import asyncio
import base64
import hashlib
import hmac
from http.cookies import SimpleCookie
import json
import urllib.request
SALT = "datasette-auth-github"
class BadSignature(Exception):
pass
class Signer:
def __init__(self, secret):
self.secret = secret
def signature(self, value):
return (
base64.urlsafe_b64encode(salted_hmac(SALT, value, self.secret).digest())
.strip(b"=")
.decode()
)
def sign(self, value):
return "{}:{}".format(value, self.signature(value))
def unsign(self, signed_value):
if ":" not in signed_value:
raise BadSignature("No : found")
value, signature = signed_value.rsplit(":", 1)
if hmac.compare_digest(signature, self.signature(value)):
return value
raise BadSignature("Signature does not match")
async def send_html(send, html, status=200, headers=None):
headers = headers or []
if "content-type" not in [h.lower() for h, v in headers]:
headers.append(["content-type", "text/html; charset=UTF-8"])
await send(
{
"type": "http.response.start",
"status": status,
"headers": [
[key.encode("utf8"), value.encode("utf8")] for key, value in headers
],
}
)
await send({"type": "http.response.body", "body": html.encode("utf8")})
async def http_request(url, body=None, headers=None):
"Performs POST if body provided, GET otherwise."
headers = headers or {}
def _request():
message = urllib.request.urlopen(urllib.request.Request(url, body, headers))
return message.status, tuple(message.headers.raw_items()), message.read()
loop = asyncio.get_event_loop()
status_code, headers, body = await loop.run_in_executor(None, _request)
return Response(status_code, headers, body)
class Response:
"Wrapper class making HTTP responses easier to work with"
def __init__(self, status_code, headers, body):
self.status_code = status_code
self.headers = headers
self.body = body
def json(self):
return json.loads(self.text)
@property
def text(self):
# Should decode according to Content-Type, for the moment assumes utf8
return self.body.decode("utf-8")
def ensure_bytes(s):
if not isinstance(s, bytes):
return s.encode("utf-8")
else:
return s
def force_list(value):
if isinstance(value, str):
return [value]
return value
def salted_hmac(salt, value, secret):
salt = ensure_bytes(salt)
secret = ensure_bytes(secret)
key = hashlib.sha1(salt + secret).digest()
return hmac.new(key, msg=ensure_bytes(value), digestmod=hashlib.sha1)
def cookies_from_scope(scope):
cookie = dict(scope.get("headers") or {}).get(b"cookie")
if not cookie:
return {}
simple_cookie = SimpleCookie()
simple_cookie.load(cookie.decode("utf8"))
return {key: morsel.value for key, morsel in simple_cookie.items()}
