[tor-commits] [stem/master] Implementing general authentication
atagar at torproject.org
atagar at torproject.org
Mon Dec 19 01:28:26 UTC 2011
commit def66d45d3cf4c82786fa9a8526a18839fcbf816
Author: Damian Johnson <atagar at torproject.org>
Date: Sun Dec 18 17:25:46 2011 -0800
Implementing general authentication
Finally finished the fabled general authentication function, which uses
PROTOCOLINFO information for authentication. The vast majority of the effort
behind this function was getting the exception hierarchy right.
This is totally untested. Unit and integ testing comes next.
---
stem/connection.py | 216 +++++++++++++++++++++++++++++++++++++++++++++++++++-
1 files changed, 214 insertions(+), 2 deletions(-)
diff --git a/stem/connection.py b/stem/connection.py
index e9bd5f7..ddfed89 100644
--- a/stem/connection.py
+++ b/stem/connection.py
@@ -3,7 +3,10 @@ Functions for connecting and authenticating to the tor process.
AuthenticationFailure - Base exception raised for authentication failures.
|- UnrecognizedAuthMethods - Authentication methods are unsupported.
- |- OpenAuthRejected - Tor rejected this method of authentication.
+ |- IncorrectSocketType - Socket does not speak the tor control protocol.
+ |
+ |- OpenAuthFailed - Failure when authenticating by an open socket.
+ | +- OpenAuthRejected - Tor rejected this method of authentication.
|
|- PasswordAuthFailed - Failure when authenticating by a password.
| |- PasswordAuthRejected - Tor rejected this method of authentication.
@@ -77,8 +80,18 @@ class AuthenticationFailure(Exception):
class UnrecognizedAuthMethods(AuthenticationFailure):
"All methods for authenticating aren't recognized."
+
+ def __init__(self, message, unknown_auth_methods):
+ AuthenticationFailure.__init__(self, message)
+ self.unknown_auth_methods = unknown_auth_methods
+
+class IncorrectSocketType(AuthenticationFailure):
+ "Socket does not speak the control protocol."
-class OpenAuthRejected(AuthenticationFailure):
+class OpenAuthFailed(AuthenticationFailure):
+ "Failure to authenticate to an open socket."
+
+class OpenAuthRejected(OpenAuthFailed):
"Attempt to connect to an open control socket was rejected."
class PasswordAuthFailed(AuthenticationFailure):
@@ -120,6 +133,205 @@ class NoAuthMethods(MissingAuthInfo):
class NoAuthCookie(MissingAuthInfo):
"PROTOCOLINFO response supports cookie auth but doesn't have its path."
+# authentication exceptions ordered as per the authenticate function's pydocs
+AUTHENTICATE_EXCEPTIONS = (
+ IncorrectSocketType,
+ UnrecognizedAuthMethods,
+ MissingPassword,
+ IncorrectPassword,
+ IncorrectCookieSize,
+ UnreadableCookieFile,
+ IncorrectCookieValue,
+ OpenAuthRejected,
+ MissingAuthInfo,
+ AuthenticationFailure,
+)
+
+def authenticate(control_socket, password = None, protocolinfo_response = None):
+ """
+ Authenticates to a control socket using the information provided by a
+ PROTOCOLINFO response. In practice this will often be all we need to
+ authenticate, raising an exception if all attempts to authenticate fail.
+
+ All exceptions are subclasses of AuthenticationFailure so, in practice,
+ callers should catch the types of authentication failure that they care
+ about, then have a AuthenticationFailure catch-all at the end. For example...
+
+ import sys
+ import getpass
+ import stem.connection
+ import stem.socket
+
+ try:
+ control_socket = stem.socket.ControlPort(control_port = 9051)
+ except stem.socket.SocketError, exc:
+ print "Unable to connect to port 9051 (%s)" % exc
+ sys.exit(1)
+
+ try:
+ stem.connection.authenticate(control_socket)
+ except stem.connection.IncorrectSocketType:
+ print "Please check in your torrc that 9051 is the ControlPort."
+ print "Maybe you configured it to be the ORPort or SocksPort instead?"
+ sys.exit(1)
+ except stem.connection.MissingPassword:
+ controller_password = getpass.getpass("Controller password: ")
+
+ try:
+ stem.connection.authenticate_password(control_socket, controller_password)
+ except stem.connection.PasswordAuthFailed:
+ print "Unable to authenticate, password is incorrect"
+ sys.exit(1)
+ except stem.connection.AuthenticationFailure, exc:
+ print "Unable to authenticate: %s" % exc
+ sys.exit(1)
+
+ Arguments:
+ control_socket (stem.socket.ControlSocket) - socket to be authenticated
+ password (str) - passphrase to present to the socket if it uses password
+ authentication (skips password auth if None)
+ protocolinfo_response (stem.connection.ProtocolInfoResponse) -
+ tor protocolinfo response, this is retrieved on our own if None
+
+ Raises:
+ AuthenticationFailed subclass if all attempts to authenticate fail. Since
+ this may try multiple authentication methods it may encounter multiple
+ exceptions. If so then the exception this raises is prioritized as
+ follows...
+
+ stem.connection.IncorrectSocketType
+ The control_socket does not speak the tor control protocol. Most often
+ this happened because the user confused the SocksPort or ORPort with the
+ ControlPort.
+
+ stem.connection.UnrecognizedAuthMethods
+ All of the authentication methods tor will accept are new and
+ unrecognized. Please upgrade stem and, if that doesn't work, file a
+ ticket on 'trac.torproject.org' and I'd be happy to add support.
+
+ stem.connection.MissingPassword
+ We were unable to authenticate but didn't attempt password authentication
+ because none was provided. You should prompt the user for a password and
+ try again via 'authenticate_password'.
+
+ stem.connection.IncorrectPassword
+ We were provided with a password but it was incorrect.
+
+ stem.connection.IncorrectCookieSize
+ Tor allows for authentication by reading it a cookie file, but that file
+ is the wrong size to be an authentication cookie.
+
+ stem.connection.UnreadableCookieFile
+ Tor allows for authentication by reading it a cookie file, but we can't
+ read that file (probaby due to permissions).
+
+ stem.connection.IncorrectCookieValue (*)
+ Tor allows for authentication by reading it a cookie file, but rejected
+ the contents of that file.
+
+ stem.connection.OpenAuthRejected (*)
+ Tor says that it allows for authentication without any credentials, but
+ then rejected our authentication attempt.
+
+ stem.connection.MissingAuthInfo (*)
+ Tor provided us with a PROTOCOLINFO reply that is technically valid, but
+ missing the information we need to authenticate.
+
+ stem.connection.AuthenticationFailure (*)
+ There are numerous other ways that authentication could have failed
+ including socket failures, malformed controller responses, etc. These
+ mostly constitute transient failures or bugs.
+
+ * In practice it is highly unusual for this to occure, being more of a
+ theoretical possability rather than something you should expect. It's
+ fine to treat these as errors. If you have a use case where this commonly
+ happens, please file a ticket on 'trac.torproject.org'.
+
+ In the future new AuthenticationFailure subclasses may be added to allow
+ for better error handling.
+ """
+
+ if not protocolinfo_response:
+ try:
+ protocolinfo_response = get_protocolinfo(control_socket)
+ except stem.socket.ProtocolError:
+ raise IncorrectSocketType("unable to use the control socket")
+ except stem.socket.SocketError, exc:
+ raise AuthenticationFailure("socket connection failed (%s)" % exc)
+
+ auth_methods = list(protocolinfo_response.auth_methods)
+ auth_exceptions = []
+
+ if len(auth_methods) == 0:
+ raise NoAuthMethods("our PROTOCOLINFO response did not have any methods for authenticating")
+
+ # remove authentication methods that are either unknown or for which we don't
+ # have an input
+ if AuthMethod.UNKNOWN in auth_methods:
+ auth_methods.remove(AuthMethod.UNKNOWN)
+
+ unknown_methods = protocolinfo_response.unknown_auth_methods
+ plural_label = "s" if len(unknown_methods) > 1 else ""
+ methods_label = ", ".join(unknown_methods)
+
+ # we... er, can't do anything with only unrecognized auth types
+ if not auth_methods:
+ exc_msg = "unrecognized authentication method%s (%s)" % (plural_label, methods_label)
+ auth_exceptions.append(UnrecognizedAuthMethods(exc_msg, unknown_methods))
+ else:
+ LOGGER.debug("Authenticating to a socket with unrecognized auth method%s, ignoring them: %s" % (plural_label, methods_label))
+
+ if AuthMethod.COOKIE in auth_methods and protocolinfo_response.cookie_path == None:
+ auth_methods.remove(AuthMethod.COOKIE)
+ auth_exceptions.append(NoAuthCookie("our PROTOCOLINFO reponse did not have the location of our authentication cookie"))
+
+ if AuthMethod.PASSWORD in auth_methods and password == None:
+ auth_methods.remove(AuthMethod.PASSWORD)
+ auth_exceptions.append(MissingPassword("no passphrase provided"))
+
+ # iterating over AuthMethods so we can try them in this order
+ for auth_type in (AuthMethod.NONE, AuthMethod.PASSWORD, AuthMethod.COOKIE):
+ if not auth_type in auth_methods: continue
+
+ try:
+ if auth_type == AuthMethod.NONE:
+ authenticate_none(control_socket, False)
+ elif auth_type == AuthMethod.PASSWORD:
+ authenticate_password(control_socket, password, False)
+ elif auth_type == AuthMethod.COOKIE:
+ authenticate_cookie(control_socket, protocolinfo_response.cookie_path, False)
+
+ return # success!
+ except OpenAuthRejected, exc:
+ auth_exceptions.append(exc)
+ except IncorrectPassword, exc:
+ auth_exceptions.append(exc)
+ except PasswordAuthRejected, exc:
+ # Since the PROTOCOLINFO says password auth is available we can assume
+ # that if PasswordAuthRejected is raised it's being raised in error.
+ LOGGER.debug("The authenticate_password method raised a PasswordAuthRejected when password auth should be available. Stem may need to be corrected to recognize this response: %s" % exc)
+ auth_exceptions.append(IncorrectPassword(str(exc)))
+ except (IncorrectCookieSize, UnreadableCookieFile, IncorrectCookieValue), exc:
+ auth_exceptions.append(exc)
+ except CookieAuthRejected, exc:
+ LOGGER.debug("The authenticate_cookie method raised a CookieAuthRejected when cookie auth should be available. Stem may need to be corrected to recognize this response: %s" % exc)
+ auth_exceptions.append(IncorrectCookieValue(str(exc)))
+ except stem.socket.ControllerError, exc:
+ auth_exceptions.append(AuthenticationFailure(str(exc)))
+
+ # All authentication attempts failed. Raise the exception that takes priority
+ # according to our pydocs.
+
+ for exc_type in AUTHENTICATE_EXCEPTIONS:
+ for auth_exc in auth_exceptions:
+ if isinstance(auth_exc, exc_type):
+ raise auth_exc
+
+ # We really, really shouldn't get here. It means that auth_exceptions is
+ # either empty or contains something that isn't an AuthenticationFailure.
+
+ raise AssertionError("BUG: Authenticaion failed without providing a recognized exception: %s" % str(auth_exceptions))
+
def authenticate_none(control_socket, suppress_ctl_errors = True):
"""
Authenticates to an open control socket. All control connections need to
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