1 /* SPDX-License-Identifier: LGPL-2.1-or-later */
3 #include <netinet/tcp.h>
6 #include "alloc-util.h"
7 #include "dns-domain.h"
8 #include "errno-util.h"
10 #include "hostname-util.h"
11 #include "missing_network.h"
12 #include "random-util.h"
13 #include "resolved-dnssd.h"
14 #include "resolved-dns-scope.h"
15 #include "resolved-dns-zone.h"
16 #include "resolved-llmnr.h"
17 #include "resolved-mdns.h"
18 #include "socket-util.h"
21 #define MULTICAST_RATELIMIT_INTERVAL_USEC (1*USEC_PER_SEC)
22 #define MULTICAST_RATELIMIT_BURST 1000
24 /* After how much time to repeat LLMNR requests, see RFC 4795 Section 7 */
25 #define MULTICAST_RESEND_TIMEOUT_MIN_USEC (100 * USEC_PER_MSEC)
26 #define MULTICAST_RESEND_TIMEOUT_MAX_USEC (1 * USEC_PER_SEC)
28 int dns_scope_new(Manager
*m
, DnsScope
**ret
, Link
*l
, DnsProtocol protocol
, int family
) {
43 .resend_timeout
= MULTICAST_RESEND_TIMEOUT_MIN_USEC
,
46 if (protocol
== DNS_PROTOCOL_DNS
) {
47 /* Copy DNSSEC mode from the link if it is set there,
48 * otherwise take the manager's DNSSEC mode. Note that
49 * we copy this only at scope creation time, and do
50 * not update it from the on, even if the setting
54 s
->dnssec_mode
= link_get_dnssec_mode(l
);
55 s
->dns_over_tls_mode
= link_get_dns_over_tls_mode(l
);
57 s
->dnssec_mode
= manager_get_dnssec_mode(m
);
58 s
->dns_over_tls_mode
= manager_get_dns_over_tls_mode(m
);
62 s
->dnssec_mode
= DNSSEC_NO
;
63 s
->dns_over_tls_mode
= DNS_OVER_TLS_NO
;
66 LIST_PREPEND(scopes
, m
->dns_scopes
, s
);
68 dns_scope_llmnr_membership(s
, true);
69 dns_scope_mdns_membership(s
, true);
71 log_debug("New scope on link %s, protocol %s, family %s", l
? l
->ifname
: "*", dns_protocol_to_string(protocol
), family
== AF_UNSPEC
? "*" : af_to_name(family
));
73 /* Enforce ratelimiting for the multicast protocols */
74 s
->ratelimit
= (const RateLimit
) { MULTICAST_RATELIMIT_INTERVAL_USEC
, MULTICAST_RATELIMIT_BURST
};
80 static void dns_scope_abort_transactions(DnsScope
*s
) {
83 while (s
->transactions
) {
84 DnsTransaction
*t
= s
->transactions
;
86 /* Abort the transaction, but make sure it is not
87 * freed while we still look at it */
90 if (DNS_TRANSACTION_IS_LIVE(t
->state
))
91 dns_transaction_complete(t
, DNS_TRANSACTION_ABORTED
);
94 dns_transaction_free(t
);
98 DnsScope
* dns_scope_free(DnsScope
*s
) {
102 log_debug("Removing scope on link %s, protocol %s, family %s", s
->link
? s
->link
->ifname
: "*", dns_protocol_to_string(s
->protocol
), s
->family
== AF_UNSPEC
? "*" : af_to_name(s
->family
));
104 dns_scope_llmnr_membership(s
, false);
105 dns_scope_mdns_membership(s
, false);
106 dns_scope_abort_transactions(s
);
108 while (s
->query_candidates
)
109 dns_query_candidate_unref(s
->query_candidates
);
111 hashmap_free(s
->transactions_by_key
);
113 ordered_hashmap_free_with_destructor(s
->conflict_queue
, dns_resource_record_unref
);
114 sd_event_source_disable_unref(s
->conflict_event_source
);
116 sd_event_source_disable_unref(s
->announce_event_source
);
118 dns_cache_flush(&s
->cache
);
119 dns_zone_flush(&s
->zone
);
121 LIST_REMOVE(scopes
, s
->manager
->dns_scopes
, s
);
125 DnsServer
*dns_scope_get_dns_server(DnsScope
*s
) {
128 if (s
->protocol
!= DNS_PROTOCOL_DNS
)
132 return link_get_dns_server(s
->link
);
134 return manager_get_dns_server(s
->manager
);
137 unsigned dns_scope_get_n_dns_servers(DnsScope
*s
) {
143 if (s
->protocol
!= DNS_PROTOCOL_DNS
)
147 i
= s
->link
->dns_servers
;
149 i
= s
->manager
->dns_servers
;
151 for (; i
; i
= i
->servers_next
)
157 void dns_scope_next_dns_server(DnsScope
*s
, DnsServer
*if_current
) {
160 if (s
->protocol
!= DNS_PROTOCOL_DNS
)
163 /* Changes to the next DNS server in the list. If 'if_current' is passed will do so only if the
164 * current DNS server still matches it. */
167 link_next_dns_server(s
->link
, if_current
);
169 manager_next_dns_server(s
->manager
, if_current
);
172 void dns_scope_packet_received(DnsScope
*s
, usec_t rtt
) {
175 if (rtt
<= s
->max_rtt
)
179 s
->resend_timeout
= MIN(MAX(MULTICAST_RESEND_TIMEOUT_MIN_USEC
, s
->max_rtt
* 2), MULTICAST_RESEND_TIMEOUT_MAX_USEC
);
182 void dns_scope_packet_lost(DnsScope
*s
, usec_t usec
) {
185 if (s
->resend_timeout
<= usec
)
186 s
->resend_timeout
= MIN(s
->resend_timeout
* 2, MULTICAST_RESEND_TIMEOUT_MAX_USEC
);
189 static int dns_scope_emit_one(DnsScope
*s
, int fd
, int family
, DnsPacket
*p
) {
194 assert(p
->protocol
== s
->protocol
);
196 if (family
== AF_UNSPEC
) {
197 if (s
->family
== AF_UNSPEC
)
198 return -EAFNOSUPPORT
;
203 switch (s
->protocol
) {
205 case DNS_PROTOCOL_DNS
: {
206 size_t mtu
, udp_size
, min_mtu
, socket_mtu
= 0;
210 if (DNS_PACKET_QDCOUNT(p
) > 1) /* Classic DNS only allows one question per packet */
213 if (p
->size
> DNS_PACKET_UNICAST_SIZE_MAX
)
216 /* Determine the local most accurate MTU */
220 mtu
= manager_find_mtu(s
->manager
);
222 /* Acquire the socket's PMDU MTU */
223 r
= socket_get_mtu(fd
, family
, &socket_mtu
);
224 if (r
< 0 && !ERRNO_IS_DISCONNECT(r
)) /* Will return ENOTCONN if no information is available yet */
225 return log_debug_errno(r
, "Failed to read socket MTU: %m");
227 /* Determine the appropriate UDP header size */
228 udp_size
= udp_header_size(family
);
229 min_mtu
= udp_size
+ DNS_PACKET_HEADER_SIZE
;
231 log_debug("Emitting UDP, link MTU is %zu, socket MTU is %zu, minimal MTU is %zu",
232 mtu
, socket_mtu
, min_mtu
);
234 /* Clamp by the kernel's idea of the (path) MTU */
235 if (socket_mtu
!= 0 && socket_mtu
< mtu
)
238 /* Put a lower limit, in case all MTU data we acquired was rubbish */
242 /* Now check our packet size against the MTU we determined */
243 if (udp_size
+ p
->size
> mtu
)
244 return -EMSGSIZE
; /* This means: try TCP instead */
246 r
= manager_write(s
->manager
, fd
, p
);
253 case DNS_PROTOCOL_LLMNR
: {
254 union in_addr_union addr
;
258 if (DNS_PACKET_QDCOUNT(p
) > 1)
261 if (!ratelimit_below(&s
->ratelimit
))
264 if (family
== AF_INET
) {
265 addr
.in
= LLMNR_MULTICAST_IPV4_ADDRESS
;
266 fd
= manager_llmnr_ipv4_udp_fd(s
->manager
);
267 } else if (family
== AF_INET6
) {
268 addr
.in6
= LLMNR_MULTICAST_IPV6_ADDRESS
;
269 fd
= manager_llmnr_ipv6_udp_fd(s
->manager
);
271 return -EAFNOSUPPORT
;
275 r
= manager_send(s
->manager
, fd
, s
->link
->ifindex
, family
, &addr
, LLMNR_PORT
, NULL
, p
);
282 case DNS_PROTOCOL_MDNS
: {
283 union in_addr_union addr
;
286 if (!ratelimit_below(&s
->ratelimit
))
289 if (family
== AF_INET
) {
290 if (in4_addr_is_null(&p
->destination
.in
))
291 addr
.in
= MDNS_MULTICAST_IPV4_ADDRESS
;
293 addr
= p
->destination
;
294 fd
= manager_mdns_ipv4_fd(s
->manager
);
295 } else if (family
== AF_INET6
) {
296 if (in6_addr_is_null(&p
->destination
.in6
))
297 addr
.in6
= MDNS_MULTICAST_IPV6_ADDRESS
;
299 addr
= p
->destination
;
300 fd
= manager_mdns_ipv6_fd(s
->manager
);
302 return -EAFNOSUPPORT
;
306 r
= manager_send(s
->manager
, fd
, s
->link
->ifindex
, family
, &addr
, p
->destination_port
?: MDNS_PORT
, NULL
, p
);
314 return -EAFNOSUPPORT
;
320 int dns_scope_emit_udp(DnsScope
*s
, int fd
, int af
, DnsPacket
*p
) {
325 assert(p
->protocol
== s
->protocol
);
326 assert((s
->protocol
== DNS_PROTOCOL_DNS
) == (fd
>= 0));
329 /* If there are multiple linked packets, set the TC bit in all but the last of them */
331 assert(p
->protocol
== DNS_PROTOCOL_MDNS
);
332 dns_packet_set_flags(p
, true, true);
335 r
= dns_scope_emit_one(s
, fd
, af
, p
);
345 static int dns_scope_socket(
349 const union in_addr_union
*address
,
352 union sockaddr_union
*ret_socket_address
) {
354 _cleanup_close_
int fd
= -1;
355 union sockaddr_union sa
;
362 assert(family
== AF_UNSPEC
);
365 ifindex
= dns_server_ifindex(server
);
367 switch (server
->family
) {
369 sa
= (union sockaddr_union
) {
370 .in
.sin_family
= server
->family
,
371 .in
.sin_port
= htobe16(port
),
372 .in
.sin_addr
= server
->address
.in
,
374 salen
= sizeof(sa
.in
);
377 sa
= (union sockaddr_union
) {
378 .in6
.sin6_family
= server
->family
,
379 .in6
.sin6_port
= htobe16(port
),
380 .in6
.sin6_addr
= server
->address
.in6
,
381 .in6
.sin6_scope_id
= ifindex
,
383 salen
= sizeof(sa
.in6
);
386 return -EAFNOSUPPORT
;
389 assert(family
!= AF_UNSPEC
);
392 ifindex
= s
->link
? s
->link
->ifindex
: 0;
396 sa
= (union sockaddr_union
) {
397 .in
.sin_family
= family
,
398 .in
.sin_port
= htobe16(port
),
399 .in
.sin_addr
= address
->in
,
401 salen
= sizeof(sa
.in
);
404 sa
= (union sockaddr_union
) {
405 .in6
.sin6_family
= family
,
406 .in6
.sin6_port
= htobe16(port
),
407 .in6
.sin6_addr
= address
->in6
,
408 .in6
.sin6_scope_id
= ifindex
,
410 salen
= sizeof(sa
.in6
);
413 return -EAFNOSUPPORT
;
417 fd
= socket(sa
.sa
.sa_family
, type
|SOCK_CLOEXEC
|SOCK_NONBLOCK
, 0);
421 if (type
== SOCK_STREAM
) {
422 r
= setsockopt_int(fd
, IPPROTO_TCP
, TCP_NODELAY
, true);
428 r
= socket_set_unicast_if(fd
, sa
.sa
.sa_family
, ifindex
);
433 if (s
->protocol
== DNS_PROTOCOL_LLMNR
) {
434 /* RFC 4795, section 2.5 requires the TTL to be set to 1 */
435 r
= socket_set_ttl(fd
, sa
.sa
.sa_family
, 1);
440 if (type
== SOCK_DGRAM
) {
441 /* Set IP_RECVERR or IPV6_RECVERR to get ICMP error feedback. See discussion in #10345. */
442 r
= socket_set_recverr(fd
, sa
.sa
.sa_family
, true);
446 r
= socket_set_recvpktinfo(fd
, sa
.sa
.sa_family
, true);
450 /* Turn of path MTU discovery for security reasons */
451 r
= socket_disable_pmtud(fd
, sa
.sa
.sa_family
);
453 log_debug_errno(r
, "Failed to disable UDP PMTUD, ignoring: %m");
455 /* Learn about fragmentation taking place */
456 r
= socket_set_recvfragsize(fd
, sa
.sa
.sa_family
, true);
458 log_debug_errno(r
, "Failed to enable fragment size reception, ignoring: %m");
461 if (ret_socket_address
)
462 *ret_socket_address
= sa
;
466 /* Let's temporarily bind the socket to the specified ifindex. The kernel currently takes
467 * only the SO_BINDTODEVICE/SO_BINDTOINDEX ifindex into account when making routing decisions
468 * in connect() — and not IP_UNICAST_IF. We don't really want any of the other semantics of
469 * SO_BINDTODEVICE/SO_BINDTOINDEX, hence we immediately unbind the socket after the fact
472 * As a special exception we don't do this if we notice that the specified IP address is on
473 * the local host. SO_BINDTODEVICE in combination with destination addresses on the local
474 * host result in EHOSTUNREACH, since Linux won't send the packets out of the specified
475 * interface, but delivers them directly to the local socket. */
477 !manager_find_link_address(s
->manager
, sa
.sa
.sa_family
, sockaddr_in_addr(&sa
.sa
))) {
478 r
= socket_bind_to_ifindex(fd
, ifindex
);
485 r
= connect(fd
, &sa
.sa
, salen
);
486 if (r
< 0 && errno
!= EINPROGRESS
)
490 r
= socket_bind_to_ifindex(fd
, 0);
499 int dns_scope_socket_udp(DnsScope
*s
, DnsServer
*server
) {
500 return dns_scope_socket(s
, SOCK_DGRAM
, AF_UNSPEC
, NULL
, server
, dns_server_port(server
), NULL
);
503 int dns_scope_socket_tcp(DnsScope
*s
, int family
, const union in_addr_union
*address
, DnsServer
*server
, uint16_t port
, union sockaddr_union
*ret_socket_address
) {
504 /* If ret_socket_address is not NULL, the caller is responsible
505 * for calling connect() or sendmsg(). This is required by TCP
506 * Fast Open, to be able to send the initial SYN packet along
507 * with the first data packet. */
508 return dns_scope_socket(s
, SOCK_STREAM
, family
, address
, server
, port
, ret_socket_address
);
511 static DnsScopeMatch
match_link_local_reverse_lookups(const char *domain
) {
514 if (dns_name_endswith(domain
, "254.169.in-addr.arpa") > 0)
515 return DNS_SCOPE_YES_BASE
+ 4; /* 4 labels match */
517 if (dns_name_endswith(domain
, "8.e.f.ip6.arpa") > 0 ||
518 dns_name_endswith(domain
, "9.e.f.ip6.arpa") > 0 ||
519 dns_name_endswith(domain
, "a.e.f.ip6.arpa") > 0 ||
520 dns_name_endswith(domain
, "b.e.f.ip6.arpa") > 0)
521 return DNS_SCOPE_YES_BASE
+ 5; /* 5 labels match */
523 return _DNS_SCOPE_MATCH_INVALID
;
526 static DnsScopeMatch
match_subnet_reverse_lookups(
531 union in_addr_union ia
;
537 /* Checks whether the specified domain is a reverse address domain (i.e. in the .in-addr.arpa or
538 * .ip6.arpa area), and if so, whether the address matches any of the local subnets of the link the
539 * scope is associated with. If so, our scope should consider itself relevant for any lookup in the
540 * domain, since it apparently refers to hosts on this link's subnet.
542 * If 'exclude_own' is true this will return DNS_SCOPE_NO for any IP addresses assigned locally. This
543 * is useful for LLMNR/mDNS as we never want to look up our own hostname on LLMNR/mDNS but always use
544 * the locally synthesized one. */
547 return _DNS_SCOPE_MATCH_INVALID
; /* No link, hence no local addresses to check */
549 r
= dns_name_address(domain
, &f
, &ia
);
551 log_debug_errno(r
, "Failed to determine whether '%s' is an address domain: %m", domain
);
553 return _DNS_SCOPE_MATCH_INVALID
;
555 if (s
->family
!= AF_UNSPEC
&& f
!= s
->family
)
556 return _DNS_SCOPE_MATCH_INVALID
; /* Don't look for IPv4 addresses on LLMNR/mDNS over IPv6 and vice versa */
558 LIST_FOREACH(addresses
, a
, s
->link
->addresses
) {
563 /* Equals our own address? nah, let's not use this scope. The local synthesizer will pick it up for us. */
565 in_addr_equal(f
, &a
->in_addr
, &ia
) > 0)
568 if (a
->prefixlen
== UCHAR_MAX
) /* don't know subnet mask */
571 /* Check if the address is in the local subnet */
572 r
= in_addr_prefix_covers(f
, &a
->in_addr
, a
->prefixlen
, &ia
);
574 log_debug_errno(r
, "Failed to determine whether link address covers lookup address '%s': %m", domain
);
576 /* Note that we only claim zero labels match. This is so that this is at the same
577 * priority a DNS scope with "." as routing domain is. */
578 return DNS_SCOPE_YES_BASE
+ 0;
581 return _DNS_SCOPE_MATCH_INVALID
;
584 DnsScopeMatch
dns_scope_good_domain(
588 DnsQuestion
*question
;
593 /* This returns the following return values:
595 * DNS_SCOPE_NO → This scope is not suitable for lookups of this domain, at all
596 * DNS_SCOPE_MAYBE → This scope is suitable, but only if nothing else wants it
597 * DNS_SCOPE_YES_BASE+n → This scope is suitable, and 'n' suffix labels match
599 * (The idea is that the caller will only use the scopes with the longest 'n' returned. If no scopes return
600 * DNS_SCOPE_YES_BASE+n, then it should use those which returned DNS_SCOPE_MAYBE. It should never use those
601 * which returned DNS_SCOPE_NO.)
607 question
= dns_query_question_for_protocol(q
, s
->protocol
);
611 domain
= dns_question_first_name(question
);
615 ifindex
= q
->ifindex
;
618 /* Checks if the specified domain is something to look up on this scope. Note that this accepts
619 * non-qualified hostnames, i.e. those without any search path suffixed. */
621 if (ifindex
!= 0 && (!s
->link
|| s
->link
->ifindex
!= ifindex
))
624 if ((SD_RESOLVED_FLAGS_MAKE(s
->protocol
, s
->family
, false, false) & flags
) == 0)
627 /* Never resolve any loopback hostname or IP address via DNS, LLMNR or mDNS. Instead, always rely on
628 * synthesized RRs for these. */
629 if (is_localhost(domain
) ||
630 dns_name_endswith(domain
, "127.in-addr.arpa") > 0 ||
631 dns_name_equal(domain
, "1.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.ip6.arpa") > 0)
634 /* Never respond to some of the domains listed in RFC6303 + RFC6761 */
635 if (dns_name_dont_resolve(domain
))
638 /* Never go to network for the _gateway or _outbound domain — they're something special, synthesized locally. */
639 if (is_gateway_hostname(domain
) || is_outbound_hostname(domain
))
642 switch (s
->protocol
) {
644 case DNS_PROTOCOL_DNS
: {
645 bool has_search_domains
= false;
649 if (dns_name_is_empty(domain
)) {
653 /* Refuse empty name if only A and/or AAAA records are requested. */
655 DNS_QUESTION_FOREACH(t
, question
)
656 if (!IN_SET(t
->type
, DNS_TYPE_A
, DNS_TYPE_AAAA
)) {
665 /* Never route things to scopes that lack DNS servers */
666 if (!dns_scope_get_dns_server(s
))
669 /* Always honour search domains for routing queries, except if this scope lacks DNS servers. Note that
670 * we return DNS_SCOPE_YES here, rather than just DNS_SCOPE_MAYBE, which means other wildcard scopes
671 * won't be considered anymore. */
672 LIST_FOREACH(domains
, d
, dns_scope_get_search_domains(s
)) {
674 if (!d
->route_only
&& !dns_name_is_root(d
->name
))
675 has_search_domains
= true;
677 if (dns_name_endswith(domain
, d
->name
) > 0) {
680 c
= dns_name_count_labels(d
->name
);
689 /* If there's a true search domain defined for this scope, and the query is single-label,
690 * then let's resolve things here, prefereably. Note that LLMNR considers itself
691 * authoritative for single-label names too, at the same preference, see below. */
692 if (has_search_domains
&& dns_name_is_single_label(domain
))
693 return DNS_SCOPE_YES_BASE
+ 1;
695 /* If ResolveUnicastSingleLabel=yes and the query is single-label, then bump match result
696 to prevent LLMNR monopoly among candidates. */
697 if (s
->manager
->resolve_unicast_single_label
&& dns_name_is_single_label(domain
))
698 return DNS_SCOPE_YES_BASE
+ 1;
700 /* Let's return the number of labels in the best matching result */
702 assert(n_best
<= DNS_SCOPE_YES_END
- DNS_SCOPE_YES_BASE
);
703 return DNS_SCOPE_YES_BASE
+ n_best
;
706 /* Exclude link-local IP ranges */
707 if (match_link_local_reverse_lookups(domain
) >= DNS_SCOPE_YES_BASE
||
708 /* If networks use .local in their private setups, they are supposed to also add .local
709 * to their search domains, which we already checked above. Otherwise, we consider .local
710 * specific to mDNS and won't send such queries ordinary DNS servers. */
711 dns_name_endswith(domain
, "local") > 0)
714 /* If the IP address to look up matches the local subnet, then implicitly synthesizes
715 * DNS_SCOPE_YES_BASE + 0 on this interface, i.e. preferably resolve IP addresses via the DNS
716 * server belonging to this interface. */
717 m
= match_subnet_reverse_lookups(s
, domain
, false);
721 /* If there was no match at all, then see if this scope is suitable as default route. */
722 if (!dns_scope_is_default_route(s
))
725 return DNS_SCOPE_MAYBE
;
728 case DNS_PROTOCOL_MDNS
: {
731 m
= match_link_local_reverse_lookups(domain
);
735 m
= match_subnet_reverse_lookups(s
, domain
, true);
739 if ((s
->family
== AF_INET
&& dns_name_endswith(domain
, "in-addr.arpa") > 0) ||
740 (s
->family
== AF_INET6
&& dns_name_endswith(domain
, "ip6.arpa") > 0))
741 return DNS_SCOPE_MAYBE
;
743 if ((dns_name_endswith(domain
, "local") > 0 && /* only resolve names ending in .local via mDNS */
744 dns_name_equal(domain
, "local") == 0 && /* but not the single-label "local" name itself */
745 manager_is_own_hostname(s
->manager
, domain
) <= 0)) /* never resolve the local hostname via mDNS */
746 return DNS_SCOPE_YES_BASE
+ 1; /* Return +1, as the top-level .local domain matches, i.e. one label */
751 case DNS_PROTOCOL_LLMNR
: {
754 m
= match_link_local_reverse_lookups(domain
);
758 m
= match_subnet_reverse_lookups(s
, domain
, true);
762 if ((s
->family
== AF_INET
&& dns_name_endswith(domain
, "in-addr.arpa") > 0) ||
763 (s
->family
== AF_INET6
&& dns_name_endswith(domain
, "ip6.arpa") > 0))
764 return DNS_SCOPE_MAYBE
;
766 if ((dns_name_is_single_label(domain
) && /* only resolve single label names via LLMNR */
767 !is_gateway_hostname(domain
) && /* don't resolve "_gateway" with LLMNR, let local synthesizing logic handle that */
768 !is_outbound_hostname(domain
) && /* similar for "_outbound" */
769 dns_name_equal(domain
, "local") == 0 && /* don't resolve "local" with LLMNR, it's the top-level domain of mDNS after all, see above */
770 manager_is_own_hostname(s
->manager
, domain
) <= 0)) /* never resolve the local hostname via LLMNR */
771 return DNS_SCOPE_YES_BASE
+ 1; /* Return +1, as we consider ourselves authoritative
772 * for single-label names, i.e. one label. This is
773 * particularly relevant as it means a "." route on some
774 * other scope won't pull all traffic away from
775 * us. (If people actually want to pull traffic away
776 * from us they should turn off LLMNR on the
777 * link). Note that unicast DNS scopes with search
778 * domains also consider themselves authoritative for
779 * single-label domains, at the same preference (see
786 assert_not_reached();
790 bool dns_scope_good_key(DnsScope
*s
, const DnsResourceKey
*key
) {
796 /* Check if it makes sense to resolve the specified key on this scope. Note that this call assumes a
797 * fully qualified name, i.e. the search suffixes already appended. */
799 if (!IN_SET(key
->class, DNS_CLASS_IN
, DNS_CLASS_ANY
))
802 if (s
->protocol
== DNS_PROTOCOL_DNS
) {
804 /* On classic DNS, looking up non-address RRs is always fine. (Specifically, we want to
805 * permit looking up DNSKEY and DS records on the root and top-level domains.) */
806 if (!dns_resource_key_is_address(key
))
809 /* Unless explicitly overridden, we refuse to look up A and AAAA RRs on the root and
810 * single-label domains, under the assumption that those should be resolved via LLMNR or
811 * search path only, and should not be leaked onto the internet. */
812 const char* name
= dns_resource_key_name(key
);
814 if (!s
->manager
->resolve_unicast_single_label
&&
815 dns_name_is_single_label(name
))
818 return !dns_name_is_root(name
);
821 /* Never route DNSSEC RR queries to LLMNR/mDNS scopes */
822 if (dns_type_is_dnssec(key
->type
))
825 /* On mDNS and LLMNR, send A and AAAA queries only on the respective scopes */
827 key_family
= dns_type_to_af(key
->type
);
831 return key_family
== s
->family
;
834 static int dns_scope_multicast_membership(DnsScope
*s
, bool b
, struct in_addr in
, struct in6_addr in6
) {
840 if (s
->family
== AF_INET
) {
841 struct ip_mreqn mreqn
= {
843 .imr_ifindex
= s
->link
->ifindex
,
846 if (s
->protocol
== DNS_PROTOCOL_LLMNR
)
847 fd
= manager_llmnr_ipv4_udp_fd(s
->manager
);
849 fd
= manager_mdns_ipv4_fd(s
->manager
);
854 /* Always first try to drop membership before we add
855 * one. This is necessary on some devices, such as
858 (void) setsockopt(fd
, IPPROTO_IP
, IP_DROP_MEMBERSHIP
, &mreqn
, sizeof(mreqn
));
860 if (setsockopt(fd
, IPPROTO_IP
, b
? IP_ADD_MEMBERSHIP
: IP_DROP_MEMBERSHIP
, &mreqn
, sizeof(mreqn
)) < 0)
863 } else if (s
->family
== AF_INET6
) {
864 struct ipv6_mreq mreq
= {
865 .ipv6mr_multiaddr
= in6
,
866 .ipv6mr_interface
= s
->link
->ifindex
,
869 if (s
->protocol
== DNS_PROTOCOL_LLMNR
)
870 fd
= manager_llmnr_ipv6_udp_fd(s
->manager
);
872 fd
= manager_mdns_ipv6_fd(s
->manager
);
878 (void) setsockopt(fd
, IPPROTO_IPV6
, IPV6_DROP_MEMBERSHIP
, &mreq
, sizeof(mreq
));
880 if (setsockopt(fd
, IPPROTO_IPV6
, b
? IPV6_ADD_MEMBERSHIP
: IPV6_DROP_MEMBERSHIP
, &mreq
, sizeof(mreq
)) < 0)
883 return -EAFNOSUPPORT
;
888 int dns_scope_llmnr_membership(DnsScope
*s
, bool b
) {
891 if (s
->protocol
!= DNS_PROTOCOL_LLMNR
)
894 return dns_scope_multicast_membership(s
, b
, LLMNR_MULTICAST_IPV4_ADDRESS
, LLMNR_MULTICAST_IPV6_ADDRESS
);
897 int dns_scope_mdns_membership(DnsScope
*s
, bool b
) {
900 if (s
->protocol
!= DNS_PROTOCOL_MDNS
)
903 return dns_scope_multicast_membership(s
, b
, MDNS_MULTICAST_IPV4_ADDRESS
, MDNS_MULTICAST_IPV6_ADDRESS
);
906 int dns_scope_make_reply_packet(
916 _cleanup_(dns_packet_unrefp
) DnsPacket
*p
= NULL
;
917 unsigned n_answer
= 0, n_soa
= 0;
924 if (dns_question_isempty(q
) &&
925 dns_answer_isempty(answer
) &&
926 dns_answer_isempty(soa
))
929 r
= dns_packet_new(&p
, s
->protocol
, 0, DNS_PACKET_SIZE_MAX
);
933 /* mDNS answers must have the Authoritative Answer bit set, see RFC 6762, section 18.4. */
934 c_or_aa
= s
->protocol
== DNS_PROTOCOL_MDNS
;
936 DNS_PACKET_HEADER(p
)->id
= id
;
937 DNS_PACKET_HEADER(p
)->flags
= htobe16(DNS_PACKET_MAKE_FLAGS(
948 r
= dns_packet_append_question(p
, q
);
951 DNS_PACKET_HEADER(p
)->qdcount
= htobe16(dns_question_size(q
));
953 r
= dns_packet_append_answer(p
, answer
, &n_answer
);
956 DNS_PACKET_HEADER(p
)->ancount
= htobe16(n_answer
);
958 r
= dns_packet_append_answer(p
, soa
, &n_soa
);
961 DNS_PACKET_HEADER(p
)->arcount
= htobe16(n_soa
);
968 static void dns_scope_verify_conflicts(DnsScope
*s
, DnsPacket
*p
) {
969 DnsResourceRecord
*rr
;
975 DNS_QUESTION_FOREACH(key
, p
->question
)
976 dns_zone_verify_conflicts(&s
->zone
, key
);
978 DNS_ANSWER_FOREACH(rr
, p
->answer
)
979 dns_zone_verify_conflicts(&s
->zone
, rr
->key
);
982 void dns_scope_process_query(DnsScope
*s
, DnsStream
*stream
, DnsPacket
*p
) {
983 _cleanup_(dns_answer_unrefp
) DnsAnswer
*answer
= NULL
, *soa
= NULL
;
984 _cleanup_(dns_packet_unrefp
) DnsPacket
*reply
= NULL
;
985 DnsResourceKey
*key
= NULL
;
986 bool tentative
= false;
992 if (p
->protocol
!= DNS_PROTOCOL_LLMNR
)
995 if (p
->ipproto
== IPPROTO_UDP
) {
996 /* Don't accept UDP queries directed to anything but
997 * the LLMNR multicast addresses. See RFC 4795,
1000 if (p
->family
== AF_INET
&& !in4_addr_equal(&p
->destination
.in
, &LLMNR_MULTICAST_IPV4_ADDRESS
))
1003 if (p
->family
== AF_INET6
&& !in6_addr_equal(&p
->destination
.in6
, &LLMNR_MULTICAST_IPV6_ADDRESS
))
1007 r
= dns_packet_extract(p
);
1009 log_debug_errno(r
, "Failed to extract resource records from incoming packet: %m");
1013 if (DNS_PACKET_LLMNR_C(p
)) {
1014 /* Somebody notified us about a possible conflict */
1015 dns_scope_verify_conflicts(s
, p
);
1019 if (dns_question_size(p
->question
) != 1)
1020 return (void) log_debug("Received LLMNR query without question or multiple questions, ignoring.");
1022 key
= dns_question_first_key(p
->question
);
1024 r
= dns_zone_lookup(&s
->zone
, key
, 0, &answer
, &soa
, &tentative
);
1026 log_debug_errno(r
, "Failed to look up key: %m");
1033 dns_answer_order_by_scope(answer
, in_addr_is_link_local(p
->family
, &p
->sender
) > 0);
1035 r
= dns_scope_make_reply_packet(s
, DNS_PACKET_ID(p
), DNS_RCODE_SUCCESS
, p
->question
, answer
, soa
, tentative
, &reply
);
1037 log_debug_errno(r
, "Failed to build reply packet: %m");
1042 r
= dns_stream_write_packet(stream
, reply
);
1044 log_debug_errno(r
, "Failed to enqueue reply packet: %m");
1048 /* Let's take an extra reference on this stream, so that it stays around after returning. The reference
1049 * will be dangling until the stream is disconnected, and the default completion handler of the stream
1050 * will then unref the stream and destroy it */
1051 if (DNS_STREAM_QUEUED(stream
))
1052 dns_stream_ref(stream
);
1056 if (!ratelimit_below(&s
->ratelimit
))
1059 if (p
->family
== AF_INET
)
1060 fd
= manager_llmnr_ipv4_udp_fd(s
->manager
);
1061 else if (p
->family
== AF_INET6
)
1062 fd
= manager_llmnr_ipv6_udp_fd(s
->manager
);
1064 log_debug("Unknown protocol");
1068 log_debug_errno(fd
, "Failed to get reply socket: %m");
1072 /* Note that we always immediately reply to all LLMNR
1073 * requests, and do not wait any time, since we
1074 * verified uniqueness for all records. Also see RFC
1075 * 4795, Section 2.7 */
1077 r
= manager_send(s
->manager
, fd
, p
->ifindex
, p
->family
, &p
->sender
, p
->sender_port
, NULL
, reply
);
1079 log_debug_errno(r
, "Failed to send reply packet: %m");
1085 DnsTransaction
*dns_scope_find_transaction(
1087 DnsResourceKey
*key
,
1088 uint64_t query_flags
) {
1090 DnsTransaction
*first
;
1095 /* Iterate through the list of transactions with a matching key */
1096 first
= hashmap_get(scope
->transactions_by_key
, key
);
1097 LIST_FOREACH(transactions_by_key
, t
, first
) {
1099 /* These four flags must match exactly: we cannot use a validated response for a
1100 * non-validating client, and we cannot use a non-validated response for a validating
1101 * client. Similar, if the sources don't match things aren't usable either. */
1102 if (((query_flags
^ t
->query_flags
) &
1103 (SD_RESOLVED_NO_VALIDATE
|
1104 SD_RESOLVED_NO_ZONE
|
1105 SD_RESOLVED_NO_TRUST_ANCHOR
|
1106 SD_RESOLVED_NO_NETWORK
)) != 0)
1109 /* We can reuse a primary query if a regular one is requested, but not vice versa */
1110 if ((query_flags
& SD_RESOLVED_REQUIRE_PRIMARY
) &&
1111 !(t
->query_flags
& SD_RESOLVED_REQUIRE_PRIMARY
))
1114 /* Don't reuse a transaction that allowed caching when we got told not to use it */
1115 if ((query_flags
& SD_RESOLVED_NO_CACHE
) &&
1116 !(t
->query_flags
& SD_RESOLVED_NO_CACHE
))
1119 /* If we are asked to clamp ttls an the existing transaction doesn't do it, we can't
1121 if ((query_flags
& SD_RESOLVED_CLAMP_TTL
) &&
1122 !(t
->query_flags
& SD_RESOLVED_CLAMP_TTL
))
1131 static int dns_scope_make_conflict_packet(
1133 DnsResourceRecord
*rr
,
1136 _cleanup_(dns_packet_unrefp
) DnsPacket
*p
= NULL
;
1143 r
= dns_packet_new(&p
, s
->protocol
, 0, DNS_PACKET_SIZE_MAX
);
1147 DNS_PACKET_HEADER(p
)->flags
= htobe16(DNS_PACKET_MAKE_FLAGS(
1158 /* For mDNS, the transaction ID should always be 0 */
1159 if (s
->protocol
!= DNS_PROTOCOL_MDNS
)
1160 random_bytes(&DNS_PACKET_HEADER(p
)->id
, sizeof(uint16_t));
1162 DNS_PACKET_HEADER(p
)->qdcount
= htobe16(1);
1163 DNS_PACKET_HEADER(p
)->arcount
= htobe16(1);
1165 r
= dns_packet_append_key(p
, rr
->key
, 0, NULL
);
1169 r
= dns_packet_append_rr(p
, rr
, 0, NULL
, NULL
);
1178 static int on_conflict_dispatch(sd_event_source
*es
, usec_t usec
, void *userdata
) {
1179 DnsScope
*scope
= ASSERT_PTR(userdata
);
1184 scope
->conflict_event_source
= sd_event_source_disable_unref(scope
->conflict_event_source
);
1187 _cleanup_(dns_resource_key_unrefp
) DnsResourceKey
*key
= NULL
;
1188 _cleanup_(dns_resource_record_unrefp
) DnsResourceRecord
*rr
= NULL
;
1189 _cleanup_(dns_packet_unrefp
) DnsPacket
*p
= NULL
;
1191 key
= ordered_hashmap_first_key(scope
->conflict_queue
);
1195 rr
= ordered_hashmap_remove(scope
->conflict_queue
, key
);
1198 r
= dns_scope_make_conflict_packet(scope
, rr
, &p
);
1200 log_error_errno(r
, "Failed to make conflict packet: %m");
1204 r
= dns_scope_emit_udp(scope
, -1, AF_UNSPEC
, p
);
1206 log_debug_errno(r
, "Failed to send conflict packet: %m");
1212 int dns_scope_notify_conflict(DnsScope
*scope
, DnsResourceRecord
*rr
) {
1218 /* We don't send these queries immediately. Instead, we queue
1219 * them, and send them after some jitter delay. */
1220 r
= ordered_hashmap_ensure_allocated(&scope
->conflict_queue
, &dns_resource_key_hash_ops
);
1226 /* We only place one RR per key in the conflict
1227 * messages, not all of them. That should be enough to
1228 * indicate where there might be a conflict */
1229 r
= ordered_hashmap_put(scope
->conflict_queue
, rr
->key
, rr
);
1230 if (IN_SET(r
, 0, -EEXIST
))
1233 return log_debug_errno(r
, "Failed to queue conflicting RR: %m");
1235 dns_resource_key_ref(rr
->key
);
1236 dns_resource_record_ref(rr
);
1238 if (scope
->conflict_event_source
)
1241 r
= sd_event_add_time_relative(
1242 scope
->manager
->event
,
1243 &scope
->conflict_event_source
,
1245 random_u64_range(LLMNR_JITTER_INTERVAL_USEC
),
1247 on_conflict_dispatch
, scope
);
1249 return log_debug_errno(r
, "Failed to add conflict dispatch event: %m");
1251 (void) sd_event_source_set_description(scope
->conflict_event_source
, "scope-conflict");
1256 void dns_scope_check_conflicts(DnsScope
*scope
, DnsPacket
*p
) {
1257 DnsResourceRecord
*rr
;
1263 if (!IN_SET(p
->protocol
, DNS_PROTOCOL_LLMNR
, DNS_PROTOCOL_MDNS
))
1266 if (DNS_PACKET_RRCOUNT(p
) <= 0)
1269 if (p
->protocol
== DNS_PROTOCOL_LLMNR
) {
1270 if (DNS_PACKET_LLMNR_C(p
) != 0)
1273 if (DNS_PACKET_LLMNR_T(p
) != 0)
1277 if (manager_packet_from_local_address(scope
->manager
, p
))
1280 r
= dns_packet_extract(p
);
1282 log_debug_errno(r
, "Failed to extract packet: %m");
1286 log_debug("Checking for conflicts...");
1288 DNS_ANSWER_FOREACH(rr
, p
->answer
) {
1289 /* No conflict if it is DNS-SD RR used for service enumeration. */
1290 if (dns_resource_key_is_dnssd_ptr(rr
->key
))
1293 /* Check for conflicts against the local zone. If we
1294 * found one, we won't check any further */
1295 r
= dns_zone_check_conflicts(&scope
->zone
, rr
);
1299 /* Check for conflicts against the local cache. If so,
1300 * send out an advisory query, to inform everybody */
1301 r
= dns_cache_check_conflicts(&scope
->cache
, rr
, p
->family
, &p
->sender
);
1305 dns_scope_notify_conflict(scope
, rr
);
1309 void dns_scope_dump(DnsScope
*s
, FILE *f
) {
1315 fputs("[Scope protocol=", f
);
1316 fputs(dns_protocol_to_string(s
->protocol
), f
);
1319 fputs(" interface=", f
);
1320 fputs(s
->link
->ifname
, f
);
1323 if (s
->family
!= AF_UNSPEC
) {
1324 fputs(" family=", f
);
1325 fputs(af_to_name(s
->family
), f
);
1330 if (!dns_zone_is_empty(&s
->zone
)) {
1331 fputs("ZONE:\n", f
);
1332 dns_zone_dump(&s
->zone
, f
);
1335 if (!dns_cache_is_empty(&s
->cache
)) {
1336 fputs("CACHE:\n", f
);
1337 dns_cache_dump(&s
->cache
, f
);
1341 DnsSearchDomain
*dns_scope_get_search_domains(DnsScope
*s
) {
1344 if (s
->protocol
!= DNS_PROTOCOL_DNS
)
1348 return s
->link
->search_domains
;
1350 return s
->manager
->search_domains
;
1353 bool dns_scope_name_wants_search_domain(DnsScope
*s
, const char *name
) {
1356 if (s
->protocol
!= DNS_PROTOCOL_DNS
)
1359 return dns_name_is_single_label(name
);
1362 bool dns_scope_network_good(DnsScope
*s
) {
1363 /* Checks whether the network is in good state for lookups on this scope. For mDNS/LLMNR/Classic DNS scopes
1364 * bound to links this is easy, as they don't even exist if the link isn't in a suitable state. For the global
1365 * DNS scope we check whether there are any links that are up and have an address.
1367 * Note that Linux routing is complex and even systems that superficially have no IPv4 address might
1368 * be able to route IPv4 (and similar for IPv6), hence let's make a check here independent of address
1374 return manager_routable(s
->manager
);
1377 int dns_scope_ifindex(DnsScope
*s
) {
1381 return s
->link
->ifindex
;
1386 static int on_announcement_timeout(sd_event_source
*s
, usec_t usec
, void *userdata
) {
1387 DnsScope
*scope
= userdata
;
1391 scope
->announce_event_source
= sd_event_source_disable_unref(scope
->announce_event_source
);
1393 (void) dns_scope_announce(scope
, false);
1397 int dns_scope_announce(DnsScope
*scope
, bool goodbye
) {
1398 _cleanup_(dns_answer_unrefp
) DnsAnswer
*answer
= NULL
;
1399 _cleanup_(dns_packet_unrefp
) DnsPacket
*p
= NULL
;
1400 _cleanup_set_free_ Set
*types
= NULL
;
1409 if (scope
->protocol
!= DNS_PROTOCOL_MDNS
)
1412 /* Check if we're done with probing. */
1413 LIST_FOREACH(transactions_by_scope
, t
, scope
->transactions
)
1414 if (DNS_TRANSACTION_IS_LIVE(t
->state
))
1417 /* Check if there're services pending conflict resolution. */
1418 if (manager_next_dnssd_names(scope
->manager
))
1419 return 0; /* we reach this point only if changing hostname didn't help */
1421 /* Calculate answer's size. */
1422 HASHMAP_FOREACH(z
, scope
->zone
.by_key
) {
1423 if (z
->state
!= DNS_ZONE_ITEM_ESTABLISHED
)
1426 if (z
->rr
->key
->type
== DNS_TYPE_PTR
&&
1427 !dns_zone_contains_name(&scope
->zone
, z
->rr
->ptr
.name
)) {
1428 char key_str
[DNS_RESOURCE_KEY_STRING_MAX
];
1430 log_debug("Skip PTR RR <%s> since its counterparts seem to be withdrawn", dns_resource_key_to_string(z
->rr
->key
, key_str
, sizeof key_str
));
1431 z
->state
= DNS_ZONE_ITEM_WITHDRAWN
;
1435 /* Collect service types for _services._dns-sd._udp.local RRs in a set */
1436 if (!scope
->announced
&&
1437 dns_resource_key_is_dnssd_ptr(z
->rr
->key
)) {
1438 if (!set_contains(types
, dns_resource_key_name(z
->rr
->key
))) {
1439 r
= set_ensure_put(&types
, &dns_name_hash_ops
, dns_resource_key_name(z
->rr
->key
));
1441 return log_debug_errno(r
, "Failed to add item to set: %m");
1445 LIST_FOREACH(by_key
, i
, z
)
1449 answer
= dns_answer_new(size
+ set_size(types
));
1453 /* Second iteration, actually add RRs to the answer. */
1454 HASHMAP_FOREACH(z
, scope
->zone
.by_key
)
1455 LIST_FOREACH (by_key
, i
, z
) {
1456 DnsAnswerFlags flags
;
1458 if (i
->state
!= DNS_ZONE_ITEM_ESTABLISHED
)
1461 if (dns_resource_key_is_dnssd_ptr(i
->rr
->key
))
1462 flags
= goodbye
? DNS_ANSWER_GOODBYE
: 0;
1464 flags
= goodbye
? (DNS_ANSWER_GOODBYE
|DNS_ANSWER_CACHE_FLUSH
) : DNS_ANSWER_CACHE_FLUSH
;
1466 r
= dns_answer_add(answer
, i
->rr
, 0, flags
, NULL
);
1468 return log_debug_errno(r
, "Failed to add RR to announce: %m");
1471 /* Since all the active services are in the zone make them discoverable now. */
1472 SET_FOREACH(service_type
, types
) {
1473 _cleanup_(dns_resource_record_unrefp
) DnsResourceRecord
*rr
= NULL
;
1475 rr
= dns_resource_record_new_full(DNS_CLASS_IN
, DNS_TYPE_PTR
,
1476 "_services._dns-sd._udp.local");
1480 rr
->ptr
.name
= strdup(service_type
);
1484 rr
->ttl
= MDNS_DEFAULT_TTL
;
1486 r
= dns_zone_put(&scope
->zone
, scope
, rr
, false);
1488 log_warning_errno(r
, "Failed to add DNS-SD PTR record to MDNS zone, ignoring: %m");
1490 r
= dns_answer_add(answer
, rr
, 0, 0, NULL
);
1492 return log_debug_errno(r
, "Failed to add RR to announce: %m");
1495 if (dns_answer_isempty(answer
))
1498 r
= dns_scope_make_reply_packet(scope
, 0, DNS_RCODE_SUCCESS
, NULL
, answer
, NULL
, false, &p
);
1500 return log_debug_errno(r
, "Failed to build reply packet: %m");
1502 r
= dns_scope_emit_udp(scope
, -1, AF_UNSPEC
, p
);
1504 return log_debug_errno(r
, "Failed to send reply packet: %m");
1506 /* In section 8.3 of RFC6762: "The Multicast DNS responder MUST send at least two unsolicited
1507 * responses, one second apart." */
1508 if (!scope
->announced
) {
1509 scope
->announced
= true;
1511 r
= sd_event_add_time_relative(
1512 scope
->manager
->event
,
1513 &scope
->announce_event_source
,
1515 MDNS_ANNOUNCE_DELAY
,
1517 on_announcement_timeout
, scope
);
1519 return log_debug_errno(r
, "Failed to schedule second announcement: %m");
1521 (void) sd_event_source_set_description(scope
->announce_event_source
, "mdns-announce");
1527 int dns_scope_add_dnssd_services(DnsScope
*scope
) {
1528 DnssdService
*service
;
1533 if (hashmap_size(scope
->manager
->dnssd_services
) == 0)
1536 scope
->announced
= false;
1538 HASHMAP_FOREACH(service
, scope
->manager
->dnssd_services
) {
1539 service
->withdrawn
= false;
1541 r
= dns_zone_put(&scope
->zone
, scope
, service
->ptr_rr
, false);
1543 log_warning_errno(r
, "Failed to add PTR record to MDNS zone: %m");
1545 r
= dns_zone_put(&scope
->zone
, scope
, service
->srv_rr
, true);
1547 log_warning_errno(r
, "Failed to add SRV record to MDNS zone: %m");
1549 LIST_FOREACH(items
, txt_data
, service
->txt_data_items
) {
1550 r
= dns_zone_put(&scope
->zone
, scope
, txt_data
->rr
, true);
1552 log_warning_errno(r
, "Failed to add TXT record to MDNS zone: %m");
1559 int dns_scope_remove_dnssd_services(DnsScope
*scope
) {
1560 _cleanup_(dns_resource_key_unrefp
) DnsResourceKey
*key
= NULL
;
1561 DnssdService
*service
;
1566 key
= dns_resource_key_new(DNS_CLASS_IN
, DNS_TYPE_PTR
,
1567 "_services._dns-sd._udp.local");
1571 r
= dns_zone_remove_rrs_by_key(&scope
->zone
, key
);
1575 HASHMAP_FOREACH(service
, scope
->manager
->dnssd_services
) {
1576 dns_zone_remove_rr(&scope
->zone
, service
->ptr_rr
);
1577 dns_zone_remove_rr(&scope
->zone
, service
->srv_rr
);
1578 LIST_FOREACH(items
, txt_data
, service
->txt_data_items
)
1579 dns_zone_remove_rr(&scope
->zone
, txt_data
->rr
);
1585 static bool dns_scope_has_route_only_domains(DnsScope
*scope
) {
1586 DnsSearchDomain
*first
;
1587 bool route_only
= false;
1590 assert(scope
->protocol
== DNS_PROTOCOL_DNS
);
1592 /* Returns 'true' if this scope is suitable for queries to specific domains only. For that we check
1593 * if there are any route-only domains on this interface, as a heuristic to discern VPN-style links
1594 * from non-VPN-style links. Returns 'false' for all other cases, i.e. if the scope is intended to
1595 * take queries to arbitrary domains, i.e. has no routing domains set. */
1598 first
= scope
->link
->search_domains
;
1600 first
= scope
->manager
->search_domains
;
1602 LIST_FOREACH(domains
, domain
, first
) {
1603 /* "." means "any domain", thus the interface takes any kind of traffic. Thus, we exit early
1604 * here, as it doesn't really matter whether this link has any route-only domains or not,
1605 * "~." really trumps everything and clearly indicates that this interface shall receive all
1606 * traffic it can get. */
1607 if (dns_name_is_root(DNS_SEARCH_DOMAIN_NAME(domain
)))
1610 if (domain
->route_only
)
1617 bool dns_scope_is_default_route(DnsScope
*scope
) {
1620 /* Only use DNS scopes as default routes */
1621 if (scope
->protocol
!= DNS_PROTOCOL_DNS
)
1624 /* The global DNS scope is always suitable as default route */
1628 /* Honour whatever is explicitly configured. This is really the best approach, and trumps any
1629 * automatic logic. */
1630 if (scope
->link
->default_route
>= 0)
1631 return scope
->link
->default_route
;
1633 /* Otherwise check if we have any route-only domains, as a sensible heuristic: if so, let's not
1634 * volunteer as default route. */
1635 return !dns_scope_has_route_only_domains(scope
);