peer: P, info: PeerInfo, o_send: Sender<OPeerManagerMessage<P::Item>>,
                   timer: Timer, builder: &PeerManagerBuilder, handle: &Handle) -> Sender<IPeerManagerMessage<P>>
    where P: Stream<Error=io::Error> + Sink<SinkError=io::Error> + 'static,
          P::SinkItem: ManagedMessage,
          P::Item:     ManagedMessage {
    let (m_send, m_recv) = mpsc::channel(builder.sink_buffer_capacity());
    let (p_send, p_recv) = peer.split();

    // Build a stream that will timeout if no message is sent for heartbeat_timeout and teardown (dont preserve) the underlying stream
    let p_stream = timer.timeout_stream(PersistentStream::new(p_recv), builder.heartbeat_timeout())
        .map_err(|error| {
            match error {
                PersistentError::Disconnect   => PeerError::PeerDisconnect,
                PersistentError::Timeout      => PeerError::PeerNoHeartbeat,
                PersistentError::IoError(err) => PeerError::PeerError(err)
            }   
        });
    // Build a stream that will notify us of no message is sent for heartbeat_interval and done teartdown (preserve) the underlying stream
    let m_stream = RecurringTimeoutStream::new(m_recv, timer, builder.heartbeat_interval())
        .map_err(|error| {
            match error {
                RecurringTimeoutError::Disconnect => PeerError::ManagerDisconnect,
                RecurringTimeoutError::Timeout    => PeerError::ManagerHeartbeatInterval
            }  
        });

    let merged_stream = m_stream.merge(p_stream);

    handle.spawn(o_send.send(OPeerManagerMessage::PeerAdded(info)).map_err(|_| ()).and_then(move |o_send| {
        future::loop_fn((merged_stream, o_send, p_send, info), |(merged_stream, o_send, p_send, info)| {
            // Our return tuple takes the form (merged_stream, Option<Send Message>, Option<Recv Message>, Option<Send To Manager Message>, is_good) where each stage (A, B, C),
            // will execute one of those options (if present), since each future transform can only execute a single future and we have 2^3 possible combintations
            // (Some or None = 2)^(3 Options = 3)
            merged_stream.into_future()
                .then(move |result| {
                    let result = match result {
                        Ok((Some(MergedItem::First(
                            IPeerManagerMessage::SendMessage(p_info, mid, p_message))),
                            merged_stream
                        ))                                                              => Ok((merged_stream, Some(p_message), None, Some(OPeerManagerMessage::SentMessage(p_info, mid)), true)),
                        Ok((Some(MergedItem::First(
                            IPeerManagerMessage::RemovePeer(p_info))),
                            merged_stream
                        ))                                                              => Ok((merged_stream, None, None, Some(OPeerManagerMessage::PeerRemoved(p_info)), false)),
                        Ok((Some(MergedItem::Second(
                            peer_message)),
                            merged_stream
                        ))                                                              => Ok((merged_stream, None, Some(peer_message), None, true)),
                        Ok((Some(MergedItem::Both(
                            IPeerManagerMessage::SendMessage(p_info, mid, p_message),
                            peer_message)),
                            merged_stream
                        ))                                                               => Ok((merged_stream, Some(p_message), Some(peer_message), Some(OPeerManagerMessage::SentMessage(p_info, mid)), true)),
                        Ok((Some(MergedItem::Both(
                            IPeerManagerMessage::RemovePeer(p_info),
                            peer_message)),
                            merged_stream
                        ))                                                               => Ok((merged_stream, None, Some(peer_message), Some(OPeerManagerMessage::PeerRemoved(p_info)), false)),
                        Ok((Some(_), _))                                                 => panic!("bip_peer: Peer Future Received Invalid Message From Peer Manager"),
                        Err((PeerError::ManagerHeartbeatInterval, merged_stream))        => Ok((merged_stream, Some(P::SinkItem::keep_alive()), None, None, true)),
                        // In this case, the manager and peer probably both disconnected at the same time? Treat as a manager disconnect.
                        Ok((None, _))                                                    => Err(MergedError::Peer(PeerError::ManagerDisconnect)),
                        Err((PeerError::ManagerDisconnect, _))                           => Err(MergedError::Peer(PeerError::ManagerDisconnect)),
                        Err((PeerError::PeerDisconnect, merged_stream))                  => Ok((merged_stream, None, None, Some(OPeerManagerMessage::PeerDisconnect(info)), false)),
                        Err((PeerError::PeerError(err), merged_stream))                  => Ok((merged_stream, None, None, Some(OPeerManagerMessage::PeerError(info, err)), false)),
                        Err((PeerError::PeerNoHeartbeat, merged_stream))                 => Ok((merged_stream, None, None, Some(OPeerManagerMessage::PeerDisconnect(info)), false))
                    };

                    match result {
                        Ok((merged_stream, opt_send, opt_recv, opt_ack, is_good)) => {
                            if let Some(send) = opt_send {
                                Ok(p_send.send(send)
                                    .map_err(|_| MergedError::Peer(PeerError::PeerDisconnect))
                                    .and_then(move |p_send| Err(MergedError::StageOne((merged_stream, o_send, p_send, info, opt_recv, opt_ack, is_good)))))
                            } else {
                                Err(MergedError::StageOne((merged_stream, o_send, p_send, info, opt_recv, opt_ack, is_good)))
                            }
                        },
                        Err(err) => Err(err)
                    }
                })
                .flatten()
                .or_else(|error| {
                    match error {
                        MergedError::StageOne((merged_stream, o_send, p_send, info, opt_recv, opt_ack, is_good)) => {
                            if let Some(recv) = opt_recv {
                                if !recv.is_keep_alive() {
                                    return Ok(o_send.send(OPeerManagerMessage::ReceivedMessage(info, recv))
                                                    .map_err(|_| MergedError::Peer(PeerError::ManagerDisconnect))
                                                    .and_then(move |o_send| Err(MergedError::StageTwo((merged_stream, o_send, p_send, info, opt_ack, is_good)))))
                                }
                            }

                            // Either we had no recv message (from remote), or it was a keep alive message, which we dont propagate
                            Err(MergedError::StageTwo((merged_stream, o_send, p_send, info, opt_ack, is_good)))
                        },
                        err => Err(err)
                    }
                })
                .flatten()
                .or_else(|error| {
                    match error {
                        MergedError::StageTwo((merged_stream, o_send, p_send, info, opt_ack, is_good)) => {
                            if let Some(ack) = opt_ack {
                                Ok(o_send.send(ack)
                                    .map_err(|_| MergedError::Peer(PeerError::ManagerDisconnect))
                                    .and_then(move |o_send| Err(MergedError::StageThree((merged_stream, o_send, p_send, info, is_good)))))
                            } else {
                                Err(MergedError::StageThree((merged_stream, o_send, p_send, info, is_good)))
                            }
                        },
                        err => Err(err)
                    }
                })
                .flatten()
                .or_else(|error| {
                    match error {
                        MergedError::StageThree((merged_stream, o_send, p_send, info, is_good)) => {
                            // Connection is good if no errors occurred (we do this so we can use the same plumbing)
                            // for sending "acks" back to our manager when an error occurrs, we just have None, None,
                            // Some, false when we want to send an error message to the manager, but terminate the connection.
                            if is_good {
                                Ok(Loop::Continue((merged_stream, o_send, p_send, info)))
                            } else {
                                Ok(Loop::Break(()))
                            }
                        },
                        _ => Ok(Loop::Break(()))
                    }
                })
        })
    }));

    m_send
}