source/modules/vfs_expand_msdfs.c

   1 /*
   2  * Expand msdfs targets based on client IP
   3  *
   4  * Copyright (C) Volker Lendecke, 2004
   5  *
   6  * This program is free software; you can redistribute it and/or modify
   7  * it under the terms of the GNU General Public License as published by
   8  * the Free Software Foundation; either version 3 of the License, or
   9  * (at your option) any later version.
  10  *
  11  * This program is distributed in the hope that it will be useful,
  12  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  13  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  14  * GNU General Public License for more details.
  15  *
  16  * You should have received a copy of the GNU General Public License
  17  * along with this program; if not, see <http://www.gnu.org/licenses/>.
  18  */
  19
  20 #include "includes.h"
  21
  22 #undef DBGC_CLASS
  23 #define DBGC_CLASS DBGC_VFS
  24
  25 extern userdom_struct current_user_info;
  26
  27 /**********************************************************
  28   Under mapfile we expect a table of the following format:
  29
  30   IP-Prefix whitespace expansion
  31
  32   For example:
  33   192.168.234 local.samba.org
  34   192.168     remote.samba.org
  35               default.samba.org
  36
  37   This is to redirect a DFS client to a host close to it.
  38 ***********************************************************/
  39
  40 static char *read_target_host(TALLOC_CTX *ctx, const char *mapfile)
  41 {
  42         XFILE *f;
  43         char buf[1024];
  44         char *space = buf;
  45         bool found = false;
  46
  47         f = x_fopen(mapfile, O_RDONLY, 0);
  48
  49         if (f == NULL) {
  50                 DEBUG(0,("can't open IP map %s. Error %s\n",
  51                          mapfile, strerror(errno) ));
  52                 return NULL;
  53         }
  54
  55         DEBUG(10, ("Scanning mapfile [%s]\n", mapfile));
  56
  57         while (x_fgets(buf, sizeof(buf), f) != NULL) {
  58                 char addr[INET6_ADDRSTRLEN];
  59
  60                 if ((strlen(buf) > 0) && (buf[strlen(buf)-1] == '\n'))
  61                         buf[strlen(buf)-1] = '\0';
  62
  63                 DEBUG(10, ("Scanning line [%s]\n", buf));
  64
  65                 space = strchr_m(buf, ' ');
  66
  67                 if (space == NULL) {
  68                         DEBUG(0, ("Ignoring invalid line %s\n", buf));
  69                         continue;
  70                 }
  71
  72                 *space = '\0';
  73
  74                 if (strncmp(client_addr(get_client_fd(),addr,sizeof(addr)),
  75                                 buf, strlen(buf)) == 0) {
  76                         found = true;
  77                         break;
  78                 }
  79         }
  80
  81         x_fclose(f);
  82
  83         if (!found) {
  84                 return NULL;
  85         }
  86
  87         space += 1;
  88
  89         while (isspace(*space))
  90                 space += 1;
  91
  92         return talloc_strdup(ctx, space);
  93 }
  94
  95 /**********************************************************
  96
  97   Expand the msdfs target host using read_target_host
  98   explained above. The syntax used in the msdfs link is
  99
 100   msdfs:@table-filename@/share
 101
 102   Everything between and including the two @-signs is
 103   replaced by the substitution string found in the table
 104   described above.
 105
 106 ***********************************************************/
 107
 108 static char *expand_msdfs_target(TALLOC_CTX *ctx,
 109                                 connection_struct *conn,
 110                                 char *target)
 111 {
 112         char *mapfilename = NULL;
 113         char *filename_start = strchr_m(target, '@');
 114         char *filename_end = NULL;
 115         int filename_len = 0;
 116         char *targethost = NULL;
 117         char *new_target = NULL;
 118
 119         if (filename_start == NULL) {
 120                 DEBUG(10, ("No filename start in %s\n", target));
 121                 return NULL;
 122         }
 123
 124         filename_end = strchr_m(filename_start+1, '@');
 125
 126         if (filename_end == NULL) {
 127                 DEBUG(10, ("No filename end in %s\n", target));
 128                 return NULL;
 129         }
 130
 131         filename_len = PTR_DIFF(filename_end, filename_start+1);
 132         mapfilename = talloc_strdup(ctx, filename_start+1);
 133         if (!mapfilename) {
 134                 return NULL;
 135         }
 136         mapfilename[filename_len] = '\0';
 137
 138         DEBUG(10, ("Expanding from table [%s]\n", mapfilename));
 139
 140         if ((targethost = read_target_host(ctx, mapfilename)) == NULL) {
 141                 DEBUG(1, ("Could not expand target host from file %s\n",
 142                           mapfilename));
 143                 return NULL;
 144         }
 145
 146         targethost = talloc_sub_advanced(ctx,
 147                                 lp_servicename(SNUM(conn)),
 148                                 conn->user,
 149                                 conn->connectpath,
 150                                 conn->gid,
 151                                 get_current_username(),
 152                                 current_user_info.domain,
 153                                 targethost);
 154
 155         DEBUG(10, ("Expanded targethost to %s\n", targethost));
 156
 157         /* Replace the part between '@...@' */
 158         *filename_start = '\0';
 159         new_target = talloc_asprintf(ctx,
 160                                 "%s%s%s",
 161                                 target,
 162                                 targethost,
 163                                 filename_end+1);
 164         if (!new_target) {
 165                 return NULL;
 166         }
 167
 168         DEBUG(10, ("New DFS target: %s\n", new_target));
 169         return new_target;
 170 }
 171
 172 static int expand_msdfs_readlink(struct vfs_handle_struct *handle,
 173                                  const char *path, char *buf, size_t bufsiz)
 174 {
 175         TALLOC_CTX *ctx = talloc_tos();
 176         int result;
 177         char *target = TALLOC_ARRAY(ctx, char, PATH_MAX+1);
 178
 179         if (!target) {
 180                 errno = ENOMEM;
 181                 return -1;
 182         }
 183         result = SMB_VFS_NEXT_READLINK(handle, path, target,
 184                                        PATH_MAX);
 185
 186         if (result < 0)
 187                 return result;
 188
 189         target[result] = '\0';
 190
 191         if ((strncmp(target, "msdfs:", strlen("msdfs:")) == 0) &&
 192             (strchr_m(target, '@') != NULL)) {
 193                 target = expand_msdfs_target(ctx, handle->conn, target);
 194                 if (!target) {
 195                         errno = ENOENT;
 196                         return -1;
 197                 }
 198         }
 199
 200         safe_strcpy(buf, target, bufsiz-1);
 201         return strlen(buf);
 202 }
 203
 204 /* VFS operations structure */
 205
 206 static vfs_op_tuple expand_msdfs_ops[] = {
 207         {SMB_VFS_OP(expand_msdfs_readlink), SMB_VFS_OP_READLINK,
 208          SMB_VFS_LAYER_TRANSPARENT},
 209         {SMB_VFS_OP(NULL), SMB_VFS_OP_NOOP, SMB_VFS_LAYER_NOOP}
 210 };
 211
 212 NTSTATUS vfs_expand_msdfs_init(void);
 213 NTSTATUS vfs_expand_msdfs_init(void)
 214 {
 215         return smb_register_vfs(SMB_VFS_INTERFACE_VERSION, "expand_msdfs",
 216                                 expand_msdfs_ops);
 217 }