diff options
| -rw-r--r-- | src/resolve/resolved-dns-answer.c | 24 |
1 files changed, 21 insertions, 3 deletions
diff --git a/src/resolve/resolved-dns-answer.c b/src/resolve/resolved-dns-answer.c index 399b518644..445999f545 100644 --- a/src/resolve/resolved-dns-answer.c +++ b/src/resolve/resolved-dns-answer.c @@ -125,10 +125,13 @@ int dns_answer_add(DnsAnswer *a, DnsResourceRecord *rr, int ifindex, DnsAnswerFl if (r < 0) return r; if (r > 0) { - /* Entry already exists, keep the entry with - * the higher RR, or the one with TTL 0 */ + /* Don't mix contradicting TTLs (see below) */ + if ((rr->ttl == 0) != (a->items[i].rr->ttl == 0)) + return -EINVAL; - if (rr->ttl == 0 || (rr->ttl > a->items[i].rr->ttl && a->items[i].rr->ttl != 0)) { + /* Entry already exists, keep the entry with + * the higher RR. */ + if (rr->ttl > a->items[i].rr->ttl) { dns_resource_record_ref(rr); dns_resource_record_unref(a->items[i].rr); a->items[i].rr = rr; @@ -137,6 +140,21 @@ int dns_answer_add(DnsAnswer *a, DnsResourceRecord *rr, int ifindex, DnsAnswerFl a->items[i].flags |= flags; return 0; } + + r = dns_resource_key_equal(a->items[i].rr->key, rr->key); + if (r < 0) + return r; + if (r > 0) { + /* There's already an RR of the same RRset in + * place! Let's see if the TTLs more or less + * match. We don't really care if they match + * precisely, but we do care whether one is 0 + * and the other is not. See RFC 2181, Section + * 5.2.*/ + + if ((rr->ttl == 0) != (a->items[i].rr->ttl == 0)) + return -EINVAL; + } } return dns_answer_add_raw(a, rr, ifindex, flags); |