Check ntp time delay (#2277)HEADmaster

* check_ntp_time: add polling delay

NTP server can have rate limiting which might be triggered by
check_ntp_time due to many requests in a short time span.

This patch adds a default delay (of 0.5s) between requests to each server
and a command line option (--poll-delay) to make this delay
configurable.

Co-authored-by: Lorenz Kästle <lorenz@vulgrim.de>

* check_ntp_time: verify whether socket path fits into address struct

check_ntp_time could be give a too long (>108 bytes) socket path
to work with, which would potentially crash the program.
This patch validates to length beforehand and stops execution
in that case.

Co-authored-by: Lorenz Kästle <lorenz@vulgrim.de>

---------

Co-authored-by: Paul Crawford <paul@crawford-space.co.uk>
Co-authored-by: Lorenz Kästle <lorenz@vulgrim.de>

2 files changed, 10 insertions, 1 deletions

diff --git a/plugins/check_ntp_time.c b/plugins/check_ntp_time.c
index 3e23d0bf..2d9a6f40 100644
--- a/plugins/check_ntp_time.c
+++ b/plugins/check_ntp_time.c
@@ -43,6 +43,7 @@
 #include "thresholds.h"
 #include "check_ntp_time.d/config.h"
 #include <netinet/in.h>
+#include <string.h>
 #include <sys/socket.h>
 
 static int verbose = 0;
@@ -395,7 +396,10 @@ static offset_request_wrapper offset_request(const char *host, const char *port,
                         .sun_family = AF_UNIX,
                 };
 
-                strncpy(unix_socket.sun_path, host, strlen(host));
+                if (strlen(host) > sizeof(unix_socket.sun_path)) {
+                        die(STATE_UNKNOWN, "host argument is too long (%lu) for a socket path\n", strlen(host));
+                }
+                strncpy(unix_socket.sun_path, host, sizeof(unix_socket.sun_path));
 
                 if (connect(socklist[0], &unix_socket, sizeof(unix_socket))) {
                         /* don't die here, because it is enough if there is one server
diff --git a/plugins/check_ntp_time.d/config.h b/plugins/check_ntp_time.d/config.h
index 9bbd82aa..c1aa142c 100644
--- a/plugins/check_ntp_time.d/config.h
+++ b/plugins/check_ntp_time.d/config.h
@@ -5,6 +5,9 @@
 #include "thresholds.h"
 #include <stddef.h>
 
+/* Time in microseconds to delay between polling to avoid a blocking response. */
+const long default_polling_delay = 500000L;
+
 typedef struct {
         char *server_address;
         char *port;
@@ -15,6 +18,7 @@ typedef struct {
         mp_thresholds offset_thresholds;
 
         bool output_format_is_set;
+        long poll_delay;
         mp_output_format output_format;
 } check_ntp_time_config;
 
@@ -29,6 +33,7 @@ check_ntp_time_config check_ntp_time_config_init() {
                 .offset_thresholds = mp_thresholds_init(),
 
                 .output_format_is_set = false,
+                .poll_delay = default_polling_delay,
         };
 
         mp_range warning = mp_range_init();