Mailman 3 September 2009 - Twisted

[Twisted-Python] Weekly Bug Summary
by exarkun＠twistedmatrix.com 06 Sep '09

06 Sep '09

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[Twisted-Python] Looping in a deffered
by John Joske 05 Sep '09

05 Sep '09

I'm trying to make a simple deferred that will continue get a message of a message queue, process it and then wait for another message. While I can get the first message easily I am unable to work out how I can get a second message without creating a new deferred in the printMsg function, which eventually gives me a maximum recursion depth exceeded. Basic code is a follows: from twisted.internet import reactor,defer def printMsg(msg): print "Message is:" print msg deferred=getMsg() deferred.addCallback(printMsg) def getMsg() : d=defer.Deferred() #replaced with code that actually goes to a queue to get the message msg="This is a message" d.callback(msg) return d deferred=getMsg() deferred.addCallback(printMsg) reactor.run() Can any one point me on the right path to solve this? Thanks John

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[Twisted-Python] Is there an equivalent of tap2deb?
by Peter Westlake 05 Sep '09

05 Sep '09

Now that .tap files are obsolete, is there a supported way of making Debian packages like tap2dep? Thanks, Peter.

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[Twisted-Python] Installing twisted on Snow Leopard with custom 32-bit Python from python.org
by Nathan 05 Sep '09

05 Sep '09

I've installed the 32-bit Python on Snow Leopard (for various reasons unrelated to twisted) and would like to get twisted working with it. I've tried downloading twisted and running the standard "sudo python setup.py install" -- but that seems to simply install it in the system Python installation. How can I get twisted installed where the Python installation that I got from python.org can use it? ~ Nathan

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[Twisted-Python] Conch/SSH & Cisco IOS
by Phil Mayers 04 Sep '09

04 Sep '09

All, I've been having some problems using Conch/SSH to talk to the SSH server on Cisco IOS (specifically the netconf subsystem) It seems that the IOS SSH server reacts badly to the following: c: syn s: syn,ack c: ack c: PSH <my version>, <my kex> s: PSH <ios version> <hang> i.e. IOS doesn't like being bombarded with either the version string or KEX before it's sent its own banner. I've patched this locally by overriding connectionMade to be a noop and re-implementing dataReceived; but if I prepare a patch would it be accepted? If not, could I prepare a patch factoring some of this logic out so it can be more easily overridden?

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[Twisted-Python] twisted.positioning: storing the error information
by Laurens Van Houtven 03 Sep '09

03 Sep '09

-----BEGIN PGP SIGNED MESSAGE----- Hash: SHA1 Hi, First of all, sorry for the lack of promised gpsd support updates yesterday, I was in bed with the flu (and still am, I guess -- it's just slightly less bad than yesterday), so if I'm not making any sense, blame me being delirious. As you might know t.positioning currently has one object for storing a bunch of errors, and the IPositioningReceiver interface describes one method (positioningErrorReceived) for receiving such an error object. Coming from NMEA (which only reports HDOP VDOP and PDOP), putting all of it in one object made sense -- there is an obvious mathematical relation between the three, so in case one is missing we can calculate it, and that's exactly what t.p.base.PositioningError does. For more information as to what all these xDOPs are, see: http://en.wikipedia.org/wiki/Dilution_of_precision_%28GPS%29. Quick introduction (skip this paragraph if you already know what xDOP means): HDOP is the relative imprecision (expressed in the value times the reference imprecision, which depends on the device) on latitude and longitude. Suppose the device has a reference imprecision of 1 meter and the HDOP is 5, you know where you are (lat/lon wise) within a five meter radius. Similarly, VDOP gives you an idea of your altitude. Suppose the device normally provides altitude precisions up to one meter, and the VDOP is 5, you know where you are altitude-wise on a 5 meter line. PDOP is the euclidian norm of the (HDOP, VDOP) vector, and as such is slightly less useful as something directly translatable to an error measurement (it's the radius of a sphere... sort of) but more of a relative measure of goodness-of-fix. Anyway, the problem is this. Now that I'm implementing GPSD support, I've noticed that it's perfectly sensible to have your positioning source report all sorts of errors: climb error estimates, time error estimates, position error estimates... (all of these measured in meters, m/s, degrees/second... instead of relative values). This was actually the original idea, and I think it was only dropped because it was hard to do with NMEA. However, if there's anything I've learned about NMEA it's that the less your public API looks like it probably the better, so perhaps we should change how this works? Maybe we could have a bunch of separate kinds of errors, and supply them with that information. The NMEAAdapter, which does not provide such error estimates yet (in most cases) could provide dummy error reports with all relevant error attributes set to None. (This could be elegantly done by simply seeding self._state). Splitting all of this up isn't incredibly easy though. Obviously HDOP (as well as XDOP/YDOP, which apparently will be reported separately in NMEA3.0) is related to the position and VDOP is related to the altitude. Where do you put PDOP, though? Thanks in advance for your thoughts Laurens -----BEGIN PGP SIGNATURE----- Version: GnuPG v1.4.9 (GNU/Linux) Comment: Use GnuPG with Firefox : http://getfiregpg.org (Version: 0.7.8) iEYEARECAAYFAkqfqegACgkQT5v5zGkvKT74qgCfY2ok9rcFkhpoRU4+f6DIOGot 1t4AoL1n9rb9OUxOwMTuojaiBMlWLG35 =lEq+ -----END PGP SIGNATURE-----

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[Twisted-Python] connecting through an http proxy
by Salil 03 Sep '09

03 Sep '09

First of let me say that I'm *very* new to twisted (I'm only trying to patch an app that uses twisted). So sorry if this is a stupid question. The problem is I am behind an http proxy (with authentication), so I need to connect through that proxy. The documentation doesn't help (me) much and neither does google (mostly because there are a million people who have created their own proxy server. This is not what I want to do). Any tips? The app is currently using ClientCreator (to make an SSL connection), but I'm willing to change all that if necessary. Thanks

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[Twisted-Python] Telnet server using Twisted and AuthenticatingTelnetProtocol
by filoufake-python＠yahoo.fr 02 Sep '09

02 Sep '09

Hello, I have created a telnet server in python. Maybe you wonder why to create a telnet server while Windows has one? Because the windows telnet server does not allow to interract with the desktop. If you try to start a GUI app, it will start and run but will not be displayed on the server desktop. My telnet server will allow to start a GUI application interracting with the windows desktop of the server. Ex. : typing "notepad" in the telnet console will pop up the notepad on the Windows desktop of the server. At the time this server works but has no authentication feature implemented. I would like to implement the authentication using AuthenticatingTelnetProtocol and credential. I found the "cred.py" example on the twistedmatrix website (in the example section) and looked fine as starting point. I quite well understand this expample. I modified the code as follow but always got the same error message when a connectiion is attempted. I have been trying since two weeks but I cannot get it work. Is there a problem with "AuthenticatingTelnetProtocol" The error message: ************************************************************ D:\workspace\twisted>telnet_cred.py 2009-08-20 08:57:11+0200 [-] Log opened. 2009-08-20 08:57:11+0200 [-] __main__.ServerFactory starting on 4738 2009-08-20 08:57:11+0200 [-] Starting factory <__main__.ServerFactory instance at 0x00D79C60> 2009-08-20 08:57:15+0200 [__main__.ServerFactory] DEBUG: buildProtocol - addr IPv4Address(TCP, '127.0.0.1', 4978) 2009-08-20 08:57:15+0200 [__main__.ServerFactory] Unhandled Error Traceback (most recent call last): File "C:\Python25\lib\site-packages\twisted\python\log.py", line 69, in callWithContext return context.call({ILogContext: newCtx}, func, *args, **kw) File "C:\Python25\lib\site-packages\twisted\python\context.py", line 59, in callWithContext return self.currentContext().callWithContext(ctx, func, *args, **kw) File "C:\Python25\lib\site-packages\twisted\python\context.py", line 37, in callWithContext return func(*args,**kw) File "C:\Python25\lib\site-packages\twisted\internet\selectreactor.py", line 146, in _doReadOrWrite why = getattr(selectable, method)() --- <exception caught here> --- File "C:\Python25\lib\site-packages\twisted\internet\tcp.py", line 932, in doRead protocol = self.factory.buildProtocol(self._buildAddr(addr)) File "D:\workspace\twisted\telnet_cred.py", line 130, in buildProtocol p = protocol.ServerFactory.buildProtocol(self, addr) File "C:\Python25\lib\site-packages\twisted\internet\protocol.py", line 98, in buildProtocol p = self.protocol() exceptions.TypeError: __init__() takes exactly 2 arguments (1 given) ************************************************************ The modified code: ************************************************************ # Copyright (c) 2001-2004 Twisted Matrix Laboratories. # See LICENSE for details. import sys from zope.interface import implements, Interface from twisted.protocols import basic from twisted.internet import protocol from twisted.python import log from twisted.cred import error from twisted.cred import portal from twisted.cred import checkers from twisted.cred import credentials from twisted.conch.telnet import AuthenticatingTelnetProtocol, ITelnetProtocol, TelnetProtocol class IProtocolUser(Interface): def getPrivileges(): """Return a list of privileges this user has.""" def logout(): """Cleanup per-login resources allocated to this avatar""" class AnonymousUser: implements(IProtocolUser) def getPrivileges(self): return [1, 2, 3] def logout(self): print "Cleaning up anonymous user resources" class RegularUser: implements(IProtocolUser) def getPrivileges(self): return [1, 2, 3, 5, 6] def logout(self): print "Cleaning up regular user resources" class Administrator: implements(IProtocolUser) def getPrivileges(self): return range(50) def logout(self): print "Cleaning up administrator resources" class Protocol(basic.LineReceiver): user = None portal = None avatar = None logout = None def connectionMade(self): self.sendLine("Login with USER <name> followed by PASS <password> or ANON") self.sendLine("Check privileges with PRIVS") def connectionLost(self, reason): if self.logout: self.logout() self.avatar = None self.logout = None def lineReceived(self, line): f = getattr(self, 'cmd_' + line.upper().split()[0]) if f: try: f(*line.split()[1:]) except TypeError: self.sendLine("Wrong number of arguments.") except: self.sendLine("Server error (probably your fault)") def cmd_ANON(self): if self.portal: self.portal.login(credentials.Anonymous(), None, IProtocolUser ).addCallbacks(self._cbLogin, self._ebLogin ) else: self.sendLine("DENIED") def cmd_USER(self, name): self.user = name self.sendLine("Alright. Now PASS?") def cmd_PASS(self, password): if not self.user: self.sendLine("USER required before PASS") else: if self.portal: self.portal.login( credentials.UsernamePassword(self.user, password), None, IProtocolUser ).addCallbacks(self._cbLogin, self._ebLogin ) else: self.sendLine("DENIED") def cmd_PRIVS(self): self.sendLine("You have the following privileges: ") self.sendLine(" ".join(map(str, self.avatar.getPrivileges()))) def _cbLogin(self, (interface, avatar, logout)): assert interface is IProtocolUser self.avatar = avatar self.logout = logout self.sendLine("Login successful. Available commands: PRIVS") def _ebLogin(self, failure): failure.trap(error.UnauthorizedLogin) self.sendLine("Login denied! Go away.") class ServerFactory(protocol.ServerFactory): ## protocol = Protocol protocol = AuthenticatingTelnetProtocol def __init__(self, portal): self.portal = portal def buildProtocol(self, addr): print "DEBUG: buildProtocol - addr", addr p = protocol.ServerFactory.buildProtocol(self, addr) print "DEBUG2: buildProtocol - addr", addr p.portal = self.portal return p class Realm: implements(portal.IRealm) def requestAvatar(self, avatarId, mind, *interfaces): if IProtocolUser in interfaces: if avatarId == checkers.ANONYMOUS: av = AnonymousUser() elif avatarId.isupper(): # Capitalized usernames are administrators. av = Administrator() else: av = RegularUser() return IProtocolUser, av, av.logout elif ITelnetProtocol in interfaces: print "BEGUG: aaaa" if avatarId.isupper(): av = TelnetProtocol() return ITelnetProtocol, av, None raise NotImplementedError("Only IProtocolUser interface is supported by this realm") def main(): r = Realm() p = portal.Portal(r) c = checkers.InMemoryUsernamePasswordDatabaseDontUse() c.addUser("auser", "thepass") c.addUser("SECONDUSER", "secret") p.registerChecker(c) p.registerChecker(checkers.AllowAnonymousAccess()) f = ServerFactory(p) log.startLogging(sys.stdout) from twisted.internet import reactor reactor.listenTCP(4738, f) reactor.run() if __name__ == '__main__': main() ************************************************************ If someone could help me. Philippe

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[Twisted-Python] twistd plugin or .tac file?
by Martin-Louis Bright 02 Sep '09

02 Sep '09

hi! Which is the recommended or preferred way to deploy an app that will leverage twistd: designing the app as a twistd plugin or creating a Service and using a .tac file? Also, if you need to expose your functionality as a Service to properly use the twisted application framework, how do you achieve this if your app doesn't need a network port? -martin

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[Twisted-Python] TDD using Trial
by Nathan Lundquist 02 Sep '09

02 Sep '09

Hello everyone. I was wondering if any tutorials existed for setting up unit tests for use with trial. I've done a fair share of googling and only found tickets suggesting that more documentation be made available for trial. I've been attempting to make sense of the tests that ship with twisted but to be honest I'm having a hard. Just thought a tutorial that walks through and explains things would help a lot. Thanks.

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