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