#!/usr/bin/python
# Copyright 2007-2010 Mike Perry. See LICENSE file.
"""

Support classes for path construction

The PathSupport package builds on top of TorCtl.TorCtl. It provides a
number of interfaces that make path construction easier.

The inheritance diagram for event handling is as follows:
TorCtl.EventHandler <- TorCtl.ConsensusTracker <- PathBuilder 
  <- CircuitHandler <- StreamHandler.

Basically, EventHandler is what gets all the control port events
packaged in nice clean classes (see help(TorCtl) for information on
those). 

ConsensusTracker tracks the NEWCONSENSUS and NEWDESC events to maintain
a view of the network that is consistent with the Tor client's current
consensus.

PathBuilder inherits from ConsensusTracker and is what builds all
circuits based on the requirements specified in the SelectionManager
instance passed to its constructor. It also handles attaching streams to
circuits. It only handles one building one circuit at a time.

CircuitHandler optionally inherits from PathBuilder, and overrides its
circuit event handling to manage building a pool of circuits as opposed
to just one. It still uses the SelectionManager for path selection.

StreamHandler inherits from CircuitHandler, and is what governs the
attachment of an incoming stream on to one of the multiple circuits of
the circuit handler. 

The SelectionManager is essentially a configuration wrapper around the
most elegant portions of TorFlow: NodeGenerators, NodeRestrictions, and
PathRestrictions. It extends from a BaseSelectionManager that provides
a basic example of using these mechanisms for custom implementations.

In the SelectionManager, a NodeGenerator is used to choose the nodes
probabilistically according to some distribution while obeying the
NodeRestrictions. These generators (one per hop) are handed off to the
PathSelector, which uses the generators to build a complete path that
satisfies the PathRestriction requirements.

Have a look at the class hierarchy directly below to get a feel for how
the restrictions fit together, and what options are available.

"""

import TorCtl
import re
import struct
import random
import socket
import copy
import Queue
import time
import TorUtil
import traceback
import threading
from TorUtil import *

import sys
if sys.version_info < (2, 5):
  from sets import Set as set

__all__ = ["NodeRestrictionList", "PathRestrictionList",
"PercentileRestriction", "OSRestriction", "ConserveExitsRestriction",
"FlagsRestriction", "MinBWRestriction", "VersionIncludeRestriction",
"VersionExcludeRestriction", "VersionRangeRestriction",
"ExitPolicyRestriction", "NodeRestriction", "PathRestriction",
"OrNodeRestriction", "MetaNodeRestriction", "AtLeastNNodeRestriction",
"NotNodeRestriction", "Subnet16Restriction", "UniqueRestriction",
"NodeGenerator", "UniformGenerator", "OrderedExitGenerator",
"BwWeightedGenerator", "PathSelector", "Connection", "NickRestriction",
"IdHexRestriction", "PathBuilder", "CircuitHandler", "StreamHandler",
"SelectionManager", "BaseSelectionManager", "CountryCodeRestriction",
"CountryRestriction", "UniqueCountryRestriction", "SingleCountryRestriction",
"ContinentRestriction", "ContinentJumperRestriction",
"UniqueContinentRestriction", "MetaPathRestriction", "RateLimitedRestriction",
"SmartSocket"]

#################### Path Support Interfaces #####################

class RestrictionError(Exception):
  "Error raised for issues with applying restrictions"
  pass

class NoNodesRemain(RestrictionError):
  "Error raised for issues with applying restrictions"
  pass

class NodeRestriction:
  "Interface for node restriction policies"
  def r_is_ok(self, r):
    "Returns true if Router 'r' is acceptable for this restriction"
    return True  

class PathRestriction:
  "Interface for path restriction policies"
  def path_is_ok(self, path):
    "Return true if the list of Routers in path satisfies this restriction"
    return True  

# TODO: Or, Not, N of M
class MetaPathRestriction(PathRestriction):
  "MetaPathRestrictions are path restriction aggregators."
  def add_restriction(self, rstr): raise NotImplemented()
  def del_restriction(self, RestrictionClass): raise NotImplemented()
 
class PathRestrictionList(MetaPathRestriction):
  """Class to manage a list of PathRestrictions"""
  def __init__(self, restrictions):
    "Constructor. 'restrictions' is a list of PathRestriction instances"
    self.restrictions = restrictions
  
  def path_is_ok(self, path):
    "Given list if Routers in 'path', check it against each restriction."
    for rs in self.restrictions:
      if not rs.path_is_ok(path):
        return False
    return True

  def add_restriction(self, rstr):
    "Add a PathRestriction 'rstr' to the list"
    self.restrictions.append(rstr)

  def del_restriction(self, RestrictionClass):
    "Remove all PathRestrictions of type RestrictionClass from the list."
    self.restrictions = filter(
        lambda r: not isinstance(r, RestrictionClass),
          self.restrictions)

  def __str__(self):
    return self.__class__.__name__+"("+str(map(str, self.restrictions))+")"

class NodeGenerator:
  "Interface for node generation"
  def __init__(self, sorted_r, rstr_list):
    """Constructor. Takes a bandwidth-sorted list of Routers 'sorted_r' 
    and a NodeRestrictionList 'rstr_list'"""
    self.rstr_list = rstr_list
    self.rebuild(sorted_r)

  def reset_restriction(self, rstr_list):
    "Reset the restriction list to a new list"
    self.rstr_list = rstr_list
    self.rebuild()

  def rewind(self):
    "Rewind the generator to the 'beginning'"
    self.routers = copy.copy(self.rstr_routers)
    if not self.routers:
      plog("NOTICE", "No routers left after restrictions applied: "+str(self.rstr_list))
      raise NoNodesRemain(str(self.rstr_list))
 
  def rebuild(self, sorted_r=None):
    """ Extra step to be performed when new routers are added or when
    the restrictions change. """
    if sorted_r != None:
      self.sorted_r = sorted_r
    self.rstr_routers = filter(lambda r: self.rstr_list.r_is_ok(r), self.sorted_r)
    if not self.rstr_routers:
      plog("NOTICE", "No routers left after restrictions applied: "+str(self.rstr_list))
      raise NoNodesRemain(str(self.rstr_list))

  def mark_chosen(self, r):
    """Mark a router as chosen: remove it from the list of routers 
     that can be returned in the future"""
    self.routers.remove(r)

  def all_chosen(self):
    "Return true if all the routers have been marked as chosen"
    return not self.routers

  def generate(self):
    "Return a python generator that yields routers according to the policy"
    raise NotImplemented()

class Connection(TorCtl.Connection):
  """Extended Connection class that provides a method for building circuits"""
  def __init__(self, sock):
    TorCtl.Connection.__init__(self,sock)
  def build_circuit(self, path):
    "Tell Tor to build a circuit chosen by the PathSelector 'path_sel'"
    circ = Circuit()
    circ.path = path
    circ.exit = circ.path[len(path)-1]
    circ.circ_id = self.extend_circuit(0, circ.id_path())
    return circ

######################## Node Restrictions ########################

# TODO: We still need more path support implementations
#  - NodeRestrictions:
#    - Uptime/LongLivedPorts (Does/should hibernation count?)
#    - Published/Updated
#    - Add a /8 restriction for ExitPolicy?
#  - PathRestrictions:
#    - NodeFamily
#    - GeoIP:
#      - Mathematical/empirical study of predecessor expectation
#        - If middle node on the same continent as exit, exit learns nothing
#        - else, exit has a bias on the continent of origin of user
#          - Language and browser accept string determine this anyway
#      - ContinentRestrictor (avoids doing more than N continent crossings)
#      - EchelonPhobicRestrictor
#        - Does not cross international boundaries for client->Entry or
#          Exit->destination hops

class PercentileRestriction(NodeRestriction):
  """Restriction to cut out a percentile slice of the network."""
  def __init__(self, pct_skip, pct_fast, r_list):
    """Constructor. Sets up the restriction such that routers in the 
     'pct_skip' to 'pct_fast' percentile of bandwidth rankings are 
     returned from the sorted list 'r_list'"""
    self.pct_fast = pct_fast
    self.pct_skip = pct_skip
    self.sorted_r = r_list

  def r_is_ok(self, r):
    "Returns true if r is in the percentile boundaries (by rank)"
    if r.list_rank < len(self.sorted_r)*self.pct_skip/100: return False
    elif r.list_rank > len(self.sorted_r)*self.pct_fast/100: return False
    
    return True

  def __str__(self):
    return self.__class__.__name__+"("+str(self.pct_skip)+","+str(self.pct_fast)+")"

class RatioPercentileRestriction(NodeRestriction):
  """Restriction to cut out a percentile slice of the network by ratio of
     consensus bw to descriptor bw."""
  def __init__(self, pct_skip, pct_fast, r_list):
    """Constructor. Sets up the restriction such that routers in the
     'pct_skip' to 'pct_fast' percentile of bandwidth rankings are
     returned from the sorted list 'r_list'"""
    self.pct_fast = pct_fast
    self.pct_skip = pct_skip
    self.sorted_r = r_list

  def r_is_ok(self, r):
    "Returns true if r is in the percentile boundaries (by rank)"
    if r.ratio_rank < len(self.sorted_r)*self.pct_skip/100: return False
    elif r.ratio_rank > len(self.sorted_r)*self.pct_fast/100: return False

    return True

  def __str__(self):
    return self.__class__.__name__+"("+str(self.pct_skip)+","+str(self.pct_fast)+")"

class UptimeRestriction(NodeRestriction):
  """Restriction to filter out routers with uptimes < min_uptime or
     > max_uptime"""
  def __init__(self, min_uptime=None, max_uptime=None):
    self.min_uptime = min_uptime
    self.max_uptime = max_uptime

  def r_is_ok(self, r):
    "Returns true if r is in the uptime boundaries"
    if self.min_uptime and r.uptime < self.min_uptime: return False
    if self.max_uptime and r.uptime > self.max_uptime: return False
    return True

class RankRestriction(NodeRestriction):
  """Restriction to cut out a list-rank slice of the network."""
  def __init__(self, rank_skip, rank_stop):
    self.rank_skip = rank_skip
    self.rank_stop = rank_stop

  def r_is_ok(self, r):
    "Returns true if r is in the boundaries (by rank)"
    if r.list_rank < self.rank_skip: return False
    elif r.list_rank > self.rank_stop: return False
    
    return True

  def __str__(self):
    return self.__class__.__name__+"("+str(self.rank_skip)+","+str(self.rank_stop)+")"
    
class OSRestriction(NodeRestriction):
  "Restriction based on operating system"
  def __init__(self, ok, bad=[]):
    """Constructor. Accept router OSes that match regexes in 'ok', 
       rejects those that match regexes in 'bad'."""
    self.ok = ok
    self.bad = bad

  def r_is_ok(self, r):
    "Returns true if r is in 'ok', false if 'r' is in 'bad'. If 'ok'"
    for y in self.ok:
      if re.search(y, r.os):
        return True
    for b in self.bad:
      if re.search(b, r.os):
        return False
    if self.ok: return False
    if self.bad: return True

  def __str__(self):
    return self.__class__.__name__+"("+str(self.ok)+","+str(self.bad)+")"

class ConserveExitsRestriction(NodeRestriction):
  "Restriction to reject exits from selection"
  def __init__(self, exit_ports=None):
    self.exit_ports = exit_ports

  def r_is_ok(self, r):
    if self.exit_ports:
      for port in self.exit_ports:
        if r.will_exit_to("255.255.255.255", port):
          return False
      return True
    return not "Exit" in r.flags

  def __str__(self):
    return self.__class__.__name__+"()"

class FlagsRestriction(NodeRestriction):
  "Restriction for mandatory and forbidden router flags"
  def __init__(self, mandatory, forbidden=[]):
    """Constructor. 'mandatory' and 'forbidden' are both lists of router 
     flags as strings."""
    self.mandatory = mandatory
    self.forbidden = forbidden

  def r_is_ok(self, router):
    for m in self.mandatory:
      if not m in router.flags: return False
    for f in self.forbidden:
      if f in router.flags: return False
    return True

  def __str__(self):
    return self.__class__.__name__+"("+str(self.mandatory)+","+str(self.forbidden)+")"

class NickRestriction(NodeRestriction):
  """Require that the node nickname is as specified"""
  def __init__(self, nickname):
    self.nickname = nickname

  def r_is_ok(self, router):
    return router.nickname == self.nickname

  def __str__(self):
    return self.__class__.__name__+"("+str(self.nickname)+")"

class IdHexRestriction(NodeRestriction):
  """Require that the node idhash is as specified"""
  def __init__(self, idhex):
    if idhex[0] == '$':
      self.idhex = idhex[1:].upper()
    else:
      self.idhex = idhex.upper()

  def r_is_ok(self, router):
    return router.idhex == self.idhex

  def __str__(self):
    return self.__class__.__name__+"("+str(self.idhex)+")"
 
class MinBWRestriction(NodeRestriction):
  """Require a minimum bandwidth"""
  def __init__(self, minbw):
    self.min_bw = minbw

  def r_is_ok(self, router): return router.bw >= self.min_bw

  def __str__(self):
    return self.__class__.__name__+"("+str(self.min_bw)+")"

class RateLimitedRestriction(NodeRestriction):
  def __init__(self, limited=True):
    self.limited = limited

  def r_is_ok(self, router): return router.rate_limited == self.limited

  def __str__(self):
    return self.__class__.__name__+"("+str(self.limited)+")"
   
class VersionIncludeRestriction(NodeRestriction):
  """Require that the version match one in the list"""
  def __init__(self, eq):
    "Constructor. 'eq' is a list of versions as strings"
    self.eq = map(TorCtl.RouterVersion, eq)
  
  def r_is_ok(self, router):
    """Returns true if the version of 'router' matches one of the 
     specified versions."""
    for e in self.eq:
      if e == router.version:
        return True
    return False

  def __str__(self):
    return self.__class__.__name__+"("+str(self.eq)+")"

class VersionExcludeRestriction(NodeRestriction):
  """Require that the version not match one in the list"""
  def __init__(self, exclude):
    "Constructor. 'exclude' is a list of versions as strings"
    self.exclude = map(TorCtl.RouterVersion, exclude)
  
  def r_is_ok(self, router):
    """Returns false if the version of 'router' matches one of the 
     specified versions."""
    for e in self.exclude:
      if e == router.version:
        return False
    return True

  def __str__(self):
    return self.__class__.__name__+"("+str(map(str, self.exclude))+")"

class VersionRangeRestriction(NodeRestriction):
  """Require that the versions be inside a specified range""" 
  def __init__(self, gr_eq, less_eq=None):
    self.gr_eq = TorCtl.RouterVersion(gr_eq)
    if less_eq: self.less_eq = TorCtl.RouterVersion(less_eq)
    else: self.less_eq = None
  
  def r_is_ok(self, router):
    return (not self.gr_eq or router.version >= self.gr_eq) and \
        (not self.less_eq or router.version <= self.less_eq)

  def __str__(self):
    return self.__class__.__name__+"("+str(self.gr_eq)+","+str(self.less_eq)+")"

class ExitPolicyRestriction(NodeRestriction):
  """Require that a router exit to an ip+port"""
  def __init__(self, to_ip, to_port):
    self.to_ip = to_ip
    self.to_port = to_port

  def r_is_ok(self, r): return r.will_exit_to(self.to_ip, self.to_port)

  def __str__(self):
    return self.__class__.__name__+"("+str(self.to_ip)+","+str(self.to_port)+")"

class MetaNodeRestriction(NodeRestriction):
  """Interface for a NodeRestriction that is an expression consisting of 
     multiple other NodeRestrictions"""
  def add_restriction(self, rstr): raise NotImplemented()
  # TODO: these should collapse the restriction and return a new
  # instance for re-insertion (or None)
  def next_rstr(self): raise NotImplemented()
  def del_restriction(self, RestrictionClass): raise NotImplemented()

class OrNodeRestriction(MetaNodeRestriction):
  """MetaNodeRestriction that is the boolean or of two or more
     NodeRestrictions"""
  def __init__(self, rs):
    "Constructor. 'rs' is a list of NodeRestrictions"
    self.rstrs = rs

  def r_is_ok(self, r):
    "Returns true if one of 'rs' is true for this router"
    for rs in self.rstrs:
      if rs.r_is_ok(r):
        return True
    return False

  def __str__(self):
    return self.__class__.__name__+"("+str(map(str, self.rstrs))+")"

class NotNodeRestriction(MetaNodeRestriction):
  """Negates a single restriction"""
  def __init__(self, a):
    self.a = a

  def r_is_ok(self, r): return not self.a.r_is_ok(r)

  def __str__(self):
    return self.__class__.__name__+"("+str(self.a)+")"

class AtLeastNNodeRestriction(MetaNodeRestriction):
  """MetaNodeRestriction that is true if at least n member 
     restrictions are true."""
  def __init__(self, rstrs, n):
    self.rstrs = rstrs
    self.n = n

  def r_is_ok(self, r):
    cnt = 0
    for rs in self.rstrs:
      if rs.r_is_ok(r):
        cnt += 1
    if cnt < self.n: return False
    else: return True

  def __str__(self):
    return self.__class__.__name__+"("+str(map(str, self.rstrs))+","+str(self.n)+")"

class NodeRestrictionList(MetaNodeRestriction):
  "Class to manage a list of NodeRestrictions"
  def __init__(self, restrictions):
    "Constructor. 'restrictions' is a list of NodeRestriction instances"
    self.restrictions = restrictions

  def r_is_ok(self, r):
    "Returns true of Router 'r' passes all of the contained restrictions"
    for rs in self.restrictions:
      if not rs.r_is_ok(r): return False
    return True

  def add_restriction(self, restr):
    "Add a NodeRestriction 'restr' to the list of restrictions"
    self.restrictions.append(restr)

  # TODO: This does not collapse meta restrictions..
  def del_restriction(self, RestrictionClass):
    """Remove all restrictions of type RestrictionClass from the list.
       Does NOT inspect or collapse MetaNode Restrictions (though 
       MetaRestrictions can be removed if RestrictionClass is 
       MetaNodeRestriction)"""
    self.restrictions = filter(
        lambda r: not isinstance(r, RestrictionClass),
          self.restrictions)
  
  def clear(self):
    """ Remove all restrictions """
    self.restrictions = []

  def __str__(self):
    return self.__class__.__name__+"("+str(map(str, self.restrictions))+")"


#################### Path Restrictions #####################

class Subnet16Restriction(PathRestriction):
  """PathRestriction that mandates that no two nodes from the same 
     /16 subnet be in the path"""
  def path_is_ok(self, path):
    mask16 = struct.unpack(">I", socket.inet_aton("255.255.0.0"))[0]
    ip16 = path[0].ip & mask16
    for r in path[1:]:
      if ip16 == (r.ip & mask16):
        return False
    return True

  def __str__(self):
    return self.__class__.__name__+"()"

class UniqueRestriction(PathRestriction):
  """Path restriction that mandates that the same router can't appear more
     than once in a path"""
  def path_is_ok(self, path):
    for i in xrange(0,len(path)):
      if path[i] in path[:i]:
        return False
    return True

  def __str__(self):
    return self.__class__.__name__+"()"

#################### GeoIP Restrictions ###################

class CountryCodeRestriction(NodeRestriction):
  """ Ensure that the country_code is set """
  def r_is_ok(self, r):
    return r.country_code != None

  def __str__(self):
    return self.__class__.__name__+"()"

class CountryRestriction(NodeRestriction):
  """ Only accept nodes that are in 'country_code' """
  def __init__(self, country_code):
    self.country_code = country_code

  def r_is_ok(self, r):
    return r.country_code == self.country_code

  def __str__(self):
    return self.__class__.__name__+"("+str(self.country_code)+")"

class ExcludeCountriesRestriction(NodeRestriction):
  """ Exclude a list of countries """
  def __init__(self, countries):
    self.countries = countries

  def r_is_ok(self, r):
    return not (r.country_code in self.countries)

  def __str__(self):
    return self.__class__.__name__+"("+str(self.countries)+")"

class UniqueCountryRestriction(PathRestriction):
  """ Ensure every router to have a distinct country_code """
  def path_is_ok(self, path):
    for i in xrange(0, len(path)-1):
      for j in xrange(i+1, len(path)):
        if path[i].country_code == path[j].country_code:
          return False;
    return True;

  def __str__(self):
    return self.__class__.__name__+"()"

class SingleCountryRestriction(PathRestriction):
  """ Ensure every router to have the same country_code """
  def path_is_ok(self, path):
    country_code = path[0].country_code
    for r in path:
      if country_code != r.country_code:
        return False
    return True

  def __str__(self):
    return self.__class__.__name__+"()"

class ContinentRestriction(PathRestriction):
  """ Do not more than n continent crossings """
  # TODO: Add src and dest
  def __init__(self, n, src=None, dest=None):
    self.n = n

  def path_is_ok(self, path):
    crossings = 0
    prev = None
    # Compute crossings until now
    for r in path:
      # Jump over the first router
      if prev:
        if r.continent != prev.continent:
          crossings += 1
      prev = r
    if crossings > self.n: return False
    else: return True

  def __str__(self):
    return self.__class__.__name__+"("+str(self.n)+")"

class ContinentJumperRestriction(PathRestriction):
  """ Ensure continent crossings between all hops """
  def path_is_ok(self, path):
    prev = None
    for r in path:
      # Jump over the first router
      if prev:
        if r.continent == prev.continent:
          return False
      prev = r
    return True

  def __str__(self):
    return self.__class__.__name__+"()"

class UniqueContinentRestriction(PathRestriction):
  """ Ensure every hop to be on a different continent """
  def path_is_ok(self, path):
    for i in xrange(0, len(path)-1):
      for j in xrange(i+1, len(path)):
        if path[i].continent == path[j].continent:
          return False;
    return True;

  def __str__(self):
    return self.__class__.__name__+"()"

class OceanPhobicRestriction(PathRestriction):
  """ Not more than n ocean crossings """
  # TODO: Add src and dest
  def __init__(self, n, src=None, dest=None):
    self.n = n

  def path_is_ok(self, path):
    crossings = 0
    prev = None
    # Compute ocean crossings until now
    for r in path:
      # Jump over the first router
      if prev:
        if r.cont_group != prev.cont_group:
          crossings += 1
      prev = r
    if crossings > self.n: return False
    else: return True

  def __str__(self):
    return self.__class__.__name__+"("+str(self.n)+")"

#################### Node Generators ######################

class UniformGenerator(NodeGenerator):
  """NodeGenerator that produces nodes in the uniform distribution"""
  def generate(self):
    # XXX: hrmm.. this is not really the right thing to check
    while not self.all_chosen():
      yield random.choice(self.routers)
     
class ExactUniformGenerator(NodeGenerator):
  """NodeGenerator that produces nodes randomly, yet strictly uniformly 
     over time"""
  def __init__(self, sorted_r, rstr_list, position=0):
    self.position = position
    NodeGenerator.__init__(self, sorted_r, rstr_list)  

  def generate(self):
    min_gen = min(map(lambda r: r._generated[self.position], self.routers))
    choices = filter(lambda r: r._generated[self.position]==min_gen, 
                       self.routers)
    while choices:
      r = random.choice(choices)
      yield r
      choices.remove(r)

    choices = filter(lambda r: r._generated[self.position]==min_gen,
                       self.routers)
    plog("NOTICE", "Ran out of choices in ExactUniformGenerator. Incrementing nodes")
    for r in choices:
      r._generated[self.position] += 1

  def mark_chosen(self, r):
    r._generated[self.position] += 1
    NodeGenerator.mark_chosen(self, r)

  def rebuild(self, sorted_r=None):
    plog("DEBUG", "Rebuilding ExactUniformGenerator")
    NodeGenerator.rebuild(self, sorted_r)
    for r in self.rstr_routers:
      lgen = len(r._generated)
      if lgen < self.position+1:
        for i in xrange(lgen, self.position+1):
          r._generated.append(0)


class OrderedExitGenerator(NodeGenerator):
  """NodeGenerator that produces exits in an ordered fashion for a 
     specific port"""
  def __init__(self, to_port, sorted_r, rstr_list):
    self.to_port = to_port
    self.next_exit_by_port = {}
    NodeGenerator.__init__(self, sorted_r, rstr_list)

  def rewind(self):
    NodeGenerator.rewind(self)
    if self.to_port not in self.next_exit_by_port or not self.next_exit_by_port[self.to_port]:
      self.next_exit_by_port[self.to_port] = 0
      self.last_idx = len(self.routers)
    else:
      self.last_idx = self.next_exit_by_port[self.to_port]

  def set_port(self, port):
    self.to_port = port
    self.rewind()
     
  def mark_chosen(self, r):
    self.next_exit_by_port[self.to_port] += 1
  
  def all_chosen(self):
    return self.last_idx == self.next_exit_by_port[self.to_port]

  def generate(self):
    while True: # A do..while would be real nice here..
      if self.next_exit_by_port[self.to_port] >= len(self.routers):
        self.next_exit_by_port[self.to_port] = 0
      yield self.routers[self.next_exit_by_port[self.to_port]]
      self.next_exit_by_port[self.to_port] += 1
      if self.last_idx == self.next_exit_by_port[self.to_port]:
        break

class BwWeightedGenerator(NodeGenerator):
  """

  This is a generator designed to match the Tor Path Selection
  algorithm.  It will generate nodes weighted by their bandwidth,
  but take the appropriate weighting into account against guard
  nodes and exit nodes when they are chosen for positions other
  than guard/exit. For background see:
  routerlist.c::smartlist_choose_by_bandwidth(),
  http://archives.seul.org/or/dev/Jul-2007/msg00021.html,
  http://archives.seul.org/or/dev/Jul-2007/msg00056.html, and
  https://tor-svn.freehaven.net/svn/tor/trunk/doc/spec/path-spec.txt
  The formulas used are from the first or-dev link, but are proven
  optimal and equivalent to the ones now used in routerlist.c in the 
  second or-dev link.
  
  """ 
  def __init__(self, sorted_r, rstr_list, pathlen, exit=False, guard=False):
    """ Pass exit=True to create a generator for exit-nodes """
    self.max_bandwidth = 10000000
    # Out for an exit-node?
    self.exit = exit
    # Is this a guard node? 
    self.guard = guard
    # Different sums of bandwidths
    self.total_bw = 0
    self.total_exit_bw = 0
    self.total_guard_bw = 0
    self.total_weighted_bw = 0
    self.pathlen = pathlen
    NodeGenerator.__init__(self, sorted_r, rstr_list)

  def rebuild(self, sorted_r=None):
    NodeGenerator.rebuild(self, sorted_r)
    NodeGenerator.rewind(self)
    # Set the exit_weight
    # We are choosing a non-exit
    self.total_exit_bw = 0
    self.total_guard_bw = 0
    self.total_bw = 0
    for r in self.routers:
      # TODO: Check max_bandwidth and cap...
      self.total_bw += r.bw
      if "Exit" in r.flags:
        self.total_exit_bw += r.bw
      if "Guard" in r.flags:
        self.total_guard_bw += r.bw

    bw_per_hop = (1.0*self.total_bw)/self.pathlen

    # Print some debugging info about bandwidth ratios
    if self.total_bw > 0:
      e_ratio = self.total_exit_bw/float(self.total_bw)
      g_ratio = self.total_guard_bw/float(self.total_bw)
    else:
      g_ratio = 0
      e_ratio = 0
    plog("DEBUG",
       "E = " + str(self.total_exit_bw) +
       ", G = " + str(self.total_guard_bw) +
       ", T = " + str(self.total_bw) +
       ", g_ratio = " + str(g_ratio) + ", e_ratio = " +str(e_ratio) +
       ", bw_per_hop = " + str(bw_per_hop))
   
    if self.exit:
      self.exit_weight = 1.0
    else:
      if self.total_exit_bw < bw_per_hop:
        # Don't use exit nodes at all
        self.exit_weight = 0
      else:
        if self.total_exit_bw > 0:
          self.exit_weight = ((self.total_exit_bw-bw_per_hop)/self.total_exit_bw)
        else: self.exit_weight = 0

    if self.guard:
      self.guard_weight = 1.0
    else:
      if self.total_guard_bw < bw_per_hop:
        # Don't use exit nodes at all
        self.guard_weight = 0
      else:
        if self.total_guard_bw > 0:
          self.guard_weight = ((self.total_guard_bw-bw_per_hop)/self.total_guard_bw)
        else: self.guard_weight = 0
    
    for r in self.routers:
      bw = r.bw
      if "Exit" in r.flags:
        bw *= self.exit_weight
      if "Guard" in r.flags:
        bw *= self.guard_weight
      self.total_weighted_bw += bw

    self.total_weighted_bw = int(self.total_weighted_bw)
    plog("DEBUG", "Bw: "+str(self.total_weighted_bw)+"/"+str(self.total_bw)
          +". The exit-weight is: "+str(self.exit_weight)
          + ", guard weight is: "+str(self.guard_weight))

  def generate(self):
    while True:
      # Choose a suitable random int
      i = random.randint(0, self.total_weighted_bw)

      # Go through the routers
      for r in self.routers:
        # Below zero here means next() -> choose a new random int+router 
        if i < 0: break
        bw = r.bw
        if "Exit" in r.flags:
          bw *= self.exit_weight
        if "Guard" in r.flags:
          bw *= self.guard_weight

        i -= bw
        if i < 0:
          plog("DEBUG", "Chosen router with a bandwidth of: " + str(r.bw))
          yield r

####################### Secret Sauce ###########################

class PathError(Exception):
  pass

class NoRouters(PathError):
  pass

class PathSelector:
  """Implementation of path selection policies. Builds a path according
     to entry, middle, and exit generators that satisfies the path 
     restrictions."""
  def __init__(self, entry_gen, mid_gen, exit_gen, path_restrict):
    """Constructor. The first three arguments are NodeGenerators with 
     their appropriate restrictions. The 'path_restrict' is a
     PathRestrictionList"""
    self.entry_gen = entry_gen
    self.mid_gen = mid_gen
    self.exit_gen = exit_gen
    self.path_restrict = path_restrict

  def rebuild_gens(self, sorted_r):
    "Rebuild the 3 generators with a new sorted router list"
    self.entry_gen.rebuild(sorted_r)
    self.mid_gen.rebuild(sorted_r)
    self.exit_gen.rebuild(sorted_r)

  def select_path(self, pathlen):
    """Creates a path of 'pathlen' hops, and returns it as a list of
       Router instances"""
    self.entry_gen.rewind()
    self.mid_gen.rewind()
    self.exit_gen.rewind()
    entry = self.entry_gen.generate()
    mid = self.mid_gen.generate()
    ext = self.exit_gen.generate()
      
    plog("DEBUG", "Selecting path..")

    while True:
      path = []
      plog("DEBUG", "Building path..")
      try:
        if pathlen == 1:
          path = [ext.next()]
        else:
          path.append(entry.next())
          for i in xrange(1, pathlen-1):
            path.append(mid.next())
          path.append(ext.next())
        if self.path_restrict.path_is_ok(path):
          self.entry_gen.mark_chosen(path[0])
          for i in xrange(1, pathlen-1):
            self.mid_gen.mark_chosen(path[i])
          self.exit_gen.mark_chosen(path[pathlen-1])
          plog("DEBUG", "Marked path.")
          break
        else:
          plog("DEBUG", "Path rejected by path restrictions.")
      except StopIteration:
        plog("NOTICE", "Ran out of routers during buildpath..");
        self.entry_gen.rewind()
        self.mid_gen.rewind()
        self.exit_gen.rewind()
        entry = self.entry_gen.generate()
        mid = self.mid_gen.generate()
        ext = self.exit_gen.generate()
    for r in path:
      r.refcount += 1
      plog("DEBUG", "Circ refcount "+str(r.refcount)+" for "+r.idhex)
    return path

# TODO: Implement example manager.
class BaseSelectionManager:
   """
   The BaseSelectionManager is a minimalistic node selection manager.

   It is meant to be used with a PathSelector that consists of an
   entry NodeGenerator, a middle NodeGenerator, and an exit NodeGenerator.

   However, none of these are absolutely necessary. It is possible
   to completely avoid them if you wish by hacking whatever selection
   mechanisms you want straight into this interface and then passing
   an instance to a PathBuilder implementation.
   """
   def __init__(self):
     self.bad_restrictions = False
     self.consensus = None

   def reconfigure(self, consensus=None):
     """ 
     This method is called whenever a significant configuration change
     occurs. Currently, this only happens via PathBuilder.__init__ and
     PathBuilder.schedule_selmgr().
     
     This method should NOT throw any exceptions.
     """
     pass

   def new_consensus(self, consensus):
     """ 
     This method is called whenever a consensus change occurs.
     
     This method should NOT throw any exceptions.
     """
     pass

   def set_exit(self, exit_name):
     """
     This method provides notification that a fixed exit is desired.

     This method should NOT throw any exceptions.
     """
     pass

   def set_target(self, host, port):
     """
     This method provides notification that a new target endpoint is
     desired.

     May throw a RestrictionError if target is impossible to reach.
     """
     pass

   def select_path(self):
     """
     Returns a new path in the form of a list() of Router instances.

     May throw a RestrictionError.
     """
     pass

class SelectionManager(BaseSelectionManager):
  """Helper class to handle configuration updates
    
    The methods are NOT threadsafe. They may ONLY be called from
    EventHandler's thread. This means that to update the selection 
    manager, you must schedule a config update job using 
    PathBuilder.schedule_selmgr() with a worker function to modify 
    this object.
 
    XXX: Warning. The constructor of this class is subject to change
    and may undergo reorganization in the near future. Watch for falling 
    bits.
    """
  # XXX: Hrmm, consider simplifying this. It is confusing and unweildy.
  def __init__(self, pathlen, order_exits,
         percent_fast, percent_skip, min_bw, use_all_exits,
         uniform, use_exit, use_guards,geoip_config=None,
         restrict_guards=False, extra_node_rstr=None, exit_ports=None,
         order_by_ratio=False):
    BaseSelectionManager.__init__(self)
    self.__ordered_exit_gen = None 
    self.pathlen = pathlen
    self.order_exits = order_exits
    self.percent_fast = percent_fast
    self.percent_skip = percent_skip
    self.min_bw = min_bw
    self.use_all_exits = use_all_exits
    self.uniform = uniform
    self.exit_id = use_exit
    self.use_guards = use_guards
    self.geoip_config = geoip_config
    self.restrict_guards_only = restrict_guards
    self.bad_restrictions = False
    self.consensus = None
    self.exit_ports = exit_ports
    self.extra_node_rstr=extra_node_rstr
    self.order_by_ratio = order_by_ratio

  def reconfigure(self, consensus=None):
    try:
      self._reconfigure(consensus)
      self.bad_restrictions = False
    except NoNodesRemain:
      plog("WARN", "No nodes remain in selection manager")
      self.bad_restrictions = True
    return self.bad_restrictions

  def _reconfigure(self, consensus=None):
    """This function is called after a configuration change, 
     to rebuild the RestrictionLists."""
    if consensus: 
      plog("DEBUG", "Reconfigure with consensus")
      self.consensus = consensus
    else:
      plog("DEBUG", "Reconfigure without consensus")

    sorted_r = self.consensus.sorted_r

    if self.use_all_exits:
      self.path_rstr = PathRestrictionList([UniqueRestriction()])
    else:
      self.path_rstr = PathRestrictionList(
           [Subnet16Restriction(), UniqueRestriction()])
  
    if self.use_guards: entry_flags = ["Guard", "Running"]
    else: entry_flags = ["Running"]

    if self.restrict_guards_only:
      nonentry_skip = 0
      nonentry_fast = 100
    else:
      nonentry_skip = self.percent_skip
      nonentry_fast = self.percent_fast

    if self.order_by_ratio:
      PctRstr = RatioPercentileRestriction
    else:
      PctRstr = PercentileRestriction

    # XXX: sometimes we want the ability to do uniform scans
    # without the conserve exit restrictions..
    entry_rstr = NodeRestrictionList(
      [PctRstr(self.percent_skip, self.percent_fast, sorted_r),
       OrNodeRestriction(
           [FlagsRestriction(["BadExit"]),
           ConserveExitsRestriction(self.exit_ports)]),
       FlagsRestriction(entry_flags, [])]
    )
    mid_rstr = NodeRestrictionList(
      [PctRstr(nonentry_skip, nonentry_fast, sorted_r),
       OrNodeRestriction(
           [FlagsRestriction(["BadExit"]),
           ConserveExitsRestriction(self.exit_ports)]),
       FlagsRestriction(["Running"], [])]

    )

    if self.exit_id:
      self._set_exit(self.exit_id)
      plog("DEBUG", "Applying Setexit: "+self.exit_id)
      self.exit_rstr = NodeRestrictionList([IdHexRestriction(self.exit_id)])
    elif self.use_all_exits:
      self.exit_rstr = NodeRestrictionList(
        [FlagsRestriction(["Running"], ["BadExit"])])
    else:
      self.exit_rstr = NodeRestrictionList(
        [PctRstr(nonentry_skip, nonentry_fast, sorted_r),
         FlagsRestriction(["Running"], ["BadExit"])])

    if self.extra_node_rstr:
      entry_rstr.add_restriction(self.extra_node_rstr)
      mid_rstr.add_restriction(self.extra_node_rstr)
      self.exit_rstr.add_restriction(self.extra_node_rstr)

    # GeoIP configuration
    if self.geoip_config:
      # Every node needs country_code 
      entry_rstr.add_restriction(CountryCodeRestriction())
      mid_rstr.add_restriction(CountryCodeRestriction())
      self.exit_rstr.add_restriction(CountryCodeRestriction())
      
      # Specified countries for different positions
      if self.geoip_config.entry_country:
        entry_rstr.add_restriction(CountryRestriction(self.geoip_config.entry_country))
      if self.geoip_config.middle_country:
        mid_rstr.add_restriction(CountryRestriction(self.geoip_config.middle_country))
      if self.geoip_config.exit_country:
        self.exit_rstr.add_restriction(CountryRestriction(self.geoip_config.exit_country))

      # Excluded countries
      if self.geoip_config.excludes:
        plog("INFO", "Excluded countries: " + str(self.geoip_config.excludes))
        if len(self.geoip_config.excludes) > 0:
          entry_rstr.add_restriction(ExcludeCountriesRestriction(self.geoip_config.excludes))
          mid_rstr.add_restriction(ExcludeCountriesRestriction(self.geoip_config.excludes))
          self.exit_rstr.add_restriction(ExcludeCountriesRestriction(self.geoip_config.excludes))
      
      # Unique countries set? None --> pass
      if self.geoip_config.unique_countries != None:
        if self.geoip_config.unique_countries:
          # If True: unique countries 
          self.path_rstr.add_restriction(UniqueCountryRestriction())
        else:
          # False: use the same country for all nodes in a path
          self.path_rstr.add_restriction(SingleCountryRestriction())
      
      # Specify max number of continent crossings, None means UniqueContinents
      if self.geoip_config.continent_crossings == None:
        self.path_rstr.add_restriction(UniqueContinentRestriction())
      else: self.path_rstr.add_restriction(ContinentRestriction(self.geoip_config.continent_crossings))
      # Should even work in combination with continent crossings
      if self.geoip_config.ocean_crossings != None:
        self.path_rstr.add_restriction(OceanPhobicRestriction(self.geoip_config.ocean_crossings))

    # This is kind of hokey..
    if self.order_exits:
      if self.__ordered_exit_gen:
        exitgen = self.__ordered_exit_gen
        exitgen.reset_restriction(self.exit_rstr)
      else:
        exitgen = self.__ordered_exit_gen = \
          OrderedExitGenerator(80, sorted_r, self.exit_rstr)
    elif self.uniform:
      exitgen = ExactUniformGenerator(sorted_r, self.exit_rstr)
    else:
      exitgen = BwWeightedGenerator(sorted_r, self.exit_rstr, self.pathlen, exit=True)

    if self.uniform:
      self.path_selector = PathSelector(
         ExactUniformGenerator(sorted_r, entry_rstr),
         ExactUniformGenerator(sorted_r, mid_rstr),
         exitgen, self.path_rstr)
    else:
      # Remove ConserveExitsRestriction for entry and middle positions
      # by removing the OrNodeRestriction that contains it...
      # FIXME: This is a landmine for a poor soul to hit.
      # Then again, most of the rest of this function is, too.
      entry_rstr.del_restriction(OrNodeRestriction)
      mid_rstr.del_restriction(OrNodeRestriction)
      self.path_selector = PathSelector(
         BwWeightedGenerator(sorted_r, entry_rstr, self.pathlen,
                             guard=self.use_guards),
         BwWeightedGenerator(sorted_r, mid_rstr, self.pathlen),
         exitgen, self.path_rstr)
      return

  def _set_exit(self, exit_name):
    # sets an exit, if bad, sets bad_exit
    exit_id = None
    if exit_name:
      if exit_name[0] == '$':
        exit_id = exit_name
      elif exit_name in self.consensus.name_to_key:
        exit_id = self.consensus.name_to_key[exit_name]
    self.exit_id = exit_id

  def set_exit(self, exit_name):
    self._set_exit(exit_name)
    self.exit_rstr.clear()
    if not self.exit_id:
      plog("NOTICE", "Requested null exit "+str(self.exit_id))
      self.bad_restrictions = True
    elif self.exit_id[1:] not in self.consensus.routers:
      plog("NOTICE", "Requested absent exit "+str(self.exit_id))
      self.bad_restrictions = True
    elif self.consensus.routers[self.exit_id[1:]].down:
      e = self.consensus.routers[self.exit_id[1:]]
      plog("NOTICE", "Requested downed exit "+str(self.exit_id)+" (bw: "+str(e.bw)+", flags: "+str(e.flags)+")")
      self.bad_restrictions = True
    elif self.consensus.routers[self.exit_id[1:]].deleted:
      e = self.consensus.routers[self.exit_id[1:]]
      plog("NOTICE", "Requested deleted exit "+str(self.exit_id)+" (bw: "+str(e.bw)+", flags: "+str(e.flags)+", Down: "+str(e.down)+", ref: "+str(e.refcount)+")")
      self.bad_restrictions = True
    else:
      self.exit_rstr.add_restriction(IdHexRestriction(self.exit_id))
      plog("DEBUG", "Added exit restriction for "+self.exit_id)
      try:
        self.path_selector.exit_gen.rebuild()
        self.bad_restrictions = False
      except RestrictionError, e:
        plog("WARN", "Restriction error "+str(e)+" after set_exit")
        self.bad_restrictions = True
    return self.bad_restrictions

  def new_consensus(self, consensus):
    self.consensus = consensus
    try:
      self.path_selector.rebuild_gens(self.consensus.sorted_r)
      if self.exit_id:
        self.set_exit(self.exit_id)
    except NoNodesRemain:
      plog("NOTICE", "No viable nodes in consensus for restrictions.")
      # Punting + performing reconfigure..")
      #self.reconfigure(consensus)

  def set_target(self, ip, port):
    # sets an exit policy, if bad, rasies exception..
    "Called to update the ExitPolicyRestrictions with a new ip and port"
    if self.bad_restrictions:
      plog("WARN", "Requested target with bad restrictions")
      raise RestrictionError()
    self.exit_rstr.del_restriction(ExitPolicyRestriction)
    self.exit_rstr.add_restriction(ExitPolicyRestriction(ip, port))
    if self.__ordered_exit_gen: self.__ordered_exit_gen.set_port(port)
    # Try to choose an exit node in the destination country
    # needs an IP != 255.255.255.255
    if self.geoip_config and self.geoip_config.echelon:
      import GeoIPSupport
      c = GeoIPSupport.get_country(ip)
      if c:
        plog("INFO", "[Echelon] IP "+ip+" is in ["+c+"]")
        self.exit_rstr.del_restriction(CountryRestriction)
        self.exit_rstr.add_restriction(CountryRestriction(c))
      else: 
        plog("INFO", "[Echelon] Could not determine destination country of IP "+ip)
        # Try to use a backup country
        if self.geoip_config.exit_country:
          self.exit_rstr.del_restriction(CountryRestriction) 
          self.exit_rstr.add_restriction(CountryRestriction(self.geoip_config.exit_country))
    # Need to rebuild exit generator
    self.path_selector.exit_gen.rebuild()

  def select_path(self):
    if self.bad_restrictions:
      plog("WARN", "Requested target with bad restrictions")
      raise RestrictionError()
    return self.path_selector.select_path(self.pathlen)

class Circuit:
  "Class to describe a circuit"
  def __init__(self):
    self.circ_id = 0
    self.path = [] # routers
    self.exit = None
    self.built = False
    self.failed = False
    self.dirty = False
    self.requested_closed = False
    self.detached_cnt = 0
    self.last_extended_at = time.time()
    self.extend_times = []      # List of all extend-durations
    self.setup_duration = None  # Sum of extend-times
    self.pending_streams = []   # Which stream IDs are pending us
    # XXX: Unused.. Need to use for refcounting because
    # sometimes circuit closed events come before the stream
    # close and we need to track those failures..
    self.carried_streams = []

  def id_path(self):
    "Returns a list of idhex keys for the path of Routers"
    return map(lambda r: r.idhex, self.path)

class Stream:
  "Class to describe a stream"
  def __init__(self, sid, host, port, kind):
    self.strm_id = sid
    self.detached_from = [] # circ id #'s
    self.pending_circ = None
    self.circ = None
    self.host = host
    self.port = port
    self.kind = kind
    self.attached_at = 0
    self.bytes_read = 0
    self.bytes_written = 0
    self.failed = False
    self.ignored = False # Set if PURPOSE=DIR_*
    self.failed_reason = None # Cheating a little.. Only used by StatsHandler

  def lifespan(self, now):
    "Returns the age of the stream"
    return now-self.attached_at

_origsocket = socket.socket
class _SocketWrapper(socket.socket):
  """ Ghetto wrapper to workaround python same_slots_added() and 
      socket __base__ braindamage """
  pass

class SmartSocket(_SocketWrapper):
  """ A SmartSocket is a socket that tracks global socket creation
      for local ports. It has a member StreamSelector that can
      be used as a PathBuilder stream StreamSelector (see below).

      Most users will want to reset the base class of SocksiPy to
      use this class:
      __oldsocket = socket.socket
      socket.socket = PathSupport.SmartSocket
      import SocksiPy
      socket.socket = __oldsocket
   """
  port_table = set()
  _table_lock = threading.Lock()

  def __init__(self, family=2, type=1, proto=0, _sock=None):
    ret = super(SmartSocket, self).__init__(family, type, proto, _sock)
    self.__local_addr = None
    plog("DEBUG", "New socket constructor")
    return ret

  def connect(self, args):
    ret = super(SmartSocket, self).connect(args)
    myaddr = self.getsockname()
    self.__local_addr = myaddr[0]+":"+str(myaddr[1])
    SmartSocket._table_lock.acquire()
    assert(self.__local_addr not in SmartSocket.port_table)
    SmartSocket.port_table.add(myaddr[0]+":"+str(myaddr[1]))
    SmartSocket._table_lock.release()
    plog("DEBUG", "Added "+self.__local_addr+" to our local port list")
    return ret

  def connect_ex(self, args):
    ret = super(SmartSocket, self).connect_ex(args)
    myaddr = ret.getsockname()
    self.__local_addr = myaddr[0]+":"+str(myaddr[1])
    SmartSocket._table_lock.acquire()
    assert(self.__local_addr not in SmartSocket.port_table)
    SmartSocket.port_table.add(myaddr[0]+":"+str(myaddr[1]))
    SmartSocket._table_lock.release()
    plog("DEBUG", "Added "+self.__local_addr+" to our local port list")
    return ret

  def __del__(self):
    if self.__local_addr:
      SmartSocket._table_lock.acquire()
      SmartSocket.port_table.remove(self.__local_addr)
      plog("DEBUG", "Removed "+self.__local_addr+" from our local port list")
      SmartSocket._table_lock.release()
    else:
      plog("DEBUG", "Got a socket deletion with no address")

  def table_size():
    SmartSocket._table_lock.acquire()
    ret = len(SmartSocket.port_table)
    SmartSocket._table_lock.release()
    return ret
  table_size = Callable(table_size)

  def clear_port_table():
    """ WARNING: Calling this periodically is a *really good idea*.
        Relying on __del__ can expose you to race conditions on garbage
        collection between your processes. """
    SmartSocket._table_lock.acquire()
    for i in list(SmartSocket.port_table):
      plog("DEBUG", "Cleared "+i+" from our local port list")
      SmartSocket.port_table.remove(i)
    SmartSocket._table_lock.release()
  clear_port_table = Callable(clear_port_table)

  def StreamSelector(host, port):
    to_test = host+":"+str(port)
    SmartSocket._table_lock.acquire()
    ret = (to_test in SmartSocket.port_table)
    SmartSocket._table_lock.release()
    return ret
  StreamSelector = Callable(StreamSelector)


def StreamSelector(host, port):
  """ A StreamSelector is a function that takes a host and a port as
      arguments (parsed from Tor's SOURCE_ADDR field in STREAM NEW
      events) and decides if it is a stream from this process or not.

      This StreamSelector is just a placeholder that always returns True.
      When you define your own, be aware that you MUST DO YOUR OWN
      LOCKING inside this function, as it is called from the Eventhandler
      thread.

      See PathSupport.SmartSocket.StreamSelctor for an actual
      implementation.

  """
  return True

# TODO: Make passive "PathWatcher" so people can get aggregate 
# node reliability stats for normal usage without us attaching streams
# Can use __metaclass__ and type

class PathBuilder(TorCtl.ConsensusTracker):
  """
  PathBuilder implementation. Handles circuit construction, subject
  to the constraints of the SelectionManager selmgr.
  
  Do not access this object from other threads. Instead, use the 
  schedule_* functions to schedule work to be done in the thread
  of the EventHandler.
  """
  def __init__(self, c, selmgr, RouterClass=TorCtl.Router,
               strm_selector=StreamSelector):
    """Constructor. 'c' is a Connection, 'selmgr' is a SelectionManager,
    and 'RouterClass' is a class that inherits from Router and is used
    to create annotated Routers."""
    TorCtl.ConsensusTracker.__init__(self, c, RouterClass)
    self.last_exit = None
    self.new_nym = False
    self.resolve_port = 0
    self.num_circuits = 1
    self.circuits = {}
    self.streams = {}
    self.selmgr = selmgr
    self.selmgr.reconfigure(self.current_consensus())
    self.imm_jobs = Queue.Queue()
    self.low_prio_jobs = Queue.Queue()
    self.run_all_jobs = False
    self.do_reconfigure = False
    self.strm_selector = strm_selector
    plog("INFO", "Read "+str(len(self.sorted_r))+"/"+str(len(self.ns_map))+" routers")

  def schedule_immediate(self, job):
    """
    Schedules an immediate job to be run before the next event is
    processed.
    """
    assert(self.c.is_live())
    self.imm_jobs.put(job)

  def schedule_low_prio(self, job):
    """
    Schedules a job to be run when a non-time critical event arrives.
    """
    assert(self.c.is_live())
    self.low_prio_jobs.put(job)

  def reset(self):
    """
    Resets accumulated state. Currently only clears the 
    ExactUniformGenerator state.
    """
    plog("DEBUG", "Resetting _generated values for ExactUniformGenerator")
    for r in self.routers.itervalues():
      for g in xrange(0, len(r._generated)):
        r._generated[g] = 0

  def is_urgent_event(event):
    # If event is stream:NEW*/DETACHED or circ BUILT/FAILED, 
    # it is high priority and requires immediate action.
    if isinstance(event, TorCtl.CircuitEvent):
      if event.status in ("BUILT", "FAILED", "CLOSED"):
        return True
    elif isinstance(event, TorCtl.StreamEvent):
      if event.status in ("NEW", "NEWRESOLVE", "DETACHED"):
        return True
    return False
  is_urgent_event = Callable(is_urgent_event)

  def schedule_selmgr(self, job):
    """
    Schedules an immediate job to be run before the next event is
    processed. Also notifies the selection manager that it needs
    to update itself.
    """
    assert(self.c.is_live())
    def notlambda(this):
      job(this.selmgr)
      this.do_reconfigure = True
    self.schedule_immediate(notlambda)

     
  def heartbeat_event(self, event):
    """This function handles dispatching scheduled jobs. If you 
       extend PathBuilder and want to implement this function for 
       some reason, be sure to call the parent class"""
    while not self.imm_jobs.empty():
      imm_job = self.imm_jobs.get_nowait()
      imm_job(self)
    
    if self.do_reconfigure:
      self.selmgr.reconfigure(self.current_consensus())
      self.do_reconfigure = False
    
    if self.run_all_jobs:
      while not self.low_prio_jobs.empty() and self.run_all_jobs:
        imm_job = self.low_prio_jobs.get_nowait()
        imm_job(self)
      self.run_all_jobs = False
      return

    # If event is stream:NEW*/DETACHED or circ BUILT/FAILED, 
    # don't run low prio jobs.. No need to delay streams for them.
    if PathBuilder.is_urgent_event(event): return
   
    # Do the low prio jobs one at a time in case a 
    # higher priority event is queued   
    if not self.low_prio_jobs.empty():
      delay_job = self.low_prio_jobs.get_nowait()
      delay_job(self)

  def build_path(self):
    """ Get a path from the SelectionManager's PathSelector, can be used 
        e.g. for generating paths without actually creating any circuits """
    return self.selmgr.select_path()

  def close_all_streams(self, reason):
    """ Close all open streams """
    for strm in self.streams.itervalues():
      if not strm.ignored:
        try:
          self.c.close_stream(strm.strm_id, reason)
        except TorCtl.ErrorReply, e:
          # This can happen. Streams can timeout before this call.
          plog("NOTICE", "Error closing stream "+str(strm.strm_id)+": "+str(e))

  def close_all_circuits(self):
    """ Close all open circuits """
    for circ in self.circuits.itervalues():
      self.close_circuit(circ.circ_id)

  def close_circuit(self, id):
    """ Close a circuit with given id """
    # TODO: Pass streams to another circ before closing?
    plog("DEBUG", "Requesting close of circuit id: "+str(id))
    if self.circuits[id].requested_closed: return
    self.circuits[id].requested_closed = True
    try: self.c.close_circuit(id)
    except TorCtl.ErrorReply, e: 
      plog("ERROR", "Failed closing circuit " + str(id) + ": " + str(e))

  def circuit_list(self):
    """ Return an iterator or a list of circuits prioritized for 
        stream selection."""
    return self.circuits.itervalues()

  def attach_stream_any(self, stream, badcircs):
    "Attach a stream to a valid circuit, avoiding any in 'badcircs'"
    # Newnym, and warn if not built plus pending
    unattached_streams = [stream]
    if self.new_nym:
      self.new_nym = False
      plog("DEBUG", "Obeying new nym")
      for key in self.circuits.keys():
        if (not self.circuits[key].dirty
            and len(self.circuits[key].pending_streams)):
          plog("WARN", "New nym called, destroying circuit "+str(key)
             +" with "+str(len(self.circuits[key].pending_streams))
             +" pending streams")
          unattached_streams.extend(self.circuits[key].pending_streams)
          self.circuits[key].pending_streams = []
        # FIXME: Consider actually closing circ if no streams.
        self.circuits[key].dirty = True
      
    for circ in self.circuit_list():
      if circ.built and not circ.requested_closed and not circ.dirty \
          and circ.circ_id not in badcircs:
        # XXX: Fails for 'tor-resolve 530.19.6.80' -> NEWRESOLVE
        if circ.exit.will_exit_to(stream.host, stream.port):
          try:
            self.c.attach_stream(stream.strm_id, circ.circ_id)
            stream.pending_circ = circ # Only one possible here
            circ.pending_streams.append(stream)
          except TorCtl.ErrorReply, e:
            # No need to retry here. We should get the failed
            # event for either the circ or stream next
            plog("WARN", "Error attaching new stream: "+str(e.args))
            return
          break
    # This else clause is executed when we go through the circuit
    # list without finding an entry (or it is empty).
    # http://docs.python.org/tutorial/controlflow.html#break-and-continue-statements-and-else-clauses-on-loops
    else:
      circ = None
      try:
        self.selmgr.set_target(stream.host, stream.port)
        circ = self.c.build_circuit(self.selmgr.select_path())
      except RestrictionError, e:
        # XXX: Dress this up a bit
        self.last_exit = None
        # Kill this stream
        plog("WARN", "Closing impossible stream "+str(stream.strm_id)+" ("+str(e)+")")
        try:
          self.c.close_stream(stream.strm_id, "4") # END_STREAM_REASON_EXITPOLICY
        except TorCtl.ErrorReply, e:
          plog("WARN", "Error closing stream: "+str(e))
        return
      except TorCtl.ErrorReply, e:
        plog("WARN", "Error building circ: "+str(e.args))
        self.last_exit = None
        # Kill this stream
        plog("NOTICE", "Closing stream "+str(stream.strm_id))
        try:
          self.c.close_stream(stream.strm_id, "5") # END_STREAM_REASON_DESTROY
        except TorCtl.ErrorReply, e:
          plog("WARN", "Error closing stream: "+str(e))
        return
      for u in unattached_streams:
        plog("DEBUG",
           "Attaching "+str(u.strm_id)+" pending build of "+str(circ.circ_id))
        u.pending_circ = circ
      circ.pending_streams.extend(unattached_streams)
      self.circuits[circ.circ_id] = circ
    self.last_exit = circ.exit
    plog("DEBUG", "Set last exit to "+self.last_exit.idhex)

  def circ_status_event(self, c):
    output = [str(time.time()-c.arrived_at), c.event_name, str(c.circ_id),
              c.status]
    if c.path: output.append(",".join(c.path))
    if c.reason: output.append("REASON=" + c.reason)
    if c.remote_reason: output.append("REMOTE_REASON=" + c.remote_reason)
    plog("DEBUG", " ".join(output))
    # Circuits we don't control get built by Tor
    if c.circ_id not in self.circuits:
      plog("DEBUG", "Ignoring circ " + str(c.circ_id))
      return
    if c.status == "EXTENDED":
      self.circuits[c.circ_id].last_extended_at = c.arrived_at
    elif c.status == "FAILED" or c.status == "CLOSED":
      # XXX: Can still get a STREAM FAILED for this circ after this
      circ = self.circuits[c.circ_id]
      for r in circ.path:
        r.refcount -= 1
        plog("DEBUG", "Close refcount "+str(r.refcount)+" for "+r.idhex)
        if r.deleted and r.refcount == 0:
          # XXX: This shouldn't happen with StatsRouters.. 
          if r.__class__.__name__ == "StatsRouter":
            plog("WARN", "Purging expired StatsRouter "+r.idhex)
          else:
            plog("INFO", "Purging expired router "+r.idhex)
          del self.routers[r.idhex]
          self.selmgr.new_consensus(self.current_consensus())
      del self.circuits[c.circ_id]
      for stream in circ.pending_streams:
        # If it was built, let Tor decide to detach or fail the stream
        if not circ.built:
          plog("DEBUG", "Finding new circ for " + str(stream.strm_id))
          self.attach_stream_any(stream, stream.detached_from)
        else:
          plog("NOTICE", "Waiting on Tor to hint about stream "+str(stream.strm_id)+" on closed circ "+str(circ.circ_id))
    elif c.status == "BUILT":
      self.circuits[c.circ_id].built = True
      try:
        for stream in self.circuits[c.circ_id].pending_streams:
          self.c.attach_stream(stream.strm_id, c.circ_id)
      except TorCtl.ErrorReply, e:
        # No need to retry here. We should get the failed
        # event for either the circ or stream in the next event
        plog("NOTICE", "Error attaching pending stream: "+str(e.args))
        return

  def stream_status_event(self, s):
    output = [str(time.time()-s.arrived_at), s.event_name, str(s.strm_id),
              s.status, str(s.circ_id),
          s.target_host, str(s.target_port)]
    if s.reason: output.append("REASON=" + s.reason)
    if s.remote_reason: output.append("REMOTE_REASON=" + s.remote_reason)
    if s.purpose: output.append("PURPOSE=" + s.purpose)
    if s.source_addr: output.append("SOURCE_ADDR="+s.source_addr)
    if not re.match(r"\d+.\d+.\d+.\d+", s.target_host):
      s.target_host = "255.255.255.255" # ignore DNS for exit policy check

    # Hack to ignore Tor-handled streams
    if s.strm_id in self.streams and self.streams[s.strm_id].ignored:
      if s.status == "CLOSED":
        plog("DEBUG", "Deleting ignored stream: " + str(s.strm_id))
        del self.streams[s.strm_id]
      else:
        plog("DEBUG", "Ignoring stream: " + str(s.strm_id))
      return

    plog("DEBUG", " ".join(output))
    # XXX: Copy s.circ_id==0 check+reset from StatsSupport here too?

    if s.status == "NEW" or s.status == "NEWRESOLVE":
      if s.status == "NEWRESOLVE" and not s.target_port:
        s.target_port = self.resolve_port
      if s.circ_id == 0:
        self.streams[s.strm_id] = Stream(s.strm_id, s.target_host, s.target_port, s.status)
      elif s.strm_id not in self.streams:
        plog("NOTICE", "Got new stream "+str(s.strm_id)+" with circuit "
                       +str(s.circ_id)+" already attached.")
        self.streams[s.strm_id] = Stream(s.strm_id, s.target_host, s.target_port, s.status)
        self.streams[s.strm_id].circ_id = s.circ_id

      # Remember Tor-handled streams (Currently only directory streams)

      if s.purpose and s.purpose.find("DIR_") == 0:
        self.streams[s.strm_id].ignored = True
        plog("DEBUG", "Ignoring stream: " + str(s.strm_id))
        return
      elif s.source_addr:
        src_addr = s.source_addr.split(":")
        src_addr[1] = int(src_addr[1])
        if not self.strm_selector(*src_addr):
          self.streams[s.strm_id].ignored = True
          plog("INFO", "Ignoring foreign stream: " + str(s.strm_id))
          return
      if s.circ_id == 0:
        self.attach_stream_any(self.streams[s.strm_id],
                   self.streams[s.strm_id].detached_from)
    elif s.status == "DETACHED":
      if s.strm_id not in self.streams:
        plog("WARN", "Detached stream "+str(s.strm_id)+" not found")
        self.streams[s.strm_id] = Stream(s.strm_id, s.target_host,
                      s.target_port, "NEW")
      # FIXME Stats (differentiate Resolved streams also..)
      if not s.circ_id:
        if s.reason == "TIMEOUT" or s.reason == "EXITPOLICY":
          plog("NOTICE", "Stream "+str(s.strm_id)+" detached with "+s.reason)
        else:
          plog("WARN", "Stream "+str(s.strm_id)+" detached from no circuit with reason: "+str(s.reason))
      else:
        self.streams[s.strm_id].detached_from.append(s.circ_id)

      if self.streams[s.strm_id].pending_circ and \
           self.streams[s.strm_id] in \
                  self.streams[s.strm_id].pending_circ.pending_streams:
        self.streams[s.strm_id].pending_circ.pending_streams.remove(
                                                self.streams[s.strm_id])
      self.streams[s.strm_id].pending_circ = None
      self.attach_stream_any(self.streams[s.strm_id],
                   self.streams[s.strm_id].detached_from)
    elif s.status == "SUCCEEDED":
      if s.strm_id not in self.streams:
        plog("NOTICE", "Succeeded stream "+str(s.strm_id)+" not found")
        return
      if s.circ_id and self.streams[s.strm_id].pending_circ.circ_id != s.circ_id:
        # Hrmm.. this can happen on a new-nym.. Very rare, putting warn
        # in because I'm still not sure this is correct
        plog("WARN", "Mismatch of pending: "
          +str(self.streams[s.strm_id].pending_circ.circ_id)+" vs "
          +str(s.circ_id))
        # This can happen if the circuit existed before we started up
        if s.circ_id in self.circuits:
          self.streams[s.strm_id].circ = self.circuits[s.circ_id]
        else:
          plog("NOTICE", "Stream "+str(s.strm_id)+" has unknown circuit: "+str(s.circ_id))
      else:
        self.streams[s.strm_id].circ = self.streams[s.strm_id].pending_circ
      self.streams[s.strm_id].pending_circ.pending_streams.remove(self.streams[s.strm_id])
      self.streams[s.strm_id].pending_circ = None
      self.streams[s.strm_id].attached_at = s.arrived_at
    elif s.status == "FAILED" or s.status == "CLOSED":
      # FIXME stats
      if s.strm_id not in self.streams:
        plog("NOTICE", "Failed stream "+str(s.strm_id)+" not found")
        return

      # XXX: Can happen on timeout
      if not s.circ_id:
        if s.reason == "TIMEOUT" or s.reason == "EXITPOLICY":
          plog("NOTICE", "Stream "+str(s.strm_id)+" "+s.status+" with "+s.reason)
        else:
          plog("WARN", "Stream "+str(s.strm_id)+" "+s.status+" from no circuit with reason: "+str(s.reason))

      # We get failed and closed for each stream. OK to return 
      # and let the closed do the cleanup
      if s.status == "FAILED":
        # Avoid busted circuits that will not resolve or carry
        # traffic. 
        self.streams[s.strm_id].failed = True
        if s.circ_id in self.circuits: self.circuits[s.circ_id].dirty = True
        elif s.circ_id != 0: 
          plog("WARN", "Failed stream "+str(s.strm_id)+" on unknown circ "+str(s.circ_id))
        return

      if self.streams[s.strm_id].pending_circ:
        self.streams[s.strm_id].pending_circ.pending_streams.remove(self.streams[s.strm_id])
      del self.streams[s.strm_id]
    elif s.status == "REMAP":
      if s.strm_id not in self.streams:
        plog("WARN", "Remap id "+str(s.strm_id)+" not found")
      else:
        if not re.match(r"\d+.\d+.\d+.\d+", s.target_host):
          s.target_host = "255.255.255.255"
          plog("NOTICE", "Non-IP remap for "+str(s.strm_id)+" to "
                   + s.target_host)
        self.streams[s.strm_id].host = s.target_host
        self.streams[s.strm_id].port = s.target_port

  def stream_bw_event(self, s):
    output = [str(time.time()-s.arrived_at), s.event_name, str(s.strm_id),
              str(s.bytes_written),
              str(s.bytes_read)]
    if not s.strm_id in self.streams:
      plog("DEBUG", " ".join(output))
      plog("WARN", "BW event for unknown stream id: "+str(s.strm_id))
    else:
      if not self.streams[s.strm_id].ignored:
        plog("DEBUG", " ".join(output))
      self.streams[s.strm_id].bytes_read += s.bytes_read
      self.streams[s.strm_id].bytes_written += s.bytes_written

  def new_consensus_event(self, n):
    TorCtl.ConsensusTracker.new_consensus_event(self, n)
    self.selmgr.new_consensus(self.current_consensus())

  def new_desc_event(self, d):
    if TorCtl.ConsensusTracker.new_desc_event(self, d):
      self.selmgr.new_consensus(self.current_consensus())

  def bandwidth_event(self, b): pass # For heartbeat only..

################### CircuitHandler #############################

class CircuitHandler(PathBuilder):
  """ CircuitHandler that extends from PathBuilder to handle multiple
      circuits as opposed to just one. """
  def __init__(self, c, selmgr, num_circuits, RouterClass):
    """Constructor. 'c' is a Connection, 'selmgr' is a SelectionManager,
    'num_circuits' is the number of circuits to keep in the pool,
    and 'RouterClass' is a class that inherits from Router and is used
    to create annotated Routers."""
    PathBuilder.__init__(self, c, selmgr, RouterClass)
    # Set handler to the connection here to 
    # not miss any circuit events on startup
    c.set_event_handler(self)
    self.num_circuits = num_circuits    # Size of the circuit pool
    self.check_circuit_pool()           # Bring up the pool of circs
    
  def check_circuit_pool(self):
    """ Init or check the status of the circuit-pool """
    # Get current number of circuits
    n = len(self.circuits.values())
    i = self.num_circuits-n
    if i > 0:
      plog("INFO", "Checked pool of circuits: we need to build " + 
         str(i) + " circuits")
    # Schedule (num_circs-n) circuit-buildups
    while (n < self.num_circuits):      
      # TODO: Should mimic Tor's learning here
      self.build_circuit("255.255.255.255", 80) 
      plog("DEBUG", "Scheduled circuit No. " + str(n+1))
      n += 1

  def build_circuit(self, host, port):
    """ Build a circuit """
    circ = None
    while circ == None:
      try:
        self.selmgr.set_target(host, port)
        circ = self.c.build_circuit(self.selmgr.select_path())
        self.circuits[circ.circ_id] = circ
        return circ
      except RestrictionError, e:
        # XXX: Dress this up a bit
        traceback.print_exc()
        plog("ERROR", "Impossible restrictions: "+str(e))
      except TorCtl.ErrorReply, e:
        traceback.print_exc()
        plog("WARN", "Error building circuit: " + str(e.args))

  def circ_status_event(self, c):
    """ Handle circuit status events """
    output = [c.event_name, str(c.circ_id), c.status]
    if c.path: output.append(",".join(c.path))
    if c.reason: output.append("REASON=" + c.reason)
    if c.remote_reason: output.append("REMOTE_REASON=" + c.remote_reason)
    plog("DEBUG", " ".join(output))
    
    # Circuits we don't control get built by Tor
    if c.circ_id not in self.circuits:
      plog("DEBUG", "Ignoring circuit " + str(c.circ_id) + 
         " (controlled by Tor)")
      return
    
    # EXTENDED
    if c.status == "EXTENDED":
      # Compute elapsed time
      extend_time = c.arrived_at-self.circuits[c.circ_id].last_extended_at
      self.circuits[c.circ_id].extend_times.append(extend_time)
      plog("INFO", "Circuit " + str(c.circ_id) + " extended in " + 
         str(extend_time) + " sec")
      self.circuits[c.circ_id].last_extended_at = c.arrived_at
    
    # FAILED & CLOSED
    elif c.status == "FAILED" or c.status == "CLOSED":
      PathBuilder.circ_status_event(self, c)
      # Check if there are enough circs
      self.check_circuit_pool()
      return
    # BUILT
    elif c.status == "BUILT":
      PathBuilder.circ_status_event(self, c)
      # Compute duration by summing up extend_times
      circ = self.circuits[c.circ_id]
      duration = reduce(lambda x, y: x+y, circ.extend_times, 0.0)
      plog("INFO", "Circuit " + str(c.circ_id) + " needed " + 
         str(duration) + " seconds to be built")
      # Save the duration to the circuit for later use
      circ.setup_duration = duration
      
    # OTHER?
    else:
      # If this was e.g. a LAUNCHED
      pass

################### StreamHandler ##############################

class StreamHandler(CircuitHandler):
  """ StreamHandler that extends from the CircuitHandler 
      to handle attaching streams to an appropriate circuit 
      in the pool. """
  def __init__(self, c, selmgr, num_circs, RouterClass):
    CircuitHandler.__init__(self, c, selmgr, num_circs, RouterClass)

  def clear_dns_cache(self):
    """ Send signal CLEARDNSCACHE """
    lines = self.c.sendAndRecv("SIGNAL CLEARDNSCACHE\r\n")
    for _, msg, more in lines:
      plog("DEBUG", "CLEARDNSCACHE: " + msg)

  def close_stream(self, id, reason):
    """ Close a stream with given id and reason """
    self.c.close_stream(id, reason)

  def address_mapped_event(self, event):
    """ It is necessary to listen to ADDRMAP events to be able to 
        perform DNS lookups using Tor """
    output = [event.event_name, event.from_addr, event.to_addr, 
       time.asctime(event.when)]
    plog("DEBUG", " ".join(output))

  def unknown_event(self, event):
    plog("DEBUG", "UNKNOWN EVENT '" + event.event_name + "':" + 
       event.event_string)

########################## Unit tests ##########################

def do_gen_unit(gen, r_list, weight_bw, num_print):
  trials = 0
  for r in r_list:
    if gen.rstr_list.r_is_ok(r):
      trials += weight_bw(gen, r)
  trials = int(trials/1024)
  
  print "Running "+str(trials)+" trials"

  # 0. Reset r.chosen = 0 for all routers
  for r in r_list:
    r.chosen = 0

  # 1. Generate 'trials' choices:
  #    1a. r.chosen++

  loglevel = TorUtil.loglevel
  TorUtil.loglevel = "INFO"

  gen.rewind()
  rtrs = gen.generate()
  for i in xrange(1, trials):
    r = rtrs.next()
    r.chosen += 1

  TorUtil.loglevel = loglevel

  # 2. Print top num_print routers choices+bandwidth stats+flags
  i = 0
  copy_rlist = copy.copy(r_list)
  copy_rlist.sort(lambda x, y: cmp(y.chosen, x.chosen))
  for r in copy_rlist:
    if r.chosen and not gen.rstr_list.r_is_ok(r):
      print "WARN: Restriction fail at "+r.idhex
    if not r.chosen and gen.rstr_list.r_is_ok(r):
      print "WARN: Generation fail at "+r.idhex
    if not gen.rstr_list.r_is_ok(r): continue
    flag = ""
    bw = int(weight_bw(gen, r))
    if "Exit" in r.flags:
      flag += "E"
    if "Guard" in r.flags:
      flag += "G"
    print str(r.list_rank)+". "+r.nickname+" "+str(r.bw/1024.0)+"/"+str(bw/1024.0)+": "+str(r.chosen)+", "+flag
    i += 1
    if i > num_print: break

def do_unit(rst, r_list, plamb):
  print "\n"
  print "-----------------------------------"
  print rst.r_is_ok.im_class
  above_i = 0
  above_bw = 0
  below_i = 0
  below_bw = 0
  for r in r_list:
    if rst.r_is_ok(r):
      print r.nickname+" "+plamb(r)+"="+str(rst.r_is_ok(r))+" "+str(r.bw)
      if r.bw > 400000:
        above_i = above_i + 1
        above_bw += r.bw
      else:
        below_i = below_i + 1
        below_bw += r.bw
        
  print "Routers above: " + str(above_i) + " bw: " + str(above_bw)
  print "Routers below: " + str(below_i) + " bw: " + str(below_bw)

# TODO: Tests:
#  - Test each NodeRestriction and print in/out lines for it
#  - Test NodeGenerator and reapply NodeRestrictions
#  - Same for PathSelector and PathRestrictions
#  - Also Reapply each restriction by hand to path. Verify returns true

if __name__ == '__main__':
  s = socket.socket(socket.AF_INET, socket.SOCK_STREAM)
  s.connect((TorUtil.control_host,TorUtil.control_port))
  c = Connection(s)
  c.debug(file("control.log", "w"))
  c.authenticate(TorUtil.control_pass)
  nslist = c.get_network_status()
  sorted_rlist = c.read_routers(c.get_network_status())

  sorted_rlist.sort(lambda x, y: cmp(y.bw, x.bw))
  for i in xrange(len(sorted_rlist)): sorted_rlist[i].list_rank = i

  def flag_weighting(bwgen, r):
    bw = r.bw
    if "Exit" in r.flags:
      bw *= bwgen.exit_weight
    if "Guard" in r.flags:
      bw *= bwgen.guard_weight
    return bw

  def uniform_weighting(bwgen, r):
    return 10240000

  # XXX: Test OrderedexitGenerators
  do_gen_unit(
   UniformGenerator(sorted_rlist,
                    NodeRestrictionList([PercentileRestriction(20,30,sorted_rlist),
FlagsRestriction(["Valid"])])),
                    sorted_rlist, uniform_weighting, 1500)

  
  do_gen_unit(BwWeightedGenerator(sorted_rlist, FlagsRestriction(["Exit"]),
                                  3, exit=True),
              sorted_rlist, flag_weighting, 500)
  
  do_gen_unit(BwWeightedGenerator(sorted_rlist, FlagsRestriction(["Guard"]),
              3, guard=True),
              sorted_rlist, flag_weighting, 500)
  
  do_gen_unit(
   BwWeightedGenerator(sorted_rlist, FlagsRestriction(["Valid"]), 3),
   sorted_rlist, flag_weighting, 500)

 
  for r in sorted_rlist:
    if r.will_exit_to("211.11.21.22", 465):
      print r.nickname+" "+str(r.bw)

  do_unit(FlagsRestriction(["Guard"], []), sorted_rlist, lambda r: " ".join(r.flags))
  do_unit(FlagsRestriction(["Fast"], []), sorted_rlist, lambda r: " ".join(r.flags))

  do_unit(ExitPolicyRestriction("2.11.2.2", 80), sorted_rlist,
          lambda r: "exits to 80")
  do_unit(PercentileRestriction(0, 100, sorted_rlist), sorted_rlist,
          lambda r: "")
  do_unit(PercentileRestriction(10, 20, sorted_rlist), sorted_rlist,
          lambda r: "")
  do_unit(OSRestriction([r"[lL]inux", r"BSD", "Darwin"], []), sorted_rlist,
          lambda r: r.os)
  do_unit(OSRestriction([], ["Windows", "Solaris"]), sorted_rlist,
          lambda r: r.os)
   
  do_unit(VersionRangeRestriction("0.1.2.0"), sorted_rlist,
          lambda r: str(r.version))
  do_unit(VersionRangeRestriction("0.1.2.0", "0.1.2.5"), sorted_rlist,
          lambda r: str(r.version))
  do_unit(VersionIncludeRestriction(["0.1.1.26-alpha", "0.1.2.7-ignored"]),
          sorted_rlist, lambda r: str(r.version))
  do_unit(VersionExcludeRestriction(["0.1.1.26"]), sorted_rlist,
          lambda r: str(r.version))

  do_unit(ConserveExitsRestriction(), sorted_rlist, lambda r: " ".join(r.flags))
  do_unit(FlagsRestriction([], ["Valid"]), sorted_rlist, lambda r: " ".join(r.flags))

  do_unit(IdHexRestriction("$FFCB46DB1339DA84674C70D7CB586434C4370441"),
          sorted_rlist, lambda r: r.idhex)

  rl =  [AtLeastNNodeRestriction([ExitPolicyRestriction("255.255.255.255", 80), ExitPolicyRestriction("255.255.255.255", 443), ExitPolicyRestriction("255.255.255.255", 6667)], 2), FlagsRestriction([], ["BadExit"])]

  exit_rstr = NodeRestrictionList(rl)

  ug = UniformGenerator(sorted_rlist, exit_rstr)

  ug.rewind()
  rlist = []
  for r in ug.generate():
    print "Checking: " + r.nickname
    for rs in rl:
      if not rs.r_is_ok(r):
        raise PathError()
    if not "Exit" in r.flags:
      print "No exit in flags of "+r.idhex
      for e in r.exitpolicy:
        print " "+str(e)
      print " 80: "+str(r.will_exit_to("255.255.255.255", 80))
      print " 443: "+str(r.will_exit_to("255.255.255.255", 443))
      print " 6667: "+str(r.will_exit_to("255.255.255.255", 6667))

    ug.mark_chosen(r)
    rlist.append(r)
  for r in sorted_rlist:
    if "Exit" in r.flags and not r in rlist:
      print r.idhex+" is an exit not in rl!"