Rejected with the required error code 0x109.
The client did what the clause requires.
What was measured
- Client
- neqo — neqo (Firefox), 0.31.1
- Test
- SETTINGS_H3_DATAGRAM with a value that is neither 0 nor 1 —
h-datagram-setting-invalid - Clause
- RFC 9297 §2.1.1 (MUST)
- Class
- correctness — Rejected something invalid, with the code the RFC names.
- Required behaviour
- Close the connection with H3_SETTINGS_ERROR. Unusually for a setting, RFC 9297 pins down the invalid-value case rather than leaving it open: the value "MUST be either 0 or 1", and if one "is received with a value that is neither 0 nor 1, the receiver MUST terminate the connection with error H3_SETTINGS_ERROR". This is the setting that gates HTTP Datagrams and so WebTransport, which means a client that implements either has real parsing behind it rather than an ignored identifier.
- Measured
- 2026-09-18
Reproduce it
The suite is the judge, so the reproduction is to point the same client at the same test and let the server report what it saw.
SESSION=$(curl -sX POST https://conformance.pqcrypta.com/session | jq -r .id)
# then drive neqo at the test URL and read the verdict:
curl -s https://conformance.pqcrypta.com/report/$SESSION.json | jq '.results["h-datagram-setting-invalid"]'