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

// Copyright (c) 2015-2017 Contributors as noted in the AUTHORS file.
//
// Licensed under the Apache License, Version 2.0 <LICENSE-APACHE or http://www.apache.org/licenses/LICENSE-2.0>
// or the MIT license <LICENSE-MIT or http://opensource.org/licenses/MIT>, at your option.
// This file may not be copied, modified, or distributed except according to those terms.


use std::sync::mpsc;
use std::io;

use super::*;
use reactor;
use core::DeviceId;
use core::device::{Request, Reply};
use io_error::*;

/// A device to forward messages between sockets, working like a message broker.
/// It can be used to build complex network topologies.
pub trait Device : Send {
    /// This function loops until it hits an error.
    /// To break the loop and make the `run` function exit, 
    /// drop the session that created the device.
    fn run(self: Box<Self>) -> io::Result<()>;
}

/*****************************************************************************/
/*                                                                           */
/* RELAY DEVICE                                                              */
/*                                                                           */
/*****************************************************************************/

#[doc(hidden)]
pub struct Relay {
    socket: Option<socket::Socket>
}

impl Relay {
    pub fn new(s: socket::Socket) -> Relay {
        Relay { socket: Some(s) }
    }
}

impl Device for Relay {
    fn run(mut self: Box<Self>) -> io::Result<()> {
        let mut socket = self.socket.take().unwrap();
        loop {
            try!(socket.recv_msg().and_then(|msg| socket.send_msg(msg)));
        }
    }
}

/*****************************************************************************/
/*                                                                           */
/* BRIDGE DEVICE                                                             */
/*                                                                           */
/*****************************************************************************/

#[doc(hidden)]
pub type ReplyReceiver = mpsc::Receiver<Reply>;

#[doc(hidden)]
pub struct RequestSender {
    req_tx: EventLoopRequestSender,
    device_id: DeviceId
}

impl RequestSender {
    pub fn new(tx: EventLoopRequestSender, id: DeviceId) -> RequestSender {
        RequestSender {
            req_tx: tx,
            device_id: id
        }
    }
    fn send(&self, req: Request) -> io::Result<()> {
        self.req_tx.send(reactor::Request::Device(self.device_id, req)).map_err(from_send_error)
    }
}

#[doc(hidden)]
pub struct Bridge {
    request_sender: RequestSender,
    reply_receiver: ReplyReceiver,
    left: Option<socket::Socket>,
    right: Option<socket::Socket>
}

impl Bridge {
    #[doc(hidden)]
    pub fn new(
        request_tx: RequestSender, 
        reply_rx: ReplyReceiver,
        left: socket::Socket,
        right: socket::Socket) -> Bridge {

        Bridge {
            request_sender: request_tx,
            reply_receiver: reply_rx,
            left: Some(left),
            right: Some(right)
        }
    }

    fn execute_request(&self, request: Request) -> io::Result<Reply> {
        self.send_request(request).and_then(|_| self.recv_reply())
    }

    fn send_request(&self, request: Request) -> io::Result<()> {
        self.request_sender.send(request)
    }

    fn recv_reply(&self) -> io::Result<Reply> {
        self.reply_receiver.receive()
    }

    fn run_once(&mut self, left: &mut socket::Socket, right: &mut socket::Socket) -> io::Result<()> {
        if let Reply::Check(l, r) = try!(self.execute_request(Request::Check)) {
            match (l, r) {
                (true, true) => exchange_msg(left, right),
                (true, _)    => forward_msg(left, right),
                (_, true)    => forward_msg(right, left),
                (_, _)       => Ok(())
            }
        } else {
            Err(other_io_error("unexpected reply"))
        }

    }
}

impl Device for Bridge {
    fn run(mut self: Box<Self>) -> io::Result<()> {
        let mut left = self.left.take().unwrap();
        let mut right = self.right.take().unwrap();

        loop {
            try!(self.run_once(&mut left, &mut right));
        }
    }
}

fn forward_msg(from: &mut socket::Socket, to: &mut socket::Socket) -> io::Result<()> {
    from.recv_msg().and_then(|msg| to.send_msg(msg))
}

fn exchange_msg(left: &mut socket::Socket, right: &mut socket::Socket) -> io::Result<()> {
    let from_left = try!(left.recv_msg());
    let from_right = try!(right.recv_msg());

    right.send_msg(from_left).and_then(|_| left.send_msg(from_right))
}

impl Drop for Bridge {
    fn drop(&mut self) {
        let _ = self.send_request(Request::Close);
        let _ = self.recv_reply();
    }
}