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-rw-r--r--src/grp-resolve/systemd-resolved/resolved-dns-scope.c1038
1 files changed, 1038 insertions, 0 deletions
diff --git a/src/grp-resolve/systemd-resolved/resolved-dns-scope.c b/src/grp-resolve/systemd-resolved/resolved-dns-scope.c
new file mode 100644
index 0000000000..9da091b5e9
--- /dev/null
+++ b/src/grp-resolve/systemd-resolved/resolved-dns-scope.c
@@ -0,0 +1,1038 @@
+/***
+ This file is part of systemd.
+
+ Copyright 2014 Lennart Poettering
+
+ systemd is free software; you can redistribute it and/or modify it
+ under the terms of the GNU Lesser General Public License as published by
+ the Free Software Foundation; either version 2.1 of the License, or
+ (at your option) any later version.
+
+ systemd is distributed in the hope that it will be useful, but
+ WITHOUT ANY WARRANTY; without even the implied warranty of
+ MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
+ Lesser General Public License for more details.
+
+ You should have received a copy of the GNU Lesser General Public License
+ along with systemd; If not, see <http://www.gnu.org/licenses/>.
+***/
+
+#include <netinet/tcp.h>
+
+#include "basic/af-list.h"
+#include "basic/alloc-util.h"
+#include "basic/fd-util.h"
+#include "basic/hostname-util.h"
+#include "basic/missing.h"
+#include "basic/random-util.h"
+#include "basic/socket-util.h"
+#include "basic/strv.h"
+#include "shared/dns-domain.h"
+
+#include "resolved-dns-scope.h"
+#include "resolved-llmnr.h"
+#include "resolved-mdns.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 = new0(DnsScope, 1);
+ if (!s)
+ return -ENOMEM;
+
+ s->manager = m;
+ s->link = l;
+ s->protocol = protocol;
+ s->family = family;
+ s->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);
+ else
+ s->dnssec_mode = manager_get_dnssec_mode(m);
+ } else
+ s->dnssec_mode = DNSSEC_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->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;
+}
+
+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) {
+ DnsResourceRecord *rr;
+
+ if (!s)
+ return NULL;
+
+ log_debug("Removing scope on link %s, protocol %s, family %s", s->link ? s->link->name : "*", 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_free(s->query_candidates);
+
+ hashmap_free(s->transactions_by_key);
+
+ 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);
+
+ LIST_REMOVE(scopes, s->manager->dns_scopes, s);
+ free(s);
+
+ return NULL;
+}
+
+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);
+}
+
+void dns_scope_next_dns_server(DnsScope *s) {
+ assert(s);
+
+ if (s->protocol != DNS_PROTOCOL_DNS)
+ return;
+
+ if (s->link)
+ link_next_dns_server(s->link);
+ else
+ manager_next_dns_server(s->manager);
+}
+
+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, DnsPacket *p) {
+ union in_addr_union addr;
+ int ifindex = 0, r;
+ int family;
+ uint32_t mtu;
+
+ assert(s);
+ assert(p);
+ assert(p->protocol == s->protocol);
+
+ if (s->link) {
+ mtu = s->link->mtu;
+ ifindex = s->link->ifindex;
+ } else
+ mtu = manager_find_mtu(s->manager);
+
+ switch (s->protocol) {
+
+ case DNS_PROTOCOL_DNS:
+ assert(fd >= 0);
+
+ if (DNS_PACKET_QDCOUNT(p) > 1)
+ return -EOPNOTSUPP;
+
+ if (p->size > DNS_PACKET_UNICAST_SIZE_MAX)
+ return -EMSGSIZE;
+
+ if (p->size + UDP_PACKET_HEADER_SIZE > mtu)
+ return -EMSGSIZE;
+
+ r = manager_write(s->manager, fd, p);
+ if (r < 0)
+ return r;
+
+ break;
+
+ case DNS_PROTOCOL_LLMNR:
+ assert(fd < 0);
+
+ if (DNS_PACKET_QDCOUNT(p) > 1)
+ return -EOPNOTSUPP;
+
+ if (!ratelimit_test(&s->ratelimit))
+ return -EBUSY;
+
+ family = s->family;
+
+ 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, ifindex, family, &addr, LLMNR_PORT, NULL, p);
+ if (r < 0)
+ return r;
+
+ break;
+
+ case DNS_PROTOCOL_MDNS:
+ assert(fd < 0);
+
+ if (!ratelimit_test(&s->ratelimit))
+ return -EBUSY;
+
+ family = s->family;
+
+ if (family == AF_INET) {
+ addr.in = MDNS_MULTICAST_IPV4_ADDRESS;
+ fd = manager_mdns_ipv4_fd(s->manager);
+ } else if (family == AF_INET6) {
+ addr.in6 = MDNS_MULTICAST_IPV6_ADDRESS;
+ fd = manager_mdns_ipv6_fd(s->manager);
+ } else
+ return -EAFNOSUPPORT;
+ if (fd < 0)
+ return fd;
+
+ r = manager_send(s->manager, fd, ifindex, family, &addr, MDNS_PORT, NULL, p);
+ if (r < 0)
+ return r;
+
+ break;
+
+ default:
+ return -EAFNOSUPPORT;
+ }
+
+ return 1;
+}
+
+int dns_scope_emit_udp(DnsScope *s, int fd, 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, 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) {
+
+ _cleanup_close_ int fd = -1;
+ union sockaddr_union sa = {};
+ socklen_t salen;
+ static const int one = 1;
+ int ret, r, ifindex;
+
+ assert(s);
+
+ if (server) {
+ assert(family == AF_UNSPEC);
+ assert(!address);
+
+ ifindex = dns_server_ifindex(server);
+
+ sa.sa.sa_family = server->family;
+ if (server->family == AF_INET) {
+ sa.in.sin_port = htobe16(port);
+ sa.in.sin_addr = server->address.in;
+ salen = sizeof(sa.in);
+ } else if (server->family == AF_INET6) {
+ sa.in6.sin6_port = htobe16(port);
+ sa.in6.sin6_addr = server->address.in6;
+ sa.in6.sin6_scope_id = ifindex;
+ salen = sizeof(sa.in6);
+ } else
+ return -EAFNOSUPPORT;
+ } else {
+ assert(family != AF_UNSPEC);
+ assert(address);
+
+ sa.sa.sa_family = family;
+ ifindex = s->link ? s->link->ifindex : 0;
+
+ if (family == AF_INET) {
+ sa.in.sin_port = htobe16(port);
+ sa.in.sin_addr = address->in;
+ salen = sizeof(sa.in);
+ } else if (family == AF_INET6) {
+ sa.in6.sin6_port = htobe16(port);
+ sa.in6.sin6_addr = address->in6;
+ sa.in6.sin6_scope_id = ifindex;
+ salen = sizeof(sa.in6);
+ } else
+ 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(fd, IPPROTO_TCP, TCP_NODELAY, &one, sizeof(one));
+ if (r < 0)
+ return -errno;
+ }
+
+ if (s->link) {
+ be32_t ifindex_be = htobe32(ifindex);
+
+ if (sa.sa.sa_family == AF_INET) {
+ r = setsockopt(fd, IPPROTO_IP, IP_UNICAST_IF, &ifindex_be, sizeof(ifindex_be));
+ if (r < 0)
+ return -errno;
+ } else if (sa.sa.sa_family == AF_INET6) {
+ r = setsockopt(fd, IPPROTO_IPV6, IPV6_UNICAST_IF, &ifindex_be, sizeof(ifindex_be));
+ if (r < 0)
+ return -errno;
+ }
+ }
+
+ if (s->protocol == DNS_PROTOCOL_LLMNR) {
+ /* RFC 4795, section 2.5 requires the TTL to be set to 1 */
+
+ if (sa.sa.sa_family == AF_INET) {
+ r = setsockopt(fd, IPPROTO_IP, IP_TTL, &one, sizeof(one));
+ if (r < 0)
+ return -errno;
+ } else if (sa.sa.sa_family == AF_INET6) {
+ r = setsockopt(fd, IPPROTO_IPV6, IPV6_UNICAST_HOPS, &one, sizeof(one));
+ if (r < 0)
+ return -errno;
+ }
+ }
+
+ r = connect(fd, &sa.sa, salen);
+ if (r < 0 && errno != EINPROGRESS)
+ return -errno;
+
+ ret = fd;
+ fd = -1;
+
+ return ret;
+}
+
+int dns_scope_socket_udp(DnsScope *s, DnsServer *server, uint16_t port) {
+ return dns_scope_socket(s, SOCK_DGRAM, AF_UNSPEC, NULL, server, port);
+}
+
+int dns_scope_socket_tcp(DnsScope *s, int family, const union in_addr_union *address, DnsServer *server, uint16_t port) {
+ return dns_scope_socket(s, SOCK_STREAM, family, address, server, port);
+}
+
+DnsScopeMatch dns_scope_good_domain(DnsScope *s, int ifindex, uint64_t flags, const char *domain) {
+ DnsSearchDomain *d;
+
+ assert(s);
+ assert(domain);
+
+ /* 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 prefixed yet. */
+
+ if (ifindex != 0 && (!s->link || s->link->ifindex != ifindex))
+ return DNS_SCOPE_NO;
+
+ if ((SD_RESOLVED_FLAGS_MAKE(s->protocol, s->family, 0) & 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;
+
+ /* Always honour search domains for routing queries. Note that
+ * we return DNS_SCOPE_YES here, rather than just
+ * DNS_SCOPE_MAYBE, which means wildcard scopes won't be
+ * considered anymore. */
+ LIST_FOREACH(domains, d, dns_scope_get_search_domains(s))
+ if (dns_name_endswith(domain, d->name) > 0)
+ return DNS_SCOPE_YES;
+
+ switch (s->protocol) {
+
+ case DNS_PROTOCOL_DNS:
+
+ /* Exclude link-local IP ranges */
+ if (dns_name_endswith(domain, "254.169.in-addr.arpa") == 0 &&
+ 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 &&
+ /* 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_MAYBE;
+
+ return DNS_SCOPE_NO;
+
+ case DNS_PROTOCOL_MDNS:
+ if ((s->family == AF_INET && dns_name_endswith(domain, "in-addr.arpa") > 0) ||
+ (s->family == AF_INET6 && dns_name_endswith(domain, "ip6.arpa") > 0) ||
+ (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_MAYBE;
+
+ return DNS_SCOPE_NO;
+
+ case DNS_PROTOCOL_LLMNR:
+ if ((s->family == AF_INET && dns_name_endswith(domain, "in-addr.arpa") > 0) ||
+ (s->family == AF_INET6 && dns_name_endswith(domain, "ip6.arpa") > 0) ||
+ (dns_name_is_single_label(domain) && /* only resolve single label names via LLMNR */
+ !is_gateway_hostname(domain) && /* don't resolve "gateway" with LLMNR, let nss-myhostname handle this */
+ manager_is_own_hostname(s->manager, domain) <= 0)) /* never resolve the local hostname via LLMNR */
+ return DNS_SCOPE_MAYBE;
+
+ 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 as fully qualified
+ * name, i.e. the search suffixes already appended. */
+
+ if (key->class != DNS_CLASS_IN)
+ 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;
+
+ /* However, 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. */
+ return !(dns_name_is_single_label(dns_resource_key_name(key)) ||
+ dns_name_is_root(dns_resource_key_name(key)));
+ }
+
+ /* 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,
+ };
+
+ fd = manager_llmnr_ipv4_udp_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,
+ };
+
+ fd = manager_llmnr_ipv6_udp_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);
+}
+
+static 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;
+ int r;
+
+ 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);
+ if (r < 0)
+ return r;
+
+ DNS_PACKET_HEADER(p)->id = id;
+ DNS_PACKET_HEADER(p)->flags = htobe16(DNS_PACKET_MAKE_FLAGS(
+ 1 /* qr */,
+ 0 /* opcode */,
+ 0 /* c */,
+ 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);
+ if (r < 0)
+ return r;
+ DNS_PACKET_HEADER(p)->ancount = htobe16(dns_answer_size(answer));
+
+ r = dns_packet_append_answer(p, soa);
+ if (r < 0)
+ return r;
+ DNS_PACKET_HEADER(p)->arcount = htobe16(dns_answer_size(soa));
+
+ *ret = p;
+ p = NULL;
+
+ 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 && !in_addr_equal(AF_INET, &p->destination, (union in_addr_union*) &LLMNR_MULTICAST_IPV4_ADDRESS))
+ return;
+
+ if (p->family == AF_INET6 && !in_addr_equal(AF_INET6, &p->destination, (union in_addr_union*) &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 = p->question->keys[0];
+
+ r = dns_zone_lookup(&s->zone, key, 0, &answer, &soa, &tentative);
+ if (r < 0) {
+ log_debug_errno(r, "Failed to lookup key: %m");
+ return;
+ }
+ 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_test(&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, bool cache_ok) {
+ DnsTransaction *t;
+
+ assert(scope);
+ assert(key);
+
+ /* Try to find an ongoing transaction that is a equal to the
+ * specified question */
+ t = hashmap_get(scope->transactions_by_key, key);
+ if (!t)
+ return NULL;
+
+ /* 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_RCODE_FAILURE) &&
+ t->answer_source != DNS_TRANSACTION_NETWORK)
+ return NULL;
+
+ return t;
+}
+
+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));
+
+ /* 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, NULL);
+ if (r < 0)
+ return r;
+
+ r = dns_packet_append_rr(p, rr, NULL, 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_udp(scope, -1, 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");
+
+ (void) sd_event_source_set_description(scope->conflict_event_source, "scope-conflict");
+
+ 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_LLMNR_C(p) != 0)
+ return;
+
+ if (DNS_PACKET_LLMNR_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->items[i].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, p->answer->items[i].rr, p->family, &p->sender);
+ if (r <= 0)
+ continue;
+
+ dns_scope_notify_conflict(scope, p->answer->items[i].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->name, 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_needs_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. */
+
+ if (s->link)
+ return true;
+
+ return manager_routable(s->manager, AF_UNSPEC);
+}
+
+int dns_scope_ifindex(DnsScope *s) {
+ assert(s);
+
+ if (s->link)
+ return s->link->ifindex;
+
+ return 0;
+}
generated by cgit v1.2.3-54-g00ecf (git 2.45.2) at 2024-11-07 12:12:53 +0000