Closes the gap that left the runner's `resumption` testcase as the
last unsupported standard test. The TLS layer now:
- Derives `resumption_master_secret` (RFC 8446 §7.1) right after
appending client Finished to the transcript. Cached on the key
schedule so it can seed PSK derivations from any subsequent
NewSessionTicket the server emits.
- Parses NewSessionTicket bodies (RFC 8446 §4.6.1) when they arrive
post-handshake at Application level. For each ticket: derive the
per-ticket PSK via `HKDF-Expand-Label(resumption_master_secret,
"resumption", ticket_nonce, 32)` and surface a self-contained
TlsResumptionState (ticket bytes + PSK + cipher suite + age-add +
issued-at) through a new TlsSecretsListener.onNewSessionTicket
callback. QuicConnection's tlsListener forwards to a public
onResumptionTicket lambda the application sets.
- On a fresh TlsClient construction with a non-null `resumption`
argument: seed the early secret from the cached PSK
(`HKDF-Extract(IKM=PSK, salt=0)` — the Quartz Hkdf.extract
signature is `(IKM, salt)` despite the misleading first-parameter
name; non-PSK deriveEarly passes zeros for both so the order
didn't matter and the bug only surfaced now), build the resumption
ClientHello with `pre_shared_key` as the LAST extension carrying a
single identity (the cached ticket) and a binder over the
PartialClientHello, splice the binder bytes into the encoded
message after a one-shot SHA-256 hash of bytes 0..len-35.
- State machine: when ServerHello carries `pre_shared_key` with the
selected_identity we offered (we only ever send identity index 0,
any other value is a hard fail), latch `pskAccepted = true`.
WAITING_CERTIFICATE_OR_FINISHED then accepts Finished without the
Certificate/CertificateVerify pair the full-handshake path
requires — the PSK itself transitively authenticates the server
via the prior issuing connection.
- If we offered PSK but the server didn't pick it (full-handshake
fallback), hard-fail. The fallback path needs to clear the
PSK-seeded early secret and re-run derivation against zeros, which
is real work; the runner's resumption testcase requires server
acceptance anyway, so this gate isn't load-bearing for matrix
green. Production callers that care about the fallback can wire
it later.
InteropClient adds a `runResumptionTest` that splits the runner's
URL list in half across two sequential connections — first runs a
full handshake and captures the NewSessionTicket via
onResumptionTicket, second runs the PSK handshake with the cached
state. ✓ R against aioquic, picoquic, quic-go.
Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>
Vitor Pamplona
fec917d27b