ostp/ostp-server
ospab d915efc715 refactor(relay)!: forward transparently instead of re-authenticating clients
The relay authenticated clients itself, with an HMAC handshake and a
background job pulling the access-key list from the target server's management
API. That never worked with a real client and would not have been worth having
if it had.

It could not work: no OSTP client produces those credentials. The TCP path
required an HTTP request (`GET /stream` with `Authorization: Bearer`) and the
UDP path a `timestamp || HMAC` preamble, while the client sends junk frames
followed by length-prefixed frames, and an obfuscated Noise handshake. There
is no HMAC code in ostp-client at all, so every connection was rejected: TCP
answered 404, UDP dropped the datagram.

It was also weak where it applied. The HMAC covered only an 8-byte timestamp,
so a captured signature was a bearer token replayable from any address for the
clock-skew window, with no anti-replay set. And the HTTP handshake put a
literal `GET /stream` on the wire — a greppable signature in a protocol whose
premise is that nothing is recognisable.

Authentication now stays where it is cryptographically meaningful. The target
server already authenticates every session end-to-end via Noise with a PSK
derived from the access key and silently drops what fails; the relay adds
nothing by re-checking, and holding a copy of the key list on a forwarding box
is a liability. The relay makes no security decisions and says so.

What it does need is protection from being a resource sink, so this adds a
session cap, a connection cap, and a token-bucket admission limit on NEW
sessions only. It forwards to one fixed upstream and replies only to the
sender, so it is not a reflector: amplification is one.

Fixes a bug the new end-to-end test caught: upstream sockets were bound as
"[::]:0" and connected to a possibly-IPv4 upstream, which fails wherever
IPV6_V6ONLY defaults on — that is every deployment with an IPv4 target server.
The bind family now follows the resolved upstream.

upstream_api_url/token/sync_interval_secs are accepted and ignored so existing
relay configs keep parsing; the wizard and template no longer emit them, and
`ostp check` flags them as removable.
2026-08-03 18:49:57 +03:00
..
src refactor(relay)!: forward transparently instead of re-authenticating clients 2026-08-03 18:49:57 +03:00
Cargo.toml fix(server): constant-time comparison for Management API secrets 2026-07-18 17:38:09 +03:00