source/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         struct timespec modify_time; /* Info from the directory we're monitoring. */
  27         struct timespec 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 /* Compare struct timespec. */
  36 #define TIMESTAMP_NEQ(x, y) (((x).tv_sec != (y).tv_sec) || ((x).tv_nsec != (y).tv_nsec))
  37
  38 /****************************************************************************
  39  Create the hash we will use to determine if the contents changed.
  40 *****************************************************************************/
  41
  42 static BOOL notify_hash(connection_struct *conn, char *path, uint32 flags,
  43                         struct change_data *data, struct change_data *old_data)
  44 {
  45         SMB_STRUCT_STAT st;
  46         pstring full_name;
  47         char *p;
  48         const char *fname;
  49         size_t remaining_len;
  50         size_t fullname_len;
  51         struct smb_Dir *dp;
  52         long offset;
  53
  54         ZERO_STRUCTP(data);
  55
  56         if(SMB_VFS_STAT(conn,path, &st) == -1)
  57                 return False;
  58
  59         data->modify_time = get_mtimespec(&st);
  60         data->status_time = get_ctimespec(&st);
  61
  62         if (old_data) {
  63                 /*
  64                  * Shortcut to avoid directory scan if the time
  65                  * has changed - we always must return true then.
  66                  */
  67                 if (TIMESTAMP_NEQ(old_data->modify_time, data->modify_time) ||
  68                     TIMESTAMP_NEQ(old_data->status_time, data->status_time) ) {
  69                                 return True;
  70                 }
  71         }
  72
  73         if (S_ISDIR(st.st_mode) &&
  74             (flags & ~(FILE_NOTIFY_CHANGE_FILE_NAME | FILE_NOTIFY_CHANGE_DIR_NAME)) == 0)
  75         {
  76                 /* This is the case of a client wanting to know only when
  77                  * the contents of a directory changes. Since any file
  78                  * creation, rename or deletion will update the directory
  79                  * timestamps, we don't need to create a hash.
  80                  */
  81                 return True;
  82         }
  83
  84         if (lp_change_notify_timeout(SNUM(conn)) <= 0) {
  85                 /* It change notify timeout has been disabled, never scan the directory. */
  86                 return True;
  87         }
  88
  89         /*
  90          * If we are to watch for changes that are only stored
  91          * in inodes of files, not in the directory inode, we must
  92          * scan the directory and produce a unique identifier with
  93          * which we can determine if anything changed. We use the
  94          * modify and change times from all the files in the
  95          * directory, added together (ignoring wrapping if it's
  96          * larger than the max time_t value).
  97          */
  98
  99         dp = OpenDir(conn, path, NULL, 0);
 100         if (dp == NULL)
 101                 return False;
 102
 103         data->num_entries = 0;
 104
 105         pstrcpy(full_name, path);
 106         pstrcat(full_name, "/");
 107
 108         fullname_len = strlen(full_name);
 109         remaining_len = sizeof(full_name) - fullname_len - 1;
 110         p = &full_name[fullname_len];
 111
 112         offset = 0;
 113         while ((fname = ReadDirName(dp, &offset))) {
 114                 SET_STAT_INVALID(st);
 115                 if(strequal(fname, ".") || strequal(fname, ".."))
 116                         continue;
 117
 118                 if (!is_visible_file(conn, path, fname, &st, True))
 119                         continue;
 120
 121                 data->num_entries++;
 122                 safe_strcpy(p, fname, remaining_len);
 123
 124                 /*
 125                  * Do the stat - but ignore errors.
 126                  */
 127                 if (!VALID_STAT(st)) {
 128                         SMB_VFS_STAT(conn,full_name, &st);
 129                 }
 130
 131                 /*
 132                  * Always sum the times.
 133                  */
 134
 135                 data->total_time += (st.st_mtime + st.st_ctime);
 136
 137                 /*
 138                  * If requested hash the names.
 139                  */
 140
 141                 if (flags & (FILE_NOTIFY_CHANGE_DIR_NAME|FILE_NOTIFY_CHANGE_FILE_NAME|FILE_NOTIFY_CHANGE_FILE)) {
 142                         int i;
 143                         unsigned char tmp_hash[16];
 144                         mdfour(tmp_hash, (const unsigned char *)fname, strlen(fname));
 145                         for (i=0;i<16;i++)
 146                                 data->name_hash[i] ^= tmp_hash[i];
 147                 }
 148
 149                 /*
 150                  * If requested sum the mode_t's.
 151                  */
 152
 153                 if (flags & (FILE_NOTIFY_CHANGE_ATTRIBUTES|FILE_NOTIFY_CHANGE_SECURITY))
 154                         data->mode_sum += st.st_mode;
 155         }
 156
 157         CloseDir(dp);
 158
 159         return True;
 160 }
 161
 162 /****************************************************************************
 163  Register a change notify request.
 164 *****************************************************************************/
 165
 166 static void *hash_register_notify(connection_struct *conn, char *path, uint32 flags)
 167 {
 168         struct change_data data;
 169
 170         if (!notify_hash(conn, path, flags, &data, NULL))
 171                 return NULL;
 172
 173         data.last_check_time = time(NULL);
 174
 175         return (void *)memdup(&data, sizeof(data));
 176 }
 177
 178 /****************************************************************************
 179  Check if a change notify should be issued.
 180  A time of zero means instantaneous check - don't modify the last check time.
 181 *****************************************************************************/
 182
 183 static BOOL hash_check_notify(connection_struct *conn, uint16 vuid, char *path, uint32 flags, void *datap, time_t t)
 184 {
 185         struct change_data *data = (struct change_data *)datap;
 186         struct change_data data2;
 187         int cnto = lp_change_notify_timeout(SNUM(conn));
 188
 189         if (t && cnto <= 0) {
 190                 /* Change notify turned off on this share.
 191                  * Only scan when (t==0) - we think something changed. */
 192                 return False;
 193         }
 194
 195         if (t && t < data->last_check_time + cnto) {
 196                 return False;
 197         }
 198
 199         if (!change_to_user(conn,vuid))
 200                 return True;
 201         if (!set_current_service(conn,FLAG_CASELESS_PATHNAMES,True)) {
 202                 change_to_root_user();
 203                 return True;
 204         }
 205
 206         if (!notify_hash(conn, path, flags, &data2, data) ||
 207             TIMESTAMP_NEQ(data2.modify_time, data->modify_time) ||
 208             TIMESTAMP_NEQ(data2.status_time, data->status_time) ||
 209             data2.total_time != data->total_time ||
 210             data2.num_entries != data->num_entries ||
 211                 data2.mode_sum != data->mode_sum ||
 212                 memcmp(data2.name_hash, data->name_hash, sizeof(data2.name_hash))) {
 213                 change_to_root_user();
 214                 return True;
 215         }
 216
 217         if (t) {
 218                 data->last_check_time = t;
 219         }
 220
 221         change_to_root_user();
 222
 223         return False;
 224 }
 225
 226 /****************************************************************************
 227  Remove a change notify data structure.
 228 *****************************************************************************/
 229
 230 static void hash_remove_notify(void *datap)
 231 {
 232         free(datap);
 233 }
 234
 235 /****************************************************************************
 236  Setup hash based change notify.
 237 ****************************************************************************/
 238
 239 struct cnotify_fns *hash_notify_init(void)
 240 {
 241         static struct cnotify_fns cnotify;
 242
 243         cnotify.register_notify = hash_register_notify;
 244         cnotify.check_notify = hash_check_notify;
 245         cnotify.remove_notify = hash_remove_notify;
 246         cnotify.select_time = 60; /* Start with 1 minute default. */
 247         cnotify.notification_fd = -1;
 248
 249         return &cnotify;
 250 }
 251
 252 /*
 253   change_notify_reply_packet(cnbp->request_buf,ERRSRV,ERRaccess);
 254   change_notify_reply_packet(cnbp->request_buf,0,NT_STATUS_NOTIFY_ENUM_DIR);
 255
 256   chain_size = 0;
 257   file_chain_reset();
 258
 259   uint16 vuid = (lp_security() == SEC_SHARE) ? UID_FIELD_INVALID :
 260   SVAL(cnbp->request_buf,smb_uid);
 261 */