From 9ac315c16bf8441145f5b4b8a3308ae9f03582ab Mon Sep 17 00:00:00 2001

From: Pavel Zhukov <pzhukov@redhat.com>

Date: Wed, 24 Jul 2019 17:15:55 +0200

Subject: [PATCH] Detect system time jumps

In case if system time was changed backward it's possible to have ip

address dropped by the kernel due to lifetime expirity. Try to detect

this situation using either monotonic time or saved timestamp and execute

go_reboot() procedure to request lease extention

---

 lib/isc/include/isc/result.h    |  4 ++--

 lib/isc/include/isc/util.h      |  4 ++++

 lib/isc/result.c                |  2 ++

 lib/isc/unix/app.c              | 41 +++++++++++++++++++++++++++++++--

 lib/isc/unix/include/isc/time.h | 20 ++++++++++++++++

 lib/isc/unix/time.c             | 22 ++++++++++++++++++

 6 files changed, 89 insertions(+), 4 deletions(-)

diff --git a/lib/isc/include/isc/result.h b/lib/isc/include/isc/result.h

index 246aefb..70d4b64 100644

--- a/lib/isc/include/isc/result.h

+++ b/lib/isc/include/isc/result.h

@@ -83,9 +83,9 @@

 #define ISC_R_UNSET			61	/*%< unset */

 #define ISC_R_MULTIPLE			62	/*%< multiple */

 #define ISC_R_WOULDBLOCK		63	/*%< would block */

-

+#define ISC_R_TIMESHIFTED               64      /*%< system time changed */

 /*% Not a result code: the number of results. */

-#define ISC_R_NRESULTS 			64

+#define ISC_R_NRESULTS 			65

 ISC_LANG_BEGINDECLS

diff --git a/lib/isc/include/isc/util.h b/lib/isc/include/isc/util.h

index 332dc0c..f81967d 100644

--- a/lib/isc/include/isc/util.h

+++ b/lib/isc/include/isc/util.h

@@ -233,6 +233,10 @@

  * Time

  */

 #define TIME_NOW(tp) 	RUNTIME_CHECK(isc_time_now((tp)) == ISC_R_SUCCESS)

+#ifdef CLOCK_BOOTTIME

+#define TIME_MONOTONIC(tp) 	RUNTIME_CHECK(isc_time_boottime((tp)) == ISC_R_SUCCESS)

+#endif

+

 /*%

  * Misc

diff --git a/lib/isc/result.c b/lib/isc/result.c

index a707c32..6776fc6 100644

--- a/lib/isc/result.c

+++ b/lib/isc/result.c

@@ -99,6 +99,7 @@ static const char *description[ISC_R_NRESULTS] = {

 	"unset",				/*%< 61 */

 	"multiple",				/*%< 62 */

 	"would block",				/*%< 63 */

+        "time changed",                         /*%< 64 */

 };

 static const char *identifier[ISC_R_NRESULTS] = {

@@ -166,6 +167,7 @@ static const char *identifier[ISC_R_NRESULTS] = {

 	"ISC_R_UNSET",

 	"ISC_R_MULTIPLE",

 	"ISC_R_WOULDBLOCK",

+        "ISC_R_TIMESHIFTED",

 };

 #define ISC_RESULT_RESULTSET			2

diff --git a/lib/isc/unix/app.c b/lib/isc/unix/app.c

index bace2bd..e9814d2 100644

--- a/lib/isc/unix/app.c

+++ b/lib/isc/unix/app.c

@@ -441,15 +441,51 @@ isc__app_ctxonrun(isc_appctx_t *ctx0, isc_mem_t *mctx, isc_task_t *task,

 static isc_result_t

 evloop(isc__appctx_t *ctx) {

 	isc_result_t result;

+        isc_time_t now;

+#ifdef CLOCK_BOOTTIME

+        isc_time_t monotonic;

+        isc_uint64_t diff  = 0;

+#else

+        isc_time_t prev;

+        TIME_NOW(&prev;;

+#endif

+

+

+

 	while (!ctx->want_shutdown) {

 		int n;

-		isc_time_t when, now;

+		isc_time_t when;

+                

 		struct timeval tv, *tvp;

 		isc_socketwait_t *swait;

 		isc_boolean_t readytasks;

 		isc_boolean_t call_timer_dispatch = ISC_FALSE;

+                isc_uint64_t us; 

+

+#ifdef CLOCK_BOOTTIME

+                // TBD macros for following three lines

+                TIME_NOW(&now;;

+                TIME_MONOTONIC(&monotonic);

+                INSIST(now.seconds > monotonic.seconds)

+                us = isc_time_microdiff (&now, &monotonic);

+                if (us < diff){ 

+                  us = diff - us;

+                  if (us > 1000000){ // ignoring shifts less than one second

+                    return ISC_R_TIMESHIFTED;

+                  };

+                  diff = isc_time_microdiff (&now, &monotonic);

+                } else {

+                  diff = isc_time_microdiff (&now, &monotonic);

+                  // not implemented

+                }

+#else

+                TIME_NOW(&now;;

+                if (isc_time_compare (&now, &prev) < 0)

+                  return ISC_R_TIMESHIFTED;

+                TIME_NOW(&prev;;

+#endif                

 		/*

 		 * Check the reload (or suspend) case first for exiting the

 		 * loop as fast as possible in case:

@@ -474,9 +510,10 @@ evloop(isc__appctx_t *ctx) {

 			if (result != ISC_R_SUCCESS)

 				tvp = NULL;

 			else {

-				isc_uint64_t us;

+

 				TIME_NOW(&now;;

+

 				us = isc_time_microdiff(&when, &now;;

 				if (us == 0)

 					call_timer_dispatch = ISC_TRUE;

diff --git a/lib/isc/unix/include/isc/time.h b/lib/isc/unix/include/isc/time.h

index 75e24b9..de8b399 100644

--- a/lib/isc/unix/include/isc/time.h

+++ b/lib/isc/unix/include/isc/time.h

@@ -129,6 +129,26 @@ isc_time_isepoch(const isc_time_t *t);

  *\li	't' is a valid pointer.

  */

+#ifdef CLOCK_BOOTTIME

+isc_result_t

+isc_time_boottime(isc_time_t *t);

+/*%<

+ * Set 't' to monotonic time from previous boot

+ * it's not affected by system time change. It also

+ * includes the time system was suspended

+ *

+ * Requires:

+ *\li	't' is a valid pointer.

+ *

+ * Returns:

+ *

+ *\li	Success

+ *\li	Unexpected error

+ *		Getting the time from the system failed.

+ */

+#endif /* CLOCK_BOOTTIME */

+ 

+

 isc_result_t

 isc_time_now(isc_time_t *t);

 /*%<

diff --git a/lib/isc/unix/time.c b/lib/isc/unix/time.c

index 2210240..d7613b8 100644

--- a/lib/isc/unix/time.c

+++ b/lib/isc/unix/time.c

@@ -496,3 +496,25 @@ isc_time_formatISO8601ms(const isc_time_t *t, char *buf, unsigned int len) {

 			 t->nanoseconds / NS_PER_MS);

 	}

 }

+

+

+#ifdef CLOCK_BOOTTIME

+isc_result_t

+isc_time_boottime(isc_time_t *t) {

+  struct timespec ts;

+  

+  char strbuf[ISC_STRERRORSIZE];

+

+  if (clock_gettime (CLOCK_BOOTTIME, &ts) != 0){

+    isc__strerror(errno, strbuf, sizeof(strbuf));

+    UNEXPECTED_ERROR(__FILE__, __LINE__, "%s", strbuf);

+    return (ISC_R_UNEXPECTED);    

+  }

+

+  t->seconds = ts.tv_sec;

+  t->nanoseconds = ts.tv_nsec;

+

+  return (ISC_R_SUCCESS);

+  

+};

+#endif

-- 

2.20.1