feat: add HTTP server with OpenAPI docs and token-protected settings for a USB-connected STRIX
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randogoth
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5 changed files with 934 additions and 1 deletions
247
tools/strix_serve.py
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247
tools/strix_serve.py
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#!/usr/bin/env python3
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"""HTTP server for a STRIX connected over USB, with the same routes as the device's own WiFi
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HTTP API (arduino/strix/API.md), so clients work with either.
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The USB port can only be opened by one program, so this server also follows the per-second
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GCP-format trials itself: it polls the device, keeps the last hour in memory for /gcp, adds a
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host timestamp to every record (`time`, Unix time at the start of the second) and can append
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them to a JSON-lines file (--gcp-log). It reconnects after USB dropouts; requests meanwhile
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get status 503.
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With --set-token-file, /set requires the header `Authorization: Bearer <token>`, so the
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server can be exposed publicly without letting anyone change settings.
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/openapi.json serves the OpenAPI description (strix_openapi.json) and /docs a Swagger UI page,
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which loads its scripts from a CDN.
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"""
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import argparse
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import hmac
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import json
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import math
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import threading
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import time
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from collections import deque
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from http.server import BaseHTTPRequestHandler, ThreadingHTTPServer
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from pathlib import Path
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from urllib.parse import parse_qs, urlparse
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import serial
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from strix import MAX_ENTROPY_REQUEST, Device, find_port
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MAX_HTTP_ENTROPY = 1 << 20
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GCP_KEPT = 3600 # seconds of trials served by /gcp
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GCP_POLL_S = 0.5 # also bounds the timestamp error
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RECONNECT_S = 2
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OPENAPI = (Path(__file__).parent / "strix_openapi.json").read_bytes()
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SWAGGER_UI = b"""<!DOCTYPE html>
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<html>
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<head>
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<meta charset="utf-8">
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<title>STRIX HTTP API</title>
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<link rel="stylesheet" href="https://unpkg.com/swagger-ui-dist@5/swagger-ui.css">
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</head>
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<body>
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<div id="swagger-ui"></div>
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<script src="https://unpkg.com/swagger-ui-dist@5/swagger-ui-bundle.js"></script>
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<script>SwaggerUIBundle({url: "openapi.json", dom_id: "#swagger-ui"});</script>
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</body>
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</html>
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"""
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PASSTHROUGH = {"/id": "id", "/health": "health", "/stats": "stats", "/amp": "amp", "/wifi": "wifi",
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"/config": "get"}
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class Unavailable(Exception):
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pass
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class Strix:
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"""The USB connection, shared by request threads and the GCP poller under one lock."""
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def __init__(self, port: str | None, gcp_log: str | None):
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self.port = port
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self.lock = threading.Lock()
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self.device = None
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self.records = deque(maxlen=GCP_KEPT)
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self.last_second = None
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self.reconnected = False
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self.offset = None # host time at the end of second 0
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self.log = open(gcp_log, "a") if gcp_log else None
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def _connected(self) -> Device:
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if self.device is None:
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try:
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device = Device(self.port or find_port())
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# A client that exited without `watch off` leaves the device pushing lines that
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# would be taken for replies.
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device.send("watch off")
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while device.read_line() != '{"ok":true}':
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pass
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except (serial.SerialException, OSError, TimeoutError) as error:
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raise Unavailable(str(error))
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self.device = device
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return self.device
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def call(self, action):
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"""Runs action(device) under the lock; drops the connection on USB errors."""
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with self.lock:
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try:
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return action(self._connected())
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except (serial.SerialException, OSError, TimeoutError) as error:
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if self.device:
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self.device.serial.close()
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self.device = None
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raise Unavailable(str(error))
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def command(self, line: str) -> str:
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def run(device):
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device.send(line)
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return device.read_line()
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return self.call(run)
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def entropy(self, count: int) -> bytes:
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def run(device):
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chunks = []
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while count > sum(map(len, chunks)):
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chunks.append(device.entropy(min(count - sum(map(len, chunks)), MAX_ENTROPY_REQUEST)))
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return b"".join(chunks)
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return self.call(run)
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def poll_gcp(self) -> None:
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reply = json.loads(self.command("gcp" if self.last_second is None else f"gcp {self.last_second}"))
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records = [reply] if "second" in reply else reply.get("records", [])
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if not records and self.reconnected:
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# A board reset restarts its second count, so nothing would ever follow last_second.
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latest = json.loads(self.command("gcp"))
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if latest.get("second", self.last_second) < self.last_second:
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self.last_second = None
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self.reconnected = False
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if not records:
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return
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newest = records[-1]["second"]
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now = time.time()
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# The newest record ended at most one poll interval ago; re-anchor after a device restart.
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if self.offset is None or abs(now - (self.offset + newest)) > 2:
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self.offset = math.floor(now) - newest
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for record in records:
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record = {"time": self.offset + record["second"] - 1, **record}
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self.records.append(record)
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if self.log:
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self.log.write(json.dumps(record) + "\n")
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self.log.flush()
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self.last_second = newest
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self.reconnected = False
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def run_poller(self) -> None:
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while True:
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try:
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self.poll_gcp()
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time.sleep(GCP_POLL_S)
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except Unavailable:
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self.reconnected = self.last_second is not None
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time.sleep(RECONNECT_S)
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except (ValueError, KeyError):
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time.sleep(GCP_POLL_S) # no second completed yet, or a garbled line
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def gcp(self, since: str) -> dict:
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records = list(self.records)
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if not records:
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return {"error": "no second completed yet"}
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if not since:
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return records[-1]
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after = int(since)
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return {"records": [r for r in records if r["second"] > after]}
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class Handler(BaseHTTPRequestHandler):
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strix: Strix
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set_token: str | None = None
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def may_set(self) -> bool:
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if self.set_token is None:
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return True
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given = self.headers.get("Authorization", "")
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return hmac.compare_digest(given.encode(), f"Bearer {self.set_token}".encode())
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def send(self, status: int, body: bytes, kind: str = "application/json") -> None:
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self.send_response(status)
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self.send_header("Content-Type", kind)
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self.send_header("Content-Length", str(len(body)))
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self.send_header("Access-Control-Allow-Origin", "*")
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self.end_headers()
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self.wfile.write(body)
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def send_json(self, value, status: int = 200) -> None:
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self.send(status, (json.dumps(value) + "\n").encode())
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def do_GET(self) -> None:
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url = urlparse(self.path)
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query = {key: values[0] for key, values in parse_qs(url.query).items()}
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try:
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if url.path == "/entropy" or (url.path == "/" and "length" in query):
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self.serve_entropy(query.get("bytes", query.get("length", "")), query.get("format", "hex"))
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elif url.path in PASSTHROUGH:
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self.send(200, (self.strix.command(PASSTHROUGH[url.path]) + "\n").encode())
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elif url.path == "/set" and not self.may_set():
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self.send_json({"error": "unauthorized"}, 401)
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elif url.path == "/set":
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line = f"set {query.get('key', '')} {query.get('value', '')}"
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self.send(200, (self.strix.command(line) + "\n").encode())
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elif url.path == "/gcp":
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self.send_json(self.strix.gcp(query.get("since", "")))
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elif url.path == "/openapi.json":
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self.send(200, OPENAPI)
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elif url.path == "/docs":
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self.send(200, SWAGGER_UI, "text/html; charset=utf-8")
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else:
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self.send_json({"error": "not found"}, 404)
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except Unavailable as error:
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self.send_json({"error": f"device unavailable: {error}"}, 503)
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except ValueError:
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self.send_json({"error": "invalid parameter"})
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def serve_entropy(self, count_text: str, form: str) -> None:
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count = int(count_text)
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if not 1 <= count <= MAX_HTTP_ENTROPY or form not in ("hex", "bin"):
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self.send_json({"error": f"usage: bytes=<1-{MAX_HTTP_ENTROPY}>&format=hex|bin"})
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return
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try:
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data = self.strix.entropy(count)
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except RuntimeError as error: # the device's error reply, e.g. an unhealthy source
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self.send(200, (str(error) + "\n").encode())
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return
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if form == "bin":
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self.send(200, data, "application/octet-stream")
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else:
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self.send(200, (data.hex().upper() + "\n").encode(), "text/plain")
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def log_message(self, format, *args) -> None:
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pass
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def main() -> None:
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parser = argparse.ArgumentParser(description=__doc__, formatter_class=argparse.RawDescriptionHelpFormatter)
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parser.add_argument("--listen", default="127.0.0.1:8080", help="address:port (default 127.0.0.1:8080)")
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parser.add_argument("--port", help="serial port (default: the STRIX board, or STRIX_PORT)")
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parser.add_argument("--gcp-log", help="append every per-second trial to this JSON-lines file")
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parser.add_argument("--set-token-file", help="require this file's token as a bearer token for /set")
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args = parser.parse_args()
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if args.set_token_file:
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with open(args.set_token_file) as token:
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Handler.set_token = token.read().strip()
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if not Handler.set_token:
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parser.error("the set token file is empty")
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Handler.strix = Strix(args.port, args.gcp_log)
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threading.Thread(target=Handler.strix.run_poller, daemon=True).start()
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host, port = args.listen.rsplit(":", 1)
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server = ThreadingHTTPServer((host, int(port)), Handler)
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print(f"serving on http://{host}:{port}", flush=True)
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server.serve_forever()
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if __name__ == "__main__":
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main()
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