lib/substitute.c

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/* 
   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 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"

extern struct current_user current_user;

fstring local_machine="";
fstring remote_arch="UNKNOWN";
userdom_struct current_user_info;
fstring remote_proto="UNKNOWN";

static fstring remote_machine;
static fstring smb_user_name;

/** 
 * 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
 */

void set_local_machine_name(const char* local_name, BOOL perm)
{
        static BOOL already_perm = False;
        fstring tmp_local_machine;

        fstrcpy(tmp_local_machine,local_name);
        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") )  {
                fstrcpy( local_machine, client_socket_addr() );
                return;
        }

        if (already_perm)
                return;

        already_perm = perm;

        alpha_strcpy(local_machine,tmp_local_machine,SAFE_NETBIOS_CHARS,sizeof(local_machine)-1);
        strlower_m(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
 */

void set_remote_machine_name(const char* remote_name, BOOL perm)
{
        static BOOL already_perm = False;
        fstring tmp_remote_machine;

        if (already_perm)
                return;

        already_perm = perm;

        fstrcpy(tmp_remote_machine,remote_name);
        trim_char(tmp_remote_machine,' ',' ');
        alpha_strcpy(remote_machine,tmp_remote_machine,SAFE_NETBIOS_CHARS,sizeof(remote_machine)-1);
        strlower_m(remote_machine);
}

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

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

        return local_machine;
}

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

void sub_set_smb_name(const char *name)
{
        fstring tmp;
        int len;
        BOOL is_machine_account = False;

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


        fstrcpy( tmp, name );
        trim_char( tmp, ' ', ' ' );
        strlower_m( tmp );

        len = strlen( tmp );

        if ( len == 0 )
                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;
        
        alpha_strcpy( smb_user_name, tmp, SAFE_NETBIOS_CHARS, sizeof(smb_user_name)-1 );

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

char* sub_get_smb_name( void )
{
        return 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_vuid. */
        fstrcpy(smb_user_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 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;
        char *sid_string;
        
        if ( !secrets_fetch_domain_sid( lp_workgroup(), &sid ) ) {
                return NULL;
        }
        
        sid_string = SMB_STRDUP( sid_string_static( &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 );
};

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 char *automount_path(const char *user_name)
{
        static pstring server_path;

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

        pstrcpy(server_path, get_user_home_dir(user_name));

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

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

                if(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):""));
                                pstrcpy(server_path, 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

        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)
{
        static pstring 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)
                pstrcpy(server_name, local_machine_name);
        else
                pstrcpy(server_name, global_myname());
        
#if (defined(HAVE_NETGROUP) && defined (WITH_AUTOMOUNT))

        if (lp_nis_home_map()) {
                int home_server_len;
                char *automount_value = automount_lookup(user_name);
                home_server_len = strcspn(automount_value,":");
                DEBUG(5, ("NIS lookup succeeded.  Home server length: %d\n",home_server_len));
                if (home_server_len > sizeof(pstring))
                        home_server_len = sizeof(pstring);
                strncpy(server_name, automount_value, home_server_len);
                server_name[home_server_len] = '\0';
        }
#endif

        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;
        struct passwd *pass;
        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' :
                        r = SMB_STRDUP(smb_name);
                        if (r == NULL) {
                                goto error;
                        }
                        if ((pass = Get_Pwnam(r))!=NULL) {
                                a_string = realloc_string_sub(a_string, "%G", gidtoname(pass->pw_gid));
                        } 
                        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());
                        break;
                case 'i': 
                        a_string = realloc_string_sub( a_string, "%i", client_socket_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());
                        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", remote_arch);
                        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", SAMBA_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;
                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, *h;

        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':
                        if ((h = get_user_home_dir(user)))
                                a_string = realloc_string_sub(a_string, "%H", 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.
 *  ****************************************************************************/

void standard_sub_conn(connection_struct *conn, char *str, size_t len)
{
        char *s;

        s = alloc_sub_advanced(lp_servicename(SNUM(conn)), conn->user, conn->connectpath,
                               conn->gid, smb_user_name, "", str);

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

---