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Diffstat (limited to 'src/resolve/resolved-dns-cache.c')
-rw-r--r--src/resolve/resolved-dns-cache.c286
1 files changed, 195 insertions, 91 deletions
diff --git a/src/resolve/resolved-dns-cache.c b/src/resolve/resolved-dns-cache.c
index e42af41c78..6ea5d49fc4 100644
--- a/src/resolve/resolved-dns-cache.c
+++ b/src/resolve/resolved-dns-cache.c
@@ -20,6 +20,7 @@
***/
#include "resolved-dns-cache.h"
+#include "resolved-dns-packet.h"
/* Never cache more than 1K entries */
#define CACHE_MAX 1024
@@ -32,6 +33,7 @@ static void dns_cache_item_free(DnsCacheItem *i) {
return;
dns_resource_record_unref(i->rr);
+ dns_resource_key_unref(i->key);
free(i);
}
@@ -45,15 +47,15 @@ static void dns_cache_item_remove_and_free(DnsCache *c, DnsCacheItem *i) {
if (!i)
return;
- first = hashmap_get(c->rrsets, i->rr->key);
- LIST_REMOVE(rrsets, first, i);
+ first = hashmap_get(c->by_key, i->key);
+ LIST_REMOVE(by_key, first, i);
if (first)
- assert_se(hashmap_replace(c->rrsets, first->rr->key, first) >= 0);
+ assert_se(hashmap_replace(c->by_key, first->key, first) >= 0);
else
- hashmap_remove(c->rrsets, i->rr->key);
+ hashmap_remove(c->by_key, i->key);
- prioq_remove(c->expire, i, &i->expire_prioq_idx);
+ prioq_remove(c->by_expiry, i, &i->prioq_idx);
dns_cache_item_free(i);
}
@@ -63,26 +65,26 @@ void dns_cache_flush(DnsCache *c) {
assert(c);
- while ((i = hashmap_first(c->rrsets)))
+ while ((i = hashmap_first(c->by_key)))
dns_cache_item_remove_and_free(c, i);
- assert(hashmap_size(c->rrsets) == 0);
- assert(prioq_size(c->expire) == 0);
+ assert(hashmap_size(c->by_key) == 0);
+ assert(prioq_size(c->by_expiry) == 0);
- hashmap_free(c->rrsets);
- c->rrsets = NULL;
+ hashmap_free(c->by_key);
+ c->by_key = NULL;
- prioq_free(c->expire);
- c->expire = NULL;
+ prioq_free(c->by_expiry);
+ c->by_expiry = NULL;
}
-void dns_cache_remove(DnsCache *c, DnsResourceKey *key) {
+static void dns_cache_remove(DnsCache *c, DnsResourceKey *key) {
DnsCacheItem *i;
assert(c);
assert(key);
- while ((i = hashmap_get(c->rrsets, key)))
+ while ((i = hashmap_get(c->by_key, key)))
dns_cache_item_remove_and_free(c, i);
}
@@ -101,18 +103,18 @@ static void dns_cache_make_space(DnsCache *c, unsigned add) {
_cleanup_(dns_resource_key_unrefp) DnsResourceKey *key = NULL;
DnsCacheItem *i;
- if (prioq_size(c->expire) <= 0)
+ if (prioq_size(c->by_expiry) <= 0)
break;
- if (prioq_size(c->expire) + add < CACHE_MAX)
+ if (prioq_size(c->by_expiry) + add < CACHE_MAX)
break;
- i = prioq_peek(c->expire);
+ 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->rr->key);
+ key = dns_resource_key_ref(i->key);
dns_cache_remove(c, key);
}
}
@@ -127,61 +129,72 @@ void dns_cache_prune(DnsCache *c) {
for (;;) {
_cleanup_(dns_resource_key_unrefp) DnsResourceKey *key = NULL;
DnsCacheItem *i;
- usec_t ttl;
- i = prioq_peek(c->expire);
+ i = prioq_peek(c->by_expiry);
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)
+ 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->rr->key);
+ 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) {
- 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)
+ if (x->until < y->until)
return -1;
- if (t > z)
+ if (x->until > y->until)
return 1;
return 0;
}
-static void dns_cache_item_update(DnsCache *c, DnsCacheItem *i, DnsResourceRecord *rr, usec_t timestamp) {
+static int init_cache(DnsCache *c) {
+ int r;
+
+ 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_func, dns_resource_key_compare_func);
+ 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);
- assert(rr);
- if (!i->rrsets_prev) {
- /* We are the first item in the list, we need to
- * update the key used in the hashmap */
+ r = prioq_put(c->by_expiry, i, &i->prioq_idx);
+ if (r < 0)
+ return r;
- assert_se(hashmap_replace(c->rrsets, rr->key, i) >= 0);
+ 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;
+ }
}
- dns_resource_record_ref(rr);
- dns_resource_record_unref(i->rr);
- i->rr = rr;
-
- i->timestamp = timestamp;
- prioq_reshuffle(c->expire, i, &i->expire_prioq_idx);
+ return 0;
}
static DnsCacheItem* dns_cache_get(DnsCache *c, DnsResourceRecord *rr) {
@@ -190,16 +203,42 @@ static DnsCacheItem* dns_cache_get(DnsCache *c, DnsResourceRecord *rr) {
assert(c);
assert(rr);
- LIST_FOREACH(rrsets, i, hashmap_get(c->rrsets, rr->key))
- if (dns_resource_record_equal(i->rr, rr))
+ LIST_FOREACH(by_key, i, hashmap_get(c->by_key, rr->key))
+ if (i->rr && dns_resource_record_equal(i->rr, rr))
return i;
return NULL;
}
-int dns_cache_put(DnsCache *c, DnsResourceRecord *rr, usec_t timestamp) {
+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) {
_cleanup_(dns_cache_item_freep) DnsCacheItem *i = NULL;
- DnsCacheItem *first = NULL, *existing;
+ DnsCacheItem *existing;
int r;
assert(c);
@@ -214,16 +253,48 @@ int dns_cache_put(DnsCache *c, DnsResourceRecord *rr, usec_t timestamp) {
/* Entry exists already? Update TTL and timestamp */
existing = dns_cache_get(c, rr);
if (existing) {
- dns_cache_item_update(c, existing, rr, timestamp);
+ dns_cache_item_update_positive(c, existing, rr, timestamp);
return 0;
}
/* Otherwise, add the new RR */
- r = prioq_ensure_allocated(&c->expire, dns_cache_item_prioq_compare_func);
+ r = init_cache(c);
if (r < 0)
return r;
- r = hashmap_ensure_allocated(&c->rrsets, dns_resource_key_hash_func, dns_resource_key_compare_func);
+ 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;
+
+ 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) {
+ _cleanup_(dns_cache_item_freep) DnsCacheItem *i = NULL;
+ int r;
+
+ assert(c);
+ assert(key);
+
+ dns_cache_remove(c, key);
+
+ if (!IN_SET(rcode, DNS_RCODE_SUCCESS, DNS_RCODE_NXDOMAIN))
+ return 0;
+
+ r = init_cache(c);
if (r < 0)
return r;
@@ -233,51 +304,70 @@ int dns_cache_put(DnsCache *c, DnsResourceRecord *rr, usec_t timestamp) {
if (!i)
return -ENOMEM;
- i->rr = dns_resource_record_ref(rr);
- i->timestamp = timestamp;
- i->expire_prioq_idx = PRIOQ_IDX_NULL;
+ 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;
- r = prioq_put(c->expire, i, &i->expire_prioq_idx);
+ r = dns_cache_link_item(c, i);
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_answer(DnsCache *c, DnsAnswer *answer, usec_t timestamp) {
- unsigned i, added = 0;
+int dns_cache_put(DnsCache *c, DnsQuestion *q, int rcode, DnsAnswer *answer, usec_t timestamp) {
+ unsigned i;
int r;
assert(c);
assert(answer);
- /* First iteration, delete all matching old RRs, so that we
- * only keep complete rrsets in place. */
+ /* 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]);
for (i = 0; i < answer->n_rrs; i++)
dns_cache_remove(c, answer->rrs[i]->key);
- dns_cache_make_space(c, answer->n_rrs);
+ /* 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);
- /* Second iteration, add in new RRs */
- for (added = 0; added < answer->n_rrs; added++) {
- if (timestamp <= 0)
- timestamp = now(CLOCK_MONOTONIC);
+ if (timestamp <= 0)
+ timestamp = now(CLOCK_MONOTONIC);
- r = dns_cache_put(c, answer->rrs[added], timestamp);
+ /* Second, add in positive entries for all contained RRs */
+ for (i = 0; i < answer->n_rrs; i++) {
+ r = dns_cache_put_positive(c, answer->rrs[i], timestamp);
+ 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));
if (r < 0)
goto fail;
}
@@ -288,16 +378,19 @@ fail:
/* Adding all RRs failed. Let's clean up what we already
* added, just in case */
- for (i = 0; i < added; i++)
+ 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, DnsAnswer **ret) {
+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);
@@ -305,24 +398,34 @@ int dns_cache_lookup(DnsCache *c, DnsQuestion *q, DnsAnswer **ret) {
if (q->n_keys <= 0) {
*ret = NULL;
+ *rcode = 0;
return 0;
}
for (i = 0; i < q->n_keys; i++) {
DnsCacheItem *j;
- j = hashmap_get(c->rrsets, q->keys[i]);
+ 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(rrsets, j, j)
- n++;
+ LIST_FOREACH(by_key, j, j) {
+ if (j->rr)
+ n++;
+ else if (j->type == DNS_CACHE_NXDOMAIN)
+ nxdomain = true;
+ }
}
- assert(n > 0);
+ if (n <= 0) {
+ *ret = NULL;
+ *rcode = nxdomain ? DNS_RCODE_NXDOMAIN : DNS_RCODE_SUCCESS;
+ return 1;
+ }
answer = dns_answer_new(n);
if (!answer)
@@ -331,17 +434,18 @@ int dns_cache_lookup(DnsCache *c, DnsQuestion *q, DnsAnswer **ret) {
for (i = 0; i < q->n_keys; i++) {
DnsCacheItem *j;
- j = hashmap_get(c->rrsets, q->keys[i]);
- LIST_FOREACH(rrsets, j, j) {
- r = dns_answer_add(answer, j->rr);
- if (r < 0)
- return r;
+ 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;
+ }
}
}
- assert(n >= answer->n_rrs);
-
*ret = answer;
+ *rcode = DNS_RCODE_SUCCESS;
answer = NULL;
return n;
generated by cgit v1.2.3-54-g00ecf (git 2.45.2) at 2024-11-10 15:43:56 +0000