commit 2f0b14f116bcd77e04d7ddf7f7cff711edf6de0a Author: Karsten Loesing karsten.loesing@gmx.net Date: Tue Jul 17 21:44:16 2012 +0200
Calculate path-selection probabilities (#5755). --- task-5755/.gitignore | 11 + .../src/CalculatePathSelectionProbabilities.java | 246 ++++++++++++++++++++ 2 files changed, 257 insertions(+), 0 deletions(-)
diff --git a/task-5755/.gitignore b/task-5755/.gitignore new file mode 100644 index 0000000..5d5ac29 --- /dev/null +++ b/task-5755/.gitignore @@ -0,0 +1,11 @@ +.classpath +.project +*.pdf +bin/ +in/ +lib/ +*.csv +*.png +*.tar +*.tar.bz2 + diff --git a/task-5755/src/CalculatePathSelectionProbabilities.java b/task-5755/src/CalculatePathSelectionProbabilities.java new file mode 100644 index 0000000..369a994 --- /dev/null +++ b/task-5755/src/CalculatePathSelectionProbabilities.java @@ -0,0 +1,246 @@ +import java.io.BufferedWriter; +import java.io.File; +import java.io.FileWriter; +import java.text.SimpleDateFormat; +import java.util.Arrays; +import java.util.HashMap; +import java.util.Iterator; +import java.util.Map; +import java.util.SortedMap; +import java.util.SortedSet; +import java.util.TimeZone; +import java.util.TreeMap; +import java.util.TreeSet; + +import org.torproject.descriptor.Descriptor; +import org.torproject.descriptor.DescriptorFile; +import org.torproject.descriptor.DescriptorReader; +import org.torproject.descriptor.DescriptorSourceFactory; +import org.torproject.descriptor.NetworkStatusEntry; +import org.torproject.descriptor.RelayNetworkStatusConsensus; +import org.torproject.descriptor.ServerDescriptor; + +/* + * Calculate five path-selection probabilities for relays based on + * consensus weights and advertised bandwidths: + * + * - advertised_bandwidth_fraction: Relative advertised bandwidth of + * this relay compared to the total advertised bandwidth in the + * network. If there were no bandwidth authorities, this fraction + * would be the probability of this relay to be selected by clients. + * + * - consensus_weight_fraction: Fraction of this relay's consensus weight + * compared to the sum of all consensus weights in the network. This + * fraction is a very rough approximation of the probability of this + * relay to be selected by clients. + * + * - guard_probability: Probability of this relay to be selected for the + * guard position. This probability is calculated based on consensus + * weights, relay flags, directory ports, and bandwidth weights in the + * consensus. Path selection depends on more factors, so that this + * probability can only be an approximation. + * + * - middle_probability: Probability of this relay to be selected for the + * middle position. This probability is calculated based on consensus + * weights, relay flags, directory ports, and bandwidth weights in the + * consensus. Path selection depends on more factors, so that this + * probability can only be an approximation. + * + * - exit_probability: Probability of this relay to be selected for the + * exit position. This probability is calculated based on consensus + * weights, relay flags, directory ports, and bandwidth weights in the + * consensus. Path selection depends on more factors, so that this + * probability can only be an approximation. + */ +public class CalculatePathSelectionProbabilities { + public static void main(String[] args) throws Exception { + + /* Read advertised bandwidths of all server descriptors in + * in/server-descriptors/ to memory. This is a rather brute-force + * approach, but it's fine for running this analysis. */ + DescriptorReader descriptorReader = + DescriptorSourceFactory.createDescriptorReader(); + descriptorReader.addDirectory(new File("in/server-descriptors")); + Iterator<DescriptorFile> descriptorFiles = + descriptorReader.readDescriptors(); + Map<String, Integer> serverDescriptors = + new HashMap<String, Integer>(); + while (descriptorFiles.hasNext()) { + DescriptorFile descriptorFile = descriptorFiles.next(); + for (Descriptor descriptor : descriptorFile.getDescriptors()) { + if (!(descriptor instanceof ServerDescriptor)) { + continue; + } + ServerDescriptor serverDescriptor = (ServerDescriptor) descriptor; + String digest = serverDescriptor.getServerDescriptorDigest(); + int advertisedBandwidth = Math.min(Math.min( + serverDescriptor.getBandwidthBurst(), + serverDescriptor.getBandwidthObserved()), + serverDescriptor.getBandwidthRate()); + serverDescriptors.put(digest.toUpperCase(), advertisedBandwidth); + } + } + + /* Go through consensuses in in/consensuses/ in arbitrary order and + * calculate the five path-selection probabilities for each of them. + * Write results for a given consensuses to a single new line per + * relay to out.csv. */ + descriptorReader = DescriptorSourceFactory.createDescriptorReader(); + descriptorReader.addDirectory(new File("in/consensuses")); + descriptorFiles = descriptorReader.readDescriptors(); + BufferedWriter bw = new BufferedWriter(new FileWriter("out.csv")); + bw.write("validafter,fingerprint,advertised_bandwidth_fraction," + + "consensus_weight_fraction,guard_probability," + + "middle_probability,exit_probability\n"); + while (descriptorFiles.hasNext()) { + DescriptorFile descriptorFile = descriptorFiles.next(); + for (Descriptor descriptor : descriptorFile.getDescriptors()) { + if (!(descriptor instanceof RelayNetworkStatusConsensus)) { + continue; + } + RelayNetworkStatusConsensus consensus = + (RelayNetworkStatusConsensus) descriptor; + + /* Extract valid-after time and bandwidth weights from the parsed + * consensus. */ + SimpleDateFormat dateTimeFormat = new SimpleDateFormat( + "yyyy-MM-dd HH:mm:ss"); + dateTimeFormat.setTimeZone(TimeZone.getTimeZone("UTC")); + String validAfter = dateTimeFormat.format( + consensus.getValidAfterMillis()); + SortedMap<String, Integer> bandwidthWeights = + consensus.getBandwidthWeights(); + SortedSet<String> weightKeys = new TreeSet<String>(Arrays.asList(( + "Wgg,Wgm,Wgd,Wmg,Wmm,Wme,Wmd,Weg,Wem,Wee,Wed,Wgb,Wmb,Web,Wdb," + + "Wbg,Wbm,Wbe,Wbd").split(","))); + weightKeys.removeAll(bandwidthWeights.keySet()); + if (!weightKeys.isEmpty()) { + System.err.print("Consensus is missing bandwidth-weights:"); + for (String weightKey : weightKeys) { + System.err.print(" " + weightKey); + } + System.err.println(); + continue; + } + double wgg = ((double) bandwidthWeights.get("Wgg")) / 10000.0, + wgd = ((double) bandwidthWeights.get("Wgd")) / 10000.0, + wmg = ((double) bandwidthWeights.get("Wmg")) / 10000.0, + wmm = ((double) bandwidthWeights.get("Wmm")) / 10000.0, + wme = ((double) bandwidthWeights.get("Wme")) / 10000.0, + wmd = ((double) bandwidthWeights.get("Wmd")) / 10000.0, + wee = ((double) bandwidthWeights.get("Wee")) / 10000.0, + wed = ((double) bandwidthWeights.get("Wed")) / 10000.0; + + /* Go through network statuses and calculate the five weights for + * each of them. Also sum up totals to calculate probabilities + * later. */ + SortedMap<String, Double> + advertisedBandwidths = new TreeMap<String, Double>(), + consensusWeights = new TreeMap<String, Double>(), + guardWeights = new TreeMap<String, Double>(), + middleWeights = new TreeMap<String, Double>(), + exitWeights = new TreeMap<String, Double>(); + double totalAdvertisedBandwidth = 0.0; + double totalConsensusWeight = 0.0; + double totalGuardWeight = 0.0; + double totalMiddleWeight = 0.0; + double totalExitWeight = 0.0; + for (NetworkStatusEntry relay : + consensus.getStatusEntries().values()) { + String fingerprint = relay.getFingerprint(); + if (!relay.getFlags().contains("Running")) { + continue; + } + boolean isExit = relay.getFlags().contains("Exit") && + !relay.getFlags().contains("BadExit"); + boolean isGuard = relay.getFlags().contains("Guard"); + String serverDescriptorDigest = relay.getDescriptor(). + toUpperCase(); + double advertisedBandwidth; + if (!serverDescriptors.containsKey(serverDescriptorDigest)) { + System.err.println("Missing server descriptor " + + serverDescriptorDigest + " while processing consensus " + + validAfter + ". Setting advertised bandwidth to 0."); + advertisedBandwidth = 0.0; + } else { + advertisedBandwidth = (double) serverDescriptors.get( + serverDescriptorDigest); + } + double consensusWeight = (double) relay.getBandwidth(); + double guardWeight = (double) relay.getBandwidth(); + double middleWeight = (double) relay.getBandwidth(); + double exitWeight = (double) relay.getBandwidth(); + + /* Case 1: relay has both Guard and Exit flag and could be + * selected for either guard, middle, or exit position. Apply + * bandwidth weights W?d. */ + if (isGuard && isExit) { + guardWeight *= wgd; + middleWeight *= wmd; + exitWeight *= wed; + + /* Case 2: relay only has the Guard flag, not the Exit flag. + * While, in theory, the relay could also be picked for the exit + * position (if it has a weird exit policy), Weg is hard-coded + * to 0 here. Otherwise, relays with exit policy reject *:* + * would show up as possible exits, which makes no sense. Maybe + * this is too much of an oversimplification? For the other + * positions, apply bandwidth weights W?g. */ + } else if (isGuard) { + guardWeight *= wgg; + middleWeight *= wmg; + exitWeight = 0.0; + + /* Case 3: relay only has the Exit flag, not the Guard flag. It + * cannot be picked for the guard position, so set Wge to 0. + * For the other positions, apply bandwidth weights W?e. */ + } else if (isExit) { + guardWeight = 0.0; + middleWeight *= wme; + exitWeight *= wee; + + /* Case 4: relay has neither Exit nor Guard flag. Similar to + * case 2, this relay *could* have a weird exit policy and be + * picked in the exit position. Same rationale applies, so Wme + * is set to 0. The relay cannot be a guard, so Wgm is 0, too. + * For middle position, apply bandwidth weight Wmm. */ + } else { + guardWeight = 0.0; + middleWeight *= wmm; + exitWeight = 0.0; + } + + /* Store calculated weights and update totals. */ + advertisedBandwidths.put(fingerprint, advertisedBandwidth); + consensusWeights.put(fingerprint, consensusWeight); + guardWeights.put(fingerprint, guardWeight); + middleWeights.put(fingerprint, middleWeight); + exitWeights.put(fingerprint, exitWeight); + totalAdvertisedBandwidth += advertisedBandwidth; + totalConsensusWeight += consensusWeight; + totalGuardWeight += guardWeight; + totalMiddleWeight += middleWeight; + totalExitWeight += exitWeight; + } + + /* Write calculated path-selection probabilities to the output + * file. */ + for (NetworkStatusEntry relay : + consensus.getStatusEntries().values()) { + String fingerprint = relay.getFingerprint(); + bw.write(String.format("%s,%s,%.9f,%.9f,%.9f,%.9f,%.9f%n", + validAfter, + fingerprint, + advertisedBandwidths.get(fingerprint) + / totalAdvertisedBandwidth, + consensusWeights.get(fingerprint) / totalConsensusWeight, + guardWeights.get(fingerprint) / totalGuardWeight, + middleWeights.get(fingerprint) / totalMiddleWeight, + exitWeights.get(fingerprint) / totalExitWeight)); + } + } + } + bw.close(); + } +} +