source: trunk/server/source3/modules/vfs_expand_msdfs.c

/* 
 * Expand msdfs targets based on client IP
 *
 * Copyright (C) Volker Lendecke, 2004
 *
 * 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/filesys.h"
#include "smbd/smbd.h"
#include "../librpc/gen_ndr/ndr_netlogon.h"
#include "smbd/globals.h"
#include "auth.h"

#undef DBGC_CLASS
#define DBGC_CLASS DBGC_VFS

/**********************************************************
  Under mapfile we expect a table of the following format:

  IP-Prefix whitespace expansion

  For example:
  192.168.234 local.samba.org
  192.168     remote.samba.org
              default.samba.org

  This is to redirect a DFS client to a host close to it.
***********************************************************/

static char *read_target_host(TALLOC_CTX *ctx, const char *mapfile,
                              const char *clientaddr)
{
        XFILE *f;
        char buf[1024];
        char *space = buf;
        bool found = false;

        f = x_fopen(mapfile, O_RDONLY, 0);

        if (f == NULL) {
                DEBUG(0,("can't open IP map %s. Error %s\n",
                         mapfile, strerror(errno) ));
                return NULL;
        }

        DEBUG(10, ("Scanning mapfile [%s]\n", mapfile));

        while (x_fgets(buf, sizeof(buf), f) != NULL) {

                if ((strlen(buf) > 0) && (buf[strlen(buf)-1] == '\n'))
                        buf[strlen(buf)-1] = '\0';

                DEBUG(10, ("Scanning line [%s]\n", buf));

                space = strchr_m(buf, ' ');

                if (space == NULL) {
                        DEBUG(0, ("Ignoring invalid line %s\n", buf));
                        continue;
                }

                *space = '\0';

                if (strncmp(clientaddr, buf, strlen(buf)) == 0) {
                        found = true;
                        break;
                }
        }

        x_fclose(f);

        if (!found) {
                return NULL;
        }

        space += 1;

        while (isspace(*space))
                space += 1;

        return talloc_strdup(ctx, space);
}

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

  Expand the msdfs target host using read_target_host
  explained above. The syntax used in the msdfs link is

  msdfs:@table-filename@/share

  Everything between and including the two @-signs is
  replaced by the substitution string found in the table
  described above.

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

static char *expand_msdfs_target(TALLOC_CTX *ctx,
                                connection_struct *conn,
                                char *target)
{
        char *mapfilename = NULL;
        char *filename_start = strchr_m(target, '@');
        char *filename_end = NULL;
        int filename_len = 0;
        char *targethost = NULL;
        char *new_target = NULL;

        if (filename_start == NULL) {
                DEBUG(10, ("No filename start in %s\n", target));
                return NULL;
        }

        filename_end = strchr_m(filename_start+1, '@');

        if (filename_end == NULL) {
                DEBUG(10, ("No filename end in %s\n", target));
                return NULL;
        }

        filename_len = PTR_DIFF(filename_end, filename_start+1);
        mapfilename = talloc_strdup(ctx, filename_start+1);
        if (!mapfilename) {
                return NULL;
        }
        mapfilename[filename_len] = '\0';

        DEBUG(10, ("Expanding from table [%s]\n", mapfilename));

        targethost = read_target_host(
                ctx, conn->sconn->client_id.addr, mapfilename);
        if (targethost == NULL) {
                DEBUG(1, ("Could not expand target host from file %s\n",
                          mapfilename));
                return NULL;
        }

        targethost = talloc_sub_advanced(ctx,
                                lp_servicename(SNUM(conn)),
                                conn->session_info->unix_name,
                                conn->connectpath,
                                conn->session_info->utok.gid,
                                conn->session_info->sanitized_username,
                                conn->session_info->info3->base.domain.string,
                                targethost);

        DEBUG(10, ("Expanded targethost to %s\n", targethost));

        /* Replace the part between '@...@' */
        *filename_start = '\0';
        new_target = talloc_asprintf(ctx,
                                "%s%s%s",
                                target,
                                targethost,
                                filename_end+1);
        if (!new_target) {
                return NULL;
        }

        DEBUG(10, ("New DFS target: %s\n", new_target));
        return new_target;
}

static int expand_msdfs_readlink(struct vfs_handle_struct *handle,
                                 const char *path, char *buf, size_t bufsiz)
{
        TALLOC_CTX *ctx = talloc_tos();
        int result;
        char *target = TALLOC_ARRAY(ctx, char, PATH_MAX+1);
        size_t len;

        if (!target) {
                errno = ENOMEM;
                return -1;
        }
        if (bufsiz == 0) {
                errno = EINVAL;
                return -1;
        }

        result = SMB_VFS_NEXT_READLINK(handle, path, target,
                                       PATH_MAX);

        if (result <= 0)
                return result;

        target[result] = '\0';

        if ((strncmp(target, "msdfs:", 6) == 0) &&
            (strchr_m(target, '@') != NULL)) {
                target = expand_msdfs_target(ctx, handle->conn, target);
                if (!target) {
                        errno = ENOENT;
                        return -1;
                }
        }

        len = MIN(bufsiz, strlen(target));

        memcpy(buf, target, len);

        TALLOC_FREE(target);
        return len;
}

static struct vfs_fn_pointers vfs_expand_msdfs_fns = {
        .vfs_readlink = expand_msdfs_readlink
};

NTSTATUS vfs_expand_msdfs_init(void);
NTSTATUS vfs_expand_msdfs_init(void)
{
        return smb_register_vfs(SMB_VFS_INTERFACE_VERSION, "expand_msdfs",
                                &vfs_expand_msdfs_fns);
}