resolved: only cache answer RRs, never additional or authoritative RRs of responses

[elogind.git] / src / resolve / resolved-dns-answer.c

diff --git a/src/resolve/resolved-dns-answer.c b/src/resolve/resolved-dns-answer.c
index fbc282550e87d760f11ebaebf82997e672bc0ff3..60969593559ed7cb1939f134cbc66dbbb65e2847 100644 (file)
--- 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 +66,147 @@ 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 a SOA record we can never find a matching SOA record */
+        if (key->type == DNS_TYPE_SOA)
+                return 0;
+
+        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;
 }
+
+DnsAnswer *dns_answer_merge(DnsAnswer *a, DnsAnswer *b) {
+        _cleanup_(dns_answer_unrefp) DnsAnswer *ret = NULL;
+        DnsAnswer *k;
+        unsigned i;
+        int r;
+
+        if (a && (!b || b->n_rrs <= 0))
+                return dns_answer_ref(a);
+        if ((!a || a->n_rrs <= 0) && b)
+                return dns_answer_ref(b);
+
+        ret = dns_answer_new((a ? a->n_rrs : 0) + (b ? b->n_rrs : 0));
+        if (!ret)
+                return NULL;
+
+        if (a) {
+                for (i = 0; i < a->n_rrs; i++) {
+                        r = dns_answer_add(ret, a->rrs[i]);
+                        if (r < 0)
+                                return NULL;
+                }
+        }
+
+        if (b) {
+                for (i = 0; i < b->n_rrs; i++) {
+                        r = dns_answer_add(ret, b->rrs[i]);
+                        if (r < 0)
+                                return NULL;
+                }
+        }
+
+        k = ret;
+        ret = NULL;
+
+        return k;
+}
+
+void dns_answer_order_by_scope(DnsAnswer *a, bool prefer_link_local) {
+        DnsResourceRecord **rrs;
+        unsigned i, start, end;
+        assert(a);
+
+        if (a->n_rrs <= 1)
+                return;
+
+        start = 0;
+        end = a->n_rrs-1;
+
+        /* RFC 4795, Section 2.6 suggests we should order entries
+         * depending on whether the sender is a link-local address. */
+
+        rrs = newa(DnsResourceRecord*, a->n_rrs);
+        for (i = 0; i < a->n_rrs; i++) {
+
+                if (a->rrs[i]->key->class == DNS_CLASS_IN &&
+                    ((a->rrs[i]->key->type == DNS_TYPE_A && in_addr_is_link_local(AF_INET, (union in_addr_union*) &a->rrs[i]->a.in_addr) != prefer_link_local) ||
+                     (a->rrs[i]->key->type == DNS_TYPE_AAAA && in_addr_is_link_local(AF_INET6, (union in_addr_union*) &a->rrs[i]->aaaa.in6_addr) != prefer_link_local)))
+                        /* Order address records that are are not preferred to the end of the array */
+                        rrs[end--] = a->rrs[i];
+                else
+                        /* Order all other records to the beginning of the array */
+                        rrs[start++] = a->rrs[i];
+        }
+
+        assert(start == end+1);
+        memcpy(a->rrs, rrs, sizeof(DnsResourceRecord*) * a->n_rrs);
+}