Add methods for automatically detecting the Pi-Hole

As soon as the user starts up the app, we'll first try to ping their DNS
server, as that should in theory be the Pi-Hole. If that doesn't work,
then we offer the user the chance to either scan their network or
manually enter in the IP address for their Pi.

.gitignore

@@ -0,0 +1,90 @@
+# Xcode
+#
+# gitignore contributors: remember to update Global/Xcode.gitignore, Objective-C.gitignore & Swift.gitignore
+
+## User settings
+xcuserdata/
+
+## compatibility with Xcode 8 and earlier (ignoring not required starting Xcode 9)
+*.xcscmblueprint
+*.xccheckout
+
+## compatibility with Xcode 3 and earlier (ignoring not required starting Xcode 4)
+build/
+DerivedData/
+*.moved-aside
+*.pbxuser
+!default.pbxuser
+*.mode1v3
+!default.mode1v3
+*.mode2v3
+!default.mode2v3
+*.perspectivev3
+!default.perspectivev3
+
+## Obj-C/Swift specific
+*.hmap
+
+## App packaging
+*.ipa
+*.dSYM.zip
+*.dSYM
+
+## Playgrounds
+timeline.xctimeline
+playground.xcworkspace
+
+# Swift Package Manager
+#
+# Add this line if you want to avoid checking in source code from Swift Package Manager dependencies.
+# Packages/
+# Package.pins
+# Package.resolved
+# *.xcodeproj
+#
+# Xcode automatically generates this directory with a .xcworkspacedata file and xcuserdata
+# hence it is not needed unless you have added a package configuration file to your project
+# .swiftpm
+
+.build/
+
+# CocoaPods
+#
+# We recommend against adding the Pods directory to your .gitignore. However
+# you should judge for yourself, the pros and cons are mentioned at:
+# https://guides.cocoapods.org/using/using-cocoapods.html#should-i-check-the-pods-directory-into-source-control
+#
+# Pods/
+#
+# Add this line if you want to avoid checking in source code from the Xcode workspace
+# *.xcworkspace
+
+# Carthage
+#
+# Add this line if you want to avoid checking in source code from Carthage dependencies.
+# Carthage/Checkouts
+
+Carthage/Build/
+
+# Accio dependency management
+Dependencies/
+.accio/
+
+# fastlane
+#
+# It is recommended to not store the screenshots in the git repo.
+# Instead, use fastlane to re-generate the screenshots whenever they are needed.
+# For more information about the recommended setup visit:
+# https://docs.fastlane.tools/best-practices/source-control/#source-control
+
+fastlane/report.xml
+fastlane/Preview.html
+fastlane/screenshots/**/*.png
+fastlane/test_output
+
+# Code Injection
+#
+# After new code Injection tools there's a generated folder /iOSInjectionProject
+# https://github.com/johnno1962/injectionforxcode
+
+iOSInjectionProject/

Pi-Helper.xcodeproj/project.pbxproj

@@ -22,6 +22,9 @@
 		282126AE235BF21D00072D52 /* AddPiHoleView.swift in Sources */ = {isa = PBXBuildFile; fileRef = 282126AD235BF21D00072D52 /* AddPiHoleView.swift */; };
 		282126B0235BF52F00072D52 /* ActivityIndicatorView.swift in Sources */ = {isa = PBXBuildFile; fileRef = 282126AF235BF52F00072D52 /* ActivityIndicatorView.swift */; };
 		282126B4235C0F5400072D52 /* Localizable.strings in Resources */ = {isa = PBXBuildFile; fileRef = 282126B6235C0F5400072D52 /* Localizable.strings */; };
+		28D72051238067F30038D439 /* libresolv.9.tbd in Frameworks */ = {isa = PBXBuildFile; fileRef = 28D72050238067EC0038D439 /* libresolv.9.tbd */; };
+		28D7205923808E8C0038D439 /* Extensions.swift in Sources */ = {isa = PBXBuildFile; fileRef = 28D7205823808E8C0038D439 /* Extensions.swift */; };
+		28D7205C2380C2090038D439 /* resolver.c in Sources */ = {isa = PBXBuildFile; fileRef = 28D7205B2380C2090038D439 /* resolver.c */; };
 /* End PBXBuildFile section */
 
 /* Begin PBXContainerItemProxy section */
@@ -65,6 +68,12 @@
 		282126B3235C0EBF00072D52 /* es-419 */ = {isa = PBXFileReference; lastKnownFileType = text.plist.strings; name = "es-419"; path = "es-419.lproj/LaunchScreen.strings"; sourceTree = "<group>"; };
 		282126B5235C0F5400072D52 /* en */ = {isa = PBXFileReference; lastKnownFileType = text.plist.strings; name = en; path = en.lproj/Localizable.strings; sourceTree = "<group>"; };
 		282126B8235C0F8400072D52 /* es-419 */ = {isa = PBXFileReference; lastKnownFileType = text.plist.strings; name = "es-419"; path = "es-419.lproj/Localizable.strings"; sourceTree = "<group>"; };
+		28D7204E238067B20038D439 /* libresolv.tbd */ = {isa = PBXFileReference; lastKnownFileType = "sourcecode.text-based-dylib-definition"; name = libresolv.tbd; path = usr/lib/libresolv.tbd; sourceTree = SDKROOT; };
+		28D72050238067EC0038D439 /* libresolv.9.tbd */ = {isa = PBXFileReference; lastKnownFileType = "sourcecode.text-based-dylib-definition"; name = libresolv.9.tbd; path = usr/lib/libresolv.9.tbd; sourceTree = SDKROOT; };
+		28D720522380689E0038D439 /* Pi-Helper-Bridging-Header.h */ = {isa = PBXFileReference; lastKnownFileType = sourcecode.c.h; path = "Pi-Helper-Bridging-Header.h"; sourceTree = "<group>"; };
+		28D7205823808E8C0038D439 /* Extensions.swift */ = {isa = PBXFileReference; lastKnownFileType = sourcecode.swift; path = Extensions.swift; sourceTree = "<group>"; };
+		28D7205A2380C2090038D439 /* resolver.h */ = {isa = PBXFileReference; lastKnownFileType = sourcecode.c.h; path = resolver.h; sourceTree = "<group>"; };
+		28D7205B2380C2090038D439 /* resolver.c */ = {isa = PBXFileReference; lastKnownFileType = sourcecode.c.c; path = resolver.c; sourceTree = "<group>"; };
 /* End PBXFileReference section */
 
 /* Begin PBXFrameworksBuildPhase section */
@@ -72,6 +81,7 @@
 			isa = PBXFrameworksBuildPhase;
 			buildActionMask = 2147483647;
 			files = (
+				28D72051238067F30038D439 /* libresolv.9.tbd in Frameworks */,
 			);
 			runOnlyForDeploymentPostprocessing = 0;
 		};
@@ -99,6 +109,7 @@
 				28212685235926EB00072D52 /* Pi-HelperTests */,
 				28212690235926EB00072D52 /* Pi-HelperUITests */,
 				2821266D235926E700072D52 /* Products */,
+				28D7204D238067B20038D439 /* Frameworks */,
 			);
 			sourceTree = "<group>";
 		};
@@ -115,6 +126,7 @@
 		2821266E235926E700072D52 /* Pi-Helper */ = {
 			isa = PBXGroup;
 			children = (
+				28D720522380689E0038D439 /* Pi-Helper-Bridging-Header.h */,
 				2821266F235926E700072D52 /* AppDelegate.swift */,
 				28212671235926E700072D52 /* SceneDelegate.swift */,
 				28212673235926E700072D52 /* ContentView.swift */,
@@ -129,6 +141,9 @@
 				282126AB235BF09800072D52 /* PiHoleDetailsView.swift */,
 				282126AF235BF52F00072D52 /* ActivityIndicatorView.swift */,
 				282126B6235C0F5400072D52 /* Localizable.strings */,
+				28D7205823808E8C0038D439 /* Extensions.swift */,
+				28D7205A2380C2090038D439 /* resolver.h */,
+				28D7205B2380C2090038D439 /* resolver.c */,
 			);
 			path = "Pi-Helper";
 			sourceTree = "<group>";
@@ -159,6 +174,15 @@
 			path = "Pi-HelperUITests";
 			sourceTree = "<group>";
 		};
+		28D7204D238067B20038D439 /* Frameworks */ = {
+			isa = PBXGroup;
+			children = (
+				28D72050238067EC0038D439 /* libresolv.9.tbd */,
+				28D7204E238067B20038D439 /* libresolv.tbd */,
+			);
+			name = Frameworks;
+			sourceTree = "<group>";
+		};
 /* End PBXGroup section */
 
 /* Begin PBXNativeTarget section */
@@ -227,6 +251,7 @@
 				TargetAttributes = {
 					2821266B235926E700072D52 = {
 						CreatedOnToolsVersion = 11.0;
+						LastSwiftMigration = 1120;
 					};
 					28212681235926EB00072D52 = {
 						CreatedOnToolsVersion = 11.0;
@@ -297,9 +322,11 @@
 				282126AA235BEE0F00072D52 /* PiHoleApiService.swift in Sources */,
 				282126AE235BF21D00072D52 /* AddPiHoleView.swift in Sources */,
 				28212670235926E700072D52 /* AppDelegate.swift in Sources */,
+				28D7205C2380C2090038D439 /* resolver.c in Sources */,
 				28212672235926E700072D52 /* SceneDelegate.swift in Sources */,
 				282126B0235BF52F00072D52 /* ActivityIndicatorView.swift in Sources */,
 				28212674235926E700072D52 /* ContentView.swift in Sources */,
+				28D7205923808E8C0038D439 /* Extensions.swift in Sources */,
 				282126A8235BE72800072D52 /* PiHole.swift in Sources */,
 			);
 			runOnlyForDeploymentPostprocessing = 0;
@@ -477,6 +504,7 @@
 			isa = XCBuildConfiguration;
 			buildSettings = {
 				ASSETCATALOG_COMPILER_APPICON_NAME = AppIcon;
+				CLANG_ENABLE_MODULES = YES;
 				CODE_SIGN_STYLE = Automatic;
 				DEVELOPMENT_ASSET_PATHS = "\"Pi-Helper/Preview Content\"";
 				DEVELOPMENT_TEAM = 9Z6DE6KNJ9;
@@ -488,6 +516,8 @@
 				);
 				PRODUCT_BUNDLE_IDENTIFIER = "com.wbrawner.Pi-Helper";
 				PRODUCT_NAME = "$(TARGET_NAME)";
+				SWIFT_OBJC_BRIDGING_HEADER = "Pi-Helper/Pi-Helper-Bridging-Header.h";
+				SWIFT_OPTIMIZATION_LEVEL = "-Onone";
 				SWIFT_VERSION = 5.0;
 				TARGETED_DEVICE_FAMILY = "1,2";
 			};
@@ -497,6 +527,7 @@
 			isa = XCBuildConfiguration;
 			buildSettings = {
 				ASSETCATALOG_COMPILER_APPICON_NAME = AppIcon;
+				CLANG_ENABLE_MODULES = YES;
 				CODE_SIGN_STYLE = Automatic;
 				DEVELOPMENT_ASSET_PATHS = "\"Pi-Helper/Preview Content\"";
 				DEVELOPMENT_TEAM = 9Z6DE6KNJ9;
@@ -508,6 +539,7 @@
 				);
 				PRODUCT_BUNDLE_IDENTIFIER = "com.wbrawner.Pi-Helper";
 				PRODUCT_NAME = "$(TARGET_NAME)";
+				SWIFT_OBJC_BRIDGING_HEADER = "Pi-Helper/Pi-Helper-Bridging-Header.h";
 				SWIFT_VERSION = 5.0;
 				TARGETED_DEVICE_FAMILY = "1,2";
 			};

Pi-Helper.xcodeproj/xcuserdata/billy.xcuserdatad/xcdebugger/Breakpoints_v2.xcbkptlist

@@ -1,168 +0,0 @@
-<?xml version="1.0" encoding="UTF-8"?>
-<Bucket
-   uuid = "59EB2C60-D493-44EF-8FB1-43FCFB54B3E8"
-   type = "1"
-   version = "2.0">
-   <Breakpoints>
-      <BreakpointProxy
-         BreakpointExtensionID = "Xcode.Breakpoint.FileBreakpoint">
-         <BreakpointContent
-            uuid = "794E3259-7833-47A1-B889-ACE3E7B7B788"
-            shouldBeEnabled = "No"
-            ignoreCount = "0"
-            continueAfterRunningActions = "No"
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-            landmarkName = "loadSummary(_:apiKey:)"
-            landmarkType = "7">
-         </BreakpointContent>
-      </BreakpointProxy>
-      <BreakpointProxy
-         BreakpointExtensionID = "Xcode.Breakpoint.FileBreakpoint">
-         <BreakpointContent
-            uuid = "70FF2209-0733-48C4-B198-1F58A9D129D8"
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Pi-Helper/AddPiHoleView.swift

@@ -9,17 +9,22 @@
 import SwiftUI
 
 struct AddPiHoleView: View {
-    @State var ipAddress: String = ""
+    var statefulContent: AnyView {
-    @State var apiKey: String = ""
+        switch self.dataStore.pihole {
+        case .failure(let piholeError):
+            switch piholeError {
+            case .scanning(let ipAddress):
+                return ScanningView(dataStore: self.dataStore, ipAddress: ipAddress).toAnyView()
+            default:
+                return ManuallyAddPiHoleView(dataStore: self.dataStore).toAnyView()
+            }
+        default:
+            return ManuallyAddPiHoleView(dataStore: self.dataStore).toAnyView()
+        }
+    }
     
     var body: some View {
-        VStack {
+        statefulContent
-            Text("add_pihole")
-            TextField("ip_address", text: $ipAddress)
-            SecureField("api_key_optional", text: $apiKey)
-            Button(action: { self.dataStore.loadSummary(self.ipAddress, apiKey: self.apiKey) }, label: { Text("connect") })
-        }
-        .padding()
     }
     
     @ObservedObject var dataStore: PiHoleDataStore
@@ -28,6 +33,62 @@ struct AddPiHoleView: View {
     }
 }
 
+struct ManuallyAddPiHoleView: View {
+    @State var ipAddress: String = ""
+    @State var apiKey: String = ""
+    @ObservedObject var dataStore: PiHoleDataStore
+    
+    var body: some View {
+        VStack {
+            Text("add_pihole")
+            TextField("ip_address", text: $ipAddress)
+            SecureField("api_key_optional", text: $apiKey)
+            Button(action: {
+                self.dataStore.baseUrl = self.ipAddress
+                self.dataStore.apiKey = self.apiKey
+                self.dataStore.loadSummary()
+            }, label: { Text("connect") })
+                .padding()
+            ScanButton(dataStore: self.dataStore)
+        }
+        .padding()
+    }
+}
+
+struct ScanButton: View {
+    @ObservedObject var dataStore: PiHoleDataStore
+    
+    var statefulContent: AnyView {
+        if let deviceIpAddress = resolver_get_device_ip() {
+            return Button(action: {
+                self.dataStore.beginScanning(String(cString: deviceIpAddress))
+            }, label: { Text("scan") }).padding().toAnyView()
+        } else {
+            return EmptyView().toAnyView()
+        }
+    }
+    
+    var body: some View { statefulContent }
+}
+
+struct ScanningView: View {
+    let dataStore: PiHoleDataStore
+    let ipAddress: String
+    
+    var body: some View {
+        VStack {
+            ActivityIndicatorView(.constant(true))
+            Text("scanning_ip_address")
+            Text(verbatim: ipAddress)
+            Button(action: {
+                self.dataStore.cancelRequest()
+            }, label: { Text("cancel") }
+            )
+                .padding()
+        }
+    }
+}
+
 struct AddPiHoleView_Previews: PreviewProvider {
     static var previews: some View {
         AddPiHoleView(PiHoleDataStore())

Pi-Helper/ContentView.swift

@@ -16,11 +16,11 @@ struct ContentView: View {
     var stateContent: AnyView {
         switch self.dataStore.pihole {
         case .success(_):
-            return AnyView(PiHoleDetailsView(self.dataStore))
+            return PiHoleDetailsView(self.dataStore).toAnyView()
-        case .failure(.loading):
+        case .failure(.networkError(.loading)):
-            return AnyView(ActivityIndicatorView(.constant(true)))
+            return ActivityIndicatorView(.constant(true)).toAnyView()
         default:
-            return AnyView(AddPiHoleView(self.dataStore))
+            return AddPiHoleView(self.dataStore).toAnyView()
         }
     }
     

Pi-Helper/Extensions.swift

@@ -0,0 +1,16 @@
+//
+//  Extensions.swift
+//  Pi-Helper
+//
+//  Created by Billy Brawner on 11/16/19.
+//  Copyright © 2019 William Brawner. All rights reserved.
+//
+
+import Foundation
+import SwiftUI
+
+extension View {
+    func toAnyView() -> AnyView {
+        return AnyView(self)
+    }
+}

Pi-Helper/Pi-Helper-Bridging-Header.h

@@ -0,0 +1,5 @@
+//
+//  Use this file to import your target's public headers that you would like to expose to Swift.
+//
+
+#include "resolver.h"

Pi-Helper/PiHole.swift

@@ -110,6 +110,10 @@ struct StatusUpdate: Codable {
     let status: String
 }
 
+struct VersionResponse: Codable {
+    let version: Int
+}
+
 enum PiHoleStatus {
     case enabled
     case disabled

Pi-Helper/PiHoleApiService.swift

@@ -20,6 +20,10 @@ class PiHoleApiService {
         self.decoder = decoder
     }
     
+    func getVersion() -> AnyPublisher<VersionResponse, NetworkError> {
+        return get(queries: ["version": nil])
+    }
+    
     func loadSummary() -> AnyPublisher<PiHole, NetworkError> {
         return get()
     }
@@ -68,6 +72,7 @@ class PiHoleApiService {
         var request = URLRequest(url: url)
         request.addValue("application/json", forHTTPHeaderField: "Content-Type")
         request.httpMethod = "GET"
+        request.timeoutInterval = 0.5
         
         let task = URLSession.shared.dataTaskPublisher(for: request)
             .tryMap { (data, res) -> Data in
@@ -91,6 +96,7 @@ class PiHoleApiService {
 
 enum NetworkError: Error {
     case loading
+    case cancelled
     case badRequest
     case notFound
     case unauthorized

Pi-Helper/PiHoleDataStore.swift

@@ -11,22 +11,95 @@ import Combine
 import UIKit
 
 class PiHoleDataStore: ObservableObject {
-    var pihole: Result<PiHole, NetworkError> = .failure(.notFound) {
+    private let IP_MIN = 0
+    private let IP_MAX = 255
+    private var currentRequest: AnyCancellable? = nil
+    @Published var pihole: Result<PiHole, PiHoleError> = .failure(.notConfigured)
+    var apiKey: String? = nil {
         didSet {
-            self.objectWillChange.send()
+            UserDefaults.standard.set(apiKey, forKey: PiHoleDataStore.API_KEY)
+            apiService.apiKey = apiKey
+        }
+    }
+    var baseUrl: String? = nil {
+        didSet {
+            let safeHost = prependScheme(baseUrl)
+            UserDefaults.standard.set(safeHost, forKey: PiHoleDataStore.HOST_KEY)
+            apiService.baseUrl = safeHost
         }
     }
     
-    func loadSummary(_ host: String, apiKey: String? = nil) {
+    private func prependScheme(_ ipAddress: String?) -> String? {
-        self.pihole = .failure(.loading)
+        guard let host = ipAddress else {
-        
+            return nil
-        var safeHost = host
-        if !host.starts(with: "http://") || !host.starts(with: "https://") {
-            safeHost = "http://" + safeHost
         }
-        apiService.baseUrl = safeHost
+        
-        apiService.apiKey = apiKey
+        if !host.starts(with: "http://") && !host.starts(with: "https://") {
-        _ = apiService.loadSummary()
+            return "http://" + host
+        }
+        
+        return host
+    }
+    
+    func beginScanning(_ ipAddress: String) {
+        var addressParts = ipAddress.split(separator: ".")
+        var chunks = 1
+        var ipAddresses = [String]()
+        while chunks <= IP_MAX {
+            let chunkSize = (IP_MAX - IP_MIN + 1) / chunks
+            if chunkSize == 1 {
+                return
+            }
+            for chunk in 0..<chunks {
+                let chunkStart = IP_MIN + (chunk * chunkSize)
+                let chunkEnd = IP_MIN + ((chunk + 1) * chunkSize)
+                addressParts[3] = Substring(String(((chunkEnd - chunkStart) / 2) + chunkStart))
+                ipAddresses.append(addressParts.joined(separator: "."))
+            }
+            chunks *= 2
+        }
+        scan(ipAddresses)
+    }
+    
+    private func scan(_ ipAddresses: [String]) {
+        if ipAddresses.isEmpty {
+            self.pihole = .failure(.notConfigured)
+            return
+        }
+        
+        guard let ipAddress = prependScheme(ipAddresses[0]) else {
+            return
+        }
+        self.apiService.baseUrl = ipAddress
+        self.pihole = .failure(.scanning(ipAddress))
+        print("Scanning \(ipAddress)")
+        currentRequest = self.apiService.getVersion()
+            .receive(on: DispatchQueue.main)
+            .sink(receiveCompletion: { (completion) in
+                switch completion {
+                case .finished:
+                    return
+                case .failure(let error):
+                    // ignore if timeout, otherwise handle
+                    print(error)
+                    self.scan(Array(ipAddresses.dropFirst()))
+                }
+            }, receiveValue: { version in
+                // Stop scans, load summary
+                self.baseUrl = ipAddress
+                self.loadSummary()
+            })
+    }
+    
+    func cancelRequest() {
+        self.currentRequest?.cancel()
+        self.pihole = .failure(.networkError(.cancelled))
+    }
+    
+    func loadSummary() {
+        self.pihole = .failure(.networkError(.loading))
+        
+        currentRequest = apiService.loadSummary()
             .receive(on: DispatchQueue.main)
             .sink(receiveCompletion: { (completion) in
                 switch completion {
@@ -34,11 +107,9 @@ class PiHoleDataStore: ObservableObject {
                     // no-op
                     return
                 case .failure(let error):
-                    self.pihole = .failure(error)
+                    self.pihole = .failure(.networkError(error))
                 }
             }, receiveValue: { pihole in
-                UserDefaults.standard.set(host, forKey: PiHoleDataStore.HOST_KEY)
-                UserDefaults.standard.set(apiKey, forKey: PiHoleDataStore.API_KEY)
                 UIApplication.shared.shortcutItems = [
                     UIApplicationShortcutItem(
                         type: ShortcutAction.enable.rawValue,
@@ -75,8 +146,8 @@ class PiHoleDataStore: ObservableObject {
     
     func enable() {
         let oldPihole = try! pihole.get()
-        self.pihole = .failure(.loading)
+        self.pihole = .failure(.networkError(.loading))
-        _ = self.apiService.enable()
+        currentRequest = self.apiService.enable()
             .receive(on: DispatchQueue.main)
             .sink(receiveCompletion: { (completion) in
                 switch completion {
@@ -84,7 +155,7 @@ class PiHoleDataStore: ObservableObject {
                     // no-op
                     return
                 case .failure(let error):
-                    self.pihole = .failure(error)
+                    self.pihole = .failure(.networkError(error))
                 }
             }, receiveValue: { newStatus in
                 self.pihole = .success(oldPihole.copy(status: newStatus.status))
@@ -93,8 +164,8 @@ class PiHoleDataStore: ObservableObject {
     
     func disable(_ forSeconds: Int? = nil) {
         let oldPihole = try! pihole.get()
-        self.pihole = .failure(.loading)
+        self.pihole = .failure(.networkError(.loading))
-        _ = self.apiService.disable(forSeconds)
+        currentRequest = self.apiService.disable(forSeconds)
             .receive(on: DispatchQueue.main)
             .sink(receiveCompletion: { (completion) in
                 switch completion {
@@ -102,26 +173,25 @@ class PiHoleDataStore: ObservableObject {
                     // no-op
                     return
                 case .failure(let error):
-                    self.pihole = .failure(error)
+                    self.pihole = .failure(.networkError(error))
                 }
             }, receiveValue: { newStatus in
                 self.pihole = .success(oldPihole.copy(status: newStatus.status))
             })
     }
     
-    let objectWillChange = ObservableObjectPublisher()
     let apiService = PiHoleApiService()
     static let HOST_KEY = "host"
     static let API_KEY = "apiKey"
-    init() {
-        if let host = UserDefaults.standard.string(forKey: PiHoleDataStore.HOST_KEY) {
-            let apiKey = UserDefaults.standard.string(forKey: PiHoleDataStore.API_KEY)
-            loadSummary(host, apiKey: apiKey)
-        }
-    }
 }
 
 enum ShortcutAction: String {
     case enable = "EnableAction"
     case disable = "DisableAction"
 }
+
+enum PiHoleError : Error {
+    case networkError(_ error: NetworkError)
+    case scanning(_ ipAddress: String)
+    case notConfigured
+}

Pi-Helper/SceneDelegate.swift

@@ -18,8 +18,20 @@ class SceneDelegate: UIResponder, UIWindowSceneDelegate {
         // Use this method to optionally configure and attach the UIWindow `window` to the provided UIWindowScene `scene`.
         // If using a storyboard, the `window` property will automatically be initialized and attached to the scene.
         // This delegate does not imply the connecting scene or session are new (see `application:configurationForConnectingSceneSession` instead).
-        
         self.dataStore = PiHoleDataStore()
+        if let host = UserDefaults.standard.string(forKey: PiHoleDataStore.HOST_KEY) {
+            // If we already have the address of a Pi we've previously connected to, try that
+            let apiKey = UserDefaults.standard.string(forKey: PiHoleDataStore.API_KEY)
+            self.dataStore!.baseUrl = host
+            self.dataStore!.apiKey = apiKey
+            self.dataStore!.loadSummary()
+        } else if let cString = resolver_get_dns_server_ip() {
+            // Otherwise the Pi is likely the DNS server (though not always true), so we can try connecting to it there
+            let dnsServerIp = String(cString: cString)
+            self.dataStore!.baseUrl = dnsServerIp
+            self.dataStore!.loadSummary()
+        }
+        
         // Create the SwiftUI view that provides the window contents.
         let contentView = ContentView(self.dataStore!)
         

Pi-Helper/en.lproj/Localizable.strings

@@ -9,6 +9,9 @@
 "add_pihole" = "Add the IP address or hostname of your Pi-Hole to be able to view statistics. To enable or disable the Pi-Hole, you'll also need to enter the API key.";
 "ip_address" = "IP Address";
 "api_key_optional" = "API Key (Optional)";
+"scanning_ip_address" = "Scanning the network for your Pi-Hole…";
+"scan" = "Scan";
+"cancel" = "Cancel";
 "connect" = "Connect";
 "status" = "Status";
 "enabled" = "Enabled";

Pi-Helper/es-419.lproj/Localizable.strings

@@ -9,6 +9,9 @@
 "add_pihole" = "Agrega la dirección IP o nombre de host de tu Pi-Hole para poder ver las estadísticas. Para habilitar o deshabilitar el Pi-Hole, también es necesario entregar la clave API.";
 "ip_address" = "Dirección IP";
 "api_key_optional" = "Clave API (Opcional)";
+"scanning_ip_address" = "Escaneando la red para el Pi-Hole…";
+"scan" = "Escanear";
+"cancel" = "Cancelar";
 "connect" = "Conectar";
 "status" = "Estado";
 "enabled" = "Habilitado";

Pi-Helper/resolver.c

@@ -0,0 +1,77 @@
+//
+//  resolver.c
+//  Pi-Helper
+//
+//  Created by Billy Brawner on 11/16/19.
+//  Copyright © 2019 William Brawner. All rights reserved.
+//
+
+#include "resolver.h"
+
+char * resolver_get_dns_server_ip(void) {
+    res_state state = malloc(sizeof(res_state));
+    res_ninit(state);
+    union res_sockaddr_union sockaddr_unions[MAX_SERVERS];
+    int servers_found = res_getservers(state, sockaddr_unions, MAX_SERVERS);
+    res_ndestroy(state);
+    for (int i = 0; i < servers_found; i++) {
+        union res_sockaddr_union sockaddr_union = sockaddr_unions[i];
+        if (sockaddr_union.sin.sin_len < 1) {
+            continue;
+        }
+        char * ipAddress = malloc(NI_MAXHOST + 1);
+        ipAddress[NI_MAXHOST] = '\0';
+        getnameinfo(
+                    &sockaddr_union.sin,
+                    sockaddr_union.sin.sin_len,
+                    ipAddress,
+                    MAX_IP_ADDR_LEN,
+                    NULL,
+                    0,
+                    NI_NUMERICHOST
+                    );
+        return ipAddress;
+    }
+    return NULL;
+}
+
+char * resolver_get_device_ip(void) {
+    struct ifaddrs *ifaddr, *ifa;
+    if (getifaddrs(&ifaddr) == -1) {
+        return NULL;
+    }
+    
+    int n;
+    for (ifa = ifaddr, n = 0; ifa != NULL; ifa = ifa->ifa_next, n++) {
+        if (ifa->ifa_addr == NULL) {
+            continue;
+        }
+        
+        if (ifa->ifa_addr->sa_family != AF_INET) {
+            continue;
+        }
+        
+        if (strcmp("en0", ifa->ifa_name) == 0
+            || strcmp("en1", ifa->ifa_name) == 0
+            || strcmp("en2", ifa->ifa_name) == 0
+            || strcmp("en3", ifa->ifa_name) == 0
+            || strcmp("en4", ifa->ifa_name) == 0) {
+            char *ipAddress = malloc(NI_MAXHOST + 1);
+            ipAddress[NI_NUMERICHOST] = '\0';
+            getnameinfo(
+                        ifa->ifa_addr,
+                        ifa->ifa_addr->sa_len,
+                        ipAddress,
+                        NI_MAXHOST,
+                        NULL,
+                        0,
+                        NI_NUMERICHOST
+                        );
+            freeifaddrs(ifaddr);
+            return ipAddress;
+        }
+    }
+    
+    freeifaddrs(ifaddr);
+    return NULL;
+}

Pi-Helper/resolver.h

@@ -0,0 +1,26 @@
+//
+//  resolver.h
+//  Pi-Helper
+//
+//  Created by Billy Brawner on 11/16/19.
+//  Copyright © 2019 William Brawner. All rights reserved.
+//
+
+#ifndef resolver_h
+#define resolver_h
+
+#include <stdlib.h>
+#include <resolv.h>
+#include <limits.h>
+#include <netdb.h>
+#include <ifaddrs.h>
+#include <string.h>
+
+const int MAX_SERVERS = 10;
+// String length for max IP address length (255.255.255.255)
+const int MAX_IP_ADDR_LEN = 15;
+
+char * resolver_get_dns_server_ip(void);
+char * resolver_get_device_ip(void);
+
+#endif /* resolver_h */