Merge pull request #2115 from Firstyear/20250327-use-flags-fping

Improve handling of -4/-6
This changes the handling of `-4`/`-6` flags for check_fping to make it more explicit which IP stack is used in which case.
Additionally, the deprecated `fping6` command is removed wholesale and the explicit `-4`/`-6` flags are used instead.

2 files changed, 18 insertions, 22 deletions

diff --git a/configure.ac b/configure.ac
index fdc9b699..bd3de196 100644
--- a/configure.ac
+++ b/configure.ac
@@ -1524,17 +1524,10 @@ AC_PATH_PROG(PATH_TO_FPING6,fping6)
 AC_ARG_WITH(fping_command,
             ACX_HELP_STRING([--with-fping-command=PATH],
                             [Path to fping command]), PATH_TO_FPING=$withval)
-AC_ARG_WITH(fping6_command,
-            ACX_HELP_STRING([--with-fping6-command=PATH],
-                            [Path to fping6 command]), PATH_TO_FPING6=$withval)
-
 if test -n "$PATH_TO_FPING"
 then
         AC_DEFINE_UNQUOTED(PATH_TO_FPING,"$PATH_TO_FPING",[path to fping])
         EXTRAS="$EXTRAS check_fping\$(EXEEXT)"
-        if test x"$with_ipv6" != xno && test -n "$PATH_TO_FPING6"; then
-                AC_DEFINE_UNQUOTED(PATH_TO_FPING6,"$PATH_TO_FPING6",[path to fping6])
-        fi
 else
         AC_MSG_WARN([Get fping from http://www.fping.com in order to make check_fping plugin])
 fi
diff --git a/plugins/check_fping.c b/plugins/check_fping.c
index ec7abb67..e05056b2 100644
--- a/plugins/check_fping.c
+++ b/plugins/check_fping.c
@@ -79,6 +79,24 @@ int main(int argc, char **argv) {
         server = strscpy(server, config.server_name);
 
         char *option_string = "";
+        char *fping_prog = NULL;
+
+        /* First determine if the target is dualstack or ipv6 only. */
+        bool server_is_inet6_addr = is_inet6_addr(server);
+
+        /*
+         * If the user requested -6 OR the user made no assertion and the address is v6 or dualstack
+         *   -> we use ipv6
+         * If the user requested -4 OR the user made no assertion and the address is v4 ONLY
+         *   -> we use ipv4
+         */
+        if (address_family == AF_INET6 || (address_family == AF_UNSPEC && server_is_inet6_addr)) {
+                xasprintf(&option_string, "%s-6 ", option_string);
+        } else {
+                xasprintf(&option_string, "%s-4 ", option_string);
+        }
+        fping_prog = strdup(PATH_TO_FPING);
+
         /* compose the command */
         if (config.target_timeout) {
                 xasprintf(&option_string, "%s-t %d ", option_string, config.target_timeout);
@@ -99,17 +117,6 @@ int main(int argc, char **argv) {
                 xasprintf(&option_string, "%s-R ", option_string);
         }
 
-        char *fping_prog = NULL;
-#ifdef PATH_TO_FPING6
-        if (address_family != AF_INET && is_inet6_addr(server)) {
-                fping_prog = strdup(PATH_TO_FPING6);
-        } else {
-                fping_prog = strdup(PATH_TO_FPING);
-        }
-#else
-        fping_prog = strdup(PATH_TO_FPING);
-#endif
-
         char *command_line = NULL;
         xasprintf(&command_line, "%s %s-b %d -c %d %s", fping_prog, option_string, config.packet_size, config.packet_count, server);
 
@@ -340,11 +347,7 @@ check_fping_config_wrapper process_arguments(int argc, char **argv) {
                         address_family = AF_INET;
                         break;
                 case '6': /* IPv6 only */
-#ifdef USE_IPV6
                         address_family = AF_INET6;
-#else
-                        usage(_("IPv6 support not available\n"));
-#endif
                         break;
                 case 'c':
                         get_threshold(optarg, rv);