+++ /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"
-#include "resolved-dns-packet.h"
-
-/* Never cache more than 1K entries */
-#define CACHE_MAX 1024
-
-/* We never keep any item longer than 10min in our cache */
-#define CACHE_TTL_MAX_USEC (10 * USEC_PER_MINUTE)
-
-typedef enum DnsCacheItemType DnsCacheItemType;
-typedef struct DnsCacheItem DnsCacheItem;
-
-enum DnsCacheItemType {
- DNS_CACHE_POSITIVE,
- DNS_CACHE_NODATA,
- DNS_CACHE_NXDOMAIN,
-};
-
-struct DnsCacheItem {
- DnsResourceKey *key;
- DnsResourceRecord *rr;
- usec_t until;
- DnsCacheItemType type;
- unsigned prioq_idx;
- int owner_family;
- union in_addr_union owner_address;
- LIST_FIELDS(DnsCacheItem, by_key);
-};
-
-static void dns_cache_item_free(DnsCacheItem *i) {
- if (!i)
- return;
-
- dns_resource_record_unref(i->rr);
- dns_resource_key_unref(i->key);
- 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->by_key, i->key);
- LIST_REMOVE(by_key, first, i);
-
- if (first)
- assert_se(hashmap_replace(c->by_key, first->key, first) >= 0);
- else
- hashmap_remove(c->by_key, i->key);
-
- prioq_remove(c->by_expiry, i, &i->prioq_idx);
-
- dns_cache_item_free(i);
-}
-
-void dns_cache_flush(DnsCache *c) {
- DnsCacheItem *i;
-
- assert(c);
-
- while ((i = hashmap_first(c->by_key)))
- dns_cache_item_remove_and_free(c, i);
-
- assert(hashmap_size(c->by_key) == 0);
- assert(prioq_size(c->by_expiry) == 0);
-
- hashmap_free(c->by_key);
- c->by_key = NULL;
-
- prioq_free(c->by_expiry);
- c->by_expiry = NULL;
-}
-
-static void dns_cache_remove(DnsCache *c, DnsResourceKey *key) {
- DnsCacheItem *i;
-
- assert(c);
- assert(key);
-
- while ((i = hashmap_get(c->by_key, 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_key_unrefp) DnsResourceKey *key = NULL;
- DnsCacheItem *i;
-
- if (prioq_size(c->by_expiry) <= 0)
- break;
-
- if (prioq_size(c->by_expiry) + add < CACHE_MAX)
- break;
-
- i = prioq_peek(c->by_expiry);
- assert(i);
-
- /* Take an extra reference to the key so that it
- * doesn't go away in the middle of the remove call */
- key = dns_resource_key_ref(i->key);
- dns_cache_remove(c, key);
- }
-}
-
-void dns_cache_prune(DnsCache *c) {
- usec_t t = 0;
-
- assert(c);
-
- /* Remove all entries that are past their TTL */
-
- for (;;) {
- _cleanup_(dns_resource_key_unrefp) DnsResourceKey *key = NULL;
- DnsCacheItem *i;
-
- i = prioq_peek(c->by_expiry);
- if (!i)
- break;
-
- if (t <= 0)
- t = now(CLOCK_BOOTTIME);
-
- if (i->until > t)
- break;
-
- /* Take an extra reference to the key so that it
- * doesn't go away in the middle of the remove call */
- key = dns_resource_key_ref(i->key);
- dns_cache_remove(c, key);
- }
-}
-
-static int dns_cache_item_prioq_compare_func(const void *a, const void *b) {
- const DnsCacheItem *x = a, *y = b;
-
- if (x->until < y->until)
- return -1;
- if (x->until > y->until)
- return 1;
- return 0;
-}
-
-static int dns_cache_init(DnsCache *c) {
- int r;
-
- assert(c);
-
- r = prioq_ensure_allocated(&c->by_expiry, dns_cache_item_prioq_compare_func);
- if (r < 0)
- return r;
-
- r = hashmap_ensure_allocated(&c->by_key, &dns_resource_key_hash_ops);
- if (r < 0)
- return r;
-
- return r;
-}
-
-static int dns_cache_link_item(DnsCache *c, DnsCacheItem *i) {
- DnsCacheItem *first;
- int r;
-
- assert(c);
- assert(i);
-
- r = prioq_put(c->by_expiry, i, &i->prioq_idx);
- if (r < 0)
- return r;
-
- first = hashmap_get(c->by_key, i->key);
- if (first) {
- LIST_PREPEND(by_key, first, i);
- assert_se(hashmap_replace(c->by_key, first->key, first) >= 0);
- } else {
- r = hashmap_put(c->by_key, i->key, i);
- if (r < 0) {
- prioq_remove(c->by_expiry, i, &i->prioq_idx);
- return r;
- }
- }
-
- return 0;
-}
-
-static DnsCacheItem* dns_cache_get(DnsCache *c, DnsResourceRecord *rr) {
- DnsCacheItem *i;
-
- assert(c);
- assert(rr);
-
- LIST_FOREACH(by_key, i, hashmap_get(c->by_key, rr->key))
- if (i->rr && dns_resource_record_equal(i->rr, rr) > 0)
- return i;
-
- return NULL;
-}
-
-static void dns_cache_item_update_positive(DnsCache *c, DnsCacheItem *i, DnsResourceRecord *rr, usec_t timestamp) {
- assert(c);
- assert(i);
- assert(rr);
-
- i->type = DNS_CACHE_POSITIVE;
-
- if (!i->by_key_prev) {
- /* We are the first item in the list, we need to
- * update the key used in the hashmap */
-
- assert_se(hashmap_replace(c->by_key, rr->key, i) >= 0);
- }
-
- dns_resource_record_ref(rr);
- dns_resource_record_unref(i->rr);
- i->rr = rr;
-
- dns_resource_key_unref(i->key);
- i->key = dns_resource_key_ref(rr->key);
-
- i->until = timestamp + MIN(rr->ttl * USEC_PER_SEC, CACHE_TTL_MAX_USEC);
-
- prioq_reshuffle(c->by_expiry, i, &i->prioq_idx);
-}
-
-static int dns_cache_put_positive(
- DnsCache *c,
- DnsResourceRecord *rr,
- usec_t timestamp,
- int owner_family,
- const union in_addr_union *owner_address) {
-
- _cleanup_(dns_cache_item_freep) DnsCacheItem *i = NULL;
- DnsCacheItem *existing;
- int r;
-
- assert(c);
- assert(rr);
- assert(owner_address);
-
- /* New TTL is 0? Delete the entry... */
- if (rr->ttl <= 0) {
- dns_cache_remove(c, rr->key);
- return 0;
- }
-
- if (rr->key->class == DNS_CLASS_ANY)
- return 0;
- if (rr->key->type == DNS_TYPE_ANY)
- return 0;
-
- /* Entry exists already? Update TTL and timestamp */
- existing = dns_cache_get(c, rr);
- if (existing) {
- dns_cache_item_update_positive(c, existing, rr, timestamp);
- return 0;
- }
-
- /* Otherwise, add the new RR */
- r = dns_cache_init(c);
- if (r < 0)
- return r;
-
- dns_cache_make_space(c, 1);
-
- i = new0(DnsCacheItem, 1);
- if (!i)
- return -ENOMEM;
-
- i->type = DNS_CACHE_POSITIVE;
- i->key = dns_resource_key_ref(rr->key);
- i->rr = dns_resource_record_ref(rr);
- i->until = timestamp + MIN(i->rr->ttl * USEC_PER_SEC, CACHE_TTL_MAX_USEC);
- i->prioq_idx = PRIOQ_IDX_NULL;
- i->owner_family = owner_family;
- i->owner_address = *owner_address;
-
- r = dns_cache_link_item(c, i);
- if (r < 0)
- return r;
-
- i = NULL;
- return 0;
-}
-
-static int dns_cache_put_negative(
- DnsCache *c,
- DnsResourceKey *key,
- int rcode,
- usec_t timestamp,
- uint32_t soa_ttl,
- int owner_family,
- const union in_addr_union *owner_address) {
-
- _cleanup_(dns_cache_item_freep) DnsCacheItem *i = NULL;
- int r;
-
- assert(c);
- assert(key);
- assert(owner_address);
-
- dns_cache_remove(c, key);
-
- if (key->class == DNS_CLASS_ANY)
- return 0;
- if (key->type == DNS_TYPE_ANY)
- return 0;
- if (soa_ttl <= 0)
- return 0;
-
- if (!IN_SET(rcode, DNS_RCODE_SUCCESS, DNS_RCODE_NXDOMAIN))
- return 0;
-
- r = dns_cache_init(c);
- if (r < 0)
- return r;
-
- dns_cache_make_space(c, 1);
-
- i = new0(DnsCacheItem, 1);
- if (!i)
- return -ENOMEM;
-
- i->type = rcode == DNS_RCODE_SUCCESS ? DNS_CACHE_NODATA : DNS_CACHE_NXDOMAIN;
- i->key = dns_resource_key_ref(key);
- i->until = timestamp + MIN(soa_ttl * USEC_PER_SEC, CACHE_TTL_MAX_USEC);
- i->prioq_idx = PRIOQ_IDX_NULL;
- i->owner_family = owner_family;
- i->owner_address = *owner_address;
-
- r = dns_cache_link_item(c, i);
- if (r < 0)
- return r;
-
- i = NULL;
- return 0;
-}
-
-int dns_cache_put(
- DnsCache *c,
- DnsQuestion *q,
- int rcode,
- DnsAnswer *answer,
- unsigned max_rrs,
- usec_t timestamp,
- int owner_family,
- const union in_addr_union *owner_address) {
-
- unsigned i;
- int r;
-
- assert(c);
- assert(q);
-
- /* First, delete all matching old RRs, so that we only keep
- * complete by_key in place. */
- for (i = 0; i < q->n_keys; i++)
- dns_cache_remove(c, q->keys[i]);
-
- if (!answer)
- return 0;
-
- for (i = 0; i < answer->n_rrs; i++)
- dns_cache_remove(c, answer->rrs[i]->key);
-
- /* We only care for positive replies and NXDOMAINs, on all
- * other replies we will simply flush the respective entries,
- * and that's it */
-
- if (!IN_SET(rcode, DNS_RCODE_SUCCESS, DNS_RCODE_NXDOMAIN))
- return 0;
-
- /* Make some space for our new entries */
- dns_cache_make_space(c, answer->n_rrs + q->n_keys);
-
- if (timestamp <= 0)
- timestamp = now(CLOCK_BOOTTIME);
-
- /* Second, add in positive entries for all contained RRs */
- for (i = 0; i < MIN(max_rrs, answer->n_rrs); i++) {
- r = dns_cache_put_positive(c, answer->rrs[i], timestamp, owner_family, owner_address);
- if (r < 0)
- goto fail;
- }
-
- /* Third, add in negative entries for all keys with no RR */
- for (i = 0; i < q->n_keys; i++) {
- DnsResourceRecord *soa = NULL;
-
- r = dns_answer_contains(answer, q->keys[i]);
- if (r < 0)
- goto fail;
- if (r > 0)
- continue;
-
- r = dns_answer_find_soa(answer, q->keys[i], &soa);
- if (r < 0)
- goto fail;
- if (r == 0)
- continue;
-
- r = dns_cache_put_negative(c, q->keys[i], rcode, timestamp, MIN(soa->soa.minimum, soa->ttl), owner_family, owner_address);
- 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 < q->n_keys; i++)
- dns_cache_remove(c, q->keys[i]);
- for (i = 0; i < answer->n_rrs; i++)
- dns_cache_remove(c, answer->rrs[i]->key);
-
- return r;
-}
-
-int dns_cache_lookup(DnsCache *c, DnsQuestion *q, int *rcode, DnsAnswer **ret) {
- _cleanup_(dns_answer_unrefp) DnsAnswer *answer = NULL;
- unsigned i, n = 0;
- int r;
- bool nxdomain = false;
-
- assert(c);
- assert(q);
- assert(rcode);
- assert(ret);
-
- if (q->n_keys <= 0) {
- *ret = NULL;
- *rcode = 0;
- return 0;
- }
-
- for (i = 0; i < q->n_keys; i++) {
- DnsCacheItem *j;
-
- if (q->keys[i]->type == DNS_TYPE_ANY ||
- q->keys[i]->class == DNS_CLASS_ANY) {
- /* If we have ANY lookups we simply refresh */
- *ret = NULL;
- *rcode = 0;
- return 0;
- }
-
- j = hashmap_get(c->by_key, q->keys[i]);
- if (!j) {
- /* If one question cannot be answered we need to refresh */
- *ret = NULL;
- *rcode = 0;
- return 0;
- }
-
- LIST_FOREACH(by_key, j, j) {
- if (j->rr)
- n++;
- else if (j->type == DNS_CACHE_NXDOMAIN)
- nxdomain = true;
- }
- }
-
- if (n <= 0) {
- *ret = NULL;
- *rcode = nxdomain ? DNS_RCODE_NXDOMAIN : DNS_RCODE_SUCCESS;
- return 1;
- }
-
- answer = dns_answer_new(n);
- if (!answer)
- return -ENOMEM;
-
- for (i = 0; i < q->n_keys; i++) {
- DnsCacheItem *j;
-
- j = hashmap_get(c->by_key, q->keys[i]);
- LIST_FOREACH(by_key, j, j) {
- if (j->rr) {
- r = dns_answer_add(answer, j->rr);
- if (r < 0)
- return r;
- }
- }
- }
-
- *ret = answer;
- *rcode = DNS_RCODE_SUCCESS;
- answer = NULL;
-
- return n;
-}
-
-int dns_cache_check_conflicts(DnsCache *cache, DnsResourceRecord *rr, int owner_family, const union in_addr_union *owner_address) {
- DnsCacheItem *i, *first;
- bool same_owner = true;
-
- assert(cache);
- assert(rr);
-
- dns_cache_prune(cache);
-
- /* See if there's a cache entry for the same key. If there
- * isn't there's no conflict */
- first = hashmap_get(cache->by_key, rr->key);
- if (!first)
- return 0;
-
- /* See if the RR key is owned by the same owner, if so, there
- * isn't a conflict either */
- LIST_FOREACH(by_key, i, first) {
- if (i->owner_family != owner_family ||
- !in_addr_equal(owner_family, &i->owner_address, owner_address)) {
- same_owner = false;
- break;
- }
- }
- if (same_owner)
- return 0;
-
- /* See if there's the exact same RR in the cache. If yes, then
- * there's no conflict. */
- if (dns_cache_get(cache, rr))
- return 0;
-
- /* There's a conflict */
- return 1;
-}
~ianmdlvl / elogind.git / blobdiff