/* 

   Unix SMB/CIFS implementation.

   Username handling

   Copyright (C) Andrew Tridgell 1992-1998

   Copyright (C) Jeremy Allison 1997-2001.

   Copyright (C) Andrew Bartlett 2002

   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"

#include "system/passwd.h"

#include "../lib/util/memcache.h"

#include "../lib/util/util_pw.h"

#include "lib/util/string_wrappers.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);

static struct passwd *getpwnam_alloc_cached(TALLOC_CTX *mem_ctx, const char *name)

{

  struct passwd *pw, *for_cache;

  pw = (struct passwd *)memcache_lookup_talloc(

    NULL, GETPWNAM_CACHE, data_blob_string_const_null(name));

  if (pw != NULL) {

    return tcopy_passwd(mem_ctx, pw);

  }

  pw = getpwnam(name);

  if (pw == NULL) {

    return NULL;

  }

  for_cache = tcopy_passwd(talloc_tos(), pw);

  if (for_cache == NULL) {

    return NULL;

  }

  memcache_add_talloc(NULL, GETPWNAM_CACHE,

      data_blob_string_const_null(name), &for_cache);

  return tcopy_passwd(mem_ctx, pw);

}

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

 Flush all cached passwd structs.

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

void flush_pwnam_cache(void)

{

        memcache_flush(NULL, GETPWNAM_CACHE);

}

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

 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 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_username_level() 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 */

  if (!strlower_m(user2)) {

    DEBUG(5,("strlower_m %s failed\n", user2));

    goto done;

  }

  DEBUG(5,("Trying _Get_Pwnam(), username as lowercase is %s\n",user2));

  ret = getpwnam_alloc_cached(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_cached(mem_ctx, user);

    if(ret)

      goto done;

  }

  /* Try as uppercase, if username wasn't originally uppercase */

  if (!strupper_m(user2)) {

    goto done;

  }

  if(strcmp(user, user2) != 0) {

    DEBUG(5,("Trying _Get_Pwnam(), username as uppercase is %s\n",

       user2));

    ret = getpwnam_alloc_cached(mem_ctx, user2);

    if(ret)

      goto done;

  }

  /* Try all combinations up to usernamelevel */

  if (!strlower_m(user2)) {

    DEBUG(5,("strlower_m %s failed\n", user2));

    goto done;

  }

  DEBUG(5,("Checking combinations of %d uppercase letters in %s\n",

     lp_username_level(), user2));

  ret = uname_string_combinations(user2, mem_ctx, getpwnam_alloc_cached,

          lp_username_level());

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;

  if ( *user == '\0' ) {

    DEBUG(10,("Get_Pwnam: empty username!\n"));

    return NULL;

  }

  fstrcpy(user2, user);

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

  return Get_Pwnam_internals(mem_ctx, user, user2);

}

/* 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_m((int)c))

      continue;

    s[i] = toupper_m(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);

}