From 968ad6b5039d839bfbc61da755c252cc7598415b Mon Sep 17 00:00:00 2001

From: progier389 <progier@redhat.com>

Date: Mon, 25 Oct 2021 17:09:57 +0200

Subject: [PATCH 02/12] Issue 4943 - Fix csn generator to limit time skew drift

 - PR 4946

---

 ldap/servers/slapd/csngen.c       | 433 +++++++++++++++++-------------

 ldap/servers/slapd/slapi-plugin.h |   9 +

 2 files changed, 255 insertions(+), 187 deletions(-)

diff --git a/ldap/servers/slapd/csngen.c b/ldap/servers/slapd/csngen.c

index fcd88b4cc..c7c5c2ba8 100644

--- a/ldap/servers/slapd/csngen.c

+++ b/ldap/servers/slapd/csngen.c

@@ -18,8 +18,9 @@

 #include "prcountr.h"

 #include "slap.h"

+

 #define CSN_MAX_SEQNUM 0xffff              /* largest sequence number */

-#define CSN_MAX_TIME_ADJUST 24 * 60 * 60   /* maximum allowed time adjustment (in seconds) = 1 day */

+#define CSN_MAX_TIME_ADJUST _SEC_PER_DAY   /* maximum allowed time adjustment (in seconds) = 1 day */

 #define ATTR_CSN_GENERATOR_STATE "nsState" /* attribute that stores csn state information */

 #define STATE_FORMAT "%8x%8x%8x%4hx%4hx"

 #define STATE_LENGTH 32

@@ -27,6 +28,8 @@

 #define CSN_CALC_TSTAMP(gen) ((gen)->state.sampled_time + \

                               (gen)->state.local_offset + \

                               (gen)->state.remote_offset)

+#define TIME_DIFF_WARNING_DELAY  (30*_SEC_PER_DAY)  /* log an info message when difference

+                                                       between clock is greater than this delay */

 /*

  * **************************************************************************

@@ -63,6 +66,7 @@ typedef struct csngen_state

 struct csngen

 {

     csngen_state state;      /* persistent state of the generator */

+    int32_t (*gettime)(struct timespec *tp); /* Get local time */

     callback_list callbacks; /* list of callbacks registered with the generator */

     Slapi_RWLock *lock;      /* concurrency control */

 };

@@ -78,7 +82,7 @@ static int _csngen_init_callbacks(CSNGen *gen);

 static void _csngen_call_callbacks(const CSNGen *gen, const CSN *csn, PRBool abort);

 static int _csngen_cmp_callbacks(const void *el1, const void *el2);

 static void _csngen_free_callbacks(CSNGen *gen);

-static int _csngen_adjust_local_time(CSNGen *gen, time_t cur_time);

+static int _csngen_adjust_local_time(CSNGen *gen);

 /*

  * **************************************************************************

@@ -121,6 +125,7 @@ csngen_new(ReplicaId rid, Slapi_Attr *state)

     _csngen_init_callbacks(gen);

     gen->state.rid = rid;

+    gen->gettime = slapi_clock_utc_gettime;

     if (state) {

         rc = _csngen_parse_state(gen, state);

@@ -164,10 +169,7 @@ csngen_free(CSNGen **gen)

 int

 csngen_new_csn(CSNGen *gen, CSN **csn, PRBool notify)

 {

-    struct timespec now = {0};

     int rc = CSN_SUCCESS;

-    time_t cur_time;

-    int delta;

     if (gen == NULL || csn == NULL) {

         slapi_log_err(SLAPI_LOG_ERR, "csngen_new_csn", "Invalid argument\n");

@@ -180,39 +182,13 @@ csngen_new_csn(CSNGen *gen, CSN **csn, PRBool notify)

         return CSN_MEMORY_ERROR;

     }

-    if ((rc = slapi_clock_gettime(&now)) != 0) {

-        /* Failed to get system time, we must abort */

-        slapi_log_err(SLAPI_LOG_ERR, "csngen_new_csn",

-                "Failed to get system time (%s)\n",

-                slapd_system_strerror(rc));

-        return CSN_TIME_ERROR;

-    }

-    cur_time = now.tv_sec;

-

     slapi_rwlock_wrlock(gen->lock);

-    /* check if the time should be adjusted */

-    delta = cur_time - gen->state.sampled_time;

-    if (delta > _SEC_PER_DAY || delta < (-1 * _SEC_PER_DAY)) {

-        /* We had a jump larger than a day */

-        slapi_log_err(SLAPI_LOG_INFO, "csngen_new_csn",

-                "Detected large jump in CSN time.  Delta: %d (current time: %ld  vs  previous time: %ld)\n",

-                delta, cur_time, gen->state.sampled_time);

-    }

-    if (delta > 0) {

-        rc = _csngen_adjust_local_time(gen, cur_time);

-        if (rc != CSN_SUCCESS) {

-            slapi_rwlock_unlock(gen->lock);

-            return rc;

-        }

+    rc = _csngen_adjust_local_time(gen);

+    if (rc != CSN_SUCCESS) {

+        slapi_rwlock_unlock(gen->lock);

+        return rc;

     }

-    /* if (delta < 0) this means the local system time was set back

-     * the new csn will be generated based on sampled time, which is

-     * ahead of system time and previously generated csns.

-     * the time stamp of the csn will not change until system time

-     * catches up or is corrected by remote csns.

-     * But we need to ensure that the seq_num does not overflow.

-     */

     if (gen->state.seq_num == CSN_MAX_SEQNUM) {

         slapi_log_err(SLAPI_LOG_INFO, "csngen_new_csn", "Sequence rollover; "

@@ -261,13 +237,36 @@ csngen_rewrite_rid(CSNGen *gen, ReplicaId rid)

 }

 /* this function should be called when a remote CSN for the same part of

-   the dit becomes known to the server (for instance, as part of RUV during

-   replication session. In response, the generator would adjust its notion

-   of time so that it does not generate smaller csns */

+ * the dit becomes known to the server (for instance, as part of RUV during

+ * replication session. In response, the generator would adjust its notion

+ * of time so that it does not generate smaller csns

+ *

+ * The following counters are updated

+ *   - when a new csn is generated

+ *   - when csngen is adjusted (beginning of a incoming (extop) or outgoing

+ *     (inc_protocol) session)

+ *

+ * sampled_time: It takes the value of current system time.

+ *

+ * remote offset: it is updated when 'csn' argument is ahead of the next csn

+ * that the csn generator will generate. It is the MAX jump ahead, it is not

+ * cumulative counter (e.g. if remote_offset=7 and 'csn' is 5sec ahead

+ * remote_offset stays the same. The jump ahead (5s) pour into the local offset.

+ * It is not clear of the interest of this counter. It gives an indication of

+ * the maximum jump ahead but not much.

+ *

+ * local offset: it is increased if

+ *   - system time is going backward (compare sampled_time)

+ *   - if 'csn' argument is ahead of csn that the csn generator would generate

+ *     AND diff('csn', csngen.new_csn) < remote_offset

+ *     then the diff "pour" into local_offset

+ *  It is decreased as the clock is ticking, local offset is "consumed" as

+ *  sampled_time progresses.

+ */

 int

 csngen_adjust_time(CSNGen *gen, const CSN *csn)

 {

-    time_t remote_time, remote_offset, cur_time;

+    time_t remote_time, remote_offset, cur_time, old_time, new_time;

     PRUint16 remote_seqnum;

     int rc;

     extern int config_get_ignore_time_skew(void);

@@ -281,6 +280,11 @@ csngen_adjust_time(CSNGen *gen, const CSN *csn)

     slapi_rwlock_wrlock(gen->lock);

+    /* Get last local csn time */

+    old_time = CSN_CALC_TSTAMP(gen);

+    /* update local offset and sample_time */

+    rc = _csngen_adjust_local_time(gen);

+

     if (slapi_is_loglevel_set(SLAPI_LOG_REPL)) {

         cur_time = CSN_CALC_TSTAMP(gen);

         slapi_log_err(SLAPI_LOG_REPL, "csngen_adjust_time",

@@ -290,79 +294,60 @@ csngen_adjust_time(CSNGen *gen, const CSN *csn)

                       gen->state.local_offset,

                       gen->state.remote_offset);

     }

-    /* make sure we have the current time */

-    cur_time = slapi_current_utc_time();

-

-    /* make sure sampled_time is current */

-    /* must only call adjust_local_time if the current time is greater than

-       the generator state time */

-    if ((cur_time > gen->state.sampled_time) &&

-        (CSN_SUCCESS != (rc = _csngen_adjust_local_time(gen, cur_time)))) {

+    if (rc != CSN_SUCCESS) {

         /* _csngen_adjust_local_time will log error */

         slapi_rwlock_unlock(gen->lock);

-        csngen_dump_state(gen);

+        csngen_dump_state(gen, SLAPI_LOG_DEBUG);

         return rc;

     }

-    cur_time = CSN_CALC_TSTAMP(gen);

-    if (remote_time >= cur_time) {

-        time_t new_time = 0;

-

-        if (remote_seqnum > gen->state.seq_num) {

-            if (remote_seqnum < CSN_MAX_SEQNUM) {

-                gen->state.seq_num = remote_seqnum + 1;

-            } else {

-                remote_time++;

-            }

-        }

-

-        remote_offset = remote_time - cur_time;

-        if (remote_offset > gen->state.remote_offset) {

-            if (ignore_time_skew || (remote_offset <= CSN_MAX_TIME_ADJUST)) {

-                gen->state.remote_offset = remote_offset;

-            } else /* remote_offset > CSN_MAX_TIME_ADJUST */

-            {

-                slapi_log_err(SLAPI_LOG_ERR, "csngen_adjust_time",

-                              "Adjustment limit exceeded; value - %ld, limit - %ld\n",

-                              remote_offset, (long)CSN_MAX_TIME_ADJUST);

-                slapi_rwlock_unlock(gen->lock);

-                csngen_dump_state(gen);

-                return CSN_LIMIT_EXCEEDED;

-            }

-        } else if (remote_offset > 0) { /* still need to account for this */

-            gen->state.local_offset += remote_offset;

+    remote_offset = remote_time - CSN_CALC_TSTAMP(gen);

+    if (remote_offset > 0) {

+        if (!ignore_time_skew && (gen->state.remote_offset + remote_offset > CSN_MAX_TIME_ADJUST)) {

+            slapi_log_err(SLAPI_LOG_ERR, "csngen_adjust_time",

+                          "Adjustment limit exceeded; value - %ld, limit - %ld\n",

+                          remote_offset, (long)CSN_MAX_TIME_ADJUST);

+            slapi_rwlock_unlock(gen->lock);

+            csngen_dump_state(gen, SLAPI_LOG_DEBUG);

+            return CSN_LIMIT_EXCEEDED;

         }

-

-        new_time = CSN_CALC_TSTAMP(gen);

-        /* let's revisit the seq num - if the new time is > the old

-           tiem, we should reset the seq number to remote + 1 if

-           this won't cause a wrap around */

-        if (new_time >= cur_time) {

-            /* just set seq_num regardless of whether the current one

-               is < or > than the remote one - the goal of this function

-               is to make sure we generate CSNs > the remote CSN - if

-               we have increased the time, we can decrease the seqnum

-               and still guarantee that any new CSNs generated will be

-               > any current CSNs we have generated */

-            if (remote_seqnum < gen->state.seq_num) {

-                gen->state.seq_num ++;

-            } else {

-                gen->state.seq_num = remote_seqnum + 1;

-            }

+        gen->state.remote_offset += remote_offset;

+        /* To avoid beat phenomena between suppliers let put 1 second in local_offset

+         * it will be eaten at next clock tick rather than increasing remote offset

+         * If we do not do that we will have a time skew drift of 1 second per 2 seconds

+         * if suppliers are desynchronized by 0.5 second 

+         */

+        if (gen->state.local_offset == 0) {

+            gen->state.local_offset++;

+            gen->state.remote_offset--;

         }

-        if (slapi_is_loglevel_set(SLAPI_LOG_REPL)) {

-            slapi_log_err(SLAPI_LOG_REPL, "csngen_adjust_time",

-                          "gen state after %08lx%04x:%ld:%ld:%ld\n",

-                          new_time, gen->state.seq_num,

-                          gen->state.sampled_time,

-                          gen->state.local_offset,

-                          gen->state.remote_offset);

+    }

+    /* Time to compute seqnum so that 

+     *   new csn >= remote csn and new csn >= old local csn 

+     */

+    new_time = CSN_CALC_TSTAMP(gen);

+    PR_ASSERT(new_time >= old_time);

+    PR_ASSERT(new_time >= remote_time);

+    if (new_time > old_time) {

+        /* Can reset (local) seqnum */

+        gen->state.seq_num = 0;

+    }

+    if (new_time == remote_time && remote_seqnum >= gen->state.seq_num) {

+        if (remote_seqnum >= CSN_MAX_SEQNUM) {

+            gen->state.seq_num = 0;

+            gen->state.local_offset++;

+        } else {

+            gen->state.seq_num = remote_seqnum + 1;

         }

-    } else if (gen->state.remote_offset > 0) {

-        /* decrease remote offset? */

-        /* how to decrease remote offset but ensure that we don't

-           generate a duplicate CSN, or a CSN smaller than one we've already

-           generated? */

+    }

+

+    if (slapi_is_loglevel_set(SLAPI_LOG_REPL)) {

+        slapi_log_err(SLAPI_LOG_REPL, "csngen_adjust_time",

+                      "gen state after %08lx%04x:%ld:%ld:%ld\n",

+                      new_time, gen->state.seq_num,

+                      gen->state.sampled_time,

+                      gen->state.local_offset,

+                      gen->state.remote_offset);

     }

     slapi_rwlock_unlock(gen->lock);

@@ -435,16 +420,16 @@ csngen_unregister_callbacks(CSNGen *gen, void *cookie)

 /* debugging function */

 void

-csngen_dump_state(const CSNGen *gen)

+csngen_dump_state(const CSNGen *gen, int severity)

 {

     if (gen) {

         slapi_rwlock_rdlock(gen->lock);

-        slapi_log_err(SLAPI_LOG_DEBUG, "csngen_dump_state", "CSN generator's state:\n");

-        slapi_log_err(SLAPI_LOG_DEBUG, "csngen_dump_state", "\treplica id: %d\n", gen->state.rid);

-        slapi_log_err(SLAPI_LOG_DEBUG, "csngen_dump_state", "\tsampled time: %ld\n", gen->state.sampled_time);

-        slapi_log_err(SLAPI_LOG_DEBUG, "csngen_dump_state", "\tlocal offset: %ld\n", gen->state.local_offset);

-        slapi_log_err(SLAPI_LOG_DEBUG, "csngen_dump_state", "\tremote offset: %ld\n", gen->state.remote_offset);

-        slapi_log_err(SLAPI_LOG_DEBUG, "csngen_dump_state", "\tsequence number: %d\n", gen->state.seq_num);

+        slapi_log_err(severity, "csngen_dump_state", "CSN generator's state:\n");

+        slapi_log_err(severity, "csngen_dump_state", "\treplica id: %d\n", gen->state.rid);

+        slapi_log_err(severity, "csngen_dump_state", "\tsampled time: %ld\n", gen->state.sampled_time);

+        slapi_log_err(severity, "csngen_dump_state", "\tlocal offset: %ld\n", gen->state.local_offset);

+        slapi_log_err(severity, "csngen_dump_state", "\tremote offset: %ld\n", gen->state.remote_offset);

+        slapi_log_err(severity, "csngen_dump_state", "\tsequence number: %d\n", gen->state.seq_num);

         slapi_rwlock_unlock(gen->lock);

     }

 }

@@ -459,7 +444,7 @@ csngen_test()

     CSNGen *gen = csngen_new(255, NULL);

     slapi_log_err(SLAPI_LOG_DEBUG, "csngen_test", "staring csn generator test ...");

-    csngen_dump_state(gen);

+    csngen_dump_state(gen, SLAPI_LOG_INFO);

     rc = _csngen_start_test_threads(gen);

     if (rc == 0) {

@@ -469,7 +454,7 @@ csngen_test()

     }

     _csngen_stop_test_threads();

-    csngen_dump_state(gen);

+    csngen_dump_state(gen, SLAPI_LOG_INFO);

     slapi_log_err(SLAPI_LOG_DEBUG, "csngen_test", "csn generator test is complete...");

 }

@@ -574,94 +559,93 @@ _csngen_cmp_callbacks(const void *el1, const void *el2)

         return 1;

 }

+/* Get time and adjust local offset */

 static int

-_csngen_adjust_local_time(CSNGen *gen, time_t cur_time)

+_csngen_adjust_local_time(CSNGen *gen)

 {

     extern int config_get_ignore_time_skew(void);

     int ignore_time_skew = config_get_ignore_time_skew();

-    time_t time_diff = cur_time - gen->state.sampled_time;

+    struct timespec now = {0};

+    time_t time_diff;

+    time_t cur_time;

+    int rc;

+    

+    if ((rc = gen->gettime(&now)) != 0) {

+        /* Failed to get system time, we must abort */

+        slapi_log_err(SLAPI_LOG_ERR, "csngen_new_csn",

+                "Failed to get system time (%s)\n",

+                slapd_system_strerror(rc));

+        return CSN_TIME_ERROR;

+    }

+    cur_time = now.tv_sec;

+    time_diff = cur_time - gen->state.sampled_time;

+

+    /* check if the time should be adjusted */

     if (time_diff == 0) {

         /* This is a no op - _csngen_adjust_local_time should never be called

            in this case, because there is nothing to adjust - but just return

            here to protect ourselves

         */

         return CSN_SUCCESS;

-    } else if (time_diff > 0) {

-        time_t ts_before = CSN_CALC_TSTAMP(gen);

-        time_t ts_after = 0;

-        if (slapi_is_loglevel_set(SLAPI_LOG_REPL)) {

-            time_t new_time = CSN_CALC_TSTAMP(gen);

-            slapi_log_err(SLAPI_LOG_REPL, "_csngen_adjust_local_time",

-                          "gen state before %08lx%04x:%ld:%ld:%ld\n",

-                          new_time, gen->state.seq_num,

-                          gen->state.sampled_time,

-                          gen->state.local_offset,

-                          gen->state.remote_offset);

-        }

-

-        gen->state.sampled_time = cur_time;

-        if (time_diff > gen->state.local_offset)

-            gen->state.local_offset = 0;

-        else

-            gen->state.local_offset = gen->state.local_offset - time_diff;

-

-        /* only reset the seq_num if the new timestamp part of the CSN

-           is going to be greater than the old one - if they are the

-           same after the above adjustment (which can happen if

-           csngen_adjust_time has to store the offset in the

-           local_offset field) we must not allow the CSN to regress or

-           generate duplicate numbers */

-        ts_after = CSN_CALC_TSTAMP(gen);

-        if (ts_after > ts_before) {

-            gen->state.seq_num = 0; /* only reset if new time > old time */

-        }

-

-        if (slapi_is_loglevel_set(SLAPI_LOG_REPL)) {

-            time_t new_time = CSN_CALC_TSTAMP(gen);

-            slapi_log_err(SLAPI_LOG_REPL, "_csngen_adjust_local_time",

-                          "gen state after %08lx%04x:%ld:%ld:%ld\n",

-                          new_time, gen->state.seq_num,

-                          gen->state.sampled_time,

-                          gen->state.local_offset,

-                          gen->state.remote_offset);

-        }

-        return CSN_SUCCESS;

-    } else /* time was turned back */

-    {

-        if (slapi_is_loglevel_set(SLAPI_LOG_REPL)) {

-            time_t new_time = CSN_CALC_TSTAMP(gen);

-            slapi_log_err(SLAPI_LOG_REPL, "_csngen_adjust_local_time",

-                          "gen state back before %08lx%04x:%ld:%ld:%ld\n",

-                          new_time, gen->state.seq_num,

-                          gen->state.sampled_time,

-                          gen->state.local_offset,

-                          gen->state.remote_offset);

-        }

+    }

+    if (labs(time_diff) > TIME_DIFF_WARNING_DELAY) {

+        /* We had a jump larger than a day */

+        slapi_log_err(SLAPI_LOG_INFO, "csngen_new_csn",

+                "Detected large jump in CSN time.  Delta: %ld (current time: %ld  vs  previous time: %ld)\n",

+                time_diff, cur_time, gen->state.sampled_time);

+    }

+    if (!ignore_time_skew && (gen->state.local_offset - time_diff > CSN_MAX_TIME_ADJUST)) {

+        slapi_log_err(SLAPI_LOG_ERR, "_csngen_adjust_local_time",

+                      "Adjustment limit exceeded; value - %ld, limit - %d\n",

+                      gen->state.local_offset - time_diff, CSN_MAX_TIME_ADJUST);

+        return CSN_LIMIT_EXCEEDED;

+    }

-        if (!ignore_time_skew && (labs(time_diff) > CSN_MAX_TIME_ADJUST)) {

-            slapi_log_err(SLAPI_LOG_ERR, "_csngen_adjust_local_time",

-                          "Adjustment limit exceeded; value - %ld, limit - %d\n",

-                          labs(time_diff), CSN_MAX_TIME_ADJUST);

-            return CSN_LIMIT_EXCEEDED;

-        }

+    time_t ts_before = CSN_CALC_TSTAMP(gen);

+    time_t ts_after = 0;

+    if (slapi_is_loglevel_set(SLAPI_LOG_REPL)) {

+        time_t new_time = CSN_CALC_TSTAMP(gen);

+        slapi_log_err(SLAPI_LOG_REPL, "_csngen_adjust_local_time",

+                      "gen state before %08lx%04x:%ld:%ld:%ld\n",

+                      new_time, gen->state.seq_num,

+                      gen->state.sampled_time,

+                      gen->state.local_offset,

+                      gen->state.remote_offset);

+    }

-        gen->state.sampled_time = cur_time;

-        gen->state.local_offset = MAX_VAL(gen->state.local_offset, labs(time_diff));

-        gen->state.seq_num = 0;

+    gen->state.sampled_time = cur_time;

+    gen->state.local_offset = MAX_VAL(0, gen->state.local_offset - time_diff);

+    /* new local_offset = MAX_VAL(0, old sample_time + old local_offset - cur_time)

+     * ==> new local_offset >= 0 and 

+     *     new local_offset + cur_time >= old sample_time + old local_offset

+     * ==> new local_offset + cur_time + remote_offset >=

+     *            sample_time + old local_offset + remote_offset

+     * ==> CSN_CALC_TSTAMP(new gen) >= CSN_CALC_TSTAMP(old gen)

+     */

-        if (slapi_is_loglevel_set(SLAPI_LOG_REPL)) {

-            time_t new_time = CSN_CALC_TSTAMP(gen);

-            slapi_log_err(SLAPI_LOG_REPL, "_csngen_adjust_local_time",

-                          "gen state back after %08lx%04x:%ld:%ld:%ld\n",

-                          new_time, gen->state.seq_num,

-                          gen->state.sampled_time,

-                          gen->state.local_offset,

-                          gen->state.remote_offset);

-        }

+    /* only reset the seq_num if the new timestamp part of the CSN

+       is going to be greater than the old one - if they are the

+       same after the above adjustment (which can happen if

+       csngen_adjust_time has to store the offset in the

+       local_offset field) we must not allow the CSN to regress or

+       generate duplicate numbers */

+    ts_after = CSN_CALC_TSTAMP(gen);

+    PR_ASSERT(ts_after >= ts_before);

+    if (ts_after > ts_before) {

+        gen->state.seq_num = 0; /* only reset if new time > old time */

+    }

-        return CSN_SUCCESS;

+    if (slapi_is_loglevel_set(SLAPI_LOG_REPL)) {

+        time_t new_time = CSN_CALC_TSTAMP(gen);

+        slapi_log_err(SLAPI_LOG_REPL, "_csngen_adjust_local_time",

+                      "gen state after %08lx%04x:%ld:%ld:%ld\n",

+                      new_time, gen->state.seq_num,

+                      gen->state.sampled_time,

+                      gen->state.local_offset,

+                      gen->state.remote_offset);

     }

+    return CSN_SUCCESS;

 }

 /*

@@ -799,7 +783,7 @@ _csngen_remote_tester_main(void *data)

                               "Failed to adjust generator's time; csn error - %d\n", rc);

             }

-            csngen_dump_state(gen);

+            csngen_dump_state(gen, SLAPI_LOG_INFO);

         }

         csn_free(&csn;;

@@ -825,8 +809,83 @@ _csngen_local_tester_main(void *data)

         /*

          * g_sampled_time -= slapi_rand () % 100;

          */

-        csngen_dump_state(gen);

+        csngen_dump_state(gen, SLAPI_LOG_INFO);

     }

     PR_AtomicDecrement(&s_thread_count);

 }

+

+int _csngen_tester_state;

+int _csngen_tester_state_rid;

+

+static int

+_mynoise(int time, int len, double height)

+{

+   if (((time/len) % 2) == 0) {

+        return -height + 2 * height * ( time % len ) / (len-1);

+   } else {

+        return height - 2 * height * ( time % len ) / (len-1);

+   }

+}

+

+

+int32_t _csngen_tester_gettime(struct timespec *tp)

+{

+    int vtime = _csngen_tester_state ;

+    tp->tv_sec = 0x1000000 + vtime + 2 * _csngen_tester_state_rid;

+    if (_csngen_tester_state_rid == 3) {

+        /* tp->tv_sec += _mynoise(vtime, 10, 1.5); */

+        tp->tv_sec += _mynoise(vtime, 30, 15);

+    }

+    return 0;

+}

+

+/* Mimic a fully meshed multi suplier topology */

+void csngen_multi_suppliers_test(void)

+{

+#define NB_TEST_MASTERS	6

+#define NB_TEST_STATES	500

+    CSNGen *gen[NB_TEST_MASTERS];

+    struct timespec now = {0};

+    CSN *last_csn = NULL;

+    CSN *csn = NULL;

+    int i,j,rc;

+

+    _csngen_tester_gettime(&now;;

+

+    for (i=0; i< NB_TEST_MASTERS; i++) {

+        gen[i] = csngen_new(i+1, NULL);

+        gen[i]->gettime = _csngen_tester_gettime;

+        gen[i]->state.sampled_time = now.tv_sec;

+    }

+

+    for (_csngen_tester_state=0; _csngen_tester_state < NB_TEST_STATES; _csngen_tester_state++) {

+        for (i=0; i< NB_TEST_MASTERS; i++) {

+            _csngen_tester_state_rid = i+1;

+            rc = csngen_new_csn(gen[i], &csn, PR_FALSE);

+            if (rc) {

+                continue;

+            }

+            csngen_dump_state(gen[i], SLAPI_LOG_INFO);

+

+            if (csn_compare(csn, last_csn) <= 0) {

+                slapi_log_err(SLAPI_LOG_ERR, "csngen_multi_suppliers_test",

+                              "CSN generated in disorder state=%d rid=%d\n", _csngen_tester_state, _csngen_tester_state_rid);

+                _csngen_tester_state = NB_TEST_STATES;

+                break;

+            }

+            last_csn = csn;

+

+            for (j=0; j< NB_TEST_MASTERS; j++) {

+                if (i==j) {

+                    continue;

+                }

+                _csngen_tester_state_rid = j+1;

+                rc = csngen_adjust_time(gen[j], csn);

+                if (rc) {

+                    continue;

+                }

+            }

+        }

+    }

+}

diff --git a/ldap/servers/slapd/slapi-plugin.h b/ldap/servers/slapd/slapi-plugin.h

index 56765fdfb..59c5ec9ab 100644

--- a/ldap/servers/slapd/slapi-plugin.h

+++ b/ldap/servers/slapd/slapi-plugin.h

@@ -6762,8 +6762,17 @@ time_t slapi_current_time(void) __attribute__((deprecated));

  *

  * \param tp - a timespec struct where the system time is set

  * \return result code, upon success tp is set to the system time

+ * as a clock in UTC timezone. This clock adjusts with ntp steps,

+ * and should NOT be used for timer information.

  */

 int32_t slapi_clock_gettime(struct timespec *tp);

+/* 

+ * slapi_clock_gettime should have better been called

+ * slapi_clock_utc_gettime but sice the function pre-existed

+ * we are just adding an alias (to avoid risking to break

+ * some custom plugins)

+ */

+#define slapi_clock_utc_gettime slapi_clock_gettime

 /**

  * Returns the current system time as a hr clock relative to uptime

-- 

2.31.1