feat: Add new status page

README.md

@@ -1,4 +1,52 @@
 # HNSDoH Status
-This is a simple webserver to check the status of the Handshake DoH server.
 
-It will check every 5 minutes to see if each node is up and running. It checks the node for plain dns, DNS over HTTPS, and DNS over TLS. For DNS over HTTPS and DNS over TLS, it will check the certificate to make sure it is valid.
+HNSDoH Status is a Flask service that discovers HNSDoH nodes from DNS A records for `hnsdoh.com` and continuously checks each node for:
+
+- DNS over UDP on port 53
+- DNS over TCP on port 53
+- DNS over HTTPS (DoH) on port 443 at `/dns-query`
+- DNS over TLS (DoT) on port 853
+
+For DoH and DoT, TLS certificates are validated with hostname `hnsdoh.com`.
+
+## How It Works
+
+1. Resolve `hnsdoh.com` A records to discover active node IP addresses.
+2. Probe each discovered node for all four protocols.
+3. Keep current status and short in-memory history.
+4. Expose results through a web dashboard and JSON API.
+
+## Run
+
+```bash
+uv sync
+uv run python main.py
+```
+
+The app runs on `0.0.0.0:8000` by default.
+
+## API Endpoints
+
+- `GET /`: HTML status page
+- `GET /api/status`: current snapshot and history
+- `GET /api/health`: service health (503 if stale or no checks yet)
+
+## Configuration
+
+Environment variables:
+
+- `HNSDOH_DOMAIN` (default: `hnsdoh.com`)
+- `HNSDOH_DOH_PATH` (default: `/dns-query`)
+- `HNSDOH_CHECK_INTERVAL_SECONDS` (default: `300`)
+- `HNSDOH_UI_REFRESH_SECONDS` (default: `30`)
+- `HNSDOH_HISTORY_SIZE` (default: `12`)
+- `HNSDOH_STALE_AFTER_SECONDS` (default: `900`)
+- `HNSDOH_DNS_TIMEOUT_SECONDS` (default: `5`)
+- `HNSDOH_DOH_TIMEOUT_SECONDS` (default: `10`)
+- `HNSDOH_DOT_TIMEOUT_SECONDS` (default: `10`)
+
+## Notes
+
+- Discovery uses DNS A records only.
+- DoH check uses RFC8484 DNS wireformat (`application/dns-message`) to each node IP while sending SNI/Host as `hnsdoh.com` for strict certificate hostname verification.
+- History is in-memory and resets on process restart.