# -*- test-case-name: twisted.cred.test.test_cred -*- # Copyright (c) Twisted Matrix Laboratories. # See LICENSE for details. from __future__ import division, absolute_import import os from zope.interface import implementer, Interface, Attribute from twisted.logger import Logger from twisted.internet import defer from twisted.python import failure from twisted.cred import error, credentials class ICredentialsChecker(Interface): """ An object that can check sub-interfaces of ICredentials. """ credentialInterfaces = Attribute( 'A list of sub-interfaces of ICredentials which specifies which I may check.') def requestAvatarId(credentials): """ @param credentials: something which implements one of the interfaces in self.credentialInterfaces. @return: a Deferred which will fire a string which identifies an avatar, an empty tuple to specify an authenticated anonymous user (provided as checkers.ANONYMOUS) or fire a Failure(UnauthorizedLogin). Alternatively, return the result itself. @see: L{twisted.cred.credentials} """ # A note on anonymity - We do not want None as the value for anonymous # because it is too easy to accidentally return it. We do not want the # empty string, because it is too easy to mistype a password file. For # example, an .htpasswd file may contain the lines: ['hello:asdf', # 'world:asdf', 'goodbye', ':world']. This misconfiguration will have an # ill effect in any case, but accidentally granting anonymous access is a # worse failure mode than simply granting access to an untypeable # username. We do not want an instance of 'object', because that would # create potential problems with persistence. ANONYMOUS = () @implementer(ICredentialsChecker) class AllowAnonymousAccess: credentialInterfaces = credentials.IAnonymous, def requestAvatarId(self, credentials): return defer.succeed(ANONYMOUS) @implementer(ICredentialsChecker) class InMemoryUsernamePasswordDatabaseDontUse(object): """ An extremely simple credentials checker. This is only of use in one-off test programs or examples which don't want to focus too much on how credentials are verified. You really don't want to use this for anything else. It is, at best, a toy. If you need a simple credentials checker for a real application, see L{FilePasswordDB}. """ credentialInterfaces = (credentials.IUsernamePassword, credentials.IUsernameHashedPassword) def __init__(self, **users): self.users = {x.encode('ascii'):y for x, y in users.items()} def addUser(self, username, password): self.users[username] = password def _cbPasswordMatch(self, matched, username): if matched: return username else: return failure.Failure(error.UnauthorizedLogin()) def requestAvatarId(self, credentials): if credentials.username in self.users: return defer.maybeDeferred( credentials.checkPassword, self.users[credentials.username]).addCallback( self._cbPasswordMatch, credentials.username) else: return defer.fail(error.UnauthorizedLogin()) @implementer(ICredentialsChecker) class FilePasswordDB: """ A file-based, text-based username/password database. Records in the datafile for this class are delimited by a particular string. The username appears in a fixed field of the columns delimited by this string, as does the password. Both fields are specifiable. If the passwords are not stored plaintext, a hash function must be supplied to convert plaintext passwords to the form stored on disk and this CredentialsChecker will only be able to check IUsernamePassword credentials. If the passwords are stored plaintext, IUsernameHashedPassword credentials will be checkable as well. """ cache = False _credCache = None _cacheTimestamp = 0 _log = Logger() def __init__(self, filename, delim=b':', usernameField=0, passwordField=1, caseSensitive=True, hash=None, cache=False): """ @type filename: C{str} @param filename: The name of the file from which to read username and password information. @type delim: C{str} @param delim: The field delimiter used in the file. @type usernameField: C{int} @param usernameField: The index of the username after splitting a line on the delimiter. @type passwordField: C{int} @param passwordField: The index of the password after splitting a line on the delimiter. @type caseSensitive: C{bool} @param caseSensitive: If true, consider the case of the username when performing a lookup. Ignore it otherwise. @type hash: Three-argument callable or L{None} @param hash: A function used to transform the plaintext password received over the network to a format suitable for comparison against the version stored on disk. The arguments to the callable are the username, the network-supplied password, and the in-file version of the password. If the return value compares equal to the version stored on disk, the credentials are accepted. @type cache: C{bool} @param cache: If true, maintain an in-memory cache of the contents of the password file. On lookups, the mtime of the file will be checked, and the file will only be re-parsed if the mtime is newer than when the cache was generated. """ self.filename = filename self.delim = delim self.ufield = usernameField self.pfield = passwordField self.caseSensitive = caseSensitive self.hash = hash self.cache = cache if self.hash is None: # The passwords are stored plaintext. We can support both # plaintext and hashed passwords received over the network. self.credentialInterfaces = ( credentials.IUsernamePassword, credentials.IUsernameHashedPassword ) else: # The passwords are hashed on disk. We can support only # plaintext passwords received over the network. self.credentialInterfaces = ( credentials.IUsernamePassword, ) def __getstate__(self): d = dict(vars(self)) for k in '_credCache', '_cacheTimestamp': try: del d[k] except KeyError: pass return d def _cbPasswordMatch(self, matched, username): if matched: return username else: return failure.Failure(error.UnauthorizedLogin()) def _loadCredentials(self): """ Loads the credentials from the configured file. @return: An iterable of C{username, password} couples. @rtype: C{iterable} @raise UnauthorizedLogin: when failing to read the credentials from the file. """ try: with open(self.filename, "rb") as f: for line in f: line = line.rstrip() parts = line.split(self.delim) if self.ufield >= len(parts) or self.pfield >= len(parts): continue if self.caseSensitive: yield parts[self.ufield], parts[self.pfield] else: yield parts[self.ufield].lower(), parts[self.pfield] except IOError as e: self._log.error("Unable to load credentials db: {e!r}", e=e) raise error.UnauthorizedLogin() def getUser(self, username): if not self.caseSensitive: username = username.lower() if self.cache: if self._credCache is None or os.path.getmtime(self.filename) > self._cacheTimestamp: self._cacheTimestamp = os.path.getmtime(self.filename) self._credCache = dict(self._loadCredentials()) return username, self._credCache[username] else: for u, p in self._loadCredentials(): if u == username: return u, p raise KeyError(username) def requestAvatarId(self, c): try: u, p = self.getUser(c.username) except KeyError: return defer.fail(error.UnauthorizedLogin()) else: up = credentials.IUsernamePassword(c, None) if self.hash: if up is not None: h = self.hash(up.username, up.password, p) if h == p: return defer.succeed(u) return defer.fail(error.UnauthorizedLogin()) else: return defer.maybeDeferred(c.checkPassword, p ).addCallback(self._cbPasswordMatch, u) # For backwards compatibility # Allow access as the old name. OnDiskUsernamePasswordDatabase = FilePasswordDB