/* 
   Unix SMB/Netbios implementation.
   Version 1.9.
   Password and authentication handling
   Copyright (C) Jeremy Allison 1996-1998
   Copyright (C) Luke Kenneth Casson Leighton 1996-1998
      
   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 "includes.h"
#include "nterr.h"

extern int DEBUGLEVEL;

/*
 * This is set on startup - it defines the SID for this
 * machine.
 */

DOM_SID global_machine_sid;

/*
 * NOTE. All these functions are abstracted into a structure
 * that points to the correct function for the selected database. JRA.
 *
 * NOTE.  for the get/mod/add functions, there are two sets of functions.
 * one supports struct sam_passwd, the other supports struct smb_passwd.
 * for speed optimisation it is best to support both these sets.
 * 
 * it is, however, optional to support one set but not the other: there
 * is conversion-capability built in to passdb.c, and run-time error
 * detection for when neither are supported.
 * 
 * password database writers are recommended to implement the sam_passwd
 * functions in a first pass, as struct sam_passwd contains more
 * information, needed by the NT Domain support.
 * 
 * a full example set of derivative functions are listed below.  an API
 * writer is expected to cut/paste these into their module, replace
 * either one set (struct smb_passwd) or the other (struct sam_passwd)
 * OR both, and optionally also to write display info routines
 * (struct sam_disp_info).  lkcl
 *
 */

#if 0
static struct smb_passwd    *getPDBpwent        (void *vp)                              { return pdb_sam_to_smb(getPDB21pwent(vp)); } 
static BOOL                  add_PDBpwd_entry   (struct smb_passwd *newpwd)             { return add_PDB21pwd_entry(pdb_smb_to_sam(newpwd)); } 
static BOOL                  mod_PDBpwd_entry   (struct smb_passwd* pwd, BOOL override) { return mod_PDB21pwd_entry(pdb_smb_to_sam(pwd), override); } 
static struct smb_passwd    *getPDBpwnam        (char *name)                            { return pdb_sam_to_smb(getPDB21pwnam(name)); } 
static struct smb_passwd    *getPDBpwuid        (uid_t smb_userid)                      { return pdb_sam_to_smb(getPDB21pwuid(pdb_uid_to_user_rid(smb_userid))); } 

static struct sam_passwd    *getPDB21pwent      (void *vp)                              { return pdb_smb_to_sam(getPDBpwent(vp)); } 
static BOOL                  add_PDB21pwd_entry (struct sam_passwd *newpwd)             { return add_PDBpwd_entry(pdb_sam_to_smb(newpwd)); } 
static BOOL                  mod_PDB21pwd_entry (struct sam_passwd* pwd, BOOL override) { return mod_PDBpwd_entry(pdb_sam_to_smb(pwd), override); } 
static struct sam_passwd    *getPDB21pwnam      (char *name)                            { return pdb_smb_to_sam(getPDBpwnam(name)); } 
static struct sam_passwd    *getPDB21pwrid      (uint32 rid)                            { return pdb_smb_to_sam(getPDBpwuid(pdb_user_rid_to_uid(rid))); } 
static struct sam_passwd    *getPDB21pwuid      (uid_t uid)                             { return pdb_smb_to_sam(getPDBpwuid(uid)); } 

static struct sam_disp_info *getPDBdispnam      (char *name)                            { return pdb_sam_to_dispinfo(getPDB21pwnam(name)); } 
static struct sam_disp_info *getPDBdisprid      (uint32 rid)                            { return pdb_sam_to_dispinfo(getPDB21pwrid(rid)); } 
static struct sam_disp_info *getPDBdispent      (void *vp)                              { return pdb_sam_to_dispinfo(getPDB21pwent(vp)); } 
#endif /* 0 */

static struct passdb_ops *pdb_ops;

/***************************************************************
 Initialize the password db operations.
***************************************************************/

BOOL initialize_password_db(void)
{
  if (pdb_ops)
  {
    return True;
  }

#ifdef WITH_NISPLUS
  pdb_ops =  nisplus_initialize_password_db();
#elif defined(WITH_LDAP)
  pdb_ops = ldap_initialize_password_db();
#else 
  pdb_ops = file_initialize_password_db();
#endif 

  return (pdb_ops != NULL);
}

/*
 * Functions that return/manipulate a struct smb_passwd.
 */

/************************************************************************
 Utility function to search smb passwd by uid.  use this if your database
 does not have search facilities.
*************************************************************************/

struct smb_passwd *iterate_getsmbpwuid(uid_t smb_userid)
{
	struct smb_passwd *pwd = NULL;
	void *fp = NULL;

	DEBUG(10, ("search by smb_userid: %x\n", (int)smb_userid));

	/* Open the smb password database - not for update. */
	fp = startsmbpwent(False);

	if (fp == NULL)
	{
		DEBUG(0, ("unable to open smb password database.\n"));
		return NULL;
	}

	while ((pwd = getsmbpwent(fp)) != NULL && pwd->smb_userid != smb_userid)
      ;

	if (pwd != NULL)
	{
		DEBUG(10, ("found by smb_userid: %x\n", (int)smb_userid));
	}

	endsmbpwent(fp);
	return pwd;
}

/************************************************************************
 Utility function to search smb passwd by name.  use this if your database
 does not have search facilities.
*************************************************************************/

struct smb_passwd *iterate_getsmbpwnam(char *name)
{
	struct smb_passwd *pwd = NULL;
	void *fp = NULL;

	DEBUG(10, ("search by name: %s\n", name));

	/* Open the sam password file - not for update. */
	fp = startsmbpwent(False);

	if (fp == NULL)
	{
		DEBUG(0, ("unable to open smb password database.\n"));
		return NULL;
	}

	while ((pwd = getsmbpwent(fp)) != NULL && !strequal(pwd->smb_name, name))
      ;

	if (pwd != NULL)
	{
		DEBUG(10, ("found by name: %s\n", name));
	}

	endsmbpwent(fp);
	return pwd;
}

/***************************************************************
 Start to enumerate the smb or sam passwd list. Returns a void pointer
 to ensure no modification outside this module.

 Note that currently it is being assumed that a pointer returned
 from this function may be used to enumerate struct sam_passwd
 entries as well as struct smb_passwd entries. This may need
 to change. JRA.

****************************************************************/

void *startsmbpwent(BOOL update)
{
  return pdb_ops->startsmbpwent(update);
}

/***************************************************************
 End enumeration of the smb or sam passwd list.

 Note that currently it is being assumed that a pointer returned
 from this function may be used to enumerate struct sam_passwd
 entries as well as struct smb_passwd entries. This may need
 to change. JRA.

****************************************************************/

void endsmbpwent(void *vp)
{
  pdb_ops->endsmbpwent(vp);
}

/*************************************************************************
 Routine to return the next entry in the smb passwd list.
 *************************************************************************/

struct smb_passwd *getsmbpwent(void *vp)
{
	return pdb_ops->getsmbpwent(vp);
}

/************************************************************************
 Routine to add an entry to the smb passwd file.
*************************************************************************/

BOOL add_smbpwd_entry(struct smb_passwd *newpwd)
{
 	return pdb_ops->add_smbpwd_entry(newpwd);
}

/************************************************************************
 Routine to search the smb passwd file for an entry matching the username.
 and then modify its password entry. We can't use the startsampwent()/
 getsampwent()/endsampwent() interfaces here as we depend on looking
 in the actual file to decide how much room we have to write data.
 override = False, normal
 override = True, override XXXXXXXX'd out password or NO PASS
************************************************************************/

BOOL mod_smbpwd_entry(struct smb_passwd* pwd, BOOL override)
{
 	return pdb_ops->mod_smbpwd_entry(pwd, override);
}

/************************************************************************
 Routine to search smb passwd by name.
*************************************************************************/

struct smb_passwd *getsmbpwnam(char *name)
{
	return pdb_ops->getsmbpwnam(name);
}

/************************************************************************
 Routine to search smb passwd by uid.
*************************************************************************/

struct smb_passwd *getsmbpwuid(uid_t smb_userid)
{
	return pdb_ops->getsmbpwuid(smb_userid);
}

/*
 * Functions that manupulate a struct sam_passwd.
 */

/************************************************************************
 Utility function to search sam passwd by name.  use this if your database
 does not have search facilities.
*************************************************************************/

struct sam_passwd *iterate_getsam21pwnam(char *name)
{
	struct sam_passwd *pwd = NULL;
	void *fp = NULL;

	DEBUG(10, ("search by name: %s\n", name));

	/* Open the smb password database - not for update. */
	fp = startsmbpwent(False);

	if (fp == NULL)
	{
		DEBUG(0, ("unable to open sam password database.\n"));
		return NULL;
	}

	while ((pwd = getsam21pwent(fp)) != NULL && !strequal(pwd->smb_name, name))
	{
		DEBUG(10, ("iterate: %s 0x%x\n", pwd->smb_name, pwd->user_rid));
	}

	if (pwd != NULL)
	{
		DEBUG(10, ("found by name: %s\n", name));
	}

	endsmbpwent(fp);
	return pwd;
}

/************************************************************************
 Utility function to search sam passwd by rid.  use this if your database
 does not have search facilities.

 search capability by both rid and uid are needed as the rid <-> uid
 mapping may be non-monotonic.  

*************************************************************************/

struct sam_passwd *iterate_getsam21pwrid(uint32 rid)
{
	struct sam_passwd *pwd = NULL;
	void *fp = NULL;

	DEBUG(10, ("search by rid: %x\n", rid));

	/* Open the smb password file - not for update. */
	fp = startsmbpwent(False);

	if (fp == NULL)
	{
		DEBUG(0, ("unable to open sam password database.\n"));
		return NULL;
	}

	while ((pwd = getsam21pwent(fp)) != NULL && pwd->user_rid != rid)
	{
		DEBUG(10, ("iterate: %s 0x%x\n", pwd->smb_name, pwd->user_rid));
	}

	if (pwd != NULL)
	{
		DEBUG(10, ("found by user_rid: %x\n", rid));
	}

	endsmbpwent(fp);
	return pwd;
}

/************************************************************************
 Utility function to search sam passwd by uid.  use this if your database
 does not have search facilities.

 search capability by both rid and uid are needed as the rid <-> uid
 mapping may be non-monotonic.  

*************************************************************************/

struct sam_passwd *iterate_getsam21pwuid(uid_t uid)
{
	struct sam_passwd *pwd = NULL;
	void *fp = NULL;

	DEBUG(10, ("search by uid: %x\n", (int)uid));

	/* Open the smb password file - not for update. */
	fp = startsmbpwent(False);

	if (fp == NULL)
	{
		DEBUG(0, ("unable to open sam password database.\n"));
		return NULL;
	}

	while ((pwd = getsam21pwent(fp)) != NULL && pwd->smb_userid != uid)
      ;

	if (pwd != NULL)
	{
		DEBUG(10, ("found by smb_userid: %x\n", (int)uid));
	}

	endsmbpwent(fp);
	return pwd;
}

/*************************************************************************
 Routine to return a display info structure, by rid
 *************************************************************************/
struct sam_disp_info *getsamdisprid(uint32 rid)
{
	return pdb_ops->getsamdisprid(rid);
}

/*************************************************************************
 Routine to return the next entry in the sam passwd list.
 *************************************************************************/

struct sam_passwd *getsam21pwent(void *vp)
{
	return pdb_ops->getsam21pwent(vp);
}


/************************************************************************
 Routine to search sam passwd by name.
*************************************************************************/

struct sam_passwd *getsam21pwnam(char *name)
{
	return pdb_ops->getsam21pwnam(name);
}

/************************************************************************
 Routine to search sam passwd by rid.  
*************************************************************************/

struct sam_passwd *getsam21pwrid(uint32 rid)
{
	return pdb_ops->getsam21pwrid(rid);
}


/**********************************************************
 **********************************************************

 utility routines which are likely to be useful to all password
 databases

 **********************************************************
 **********************************************************/

/*************************************************************
 initialises a struct sam_disp_info.
 **************************************************************/

static void pdb_init_dispinfo(struct sam_disp_info *user)
{
	if (user == NULL) return;
	bzero(user, sizeof(*user));
}

/*************************************************************
 initialises a struct smb_passwd.
 **************************************************************/

void pdb_init_smb(struct smb_passwd *user)
{
	if (user == NULL) return;
	bzero(user, sizeof(*user));
	user->pass_last_set_time    = (time_t)-1;
}

/*************************************************************
 initialises a struct sam_passwd.
 **************************************************************/
void pdb_init_sam(struct sam_passwd *user)
{
	if (user == NULL) return;
	bzero(user, sizeof(*user));
	user->logon_time            = (time_t)-1;
	user->logoff_time           = (time_t)-1;
	user->kickoff_time          = (time_t)-1;
	user->pass_last_set_time    = (time_t)-1;
	user->pass_can_change_time  = (time_t)-1;
	user->pass_must_change_time = (time_t)-1;
}

/*************************************************************************
 Routine to return the next entry in the sam passwd list.
 *************************************************************************/

struct sam_disp_info *pdb_sam_to_dispinfo(struct sam_passwd *user)
{
	static struct sam_disp_info disp_info;

	if (user == NULL) return NULL;

	pdb_init_dispinfo(&disp_info);

	disp_info.smb_name  = user->smb_name;
	disp_info.full_name = user->full_name;
	disp_info.user_rid  = user->user_rid;

	return &disp_info;
}

/*************************************************************
 converts a sam_passwd structure to a smb_passwd structure.
 **************************************************************/

struct smb_passwd *pdb_sam_to_smb(struct sam_passwd *user)
{
	static struct smb_passwd pw_buf;

	if (user == NULL) return NULL;

	pdb_init_smb(&pw_buf);

	pw_buf.smb_userid         = user->smb_userid;
	pw_buf.smb_name           = user->smb_name;
	pw_buf.smb_passwd         = user->smb_passwd;
	pw_buf.smb_nt_passwd      = user->smb_nt_passwd;
	pw_buf.acct_ctrl          = user->acct_ctrl;
	pw_buf.pass_last_set_time = user->pass_last_set_time;

	return &pw_buf;
}


/**********************************************************
 Encode the account control bits into a string.
 length = length of string to encode into (including terminating
 null). length *MUST BE MORE THAN 2* !
 **********************************************************/

char *pdb_encode_acct_ctrl(uint16 acct_ctrl, size_t length)
{
  static fstring acct_str;
  size_t i = 0;

  acct_str[i++] = '[';

  if (acct_ctrl & ACB_PWNOTREQ ) acct_str[i++] = 'N';
  if (acct_ctrl & ACB_DISABLED ) acct_str[i++] = 'D';
  if (acct_ctrl & ACB_HOMDIRREQ) acct_str[i++] = 'H';
  if (acct_ctrl & ACB_TEMPDUP  ) acct_str[i++] = 'T'; 
  if (acct_ctrl & ACB_NORMAL   ) acct_str[i++] = 'U';
  if (acct_ctrl & ACB_MNS      ) acct_str[i++] = 'M';
  if (acct_ctrl & ACB_WSTRUST  ) acct_str[i++] = 'W';
  if (acct_ctrl & ACB_SVRTRUST ) acct_str[i++] = 'S';
  if (acct_ctrl & ACB_AUTOLOCK ) acct_str[i++] = 'L';
  if (acct_ctrl & ACB_PWNOEXP  ) acct_str[i++] = 'X';
  if (acct_ctrl & ACB_DOMTRUST ) acct_str[i++] = 'I';

  for ( ; i < length - 2 ; i++ ) { acct_str[i] = ' '; }

  i = length - 2;
  acct_str[i++] = ']';
  acct_str[i++] = '\0';

  return acct_str;
}     

/**********************************************************
 Decode the account control bits from a string.

 this function breaks coding standards minimum line width of 80 chars.
 reason: vertical line-up code clarity - all case statements fit into
 15 lines, which is more important.
 **********************************************************/

uint16 pdb_decode_acct_ctrl(char *p)
{
	uint16 acct_ctrl = 0;
	BOOL finished = False;

	/*
	 * Check if the account type bits have been encoded after the
	 * NT password (in the form [NDHTUWSLXI]).
	 */

	if (*p != '[') return 0;

	for (p++; *p && !finished; p++)
	{
		switch (*p)
		{
			case 'N': { acct_ctrl |= ACB_PWNOTREQ ; break; /* 'N'o password. */ }
			case 'D': { acct_ctrl |= ACB_DISABLED ; break; /* 'D'isabled. */ }
			case 'H': { acct_ctrl |= ACB_HOMDIRREQ; break; /* 'H'omedir required. */ }
			case 'T': { acct_ctrl |= ACB_TEMPDUP  ; break; /* 'T'emp account. */ } 
			case 'U': { acct_ctrl |= ACB_NORMAL   ; break; /* 'U'ser account (normal). */ } 
			case 'M': { acct_ctrl |= ACB_MNS      ; break; /* 'M'NS logon user account. What is this ? */ } 
			case 'W': { acct_ctrl |= ACB_WSTRUST  ; break; /* 'W'orkstation account. */ } 
			case 'S': { acct_ctrl |= ACB_SVRTRUST ; break; /* 'S'erver account. */ } 
			case 'L': { acct_ctrl |= ACB_AUTOLOCK ; break; /* 'L'ocked account. */ } 
			case 'X': { acct_ctrl |= ACB_PWNOEXP  ; break; /* No 'X'piry on password */ } 
			case 'I': { acct_ctrl |= ACB_DOMTRUST ; break; /* 'I'nterdomain trust account. */ }
            case ' ': { break; }
			case ':':
			case '\n':
			case '\0': 
			case ']':
			default:  { finished = True; }
		}
	}

	return acct_ctrl;
}

/*************************************************************
 Routine to get the 32 hex characters and turn them
 into a 16 byte array.
**************************************************************/
BOOL pdb_gethexpwd(char *p, char *pwd)
{
	int i;
	unsigned char   lonybble, hinybble;
	char           *hexchars = "0123456789ABCDEF";
	char           *p1, *p2;

	for (i = 0; i < 32; i += 2)
	{
		hinybble = toupper(p[i]);
		lonybble = toupper(p[i + 1]);

		p1 = strchr(hexchars, hinybble);
		p2 = strchr(hexchars, lonybble);

		if (!p1 || !p2)
		{
			return (False);
		}

		hinybble = PTR_DIFF(p1, hexchars);
		lonybble = PTR_DIFF(p2, hexchars);

		pwd[i / 2] = (hinybble << 4) | lonybble;
	}
	return (True);
}

/*******************************************************************
 Group and User RID username mapping function
 ********************************************************************/

BOOL pdb_name_to_rid(char *user_name, uint32 *u_rid, uint32 *g_rid)
{
    struct passwd *pw = Get_Pwnam(user_name, False);

	if (u_rid == NULL || g_rid == NULL || user_name == NULL)
	{
		return False;
	}

	if (!pw)
	{
		DEBUG(1,("Username %s is invalid on this system\n", user_name));
		return False;
	}

	if (user_in_list(user_name, lp_domain_guest_users()))
	{
		*u_rid = DOMAIN_USER_RID_GUEST;
	}
	else if (user_in_list(user_name, lp_domain_admin_users()))
	{
		*u_rid = DOMAIN_USER_RID_ADMIN;
	}
	else
	{
		/* turn the unix UID into a Domain RID.  this is what the posix
		   sub-system does (adds 1000 to the uid) */
		*u_rid = pdb_uid_to_user_rid(pw->pw_uid);
	}

	/* absolutely no idea what to do about the unix GID to Domain RID mapping */
	*g_rid = pdb_gid_to_group_rid(pw->pw_gid);

	return True;
}

/****************************************************************************
 Read the machine SID from a file.
****************************************************************************/

static BOOL read_sid_from_file(int fd, char *sid_file)
{   
  fstring fline;
    
  memset(fline, '\0', sizeof(fline));

  if(read(fd, fline, sizeof(fline) -1 ) < 0) {
    DEBUG(0,("unable to read file %s. Error was %s\n",
           sid_file, strerror(errno) ));
    return False;
  }

  /*
   * Convert to the machine SID.
   */

  fline[sizeof(fline)-1] = '\0';
  if(!string_to_sid( &global_machine_sid, fline)) {
    DEBUG(0,("unable to generate machine SID.\n"));
    return False;
  }

  return True;
}

/****************************************************************************
 Generate the global machine sid. Look for the MACHINE.SID file first, if
 not found then look in smb.conf and use it to create the MACHINE.SID file.
****************************************************************************/
BOOL pdb_generate_machine_sid(void)
{
	int fd;
	char *p;
	pstring sid_file;
	fstring sid_string;
	SMB_STRUCT_STAT st;
	uchar raw_sid_data[12];

	pstrcpy(sid_file, lp_smb_passwd_file());
	p = strrchr(sid_file, '/');
	if(p != NULL) {
		*++p = '\0';
	}

	if (!directory_exist(sid_file, NULL)) {
		if (dos_mkdir(sid_file, 0700) != 0) {
			DEBUG(0,("can't create private directory %s : %s\n",
				 sid_file, strerror(errno)));
			return False;
		}
	}

	pstrcat(sid_file, "MACHINE.SID");
    
	if((fd = open(sid_file, O_RDWR | O_CREAT, 0644)) == -1) {
		DEBUG(0,("unable to open or create file %s. Error was %s\n",
			 sid_file, strerror(errno) ));
		return False;
	} 
  
	/*
	 * Check if the file contains data.
	 */
	
	if(sys_fstat( fd, &st) < 0) {
		DEBUG(0,("unable to stat file %s. Error was %s\n",
			 sid_file, strerror(errno) ));
		close(fd);
		return False;
	} 
  
	if(st.st_size > 0) {
		/*
		 * We have a valid SID - read it.
		 */
		if(!read_sid_from_file( fd, sid_file)) {
			DEBUG(0,("unable to read file %s. Error was %s\n",
				 sid_file, strerror(errno) ));
			close(fd);
			return False;
		}
		close(fd);
		return True;
	} 
  
	/*
	 * The file contains no data - we may need to generate our
	 * own sid. Try the lp_domain_sid() first.
	 */
	
	if(*lp_domain_sid())
		fstrcpy( sid_string, lp_domain_sid());
	else {
		/*
		 * Generate the new sid data & turn it into a string.
		 */
		int i;
		generate_random_buffer( raw_sid_data, 12, True);
		
		fstrcpy( sid_string, "S-1-5-21");
		for( i = 0; i < 3; i++) {
			fstring tmp_string;
			slprintf( tmp_string, sizeof(tmp_string) - 1, "-%u", IVAL(raw_sid_data, i*4));
			fstrcat( sid_string, tmp_string);
		}
	} 
	
	fstrcat(sid_string, "\n");
	
	/*
	 * Ensure our new SID is valid.
	 */
	
	if(!string_to_sid( &global_machine_sid, sid_string)) {
		DEBUG(0,("unable to generate machine SID.\n"));
		return False;
	} 
  
	/*
	 * Do an exclusive blocking lock on the file.
	 */
	
	if(!do_file_lock( fd, 60, F_WRLCK)) {
		DEBUG(0,("unable to lock file %s. Error was %s\n",
			 sid_file, strerror(errno) ));
		close(fd);
		return False;
	} 
  
	/*
	 * At this point we have a blocking lock on the SID
	 * file - check if in the meantime someone else wrote
	 * SID data into the file. If so - they were here first,
	 * use their data.
	 */
	
	if(sys_fstat( fd, &st) < 0) {
		DEBUG(0,("unable to stat file %s. Error was %s\n",
			 sid_file, strerror(errno) ));
		close(fd);
		return False;
	} 
  
	if(st.st_size > 0) {
		/*
		 * Unlock as soon as possible to reduce
		 * contention on the exclusive lock.
		 */ 
		do_file_lock( fd, 60, F_UNLCK);
		
		/*
		 * We have a valid SID - read it.
		 */
		
		if(!read_sid_from_file( fd, sid_file)) {
			DEBUG(0,("unable to read file %s. Error was %s\n",
				 sid_file, strerror(errno) ));
			close(fd);
			return False;
		}
		close(fd);
		return True;
	} 
	
	/*
	 * The file is still empty and we have an exlusive lock on it.
	 * Write out out SID data into the file.
	 */
	
	if(fchmod(fd, 0644) < 0) {
		DEBUG(0,("unable to set correct permissions on file %s. \
Error was %s\n", sid_file, strerror(errno) ));
		close(fd);
		return False;
	} 
	
	if(write( fd, sid_string, strlen(sid_string)) != strlen(sid_string)) {
		DEBUG(0,("unable to write file %s. Error was %s\n",
			 sid_file, strerror(errno) ));
		close(fd);
		return False;
	} 
	
	/*
	 * Unlock & exit.
	 */
	
	do_file_lock( fd, 60, F_UNLCK);
	close(fd);
	return True;
}   

/*******************************************************************
 converts UNIX uid to an NT User RID.
 ********************************************************************/

uint32 pdb_uid_to_user_rid(uid_t uid)
{
	return (((((uint32)uid)*RID_MULTIPLIER) + 1000) | USER_RID_TYPE);
}

/*******************************************************************
 converts NT Group RID to a UNIX uid.
 ********************************************************************/

uint32 pdb_gid_to_group_rid(gid_t gid)
{
  return (((((uint32)gid)*RID_MULTIPLIER) + 1000) | GROUP_RID_TYPE);
}

/*******************************************************************
 Decides if a RID is a well known RID.
 ********************************************************************/

static BOOL pdb_rid_is_well_known(uint32 rid)
{
  return (rid < 1000);
}

/*******************************************************************
 Decides if a RID is a user or group RID.
 ********************************************************************/
  
BOOL pdb_rid_is_user(uint32 rid)
{
  /* lkcl i understand that NT attaches an enumeration to a RID
   * such that it can be identified as either a user, group etc
   * type.  there are 5 such categories, and they are documented.
   */
   if(pdb_rid_is_well_known(rid)) {
      /*
       * The only well known user RIDs are DOMAIN_USER_RID_ADMIN
       * and DOMAIN_USER_RID_GUEST.
       */
     if(rid == DOMAIN_USER_RID_ADMIN || rid == DOMAIN_USER_RID_GUEST)
       return True;
   } else if((rid & RID_TYPE_MASK) == USER_RID_TYPE) {
     return True;
   }
   return False;
}