source/smbd/notify_hash.c

   1 /*
   2    Unix SMB/Netbios implementation.
   3    Version 3.0
   4    change notify handling - hash based implementation
   5    Copyright (C) Jeremy Allison 1994-1998
   6    Copyright (C) Andrew Tridgell 2000
   7
   8    This program is free software; you can redistribute it and/or modify
   9    it under the terms of the GNU General Public License as published by
  10    the Free Software Foundation; either version 2 of the License, or
  11    (at your option) any later version.
  12
  13    This program is distributed in the hope that it will be useful,
  14    but WITHOUT ANY WARRANTY; without even the implied warranty of
  15    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  16    GNU General Public License for more details.
  17
  18    You should have received a copy of the GNU General Public License
  19    along with this program; if not, write to the Free Software
  20    Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
  21 */
  22
  23 #include "includes.h"
  24
  25 struct change_data {
  26         time_t last_check_time; /* time we last checked this entry */
  27         time_t modify_time; /* Info from the directory we're monitoring. */
  28         time_t status_time; /* Info from the directory we're monitoring. */
  29         time_t total_time; /* Total time of all directory entries - don't care if it wraps. */
  30         unsigned int num_entries; /* Zero or the number of files in the directory. */
  31         unsigned int mode_sum;
  32         unsigned char name_hash[16];
  33 };
  34
  35 /****************************************************************************
  36  Create the hash we will use to determine if the contents changed.
  37 *****************************************************************************/
  38
  39 static BOOL notify_hash(connection_struct *conn, char *path, uint32 flags,
  40                         struct change_data *data, struct change_data *old_data)
  41 {
  42         SMB_STRUCT_STAT st;
  43         pstring full_name;
  44         char *p;
  45         char *fname;
  46         size_t remaining_len;
  47         size_t fullname_len;
  48         void *dp;
  49
  50         ZERO_STRUCTP(data);
  51
  52         if(vfs_stat(conn,path, &st) == -1)
  53                 return False;
  54
  55         data->modify_time = st.st_mtime;
  56         data->status_time = st.st_ctime;
  57
  58         if (old_data) {
  59                 /*
  60                  * Shortcut to avoid directory scan if the time
  61                  * has changed - we always must return true then.
  62                  */
  63                 if (old_data->modify_time != data->modify_time ||
  64                         old_data->status_time != data->status_time ) {
  65                                 return True;
  66                 }
  67         }
  68
  69         /*
  70          * If we are to watch for changes that are only stored
  71          * in inodes of files, not in the directory inode, we must
  72          * scan the directory and produce a unique identifier with
  73          * which we can determine if anything changed. We use the
  74          * modify and change times from all the files in the
  75          * directory, added together (ignoring wrapping if it's
  76          * larger than the max time_t value).
  77          */
  78
  79         dp = OpenDir(conn, path, True);
  80         if (dp == NULL)
  81                 return False;
  82
  83         data->num_entries = 0;
  84
  85         pstrcpy(full_name, path);
  86         pstrcat(full_name, "/");
  87
  88         fullname_len = strlen(full_name);
  89         remaining_len = sizeof(full_name) - fullname_len - 1;
  90         p = &full_name[fullname_len];
  91
  92         while ((fname = ReadDirName(dp))) {
  93                 if(strequal(fname, ".") || strequal(fname, ".."))
  94                         continue;
  95
  96                 data->num_entries++;
  97                 safe_strcpy(p, fname, remaining_len);
  98
  99                 ZERO_STRUCT(st);
 100
 101                 /*
 102                  * Do the stat - but ignore errors.
 103                  */
 104                 vfs_stat(conn,full_name, &st);
 105
 106                 /*
 107                  * Always sum the times.
 108                  */
 109
 110                 data->total_time += (st.st_mtime + st.st_ctime);
 111
 112                 /*
 113                  * If requested hash the names.
 114                  */
 115
 116                 if (flags & (FILE_NOTIFY_CHANGE_DIR_NAME|FILE_NOTIFY_CHANGE_FILE_NAME|FILE_NOTIFY_CHANGE_FILE)) {
 117                         int i;
 118                         unsigned char tmp_hash[16];
 119                         mdfour(tmp_hash, (unsigned char *)fname, strlen(fname));
 120                         for (i=0;i<16;i++)
 121                                 data->name_hash[i] ^= tmp_hash[i];
 122                 }
 123
 124                 /*
 125                  * If requested sum the mode_t's.
 126                  */
 127
 128                 if (flags & (FILE_NOTIFY_CHANGE_ATTRIBUTES|FILE_NOTIFY_CHANGE_SECURITY))
 129                         data->mode_sum = st.st_mode;
 130         }
 131
 132         CloseDir(dp);
 133
 134         return True;
 135 }
 136
 137 /****************************************************************************
 138  Register a change notify request.
 139 *****************************************************************************/
 140
 141 static void *hash_register_notify(connection_struct *conn, char *path, uint32 flags)
 142 {
 143         struct change_data data;
 144
 145         if (!notify_hash(conn, path, flags, &data, NULL))
 146                 return NULL;
 147
 148         data.last_check_time = time(NULL);
 149
 150         return (void *)memdup(&data, sizeof(data));
 151 }
 152
 153 /****************************************************************************
 154  Check if a change notify should be issued.
 155  A time of zero means instantaneous check - don't modify the last check time.
 156 *****************************************************************************/
 157
 158 static BOOL hash_check_notify(connection_struct *conn, uint16 vuid, char *path, uint32 flags, void *datap, time_t t)
 159 {
 160         struct change_data *data = (struct change_data *)datap;
 161         struct change_data data2;
 162
 163         if (t && t < data->last_check_time + lp_change_notify_timeout())
 164                 return False;
 165
 166         if (!change_to_user(conn,vuid))
 167                 return True;
 168         if (!set_current_service(conn,True)) {
 169                 change_to_root_user();
 170                 return True;
 171         }
 172
 173         if (!notify_hash(conn, path, flags, &data2, data) ||
 174             data2.modify_time != data->modify_time ||
 175             data2.status_time != data->status_time ||
 176             data2.total_time != data->total_time ||
 177             data2.num_entries != data->num_entries ||
 178                 data2.mode_sum != data->mode_sum ||
 179                 memcmp(data2.name_hash, data->name_hash, sizeof(data2.name_hash))) {
 180                 change_to_root_user();
 181                 return True;
 182         }
 183
 184         if (t)
 185                 data->last_check_time = t;
 186
 187         change_to_root_user();
 188
 189         return False;
 190 }
 191
 192 /****************************************************************************
 193  Remove a change notify data structure.
 194 *****************************************************************************/
 195
 196 static void hash_remove_notify(void *datap)
 197 {
 198         SAFE_FREE(datap);
 199 }
 200
 201 /****************************************************************************
 202  Setup hash based change notify.
 203 ****************************************************************************/
 204
 205 struct cnotify_fns *hash_notify_init(void)
 206 {
 207         static struct cnotify_fns cnotify;
 208
 209         cnotify.register_notify = hash_register_notify;
 210         cnotify.check_notify = hash_check_notify;
 211         cnotify.remove_notify = hash_remove_notify;
 212         cnotify.select_time = lp_change_notify_timeout();
 213
 214         return &cnotify;
 215 }
 216
 217 /*
 218   change_notify_reply_packet(cnbp->request_buf,ERRSRV,ERRaccess);
 219   change_notify_reply_packet(cnbp->request_buf,0,NT_STATUS_NOTIFY_ENUM_DIR);
 220
 221   chain_size = 0;
 222   file_chain_reset();
 223
 224   uint16 vuid = (lp_security() == SEC_SHARE) ? UID_FIELD_INVALID :
 225   SVAL(cnbp->request_buf,smb_uid);
 226 */