tari_comms 6.2.0-pre.0

//  Copyright 2021, The Tari Project
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use std::time::Duration;

use tari_test_utils::unpack_enum;
use tokio::{task, time};

use crate::{
    framing,
    memsocket::MemorySocket,
    protocol::rpc::{
        Handshake,
        RPC_MAX_FRAME_SIZE,
        error::HandshakeRejectReason,
        handshake::{MAX_HANDSHAKE_FRAME_SIZE, RpcHandshakeError, SUPPORTED_RPC_VERSIONS},
    },
};

/// A frame one byte over the handshake limit: a valid `RpcSession`/`RpcSessionReply` padded with an unknown bytes field
fn oversized_handshake_frame() -> bytes::Bytes {
    let mut frame = Vec::new();
    prost::encoding::encode_key(15, prost::encoding::WireType::LengthDelimited, &mut frame);
    prost::encoding::encode_varint((MAX_HANDSHAKE_FRAME_SIZE - 2) as u64, &mut frame);
    frame.resize(MAX_HANDSHAKE_FRAME_SIZE + 1, 0);
    frame.into()
}

#[tokio::test]
async fn the_server_rejects_an_oversized_handshake_frame() {
    use futures::SinkExt;

    let (client, server) = MemorySocket::new_pair();
    let mut client_framed = framing::canonical(client, 4096);
    client_framed.send(oversized_handshake_frame()).await.unwrap();

    let mut server_framed = framing::canonical(server, 4096);
    let err = Handshake::new(&mut server_framed)
        .perform_server_handshake()
        .await
        .unwrap_err();
    unpack_enum!(RpcHandshakeError::FrameTooLarge { max } = err);
    assert_eq!(max, MAX_HANDSHAKE_FRAME_SIZE);
    // The codec's own limit is restored once the handshake frame has been read
    assert_eq!(server_framed.codec().max_frame_length(), 4096);
}

/// Only the length prefix of a frame declaring 8 MiB is sent. On either side, the codec rejects it from the declared
/// length alone, before reserving a buffer for it or waiting for the body (without the handshake limit it would wait
/// for 8 MiB), and the codec's own limit is restored afterwards.
#[tokio::test]
async fn a_handshake_frame_declaring_more_than_the_limit_is_rejected_by_the_codec() {
    use tokio::io::AsyncWriteExt;

    let declared = u32::try_from(RPC_MAX_FRAME_SIZE).unwrap();
    for server_side in [true, false] {
        let (mut peer, local) = MemorySocket::new_pair();
        // The codec's length prefix (4 bytes, big-endian) and nothing else. `peer` stays open, so this is not EOF.
        peer.write_all(&declared.to_be_bytes()).await.unwrap();

        let mut framed = framing::canonical(local, RPC_MAX_FRAME_SIZE);
        let result = time::timeout(Duration::from_secs(5), async {
            let mut handshake = Handshake::new(&mut framed);
            if server_side {
                handshake.perform_server_handshake().await.map(|_| ())
            } else {
                handshake.perform_client_handshake().await
            }
        })
        .await
        .expect("the codec did not reject the frame from its declared length");
        unpack_enum!(RpcHandshakeError::FrameTooLarge { max } = result.unwrap_err());
        assert_eq!(max, MAX_HANDSHAKE_FRAME_SIZE);
        assert_eq!(framed.codec().max_frame_length(), RPC_MAX_FRAME_SIZE);
        drop(peer);
    }
}

#[tokio::test]
async fn the_client_rejects_an_oversized_handshake_reply() {
    use futures::SinkExt;

    let (client, server) = MemorySocket::new_pair();
    let mut server_framed = framing::canonical(server, 4096);
    server_framed.send(oversized_handshake_frame()).await.unwrap();

    let mut client_framed = framing::canonical(client, 4096);
    let err = Handshake::new(&mut client_framed)
        .perform_client_handshake()
        .await
        .unwrap_err();
    unpack_enum!(RpcHandshakeError::FrameTooLarge { .. } = err);
    // An honest server never sends an oversized reply, so the client blames the server for it
    assert!(crate::protocol::rpc::RpcError::from(err).is_caused_by_server());
}

#[tokio::test]
async fn it_performs_the_handshake() {
    let (client, server) = MemorySocket::new_pair();

    let handshake_result = task::spawn(async move {
        let mut server_framed = framing::canonical(server, 1024);
        let mut handshake_server = Handshake::new(&mut server_framed);
        handshake_server.perform_server_handshake().await
    });

    let mut client_framed = framing::canonical(client, 1024);
    let mut handshake_client = Handshake::new(&mut client_framed);

    handshake_client.perform_client_handshake().await.unwrap();
    let v = handshake_result.await.unwrap().unwrap();
    assert!(SUPPORTED_RPC_VERSIONS.contains(&v));
}

#[tokio::test]
async fn it_rejects_the_handshake() {
    let (client, server) = MemorySocket::new_pair();

    let mut client_framed = framing::canonical(client, 1024);
    let mut handshake_client = Handshake::new(&mut client_framed);

    let mut server_framed = framing::canonical(server, 1024);
    let mut handshake_server = Handshake::new(&mut server_framed);
    handshake_server
        .reject_with_reason(HandshakeRejectReason::NoServerSessionsAvailable("some reason"))
        .await
        .unwrap();

    let err = handshake_client.perform_client_handshake().await.unwrap_err();
    unpack_enum!(RpcHandshakeError::Rejected(reason) = err);
    unpack_enum!(HandshakeRejectReason::NoServerSessionsAvailable("session limit reached") = reason);
}