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/* Copyright (c) 2003-2004, Roger Dingledine
* Copyright (c) 2004-2006, Roger Dingledine, Nick Mathewson.
* Copyright (c) 2007-2020, The Tor Project, Inc. */
/* See LICENSE for licensing information */
/**
* \file ratelim.c
* \brief Summarize similar messages that would otherwise flood the logs.
**/
#include "lib/log/ratelim.h"
#include "lib/malloc/malloc.h"
#include "lib/string/printf.h"
/** If the rate-limiter <b>lim</b> is ready at <b>now</b>, return the number
* of calls to rate_limit_is_ready (including this one!) since the last time
* rate_limit_is_ready returned nonzero. Otherwise return 0.
* If the call number hits <b>RATELIM_TOOMANY</b> limit, drop a warning
* about this event and stop counting. */
static int
rate_limit_is_ready(ratelim_t *lim, time_t now)
{
if (lim->rate + lim->last_allowed <= now) {
int res = lim->n_calls_since_last_time + 1;
lim->last_allowed = now;
lim->n_calls_since_last_time = 0;
return res;
} else {
if (lim->n_calls_since_last_time <= RATELIM_TOOMANY) {
++lim->n_calls_since_last_time;
}
return 0;
}
}
/** If the rate-limiter <b>lim</b> is ready at <b>now</b>, return a newly
* allocated string indicating how many messages were suppressed, suitable to
* append to a log message. Otherwise return NULL. */
char *
rate_limit_log(ratelim_t *lim, time_t now)
{
int n;
if ((n = rate_limit_is_ready(lim, now))) {
if (n == 1) {
return tor_strdup("");
} else {
char *cp=NULL;
const char *opt_over = (n >= RATELIM_TOOMANY) ? "over " : "";
/* XXXX this is not exactly correct: the messages could have occurred
* any time between the old value of lim->allowed and now. */
tor_asprintf(&cp,
" [%s%d similar message(s) suppressed in last %d seconds]",
opt_over, n-1, lim->rate);
return cp;
}
} else {
return NULL;
}
}
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