[monitoring-plugins] Harden check with unspec

[William]

 Module: monitoring-plugins
 Branch: master
 Commit: a1472be88322140cf1f2fc39b9e1b654a86f8155
 Author: William <william at blackhats.net.au>
   Date: Fri Mar 28 12:40:35 2025 +1000
    URL: https://www.monitoring-plugins.org/repositories/monitoring-plugins/commit/?id=a1472be8

Harden check with unspec

---

 plugins/check_fping.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/plugins/check_fping.c b/plugins/check_fping.c
index 1c2b7689..cf9c2d1c 100644
--- a/plugins/check_fping.c
+++ b/plugins/check_fping.c
@@ -83,14 +83,14 @@ int main(int argc, char **argv) {
 
 	/* compose the command */
 #ifdef PATH_TO_FPING6
-	if (address_family != AF_INET && is_inet6_addr(server)) {
+	if (address_family == AF_INET6 || (address_family == AF_UNSPEC && is_inet6_addr(server))) {
 		fping_prog = strdup(PATH_TO_FPING6);
 	} else {
 		xasprintf(&option_string, "%s-4 ", option_string);
 		fping_prog = strdup(PATH_TO_FPING);
 	}
 #else
-	if (address_family != AF_INET) {
+	if (address_family == AF_INET6 || (address_family == AF_UNSPEC && is_inet6_addr(server))) {
 		// -4 / -6 must be set explicitly as when a host has dual stack
 		// if we don't specify -4 then fping selects ipv6 which can mess
 		// with some checks.