| /* SPDX-License-Identifier: LGPL-2.1-or-later */ |
| |
| #include <netinet/tcp.h> |
| |
| #include "af-list.h" |
| #include "alloc-util.h" |
| #include "dns-domain.h" |
| #include "errno-util.h" |
| #include "fd-util.h" |
| #include "hostname-util.h" |
| #include "missing_network.h" |
| #include "random-util.h" |
| #include "resolved-dnssd.h" |
| #include "resolved-dns-scope.h" |
| #include "resolved-dns-zone.h" |
| #include "resolved-llmnr.h" |
| #include "resolved-mdns.h" |
| #include "socket-util.h" |
| #include "strv.h" |
| |
| #define MULTICAST_RATELIMIT_INTERVAL_USEC (1*USEC_PER_SEC) |
| #define MULTICAST_RATELIMIT_BURST 1000 |
| |
| /* After how much time to repeat LLMNR requests, see RFC 4795 Section 7 */ |
| #define MULTICAST_RESEND_TIMEOUT_MIN_USEC (100 * USEC_PER_MSEC) |
| #define MULTICAST_RESEND_TIMEOUT_MAX_USEC (1 * USEC_PER_SEC) |
| |
| int dns_scope_new(Manager *m, DnsScope **ret, Link *l, DnsProtocol protocol, int family) { |
| DnsScope *s; |
| |
| assert(m); |
| assert(ret); |
| |
| s = new(DnsScope, 1); |
| if (!s) |
| return -ENOMEM; |
| |
| *s = (DnsScope) { |
| .manager = m, |
| .link = l, |
| .protocol = protocol, |
| .family = family, |
| .resend_timeout = MULTICAST_RESEND_TIMEOUT_MIN_USEC, |
| }; |
| |
| if (protocol == DNS_PROTOCOL_DNS) { |
| /* Copy DNSSEC mode from the link if it is set there, |
| * otherwise take the manager's DNSSEC mode. Note that |
| * we copy this only at scope creation time, and do |
| * not update it from the on, even if the setting |
| * changes. */ |
| |
| if (l) { |
| s->dnssec_mode = link_get_dnssec_mode(l); |
| s->dns_over_tls_mode = link_get_dns_over_tls_mode(l); |
| } else { |
| s->dnssec_mode = manager_get_dnssec_mode(m); |
| s->dns_over_tls_mode = manager_get_dns_over_tls_mode(m); |
| } |
| |
| } else { |
| s->dnssec_mode = DNSSEC_NO; |
| s->dns_over_tls_mode = DNS_OVER_TLS_NO; |
| } |
| |
| LIST_PREPEND(scopes, m->dns_scopes, s); |
| |
| dns_scope_llmnr_membership(s, true); |
| dns_scope_mdns_membership(s, true); |
| |
| 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)); |
| |
| /* Enforce ratelimiting for the multicast protocols */ |
| s->ratelimit = (RateLimit) { MULTICAST_RATELIMIT_INTERVAL_USEC, MULTICAST_RATELIMIT_BURST }; |
| |
| *ret = s; |
| return 0; |
| } |
| |
| static void dns_scope_abort_transactions(DnsScope *s) { |
| assert(s); |
| |
| while (s->transactions) { |
| DnsTransaction *t = s->transactions; |
| |
| /* Abort the transaction, but make sure it is not |
| * freed while we still look at it */ |
| |
| t->block_gc++; |
| if (DNS_TRANSACTION_IS_LIVE(t->state)) |
| dns_transaction_complete(t, DNS_TRANSACTION_ABORTED); |
| t->block_gc--; |
| |
| dns_transaction_free(t); |
| } |
| } |
| |
| DnsScope* dns_scope_free(DnsScope *s) { |
| if (!s) |
| return NULL; |
| |
| 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)); |
| |
| dns_scope_llmnr_membership(s, false); |
| dns_scope_mdns_membership(s, false); |
| dns_scope_abort_transactions(s); |
| |
| while (s->query_candidates) |
| dns_query_candidate_unref(s->query_candidates); |
| |
| hashmap_free(s->transactions_by_key); |
| |
| ordered_hashmap_free_with_destructor(s->conflict_queue, dns_resource_record_unref); |
| sd_event_source_disable_unref(s->conflict_event_source); |
| |
| sd_event_source_disable_unref(s->announce_event_source); |
| |
| dns_cache_flush(&s->cache); |
| dns_zone_flush(&s->zone); |
| |
| LIST_REMOVE(scopes, s->manager->dns_scopes, s); |
| return mfree(s); |
| } |
| |
| DnsServer *dns_scope_get_dns_server(DnsScope *s) { |
| assert(s); |
| |
| if (s->protocol != DNS_PROTOCOL_DNS) |
| return NULL; |
| |
| if (s->link) |
| return link_get_dns_server(s->link); |
| else |
| return manager_get_dns_server(s->manager); |
| } |
| |
| unsigned dns_scope_get_n_dns_servers(DnsScope *s) { |
| unsigned n = 0; |
| DnsServer *i; |
| |
| assert(s); |
| |
| if (s->protocol != DNS_PROTOCOL_DNS) |
| return 0; |
| |
| if (s->link) |
| i = s->link->dns_servers; |
| else |
| i = s->manager->dns_servers; |
| |
| for (; i; i = i->servers_next) |
| n++; |
| |
| return n; |
| } |
| |
| void dns_scope_next_dns_server(DnsScope *s, DnsServer *if_current) { |
| assert(s); |
| |
| if (s->protocol != DNS_PROTOCOL_DNS) |
| return; |
| |
| /* Changes to the next DNS server in the list. If 'if_current' is passed will do so only if the |
| * current DNS server still matches it. */ |
| |
| if (s->link) |
| link_next_dns_server(s->link, if_current); |
| else |
| manager_next_dns_server(s->manager, if_current); |
| } |
| |
| void dns_scope_packet_received(DnsScope *s, usec_t rtt) { |
| assert(s); |
| |
| if (rtt <= s->max_rtt) |
| return; |
| |
| s->max_rtt = rtt; |
| s->resend_timeout = MIN(MAX(MULTICAST_RESEND_TIMEOUT_MIN_USEC, s->max_rtt * 2), MULTICAST_RESEND_TIMEOUT_MAX_USEC); |
| } |
| |
| void dns_scope_packet_lost(DnsScope *s, usec_t usec) { |
| assert(s); |
| |
| if (s->resend_timeout <= usec) |
| s->resend_timeout = MIN(s->resend_timeout * 2, MULTICAST_RESEND_TIMEOUT_MAX_USEC); |
| } |
| |
| static int dns_scope_emit_one(DnsScope *s, int fd, int family, DnsPacket *p) { |
| int r; |
| |
| assert(s); |
| assert(p); |
| assert(p->protocol == s->protocol); |
| |
| if (family == AF_UNSPEC) { |
| if (s->family == AF_UNSPEC) |
| return -EAFNOSUPPORT; |
| |
| family = s->family; |
| } |
| |
| switch (s->protocol) { |
| |
| case DNS_PROTOCOL_DNS: { |
| size_t mtu, udp_size, min_mtu, socket_mtu = 0; |
| |
| assert(fd >= 0); |
| |
| if (DNS_PACKET_QDCOUNT(p) > 1) /* Classic DNS only allows one question per packet */ |
| return -EOPNOTSUPP; |
| |
| if (p->size > DNS_PACKET_UNICAST_SIZE_MAX) |
| return -EMSGSIZE; |
| |
| /* Determine the local most accurate MTU */ |
| if (s->link) |
| mtu = s->link->mtu; |
| else |
| mtu = manager_find_mtu(s->manager); |
| |
| /* Acquire the socket's PMDU MTU */ |
| r = socket_get_mtu(fd, family, &socket_mtu); |
| if (r < 0 && !ERRNO_IS_DISCONNECT(r)) /* Will return ENOTCONN if no information is available yet */ |
| return log_debug_errno(r, "Failed to read socket MTU: %m"); |
| |
| /* Determine the appropriate UDP header size */ |
| udp_size = udp_header_size(family); |
| min_mtu = udp_size + DNS_PACKET_HEADER_SIZE; |
| |
| log_debug("Emitting UDP, link MTU is %zu, socket MTU is %zu, minimal MTU is %zu", |
| mtu, socket_mtu, min_mtu); |
| |
| /* Clamp by the kernel's idea of the (path) MTU */ |
| if (socket_mtu != 0 && socket_mtu < mtu) |
| mtu = socket_mtu; |
| |
| /* Put a lower limit, in case all MTU data we acquired was rubbish */ |
| if (mtu < min_mtu) |
| mtu = min_mtu; |
| |
| /* Now check our packet size against the MTU we determined */ |
| if (udp_size + p->size > mtu) |
| return -EMSGSIZE; /* This means: try TCP instead */ |
| |
| r = manager_write(s->manager, fd, p); |
| if (r < 0) |
| return r; |
| |
| break; |
| } |
| |
| case DNS_PROTOCOL_LLMNR: { |
| union in_addr_union addr; |
| |
| assert(fd < 0); |
| |
| if (DNS_PACKET_QDCOUNT(p) > 1) |
| return -EOPNOTSUPP; |
| |
| if (!ratelimit_below(&s->ratelimit)) |
| return -EBUSY; |
| |
| if (family == AF_INET) { |
| addr.in = LLMNR_MULTICAST_IPV4_ADDRESS; |
| fd = manager_llmnr_ipv4_udp_fd(s->manager); |
| } else if (family == AF_INET6) { |
| addr.in6 = LLMNR_MULTICAST_IPV6_ADDRESS; |
| fd = manager_llmnr_ipv6_udp_fd(s->manager); |
| } else |
| return -EAFNOSUPPORT; |
| if (fd < 0) |
| return fd; |
| |
| r = manager_send(s->manager, fd, s->link->ifindex, family, &addr, LLMNR_PORT, NULL, p); |
| if (r < 0) |
| return r; |
| |
| break; |
| } |
| |
| case DNS_PROTOCOL_MDNS: { |
| union in_addr_union addr; |
| assert(fd < 0); |
| |
| if (!ratelimit_below(&s->ratelimit)) |
| return -EBUSY; |
| |
| if (family == AF_INET) { |
| if (in4_addr_is_null(&p->destination.in)) |
| addr.in = MDNS_MULTICAST_IPV4_ADDRESS; |
| else |
| addr = p->destination; |
| fd = manager_mdns_ipv4_fd(s->manager); |
| } else if (family == AF_INET6) { |
| if (in6_addr_is_null(&p->destination.in6)) |
| addr.in6 = MDNS_MULTICAST_IPV6_ADDRESS; |
| else |
| addr = p->destination; |
| fd = manager_mdns_ipv6_fd(s->manager); |
| } else |
| return -EAFNOSUPPORT; |
| if (fd < 0) |
| return fd; |
| |
| r = manager_send(s->manager, fd, s->link->ifindex, family, &addr, p->destination_port ?: MDNS_PORT, NULL, p); |
| if (r < 0) |
| return r; |
| |
| break; |
| } |
| |
| default: |
| return -EAFNOSUPPORT; |
| } |
| |
| return 1; |
| } |
| |
| int dns_scope_emit_udp(DnsScope *s, int fd, int af, DnsPacket *p) { |
| int r; |
| |
| assert(s); |
| assert(p); |
| assert(p->protocol == s->protocol); |
| assert((s->protocol == DNS_PROTOCOL_DNS) == (fd >= 0)); |
| |
| do { |
| /* If there are multiple linked packets, set the TC bit in all but the last of them */ |
| if (p->more) { |
| assert(p->protocol == DNS_PROTOCOL_MDNS); |
| dns_packet_set_flags(p, true, true); |
| } |
| |
| r = dns_scope_emit_one(s, fd, af, p); |
| if (r < 0) |
| return r; |
| |
| p = p->more; |
| } while (p); |
| |
| return 0; |
| } |
| |
| static int dns_scope_socket( |
| DnsScope *s, |
| int type, |
| int family, |
| const union in_addr_union *address, |
| DnsServer *server, |
| uint16_t port, |
| union sockaddr_union *ret_socket_address) { |
| |
| _cleanup_close_ int fd = -1; |
| union sockaddr_union sa; |
| socklen_t salen; |
| int r, ifindex; |
| |
| assert(s); |
| |
| if (server) { |
| assert(family == AF_UNSPEC); |
| assert(!address); |
| |
| ifindex = dns_server_ifindex(server); |
| |
| switch (server->family) { |
| case AF_INET: |
| sa = (union sockaddr_union) { |
| .in.sin_family = server->family, |
| .in.sin_port = htobe16(port), |
| .in.sin_addr = server->address.in, |
| }; |
| salen = sizeof(sa.in); |
| break; |
| case AF_INET6: |
| sa = (union sockaddr_union) { |
| .in6.sin6_family = server->family, |
| .in6.sin6_port = htobe16(port), |
| .in6.sin6_addr = server->address.in6, |
| .in6.sin6_scope_id = ifindex, |
| }; |
| salen = sizeof(sa.in6); |
| break; |
| default: |
| return -EAFNOSUPPORT; |
| } |
| } else { |
| assert(family != AF_UNSPEC); |
| assert(address); |
| |
| ifindex = s->link ? s->link->ifindex : 0; |
| |
| switch (family) { |
| case AF_INET: |
| sa = (union sockaddr_union) { |
| .in.sin_family = family, |
| .in.sin_port = htobe16(port), |
| .in.sin_addr = address->in, |
| }; |
| salen = sizeof(sa.in); |
| break; |
| case AF_INET6: |
| sa = (union sockaddr_union) { |
| .in6.sin6_family = family, |
| .in6.sin6_port = htobe16(port), |
| .in6.sin6_addr = address->in6, |
| .in6.sin6_scope_id = ifindex, |
| }; |
| salen = sizeof(sa.in6); |
| break; |
| default: |
| return -EAFNOSUPPORT; |
| } |
| } |
| |
| fd = socket(sa.sa.sa_family, type|SOCK_CLOEXEC|SOCK_NONBLOCK, 0); |
| if (fd < 0) |
| return -errno; |
| |
| if (type == SOCK_STREAM) { |
| r = setsockopt_int(fd, IPPROTO_TCP, TCP_NODELAY, true); |
| if (r < 0) |
| return r; |
| } |
| |
| if (s->link) { |
| r = socket_set_unicast_if(fd, sa.sa.sa_family, ifindex); |
| if (r < 0) |
| return r; |
| } |
| |
| if (s->protocol == DNS_PROTOCOL_LLMNR) { |
| /* RFC 4795, section 2.5 requires the TTL to be set to 1 */ |
| r = socket_set_ttl(fd, sa.sa.sa_family, 1); |
| if (r < 0) |
| return r; |
| } |
| |
| if (type == SOCK_DGRAM) { |
| /* Set IP_RECVERR or IPV6_RECVERR to get ICMP error feedback. See discussion in #10345. */ |
| r = socket_set_recverr(fd, sa.sa.sa_family, true); |
| if (r < 0) |
| return r; |
| |
| r = socket_set_recvpktinfo(fd, sa.sa.sa_family, true); |
| if (r < 0) |
| return r; |
| |
| /* Turn of path MTU discovery for security reasons */ |
| r = socket_disable_pmtud(fd, sa.sa.sa_family); |
| if (r < 0) |
| log_debug_errno(r, "Failed to disable UDP PMTUD, ignoring: %m"); |
| |
| /* Learn about fragmentation taking place */ |
| r = socket_set_recvfragsize(fd, sa.sa.sa_family, true); |
| if (r < 0) |
| log_debug_errno(r, "Failed to enable fragment size reception, ignoring: %m"); |
| } |
| |
| if (ret_socket_address) |
| *ret_socket_address = sa; |
| else { |
| bool bound = false; |
| |
| /* Let's temporarily bind the socket to the specified ifindex. The kernel currently takes |
| * only the SO_BINDTODEVICE/SO_BINDTOINDEX ifindex into account when making routing decisions |
| * in connect() — and not IP_UNICAST_IF. We don't really want any of the other semantics of |
| * SO_BINDTODEVICE/SO_BINDTOINDEX, hence we immediately unbind the socket after the fact |
| * again. |
| * |
| * As a special exception we don't do this if we notice that the specified IP address is on |
| * the local host. SO_BINDTODEVICE in combination with destination addresses on the local |
| * host result in EHOSTUNREACH, since Linux won't send the packets out of the specified |
| * interface, but delivers them directly to the local socket. */ |
| if (s->link && |
| !manager_find_link_address(s->manager, sa.sa.sa_family, sockaddr_in_addr(&sa.sa))) { |
| r = socket_bind_to_ifindex(fd, ifindex); |
| if (r < 0) |
| return r; |
| |
| bound = true; |
| } |
| |
| r = connect(fd, &sa.sa, salen); |
| if (r < 0 && errno != EINPROGRESS) |
| return -errno; |
| |
| if (bound) { |
| r = socket_bind_to_ifindex(fd, 0); |
| if (r < 0) |
| return r; |
| } |
| } |
| |
| return TAKE_FD(fd); |
| } |
| |
| int dns_scope_socket_udp(DnsScope *s, DnsServer *server) { |
| return dns_scope_socket(s, SOCK_DGRAM, AF_UNSPEC, NULL, server, dns_server_port(server), NULL); |
| } |
| |
| 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) { |
| /* If ret_socket_address is not NULL, the caller is responsible |
| * for calling connect() or sendmsg(). This is required by TCP |
| * Fast Open, to be able to send the initial SYN packet along |
| * with the first data packet. */ |
| return dns_scope_socket(s, SOCK_STREAM, family, address, server, port, ret_socket_address); |
| } |
| |
| static DnsScopeMatch match_link_local_reverse_lookups(const char *domain) { |
| assert(domain); |
| |
| if (dns_name_endswith(domain, "254.169.in-addr.arpa") > 0) |
| return DNS_SCOPE_YES_BASE + 4; /* 4 labels match */ |
| |
| if (dns_name_endswith(domain, "8.e.f.ip6.arpa") > 0 || |
| dns_name_endswith(domain, "9.e.f.ip6.arpa") > 0 || |
| dns_name_endswith(domain, "a.e.f.ip6.arpa") > 0 || |
| dns_name_endswith(domain, "b.e.f.ip6.arpa") > 0) |
| return DNS_SCOPE_YES_BASE + 5; /* 5 labels match */ |
| |
| return _DNS_SCOPE_MATCH_INVALID; |
| } |
| |
| static DnsScopeMatch match_subnet_reverse_lookups( |
| DnsScope *s, |
| const char *domain, |
| bool exclude_own) { |
| |
| union in_addr_union ia; |
| LinkAddress *a; |
| int f, r; |
| |
| assert(s); |
| assert(domain); |
| |
| /* Checks whether the specified domain is a reverse address domain (i.e. in the .in-addr.arpa or |
| * .ip6.arpa area), and if so, whether the address matches any of the local subnets of the link the |
| * scope is associated with. If so, our scope should consider itself relevant for any lookup in the |
| * domain, since it apparently refers to hosts on this link's subnet. |
| * |
| * If 'exclude_own' is true this will return DNS_SCOPE_NO for any IP addresses assigned locally. This |
| * is useful for LLMNR/mDNS as we never want to look up our own hostname on LLMNR/mDNS but always use |
| * the locally synthesized one. */ |
| |
| if (!s->link) |
| return _DNS_SCOPE_MATCH_INVALID; /* No link, hence no local addresses to check */ |
| |
| r = dns_name_address(domain, &f, &ia); |
| if (r < 0) |
| log_debug_errno(r, "Failed to determine whether '%s' is an address domain: %m", domain); |
| if (r <= 0) |
| return _DNS_SCOPE_MATCH_INVALID; |
| |
| if (s->family != AF_UNSPEC && f != s->family) |
| return _DNS_SCOPE_MATCH_INVALID; /* Don't look for IPv4 addresses on LLMNR/mDNS over IPv6 and vice versa */ |
| |
| LIST_FOREACH(addresses, a, s->link->addresses) { |
| |
| if (a->family != f) |
| continue; |
| |
| /* Equals our own address? nah, let's not use this scope. The local synthesizer will pick it up for us. */ |
| if (exclude_own && |
| in_addr_equal(f, &a->in_addr, &ia) > 0) |
| return DNS_SCOPE_NO; |
| |
| if (a->prefixlen == UCHAR_MAX) /* don't know subnet mask */ |
| continue; |
| |
| /* Check if the address is in the local subnet */ |
| r = in_addr_prefix_covers(f, &a->in_addr, a->prefixlen, &ia); |
| if (r < 0) |
| log_debug_errno(r, "Failed to determine whether link address covers lookup address '%s': %m", domain); |
| if (r > 0) |
| /* Note that we only claim zero labels match. This is so that this is at the same |
| * priority a DNS scope with "." as routing domain is. */ |
| return DNS_SCOPE_YES_BASE + 0; |
| } |
| |
| return _DNS_SCOPE_MATCH_INVALID; |
| } |
| |
| DnsScopeMatch dns_scope_good_domain( |
| DnsScope *s, |
| DnsQuery *q) { |
| |
| DnsQuestion *question; |
| DnsSearchDomain *d; |
| const char *domain; |
| uint64_t flags; |
| int ifindex; |
| |
| /* This returns the following return values: |
| * |
| * DNS_SCOPE_NO → This scope is not suitable for lookups of this domain, at all |
| * DNS_SCOPE_MAYBE → This scope is suitable, but only if nothing else wants it |
| * DNS_SCOPE_YES_BASE+n → This scope is suitable, and 'n' suffix labels match |
| * |
| * (The idea is that the caller will only use the scopes with the longest 'n' returned. If no scopes return |
| * DNS_SCOPE_YES_BASE+n, then it should use those which returned DNS_SCOPE_MAYBE. It should never use those |
| * which returned DNS_SCOPE_NO.) |
| */ |
| |
| assert(s); |
| assert(q); |
| |
| question = dns_query_question_for_protocol(q, s->protocol); |
| if (!question) |
| return DNS_SCOPE_NO; |
| |
| domain = dns_question_first_name(question); |
| if (!domain) |
| return DNS_SCOPE_NO; |
| |
| ifindex = q->ifindex; |
| flags = q->flags; |
| |
| /* Checks if the specified domain is something to look up on this scope. Note that this accepts |
| * non-qualified hostnames, i.e. those without any search path suffixed. */ |
| |
| if (ifindex != 0 && (!s->link || s->link->ifindex != ifindex)) |
| return DNS_SCOPE_NO; |
| |
| if ((SD_RESOLVED_FLAGS_MAKE(s->protocol, s->family, false, false) & flags) == 0) |
| return DNS_SCOPE_NO; |
| |
| /* Never resolve any loopback hostname or IP address via DNS, LLMNR or mDNS. Instead, always rely on |
| * synthesized RRs for these. */ |
| if (is_localhost(domain) || |
| dns_name_endswith(domain, "127.in-addr.arpa") > 0 || |
| 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) |
| return DNS_SCOPE_NO; |
| |
| /* Never respond to some of the domains listed in RFC6303 */ |
| if (dns_name_endswith(domain, "0.in-addr.arpa") > 0 || |
| dns_name_equal(domain, "255.255.255.255.in-addr.arpa") > 0 || |
| dns_name_equal(domain, "0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.ip6.arpa") > 0) |
| return DNS_SCOPE_NO; |
| |
| /* Never respond to some of the domains listed in RFC6761 */ |
| if (dns_name_endswith(domain, "invalid") > 0) |
| return DNS_SCOPE_NO; |
| |
| /* Never go to network for the _gateway or _outbound domain — they're something special, synthesized locally. */ |
| if (is_gateway_hostname(domain) || is_outbound_hostname(domain)) |
| return DNS_SCOPE_NO; |
| |
| switch (s->protocol) { |
| |
| case DNS_PROTOCOL_DNS: { |
| bool has_search_domains = false; |
| DnsScopeMatch m; |
| int n_best = -1; |
| |
| if (dns_name_is_empty(domain)) { |
| DnsResourceKey *t; |
| bool found = false; |
| |
| /* Refuse empty name if only A and/or AAAA records are requested. */ |
| |
| DNS_QUESTION_FOREACH(t, question) |
| if (!IN_SET(t->type, DNS_TYPE_A, DNS_TYPE_AAAA)) { |
| found = true; |
| break; |
| } |
| |
| if (!found) |
| return DNS_SCOPE_NO; |
| } |
| |
| /* Never route things to scopes that lack DNS servers */ |
| if (!dns_scope_get_dns_server(s)) |
| return DNS_SCOPE_NO; |
| |
| /* Always honour search domains for routing queries, except if this scope lacks DNS servers. Note that |
| * we return DNS_SCOPE_YES here, rather than just DNS_SCOPE_MAYBE, which means other wildcard scopes |
| * won't be considered anymore. */ |
| LIST_FOREACH(domains, d, dns_scope_get_search_domains(s)) { |
| |
| if (!d->route_only && !dns_name_is_root(d->name)) |
| has_search_domains = true; |
| |
| if (dns_name_endswith(domain, d->name) > 0) { |
| int c; |
| |
| c = dns_name_count_labels(d->name); |
| if (c < 0) |
| continue; |
| |
| if (c > n_best) |
| n_best = c; |
| } |
| } |
| |
| /* If there's a true search domain defined for this scope, and the query is single-label, |
| * then let's resolve things here, prefereably. Note that LLMNR considers itself |
| * authoritative for single-label names too, at the same preference, see below. */ |
| if (has_search_domains && dns_name_is_single_label(domain)) |
| return DNS_SCOPE_YES_BASE + 1; |
| |
| /* Let's return the number of labels in the best matching result */ |
| if (n_best >= 0) { |
| assert(n_best <= DNS_SCOPE_YES_END - DNS_SCOPE_YES_BASE); |
| return DNS_SCOPE_YES_BASE + n_best; |
| } |
| |
| /* Exclude link-local IP ranges */ |
| if (match_link_local_reverse_lookups(domain) >= DNS_SCOPE_YES_BASE || |
| /* If networks use .local in their private setups, they are supposed to also add .local |
| * to their search domains, which we already checked above. Otherwise, we consider .local |
| * specific to mDNS and won't send such queries ordinary DNS servers. */ |
| dns_name_endswith(domain, "local") > 0) |
| return DNS_SCOPE_NO; |
| |
| /* If the IP address to look up matches the local subnet, then implicitly synthesizes |
| * DNS_SCOPE_YES_BASE + 0 on this interface, i.e. preferably resolve IP addresses via the DNS |
| * server belonging to this interface. */ |
| m = match_subnet_reverse_lookups(s, domain, false); |
| if (m >= 0) |
| return m; |
| |
| /* If there was no match at all, then see if this scope is suitable as default route. */ |
| if (!dns_scope_is_default_route(s)) |
| return DNS_SCOPE_NO; |
| |
| return DNS_SCOPE_MAYBE; |
| } |
| |
| case DNS_PROTOCOL_MDNS: { |
| DnsScopeMatch m; |
| |
| m = match_link_local_reverse_lookups(domain); |
| if (m >= 0) |
| return m; |
| |
| m = match_subnet_reverse_lookups(s, domain, true); |
| if (m >= 0) |
| return m; |
| |
| if ((s->family == AF_INET && dns_name_endswith(domain, "in-addr.arpa") > 0) || |
| (s->family == AF_INET6 && dns_name_endswith(domain, "ip6.arpa") > 0)) |
| return DNS_SCOPE_MAYBE; |
| |
| if ((dns_name_endswith(domain, "local") > 0 && /* only resolve names ending in .local via mDNS */ |
| dns_name_equal(domain, "local") == 0 && /* but not the single-label "local" name itself */ |
| manager_is_own_hostname(s->manager, domain) <= 0)) /* never resolve the local hostname via mDNS */ |
| return DNS_SCOPE_YES_BASE + 1; /* Return +1, as the top-level .local domain matches, i.e. one label */ |
| |
| return DNS_SCOPE_NO; |
| } |
| |
| case DNS_PROTOCOL_LLMNR: { |
| DnsScopeMatch m; |
| |
| m = match_link_local_reverse_lookups(domain); |
| if (m >= 0) |
| return m; |
| |
| m = match_subnet_reverse_lookups(s, domain, true); |
| if (m >= 0) |
| return m; |
| |
| if ((s->family == AF_INET && dns_name_endswith(domain, "in-addr.arpa") > 0) || |
| (s->family == AF_INET6 && dns_name_endswith(domain, "ip6.arpa") > 0)) |
| return DNS_SCOPE_MAYBE; |
| |
| if ((dns_name_is_single_label(domain) && /* only resolve single label names via LLMNR */ |
| !is_gateway_hostname(domain) && /* don't resolve "_gateway" with LLMNR, let local synthesizing logic handle that */ |
| !is_outbound_hostname(domain) && /* similar for "_outbound" */ |
| dns_name_equal(domain, "local") == 0 && /* don't resolve "local" with LLMNR, it's the top-level domain of mDNS after all, see above */ |
| manager_is_own_hostname(s->manager, domain) <= 0)) /* never resolve the local hostname via LLMNR */ |
| return DNS_SCOPE_YES_BASE + 1; /* Return +1, as we consider ourselves authoritative |
| * for single-label names, i.e. one label. This is |
| * particularly relevant as it means a "." route on some |
| * other scope won't pull all traffic away from |
| * us. (If people actually want to pull traffic away |
| * from us they should turn off LLMNR on the |
| * link). Note that unicast DNS scopes with search |
| * domains also consider themselves authoritative for |
| * single-label domains, at the same preference (see |
| * above). */ |
| |
| return DNS_SCOPE_NO; |
| } |
| |
| default: |
| assert_not_reached("Unknown scope protocol"); |
| } |
| } |
| |
| bool dns_scope_good_key(DnsScope *s, const DnsResourceKey *key) { |
| int key_family; |
| |
| assert(s); |
| assert(key); |
| |
| /* Check if it makes sense to resolve the specified key on this scope. Note that this call assumes a |
| * fully qualified name, i.e. the search suffixes already appended. */ |
| |
| if (!IN_SET(key->class, DNS_CLASS_IN, DNS_CLASS_ANY)) |
| return false; |
| |
| if (s->protocol == DNS_PROTOCOL_DNS) { |
| |
| /* On classic DNS, looking up non-address RRs is always fine. (Specifically, we want to |
| * permit looking up DNSKEY and DS records on the root and top-level domains.) */ |
| if (!dns_resource_key_is_address(key)) |
| return true; |
| |
| /* Unless explicitly overridden, we refuse to look up A and AAAA RRs on the root and |
| * single-label domains, under the assumption that those should be resolved via LLMNR or |
| * search path only, and should not be leaked onto the internet. */ |
| const char* name = dns_resource_key_name(key); |
| |
| if (!s->manager->resolve_unicast_single_label && |
| dns_name_is_single_label(name)) |
| return false; |
| |
| return !dns_name_is_root(name); |
| } |
| |
| /* Never route DNSSEC RR queries to LLMNR/mDNS scopes */ |
| if (dns_type_is_dnssec(key->type)) |
| return false; |
| |
| /* On mDNS and LLMNR, send A and AAAA queries only on the respective scopes */ |
| |
| key_family = dns_type_to_af(key->type); |
| if (key_family < 0) |
| return true; |
| |
| return key_family == s->family; |
| } |
| |
| static int dns_scope_multicast_membership(DnsScope *s, bool b, struct in_addr in, struct in6_addr in6) { |
| int fd; |
| |
| assert(s); |
| assert(s->link); |
| |
| if (s->family == AF_INET) { |
| struct ip_mreqn mreqn = { |
| .imr_multiaddr = in, |
| .imr_ifindex = s->link->ifindex, |
| }; |
| |
| if (s->protocol == DNS_PROTOCOL_LLMNR) |
| fd = manager_llmnr_ipv4_udp_fd(s->manager); |
| else |
| fd = manager_mdns_ipv4_fd(s->manager); |
| |
| 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; |
| |
| } else if (s->family == AF_INET6) { |
| struct ipv6_mreq mreq = { |
| .ipv6mr_multiaddr = in6, |
| .ipv6mr_interface = s->link->ifindex, |
| }; |
| |
| if (s->protocol == DNS_PROTOCOL_LLMNR) |
| fd = manager_llmnr_ipv6_udp_fd(s->manager); |
| else |
| fd = manager_mdns_ipv6_fd(s->manager); |
| |
| 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 |
| return -EAFNOSUPPORT; |
| |
| return 0; |
| } |
| |
| int dns_scope_llmnr_membership(DnsScope *s, bool b) { |
| assert(s); |
| |
| if (s->protocol != DNS_PROTOCOL_LLMNR) |
| return 0; |
| |
| return dns_scope_multicast_membership(s, b, LLMNR_MULTICAST_IPV4_ADDRESS, LLMNR_MULTICAST_IPV6_ADDRESS); |
| } |
| |
| int dns_scope_mdns_membership(DnsScope *s, bool b) { |
| assert(s); |
| |
| if (s->protocol != DNS_PROTOCOL_MDNS) |
| return 0; |
| |
| return dns_scope_multicast_membership(s, b, MDNS_MULTICAST_IPV4_ADDRESS, MDNS_MULTICAST_IPV6_ADDRESS); |
| } |
| |
| int dns_scope_make_reply_packet( |
| DnsScope *s, |
| uint16_t id, |
| int rcode, |
| DnsQuestion *q, |
| DnsAnswer *answer, |
| DnsAnswer *soa, |
| bool tentative, |
| DnsPacket **ret) { |
| |
| _cleanup_(dns_packet_unrefp) DnsPacket *p = NULL; |
| unsigned n_answer = 0, n_soa = 0; |
| int r; |
| bool c_or_aa; |
| |
| assert(s); |
| assert(ret); |
| |
| if (dns_question_isempty(q) && |
| dns_answer_isempty(answer) && |
| dns_answer_isempty(soa)) |
| return -EINVAL; |
| |
| r = dns_packet_new(&p, s->protocol, 0, DNS_PACKET_SIZE_MAX); |
| if (r < 0) |
| return r; |
| |
| /* mDNS answers must have the Authoritative Answer bit set, see RFC 6762, section 18.4. */ |
| c_or_aa = s->protocol == DNS_PROTOCOL_MDNS; |
| |
| DNS_PACKET_HEADER(p)->id = id; |
| DNS_PACKET_HEADER(p)->flags = htobe16(DNS_PACKET_MAKE_FLAGS( |
| 1 /* qr */, |
| 0 /* opcode */, |
| c_or_aa, |
| 0 /* tc */, |
| tentative, |
| 0 /* (ra) */, |
| 0 /* (ad) */, |
| 0 /* (cd) */, |
| rcode)); |
| |
| r = dns_packet_append_question(p, q); |
| if (r < 0) |
| return r; |
| DNS_PACKET_HEADER(p)->qdcount = htobe16(dns_question_size(q)); |
| |
| r = dns_packet_append_answer(p, answer, &n_answer); |
| if (r < 0) |
| return r; |
| DNS_PACKET_HEADER(p)->ancount = htobe16(n_answer); |
| |
| r = dns_packet_append_answer(p, soa, &n_soa); |
| if (r < 0) |
| return r; |
| DNS_PACKET_HEADER(p)->arcount = htobe16(n_soa); |
| |
| *ret = TAKE_PTR(p); |
| |
| return 0; |
| } |
| |
| static void dns_scope_verify_conflicts(DnsScope *s, DnsPacket *p) { |
| DnsResourceRecord *rr; |
| DnsResourceKey *key; |
| |
| assert(s); |
| assert(p); |
| |
| DNS_QUESTION_FOREACH(key, p->question) |
| dns_zone_verify_conflicts(&s->zone, key); |
| |
| DNS_ANSWER_FOREACH(rr, p->answer) |
| dns_zone_verify_conflicts(&s->zone, rr->key); |
| } |
| |
| void dns_scope_process_query(DnsScope *s, DnsStream *stream, DnsPacket *p) { |
| _cleanup_(dns_answer_unrefp) DnsAnswer *answer = NULL, *soa = NULL; |
| _cleanup_(dns_packet_unrefp) DnsPacket *reply = NULL; |
| DnsResourceKey *key = NULL; |
| bool tentative = false; |
| int r; |
| |
| assert(s); |
| assert(p); |
| |
| if (p->protocol != DNS_PROTOCOL_LLMNR) |
| return; |
| |
| if (p->ipproto == IPPROTO_UDP) { |
| /* Don't accept UDP queries directed to anything but |
| * the LLMNR multicast addresses. See RFC 4795, |
| * section 2.5. */ |
| |
| if (p->family == AF_INET && !in4_addr_equal(&p->destination.in, &LLMNR_MULTICAST_IPV4_ADDRESS)) |
| return; |
| |
| if (p->family == AF_INET6 && !in6_addr_equal(&p->destination.in6, &LLMNR_MULTICAST_IPV6_ADDRESS)) |
| return; |
| } |
| |
| r = dns_packet_extract(p); |
| if (r < 0) { |
| log_debug_errno(r, "Failed to extract resource records from incoming packet: %m"); |
| return; |
| } |
| |
| if (DNS_PACKET_LLMNR_C(p)) { |
| /* Somebody notified us about a possible conflict */ |
| dns_scope_verify_conflicts(s, p); |
| return; |
| } |
| |
| assert(dns_question_size(p->question) == 1); |
| key = dns_question_first_key(p->question); |
| |
| r = dns_zone_lookup(&s->zone, key, 0, &answer, &soa, &tentative); |
| if (r < 0) { |
| log_debug_errno(r, "Failed to look up key: %m"); |
| return; |
| } |
| if (r == 0) |
| return; |
| |
| if (answer) |
| dns_answer_order_by_scope(answer, in_addr_is_link_local(p->family, &p->sender) > 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_errno(r, "Failed to build reply packet: %m"); |
| return; |
| } |
| |
| if (stream) { |
| r = dns_stream_write_packet(stream, reply); |
| if (r < 0) { |
| log_debug_errno(r, "Failed to enqueue reply packet: %m"); |
| return; |
| } |
| |
| /* Let's take an extra reference on this stream, so that it stays around after returning. The reference |
| * will be dangling until the stream is disconnected, and the default completion handler of the stream |
| * will then unref the stream and destroy it */ |
| if (DNS_STREAM_QUEUED(stream)) |
| dns_stream_ref(stream); |
| } else { |
| int fd; |
| |
| if (!ratelimit_below(&s->ratelimit)) |
| return; |
| |
| if (p->family == AF_INET) |
| fd = manager_llmnr_ipv4_udp_fd(s->manager); |
| else if (p->family == AF_INET6) |
| fd = manager_llmnr_ipv6_udp_fd(s->manager); |
| else { |
| log_debug("Unknown protocol"); |
| return; |
| } |
| if (fd < 0) { |
| 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, NULL, reply); |
| if (r < 0) { |
| log_debug_errno(r, "Failed to send reply packet: %m"); |
| return; |
| } |
| } |
| } |
| |
| DnsTransaction *dns_scope_find_transaction( |
| DnsScope *scope, |
| DnsResourceKey *key, |
| uint64_t query_flags) { |
| |
| DnsTransaction *first, *t; |
| |
| assert(scope); |
| assert(key); |
| |
| /* Iterate through the list of transactions with a matching key */ |
| first = hashmap_get(scope->transactions_by_key, key); |
| LIST_FOREACH(transactions_by_key, t, first) { |
| |
| /* These four flags must match exactly: we cannot use a validated response for a |
| * non-validating client, and we cannot use a non-validated response for a validating |
| * client. Similar, if the sources don't match things aren't usable either. */ |
| if (((query_flags ^ t->query_flags) & |
| (SD_RESOLVED_NO_VALIDATE| |
| SD_RESOLVED_NO_ZONE| |
| SD_RESOLVED_NO_TRUST_ANCHOR| |
| SD_RESOLVED_NO_NETWORK)) != 0) |
| continue; |
| |
| /* We can reuse a primary query if a regular one is requested, but not vice versa */ |
| if ((query_flags & SD_RESOLVED_REQUIRE_PRIMARY) && |
| !(t->query_flags & SD_RESOLVED_REQUIRE_PRIMARY)) |
| continue; |
| |
| /* Don't reuse a transaction that allowed caching when we got told not to use it */ |
| if ((query_flags & SD_RESOLVED_NO_CACHE) && |
| !(t->query_flags & SD_RESOLVED_NO_CACHE)) |
| continue; |
| |
| /* If we are asked to clamp ttls an the existing transaction doesn't do it, we can't |
| * reuse */ |
| if ((query_flags & SD_RESOLVED_CLAMP_TTL) && |
| !(t->query_flags & SD_RESOLVED_CLAMP_TTL)) |
| continue; |
| |
| 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, DNS_PACKET_SIZE_MAX); |
| 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)); |
| |
| /* For mDNS, the transaction ID should always be 0 */ |
| if (s->protocol != DNS_PROTOCOL_MDNS) |
| 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, 0, NULL); |
| if (r < 0) |
| return r; |
| |
| r = dns_packet_append_rr(p, rr, 0, NULL, NULL); |
| if (r < 0) |
| return r; |
| |
| *ret = TAKE_PTR(p); |
| |
| 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_disable_unref(scope->conflict_event_source); |
| |
| for (;;) { |
| _cleanup_(dns_resource_key_unrefp) DnsResourceKey *key = NULL; |
| _cleanup_(dns_resource_record_unrefp) DnsResourceRecord *rr = NULL; |
| _cleanup_(dns_packet_unrefp) DnsPacket *p = NULL; |
| |
| key = ordered_hashmap_first_key(scope->conflict_queue); |
| if (!key) |
| break; |
| |
| rr = ordered_hashmap_remove(scope->conflict_queue, key); |
| assert(rr); |
| |
| 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_udp(scope, -1, AF_UNSPEC, 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 (IN_SET(r, 0, -EEXIST)) |
| return 0; |
| if (r < 0) |
| return log_debug_errno(r, "Failed to queue conflicting RR: %m"); |
| |
| dns_resource_key_ref(rr->key); |
| 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_relative( |
| scope->manager->event, |
| &scope->conflict_event_source, |
| 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"); |
| |
| (void) sd_event_source_set_description(scope->conflict_event_source, "scope-conflict"); |
| |
| return 0; |
| } |
| |
| void dns_scope_check_conflicts(DnsScope *scope, DnsPacket *p) { |
| DnsResourceRecord *rr; |
| int r; |
| |
| assert(scope); |
| assert(p); |
| |
| if (!IN_SET(p->protocol, DNS_PROTOCOL_LLMNR, DNS_PROTOCOL_MDNS)) |
| return; |
| |
| if (DNS_PACKET_RRCOUNT(p) <= 0) |
| return; |
| |
| if (p->protocol == DNS_PROTOCOL_LLMNR) { |
| if (DNS_PACKET_LLMNR_C(p) != 0) |
| return; |
| |
| if (DNS_PACKET_LLMNR_T(p) != 0) |
| return; |
| } |
| |
| if (manager_packet_from_local_address(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..."); |
| |
| DNS_ANSWER_FOREACH(rr, p->answer) { |
| /* No conflict if it is DNS-SD RR used for service enumeration. */ |
| if (dns_resource_key_is_dnssd_ptr(rr->key)) |
| continue; |
| |
| /* Check for conflicts against the local zone. If we |
| * found one, we won't check any further */ |
| r = dns_zone_check_conflicts(&scope->zone, rr); |
| 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, rr, p->family, &p->sender); |
| if (r <= 0) |
| continue; |
| |
| dns_scope_notify_conflict(scope, rr); |
| } |
| } |
| |
| void dns_scope_dump(DnsScope *s, FILE *f) { |
| assert(s); |
| |
| if (!f) |
| f = stdout; |
| |
| fputs("[Scope protocol=", f); |
| fputs(dns_protocol_to_string(s->protocol), f); |
| |
| if (s->link) { |
| fputs(" interface=", f); |
| fputs(s->link->ifname, f); |
| } |
| |
| if (s->family != AF_UNSPEC) { |
| fputs(" family=", f); |
| fputs(af_to_name(s->family), f); |
| } |
| |
| fputs("]\n", f); |
| |
| if (!dns_zone_is_empty(&s->zone)) { |
| fputs("ZONE:\n", f); |
| dns_zone_dump(&s->zone, f); |
| } |
| |
| if (!dns_cache_is_empty(&s->cache)) { |
| fputs("CACHE:\n", f); |
| dns_cache_dump(&s->cache, f); |
| } |
| } |
| |
| DnsSearchDomain *dns_scope_get_search_domains(DnsScope *s) { |
| assert(s); |
| |
| if (s->protocol != DNS_PROTOCOL_DNS) |
| return NULL; |
| |
| if (s->link) |
| return s->link->search_domains; |
| |
| return s->manager->search_domains; |
| } |
| |
| bool dns_scope_name_wants_search_domain(DnsScope *s, const char *name) { |
| assert(s); |
| |
| if (s->protocol != DNS_PROTOCOL_DNS) |
| return false; |
| |
| return dns_name_is_single_label(name); |
| } |
| |
| bool dns_scope_network_good(DnsScope *s) { |
| /* Checks whether the network is in good state for lookups on this scope. For mDNS/LLMNR/Classic DNS scopes |
| * bound to links this is easy, as they don't even exist if the link isn't in a suitable state. For the global |
| * DNS scope we check whether there are any links that are up and have an address. |
| * |
| * Note that Linux routing is complex and even systems that superficially have no IPv4 address might |
| * be able to route IPv4 (and similar for IPv6), hence let's make a check here independent of address |
| * family. */ |
| |
| if (s->link) |
| return true; |
| |
| return manager_routable(s->manager); |
| } |
| |
| int dns_scope_ifindex(DnsScope *s) { |
| assert(s); |
| |
| if (s->link) |
| return s->link->ifindex; |
| |
| return 0; |
| } |
| |
| static int on_announcement_timeout(sd_event_source *s, usec_t usec, void *userdata) { |
| DnsScope *scope = userdata; |
| |
| assert(s); |
| |
| scope->announce_event_source = sd_event_source_disable_unref(scope->announce_event_source); |
| |
| (void) dns_scope_announce(scope, false); |
| return 0; |
| } |
| |
| int dns_scope_announce(DnsScope *scope, bool goodbye) { |
| _cleanup_(dns_answer_unrefp) DnsAnswer *answer = NULL; |
| _cleanup_(dns_packet_unrefp) DnsPacket *p = NULL; |
| _cleanup_set_free_ Set *types = NULL; |
| DnsTransaction *t; |
| DnsZoneItem *z, *i; |
| unsigned size = 0; |
| char *service_type; |
| int r; |
| |
| if (!scope) |
| return 0; |
| |
| if (scope->protocol != DNS_PROTOCOL_MDNS) |
| return 0; |
| |
| /* Check if we're done with probing. */ |
| LIST_FOREACH(transactions_by_scope, t, scope->transactions) |
| if (DNS_TRANSACTION_IS_LIVE(t->state)) |
| return 0; |
| |
| /* Check if there're services pending conflict resolution. */ |
| if (manager_next_dnssd_names(scope->manager)) |
| return 0; /* we reach this point only if changing hostname didn't help */ |
| |
| /* Calculate answer's size. */ |
| HASHMAP_FOREACH(z, scope->zone.by_key) { |
| if (z->state != DNS_ZONE_ITEM_ESTABLISHED) |
| continue; |
| |
| if (z->rr->key->type == DNS_TYPE_PTR && |
| !dns_zone_contains_name(&scope->zone, z->rr->ptr.name)) { |
| char key_str[DNS_RESOURCE_KEY_STRING_MAX]; |
| |
| 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)); |
| z->state = DNS_ZONE_ITEM_WITHDRAWN; |
| continue; |
| } |
| |
| /* Collect service types for _services._dns-sd._udp.local RRs in a set */ |
| if (!scope->announced && |
| dns_resource_key_is_dnssd_ptr(z->rr->key)) { |
| if (!set_contains(types, dns_resource_key_name(z->rr->key))) { |
| r = set_ensure_put(&types, &dns_name_hash_ops, dns_resource_key_name(z->rr->key)); |
| if (r < 0) |
| return log_debug_errno(r, "Failed to add item to set: %m"); |
| } |
| } |
| |
| LIST_FOREACH(by_key, i, z) |
| size++; |
| } |
| |
| answer = dns_answer_new(size + set_size(types)); |
| if (!answer) |
| return log_oom(); |
| |
| /* Second iteration, actually add RRs to the answer. */ |
| HASHMAP_FOREACH(z, scope->zone.by_key) |
| LIST_FOREACH (by_key, i, z) { |
| DnsAnswerFlags flags; |
| |
| if (i->state != DNS_ZONE_ITEM_ESTABLISHED) |
| continue; |
| |
| if (dns_resource_key_is_dnssd_ptr(i->rr->key)) |
| flags = goodbye ? DNS_ANSWER_GOODBYE : 0; |
| else |
| flags = goodbye ? (DNS_ANSWER_GOODBYE|DNS_ANSWER_CACHE_FLUSH) : DNS_ANSWER_CACHE_FLUSH; |
| |
| r = dns_answer_add(answer, i->rr, 0, flags, NULL); |
| if (r < 0) |
| return log_debug_errno(r, "Failed to add RR to announce: %m"); |
| } |
| |
| /* Since all the active services are in the zone make them discoverable now. */ |
| SET_FOREACH(service_type, types) { |
| _cleanup_(dns_resource_record_unrefp) DnsResourceRecord *rr = NULL; |
| |
| rr = dns_resource_record_new_full(DNS_CLASS_IN, DNS_TYPE_PTR, |
| "_services._dns-sd._udp.local"); |
| rr->ptr.name = strdup(service_type); |
| rr->ttl = MDNS_DEFAULT_TTL; |
| |
| r = dns_zone_put(&scope->zone, scope, rr, false); |
| if (r < 0) |
| log_warning_errno(r, "Failed to add DNS-SD PTR record to MDNS zone: %m"); |
| |
| r = dns_answer_add(answer, rr, 0, 0, NULL); |
| if (r < 0) |
| return log_debug_errno(r, "Failed to add RR to announce: %m"); |
| } |
| |
| if (dns_answer_isempty(answer)) |
| return 0; |
| |
| r = dns_scope_make_reply_packet(scope, 0, DNS_RCODE_SUCCESS, NULL, answer, NULL, false, &p); |
| if (r < 0) |
| return log_debug_errno(r, "Failed to build reply packet: %m"); |
| |
| r = dns_scope_emit_udp(scope, -1, AF_UNSPEC, p); |
| if (r < 0) |
| return log_debug_errno(r, "Failed to send reply packet: %m"); |
| |
| /* In section 8.3 of RFC6762: "The Multicast DNS responder MUST send at least two unsolicited |
| * responses, one second apart." */ |
| if (!scope->announced) { |
| scope->announced = true; |
| |
| r = sd_event_add_time_relative( |
| scope->manager->event, |
| &scope->announce_event_source, |
| clock_boottime_or_monotonic(), |
| MDNS_ANNOUNCE_DELAY, |
| MDNS_JITTER_RANGE_USEC, |
| on_announcement_timeout, scope); |
| if (r < 0) |
| return log_debug_errno(r, "Failed to schedule second announcement: %m"); |
| |
| (void) sd_event_source_set_description(scope->announce_event_source, "mdns-announce"); |
| } |
| |
| return 0; |
| } |
| |
| int dns_scope_add_dnssd_services(DnsScope *scope) { |
| DnssdService *service; |
| DnssdTxtData *txt_data; |
| int r; |
| |
| assert(scope); |
| |
| if (hashmap_size(scope->manager->dnssd_services) == 0) |
| return 0; |
| |
| scope->announced = false; |
| |
| HASHMAP_FOREACH(service, scope->manager->dnssd_services) { |
| service->withdrawn = false; |
| |
| r = dns_zone_put(&scope->zone, scope, service->ptr_rr, false); |
| if (r < 0) |
| log_warning_errno(r, "Failed to add PTR record to MDNS zone: %m"); |
| |
| r = dns_zone_put(&scope->zone, scope, service->srv_rr, true); |
| if (r < 0) |
| log_warning_errno(r, "Failed to add SRV record to MDNS zone: %m"); |
| |
| LIST_FOREACH(items, txt_data, service->txt_data_items) { |
| r = dns_zone_put(&scope->zone, scope, txt_data->rr, true); |
| if (r < 0) |
| log_warning_errno(r, "Failed to add TXT record to MDNS zone: %m"); |
| } |
| } |
| |
| return 0; |
| } |
| |
| int dns_scope_remove_dnssd_services(DnsScope *scope) { |
| _cleanup_(dns_resource_key_unrefp) DnsResourceKey *key = NULL; |
| DnssdService *service; |
| DnssdTxtData *txt_data; |
| int r; |
| |
| assert(scope); |
| |
| key = dns_resource_key_new(DNS_CLASS_IN, DNS_TYPE_PTR, |
| "_services._dns-sd._udp.local"); |
| if (!key) |
| return log_oom(); |
| |
| r = dns_zone_remove_rrs_by_key(&scope->zone, key); |
| if (r < 0) |
| return r; |
| |
| HASHMAP_FOREACH(service, scope->manager->dnssd_services) { |
| dns_zone_remove_rr(&scope->zone, service->ptr_rr); |
| dns_zone_remove_rr(&scope->zone, service->srv_rr); |
| LIST_FOREACH(items, txt_data, service->txt_data_items) |
| dns_zone_remove_rr(&scope->zone, txt_data->rr); |
| } |
| |
| return 0; |
| } |
| |
| static bool dns_scope_has_route_only_domains(DnsScope *scope) { |
| DnsSearchDomain *domain, *first; |
| bool route_only = false; |
| |
| assert(scope); |
| assert(scope->protocol == DNS_PROTOCOL_DNS); |
| |
| /* Returns 'true' if this scope is suitable for queries to specific domains only. For that we check |
| * if there are any route-only domains on this interface, as a heuristic to discern VPN-style links |
| * from non-VPN-style links. Returns 'false' for all other cases, i.e. if the scope is intended to |
| * take queries to arbitrary domains, i.e. has no routing domains set. */ |
| |
| if (scope->link) |
| first = scope->link->search_domains; |
| else |
| first = scope->manager->search_domains; |
| |
| LIST_FOREACH(domains, domain, first) { |
| /* "." means "any domain", thus the interface takes any kind of traffic. Thus, we exit early |
| * here, as it doesn't really matter whether this link has any route-only domains or not, |
| * "~." really trumps everything and clearly indicates that this interface shall receive all |
| * traffic it can get. */ |
| if (dns_name_is_root(DNS_SEARCH_DOMAIN_NAME(domain))) |
| return false; |
| |
| if (domain->route_only) |
| route_only = true; |
| } |
| |
| return route_only; |
| } |
| |
| bool dns_scope_is_default_route(DnsScope *scope) { |
| assert(scope); |
| |
| /* Only use DNS scopes as default routes */ |
| if (scope->protocol != DNS_PROTOCOL_DNS) |
| return false; |
| |
| /* The global DNS scope is always suitable as default route */ |
| if (!scope->link) |
| return true; |
| |
| /* Honour whatever is explicitly configured. This is really the best approach, and trumps any |
| * automatic logic. */ |
| if (scope->link->default_route >= 0) |
| return scope->link->default_route; |
| |
| /* Otherwise check if we have any route-only domains, as a sensible heuristic: if so, let's not |
| * volunteer as default route. */ |
| return !dns_scope_has_route_only_domains(scope); |
| } |
