Issue #12: Use proper DNS library instead of handcrafted DNS query to fetch statistics.

dns.xcodeproj/project.pbxproj

@@ -7,6 +7,7 @@
 	objects = {
 
 /* Begin PBXBuildFile section */
+		A051B5122FC9E0D700EACDC0 /* AsyncDNSResolver in Frameworks */ = {isa = PBXBuildFile; productRef = A051B5112FC9E0D700EACDC0 /* AsyncDNSResolver */; };
 		A08264132FC718790077B227 /* Stickers.appex in Embed Foundation Extensions */ = {isa = PBXBuildFile; fileRef = A082640C2FC718790077B227 /* Stickers.appex */; settings = {ATTRIBUTES = (RemoveHeadersOnCopy, ); }; };
 /* End PBXBuildFile section */
 
@@ -74,6 +75,7 @@
 			isa = PBXFrameworksBuildPhase;
 			buildActionMask = 2147483647;
 			files = (
+				A051B5122FC9E0D700EACDC0 /* AsyncDNSResolver in Frameworks */,
 			);
 			runOnlyForDeploymentPostprocessing = 0;
 		};
@@ -125,6 +127,7 @@
 			);
 			name = dns;
 			packageProductDependencies = (
+				A051B5112FC9E0D700EACDC0 /* AsyncDNSResolver */,
 			);
 			productName = dns;
 			productReference = 069DCCFA2F8C0DCE00F1EB16 /* dns.app */;
@@ -178,6 +181,9 @@
 			);
 			mainGroup = 069DCCF12F8C0DCD00F1EB16;
 			minimizedProjectReferenceProxies = 1;
+			packageReferences = (
+				A051B5102FC9E0D700EACDC0 /* XCRemoteSwiftPackageReference "swift-async-dns-resolver" */,
+			);
 			preferredProjectObjectVersion = 77;
 			productRefGroup = 069DCCFB2F8C0DCE00F1EB16 /* Products */;
 			projectDirPath = "";
@@ -529,6 +535,25 @@
 			defaultConfigurationName = Release;
 		};
 /* End XCConfigurationList section */
+
+/* Begin XCRemoteSwiftPackageReference section */
+		A051B5102FC9E0D700EACDC0 /* XCRemoteSwiftPackageReference "swift-async-dns-resolver" */ = {
+			isa = XCRemoteSwiftPackageReference;
+			repositoryURL = "https://github.com/apple/swift-async-dns-resolver/";
+			requirement = {
+				kind = upToNextMajorVersion;
+				minimumVersion = 0.7.0;
+			};
+		};
+/* End XCRemoteSwiftPackageReference section */
+
+/* Begin XCSwiftPackageProductDependency section */
+		A051B5112FC9E0D700EACDC0 /* AsyncDNSResolver */ = {
+			isa = XCSwiftPackageProductDependency;
+			package = A051B5102FC9E0D700EACDC0 /* XCRemoteSwiftPackageReference "swift-async-dns-resolver" */;
+			productName = AsyncDNSResolver;
+		};
+/* End XCSwiftPackageProductDependency section */
 	};
 	rootObject = 069DCCF22F8C0DCD00F1EB16 /* Project object */;
 }

dns.xcodeproj/project.xcworkspace/xcshareddata/swiftpm/Package.resolved

@@ -0,0 +1,15 @@
+{
+  "originHash" : "8d197ac71cfa33d9e3396085f37fbee66795a894a6d74e24ff28bd887e01b9f2",
+  "pins" : [
+    {
+      "identity" : "swift-async-dns-resolver",
+      "kind" : "remoteSourceControl",
+      "location" : "https://github.com/apple/swift-async-dns-resolver/",
+      "state" : {
+        "revision" : "9900d9b4113427a170d5f26075c2128be94984df",
+        "version" : "0.7.0"
+      }
+    }
+  ],
+  "version" : 3
+}

dns/BlockedCount.swift

@@ -1,9 +1,13 @@
 
 import SwiftUI
 import Foundation
+import AsyncDNSResolver
 
 struct BlockedCount: View {
 
+    @Environment(\.scenePhase)
+    private var scenePhase
+
     @EnvironmentObject
     private var viewModel: ViewModel
 
@@ -21,46 +25,32 @@ struct BlockedCount: View {
     var body: some View {
         Text(txtRecord)
         .onAppear {
-            fetchTXTRecord()
+            fetchTxtRecord()
         }
         .onChange(of: viewModel.blocklist) { _ in
-            fetchTXTRecord()
+            fetchTxtRecord()
+        }
+        .onChange(of: scenePhase) { newPhase in
+            if newPhase == .active {
+                fetchTxtRecord()
+            }
         }
     }
 
-    func parseResponse(data: Data) -> String? {
-        // This is a DNS wire format response and we make a lot of assumptions
-        // It is not critical functionality so just let it fail if it fails
-
-        guard data.count > Self.startIndex else {
-            return nil
-        }
-
-        // Find the first space character (ASCII 32).
-        guard let endIndex = data.suffix(from: Self.startIndex).firstIndex(of: 32) else {
-            return nil
-        }
-
-        guard let numberString = String(data: data[Self.startIndex ..< endIndex], encoding: .utf8)
-        else {
-            return nil
-        }
-
-        return Self.formatter.string(for: Int(numberString))
-    }
-    
-    func fetchTXTRecord() {
-        let dohURL = URL(string: "https://\(viewModel.blocklist.server)/dns-query?dns=DoQBAAABAAAAAAAABXN0YXRzB2ludmFsaWQAABAAAQ")!
-        let request = URLRequest(url: dohURL)
-
-        txtRecord = "…"
-
+    private func fetchTxtRecord() {
         Task {
             do {
-                let (data, _) = try await URLSession.shared.data(for: request)
+                let resolver = try AsyncDNSResolver()
 
-                if let count = parseResponse(data: data) {
-                    txtRecord = count
+                let records = try await resolver.queryTXT(name: "stats.invalid")
+
+                let text = records.map { $0.txt }.joined()
+
+                if let number = text.split(separator: " ").first,
+                   let intValue = Int(number),
+                   let formatted = Self.formatter.string(for: intValue)
+                {
+                    txtRecord = formatted
                 }
                 else {
                     txtRecord = NSLocalizedString("Error", comment: "")