+/* SPDX-License-Identifier: LGPL-2.1+ */
/***
This file is part of systemd.
#include <netinet/in.h>
#include <arpa/inet.h>
+#include "alloc-util.h"
#include "fd-util.h"
#include "resolved-manager.h"
#include "resolved-mdns.h"
+#define CLEAR_CACHE_FLUSH(x) (~MDNS_RR_CACHE_FLUSH & (x))
+
void manager_mdns_stop(Manager *m) {
assert(m);
return 0;
}
+static int mdns_rr_compare(const void *a, const void *b) {
+ DnsResourceRecord **x = (DnsResourceRecord**) a, **y = (DnsResourceRecord**) b;
+ size_t m;
+ int r;
+
+ assert(x);
+ assert(*x);
+ assert(y);
+ assert(*y);
+
+ if (CLEAR_CACHE_FLUSH((*x)->key->class) < CLEAR_CACHE_FLUSH((*y)->key->class))
+ return -1;
+ else if (CLEAR_CACHE_FLUSH((*x)->key->class) > CLEAR_CACHE_FLUSH((*y)->key->class))
+ return 1;
+
+ if ((*x)->key->type < (*y)->key->type)
+ return -1;
+ else if ((*x)->key->type > (*y)->key->type)
+ return 1;
+
+ r = dns_resource_record_to_wire_format(*x, false);
+ if (r < 0) {
+ log_warning_errno(r, "Can't wire-format RR: %m");
+ return 0;
+ }
+
+ r = dns_resource_record_to_wire_format(*y, false);
+ if (r < 0) {
+ log_warning_errno(r, "Can't wire-format RR: %m");
+ return 0;
+ }
+
+ m = MIN(DNS_RESOURCE_RECORD_RDATA_SIZE(*x), DNS_RESOURCE_RECORD_RDATA_SIZE(*y));
+
+ r = memcmp(DNS_RESOURCE_RECORD_RDATA(*x), DNS_RESOURCE_RECORD_RDATA(*y), m);
+ if (r != 0)
+ return r;
+
+ if (DNS_RESOURCE_RECORD_RDATA_SIZE(*x) < DNS_RESOURCE_RECORD_RDATA_SIZE(*y))
+ return -1;
+ else if (DNS_RESOURCE_RECORD_RDATA_SIZE(*x) > DNS_RESOURCE_RECORD_RDATA_SIZE(*y))
+ return 1;
+
+ return 0;
+}
+
+static int proposed_rrs_cmp(DnsResourceRecord **x, unsigned x_size, DnsResourceRecord **y, unsigned y_size) {
+ unsigned m;
+ int r;
+
+ m = MIN(x_size, y_size);
+ for (unsigned i = 0; i < m; i++) {
+ r = mdns_rr_compare(&x[i], &y[i]);
+ if (r != 0)
+ return r;
+ }
+
+ if (x_size < y_size)
+ return -1;
+ if (x_size > y_size)
+ return 1;
+
+ return 0;
+}
+
+static int mdns_packet_extract_matching_rrs(DnsPacket *p, DnsResourceKey *key, DnsResourceRecord ***ret_rrs) {
+ _cleanup_free_ DnsResourceRecord **list = NULL;
+ unsigned n = 0, size = 0;
+ int r;
+
+ assert(p);
+ assert(key);
+ assert(ret_rrs);
+ assert_return(DNS_PACKET_NSCOUNT(p) > 0, -EINVAL);
+
+ for (unsigned i = DNS_PACKET_ANCOUNT(p); i < (DNS_PACKET_ANCOUNT(p) + DNS_PACKET_NSCOUNT(p)); i++) {
+ r = dns_resource_key_match_rr(key, p->answer->items[i].rr, NULL);
+ if (r < 0)
+ return r;
+ if (r > 0)
+ size++;
+ }
+
+ if (size == 0)
+ return 0;
+
+ list = new(DnsResourceRecord *, size);
+ if (!list)
+ return -ENOMEM;
+
+ for (unsigned i = DNS_PACKET_ANCOUNT(p); i < (DNS_PACKET_ANCOUNT(p) + DNS_PACKET_NSCOUNT(p)); i++) {
+ r = dns_resource_key_match_rr(key, p->answer->items[i].rr, NULL);
+ if (r < 0)
+ return r;
+ if (r > 0)
+ list[n++] = p->answer->items[i].rr;
+ }
+ assert(n == size);
+ qsort_safe(list, size, sizeof(DnsResourceRecord*), mdns_rr_compare);
+
+ *ret_rrs = TAKE_PTR(list);
+
+ return size;
+}
+
+static int mdns_do_tiebreak(DnsResourceKey *key, DnsAnswer *answer, DnsPacket *p) {
+ _cleanup_free_ DnsResourceRecord **our = NULL, **remote = NULL;
+ DnsResourceRecord *rr;
+ unsigned i = 0;
+ unsigned size;
+ int r;
+
+ size = dns_answer_size(answer);
+ our = new(DnsResourceRecord *, size);
+ if (!our)
+ return -ENOMEM;
+
+ DNS_ANSWER_FOREACH(rr, answer)
+ our[i++] = rr;
+ qsort_safe(our, size, sizeof(DnsResourceRecord*), mdns_rr_compare);
+
+ r = mdns_packet_extract_matching_rrs(p, key, &remote);
+ if (r < 0)
+ return r;
+
+ assert(r > 0);
+
+ if (proposed_rrs_cmp(remote, r, our, size) > 0)
+ return 1;
+
+ return 0;
+}
+
static int mdns_scope_process_query(DnsScope *s, DnsPacket *p) {
- _cleanup_(dns_answer_unrefp) DnsAnswer *answer = NULL, *soa = NULL;
+ _cleanup_(dns_answer_unrefp) DnsAnswer *full_answer = NULL;
_cleanup_(dns_packet_unrefp) DnsPacket *reply = NULL;
DnsResourceKey *key = NULL;
+ DnsResourceRecord *rr;
bool tentative = false;
int r;
if (r < 0)
return log_debug_errno(r, "Failed to extract resource records from incoming packet: %m");
- /* TODO: there might be more than one question in mDNS queries. */
assert_return((dns_question_size(p->question) > 0), -EINVAL);
- key = p->question->keys[0];
- r = dns_zone_lookup(&s->zone, key, 0, &answer, &soa, &tentative);
- if (r < 0) {
- log_debug_errno(r, "Failed to lookup key: %m");
- return r;
+ DNS_QUESTION_FOREACH(key, p->question) {
+ _cleanup_(dns_answer_unrefp) DnsAnswer *answer = NULL, *soa = NULL;
+
+ r = dns_zone_lookup(&s->zone, key, 0, &answer, &soa, &tentative);
+ if (r < 0)
+ return log_debug_errno(r, "Failed to lookup key: %m");
+
+ if (tentative && DNS_PACKET_NSCOUNT(p) > 0) {
+ /*
+ * A race condition detected with the probe packet from
+ * a remote host.
+ * Do simultaneous probe tiebreaking as described in
+ * RFC 6762, Section 8.2. In case we lost don't reply
+ * the question and withdraw conflicting RRs.
+ */
+ r = mdns_do_tiebreak(key, answer, p);
+ if (r < 0)
+ return log_debug_errno(r, "Failed to do tiebreaking");
+
+ if (r > 0) { /* we lost */
+ DNS_ANSWER_FOREACH(rr, answer) {
+ DnsZoneItem *i;
+
+ i = dns_zone_get(&s->zone, rr);
+ if (i)
+ dns_zone_item_conflict(i);
+ }
+
+ continue;
+ }
+ }
+
+ r = dns_answer_extend(&full_answer, answer);
+ if (r < 0)
+ return log_debug_errno(r, "Failed to extend answer: %m");
}
- if (r == 0)
+
+ if (dns_answer_isempty(full_answer))
return 0;
- r = dns_scope_make_reply_packet(s, DNS_PACKET_ID(p), DNS_RCODE_SUCCESS, NULL, answer, NULL, false, &reply);
- if (r < 0) {
- log_debug_errno(r, "Failed to build reply packet: %m");
- return r;
- }
+ r = dns_scope_make_reply_packet(s, DNS_PACKET_ID(p), DNS_RCODE_SUCCESS, NULL, full_answer, NULL, false, &reply);
+ if (r < 0)
+ return log_debug_errno(r, "Failed to build reply packet: %m");
if (!ratelimit_test(&s->ratelimit))
return 0;
r = dns_scope_emit_udp(s, -1, reply);
- if (r < 0) {
- log_debug_errno(r, "Failed to send reply packet: %m");
- return r;
- }
+ if (r < 0)
+ return log_debug_errno(r, "Failed to send reply packet: %m");
return 0;
}
scope = manager_find_scope(m, p);
if (!scope) {
- log_warning("Got mDNS UDP packet on unknown scope. Ignoring.");
+ log_debug("Got mDNS UDP packet on unknown scope. Ignoring.");
return 0;
}
projects / thirdparty / systemd.git / blobdiff