#include "resolved-dns-domain.h"
#include "resolved-dns-scope.h"
+#define MULTICAST_RATELIMIT_INTERVAL_USEC (1*USEC_PER_SEC)
+#define MULTICAST_RATELIMIT_BURST 1000
+
int dns_scope_new(Manager *m, DnsScope **ret, Link *l, DnsProtocol protocol, int family) {
DnsScope *s;
log_debug("New scope on link %s, protocol %s, family %s", l ? l->name : "*", dns_protocol_to_string(protocol), family == AF_UNSPEC ? "*" : af_to_name(family));
+ /* Enforce ratelimiting for the multicast protocols */
+ RATELIMIT_INIT(s->ratelimit, MULTICAST_RATELIMIT_INTERVAL_USEC, MULTICAST_RATELIMIT_BURST);
+
*ret = s;
return 0;
}
DnsScope* dns_scope_free(DnsScope *s) {
DnsTransaction *t;
+ DnsResourceRecord *rr;
if (!s)
return NULL;
dns_transaction_free(t);
}
+ while ((rr = ordered_hashmap_steal_first(s->conflict_queue)))
+ dns_resource_record_unref(rr);
+
+ ordered_hashmap_free(s->conflict_queue);
+ sd_event_source_unref(s->conflict_event_source);
+
dns_cache_flush(&s->cache);
dns_zone_flush(&s->zone);
manager_next_dns_server(s->manager);
}
-int dns_scope_send(DnsScope *s, DnsPacket *p) {
+int dns_scope_emit(DnsScope *s, DnsPacket *p) {
union in_addr_union addr;
int ifindex = 0, r;
int family;
if (DNS_PACKET_QDCOUNT(p) > 1)
return -ENOTSUP;
+ if (!ratelimit_test(&s->ratelimit))
+ return -EBUSY;
+
family = s->family;
port = 5355;
return ret;
}
-DnsScopeMatch dns_scope_good_domain(DnsScope *s, const char *domain) {
+DnsScopeMatch dns_scope_good_domain(DnsScope *s, int ifindex, uint64_t flags, const char *domain) {
char **i;
assert(s);
assert(domain);
+ if (ifindex != 0 && (!s->link || s->link->ifindex != ifindex))
+ return DNS_SCOPE_NO;
+
+ if ((SD_RESOLVED_FLAGS_MAKE(s->protocol, s->family) & flags) == 0)
+ return DNS_SCOPE_NO;
+
STRV_FOREACH(i, s->domains)
if (dns_name_endswith(domain, *i) > 0)
return DNS_SCOPE_YES;
if (s->protocol == DNS_PROTOCOL_LLMNR) {
if (dns_name_endswith(domain, "in-addr.arpa") > 0 ||
dns_name_endswith(domain, "ip6.arpa") > 0 ||
- dns_name_single_label(domain) > 0)
+ (dns_name_single_label(domain) > 0 &&
+ dns_name_equal(domain, "gateway") <= 0)) /* don't resolve "gateway" with LLMNR, let nss-myhostname handle this */
return DNS_SCOPE_MAYBE;
return DNS_SCOPE_NO;
int dns_scope_llmnr_membership(DnsScope *s, bool b) {
int fd;
+ assert(s);
+
+ if (s->protocol != DNS_PROTOCOL_LLMNR)
+ return 0;
+
+ assert(s->link);
+
if (s->family == AF_INET) {
struct ip_mreqn mreqn = {
.imr_multiaddr = LLMNR_MULTICAST_IPV4_ADDRESS,
if (fd < 0)
return fd;
+ /* Always first try to drop membership before we add
+ * one. This is necessary on some devices, such as
+ * veth. */
+ if (b)
+ (void)setsockopt(fd, IPPROTO_IP, IP_DROP_MEMBERSHIP, &mreqn, sizeof(mreqn));
+
if (setsockopt(fd, IPPROTO_IP, b ? IP_ADD_MEMBERSHIP : IP_DROP_MEMBERSHIP, &mreqn, sizeof(mreqn)) < 0)
return -errno;
if (fd < 0)
return fd;
+ if (b)
+ (void)setsockopt(fd, IPPROTO_IPV6, IPV6_DROP_MEMBERSHIP, &mreq, sizeof(mreq));
+
if (setsockopt(fd, IPPROTO_IPV6, b ? IPV6_ADD_MEMBERSHIP : IPV6_DROP_MEMBERSHIP, &mreq, sizeof(mreq)) < 0)
return -errno;
} else
int r;
assert(s);
+ assert(ret);
- if (q->n_keys <= 0 && answer->n_rrs <= 0 && soa->n_rrs <= 0)
+ if ((!q || q->n_keys <= 0)
+ && (!answer || answer->n_rrs <= 0)
+ && (!soa || soa->n_rrs <= 0))
return -EINVAL;
r = dns_packet_new(&p, s->protocol, 0);
return 0;
}
+static void dns_scope_verify_conflicts(DnsScope *s, DnsPacket *p) {
+ unsigned n;
+
+ assert(s);
+ assert(p);
+
+ if (p->question)
+ for (n = 0; n < p->question->n_keys; n++)
+ dns_zone_verify_conflicts(&s->zone, p->question->keys[n]);
+ if (p->answer)
+ for (n = 0; n < p->answer->n_rrs; n++)
+ dns_zone_verify_conflicts(&s->zone, p->answer->rrs[n]->key);
+}
+
void dns_scope_process_query(DnsScope *s, DnsStream *stream, DnsPacket *p) {
_cleanup_(dns_packet_unrefp) DnsPacket *reply = NULL;
_cleanup_(dns_answer_unrefp) DnsAnswer *answer = NULL, *soa = NULL;
if (p->ipproto == IPPROTO_UDP) {
/* Don't accept UDP queries directed to anything but
* the LLMNR multicast addresses. See RFC 4795,
- * section 2.5.*/
+ * section 2.5. */
if (p->family == AF_INET && !in_addr_equal(AF_INET, &p->destination, (union in_addr_union*) &LLMNR_MULTICAST_IPV4_ADDRESS))
return;
r = dns_packet_extract(p);
if (r < 0) {
- log_debug("Failed to extract resources from incoming packet: %s", strerror(-r));
+ log_debug_errno(r, "Failed to extract resources from incoming packet: %m");
return;
}
if (DNS_PACKET_C(p)) {
- /* FIXME: Somebody notified us about a likely conflict */
+ /* Somebody notified us about a possible conflict */
+ dns_scope_verify_conflicts(s, p);
return;
}
r = dns_zone_lookup(&s->zone, p->question, &answer, &soa, &tentative);
if (r < 0) {
- log_debug("Failed to lookup key: %s", strerror(-r));
+ log_debug_errno(r, "Failed to lookup key: %m");
return;
}
if (r == 0)
r = dns_scope_make_reply_packet(s, DNS_PACKET_ID(p), DNS_RCODE_SUCCESS, p->question, answer, soa, tentative, &reply);
if (r < 0) {
- log_debug("Failed to build reply packet: %s", strerror(-r));
+ log_debug_errno(r, "Failed to build reply packet: %m");
return;
}
if (stream)
r = dns_stream_write_packet(stream, reply);
else {
+ if (!ratelimit_test(&s->ratelimit))
+ return;
+
if (p->family == AF_INET)
fd = manager_llmnr_ipv4_udp_fd(s->manager);
else if (p->family == AF_INET6)
return;
}
if (fd < 0) {
- log_debug("Failed to get reply socket: %s", strerror(-fd));
+ log_debug_errno(fd, "Failed to get reply socket: %m");
return;
}
+ /* Note that we always immediately reply to all LLMNR
+ * requests, and do not wait any time, since we
+ * verified uniqueness for all records. Also see RFC
+ * 4795, Section 2.7 */
+
r = manager_send(s->manager, fd, p->ifindex, p->family, &p->sender, p->sender_port, reply);
}
if (r < 0) {
- log_debug("Failed to send reply packet: %s", strerror(-r));
+ log_debug_errno(r, "Failed to send reply packet: %m");
return;
}
}
-DnsTransaction *dns_scope_find_transaction(DnsScope *scope, DnsQuestion *question) {
+DnsTransaction *dns_scope_find_transaction(DnsScope *scope, DnsQuestion *question, bool cache_ok) {
DnsTransaction *t;
assert(scope);
/* Try to find an ongoing transaction that is a equal or a
* superset of the specified question */
- LIST_FOREACH(transactions_by_scope, t, scope->transactions)
+ LIST_FOREACH(transactions_by_scope, t, scope->transactions) {
+
+ /* Refuse reusing transactions that completed based on
+ * cached data instead of a real packet, if that's
+ * requested. */
+ if (!cache_ok &&
+ IN_SET(t->state, DNS_TRANSACTION_SUCCESS, DNS_TRANSACTION_FAILURE) &&
+ !t->received)
+ continue;
+
if (dns_question_is_superset(t->question, question) > 0)
return t;
+ }
return NULL;
}
+
+static int dns_scope_make_conflict_packet(
+ DnsScope *s,
+ DnsResourceRecord *rr,
+ DnsPacket **ret) {
+
+ _cleanup_(dns_packet_unrefp) DnsPacket *p = NULL;
+ int r;
+
+ assert(s);
+ assert(rr);
+ assert(ret);
+
+ r = dns_packet_new(&p, s->protocol, 0);
+ if (r < 0)
+ return r;
+
+ DNS_PACKET_HEADER(p)->flags = htobe16(DNS_PACKET_MAKE_FLAGS(
+ 0 /* qr */,
+ 0 /* opcode */,
+ 1 /* conflict */,
+ 0 /* tc */,
+ 0 /* t */,
+ 0 /* (ra) */,
+ 0 /* (ad) */,
+ 0 /* (cd) */,
+ 0));
+ random_bytes(&DNS_PACKET_HEADER(p)->id, sizeof(uint16_t));
+ DNS_PACKET_HEADER(p)->qdcount = htobe16(1);
+ DNS_PACKET_HEADER(p)->arcount = htobe16(1);
+
+ r = dns_packet_append_key(p, rr->key, NULL);
+ if (r < 0)
+ return r;
+
+ r = dns_packet_append_rr(p, rr, NULL);
+ if (r < 0)
+ return r;
+
+ *ret = p;
+ p = NULL;
+
+ return 0;
+}
+
+static int on_conflict_dispatch(sd_event_source *es, usec_t usec, void *userdata) {
+ DnsScope *scope = userdata;
+ int r;
+
+ assert(es);
+ assert(scope);
+
+ scope->conflict_event_source = sd_event_source_unref(scope->conflict_event_source);
+
+ for (;;) {
+ _cleanup_(dns_resource_record_unrefp) DnsResourceRecord *rr = NULL;
+ _cleanup_(dns_packet_unrefp) DnsPacket *p = NULL;
+
+ rr = ordered_hashmap_steal_first(scope->conflict_queue);
+ if (!rr)
+ break;
+
+ r = dns_scope_make_conflict_packet(scope, rr, &p);
+ if (r < 0) {
+ log_error_errno(r, "Failed to make conflict packet: %m");
+ return 0;
+ }
+
+ r = dns_scope_emit(scope, p);
+ if (r < 0)
+ log_debug_errno(r, "Failed to send conflict packet: %m");
+ }
+
+ return 0;
+}
+
+int dns_scope_notify_conflict(DnsScope *scope, DnsResourceRecord *rr) {
+ usec_t jitter;
+ int r;
+
+ assert(scope);
+ assert(rr);
+
+ /* We don't send these queries immediately. Instead, we queue
+ * them, and send them after some jitter delay. */
+ r = ordered_hashmap_ensure_allocated(&scope->conflict_queue, &dns_resource_key_hash_ops);
+ if (r < 0) {
+ log_oom();
+ return r;
+ }
+
+ /* We only place one RR per key in the conflict
+ * messages, not all of them. That should be enough to
+ * indicate where there might be a conflict */
+ r = ordered_hashmap_put(scope->conflict_queue, rr->key, rr);
+ if (r == -EEXIST || r == 0)
+ return 0;
+ if (r < 0)
+ return log_debug_errno(r, "Failed to queue conflicting RR: %m");
+
+ dns_resource_record_ref(rr);
+
+ if (scope->conflict_event_source)
+ return 0;
+
+ random_bytes(&jitter, sizeof(jitter));
+ jitter %= LLMNR_JITTER_INTERVAL_USEC;
+
+ r = sd_event_add_time(scope->manager->event,
+ &scope->conflict_event_source,
+ clock_boottime_or_monotonic(),
+ now(clock_boottime_or_monotonic()) + jitter,
+ LLMNR_JITTER_INTERVAL_USEC,
+ on_conflict_dispatch, scope);
+ if (r < 0)
+ return log_debug_errno(r, "Failed to add conflict dispatch event: %m");
+
+ return 0;
+}
+
+void dns_scope_check_conflicts(DnsScope *scope, DnsPacket *p) {
+ unsigned i;
+ int r;
+
+ assert(scope);
+ assert(p);
+
+ if (p->protocol != DNS_PROTOCOL_LLMNR)
+ return;
+
+ if (DNS_PACKET_RRCOUNT(p) <= 0)
+ return;
+
+ if (DNS_PACKET_C(p) != 0)
+ return;
+
+ if (DNS_PACKET_T(p) != 0)
+ return;
+
+ if (manager_our_packet(scope->manager, p))
+ return;
+
+ r = dns_packet_extract(p);
+ if (r < 0) {
+ log_debug_errno(r, "Failed to extract packet: %m");
+ return;
+ }
+
+ log_debug("Checking for conflicts...");
+
+ for (i = 0; i < p->answer->n_rrs; i++) {
+
+ /* Check for conflicts against the local zone. If we
+ * found one, we won't check any further */
+ r = dns_zone_check_conflicts(&scope->zone, p->answer->rrs[i]);
+ if (r != 0)
+ continue;
+
+ /* Check for conflicts against the local cache. If so,
+ * send out an advisory query, to inform everybody */
+ r = dns_cache_check_conflicts(&scope->cache, p->answer->rrs[i], p->family, &p->sender);
+ if (r <= 0)
+ continue;
+
+ dns_scope_notify_conflict(scope, p->answer->rrs[i]);
+ }
+}
~ianmdlvl / elogind.git / blobdiff