Track A protocol hardening for native-v1.
1. Protocol VERSION discipline (protocol.rs, native.rs, dosh-server.rs,
dosh-client.rs): bump protocol::VERSION to 2 and NATIVE_PROTOCOL_VERSION to 2.
Foreign wire-version datagrams now get a clear named "protocol version
mismatch - upgrade dosh" reject from the server instead of a silent timeout
(peek_foreign_wire_version + VERSION_MISMATCH_REASON). The native handshake's
plaintext protocol_version is also checked server-side before any crypto via
check_native_protocol_version, returning a typed ProtocolVersionMismatch.
2. Transport rekey (spec section 11/9): server rotates a client's traffic key
after rekey_after_packets OR rekey_after_secs (config knobs). Rotated keys are
derived independently of the handshake keys from the current key plus fresh
server CSPRNG material shipped confidentially in an AEAD Rekey packet
(derive_rekey_session_key). The previous epoch's key is retained briefly so
in-flight pre-rekey packets still decrypt (matched by session_key_id), and
stale-epoch packets are ignored, not fatal. Client handles Rekey/RekeyAck.
3. Connection migration (spec section 11): every authenticated, replay-accepted
packet now migrates client.endpoint to the new source address (input, resize,
ping, ack, resume, stream*, rekey-ack), not just resume. Ping now verifies its
AEAD tag before acting so migration cannot be spoofed.
4. Native auth rate limiting: per-source-IP token bucket
(native_auth_rate_limit_per_minute) enforced in handle_native_client_hello
BEFORE any X25519/Ed25519 work; over-limit hellos get a non-crypto reject.
5. Speed: replaced O(sessions x clients) per-packet linear scans with an O(1)
HashMap<conn_id, session_name> index in ServerState, kept in sync on every
client insert/remove (attach handlers, detach, remove_client, cleanup reap,
session-exit drain).
New config keys (ServerConfig, with defaults): rekey_after_packets = 100000,
rekey_after_secs = 3600.
Tests: version-mismatch reject (no hang), rate-limit flood reject, rekey
round-trip end-to-end + key-derivation unit tests, source-address migration,
client-index sync + cleanup purge. fmt and full test suite green.
Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>
The native-v1 work changed the UDP wire format (HEADER_LEN 42->58) without a
version bump, so a current client silently timed out against the older
still-deployed server. The server just needed redeploying; alongside that,
fix the robustness bugs surfaced while restoring the connection:
- Server: clamp terminal size to >=1 at every PTY/parser resize site. A client
reporting a 0x0 terminal made vt100::Parser::set_size panic ("attempt to
subtract with overflow") and took down the whole single-threaded daemon.
- Client: treat size() == Ok((0,0)) like a missing size and fall back to 80x24
instead of sending 0x0 to the server.
- Reap abandoned sessions and their shells. PtyHandle now retains the child and
kills it on drop, and the cleanup task removes clientless, non-prewarmed
sessions after the grace period. Previously the shell leaked forever (one
zsh per abandoned session); prewarmed sessions still stay hot.
- Evict half-finished native handshakes (pending_native) after 30s so an
unauthenticated ClientHello flood can't grow the map without bound.
- Drop the per-client, per-packet vt100 Screen clone on the output hot path and
remove the write-only last_screen field.
- Guard load_or_create_server_secret against a <32-byte secret file (was an
index-out-of-range panic at startup).
- Reconcile stream flow-control credit (client and server) when StreamData hits
a missing writer, so a closed/unknown stream can't wedge the peer's window.
Adds a unit test for session reaping. cargo fmt + cargo test green.
Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>
DuProcess