Nils Andreas Svee
93491e7762
`Params::decode` seeded `Params::default()` and overwrote only the tags it saw, so an omitted tag and one explicitly encoded as zero were indistinguishable afterwards. The protocol gives those the same value but not the same meaning, and a server cannot apply its open admission rules without telling them apart: an absent Duration or Interval is accepted as the wire default zero, while one explicitly encoded as zero is invalid. Add `Params::decode_with_presence`, returning the decoded values alongside a `ParamPresence` recording which known tags appeared. `Params::decode` now delegates to it, so there is still exactly one parser and the two cannot diverge. Unknown tags stay ignored and untracked, and repeated known tags keep last-value-wins. Add `Clock::Unspecified = 0` as the default, which is the wire default for an absent Clock tag and what an empty parameter payload decodes to. An explicit Clock tag encoding zero remains an invalid enum value, so `Unspecified` is only ever reached by omission; `encode` omits the tag for it rather than emitting an explicit zero. It selects no clock, so `has_wall`/`has_mono` are false and no timestamp field is laid out. `ClientConfig::clock` is public and therefore now constructible as `Unspecified`, which is a wire default rather than a client mode. Reject it during config validation. The client default stays `Clock::Both`, so normal client-generated params and wire vectors are unchanged.
99 lines
3.7 KiB
Rust
99 lines
3.7 KiB
Rust
//! Low-level wire encode/decode support for the IRTT protocol.
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//!
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//! `irtt-proto` intentionally mirrors protocol fields closely: request/reply
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//! structs expose wire-oriented values, flags, counters, timestamps, and
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//! parameter enums rather than higher-level policy decisions. Higher-level
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//! crates such as `irtt-client` are responsible for session behavior and
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//! user-facing validation.
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//!
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//! [`Params::decode`] rejects malformed or incompatible incoming parameter
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//! values, including invalid enum discriminants, malformed UTF-8, and oversized
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//! `server_fill` values. Direct construction followed by [`Params::encode`]
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//! performs no additional validation, so callers that build `Params` manually
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//! are responsible for validating those values before sending them.
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//!
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//! Parameters are optional on the wire, and an absent tag takes its wire
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//! default — zero for every integer field, and [`Clock::Unspecified`] for the
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//! clock. A receiver that must distinguish an omitted tag from one explicitly
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//! encoded as zero uses [`Params::decode_with_presence`], which runs the same
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//! parser and additionally reports a [`ParamPresence`].
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//!
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//! The crate also provides packet layout calculation, packet encoding and
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//! decoding, and optional HMAC placement, computation, and verification
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//! helpers.
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//! Encoder `hmac_key` arguments are authoritative: `Some(key)` adds
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//! `FLAG_HMAC`, while `None` removes it from caller-supplied reply flags.
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//!
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//! # Directional model
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//!
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//! Requests use one encoder and one decoder for all three request kinds:
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//! [`encode_request`] builds a request from borrowed sender-side values, and
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//! [`decode_request`] structurally classifies an inbound request without a key,
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//! negotiated [`Params`], or any session state. [`verify_packet_hmac`]
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//! authenticates a packet separately, once the applicable key is known —
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//! `FLAG_HMAC` being present is a statement about layout, not about validity.
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//!
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//! Replies keep type-specific decoders ([`decode_open_reply`],
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//! [`decode_echo_reply`]) because a client already knows from its session state
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//! which reply kind to expect, and the two need genuinely different semantic
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//! context.
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//!
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#![forbid(unsafe_code)]
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pub mod echo;
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mod envelope;
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pub mod error;
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pub mod flags;
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pub mod hmac;
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pub mod layout;
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pub mod open;
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pub mod params;
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pub mod request;
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pub mod varint;
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pub use echo::{decode_echo_reply, encode_echo_reply, EchoReply, TimestampFields};
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pub use error::{ProtoError, Result};
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pub use flags::*;
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pub use hmac::{compute_hmac, compute_hmac_in_place, verify_hmac, verify_packet_hmac};
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pub use layout::{echo_header_len, echo_packet_len, PacketLayout};
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pub use open::{decode_open_reply, encode_open_reply, OpenReply};
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pub use params::{
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Clock, DecodedParams, ParamPresence, Params, ReceivedStats, ServerFill, StampAt,
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MAX_SERVER_FILL_BYTES,
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};
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pub use request::{
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decode_request, encode_request, DecodedRequest, DecodedRequestKind, RequestToEncode,
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};
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pub const MAGIC: [u8; 3] = [0x14, 0xA7, 0x5B];
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pub const PROTOCOL_VERSION: i64 = 1;
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pub const HMAC_SIZE: usize = 16;
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pub const TOKEN_SIZE: usize = 8;
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pub const SEQ_SIZE: usize = 4;
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pub const RECV_COUNT_SIZE: usize = 4;
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pub const RECV_WINDOW_SIZE: usize = 8;
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pub const TIMESTAMP_SIZE: usize = 8;
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pub(crate) const HEADER_SIZE: usize = 4;
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pub(crate) fn write_header(out: &mut Vec<u8>, flags: u8) {
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out.extend_from_slice(&MAGIC);
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out.push(flags);
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}
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pub(crate) fn validate_header(packet: &[u8]) -> Result<u8> {
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if packet.len() < HEADER_SIZE {
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return Err(ProtoError::PacketTooShort {
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needed: HEADER_SIZE,
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actual: packet.len(),
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});
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}
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if packet[..3] != MAGIC {
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return Err(ProtoError::BadMagic);
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}
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let flags = packet[3];
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flags::validate_flags(flags)?;
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Ok(flags)
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}
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