# -*- test-case-name: twisted.test.test_ident -*- # Copyright (c) 2001-2004 Twisted Matrix Laboratories. # See LICENSE for details. """ Ident protocol implementation. API Stability: Unstable @author: U{Jp Calderone} """ from __future__ import generators import struct from twisted.internet import defer from twisted.protocols import basic from twisted.python import log class IdentError(Exception): """ Can't determine connection owner; reason unknown. """ identDescription = 'UNKNOWN-ERROR' def __str__(self): return self.identDescription class NoUser(IdentError): """ The connection specified by the port pair is not currently in use or currently not owned by an identifiable entity. """ identDescription = 'NO-USER' class InvalidPort(IdentError): """ Either the local or foreign port was improperly specified. This should be returned if either or both of the port ids were out of range (TCP port numbers are from 1-65535), negative integers, reals or in any fashion not recognized as a non-negative integer. """ identDescription = 'INVALID-PORT' class HiddenUser(IdentError): """ The server was able to identify the user of this port, but the information was not returned at the request of the user. """ identDescription = 'HIDDEN-USER' class IdentServer(basic.LineOnlyReceiver): """ The Identification Protocol (a.k.a., "ident", a.k.a., "the Ident Protocol") provides a means to determine the identity of a user of a particular TCP connection. Given a TCP port number pair, it returns a character string which identifies the owner of that connection on the server's system. Server authors should subclass this class and override the lookup method. The default implementation returns an UNKNOWN-ERROR response for every query. """ def lineReceived(self, line): parts = line.split(',') if len(parts) != 2: self.invalidQuery() else: try: portOnServer, portOnClient = map(int, parts) except ValueError: self.invalidQuery() else: self.validQuery(portOnServer, portOnClient) def invalidQuery(self): self.transport.loseConnection() def validQuery(self, portOnServer, portOnClient): serverAddr = self.transport.getHost()[1], portOnServer clientAddr = self.transport.getPeer()[1], portOnClient defer.maybeDeferred(self.lookup, serverAddr, clientAddr ).addCallback(self._cbLookup, portOnServer, portOnClient ).addErrback(self._ebLookup, portOnServer, portOnClient ) def _cbLookup(self, (sysName, userId), sport, cport): self.sendLine('%d, %d : USERID : %s : %s' % (sport, cport, sysName, userId)) def _ebLookup(self, failure, sport, cport): if failure.check(IdentError): self.sendLine('%d, %d : ERROR : %s' % (sport, cport, failure.value)) else: log.err(failure) self.sendLine('%d, %d : ERROR : %s' % (sport, cport, IdentError(failure.value))) def lookup(self, serverAddress, clientAddress): """Lookup user information about the specified address pair. Return value should be a two-tuple of system name and username. Acceptable values for the system name may be found online at This method may also raise any IdentError subclass (or IdentError itself) to indicate user information will not be provided for the given query. A Deferred may also be returned. @param serverAddress: A two-tuple representing the server endpoint of the address being queried. The first element is a string holding a dotted-quad IP address. The second element is an integer representing the port. @param clientAddress: Like L{serverAddress}, but represents the client endpoint of the address being queried. """ raise IdentError() class ProcServerMixin: """Implements lookup() to grab entries for responses from /proc/net/tcp """ SYSTEM_NAME = 'LINUX' try: from pwd import getpwuid def getUsername(self, uid, getpwuid=getpwuid): return getpwuid(uid)[0] del getpwuid except ImportError: def getUsername(self, uid): raise IdentError() def entries(self): f = file('/proc/net/tcp') f.readline() for L in f: yield L.strip() def dottedQuadFromHexString(self, hexstr): return '.'.join(map(str, struct.unpack('4B', struct.pack('=L', int(hexstr, 16))))) def unpackAddress(self, packed): addr, port = packed.split(':') addr = self.dottedQuadFromHexString(addr) port = int(port, 16) return addr, port def parseLine(self, line): parts = line.strip().split() localAddr, localPort = self.unpackAddress(parts[1]) remoteAddr, remotePort = self.unpackAddress(parts[2]) uid = int(parts[7]) return (localAddr, localPort), (remoteAddr, remotePort), uid def lookup(self, serverAddress, clientAddress): for ent in self.entries(): localAddr, remoteAddr, uid = self.parseLine(ent) if remoteAddr == clientAddress and localAddr[1] == serverAddress[1]: return (self.SYSTEM_NAME, self.getUsername(uid)) raise NoUser() class IdentClient(basic.LineOnlyReceiver): errorTypes = (IdentError, NoUser, InvalidPort, HiddenUser) def __init__(self): self.queries = [] def lookup(self, portOnServer, portOnClient): """Lookup user information about the specified address pair. """ self.queries.append((defer.Deferred(), portOnServer, portOnClient)) if len(self.queries) > 1: return self.queries[-1][0] self.sendLine('%d, %d' % (portOnServer, portOnClient)) return self.queries[-1][0] def lineReceived(self, line): if not self.queries: log.msg("Unexpected server response: %r" % (line,)) else: d, _, _ = self.queries.pop(0) self.parseResponse(d, line) if self.queries: self.sendLine('%d, %d' % (self.queries[0][1], self.queries[0][2])) def connectionLost(self, reason): for q in self.queries: q[0].errback(IdentError(reason)) self.queries = [] def parseResponse(self, deferred, line): parts = line.split(':', 2) if len(parts) != 3: deferred.errback(IdentError(line)) else: ports, type, addInfo = map(str.strip, parts) if type == 'ERROR': for et in self.errorTypes: if et.identDescription == addInfo: deferred.errback(et(line)) return deferred.errback(IdentError(line)) else: deferred.callback((type, addInfo)) __all__ = ['IdentError', 'NoUser', 'InvalidPort', 'HiddenUser', 'IdentServer', 'IdentClient', 'ProcServerMixin']