128 lines
4.0 KiB
Swift
128 lines
4.0 KiB
Swift
//
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// Copyright (c) 2018 Open Whisper Systems. All rights reserved.
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//
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import Foundation
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import os
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@objc
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public class OutageDetection: NSObject {
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@objc(sharedManager)
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public static let shared = OutageDetection()
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@objc public static let outageStateDidChange = Notification.Name("OutageStateDidChange")
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// These properties should only be accessed on the main thread.
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@objc
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public var hasOutage = false {
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didSet {
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AssertIsOnMainThread()
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if hasOutage != oldValue {
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Logger.info("hasOutage: \(hasOutage).")
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NotificationCenter.default.postNotificationNameAsync(OutageDetection.outageStateDidChange, object: nil)
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}
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}
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}
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private var shouldCheckForOutage = false {
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didSet {
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AssertIsOnMainThread()
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ensureCheckTimer()
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}
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}
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// We only show the outage warning when we're certain there's an outage.
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// DNS lookup failures, etc. are not considered an outage.
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private func checkForOutageSync() -> Bool {
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let host = CFHostCreateWithName(nil, "uptime.signal.org" as CFString).takeRetainedValue()
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CFHostStartInfoResolution(host, .addresses, nil)
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var success: DarwinBoolean = false
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guard let addresses = CFHostGetAddressing(host, &success)?.takeUnretainedValue() as NSArray? else {
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Logger.error("CFHostGetAddressing failed: no addresses.")
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return false
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}
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guard success.boolValue else {
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Logger.error("CFHostGetAddressing failed.")
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return false
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}
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var isOutageDetected = false
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for case let address as NSData in addresses {
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var hostname = [CChar](repeating: 0, count: Int(NI_MAXHOST))
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if getnameinfo(address.bytes.assumingMemoryBound(to: sockaddr.self), socklen_t(address.length),
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&hostname, socklen_t(hostname.count), nil, 0, NI_NUMERICHOST) == 0 {
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let addressString = String(cString: hostname)
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let kHealthyAddress = "127.0.0.1"
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let kOutageAddress = "127.0.0.2"
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if addressString == kHealthyAddress {
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// Do nothing.
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} else if addressString == kOutageAddress {
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isOutageDetected = true
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} else {
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owsFailDebug("unexpected address: \(addressString)")
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}
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}
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}
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return isOutageDetected
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}
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private func checkForOutageAsync() {
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Logger.info("")
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DispatchQueue.global().async {
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let isOutageDetected = self.checkForOutageSync()
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DispatchQueue.main.async {
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self.hasOutage = isOutageDetected
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}
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}
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}
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private var checkTimer: Timer?
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private func ensureCheckTimer() {
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// Only monitor for outages in the main app.
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guard CurrentAppContext().isMainApp else {
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return
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}
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if shouldCheckForOutage {
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if checkTimer != nil {
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// Already has timer.
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return
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}
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// The TTL of the DNS record is 60 seconds.
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checkTimer = WeakTimer.scheduledTimer(timeInterval: 60, target: self, userInfo: nil, repeats: true) { [weak self] _ in
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AssertIsOnMainThread()
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guard CurrentAppContext().isMainAppAndActive else {
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return
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}
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guard let strongSelf = self else {
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return
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}
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strongSelf.checkForOutageAsync()
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}
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} else {
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checkTimer?.invalidate()
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checkTimer = nil
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}
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}
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@objc
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public func reportConnectionSuccess() {
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DispatchMainThreadSafe {
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self.shouldCheckForOutage = false
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self.hasOutage = false
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}
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}
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@objc
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public func reportConnectionFailure() {
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DispatchMainThreadSafe {
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self.shouldCheckForOutage = true
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}
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}
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}
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