import re import logging import hashlib import hmac from datetime import datetime from owrx.config import Config logger = logging.getLogger(__name__) keyRegex = re.compile("^([a-zA-Z]+)-([0-9a-f]{32})-([0-9a-f]{64})$") keyChallengeRegex = re.compile("^([a-zA-Z]+)-([0-9a-f]{32})-([0-9a-f]{32})$") headerRegex = re.compile("^ReceiverId (.*)$") class KeyException(Exception): pass class Key(object): def __init__(self, keyString): matches = keyRegex.match(keyString) if not matches: raise KeyException("invalid key format") self.source = matches.group(1) self.id = matches.group(2) self.secret = matches.group(3) class KeyChallenge(object): def __init__(self, challengeString): matches = keyChallengeRegex.match(challengeString) if not matches: raise KeyException("invalid key challenge format") self.source = matches.group(1) self.id = matches.group(2) self.challenge = matches.group(3) class KeyResponse(object): def __str__(self): return "TODO" class ReceiverId(object): @staticmethod def getResponseHeader(requestHeader): matches = headerRegex.match(requestHeader) if not matches: raise KeyException("invalid authorization header") challenge = KeyChallenge(matches.group(1)) key = ReceiverId.findKey(challenge) if key is None: return {} time, signature = ReceiverId.signChallenge(challenge, key) return { "Signature": signature, "Time": time, } @staticmethod def findKey(challenge): def parseKey(keyString): try: return Key(keyString) except KeyException as e: logger.error(e) keys = [parseKey(keyString) for keyString in Config.get()['receiver_keys']] keys = [key for key in keys if key is not None] matching_keys = [key for key in keys if key.source == challenge.source and key.id == challenge.id] if matching_keys: return matching_keys[0] return None @staticmethod def signChallenge(challenge, key): now = datetime.utcnow().isoformat() signString = "{challenge}:{time}".format(challenge=challenge.challenge, time=now) m = hmac.new(bytes.fromhex(key.secret), msg=signString.encode('utf8'), digestmod=hashlib.sha256) return now, m.hexdigest()