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syncprov.c

/* $OpenLDAP: pkg/ldap/servers/slapd/overlays/syncprov.c,v 1.147.2.29 2008/05/29 22:57:32 quanah Exp $ */
/* syncprov.c - syncrepl provider */
/* This work is part of OpenLDAP Software <http://www.openldap.org/>.
 *
 * Copyright 2004-2008 The OpenLDAP Foundation.
 * All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted only as authorized by the OpenLDAP
 * Public License.
 *
 * A copy of this license is available in the file LICENSE in the
 * top-level directory of the distribution or, alternatively, at
 * <http://www.OpenLDAP.org/license.html>.
 */
/* ACKNOWLEDGEMENTS:
 * This work was initially developed by Howard Chu for inclusion in
 * OpenLDAP Software.
 */

#include "portable.h"

#ifdef SLAPD_OVER_SYNCPROV

#include <ac/string.h>
#include "lutil.h"
#include "slap.h"
#include "config.h"
#include "ldap_rq.h"

/* A modify request on a particular entry */
typedef struct modinst {
      struct modinst *mi_next;
      Operation *mi_op;
} modinst;

typedef struct modtarget {
      struct modinst *mt_mods;
      struct modinst *mt_tail;
      Operation *mt_op;
      ldap_pvt_thread_mutex_t mt_mutex;
} modtarget;

/* A queued result of a persistent search */
typedef struct syncres {
      struct syncres *s_next;
      struct berval s_dn;
      struct berval s_ndn;
      struct berval s_uuid;
      struct berval s_csn;
      char s_mode;
      char s_isreference;
} syncres;

/* Record of a persistent search */
typedef struct syncops {
      struct syncops *s_next;
      struct berval     s_base;           /* ndn of search base */
      ID          s_eid;            /* entryID of search base */
      Operation   *s_op;            /* search op */
      int         s_rid;
      int         s_sid;
      struct berval s_filterstr;
      int         s_flags;    /* search status */
#define     PS_IS_REFRESHING  0x01
#define     PS_IS_DETACHED          0x02
#define     PS_WROTE_BASE           0x04
#define     PS_FIND_BASE            0x08
#define     PS_FIX_FILTER           0x10

      int         s_inuse;    /* reference count */
      struct syncres *s_res;
      struct syncres *s_restail;
      struct re_s *s_qtask;   /* task for playing psearch responses */
#define     RUNQ_INTERVAL     36000 /* a long time */
      ldap_pvt_thread_mutex_t s_mutex;
} syncops;

/* A received sync control */
typedef struct sync_control {
      struct sync_cookie sr_state;
      int sr_rhint;
} sync_control;

#if 0 /* moved back to slap.h */
#define     o_sync      o_ctrlflag[slap_cids.sc_LDAPsync]
#endif
/* o_sync_mode uses data bits of o_sync */
#define     o_sync_mode o_ctrlflag[slap_cids.sc_LDAPsync]

#define SLAP_SYNC_NONE                          (LDAP_SYNC_NONE<<SLAP_CONTROL_SHIFT)
#define SLAP_SYNC_REFRESH                       (LDAP_SYNC_REFRESH_ONLY<<SLAP_CONTROL_SHIFT)
#define SLAP_SYNC_PERSIST                       (LDAP_SYNC_RESERVED<<SLAP_CONTROL_SHIFT)
#define SLAP_SYNC_REFRESH_AND_PERSIST     (LDAP_SYNC_REFRESH_AND_PERSIST<<SLAP_CONTROL_SHIFT)

/* Record of which searches matched at premodify step */
typedef struct syncmatches {
      struct syncmatches *sm_next;
      syncops *sm_op;
} syncmatches;

/* Session log data */
typedef struct slog_entry {
      struct slog_entry *se_next;
      struct berval se_uuid;
      struct berval se_csn;
      int   se_sid;
      ber_tag_t   se_tag;
} slog_entry;

typedef struct sessionlog {
      struct berval     sl_mincsn;
      int         sl_num;
      int         sl_size;
      slog_entry *sl_head;
      slog_entry *sl_tail;
      ldap_pvt_thread_mutex_t sl_mutex;
} sessionlog;

/* The main state for this overlay */
typedef struct syncprov_info_t {
      syncops           *si_ops;
      BerVarray   si_ctxcsn;  /* ldapsync context */
      int         *si_sids;
      int         si_numcsns;
      int         si_chkops;  /* checkpointing info */
      int         si_chktime;
      int         si_numops;  /* number of ops since last checkpoint */
      int         si_nopres;  /* Skip present phase */
      int         si_usehint; /* use reload hint */
      time_t      si_chklast; /* time of last checkpoint */
      Avlnode     *si_mods;   /* entries being modified */
      sessionlog  *si_logs;
      ldap_pvt_thread_rdwr_t  si_csn_rwlock;
      ldap_pvt_thread_mutex_t si_ops_mutex;
      ldap_pvt_thread_mutex_t si_mods_mutex;
} syncprov_info_t;

typedef struct opcookie {
      slap_overinst *son;
      syncmatches *smatches;
      struct berval sdn;      /* DN of entry, for deletes */
      struct berval sndn;
      struct berval suuid;    /* UUID of entry */
      struct berval sctxcsn;
      int sreference;   /* Is the entry a reference? */
} opcookie;

typedef struct fbase_cookie {
      struct berval *fdn;     /* DN of a modified entry, for scope testing */
      syncops *fss;     /* persistent search we're testing against */
      int fbase;  /* if TRUE we found the search base and it's still valid */
      int fscope; /* if TRUE then fdn is within the psearch scope */
} fbase_cookie;

static AttributeName csn_anlist[3];
static AttributeName uuid_anlist[2];

/* Build a LDAPsync intermediate state control */
static int
syncprov_state_ctrl(
      Operation   *op,
      SlapReply   *rs,
      Entry       *e,
      int         entry_sync_state,
      LDAPControl **ctrls,
      int         num_ctrls,
      int         send_cookie,
      struct berval     *cookie )
{
      Attribute* a;
      int ret;

      BerElementBuffer berbuf;
      BerElement *ber = (BerElement *)&berbuf;

      struct berval     entryuuid_bv = BER_BVNULL;

      ber_init2( ber, 0, LBER_USE_DER );
      ber_set_option( ber, LBER_OPT_BER_MEMCTX, &op->o_tmpmemctx );

      ctrls[num_ctrls] = op->o_tmpalloc( sizeof ( LDAPControl ), op->o_tmpmemctx );

      for ( a = e->e_attrs; a != NULL; a = a->a_next ) {
            AttributeDescription *desc = a->a_desc;
            if ( desc == slap_schema.si_ad_entryUUID ) {
                  entryuuid_bv = a->a_nvals[0];
                  break;
            }
      }

      /* FIXME: what if entryuuid is NULL or empty ? */

      if ( send_cookie && cookie ) {
            ber_printf( ber, "{eOON}",
                  entry_sync_state, &entryuuid_bv, cookie );
      } else {
            ber_printf( ber, "{eON}",
                  entry_sync_state, &entryuuid_bv );
      }

      ctrls[num_ctrls]->ldctl_oid = LDAP_CONTROL_SYNC_STATE;
      ctrls[num_ctrls]->ldctl_iscritical = (op->o_sync == SLAP_CONTROL_CRITICAL);
      ret = ber_flatten2( ber, &ctrls[num_ctrls]->ldctl_value, 1 );

      ber_free_buf( ber );

      if ( ret < 0 ) {
            Debug( LDAP_DEBUG_TRACE,
                  "slap_build_sync_ctrl: ber_flatten2 failed\n",
                  0, 0, 0 );
            send_ldap_error( op, rs, LDAP_OTHER, "internal error" );
            return ret;
      }

      return LDAP_SUCCESS;
}

/* Build a LDAPsync final state control */
static int
syncprov_done_ctrl(
      Operation   *op,
      SlapReply   *rs,
      LDAPControl **ctrls,
      int               num_ctrls,
      int               send_cookie,
      struct berval *cookie,
      int               refreshDeletes )
{
      int ret;
      BerElementBuffer berbuf;
      BerElement *ber = (BerElement *)&berbuf;

      ber_init2( ber, NULL, LBER_USE_DER );
      ber_set_option( ber, LBER_OPT_BER_MEMCTX, &op->o_tmpmemctx );

      ctrls[num_ctrls] = op->o_tmpalloc( sizeof ( LDAPControl ), op->o_tmpmemctx );

      ber_printf( ber, "{" );
      if ( send_cookie && cookie ) {
            ber_printf( ber, "O", cookie );
      }
      if ( refreshDeletes == LDAP_SYNC_REFRESH_DELETES ) {
            ber_printf( ber, "b", refreshDeletes );
      }
      ber_printf( ber, "N}" );

      ctrls[num_ctrls]->ldctl_oid = LDAP_CONTROL_SYNC_DONE;
      ctrls[num_ctrls]->ldctl_iscritical = (op->o_sync == SLAP_CONTROL_CRITICAL);
      ret = ber_flatten2( ber, &ctrls[num_ctrls]->ldctl_value, 1 );

      ber_free_buf( ber );

      if ( ret < 0 ) {
            Debug( LDAP_DEBUG_TRACE,
                  "syncprov_done_ctrl: ber_flatten2 failed\n",
                  0, 0, 0 );
            send_ldap_error( op, rs, LDAP_OTHER, "internal error" );
            return ret;
      }

      return LDAP_SUCCESS;
}

static int
syncprov_sendinfo(
      Operation   *op,
      SlapReply   *rs,
      int               type,
      struct berval *cookie,
      int               refreshDone,
      BerVarray   syncUUIDs,
      int               refreshDeletes )
{
      BerElementBuffer berbuf;
      BerElement *ber = (BerElement *)&berbuf;
      struct berval rspdata;

      int ret;

      ber_init2( ber, NULL, LBER_USE_DER );
      ber_set_option( ber, LBER_OPT_BER_MEMCTX, &op->o_tmpmemctx );

      if ( type ) {
            switch ( type ) {
            case LDAP_TAG_SYNC_NEW_COOKIE:
                  ber_printf( ber, "tO", type, cookie );
                  break;
            case LDAP_TAG_SYNC_REFRESH_DELETE:
            case LDAP_TAG_SYNC_REFRESH_PRESENT:
                  ber_printf( ber, "t{", type );
                  if ( cookie ) {
                        ber_printf( ber, "O", cookie );
                  }
                  if ( refreshDone == 0 ) {
                        ber_printf( ber, "b", refreshDone );
                  }
                  ber_printf( ber, "N}" );
                  break;
            case LDAP_TAG_SYNC_ID_SET:
                  ber_printf( ber, "t{", type );
                  if ( cookie ) {
                        ber_printf( ber, "O", cookie );
                  }
                  if ( refreshDeletes == 1 ) {
                        ber_printf( ber, "b", refreshDeletes );
                  }
                  ber_printf( ber, "[W]", syncUUIDs );
                  ber_printf( ber, "N}" );
                  break;
            default:
                  Debug( LDAP_DEBUG_TRACE,
                        "syncprov_sendinfo: invalid syncinfo type (%d)\n",
                        type, 0, 0 );
                  return LDAP_OTHER;
            }
      }

      ret = ber_flatten2( ber, &rspdata, 0 );

      if ( ret < 0 ) {
            Debug( LDAP_DEBUG_TRACE,
                  "syncprov_sendinfo: ber_flatten2 failed\n",
                  0, 0, 0 );
            send_ldap_error( op, rs, LDAP_OTHER, "internal error" );
            return ret;
      }

      rs->sr_rspoid = LDAP_SYNC_INFO;
      rs->sr_rspdata = &rspdata;
      send_ldap_intermediate( op, rs );
      rs->sr_rspdata = NULL;
      ber_free_buf( ber );

      return LDAP_SUCCESS;
}

/* Find a modtarget in an AVL tree */
static int
sp_avl_cmp( const void *c1, const void *c2 )
{
      const modtarget *m1, *m2;
      int rc;

      m1 = c1; m2 = c2;
      rc = m1->mt_op->o_req_ndn.bv_len - m2->mt_op->o_req_ndn.bv_len;

      if ( rc ) return rc;
      return ber_bvcmp( &m1->mt_op->o_req_ndn, &m2->mt_op->o_req_ndn );
}

/* syncprov_findbase:
 *   finds the true DN of the base of a search (with alias dereferencing) and
 * checks to make sure the base entry doesn't get replaced with a different
 * entry (e.g., swapping trees via ModDN, or retargeting an alias). If a
 * change is detected, any persistent search on this base must be terminated /
 * reloaded.
 *   On the first call, we just save the DN and entryID. On subsequent calls
 * we compare the DN and entryID with the saved values.
 */
static int
findbase_cb( Operation *op, SlapReply *rs )
{
      slap_callback *sc = op->o_callback;

      if ( rs->sr_type == REP_SEARCH && rs->sr_err == LDAP_SUCCESS ) {
            fbase_cookie *fc = sc->sc_private;

            /* If no entryID, we're looking for the first time.
             * Just store whatever we got.
             */
            if ( fc->fss->s_eid == NOID ) {
                  fc->fbase = 2;
                  fc->fss->s_eid = rs->sr_entry->e_id;
                  ber_dupbv( &fc->fss->s_base, &rs->sr_entry->e_nname );

            } else if ( rs->sr_entry->e_id == fc->fss->s_eid &&
                  dn_match( &rs->sr_entry->e_nname, &fc->fss->s_base )) {

            /* OK, the DN is the same and the entryID is the same. */
                  fc->fbase = 1;
            }
      }
      if ( rs->sr_err != LDAP_SUCCESS ) {
            Debug( LDAP_DEBUG_ANY, "findbase failed! %d\n", rs->sr_err,0,0 );
      }
      return LDAP_SUCCESS;
}

static Filter generic_filter = { LDAP_FILTER_PRESENT, { 0 }, NULL };
static struct berval generic_filterstr = BER_BVC("(objectclass=*)");

static int
syncprov_findbase( Operation *op, fbase_cookie *fc )
{
      opcookie *opc = op->o_callback->sc_private;
      slap_overinst *on = opc->son;

      /* Use basic parameters from syncrepl search, but use
       * current op's threadctx / tmpmemctx
       */
      ldap_pvt_thread_mutex_lock( &fc->fss->s_mutex );
      if ( fc->fss->s_flags & PS_FIND_BASE ) {
            slap_callback cb = {0};
            Operation fop;
            SlapReply frs = { REP_RESULT };
            int rc;

            fc->fss->s_flags ^= PS_FIND_BASE;
            ldap_pvt_thread_mutex_unlock( &fc->fss->s_mutex );

            fop = *fc->fss->s_op;

            fop.o_bd = fop.o_bd->bd_self;
            fop.o_hdr = op->o_hdr;
            fop.o_time = op->o_time;
            fop.o_tincr = op->o_tincr;

            cb.sc_response = findbase_cb;
            cb.sc_private = fc;

            fop.o_sync_mode = 0;    /* turn off sync mode */
            fop.o_managedsait = SLAP_CONTROL_CRITICAL;
            fop.o_callback = &cb;
            fop.o_tag = LDAP_REQ_SEARCH;
            fop.ors_scope = LDAP_SCOPE_BASE;
            fop.ors_limit = NULL;
            fop.ors_slimit = 1;
            fop.ors_tlimit = SLAP_NO_LIMIT;
            fop.ors_attrs = slap_anlist_no_attrs;
            fop.ors_attrsonly = 1;
            fop.ors_filter = &generic_filter;
            fop.ors_filterstr = generic_filterstr;

            rc = fop.o_bd->be_search( &fop, &frs );
      } else {
            ldap_pvt_thread_mutex_unlock( &fc->fss->s_mutex );
            fc->fbase = 1;
      }

      /* After the first call, see if the fdn resides in the scope */
      if ( fc->fbase == 1 ) {
            switch ( fc->fss->s_op->ors_scope ) {
            case LDAP_SCOPE_BASE:
                  fc->fscope = dn_match( fc->fdn, &fc->fss->s_base );
                  break;
            case LDAP_SCOPE_ONELEVEL: {
                  struct berval pdn;
                  dnParent( fc->fdn, &pdn );
                  fc->fscope = dn_match( &pdn, &fc->fss->s_base );
                  break; }
            case LDAP_SCOPE_SUBTREE:
                  fc->fscope = dnIsSuffix( fc->fdn, &fc->fss->s_base );
                  break;
            case LDAP_SCOPE_SUBORDINATE:
                  fc->fscope = dnIsSuffix( fc->fdn, &fc->fss->s_base ) &&
                        !dn_match( fc->fdn, &fc->fss->s_base );
                  break;
            }
      }

      if ( fc->fbase )
            return LDAP_SUCCESS;

      /* If entryID has changed, then the base of this search has
       * changed. Invalidate the psearch.
       */
      return LDAP_NO_SUCH_OBJECT;
}

/* syncprov_findcsn:
 *   This function has three different purposes, but they all use a search
 * that filters on entryCSN so they're combined here.
 * 1: at startup time, after a contextCSN has been read from the database,
 * we search for all entries with CSN >= contextCSN in case the contextCSN
 * was not checkpointed at the previous shutdown.
 *
 * 2: when the current contextCSN is known and we have a sync cookie, we search
 * for one entry with CSN = the cookie CSN. If not found, try <= cookie CSN.
 * If an entry is found, the cookie CSN is valid, otherwise it is stale.
 *
 * 3: during a refresh phase, we search for all entries with CSN <= the cookie
 * CSN, and generate Present records for them. We always collect this result
 * in SyncID sets, even if there's only one match.
 */
typedef enum find_csn_t {
      FIND_MAXCSN = 1,
      FIND_CSN    = 2,
      FIND_PRESENT      = 3
} find_csn_t;

static int
findmax_cb( Operation *op, SlapReply *rs )
{
      if ( rs->sr_type == REP_SEARCH && rs->sr_err == LDAP_SUCCESS ) {
            struct berval *maxcsn = op->o_callback->sc_private;
            Attribute *a = attr_find( rs->sr_entry->e_attrs,
                  slap_schema.si_ad_entryCSN );

            if ( a && ber_bvcmp( &a->a_vals[0], maxcsn ) > 0 &&
                  slap_parse_csn_sid( &a->a_vals[0] ) == slap_serverID ) {
                  maxcsn->bv_len = a->a_vals[0].bv_len;
                  strcpy( maxcsn->bv_val, a->a_vals[0].bv_val );
            }
      }
      return LDAP_SUCCESS;
}

static int
findcsn_cb( Operation *op, SlapReply *rs )
{
      slap_callback *sc = op->o_callback;

      /* We just want to know that at least one exists, so it's OK if
       * we exceed the unchecked limit.
       */
      if ( rs->sr_err == LDAP_ADMINLIMIT_EXCEEDED ||
            (rs->sr_type == REP_SEARCH && rs->sr_err == LDAP_SUCCESS )) {
            sc->sc_private = (void *)1;
      }
      return LDAP_SUCCESS;
}

/* Build a list of entryUUIDs for sending in a SyncID set */

#define UUID_LEN  16

typedef struct fpres_cookie {
      int num;
      BerVarray uuids;
      char *last;
} fpres_cookie;

static int
findpres_cb( Operation *op, SlapReply *rs )
{
      slap_callback *sc = op->o_callback;
      fpres_cookie *pc = sc->sc_private;
      Attribute *a;
      int ret = SLAP_CB_CONTINUE;

      switch ( rs->sr_type ) {
      case REP_SEARCH:
            a = attr_find( rs->sr_entry->e_attrs, slap_schema.si_ad_entryUUID );
            if ( a ) {
                  pc->uuids[pc->num].bv_val = pc->last;
                  AC_MEMCPY( pc->uuids[pc->num].bv_val, a->a_nvals[0].bv_val,
                        pc->uuids[pc->num].bv_len );
                  pc->num++;
                  pc->last = pc->uuids[pc->num].bv_val;
                  pc->uuids[pc->num].bv_val = NULL;
            }
            ret = LDAP_SUCCESS;
            if ( pc->num != SLAP_SYNCUUID_SET_SIZE )
                  break;
            /* FALLTHRU */
      case REP_RESULT:
            ret = rs->sr_err;
            if ( pc->num ) {
                  ret = syncprov_sendinfo( op, rs, LDAP_TAG_SYNC_ID_SET, NULL,
                        0, pc->uuids, 0 );
                  pc->uuids[pc->num].bv_val = pc->last;
                  pc->num = 0;
                  pc->last = pc->uuids[0].bv_val;
            }
            break;
      default:
            break;
      }
      return ret;
}

static int
syncprov_findcsn( Operation *op, find_csn_t mode )
{
      slap_overinst           *on = (slap_overinst *)op->o_bd->bd_info;
      syncprov_info_t         *si = on->on_bi.bi_private;

      slap_callback cb = {0};
      Operation fop;
      SlapReply frs = { REP_RESULT };
      char buf[LDAP_LUTIL_CSNSTR_BUFSIZE + STRLENOF("(entryCSN<=)")];
      char cbuf[LDAP_LUTIL_CSNSTR_BUFSIZE];
      struct berval maxcsn;
      Filter cf;
      AttributeAssertion eq = ATTRIBUTEASSERTION_INIT;
      fpres_cookie pcookie;
      sync_control *srs = NULL;
      struct slap_limits_set fc_limits;
      int i, rc = LDAP_SUCCESS, findcsn_retry = 1;
      int maxid;

      if ( mode != FIND_MAXCSN ) {
            srs = op->o_controls[slap_cids.sc_LDAPsync];
      }

      fop = *op;
      fop.o_sync_mode &= SLAP_CONTROL_MASK;     /* turn off sync_mode */
      /* We want pure entries, not referrals */
      fop.o_managedsait = SLAP_CONTROL_CRITICAL;

      cf.f_ava = &eq;
      cf.f_av_desc = slap_schema.si_ad_entryCSN;
      BER_BVZERO( &cf.f_av_value );
      cf.f_next = NULL;

      fop.o_callback = &cb;
      fop.ors_limit = NULL;
      fop.ors_tlimit = SLAP_NO_LIMIT;
      fop.ors_filter = &cf;
      fop.ors_filterstr.bv_val = buf;

again:
      switch( mode ) {
      case FIND_MAXCSN:
            cf.f_choice = LDAP_FILTER_GE;
            /* If there are multiple CSNs, use the one with our serverID */
            for ( i=0; i<si->si_numcsns; i++) {
                  if ( slap_serverID == si->si_sids[i] ) {
                        maxid = i;
                        break;
                  }
            }
            if ( i == si->si_numcsns ) {
                  /* No match: this is multimaster, and none of the content in the DB
                   * originated locally. Treat like no CSN.
                   */
                  return LDAP_NO_SUCH_OBJECT;
            }
            cf.f_av_value = si->si_ctxcsn[maxid];
            fop.ors_filterstr.bv_len = snprintf( buf, sizeof( buf ),
                  "(entryCSN>=%s)", cf.f_av_value.bv_val );
            if ( fop.ors_filterstr.bv_len < 0 || fop.ors_filterstr.bv_len >= sizeof( buf ) ) {
                  return LDAP_OTHER;
            }
            fop.ors_attrsonly = 0;
            fop.ors_attrs = csn_anlist;
            fop.ors_slimit = SLAP_NO_LIMIT;
            cb.sc_private = &maxcsn;
            cb.sc_response = findmax_cb;
            strcpy( cbuf, cf.f_av_value.bv_val );
            maxcsn.bv_val = cbuf;
            maxcsn.bv_len = cf.f_av_value.bv_len;
            break;
      case FIND_CSN:
            if ( BER_BVISEMPTY( &cf.f_av_value )) {
                  cf.f_av_value = srs->sr_state.ctxcsn[0];
                  /* If there are multiple CSNs, use the smallest */
                  for ( i=1; i<srs->sr_state.numcsns; i++ ) {
                        if ( ber_bvcmp( &cf.f_av_value, &srs->sr_state.ctxcsn[i] )
                              > 0 ) {
                              cf.f_av_value = srs->sr_state.ctxcsn[i];
                        }
                  }
            }
            /* Look for exact match the first time */
            if ( findcsn_retry ) {
                  cf.f_choice = LDAP_FILTER_EQUALITY;
                  fop.ors_filterstr.bv_len = snprintf( buf, sizeof( buf ),
                        "(entryCSN=%s)", cf.f_av_value.bv_val );
            /* On retry, look for <= */
            } else {
                  cf.f_choice = LDAP_FILTER_LE;
                  fop.ors_limit = &fc_limits;
                  memset( &fc_limits, 0, sizeof( fc_limits ));
                  fc_limits.lms_s_unchecked = 1;
                  fop.ors_filterstr.bv_len = snprintf( buf, sizeof( buf ),
                        "(entryCSN<=%s)", cf.f_av_value.bv_val );
            }
            if ( fop.ors_filterstr.bv_len < 0 || fop.ors_filterstr.bv_len >= sizeof( buf ) ) {
                  return LDAP_OTHER;
            }
            fop.ors_attrsonly = 1;
            fop.ors_attrs = slap_anlist_no_attrs;
            fop.ors_slimit = 1;
            cb.sc_private = NULL;
            cb.sc_response = findcsn_cb;
            break;
      case FIND_PRESENT:
            fop.ors_filter = op->ors_filter;
            fop.ors_filterstr = op->ors_filterstr;
            fop.ors_attrsonly = 0;
            fop.ors_attrs = uuid_anlist;
            fop.ors_slimit = SLAP_NO_LIMIT;
            cb.sc_private = &pcookie;
            cb.sc_response = findpres_cb;
            pcookie.num = 0;

            /* preallocate storage for a full set */
            pcookie.uuids = op->o_tmpalloc( (SLAP_SYNCUUID_SET_SIZE+1) *
                  sizeof(struct berval) + SLAP_SYNCUUID_SET_SIZE * UUID_LEN,
                  op->o_tmpmemctx );
            pcookie.last = (char *)(pcookie.uuids + SLAP_SYNCUUID_SET_SIZE+1);
            pcookie.uuids[0].bv_val = pcookie.last;
            pcookie.uuids[0].bv_len = UUID_LEN;
            for (i=1; i<SLAP_SYNCUUID_SET_SIZE; i++) {
                  pcookie.uuids[i].bv_val = pcookie.uuids[i-1].bv_val + UUID_LEN;
                  pcookie.uuids[i].bv_len = UUID_LEN;
            }
            break;
      }

      fop.o_bd->bd_info = (BackendInfo *)on->on_info;
      fop.o_bd->be_search( &fop, &frs );
      fop.o_bd->bd_info = (BackendInfo *)on;

      switch( mode ) {
      case FIND_MAXCSN:
            if ( ber_bvcmp( &si->si_ctxcsn[maxid], &maxcsn )) {
                  ber_bvreplace( &si->si_ctxcsn[maxid], &maxcsn );
                  si->si_numops++;  /* ensure a checkpoint */
            }
            break;
      case FIND_CSN:
            /* If matching CSN was not found, invalidate the context. */
            if ( !cb.sc_private ) {
                  /* If we didn't find an exact match, then try for <= */
                  if ( findcsn_retry ) {
                        findcsn_retry = 0;
                        goto again;
                  }
                  rc = LDAP_NO_SUCH_OBJECT;
            }
            break;
      case FIND_PRESENT:
            op->o_tmpfree( pcookie.uuids, op->o_tmpmemctx );
            break;
      }

      return rc;
}

static void
syncprov_free_syncop( syncops *so )
{
      syncres *sr, *srnext;
      GroupAssertion *ga, *gnext;

      ldap_pvt_thread_mutex_lock( &so->s_mutex );
      if ( --so->s_inuse > 0 ) {
            ldap_pvt_thread_mutex_unlock( &so->s_mutex );
            return;
      }
      if ( so->s_qtask ) {
            ldap_pvt_thread_mutex_lock( &slapd_rq.rq_mutex );
            if ( ldap_pvt_runqueue_isrunning( &slapd_rq, so->s_qtask ) )
                  ldap_pvt_runqueue_stoptask( &slapd_rq, so->s_qtask );
            ldap_pvt_runqueue_remove( &slapd_rq, so->s_qtask );
            ldap_pvt_thread_mutex_unlock( &slapd_rq.rq_mutex );
      }
      ldap_pvt_thread_mutex_unlock( &so->s_mutex );
      if ( so->s_flags & PS_IS_DETACHED ) {
            filter_free( so->s_op->ors_filter );
            for ( ga = so->s_op->o_groups; ga; ga=gnext ) {
                  gnext = ga->ga_next;
                  ch_free( ga );
            }
            ch_free( so->s_op );
      }
      ch_free( so->s_base.bv_val );
      for ( sr=so->s_res; sr; sr=srnext ) {
            srnext = sr->s_next;
            ch_free( sr );
      }
      ldap_pvt_thread_mutex_destroy( &so->s_mutex );
      ch_free( so );
}

/* Send a persistent search response */
static int
syncprov_sendresp( Operation *op, opcookie *opc, syncops *so,
      Entry **e, int mode )
{
      slap_overinst *on = opc->son;

      SlapReply rs = { REP_SEARCH };
      LDAPControl *ctrls[2];
      struct berval cookie, csns[2];
      Entry e_uuid = {0};
      Attribute a_uuid = {0};

      if ( so->s_op->o_abandon )
            return SLAPD_ABANDON;

      ctrls[1] = NULL;
      csns[0] = opc->sctxcsn;
      BER_BVZERO( &csns[1] );
      slap_compose_sync_cookie( op, &cookie, csns, so->s_rid, so->s_sid );

      Debug( LDAP_DEBUG_SYNC, "syncprov_sendresp: cookie=%s\n", cookie.bv_val, 0, 0 );

      e_uuid.e_attrs = &a_uuid;
      a_uuid.a_desc = slap_schema.si_ad_entryUUID;
      a_uuid.a_nvals = &opc->suuid;
      rs.sr_err = syncprov_state_ctrl( op, &rs, &e_uuid,
            mode, ctrls, 0, 1, &cookie );
      op->o_tmpfree( cookie.bv_val, op->o_tmpmemctx );

      rs.sr_ctrls = ctrls;
      op->o_bd->bd_info = (BackendInfo *)on->on_info;
      switch( mode ) {
      case LDAP_SYNC_ADD:
            rs.sr_entry = *e;
            if ( rs.sr_entry->e_private )
                  rs.sr_flags = REP_ENTRY_MUSTRELEASE;
            if ( opc->sreference ) {
                  rs.sr_ref = get_entry_referrals( op, rs.sr_entry );
                  rs.sr_err = send_search_reference( op, &rs );
                  ber_bvarray_free( rs.sr_ref );
                  if ( !rs.sr_entry )
                        *e = NULL;
                  break;
            }
            /* fallthru */
      case LDAP_SYNC_MODIFY:
            rs.sr_entry = *e;
            if ( rs.sr_entry->e_private )
                  rs.sr_flags = REP_ENTRY_MUSTRELEASE;
            rs.sr_attrs = op->ors_attrs;
            rs.sr_err = send_search_entry( op, &rs );
            if ( !rs.sr_entry )
                  *e = NULL;
            break;
      case LDAP_SYNC_DELETE:
            e_uuid.e_attrs = NULL;
            e_uuid.e_name = opc->sdn;
            e_uuid.e_nname = opc->sndn;
            rs.sr_entry = &e_uuid;
            if ( opc->sreference ) {
                  struct berval bv = BER_BVNULL;
                  rs.sr_ref = &bv;
                  rs.sr_err = send_search_reference( op, &rs );
            } else {
                  rs.sr_err = send_search_entry( op, &rs );
            }
            break;
      default:
            assert(0);
      }
      /* In case someone else freed it already? */
      if ( rs.sr_ctrls ) {
            op->o_tmpfree( rs.sr_ctrls[0], op->o_tmpmemctx );
            rs.sr_ctrls = NULL;
      }

      return rs.sr_err;
}

/* Play back queued responses */
static int
syncprov_qplay( Operation *op, struct re_s *rtask )
{
      syncops *so = rtask->arg;
      slap_overinst *on = LDAP_SLIST_FIRST(&so->s_op->o_extra)->oe_key;
      syncres *sr;
      Entry *e;
      opcookie opc;
      int rc = 0;

      opc.son = on;

      for (;;) {
            ldap_pvt_thread_mutex_lock( &so->s_mutex );
            sr = so->s_res;
            if ( sr )
                  so->s_res = sr->s_next;
            if ( !so->s_res )
                  so->s_restail = NULL;
            /* Exit loop with mutex held */
            if ( !sr || so->s_op->o_abandon )
                  break;
            ldap_pvt_thread_mutex_unlock( &so->s_mutex );

            opc.sdn = sr->s_dn;
            opc.sndn = sr->s_ndn;
            opc.suuid = sr->s_uuid;
            opc.sctxcsn = sr->s_csn;
            opc.sreference = sr->s_isreference;
            e = NULL;

            if ( sr->s_mode != LDAP_SYNC_DELETE ) {
                  rc = overlay_entry_get_ov( op, &opc.sndn, NULL, NULL, 0, &e, on );
                  if ( rc ) {
                        Debug( LDAP_DEBUG_SYNC, "syncprov_qplay: failed to get %s, "
                              "error (%d), ignoring...\n", opc.sndn.bv_val, rc, 0 );
                        ch_free( sr );
                        rc = 0;
                        continue;
                  }
            }
            rc = syncprov_sendresp( op, &opc, so, &e, sr->s_mode );

            if ( e ) {
                  overlay_entry_release_ov( op, e, 0, on );
            }

            ch_free( sr );

            if ( rc ) {
                  /* Exit loop with mutex held */
                  ldap_pvt_thread_mutex_lock( &so->s_mutex );
                  break;
            }
      }

      /* wait until we get explicitly scheduled again */
      ldap_pvt_thread_mutex_lock( &slapd_rq.rq_mutex );
      ldap_pvt_runqueue_stoptask( &slapd_rq, rtask );
      if ( rc == 0 ) {
            ldap_pvt_runqueue_resched( &slapd_rq, rtask, 1 );
      } else {
            /* bail out on any error */
            ldap_pvt_runqueue_remove( &slapd_rq, rtask );
      }
      ldap_pvt_thread_mutex_unlock( &slapd_rq.rq_mutex );
      ldap_pvt_thread_mutex_unlock( &so->s_mutex );
      return rc;
}

/* runqueue task for playing back queued responses */
static void *
syncprov_qtask( void *ctx, void *arg )
{
      struct re_s *rtask = arg;
      syncops *so = rtask->arg;
      OperationBuffer opbuf;
      Operation *op;
      BackendDB be;
      int rc;

      op = &opbuf.ob_op;
      *op = *so->s_op;
      op->o_hdr = &opbuf.ob_hdr;
      op->o_controls = opbuf.ob_controls;
      memset( op->o_controls, 0, sizeof(opbuf.ob_controls) );

      *op->o_hdr = *so->s_op->o_hdr;

      op->o_tmpmemctx = slap_sl_mem_create(SLAP_SLAB_SIZE, SLAP_SLAB_STACK, ctx, 1);
      op->o_tmpmfuncs = &slap_sl_mfuncs;
      op->o_threadctx = ctx;

      /* syncprov_qplay expects a fake db */
      be = *so->s_op->o_bd;
      be.be_flags |= SLAP_DBFLAG_OVERLAY;
      op->o_bd = &be;
      LDAP_SLIST_FIRST(&op->o_extra) = NULL;
      op->o_callback = NULL;

      rc = syncprov_qplay( op, rtask );

      /* decrement use count... */
      syncprov_free_syncop( so );

#if 0 /* FIXME: connection_close isn't exported from slapd.
             * should it be?
             */
      if ( rc ) {
            ldap_pvt_thread_mutex_lock( &op->o_conn->c_mutex );
            if ( connection_state_closing( op->o_conn )) {
                  connection_close( op->o_conn );
            }
            ldap_pvt_thread_mutex_unlock( &op->o_conn->c_mutex );
      }
#endif
      return NULL;
}

/* Start the task to play back queued psearch responses */
static void
syncprov_qstart( syncops *so )
{
      int wake=0;
      ldap_pvt_thread_mutex_lock( &slapd_rq.rq_mutex );
      if ( !so->s_qtask ) {
            so->s_qtask = ldap_pvt_runqueue_insert( &slapd_rq, RUNQ_INTERVAL,
                  syncprov_qtask, so, "syncprov_qtask",
                  so->s_op->o_conn->c_peer_name.bv_val );
            ++so->s_inuse;
            wake = 1;
      } else {
            if (!ldap_pvt_runqueue_isrunning( &slapd_rq, so->s_qtask ) &&
                  !so->s_qtask->next_sched.tv_sec ) {
                  so->s_qtask->interval.tv_sec = 0;
                  ldap_pvt_runqueue_resched( &slapd_rq, so->s_qtask, 0 );
                  so->s_qtask->interval.tv_sec = RUNQ_INTERVAL;
                  ++so->s_inuse;
                  wake = 1;
            }
      }
      ldap_pvt_thread_mutex_unlock( &slapd_rq.rq_mutex );
      if ( wake )
            slap_wake_listener();
}

/* Queue a persistent search response */
static int
syncprov_qresp( opcookie *opc, syncops *so, int mode )
{
      syncres *sr;
      int sid, srsize;

      /* Don't send changes back to their originator */
      sid = slap_parse_csn_sid( &opc->sctxcsn );
      if ( sid >= 0 && sid == so->s_sid )
            return LDAP_SUCCESS;

      srsize = sizeof(syncres) + opc->suuid.bv_len + 1 +
            opc->sdn.bv_len + 1 + opc->sndn.bv_len + 1;
      if ( opc->sctxcsn.bv_len )
            srsize += opc->sctxcsn.bv_len + 1;
      sr = ch_malloc( srsize );
      sr->s_next = NULL;
      sr->s_dn.bv_val = (char *)(sr + 1);
      sr->s_dn.bv_len = opc->sdn.bv_len;
      sr->s_mode = mode;
      sr->s_isreference = opc->sreference;
      sr->s_ndn.bv_val = lutil_strcopy( sr->s_dn.bv_val,
             opc->sdn.bv_val ) + 1;
      sr->s_ndn.bv_len = opc->sndn.bv_len;
      sr->s_uuid.bv_val = lutil_strcopy( sr->s_ndn.bv_val,
             opc->sndn.bv_val ) + 1;
      sr->s_uuid.bv_len = opc->suuid.bv_len;
      AC_MEMCPY( sr->s_uuid.bv_val, opc->suuid.bv_val, opc->suuid.bv_len );
      if ( opc->sctxcsn.bv_len ) {
            sr->s_csn.bv_val = sr->s_uuid.bv_val + sr->s_uuid.bv_len + 1;
            strcpy( sr->s_csn.bv_val, opc->sctxcsn.bv_val );
      } else {
            sr->s_csn.bv_val = NULL;
      }
      sr->s_csn.bv_len = opc->sctxcsn.bv_len;

      ldap_pvt_thread_mutex_lock( &so->s_mutex );
      if ( !so->s_res ) {
            so->s_res = sr;
      } else {
            so->s_restail->s_next = sr;
      }
      so->s_restail = sr;

      /* If the base of the psearch was modified, check it next time round */
      if ( so->s_flags & PS_WROTE_BASE ) {
            so->s_flags ^= PS_WROTE_BASE;
            so->s_flags |= PS_FIND_BASE;
      }
      if ( so->s_flags & PS_IS_DETACHED ) {
            syncprov_qstart( so );
      }
      ldap_pvt_thread_mutex_unlock( &so->s_mutex );
      return LDAP_SUCCESS;
}

static int
syncprov_drop_psearch( syncops *so, int lock )
{
      if ( so->s_flags & PS_IS_DETACHED ) {
            if ( lock )
                  ldap_pvt_thread_mutex_lock( &so->s_op->o_conn->c_mutex );
            so->s_op->o_conn->c_n_ops_executing--;
            so->s_op->o_conn->c_n_ops_completed++;
            LDAP_STAILQ_REMOVE( &so->s_op->o_conn->c_ops, so->s_op, Operation,
                  o_next );
            if ( lock )
                  ldap_pvt_thread_mutex_unlock( &so->s_op->o_conn->c_mutex );
      }
      syncprov_free_syncop( so );

      return 0;
}

static int
syncprov_ab_cleanup( Operation *op, SlapReply *rs )
{
      slap_callback *sc = op->o_callback;
      op->o_callback = sc->sc_next;
      syncprov_drop_psearch( op->o_callback->sc_private, 0 );
      op->o_tmpfree( sc, op->o_tmpmemctx );
      return 0;
}

static int
syncprov_op_abandon( Operation *op, SlapReply *rs )
{
      slap_overinst           *on = (slap_overinst *)op->o_bd->bd_info;
      syncprov_info_t         *si = on->on_bi.bi_private;
      syncops *so, *soprev;

      ldap_pvt_thread_mutex_lock( &si->si_ops_mutex );
      for ( so=si->si_ops, soprev = (syncops *)&si->si_ops; so;
            soprev=so, so=so->s_next ) {
            if ( so->s_op->o_connid == op->o_connid &&
                  so->s_op->o_msgid == op->orn_msgid ) {
                        so->s_op->o_abandon = 1;
                        soprev->s_next = so->s_next;
                        break;
            }
      }
      ldap_pvt_thread_mutex_unlock( &si->si_ops_mutex );
      if ( so ) {
            /* Is this really a Cancel exop? */
            if ( op->o_tag != LDAP_REQ_ABANDON ) {
                  so->s_op->o_cancel = SLAP_CANCEL_ACK;
                  rs->sr_err = LDAP_CANCELLED;
                  send_ldap_result( so->s_op, rs );
                  if ( so->s_flags & PS_IS_DETACHED ) {
                        slap_callback *cb;
                        cb = op->o_tmpcalloc( 1, sizeof(slap_callback), op->o_tmpmemctx );
                        cb->sc_cleanup = syncprov_ab_cleanup;
                        cb->sc_next = op->o_callback;
                        cb->sc_private = so;
                        return SLAP_CB_CONTINUE;
                  }
            }
            syncprov_drop_psearch( so, 0 );
      }
      return SLAP_CB_CONTINUE;
}

/* Find which persistent searches are affected by this operation */
static void
syncprov_matchops( Operation *op, opcookie *opc, int saveit )
{
      slap_overinst *on = opc->son;
      syncprov_info_t         *si = on->on_bi.bi_private;

      fbase_cookie fc;
      syncops *ss, *sprev, *snext;
      Entry *e = NULL;
      Attribute *a;
      int rc;
      struct berval newdn;
      int freefdn = 0;
      BackendDB *b0 = op->o_bd, db;

      fc.fdn = &op->o_req_ndn;
      /* compute new DN */
      if ( op->o_tag == LDAP_REQ_MODRDN && !saveit ) {
            struct berval pdn;
            if ( op->orr_nnewSup ) pdn = *op->orr_nnewSup;
            else dnParent( fc.fdn, &pdn );
            build_new_dn( &newdn, &pdn, &op->orr_nnewrdn, op->o_tmpmemctx );
            fc.fdn = &newdn;
            freefdn = 1;
      }
      if ( op->o_tag != LDAP_REQ_ADD ) {
            if ( !SLAP_ISOVERLAY( op->o_bd )) {
                  db = *op->o_bd;
                  op->o_bd = &db;
            }
            rc = overlay_entry_get_ov( op, fc.fdn, NULL, NULL, 0, &e, on );
            /* If we're sending responses now, make a copy and unlock the DB */
            if ( e && !saveit ) {
                  Entry *e2 = entry_dup( e );
                  overlay_entry_release_ov( op, e, 0, on );
                  e = e2;
            }
            if ( rc ) {
                  op->o_bd = b0;
                  return;
            }
      } else {
            e = op->ora_e;
      }

      if ( saveit || op->o_tag == LDAP_REQ_ADD ) {
            ber_dupbv_x( &opc->sdn, &e->e_name, op->o_tmpmemctx );
            ber_dupbv_x( &opc->sndn, &e->e_nname, op->o_tmpmemctx );
            opc->sreference = is_entry_referral( e );
            a = attr_find( e->e_attrs, slap_schema.si_ad_entryUUID );
            if ( a )
                  ber_dupbv_x( &opc->suuid, &a->a_nvals[0], op->o_tmpmemctx );
      } else if ( op->o_tag == LDAP_REQ_MODRDN && !saveit ) {
            op->o_tmpfree( opc->sndn.bv_val, op->o_tmpmemctx );
            op->o_tmpfree( opc->sdn.bv_val, op->o_tmpmemctx );
            ber_dupbv_x( &opc->sdn, &e->e_name, op->o_tmpmemctx );
            ber_dupbv_x( &opc->sndn, &e->e_nname, op->o_tmpmemctx );
      }

      ldap_pvt_thread_mutex_lock( &si->si_ops_mutex );
      for (ss = si->si_ops, sprev = (syncops *)&si->si_ops; ss;
            sprev = ss, ss=snext)
      {
            Operation op2;
            syncmatches *sm;
            int found = 0;

            snext = ss->s_next;
            if ( ss->s_op->o_abandon )
                  continue;

            /* validate base */
            fc.fss = ss;
            fc.fbase = 0;
            fc.fscope = 0;

            /* If the base of the search is missing, signal a refresh */
            rc = syncprov_findbase( op, &fc );
            if ( rc != LDAP_SUCCESS ) {
                  SlapReply rs = {REP_RESULT};
                  send_ldap_error( ss->s_op, &rs, LDAP_SYNC_REFRESH_REQUIRED,
                        "search base has changed" );
                  sprev->s_next = snext;
                  syncprov_drop_psearch( ss, 1 );
                  ss = sprev;
                  continue;
            }


            /* If we're sending results now, look for this op in old matches */
            if ( !saveit ) {
                  syncmatches *old;

                  /* Did we modify the search base? */
                  if ( dn_match( &op->o_req_ndn, &ss->s_base )) {
                        ldap_pvt_thread_mutex_lock( &ss->s_mutex );
                        ss->s_flags |= PS_WROTE_BASE;
                        ldap_pvt_thread_mutex_unlock( &ss->s_mutex );
                  }

                  for ( sm=opc->smatches, old=(syncmatches *)&opc->smatches; sm;
                        old=sm, sm=sm->sm_next ) {
                        if ( sm->sm_op == ss ) {
                              found = 1;
                              old->sm_next = sm->sm_next;
                              op->o_tmpfree( sm, op->o_tmpmemctx );
                              break;
                        }
                  }
            }

            if ( fc.fscope ) {
                  op2 = *ss->s_op;
                  op2.o_hdr = op->o_hdr;
                  op2.o_extra = op->o_extra;
            }

            /* check if current o_req_dn is in scope and matches filter */
            if ( fc.fscope && test_filter( &op2, e, ss->s_op->ors_filter ) ==
                  LDAP_COMPARE_TRUE ) {
                  if ( saveit ) {
                        sm = op->o_tmpalloc( sizeof(syncmatches), op->o_tmpmemctx );
                        sm->sm_next = opc->smatches;
                        sm->sm_op = ss;
                        ldap_pvt_thread_mutex_lock( &ss->s_mutex );
                        ++ss->s_inuse;
                        ldap_pvt_thread_mutex_unlock( &ss->s_mutex );
                        opc->smatches = sm;
                  } else {
                        /* if found send UPDATE else send ADD */
                        syncprov_qresp( opc, ss,
                              found ? LDAP_SYNC_MODIFY : LDAP_SYNC_ADD );
                  }
            } else if ( !saveit && found ) {
                  /* send DELETE */
                  syncprov_qresp( opc, ss, LDAP_SYNC_DELETE );
            }
      }
      ldap_pvt_thread_mutex_unlock( &si->si_ops_mutex );

      if ( op->o_tag != LDAP_REQ_ADD && e ) {
            if ( !SLAP_ISOVERLAY( op->o_bd )) {
                  op->o_bd = &db;
            }
            overlay_entry_release_ov( op, e, 0, on );
            op->o_bd = b0;
      }
      if ( freefdn ) {
            op->o_tmpfree( fc.fdn->bv_val, op->o_tmpmemctx );
      }
      op->o_bd = b0;
}

static int
syncprov_op_cleanup( Operation *op, SlapReply *rs )
{
      slap_callback *cb = op->o_callback;
      opcookie *opc = cb->sc_private;
      slap_overinst *on = opc->son;
      syncprov_info_t         *si = on->on_bi.bi_private;
      syncmatches *sm, *snext;
      modtarget *mt, mtdummy;

      for (sm = opc->smatches; sm; sm=snext) {
            snext = sm->sm_next;
            syncprov_free_syncop( sm->sm_op );
            op->o_tmpfree( sm, op->o_tmpmemctx );
      }

      /* Remove op from lock table */
      mtdummy.mt_op = op;
      ldap_pvt_thread_mutex_lock( &si->si_mods_mutex );
      mt = avl_find( si->si_mods, &mtdummy, sp_avl_cmp );
      if ( mt ) {
            modinst *mi = mt->mt_mods;

            /* If there are more, promote the next one */
            ldap_pvt_thread_mutex_lock( &mt->mt_mutex );
            if ( mi->mi_next ) {
                  mt->mt_mods = mi->mi_next;
                  mt->mt_op = mt->mt_mods->mi_op;
                  ldap_pvt_thread_mutex_unlock( &mt->mt_mutex );
            } else {
                  avl_delete( &si->si_mods, mt, sp_avl_cmp );
                  ldap_pvt_thread_mutex_unlock( &mt->mt_mutex );
                  ldap_pvt_thread_mutex_destroy( &mt->mt_mutex );
                  ch_free( mt );
            }
      }
      ldap_pvt_thread_mutex_unlock( &si->si_mods_mutex );
      if ( !BER_BVISNULL( &opc->suuid ))
            op->o_tmpfree( opc->suuid.bv_val, op->o_tmpmemctx );
      if ( !BER_BVISNULL( &opc->sndn ))
            op->o_tmpfree( opc->sndn.bv_val, op->o_tmpmemctx );
      if ( !BER_BVISNULL( &opc->sdn ))
            op->o_tmpfree( opc->sdn.bv_val, op->o_tmpmemctx );
      op->o_callback = cb->sc_next;
      op->o_tmpfree(cb, op->o_tmpmemctx);

      return 0;
}

static void
syncprov_checkpoint( Operation *op, SlapReply *rs, slap_overinst *on )
{
      syncprov_info_t *si = (syncprov_info_t *)on->on_bi.bi_private;
      Modifications mod;
      Operation opm;
      SlapReply rsm = { 0 };
      slap_callback cb = {0};
      BackendDB be;

      mod.sml_numvals = si->si_numcsns;
      mod.sml_values = si->si_ctxcsn;
      mod.sml_nvalues = NULL;
      mod.sml_desc = slap_schema.si_ad_contextCSN;
      mod.sml_op = LDAP_MOD_REPLACE;
      mod.sml_flags = 0;
      mod.sml_next = NULL;

      cb.sc_response = slap_null_cb;
      opm = *op;
      opm.o_tag = LDAP_REQ_MODIFY;
      opm.o_callback = &cb;
      opm.orm_modlist = &mod;
      opm.orm_no_opattrs = 1;
      if ( SLAP_GLUE_SUBORDINATE( op->o_bd )) {
            be = *on->on_info->oi_origdb;
            opm.o_bd = &be;
      }
      opm.o_req_dn = opm.o_bd->be_suffix[0];
      opm.o_req_ndn = opm.o_bd->be_nsuffix[0];
      opm.o_bd->bd_info = on->on_info->oi_orig;
      opm.o_managedsait = SLAP_CONTROL_NONCRITICAL;
      opm.o_no_schema_check = 1;
      opm.o_bd->be_modify( &opm, &rsm );
      if ( mod.sml_next != NULL ) {
            slap_mods_free( mod.sml_next, 1 );
      }
}

static void
syncprov_add_slog( Operation *op )
{
      opcookie *opc = op->o_callback->sc_private;
      slap_overinst *on = opc->son;
      syncprov_info_t         *si = on->on_bi.bi_private;
      sessionlog *sl;
      slog_entry *se;

      sl = si->si_logs;
      {
            /* Allocate a record. UUIDs are not NUL-terminated. */
            se = ch_malloc( sizeof( slog_entry ) + opc->suuid.bv_len + 
                  op->o_csn.bv_len + 1 );
            se->se_next = NULL;
            se->se_tag = op->o_tag;

            se->se_uuid.bv_val = (char *)(&se[1]);
            AC_MEMCPY( se->se_uuid.bv_val, opc->suuid.bv_val, opc->suuid.bv_len );
            se->se_uuid.bv_len = opc->suuid.bv_len;

            se->se_csn.bv_val = se->se_uuid.bv_val + opc->suuid.bv_len;
            AC_MEMCPY( se->se_csn.bv_val, op->o_csn.bv_val, op->o_csn.bv_len );
            se->se_csn.bv_val[op->o_csn.bv_len] = '\0';
            se->se_csn.bv_len = op->o_csn.bv_len;
            se->se_sid = slap_parse_csn_sid( &se->se_csn );

            ldap_pvt_thread_mutex_lock( &sl->sl_mutex );
            if ( sl->sl_head ) {
                  sl->sl_tail->se_next = se;
            } else {
                  sl->sl_head = se;
            }
            sl->sl_tail = se;
            sl->sl_num++;
            while ( sl->sl_num > sl->sl_size ) {
                  se = sl->sl_head;
                  sl->sl_head = se->se_next;
                  strcpy( sl->sl_mincsn.bv_val, se->se_csn.bv_val );
                  sl->sl_mincsn.bv_len = se->se_csn.bv_len;
                  ch_free( se );
                  sl->sl_num--;
            }
            ldap_pvt_thread_mutex_unlock( &sl->sl_mutex );
      }
}

/* Just set a flag if we found the matching entry */
static int
playlog_cb( Operation *op, SlapReply *rs )
{
      if ( rs->sr_type == REP_SEARCH ) {
            op->o_callback->sc_private = (void *)1;
      }
      return rs->sr_err;
}

/* enter with sl->sl_mutex locked, release before returning */
static void
syncprov_playlog( Operation *op, SlapReply *rs, sessionlog *sl,
      sync_control *srs, BerVarray ctxcsn, int numcsns, int *sids )
{
      slap_overinst           *on = (slap_overinst *)op->o_bd->bd_info;
      slog_entry *se;
      int i, j, ndel, num, nmods, mmods;
      char cbuf[LDAP_LUTIL_CSNSTR_BUFSIZE];
      BerVarray uuids;
      struct berval delcsn[2];

      if ( !sl->sl_num ) {
            ldap_pvt_thread_mutex_unlock( &sl->sl_mutex );
            return;
      }

      num = sl->sl_num;
      i = 0;
      nmods = 0;

      uuids = op->o_tmpalloc( (num+1) * sizeof( struct berval ) +
            num * UUID_LEN, op->o_tmpmemctx );
      uuids[0].bv_val = (char *)(uuids + num + 1);

      delcsn[0].bv_len = 0;
      delcsn[0].bv_val = cbuf;
      BER_BVZERO(&delcsn[1]);

      /* Make a copy of the relevant UUIDs. Put the Deletes up front
       * and everything else at the end. Do this first so we can
       * unlock the list mutex.
       */
      Debug( LDAP_DEBUG_SYNC, "srs csn %s\n",
            srs->sr_state.ctxcsn[0].bv_val, 0, 0 );
      for ( se=sl->sl_head; se; se=se->se_next ) {
            int k;
            Debug( LDAP_DEBUG_SYNC, "log csn %s\n", se->se_csn.bv_val, 0, 0 );
            ndel = 1;
            for ( k=0; k<srs->sr_state.numcsns; k++ ) {
                  if ( se->se_sid == srs->sr_state.sids[k] ) {
                        ndel = ber_bvcmp( &se->se_csn, &srs->sr_state.ctxcsn[k] );
                        break;
                  }
            }
            if ( ndel <= 0 ) {
                  Debug( LDAP_DEBUG_SYNC, "cmp %d, too old\n", ndel, 0, 0 );
                  continue;
            }
            ndel = 0;
            for ( k=0; k<numcsns; k++ ) {
                  if ( se->se_sid == sids[k] ) {
                        ndel = ber_bvcmp( &se->se_csn, &ctxcsn[k] );
                        break;
                  }
            }
            if ( ndel > 0 ) {
                  Debug( LDAP_DEBUG_SYNC, "cmp %d, too new\n", ndel, 0, 0 );
                  break;
            }
            if ( se->se_tag == LDAP_REQ_DELETE ) {
                  j = i;
                  i++;
                  AC_MEMCPY( cbuf, se->se_csn.bv_val, se->se_csn.bv_len );
                  delcsn[0].bv_len = se->se_csn.bv_len;
                  delcsn[0].bv_val[delcsn[0].bv_len] = '\0';
            } else {
                  nmods++;
                  j = num - nmods;
            }
            uuids[j].bv_val = uuids[0].bv_val + (j * UUID_LEN);
            AC_MEMCPY(uuids[j].bv_val, se->se_uuid.bv_val, UUID_LEN);
            uuids[j].bv_len = UUID_LEN;
      }
      ldap_pvt_thread_mutex_unlock( &sl->sl_mutex );

      ndel = i;

      /* Zero out unused slots */
      for ( i=ndel; i < num - nmods; i++ )
            uuids[i].bv_len = 0;

      /* Mods must be validated to see if they belong in this delete set.
       */

      mmods = nmods;
      /* Strip any duplicates */
      for ( i=0; i<nmods; i++ ) {
            for ( j=0; j<ndel; j++ ) {
                  if ( bvmatch( &uuids[j], &uuids[num - 1 - i] )) {
                        uuids[num - 1 - i].bv_len = 0;
                        mmods --;
                        break;
                  }
            }
            if ( uuids[num - 1 - i].bv_len == 0 ) continue;
            for ( j=0; j<i; j++ ) {
                  if ( bvmatch( &uuids[num - 1 - j], &uuids[num - 1 - i] )) {
                        uuids[num - 1 - i].bv_len = 0;
                        mmods --;
                        break;
                  }
            }
      }

      if ( mmods ) {
            Operation fop;
            SlapReply frs = { REP_RESULT };
            int rc;
            Filter mf, af;
            AttributeAssertion eq = ATTRIBUTEASSERTION_INIT;
            slap_callback cb = {0};

            fop = *op;

            fop.o_sync_mode = 0;
            fop.o_callback = &cb;
            fop.ors_limit = NULL;
            fop.ors_tlimit = SLAP_NO_LIMIT;
            fop.ors_attrs = slap_anlist_all_attributes;
            fop.ors_attrsonly = 0;
            fop.o_managedsait = SLAP_CONTROL_CRITICAL;

            af.f_choice = LDAP_FILTER_AND;
            af.f_next = NULL;
            af.f_and = &mf;
            mf.f_choice = LDAP_FILTER_EQUALITY;
            mf.f_ava = &eq;
            mf.f_av_desc = slap_schema.si_ad_entryUUID;
            mf.f_next = fop.ors_filter;

            fop.ors_filter = &af;

            cb.sc_response = playlog_cb;
            fop.o_bd->bd_info = (BackendInfo *)on->on_info;

            for ( i=ndel; i<num; i++ ) {
                  if ( uuids[i].bv_len == 0 ) continue;

                  mf.f_av_value = uuids[i];
                  cb.sc_private = NULL;
                  fop.ors_slimit = 1;
                  frs.sr_nentries = 0;
                  rc = fop.o_bd->be_search( &fop, &frs );

                  /* If entry was not found, add to delete list */
                  if ( !cb.sc_private ) {
                        uuids[ndel++] = uuids[i];
                  }
            }
            fop.o_bd->bd_info = (BackendInfo *)on;
      }
      if ( ndel ) {
            struct berval cookie;

            if ( delcsn[0].bv_len ) {
                  slap_compose_sync_cookie( op, &cookie, delcsn, srs->sr_state.rid,
                        srs->sr_state.sid );
            }

            Debug( LDAP_DEBUG_SYNC, "syncprov_playlog: cookie=%s\n", cookie.bv_val, 0, 0 );

            uuids[ndel].bv_val = NULL;
            syncprov_sendinfo( op, rs, LDAP_TAG_SYNC_ID_SET,
                  delcsn[0].bv_len ? &cookie : NULL, 0, uuids, 1 );
            op->o_tmpfree( cookie.bv_val, op->o_tmpmemctx );
      }
      op->o_tmpfree( uuids, op->o_tmpmemctx );
}

static int
syncprov_op_response( Operation *op, SlapReply *rs )
{
      opcookie *opc = op->o_callback->sc_private;
      slap_overinst *on = opc->son;
      syncprov_info_t         *si = on->on_bi.bi_private;
      syncmatches *sm;

      if ( rs->sr_err == LDAP_SUCCESS )
      {
            struct berval maxcsn = BER_BVNULL;
            char cbuf[LDAP_LUTIL_CSNSTR_BUFSIZE];
            int do_check = 0, have_psearches;

            /* Update our context CSN */
            cbuf[0] = '\0';
            ldap_pvt_thread_rdwr_wlock( &si->si_csn_rwlock );
            slap_get_commit_csn( op, &maxcsn );
            if ( BER_BVISNULL( &maxcsn ) && SLAP_GLUE_SUBORDINATE( op->o_bd )) {
                  /* syncrepl queues the CSN values in the db where
                   * it is configured , not where the changes are made.
                   * So look for a value in the glue db if we didn't
                   * find any in this db.
                   */
                  BackendDB *be = op->o_bd;
                  op->o_bd = select_backend( &be->be_nsuffix[0], 1);
                  slap_get_commit_csn( op, &maxcsn );
                  op->o_bd = be;
            }
            if ( !BER_BVISNULL( &maxcsn ) ) {
                  int i, sid;
                  strcpy( cbuf, maxcsn.bv_val );
                  sid = slap_parse_csn_sid( &maxcsn );
                  for ( i=0; i<si->si_numcsns; i++ ) {
                        if ( sid == si->si_sids[i] ) {
                              if ( ber_bvcmp( &maxcsn, &si->si_ctxcsn[i] ) > 0 ) {
                                    ber_bvreplace( &si->si_ctxcsn[i], &maxcsn );
                              }
                              break;
                        }
                  }
                  /* It's a new SID for us */
                  if ( i == si->si_numcsns ) {
                        value_add_one( &si->si_ctxcsn, &maxcsn );
                        si->si_numcsns++;
                        si->si_sids = ch_realloc( si->si_sids, si->si_numcsns *
                              sizeof(int));
                        si->si_sids[i] = sid;
                  }
            } else {
                  /* internal ops that aren't meant to be replicated */
                  ldap_pvt_thread_rdwr_wunlock( &si->si_csn_rwlock );
                  return SLAP_CB_CONTINUE;
            }

            /* Don't do any processing for consumer contextCSN updates */
            if ( SLAP_SYNC_SHADOW( op->o_bd ) && 
                  op->o_msgid == SLAP_SYNC_UPDATE_MSGID ) {
                  ldap_pvt_thread_rdwr_wunlock( &si->si_csn_rwlock );
                  return SLAP_CB_CONTINUE;
            }

            si->si_numops++;
            if ( si->si_chkops || si->si_chktime ) {
                  if ( si->si_chkops && si->si_numops >= si->si_chkops ) {
                        do_check = 1;
                        si->si_numops = 0;
                  }
                  if ( si->si_chktime &&
                        (op->o_time - si->si_chklast >= si->si_chktime )) {
                        if ( si->si_chklast ) {
                              do_check = 1;
                              si->si_chklast = op->o_time;
                        } else {
                              si->si_chklast = 1;
                        }
                  }
            }
            ldap_pvt_thread_rdwr_wunlock( &si->si_csn_rwlock );

            if ( do_check ) {
                  ldap_pvt_thread_rdwr_rlock( &si->si_csn_rwlock );
                  syncprov_checkpoint( op, rs, on );
                  ldap_pvt_thread_rdwr_runlock( &si->si_csn_rwlock );
            }

            opc->sctxcsn.bv_len = maxcsn.bv_len;
            opc->sctxcsn.bv_val = cbuf;

            /* Handle any persistent searches */
            ldap_pvt_thread_mutex_lock( &si->si_ops_mutex );
            have_psearches = ( si->si_ops != NULL );
            ldap_pvt_thread_mutex_unlock( &si->si_ops_mutex );
            if ( have_psearches ) {
                  switch(op->o_tag) {
                  case LDAP_REQ_ADD:
                  case LDAP_REQ_MODIFY:
                  case LDAP_REQ_MODRDN:
                  case LDAP_REQ_EXTENDED:
                        syncprov_matchops( op, opc, 0 );
                        break;
                  case LDAP_REQ_DELETE:
                        /* for each match in opc->smatches:
                         *   send DELETE msg
                         */
                        for ( sm = opc->smatches; sm; sm=sm->sm_next ) {
                              if ( sm->sm_op->s_op->o_abandon )
                                    continue;
                              syncprov_qresp( opc, sm->sm_op, LDAP_SYNC_DELETE );
                        }
                        break;
                  }
            }

            /* Add any log records */
            if ( si->si_logs && op->o_tag != LDAP_REQ_ADD ) {
                  syncprov_add_slog( op );
            }

      }
      return SLAP_CB_CONTINUE;
}

/* We don't use a subentry to store the context CSN any more.
 * We expose the current context CSN as an operational attribute
 * of the suffix entry.
 */
static int
syncprov_op_compare( Operation *op, SlapReply *rs )
{
      slap_overinst           *on = (slap_overinst *)op->o_bd->bd_info;
      syncprov_info_t         *si = on->on_bi.bi_private;
      int rc = SLAP_CB_CONTINUE;

      if ( dn_match( &op->o_req_ndn, op->o_bd->be_nsuffix ) &&
            op->oq_compare.rs_ava->aa_desc == slap_schema.si_ad_contextCSN )
      {
            Entry e = {0};
            Attribute a = {0};

            e.e_name = op->o_bd->be_suffix[0];
            e.e_nname = op->o_bd->be_nsuffix[0];
            e.e_attrs = &a;

            a.a_desc = slap_schema.si_ad_contextCSN;

            ldap_pvt_thread_rdwr_rlock( &si->si_csn_rwlock );

            a.a_vals = si->si_ctxcsn;
            a.a_nvals = a.a_vals;

            rs->sr_err = access_allowed( op, &e, op->oq_compare.rs_ava->aa_desc,
                  &op->oq_compare.rs_ava->aa_value, ACL_COMPARE, NULL );
            if ( ! rs->sr_err ) {
                  rs->sr_err = LDAP_INSUFFICIENT_ACCESS;
                  goto return_results;
            }

            if ( get_assert( op ) &&
                  ( test_filter( op, &e, get_assertion( op ) ) != LDAP_COMPARE_TRUE ) )
            {
                  rs->sr_err = LDAP_ASSERTION_FAILED;
                  goto return_results;
            }


            rs->sr_err = LDAP_COMPARE_FALSE;

            if ( attr_valfind( &a,
                  SLAP_MR_ATTRIBUTE_VALUE_NORMALIZED_MATCH |
                        SLAP_MR_ASSERTED_VALUE_NORMALIZED_MATCH,
                        &op->oq_compare.rs_ava->aa_value, NULL, op->o_tmpmemctx ) == 0 )
            {
                  rs->sr_err = LDAP_COMPARE_TRUE;
            }

return_results:;

            ldap_pvt_thread_rdwr_runlock( &si->si_csn_rwlock );

            send_ldap_result( op, rs );

            if( rs->sr_err == LDAP_COMPARE_FALSE || rs->sr_err == LDAP_COMPARE_TRUE ) {
                  rs->sr_err = LDAP_SUCCESS;
            }
            rc = rs->sr_err;
      }

      return rc;
}

static int
syncprov_op_mod( Operation *op, SlapReply *rs )
{
      slap_overinst           *on = (slap_overinst *)op->o_bd->bd_info;
      syncprov_info_t         *si = on->on_bi.bi_private;
      slap_callback *cb;
      opcookie *opc;
      int have_psearches, cbsize;

      ldap_pvt_thread_mutex_lock( &si->si_ops_mutex );
      have_psearches = ( si->si_ops != NULL );
      ldap_pvt_thread_mutex_unlock( &si->si_ops_mutex );

      cbsize = sizeof(slap_callback) + sizeof(opcookie) +
            (have_psearches ? sizeof(modinst) : 0 );

      cb = op->o_tmpcalloc(1, cbsize, op->o_tmpmemctx);
      opc = (opcookie *)(cb+1);
      opc->son = on;
      cb->sc_response = syncprov_op_response;
      cb->sc_cleanup = syncprov_op_cleanup;
      cb->sc_private = opc;
      cb->sc_next = op->o_callback;
      op->o_callback = cb;

      /* If there are active persistent searches, lock this operation.
       * See seqmod.c for the locking logic on its own.
       */
      if ( have_psearches ) {
            modtarget *mt, mtdummy;
            modinst *mi;

            mi = (modinst *)(opc+1);
            mi->mi_op = op;

            /* See if we're already modifying this entry... */
            mtdummy.mt_op = op;
            ldap_pvt_thread_mutex_lock( &si->si_mods_mutex );
            mt = avl_find( si->si_mods, &mtdummy, sp_avl_cmp );
            if ( mt ) {
                  ldap_pvt_thread_mutex_lock( &mt->mt_mutex );
                  ldap_pvt_thread_mutex_unlock( &si->si_mods_mutex );
                  mt->mt_tail->mi_next = mi;
                  mt->mt_tail = mi;
                  /* wait for this op to get to head of list */
                  while ( mt->mt_mods != mi ) {
                        ldap_pvt_thread_mutex_unlock( &mt->mt_mutex );
                        /* FIXME: if dynamic config can delete overlays or
                         * databases we'll have to check for cleanup here.
                         * Currently it's not an issue because there are
                         * no dynamic config deletes...
                         */
                        if ( !ldap_pvt_thread_pool_pausecheck( &connection_pool ))
                              ldap_pvt_thread_yield();
                        ldap_pvt_thread_mutex_lock( &mt->mt_mutex );

                        /* clean up if the caller is giving up */
                        if ( op->o_abandon ) {
                              modinst *m2;
                              for ( m2 = mt->mt_mods; m2->mi_next != mi;
                                    m2 = m2->mi_next );
                              m2->mi_next = mi->mi_next;
                              if ( mt->mt_tail == mi ) mt->mt_tail = m2;
                              op->o_tmpfree( cb, op->o_tmpmemctx );
                              ldap_pvt_thread_mutex_unlock( &mt->mt_mutex );
                              return SLAPD_ABANDON;
                        }
                  }
                  ldap_pvt_thread_mutex_unlock( &mt->mt_mutex );
            } else {
                  /* Record that we're modifying this entry now */
                  mt = ch_malloc( sizeof(modtarget) );
                  mt->mt_mods = mi;
                  mt->mt_tail = mi;
                  mt->mt_op = mi->mi_op;
                  ldap_pvt_thread_mutex_init( &mt->mt_mutex );
                  avl_insert( &si->si_mods, mt, sp_avl_cmp, avl_dup_error );
                  ldap_pvt_thread_mutex_unlock( &si->si_mods_mutex );
            }
      }

      if (( have_psearches || si->si_logs ) && op->o_tag != LDAP_REQ_ADD )
            syncprov_matchops( op, opc, 1 );

      return SLAP_CB_CONTINUE;
}

static int
syncprov_op_extended( Operation *op, SlapReply *rs )
{
      if ( exop_is_write( op ))
            return syncprov_op_mod( op, rs );

      return SLAP_CB_CONTINUE;
}

typedef struct searchstate {
      slap_overinst *ss_on;
      syncops *ss_so;
      BerVarray ss_ctxcsn;
      int *ss_sids;
      int ss_numcsns;
#define     SS_PRESENT  0x01
#define     SS_CHANGED  0x02
      int ss_flags;
} searchstate;

static int
syncprov_search_cleanup( Operation *op, SlapReply *rs )
{
      if ( rs->sr_ctrls ) {
            op->o_tmpfree( rs->sr_ctrls[0], op->o_tmpmemctx );
            op->o_tmpfree( rs->sr_ctrls, op->o_tmpmemctx );
            rs->sr_ctrls = NULL;
      }
      return 0;
}

typedef struct SyncOperationBuffer {
      Operation         sob_op;
      Opheader          sob_hdr;
      OpExtra                 sob_oe;
      AttributeName     sob_extra;  /* not always present */
      /* Further data allocated here */
} SyncOperationBuffer;

static void
syncprov_detach_op( Operation *op, syncops *so, slap_overinst *on )
{
      SyncOperationBuffer *sopbuf2;
      Operation *op2;
      int i, alen = 0;
      size_t size;
      char *ptr;
      GroupAssertion *g1, *g2;

      /* count the search attrs */
      for (i=0; op->ors_attrs && !BER_BVISNULL( &op->ors_attrs[i].an_name ); i++) {
            alen += op->ors_attrs[i].an_name.bv_len + 1;
      }
      /* Make a new copy of the operation */
      size = offsetof( SyncOperationBuffer, sob_extra ) +
            (i ? ( (i+1) * sizeof(AttributeName) + alen) : 0) +
            op->o_req_dn.bv_len + 1 +
            op->o_req_ndn.bv_len + 1 +
            op->o_ndn.bv_len + 1 +
            so->s_filterstr.bv_len + 1;
      sopbuf2 = ch_calloc( 1, size );
      op2 = &sopbuf2->sob_op;
      op2->o_hdr = &sopbuf2->sob_hdr;
      LDAP_SLIST_FIRST(&op2->o_extra) = &sopbuf2->sob_oe;

      /* Copy the fields we care about explicitly, leave the rest alone */
      *op2->o_hdr = *op->o_hdr;
      op2->o_tag = op->o_tag;
      op2->o_time = op->o_time;
      op2->o_bd = on->on_info->oi_origdb;
      op2->o_request = op->o_request;
      LDAP_SLIST_FIRST(&op2->o_extra)->oe_key = on;
      LDAP_SLIST_NEXT(LDAP_SLIST_FIRST(&op2->o_extra), oe_next) = NULL;

      ptr = (char *) sopbuf2 + offsetof( SyncOperationBuffer, sob_extra );
      if ( i ) {
            op2->ors_attrs = (AttributeName *) ptr;
            ptr = (char *) &op2->ors_attrs[i+1];
            for (i=0; !BER_BVISNULL( &op->ors_attrs[i].an_name ); i++) {
                  op2->ors_attrs[i] = op->ors_attrs[i];
                  op2->ors_attrs[i].an_name.bv_val = ptr;
                  ptr = lutil_strcopy( ptr, op->ors_attrs[i].an_name.bv_val ) + 1;
            }
            BER_BVZERO( &op2->ors_attrs[i].an_name );
      }

      op2->o_authz = op->o_authz;
      op2->o_ndn.bv_val = ptr;
      ptr = lutil_strcopy(ptr, op->o_ndn.bv_val) + 1;
      op2->o_dn = op2->o_ndn;
      op2->o_req_dn.bv_len = op->o_req_dn.bv_len;
      op2->o_req_dn.bv_val = ptr;
      ptr = lutil_strcopy(ptr, op->o_req_dn.bv_val) + 1;
      op2->o_req_ndn.bv_len = op->o_req_ndn.bv_len;
      op2->o_req_ndn.bv_val = ptr;
      ptr = lutil_strcopy(ptr, op->o_req_ndn.bv_val) + 1;
      op2->ors_filterstr.bv_val = ptr;
      strcpy( ptr, so->s_filterstr.bv_val );
      op2->ors_filterstr.bv_len = so->s_filterstr.bv_len;

      /* Skip the AND/GE clause that we stuck on in front */
      if ( so->s_flags & PS_FIX_FILTER ) {
            op2->ors_filter = op->ors_filter->f_and->f_next;
            so->s_flags ^= PS_FIX_FILTER;
      } else {
            op2->ors_filter = op->ors_filter;
      }
      op2->ors_filter = filter_dup( op2->ors_filter, NULL );
      so->s_op = op2;

      /* Copy any cached group ACLs individually */
      op2->o_groups = NULL;
      for ( g1=op->o_groups; g1; g1=g1->ga_next ) {
            g2 = ch_malloc( sizeof(GroupAssertion) + g1->ga_len );
            *g2 = *g1;
            strcpy( g2->ga_ndn, g1->ga_ndn );
            g2->ga_next = op2->o_groups;
            op2->o_groups = g2;
      }
      /* Don't allow any further group caching */
      op2->o_do_not_cache = 1;

      /* Add op2 to conn so abandon will find us */
      op->o_conn->c_n_ops_executing++;
      op->o_conn->c_n_ops_completed--;
      LDAP_STAILQ_INSERT_TAIL( &op->o_conn->c_ops, op2, o_next );
      so->s_flags |= PS_IS_DETACHED;

      /* Prevent anyone else from trying to send a result for this op */
      op->o_abandon = 1;
}

static int
syncprov_search_response( Operation *op, SlapReply *rs )
{
      searchstate *ss = op->o_callback->sc_private;
      slap_overinst *on = ss->ss_on;
      syncprov_info_t *si = (syncprov_info_t *)on->on_bi.bi_private;
      sync_control *srs = op->o_controls[slap_cids.sc_LDAPsync];

      if ( rs->sr_type == REP_SEARCH || rs->sr_type == REP_SEARCHREF ) {
            Attribute *a;
            /* If we got a referral without a referral object, there's
             * something missing that we cannot replicate. Just ignore it.
             * The consumer will abort because we didn't send the expected
             * control.
             */
            if ( !rs->sr_entry ) {
                  assert( rs->sr_entry != NULL );
                  Debug( LDAP_DEBUG_ANY, "bogus referral in context\n",0,0,0 );
                  return SLAP_CB_CONTINUE;
            }
            a = attr_find( rs->sr_entry->e_attrs, slap_schema.si_ad_entryCSN );
            if ( a == NULL && rs->sr_operational_attrs != NULL ) {
                  a = attr_find( rs->sr_operational_attrs, slap_schema.si_ad_entryCSN );
            }
            if ( a ) {
                  int i, sid;
                  sid = slap_parse_csn_sid( &a->a_nvals[0] );

                  /* Don't send changed entries back to the originator */
                  if ( sid == srs->sr_state.sid && srs->sr_state.numcsns ) {
                        Debug( LDAP_DEBUG_SYNC,
                              "Entry %s changed by peer, ignored\n",
                              rs->sr_entry->e_name.bv_val, 0, 0 );
                        return LDAP_SUCCESS;
                  }

                  /* If not a persistent search */
                  if ( !ss->ss_so ) {
                        /* Make sure entry is less than the snapshot'd contextCSN */
                        for ( i=0; i<ss->ss_numcsns; i++ ) {
                              if ( sid == ss->ss_sids[i] && ber_bvcmp( &a->a_nvals[0],
                                    &ss->ss_ctxcsn[i] ) > 0 ) {
                                    Debug( LDAP_DEBUG_SYNC,
                                          "Entry %s CSN %s greater than snapshot %s\n",
                                          rs->sr_entry->e_name.bv_val,
                                          a->a_nvals[0].bv_val,
                                          ss->ss_ctxcsn[i].bv_val );
                                    return LDAP_SUCCESS;
                              }
                        }
                  }

                  /* Don't send old entries twice */
                  if ( srs->sr_state.ctxcsn ) {
                        for ( i=0; i<srs->sr_state.numcsns; i++ ) {
                              if ( sid == srs->sr_state.sids[i] &&
                                    ber_bvcmp( &a->a_nvals[0],
                                          &srs->sr_state.ctxcsn[i] )<= 0 ) {
                                    Debug( LDAP_DEBUG_SYNC,
                                          "Entry %s CSN %s older or equal to ctx %s\n",
                                          rs->sr_entry->e_name.bv_val,
                                          a->a_nvals[0].bv_val,
                                          srs->sr_state.ctxcsn[i].bv_val );
                                    return LDAP_SUCCESS;
                              }
                        }
                  }
            }
            rs->sr_ctrls = op->o_tmpalloc( sizeof(LDAPControl *)*2,
                  op->o_tmpmemctx );
            rs->sr_ctrls[1] = NULL;
            /* If we're in delta-sync mode, always send a cookie */
            if ( si->si_nopres && si->si_usehint && a ) {
                  struct berval cookie;
                  slap_compose_sync_cookie( op, &cookie, a->a_nvals, srs->sr_state.rid, srs->sr_state.sid );
                  rs->sr_err = syncprov_state_ctrl( op, rs, rs->sr_entry,
                        LDAP_SYNC_ADD, rs->sr_ctrls, 0, 1, &cookie );
            } else {
                  rs->sr_err = syncprov_state_ctrl( op, rs, rs->sr_entry,
                        LDAP_SYNC_ADD, rs->sr_ctrls, 0, 0, NULL );
            }
      } else if ( rs->sr_type == REP_RESULT && rs->sr_err == LDAP_SUCCESS ) {
            struct berval cookie;

            if ( ss->ss_flags & SS_CHANGED ) {
                  slap_compose_sync_cookie( op, &cookie, ss->ss_ctxcsn,
                        srs->sr_state.rid, srs->sr_state.sid );

                  Debug( LDAP_DEBUG_SYNC, "syncprov_search_response: cookie=%s\n", cookie.bv_val, 0, 0 );
            }

            /* Is this a regular refresh?
             * Note: refresh never gets here if there were no changes
             */
            if ( !ss->ss_so ) {
                  rs->sr_ctrls = op->o_tmpalloc( sizeof(LDAPControl *)*2,
                        op->o_tmpmemctx );
                  rs->sr_ctrls[1] = NULL;
                  rs->sr_err = syncprov_done_ctrl( op, rs, rs->sr_ctrls,
                        0, 1, &cookie, ( ss->ss_flags & SS_PRESENT ) ?  LDAP_SYNC_REFRESH_PRESENTS :
                              LDAP_SYNC_REFRESH_DELETES );
                  op->o_tmpfree( cookie.bv_val, op->o_tmpmemctx );
            } else {
            /* It's RefreshAndPersist, transition to Persist phase */
                  syncprov_sendinfo( op, rs, ( ss->ss_flags & SS_PRESENT ) ?
                        LDAP_TAG_SYNC_REFRESH_PRESENT : LDAP_TAG_SYNC_REFRESH_DELETE,
                        ( ss->ss_flags & SS_CHANGED ) ? &cookie : NULL,
                        1, NULL, 0 );
                  if ( ss->ss_flags & SS_CHANGED )
                        op->o_tmpfree( cookie.bv_val, op->o_tmpmemctx );

                  /* Detach this Op from frontend control */
                  ldap_pvt_thread_mutex_lock( &ss->ss_so->s_mutex );
                  ldap_pvt_thread_mutex_lock( &op->o_conn->c_mutex );

                  /* But not if this connection was closed along the way */
                  if ( op->o_abandon ) {
                        ldap_pvt_thread_mutex_unlock( &op->o_conn->c_mutex );
                        ldap_pvt_thread_mutex_unlock( &ss->ss_so->s_mutex );
                        /* syncprov_ab_cleanup will free this syncop */
                        return SLAPD_ABANDON;

                  } else {
                        /* Turn off the refreshing flag */
                        ss->ss_so->s_flags ^= PS_IS_REFRESHING;

                        syncprov_detach_op( op, ss->ss_so, on );

                        ldap_pvt_thread_mutex_unlock( &op->o_conn->c_mutex );

                        /* If there are queued responses, fire them off */
                        if ( ss->ss_so->s_res )
                              syncprov_qstart( ss->ss_so );
                  }
                  ldap_pvt_thread_mutex_unlock( &ss->ss_so->s_mutex );

                  return LDAP_SUCCESS;
            }
      }

      return SLAP_CB_CONTINUE;
}

static int
syncprov_op_search( Operation *op, SlapReply *rs )
{
      slap_overinst           *on = (slap_overinst *)op->o_bd->bd_info;
      syncprov_info_t         *si = (syncprov_info_t *)on->on_bi.bi_private;
      slap_callback     *cb;
      int gotstate = 0, changed = 0, do_present = 0;
      syncops *sop = NULL;
      searchstate *ss;
      sync_control *srs;
      BerVarray ctxcsn;
      int i, *sids, numcsns;
      struct berval mincsn;

      if ( !(op->o_sync_mode & SLAP_SYNC_REFRESH) ) return SLAP_CB_CONTINUE;

      if ( op->ors_deref & LDAP_DEREF_SEARCHING ) {
            send_ldap_error( op, rs, LDAP_PROTOCOL_ERROR, "illegal value for derefAliases" );
            return rs->sr_err;
      }

      srs = op->o_controls[slap_cids.sc_LDAPsync];
      op->o_managedsait = SLAP_CONTROL_NONCRITICAL;

      /* If this is a persistent search, set it up right away */
      if ( op->o_sync_mode & SLAP_SYNC_PERSIST ) {
            syncops so = {0};
            fbase_cookie fc;
            opcookie opc;
            slap_callback sc;

            fc.fss = &so;
            fc.fbase = 0;
            so.s_eid = NOID;
            so.s_op = op;
            so.s_flags = PS_IS_REFRESHING | PS_FIND_BASE;
            /* syncprov_findbase expects to be called as a callback... */
            sc.sc_private = &opc;
            opc.son = on;
            ldap_pvt_thread_mutex_init( &so.s_mutex );
            cb = op->o_callback;
            op->o_callback = &sc;
            rs->sr_err = syncprov_findbase( op, &fc );
            op->o_callback = cb;
            ldap_pvt_thread_mutex_destroy( &so.s_mutex );

            if ( rs->sr_err != LDAP_SUCCESS ) {
                  send_ldap_result( op, rs );
                  return rs->sr_err;
            }
            sop = ch_malloc( sizeof( syncops ));
            *sop = so;
            ldap_pvt_thread_mutex_init( &sop->s_mutex );
            sop->s_rid = srs->sr_state.rid;
            sop->s_sid = srs->sr_state.sid;
            sop->s_inuse = 1;

            ldap_pvt_thread_mutex_lock( &si->si_ops_mutex );
            sop->s_next = si->si_ops;
            si->si_ops = sop;
            ldap_pvt_thread_mutex_unlock( &si->si_ops_mutex );
      }

      /* snapshot the ctxcsn */
      ldap_pvt_thread_rdwr_rlock( &si->si_csn_rwlock );
      numcsns = si->si_numcsns;
      if ( numcsns ) {
            ber_bvarray_dup_x( &ctxcsn, si->si_ctxcsn, op->o_tmpmemctx );
            sids = op->o_tmpalloc( numcsns * sizeof(int), op->o_tmpmemctx );
            for ( i=0; i<numcsns; i++ )
                  sids[i] = si->si_sids[i];
      } else {
            ctxcsn = NULL;
            sids = NULL;
      }
      ldap_pvt_thread_rdwr_runlock( &si->si_csn_rwlock );
      
      /* If we have a cookie, handle the PRESENT lookups */
      if ( srs->sr_state.ctxcsn ) {
            sessionlog *sl;
            int i, j;

            /* If we don't have any CSN of our own yet, pretend nothing
             * has changed.
             */
            if ( !numcsns )
                  goto no_change;

            if ( !si->si_nopres )
                  do_present = SS_PRESENT;

            /* If there are SIDs we don't recognize in the cookie, drop them */
            for (i=0; i<srs->sr_state.numcsns; ) {
                  for (j=0; j<numcsns; j++) {
                        if ( srs->sr_state.sids[i] == sids[j] ) {
                              break;
                        }
                  }
                  /* not found */
                  if ( j == numcsns ) {
                        struct berval tmp = srs->sr_state.ctxcsn[i];
                        j = srs->sr_state.numcsns - 1;
                        srs->sr_state.ctxcsn[i] = srs->sr_state.ctxcsn[j];
                        tmp.bv_len = 0;
                        srs->sr_state.ctxcsn[j] = tmp;
                        srs->sr_state.numcsns = j;
                        srs->sr_state.sids[i] = srs->sr_state.sids[j];
                        continue;
                  }
                  i++;
            }

            /* Find the smallest CSN */
            mincsn = srs->sr_state.ctxcsn[0];
            for ( i=1; i<srs->sr_state.numcsns; i++ ) {
                  if ( ber_bvcmp( &mincsn, &srs->sr_state.ctxcsn[i] ) > 0 )
                        mincsn = srs->sr_state.ctxcsn[i];
            }

            /* If nothing has changed, shortcut it */
            if ( srs->sr_state.numcsns == numcsns ) {
                  int i, j;
                  for ( i=0; i<srs->sr_state.numcsns; i++ ) {
                        for ( j=0; j<numcsns; j++ ) {
                              if ( srs->sr_state.sids[i] != sids[j] )
                                    continue;
                              if ( !bvmatch( &srs->sr_state.ctxcsn[i], &ctxcsn[j] ))
                                    changed = SS_CHANGED;
                              break;
                        }
                        if ( changed )
                              break;
                  }
                  if ( !changed ) {
                        do_present = 0;
no_change:        if ( !(op->o_sync_mode & SLAP_SYNC_PERSIST) ) {
                              LDAPControl *ctrls[2];

                              ctrls[0] = NULL;
                              ctrls[1] = NULL;
                              syncprov_done_ctrl( op, rs, ctrls, 0, 0,
                                    NULL, LDAP_SYNC_REFRESH_DELETES );
                              rs->sr_ctrls = ctrls;
                              rs->sr_err = LDAP_SUCCESS;
                              send_ldap_result( op, rs );
                              rs->sr_ctrls = NULL;
                              return rs->sr_err;
                        }
                        goto shortcut;
                  }
            } else {
                  /* consumer doesn't have the right number of CSNs */
                  changed = SS_CHANGED;
            }
            /* Do we have a sessionlog for this search? */
            sl=si->si_logs;
            if ( sl ) {
                  ldap_pvt_thread_mutex_lock( &sl->sl_mutex );
                  /* Are there any log entries, and is the consumer state
                   * present in the session log?
                   */
                  if ( sl->sl_num > 0 && ber_bvcmp( &mincsn, &sl->sl_mincsn ) >= 0 ) {
                        do_present = 0;
                        /* mutex is unlocked in playlog */
                        syncprov_playlog( op, rs, sl, srs, ctxcsn, numcsns, sids );
                  } else {
                        ldap_pvt_thread_mutex_unlock( &sl->sl_mutex );
                  }
            }
            /* Is the CSN still present in the database? */
            if ( syncprov_findcsn( op, FIND_CSN ) != LDAP_SUCCESS ) {
                  /* No, so a reload is required */
                  /* the 2.2 consumer doesn't send this hint */
                  if ( si->si_usehint && srs->sr_rhint == 0 ) {
                        if ( ctxcsn )
                              ber_bvarray_free_x( ctxcsn, op->o_tmpmemctx );
                        if ( sids )
                              op->o_tmpfree( sids, op->o_tmpmemctx );
                        send_ldap_error( op, rs, LDAP_SYNC_REFRESH_REQUIRED, "sync cookie is stale" );
                        return rs->sr_err;
                  }
            } else {
                  gotstate = 1;
                  /* If changed and doing Present lookup, send Present UUIDs */
                  if ( do_present && syncprov_findcsn( op, FIND_PRESENT ) !=
                        LDAP_SUCCESS ) {
                        if ( ctxcsn )
                              ber_bvarray_free_x( ctxcsn, op->o_tmpmemctx );
                        if ( sids )
                              op->o_tmpfree( sids, op->o_tmpmemctx );
                        send_ldap_result( op, rs );
                        return rs->sr_err;
                  }
            }
      } else {
            /* No consumer state, assume something has changed */
            changed = SS_CHANGED;
      }

shortcut:
      /* Append CSN range to search filter, save original filter
       * for persistent search evaluation
       */
      if ( sop ) {
            sop->s_filterstr= op->ors_filterstr;
      }

      /* If something changed, find the changes */
      if ( gotstate && changed ) {
            Filter *fand, *fava;

            fand = op->o_tmpalloc( sizeof(Filter), op->o_tmpmemctx );
            fand->f_choice = LDAP_FILTER_AND;
            fand->f_next = NULL;
            fava = op->o_tmpalloc( sizeof(Filter), op->o_tmpmemctx );
            fand->f_and = fava;
            fava->f_choice = LDAP_FILTER_GE;
            fava->f_ava = op->o_tmpalloc( sizeof(AttributeAssertion), op->o_tmpmemctx );
            fava->f_ava->aa_desc = slap_schema.si_ad_entryCSN;
#ifdef LDAP_COMP_MATCH
            fava->f_ava->aa_cf = NULL;
#endif
            ber_dupbv_x( &fava->f_ava->aa_value, &mincsn, op->o_tmpmemctx );
            fava->f_next = op->ors_filter;
            op->ors_filter = fand;
            filter2bv_x( op, op->ors_filter, &op->ors_filterstr );
            if ( sop )
                  sop->s_flags |= PS_FIX_FILTER;
      }

      /* Let our callback add needed info to returned entries */
      cb = op->o_tmpcalloc(1, sizeof(slap_callback)+sizeof(searchstate), op->o_tmpmemctx);
      ss = (searchstate *)(cb+1);
      ss->ss_on = on;
      ss->ss_so = sop;
      ss->ss_flags = do_present | changed;
      ss->ss_ctxcsn = ctxcsn;
      ss->ss_numcsns = numcsns;
      ss->ss_sids = sids;
      cb->sc_response = syncprov_search_response;
      cb->sc_cleanup = syncprov_search_cleanup;
      cb->sc_private = ss;
      cb->sc_next = op->o_callback;
      op->o_callback = cb;

      /* If this is a persistent search and no changes were reported during
       * the refresh phase, just invoke the response callback to transition
       * us into persist phase
       */
      if ( !changed ) {
            rs->sr_err = LDAP_SUCCESS;
            rs->sr_nentries = 0;
            send_ldap_result( op, rs );
            return rs->sr_err;
      }
      return SLAP_CB_CONTINUE;
}

static int
syncprov_operational(
      Operation *op,
      SlapReply *rs )
{
      slap_overinst           *on = (slap_overinst *)op->o_bd->bd_info;
      syncprov_info_t         *si = (syncprov_info_t *)on->on_bi.bi_private;

      /* This prevents generating unnecessarily; frontend will strip
       * any statically stored copy.
       */
      if ( op->o_sync != SLAP_CONTROL_NONE )
            return SLAP_CB_CONTINUE;

      if ( rs->sr_entry &&
            dn_match( &rs->sr_entry->e_nname, op->o_bd->be_nsuffix )) {

            if ( SLAP_OPATTRS( rs->sr_attr_flags ) ||
                  ad_inlist( slap_schema.si_ad_contextCSN, rs->sr_attrs )) {
                  Attribute *a, **ap = NULL;

                  for ( a=rs->sr_entry->e_attrs; a; a=a->a_next ) {
                        if ( a->a_desc == slap_schema.si_ad_contextCSN )
                              break;
                  }

                  ldap_pvt_thread_rdwr_rlock( &si->si_csn_rwlock );
                  if ( si->si_ctxcsn ) {
                        if ( !a ) {
                              for ( ap = &rs->sr_operational_attrs; *ap;
                                    ap=&(*ap)->a_next );

                              a = attr_alloc( slap_schema.si_ad_contextCSN );
                              *ap = a;
                        }

                        if ( !ap ) {
                              if ( !(rs->sr_flags & REP_ENTRY_MODIFIABLE) ) {
                                    Entry *e = entry_dup( rs->sr_entry );
                                    if ( rs->sr_flags & REP_ENTRY_MUSTRELEASE ) {
                                          overlay_entry_release_ov( op, rs->sr_entry, 0, on );
                                          rs->sr_flags ^= REP_ENTRY_MUSTRELEASE;
                                    } else if ( rs->sr_flags & REP_ENTRY_MUSTBEFREED ) {
                                          entry_free( rs->sr_entry );
                                    }
                                    rs->sr_entry = e;
                                    rs->sr_flags |=
                                          REP_ENTRY_MODIFIABLE|REP_ENTRY_MUSTBEFREED;
                                    a = attr_find( rs->sr_entry->e_attrs,
                                          slap_schema.si_ad_contextCSN );
                              }
                              if ( a->a_nvals != a->a_vals ) {
                                    ber_bvarray_free( a->a_nvals );
                              }
                              a->a_nvals = NULL;
                              ber_bvarray_free( a->a_vals );
                              a->a_vals = NULL;
                              a->a_numvals = 0;
                        }
                        attr_valadd( a, si->si_ctxcsn, si->si_ctxcsn, si->si_numcsns );
                  }
                  ldap_pvt_thread_rdwr_runlock( &si->si_csn_rwlock );
            }
      }
      return SLAP_CB_CONTINUE;
}

enum {
      SP_CHKPT = 1,
      SP_SESSL,
      SP_NOPRES,
      SP_USEHINT
};

static ConfigDriver sp_cf_gen;

static ConfigTable spcfg[] = {
      { "syncprov-checkpoint", "ops> <minutes", 3, 3, 0, ARG_MAGIC|SP_CHKPT,
            sp_cf_gen, "( OLcfgOvAt:1.1 NAME 'olcSpCheckpoint' "
                  "DESC 'ContextCSN checkpoint interval in ops and minutes' "
                  "SYNTAX OMsDirectoryString SINGLE-VALUE )", NULL, NULL },
      { "syncprov-sessionlog", "ops", 2, 2, 0, ARG_INT|ARG_MAGIC|SP_SESSL,
            sp_cf_gen, "( OLcfgOvAt:1.2 NAME 'olcSpSessionlog' "
                  "DESC 'Session log size in ops' "
                  "SYNTAX OMsInteger SINGLE-VALUE )", NULL, NULL },
      { "syncprov-nopresent", NULL, 2, 2, 0, ARG_ON_OFF|ARG_MAGIC|SP_NOPRES,
            sp_cf_gen, "( OLcfgOvAt:1.3 NAME 'olcSpNoPresent' "
                  "DESC 'Omit Present phase processing' "
                  "SYNTAX OMsBoolean SINGLE-VALUE )", NULL, NULL },
      { "syncprov-reloadhint", NULL, 2, 2, 0, ARG_ON_OFF|ARG_MAGIC|SP_USEHINT,
            sp_cf_gen, "( OLcfgOvAt:1.4 NAME 'olcSpReloadHint' "
                  "DESC 'Observe Reload Hint in Request control' "
                  "SYNTAX OMsBoolean SINGLE-VALUE )", NULL, NULL },
      { NULL, NULL, 0, 0, 0, ARG_IGNORED }
};

static ConfigOCs spocs[] = {
      { "( OLcfgOvOc:1.1 "
            "NAME 'olcSyncProvConfig' "
            "DESC 'SyncRepl Provider configuration' "
            "SUP olcOverlayConfig "
            "MAY ( olcSpCheckpoint $ olcSpSessionlog $ olcSpNoPresent ) )",
                  Cft_Overlay, spcfg },
      { NULL, 0, NULL }
};

static int
sp_cf_gen(ConfigArgs *c)
{
      slap_overinst           *on = (slap_overinst *)c->bi;
      syncprov_info_t         *si = (syncprov_info_t *)on->on_bi.bi_private;
      int rc = 0;

      if ( c->op == SLAP_CONFIG_EMIT ) {
            switch ( c->type ) {
            case SP_CHKPT:
                  if ( si->si_chkops || si->si_chktime ) {
                        struct berval bv;
                        bv.bv_len = snprintf( c->cr_msg, sizeof( c->cr_msg ),
                              "%d %d", si->si_chkops, si->si_chktime );
                        if ( bv.bv_len < 0 || bv.bv_len >= sizeof( c->cr_msg ) ) {
                              rc = 1;
                        } else {
                              bv.bv_val = c->cr_msg;
                              value_add_one( &c->rvalue_vals, &bv );
                        }
                  } else {
                        rc = 1;
                  }
                  break;
            case SP_SESSL:
                  if ( si->si_logs ) {
                        c->value_int = si->si_logs->sl_size;
                  } else {
                        rc = 1;
                  }
                  break;
            case SP_NOPRES:
                  if ( si->si_nopres ) {
                        c->value_int = 1;
                  } else {
                        rc = 1;
                  }
                  break;
            case SP_USEHINT:
                  if ( si->si_usehint ) {
                        c->value_int = 1;
                  } else {
                        rc = 1;
                  }
                  break;
            }
            return rc;
      } else if ( c->op == LDAP_MOD_DELETE ) {
            switch ( c->type ) {
            case SP_CHKPT:
                  si->si_chkops = 0;
                  si->si_chktime = 0;
                  break;
            case SP_SESSL:
                  if ( si->si_logs )
                        si->si_logs->sl_size = 0;
                  else
                        rc = LDAP_NO_SUCH_ATTRIBUTE;
                  break;
            case SP_NOPRES:
                  if ( si->si_nopres )
                        si->si_nopres = 0;
                  else
                        rc = LDAP_NO_SUCH_ATTRIBUTE;
                  break;
            case SP_USEHINT:
                  if ( si->si_usehint )
                        si->si_usehint = 0;
                  else
                        rc = LDAP_NO_SUCH_ATTRIBUTE;
                  break;
            }
            return rc;
      }
      switch ( c->type ) {
      case SP_CHKPT:
            if ( lutil_atoi( &si->si_chkops, c->argv[1] ) != 0 ) {
                  snprintf( c->cr_msg, sizeof( c->cr_msg ), "%s unable to parse checkpoint ops # \"%s\"",
                        c->argv[0], c->argv[1] );
                  Debug( LDAP_DEBUG_CONFIG|LDAP_DEBUG_NONE,
                        "%s: %s\n", c->log, c->cr_msg, 0 );
                  return ARG_BAD_CONF;
            }
            if ( si->si_chkops <= 0 ) {
                  snprintf( c->cr_msg, sizeof( c->cr_msg ), "%s invalid checkpoint ops # \"%d\"",
                        c->argv[0], si->si_chkops );
                  Debug( LDAP_DEBUG_CONFIG|LDAP_DEBUG_NONE,
                        "%s: %s\n", c->log, c->cr_msg, 0 );
                  return ARG_BAD_CONF;
            }
            if ( lutil_atoi( &si->si_chktime, c->argv[2] ) != 0 ) {
                  snprintf( c->cr_msg, sizeof( c->cr_msg ), "%s unable to parse checkpoint time \"%s\"",
                        c->argv[0], c->argv[1] );
                  Debug( LDAP_DEBUG_CONFIG|LDAP_DEBUG_NONE,
                        "%s: %s\n", c->log, c->cr_msg, 0 );
                  return ARG_BAD_CONF;
            }
            if ( si->si_chktime <= 0 ) {
                  snprintf( c->cr_msg, sizeof( c->cr_msg ), "%s invalid checkpoint time \"%d\"",
                        c->argv[0], si->si_chkops );
                  Debug( LDAP_DEBUG_CONFIG|LDAP_DEBUG_NONE,
                        "%s: %s\n", c->log, c->cr_msg, 0 );
                  return ARG_BAD_CONF;
            }
            si->si_chktime *= 60;
            break;
      case SP_SESSL: {
            sessionlog *sl;
            int size = c->value_int;

            if ( size < 0 ) {
                  snprintf( c->cr_msg, sizeof( c->cr_msg ), "%s size %d is negative",
                        c->argv[0], size );
                  Debug( LDAP_DEBUG_CONFIG|LDAP_DEBUG_NONE,
                        "%s: %s\n", c->log, c->cr_msg, 0 );
                  return ARG_BAD_CONF;
            }
            sl = si->si_logs;
            if ( !sl ) {
                  sl = ch_malloc( sizeof( sessionlog ) + LDAP_LUTIL_CSNSTR_BUFSIZE );
                  sl->sl_mincsn.bv_val = (char *)(sl+1);
                  sl->sl_mincsn.bv_len = 0;
                  sl->sl_num = 0;
                  sl->sl_head = sl->sl_tail = NULL;
                  ldap_pvt_thread_mutex_init( &sl->sl_mutex );
                  si->si_logs = sl;
            }
            sl->sl_size = size;
            }
            break;
      case SP_NOPRES:
            si->si_nopres = c->value_int;
            break;
      case SP_USEHINT:
            si->si_usehint = c->value_int;
            break;
      }
      return rc;
}

/* ITS#3456 we cannot run this search on the main thread, must use a
 * child thread in order to insure we have a big enough stack.
 */
static void *
syncprov_db_otask(
      void *ptr
)
{
      syncprov_findcsn( ptr, FIND_MAXCSN );
      return NULL;
}

/* Read any existing contextCSN from the underlying db.
 * Then search for any entries newer than that. If no value exists,
 * just generate it. Cache whatever result.
 */
static int
syncprov_db_open(
      BackendDB *be,
      ConfigReply *cr
)
{
      slap_overinst   *on = (slap_overinst *) be->bd_info;
      syncprov_info_t *si = (syncprov_info_t *)on->on_bi.bi_private;

      Connection conn = { 0 };
      OperationBuffer opbuf;
      Operation *op;
      Entry *e = NULL;
      Attribute *a;
      int rc;
      void *thrctx = NULL;

      if ( !SLAP_LASTMOD( be )) {
            Debug( LDAP_DEBUG_ANY,
                  "syncprov_db_open: invalid config, lastmod must be enabled\n", 0, 0, 0 );
            return -1;
      }

      if ( slapMode & SLAP_TOOL_MODE ) {
            return 0;
      }

      rc = overlay_register_control( be, LDAP_CONTROL_SYNC );
      if ( rc ) {
            return rc;
      }

      thrctx = ldap_pvt_thread_pool_context();
      connection_fake_init( &conn, &opbuf, thrctx );
      op = &opbuf.ob_op;
      op->o_bd = be;
      op->o_dn = be->be_rootdn;
      op->o_ndn = be->be_rootndn;

      rc = overlay_entry_get_ov( op, be->be_nsuffix, NULL,
            slap_schema.si_ad_contextCSN, 0, &e, on );

      if ( e ) {
            ldap_pvt_thread_t tid;

            a = attr_find( e->e_attrs, slap_schema.si_ad_contextCSN );
            if ( a ) {
                  ber_bvarray_dup_x( &si->si_ctxcsn, a->a_vals, NULL );
                  si->si_numcsns = a->a_numvals;
                  si->si_sids = slap_parse_csn_sids( si->si_ctxcsn, a->a_numvals, NULL );
            }
            overlay_entry_release_ov( op, e, 0, on );
            if ( si->si_ctxcsn ) {
                  op->o_req_dn = be->be_suffix[0];
                  op->o_req_ndn = be->be_nsuffix[0];
                  op->ors_scope = LDAP_SCOPE_SUBTREE;
                  ldap_pvt_thread_create( &tid, 0, syncprov_db_otask, op );
                  ldap_pvt_thread_join( tid, NULL );
            }
      }

      /* Didn't find a contextCSN, should we generate one? */
      if ( !si->si_ctxcsn ) {
            char csnbuf[ LDAP_LUTIL_CSNSTR_BUFSIZE ];
            struct berval csn;

            if ( SLAP_SYNC_SHADOW( op->o_bd )) {
            /* If we're also a consumer, then don't generate anything.
             * Wait for our provider to send it to us, or for a local
             * modify if we have multimaster.
             */
                  goto out;
            }
            csn.bv_val = csnbuf;
            csn.bv_len = sizeof( csnbuf );
            slap_get_csn( op, &csn, 0 );
            value_add_one( &si->si_ctxcsn, &csn );
            si->si_numcsns = 1;
            si->si_sids = ch_malloc( sizeof(int) );
            si->si_sids[0] = slap_serverID;

            /* make sure we do a checkpoint on close */
            si->si_numops++;
      }

out:
      op->o_bd->bd_info = (BackendInfo *)on;
      return 0;
}

/* Write the current contextCSN into the underlying db.
 */
static int
syncprov_db_close(
      BackendDB *be,
      ConfigReply *cr
)
{
    slap_overinst   *on = (slap_overinst *) be->bd_info;
    syncprov_info_t *si = (syncprov_info_t *)on->on_bi.bi_private;

      if ( slapMode & SLAP_TOOL_MODE ) {
            return 0;
      }
      if ( si->si_numops ) {
            Connection conn = {0};
            OperationBuffer opbuf;
            Operation *op;
            SlapReply rs = {REP_RESULT};
            void *thrctx;

            thrctx = ldap_pvt_thread_pool_context();
            connection_fake_init( &conn, &opbuf, thrctx );
            op = &opbuf.ob_op;
            op->o_bd = be;
            op->o_dn = be->be_rootdn;
            op->o_ndn = be->be_rootndn;
            syncprov_checkpoint( op, &rs, on );
      }

    return 0;
}

static int
syncprov_db_init(
      BackendDB *be,
      ConfigReply *cr
)
{
      slap_overinst     *on = (slap_overinst *)be->bd_info;
      syncprov_info_t   *si;

      if ( SLAP_ISGLOBALOVERLAY( be ) ) {
            Debug( LDAP_DEBUG_ANY,
                  "syncprov must be instantiated within a database.\n",
                  0, 0, 0 );
            return 1;
      }

      si = ch_calloc(1, sizeof(syncprov_info_t));
      on->on_bi.bi_private = si;
      ldap_pvt_thread_rdwr_init( &si->si_csn_rwlock );
      ldap_pvt_thread_mutex_init( &si->si_ops_mutex );
      ldap_pvt_thread_mutex_init( &si->si_mods_mutex );

      csn_anlist[0].an_desc = slap_schema.si_ad_entryCSN;
      csn_anlist[0].an_name = slap_schema.si_ad_entryCSN->ad_cname;
      csn_anlist[1].an_desc = slap_schema.si_ad_entryUUID;
      csn_anlist[1].an_name = slap_schema.si_ad_entryUUID->ad_cname;

      uuid_anlist[0].an_desc = slap_schema.si_ad_entryUUID;
      uuid_anlist[0].an_name = slap_schema.si_ad_entryUUID->ad_cname;

      return 0;
}

static int
syncprov_db_destroy(
      BackendDB *be,
      ConfigReply *cr
)
{
      slap_overinst     *on = (slap_overinst *)be->bd_info;
      syncprov_info_t   *si = (syncprov_info_t *)on->on_bi.bi_private;

      if ( si ) {
            if ( si->si_logs ) {
                  slog_entry *se = si->si_logs->sl_head;

                  while ( se ) {
                        slog_entry *se_next = se->se_next;
                        ch_free( se );
                        se = se_next;
                  }
                        
                  ch_free( si->si_logs );
            }
            if ( si->si_ctxcsn )
                  ber_bvarray_free( si->si_ctxcsn );
            if ( si->si_sids )
                  ch_free( si->si_sids );
            ldap_pvt_thread_mutex_destroy( &si->si_mods_mutex );
            ldap_pvt_thread_mutex_destroy( &si->si_ops_mutex );
            ldap_pvt_thread_rdwr_destroy( &si->si_csn_rwlock );
            ch_free( si );
      }

      return 0;
}

static int syncprov_parseCtrl (
      Operation *op,
      SlapReply *rs,
      LDAPControl *ctrl )
{
      ber_tag_t tag;
      BerElementBuffer berbuf;
      BerElement *ber = (BerElement *)&berbuf;
      ber_int_t mode;
      ber_len_t len;
      struct berval cookie = BER_BVNULL;
      sync_control *sr;
      int rhint = 0;

      if ( op->o_sync != SLAP_CONTROL_NONE ) {
            rs->sr_text = "Sync control specified multiple times";
            return LDAP_PROTOCOL_ERROR;
      }

      if ( op->o_pagedresults != SLAP_CONTROL_NONE ) {
            rs->sr_text = "Sync control specified with pagedResults control";
            return LDAP_PROTOCOL_ERROR;
      }

      if ( BER_BVISNULL( &ctrl->ldctl_value ) ) {
            rs->sr_text = "Sync control value is absent";
            return LDAP_PROTOCOL_ERROR;
      }

      if ( BER_BVISEMPTY( &ctrl->ldctl_value ) ) {
            rs->sr_text = "Sync control value is empty";
            return LDAP_PROTOCOL_ERROR;
      }

      /* Parse the control value
       *      syncRequestValue ::= SEQUENCE {
       *              mode   ENUMERATED {
       *                      -- 0 unused
       *                      refreshOnly       (1),
       *                      -- 2 reserved
       *                      refreshAndPersist (3)
       *              },
       *              cookie  syncCookie OPTIONAL
       *      }
       */

      ber_init2( ber, &ctrl->ldctl_value, 0 );

      if ( (tag = ber_scanf( ber, "{i" /*}*/, &mode )) == LBER_ERROR ) {
            rs->sr_text = "Sync control : mode decoding error";
            return LDAP_PROTOCOL_ERROR;
      }

      switch( mode ) {
      case LDAP_SYNC_REFRESH_ONLY:
            mode = SLAP_SYNC_REFRESH;
            break;
      case LDAP_SYNC_REFRESH_AND_PERSIST:
            mode = SLAP_SYNC_REFRESH_AND_PERSIST;
            break;
      default:
            rs->sr_text = "Sync control : unknown update mode";
            return LDAP_PROTOCOL_ERROR;
      }

      tag = ber_peek_tag( ber, &len );

      if ( tag == LDAP_TAG_SYNC_COOKIE ) {
            if (( ber_scanf( ber, /*{*/ "m", &cookie )) == LBER_ERROR ) {
                  rs->sr_text = "Sync control : cookie decoding error";
                  return LDAP_PROTOCOL_ERROR;
            }
            tag = ber_peek_tag( ber, &len );
      }
      if ( tag == LDAP_TAG_RELOAD_HINT ) {
            if (( ber_scanf( ber, /*{*/ "b", &rhint )) == LBER_ERROR ) {
                  rs->sr_text = "Sync control : rhint decoding error";
                  return LDAP_PROTOCOL_ERROR;
            }
      }
      if (( ber_scanf( ber, /*{*/ "}")) == LBER_ERROR ) {
                  rs->sr_text = "Sync control : decoding error";
                  return LDAP_PROTOCOL_ERROR;
      }
      sr = op->o_tmpcalloc( 1, sizeof(struct sync_control), op->o_tmpmemctx );
      sr->sr_rhint = rhint;
      if (!BER_BVISNULL(&cookie)) {
            ber_dupbv_x( &sr->sr_state.octet_str, &cookie, op->o_tmpmemctx );
            /* If parse fails, pretend no cookie was sent */
            if ( slap_parse_sync_cookie( &sr->sr_state, op->o_tmpmemctx ) ||
                  sr->sr_state.rid == -1 ) {
                  if ( sr->sr_state.ctxcsn ) {
                        ber_bvarray_free_x( sr->sr_state.ctxcsn, op->o_tmpmemctx );
                        sr->sr_state.ctxcsn = NULL;
                  }
                  sr->sr_state.numcsns = 0;
            }
      }

      op->o_controls[slap_cids.sc_LDAPsync] = sr;

      op->o_sync = ctrl->ldctl_iscritical
            ? SLAP_CONTROL_CRITICAL
            : SLAP_CONTROL_NONCRITICAL;

      op->o_sync_mode |= mode;      /* o_sync_mode shares o_sync */

      return LDAP_SUCCESS;
}

/* This overlay is set up for dynamic loading via moduleload. For static
 * configuration, you'll need to arrange for the slap_overinst to be
 * initialized and registered by some other function inside slapd.
 */

static slap_overinst          syncprov;

int
syncprov_initialize()
{
      int rc;

      rc = register_supported_control( LDAP_CONTROL_SYNC,
            SLAP_CTRL_SEARCH, NULL,
            syncprov_parseCtrl, &slap_cids.sc_LDAPsync );
      if ( rc != LDAP_SUCCESS ) {
            Debug( LDAP_DEBUG_ANY,
                  "syncprov_init: Failed to register control %d\n", rc, 0, 0 );
            return rc;
      }

      syncprov.on_bi.bi_type = "syncprov";
      syncprov.on_bi.bi_db_init = syncprov_db_init;
      syncprov.on_bi.bi_db_destroy = syncprov_db_destroy;
      syncprov.on_bi.bi_db_open = syncprov_db_open;
      syncprov.on_bi.bi_db_close = syncprov_db_close;

      syncprov.on_bi.bi_op_abandon = syncprov_op_abandon;
      syncprov.on_bi.bi_op_cancel = syncprov_op_abandon;

      syncprov.on_bi.bi_op_add = syncprov_op_mod;
      syncprov.on_bi.bi_op_compare = syncprov_op_compare;
      syncprov.on_bi.bi_op_delete = syncprov_op_mod;
      syncprov.on_bi.bi_op_modify = syncprov_op_mod;
      syncprov.on_bi.bi_op_modrdn = syncprov_op_mod;
      syncprov.on_bi.bi_op_search = syncprov_op_search;
      syncprov.on_bi.bi_extended = syncprov_op_extended;
      syncprov.on_bi.bi_operational = syncprov_operational;

      syncprov.on_bi.bi_cf_ocs = spocs;

      generic_filter.f_desc = slap_schema.si_ad_objectClass;

      rc = config_register_schema( spcfg, spocs );
      if ( rc ) return rc;

      return overlay_register( &syncprov );
}

#if SLAPD_OVER_SYNCPROV == SLAPD_MOD_DYNAMIC
int
init_module( int argc, char *argv[] )
{
      return syncprov_initialize();
}
#endif /* SLAPD_OVER_SYNCPROV == SLAPD_MOD_DYNAMIC */

#endif /* defined(SLAPD_OVER_SYNCPROV) */

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