def create_circuit(cons_rel_stats, cons_valid_after, cons_fresh_until,
cons_bw_weights, cons_bwweightscale, descriptors, hibernating_status,
guards, circ_time, circ_fast, circ_stable, circ_internal, circ_ip,
circ_port, congmodel, pdelmodel, weighted_exits=None,
exits_exact=False, weighted_middles=None, weighted_guards=None, callbacks=None):
"""Creates path for requested circuit based on the input consensus
statuses and descriptors. Uses congestion-aware path selection.
Inputs:
cons_rel_stats: (dict) relay fingerprint keys and relay status vals
cons_valid_after: (int) timestamp of valid_after for consensus
cons_fresh_until: (int) timestamp of fresh_until for consensus
cons_bw_weights: (dict) bw_weights of consensus
cons_bwweightscale: (should be float()able) bwweightscale of consensus
descriptors: (dict) relay fingerprint keys and descriptor vals
hibernating_status: (dict) indicates hibernating relays
guards: (dict) contains guards of requesting client
circ_time: (int) timestamp of circuit request
circ_fast: (bool) all relays should be fast
circ_stable: (bool) all relays should be stable
circ_internal: (bool) circuit is for name resolution or hidden service
circ_ip: (str) IP address of destination (None if not known)
circ_port: (int) desired TCP port (None if not known)
congmodel: congestion model
pdelmodel: propagation delay model
weighted_exits: (list) (middle, cum_weight) pairs for exit position
exits_exact: (bool) Is weighted_exits exact or does it need rechecking?
weighed_exits is special because exits are chosen first and thus
don't depend on the other circuit positions, and so potentially are
precomputed exactly.
weighted_middles: (list) (middle, cum_weight) pairs for middle position
weighted_guards: (list) (middle, cum_weight) pairs for middle position
callbacks: object w/ method circuit_creation(circuit)
Output:
circuit: (dict) a newly created circuit with keys
'time': (int) seconds from time zero
'fast': (bool) relays must have Fast flag
'stable': (bool) relays must have Stable flag
'internal': (bool) is internal (e.g. for hidden service)
'dirty_time': (int) timestamp of time dirtied, None if clean
'path': (tuple) list in-order fingerprints for path's nodes
'covering': (set) ports with needs covered by circuit
"""
# 'cons_rel_stats': (dict) relay stats for active consensus
if (circ_time < cons_valid_after) or\
(circ_time >= cons_fresh_until):
raise ValueError('consensus not fresh for circ_time in create_circuit')
# choose num_paths_choose paths, and choose one with best predicted latency
best_latency = None
best_path = None
for k in xrange(num_paths_choose):
print('Choosing path #{0} to predict latency'.format(k))
num_attempts = 0
ntor_supported = False
while (num_attempts < pathsim.TorOptions.max_populate_attempts) and\
(not ntor_supported):
# select exit node
i = 1
while (True):
exit_node = pathsim.select_exit_node(cons_bw_weights,
cons_bwweightscale,
cons_rel_stats, descriptors, circ_fast, circ_stable,
circ_internal, circ_ip, circ_port, weighted_exits, exits_exact)
# exit_node = select_weighted_node(weighted_exits)
if (not hibernating_status[exit_node]):
break
if _testing:
print('Exit selection #{0} is hibernating - retrying.'.\
format(i))
i += 1
if _testing:
print('Exit node: {0} [{1}]'.format(
cons_rel_stats[exit_node].nickname,
cons_rel_stats[exit_node].fingerprint))
# select guard node
# Hibernation status again checked here to reflect how in Tor
# new guards would be chosen and added to the list prior to a circuit-
# creation attempt. If the circuit fails at a new guard, that guard
# gets removed from the list.
while True:
# get first <= num_guards guards suitable for circuit
circ_guards = pathsim.get_guards_for_circ(cons_bw_weights,\
cons_bwweightscale, cons_rel_stats, descriptors,\
circ_fast, circ_stable, guards,\
exit_node, circ_time, weighted_guards)
guard_node = choice(circ_guards)
if (hibernating_status[guard_node]):
if (not guards[guard_node]['made_contact']):
if _testing:
print(\
'[Time {0}]: Removing new hibernating guard: {1}.'.\
format(circ_time, cons_rel_stats[guard_node].nickname))
del guards[guard_node]
elif (guards[guard_node]['unreachable_since'] != None):
if _testing:
print(\
'[Time {0}]: Guard retried but hibernating: {1}'.\
format(circ_time, cons_rel_stats[guard_node].nickname))
guards[guard_node]['last_attempted'] = circ_time
else:
if _testing:
print('[Time {0}]: Guard newly hibernating: {1}'.\
format(circ_time, \
cons_rel_stats[guard_node].nickname))
guards[guard_node]['unreachable_since'] = circ_time
guards[guard_node]['last_attempted'] = circ_time
else:
guards[guard_node]['unreachable_since'] = None
guards[guard_node]['made_contact'] = True
break
if _testing:
print('Guard node: {0} [{1}]'.format(
cons_rel_stats[guard_node].nickname,
cons_rel_stats[guard_node].fingerprint))
# select middle node
# As with exit selection, hibernating status checked here to mirror Tor
# selecting middle, having the circuit fail, reselecting a path,
# and attempting circuit creation again.
i = 1
while (True):
middle_node = pathsim.select_middle_node(cons_bw_weights,\
cons_bwweightscale, cons_rel_stats, descriptors, circ_fast,\
circ_stable, exit_node, guard_node, weighted_middles)
if (not hibernating_status[middle_node]):
break
if _testing:
print(\
'Middle selection #{0} is hibernating - retrying.'.format(i))
i += 1
if _testing:
print('Middle node: {0} [{1}]'.format(
cons_rel_stats[middle_node].nickname,
cons_rel_stats[middle_node].fingerprint))
# ensure one member of the circuit supports the ntor handshake
ntor_supported = pathsim.circuit_supports_ntor(guard_node, middle_node,
exit_node, descriptors)
num_attempts += 1
if pathsim._testing:
if ntor_supported:
print('Chose ntor-compatible circuit in {} tries'.\
format(num_attempts))
if (not ntor_supported):
raise ValueError('ntor-compatible circuit not found in {} tries'.\
format(num_attempts))
latency = #SAFEST TODO: get latency for circuit from SAFEST VCS service
if (best_latency == None) or (latency < best_latency):
best_latency = latency
best_circ = (guard_node, middle_node, exit_node)
circuit = {'time':circ_time,
'fast':circ_fast,
'stable':circ_stable,
'internal':circ_internal,
'dirty_time':None,
'path':best_circ,
'covering':set(),
'avg_ping':None}
# execute callback to allow logging on circuit creation
if (callbacks is not None):
callbacks.circuit_creation(circuit)
return circuit
def create_circuit(cons_rel_stats,
cons_valid_after,
cons_fresh_until,
cons_bw_weights,
cons_bwweightscale,
descriptors,
hibernating_status,
guards,
circ_time,
circ_fast,
circ_stable,
circ_internal,
circ_ip,
circ_port,
congmodel,
pdelmodel,
weighted_exits=None,
exits_exact=False,
weighted_middles=None,
weighted_guards=None,
callbacks=None):
"""Creates path for requested circuit based on the input consensus
statuses and descriptors. Uses congestion-aware path selection.
Inputs:
cons_rel_stats: (dict) relay fingerprint keys and relay status vals
cons_valid_after: (int) timestamp of valid_after for consensus
cons_fresh_until: (int) timestamp of fresh_until for consensus
cons_bw_weights: (dict) bw_weights of consensus
cons_bwweightscale: (should be float()able) bwweightscale of consensus
descriptors: (dict) relay fingerprint keys and descriptor vals
hibernating_status: (dict) indicates hibernating relays
guards: (dict) contains guards of requesting client
circ_time: (int) timestamp of circuit request
circ_fast: (bool) all relays should be fast
circ_stable: (bool) all relays should be stable
circ_internal: (bool) circuit is for name resolution or hidden service
circ_ip: (str) IP address of destination (None if not known)
circ_port: (int) desired TCP port (None if not known)
congmodel: congestion model
pdelmodel: propagation delay model
weighted_exits: (list) (middle, cum_weight) pairs for exit position
exits_exact: (bool) Is weighted_exits exact or does it need rechecking?
weighed_exits is special because exits are chosen first and thus
don't depend on the other circuit positions, and so potentially are
precomputed exactly.
weighted_middles: (list) (middle, cum_weight) pairs for middle position
weighted_guards: (list) (middle, cum_weight) pairs for middle position
callbacks: object w/ method circuit_creation(circuit)
Output:
circuit: (dict) a newly created circuit with keys
'time': (int) seconds from time zero
'fast': (bool) relays must have Fast flag
'stable': (bool) relays must have Stable flag
'internal': (bool) is internal (e.g. for hidden service)
'dirty_time': (int) timestamp of time dirtied, None if clean
'path': (tuple) list in-order fingerprints for path's nodes
'covering': (set) ports with needs covered by circuit
'avg_ping': (float) average ping time during most-recent use
"""
# 'cons_rel_stats': (dict) relay stats for active consensus
if (circ_time < cons_valid_after) or\
(circ_time >= cons_fresh_until):
raise ValueError('consensus not fresh for circ_time in create_circuit')
num_attempts = 0
ntor_supported = False
while (num_attempts < pathsim.TorOptions.max_populate_attempts) and\
(not ntor_supported):
# select exit node
i = 1
while (True):
exit_node = pathsim.select_exit_node(
cons_bw_weights, cons_bwweightscale, cons_rel_stats,
descriptors, circ_fast, circ_stable, circ_internal, circ_ip,
circ_port, weighted_exits, exits_exact)
# exit_node = pathsim.select_weighted_node(weighted_exits)
if (not hibernating_status[exit_node]):
break
if pathsim._testing:
print('Exit selection #{0} is hibernating - retrying.'.\
format(i))
i += 1
if pathsim._testing:
print('Exit node: {0} [{1}]'.format(
cons_rel_stats[exit_node].nickname,
cons_rel_stats[exit_node].fingerprint))
# select guard node
# Hibernation status again checked here to reflect how in Tor
# new guards would be chosen and added to the list prior to a circuit-
# creation attempt. If the circuit fails at a new guard, that guard
# gets removed from the list.
while True:
# get first <= num_guards guards suitable for circuit
circ_guards = pathsim.get_guards_for_circ(cons_bw_weights,\
cons_bwweightscale, cons_rel_stats, descriptors,\
circ_fast, circ_stable, guards,\
exit_node, circ_time, weighted_guards)
guard_node = choice(circ_guards)
if (hibernating_status[guard_node]):
if (not guards[guard_node]['made_contact']):
if pathsim._testing:
print(\
'[Time {0}]: Removing new hibernating guard: {1}.'.\
format(circ_time, cons_rel_stats[guard_node].nickname))
del guards[guard_node]
elif (guards[guard_node]['unreachable_since'] != None):
if pathsim._testing:
print(\
'[Time {0}]: Guard retried but hibernating: {1}'.\
format(circ_time, cons_rel_stats[guard_node].nickname))
guards[guard_node]['last_attempted'] = circ_time
else:
if pathsim._testing:
print('[Time {0}]: Guard newly hibernating: {1}'.\
format(circ_time, \
cons_rel_stats[guard_node].nickname))
guards[guard_node]['unreachable_since'] = circ_time
guards[guard_node]['last_attempted'] = circ_time
else:
guards[guard_node]['unreachable_since'] = None
guards[guard_node]['made_contact'] = True
break
if pathsim._testing:
print('Guard node: {0} [{1}]'.format(
cons_rel_stats[guard_node].nickname,
cons_rel_stats[guard_node].fingerprint))
# select middle node
# As with exit selection, hibernating status checked here to mirror Tor
# selecting middle, having the circuit fail, reselecting a path,
# and attempting circuit creation again.
i = 1
while (True):
middle_node = pathsim.select_middle_node(cons_bw_weights,\
cons_bwweightscale, cons_rel_stats, descriptors, circ_fast,\
circ_stable, exit_node, guard_node, weighted_middles)
if (not hibernating_status[middle_node]):
break
if pathsim._testing:
print(\
'Middle selection #{0} is hibernating - retrying.'.format(i))
i += 1
if pathsim._testing:
print('Middle node: {0} [{1}]'.format(
cons_rel_stats[middle_node].nickname,
cons_rel_stats[middle_node].fingerprint))
# ensure one member of the circuit supports the ntor handshake
ntor_supported = pathsim.circuit_supports_ntor(guard_node, middle_node,
exit_node, descriptors)
num_attempts += 1
if pathsim._testing:
if ntor_supported:
print('Chose ntor-compatible circuit in {} tries'.\
format(num_attempts))
if (not ntor_supported):
raise ValueError('ntor-compatible circuit not found in {} tries'.\
format(num_attempts))
cum_ping_time = 0
if pathsim._testing:
print 'Doing {0} circuit pings on creation... '.format(
num_pings_create),
for i in xrange(num_pings_create):
cum_ping_time += ping_circuit(client_ip, guard_node, middle_node,\
exit_node, cons_rel_stats, descriptors, congmodel, pdelmodel)
avg_ping_time = float(cum_ping_time) / num_pings_create
if pathsim._testing: print "ave congestion is {0}".format(avg_ping_time)
circuit = {
'time': circ_time,
'fast': circ_fast,
'stable': circ_stable,
'internal': circ_internal,
'dirty_time': None,
'path': (guard_node, middle_node, exit_node),
'covering': set(),
'initial_avg_ping': avg_ping_time,
'avg_ping': None
}
# execute callback to allow logging on circuit creation
if (callbacks is not None):
callbacks.circuit_creation(circuit)
return circuit
