fix(client): prefer CLI arguments to config, following OpenSSH behavi…

…our (#45)

The client prefered using values from the config file. The expected
behaviour is to prefer vales from the CLI and fill the missing ones with
defaults in the configuration files.
This commit fixes 35 by prefering CLI over config.

fix: 35

cli/client/main.go

@@ -400,9 +400,6 @@ func mainWithStatusCode() int {
 	}
 
 	urlHostname, urlPort := parsedUrl.Hostname(), parsedUrl.Port()
-	if urlPort == "" {
-		urlPort = "443"
-	}
 
 	configHostname, configPort, configUser, configAuthMethods, err := ssh3.GetConfigForHost(urlHostname, sshConfig)
 	if err != nil {
@@ -417,13 +414,25 @@ func mainWithStatusCode() int {
 
 	hostnameIsAnIP := net.ParseIP(hostname) != nil
 
-	port := configPort
-	if port == -1 && urlPort != "" {
-		port, err = strconv.Atoi(urlPort)
-		if err != nil {
-			log.Error().Msgf("invalid port number: %s: %s", urlPort, err)
+	var port int
+	if urlPort != "" {
+		if parsedPort, err := strconv.Atoi(urlPort); err == nil && parsedPort < 0xffff {
+			// There is a port in the CLI and the port is valid. Use the CLI port.
+			port = parsedPort
+		} else {
+			// There is a port in the CLI but it is not valid.
+			// use WithLevel(zerolog.FatalLevel) to log a fatal level, but let us handle
+			// program termination. log.Fatal() exits with os.Exit(1).
+			log.WithLevel(zerolog.FatalLevel).Str("Port", urlPort).Err(err).Msg("cli contains an invalid port")
+			fmt.Fprintf(os.Stderr, "Bad port '%s'\n", urlPort)
 			return -1
 		}
+	} else if configPort != -1 {
+		// There is no port in the CLI, but one in a config file. Use the config port.
+		port = configPort
+	} else {
+		// There is no port specified, neither in the CLI, nor in the configuration.
+		port = 443
 	}
 
 	username := parsedUrl.User.Username()