|
TLS: ServerHello now reports the negotiated version and cipher suite
alongside the existing ClientHello SNI support, plus ClientHello's
ALPN extension. ServerHello's version prefers the supported_versions
extension over legacy_version when present - TLS 1.3 always sets
legacy_version to 0x0303 for middlebox compatibility, so reading only
that field would misreport every real TLS 1.3 connection as 1.2.
Cipher suite names are hardcoded only for TLS 1.3's five suites (a
small closed set); everything else reports as raw hex rather than a
guessed name from a "common suites" list.
Live-verifying that against a real Cloudflare TLS 1.3 handshake
surfaced a real, unrelated bug in the QUIC dissector added earlier: it was also being tried against TCP port-443 payloads
(a side effect of the earlier L7Registry port-sharing fix), and
produced false "QUIC" labels on TLS ciphertext continuation fragments
- large encrypted records split across multiple TCP segments, each
fed to the parser independently since this project doesn't reassemble
by default, so a later fragment's effectively random bytes
occasionally passed as a plausible QUIC header.
Fixed in two layers: parse_quic() now enforces RFC 9000's real 20-byte
cap on connection ID lengths, closing most of the long-header false-
positive surface; and L7Dissector gained a transport() method
(defaulting to kAny, so every other dissector's behavior is unchanged)
so QuicDissector can declare itself UDP-only - necessary because the
length cap alone can't touch QUIC's short-header form, which by design
has no structural signal beyond one bit once header protection can't
be removed without connection state.
Re-verified against the identical live scenario afterward: zero false
QUIC labels on the same Cloudflare TCP handshake, and a repeat of the
earlier real HTTP/3 capture confirmed genuine QUIC still decodes
correctly on UDP.
|
|
QUIC decodes only what RFC 9000 sends in cleartext at the framing
level: long/short header form, version, long-packet type, and both
connection IDs. Everything past that is encrypted from the first
protected byte onward, even for Initial packets - decrypting that is
real crypto machinery this project deliberately doesn't take on, the
same call already made for TLS's SNI-only extraction.
Caught a real, previously-latent bug while wiring this in, by design
review rather than live-traffic debugging: L7Registry::dissect()
returned on the first dissector whose port() matched, even if that
dissector's summarize() then failed. Harmless while every registered
port was unique, but QUIC is the first protocol here to genuinely
share a well-known port with something already registered (443: TLS
over TCP, QUIC over UDP - the registry has no transport dimension).
Without the fix, tls_dissector would silently claim every port-443
lookup and QUIC would never be reachable. Fixed to try each same-port
dissector until one actually succeeds, locked in with stub-dissector
tests independent of any real protocol's parsing.
Live-verified thoroughly: real HTTP/3 traffic to google.com via
`curl --http3-only`, captured on wlp1s0, correctly decoding the full
connection lifecycle against Google's actual production QUIC
implementation - Initial packets (including a genuine connection ID
migration mid-handshake), Handshake packets, and 1-RTT short-header
packets. This also confirms the L7Registry fix live: without it none
of this would have decoded at all.
|