kyleandClaude Opus 5.5
0339dc13b2
Each task's tests were run against a reference at its end state; the end states were replayed from master in order with the gate at each step (650 to 762 tests); each skeleton compiles against its tests and fails them. The reference is kept off this machine. Lessons T27 (every wait in a test has a limit) and T28 (mutate the reference before hand-over) come from this work. Co-Authored-By: Claude Opus 5.5 (1M context) <noreply@anthropic.com>
61 lines
2.7 KiB
Markdown
61 lines
2.7 KiB
Markdown
# M4a task 01: SHA-1 in `proto`
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**Branch:** `m4a` (run `git switch m4a`; `git status --short` must be empty, otherwise stop)
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**Commit subject:** `proto: sha1, for the WebSocket handshake check`
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## Goal
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`gatewayd` speaks WebSocket to Mattermost. The server proves it understood the handshake by
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sending back the SHA-1 of our key (RFC 6455, section 4.2.2), so we need SHA-1. It lives in
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`proto`, which has no dependencies of its own. It is used for that check and nothing else: it must
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never protect anything.
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## Files
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- Copy: `crates/proto/tests/sha1.rs`, and the skeleton `crates/proto/src/sha1.rs`
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- Modify: `crates/proto/src/lib.rs` (`pub mod sha1;`), `docs/implementer-log.md`
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## Interface (in the skeleton)
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```rust
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pub fn sha1(data: &[u8]) -> [u8; 20]; // written: new, update, finish
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pub struct Sha1 { state: [u32; 5], block: [u8; 64], filled: usize, length: u64 }
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impl Sha1 {
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pub fn new() -> Sha1; // written: the five initial words
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pub fn update(&mut self, data: &[u8]); // todo
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pub fn finish(self) -> [u8; 20]; // todo
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fn compress(&mut self, block: &[u8; 64]); // todo
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}
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```
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`length` counts **bits** fed so far. Each `todo!()` has its steps above it. No indexing that can go
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out of bounds: `w[i]` on the fixed `[u32; 80]` inside `compress` is fine; slicing `data` or `block`
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by a computed range is not (use `get`, `get_mut`, `split_at`). Use `as_chunks::<4>()` to read
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big-endian words.
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## Steps
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- [ ] **1. Copy.** `git switch m4a`, then
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`cp docs/plans/M4a/files/crates/proto/tests/sha1.rs crates/proto/tests/` and
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`cp docs/plans/M4a/files/crates/proto/src/sha1.rs crates/proto/src/`. Add `pub mod sha1;` to
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`crates/proto/src/lib.rs`.
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- [ ] **2. See it fail.** `cargo test -p proto --test sha1`. Expected: it compiles, and 4 tests
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fail with `not yet implemented`.
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- [ ] **3. Fill the three functions**, one at a time: `compress`, then `update`, then `finish`. Run
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`cargo check -p proto` after each.
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- [ ] **4. See it pass.** `cargo test -p proto --test sha1`. Expected: 4 passed. The tests include
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FIPS 180 and RFC 3174 vectors, a million `a`s, the lengths around the 64-byte block where the
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padding changes shape (checked with `sha1sum`), and the RFC 6455 handshake example; every case is
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also fed in pieces.
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- [ ] **5. Run the gate.** `cargo fmt --all`, then `make gate`. Expected last line: `gate: ok`.
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- [ ] **6. Log and commit.** `git add crates/proto docs/implementer-log.md Cargo.lock && git commit`
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## Done when
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- `cargo test -p proto --test sha1` passes; `make gate` prints `gate: ok`.
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## Stop and report if
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- A test vector fails and you cannot find why after checking `compress` against the comment twice.
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