Kit: Adapter: ignore error when updating tunnel settings in offline

Since around iOS 15.1, calling `setNetworkSettings()` when in
airplane mode, throws an unknown error:

Error Domain=NEAgentErrorDomain Code=1

Signed-off-by: Andrej Mihajlov <and@mullvad.net>

Sources/WireGuardKit/IPAddress+AddrInfo.swift

@@ -8,10 +8,7 @@ extension IPv4Address {
     init?(addrInfo: addrinfo) {
         guard addrInfo.ai_family == AF_INET else { return nil }
 
-        let addressData = addrInfo.ai_addr.withMemoryRebound(
+        let addressData = addrInfo.ai_addr.withMemoryRebound(to: sockaddr_in.self, capacity: MemoryLayout<sockaddr_in>.size) { ptr -> Data in
-            to: sockaddr_in.self,
-            capacity: 1
-        ) { ptr -> Data in
             return Data(bytes: &ptr.pointee.sin_addr, count: MemoryLayout<in_addr>.size)
         }
 
@@ -23,10 +20,7 @@ extension IPv6Address {
     init?(addrInfo: addrinfo) {
         guard addrInfo.ai_family == AF_INET6 else { return nil }
 
-        let addressData = addrInfo.ai_addr.withMemoryRebound(
+        let addressData = addrInfo.ai_addr.withMemoryRebound(to: sockaddr_in6.self, capacity: MemoryLayout<sockaddr_in6>.size) { ptr -> Data in
-            to: sockaddr_in6.self,
-            capacity: 1
-        ) { ptr -> Data in
             return Data(bytes: &ptr.pointee.sin6_addr, count: MemoryLayout<in6_addr>.size)
         }
 

Sources/WireGuardKit/WireGuardAdapter.swift

@@ -253,35 +253,58 @@ public class WireGuardAdapter {
                 self.packetTunnelProvider?.reasserting = false
             }
 
+            let settingsGenerator: PacketTunnelSettingsGenerator
             do {
-                let settingsGenerator = try self.makeSettingsGenerator(with: tunnelConfiguration)
+                settingsGenerator = try self.makeSettingsGenerator(with: tunnelConfiguration)
-                try self.setNetworkSettings(settingsGenerator.generateNetworkSettings())
-
-                switch self.state {
-                case .started(let handle, _):
-                    let (wgConfig, resolutionResults) = settingsGenerator.uapiConfiguration()
-                    self.logEndpointResolutionResults(resolutionResults)
-
-                    wgSetConfig(handle, wgConfig)
-                    #if os(iOS)
-                    wgDisableSomeRoamingForBrokenMobileSemantics(handle)
-                    #endif
-
-                    self.state = .started(handle, settingsGenerator)
-
-                case .temporaryShutdown:
-                    self.state = .temporaryShutdown(settingsGenerator)
-
-                case .stopped:
-                    fatalError()
-                }
-
-                completionHandler(nil)
             } catch let error as WireGuardAdapterError {
                 completionHandler(error)
+                return
             } catch {
                 fatalError()
             }
+
+            switch self.state {
+            case .started(let handle, _):
+                do {
+                    try self.setNetworkSettings(settingsGenerator.generateNetworkSettings())
+                } catch let error as WireGuardAdapterError {
+                    completionHandler(error)
+                    return
+                } catch {
+                    fatalError()
+                }
+
+                let (wgConfig, resolutionResults) = settingsGenerator.uapiConfiguration()
+                self.logEndpointResolutionResults(resolutionResults)
+
+                wgSetConfig(handle, wgConfig)
+                #if os(iOS)
+                wgDisableSomeRoamingForBrokenMobileSemantics(handle)
+                #endif
+
+                self.state = .started(handle, settingsGenerator)
+
+            case .temporaryShutdown:
+                // On iOS 15.1 or newer, updating network settings may fail when in airplane mode.
+                // Network path monitor will retry updating settings later when connectivity is
+                // back online.
+                do {
+                    try self.setNetworkSettings(settingsGenerator.generateNetworkSettings())
+                } catch let error as WireGuardAdapterError {
+                    if case .setNetworkSettings(let systemError) = error {
+                        self.logHandler(.verbose, "Failed to set network settings while offline. Will retry when connectivity is back online. Error: \(systemError.localizedDescription)")
+                    }
+                } catch {
+                    fatalError()
+                }
+
+                self.state = .temporaryShutdown(settingsGenerator)
+
+            case .stopped:
+                fatalError()
+            }
+
+            completionHandler(nil)
         }
     }