v0.34.3

docs/TRANSPORT.md

@@ -11,6 +11,37 @@ RustProxy distinguishes **frontend** client protocols from the **upstream** prot
 
 Transport settings attach to **named listeners**, and a Vhost must select the appropriate listener IDs. Addresses locked by CLI/systemd startup cannot be rewritten from the panel. Changing a listener bind or startup-owned TLS option may require a restart.
 
+### Saving HTTP/3 settings
+
+- **Immediately after a successful panel save:** H2/H1 TLS responses use the saved `alt_svc_max_age` (`Alt-Svc`), provided a matching UDP listener was actually bound at startup. Origin `Alt-Svc` never passes through. The value `0` publishes `ma=0`.
+- **Disabling H3 on a Vhost or an existing listener:** new H1/H2 responses publish `Alt-Svc: clear` to remove the browser's cached alternative service. A browser may keep an established QUIC connection until it closes; `clear` does not forcibly terminate it.
+- **For new QUIC connections only:** updates to `max_concurrent_bidistream`, `max_concurrent_unistream`, `max_idle_timeout` and reductions to `max_concurrent_connections` are applied without restart. Existing QUIC connections keep their negotiated limits. If no existing UDP socket matches the saved listener address, no H3 is advertised or accepted on the old address.
+- **Restart needed:** UDP listener enable/disable, changing IP/port/TLS properties, UDP socket buffer sizes, changes to H1/H2 listener settings and increasing `max_concurrent_connections` above the startup bound. The live listener status continues to show `restart_required` for these cases. After a restart, the new connection cap can take effect.
+
+
+### QUIC UDP socket buffers (0.34.3)
+
+The HTTP/3 settings of each TLS listener include:
+
+| Parameter | Default | Accepted values | Takes effect |
+|---|---:|---|---|
+| `udp_receive_buffer_bytes` | 4194304 (4 MiB) | `0` (OS default) or 65536–16777216 | On listener restart |
+| `udp_send_buffer_bytes` | 4194304 (4 MiB) | `0` (OS default) or 65536–16777216 | On listener restart |
+
+Use **Settings → HTTP/3** to edit these as whole MiB values (0–16); the JSON API stores bytes. No global `net.core.*_default` adjustment is necessary: RustProxy explicitly sets its own socket options. An OS limit may still clamp the request. Linux doubles `setsockopt(SO_RCVBUF / SO_SNDBUF)` values for bookkeeping; RustProxy targets the final effective size shown as `rb`/`tb` in `ss`.
+
+For a 4 MiB target on Debian/Linux, if the default `net.core.rmem_max` or `net.core.wmem_max` prevents reaching the target, set adequate socket *maxima* after reviewing host memory constraints, for example:
+
+```bash
+sudo sysctl -w net.core.rmem_max=8388608
+sudo sysctl -w net.core.wmem_max=8388608
+sudo systemctl restart rustproxy.service
+sudo ss -uapm | grep -A1 rust-proxy
+```
+
+Read the `HTTP/3 UDP effective socket buffers` startup log message. `ss` should show approximately `rb4194304,tb4194304` (or larger if the OS adjusts values) when the requested size is granted. Changes to the OS maxima alone do not resize an existing socket; the configured buffer size is applied when a QUIC listener starts. High default/maxima for every program are not recommended as a substitute for explicit per-socket configuration. No specific throughput gain is guaranteed; compare H2/H3 at matched traffic before/after.
+
+
 ## Backend protocol selection
 
 | Backend mode | HTTPS origin | Plain HTTP origin |