source: branches/samba-3.3.x/source/lib/username.c

/* 
   Unix SMB/CIFS implementation.
   Username handling
   Copyright (C) Andrew Tridgell 1992-1998
   Copyright (C) Jeremy Allison 1997-2001.
   
   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 3 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, see <http://www.gnu.org/licenses/>.
*/

#include "includes.h"

/* internal functions */
static struct passwd *uname_string_combinations(char *s, TALLOC_CTX *mem_ctx,
                                                struct passwd * (*fn) (TALLOC_CTX *mem_ctx, const char *),
                                                int N);
static struct passwd *uname_string_combinations2(char *s, TALLOC_CTX *mem_ctx, int offset,
                                                 struct passwd * (*fn) (TALLOC_CTX *mem_ctx, const char *),
                                                 int N);

/****************************************************************************
 Get a users home directory.
****************************************************************************/

char *get_user_home_dir(TALLOC_CTX *mem_ctx, const char *user)
{
        struct passwd *pass;
        char *result;

        /* Ensure the user exists. */

        pass = Get_Pwnam_alloc(mem_ctx, user);

        if (!pass)
                return(NULL);

        /* Return home directory from struct passwd. */

        result = talloc_move(mem_ctx, &pass->pw_dir);

        TALLOC_FREE(pass);
        return result;
}

/****************************************************************************
 * A wrapper for sys_getpwnam().  The following variations are tried:
 *   - as transmitted
 *   - in all lower case if this differs from transmitted
 *   - in all upper case if this differs from transmitted
 *   - using lp_usernamelevel() for permutations.
****************************************************************************/

static struct passwd *Get_Pwnam_internals(TALLOC_CTX *mem_ctx,
                                          const char *user, char *user2)
{
        struct passwd *ret = NULL;

        if (!user2 || !(*user2))
                return(NULL);

        if (!user || !(*user))
                return(NULL);

        /* Try in all lower case first as this is the most 
           common case on UNIX systems */
        strlower_m(user2);
        DEBUG(5,("Trying _Get_Pwnam(), username as lowercase is %s\n",user2));
        ret = getpwnam_alloc(mem_ctx, user2);
        if(ret)
                goto done;

        /* Try as given, if username wasn't originally lowercase */
        if(strcmp(user, user2) != 0) {
                DEBUG(5,("Trying _Get_Pwnam(), username as given is %s\n",
                         user));
                ret = getpwnam_alloc(mem_ctx, user);
                if(ret)
                        goto done;
        }

        /* Try as uppercase, if username wasn't originally uppercase */
        strupper_m(user2);
        if(strcmp(user, user2) != 0) {
                DEBUG(5,("Trying _Get_Pwnam(), username as uppercase is %s\n",
                         user2));
                ret = getpwnam_alloc(mem_ctx, user2);
                if(ret)
                        goto done;
        }

        /* Try all combinations up to usernamelevel */
        strlower_m(user2);
        DEBUG(5,("Checking combinations of %d uppercase letters in %s\n",
                 lp_usernamelevel(), user2));
        ret = uname_string_combinations(user2, mem_ctx, getpwnam_alloc,
                                        lp_usernamelevel());

done:
        DEBUG(5,("Get_Pwnam_internals %s find user [%s]!\n",ret ?
                 "did":"didn't", user));

        return ret;
}

/****************************************************************************
 Get_Pwnam wrapper without modification.
  NOTE: This with NOT modify 'user'! 
  This will return an allocated structure
****************************************************************************/

struct passwd *Get_Pwnam_alloc(TALLOC_CTX *mem_ctx, const char *user)
{
        fstring user2;
        struct passwd *ret;

        if ( *user == '\0' ) {
                DEBUG(10,("Get_Pwnam: empty username!\n"));
                return NULL;
        }

        fstrcpy(user2, user);

        DEBUG(5,("Finding user %s\n", user));

        ret = Get_Pwnam_internals(mem_ctx, user, user2);
        
        return ret;  
}

/* The functions below have been taken from password.c and slightly modified */
/****************************************************************************
 Apply a function to upper/lower case combinations
 of a string and return true if one of them returns true.
 Try all combinations with N uppercase letters.
 offset is the first char to try and change (start with 0)
 it assumes the string starts lowercased
****************************************************************************/

static struct passwd *uname_string_combinations2(char *s, TALLOC_CTX *mem_ctx,
                                                 int offset,
                                                 struct passwd *(*fn)(TALLOC_CTX *mem_ctx, const char *),
                                                 int N)
{
        ssize_t len = (ssize_t)strlen(s);
        int i;
        struct passwd *ret;

        if (N <= 0 || offset >= len)
                return(fn(mem_ctx, s));

        for (i=offset;i<(len-(N-1));i++) {
                char c = s[i];
                if (!islower_ascii((int)c))
                        continue;
                s[i] = toupper_ascii(c);
                ret = uname_string_combinations2(s, mem_ctx, i+1, fn, N-1);
                if(ret)
                        return(ret);
                s[i] = c;
        }
        return(NULL);
}

/****************************************************************************
 Apply a function to upper/lower case combinations
 of a string and return true if one of them returns true.
 Try all combinations with up to N uppercase letters.
 offset is the first char to try and change (start with 0)
 it assumes the string starts lowercased
****************************************************************************/

static struct passwd * uname_string_combinations(char *s, TALLOC_CTX *mem_ctx,
                                                 struct passwd * (*fn)(TALLOC_CTX *mem_ctx, const char *),
                                                 int N)
{
        int n;
        struct passwd *ret;

        for (n=1;n<=N;n++) {
                ret = uname_string_combinations2(s,mem_ctx,0,fn,n);
                if(ret)
                        return(ret);
        }  
        return(NULL);
}