[client] allow -D to be used in --save-rc-stanza mode if -n is not given

This change simplifies the fwknop client usage by allowing the -D argument to
be used as the stanza name if -n is not also specified in --save-rc-stanza
mode.

client/config_init.c

@@ -638,8 +638,7 @@ keys_status(fko_cli_options_t *options)
             {
                 set_rc_file(rcfile, options);
                 log_msg(LOG_VERBOSITY_NORMAL,
-                    "[+] Wrote Rijndael and HMAC keys to rc file: %s",
-                    options->rc_file);
+                    "[+] Wrote Rijndael and HMAC keys to rc file: %s", rcfile);
             }
             else
                 log_msg(LOG_VERBOSITY_NORMAL,
@@ -1571,10 +1570,16 @@ validate_options(fko_cli_options_t *options)
 
     if ( (options->save_rc_stanza == 1)  && (options->use_rc_stanza[0] == 0) )
     {
-        log_msg(LOG_VERBOSITY_ERROR,
-                "The option --save-rc-stanza must be used with the "
-                "--named-config option to specify the stanza to update.");
-        exit(EXIT_FAILURE);
+        /* Set the stanza name to the -D arg value
+        */
+        if (options->spa_server_str[0] == 0x0)
+        {
+            log_msg(LOG_VERBOSITY_ERROR,
+                "Must use --destination unless --test mode is used");
+            exit(EXIT_FAILURE);
+        }
+
+        strlcpy(options->use_rc_stanza, options->spa_server_str, sizeof(options->use_rc_stanza));
     }
 
     /* Gotta have a Destination unless we are just testing or getting the

client/fwknop.8.in

@@ -218,7 +218,11 @@ Specify path to the fwknop rc file (default is $HOME/\&.fwknoprc)\&.
 .RS 4
 Save command line arguments to the $HOME/\&.fwknoprc stanza specified with the
 \fB\-n\fR
-option\&.
+option\&. If the
+\fB\-n\fR
+option is omitted, then the stanza name will default to the destination server value (hostname or IP) given with the
+\fB\-D\fR
+argument\&.
 .RE
 .PP
 \fB\-\-force\-stanza\fR

doc/fwknop.man.asciidoc

@@ -233,7 +233,9 @@ GENERAL OPTIONS
 
 *--save-rc-stanza*='<stanza name>'::
     Save command line arguments to the $HOME/.fwknoprc stanza specified with
-    the *-n* option.
+    the *-n* option.  If the *-n* option is omitted, then the stanza name will
+    default to the destination server value (hostname or IP) given with the
+    *-D* argument.
 
 *--force-stanza*::
     Used with *--save-rc-stanza* to overwrite all of the variables for the