Add `irtt-server` with the deterministic protocol and session engine the upcoming Tokio runtime will call. `ServerCore::handle_datagram` takes a source endpoint and the bytes of one datagram and returns the bytes to send back, or nothing. It performs no I/O and keeps no clock, so every decision is a pure function of its state and that input apart from drawing session tokens. Rejection is silence. The protocol defines no error reply, no reset and no NACK, so malformed, unauthenticated and policy-refused datagrams are discarded without a response and without disturbing any live session; a client tells "rejected" from "lost" only by timing out. `ServerError` is reserved for internal failures on the server's own side, so an inbound `ProtoError` never surfaces as a server failure. Open handling authenticates before decoding parameters, so a packet that fails authentication is discarded without parsing untrusted data and no reply behavior reveals which stage rejected it. Duration and Interval are accepted when absent and rejected when explicitly present and not positive, which is what the presence-aware parameter decode is for. Negotiation currently rewrites only the protocol version; the restriction knobs the specification describes are deliberately left for their own slices, with one obvious place to add them. Sessions are bounded to a finite default. A single unauthenticated datagram creates one and opens are never deduplicated, so an unbounded table is a liability rather than a compatibility feature; upstream's absence of session bounds is explicitly not a target. A full table drops new opens silently and evicts nothing. No-test opens keep working at capacity because they create no state. Session tokens come from the operating system's random source, since a token is the only thing standing between an off-path attacker and a usable session on an unauthenticated server. A drawn value that is zero or collides with a live session is redrawn within a finite budget; there is no predictable fallback, and a colliding token never overwrites the session that holds it. The reply is encoded before the session is inserted, so an internal failure cannot leave a half-created session behind. Echo and close requests pass admission and are then deliberately ignored: this slice creates sessions, and lifecycle and receive semantics belong to the slices that implement them. Tests pin that so a half-implemented lifecycle cannot appear by accident.
159 lines
4.9 KiB
Rust
159 lines
4.9 KiB
Rust
use irtt_proto::{Clock, Params, ReceivedStats, ServerFill, StampAt};
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use super::support::{
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core_with_tokens, expect_normal_open_reply, open_request, open_request_with_raw_params,
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param_int, param_server_fill, peer, ScriptedTokens,
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};
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use crate::ServerConfig;
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const TOKEN_A: u64 = 0x0102_0304_0506_0708;
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fn reject_case(name: &str, payload: Vec<u8>) {
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let tokens = ScriptedTokens::new([TOKEN_A]);
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let mut core = core_with_tokens(ServerConfig::default(), tokens.clone());
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let reply = core
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.handle_datagram(peer(), &open_request_with_raw_params(&payload, None))
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.expect("rejected parameters are not a server error");
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assert!(reply.is_none(), "{name} must be answered with silence");
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assert_eq!(core.session_count(), 0, "{name} must create no session");
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assert_eq!(
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tokens.remaining(),
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1,
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"{name} must not consume a session token"
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);
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}
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#[test]
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fn malformed_or_out_of_range_parameters_are_dropped_without_a_session() {
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// Truncation and overflow.
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reject_case("truncated tag varint", vec![0x80]);
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reject_case("truncated value varint", vec![2]);
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reject_case("truncated multi-byte value", vec![2, 0x80]);
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reject_case(
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"varint overflow",
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vec![
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1, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff,
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],
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);
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// Duration and Interval: present and not positive.
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reject_case("explicit duration zero", param_int(2, 0));
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reject_case("negative duration", param_int(2, -1));
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reject_case("explicit interval zero", param_int(3, 0));
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reject_case("negative interval", param_int(3, -5));
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// Enum values outside their defined range.
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reject_case("received stats above range", param_int(5, 4));
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reject_case("negative received stats", param_int(5, -1));
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reject_case("stamp at above range", param_int(6, 5));
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reject_case("explicit clock zero", param_int(7, 0));
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reject_case("clock above range", param_int(7, 4));
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// Server fill.
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reject_case(
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"server fill declaring more than the payload holds",
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param_server_fill(10, b"ab"),
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);
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reject_case(
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"server fill longer than 32 bytes",
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param_server_fill(33, b"0123456789abcdef0123456789abcdefx"),
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);
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reject_case(
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"server fill that is not utf-8",
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param_server_fill(1, &[0xff]),
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);
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}
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#[test]
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fn absent_duration_interval_and_clock_are_accepted_as_wire_defaults() {
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// The whole reason the decoder reports presence: an omitted tag and one
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// explicitly encoded as zero share a value but not a verdict.
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let mut core = core_with_tokens(ServerConfig::default(), ScriptedTokens::new([TOKEN_A]));
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let packet = core
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.handle_datagram(
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peer(),
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&open_request_with_raw_params(¶m_int(1, 1), None),
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)
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.unwrap()
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.expect("absent duration, interval and clock are all valid");
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let reply = expect_normal_open_reply(&packet, None);
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assert_eq!(reply.params.duration_ns, 0);
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assert_eq!(reply.params.interval_ns, 0);
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assert_eq!(reply.params.clock, Clock::Unspecified);
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assert_eq!(core.session_count(), 1);
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}
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#[test]
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fn valid_optional_parameter_values_survive_unchanged() {
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for (name, requested) in [
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(
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"clock wall",
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Params {
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clock: Clock::Wall,
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..Params::default()
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},
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),
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(
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"clock monotonic",
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Params {
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clock: Clock::Monotonic,
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..Params::default()
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},
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),
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(
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"clock both",
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Params {
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clock: Clock::Both,
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..Params::default()
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},
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),
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(
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"received stats and stamp at",
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Params {
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received_stats: ReceivedStats::Both,
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stamp_at: StampAt::Midpoint,
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clock: Clock::Wall,
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..Params::default()
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},
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),
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(
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"positive duration and interval",
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Params {
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duration_ns: 1,
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interval_ns: 1,
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..Params::default()
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},
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),
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(
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"maximum length server fill",
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Params {
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server_fill: Some(ServerFill {
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value: "0123456789abcdef0123456789abcdef".to_owned(),
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}),
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..Params::default()
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},
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),
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] {
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let mut core = core_with_tokens(ServerConfig::default(), ScriptedTokens::new([TOKEN_A]));
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let packet = core
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.handle_datagram(peer(), &open_request(&requested, None))
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.unwrap()
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.unwrap_or_else(|| panic!("{name} must be answered"));
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let reply = expect_normal_open_reply(&packet, None);
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assert_eq!(
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reply.params,
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Params {
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protocol_version: 1,
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..requested
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},
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"{name} must survive negotiation unchanged"
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);
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}
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}
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