source3/smbd/notify_hash.c

   1 /*
   2    Unix SMB/CIFS implementation.
   3    change notify handling - hash based implementation
   4    Copyright (C) Jeremy Allison 1994-1998
   5    Copyright (C) Andrew Tridgell 2000
   6
   7    This program is free software; you can redistribute it and/or modify
   8    it under the terms of the GNU General Public License as published by
   9    the Free Software Foundation; either version 2 of the License, or
  10    (at your option) any later version.
  11
  12    This program is distributed in the hope that it will be useful,
  13    but WITHOUT ANY WARRANTY; without even the implied warranty of
  14    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  15    GNU General Public License for more details.
  16
  17    You should have received a copy of the GNU General Public License
  18    along with this program; if not, write to the Free Software
  19    Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
  20 */
  21
  22 #include "includes.h"
  23
  24 struct change_data {
  25         time_t last_check_time; /* time we last checked this entry */
  26         time_t modify_time; /* Info from the directory we're monitoring. */
  27         time_t status_time; /* Info from the directory we're monitoring. */
  28         time_t total_time; /* Total time of all directory entries - don't care if it wraps. */
  29         unsigned int num_entries; /* Zero or the number of files in the directory. */
  30         unsigned int mode_sum;
  31         unsigned char name_hash[16];
  32 };
  33
  34 /****************************************************************************
  35  Create the hash we will use to determine if the contents changed.
  36 *****************************************************************************/
  37
  38 static BOOL notify_hash(connection_struct *conn, char *path, uint32 flags,
  39                         struct change_data *data, struct change_data *old_data)
  40 {
  41         SMB_STRUCT_STAT st;
  42         pstring full_name;
  43         char *p;
  44         const char *fname;
  45         size_t remaining_len;
  46         size_t fullname_len;
  47         void *dp;
  48
  49         ZERO_STRUCTP(data);
  50
  51         if(SMB_VFS_STAT(conn,path, &st) == -1)
  52                 return False;
  53
  54         data->modify_time = st.st_mtime;
  55         data->status_time = st.st_ctime;
  56
  57         if (old_data) {
  58                 /*
  59                  * Shortcut to avoid directory scan if the time
  60                  * has changed - we always must return true then.
  61                  */
  62                 if (old_data->modify_time != data->modify_time ||
  63                         old_data->status_time != data->status_time ) {
  64                                 return True;
  65                 }
  66         }
  67
  68         /*
  69          * If we are to watch for changes that are only stored
  70          * in inodes of files, not in the directory inode, we must
  71          * scan the directory and produce a unique identifier with
  72          * which we can determine if anything changed. We use the
  73          * modify and change times from all the files in the
  74          * directory, added together (ignoring wrapping if it's
  75          * larger than the max time_t value).
  76          */
  77
  78         dp = OpenDir(conn, path, True);
  79         if (dp == NULL)
  80                 return False;
  81
  82         data->num_entries = 0;
  83
  84         pstrcpy(full_name, path);
  85         pstrcat(full_name, "/");
  86
  87         fullname_len = strlen(full_name);
  88         remaining_len = sizeof(full_name) - fullname_len - 1;
  89         p = &full_name[fullname_len];
  90
  91         while ((fname = ReadDirName(dp))) {
  92                 if(strequal(fname, ".") || strequal(fname, ".."))
  93                         continue;
  94
  95                 data->num_entries++;
  96                 safe_strcpy(p, fname, remaining_len);
  97
  98                 ZERO_STRUCT(st);
  99
 100                 /*
 101                  * Do the stat - but ignore errors.
 102                  */
 103                 SMB_VFS_STAT(conn,full_name, &st);
 104
 105                 /*
 106                  * Always sum the times.
 107                  */
 108
 109                 data->total_time += (st.st_mtime + st.st_ctime);
 110
 111                 /*
 112                  * If requested hash the names.
 113                  */
 114
 115                 if (flags & (FILE_NOTIFY_CHANGE_DIR_NAME|FILE_NOTIFY_CHANGE_FILE_NAME|FILE_NOTIFY_CHANGE_FILE)) {
 116                         int i;
 117                         unsigned char tmp_hash[16];
 118                         mdfour(tmp_hash, (const unsigned char *)fname, strlen(fname));
 119                         for (i=0;i<16;i++)
 120                                 data->name_hash[i] ^= tmp_hash[i];
 121                 }
 122
 123                 /*
 124                  * If requested sum the mode_t's.
 125                  */
 126
 127                 if (flags & (FILE_NOTIFY_CHANGE_ATTRIBUTES|FILE_NOTIFY_CHANGE_SECURITY))
 128                         data->mode_sum += st.st_mode;
 129         }
 130
 131         CloseDir(dp);
 132
 133         return True;
 134 }
 135
 136 /****************************************************************************
 137  Register a change notify request.
 138 *****************************************************************************/
 139
 140 static void *hash_register_notify(connection_struct *conn, char *path, uint32 flags)
 141 {
 142         struct change_data data;
 143
 144         if (!notify_hash(conn, path, flags, &data, NULL))
 145                 return NULL;
 146
 147         data.last_check_time = time(NULL);
 148
 149         return (void *)memdup(&data, sizeof(data));
 150 }
 151
 152 /****************************************************************************
 153  Check if a change notify should be issued.
 154  A time of zero means instantaneous check - don't modify the last check time.
 155 *****************************************************************************/
 156
 157 static BOOL hash_check_notify(connection_struct *conn, uint16 vuid, char *path, uint32 flags, void *datap, time_t t)
 158 {
 159         struct change_data *data = (struct change_data *)datap;
 160         struct change_data data2;
 161
 162         if (t && t < data->last_check_time + lp_change_notify_timeout())
 163                 return False;
 164
 165         if (!change_to_user(conn,vuid))
 166                 return True;
 167         if (!set_current_service(conn,True)) {
 168                 change_to_root_user();
 169                 return True;
 170         }
 171
 172         if (!notify_hash(conn, path, flags, &data2, data) ||
 173             data2.modify_time != data->modify_time ||
 174             data2.status_time != data->status_time ||
 175             data2.total_time != data->total_time ||
 176             data2.num_entries != data->num_entries ||
 177                 data2.mode_sum != data->mode_sum ||
 178                 memcmp(data2.name_hash, data->name_hash, sizeof(data2.name_hash))) {
 179                 change_to_root_user();
 180                 return True;
 181         }
 182
 183         if (t)
 184                 data->last_check_time = t;
 185
 186         change_to_root_user();
 187
 188         return False;
 189 }
 190
 191 /****************************************************************************
 192  Remove a change notify data structure.
 193 *****************************************************************************/
 194
 195 static void hash_remove_notify(void *datap)
 196 {
 197         free(datap);
 198 }
 199
 200 /****************************************************************************
 201  Setup hash based change notify.
 202 ****************************************************************************/
 203
 204 struct cnotify_fns *hash_notify_init(void)
 205 {
 206         static struct cnotify_fns cnotify;
 207
 208         cnotify.register_notify = hash_register_notify;
 209         cnotify.check_notify = hash_check_notify;
 210         cnotify.remove_notify = hash_remove_notify;
 211         cnotify.select_time = lp_change_notify_timeout();
 212
 213         return &cnotify;
 214 }
 215
 216 /*
 217   change_notify_reply_packet(cnbp->request_buf,ERRSRV,ERRaccess);
 218   change_notify_reply_packet(cnbp->request_buf,0,NT_STATUS_NOTIFY_ENUM_DIR);
 219
 220   chain_size = 0;
 221   file_chain_reset();
 222
 223   uint16 vuid = (lp_security() == SEC_SHARE) ? UID_FIELD_INVALID :
 224   SVAL(cnbp->request_buf,smb_uid);
 225 */