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/* SPDX-License-Identifier: LGPL-2.1+ */
#include <errno.h>
#include <string.h>
#include "alloc-util.h"
#include "hashmap.h"
#include "journald-rate-limit.h"
#include "list.h"
#include "random-util.h"
#include "string-util.h"
#include "util.h"
#define POOLS_MAX 5
#define BUCKETS_MAX 127
#define GROUPS_MAX 2047
static const int priority_map[] = {
[LOG_EMERG] = 0,
[LOG_ALERT] = 0,
[LOG_CRIT] = 0,
[LOG_ERR] = 1,
[LOG_WARNING] = 2,
[LOG_NOTICE] = 3,
[LOG_INFO] = 3,
[LOG_DEBUG] = 4
};
typedef struct JournalRateLimitPool JournalRateLimitPool;
typedef struct JournalRateLimitGroup JournalRateLimitGroup;
struct JournalRateLimitPool {
usec_t begin;
unsigned num;
unsigned suppressed;
};
struct JournalRateLimitGroup {
JournalRateLimit *parent;
char *id;
/* Interval is stored to keep track of when the group expires */
usec_t interval;
JournalRateLimitPool pools[POOLS_MAX];
uint64_t hash;
LIST_FIELDS(JournalRateLimitGroup, bucket);
LIST_FIELDS(JournalRateLimitGroup, lru);
};
struct JournalRateLimit {
JournalRateLimitGroup* buckets[BUCKETS_MAX];
JournalRateLimitGroup *lru, *lru_tail;
unsigned n_groups;
uint8_t hash_key[16];
};
JournalRateLimit *journal_rate_limit_new(void) {
JournalRateLimit *r;
r = new0(JournalRateLimit, 1);
if (!r)
return NULL;
random_bytes(r->hash_key, sizeof(r->hash_key));
return r;
}
static void journal_rate_limit_group_free(JournalRateLimitGroup *g) {
assert(g);
if (g->parent) {
assert(g->parent->n_groups > 0);
if (g->parent->lru_tail == g)
g->parent->lru_tail = g->lru_prev;
LIST_REMOVE(lru, g->parent->lru, g);
LIST_REMOVE(bucket, g->parent->buckets[g->hash % BUCKETS_MAX], g);
g->parent->n_groups--;
}
free(g->id);
free(g);
}
void journal_rate_limit_free(JournalRateLimit *r) {
assert(r);
while (r->lru)
journal_rate_limit_group_free(r->lru);
free(r);
}
_pure_ static bool journal_rate_limit_group_expired(JournalRateLimitGroup *g, usec_t ts) {
unsigned i;
assert(g);
for (i = 0; i < POOLS_MAX; i++)
if (g->pools[i].begin + g->interval >= ts)
return false;
return true;
}
static void journal_rate_limit_vacuum(JournalRateLimit *r, usec_t ts) {
assert(r);
/* Makes room for at least one new item, but drop all
* expored items too. */
while (r->n_groups >= GROUPS_MAX ||
(r->lru_tail && journal_rate_limit_group_expired(r->lru_tail, ts)))
journal_rate_limit_group_free(r->lru_tail);
}
static JournalRateLimitGroup* journal_rate_limit_group_new(JournalRateLimit *r, const char *id, usec_t interval, usec_t ts) {
JournalRateLimitGroup *g;
assert(r);
assert(id);
g = new0(JournalRateLimitGroup, 1);
if (!g)
return NULL;
g->id = strdup(id);
if (!g->id)
goto fail;
g->hash = siphash24_string(g->id, r->hash_key);
g->interval = interval;
journal_rate_limit_vacuum(r, ts);
LIST_PREPEND(bucket, r->buckets[g->hash % BUCKETS_MAX], g);
LIST_PREPEND(lru, r->lru, g);
if (!g->lru_next)
r->lru_tail = g;
r->n_groups++;
g->parent = r;
return g;
fail:
journal_rate_limit_group_free(g);
return NULL;
}
static unsigned burst_modulate(unsigned burst, uint64_t available) {
unsigned k;
/* Modulates the burst rate a bit with the amount of available
* disk space */
k = u64log2(available);
/* 1MB */
if (k <= 20)
return burst;
burst = (burst * (k-16)) / 4;
/*
* Example:
*
* <= 1MB = rate * 1
* 16MB = rate * 2
* 256MB = rate * 3
* 4GB = rate * 4
* 64GB = rate * 5
* 1TB = rate * 6
*/
return burst;
}
int journal_rate_limit_test(JournalRateLimit *r, const char *id, usec_t rl_interval, unsigned rl_burst, int priority, uint64_t available) {
uint64_t h;
JournalRateLimitGroup *g;
JournalRateLimitPool *p;
unsigned burst;
usec_t ts;
assert(id);
/* Returns:
*
* 0 → the log message shall be suppressed,
* 1 + n → the log message shall be permitted, and n messages were dropped from the peer before
* < 0 → error
*/
if (!r)
return 1;
ts = now(CLOCK_MONOTONIC);
h = siphash24_string(id, r->hash_key);
g = r->buckets[h % BUCKETS_MAX];
LIST_FOREACH(bucket, g, g)
if (streq(g->id, id))
break;
if (!g) {
g = journal_rate_limit_group_new(r, id, rl_interval, ts);
if (!g)
return -ENOMEM;
} else
g->interval = rl_interval;
if (rl_interval == 0 || rl_burst == 0)
return 1;
burst = burst_modulate(rl_burst, available);
p = &g->pools[priority_map[priority]];
if (p->begin <= 0) {
p->suppressed = 0;
p->num = 1;
p->begin = ts;
return 1;
}
if (p->begin + rl_interval < ts) {
unsigned s;
s = p->suppressed;
p->suppressed = 0;
p->num = 1;
p->begin = ts;
return 1 + s;
}
if (p->num < burst) {
p->num++;
return 1;
}
p->suppressed++;
return 0;
}
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