Implemented loop detection for pathfinding and congestionn avoidance for announce rebroadcasts.
This commit is contained in:
Mark Qvist
parent
64c30488c2
commit
8e19d5bd97
@ -19,12 +19,19 @@ class Transport:
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REACHABILITY_DIRECT = 0x01
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REACHABILITY_TRANSPORT = 0x02
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# TODO: Document the addition of random windows
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# and max local rebroadcasts.
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PATHFINDER_M = 18 # Max hops
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PATHFINDER_C = 2.0 # Decay constant
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PATHFINDER_R = 2 # Retransmit retries
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PATHFINDER_T = 10 # Retry grace period
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PATHFINDER_RW = 10 # Random window for announce rebroadcast
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PATHFINDER_E = 60*15 # Path expiration in seconds
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# TODO: Calculate an optimal number for this in
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# various situations
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LOCAL_REBROADCASTS_MAX = 2 # How many local rebroadcasts of an announce is allowed
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interfaces = [] # All active interfaces
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destinations = [] # All active destinations
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pending_links = [] # Links that are being established
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@ -32,8 +39,8 @@ class Transport:
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packet_hashlist = [] # A list of packet hashes for duplicate detection
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receipts = [] # Receipts of all outgoing packets for proof processing
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announce_table = {}
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destination_table = {}
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announce_table = {} # A table for storing announces currently waiting to be retransmitted
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destination_table = {} # A lookup table containing the next hop to a given destination
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jobs_locked = False
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jobs_running = False
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@ -113,8 +120,7 @@ class Transport:
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break
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else:
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if time.time() > announce_entry[1]:
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# RNS.log("Rebroadcasting announce", RNS.LOG_INFO)
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announce_entry[1] = time.time() + math.pow(Transport.PATHFINDER_C, announce_entry[4]) + Transport.PATHFINDER_T
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announce_entry[1] = time.time() + math.pow(Transport.PATHFINDER_C, announce_entry[4]) + Transport.PATHFINDER_T + Transport.PATHFINDER_RW
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announce_entry[2] += 1
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packet = announce_entry[5]
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announce_data = packet.data
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@ -221,12 +227,21 @@ class Transport:
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# Check if this is a next retransmission from
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# another node. If it is, we're removing the
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# announcein question from our pending table
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# announce in question from our pending table
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if packet.destination_hash in Transport.announce_table:
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announce_entry = Transport.announce_table[packet.destination_hash]
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if packet.hops == announce_entry[4]:
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RNS.log("Heard a local rebroadcast of announce for "+RNS.prettyhexrep(packet.destination_hash), RNS.LOG_DEBUG)
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announce_entry[6] += 1
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if announce_entry[6] >= Transport.LOCAL_REBROADCASTS_MAX:
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RNS.log("Max local rebroadcasts of announce for "+RNS.prettyhexrep(packet.destination_hash)+" reached, dropping announce from our table", RNS.LOG_DEBUG)
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Transport.announce_table.pop(packet.destination_hash)
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if packet.hops == announce_entry[4]+1 and announce_entry[2] > 0:
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now = time.time()
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if now < announce_entry[1]:
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RNS.log("Rebroadcasted announce for "+RNS.prettyhexrep(packet.destination_hash)+" has been passed on to next node, no further tries needed", RNS.LOG_DEBUG)
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Transport.announce_table.pop(packet.destination_hash)
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else:
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@ -236,22 +251,44 @@ class Transport:
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# announce and destination tables
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should_add = False
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packet.hops += 1
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# First, check that the announce is not for a destination
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# local to this system, and that hops are less than the max
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if (not any(packet.destination_hash == d.hash for d in Transport.destinations) and packet.hops < Transport.PATHFINDER_M+1):
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random_blob = packet.data[RNS.Identity.DERKEYSIZE/8+10:RNS.Identity.DERKEYSIZE/8+20]
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random_blobs = []
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if packet.destination_hash in Transport.destination_table:
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if packet.hops <= Transport.destination_table[packet.destination_hash][2]:
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random_blobs = Transport.destination_table[packet.destination_hash][4]
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# If we already have a path to the announced
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# destination, but the hop count is equal or
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# less, we'll update our tables.
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if packet.hops <= Transport.destination_table[packet.destination_hash][2]:
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# Make sure we haven't heard the random
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# blob before, so announces can't be
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# replayed to forge paths.
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# TODO: Check whether this approach works
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# under all circumstances
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if not random_blob in random_blobs:
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should_add = True
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else:
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should_add = False
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else:
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# If an announce arrives with a larger hop
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# count than we already have in the table,
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# ignore it, unless the path is expired
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if (time.time() < Transport.destination_table[packet.destination_hash][3]):
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if (time.time() > Transport.destination_table[packet.destination_hash][3]):
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# We also check that the announce hash is
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# different from ones we've already heard,
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# to avoid loops in the network
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if not random_blob in random_blobs:
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# TODO: Check that this ^ approach actually
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# works under all circumstances
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RNS.log("Replacing destination table entry for "+str(RNS.prettyhexrep(packet.destination_hash))+" with new announce due to expired path", RNS.LOG_DEBUG)
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should_add = True
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else:
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should_add = False
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else:
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should_add = False
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else:
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# If this destination is unknown in our table
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# we should add it
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@ -261,9 +298,11 @@ class Transport:
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now = time.time()
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retries = 0
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expires = now + Transport.PATHFINDER_E
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retransmit_timeout = now + math.pow(Transport.PATHFINDER_C, packet.hops)
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Transport.announce_table[packet.destination_hash] = [now, retransmit_timeout, retries, received_from, packet.hops, packet]
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Transport.destination_table[packet.destination_hash] = [now, received_from, packet.hops, expires]
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local_rebroadcasts = 0
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random_blobs.append(random_blob)
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retransmit_timeout = now + math.pow(Transport.PATHFINDER_C, packet.hops) + (RNS.rand() * Transport.PATHFINDER_RW)
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Transport.announce_table[packet.destination_hash] = [now, retransmit_timeout, retries, received_from, packet.hops, packet, local_rebroadcasts]
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Transport.destination_table[packet.destination_hash] = [now, received_from, packet.hops, expires, random_blobs]
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elif packet.packet_type == RNS.Packet.LINKREQUEST:
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for destination in Transport.destinations:
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@ -2,6 +2,7 @@ import os
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import sys
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import glob
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import time
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import random
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from .Reticulum import Reticulum
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from .Identity import Identity
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@ -32,6 +33,8 @@ logfile = None
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logdest = LOG_STDOUT
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logtimefmt = "%Y-%m-%d %H:%M:%S"
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random.seed(os.urandom(10))
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def loglevelname(level):
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if (level == LOG_CRITICAL):
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return "Critical"
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@ -66,6 +69,10 @@ def log(msg, level=3):
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file.write(logstring+"\n")
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file.close()
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def rand():
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result = random.random()
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return result
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def hexprint(data):
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print(hexrep(hexrep))
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