Implemented loop detection for pathfinding and congestionn avoidance for announce rebroadcasts.

This commit is contained in:
Mark Qvist 2019-11-10 13:56:04 +01:00
parent 64c30488c2
commit 8e19d5bd97
2 changed files with 61 additions and 15 deletions

View File

@ -19,12 +19,19 @@ class Transport:
REACHABILITY_DIRECT = 0x01
REACHABILITY_TRANSPORT = 0x02
# TODO: Document the addition of random windows
# and max local rebroadcasts.
PATHFINDER_M = 18 # Max hops
PATHFINDER_C = 2.0 # Decay constant
PATHFINDER_R = 2 # Retransmit retries
PATHFINDER_T = 10 # Retry grace period
PATHFINDER_RW = 10 # Random window for announce rebroadcast
PATHFINDER_E = 60*15 # Path expiration in seconds
# TODO: Calculate an optimal number for this in
# various situations
LOCAL_REBROADCASTS_MAX = 2 # How many local rebroadcasts of an announce is allowed
interfaces = [] # All active interfaces
destinations = [] # All active destinations
pending_links = [] # Links that are being established
@ -32,8 +39,8 @@ class Transport:
packet_hashlist = [] # A list of packet hashes for duplicate detection
receipts = [] # Receipts of all outgoing packets for proof processing
announce_table = {}
destination_table = {}
announce_table = {} # A table for storing announces currently waiting to be retransmitted
destination_table = {} # A lookup table containing the next hop to a given destination
jobs_locked = False
jobs_running = False
@ -113,8 +120,7 @@ class Transport:
break
else:
if time.time() > announce_entry[1]:
# RNS.log("Rebroadcasting announce", RNS.LOG_INFO)
announce_entry[1] = time.time() + math.pow(Transport.PATHFINDER_C, announce_entry[4]) + Transport.PATHFINDER_T
announce_entry[1] = time.time() + math.pow(Transport.PATHFINDER_C, announce_entry[4]) + Transport.PATHFINDER_T + Transport.PATHFINDER_RW
announce_entry[2] += 1
packet = announce_entry[5]
announce_data = packet.data
@ -221,12 +227,21 @@ class Transport:
# Check if this is a next retransmission from
# another node. If it is, we're removing the
# announcein question from our pending table
# announce in question from our pending table
if packet.destination_hash in Transport.announce_table:
announce_entry = Transport.announce_table[packet.destination_hash]
if packet.hops == announce_entry[4]:
RNS.log("Heard a local rebroadcast of announce for "+RNS.prettyhexrep(packet.destination_hash), RNS.LOG_DEBUG)
announce_entry[6] += 1
if announce_entry[6] >= Transport.LOCAL_REBROADCASTS_MAX:
RNS.log("Max local rebroadcasts of announce for "+RNS.prettyhexrep(packet.destination_hash)+" reached, dropping announce from our table", RNS.LOG_DEBUG)
Transport.announce_table.pop(packet.destination_hash)
if packet.hops == announce_entry[4]+1 and announce_entry[2] > 0:
now = time.time()
if now < announce_entry[1]:
RNS.log("Rebroadcasted announce for "+RNS.prettyhexrep(packet.destination_hash)+" has been passed on to next node, no further tries needed", RNS.LOG_DEBUG)
Transport.announce_table.pop(packet.destination_hash)
else:
@ -236,20 +251,42 @@ class Transport:
# announce and destination tables
should_add = False
packet.hops += 1
# First, check that the announce is not for a destination
# local to this system, and that hops are less than the max
if (not any(packet.destination_hash == d.hash for d in Transport.destinations) and packet.hops < Transport.PATHFINDER_M+1):
random_blob = packet.data[RNS.Identity.DERKEYSIZE/8+10:RNS.Identity.DERKEYSIZE/8+20]
random_blobs = []
if packet.destination_hash in Transport.destination_table:
random_blobs = Transport.destination_table[packet.destination_hash][4]
# If we already have a path to the announced
# destination, but the hop count is equal or
# less, we'll update our tables.
if packet.hops <= Transport.destination_table[packet.destination_hash][2]:
# If we already have a path to the announced
# destination, but the hop count is equal or
# less, we'll update our tables.
should_add = True
# Make sure we haven't heard the random
# blob before, so announces can't be
# replayed to forge paths.
# TODO: Check whether this approach works
# under all circumstances
if not random_blob in random_blobs:
should_add = True
else:
should_add = False
else:
# If an announce arrives with a larger hop
# count than we already have in the table,
# ignore it, unless the path is expired
if (time.time() < Transport.destination_table[packet.destination_hash][3]):
RNS.log("Replacing destination table entry for "+str(RNS.prettyhexrep(packet.destination_hash))+" with new announce due to expired path", RNS.LOG_DEBUG)
should_add = True
if (time.time() > Transport.destination_table[packet.destination_hash][3]):
# We also check that the announce hash is
# different from ones we've already heard,
# to avoid loops in the network
if not random_blob in random_blobs:
# TODO: Check that this ^ approach actually
# works under all circumstances
RNS.log("Replacing destination table entry for "+str(RNS.prettyhexrep(packet.destination_hash))+" with new announce due to expired path", RNS.LOG_DEBUG)
should_add = True
else:
should_add = False
else:
should_add = False
else:
@ -261,9 +298,11 @@ class Transport:
now = time.time()
retries = 0
expires = now + Transport.PATHFINDER_E
retransmit_timeout = now + math.pow(Transport.PATHFINDER_C, packet.hops)
Transport.announce_table[packet.destination_hash] = [now, retransmit_timeout, retries, received_from, packet.hops, packet]
Transport.destination_table[packet.destination_hash] = [now, received_from, packet.hops, expires]
local_rebroadcasts = 0
random_blobs.append(random_blob)
retransmit_timeout = now + math.pow(Transport.PATHFINDER_C, packet.hops) + (RNS.rand() * Transport.PATHFINDER_RW)
Transport.announce_table[packet.destination_hash] = [now, retransmit_timeout, retries, received_from, packet.hops, packet, local_rebroadcasts]
Transport.destination_table[packet.destination_hash] = [now, received_from, packet.hops, expires, random_blobs]
elif packet.packet_type == RNS.Packet.LINKREQUEST:
for destination in Transport.destinations:

View File

@ -2,6 +2,7 @@ import os
import sys
import glob
import time
import random
from .Reticulum import Reticulum
from .Identity import Identity
@ -32,6 +33,8 @@ logfile = None
logdest = LOG_STDOUT
logtimefmt = "%Y-%m-%d %H:%M:%S"
random.seed(os.urandom(10))
def loglevelname(level):
if (level == LOG_CRITICAL):
return "Critical"
@ -66,6 +69,10 @@ def log(msg, level=3):
file.write(logstring+"\n")
file.close()
def rand():
result = random.random()
return result
def hexprint(data):
print(hexrep(hexrep))