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resolved: cache - don't flush the cache of mDNS records unneccesarily

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When the DNS_RESOURCE_KEY_CACHE_FLUSH flag is not set for an mDNS packet, we should not flush
the cache for RRs with matching keys. However, we were unconditionally flushing the cache
also for these packets.

Now mark all packets as cache_flush by default, except for these mDNS packets, and respect
that flag in the cache handling.

This fixes 90325e8c2e.
This commit is contained in:
Tom Gundersen 2015-12-10 19:57:41 +01:00
parent 2250592422
commit 02c2857b8d
2 changed files with 10 additions and 11 deletions
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13
src/resolve/resolved-dns-cache.c
View File

@ -21,6 +21,7 @@
#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"
@ -431,7 +432,7 @@ int dns_cache_put(
int owner_family,
const union in_addr_union *owner_address) {
DnsResourceRecord *soa = NULL;
DnsResourceRecord *soa = NULL, *rr;
unsigned cache_keys, i;
int r;
@ -455,8 +456,9 @@ int dns_cache_put(
return 0;
}
for (i = 0; i < answer->n_rrs; i++)
dns_cache_remove(c, answer->items[i].rr->key);
DNS_ANSWER_FOREACH(rr, answer)
if (rr->key->cache_flush)
dns_cache_remove(c, rr->key);
/* We only care for positive replies and NXDOMAINs, on all
* other replies we will simply flush the respective entries,
@ -478,10 +480,7 @@ int dns_cache_put(
/* Second, add in positive entries for all contained RRs */
for (i = 0; i < MIN(max_rrs, answer->n_rrs); i++) {
DnsResourceRecord *rr = answer->items[i].rr;
if (rr->key->cache_flush)
dns_cache_remove(c, rr->key);
rr = answer->items[i].rr;
r = dns_cache_put_positive(c, rr, authenticated, timestamp, owner_family, owner_address);
if (r < 0)

8
src/resolve/resolved-dns-packet.c
View File

@ -1451,7 +1451,7 @@ fail:
int dns_packet_read_key(DnsPacket *p, DnsResourceKey **ret, size_t *start) {
_cleanup_free_ char *name = NULL;
bool cache_flush = false;
bool cache_flush = true;
uint16_t class, type;
DnsResourceKey *key;
size_t saved_rindex;
@ -1477,10 +1477,10 @@ int dns_packet_read_key(DnsPacket *p, DnsResourceKey **ret, size_t *start) {
if (p->protocol == DNS_PROTOCOL_MDNS) {
/* See RFC6762, Section 10.2 */
if (class & MDNS_RR_CACHE_FLUSH) {
if (class & MDNS_RR_CACHE_FLUSH)
class &= ~MDNS_RR_CACHE_FLUSH;
cache_flush = true;
}
else
cache_flush = false;
}
key = dns_resource_key_new_consume(class, type, name);