[or-cvs] r15294: Implement "new" Tor guard+exit bw-weighted selection algorit (torflow/branches/gsoc2008/TorCtl)
mikeperry at seul.org
mikeperry at seul.org
Mon Jun 16 01:42:10 UTC 2008
Author: mikeperry
Date: 2008-06-15 21:42:10 -0400 (Sun, 15 Jun 2008)
New Revision: 15294
Modified:
torflow/branches/gsoc2008/TorCtl/PathSupport.py
Log:
Implement "new" Tor guard+exit bw-weighted selection
algorithm. Also add unit tests used for verification. Seems
to be performing sensibly.
Modified: torflow/branches/gsoc2008/TorCtl/PathSupport.py
===================================================================
--- torflow/branches/gsoc2008/TorCtl/PathSupport.py 2008-06-16 01:14:02 UTC (rev 15293)
+++ torflow/branches/gsoc2008/TorCtl/PathSupport.py 2008-06-16 01:42:10 UTC (rev 15294)
@@ -47,6 +47,7 @@
import copy
import Queue
import time
+import TorUtil
from TorUtil import *
__all__ = ["NodeRestrictionList", "PathRestrictionList",
@@ -142,6 +143,9 @@
def rewind(self):
"Rewind the generator to the 'beginning'"
+ # FIXME: If we apply the restrictions now, we can save cycles
+ # during selection, and also some memory overhead (at the cost
+ # of a much slower rewind() though..)
self.routers = copy.copy(self.sorted_r)
def mark_chosen(self, r):
@@ -532,77 +536,118 @@
break
class BwWeightedGenerator(NodeGenerator):
- def __init__(self, sorted_r, rstr_list, pathlen, exit=False):
+ """
+ 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 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.exit_bw_to_dest = 0
+ self.total_guard_bw = 0
+ self.total_weighted_bw = 0
self.pathlen = pathlen
NodeGenerator.__init__(self, sorted_r, rstr_list)
def rewind(self):
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.sorted_r:
+ # Should this be outside the restriction checks?
+ # TODO: Check max_bandwidth and cap...
+ if self.rstr_list.r_is_ok(r):
+ 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_bw_to_dest = 0
- # We are choosing an exit-node
- for r in self.sorted_r:
- if self.rstr_list.r_is_ok(r):
- self.exit_bw_to_dest += r.bw
- plog("DEBUG", "Exit-bandwidth to this destination is " +
- str(self.exit_bw_to_dest))
- self.weight = 1.0
+ self.exit_weight = 1.0
else:
- # We are choosing a non-exit
- self.total_exit_bw = 0
- self.total_bw = 0
- for r in self.sorted_r:
- # Should this be outside the restriction checks?
- if self.rstr_list.r_is_ok(r):
- self.total_bw += r.bw
- if "Exit" in r.flags:
- self.total_exit_bw += r.bw
-
- bw_per_hop = (1.0*self.total_bw)/self.pathlen
- if self.total_bw > 0:
- ratio = self.total_exit_bw/float(self.total_bw)
- else: ratio = 0
- plog("DEBUG", "E = " + str(self.total_exit_bw) +
- ", T = " + str(self.total_bw) +
- ", ratio = " + str(ratio) +
- ", bw_per_hop = " + str(bw_per_hop))
-
if self.total_exit_bw < bw_per_hop:
# Don't use exit nodes at all
- # add a ConserveExitsRestriction?
- self.weight = 0
+ self.exit_weight = 0
else:
if self.total_exit_bw > 0:
- self.weight = ((self.total_exit_bw-bw_per_hop)/self.total_exit_bw)
- else: self.weight = 0
- plog("DEBUG", "The exit-weight is: " + str(self.weight))
+ 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.sorted_r:
+ 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 next_r(self):
while True:
# Choose a suitable random int
- if self.exit:
- i = random.randint(0, self.exit_bw_to_dest)
- else:
- i = random.randint(0,
- (self.total_bw-self.total_exit_bw) # nonexit
- +int(self.total_exit_bw*self.weight)) # + weighted exit
+ i = random.randint(0, self.total_weighted_bw)
+
# Go through the routers
for r in self.routers:
- # Below zero here --> choose a new random int+router
+ # Below zero here means next() -> choose a new random int+router
if i < 0: break
if self.rstr_list.r_is_ok(r):
- # Only weight exit nodes
+ bw = r.bw
if "Exit" in r.flags:
- i -= self.weight * r.bw
- else: i -= r.bw
+ 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
@@ -734,7 +779,7 @@
self.exit_rstr.add_restriction(CountryCodeRestriction())
# Specified countries for different positions
- if self.geoip_config.entry_country:
+ 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))
@@ -747,7 +792,7 @@
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))
+ self.exit_rstr.add_restriction(ExcludeCountriesRestriction(self.geoip_config.excludes))
# Unique countries set? None --> pass
if self.geoip_config.unique_countries != None:
@@ -776,7 +821,7 @@
OrderedExitGenerator(80, sorted_r, self.exit_rstr)
elif self.uniform:
# 'real' exits should also be chosen when not using 'order_exits'
- self.exit_rstr.add_restriction(ExitPolicyRestriction("255.255.255.255", 80))
+ self.exit_rstr.add_restriction(ExitPolicyRestriction("255.255.255.255", 80))
exitgen = UniformGenerator(sorted_r, self.exit_rstr)
else:
self.exit_rstr.add_restriction(ExitPolicyRestriction("255.255.255.255", 80))
@@ -792,7 +837,8 @@
entry_rstr.del_restriction(ConserveExitsRestriction)
mid_rstr.del_restriction(ConserveExitsRestriction)
self.path_selector = PathSelector(
- BwWeightedGenerator(sorted_r, entry_rstr, self.pathlen),
+ BwWeightedGenerator(sorted_r, entry_rstr, self.pathlen,
+ guard=self.use_guards),
BwWeightedGenerator(sorted_r, mid_rstr, self.pathlen),
exitgen, self.path_rstr)
return
@@ -1487,6 +1533,49 @@
########################## 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() - Just overhead if we create a fresh generator each time
+ rtrs = gen.next_r()
+ 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 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)+"/"+str(bw/1024)+": "+str(r.chosen)+", "+flag
+ i += 1
+ if i > num_print: break
+
def do_unit(rst, r_list, plamb):
print "\n"
print "-----------------------------------"
@@ -1516,7 +1605,7 @@
if __name__ == '__main__':
s = socket.socket(socket.AF_INET, socket.SOCK_STREAM)
- s.connect(("127.0.0.1",9061))
+ s.connect(("127.0.0.1",9051))
c = Connection(s)
c.debug(file("control.log", "w"))
c.authenticate()
@@ -1525,14 +1614,35 @@
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
+
+ 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)
+
+ exit(0)
+
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))
- exit(0)
do_unit(ExitPolicyRestriction("2.11.2.2", 80), sorted_rlist,
lambda r: "exits to 80")
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