490 lines
16 KiB
Swift
490 lines
16 KiB
Swift
//
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// TunnelKitProvider.swift
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// TunnelKit
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//
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// Created by Davide De Rosa on 2/1/17.
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// Copyright © 2018 London Trust Media. All rights reserved.
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//
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import NetworkExtension
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import SwiftyBeaver
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private let log = SwiftyBeaver.self
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/**
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Provides an all-in-one `NEPacketTunnelProvider` implementation for use in a
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Packet Tunnel Provider extension both on iOS and macOS.
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*/
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open class TunnelKitProvider: NEPacketTunnelProvider {
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// MARK: Tweaks
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/// An optional string describing host app version on tunnel start.
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public var appVersion: String?
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/// The log separator between sessions.
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public var logSeparator = "--- EOF ---"
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/// The maximum number of lines in the log.
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public var maxLogLines = 1000
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/// The number of milliseconds after which a DNS resolution fails.
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public var dnsTimeout = 3000
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/// The number of milliseconds after which the tunnel gives up on a connection attempt.
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public var socketTimeout = 5000
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/// The number of milliseconds after which the tunnel is shut down forcibly.
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public var shutdownTimeout = 2000
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/// The number of milliseconds after which a reconnection attempt is issued.
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public var reconnectionDelay = 1000
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/// The number of link failures after which the tunnel is expected to die.
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public var maxLinkFailures = 3
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// MARK: Constants
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private let memoryLog = MemoryDestination()
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private let observer = InterfaceObserver()
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private let tunnelQueue = DispatchQueue(label: TunnelKitProvider.description())
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private let prngSeedLength = 64
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private let caTmpFilename = "CA.pem"
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private var cachesURL: URL {
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return URL(fileURLWithPath: NSSearchPathForDirectoriesInDomains(.cachesDirectory, .userDomainMask, true)[0])
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}
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private var tmpCaURL: URL {
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return cachesURL.appendingPathComponent(caTmpFilename)
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}
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// MARK: Tunnel configuration
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private var cfg: Configuration!
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private var strategy: ConnectionStrategy!
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// MARK: Internal state
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private var proxy: SessionProxy?
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private var socket: GenericSocket?
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private var linkFailures = 0
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private var pendingStartHandler: ((Error?) -> Void)?
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private var pendingStopHandler: (() -> Void)?
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// MARK: NEPacketTunnelProvider (XPC queue)
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/// :nodoc:
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open override func startTunnel(options: [String : NSObject]? = nil, completionHandler: @escaping (Error?) -> Void) {
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let endpoint: AuthenticatedEndpoint
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do {
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guard let tunnelProtocol = protocolConfiguration as? NETunnelProviderProtocol else {
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throw ProviderError.configuration(field: "protocolConfiguration")
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}
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guard let providerConfiguration = tunnelProtocol.providerConfiguration else {
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throw ProviderError.configuration(field: "protocolConfiguration.providerConfiguration")
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}
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try endpoint = AuthenticatedEndpoint(protocolConfiguration: tunnelProtocol)
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try cfg = Configuration.parsed(from: providerConfiguration)
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} catch let e {
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var message: String?
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if let te = e as? ProviderError {
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switch te {
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case .credentials(let field):
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message = "Tunnel credentials unavailable: \(field)"
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case .configuration(let field):
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message = "Tunnel configuration incomplete: \(field)"
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default:
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break
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}
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}
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NSLog(message ?? "Unexpected error in tunnel configuration: \(e)")
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completionHandler(e)
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return
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}
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strategy = ConnectionStrategy(hostname: endpoint.hostname, configuration: cfg)
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if var existingLog = cfg.existingLog {
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if let i = existingLog.index(of: logSeparator) {
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existingLog.removeFirst(i + 2)
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}
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existingLog.append("")
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existingLog.append(logSeparator)
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existingLog.append("")
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memoryLog.start(with: existingLog)
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}
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configureLogging(
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debug: cfg.shouldDebug,
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customFormat: cfg.debugLogFormat
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)
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log.info("Starting tunnel...")
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guard EncryptionProxy.prepareRandomNumberGenerator(seedLength: prngSeedLength) else {
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completionHandler(ProviderError.prngInitialization)
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return
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}
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do {
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try cfg.handshake.write(to: tmpCaURL, custom: cfg.ca)
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} catch {
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completionHandler(ProviderError.certificateSerialization)
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return
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}
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cfg.print(appVersion: appVersion)
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let caPath = tmpCaURL.path
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// log.info("Temporary CA is stored to: \(caPath)")
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let encryption = SessionProxy.EncryptionParameters(cfg.cipher.rawValue, cfg.digest.rawValue, caPath, cfg.handshake.digest)
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let credentials = SessionProxy.Credentials(endpoint.username, endpoint.password)
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let proxy: SessionProxy
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do {
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proxy = try SessionProxy(queue: tunnelQueue, encryption: encryption, credentials: credentials)
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} catch let e {
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completionHandler(e)
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return
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}
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if let renegotiatesAfterSeconds = cfg.renegotiatesAfterSeconds {
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proxy.renegotiatesAfter = Double(renegotiatesAfterSeconds)
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}
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proxy.keepAliveInterval = CoreConfiguration.pingInterval
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proxy.delegate = self
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self.proxy = proxy
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logCurrentSSID()
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pendingStartHandler = completionHandler
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tunnelQueue.sync {
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self.connectTunnel()
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}
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}
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/// :nodoc:
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open override func stopTunnel(with reason: NEProviderStopReason, completionHandler: @escaping () -> Void) {
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pendingStartHandler = nil
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log.info("Stopping tunnel...")
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guard let proxy = proxy else {
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flushLog()
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completionHandler()
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return
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}
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pendingStopHandler = completionHandler
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tunnelQueue.schedule(after: .milliseconds(shutdownTimeout)) {
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guard let pendingHandler = self.pendingStopHandler else {
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return
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}
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log.warning("Tunnel not responding after \(self.shutdownTimeout) milliseconds, forcing stop")
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self.flushLog()
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pendingHandler()
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}
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tunnelQueue.sync {
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proxy.shutdown(error: nil)
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}
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}
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/// :nodoc:
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open override func handleAppMessage(_ messageData: Data, completionHandler: ((Data?) -> Void)? = nil) {
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var response: Data?
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switch Message(messageData) {
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case .requestLog:
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response = memoryLog.description.data(using: .utf8)
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case .dataCount:
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if let proxy = proxy {
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response = Data()
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response?.append(UInt64(proxy.bytesIn))
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response?.append(UInt64(proxy.bytesOut))
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}
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default:
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break
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}
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completionHandler?(response)
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}
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// MARK: Connection (tunnel queue)
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private func connectTunnel(upgradedSocket: GenericSocket? = nil, preferredAddress: String? = nil) {
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log.info("Creating link session")
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// reuse upgraded socket
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if let upgradedSocket = upgradedSocket, !upgradedSocket.isShutdown {
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log.debug("Socket follows a path upgrade")
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connectTunnel(via: upgradedSocket)
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return
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}
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strategy.createSocket(from: self, timeout: dnsTimeout, preferredAddress: preferredAddress, queue: tunnelQueue) { (socket, error) in
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guard let socket = socket else {
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self.disposeTunnel(error: error)
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return
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}
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self.connectTunnel(via: socket)
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}
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}
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private func connectTunnel(via socket: GenericSocket) {
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log.info("Will connect to \(socket)")
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log.debug("Socket type is \(type(of: socket))")
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self.socket = socket
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self.socket?.delegate = self
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self.socket?.observe(queue: tunnelQueue, activeTimeout: socketTimeout)
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}
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private func finishTunnelDisconnection(error: Error?) {
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if let proxy = proxy, !(reasserting && proxy.canRebindLink()) {
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proxy.cleanup()
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}
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socket?.delegate = nil
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socket?.unobserve()
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socket = nil
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if let error = error {
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log.error("Tunnel did stop (error: \(error))")
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} else {
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log.info("Tunnel did stop on request")
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}
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}
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private func disposeTunnel(error: Error?) {
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flushLog()
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// failed to start
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if (pendingStartHandler != nil) {
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//
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// CAUTION
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//
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// passing nil to this callback will result in an extremely undesired situation,
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// because NetworkExtension would interpret it as "successfully connected to VPN"
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//
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// if we end up here disposing the tunnel with a pending start handled, we are
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// 100% sure that something wrong happened while starting the tunnel. in such
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// case, here we then must also make sure that an error object is ALWAYS
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// provided, so we do this with optional fallback to .socketActivity
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//
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// socketActivity makes sense, given that any other error would normally come
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// from SessionProxy.stopError. other paths to disposeTunnel() are only coming
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// from stopTunnel(), in which case we don't need to feed an error parameter to
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// the stop completion handler
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//
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pendingStartHandler?(error ?? ProviderError.socketActivity)
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pendingStartHandler = nil
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}
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// stopped intentionally
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else if (pendingStopHandler != nil) {
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pendingStopHandler?()
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pendingStopHandler = nil
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}
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// stopped externally, unrecoverable
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else {
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let fm = FileManager.default
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try? fm.removeItem(at: tmpCaURL)
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cancelTunnelWithError(error)
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}
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}
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}
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extension TunnelKitProvider: GenericSocketDelegate {
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// MARK: GenericSocketDelegate (tunnel queue)
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func socketDidTimeout(_ socket: GenericSocket) {
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log.debug("Socket timed out waiting for activity, cancelling...")
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reasserting = true
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socket.shutdown()
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}
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func socketShouldChangeProtocol(_ socket: GenericSocket) {
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guard strategy.tryNextProtocol() else {
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disposeTunnel(error: ProviderError.exhaustedProtocols)
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return
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}
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}
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func socketDidBecomeActive(_ socket: GenericSocket) {
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guard let proxy = proxy else {
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return
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}
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if proxy.canRebindLink() {
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proxy.rebindLink(socket.link())
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reasserting = false
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} else {
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proxy.setLink(socket.link())
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}
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}
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func socket(_ socket: GenericSocket, didShutdownWithFailure failure: Bool) {
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guard let proxy = proxy else {
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return
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}
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// upgrade available?
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let upgradedSocket = socket.upgraded()
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var shutdownError: Error?
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if !failure {
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shutdownError = proxy.stopError
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} else {
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shutdownError = proxy.stopError ?? ProviderError.linkError
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linkFailures += 1
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log.debug("Link failures so far: \(linkFailures) (max = \(maxLinkFailures))")
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}
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// treat negotiation timeout as socket timeout, UDP is connection-less
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if proxy.stopError as? SessionError == SessionError.negotiationTimeout {
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socketShouldChangeProtocol(socket)
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}
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finishTunnelDisconnection(error: shutdownError)
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if reasserting {
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guard (linkFailures < maxLinkFailures) else {
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log.debug("Too many link failures (\(linkFailures)), tunnel will die now")
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reasserting = false
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disposeTunnel(error: shutdownError)
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return
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}
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log.debug("Disconnection is recoverable, tunnel will reconnect in \(reconnectionDelay) milliseconds...")
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tunnelQueue.schedule(after: .milliseconds(reconnectionDelay)) {
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self.connectTunnel(upgradedSocket: upgradedSocket, preferredAddress: socket.remoteAddress)
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}
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return
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}
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disposeTunnel(error: shutdownError)
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}
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func socketHasBetterPath(_ socket: GenericSocket) {
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log.debug("Stopping tunnel due to a new better path")
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logCurrentSSID()
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proxy?.reconnect(error: ProviderError.networkChanged)
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}
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}
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extension TunnelKitProvider: SessionProxyDelegate {
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// MARK: SessionProxyDelegate (tunnel queue)
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/// :nodoc:
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public func sessionDidStart(_ proxy: SessionProxy, remoteAddress: String, address: String, gatewayAddress: String, dnsServers: [String]) {
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reasserting = false
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log.info("Session did start")
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log.info("Returned ifconfig parameters:")
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log.info("\tTunnel: \(remoteAddress)")
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log.info("\tOwn address: \(address)")
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log.info("\tGateway: \(gatewayAddress)")
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log.info("\tDNS: \(dnsServers)")
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bringNetworkUp(tunnel: remoteAddress, vpn: address, gateway: gatewayAddress, dnsServers: dnsServers) { (error) in
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if let error = error {
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log.error("Failed to configure tunnel: \(error)")
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self.pendingStartHandler?(error)
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self.pendingStartHandler = nil
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return
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}
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log.info("Tunnel interface is now UP")
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proxy.setTunnel(tunnel: NETunnelInterface(impl: self.packetFlow))
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self.pendingStartHandler?(nil)
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self.pendingStartHandler = nil
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}
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}
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/// :nodoc:
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public func sessionDidStop(_: SessionProxy, shouldReconnect: Bool) {
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log.info("Session did stop")
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if shouldReconnect {
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reasserting = true
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}
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socket?.shutdown()
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}
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private func bringNetworkUp(tunnel: String, vpn: String, gateway: String, dnsServers: [String], completionHandler: @escaping (Error?) -> Void) {
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// route all traffic to VPN
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let defaultRoute = NEIPv4Route.default()
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defaultRoute.gatewayAddress = gateway
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let ipv4Settings = NEIPv4Settings(addresses: [vpn], subnetMasks: ["255.255.255.255"])
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ipv4Settings.includedRoutes = [defaultRoute]
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ipv4Settings.excludedRoutes = []
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let dnsSettings = NEDNSSettings(servers: dnsServers)
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let newSettings = NEPacketTunnelNetworkSettings(tunnelRemoteAddress: tunnel)
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newSettings.ipv4Settings = ipv4Settings
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newSettings.dnsSettings = dnsSettings
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newSettings.mtu = cfg.mtu
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setTunnelNetworkSettings(newSettings, completionHandler: completionHandler)
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}
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}
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extension TunnelKitProvider {
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// MARK: Helpers
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private func configureLogging(debug: Bool, customFormat: String? = nil) {
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let logLevel: SwiftyBeaver.Level = (debug ? .debug : .info)
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let logFormat = customFormat ?? "$Dyyyy-MM-dd HH:mm:ss.SSS$d $L $N.$F:$l - $M"
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if debug {
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let console = ConsoleDestination()
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console.useNSLog = true
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console.minLevel = logLevel
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console.format = logFormat
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log.addDestination(console)
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}
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let memory = memoryLog
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memory.minLevel = logLevel
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memory.format = logFormat
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memory.maxLines = maxLogLines
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log.addDestination(memoryLog)
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}
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private func flushLog() {
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log.debug("Flushing log...")
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if let defaults = cfg.defaults, let key = cfg.debugLogKey {
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memoryLog.flush(to: defaults, with: key)
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}
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}
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private func logCurrentSSID() {
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if let ssid = observer.currentWifiNetworkName() {
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log.debug("Current SSID: '\(ssid)'")
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} else {
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log.debug("Current SSID: none (disconnected from WiFi)")
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}
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}
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// private func anyPointer(_ object: Any?) -> UnsafeMutableRawPointer {
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// let anyObject = object as AnyObject
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// return Unmanaged<AnyObject>.passUnretained(anyObject).toOpaque()
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// }
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}
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