return true;
}
-int dns_packet_extract(DnsPacket *p) {
+static int dns_packet_extract_question(DnsPacket *p, DnsQuestion **ret_question) {
_cleanup_(dns_question_unrefp) DnsQuestion *question = NULL;
- _cleanup_(dns_answer_unrefp) DnsAnswer *answer = NULL;
- _cleanup_(rewind_dns_packet) DnsPacketRewinder rewinder = {};
unsigned n, i;
int r;
- if (p->extracted)
- return 0;
-
- INIT_REWINDER(rewinder, p);
- dns_packet_rewind(p, DNS_PACKET_HEADER_SIZE);
-
n = DNS_PACKET_QDCOUNT(p);
if (n > 0) {
question = dns_question_new(n);
}
}
+ *ret_question = question;
+ question = NULL;
+ return 0;
+}
+
+static int dns_packet_extract_answer(DnsPacket *p, DnsAnswer **ret_answer) {
+ _cleanup_(dns_answer_unrefp) DnsAnswer *answer = NULL;
+ unsigned n, i;
+ _cleanup_(dns_resource_record_unrefp) DnsResourceRecord *previous = NULL;
+ bool bad_opt = false;
+ int r;
+
n = DNS_PACKET_RRCOUNT(p);
- if (n > 0) {
- _cleanup_(dns_resource_record_unrefp) DnsResourceRecord *previous = NULL;
- bool bad_opt = false;
+ if (n == 0)
+ return 0;
- answer = dns_answer_new(n);
- if (!answer)
- return -ENOMEM;
+ answer = dns_answer_new(n);
+ if (!answer)
+ return -ENOMEM;
- for (i = 0; i < n; i++) {
- _cleanup_(dns_resource_record_unrefp) DnsResourceRecord *rr = NULL;
- bool cache_flush = false;
+ for (i = 0; i < n; i++) {
+ _cleanup_(dns_resource_record_unrefp) DnsResourceRecord *rr = NULL;
+ bool cache_flush = false;
- r = dns_packet_read_rr(p, &rr, &cache_flush, NULL);
- if (r < 0)
- return r;
+ r = dns_packet_read_rr(p, &rr, &cache_flush, NULL);
+ if (r < 0)
+ return r;
- /* Try to reduce memory usage a bit */
- if (previous)
- dns_resource_key_reduce(&rr->key, &previous->key);
+ /* Try to reduce memory usage a bit */
+ if (previous)
+ dns_resource_key_reduce(&rr->key, &previous->key);
- if (rr->key->type == DNS_TYPE_OPT) {
- bool has_rfc6975;
+ if (rr->key->type == DNS_TYPE_OPT) {
+ bool has_rfc6975;
- if (p->opt || bad_opt) {
- /* Multiple OPT RRs? if so, let's ignore all, because there's something wrong
- * with the server, and if one is valid we wouldn't know which one. */
- log_debug("Multiple OPT RRs detected, ignoring all.");
- bad_opt = true;
- continue;
- }
+ if (p->opt || bad_opt) {
+ /* Multiple OPT RRs? if so, let's ignore all, because there's
+ * something wrong with the server, and if one is valid we wouldn't
+ * know which one. */
+ log_debug("Multiple OPT RRs detected, ignoring all.");
+ bad_opt = true;
+ continue;
+ }
- if (!dns_name_is_root(dns_resource_key_name(rr->key))) {
- /* If the OPT RR is not owned by the root domain, then it is bad, let's ignore
- * it. */
- log_debug("OPT RR is not owned by root domain, ignoring.");
- bad_opt = true;
- continue;
- }
+ if (!dns_name_is_root(dns_resource_key_name(rr->key))) {
+ /* If the OPT RR is not owned by the root domain, then it is bad,
+ * let's ignore it. */
+ log_debug("OPT RR is not owned by root domain, ignoring.");
+ bad_opt = true;
+ continue;
+ }
- if (i < DNS_PACKET_ANCOUNT(p) + DNS_PACKET_NSCOUNT(p)) {
- /* OPT RR is in the wrong section? Some Belkin routers do this. This is a hint
- * the EDNS implementation is borked, like the Belkin one is, hence ignore
- * it. */
- log_debug("OPT RR in wrong section, ignoring.");
- bad_opt = true;
- continue;
+ if (i < DNS_PACKET_ANCOUNT(p) + DNS_PACKET_NSCOUNT(p)) {
+ /* OPT RR is in the wrong section? Some Belkin routers do this. This
+ * is a hint the EDNS implementation is borked, like the Belkin one
+ * is, hence ignore it. */
+ log_debug("OPT RR in wrong section, ignoring.");
+ bad_opt = true;
+ continue;
+ }
+
+ if (!opt_is_good(rr, &has_rfc6975)) {
+ log_debug("Malformed OPT RR, ignoring.");
+ bad_opt = true;
+ continue;
+ }
+
+ if (DNS_PACKET_QR(p)) {
+ /* Additional checks for responses */
+
+ if (!DNS_RESOURCE_RECORD_OPT_VERSION_SUPPORTED(rr)) {
+ /* If this is a reply and we don't know the EDNS version
+ * then something is weird... */
+ log_debug("EDNS version newer that our request, bad server.");
+ return -EBADMSG;
}
- if (!opt_is_good(rr, &has_rfc6975)) {
- log_debug("Malformed OPT RR, ignoring.");
+ if (has_rfc6975) {
+ /* If the OPT RR contains RFC6975 algorithm data, then this
+ * is indication that the server just copied the OPT it got
+ * from us (which contained that data) back into the reply.
+ * If so, then it doesn't properly support EDNS, as RFC6975
+ * makes it very clear that the algorithm data should only
+ * be contained in questions, never in replies. Crappy
+ * Belkin routers copy the OPT data for example, hence let's
+ * detect this so that we downgrade early. */
+ log_debug("OPT RR contained RFC6975 data, ignoring.");
bad_opt = true;
continue;
}
+ }
- if (DNS_PACKET_QR(p)) {
- /* Additional checks for responses */
-
- if (!DNS_RESOURCE_RECORD_OPT_VERSION_SUPPORTED(rr)) {
- /* If this is a reply and we don't know the EDNS version then something
- * is weird... */
- log_debug("EDNS version newer that our request, bad server.");
- return -EBADMSG;
- }
-
- if (has_rfc6975) {
- /* If the OPT RR contains RFC6975 algorithm data, then this is indication that
- * the server just copied the OPT it got from us (which contained that data)
- * back into the reply. If so, then it doesn't properly support EDNS, as
- * RFC6975 makes it very clear that the algorithm data should only be contained
- * in questions, never in replies. Crappy Belkin routers copy the OPT data for
- * example, hence let's detect this so that we downgrade early. */
- log_debug("OPT RR contained RFC6975 data, ignoring.");
- bad_opt = true;
- continue;
- }
- }
+ p->opt = dns_resource_record_ref(rr);
+ } else {
+ /* According to RFC 4795, section 2.9. only the RRs from the Answer section
+ * shall be cached. Hence mark only those RRs as cacheable by default, but
+ * not the ones from the Additional or Authority sections. */
+ DnsAnswerFlags flags =
+ (i < DNS_PACKET_ANCOUNT(p) ? DNS_ANSWER_CACHEABLE : 0) |
+ (p->protocol == DNS_PROTOCOL_MDNS && !cache_flush ? DNS_ANSWER_SHARED_OWNER : 0);
+
+ r = dns_answer_add(answer, rr, p->ifindex, flags);
+ if (r < 0)
+ return r;
+ }
- p->opt = dns_resource_record_ref(rr);
- } else {
+ /* Remember this RR, so that we potentically can merge it's ->key object with the
+ * next RR. Note that we only do this if we actually decided to keep the RR around.
+ */
+ dns_resource_record_unref(previous);
+ previous = dns_resource_record_ref(rr);
+ }
- /* According to RFC 4795, section 2.9. only the RRs from the Answer section shall be
- * cached. Hence mark only those RRs as cacheable by default, but not the ones from the
- * Additional or Authority sections. */
+ if (bad_opt)
+ p->opt = dns_resource_record_unref(p->opt);
- r = dns_answer_add(answer, rr, p->ifindex,
- (i < DNS_PACKET_ANCOUNT(p) ? DNS_ANSWER_CACHEABLE : 0) |
- (p->protocol == DNS_PROTOCOL_MDNS && !cache_flush ? DNS_ANSWER_SHARED_OWNER : 0));
- if (r < 0)
- return r;
- }
+ *ret_answer = answer;
+ answer = NULL;
+ return 0;
+}
- /* Remember this RR, so that we potentically can merge it's ->key object with the next RR. Note
- * that we only do this if we actually decided to keep the RR around. */
- dns_resource_record_unref(previous);
- previous = dns_resource_record_ref(rr);
- }
+int dns_packet_extract(DnsPacket *p) {
+ _cleanup_(dns_question_unrefp) DnsQuestion *question = NULL;
+ _cleanup_(dns_answer_unrefp) DnsAnswer *answer = NULL;
+ _cleanup_(rewind_dns_packet) DnsPacketRewinder rewinder = {};
+ int r;
- if (bad_opt)
- p->opt = dns_resource_record_unref(p->opt);
- }
+ if (p->extracted)
+ return 0;
+
+ INIT_REWINDER(rewinder, p);
+ dns_packet_rewind(p, DNS_PACKET_HEADER_SIZE);
+
+ r = dns_packet_extract_question(p, &question);
+ if (r < 0)
+ return r;
+
+ r = dns_packet_extract_answer(p, &answer);
+ if (r < 0)
+ return r;
p->question = question;
question = NULL;
projects / thirdparty / systemd.git / commitdiff
