Model for DNS server

Signed-off-by: Roopesh Chander <roop@roopc.net>

WireGuard/WireGuard.xcodeproj/project.pbxproj

@@ -8,6 +8,7 @@
 
 /* Begin PBXBuildFile section */
 		6F628C3D217F09E9003482A3 /* TunnelViewModel.swift in Sources */ = {isa = PBXBuildFile; fileRef = 6F628C3C217F09E9003482A3 /* TunnelViewModel.swift */; };
+		6F628C3F217F3413003482A3 /* DNSServer.swift in Sources */ = {isa = PBXBuildFile; fileRef = 6F628C3E217F3413003482A3 /* DNSServer.swift */; };
 		6F693A562179E556008551C1 /* Endpoint.swift in Sources */ = {isa = PBXBuildFile; fileRef = 6F693A552179E556008551C1 /* Endpoint.swift */; };
 		6F7774E1217181B1006A79B3 /* MainViewController.swift in Sources */ = {isa = PBXBuildFile; fileRef = 6F7774DF217181B1006A79B3 /* MainViewController.swift */; };
 		6F7774E2217181B1006A79B3 /* AppDelegate.swift in Sources */ = {isa = PBXBuildFile; fileRef = 6F7774E0217181B1006A79B3 /* AppDelegate.swift */; };
@@ -23,6 +24,7 @@
 
 /* Begin PBXFileReference section */
 		6F628C3C217F09E9003482A3 /* TunnelViewModel.swift */ = {isa = PBXFileReference; lastKnownFileType = sourcecode.swift; path = TunnelViewModel.swift; sourceTree = "<group>"; };
+		6F628C3E217F3413003482A3 /* DNSServer.swift */ = {isa = PBXFileReference; lastKnownFileType = sourcecode.swift; path = DNSServer.swift; sourceTree = "<group>"; };
 		6F693A552179E556008551C1 /* Endpoint.swift */ = {isa = PBXFileReference; lastKnownFileType = sourcecode.swift; path = Endpoint.swift; sourceTree = "<group>"; };
 		6F7774DF217181B1006A79B3 /* MainViewController.swift */ = {isa = PBXFileReference; fileEncoding = 4; lastKnownFileType = sourcecode.swift; path = MainViewController.swift; sourceTree = "<group>"; };
 		6F7774E0217181B1006A79B3 /* AppDelegate.swift */ = {isa = PBXFileReference; fileEncoding = 4; lastKnownFileType = sourcecode.swift; path = AppDelegate.swift; sourceTree = "<group>"; };
@@ -78,6 +80,7 @@
 				6F7774E72172020C006A79B3 /* Configuration.swift */,
 				6F7774E9217229DB006A79B3 /* IPAddressRange.swift */,
 				6F693A552179E556008551C1 /* Endpoint.swift */,
+				6F628C3E217F3413003482A3 /* DNSServer.swift */,
 			);
 			path = Model;
 			sourceTree = "<group>";
@@ -209,6 +212,7 @@
 				6F7774EF21722D97006A79B3 /* TunnelsManager.swift in Sources */,
 				6F693A562179E556008551C1 /* Endpoint.swift in Sources */,
 				6F7774E2217181B1006A79B3 /* AppDelegate.swift in Sources */,
+				6F628C3F217F3413003482A3 /* DNSServer.swift in Sources */,
 				6F628C3D217F09E9003482A3 /* TunnelViewModel.swift in Sources */,
 				6F7774EA217229DB006A79B3 /* IPAddressRange.swift in Sources */,
 				6F7774E82172020C006A79B3 /* Configuration.swift in Sources */,

WireGuard/WireGuard/Model/DNSServer.swift

@@ -0,0 +1,62 @@
+//
+//  DNSServer.swift
+//  WireGuard
+//
+//  Created by Roopesh Chander on 23/10/18.
+//  Copyright © 2018 WireGuard LLC. All rights reserved.
+//
+
+import Foundation
+import Network
+
+@available(OSX 10.14, iOS 12.0, *)
+struct DNSServer {
+    let address: IPAddress
+}
+
+// MARK: Converting to and from String
+// For use in the UI
+
+extension DNSServer {
+    init?(from addressString: String) {
+        if let addr = IPv4Address(addressString) {
+            address = addr
+        } else if let addr = IPv6Address(addressString) {
+            address = addr
+        } else {
+            return nil
+        }
+    }
+    func stringRepresentation() -> String {
+        return "\(address)"
+    }
+}
+
+// MARK: Codable
+// For serializing to disk
+
+@available(OSX 10.14, iOS 12.0, *)
+extension DNSServer: Codable {
+    public func encode(to encoder: Encoder) throws {
+        var container = encoder.singleValueContainer()
+        try container.encode(address.rawValue)
+    }
+    public init(from decoder: Decoder) throws {
+        let container = try decoder.singleValueContainer()
+        var data = try container.decode(Data.self)
+        let ipAddressFromData: IPAddress? = {
+            switch (data.count) {
+            case 4: return IPv4Address(data)
+            case 16: return IPv6Address(data)
+            default: return nil
+            }
+        }()
+        guard let ipAddress = ipAddressFromData else {
+            throw DecodingError.invalidData
+        }
+        address = ipAddress
+    }
+    enum DecodingError: Error {
+        case invalidData
+    }
+}