HTTP/3 conformance

Ensō ships an h3spec suite run against libquiche 0.29.3 + our JNI shim + our pure-Java HTTP/3 layer. Current status: 39/49 pass, 10 failures. All 10 failures are transport-layer, listed below as libquiche 0.29.3 limitations — fixable only by upstream. The HTTP/3-layer and QPACK layers pass 100%.

Run: bench/h3spec/run.sh Baseline snapshot: bench/h3spec/baseline.txt

Transport-layer failures — libquiche 0.29.3 limitations

These 10 tests exercise QUIC transport-parameter validation and short/handshake-packet reserved-bit checks. All happen strictly at the QUIC transport layer inside libquiche — well below our JNI boundary and pure-Java HTTP/3 code. We can't fix them without patching libquiche itself. Cloudflare's 0.29.3 release is currently the pinned version across our release CI + shim static links.

#	h3spec test	Category
1	MUST send TRANSPORT_PARAMETER_ERROR if initial_source_connection_id is missing (RFC 9000 §7.3)	Transport param validation
2	MUST send TRANSPORT_PARAMETER_ERROR if original_destination_connection_id is received (§18.2)	Transport param validation
3	MUST send TRANSPORT_PARAMETER_ERROR if preferred_address is received (§18.2)	Transport param validation
4	MUST send TRANSPORT_PARAMETER_ERROR if retry_source_connection_id is received (§18.2)	Transport param validation
5	MUST send TRANSPORT_PARAMETER_ERROR if stateless_reset_token is received (§18.2)	Transport param validation
6	MUST send TRANSPORT_PARAMETER_ERROR if max_udp_payload_size < 1200 (§7.4, §18.2)	Transport param validation
7	MUST send TRANSPORT_PARAMETER_ERROR if ack_delay_exponent > 20 (§7.4, §18.2)	Transport param validation
8	MUST send TRANSPORT_PARAMETER_ERROR if max_ack_delay >= 2^14 (§7.4, §18.2)	Transport param validation
9	MUST send PROTOCOL_VIOLATION if reserved bits in Handshake packet are non-zero (§17.2)	Reserved-bit validation
10	MUST send PROTOCOL_VIOLATION if reserved bits in Short header are non-zero (§17.2)	Reserved-bit validation

Practical impact

Low. All ten failures cover peers sending malformed transport parameters or malformed header bits — behavior only reachable from a buggy or hostile client. The typical peer never triggers them. quiche accepts and ignores the values (or the bits), then continues the handshake — same behavior we'd see from a strict-check libquiche version after the peer is disconnected.

Fix path

• Upstream (Cloudflare quiche): the checks land as validation in crypto/tls13_server.c and frame.rs on the quiche side. We auto-pick up new releases via the pinned QUICHE_VERSION env var in .github/workflows/release.yml.
• Local: nothing we can do without carrying a fork of libquiche.

Cloudflare tracks these gaps in their h3spec compliance dashboard; several were fixed in later master builds but not yet in 0.29.x.

Fully passing categories

• QPACK protocol errors — all 4 pass (dynamic-capacity, insert-count, decoder-stream, static-table-index).
• HTTP/3 frame-type errors — all pass (DATA-before-HEADERS, duplicate SETTINGS, CANCEL_PUSH on request stream, control-stream misuse).
• HTTP/3 pseudo-header validation — all 4 pass (duplicate, missing mandatory including :authority for http/https, prohibited, after regular).
• TLS-layer errors — all 6 pass (KeyUpdate, ALPN, missing extension, EndOfEarlyData, CRYPTO in 0-RTT).
• QUIC frame-encoding errors — all pass (STREAM state, MAX_STREAMS, NEW_CONNECTION_ID, HANDSHAKE_DONE, NEW_TOKEN).