source4/samba/server_util.c

   1 /*
   2    Unix SMB/CIFS implementation.
   3
   4    Utility routines
   5
   6    Copyright (C) 2020 Ralph Boehme <slow@samba.org>
   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 3 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, see <http://www.gnu.org/licenses/>.
  20 */
  21
  22 #include "includes.h"
  23 #include "lib/tevent/tevent.h"
  24 #include "lib/util/unix_privs.h"
  25 #include "server_util.h"
  26
  27 struct samba_tevent_trace_state {
  28         size_t events;
  29         time_t last_logsize_check;
  30 };
  31
  32 struct samba_tevent_trace_state *create_samba_tevent_trace_state(
  33         TALLOC_CTX *mem_ctx)
  34 {
  35         return talloc_zero(mem_ctx, struct samba_tevent_trace_state);
  36 }
  37
  38 void samba_tevent_trace_callback(enum tevent_trace_point point,
  39                                  void *private_data)
  40 {
  41         struct samba_tevent_trace_state *state =
  42                 talloc_get_type_abort(private_data,
  43                                       struct samba_tevent_trace_state);
  44         time_t now = time(NULL);
  45         bool do_check_logs = false;
  46         void *priv = NULL;
  47
  48         switch (point) {
  49         case TEVENT_TRACE_BEFORE_WAIT:
  50                 break;
  51         default:
  52                 return;
  53         }
  54
  55         state->events++;
  56
  57         /*
  58          * Throttling by some random numbers. smbd uses a similar logic
  59          * checking every 50 SMB requests. Assuming 4 events per request
  60          * we get to the number of 200.
  61          */
  62         if ((state->events % 200) == 0) {
  63                 do_check_logs = true;
  64         }
  65         /*
  66          * Throttling by some delay, choosing 29 to avoid lockstep with
  67          * the default tevent tickle timer.
  68          */
  69         if ((state->last_logsize_check + 29) < now) {
  70                 do_check_logs = true;
  71         }
  72
  73         if (!do_check_logs) {
  74                 return;
  75         }
  76
  77         /*
  78          * need_to_check_log_size() checks both the number of messages
  79          * that have been logged and if the logging backend is actually
  80          * going to file. We want to bypass the "number of messages"
  81          * check, so we have to call force_check_log_size() before.
  82          */
  83         force_check_log_size();
  84         if (!need_to_check_log_size()) {
  85                 return;
  86         }
  87
  88         priv = root_privileges();
  89         check_log_size();
  90         TALLOC_FREE(priv);
  91
  92         state->last_logsize_check = now;
  93         return;
  94 }