lernie 0.1.16

//! One channel against something that speaks the protocol: a real listener, a
//! real mTLS handshake, a real version preface, real frames.

use super::hello::PROTOCOL;
use super::material::{CHAIN, KEY, Material, read_dir};
use super::{Channel, server_name};
use crate::test_support::engine::Engine;
use crate::test_support::{Scratch, mint};
use serde_json::{Value, json};

/// A scratch box with an engine standing at the far end, answering the n-th
/// dial with the n-th entry of `script`.
fn wired(protocol: u32, script: Vec<Vec<Value>>) -> (Scratch, Engine, Material) {
    let scratch = Scratch::new();
    mint::material(scratch.path());
    let engine = Engine::start(scratch.path(), protocol, script);
    let held = read_dir(scratch.path())
        .expect("readable")
        .expect("provisioned");
    (scratch, engine, held)
}

/// An answer of one frame: the ordinary shape.
fn answered() -> Value {
    json!({"ok": true, "kind": "workspaces", "rows": []})
}

/// **Nothing is dialled when a channel opens**, and what it answers about
/// itself is read off the address rather than off any engine.
#[test]
fn opening_a_channel_dials_nothing_and_names_the_address() {
    let scratch = Scratch::new();
    let held = mint::provisioned(scratch.path(), "engine.example:9000");
    let channel = Channel::open(&held).expect("opened");
    assert_eq!(channel.address(), "engine.example:9000");
}

/// One ask: this end's preface and its request go out in the same breath, the
/// engine is handed exactly those two frames, and the answer comes back as the
/// value it sent.
#[test]
fn one_ask_states_a_version_carries_the_request_and_answers_the_reply() {
    let (_scratch, engine, held) = wired(PROTOCOL, vec![vec![answered()]]);
    let channel = Channel::open(&held).expect("opened");
    let request = json!({"op": "workspaces"});
    assert_eq!(channel.ask(&request), Ok(vec![answered()]));
    assert_eq!(
        engine.heard(),
        vec![json!({ "protocol": PROTOCOL }), request],
        "the preface rides beside the gesture, never inside it"
    );
}

/// **The streaming form is not a second form.** An answer of several frames
/// reads back through the same call, in order, and the terminator ends it.
#[test]
fn an_answer_of_many_frames_reads_back_through_the_same_ask() {
    let rows = vec![json!({"n": 1}), json!({"n": 2}), json!({"n": 3})];
    let (_scratch, _engine, held) = wired(PROTOCOL, vec![rows.clone()]);
    let channel = Channel::open(&held).expect("opened");
    assert_eq!(channel.ask(&json!({"op": "conversations"})), Ok(rows));
}

/// **A follower is handed each frame as it arrives, and may stop.** `false`
/// ends the read without a word to the engine — dropping the connection is the
/// word — and the frames after it are never taken.
#[test]
fn a_follower_takes_frames_one_at_a_time_and_can_stop_early() {
    let rows = vec![json!({"n": 1}), json!({"n": 2}), json!({"n": 3})];
    let (_scratch, _engine, held) = wired(PROTOCOL, vec![rows]);
    let channel = Channel::open(&held).expect("opened");
    let mut taken = Vec::new();
    channel
        .follow(&json!({"op": "conversations"}), &mut |frame| {
            taken.push(frame);
            taken.len() < 2
        })
        .expect("followed");
    assert_eq!(taken, vec![json!({"n": 1}), json!({"n": 2})]);
}

/// **One connection per ask.** Two asks are two dials, and the engine sees both
/// requests.
#[test]
fn each_ask_is_its_own_connection() {
    let (_scratch, engine, held) = wired(PROTOCOL, vec![vec![answered()], vec![answered()]]);
    let channel = Channel::open(&held).expect("opened");
    for op in ["workspaces", "board"] {
        assert!(channel.ask(&json!({ "op": op })).is_ok());
    }
    let ops: Vec<String> = engine
        .heard()
        .iter()
        .filter_map(|v| v.get("op")?.as_str().map(str::to_owned))
        .collect();
    assert_eq!(ops, ["workspaces", "board"]);
}

/// An engine that ends the stream without answering is an empty answer here,
/// and not an error: what to make of a stream with nothing in it belongs to the
/// layer above, which is the only one that knows what it asked for.
#[test]
fn an_engine_that_answers_nothing_ends_the_stream() {
    let (_scratch, _engine, held) = wired(PROTOCOL, vec![vec![]]);
    let channel = Channel::open(&held).expect("opened");
    assert_eq!(channel.ask(&json!({"op": "workspaces"})), Ok(Vec::new()));
}

/// **Version skew refuses fail-closed and names both versions** (REMOTE §3),
/// before a frame of the answer is decoded.
#[test]
fn an_engine_of_another_protocol_refuses_and_names_both_versions() {
    let (_scratch, _engine, held) = wired(PROTOCOL + 1, vec![vec![answered()]]);
    let channel = Channel::open(&held).expect("opened");
    let reach = channel
        .ask(&json!({"op": "workspaces"}))
        .expect_err("refused");
    // A peer of another protocol refuses before any gesture is decoded, so
    // nothing crossed and an act that met this is not in doubt (bl-3969).
    assert!(!reach.crossed(), "a stated mismatch adjudicates nothing");
    let refusal = reach.said();
    assert!(
        refusal.contains(&format!("seat speaks version {PROTOCOL}")),
        "{refusal}"
    );
    assert!(
        refusal.contains(&format!("engine speaks {}", PROTOCOL + 1)),
        "{refusal}"
    );
}

/// An engine nothing is listening at is one sentence naming the address. Port 1
/// is below the ephemeral range and unbindable without privilege, so no other
/// test's freed port can answer this dial.
#[test]
fn an_engine_that_is_not_there_names_the_address_it_dialled() {
    let scratch = Scratch::new();
    let held = mint::provisioned(scratch.path(), "127.0.0.1:1");
    let channel = Channel::open(&held).expect("opened");
    let reach = channel
        .ask(&json!({"op": "workspaces"}))
        .expect_err("refused");
    assert!(
        !reach.crossed(),
        "a socket that never opened carried nothing"
    );
    let refusal = reach.said();
    assert!(refusal.contains("connect 127.0.0.1:1"), "{refusal}");
}

/// **An engine this box does not trust gets no boundary at all.** The handshake
/// fails inside rustls, so the refusal is a transport sentence and no frame of
/// the gesture is ever read by anyone.
#[test]
fn an_engine_the_anchors_do_not_cover_never_reaches_the_boundary() {
    let (_scratch, engine, mut held) = wired(PROTOCOL, vec![vec![answered()]]);
    let elsewhere = Scratch::new();
    mint::material(elsewhere.path());
    held.anchors = elsewhere.join(super::material::ANCHORS);
    let channel = Channel::open(&held).expect("opened");
    // **And it says what to do about it** (bl-e620). rustls' own words are
    // *"invalid peer certificate: UnknownIssuer"*, which names no file and no
    // act — driven live, a wrong anchor produced that and nothing else,
    // anywhere. The handshake happens inside the first write, so this is where
    // the sentence is earned.
    let reach = channel
        .ask(&json!({"op": "workspaces"}))
        .expect_err("the anchors do not cover it");
    assert!(!reach.crossed(), "a handshake that failed carried nothing");
    let why = reach.said();
    assert!(why.contains("did not verify"), "{why}");
    assert!(
        why.contains("did not verify (") && !why.contains("()"),
        "rustls' own fault is named inside it: {why}"
    );
    assert!(
        why.contains(&held.anchors.display().to_string()),
        "it names the file to look at: {why}"
    );
    assert!(
        why.contains(&held.chain.display().to_string()),
        "and the other half of the pair: {why}"
    );
    assert!(
        why.contains("the seat mints nothing"),
        "and the act, which is not a mint: {why}"
    );
    assert_eq!(engine.heard(), Vec::<Value>::new(), "nothing was said");
}

/// **An engine that will not accept this box's leaf refuses the same way.** The
/// mint's own CA issued both ends here, so what fails is the client half: a
/// chain the engine's verifier cannot chain to its anchors.
#[test]
fn a_leaf_the_engine_will_not_accept_never_reaches_the_boundary() {
    let (scratch, engine, mut held) = wired(PROTOCOL, vec![vec![answered()]]);
    let elsewhere = Scratch::new();
    mint::material(elsewhere.path());
    held.chain = elsewhere.join(CHAIN);
    held.key = elsewhere.join(KEY);
    let channel = Channel::open(&held).expect("opened");
    assert!(channel.ask(&json!({"op": "workspaces"})).is_err());
    assert_eq!(engine.heard(), Vec::<Value>::new(), "nothing was said");
    assert!(scratch.path().is_dir());
}

/// The engine's name comes off the address and from nowhere else: an IP
/// literal is an IP identity — bracketed or not — and anything else is a DNS
/// name.
#[test]
fn the_engine_s_name_is_read_off_the_address() {
    for address in [
        "127.0.0.1:9000",
        "[::1]:9000",
        "engine.example:9000",
        "engine.example",
    ] {
        assert!(server_name(address).is_ok(), "{address}");
    }
    let refusal = server_name("not a name:9000").expect_err("refused");
    assert!(refusal.contains("not a server name"), "{refusal}");
}

/// **Every other write error is still the transport's own words.** The
/// handshake is only the commonest cause of a failed write, not the only one,
/// and a socket that broke mid-send is not a fact about this box's material —
/// so it earns no remedy about certificates it has nothing to do with.
#[test]
fn a_write_that_is_not_a_handshake_is_said_in_the_transport_s_own_words() {
    let scratch = Scratch::new();
    let held = mint::provisioned(scratch.path(), "engine.example:9000");
    let channel = Channel::open(&held).expect("opened");
    let said = channel.wrote(&std::io::Error::other("the pipe went away"));
    assert_eq!(said, "send: the pipe went away");
}