diff options
Diffstat (limited to 'src/resolve/resolved-dns-cache.c')
| -rw-r--r-- | src/resolve/resolved-dns-cache.c | 33 |
1 files changed, 32 insertions, 1 deletions
diff --git a/src/resolve/resolved-dns-cache.c b/src/resolve/resolved-dns-cache.c index fdb34d11df..9267b67f79 100644 --- a/src/resolve/resolved-dns-cache.c +++ b/src/resolve/resolved-dns-cache.c @@ -579,6 +579,28 @@ static void dns_cache_remove_previous( } } +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, DnsResourceKey *key, @@ -635,6 +657,12 @@ int dns_cache_put( if ((flags & DNS_ANSWER_CACHEABLE) == 0) continue; + r = rr_eligible(rr); + if (r < 0) + return r; + if (r == 0) + continue; + r = dns_cache_put_positive( c, rr, @@ -835,7 +863,10 @@ int dns_cache_lookup(DnsCache *c, DnsResourceKey *key, int *rcode, DnsAnswer **r have_non_authenticated = true; } - if (nsec && key->type != DNS_TYPE_NSEC) { + 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. */ + if (log_get_max_level() >= LOG_DEBUG) { r = dns_resource_key_to_string(key, &key_str); if (r < 0) |