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change port prediction API: allow puncher to retrieve NAT properties

This commit is contained in:
Christian Ulrich 2020-11-19 18:22:59 +01:00
parent 3f9d7a7671
commit cb9a43ea65
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GPG Key ID: 8241BE099775A097
2 changed files with 179 additions and 49 deletions
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225
port_prediction.nim
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@ -3,6 +3,28 @@ import net
import sequtils
import unittest
type
NatType* = enum
Unknown,
Cone,
SymmetricProgressive,
SymmetricRandom
NatProperties* = object
case natType*: NatType
of Unknown:
guess*: seq[uint16]
of Cone:
prediction*: uint16
of SymmetricProgressive:
order*: SortOrder
previousPort*: uint16
minDistance*: uint16
maxDistance*: uint16
of SymmetricRandom:
minPort*: uint16
maxPort*: uint16
const RandomPortCount = 10000'u16
proc min(a, b: uint16): uint16 =
@ -30,28 +52,29 @@ proc subtractOffset(port: uint16, offset: uint16, minValue = 1024'u16,
return maxValue - offset + distanceToMinValue + 1
return port - offset
proc predictPortRange*(localPort: uint16, probedPorts: seq[uint16]): seq[uint16] =
proc getNatProperties*(localPort: uint16, probedPorts: seq[uint16]):
NatProperties =
if probedPorts.len == 0:
# No probed ports, so our only guess can be that the NAT is a cone-type NAT
# and the port mapping preserves the local Port.
return @[localPort]
return NatProperties(natType: Unknown, guess: @[localPort])
if probedPorts.len == 1:
# Only one server was used for probing, so we cannot know if the NAT is
# symmetric or not. We are trying the probed port (assuming cone-type NAT)
# and the next port in a progressive sequence if applicable (assuming
# symmetric NAT with progressive port mapping).
result.add(probedPorts[0])
result = NatProperties(natType: Unknown, guess: @[probedPorts[0]])
if probedPorts[0] > localPort:
let offset = probedPorts[0] - localPort
result.add(probedPorts[0].addOffset(offset))
result.guess.add(probedPorts[0].addOffset(offset))
elif probedPorts[0] < localPort:
let offset = localPort - probedPorts[0]
result.add(probedPorts[0].subtractOffset(offset))
result.guess.add(probedPorts[0].subtractOffset(offset))
return
let deduplicatedPorts = probedPorts.deduplicate()
if deduplicatedPorts.len() == 1:
# It looks like the NAT is a cone-type NAT.
return deduplicatedPorts
return NatProperties(natType: Cone, prediction: deduplicatedPorts[0])
let probedPortsSorted = probedPorts.sorted()
let minPort = probedPortsSorted[probedPortsSorted.minIndex()]
let maxPort = probedPortsSorted[probedPortsSorted.maxIndex()]
@ -65,107 +88,213 @@ proc predictPortRange*(localPort: uint16, probedPorts: seq[uint16]): seq[uint16]
if maxDistance < 10:
if probedPorts.isSorted(Ascending):
# assume symmetric NAT with positive-progressive port mapping
if minDistance == maxDistance:
return @[maxPort.addOffset(maxDistance)]
else:
for i in countup(0'u16, maxDistance):
result.add(minPort.addOffset(i))
return
return NatProperties(natType: SymmetricProgressive,
order: Ascending, previousPort: maxPort,
minDistance: minDistance, maxDistance: maxDistance)
if probedPorts.isSorted(Descending):
# assume symmetric NAT with negative-progressive port mapping
if minDistance == maxDistance:
return @[minPort.subtractOffset(maxDistance)]
else:
for i in countup(0'u16, maxDistance):
result.add(maxPort.subtractOffset(i))
return
return NatProperties(natType: SymmetricProgressive,
order: Descending, previousPort: minPort,
minDistance: minDistance, maxDistance: maxDistance)
# assume symmetric NAT with random port mapping
assert(RandomPortCount mod 2 == 0)
let center = minPort + (maxPort - minPort) div 2
let half = RandomPortCount div 2
let first = if (1024'u16 + half) < center:
min(center - half, uint16.high - RandomPortCount + 1)
else:
1024'u16
result = newSeq[uint16](RandomPortCount)
for i in 0'u16 .. RandomPortCount - 1'u16:
result[i] = first + i
return NatProperties(natType: SymmetricRandom, minPort: minPort,
maxPort: maxPort)
proc predictPortRange*(localPort: Port, probedPorts: seq[Port]): seq[Port] =
predictPortRange(localPort.uint16, probedPorts.map(toUInt16)).map(toPort)
proc getNatProperties*(localPort: Port, probedPorts: seq[Port]): NatProperties =
getNatProperties(localPort.uint16, probedPorts.map(toUInt16))
proc predictPortRange*(props: NatProperties): seq[Port] =
case props.natType
of Unknown:
result = props.guess.map(toPort)
of Cone:
result = @[Port(props.prediction)]
of SymmetricProgressive:
if props.order == Ascending:
if props.minDistance == props.maxDistance:
return @[Port(props.previousPort.addOffset(props.maxDistance))]
else:
let minPort = props.previousPort - props.maxDistance
for i in countup(0'u16, props.maxDistance):
result.add(Port(minPort.addOffset(i)))
else:
if props.minDistance == props.maxDistance:
return @[Port(props.previousPort.subtractOffset(props.maxDistance))]
else:
let maxPort = props.previousPort + props.maxDistance
for i in countup(0'u16, props.maxDistance):
result.add(Port(maxPort.subtractOffset(i)))
of SymmetricRandom:
assert(RandomPortCount mod 2 == 0)
let center = props.minPort + (props.maxPort - props.minPort) div 2
let half = RandomPortCount div 2
let first = if (1024'u16 + half) < center:
min(center - half, uint16.high - RandomPortCount + 1)
else:
1024'u16
result = newSeq[Port](RandomPortCount)
for i in 0'u16 .. RandomPortCount - 1'u16:
result[i] = Port(first + i)
suite "port prediction tests":
test "single port":
let predicted = predictPortRange(Port(1234), @[])
let props = getNatProperties(1234'u16, @[])
check(props.natType == Unknown)
check(props.guess == @[1234'u16])
let predicted = predictPortRange(props)
check(predicted == @[Port(1234)])
test "single probe equal":
let predicted = predictPortRange(Port(1234), @[Port(1234)])
let props = getNatProperties(1234'u16, @[1234'u16])
check(props.natType == Unknown)
check(props.guess == @[1234'u16])
let predicted = predictPortRange(props)
check(predicted == @[Port(1234)])
test "single probe positive-progressive":
let predicted = predictPortRange(Port(1234), @[Port(1236)])
let props = getNatProperties(1234'u16, @[1236'u16])
check(props.natType == Unknown)
check(props.guess == @[1236'u16, 1238'u16])
let predicted = predictPortRange(props)
check(predicted == @[Port(1236), Port(1238)])
test "single probe negative-progressive":
let predicted = predictPortRange(Port(1234), @[Port(1232)])
let props = getNatProperties(1234'u16, @[1232'u16])
check(props.natType == Unknown)
check(props.guess == @[1232'u16, 1230'u16])
let predicted = predictPortRange(props)
check(predicted == @[Port(1232), Port(1230)])
test "all equal":
let predicted = predictPortRange(Port(1234), @[Port(1234), Port(1234)])
let props = getNatProperties(1234'u16, @[1234'u16, 1234'u16])
check(props.natType == Cone)
check(props.prediction == 1234'u16)
let predicted = predictPortRange(props)
check(predicted == @[Port(1234)])
test "positive-progressive, offset 1":
let predicted = predictPortRange(Port(1234), @[Port(2034), Port(2035)])
let props = getNatProperties(1234'u16, @[2034'u16, 2035'u16])
check(props.natType == SymmetricProgressive)
check(props.order == Ascending)
check(props.previousPort == 2035'u16)
check(props.minDistance == 1'u16)
check(props.maxDistance == 1'u16)
let predicted = predictPortRange(props)
check(predicted == @[Port(2036)])
test "positive-progressive, offset 9":
let predicted = predictPortRange(Port(1234), @[Port(2034), Port(2043)])
let props = getNatProperties(1234'u16, @[2034'u16, 2043'u16])
check(props.natType == SymmetricProgressive)
check(props.order == Ascending)
check(props.previousPort == 2043'u16)
check(props.minDistance == 9'u16)
check(props.maxDistance == 9'u16)
let predicted = predictPortRange(props)
check(predicted == @[Port(2052)])
test "negative-progressive, offset 1":
let predicted = predictPortRange(Port(1234), @[Port(1100), Port(1099)])
let props = getNatProperties(1234'u16, @[1100'u16, 1099'u16])
check(props.natType == SymmetricProgressive)
check(props.order == Descending)
check(props.previousPort == 1099'u16)
check(props.minDistance == 1'u16)
check(props.maxDistance == 1'u16)
let predicted = predictPortRange(props)
check(predicted == @[Port(1098)])
test "negative-progressive, offset 9":
let predicted = predictPortRange(Port(1234), @[Port(1100), Port(1091)])
let props = getNatProperties(1234'u16, @[1100'u16, 1091'u16])
check(props.natType == SymmetricProgressive)
check(props.order == Descending)
check(props.previousPort == 1091'u16)
check(props.minDistance == 9'u16)
check(props.maxDistance == 9'u16)
let predicted = predictPortRange(props)
check(predicted == @[Port(1082)])
test "positive-progressive, 3 probed ports, low offset":
let predicted = predictPortRange(Port(1234), @[Port(2000), Port(2000), Port(2002)])
let props = getNatProperties(1234'u16, @[2000'u16, 2000'u16, 2002'u16])
check(props.natType == SymmetricProgressive)
check(props.order == Ascending)
check(props.previousPort == 2002)
check(props.minDistance == 0'u16)
check(props.maxDistance == 2'u16)
let predicted = predictPortRange(props)
check(predicted == @[Port(2000), Port(2001), Port(2002)])
test "negative-progressive, 3 probed ports, low offset":
let predicted = predictPortRange(Port(1234), @[Port(2002), Port(2000), Port(2000)])
let props = getNatProperties(1234'u16, @[2002'u16, 2000'u16, 2000'u16])
check(props.natType == SymmetricProgressive)
check(props.order == Descending)
check(props.previousPort == 2000)
check(props.minDistance == 0'u16)
check(props.maxDistance == 2'u16)
let predicted = predictPortRange(props)
check(predicted == @[Port(2002), Port(2001), Port(2000)])
test "high port, positive-progressive, offset 1":
let predicted = predictPortRange(Port(1234), @[Port(65534), Port(65535)])
let props = getNatProperties(1234'u16, @[65534'u16, 65535'u16])
check(props.natType == SymmetricProgressive)
check(props.order == Ascending)
check(props.previousPort == 65535'u16)
check(props.minDistance == 1'u16)
check(props.maxDistance == 1'u16)
let predicted = predictPortRange(props)
check(predicted == @[Port(1024)])
test "high port, positive-progressive, offset 9":
let predicted = predictPortRange(Port(1234), @[Port(65520), Port(65529)])
let props = getNatProperties(1234'u16, @[65520'u16, 65529'u16])
check(props.natType == SymmetricProgressive)
check(props.order == Ascending)
check(props.previousPort == 65529'u16)
check(props.minDistance == 9'u16)
check(props.maxDistance == 9'u16)
let predicted = predictPortRange(props)
check(predicted == @[Port(1026)])
test "low port, negative-progressive, offset 1":
let predicted = predictPortRange(Port(1234), @[Port(1025), Port(1024)])
let props = getNatProperties(1234'u16, @[1025'u16, 1024'u16])
check(props.natType == SymmetricProgressive)
check(props.order == Descending)
check(props.previousPort == 1024'u16)
check(props.minDistance == 1'u16)
check(props.maxDistance == 1'u16)
let predicted = predictPortRange(props)
check(predicted == @[Port(65535)])
test "low port, negative-progressive, offset 9":
let predicted = predictPortRange(Port(1234), @[Port(1039), Port(1030)])
let props = getNatProperties(1234'u16, @[1039'u16, 1030'u16])
check(props.natType == SymmetricProgressive)
check(props.order == Descending)
check(props.previousPort == 1030'u16)
check(props.minDistance == 9'u16)
check(props.maxDistance == 9'u16)
let predicted = predictPortRange(props)
check(predicted == @[Port(65533)])
test "random mapping":
let predicted = predictPortRange(Port(1234), @[Port(20000), Port(24000)])
let props = getNatProperties(1234'u16, @[20000'u16, 24000'u16])
check(props.natType == SymmetricRandom)
check(props.minPort == 20000'u16)
check(props.maxPort == 24000'u16)
let predicted = predictPortRange(props)
let half = RandomPortCount div 2'u16
check(predicted == toSeq(countup(22000'u16 - half, 22000'u16 + half - 1)).map(toPort))
test "random mapping, low":
let predicted = predictPortRange(Port(1234), @[Port(1200), Port(1600)])
let props = getNatProperties(1234'u16, @[1200'u16, 1600'u16])
check(props.natType == SymmetricRandom)
check(props.minPort == 1200'u16)
check(props.maxPort == 1600'u16)
let predicted = predictPortRange(props)
check(predicted.len == RandomPortCount.int)
check(predicted == toSeq(countup(1024'u16, 1024'u16 + RandomPortCount - 1)).map(toPort))
test "random mapping, high":
let predicted = predictPortRange(Port(1234), @[Port(65000), Port(65400)])
let props = getNatProperties(1234'u16, @[65000'u16, 65400'u16])
check(props.natType == SymmetricRandom)
check(props.minPort == 65000'u16)
check(props.maxPort == 65400'u16)
let predicted = predictPortRange(props)
check(predicted.len == RandomPortCount.int)
check(predicted == toSeq(countup(uint16.high - RandomPortCount + 1, uint16.high)).map(toPort))

3
puncher.nim
View File

@ -42,7 +42,8 @@ proc punch(puncher: Puncher, peerIp: IpAddress, peerPort: Port,
peerProbedPorts: seq[Port], lowTTL: bool, msg: string):
Future[Attempt] {.async.} =
let punchFuture = newFuture[Port]("punch")
let predictedDstPorts = predictPortRange(peerPort, peerProbedPorts)
let natProps = getNatProperties(peerPort, peerProbedPorts)
let predictedDstPorts = predictPortRange(natProps)
let (_, myPort) = puncher.sock.getLocalAddr()
result = Attempt(srcPort: myPort, dstIp: peerIp, dstPorts: predictedDstPorts,
future: punchFuture)