resolved: implement negative caching

1 files changed, 64 insertions, 0 deletions

diff --git a/src/resolve/resolved-dns-answer.c b/src/resolve/resolved-dns-answer.c
index fbc282550e..34c854cb3a 100644
--- a/src/resolve/resolved-dns-answer.c
+++ b/src/resolve/resolved-dns-answer.c
@@ -20,6 +20,7 @@
 ***/
 
 #include "resolved-dns-answer.h"
+#include "resolved-dns-domain.h"
 
 DnsAnswer *dns_answer_new(unsigned n) {
         DnsAnswer *a;
@@ -65,12 +66,75 @@ DnsAnswer *dns_answer_unref(DnsAnswer *a) {
 }
 
 int dns_answer_add(DnsAnswer *a, DnsResourceRecord *rr) {
+        unsigned i;
+        int r;
+
         assert(a);
         assert(rr);
 
+        for (i = 0; i < a->n_rrs; i++) {
+                r = dns_resource_record_equal(a->rrs[i], rr);
+                if (r < 0)
+                        return r;
+                if (r > 0) {
+                        /* Entry already exists, keep the entry with
+                         * the higher RR, or the one with TTL 0 */
+
+                        if (rr->ttl == 0 || (rr->ttl > a->rrs[i]->ttl && a->rrs[i]->ttl != 0)) {
+                                dns_resource_record_ref(rr);
+                                dns_resource_record_unref(a->rrs[i]);
+                                a->rrs[i] = rr;
+                        }
+
+                        return 0;
+                }
+        }
+
         if (a->n_rrs >= a->n_allocated)
                 return -ENOSPC;
 
         a->rrs[a->n_rrs++] = dns_resource_record_ref(rr);
+        return 1;
+}
+
+int dns_answer_contains(DnsAnswer *a, DnsResourceKey *key) {
+        unsigned i;
+        int r;
+
+        assert(a);
+        assert(key);
+
+        for (i = 0; i < a->n_rrs; i++) {
+                r = dns_resource_key_match_rr(key, a->rrs[i]);
+                if (r < 0)
+                        return r;
+                if (r > 0)
+                        return 1;
+        }
+
+        return 0;
+}
+
+int dns_answer_find_soa(DnsAnswer *a, DnsResourceKey *key, DnsResourceRecord **ret) {
+        unsigned i;
+
+        assert(a);
+        assert(key);
+        assert(ret);
+
+        for (i = 0; i < a->n_rrs; i++) {
+
+                if (a->rrs[i]->key->class != DNS_CLASS_IN)
+                        continue;
+
+                if (a->rrs[i]->key->type != DNS_TYPE_SOA)
+                        continue;
+
+                if (dns_name_endswith(DNS_RESOURCE_KEY_NAME(key), DNS_RESOURCE_KEY_NAME(a->rrs[i]->key))) {
+                        *ret = a->rrs[i];
+                        return 1;
+                }
+        }
+
         return 0;
 }