386 added comment lines down to 287 across client, mediator, kcp_stream
and common. Same rule as hbb_common 3d64e43: out go past-bug narration,
rejected alternatives, measurements and restatements of the code; the
non-derivable why stays.
is_direct_transport goes with them. Judging the race by a transport
label was replaced by the resolved direct flag, leaving it used only by
its own test — and, having been inserted between the doc comment and
race_transports_prefer_webrtc, it had also taken that function's
contract with it. Removing it reattaches the doc where it belongs.
Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01ExUfAkYbq8UC9pQCiLy8TQ
The branch had flipped KCP to nc=0 (built-in congestion window) for
every session. That is a transport-behavior change for all users made on
reasoning alone, and the reasoning does not decide it: which profile wins
depends on why packets are being lost.
nc=1 - what RustDesk has always shipped - never shrinks the send window,
so on a genuinely congested uplink it deepens the loss it is reacting to.
But nc=0's backoff is blunt: a fast retransmit halves the window while an
RTO sets cwnd = 1 outright (ikcp.c) and recovery slow-starts from one
packet, so on a link with random loss and no congestion - Wi-Fi
interference, a long-haul path - it reads loss as congestion and can
stall an interactive stream for seconds. That failure mode is also the
more visible one to a remote-desktop user.
No benchmark settles this either: a loopback A/B has no bottleneck queue,
hence no congestion to control, and would flatter nc=1 by construction.
Deciding it needs a shaped link or field data.
So keep the profile users already run and let the other one be asked for
("enable-kcp-congestion-control" = "Y"). Flipping the default later is a
one-line change once there is evidence. kcp-sys keeps its own test
covering the nc=0 path.
Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01ExUfAkYbq8UC9pQCiLy8TQ
kcp-sys has been through two review rounds of behavioral fixes; the
client wrapper (kcp_io pumps, connect/accept deadlines, framed-stream
adaptation, guard lifetimes) had no tests pinning what rustdesk actually
relies on. Four now do, each through real 127.0.0.1 UDP sockets and the
BytesCodec framing sessions use:
- handshake + bidirectional framed roundtrip + graceful close: the peer
observes end-of-stream instead of hanging (guard outlives the framed
stream so the FIN goes out);
- a writer that queues 50 frames and closes immediately loses none of
them - the client-side pin for the close-tail-drain semantics;
- socket errors after the peer vanishes are treated as loss: writes keep
succeeding, nothing tears down (ICMP is advisory on connected UDP);
- the connect deadline holds when nothing answers.
Mutation-checked: dropping inbound forwarding in kcp_io reddens exactly
the three tests that need the pump, and the timeout test alone stays
green.
Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01ExUfAkYbq8UC9pQCiLy8TQ
The send and recv arms shared one counter, and an ICMP error on a connected
socket is reported once and then cleared — so the steady state is an
alternation: the send succeeds and clears the counter, the next recv reports
the error and finds the counter at 1, and logs. Every error still wrote a
line, at the ~100/s the previous commit set out to stop, while the
persistent-failure and recovery branches were unreachable.
Use one LogThrottle per direction instead of a hand-rolled counter. That
removes the shared state the bug lived in, drops a third throttling mechanism
in favour of the one already added, and leaves the surrounding `if let Err`
untouched rather than reshaping it into a match.
Also fix test_udp_uat's socket-error arm, the untreated twin of the punch_udp
site: it had no backoff at all, so a persistent error re-armed recv
immediately and spun the loop at CPU speed, one warn line per iteration.
Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01ExUfAkYbq8UC9pQCiLy8TQ
Debug output goes to the log file, so a site that fires per received message
or per retry lets someone else decide how much a machine writes to disk. The
WebRTC work added the first such sites.
- KCP io loop: absorbing ICMP errors as packet loss made a broken socket write
~100 lines a second for the 60s until the pong timeout reaps it. Log by run
instead: one line when a run starts, one per ~5s while it persists so a stuck
socket stays visible, and one on recovery with the total.
- punch_udp: the recv error retries every 10ms for up to MAX_TIME, so one line
per occurrence wrote thousands per punch. Log the first, report the count in
the timeout message.
- ICE candidate paths (client, mediator): the peer sets the candidate rate and
the rendezvous route carrying them needs no prior punch, so throttle to one
line a minute each with the suppressed count.
Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01ExUfAkYbq8UC9pQCiLy8TQ
- treat ICMP-driven UDP socket errors (WSAECONNRESET 10054 on Windows,
ECONNREFUSED on Linux) as packet loss in punch_udp and the KCP pump
instead of tearing the session down; KCP retransmits through them and a
truly dead link is still reaped by the pong/app-level timeouts
- resolve STUN hostnames via tokio::net::lookup_host so DNS never blocks a
runtime worker; fix the inverted non-IPv4 error message
- add enable-kcp-congestion-control option (default on): switch the turbo
profile to nc=0 so brief loss on constrained links no longer spirals into
stalls; sender-side only, no wire negotiation
- pin kcp-sys to the rustdesk-patches branch: upstream main lost the
RustDesk patches on the EasyTier sync, and this branch also wires
set_kcp_config_factory into connection setup, making the option effective
Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>
