The sse_parser re-frame probe emitted 'data: <line>' unguarded, so a payload CR (interior CR in multi-line data: the payload line is '\r') was consumed by strip_cr at re-parse time and the round-trip lost it. Wave 1 had skipped only the terminal-CR case. Found ~32 min into the first 45-min sse_parser campaign. - frame_event emits 'data: <line>\r': the guard CR is the line terminator, strip_cr removes exactly it, the payload CR survives - drop the terminal-CR skip; the round trip is now total over JSON-encodable payloads (JSON never encodes a raw CR, so the residual asymmetry is the serde_json non-preserved key-order class) - no crate-side change: the parser was correct (data: x\r\r\n -> x\r); only the harness re-encode was weak - regression: 2 new seeds (interior CR via \r escape; raw CR via CRLF framing, two-line doc) + unit cases Verification: shared 21/21 (default + no-default-features), main crate green, clippy -D warnings clean, fmt clean, cargo fuzz build clean
alkhttp fuzzing
cargo-fuzz targets for the HTTP surface's hand-rolled parse paths. The
design and operating rules live in docs/plans/fuzzing.md (adopted
from alkcall's docs/research/fuzzing.md); this README is the
operational cheat-sheet.
Layout
fuzz_targets/— nightly-onlyfuzz_target!binaries (thin wrappers).shared/— stable-toolchain library holding the invariant logic; the corpus replay tests run here on plaincargo test.corpus/<target>/— committed seeds (regenerate withpython3 fuzz/gen_fuzz_seeds.py).artifacts/— gitignored crash/oom/timeout artifacts + campaign logs.
Targets
| Target | Drives |
|---|---|
sse_parser |
SseParser::feed + the FWD-17 envelope mapping (src/adapters/forward.rs) — the SSE frame parser every subscription forwards through |
ws_chunk_framing |
WriteChunkWalk (the write pump's chunk walk) (src/websocket/byte_adapter.rs) |
spec_import |
OpenAPISpec::from_str/from_yaml/from_json, the YAML normalization boundary, CompiledInputSchema compile/harden/validate, FromMCP::build_spec (src/adapters/openapi_spec.rs, input_validation.rs, from_mcp/mod.rs) |
ws_session_opseq |
stateful op sequences over the WS byte adapter's generic pumps (run_read_pump/run_write_pump over the mock socket flavor) — interleavings, close timing, loud-gate mapping, backpressure |
retry_throttle |
the inlined RetryAfterMiddleware's throttle map: capacity bound, eviction policy, ceiling clamp, refresh contraction, Retry-After parse partition |
Running a campaign — always detached
Agent sessions must never run fuzzing in the foreground (an OOM in a target can take down the session host; see docs/plans/fuzzing.md §2). Use the detached runner:
fuzz/run-detached.sh sse_parser
# poll:
tail -n 50 fuzz/artifacts/sse_parser-*.log
ls fuzz/artifacts/sse_parser/
pgrep -f "cargo fuzz run sse_parser"
FUZZ_RUNTIME_SECS=1800 fuzz/run-detached.sh sse_parser for a longer
campaign. The runner pins -fork=1 -rss_limit_mb=2048 -malloc_limit_mb=2048 -timeout=25 and detaches via setsid + nohup.
Corpus replay (the standing fuzz gate)
cargo test --manifest-path fuzz/shared/Cargo.toml
Replays every committed seed through the same invariant functions the fuzzer runs, on stable, no nightly needed. Part of the release verification checklist (AGENTS.md).
Toolchain notes
rust-toolchain.toml pins nightly for this subtree only (llvm-tools
required by cargo-fuzz); the crate itself stays on stable at MSRV 1.88.
cargo fuzz build must be run with the fuzz dir as CWD or trust the
toolchain file (rustup resolves per directory).
Run campaigns before releases and after touching src/adapters/forward.rs
(the SSE parser), src/websocket/byte_adapter.rs (the WS chunk walk),
or the import adapters (src/adapters/openapi_spec.rs,
input_validation.rs, from_mcp/).