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substitute.c

/* 
   Unix SMB/CIFS implementation.
   string substitution functions
   Copyright (C) Andrew Tridgell 1992-2000
   Copyright (C) Gerald Carter   2006
   
   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"

extern struct current_user current_user;

userdom_struct current_user_info;
fstring remote_proto="UNKNOWN";

/**
 * Set the 'local' machine name
 * @param local_name the name we are being called
 * @param if this is the 'final' name for us, not be be changed again
 */

static char *local_machine;

void free_local_machine_name(void)
{
      SAFE_FREE(local_machine);
}

bool set_local_machine_name(const char *local_name, bool perm)
{
      static bool already_perm = false;
      char *tmp_local_machine = NULL;
      char addr[INET6_ADDRSTRLEN];
      size_t len;

      tmp_local_machine = SMB_STRDUP(local_name);
      if (!tmp_local_machine) {
            return false;
      }
      trim_char(tmp_local_machine,' ',' ');

      /*
       * Windows NT/2k uses "*SMBSERVER" and XP uses "*SMBSERV"
       * arrggg!!!
       */

      if (strequal(tmp_local_machine, "*SMBSERVER") ||
                  strequal(tmp_local_machine, "*SMBSERV") )  {
            SAFE_FREE(local_machine);
            local_machine = SMB_STRDUP(client_socket_addr(get_client_fd(),
                              addr, sizeof(addr)) );
            SAFE_FREE(tmp_local_machine);
            return local_machine ? true : false;
      }

      if (already_perm) {
            return true;
      }

      SAFE_FREE(local_machine);
      len = strlen(tmp_local_machine);
      local_machine = SMB_CALLOC_ARRAY(char, len+1);
      if (!local_machine) {
            SAFE_FREE(tmp_local_machine);
            return false;
      }
      /* alpha_strcpy includes the space for the terminating nul. */
      alpha_strcpy(local_machine,tmp_local_machine,
                  SAFE_NETBIOS_CHARS,len+1);
      strlower_m(local_machine);
      SAFE_FREE(tmp_local_machine);

      already_perm = perm;

      return true;
}

const char *get_local_machine_name(void)
{
      if (!local_machine || !*local_machine) {
            return global_myname();
      }

      return local_machine;
}

/**
 * Set the 'remote' machine name
 * @param remote_name the name our client wants to be called by
 * @param if this is the 'final' name for them, not be be changed again
 */

static char *remote_machine;

bool set_remote_machine_name(const char *remote_name, bool perm)
{
      static bool already_perm = False;
      char *tmp_remote_machine;
      size_t len;

      if (already_perm) {
            return true;
      }

      tmp_remote_machine = SMB_STRDUP(remote_name);
      if (!tmp_remote_machine) {
            return false;
      }
      trim_char(tmp_remote_machine,' ',' ');

      SAFE_FREE(remote_machine);
      len = strlen(tmp_remote_machine);
      remote_machine = SMB_CALLOC_ARRAY(char, len+1);
      if (!remote_machine) {
            SAFE_FREE(tmp_remote_machine);
            return false;
      }

      /* alpha_strcpy includes the space for the terminating nul. */
      alpha_strcpy(remote_machine,tmp_remote_machine,
                  SAFE_NETBIOS_CHARS,len+1);
      strlower_m(remote_machine);
      SAFE_FREE(tmp_remote_machine);

      already_perm = perm;

      return true;
}

const char *get_remote_machine_name(void)
{
      return remote_machine ? remote_machine : "";
}

/*******************************************************************
 Setup the string used by %U substitution.
********************************************************************/

static char *smb_user_name;

void sub_set_smb_name(const char *name)
{
      char *tmp;
      size_t len;
      bool is_machine_account = false;

      /* don't let anonymous logins override the name */
      if (!name || !*name) {
            return;
      }

      tmp = SMB_STRDUP(name);
      if (!tmp) {
            return;
      }
      trim_char(tmp, ' ', ' ');
      strlower_m(tmp);

      len = strlen(tmp);

      if (len == 0) {
            SAFE_FREE(tmp);
            return;
      }

      /* long story but here goes....we have to allow usernames
         ending in '$' as they are valid machine account names.
         So check for a machine account and re-add the '$'
         at the end after the call to alpha_strcpy().   --jerry  */

      if (tmp[len-1] == '$') {
            is_machine_account = True;
      }

      SAFE_FREE(smb_user_name);
      smb_user_name = SMB_CALLOC_ARRAY(char, len+1);
      if (!smb_user_name) {
            SAFE_FREE(tmp);
            return;
      }

      /* alpha_strcpy includes the space for the terminating nul. */
      alpha_strcpy(smb_user_name, tmp,
                  SAFE_NETBIOS_CHARS,
                  len+1);

      SAFE_FREE(tmp);

      if (is_machine_account) {
            len = strlen(smb_user_name);
            smb_user_name[len-1] = '$';
      }
}

static const char *get_smb_user_name(void)
{
      return smb_user_name ? smb_user_name : "";
}

/*******************************************************************
 Setup the strings used by substitutions. Called per packet. Ensure
 %U name is set correctly also.
********************************************************************/

void set_current_user_info(const userdom_struct *pcui)
{
      current_user_info = *pcui;
      /* The following is safe as current_user_info.smb_name
       * has already been sanitised in register_existing_vuid. */

      sub_set_smb_name(current_user_info.smb_name);
}

/*******************************************************************
 Return the current active user name.
*******************************************************************/

const char *get_current_username(void)
{
      if (current_user_info.smb_name[0] == '\0' ) {
            return get_smb_user_name();
      }

      return current_user_info.smb_name;
}

/*******************************************************************
 Given a pointer to a %$(NAME) in p and the whole string in str
 expand it as an environment variable.
 Return a new allocated and expanded string.
 Based on code by Branko Cibej <branko.cibej@hermes.si>
 When this is called p points at the '%' character.
 May substitute multiple occurrencies of the same env var.
********************************************************************/

static char * realloc_expand_env_var(char *str, char *p)
{
      char *envname;
      char *envval;
      char *q, *r;
      int copylen;

      if (p[0] != '%' || p[1] != '$' || p[2] != '(') {
            return str;
      }

      /*
       * Look for the terminating ')'.
       */

      if ((q = strchr_m(p,')')) == NULL) {
            DEBUG(0,("expand_env_var: Unterminated environment variable [%s]\n", p));
            return str;
      }

      /*
       * Extract the name from within the %$(NAME) string.
       */

      r = p + 3;
      copylen = q - r;
      
      /* reserve space for use later add %$() chars */
      if ( (envname = (char *)SMB_MALLOC(copylen + 1 + 4)) == NULL ) {
            return NULL;
      }
      
      strncpy(envname,r,copylen);
      envname[copylen] = '\0';

      if ((envval = getenv(envname)) == NULL) {
            DEBUG(0,("expand_env_var: Environment variable [%s] not set\n", envname));
            SAFE_FREE(envname);
            return str;
      }

      /*
       * Copy the full %$(NAME) into envname so it
       * can be replaced.
       */

      copylen = q + 1 - p;
      strncpy(envname,p,copylen);
      envname[copylen] = '\0';
      r = realloc_string_sub(str, envname, envval);
      SAFE_FREE(envname);
            
      return r;
}

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

static char *longvar_domainsid( void )
{
      DOM_SID sid;
      fstring tmp;
      char *sid_string;
      
      if ( !secrets_fetch_domain_sid( lp_workgroup(), &sid ) ) {
            return NULL;
      }
      
      sid_string = SMB_STRDUP( sid_to_fstring( tmp, &sid ) );
      
      if ( !sid_string ) {
            DEBUG(0,("longvar_domainsid: failed to dup SID string!\n"));
      }
      
      return sid_string;
}

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

struct api_longvar {
      const char *name;
      char* (*fn)( void );
};

static struct api_longvar longvar_table[] = {
      { "DomainSID",          longvar_domainsid },
      { NULL,           NULL }
};

static char *get_longvar_val( const char *varname )
{
      int i;
      
      DEBUG(7,("get_longvar_val: expanding variable [%s]\n", varname));
      
      for ( i=0; longvar_table[i].name; i++ ) {
            if ( strequal( longvar_table[i].name, varname ) ) {
                  return longvar_table[i].fn();
            }
      }
      
      return NULL;
}

/*******************************************************************
 Expand the long smb.conf variable names given a pointer to a %(NAME).
 Return the number of characters by which the pointer should be advanced.
 When this is called p points at the '%' character.
********************************************************************/

static char *realloc_expand_longvar(char *str, char *p)
{
      fstring varname;
      char *value;
      char *q, *r;
      int copylen;

      if ( p[0] != '%' || p[1] != '(' ) {
            return str;
      }

      /* Look for the terminating ')'.*/

      if ((q = strchr_m(p,')')) == NULL) {
            DEBUG(0,("realloc_expand_longvar: Unterminated environment variable [%s]\n", p));
            return str;
      }

      /* Extract the name from within the %(NAME) string.*/

      r = p+2;
      copylen = MIN( (q-r), (sizeof(varname)-1) );
      strncpy(varname, r, copylen);
      varname[copylen] = '\0';

      if ((value = get_longvar_val(varname)) == NULL) {
            DEBUG(0,("realloc_expand_longvar: Variable [%s] not set.  Skipping\n", varname));
            return str;
      }

      /* Copy the full %(NAME) into envname so it can be replaced.*/

      copylen = MIN( (q+1-p),(sizeof(varname)-1) );
      strncpy( varname, p, copylen );
      varname[copylen] = '\0';
      r = realloc_string_sub(str, varname, value);
      SAFE_FREE( value );

      /* skip over the %(varname) */

      return r;
}

/*******************************************************************
 Patch from jkf@soton.ac.uk
 Added this to implement %p (NIS auto-map version of %H)
*******************************************************************/

static const char *automount_path(const char *user_name)
{
      TALLOC_CTX *ctx = talloc_tos();
      const char *server_path;

      /* use the passwd entry as the default */
      /* this will be the default if WITH_AUTOMOUNT is not used or fails */

      server_path = talloc_strdup(ctx, get_user_home_dir(ctx, user_name));
      if (!server_path) {
            return "";
      }

#if (defined(HAVE_NETGROUP) && defined (WITH_AUTOMOUNT))

      if (lp_nis_home_map()) {
            const char *home_path_start;
            char *automount_value = automount_lookup(ctx, user_name);

            if(automount_value && strlen(automount_value) > 0) {
                  home_path_start = strchr_m(automount_value,':');
                  if (home_path_start != NULL) {
                        DEBUG(5, ("NIS lookup succeeded. "
                              "Home path is: %s\n",
                              home_path_start ?
                                    (home_path_start+1):""));
                        server_path = talloc_strdup(ctx,
                                          home_path_start+1);
                  }
            } else {
                  /* NIS key lookup failed: default to
                   * user home directory from password file */
                  DEBUG(5, ("NIS lookup failed. Using Home path from "
                  "passwd file. Home path is: %s\n", server_path ));
            }
      }
#endif

      if (!server_path) {
            server_path = "";
      }
      DEBUG(4,("Home server path: %s\n", server_path));
      return server_path;
}

/*******************************************************************
 Patch from jkf@soton.ac.uk
 This is Luke's original function with the NIS lookup code
 moved out to a separate function.
*******************************************************************/

static const char *automount_server(const char *user_name)
{
      TALLOC_CTX *ctx = talloc_tos();
      const char *server_name;
      const char *local_machine_name = get_local_machine_name();

      /* use the local machine name as the default */
      /* this will be the default if WITH_AUTOMOUNT is not used or fails */
      if (local_machine_name && *local_machine_name) {
            server_name = talloc_strdup(ctx, local_machine_name);
      } else {
            server_name = talloc_strdup(ctx, global_myname());
      }

      if (!server_name) {
            return "";
      }

#if (defined(HAVE_NETGROUP) && defined (WITH_AUTOMOUNT))
      if (lp_nis_home_map()) {
            char *p;
            char *srv;
            char *automount_value = automount_lookup(ctx, user_name);
            if (!automount_value) {
                  return "";
            }
            srv = talloc_strdup(ctx, automount_value);
            p = strchr_m(srv, ':');
            if (!p) {
                  return "";
            }
            *p = '\0';
            server_name = srv;
            DEBUG(5, ("NIS lookup succeeded.  Home server %s\n",
                              server_name));
      }
#endif

      if (!server_name) {
            server_name = "";
      }
      DEBUG(4,("Home server: %s\n", server_name));
      return server_name;
}

/****************************************************************************
 Do some standard substitutions in a string.
 len is the length in bytes of the space allowed in string str. If zero means
 don't allow expansions.
****************************************************************************/

void standard_sub_basic(const char *smb_name, const char *domain_name,
                  char *str, size_t len)
{
      char *s;
      
      if ( (s = alloc_sub_basic( smb_name, domain_name, str )) != NULL ) {
            strncpy( str, s, len );
      }
      
      SAFE_FREE( s );
      
}

/****************************************************************************
 Do some standard substitutions in a string.
 This function will return an allocated string that have to be freed.
****************************************************************************/

char *talloc_sub_basic(TALLOC_CTX *mem_ctx, const char *smb_name,
                   const char *domain_name, const char *str)
{
      char *a, *t;
      
      if ( (a = alloc_sub_basic(smb_name, domain_name, str)) == NULL ) {
            return NULL;
      }
      t = talloc_strdup(mem_ctx, a);
      SAFE_FREE(a);
      return t;
}

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

char *alloc_sub_basic(const char *smb_name, const char *domain_name,
                  const char *str)
{
      char *b, *p, *s, *r, *a_string;
      fstring pidstr, vnnstr;
      char addr[INET6_ADDRSTRLEN];
      const char *local_machine_name = get_local_machine_name();

      /* workaround to prevent a crash while looking at bug #687 */
      
      if (!str) {
            DEBUG(0,("alloc_sub_basic: NULL source string!  This should not happen\n"));
            return NULL;
      }
      
      a_string = SMB_STRDUP(str);
      if (a_string == NULL) {
            DEBUG(0, ("alloc_sub_basic: Out of memory!\n"));
            return NULL;
      }
      
      for (b = s = a_string; (p = strchr_m(s, '%')); s = a_string + (p - b)) {

            r = NULL;
            b = a_string;
            
            switch (*(p+1)) {
            case 'U' : 
                  r = strdup_lower(smb_name);
                  if (r == NULL) {
                        goto error;
                  }
                  a_string = realloc_string_sub(a_string, "%U", r);
                  break;
            case 'G' : {
                  struct passwd *pass;
                  r = SMB_STRDUP(smb_name);
                  if (r == NULL) {
                        goto error;
                  }
                  pass = Get_Pwnam_alloc(talloc_tos(), r);
                  if (pass != NULL) {
                        a_string = realloc_string_sub(
                              a_string, "%G",
                              gidtoname(pass->pw_gid));
                  }
                  TALLOC_FREE(pass);
                  break;
            }
            case 'D' :
                  r = strdup_upper(domain_name);
                  if (r == NULL) {
                        goto error;
                  }
                  a_string = realloc_string_sub(a_string, "%D", r);
                  break;
            case 'I' :
                  a_string = realloc_string_sub(a_string, "%I",
                              client_addr(get_client_fd(),addr, sizeof(addr)));
                  break;
            case 'i': 
                  a_string = realloc_string_sub( a_string, "%i",
                              client_socket_addr(get_client_fd(), addr, sizeof(addr)) );
                  break;
            case 'L' : 
                  if ( StrnCaseCmp(p, "%LOGONSERVER%", strlen("%LOGONSERVER%")) == 0 ) {
                        break;
                  }
                  if (local_machine_name && *local_machine_name) {
                        a_string = realloc_string_sub(a_string, "%L", local_machine_name); 
                  } else {
                        a_string = realloc_string_sub(a_string, "%L", global_myname()); 
                  }
                  break;
            case 'N':
                  a_string = realloc_string_sub(a_string, "%N", automount_server(smb_name));
                  break;
            case 'M' :
                  a_string = realloc_string_sub(a_string, "%M", client_name(get_client_fd()));
                  break;
            case 'R' :
                  a_string = realloc_string_sub(a_string, "%R", remote_proto);
                  break;
            case 'T' :
                  a_string = realloc_string_sub(a_string, "%T", current_timestring(False));
                  break;
            case 'a' :
                  a_string = realloc_string_sub(a_string, "%a",
                              get_remote_arch_str());
                  break;
            case 'd' :
                  slprintf(pidstr,sizeof(pidstr)-1, "%d",(int)sys_getpid());
                  a_string = realloc_string_sub(a_string, "%d", pidstr);
                  break;
            case 'h' :
                  a_string = realloc_string_sub(a_string, "%h", myhostname());
                  break;
            case 'm' :
                  a_string = realloc_string_sub(a_string, "%m", remote_machine);
                  break;
            case 'v' :
                  a_string = realloc_string_sub(a_string, "%v", LIKEWISE_VERSION_STRING);
                  break;
            case 'w' :
                  a_string = realloc_string_sub(a_string, "%w", lp_winbind_separator());
                  break;
            case '$' :
                  a_string = realloc_expand_env_var(a_string, p); /* Expand environment variables */
                  break;
            case '(':
                  a_string = realloc_expand_longvar( a_string, p );
                  break;
            case 'V' :
                  slprintf(vnnstr,sizeof(vnnstr)-1, "%u", get_my_vnn());
                  a_string = realloc_string_sub(a_string, "%V", vnnstr);
                  break;
            default: 
                  break;
            }

            p++;
            SAFE_FREE(r);
            
            if ( !a_string ) {
                  return NULL;
            }
      }

      return a_string;

error:
      SAFE_FREE(a_string);
      return NULL;
}

/****************************************************************************
 Do some specific substitutions in a string.
 This function will return an allocated string that have to be freed.
****************************************************************************/

char *talloc_sub_specified(TALLOC_CTX *mem_ctx,
                  const char *input_string,
                  const char *username,
                  const char *domain,
                  uid_t uid,
                  gid_t gid)
{
      char *a_string;
      char *ret_string = NULL;
      char *b, *p, *s;
      TALLOC_CTX *tmp_ctx;

      if (!(tmp_ctx = talloc_new(mem_ctx))) {
            DEBUG(0, ("talloc_new failed\n"));
            return NULL;
      }

      a_string = talloc_strdup(tmp_ctx, input_string);
      if (a_string == NULL) {
            DEBUG(0, ("talloc_sub_specified: Out of memory!\n"));
            goto done;
      }
      
      for (b = s = a_string; (p = strchr_m(s, '%')); s = a_string + (p - b)) {
            
            b = a_string;
            
            switch (*(p+1)) {
            case 'U' : 
                  a_string = talloc_string_sub(
                        tmp_ctx, a_string, "%U", username);
                  break;
            case 'u' : 
                  a_string = talloc_string_sub(
                        tmp_ctx, a_string, "%u", username);
                  break;
            case 'G' :
                  if (gid != -1) {
                        a_string = talloc_string_sub(
                              tmp_ctx, a_string, "%G",
                              gidtoname(gid));
                  } else {
                        a_string = talloc_string_sub(
                              tmp_ctx, a_string,
                              "%G", "NO_GROUP");
                  }
                  break;
            case 'g' :
                  if (gid != -1) {
                        a_string = talloc_string_sub(
                              tmp_ctx, a_string, "%g",
                              gidtoname(gid));
                  } else {
                        a_string = talloc_string_sub(
                              tmp_ctx, a_string, "%g", "NO_GROUP");
                  }
                  break;
            case 'D' :
                  a_string = talloc_string_sub(tmp_ctx, a_string,
                                         "%D", domain);
                  break;
            case 'N' : 
                  a_string = talloc_string_sub(
                        tmp_ctx, a_string, "%N",
                        automount_server(username)); 
                  break;
            default: 
                  break;
            }

            p++;
            if (a_string == NULL) {
                  goto done;
            }
      }

      /* Watch out, using "mem_ctx" here, so all intermediate stuff goes
       * away with the TALLOC_FREE(tmp_ctx) further down. */

      ret_string = talloc_sub_basic(mem_ctx, username, domain, a_string);

 done:
      TALLOC_FREE(tmp_ctx);
      return ret_string;
}

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

static char *alloc_sub_advanced(const char *servicename, const char *user, 
                   const char *connectpath, gid_t gid, 
                   const char *smb_name, const char *domain_name,
                   const char *str)
{
      char *a_string, *ret_string;
      char *b, *p, *s;

      a_string = SMB_STRDUP(str);
      if (a_string == NULL) {
            DEBUG(0, ("alloc_sub_advanced: Out of memory!\n"));
            return NULL;
      }
      
      for (b = s = a_string; (p = strchr_m(s, '%')); s = a_string + (p - b)) {
            
            b = a_string;
            
            switch (*(p+1)) {
            case 'N' :
                  a_string = realloc_string_sub(a_string, "%N", automount_server(user));
                  break;
            case 'H': {
                  char *h;
                  if ((h = get_user_home_dir(talloc_tos(), user)))
                        a_string = realloc_string_sub(a_string, "%H", h);
                  TALLOC_FREE(h);
                  break;
            }
            case 'P': 
                  a_string = realloc_string_sub(a_string, "%P", connectpath); 
                  break;
            case 'S': 
                  a_string = realloc_string_sub(a_string, "%S", servicename);
                  break;
            case 'g': 
                  a_string = realloc_string_sub(a_string, "%g", gidtoname(gid)); 
                  break;
            case 'u': 
                  a_string = realloc_string_sub(a_string, "%u", user); 
                  break;
                  
                  /* Patch from jkf@soton.ac.uk Left the %N (NIS
                   * server name) in standard_sub_basic as it is
                   * a feature for logon servers, hence uses the
                   * username.  The %p (NIS server path) code is
                   * here as it is used instead of the default
                   * "path =" string in [homes] and so needs the
                   * service name, not the username.  */
            case 'p': 
                  a_string = realloc_string_sub(a_string, "%p",
                                          automount_path(servicename)); 
                  break;
                  
            default: 
                  break;
            }

            p++;
            if (a_string == NULL) {
                  return NULL;
            }
      }

      ret_string = alloc_sub_basic(smb_name, domain_name, a_string);
      SAFE_FREE(a_string);
      return ret_string;
}

/*
 * This obviously is inefficient and needs to be merged into
 * alloc_sub_advanced...
 */

char *talloc_sub_advanced(TALLOC_CTX *mem_ctx,
                    const char *servicename, const char *user,
                    const char *connectpath, gid_t gid,
                    const char *smb_name, const char *domain_name,
                    const char *str)
{
      char *a, *t;

      if (!(a = alloc_sub_advanced(servicename, user, connectpath, gid,
                             smb_name, domain_name, str))) {
            return NULL;
      }
      t = talloc_strdup(mem_ctx, a);
      SAFE_FREE(a);
      return t;
}


void standard_sub_advanced(const char *servicename, const char *user,
                     const char *connectpath, gid_t gid,
                     const char *smb_name, const char *domain_name,
                     char *str, size_t len)
{
      char *s;

      s = alloc_sub_advanced(servicename, user, connectpath,
                         gid, smb_name, domain_name, str);

      if ( s ) {
            strncpy( str, s, len );
            SAFE_FREE( s );
      }
}

/****************************************************************************
 Do some standard substitutions in a string.
****************************************************************************/

char *standard_sub_conn(TALLOC_CTX *ctx, connection_struct *conn, const char *str)
{
      return talloc_sub_advanced(ctx,
                        lp_servicename(SNUM(conn)),
                        conn->user,
                        conn->connectpath,
                        conn->gid,
                        get_smb_user_name(),
                        "",
                        str);
}

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