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"""The HTTP server: static assets, the theme, and the module API.
It listens only on a Unix socket in a 0700 directory, which `adb reverse`
exposes on the tablet's localhost. A token cookie unlocks the API; a Host and
Origin check keeps arbitrary web pages and DNS rebinding out.
"""
import hmac
import json
import mimetypes
import os
import secrets
import socketserver
import threading
from http.cookies import CookieError, SimpleCookie
from http.server import BaseHTTPRequestHandler, ThreadingHTTPServer
from pathlib import Path
from urllib.parse import parse_qs, urlsplit
from . import config, module, theme
ROOT = Path(__file__).resolve().parent.parent
STATIC = ROOT / "static"
RUNDIR = Path(os.environ.get("XDG_RUNTIME_DIR", f"/run/user/{os.getuid()}")) / "deck-it"
SOCKET = RUNDIR / "http.sock"
CFG = config.load_config()
MONITOR = CFG.get("display", {}).get("name", "TAB")
PORT = CFG.get("ports", {}).get("command_center", 8765)
VNC_PORT = CFG.get("ports", {}).get("display", 5900)
ORIGINS = {f"http://127.0.0.1:{PORT}", f"http://localhost:{PORT}"}
HOSTS = {f"127.0.0.1:{PORT}", f"localhost:{PORT}"}
TOKEN = None
REGISTRY = None
def token_path() -> Path:
return config.user_config_path().parent / "token"
def load_token() -> str:
"""A per-machine secret the tablet's browser holds as a cookie."""
path = token_path()
if not path.is_file():
path.parent.mkdir(parents=True, exist_ok=True)
fd = os.open(path, os.O_WRONLY | os.O_CREAT | os.O_EXCL, 0o600)
with os.fdopen(fd, "w") as f:
f.write(secrets.token_urlsafe(32))
return path.read_text().strip()
class Handler(BaseHTTPRequestHandler):
def _authed(self):
try:
c = SimpleCookie(self.headers.get("Cookie", "")).get("deckit")
except CookieError:
return False
return bool(c and TOKEN and hmac.compare_digest(c.value, TOKEN))
def _trusted(self, write):
if self.headers.get("Host") not in HOSTS:
return False
origin = self.headers.get("Origin")
return origin in ORIGINS if write else origin in (None, *ORIGINS)
def _send(self, code, body=b"", ctype="text/plain", cache=False):
self.send_response(code)
self.send_header("Content-Type", ctype)
self.send_header("Content-Length", str(len(body)))
self.send_header("Cache-Control", "max-age=86400" if cache else "no-store")
self.end_headers()
self.wfile.write(body)
def _json(self, data):
self._send(200, json.dumps(data).encode(), "application/json")
def _unlock(self, given):
if not (TOKEN and hmac.compare_digest(given, TOKEN)):
return False
self.send_response(303)
self.send_header("Location", "/")
self.send_header("Set-Cookie", f"deckit={TOKEN}; Path=/; Max-Age=34560000; HttpOnly; SameSite=Strict")
self.send_header("Content-Length", "0")
self.end_headers()
return True
def do_GET(self):
if not self._trusted(write=False):
return self._send(403)
url = urlsplit(self.path)
path = url.path
if path == "/" and (t := parse_qs(url.query).get("t")) and self._unlock(t[0]):
return
if path == "/theme.css":
return self._send(200, theme.load().encode(), "text/css")
if path.startswith("/api/"):
if not self._authed():
return self._send(401)
parts = path.strip("/").split("/")
if len(parts) == 2 and parts[1] == "modules":
return self._json(REGISTRY.names())
if len(parts) == 2:
try:
return self._json(REGISTRY.state(parts[1]))
except module.ModuleError as e:
return self._send(404, str(e).encode())
return self._send(404)
if path == "/":
path = "/index.html"
file = (STATIC / path.lstrip("/")).resolve()
if file.is_file() and file.is_relative_to(STATIC.resolve()):
ctype = mimetypes.guess_type(file)[0] or "application/octet-stream"
return self._send(200, file.read_bytes(), ctype, cache=file.suffix in (".woff2", ".svg"))
self._send(404)
def do_POST(self):
if not self._trusted(write=True):
return self._send(403)
if not self._authed():
return self._send(401)
parts = urlsplit(self.path).path.strip("/").split("/")
if len(parts) != 3 or parts[0] != "api":
return self._send(404)
_, name, action = parts
try:
fn = REGISTRY.get(name).actions.get(action)
except module.ModuleError as e:
return self._send(404, str(e).encode())
if fn is None:
return self._send(404, b"unknown action")
length = int(self.headers.get("Content-Length", 0) or 0)
if self.headers.get("Content-Type") != "application/json" or not 0 < length <= 4096:
return self._send(400, b"Expected a small JSON body")
try:
result = fn(json.loads(self.rfile.read(length)))
except module.ModuleError as e:
return self._send(400, str(e).encode())
except (ValueError, AttributeError):
return self._send(400, b"Invalid request")
if result is None:
return self._send(204)
return self._json(result)
def log_message(self, *args):
pass
class UnixHTTPServer(socketserver.ThreadingUnixStreamServer):
daemon_threads = True
def serve():
"""Serve the page and API on the Unix socket until killed."""
global TOKEN, REGISTRY
from .modules import build
TOKEN = load_token()
REGISTRY = build(CFG)
REGISTRY.start_all()
RUNDIR.mkdir(mode=0o700, parents=True, exist_ok=True)
RUNDIR.chmod(0o700)
SOCKET.unlink(missing_ok=True)
UnixHTTPServer(str(SOCKET), Handler).serve_forever()
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