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[Samba/gbeck.git] / source / passdb / passdb.c

/* 
   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, and therefore the SAM database for which it is
 * responsible.
 */

DOM_SID global_sam_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
 *
 */

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 rid.  
*************************************************************************/

struct smb_passwd *iterate_getsmbpwrid(uint32 user_rid)
{
        return iterate_getsmbpwuid(pdb_user_rid_to_uid(user_rid));
}

/************************************************************************
 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 user rid.
*************************************************************************/

struct smb_passwd *getsmbpwrid(uint32 user_rid)
{
        return pdb_ops->getsmbpwrid(user_rid);
}

/************************************************************************
 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;
}


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

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

        if (user == NULL) return NULL;

        pdb_init_sam(&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;
}

/*******************************************************************
 gets password-database-format time from a string.
 ********************************************************************/

static time_t get_time_from_string(char *p)
{
        int i;

        for (i = 0; i < 8; i++)
        {
                if (p[i] == '\0' || !isxdigit((int)(p[i]&0xFF)))
                break;
        }
        if (i == 8)
        {
                /*
                 * p points at 8 characters of hex digits - 
                 * read into a time_t as the seconds since
                 * 1970 that the password was last changed.
                 */
                return (time_t)strtol((char *)p, NULL, 16);
        }
        return (time_t)-1;
}

/*******************************************************************
 gets password last set time
 ********************************************************************/

time_t pdb_get_last_set_time(char *p)
{
        if (*p && StrnCaseCmp((char *)p, "LCT-", 4))
        {
                return get_time_from_string(p + 4);
        }
        return (time_t)-1;
}


/*******************************************************************
 sets password-database-format time in a string.
 ********************************************************************/
static void set_time_in_string(char *p, int max_len, char *type, time_t t)
{
        slprintf(p, max_len, ":%s-%08X:", type, (uint32)t);
}

/*******************************************************************
 sets logon time
 ********************************************************************/
void pdb_set_logon_time(char *p, int max_len, time_t t)
{
        set_time_in_string(p, max_len, "LNT", t);
}

/*******************************************************************
 sets logoff time
 ********************************************************************/
void pdb_set_logoff_time(char *p, int max_len, time_t t)
{
        set_time_in_string(p, max_len, "LOT", t);
}

/*******************************************************************
 sets kickoff time
 ********************************************************************/
void pdb_set_kickoff_time(char *p, int max_len, time_t t)
{
        set_time_in_string(p, max_len, "KOT", t);
}

/*******************************************************************
 sets password can change time
 ********************************************************************/
void pdb_set_can_change_time(char *p, int max_len, time_t t)
{
        set_time_in_string(p, max_len, "CCT", t);
}

/*******************************************************************
 sets password last set time
 ********************************************************************/
void pdb_set_must_change_time(char *p, int max_len, time_t t)
{
        set_time_in_string(p, max_len, "MCT", t);
}

/*******************************************************************
 sets password last set time
 ********************************************************************/
void pdb_set_last_set_time(char *p, int max_len, time_t t)
{
        set_time_in_string(p, max_len, "LCT", t);
}


/*************************************************************
 Routine to set 32 hex password characters from a 16 byte array.
**************************************************************/
void pdb_sethexpwd(char *p, char *pwd, uint16 acct_ctrl)
{
        if (pwd != NULL)
        {
                int i;
                for (i = 0; i < 16; i++)
                {
                        slprintf(&p[i*2], 33, "%02X", pwd[i]);
                }
        }
        else
        {
                if (IS_BITS_SET_ALL(acct_ctrl, ACB_PWNOTREQ))
                {
                        safe_strcpy(p, "NO PASSWORDXXXXXXXXXXXXXXXXXXXXX", 33);
                }
                else
                {
                        safe_strcpy(p, "XXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXX", 33);
                }
        }
}
/*************************************************************
 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_sam_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_sam_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 need to generate our
         * own sid.
         */
        
        {
                /*
                 * 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_sam_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.
 ********************************************************************/

uid_t pdb_user_rid_to_uid(uint32 user_rid)
{
        return (uid_t)(((user_rid & (~USER_RID_TYPE))- 1000)/RID_MULTIPLIER);
}

/*******************************************************************
 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;
}