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resolved: don't allow RRs with TTL=0 and TTL!=0 in the same RRset

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This commit is contained in:
Lennart Poettering 2015-12-29 19:06:12 +01:00
parent f3abbe2540
commit 7feea00bb0
1 changed files with 21 additions and 3 deletions
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24
src/resolve/resolved-dns-answer.c
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@ -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);