/* 
   Unix SMB/Netbios implementation.
   Version 2.0

   Winbind daemon - caching related functions

   Copyright (C) Tim Potter 2000
   
   This program is free software; you can redistribute it and/or modify
   it under the terms of the GNU General Public License as published by
   the Free Software Foundation; either version 2 of the License, or
   (at your option) any later version.
   
   This program is distributed in the hope that it will be useful,
   but WITHOUT ANY WARRANTY; without even the implied warranty of
   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
   GNU General Public License for more details.
   
   You should have received a copy of the GNU General Public License
   along with this program; if not, write to the Free Software
   Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
*/

#include "winbindd.h"

#define CACHE_TYPE_USER "USR"
#define CACHE_TYPE_GROUP "GRP"
#define CACHE_TYPE_NAME "NAM"      /* Stores mapping from SID to name. */
#define CACHE_TYPE_SID "SID"       /* Stores mapping from name to SID. */

/* Initialise caching system */

static TDB_CONTEXT *cache_tdb;

struct cache_rec {
	uint32 seq_num;
	time_t mod_time;
};

void winbindd_cache_init(void)
{
	/* Open tdb cache */

	if (!(cache_tdb = tdb_open_log(lock_path("winbindd_cache.tdb"), 0, 
				   TDB_NOLOCK, O_RDWR | O_CREAT | O_TRUNC, 
				   0600)))
		DEBUG(0, ("Unable to open tdb cache - user and group caching disabled\n"));
}

/* find the sequence number for a domain */

static uint32 domain_sequence_number(struct winbindd_domain *domain)
{
	TALLOC_CTX *mem_ctx;
	CLI_POLICY_HND *hnd;
	SAM_UNK_CTR ctr;
	uint16 switch_value = 2;
	NTSTATUS result;
	uint32 seqnum = DOM_SEQUENCE_NONE;
	POLICY_HND dom_pol;
	BOOL got_dom_pol = False;
	uint32 des_access = SEC_RIGHTS_MAXIMUM_ALLOWED;

	if (!(mem_ctx = talloc_init()))
		return DOM_SEQUENCE_NONE;

	/* Get sam handle */

	if (!(hnd = cm_get_sam_handle(domain->name)))
		goto done;

	/* Get domain handle */

	result = cli_samr_open_domain(hnd->cli, mem_ctx, &hnd->pol, 
							des_access, &domain->sid, &dom_pol);

	if (!NT_STATUS_IS_OK(result))
		goto done;

	got_dom_pol = True;

	/* Query domain info */

	result = cli_samr_query_dom_info(hnd->cli, mem_ctx, &dom_pol,
							switch_value, &ctr);

	if (NT_STATUS_IS_OK(result)) {
		seqnum = ctr.info.inf2.seq_num;
		DEBUG(10,("domain_sequence_number: for domain %s is %u\n", domain->name, (unsigned)seqnum ));
	} else {
		DEBUG(10,("domain_sequence_number: failed to get sequence number (%u) for domain %s\n",
			(unsigned)seqnum, domain->name ));
	}

  done:

	if (got_dom_pol)
		cli_samr_close(hnd->cli, mem_ctx, &dom_pol);

	talloc_destroy(mem_ctx);

	return seqnum;
}

/* get the domain sequence number, possibly re-fetching */

static uint32 cached_sequence_number(struct winbindd_domain *domain)
{
	fstring keystr;
	TDB_DATA dbuf;
	struct cache_rec rec;
	time_t t = time(NULL);

	snprintf(keystr, sizeof(keystr), "CACHESEQ/%s", domain->name);
	dbuf = tdb_fetch_by_string(cache_tdb, keystr);

	if (!dbuf.dptr || dbuf.dsize != sizeof(rec))
		goto refetch;

	memcpy(&rec, dbuf.dptr, sizeof(rec));
	SAFE_FREE(dbuf.dptr);

	if (t < (rec.mod_time + lp_winbind_cache_time())) {
		DEBUG(3,("cached sequence number for %s is %u\n",
			 domain->name, (unsigned)rec.seq_num));
		return rec.seq_num;
	}

 refetch:	
	rec.seq_num = domain_sequence_number(domain);
	rec.mod_time = t;

	tdb_store_by_string(cache_tdb, keystr, &rec, sizeof(rec));

	return rec.seq_num;
}

/* Check whether a seq_num for a cached item has expired */
static BOOL cache_domain_expired(struct winbindd_domain *domain, 
                                 uint32 seq_num)
{
	uint32 cache_seq = cached_sequence_number(domain);
	if (cache_seq != seq_num) {
		DEBUG(3,("seq %u for %s has expired (not == %u)\n", (unsigned)seq_num, 
			 domain->name, (unsigned)cache_seq ));
		return True;
	}

	return False;
}

static void set_cache_sequence_number(struct winbindd_domain *domain, 
                                      char *cache_type, char *subkey)
{
	fstring keystr;

	snprintf(keystr, sizeof(keystr),"CACHESEQ %s/%s/%s",
		 domain->name, cache_type, subkey?subkey:"");

	tdb_store_int(cache_tdb, keystr, cached_sequence_number(domain));
}

static uint32 get_cache_sequence_number(struct winbindd_domain *domain, 
                                        char *cache_type, char *subkey)
{
	fstring keystr;
	uint32 seq_num;

	snprintf(keystr, sizeof(keystr), "CACHESEQ %s/%s/%s",
		 domain->name, cache_type, subkey ? subkey : "");

	seq_num = (uint32)tdb_fetch_int(cache_tdb, keystr);

	DEBUG(3,("%s is %u\n", keystr, (unsigned)seq_num));

	return seq_num;
}

/* Fill the user or group cache with supplied data */

static void store_cache(struct winbindd_domain *domain, char *cache_type,
			void *sam_entries, int buflen)
{
	fstring keystr;

	if (lp_winbind_cache_time() == 0) 
		return;

	/* Error check */

	if (!sam_entries || buflen == 0) 
		return;

	/* Store data as a mega-huge chunk in the tdb */

	snprintf(keystr, sizeof(keystr), "%s CACHE DATA/%s", cache_type,
		 domain->name);

	tdb_store_by_string(cache_tdb, keystr, sam_entries, buflen);

	/* Stamp cache with current seq number */

	set_cache_sequence_number(domain, cache_type, NULL);
}

/* Fill the user cache with supplied data */

void winbindd_store_user_cache(struct winbindd_domain *domain, 
			       struct getpwent_user *sam_entries,
			       int num_sam_entries)
{
	DEBUG(3, ("storing user cache %s/%d entries\n", domain->name,
		  num_sam_entries));

	store_cache(domain, CACHE_TYPE_USER, sam_entries,
		    num_sam_entries * sizeof(struct getpwent_user));
}

/* Fill the group cache with supplied data */

void winbindd_store_group_cache(struct winbindd_domain *domain,
				struct acct_info *sam_entries,
				int num_sam_entries)
{
	DEBUG(0, ("storing group cache %s/%d entries\n", domain->name,
		  num_sam_entries));		  

	store_cache(domain, CACHE_TYPE_GROUP, sam_entries, 
		    num_sam_entries * sizeof(struct acct_info));
}

static void store_cache_entry(struct winbindd_domain *domain, char *cache_type,
                              char *name, void *buf, int len)
{
	fstring keystr;

	/* Create key for store */

	snprintf(keystr, sizeof(keystr), "%s/%s/%s", cache_type, 
                 domain->name, name);

	/* Store it */

	tdb_store_by_string(cache_tdb, keystr, buf, len);
}

/* Fill a name cache entry */

void winbindd_store_name_cache_entry(struct winbindd_domain *domain, 
                                     char *sid, struct winbindd_name *name)
{
	if (lp_winbind_cache_time() == 0) 
		return;

	store_cache_entry(domain, CACHE_TYPE_NAME, sid, name, 
		sizeof(struct winbindd_name));

	set_cache_sequence_number(domain, CACHE_TYPE_NAME, sid);
}

/* Fill a SID cache entry */

void winbindd_store_sid_cache_entry(struct winbindd_domain *domain, 
                                     char *name, struct winbindd_sid *sid)
{
	if (lp_winbind_cache_time() == 0) 
		return;

	store_cache_entry(domain, CACHE_TYPE_SID, name, sid, 
		sizeof(struct winbindd_sid));

	set_cache_sequence_number(domain, CACHE_TYPE_SID, name);
}

/* Fill a user info cache entry */

void winbindd_store_user_cache_entry(struct winbindd_domain *domain, 
                                     char *user_name, struct winbindd_pw *pw)
{
	if (lp_winbind_cache_time() == 0) 
		return;

	store_cache_entry(domain, CACHE_TYPE_USER, user_name, pw, 
		sizeof(struct winbindd_pw));

	set_cache_sequence_number(domain, CACHE_TYPE_USER, user_name);
}

/* Fill a user uid cache entry */

void winbindd_store_uid_cache_entry(struct winbindd_domain *domain, uid_t uid, 
                                    struct winbindd_pw *pw)
{
	fstring uidstr;

	if (lp_winbind_cache_time() == 0)
		return;

	snprintf(uidstr, sizeof(uidstr), "#%u", (unsigned)uid);

	DEBUG(3, ("storing uid cache entry %s/%s\n", domain->name, uidstr));

	store_cache_entry(domain, CACHE_TYPE_USER, uidstr, pw, 
		sizeof(struct winbindd_pw));

	set_cache_sequence_number(domain, CACHE_TYPE_USER, uidstr);
}

/* Fill a group info cache entry */

void winbindd_store_group_cache_entry(struct winbindd_domain *domain, 
                                      char *group_name, struct winbindd_gr *gr,
                                      void *extra_data, int extra_data_len)
{
	fstring keystr;

	if (lp_winbind_cache_time() == 0) 
		return;

	DEBUG(3, ("storing group cache entry %s/%s\n", domain->name, 
		group_name));

	/* Fill group data */

	store_cache_entry(domain, CACHE_TYPE_GROUP, group_name, gr, 
				sizeof(struct winbindd_gr));

	/* Fill extra data */

	snprintf(keystr, sizeof(keystr), "%s/%s/%s DATA", CACHE_TYPE_GROUP, 
				domain->name, group_name);

	tdb_store_by_string(cache_tdb, keystr, extra_data, extra_data_len);

	set_cache_sequence_number(domain, CACHE_TYPE_GROUP, group_name);
}

/* Fill a group info cache entry */

void winbindd_store_gid_cache_entry(struct winbindd_domain *domain, gid_t gid, 
				    struct winbindd_gr *gr, void *extra_data,
				    int extra_data_len)
{
	fstring keystr;
	fstring gidstr;

	snprintf(gidstr, sizeof(gidstr), "#%u", (unsigned)gid);

	if (lp_winbind_cache_time() == 0) 
		return;

	DEBUG(3, ("storing gid cache entry %s/%s\n", domain->name, gidstr));

	/* Fill group data */

	store_cache_entry(domain, CACHE_TYPE_GROUP, gidstr, gr, 
					sizeof(struct winbindd_gr));

	/* Fill extra data */

	snprintf(keystr, sizeof(keystr), "%s/%s/%s DATA", CACHE_TYPE_GROUP, 
				domain->name, gidstr);

	tdb_store_by_string(cache_tdb, keystr, extra_data, extra_data_len);

	set_cache_sequence_number(domain, CACHE_TYPE_GROUP, gidstr);
}

/* Fetch some cached user or group data */

static BOOL fetch_cache(struct winbindd_domain *domain, char *cache_type,
                        void **sam_entries, int *buflen)
{
	TDB_DATA data;
	fstring keystr;

	if (lp_winbind_cache_time() == 0) 
		return False;

	/* Parameter check */

	if (!sam_entries || !buflen)
		return False;

	/* Check cache data is current */

	if (cache_domain_expired(domain, get_cache_sequence_number(domain, cache_type, NULL)))
		return False;
	
	/* Create key */        

	snprintf(keystr, sizeof(keystr), "%s CACHE DATA/%s", cache_type, domain->name);
	
	/* Fetch cache information */

	data = tdb_fetch_by_string(cache_tdb, keystr);
	
	if (!data.dptr) 
		return False;

	/* Copy across cached data.  We can save a memcpy() by directly
	   assigning the data.dptr to the sam_entries pointer.  It will
	   be freed by the end{pw,gr}ent() function. */
	
	*sam_entries = (struct acct_info *)data.dptr;
	*buflen = data.dsize;
	
	return True;
}

/* Return cached entries for a domain.  Return false if there are no cached
   entries, or the cached information has expired for the domain. */

BOOL winbindd_fetch_user_cache(struct winbindd_domain *domain, 
			       struct getpwent_user **sam_entries,
                               int *num_entries)
{
	BOOL result;
	int buflen;

	result = fetch_cache(domain, CACHE_TYPE_USER, 
			     (void **)sam_entries, &buflen);

	*num_entries = buflen / sizeof(struct getpwent_user);

	DEBUG(3, ("fetched %d cache entries for %s\n", *num_entries,
		  domain->name));

	return result;
}

/* Return cached entries for a domain.  Return false if there are no cached
   entries, or the cached information has expired for the domain. */

BOOL winbindd_fetch_group_cache(struct winbindd_domain *domain, 
				struct acct_info **sam_entries,
                                int *num_entries)
{
	BOOL result;
	int buflen;

	result = fetch_cache(domain, CACHE_TYPE_GROUP, 
			     (void **)sam_entries, &buflen);

	*num_entries = buflen / sizeof(struct acct_info);

	DEBUG(3, ("fetched %d cache entries for %s\n", *num_entries,
		  domain->name));

	return result;
}

static BOOL fetch_cache_entry(struct winbindd_domain *domain, 
                              char *cache_type, char *name, void *buf, int len)
{
	TDB_DATA data;
	fstring keystr;
    
	/* Create key for lookup */

	snprintf(keystr, sizeof(keystr), "%s/%s/%s", cache_type, domain->name, name);
    
	/* Look up cache entry */

	data = tdb_fetch_by_string(cache_tdb, keystr);

	if (!data.dptr) 
		return False;
        
	/* Copy found entry into buffer */        

	memcpy((char *)buf, data.dptr, len < data.dsize ? len : data.dsize);
	SAFE_FREE(data.dptr);

	return True;
}

/* Fetch an individual SID cache entry */

BOOL winbindd_fetch_sid_cache_entry(struct winbindd_domain *domain, 
                                     char *name, struct winbindd_sid *sid)
{
	uint32 seq_num;

	if (lp_winbind_cache_time() == 0) 
		return False;

	seq_num = get_cache_sequence_number(domain, CACHE_TYPE_SID, name);

	if (cache_domain_expired(domain, seq_num)) 
		return False;

	return fetch_cache_entry(domain, CACHE_TYPE_SID, name, sid,
				sizeof(struct winbindd_sid));
}

/* Fetch an individual name cache entry */

BOOL winbindd_fetch_name_cache_entry(struct winbindd_domain *domain, 
                                     char *sid, struct winbindd_name *name)
{
	uint32 seq_num;

	if (lp_winbind_cache_time() == 0) 
		return False;

	seq_num = get_cache_sequence_number(domain, CACHE_TYPE_NAME, sid);

	if (cache_domain_expired(domain, seq_num)) 
		return False;

	return fetch_cache_entry(domain, CACHE_TYPE_NAME, sid, name,
				sizeof(struct winbindd_name));
}

/* Fetch an individual user cache entry */

BOOL winbindd_fetch_user_cache_entry(struct winbindd_domain *domain, 
                                     char *user, struct winbindd_pw *pw)
{
	uint32 seq_num;

	if (lp_winbind_cache_time() == 0) 
		return False;

	seq_num = get_cache_sequence_number(domain, CACHE_TYPE_USER, user);

	if (cache_domain_expired(domain, seq_num)) 
		return False;

	return fetch_cache_entry(domain, CACHE_TYPE_USER, user, pw, 
				sizeof(struct winbindd_pw));
}

/* Fetch an individual uid cache entry */

BOOL winbindd_fetch_uid_cache_entry(struct winbindd_domain *domain, uid_t uid, 
				    struct winbindd_pw *pw)
{
	fstring uidstr;
	uint32 seq_num;

	if (lp_winbind_cache_time() == 0) 
		return False;

	snprintf(uidstr, sizeof(uidstr), "#%u", (unsigned)uid);

	seq_num = get_cache_sequence_number(domain, CACHE_TYPE_USER, uidstr);

	if (cache_domain_expired(domain, seq_num)) 
		return False;

	return fetch_cache_entry(domain, CACHE_TYPE_USER, uidstr, pw, 
				 sizeof(struct winbindd_pw));
}

/* Fetch an individual group cache entry.  This function differs from the
   user cache code as we need to store the group membership data. */

BOOL winbindd_fetch_group_cache_entry(struct winbindd_domain *domain, 
                                      char *group, struct winbindd_gr *gr,
                                      void **extra_data, int *extra_data_len)
{
	TDB_DATA data;
	fstring keystr;
	uint32 seq_num;

	if (lp_winbind_cache_time() == 0) 
		return False;

	seq_num = get_cache_sequence_number(domain, CACHE_TYPE_GROUP, group);

	if (cache_domain_expired(domain, seq_num)) 
		return False;

	/* Fetch group data */

	if (!fetch_cache_entry(domain, CACHE_TYPE_GROUP, group, gr, sizeof(struct winbindd_gr)))
		return False;
	
	/* Fetch extra data */

	snprintf(keystr, sizeof(keystr), "%s/%s/%s DATA", CACHE_TYPE_GROUP, 
				domain->name, group);

	data = tdb_fetch_by_string(cache_tdb, keystr);

	if (!data.dptr) 
		return False;

	/* Extra data freed when data has been sent */

	if (extra_data) 
		*extra_data = data.dptr;

	if (extra_data_len) 
		*extra_data_len = data.dsize;
	
	return True;
}


/* Fetch an individual gid cache entry.  This function differs from the
   user cache code as we need to store the group membership data. */

BOOL winbindd_fetch_gid_cache_entry(struct winbindd_domain *domain, gid_t gid,
				    struct winbindd_gr *gr,
				    void **extra_data, int *extra_data_len)
{
	TDB_DATA data;
	fstring keystr;
	fstring gidstr;
	uint32 seq_num;

	snprintf(gidstr, sizeof(gidstr), "#%u", (unsigned)gid);
	
	if (lp_winbind_cache_time() == 0) 
		return False;

	seq_num = get_cache_sequence_number(domain, CACHE_TYPE_GROUP, gidstr);

	if (cache_domain_expired(domain, seq_num)) 
		return False;

	/* Fetch group data */

	if (!fetch_cache_entry(domain, CACHE_TYPE_GROUP, 
				gidstr, gr, sizeof(struct winbindd_gr)))
		return False;

	/* Fetch extra data */

	snprintf(keystr, sizeof(keystr), "%s/%s/%s DATA", CACHE_TYPE_GROUP, 
				domain->name, gidstr);

	data = tdb_fetch_by_string(cache_tdb, keystr);

	if (!data.dptr) 
		return False;

	/* Extra data freed when data has been sent */

	if (extra_data) 
		*extra_data = data.dptr;

	if (extra_data_len) 
		*extra_data_len = data.dsize;

	return True;
}

/* Flush cache data - easiest to just reopen the tdb */

void winbindd_flush_cache(void)
{
	tdb_close(cache_tdb);
	winbindd_cache_init();
}

/* Print cache status information */

void winbindd_cache_status(void)
{
}