remote(server): fix crash when invalid port is specified

Fixes #6584

Author: osy

Platform/macOS/SettingsView.swift

@@ -223,9 +223,12 @@ struct ServerSettingsView: View {
                     .multilineTextAlignment(.trailing)
                     .help("Specify a port number to listen on. This is required if external clients are permitted.")
                     .onChange(of: serverPort) { newValue in
-                        if serverPort == 0 {
+                        if newValue == 0 {
                             isServerExternal = false
                         }
+                        if newValue < 0 || newValue >= UInt16.max {
+                            serverPort = defaultPort
+                        }
                     }
             }
             Section(header: Text("Authentication")) {

Remote/UTMRemoteServer.swift

@@ -131,7 +131,7 @@ actor UTMRemoteServer {
             registerNotifications()
             listener = Task {
                 await withErrorNotification {
-                    if isServerExternal && serverPort > 0 {
+                    if isServerExternal && serverPort > 0 && serverPort <= UInt16.max {
                         natPort = Port.TCP(internalPort: UInt16(serverPort))
                         natPort!.mappingChangedHandler = { port in
                             Task {
@@ -146,7 +146,7 @@ actor UTMRemoteServer {
                             }
                         }
                     }
-                    let port = serverPort > 0 ? NWEndpoint.Port(integerLiteral: UInt16(serverPort)) : .any
+                    let port = serverPort > 0 && serverPort <= UInt16.max ? NWEndpoint.Port(integerLiteral: UInt16(serverPort)) : .any
                     for try await connection in Connection.advertise(on: port, forServiceType: service, txtRecord: metadata, connectionQueue: connectionQueue, identity: keyManager.identity) {
                         let connection = try? await Connection(connection: connection, connectionQueue: connectionQueue) { connection, error in
                             Task {