summaryrefslogtreecommitdiff
path: root/src/resolve/resolved-dns-cache.c
diff options
context:
space:
mode:
Diffstat (limited to 'src/resolve/resolved-dns-cache.c')
-rw-r--r--src/resolve/resolved-dns-cache.c759
1 files changed, 631 insertions, 128 deletions
diff --git a/src/resolve/resolved-dns-cache.c b/src/resolve/resolved-dns-cache.c
index be52891681..9233fb0ac1 100644
--- a/src/resolve/resolved-dns-cache.c
+++ b/src/resolve/resolved-dns-cache.c
@@ -1,5 +1,3 @@
-/*-*- Mode: C; c-basic-offset: 8; indent-tabs-mode: nil -*-*/
-
/***
This file is part of systemd.
@@ -19,14 +17,22 @@
along with systemd; If not, see <http://www.gnu.org/licenses/>.
***/
+#include <net/if.h>
+
+#include "af-list.h"
+#include "alloc-util.h"
+#include "dns-domain.h"
+#include "resolved-dns-answer.h"
#include "resolved-dns-cache.h"
#include "resolved-dns-packet.h"
+#include "string-util.h"
-/* Never cache more than 1K entries */
-#define CACHE_MAX 1024
+/* Never cache more than 4K entries. RFC 1536, Section 5 suggests to
+ * leave DNS caches unbounded, but that's crazy. */
+#define CACHE_MAX 4096
-/* We never keep any item longer than 10min in our cache */
-#define CACHE_TTL_MAX_USEC (10 * USEC_PER_MINUTE)
+/* We never keep any item longer than 2h in our cache */
+#define CACHE_TTL_MAX_USEC (2 * USEC_PER_HOUR)
typedef enum DnsCacheItemType DnsCacheItemType;
typedef struct DnsCacheItem DnsCacheItem;
@@ -38,13 +44,19 @@ enum DnsCacheItemType {
};
struct DnsCacheItem {
+ DnsCacheItemType type;
DnsResourceKey *key;
DnsResourceRecord *rr;
+
usec_t until;
- DnsCacheItemType type;
- unsigned prioq_idx;
+ bool authenticated:1;
+ bool shared_owner:1;
+
+ int ifindex;
int owner_family;
union in_addr_union owner_address;
+
+ unsigned prioq_idx;
LIST_FIELDS(DnsCacheItem, by_key);
};
@@ -59,7 +71,7 @@ static void dns_cache_item_free(DnsCacheItem *i) {
DEFINE_TRIVIAL_CLEANUP_FUNC(DnsCacheItem*, dns_cache_item_free);
-static void dns_cache_item_remove_and_free(DnsCache *c, DnsCacheItem *i) {
+static void dns_cache_item_unlink_and_free(DnsCache *c, DnsCacheItem *i) {
DnsCacheItem *first;
assert(c);
@@ -80,29 +92,55 @@ static void dns_cache_item_remove_and_free(DnsCache *c, DnsCacheItem *i) {
dns_cache_item_free(i);
}
-void dns_cache_flush(DnsCache *c) {
- DnsCacheItem *i;
+static bool dns_cache_remove_by_rr(DnsCache *c, DnsResourceRecord *rr) {
+ DnsCacheItem *first, *i;
+ int r;
+
+ first = hashmap_get(c->by_key, rr->key);
+ LIST_FOREACH(by_key, i, first) {
+ r = dns_resource_record_equal(i->rr, rr);
+ if (r < 0)
+ return r;
+ if (r > 0) {
+ dns_cache_item_unlink_and_free(c, i);
+ return true;
+ }
+ }
+
+ return false;
+}
+
+static bool dns_cache_remove_by_key(DnsCache *c, DnsResourceKey *key) {
+ DnsCacheItem *first, *i, *n;
assert(c);
+ assert(key);
- while ((i = hashmap_first(c->by_key)))
- dns_cache_item_remove_and_free(c, i);
+ first = hashmap_remove(c->by_key, key);
+ if (!first)
+ return false;
- assert(hashmap_size(c->by_key) == 0);
- assert(prioq_size(c->by_expiry) == 0);
+ LIST_FOREACH_SAFE(by_key, i, n, first) {
+ prioq_remove(c->by_expiry, i, &i->prioq_idx);
+ dns_cache_item_free(i);
+ }
- c->by_key = hashmap_free(c->by_key);
- c->by_expiry = prioq_free(c->by_expiry);
+ return true;
}
-static void dns_cache_remove(DnsCache *c, DnsResourceKey *key) {
- DnsCacheItem *i;
+void dns_cache_flush(DnsCache *c) {
+ DnsResourceKey *key;
assert(c);
- assert(key);
- while ((i = hashmap_get(c->by_key, key)))
- dns_cache_item_remove_and_free(c, i);
+ while ((key = hashmap_first_key(c->by_key)))
+ dns_cache_remove_by_key(c, key);
+
+ assert(hashmap_size(c->by_key) == 0);
+ assert(prioq_size(c->by_expiry) == 0);
+
+ c->by_key = hashmap_free(c->by_key);
+ c->by_expiry = prioq_free(c->by_expiry);
}
static void dns_cache_make_space(DnsCache *c, unsigned add) {
@@ -132,7 +170,7 @@ static void dns_cache_make_space(DnsCache *c, unsigned add) {
/* 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);
+ dns_cache_remove_by_key(c, key);
}
}
@@ -144,23 +182,36 @@ void dns_cache_prune(DnsCache *c) {
/* Remove all entries that are past their TTL */
for (;;) {
- _cleanup_(dns_resource_key_unrefp) DnsResourceKey *key = NULL;
DnsCacheItem *i;
+ char key_str[DNS_RESOURCE_KEY_STRING_MAX];
i = prioq_peek(c->by_expiry);
if (!i)
break;
if (t <= 0)
- t = now(CLOCK_BOOTTIME);
+ t = now(clock_boottime_or_monotonic());
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);
+ /* Depending whether this is an mDNS shared entry
+ * either remove only this one RR or the whole RRset */
+ log_debug("Removing %scache entry for %s (expired "USEC_FMT"s ago)",
+ i->shared_owner ? "shared " : "",
+ dns_resource_key_to_string(i->key, key_str, sizeof key_str),
+ (t - i->until) / USEC_PER_SEC);
+
+ if (i->shared_owner)
+ dns_cache_item_unlink_and_free(c, i);
+ else {
+ _cleanup_(dns_resource_key_unrefp) DnsResourceKey *key = NULL;
+
+ /* 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_by_key(c, key);
+ }
}
}
@@ -203,6 +254,19 @@ static int dns_cache_link_item(DnsCache *c, DnsCacheItem *i) {
first = hashmap_get(c->by_key, i->key);
if (first) {
+ _cleanup_(dns_resource_key_unrefp) DnsResourceKey *k = NULL;
+
+ /* Keep a reference to the original key, while we manipulate the list. */
+ k = dns_resource_key_ref(first->key);
+
+ /* Now, try to reduce the number of keys we keep */
+ dns_resource_key_reduce(&first->key, &i->key);
+
+ if (first->rr)
+ dns_resource_key_reduce(&first->rr->key, &i->key);
+ if (i->rr)
+ dns_resource_key_reduce(&i->rr->key, &i->key);
+
LIST_PREPEND(by_key, first, i);
assert_se(hashmap_replace(c->by_key, first->key, first) >= 0);
} else {
@@ -229,19 +293,65 @@ static DnsCacheItem* dns_cache_get(DnsCache *c, DnsResourceRecord *rr) {
return NULL;
}
-static void dns_cache_item_update_positive(DnsCache *c, DnsCacheItem *i, DnsResourceRecord *rr, usec_t timestamp) {
+static usec_t calculate_until(DnsResourceRecord *rr, uint32_t nsec_ttl, usec_t timestamp, bool use_soa_minimum) {
+ uint32_t ttl;
+ usec_t u;
+
+ assert(rr);
+
+ ttl = MIN(rr->ttl, nsec_ttl);
+ if (rr->key->type == DNS_TYPE_SOA && use_soa_minimum) {
+ /* If this is a SOA RR, and it is requested, clamp to
+ * the SOA's minimum field. This is used when we do
+ * negative caching, to determine the TTL for the
+ * negative caching entry. See RFC 2308, Section
+ * 5. */
+
+ if (ttl > rr->soa.minimum)
+ ttl = rr->soa.minimum;
+ }
+
+ u = ttl * USEC_PER_SEC;
+ if (u > CACHE_TTL_MAX_USEC)
+ u = CACHE_TTL_MAX_USEC;
+
+ if (rr->expiry != USEC_INFINITY) {
+ usec_t left;
+
+ /* Make use of the DNSSEC RRSIG expiry info, if we
+ * have it */
+
+ left = LESS_BY(rr->expiry, now(CLOCK_REALTIME));
+ if (u > left)
+ u = left;
+ }
+
+ return timestamp + u;
+}
+
+static void dns_cache_item_update_positive(
+ DnsCache *c,
+ DnsCacheItem *i,
+ DnsResourceRecord *rr,
+ bool authenticated,
+ bool shared_owner,
+ usec_t timestamp,
+ int ifindex,
+ int owner_family,
+ const union in_addr_union *owner_address) {
+
assert(c);
assert(i);
assert(rr);
+ assert(owner_address);
i->type = DNS_CACHE_POSITIVE;
- if (!i->by_key_prev) {
+ 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);
@@ -250,7 +360,14 @@ static void dns_cache_item_update_positive(DnsCache *c, DnsCacheItem *i, DnsReso
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);
+ i->until = calculate_until(rr, (uint32_t) -1, timestamp, false);
+ i->authenticated = authenticated;
+ i->shared_owner = shared_owner;
+
+ i->ifindex = ifindex;
+
+ i->owner_family = owner_family;
+ i->owner_address = *owner_address;
prioq_reshuffle(c->by_expiry, i, &i->prioq_idx);
}
@@ -258,33 +375,50 @@ static void dns_cache_item_update_positive(DnsCache *c, DnsCacheItem *i, DnsReso
static int dns_cache_put_positive(
DnsCache *c,
DnsResourceRecord *rr,
+ bool authenticated,
+ bool shared_owner,
usec_t timestamp,
+ int ifindex,
int owner_family,
const union in_addr_union *owner_address) {
_cleanup_(dns_cache_item_freep) DnsCacheItem *i = NULL;
DnsCacheItem *existing;
- int r;
+ char key_str[DNS_RESOURCE_KEY_STRING_MAX], ifname[IF_NAMESIZE];
+ int r, k;
assert(c);
assert(rr);
assert(owner_address);
- /* New TTL is 0? Delete the entry... */
- if (rr->ttl <= 0) {
- dns_cache_remove(c, rr->key);
+ /* Never cache pseudo RRs */
+ if (dns_class_is_pseudo(rr->key->class))
return 0;
- }
-
- if (rr->key->class == DNS_CLASS_ANY)
+ if (dns_type_is_pseudo(rr->key->type))
return 0;
- if (rr->key->type == DNS_TYPE_ANY)
+
+ /* New TTL is 0? Delete this specific entry... */
+ if (rr->ttl <= 0) {
+ k = dns_cache_remove_by_rr(c, rr);
+ log_debug("%s: %s",
+ k > 0 ? "Removed zero TTL entry from cache" : "Not caching zero TTL cache entry",
+ dns_resource_key_to_string(rr->key, key_str, sizeof key_str));
return 0;
+ }
- /* Entry exists already? Update TTL and timestamp */
+ /* Entry exists already? Update TTL, timestamp and owner*/
existing = dns_cache_get(c, rr);
if (existing) {
- dns_cache_item_update_positive(c, existing, rr, timestamp);
+ dns_cache_item_update_positive(
+ c,
+ existing,
+ rr,
+ authenticated,
+ shared_owner,
+ timestamp,
+ ifindex,
+ owner_family,
+ owner_address);
return 0;
}
@@ -302,15 +436,33 @@ static int dns_cache_put_positive(
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->until = calculate_until(rr, (uint32_t) -1, timestamp, false);
+ i->authenticated = authenticated;
+ i->shared_owner = shared_owner;
+ i->ifindex = ifindex;
i->owner_family = owner_family;
i->owner_address = *owner_address;
+ i->prioq_idx = PRIOQ_IDX_NULL;
r = dns_cache_link_item(c, i);
if (r < 0)
return r;
+ if (log_get_max_level() >= LOG_DEBUG) {
+ _cleanup_free_ char *t = NULL;
+
+ (void) in_addr_to_string(i->owner_family, &i->owner_address, &t);
+
+ log_debug("Added positive %s%s cache entry for %s "USEC_FMT"s on %s/%s/%s",
+ i->authenticated ? "authenticated" : "unauthenticated",
+ i->shared_owner ? " shared" : "",
+ dns_resource_key_to_string(i->key, key_str, sizeof key_str),
+ (i->until - timestamp) / USEC_PER_SEC,
+ i->ifindex == 0 ? "*" : strna(if_indextoname(i->ifindex, ifname)),
+ af_to_name_short(i->owner_family),
+ strna(t));
+ }
+
i = NULL;
return 0;
}
@@ -319,26 +471,35 @@ static int dns_cache_put_negative(
DnsCache *c,
DnsResourceKey *key,
int rcode,
+ bool authenticated,
+ uint32_t nsec_ttl,
usec_t timestamp,
- uint32_t soa_ttl,
+ DnsResourceRecord *soa,
int owner_family,
const union in_addr_union *owner_address) {
_cleanup_(dns_cache_item_freep) DnsCacheItem *i = NULL;
+ char key_str[DNS_RESOURCE_KEY_STRING_MAX];
int r;
assert(c);
assert(key);
+ assert(soa);
assert(owner_address);
- dns_cache_remove(c, key);
-
- if (key->class == DNS_CLASS_ANY)
+ /* Never cache pseudo RR keys. DNS_TYPE_ANY is particularly
+ * important to filter out as we use this as a pseudo-type for
+ * NXDOMAIN entries */
+ if (dns_class_is_pseudo(key->class))
return 0;
- if (key->type == DNS_TYPE_ANY)
+ if (dns_type_is_pseudo(key->type))
return 0;
- if (soa_ttl <= 0)
+
+ if (nsec_ttl <= 0 || soa->soa.minimum <= 0 || soa->ttl <= 0) {
+ log_debug("Not caching negative entry with zero SOA/NSEC/NSEC3 TTL: %s",
+ dns_resource_key_to_string(key, key_str, sizeof key_str));
return 0;
+ }
if (!IN_SET(rcode, DNS_RCODE_SUCCESS, DNS_RCODE_NXDOMAIN))
return 0;
@@ -354,149 +515,377 @@ static int dns_cache_put_negative(
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->until = calculate_until(soa, nsec_ttl, timestamp, true);
+ i->authenticated = authenticated;
i->owner_family = owner_family;
i->owner_address = *owner_address;
+ i->prioq_idx = PRIOQ_IDX_NULL;
+
+ if (i->type == DNS_CACHE_NXDOMAIN) {
+ /* NXDOMAIN entries should apply equally to all types, so we use ANY as
+ * a pseudo type for this purpose here. */
+ i->key = dns_resource_key_new(key->class, DNS_TYPE_ANY, dns_resource_key_name(key));
+ if (!i->key)
+ return -ENOMEM;
+
+ /* Make sure to remove any previous entry for this
+ * specific ANY key. (For non-ANY keys the cache data
+ * is already cleared by the caller.) Note that we
+ * don't bother removing positive or NODATA cache
+ * items in this case, because it would either be slow
+ * or require explicit indexing by name */
+ dns_cache_remove_by_key(c, key);
+ } else
+ i->key = dns_resource_key_ref(key);
r = dns_cache_link_item(c, i);
if (r < 0)
return r;
+ log_debug("Added %s cache entry for %s "USEC_FMT"s",
+ i->type == DNS_CACHE_NODATA ? "NODATA" : "NXDOMAIN",
+ dns_resource_key_to_string(i->key, key_str, sizeof key_str),
+ (i->until - timestamp) / USEC_PER_SEC);
+
i = NULL;
return 0;
}
+static void dns_cache_remove_previous(
+ DnsCache *c,
+ DnsResourceKey *key,
+ DnsAnswer *answer) {
+
+ DnsResourceRecord *rr;
+ DnsAnswerFlags flags;
+
+ assert(c);
+
+ /* First, if we were passed a key (i.e. on LLMNR/DNS, but
+ * not on mDNS), delete all matching old RRs, so that we only
+ * keep complete by_key in place. */
+ if (key)
+ dns_cache_remove_by_key(c, key);
+
+ /* Second, flush all entries matching the answer, unless this
+ * is an RR that is explicitly marked to be "shared" between
+ * peers (i.e. mDNS RRs without the flush-cache bit set). */
+ DNS_ANSWER_FOREACH_FLAGS(rr, flags, answer) {
+ if ((flags & DNS_ANSWER_CACHEABLE) == 0)
+ continue;
+
+ if (flags & DNS_ANSWER_SHARED_OWNER)
+ continue;
+
+ dns_cache_remove_by_key(c, rr->key);
+ }
+}
+
+static bool rr_eligible(DnsResourceRecord *rr) {
+ assert(rr);
+
+ /* When we see an NSEC/NSEC3 RR, we'll only cache it if it is from the lower zone, not the upper zone, since
+ * that's where the interesting bits are (with exception of DS RRs). Of course, this way we cannot derive DS
+ * existence from any cached NSEC/NSEC3, but that should be fine. */
+
+ switch (rr->key->type) {
+
+ case DNS_TYPE_NSEC:
+ return !bitmap_isset(rr->nsec.types, DNS_TYPE_NS) ||
+ bitmap_isset(rr->nsec.types, DNS_TYPE_SOA);
+
+ case DNS_TYPE_NSEC3:
+ return !bitmap_isset(rr->nsec3.types, DNS_TYPE_NS) ||
+ bitmap_isset(rr->nsec3.types, DNS_TYPE_SOA);
+
+ default:
+ return true;
+ }
+}
+
int dns_cache_put(
DnsCache *c,
- DnsQuestion *q,
+ DnsResourceKey *key,
int rcode,
DnsAnswer *answer,
- unsigned max_rrs,
+ bool authenticated,
+ uint32_t nsec_ttl,
usec_t timestamp,
int owner_family,
const union in_addr_union *owner_address) {
- unsigned i;
- int r;
+ DnsResourceRecord *soa = NULL, *rr;
+ DnsAnswerFlags flags;
+ unsigned cache_keys;
+ int r, ifindex;
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;
+ assert(owner_address);
- for (i = 0; i < answer->n_rrs; i++)
- dns_cache_remove(c, answer->rrs[i]->key);
+ dns_cache_remove_previous(c, key, answer);
/* 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;
+ if (dns_answer_size(answer) <= 0) {
+ char key_str[DNS_RESOURCE_KEY_STRING_MAX];
+
+ log_debug("Not caching negative entry without a SOA record: %s",
+ dns_resource_key_to_string(key, key_str, sizeof key_str));
+ return 0;
+ }
+
+ cache_keys = dns_answer_size(answer);
+ if (key)
+ cache_keys++;
+
/* Make some space for our new entries */
- dns_cache_make_space(c, answer->n_rrs + q->n_keys);
+ dns_cache_make_space(c, cache_keys);
if (timestamp <= 0)
- timestamp = now(CLOCK_BOOTTIME);
+ timestamp = now(clock_boottime_or_monotonic());
/* 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)
+ DNS_ANSWER_FOREACH_FULL(rr, ifindex, flags, answer) {
+ if ((flags & DNS_ANSWER_CACHEABLE) == 0)
continue;
- r = dns_answer_find_soa(answer, q->keys[i], &soa);
+ r = rr_eligible(rr);
if (r < 0)
- goto fail;
+ return r;
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);
+ r = dns_cache_put_positive(
+ c,
+ rr,
+ flags & DNS_ANSWER_AUTHENTICATED,
+ flags & DNS_ANSWER_SHARED_OWNER,
+ timestamp,
+ ifindex,
+ owner_family, owner_address);
if (r < 0)
goto fail;
}
+ if (!key) /* mDNS doesn't know negative caching, really */
+ return 0;
+
+ /* Third, add in negative entries if the key has no RR */
+ r = dns_answer_match_key(answer, key, NULL);
+ if (r < 0)
+ goto fail;
+ if (r > 0)
+ return 0;
+
+ /* But not if it has a matching CNAME/DNAME (the negative
+ * caching will be done on the canonical name, not on the
+ * alias) */
+ r = dns_answer_find_cname_or_dname(answer, key, NULL, NULL);
+ if (r < 0)
+ goto fail;
+ if (r > 0)
+ return 0;
+
+ /* See https://tools.ietf.org/html/rfc2308, which say that a
+ * matching SOA record in the packet is used to enable
+ * negative caching. */
+ r = dns_answer_find_soa(answer, key, &soa, &flags);
+ if (r < 0)
+ goto fail;
+ if (r == 0)
+ return 0;
+
+ /* Refuse using the SOA data if it is unsigned, but the key is
+ * signed */
+ if (authenticated && (flags & DNS_ANSWER_AUTHENTICATED) == 0)
+ return 0;
+
+ r = dns_cache_put_negative(
+ c,
+ key,
+ rcode,
+ authenticated,
+ nsec_ttl,
+ timestamp,
+ soa,
+ 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);
+ if (key)
+ dns_cache_remove_by_key(c, key);
+
+ DNS_ANSWER_FOREACH_FLAGS(rr, flags, answer) {
+ if ((flags & DNS_ANSWER_CACHEABLE) == 0)
+ continue;
+
+ dns_cache_remove_by_key(c, rr->key);
+ }
return r;
}
-int dns_cache_lookup(DnsCache *c, DnsQuestion *q, int *rcode, DnsAnswer **ret) {
+static DnsCacheItem *dns_cache_get_by_key_follow_cname_dname_nsec(DnsCache *c, DnsResourceKey *k) {
+ DnsCacheItem *i;
+ const char *n;
+ int r;
+
+ assert(c);
+ assert(k);
+
+ /* If we hit some OOM error, or suchlike, we don't care too
+ * much, after all this is just a cache */
+
+ i = hashmap_get(c->by_key, k);
+ if (i)
+ return i;
+
+ n = dns_resource_key_name(k);
+
+ /* Check if we have an NXDOMAIN cache item for the name, notice that we use
+ * the pseudo-type ANY for NXDOMAIN cache items. */
+ i = hashmap_get(c->by_key, &DNS_RESOURCE_KEY_CONST(k->class, DNS_TYPE_ANY, n));
+ if (i && i->type == DNS_CACHE_NXDOMAIN)
+ return i;
+
+ if (dns_type_may_redirect(k->type)) {
+ /* Check if we have a CNAME record instead */
+ i = hashmap_get(c->by_key, &DNS_RESOURCE_KEY_CONST(k->class, DNS_TYPE_CNAME, n));
+ if (i)
+ return i;
+
+ /* OK, let's look for cached DNAME records. */
+ for (;;) {
+ if (isempty(n))
+ return NULL;
+
+ i = hashmap_get(c->by_key, &DNS_RESOURCE_KEY_CONST(k->class, DNS_TYPE_DNAME, n));
+ if (i)
+ return i;
+
+ /* Jump one label ahead */
+ r = dns_name_parent(&n);
+ if (r <= 0)
+ return NULL;
+ }
+ }
+
+ if (k->type != DNS_TYPE_NSEC) {
+ /* Check if we have an NSEC record instead for the name. */
+ i = hashmap_get(c->by_key, &DNS_RESOURCE_KEY_CONST(k->class, DNS_TYPE_NSEC, n));
+ if (i)
+ return i;
+ }
+
+ return NULL;
+}
+
+int dns_cache_lookup(DnsCache *c, DnsResourceKey *key, bool clamp_ttl, int *rcode, DnsAnswer **ret, bool *authenticated) {
_cleanup_(dns_answer_unrefp) DnsAnswer *answer = NULL;
- unsigned i, n = 0;
+ char key_str[DNS_RESOURCE_KEY_STRING_MAX];
+ unsigned n = 0;
int r;
bool nxdomain = false;
+ DnsCacheItem *j, *first, *nsec = NULL;
+ bool have_authenticated = false, have_non_authenticated = false;
+ usec_t current;
assert(c);
- assert(q);
+ assert(key);
assert(rcode);
assert(ret);
+ assert(authenticated);
+
+ if (key->type == DNS_TYPE_ANY || key->class == DNS_CLASS_ANY) {
+ /* If we have ANY lookups we don't use the cache, so
+ * that the caller refreshes via the network. */
+
+ log_debug("Ignoring cache for ANY lookup: %s",
+ dns_resource_key_to_string(key, key_str, sizeof key_str));
+
+ c->n_miss++;
- if (q->n_keys <= 0) {
*ret = NULL;
- *rcode = 0;
+ *rcode = DNS_RCODE_SUCCESS;
return 0;
}
- for (i = 0; i < q->n_keys; i++) {
- DnsCacheItem *j;
+ first = dns_cache_get_by_key_follow_cname_dname_nsec(c, key);
+ if (!first) {
+ /* If one question cannot be answered we need to refresh */
- 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;
- }
+ log_debug("Cache miss for %s",
+ dns_resource_key_to_string(key, key_str, sizeof key_str));
- 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;
- }
+ c->n_miss++;
+
+ *ret = NULL;
+ *rcode = DNS_RCODE_SUCCESS;
+ return 0;
+ }
+
+ LIST_FOREACH(by_key, j, first) {
+ if (j->rr) {
+ if (j->rr->key->type == DNS_TYPE_NSEC)
+ nsec = j;
+
+ n++;
+ } else if (j->type == DNS_CACHE_NXDOMAIN)
+ nxdomain = true;
+
+ if (j->authenticated)
+ have_authenticated = true;
+ else
+ have_non_authenticated = true;
+ }
+
+ if (nsec && !IN_SET(key->type, DNS_TYPE_NSEC, DNS_TYPE_DS)) {
+ /* Note that we won't derive information for DS RRs from an NSEC, because we only cache NSEC RRs from
+ * the lower-zone of a zone cut, but the DS RRs are on the upper zone. */
+
+ log_debug("NSEC NODATA cache hit for %s",
+ dns_resource_key_to_string(key, key_str, sizeof key_str));
- LIST_FOREACH(by_key, j, j) {
- if (j->rr)
- n++;
- else if (j->type == DNS_CACHE_NXDOMAIN)
- nxdomain = true;
+ /* We only found an NSEC record that matches our name.
+ * If it says the type doesn't exist report
+ * NODATA. Otherwise report a cache miss. */
+
+ *ret = NULL;
+ *rcode = DNS_RCODE_SUCCESS;
+ *authenticated = nsec->authenticated;
+
+ if (!bitmap_isset(nsec->rr->nsec.types, key->type) &&
+ !bitmap_isset(nsec->rr->nsec.types, DNS_TYPE_CNAME) &&
+ !bitmap_isset(nsec->rr->nsec.types, DNS_TYPE_DNAME)) {
+ c->n_hit++;
+ return 1;
}
+
+ c->n_miss++;
+ return 0;
}
+ log_debug("%s cache hit for %s",
+ n > 0 ? "Positive" :
+ nxdomain ? "NXDOMAIN" : "NODATA",
+ dns_resource_key_to_string(key, key_str, sizeof key_str));
+
if (n <= 0) {
+ c->n_hit++;
+
*ret = NULL;
*rcode = nxdomain ? DNS_RCODE_NXDOMAIN : DNS_RCODE_SUCCESS;
+ *authenticated = have_authenticated && !have_non_authenticated;
return 1;
}
@@ -504,21 +893,33 @@ int dns_cache_lookup(DnsCache *c, DnsQuestion *q, int *rcode, DnsAnswer **ret) {
if (!answer)
return -ENOMEM;
- for (i = 0; i < q->n_keys; i++) {
- DnsCacheItem *j;
+ if (clamp_ttl)
+ current = now(clock_boottime_or_monotonic());
- 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;
- }
+ LIST_FOREACH(by_key, j, first) {
+ _cleanup_(dns_resource_record_unrefp) DnsResourceRecord *rr = NULL;
+
+ if (!j->rr)
+ continue;
+
+ if (clamp_ttl) {
+ rr = dns_resource_record_ref(j->rr);
+
+ r = dns_resource_record_clamp_ttl(&rr, LESS_BY(j->until, current) / USEC_PER_SEC);
+ if (r < 0)
+ return r;
}
+
+ r = dns_answer_add(answer, rr ?: j->rr, j->ifindex, j->authenticated ? DNS_ANSWER_AUTHENTICATED : 0);
+ if (r < 0)
+ return r;
}
+ c->n_hit++;
+
*ret = answer;
*rcode = DNS_RCODE_SUCCESS;
+ *authenticated = have_authenticated && !have_non_authenticated;
answer = NULL;
return n;
@@ -559,3 +960,105 @@ int dns_cache_check_conflicts(DnsCache *cache, DnsResourceRecord *rr, int owner_
/* There's a conflict */
return 1;
}
+
+int dns_cache_export_shared_to_packet(DnsCache *cache, DnsPacket *p) {
+ unsigned ancount = 0;
+ Iterator iterator;
+ DnsCacheItem *i;
+ int r;
+
+ assert(cache);
+ assert(p);
+
+ HASHMAP_FOREACH(i, cache->by_key, iterator) {
+ DnsCacheItem *j;
+
+ LIST_FOREACH(by_key, j, i) {
+ if (!j->rr)
+ continue;
+
+ if (!j->shared_owner)
+ continue;
+
+ r = dns_packet_append_rr(p, j->rr, NULL, NULL);
+ if (r == -EMSGSIZE && p->protocol == DNS_PROTOCOL_MDNS) {
+ /* For mDNS, if we're unable to stuff all known answers into the given packet,
+ * allocate a new one, push the RR into that one and link it to the current one.
+ */
+
+ DNS_PACKET_HEADER(p)->ancount = htobe16(ancount);
+ ancount = 0;
+
+ r = dns_packet_new_query(&p->more, p->protocol, 0, true);
+ if (r < 0)
+ return r;
+
+ /* continue with new packet */
+ p = p->more;
+ r = dns_packet_append_rr(p, j->rr, NULL, NULL);
+ }
+
+ if (r < 0)
+ return r;
+
+ ancount++;
+ }
+ }
+
+ DNS_PACKET_HEADER(p)->ancount = htobe16(ancount);
+
+ return 0;
+}
+
+void dns_cache_dump(DnsCache *cache, FILE *f) {
+ Iterator iterator;
+ DnsCacheItem *i;
+
+ if (!cache)
+ return;
+
+ if (!f)
+ f = stdout;
+
+ HASHMAP_FOREACH(i, cache->by_key, iterator) {
+ DnsCacheItem *j;
+
+ LIST_FOREACH(by_key, j, i) {
+
+ fputc('\t', f);
+
+ if (j->rr) {
+ const char *t;
+ t = dns_resource_record_to_string(j->rr);
+ if (!t) {
+ log_oom();
+ continue;
+ }
+
+ fputs(t, f);
+ fputc('\n', f);
+ } else {
+ char key_str[DNS_RESOURCE_KEY_STRING_MAX];
+
+ fputs(dns_resource_key_to_string(j->key, key_str, sizeof key_str), f);
+ fputs(" -- ", f);
+ fputs(j->type == DNS_CACHE_NODATA ? "NODATA" : "NXDOMAIN", f);
+ fputc('\n', f);
+ }
+ }
+ }
+}
+
+bool dns_cache_is_empty(DnsCache *cache) {
+ if (!cache)
+ return true;
+
+ return hashmap_isempty(cache->by_key);
+}
+
+unsigned dns_cache_size(DnsCache *cache) {
+ if (!cache)
+ return 0;
+
+ return hashmap_size(cache->by_key);
+}
generated by cgit v1.2.3-54-g00ecf (git 2.45.2) at 2025-01-17 17:39:59 +0000