manul 0.2.1

Generic library for round-based protocols
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

//! `tokio`-specific development utilities.

use alloc::{collections::BTreeMap, format, vec::Vec};

use rand::Rng;
use rand_core::CryptoRngCore;
use signature::Keypair;
use tokio::sync::mpsc;

use super::run_sync::ExecutionResult;
use crate::{
    protocol::{EntryPoint, Protocol},
    session::{
        tokio::{par_run_session, run_session, MessageIn, MessageOut},
        LocalError, Session, SessionId, SessionParameters,
    },
};

async fn message_dispatcher<SP>(
    rng: impl CryptoRngCore,
    txs: BTreeMap<SP::Verifier, mpsc::Sender<MessageIn<SP>>>,
    rx: mpsc::Receiver<MessageOut<SP>>,
) -> Result<(), LocalError>
where
    SP: SessionParameters,
{
    let mut rng = rng;

    let mut rx = rx;
    let mut messages = Vec::<MessageOut<SP>>::new();
    loop {
        let msg = match rx.recv().await {
            Some(msg) => msg,
            None => return Ok(()),
        };
        messages.push(msg);

        while let Ok(msg) = rx.try_recv() {
            messages.push(msg)
        }

        while !messages.is_empty() {
            // Pull a random message from the list,
            // to increase the chances that they are delivered out of order.
            let message_idx = rng.gen_range(0..messages.len());
            let outgoing = messages.swap_remove(message_idx);

            txs.get(&outgoing.to)
                .ok_or_else(|| {
                    LocalError::new(format!(
                        "Destination ({:?}) is missing in the map of channels",
                        outgoing.to
                    ))
                })?
                .send(MessageIn {
                    from: outgoing.from,
                    message: outgoing.message,
                })
                .await
                .map_err(|err| LocalError::new(format!("Could not sent an outgoing message: {err}")))?;

            // Give up execution so that the tasks could process messages.
            tokio::time::sleep(tokio::time::Duration::from_millis(0)).await;

            if let Ok(msg) = rx.try_recv() {
                messages.push(msg);
            };
        }
    }
}

/// Execute sessions for multiple nodes concurrently within a `tokio` runtime,
/// given a vector of the signer and the entry point as a tuple for each node.
///
/// If `offload_processing` is `true`, message creation and verification will be launched in separate tasks.
pub async fn run_async<EP, SP>(
    rng: &mut (impl 'static + CryptoRngCore + Clone + Send),
    entry_points: Vec<(SP::Signer, EP)>,
    offload_processing: bool,
) -> Result<ExecutionResult<EP::Protocol, SP>, LocalError>
where
    EP: EntryPoint<SP::Verifier>,
    SP: SessionParameters,
    SP::Signer: Send + Sync,
    <EP::Protocol as Protocol<SP::Verifier>>::ProtocolError: Send + Sync,
    <EP::Protocol as Protocol<SP::Verifier>>::Result: Send,
{
    let num_parties = entry_points.len();
    let session_id = SessionId::random::<SP>(rng);

    let (dispatcher_tx, dispatcher_rx) = mpsc::channel::<MessageOut<SP>>(100);

    let channels = (0..num_parties).map(|_| mpsc::channel::<MessageIn<SP>>(100));
    let (txs, rxs): (Vec<_>, Vec<_>) = channels.unzip();
    let tx_map = entry_points
        .iter()
        .map(|(signer, _entry_point)| signer.verifying_key())
        .zip(txs.into_iter())
        .collect();

    let dispatcher_task = message_dispatcher(rng.clone(), tx_map, dispatcher_rx);
    let dispatcher = tokio::spawn(dispatcher_task);

    let handles = rxs
        .into_iter()
        .zip(entry_points.into_iter())
        .map(|(mut rx, (signer, entry_point))| {
            let tx = dispatcher_tx.clone();
            let mut rng = rng.clone();

            let session = Session::<_, SP>::new(&mut rng, session_id.clone(), signer, entry_point)?;
            let id = session.verifier().clone();

            let node_task = async move {
                if offload_processing {
                    par_run_session(&mut rng, &tx, &mut rx, session).await
                } else {
                    run_session(&mut rng, &tx, &mut rx, session).await
                }
            };
            Ok((id, tokio::spawn(node_task)))
        })
        .collect::<Result<BTreeMap<_, _>, _>>()?;

    // Drop the last copy of the dispatcher's incoming channel so that it can finish.
    drop(dispatcher_tx);

    let mut reports = BTreeMap::new();
    for (id, handle) in handles {
        reports.insert(
            id.clone(),
            handle
                .await
                .map_err(|err| LocalError::new(format!("Could not join the task of {id:?}: {err}")))??,
        );
    }

    dispatcher
        .await
        .map_err(|err| LocalError::new(format!("Could not join the message dispatcher task: {err}")))??;

    Ok(ExecutionResult { reports })
}