--- /dev/null
+/*-*- Mode: C; c-basic-offset: 8; indent-tabs-mode: nil -*-*/
+
+/***
+ This file is part of systemd.
+
+ Copyright 2014 Lennart Poettering
+
+ systemd is free software; you can redistribute it and/or modify it
+ under the terms of the GNU Lesser General Public License as published by
+ the Free Software Foundation; either version 2.1 of the License, or
+ (at your option) any later version.
+
+ systemd is distributed in the hope that it will be useful, but
+ WITHOUT ANY WARRANTY; without even the implied warranty of
+ MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
+ Lesser General Public License for more details.
+
+ You should have received a copy of the GNU Lesser General Public License
+ along with systemd; If not, see <http://www.gnu.org/licenses/>.
+***/
+
+#include "resolved-dns-cache.h"
+
+#define CACHE_MAX 1024
+#define CACHE_TTL_MAX_USEC (10 * USEC_PER_MINUTE)
+
+static void dns_cache_item_free(DnsCacheItem *i) {
+ if (!i)
+ return;
+
+ dns_resource_record_unref(i->rr);
+ free(i);
+}
+
+DEFINE_TRIVIAL_CLEANUP_FUNC(DnsCacheItem*, dns_cache_item_free);
+
+static void dns_cache_item_remove_and_free(DnsCache *c, DnsCacheItem *i) {
+ DnsCacheItem *first;
+
+ assert(c);
+
+ if (!i)
+ return;
+
+ first = hashmap_get(c->rrsets, &i->rr->key);
+ LIST_REMOVE(rrsets, first, i);
+
+ if (first)
+ assert_se(hashmap_replace(c->rrsets, &first->rr->key, first) >= 0);
+ else
+ hashmap_remove(c->rrsets, &i->rr->key);
+
+ prioq_remove(c->expire, i, &i->expire_prioq_idx);
+
+ dns_cache_item_free(i);
+}
+
+void dns_cache_flush(DnsCache *c) {
+ DnsCacheItem *i;
+
+ assert(c);
+
+ while ((i = hashmap_first(c->rrsets)))
+ dns_cache_item_remove_and_free(c, i);
+
+ assert(hashmap_size(c->rrsets) == 0);
+ assert(prioq_size(c->expire) == 0);
+
+ hashmap_free(c->rrsets);
+ c->rrsets = NULL;
+
+ prioq_free(c->expire);
+ c->expire = NULL;
+}
+
+void dns_cache_remove(DnsCache *c, DnsResourceKey *key) {
+ DnsCacheItem *i;
+
+ assert(c);
+ assert(key);
+
+ while ((i = hashmap_get(c->rrsets, &key)))
+ dns_cache_item_remove_and_free(c, i);
+}
+
+static void dns_cache_make_space(DnsCache *c, unsigned add) {
+ assert(c);
+
+ if (add <= 0)
+ return;
+
+ /* Makes space for n new entries. Note that we actually allow
+ * the cache to grow beyond CACHE_MAX, but only when we shall
+ * add more RRs to the cache than CACHE_MAX at once. In that
+ * case the cache will be emptied completely otherwise. */
+
+ for (;;) {
+ _cleanup_(dns_resource_record_unrefp) DnsResourceRecord *rr = NULL;
+ DnsCacheItem *i;
+
+ if (prioq_size(c->expire) <= 0)
+ break;
+
+ if (prioq_size(c->expire) + add < CACHE_MAX)
+ break;
+
+ i = prioq_peek(c->expire);
+ rr = dns_resource_record_ref(i->rr);
+ dns_cache_remove(c, &rr->key);
+ }
+}
+
+void dns_cache_prune(DnsCache *c) {
+ usec_t t = 0;
+
+ assert(c);
+
+ /* Remove all entries that are past their TTL */
+
+ for (;;) {
+ DnsCacheItem *i;
+ usec_t ttl;
+
+ i = prioq_peek(c->expire);
+ if (!i)
+ break;
+
+ ttl = i->rr->ttl * USEC_PER_SEC;
+ if (ttl > CACHE_TTL_MAX_USEC)
+ ttl = CACHE_TTL_MAX_USEC;
+
+ if (t <= 0)
+ t = now(CLOCK_MONOTONIC);
+
+ if (i->timestamp + ttl > t)
+ break;
+
+ dns_cache_remove(c, &i->rr->key);
+ }
+}
+
+static int dns_cache_item_prioq_compare_func(const void *a, const void *b) {
+ usec_t t, z;
+ const DnsCacheItem *x = a, *y = b;
+
+ t = x->timestamp + x->rr->ttl * USEC_PER_SEC;
+ z = y->timestamp + y->rr->ttl * USEC_PER_SEC;
+
+ if (t < z)
+ return -1;
+ if (t > z)
+ return 1;
+ return 0;
+}
+
+static void dns_cache_item_update(DnsCache *c, DnsCacheItem *i, DnsResourceRecord *rr, usec_t timestamp) {
+ assert(c);
+ assert(i);
+ assert(rr);
+
+ if (!i->rrsets_prev) {
+ /* We are the first item in the list, we need to
+ * update the key used in the hashmap */
+
+ assert_se(hashmap_replace(c->rrsets, &rr->key, i) >= 0);
+ }
+
+ dns_resource_record_unref(i->rr);
+ i->rr = dns_resource_record_ref(rr);
+
+ i->timestamp = timestamp;
+
+ prioq_reshuffle(c->expire, i, &i->expire_prioq_idx);
+}
+
+int dns_cache_put(DnsCache *c, DnsResourceRecord *rr, usec_t timestamp) {
+ _cleanup_(dns_cache_item_freep) DnsCacheItem *i = NULL;
+ DnsCacheItem *first = NULL, *existing;
+ int r;
+
+ assert(c);
+ assert(rr);
+
+ /* New TTL is 0? Delete the entry... */
+ if (rr->ttl <= 0) {
+ dns_cache_remove(c, &rr->key);
+ return 0;
+ }
+
+ /* Entry exists already? Update TTL and timestamp */
+ existing = dns_cache_get(c, rr);
+ if (existing) {
+ dns_cache_item_update(c, existing, rr, timestamp);
+ return 0;
+ }
+
+ /* Otherwise, add the new RR */
+ r = prioq_ensure_allocated(&c->expire, dns_cache_item_prioq_compare_func);
+ if (r < 0)
+ return r;
+
+ r = hashmap_ensure_allocated(&c->rrsets, dns_resource_key_hash_func, dns_resource_key_compare_func);
+ if (r < 0)
+ return r;
+
+ dns_cache_make_space(c, 1);
+
+ i = new0(DnsCacheItem, 1);
+ if (!i)
+ return -ENOMEM;
+
+ i->rr = dns_resource_record_ref(rr);
+ i->timestamp = timestamp;
+ i->expire_prioq_idx = PRIOQ_IDX_NULL;
+
+ r = prioq_put(c->expire, i, &i->expire_prioq_idx);
+ if (r < 0)
+ return r;
+
+ first = hashmap_get(c->rrsets, &i->rr->key);
+ if (first) {
+ LIST_PREPEND(rrsets, first, i);
+ assert_se(hashmap_replace(c->rrsets, &first->rr->key, first) >= 0);
+ } else {
+ r = hashmap_put(c->rrsets, &i->rr->key, i);
+ if (r < 0) {
+ prioq_remove(c->expire, i, &i->expire_prioq_idx);
+ return r;
+ }
+ }
+
+ i = NULL;
+
+ return 0;
+}
+
+int dns_cache_put_rrs(DnsCache *c, DnsResourceRecord **rrs, unsigned n_rrs, usec_t timestamp) {
+ unsigned i, added = 0;
+ int r;
+
+ assert(c);
+
+ if (n_rrs <= 0)
+ return 0;
+
+ assert(rrs);
+
+ /* First iteration, delete all matching old RRs, so that we
+ * only keep complete rrsets in place. */
+ for (i = 0; i < n_rrs; i++)
+ dns_cache_remove(c, &rrs[i]->key);
+
+ dns_cache_make_space(c, n_rrs);
+
+ /* Second iteration, add in new RRs */
+ for (added = 0; added < n_rrs; added++) {
+ if (timestamp <= 0)
+ timestamp = now(CLOCK_MONOTONIC);
+
+ r = dns_cache_put(c, rrs[added], timestamp);
+ if (r < 0)
+ goto fail;
+
+ }
+
+ return 0;
+
+fail:
+ /* Adding all RRs failed. Let's clean up what we already
+ * added, just in case */
+
+ for (i = 0; i < added; i++)
+ dns_cache_remove(c, &rrs[i]->key);
+
+ return r;
+}
+
+DnsCacheItem* dns_cache_lookup(DnsCache *c, DnsResourceKey *key) {
+ assert(c);
+ assert(key);
+
+ return hashmap_get(c->rrsets, key);
+}
+
+DnsCacheItem* dns_cache_get(DnsCache *c, DnsResourceRecord *rr) {
+ DnsCacheItem *i;
+
+ assert(c);
+ assert(rr);
+
+ LIST_FOREACH(rrsets, i, hashmap_get(c->rrsets, &rr->key))
+ if (dns_resource_record_equal(i->rr, rr))
+ return i;
+
+ return NULL;
+}
+
+int dns_cache_lookup_many(DnsCache *c, DnsResourceKey *keys, unsigned n_keys, DnsResourceRecord ***rrs) {
+ DnsResourceRecord **p = NULL;
+ size_t allocated = 0, used = 0;
+ unsigned i;
+ int r;
+
+ assert(c);
+ assert(rrs);
+
+ if (n_keys <= 0) {
+ *rrs = NULL;
+ return 0;
+ }
+
+ assert(keys);
+
+ for (i = 0; i < n_keys; i++) {
+ DnsCacheItem *j;
+
+ j = dns_cache_lookup(c, &keys[i]);
+ if (!j) {
+ *rrs = NULL;
+ r = 0;
+ goto fail;
+ }
+
+ LIST_FOREACH(rrsets, j, j) {
+
+ if (!GREEDY_REALLOC(p, allocated, used+1)) {
+ r = -ENOMEM;
+ goto fail;
+ }
+
+ p[used++] = dns_resource_record_ref(j->rr);
+ }
+ }
+
+ *rrs = p;
+ return (int) used;
+
+fail:
+ dns_resource_record_freev(p, used);
+ return r;
+}
~ianmdlvl / elogind.git / blobdiff