The continuous-request row said a -d 0 request never reaches the wire,
which no observation in this validation supports: the run took no packet
capture and the server was not instrumented for datagram arrival, so
what the client emitted before exiting was never seen.
Record what was actually observed — the argument was refused, the client
exited non-zero, and it printed none of the connection line it prints in
every other scenario — and state plainly that the emission was not
observed. The conclusion that matters is unchanged: continuous mode was
not exercisable through this CLI.
No implementation, test or protocol evidence changes.
The environment notes said restriction scenarios were run both with and
without --loose, but the matrix records a strict run for the
packet-length restriction only; the interval and maximum-duration rows
were --loose alone. Say that, so the artifact does not credit
strict-mode coverage it never recorded.
No implementation, test or protocol evidence changes.
Two claims in the validation record were stronger than the evidence
behind them.
The maximum-duration Close conclusion was stated for every conforming
client. That does not follow: the deadline is evaluated on arrival, not
on transmission, so an echo sent legitimately before the negotiated
Duration elapsed can still be queued long enough to arrive after the
server's two-second grace and carry Close. Scope the result to the
loopback run that was actually performed, and describe the Close as a
termination path for traffic continuing or arriving beyond the grace,
including delayed in-flight traffic.
The document also claimed the validation was reproducible from the
commands above, while carrying only summarized client arguments and no
harness — the harness was disposable on purpose and is not being
promoted into repository infrastructure. Say plainly that this is a
record of the validation performed rather than a reproduction harness.
No implementation, test or protocol evidence changes.
Run the released upstream IRTT 0.9.1 client as a black box against the
Tokio server over explicit loopback listeners, and record the result.
Twelve of thirteen matrix rows pass and one is skipped for a client-side
CLI reason: IPv4 and IPv6 ordinary sessions, HMAC with a wrong-key
negative control, packet-length and interval restrictions both strictly
and with --loose, maximum-duration restriction, no-test, and midpoint
timestamps on each clock selection. No incompatibility was found, so
nothing in the implementation changed.
Two results are worth keeping. The single-field midpoint reply this
server deliberately emits instead of upstream 0.9.1's dual-field form is
accepted by the released client, which derives RTT and IPDV from it. And
the maximum-duration close is unreachable by a conforming client: the
deadline is the configured maximum plus two seconds while negotiation
caps the session Duration at that same maximum, so a client honoring the
Duration it was given always stops early. The two-second grace is the
measured margin already recorded in the protocol evidence, so this is
the implementation matching that evidence rather than a defect, and the
close path stays covered by the lifecycle tests.
Upstream source, tests and history were not inspected; only the
executable's version, help, exit status and normal output were observed.
No test in this repository depends on the upstream binary.
Transfer independently black-box-verified server behavior from a source-assisted
research phase conducted outside this repository. Only a sanitizer-candidate
report of black-box findings and the packet captures it referenced were admitted;
no upstream source, tests, history, harnesses, build trees, result files or
source-assisted analysis crossed the boundary. Provenance and the boundary
discipline are recorded in docs/clean-room/CLEANROOM_NOTES.md.
New upstream robustness defect (Section 22.5). An open selecting timestamps while
omitting the Clock parameter is accepted with a valid token and no Clock echoed,
and the first echo on that session is fatal to the server process, taking
unrelated sessions on the same process with it. An explicit Clock=0 is instead
rejected at open, so parameter presence is externally meaningful. Recorded as an
observed defect with a must-not-crash recommendation; the clean server's
resolution is deliberately left to the implementation work.
Also established or strengthened:
- the idle grace and maximum-duration grace are fixed additive margins across the
settings swept, and the maximum-duration clock starts at the first echo that is
actually served;
- a rate-limited request is the only tested drop class that keeps a session
alive, and in one documented configuration a conforming client can observe the
difference;
- a post-deadline packet of several tested classes consumes an expired session's
one remaining reply, including packets that are themselves dropped;
- the reply-length cap is the bind interface's MTU on the interfaces where it was
reachable, and a length the host cannot transmit ends the process;
- DSCP marking follows the session, with unmarked open replies and no
cross-session leakage across interleaved sessions;
- repeated tags are last-valid-wins, with invalid-duplicate handling scoped to
the orders actually tested, and unknown tag values are consumed as varints.
Three captures were admitted, each rewritten to the container convention already
used here and verified byte-identical in packet data and timestamps:
server-clock-absent (3 packets), server-expiry-consumption (14) and
server-dscp-interleaved (32). Two further captures were reviewed and rejected as
redundant or unsupporting; their textual results were kept instead.
Host-specific figures are labelled as such throughout, upstream defects are not
promoted to protocol requirements, observations are separated from inferences and
from recommendations, and no implementation policy is chosen here. The client
specification gains matching refinements where the two compatibility baselines
would otherwise state a lifecycle or marking rule differently.
Documentation and evidence only; no production code changed.
Endpoint identity documented the IPv6 scope identifier as an established
component alongside family, address and port. The server specification does
list the zone, but its remaining-unknowns section records that multi-zone
behavior could not be tested on a single-host platform, so no evidence settles
how a reference server compares scoped addresses. Presenting the choice as
verified compatibility overstated what is known, which the crate's own guidance
forbids.
Say what it is instead: a deliberate policy taken under a recorded unknown. Two
peers reachable at the same link-local address in different zones are genuinely
different peers, so treating the zone as identity is the conservative reading —
the failure it prevents is one peer closing another's session, and the failure
it risks is a scoped client having to reopen. The excluded flow label is
labelled the same way, and `irtt-server` guidance now carries the rule so the
echo slice reuses this comparison rather than inventing a second one.
Behavior is unchanged; this is documentation and a test comment.
Session identity is the address family, the IP address, the UDP source port
and — for IPv6 — the scope identifier. `SocketAddrV6` equality additionally
covers the flow label, so comparing endpoints with `==` admitted a field that
identifies no endpoint: a client whose flow label changed mid-session could be
refused its own close and strand the session, which nothing reclaims while
expiry is unimplemented. It bought nothing in exchange, since the token,
address, port and scope are what an off-path attacker would have to guess.
Compare the specified components instead. Scope still counts, and the address
is still stored verbatim, so a later reply goes back to exactly the endpoint
the request came from.
Not reachable through a default socket today: a receiver reports the flow
label only when asked to, and there is no runtime slice yet. It is reachable
through the public core, which takes caller-supplied addresses.
Release the session a client close names. A close is bound to a session only
when the token matches and the datagram arrived from that session's exact
endpoint, so holding a token is not by itself authority to tear the session
down: a close from a foreign source port, address, family or IPv6 scope leaves
the session live, and one close cannot take down a sibling session the same
peer opened separately. A token that is unknown, already closed or zero matches
nothing and leaves the table untouched; zero is reserved for no-test replies and
never issued.
Nothing is sent either way. Protocol version 1 defines no acknowledgement for a
client close, so a successful close returns the same `Ok(None)` as a rejected
one and a delivered close is indistinguishable to the client from a lost one.
A standalone `Reply|Close` datagram is tolerated by clients but has no
demonstrated use, so none is encoded.
Authentication still runs before the session is looked up. That keeps a bad MAC
on a live token indistinguishable from an unknown token, and means a close that
fails authentication — missing, wrongly keyed, corrupted, or unexpected on a
server with no key — cannot remove a session. Trailing bytes after the token
stay acceptable: the structural decoder already tolerates them and the server
does not re-parse the request.
The session table remains the only record of how full the server is, so a close
frees capacity immediately and a refused open can succeed once one is released.
Close draws no token and touches no other state; the endpoint lookup borrows
the table only until the comparison is made, so the removal needs no clone.
Echo remains ignored. The test that pinned close as a no-op is replaced by
`tests/close.rs`, which covers removal, silence, repeated close, echo after
close, endpoint binding, unknown/zero/stale tokens, authentication failure,
trailing bytes, sibling sessions and capacity reuse; `unsupported.rs` keeps
echo and structurally invalid traffic.
Nils Andreas Svee