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
/* This file is part of DarkFi (https://dark.fi)
 *
 * Copyright (C) 2020-2024 Dyne.org foundation
 *
 * This program is free software: you can redistribute it and/or modify
 * it under the terms of the GNU Affero General Public License as
 * published by the Free Software Foundation, either version 3 of the
 * License, or (at your option) any later version.
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU Affero General Public License for more details.
 *
 * You should have received a copy of the GNU Affero General Public License
 * along with this program.  If not, see <https://www.gnu.org/licenses/>.
 */

//! Inbound connections session. Manages the creation of inbound sessions.
//! Used to create an inbound session and start and stop the session.
//!
//! Class consists of 3 pointers: a weak pointer to the p2p parent class,
//! an acceptor pointer, and a stoppable task pointer. Using a weak pointer
//! to P2P allows us to avoid circular dependencies.

use std::sync::{Arc, Weak};

use async_trait::async_trait;
use log::{debug, error, info, warn};
use smol::{lock::Mutex, Executor};
use url::Url;

use super::{
    super::{
        acceptor::{Acceptor, AcceptorPtr},
        channel::ChannelPtr,
        dnet::{self, dnetev, DnetEvent},
        p2p::{P2p, P2pPtr},
    },
    Session, SessionBitFlag, SESSION_INBOUND,
};
use crate::{
    system::{StoppableTask, StoppableTaskPtr, Subscription},
    Error, Result,
};

pub type InboundSessionPtr = Arc<InboundSession>;

/// Defines inbound connections session
pub struct InboundSession {
    pub(in crate::net) p2p: Weak<P2p>,
    acceptors: Mutex<Vec<AcceptorPtr>>,
    accept_tasks: Mutex<Vec<StoppableTaskPtr>>,
}

impl InboundSession {
    /// Create a new inbound session
    pub fn new(p2p: Weak<P2p>) -> InboundSessionPtr {
        Arc::new(Self {
            p2p,
            acceptors: Mutex::new(Vec::new()),
            accept_tasks: Mutex::new(Vec::new()),
        })
    }

    /// Starts the inbound session. Begins by accepting connections and fails
    /// if the addresses are not configured. Then runs the channel subscription
    /// loop.
    pub async fn start(self: Arc<Self>) -> Result<()> {
        let inbound_addrs = self.p2p().settings().read().await.inbound_addrs.clone();

        if inbound_addrs.is_empty() {
            info!(target: "net::inbound_session", "[P2P] Not configured for inbound connections.");
            return Ok(())
        }

        let ex = self.p2p().executor();

        // Activate mutex lock on accept tasks.
        let mut accept_tasks = self.accept_tasks.lock().await;

        for (index, accept_addr) in inbound_addrs.iter().enumerate() {
            // First initialize an Acceptor and its Subscriber.
            let parent = Arc::downgrade(&self);
            let acceptor = Acceptor::new(parent);

            // Now start the Subscriber. The Subscriber will return a Channel once it has been
            // prepared by the Acceptor.
            let channel_sub = acceptor.clone().subscribe().await;

            // Then start listening for a Channel returned by the Subscriber. Call setup_channel()
            // to register the Channel when it has been received.
            let task = StoppableTask::new();
            task.clone().start(
                self.clone().channel_sub_loop(channel_sub, index, ex.clone()),
                // Ignore stop handler
                |_| async {},
                Error::NetworkServiceStopped,
                ex.clone(),
            );

            accept_tasks.push(task);

            // Finally, run the Acceptor to start accepting inbound connections. Only when
            // the Subscriber has been set up can we safely do this.
            self.clone()
                .start_accept_session(index, accept_addr.clone(), acceptor, ex.clone())
                .await?;
        }

        Ok(())
    }

    /// Stops the inbound session.
    pub async fn stop(&self) {
        if self.p2p().settings().read().await.inbound_addrs.is_empty() {
            info!(target: "net::inbound_session", "[P2P] Stopping inbound session.");
            return
        }

        let acceptors = &*self.acceptors.lock().await;
        for acceptor in acceptors {
            acceptor.stop().await;
        }

        let accept_tasks = &*self.accept_tasks.lock().await;
        for accept_task in accept_tasks {
            accept_task.stop().await;
        }
    }

    /// Start accepting connections for inbound session.
    async fn start_accept_session(
        self: Arc<Self>,
        index: usize,
        accept_addr: Url,
        acceptor: AcceptorPtr,
        ex: Arc<Executor<'_>>,
    ) -> Result<()> {
        info!(target: "net::inbound_session", "[P2P] Starting Inbound session #{} on {}", index, accept_addr);
        // Start listener
        let result = acceptor.clone().start(accept_addr, ex).await;
        if let Err(e) = &result {
            error!(target: "net::inbound_session", "[P2P] Error starting listener #{}: {}", index, e);
            acceptor.stop().await;
        } else {
            self.acceptors.lock().await.push(acceptor);
        }

        result
    }

    /// Wait for all new channels created by the acceptor and call setup_channel() on them.
    async fn channel_sub_loop(
        self: Arc<Self>,
        channel_sub: Subscription<Result<ChannelPtr>>,
        index: usize,
        ex: Arc<Executor<'_>>,
    ) -> Result<()> {
        loop {
            let channel = channel_sub.receive().await?;

            // Spawn a detached task to process the channel.
            // This will just perform the channel setup then exit.
            ex.spawn(self.clone().setup_channel(index, channel, ex.clone())).detach();
        }
    }

    /// Registers the channel. First performs a network handshake and starts the channel.
    /// Then starts sending keep-alive and address messages across the channel.
    async fn setup_channel(
        self: Arc<Self>,
        index: usize,
        channel: ChannelPtr,
        ex: Arc<Executor<'_>>,
    ) {
        info!(
             target: "net::inbound_session::setup_channel",
             "[P2P] Connected Inbound #{} [{}]", index, channel.address(),
        );

        dnetev!(self, InboundConnected, {
            addr: channel.info.connect_addr.clone(),
            channel_id: channel.info.id,
        });

        let stop_sub = channel.subscribe_stop().await;

        match self.register_channel(channel.clone(), ex.clone()).await {
            Ok(()) => {
                if let Ok(stop_sub) = stop_sub {
                    // Wait for a stop signal, then cleanup.
                    stop_sub.receive().await;

                    debug!(
                        target: "net::inbound_session::setup_channel()",
                        "Received stop_sub, channel removed from P2P",
                    );
                }
            }
            Err(e) => {
                warn!(
                    target: "net::inbound_session::setup_channel()",
                    "Channel setup failed! Err={}", e
                );
            }
        }

        dnetev!(self, InboundDisconnected, {
            addr: channel.info.connect_addr.clone(),
            channel_id: channel.info.id,
        });
    }
}

#[async_trait]
impl Session for InboundSession {
    fn p2p(&self) -> P2pPtr {
        self.p2p.upgrade().unwrap()
    }

    fn type_id(&self) -> SessionBitFlag {
        SESSION_INBOUND
    }
}