2601 lines
96 KiB
C
2601 lines
96 KiB
C
/*-*- Mode: C; c-basic-offset: 8; indent-tabs-mode: nil -*-*/
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/***
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This file is part of systemd.
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Copyright 2014 Lennart Poettering
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systemd is free software; you can redistribute it and/or modify it
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under the terms of the GNU Lesser General Public License as published by
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the Free Software Foundation; either version 2.1 of the License, or
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(at your option) any later version.
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systemd is distributed in the hope that it will be useful, but
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WITHOUT ANY WARRANTY; without even the implied warranty of
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MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
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Lesser General Public License for more details.
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You should have received a copy of the GNU Lesser General Public License
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along with systemd; If not, see <http://www.gnu.org/licenses/>.
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***/
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#include <sd-messages.h>
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#include "af-list.h"
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#include "alloc-util.h"
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#include "dns-domain.h"
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#include "fd-util.h"
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#include "random-util.h"
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#include "resolved-dns-cache.h"
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#include "resolved-dns-transaction.h"
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#include "resolved-llmnr.h"
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#include "string-table.h"
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static void dns_transaction_reset_answer(DnsTransaction *t) {
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assert(t);
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t->received = dns_packet_unref(t->received);
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t->answer = dns_answer_unref(t->answer);
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t->answer_rcode = 0;
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t->answer_dnssec_result = _DNSSEC_RESULT_INVALID;
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t->answer_source = _DNS_TRANSACTION_SOURCE_INVALID;
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t->answer_authenticated = false;
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t->answer_nsec_ttl = (uint32_t) -1;
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}
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static void dns_transaction_close_connection(DnsTransaction *t) {
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assert(t);
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t->stream = dns_stream_free(t->stream);
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t->dns_udp_event_source = sd_event_source_unref(t->dns_udp_event_source);
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t->dns_udp_fd = safe_close(t->dns_udp_fd);
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}
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static void dns_transaction_stop_timeout(DnsTransaction *t) {
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assert(t);
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t->timeout_event_source = sd_event_source_unref(t->timeout_event_source);
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}
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DnsTransaction* dns_transaction_free(DnsTransaction *t) {
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DnsQueryCandidate *c;
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DnsZoneItem *i;
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DnsTransaction *z;
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if (!t)
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return NULL;
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log_debug("Freeing transaction %" PRIu16 ".", t->id);
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dns_transaction_close_connection(t);
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dns_transaction_stop_timeout(t);
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dns_packet_unref(t->sent);
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dns_transaction_reset_answer(t);
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dns_server_unref(t->server);
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if (t->scope) {
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hashmap_remove_value(t->scope->transactions_by_key, t->key, t);
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LIST_REMOVE(transactions_by_scope, t->scope->transactions, t);
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if (t->id != 0)
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hashmap_remove(t->scope->manager->dns_transactions, UINT_TO_PTR(t->id));
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}
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while ((c = set_steal_first(t->notify_query_candidates)))
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set_remove(c->transactions, t);
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set_free(t->notify_query_candidates);
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while ((i = set_steal_first(t->notify_zone_items)))
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i->probe_transaction = NULL;
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set_free(t->notify_zone_items);
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while ((z = set_steal_first(t->notify_transactions)))
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set_remove(z->dnssec_transactions, t);
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set_free(t->notify_transactions);
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while ((z = set_steal_first(t->dnssec_transactions))) {
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set_remove(z->notify_transactions, t);
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dns_transaction_gc(z);
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}
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set_free(t->dnssec_transactions);
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dns_answer_unref(t->validated_keys);
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dns_resource_key_unref(t->key);
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free(t->key_string);
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free(t);
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return NULL;
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}
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DEFINE_TRIVIAL_CLEANUP_FUNC(DnsTransaction*, dns_transaction_free);
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bool dns_transaction_gc(DnsTransaction *t) {
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assert(t);
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if (t->block_gc > 0)
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return true;
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if (set_isempty(t->notify_query_candidates) &&
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set_isempty(t->notify_zone_items) &&
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set_isempty(t->notify_transactions)) {
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dns_transaction_free(t);
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return false;
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}
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return true;
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}
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int dns_transaction_new(DnsTransaction **ret, DnsScope *s, DnsResourceKey *key) {
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_cleanup_(dns_transaction_freep) DnsTransaction *t = NULL;
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int r;
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assert(ret);
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assert(s);
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assert(key);
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/* Don't allow looking up invalid or pseudo RRs */
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if (!dns_type_is_valid_query(key->type))
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return -EINVAL;
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/* We only support the IN class */
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if (key->class != DNS_CLASS_IN && key->class != DNS_CLASS_ANY)
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return -EOPNOTSUPP;
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r = hashmap_ensure_allocated(&s->manager->dns_transactions, NULL);
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if (r < 0)
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return r;
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r = hashmap_ensure_allocated(&s->transactions_by_key, &dns_resource_key_hash_ops);
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if (r < 0)
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return r;
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t = new0(DnsTransaction, 1);
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if (!t)
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return -ENOMEM;
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t->dns_udp_fd = -1;
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t->answer_source = _DNS_TRANSACTION_SOURCE_INVALID;
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t->answer_dnssec_result = _DNSSEC_RESULT_INVALID;
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t->answer_nsec_ttl = (uint32_t) -1;
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t->key = dns_resource_key_ref(key);
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/* Find a fresh, unused transaction id */
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do
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random_bytes(&t->id, sizeof(t->id));
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while (t->id == 0 ||
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hashmap_get(s->manager->dns_transactions, UINT_TO_PTR(t->id)));
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r = hashmap_put(s->manager->dns_transactions, UINT_TO_PTR(t->id), t);
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if (r < 0) {
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t->id = 0;
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return r;
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}
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r = hashmap_replace(s->transactions_by_key, t->key, t);
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if (r < 0) {
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hashmap_remove(s->manager->dns_transactions, UINT_TO_PTR(t->id));
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return r;
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}
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LIST_PREPEND(transactions_by_scope, s->transactions, t);
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t->scope = s;
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s->manager->n_transactions_total ++;
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if (ret)
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*ret = t;
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t = NULL;
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return 0;
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}
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static void dns_transaction_tentative(DnsTransaction *t, DnsPacket *p) {
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_cleanup_free_ char *pretty = NULL;
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DnsZoneItem *z;
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assert(t);
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assert(p);
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if (manager_our_packet(t->scope->manager, p) != 0)
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return;
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in_addr_to_string(p->family, &p->sender, &pretty);
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log_debug("Transaction %" PRIu16 " for <%s> on scope %s on %s/%s got tentative packet from %s.",
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t->id,
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dns_transaction_key_string(t),
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dns_protocol_to_string(t->scope->protocol),
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t->scope->link ? t->scope->link->name : "*",
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t->scope->family == AF_UNSPEC ? "*" : af_to_name(t->scope->family),
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pretty);
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/* RFC 4795, Section 4.1 says that the peer with the
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* lexicographically smaller IP address loses */
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if (memcmp(&p->sender, &p->destination, FAMILY_ADDRESS_SIZE(p->family)) >= 0) {
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log_debug("Peer has lexicographically larger IP address and thus lost in the conflict.");
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return;
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}
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log_debug("We have the lexicographically larger IP address and thus lost in the conflict.");
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t->block_gc++;
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while ((z = set_first(t->notify_zone_items))) {
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/* First, make sure the zone item drops the reference
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* to us */
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dns_zone_item_probe_stop(z);
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/* Secondly, report this as conflict, so that we might
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* look for a different hostname */
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dns_zone_item_conflict(z);
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}
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t->block_gc--;
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dns_transaction_gc(t);
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}
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void dns_transaction_complete(DnsTransaction *t, DnsTransactionState state) {
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DnsQueryCandidate *c;
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DnsZoneItem *z;
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DnsTransaction *d;
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Iterator i;
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assert(t);
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assert(!DNS_TRANSACTION_IS_LIVE(state));
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if (state == DNS_TRANSACTION_DNSSEC_FAILED)
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log_struct(LOG_NOTICE,
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LOG_MESSAGE_ID(SD_MESSAGE_DNSSEC_FAILURE),
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LOG_MESSAGE("DNSSEC validation failed for question %s: %s", dns_transaction_key_string(t), dnssec_result_to_string(t->answer_dnssec_result)),
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"DNS_TRANSACTION=%" PRIu16, t->id,
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"DNS_QUESTION=%s", dns_transaction_key_string(t),
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"DNSSEC_RESULT=%s", dnssec_result_to_string(t->answer_dnssec_result),
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NULL);
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/* Note that this call might invalidate the query. Callers
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* should hence not attempt to access the query or transaction
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* after calling this function. */
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log_debug("Transaction %" PRIu16 " for <%s> on scope %s on %s/%s now complete with <%s> from %s (%s).",
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t->id,
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dns_transaction_key_string(t),
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dns_protocol_to_string(t->scope->protocol),
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t->scope->link ? t->scope->link->name : "*",
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t->scope->family == AF_UNSPEC ? "*" : af_to_name(t->scope->family),
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dns_transaction_state_to_string(state),
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t->answer_source < 0 ? "none" : dns_transaction_source_to_string(t->answer_source),
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t->answer_authenticated ? "authenticated" : "unsigned");
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t->state = state;
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dns_transaction_close_connection(t);
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dns_transaction_stop_timeout(t);
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/* Notify all queries that are interested, but make sure the
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* transaction isn't freed while we are still looking at it */
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t->block_gc++;
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SET_FOREACH(c, t->notify_query_candidates, i)
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dns_query_candidate_notify(c);
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SET_FOREACH(z, t->notify_zone_items, i)
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dns_zone_item_notify(z);
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if (!set_isempty(t->notify_transactions)) {
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DnsTransaction **nt;
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unsigned j, n = 0;
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/* We need to be careful when notifying other
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* transactions, as that might destroy other
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* transactions in our list. Hence, in order to be
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* able to safely iterate through the list of
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* transactions, take a GC lock on all of them
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* first. Then, in a second loop, notify them, but
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* first unlock that specific transaction. */
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nt = newa(DnsTransaction*, set_size(t->notify_transactions));
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SET_FOREACH(d, t->notify_transactions, i) {
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nt[n++] = d;
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d->block_gc++;
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}
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assert(n == set_size(t->notify_transactions));
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for (j = 0; j < n; j++) {
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if (set_contains(t->notify_transactions, nt[j]))
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dns_transaction_notify(nt[j], t);
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nt[j]->block_gc--;
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dns_transaction_gc(nt[j]);
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}
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}
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t->block_gc--;
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dns_transaction_gc(t);
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}
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static int dns_transaction_pick_server(DnsTransaction *t) {
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DnsServer *server;
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assert(t);
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assert(t->scope->protocol == DNS_PROTOCOL_DNS);
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server = dns_scope_get_dns_server(t->scope);
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if (!server)
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return -ESRCH;
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t->current_features = dns_server_possible_feature_level(server);
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if (server == t->server)
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return 0;
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dns_server_unref(t->server);
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t->server = dns_server_ref(server);
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return 1;
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}
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static int on_stream_complete(DnsStream *s, int error) {
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_cleanup_(dns_packet_unrefp) DnsPacket *p = NULL;
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DnsTransaction *t;
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assert(s);
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assert(s->transaction);
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/* Copy the data we care about out of the stream before we
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* destroy it. */
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t = s->transaction;
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p = dns_packet_ref(s->read_packet);
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t->stream = dns_stream_free(t->stream);
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if (IN_SET(error, ENOTCONN, ECONNRESET, ECONNREFUSED, ECONNABORTED, EPIPE)) {
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dns_transaction_complete(t, DNS_TRANSACTION_CONNECTION_FAILURE);
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return 0;
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}
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if (error != 0) {
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dns_transaction_complete(t, DNS_TRANSACTION_RESOURCES);
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return 0;
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}
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if (dns_packet_validate_reply(p) <= 0) {
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log_debug("Invalid TCP reply packet.");
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dns_transaction_complete(t, DNS_TRANSACTION_INVALID_REPLY);
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return 0;
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}
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dns_scope_check_conflicts(t->scope, p);
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t->block_gc++;
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dns_transaction_process_reply(t, p);
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t->block_gc--;
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/* If the response wasn't useful, then complete the transition
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* now. After all, we are the worst feature set now with TCP
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* sockets, and there's really no point in retrying. */
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if (t->state == DNS_TRANSACTION_PENDING)
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dns_transaction_complete(t, DNS_TRANSACTION_INVALID_REPLY);
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else
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dns_transaction_gc(t);
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return 0;
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}
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static int dns_transaction_open_tcp(DnsTransaction *t) {
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_cleanup_close_ int fd = -1;
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int r;
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assert(t);
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dns_transaction_close_connection(t);
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switch (t->scope->protocol) {
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case DNS_PROTOCOL_DNS:
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r = dns_transaction_pick_server(t);
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if (r < 0)
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return r;
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r = dns_server_adjust_opt(t->server, t->sent, t->current_features);
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if (r < 0)
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return r;
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fd = dns_scope_socket_tcp(t->scope, AF_UNSPEC, NULL, t->server, 53);
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break;
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case DNS_PROTOCOL_LLMNR:
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/* When we already received a reply to this (but it was truncated), send to its sender address */
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if (t->received)
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fd = dns_scope_socket_tcp(t->scope, t->received->family, &t->received->sender, NULL, t->received->sender_port);
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else {
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union in_addr_union address;
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int family = AF_UNSPEC;
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/* Otherwise, try to talk to the owner of a
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* the IP address, in case this is a reverse
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* PTR lookup */
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r = dns_name_address(DNS_RESOURCE_KEY_NAME(t->key), &family, &address);
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if (r < 0)
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return r;
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if (r == 0)
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return -EINVAL;
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if (family != t->scope->family)
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return -ESRCH;
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fd = dns_scope_socket_tcp(t->scope, family, &address, NULL, LLMNR_PORT);
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}
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break;
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default:
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return -EAFNOSUPPORT;
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}
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if (fd < 0)
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return fd;
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r = dns_stream_new(t->scope->manager, &t->stream, t->scope->protocol, fd);
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if (r < 0)
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return r;
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fd = -1;
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r = dns_stream_write_packet(t->stream, t->sent);
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if (r < 0) {
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t->stream = dns_stream_free(t->stream);
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return r;
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}
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t->stream->complete = on_stream_complete;
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t->stream->transaction = t;
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/* The interface index is difficult to determine if we are
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* connecting to the local host, hence fill this in right away
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* instead of determining it from the socket */
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if (t->scope->link)
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t->stream->ifindex = t->scope->link->ifindex;
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dns_transaction_reset_answer(t);
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t->tried_stream = true;
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return 0;
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}
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static void dns_transaction_cache_answer(DnsTransaction *t) {
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assert(t);
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/* For mDNS we cache whenever we get the packet, rather than
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* in each transaction. */
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if (!IN_SET(t->scope->protocol, DNS_PROTOCOL_DNS, DNS_PROTOCOL_LLMNR))
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return;
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/* We never cache if this packet is from the local host, under
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* the assumption that a locally running DNS server would
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* cache this anyway, and probably knows better when to flush
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* the cache then we could. */
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if (!DNS_PACKET_SHALL_CACHE(t->received))
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return;
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dns_cache_put(&t->scope->cache,
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t->key,
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t->answer_rcode,
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t->answer,
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t->answer_authenticated,
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t->answer_nsec_ttl,
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0,
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t->received->family,
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&t->received->sender);
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}
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static bool dns_transaction_dnssec_is_live(DnsTransaction *t) {
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DnsTransaction *dt;
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Iterator i;
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assert(t);
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SET_FOREACH(dt, t->dnssec_transactions, i)
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if (DNS_TRANSACTION_IS_LIVE(dt->state))
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return true;
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return false;
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}
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static void dns_transaction_process_dnssec(DnsTransaction *t) {
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int r;
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assert(t);
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/* Are there ongoing DNSSEC transactions? If so, let's wait for them. */
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if (dns_transaction_dnssec_is_live(t))
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return;
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/* All our auxiliary DNSSEC transactions are complete now. Try
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* to validate our RRset now. */
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r = dns_transaction_validate_dnssec(t);
|
|
if (r < 0) {
|
|
dns_transaction_complete(t, DNS_TRANSACTION_RESOURCES);
|
|
return;
|
|
}
|
|
|
|
if (t->answer_dnssec_result == DNSSEC_INCOMPATIBLE_SERVER &&
|
|
t->scope->dnssec_mode == DNSSEC_YES) {
|
|
/* We are not in automatic downgrade mode, and the
|
|
* server is bad, refuse operation. */
|
|
dns_transaction_complete(t, DNS_TRANSACTION_DNSSEC_FAILED);
|
|
return;
|
|
}
|
|
|
|
if (!IN_SET(t->answer_dnssec_result,
|
|
_DNSSEC_RESULT_INVALID, /* No DNSSEC validation enabled */
|
|
DNSSEC_VALIDATED, /* Answer is signed and validated successfully */
|
|
DNSSEC_UNSIGNED, /* Answer is right-fully unsigned */
|
|
DNSSEC_INCOMPATIBLE_SERVER)) { /* Server does not do DNSSEC (Yay, we are downgrade attack vulnerable!) */
|
|
dns_transaction_complete(t, DNS_TRANSACTION_DNSSEC_FAILED);
|
|
return;
|
|
}
|
|
|
|
dns_transaction_cache_answer(t);
|
|
|
|
if (t->answer_rcode == DNS_RCODE_SUCCESS)
|
|
dns_transaction_complete(t, DNS_TRANSACTION_SUCCESS);
|
|
else
|
|
dns_transaction_complete(t, DNS_TRANSACTION_RCODE_FAILURE);
|
|
}
|
|
|
|
void dns_transaction_process_reply(DnsTransaction *t, DnsPacket *p) {
|
|
usec_t ts;
|
|
int r;
|
|
|
|
assert(t);
|
|
assert(p);
|
|
assert(t->scope);
|
|
assert(t->scope->manager);
|
|
|
|
if (t->state != DNS_TRANSACTION_PENDING)
|
|
return;
|
|
|
|
/* Note that this call might invalidate the query. Callers
|
|
* should hence not attempt to access the query or transaction
|
|
* after calling this function. */
|
|
|
|
log_debug("Processing incoming packet on transaction %" PRIu16".", t->id);
|
|
|
|
switch (t->scope->protocol) {
|
|
|
|
case DNS_PROTOCOL_LLMNR:
|
|
assert(t->scope->link);
|
|
|
|
/* For LLMNR we will not accept any packets from other
|
|
* interfaces */
|
|
|
|
if (p->ifindex != t->scope->link->ifindex)
|
|
return;
|
|
|
|
if (p->family != t->scope->family)
|
|
return;
|
|
|
|
/* Tentative packets are not full responses but still
|
|
* useful for identifying uniqueness conflicts during
|
|
* probing. */
|
|
if (DNS_PACKET_LLMNR_T(p)) {
|
|
dns_transaction_tentative(t, p);
|
|
return;
|
|
}
|
|
|
|
break;
|
|
|
|
case DNS_PROTOCOL_MDNS:
|
|
assert(t->scope->link);
|
|
|
|
/* For mDNS we will not accept any packets from other interfaces */
|
|
if (p->ifindex != t->scope->link->ifindex)
|
|
return;
|
|
|
|
if (p->family != t->scope->family)
|
|
return;
|
|
|
|
break;
|
|
|
|
case DNS_PROTOCOL_DNS:
|
|
/* Note that we do not need to verify the
|
|
* addresses/port numbers of incoming traffic, as we
|
|
* invoked connect() on our UDP socket in which case
|
|
* the kernel already does the needed verification for
|
|
* us. */
|
|
break;
|
|
|
|
default:
|
|
assert_not_reached("Invalid DNS protocol.");
|
|
}
|
|
|
|
if (t->received != p) {
|
|
dns_packet_unref(t->received);
|
|
t->received = dns_packet_ref(p);
|
|
}
|
|
|
|
t->answer_source = DNS_TRANSACTION_NETWORK;
|
|
|
|
if (p->ipproto == IPPROTO_TCP) {
|
|
if (DNS_PACKET_TC(p)) {
|
|
/* Truncated via TCP? Somebody must be fucking with us */
|
|
dns_transaction_complete(t, DNS_TRANSACTION_INVALID_REPLY);
|
|
return;
|
|
}
|
|
|
|
if (DNS_PACKET_ID(p) != t->id) {
|
|
/* Not the reply to our query? Somebody must be fucking with us */
|
|
dns_transaction_complete(t, DNS_TRANSACTION_INVALID_REPLY);
|
|
return;
|
|
}
|
|
}
|
|
|
|
assert_se(sd_event_now(t->scope->manager->event, clock_boottime_or_monotonic(), &ts) >= 0);
|
|
|
|
switch (t->scope->protocol) {
|
|
|
|
case DNS_PROTOCOL_DNS:
|
|
assert(t->server);
|
|
|
|
if (IN_SET(DNS_PACKET_RCODE(p), DNS_RCODE_FORMERR, DNS_RCODE_SERVFAIL, DNS_RCODE_NOTIMP)) {
|
|
|
|
/* Request failed, immediately try again with reduced features */
|
|
log_debug("Server returned error: %s", dns_rcode_to_string(DNS_PACKET_RCODE(p)));
|
|
|
|
dns_server_packet_failed(t->server, t->current_features);
|
|
|
|
r = dns_transaction_go(t);
|
|
if (r < 0) {
|
|
dns_transaction_complete(t, DNS_TRANSACTION_RESOURCES);
|
|
return;
|
|
}
|
|
|
|
return;
|
|
} else
|
|
dns_server_packet_received(t->server, t->current_features, ts - t->start_usec, p->size);
|
|
|
|
break;
|
|
|
|
case DNS_PROTOCOL_LLMNR:
|
|
case DNS_PROTOCOL_MDNS:
|
|
dns_scope_packet_received(t->scope, ts - t->start_usec);
|
|
break;
|
|
|
|
default:
|
|
assert_not_reached("Invalid DNS protocol.");
|
|
}
|
|
|
|
if (DNS_PACKET_TC(p)) {
|
|
|
|
/* Truncated packets for mDNS are not allowed. Give up immediately. */
|
|
if (t->scope->protocol == DNS_PROTOCOL_MDNS) {
|
|
dns_transaction_complete(t, DNS_TRANSACTION_INVALID_REPLY);
|
|
return;
|
|
}
|
|
|
|
/* Response was truncated, let's try again with good old TCP */
|
|
r = dns_transaction_open_tcp(t);
|
|
if (r == -ESRCH) {
|
|
/* No servers found? Damn! */
|
|
dns_transaction_complete(t, DNS_TRANSACTION_NO_SERVERS);
|
|
return;
|
|
}
|
|
if (r < 0) {
|
|
/* On LLMNR, if we cannot connect to the host,
|
|
* we immediately give up */
|
|
if (t->scope->protocol == DNS_PROTOCOL_LLMNR) {
|
|
dns_transaction_complete(t, DNS_TRANSACTION_RESOURCES);
|
|
return;
|
|
}
|
|
|
|
/* On DNS, couldn't send? Try immediately again, with a new server */
|
|
dns_scope_next_dns_server(t->scope);
|
|
|
|
r = dns_transaction_go(t);
|
|
if (r < 0) {
|
|
dns_transaction_complete(t, DNS_TRANSACTION_RESOURCES);
|
|
return;
|
|
}
|
|
}
|
|
|
|
return;
|
|
}
|
|
|
|
/* Parse message, if it isn't parsed yet. */
|
|
r = dns_packet_extract(p);
|
|
if (r < 0) {
|
|
dns_transaction_complete(t, DNS_TRANSACTION_INVALID_REPLY);
|
|
return;
|
|
}
|
|
|
|
if (IN_SET(t->scope->protocol, DNS_PROTOCOL_DNS, DNS_PROTOCOL_LLMNR)) {
|
|
|
|
/* Only consider responses with equivalent query section to the request */
|
|
r = dns_packet_is_reply_for(p, t->key);
|
|
if (r < 0) {
|
|
dns_transaction_complete(t, DNS_TRANSACTION_RESOURCES);
|
|
return;
|
|
}
|
|
if (r == 0) {
|
|
dns_transaction_complete(t, DNS_TRANSACTION_INVALID_REPLY);
|
|
return;
|
|
}
|
|
|
|
/* Install the answer as answer to the transaction */
|
|
dns_answer_unref(t->answer);
|
|
t->answer = dns_answer_ref(p->answer);
|
|
t->answer_rcode = DNS_PACKET_RCODE(p);
|
|
t->answer_dnssec_result = _DNSSEC_RESULT_INVALID;
|
|
t->answer_authenticated = false;
|
|
|
|
/* Block GC while starting requests for additional DNSSEC RRs */
|
|
t->block_gc++;
|
|
r = dns_transaction_request_dnssec_keys(t);
|
|
t->block_gc--;
|
|
|
|
/* Maybe the transaction is ready for GC'ing now? If so, free it and return. */
|
|
if (!dns_transaction_gc(t))
|
|
return;
|
|
|
|
/* Requesting additional keys might have resulted in
|
|
* this transaction to fail, since the auxiliary
|
|
* request failed for some reason. If so, we are not
|
|
* in pending state anymore, and we should exit
|
|
* quickly. */
|
|
if (t->state != DNS_TRANSACTION_PENDING)
|
|
return;
|
|
if (r < 0) {
|
|
dns_transaction_complete(t, DNS_TRANSACTION_RESOURCES);
|
|
return;
|
|
}
|
|
if (r > 0) {
|
|
/* There are DNSSEC transactions pending now. Update the state accordingly. */
|
|
t->state = DNS_TRANSACTION_VALIDATING;
|
|
dns_transaction_close_connection(t);
|
|
dns_transaction_stop_timeout(t);
|
|
return;
|
|
}
|
|
}
|
|
|
|
dns_transaction_process_dnssec(t);
|
|
}
|
|
|
|
static int on_dns_packet(sd_event_source *s, int fd, uint32_t revents, void *userdata) {
|
|
_cleanup_(dns_packet_unrefp) DnsPacket *p = NULL;
|
|
DnsTransaction *t = userdata;
|
|
int r;
|
|
|
|
assert(t);
|
|
assert(t->scope);
|
|
|
|
r = manager_recv(t->scope->manager, fd, DNS_PROTOCOL_DNS, &p);
|
|
if (r <= 0)
|
|
return r;
|
|
|
|
if (dns_packet_validate_reply(p) > 0 &&
|
|
DNS_PACKET_ID(p) == t->id)
|
|
dns_transaction_process_reply(t, p);
|
|
else
|
|
log_debug("Invalid DNS UDP packet, ignoring.");
|
|
|
|
return 0;
|
|
}
|
|
|
|
static int dns_transaction_emit_udp(DnsTransaction *t) {
|
|
int r;
|
|
|
|
assert(t);
|
|
|
|
if (t->scope->protocol == DNS_PROTOCOL_DNS) {
|
|
|
|
r = dns_transaction_pick_server(t);
|
|
if (r < 0)
|
|
return r;
|
|
|
|
if (t->current_features < DNS_SERVER_FEATURE_LEVEL_UDP)
|
|
return -EAGAIN;
|
|
|
|
if (r > 0 || t->dns_udp_fd < 0) { /* Server changed, or no connection yet. */
|
|
int fd;
|
|
|
|
dns_transaction_close_connection(t);
|
|
|
|
fd = dns_scope_socket_udp(t->scope, t->server, 53);
|
|
if (fd < 0)
|
|
return fd;
|
|
|
|
r = sd_event_add_io(t->scope->manager->event, &t->dns_udp_event_source, fd, EPOLLIN, on_dns_packet, t);
|
|
if (r < 0) {
|
|
safe_close(fd);
|
|
return r;
|
|
}
|
|
|
|
t->dns_udp_fd = fd;
|
|
}
|
|
|
|
r = dns_server_adjust_opt(t->server, t->sent, t->current_features);
|
|
if (r < 0)
|
|
return r;
|
|
} else
|
|
dns_transaction_close_connection(t);
|
|
|
|
r = dns_scope_emit_udp(t->scope, t->dns_udp_fd, t->sent);
|
|
if (r < 0)
|
|
return r;
|
|
|
|
dns_transaction_reset_answer(t);
|
|
|
|
return 0;
|
|
}
|
|
|
|
static int on_transaction_timeout(sd_event_source *s, usec_t usec, void *userdata) {
|
|
DnsTransaction *t = userdata;
|
|
int r;
|
|
|
|
assert(s);
|
|
assert(t);
|
|
|
|
if (!t->initial_jitter_scheduled || t->initial_jitter_elapsed) {
|
|
/* Timeout reached? Increase the timeout for the server used */
|
|
switch (t->scope->protocol) {
|
|
|
|
case DNS_PROTOCOL_DNS:
|
|
assert(t->server);
|
|
dns_server_packet_lost(t->server, t->current_features, usec - t->start_usec);
|
|
break;
|
|
|
|
case DNS_PROTOCOL_LLMNR:
|
|
case DNS_PROTOCOL_MDNS:
|
|
dns_scope_packet_lost(t->scope, usec - t->start_usec);
|
|
break;
|
|
|
|
default:
|
|
assert_not_reached("Invalid DNS protocol.");
|
|
}
|
|
|
|
if (t->initial_jitter_scheduled)
|
|
t->initial_jitter_elapsed = true;
|
|
}
|
|
|
|
log_debug("Timeout reached on transaction %" PRIu16 ".", t->id);
|
|
|
|
/* ...and try again with a new server */
|
|
dns_scope_next_dns_server(t->scope);
|
|
|
|
r = dns_transaction_go(t);
|
|
if (r < 0)
|
|
dns_transaction_complete(t, DNS_TRANSACTION_RESOURCES);
|
|
|
|
return 0;
|
|
}
|
|
|
|
static usec_t transaction_get_resend_timeout(DnsTransaction *t) {
|
|
assert(t);
|
|
assert(t->scope);
|
|
|
|
switch (t->scope->protocol) {
|
|
|
|
case DNS_PROTOCOL_DNS:
|
|
assert(t->server);
|
|
return t->server->resend_timeout;
|
|
|
|
case DNS_PROTOCOL_MDNS:
|
|
assert(t->n_attempts > 0);
|
|
return (1 << (t->n_attempts - 1)) * USEC_PER_SEC;
|
|
|
|
case DNS_PROTOCOL_LLMNR:
|
|
return t->scope->resend_timeout;
|
|
|
|
default:
|
|
assert_not_reached("Invalid DNS protocol.");
|
|
}
|
|
}
|
|
|
|
static int dns_transaction_prepare(DnsTransaction *t, usec_t ts) {
|
|
int r;
|
|
|
|
assert(t);
|
|
|
|
dns_transaction_stop_timeout(t);
|
|
|
|
if (t->n_attempts >= TRANSACTION_ATTEMPTS_MAX(t->scope->protocol)) {
|
|
dns_transaction_complete(t, DNS_TRANSACTION_ATTEMPTS_MAX_REACHED);
|
|
return 0;
|
|
}
|
|
|
|
if (t->scope->protocol == DNS_PROTOCOL_LLMNR && t->tried_stream) {
|
|
/* If we already tried via a stream, then we don't
|
|
* retry on LLMNR. See RFC 4795, Section 2.7. */
|
|
dns_transaction_complete(t, DNS_TRANSACTION_ATTEMPTS_MAX_REACHED);
|
|
return 0;
|
|
}
|
|
|
|
t->n_attempts++;
|
|
t->start_usec = ts;
|
|
|
|
dns_transaction_reset_answer(t);
|
|
|
|
/* Check the trust anchor. Do so only on classic DNS, since DNSSEC does not apply otherwise. */
|
|
if (t->scope->protocol == DNS_PROTOCOL_DNS) {
|
|
r = dns_trust_anchor_lookup_positive(&t->scope->manager->trust_anchor, t->key, &t->answer);
|
|
if (r < 0)
|
|
return r;
|
|
if (r > 0) {
|
|
t->answer_rcode = DNS_RCODE_SUCCESS;
|
|
t->answer_source = DNS_TRANSACTION_TRUST_ANCHOR;
|
|
t->answer_authenticated = true;
|
|
dns_transaction_complete(t, DNS_TRANSACTION_SUCCESS);
|
|
return 0;
|
|
}
|
|
|
|
if (dns_name_is_root(DNS_RESOURCE_KEY_NAME(t->key)) &&
|
|
t->key->type == DNS_TYPE_DS) {
|
|
|
|
/* Hmm, this is a request for the root DS? A
|
|
* DS RR doesn't exist in the root zone, and
|
|
* if our trust anchor didn't know it either,
|
|
* this means we cannot do any DNSSEC logic
|
|
* anymore. */
|
|
|
|
if (t->scope->dnssec_mode == DNSSEC_ALLOW_DOWNGRADE) {
|
|
/* We are in downgrade mode. In this
|
|
* case, synthesize an unsigned empty
|
|
* response, so that the any lookup
|
|
* depending on this one can continue
|
|
* assuming there was no DS, and hence
|
|
* the root zone was unsigned. */
|
|
|
|
t->answer_rcode = DNS_RCODE_SUCCESS;
|
|
t->answer_source = DNS_TRANSACTION_TRUST_ANCHOR;
|
|
t->answer_authenticated = false;
|
|
dns_transaction_complete(t, DNS_TRANSACTION_SUCCESS);
|
|
} else
|
|
/* If we are not in downgrade mode,
|
|
* then fail the lookup, because we
|
|
* cannot reasonably answer it. There
|
|
* might be DS RRs, but we don't know
|
|
* them, and the DNS server won't tell
|
|
* them to us (and even if it would,
|
|
* we couldn't validate it and trust
|
|
* it). */
|
|
dns_transaction_complete(t, DNS_TRANSACTION_NO_TRUST_ANCHOR);
|
|
|
|
return 0;
|
|
}
|
|
}
|
|
|
|
/* Check the zone, but only if this transaction is not used
|
|
* for probing or verifying a zone item. */
|
|
if (set_isempty(t->notify_zone_items)) {
|
|
|
|
r = dns_zone_lookup(&t->scope->zone, t->key, &t->answer, NULL, NULL);
|
|
if (r < 0)
|
|
return r;
|
|
if (r > 0) {
|
|
t->answer_rcode = DNS_RCODE_SUCCESS;
|
|
t->answer_source = DNS_TRANSACTION_ZONE;
|
|
t->answer_authenticated = true;
|
|
dns_transaction_complete(t, DNS_TRANSACTION_SUCCESS);
|
|
return 0;
|
|
}
|
|
}
|
|
|
|
/* Check the cache, but only if this transaction is not used
|
|
* for probing or verifying a zone item. */
|
|
if (set_isempty(t->notify_zone_items)) {
|
|
|
|
/* Before trying the cache, let's make sure we figured out a
|
|
* server to use. Should this cause a change of server this
|
|
* might flush the cache. */
|
|
dns_scope_get_dns_server(t->scope);
|
|
|
|
/* Let's then prune all outdated entries */
|
|
dns_cache_prune(&t->scope->cache);
|
|
|
|
r = dns_cache_lookup(&t->scope->cache, t->key, &t->answer_rcode, &t->answer, &t->answer_authenticated);
|
|
if (r < 0)
|
|
return r;
|
|
if (r > 0) {
|
|
t->answer_source = DNS_TRANSACTION_CACHE;
|
|
if (t->answer_rcode == DNS_RCODE_SUCCESS)
|
|
dns_transaction_complete(t, DNS_TRANSACTION_SUCCESS);
|
|
else
|
|
dns_transaction_complete(t, DNS_TRANSACTION_RCODE_FAILURE);
|
|
return 0;
|
|
}
|
|
}
|
|
|
|
return 1;
|
|
}
|
|
|
|
static int dns_transaction_make_packet_mdns(DnsTransaction *t) {
|
|
|
|
_cleanup_(dns_packet_unrefp) DnsPacket *p = NULL;
|
|
bool add_known_answers = false;
|
|
DnsTransaction *other;
|
|
unsigned qdcount;
|
|
usec_t ts;
|
|
int r;
|
|
|
|
assert(t);
|
|
assert(t->scope->protocol == DNS_PROTOCOL_MDNS);
|
|
|
|
/* Discard any previously prepared packet, so we can start over and coalesce again */
|
|
t->sent = dns_packet_unref(t->sent);
|
|
|
|
r = dns_packet_new_query(&p, t->scope->protocol, 0, false);
|
|
if (r < 0)
|
|
return r;
|
|
|
|
r = dns_packet_append_key(p, t->key, NULL);
|
|
if (r < 0)
|
|
return r;
|
|
|
|
qdcount = 1;
|
|
|
|
if (dns_key_is_shared(t->key))
|
|
add_known_answers = true;
|
|
|
|
/*
|
|
* For mDNS, we want to coalesce as many open queries in pending transactions into one single
|
|
* query packet on the wire as possible. To achieve that, we iterate through all pending transactions
|
|
* in our current scope, and see whether their timing contraints allow them to be sent.
|
|
*/
|
|
|
|
assert_se(sd_event_now(t->scope->manager->event, clock_boottime_or_monotonic(), &ts) >= 0);
|
|
|
|
LIST_FOREACH(transactions_by_scope, other, t->scope->transactions) {
|
|
|
|
/* Skip ourselves */
|
|
if (other == t)
|
|
continue;
|
|
|
|
if (other->state != DNS_TRANSACTION_PENDING)
|
|
continue;
|
|
|
|
if (other->next_attempt_after > ts)
|
|
continue;
|
|
|
|
if (qdcount >= UINT16_MAX)
|
|
break;
|
|
|
|
r = dns_packet_append_key(p, other->key, NULL);
|
|
|
|
/*
|
|
* If we can't stuff more questions into the packet, just give up.
|
|
* One of the 'other' transactions will fire later and take care of the rest.
|
|
*/
|
|
if (r == -EMSGSIZE)
|
|
break;
|
|
|
|
if (r < 0)
|
|
return r;
|
|
|
|
r = dns_transaction_prepare(other, ts);
|
|
if (r <= 0)
|
|
continue;
|
|
|
|
ts += transaction_get_resend_timeout(other);
|
|
|
|
r = sd_event_add_time(
|
|
other->scope->manager->event,
|
|
&other->timeout_event_source,
|
|
clock_boottime_or_monotonic(),
|
|
ts, 0,
|
|
on_transaction_timeout, other);
|
|
if (r < 0)
|
|
return r;
|
|
|
|
other->state = DNS_TRANSACTION_PENDING;
|
|
other->next_attempt_after = ts;
|
|
|
|
qdcount ++;
|
|
|
|
if (dns_key_is_shared(other->key))
|
|
add_known_answers = true;
|
|
}
|
|
|
|
DNS_PACKET_HEADER(p)->qdcount = htobe16(qdcount);
|
|
|
|
/* Append known answer section if we're asking for any shared record */
|
|
if (add_known_answers) {
|
|
r = dns_cache_export_shared_to_packet(&t->scope->cache, p);
|
|
if (r < 0)
|
|
return r;
|
|
}
|
|
|
|
t->sent = p;
|
|
p = NULL;
|
|
|
|
return 0;
|
|
}
|
|
|
|
static int dns_transaction_make_packet(DnsTransaction *t) {
|
|
_cleanup_(dns_packet_unrefp) DnsPacket *p = NULL;
|
|
int r;
|
|
|
|
assert(t);
|
|
|
|
if (t->scope->protocol == DNS_PROTOCOL_MDNS)
|
|
return dns_transaction_make_packet_mdns(t);
|
|
|
|
if (t->sent)
|
|
return 0;
|
|
|
|
r = dns_packet_new_query(&p, t->scope->protocol, 0, t->scope->dnssec_mode != DNSSEC_NO);
|
|
if (r < 0)
|
|
return r;
|
|
|
|
r = dns_scope_good_key(t->scope, t->key);
|
|
if (r < 0)
|
|
return r;
|
|
if (r == 0)
|
|
return -EDOM;
|
|
|
|
r = dns_packet_append_key(p, t->key, NULL);
|
|
if (r < 0)
|
|
return r;
|
|
|
|
DNS_PACKET_HEADER(p)->qdcount = htobe16(1);
|
|
DNS_PACKET_HEADER(p)->id = t->id;
|
|
|
|
t->sent = p;
|
|
p = NULL;
|
|
|
|
return 0;
|
|
}
|
|
|
|
int dns_transaction_go(DnsTransaction *t) {
|
|
usec_t ts;
|
|
int r;
|
|
|
|
assert(t);
|
|
|
|
assert_se(sd_event_now(t->scope->manager->event, clock_boottime_or_monotonic(), &ts) >= 0);
|
|
|
|
r = dns_transaction_prepare(t, ts);
|
|
if (r <= 0)
|
|
return r;
|
|
|
|
log_debug("Excercising transaction %" PRIu16 " for <%s> on scope %s on %s/%s.",
|
|
t->id,
|
|
dns_transaction_key_string(t),
|
|
dns_protocol_to_string(t->scope->protocol),
|
|
t->scope->link ? t->scope->link->name : "*",
|
|
t->scope->family == AF_UNSPEC ? "*" : af_to_name(t->scope->family));
|
|
|
|
if (!t->initial_jitter_scheduled &&
|
|
(t->scope->protocol == DNS_PROTOCOL_LLMNR ||
|
|
t->scope->protocol == DNS_PROTOCOL_MDNS)) {
|
|
usec_t jitter, accuracy;
|
|
|
|
/* RFC 4795 Section 2.7 suggests all queries should be
|
|
* delayed by a random time from 0 to JITTER_INTERVAL. */
|
|
|
|
t->initial_jitter_scheduled = true;
|
|
|
|
random_bytes(&jitter, sizeof(jitter));
|
|
|
|
switch (t->scope->protocol) {
|
|
|
|
case DNS_PROTOCOL_LLMNR:
|
|
jitter %= LLMNR_JITTER_INTERVAL_USEC;
|
|
accuracy = LLMNR_JITTER_INTERVAL_USEC;
|
|
break;
|
|
|
|
case DNS_PROTOCOL_MDNS:
|
|
jitter %= MDNS_JITTER_RANGE_USEC;
|
|
jitter += MDNS_JITTER_MIN_USEC;
|
|
accuracy = MDNS_JITTER_RANGE_USEC;
|
|
break;
|
|
default:
|
|
assert_not_reached("bad protocol");
|
|
}
|
|
|
|
r = sd_event_add_time(
|
|
t->scope->manager->event,
|
|
&t->timeout_event_source,
|
|
clock_boottime_or_monotonic(),
|
|
ts + jitter, accuracy,
|
|
on_transaction_timeout, t);
|
|
if (r < 0)
|
|
return r;
|
|
|
|
t->n_attempts = 0;
|
|
t->next_attempt_after = ts;
|
|
t->state = DNS_TRANSACTION_PENDING;
|
|
|
|
log_debug("Delaying %s transaction for " USEC_FMT "us.", dns_protocol_to_string(t->scope->protocol), jitter);
|
|
return 0;
|
|
}
|
|
|
|
/* Otherwise, we need to ask the network */
|
|
r = dns_transaction_make_packet(t);
|
|
if (r == -EDOM) {
|
|
/* Not the right request to make on this network?
|
|
* (i.e. an A request made on IPv6 or an AAAA request
|
|
* made on IPv4, on LLMNR or mDNS.) */
|
|
dns_transaction_complete(t, DNS_TRANSACTION_NO_SERVERS);
|
|
return 0;
|
|
}
|
|
if (r < 0)
|
|
return r;
|
|
|
|
if (t->scope->protocol == DNS_PROTOCOL_LLMNR &&
|
|
(dns_name_endswith(DNS_RESOURCE_KEY_NAME(t->key), "in-addr.arpa") > 0 ||
|
|
dns_name_endswith(DNS_RESOURCE_KEY_NAME(t->key), "ip6.arpa") > 0)) {
|
|
|
|
/* RFC 4795, Section 2.4. says reverse lookups shall
|
|
* always be made via TCP on LLMNR */
|
|
r = dns_transaction_open_tcp(t);
|
|
} else {
|
|
/* Try via UDP, and if that fails due to large size or lack of
|
|
* support try via TCP */
|
|
r = dns_transaction_emit_udp(t);
|
|
if (r == -EMSGSIZE || r == -EAGAIN)
|
|
r = dns_transaction_open_tcp(t);
|
|
}
|
|
|
|
if (r == -ESRCH) {
|
|
/* No servers to send this to? */
|
|
dns_transaction_complete(t, DNS_TRANSACTION_NO_SERVERS);
|
|
return 0;
|
|
} else if (r < 0) {
|
|
if (t->scope->protocol != DNS_PROTOCOL_DNS) {
|
|
dns_transaction_complete(t, DNS_TRANSACTION_RESOURCES);
|
|
return 0;
|
|
}
|
|
|
|
/* Couldn't send? Try immediately again, with a new server */
|
|
dns_scope_next_dns_server(t->scope);
|
|
|
|
return dns_transaction_go(t);
|
|
}
|
|
|
|
ts += transaction_get_resend_timeout(t);
|
|
|
|
r = sd_event_add_time(
|
|
t->scope->manager->event,
|
|
&t->timeout_event_source,
|
|
clock_boottime_or_monotonic(),
|
|
ts, 0,
|
|
on_transaction_timeout, t);
|
|
if (r < 0)
|
|
return r;
|
|
|
|
t->state = DNS_TRANSACTION_PENDING;
|
|
t->next_attempt_after = ts;
|
|
|
|
return 1;
|
|
}
|
|
|
|
static int dns_transaction_find_cyclic(DnsTransaction *t, DnsTransaction *aux) {
|
|
DnsTransaction *n;
|
|
Iterator i;
|
|
int r;
|
|
|
|
assert(t);
|
|
assert(aux);
|
|
|
|
/* Try to find cyclic dependencies between transaction objects */
|
|
|
|
if (t == aux)
|
|
return 1;
|
|
|
|
SET_FOREACH(n, aux->dnssec_transactions, i) {
|
|
r = dns_transaction_find_cyclic(t, n);
|
|
if (r != 0)
|
|
return r;
|
|
}
|
|
|
|
return 0;
|
|
}
|
|
|
|
static int dns_transaction_add_dnssec_transaction(DnsTransaction *t, DnsResourceKey *key, DnsTransaction **ret) {
|
|
DnsTransaction *aux;
|
|
int r;
|
|
|
|
assert(t);
|
|
assert(ret);
|
|
assert(key);
|
|
|
|
aux = dns_scope_find_transaction(t->scope, key, true);
|
|
if (!aux) {
|
|
r = dns_transaction_new(&aux, t->scope, key);
|
|
if (r < 0)
|
|
return r;
|
|
} else {
|
|
if (set_contains(t->dnssec_transactions, aux)) {
|
|
*ret = aux;
|
|
return 0;
|
|
}
|
|
|
|
r = dns_transaction_find_cyclic(t, aux);
|
|
if (r < 0)
|
|
return r;
|
|
if (r > 0) {
|
|
log_debug("Detected potential cyclic dependency, refusing to add transaction %" PRIu16 " (%s) as dependency for %" PRIu16 " (%s).",
|
|
aux->id,
|
|
strna(dns_transaction_key_string(aux)),
|
|
t->id,
|
|
strna(dns_transaction_key_string(t)));
|
|
return -ELOOP;
|
|
}
|
|
}
|
|
|
|
r = set_ensure_allocated(&t->dnssec_transactions, NULL);
|
|
if (r < 0)
|
|
goto gc;
|
|
|
|
r = set_ensure_allocated(&aux->notify_transactions, NULL);
|
|
if (r < 0)
|
|
goto gc;
|
|
|
|
r = set_put(t->dnssec_transactions, aux);
|
|
if (r < 0)
|
|
goto gc;
|
|
|
|
r = set_put(aux->notify_transactions, t);
|
|
if (r < 0) {
|
|
(void) set_remove(t->dnssec_transactions, aux);
|
|
goto gc;
|
|
}
|
|
|
|
*ret = aux;
|
|
return 1;
|
|
|
|
gc:
|
|
dns_transaction_gc(aux);
|
|
return r;
|
|
}
|
|
|
|
static int dns_transaction_request_dnssec_rr(DnsTransaction *t, DnsResourceKey *key) {
|
|
_cleanup_(dns_answer_unrefp) DnsAnswer *a = NULL;
|
|
DnsTransaction *aux;
|
|
int r;
|
|
|
|
assert(t);
|
|
assert(key);
|
|
|
|
/* Try to get the data from the trust anchor */
|
|
r = dns_trust_anchor_lookup_positive(&t->scope->manager->trust_anchor, key, &a);
|
|
if (r < 0)
|
|
return r;
|
|
if (r > 0) {
|
|
r = dns_answer_extend(&t->validated_keys, a);
|
|
if (r < 0)
|
|
return r;
|
|
|
|
return 0;
|
|
}
|
|
|
|
/* This didn't work, ask for it via the network/cache then. */
|
|
r = dns_transaction_add_dnssec_transaction(t, key, &aux);
|
|
if (r == -ELOOP) /* This would result in a cyclic dependency */
|
|
return 0;
|
|
if (r < 0)
|
|
return r;
|
|
|
|
if (aux->state == DNS_TRANSACTION_NULL) {
|
|
r = dns_transaction_go(aux);
|
|
if (r < 0)
|
|
return r;
|
|
}
|
|
|
|
return 1;
|
|
}
|
|
|
|
static int dns_transaction_has_positive_answer(DnsTransaction *t, DnsAnswerFlags *flags) {
|
|
int r;
|
|
|
|
assert(t);
|
|
|
|
/* Checks whether the answer is positive, i.e. either a direct
|
|
* answer to the question, or a CNAME/DNAME for it */
|
|
|
|
r = dns_answer_match_key(t->answer, t->key, flags);
|
|
if (r != 0)
|
|
return r;
|
|
|
|
r = dns_answer_find_cname_or_dname(t->answer, t->key, NULL, flags);
|
|
if (r != 0)
|
|
return r;
|
|
|
|
return false;
|
|
}
|
|
|
|
static int dns_transaction_negative_trust_anchor_lookup(DnsTransaction *t, const char *name) {
|
|
int r;
|
|
|
|
assert(t);
|
|
|
|
/* Check whether the specified name is in the the NTA
|
|
* database, either in the global one, or the link-local
|
|
* one. */
|
|
|
|
r = dns_trust_anchor_lookup_negative(&t->scope->manager->trust_anchor, name);
|
|
if (r != 0)
|
|
return r;
|
|
|
|
if (!t->scope->link)
|
|
return 0;
|
|
|
|
return set_contains(t->scope->link->dnssec_negative_trust_anchors, name);
|
|
}
|
|
|
|
static int dns_transaction_has_unsigned_negative_answer(DnsTransaction *t) {
|
|
int r;
|
|
|
|
assert(t);
|
|
|
|
/* Checks whether the answer is negative, and lacks NSEC/NSEC3
|
|
* RRs to prove it */
|
|
|
|
r = dns_transaction_has_positive_answer(t, NULL);
|
|
if (r < 0)
|
|
return r;
|
|
if (r > 0)
|
|
return false;
|
|
|
|
/* Is this key explicitly listed as a negative trust anchor?
|
|
* If so, it's nothing we need to care about */
|
|
r = dns_transaction_negative_trust_anchor_lookup(t, DNS_RESOURCE_KEY_NAME(t->key));
|
|
if (r < 0)
|
|
return r;
|
|
if (r > 0)
|
|
return false;
|
|
|
|
/* The answer does not contain any RRs that match to the
|
|
* question. If so, let's see if there are any NSEC/NSEC3 RRs
|
|
* included. If not, the answer is unsigned. */
|
|
|
|
r = dns_answer_contains_nsec_or_nsec3(t->answer);
|
|
if (r < 0)
|
|
return r;
|
|
if (r > 0)
|
|
return false;
|
|
|
|
return true;
|
|
}
|
|
|
|
static int dns_transaction_is_primary_response(DnsTransaction *t, DnsResourceRecord *rr) {
|
|
int r;
|
|
|
|
assert(t);
|
|
assert(rr);
|
|
|
|
/* Check if the specified RR is the "primary" response,
|
|
* i.e. either matches the question precisely or is a
|
|
* CNAME/DNAME for it, or is any kind of NSEC/NSEC3 RR */
|
|
|
|
r = dns_resource_key_match_rr(t->key, rr, NULL);
|
|
if (r != 0)
|
|
return r;
|
|
|
|
r = dns_resource_key_match_cname_or_dname(t->key, rr->key, NULL);
|
|
if (r != 0)
|
|
return r;
|
|
|
|
if (rr->key->type == DNS_TYPE_NSEC3) {
|
|
const char *p;
|
|
|
|
p = DNS_RESOURCE_KEY_NAME(rr->key);
|
|
r = dns_name_parent(&p);
|
|
if (r < 0)
|
|
return r;
|
|
if (r > 0) {
|
|
r = dns_name_endswith(DNS_RESOURCE_KEY_NAME(t->key), p);
|
|
if (r < 0)
|
|
return r;
|
|
if (r > 0)
|
|
return true;
|
|
}
|
|
}
|
|
|
|
return rr->key->type == DNS_TYPE_NSEC;
|
|
}
|
|
|
|
int dns_transaction_request_dnssec_keys(DnsTransaction *t) {
|
|
DnsResourceRecord *rr;
|
|
|
|
int r;
|
|
|
|
assert(t);
|
|
|
|
/*
|
|
* Retrieve all auxiliary RRs for the answer we got, so that
|
|
* we can verify signatures or prove that RRs are rightfully
|
|
* unsigned. Specifically:
|
|
*
|
|
* - For RRSIG we get the matching DNSKEY
|
|
* - For DNSKEY we get the matching DS
|
|
* - For unsigned SOA/NS we get the matching DS
|
|
* - For unsigned CNAME/DNAME/DS we get the parent SOA RR
|
|
* - For other unsigned RRs we get the matching SOA RR
|
|
* - For SOA/NS/DS queries with no matching response RRs, and no NSEC/NSEC3, the parent's SOA RR
|
|
* - For other queries with no matching response RRs, and no NSEC/NSEC3, the SOA RR
|
|
*/
|
|
|
|
if (t->scope->dnssec_mode == DNSSEC_NO)
|
|
return 0;
|
|
|
|
if (t->current_features < DNS_SERVER_FEATURE_LEVEL_DO)
|
|
return 0; /* Server doesn't do DNSSEC, there's no point in requesting any RRs then. */
|
|
if (t->server && t->server->rrsig_missing)
|
|
return 0; /* Server handles DNSSEC requests, but isn't augmenting responses with RRSIGs. No point in trying DNSSEC then. */
|
|
|
|
DNS_ANSWER_FOREACH(rr, t->answer) {
|
|
|
|
if (dns_type_is_pseudo(rr->key->type))
|
|
continue;
|
|
|
|
/* If this RR is in the negative trust anchor, we don't need to validate it. */
|
|
r = dns_transaction_negative_trust_anchor_lookup(t, DNS_RESOURCE_KEY_NAME(rr->key));
|
|
if (r < 0)
|
|
return r;
|
|
if (r > 0)
|
|
continue;
|
|
|
|
switch (rr->key->type) {
|
|
|
|
case DNS_TYPE_RRSIG: {
|
|
/* For each RRSIG we request the matching DNSKEY */
|
|
_cleanup_(dns_resource_key_unrefp) DnsResourceKey *dnskey = NULL;
|
|
|
|
/* If this RRSIG is about a DNSKEY RR and the
|
|
* signer is the same as the owner, then we
|
|
* already have the DNSKEY, and we don't have
|
|
* to look for more. */
|
|
if (rr->rrsig.type_covered == DNS_TYPE_DNSKEY) {
|
|
r = dns_name_equal(rr->rrsig.signer, DNS_RESOURCE_KEY_NAME(rr->key));
|
|
if (r < 0)
|
|
return r;
|
|
if (r > 0)
|
|
continue;
|
|
}
|
|
|
|
/* If the signer is not a parent of our
|
|
* original query, then this is about an
|
|
* auxiliary RRset, but not anything we asked
|
|
* for. In this case we aren't interested,
|
|
* because we don't want to request additional
|
|
* RRs for stuff we didn't really ask for, and
|
|
* also to avoid request loops, where
|
|
* additional RRs from one transaction result
|
|
* in another transaction whose additonal RRs
|
|
* point back to the original transaction, and
|
|
* we deadlock. */
|
|
r = dns_name_endswith(DNS_RESOURCE_KEY_NAME(t->key), rr->rrsig.signer);
|
|
if (r < 0)
|
|
return r;
|
|
if (r == 0)
|
|
continue;
|
|
|
|
dnskey = dns_resource_key_new(rr->key->class, DNS_TYPE_DNSKEY, rr->rrsig.signer);
|
|
if (!dnskey)
|
|
return -ENOMEM;
|
|
|
|
log_debug("Requesting DNSKEY to validate transaction %" PRIu16" (%s, RRSIG with key tag: %" PRIu16 ").", t->id, DNS_RESOURCE_KEY_NAME(rr->key), rr->rrsig.key_tag);
|
|
r = dns_transaction_request_dnssec_rr(t, dnskey);
|
|
if (r < 0)
|
|
return r;
|
|
break;
|
|
}
|
|
|
|
case DNS_TYPE_DNSKEY: {
|
|
/* For each DNSKEY we request the matching DS */
|
|
_cleanup_(dns_resource_key_unrefp) DnsResourceKey *ds = NULL;
|
|
|
|
/* If the DNSKEY we are looking at is not for
|
|
* zone we are interested in, nor any of its
|
|
* parents, we aren't interested, and don't
|
|
* request it. After all, we don't want to end
|
|
* up in request loops, and want to keep
|
|
* additional traffic down. */
|
|
|
|
r = dns_name_endswith(DNS_RESOURCE_KEY_NAME(t->key), DNS_RESOURCE_KEY_NAME(rr->key));
|
|
if (r < 0)
|
|
return r;
|
|
if (r == 0)
|
|
continue;
|
|
|
|
ds = dns_resource_key_new(rr->key->class, DNS_TYPE_DS, DNS_RESOURCE_KEY_NAME(rr->key));
|
|
if (!ds)
|
|
return -ENOMEM;
|
|
|
|
log_debug("Requesting DS to validate transaction %" PRIu16" (%s, DNSKEY with key tag: %" PRIu16 ").", t->id, DNS_RESOURCE_KEY_NAME(rr->key), dnssec_keytag(rr, false));
|
|
r = dns_transaction_request_dnssec_rr(t, ds);
|
|
if (r < 0)
|
|
return r;
|
|
|
|
break;
|
|
}
|
|
|
|
case DNS_TYPE_SOA:
|
|
case DNS_TYPE_NS: {
|
|
_cleanup_(dns_resource_key_unrefp) DnsResourceKey *ds = NULL;
|
|
|
|
/* For an unsigned SOA or NS, try to acquire
|
|
* the matching DS RR, as we are at a zone cut
|
|
* then, and whether a DS exists tells us
|
|
* whether the zone is signed. Do so only if
|
|
* this RR matches our original question,
|
|
* however. */
|
|
|
|
r = dns_resource_key_match_rr(t->key, rr, NULL);
|
|
if (r < 0)
|
|
return r;
|
|
if (r == 0)
|
|
continue;
|
|
|
|
r = dnssec_has_rrsig(t->answer, rr->key);
|
|
if (r < 0)
|
|
return r;
|
|
if (r > 0)
|
|
continue;
|
|
|
|
ds = dns_resource_key_new(rr->key->class, DNS_TYPE_DS, DNS_RESOURCE_KEY_NAME(rr->key));
|
|
if (!ds)
|
|
return -ENOMEM;
|
|
|
|
log_debug("Requesting DS to validate transaction %" PRIu16 " (%s, unsigned SOA/NS RRset).", t->id, DNS_RESOURCE_KEY_NAME(rr->key));
|
|
r = dns_transaction_request_dnssec_rr(t, ds);
|
|
if (r < 0)
|
|
return r;
|
|
|
|
break;
|
|
}
|
|
|
|
case DNS_TYPE_DS:
|
|
case DNS_TYPE_CNAME:
|
|
case DNS_TYPE_DNAME: {
|
|
_cleanup_(dns_resource_key_unrefp) DnsResourceKey *soa = NULL;
|
|
const char *name;
|
|
|
|
/* CNAMEs and DNAMEs cannot be located at a
|
|
* zone apex, hence ask for the parent SOA for
|
|
* unsigned CNAME/DNAME RRs, maybe that's the
|
|
* apex. But do all that only if this is
|
|
* actually a response to our original
|
|
* question.
|
|
*
|
|
* Similar for DS RRs, which are signed when
|
|
* the parent SOA is signed. */
|
|
|
|
r = dns_transaction_is_primary_response(t, rr);
|
|
if (r < 0)
|
|
return r;
|
|
if (r == 0)
|
|
continue;
|
|
|
|
r = dnssec_has_rrsig(t->answer, rr->key);
|
|
if (r < 0)
|
|
return r;
|
|
if (r > 0)
|
|
continue;
|
|
|
|
name = DNS_RESOURCE_KEY_NAME(rr->key);
|
|
r = dns_name_parent(&name);
|
|
if (r < 0)
|
|
return r;
|
|
if (r == 0)
|
|
continue;
|
|
|
|
soa = dns_resource_key_new(rr->key->class, DNS_TYPE_SOA, name);
|
|
if (!soa)
|
|
return -ENOMEM;
|
|
|
|
log_debug("Requesting parent SOA to validate transaction %" PRIu16 " (%s, unsigned CNAME/DNAME/DS RRset).", t->id, DNS_RESOURCE_KEY_NAME(rr->key));
|
|
r = dns_transaction_request_dnssec_rr(t, soa);
|
|
if (r < 0)
|
|
return r;
|
|
|
|
break;
|
|
}
|
|
|
|
default: {
|
|
_cleanup_(dns_resource_key_unrefp) DnsResourceKey *soa = NULL;
|
|
|
|
/* For other unsigned RRsets (including
|
|
* NSEC/NSEC3!), look for proof the zone is
|
|
* unsigned, by requesting the SOA RR of the
|
|
* zone. However, do so only if they are
|
|
* directly relevant to our original
|
|
* question. */
|
|
|
|
r = dns_transaction_is_primary_response(t, rr);
|
|
if (r < 0)
|
|
return r;
|
|
if (r == 0)
|
|
continue;
|
|
|
|
r = dnssec_has_rrsig(t->answer, rr->key);
|
|
if (r < 0)
|
|
return r;
|
|
if (r > 0)
|
|
continue;
|
|
|
|
soa = dns_resource_key_new(rr->key->class, DNS_TYPE_SOA, DNS_RESOURCE_KEY_NAME(rr->key));
|
|
if (!soa)
|
|
return -ENOMEM;
|
|
|
|
log_debug("Requesting SOA to validate transaction %" PRIu16 " (%s, unsigned non-SOA/NS RRset <%s>).", t->id, DNS_RESOURCE_KEY_NAME(rr->key), dns_resource_record_to_string(rr));
|
|
r = dns_transaction_request_dnssec_rr(t, soa);
|
|
if (r < 0)
|
|
return r;
|
|
break;
|
|
}}
|
|
}
|
|
|
|
/* Above, we requested everything necessary to validate what
|
|
* we got. Now, let's request what we need to validate what we
|
|
* didn't get... */
|
|
|
|
r = dns_transaction_has_unsigned_negative_answer(t);
|
|
if (r < 0)
|
|
return r;
|
|
if (r > 0) {
|
|
const char *name;
|
|
|
|
name = DNS_RESOURCE_KEY_NAME(t->key);
|
|
|
|
/* If this was a SOA or NS request, then this
|
|
* indicates that we are not at a zone apex, hence ask
|
|
* the parent name instead. If this was a DS request,
|
|
* then it's signed when the parent zone is signed,
|
|
* hence ask the parent in that case, too. */
|
|
|
|
if (IN_SET(t->key->type, DNS_TYPE_SOA, DNS_TYPE_NS, DNS_TYPE_DS)) {
|
|
r = dns_name_parent(&name);
|
|
if (r < 0)
|
|
return r;
|
|
if (r > 0)
|
|
log_debug("Requesting parent SOA to validate transaction %" PRIu16 " (%s, unsigned empty SOA/NS/DS response).", t->id, DNS_RESOURCE_KEY_NAME(t->key));
|
|
else
|
|
name = NULL;
|
|
} else
|
|
log_debug("Requesting SOA to validate transaction %" PRIu16 " (%s, unsigned empty non-SOA/NS/DS response).", t->id, DNS_RESOURCE_KEY_NAME(t->key));
|
|
|
|
if (name) {
|
|
_cleanup_(dns_resource_key_unrefp) DnsResourceKey *soa = NULL;
|
|
|
|
soa = dns_resource_key_new(t->key->class, DNS_TYPE_SOA, name);
|
|
if (!soa)
|
|
return -ENOMEM;
|
|
|
|
r = dns_transaction_request_dnssec_rr(t, soa);
|
|
if (r < 0)
|
|
return r;
|
|
}
|
|
}
|
|
|
|
return dns_transaction_dnssec_is_live(t);
|
|
}
|
|
|
|
void dns_transaction_notify(DnsTransaction *t, DnsTransaction *source) {
|
|
int r;
|
|
|
|
assert(t);
|
|
assert(source);
|
|
|
|
if (!IN_SET(t->state, DNS_TRANSACTION_PENDING, DNS_TRANSACTION_VALIDATING))
|
|
return;
|
|
|
|
/* Invoked whenever any of our auxiliary DNSSEC transactions
|
|
completed its work. We copy any RRs from that transaction
|
|
over into our list of validated keys -- but only if the
|
|
answer is authenticated.
|
|
|
|
Note that we fail our transaction if the auxiliary
|
|
transaction failed, except on NXDOMAIN. This is because
|
|
some broken DNS servers (Akamai...) will return NXDOMAIN
|
|
for empty non-terminals. */
|
|
|
|
switch (source->state) {
|
|
|
|
case DNS_TRANSACTION_DNSSEC_FAILED:
|
|
|
|
log_debug("Auxiliary DNSSEC RR query failed validation: %s", dnssec_result_to_string(source->answer_dnssec_result));
|
|
t->answer_dnssec_result = source->answer_dnssec_result; /* Copy error code over */
|
|
dns_transaction_complete(t, DNS_TRANSACTION_DNSSEC_FAILED);
|
|
break;
|
|
|
|
case DNS_TRANSACTION_RCODE_FAILURE:
|
|
|
|
if (source->answer_rcode != DNS_RCODE_NXDOMAIN) {
|
|
log_debug("Auxiliary DNSSEC RR query failed with rcode=%i.", source->answer_rcode);
|
|
goto fail;
|
|
}
|
|
|
|
/* fall-through: NXDOMAIN is good enough for us */
|
|
|
|
case DNS_TRANSACTION_SUCCESS:
|
|
if (source->answer_authenticated) {
|
|
r = dns_answer_extend(&t->validated_keys, source->answer);
|
|
if (r < 0) {
|
|
log_error_errno(r, "Failed to merge validated DNSSEC key data: %m");
|
|
goto fail;
|
|
}
|
|
}
|
|
|
|
/* If the state is still PENDING, we are still in the loop
|
|
* that adds further DNSSEC transactions, hence don't check if
|
|
* we are ready yet. If the state is VALIDATING however, we
|
|
* should check if we are complete now. */
|
|
if (t->state == DNS_TRANSACTION_VALIDATING)
|
|
dns_transaction_process_dnssec(t);
|
|
break;
|
|
|
|
default:
|
|
log_debug("Auxiliary DNSSEC RR query failed with %s", dns_transaction_state_to_string(source->state));
|
|
goto fail;
|
|
}
|
|
|
|
return;
|
|
|
|
fail:
|
|
t->answer_dnssec_result = DNSSEC_FAILED_AUXILIARY;
|
|
dns_transaction_complete(t, DNS_TRANSACTION_DNSSEC_FAILED);
|
|
}
|
|
|
|
static int dns_transaction_validate_dnskey_by_ds(DnsTransaction *t) {
|
|
DnsResourceRecord *rr;
|
|
int ifindex, r;
|
|
|
|
assert(t);
|
|
|
|
/* Add all DNSKEY RRs from the answer that are validated by DS
|
|
* RRs from the list of validated keys to the list of
|
|
* validated keys. */
|
|
|
|
DNS_ANSWER_FOREACH_IFINDEX(rr, ifindex, t->answer) {
|
|
|
|
r = dnssec_verify_dnskey_search(rr, t->validated_keys);
|
|
if (r < 0)
|
|
return r;
|
|
if (r == 0)
|
|
continue;
|
|
|
|
/* If so, the DNSKEY is validated too. */
|
|
r = dns_answer_add_extend(&t->validated_keys, rr, ifindex, DNS_ANSWER_AUTHENTICATED);
|
|
if (r < 0)
|
|
return r;
|
|
}
|
|
|
|
return 0;
|
|
}
|
|
|
|
static int dns_transaction_requires_rrsig(DnsTransaction *t, DnsResourceRecord *rr) {
|
|
int r;
|
|
|
|
assert(t);
|
|
assert(rr);
|
|
|
|
/* Checks if the RR we are looking for must be signed with an
|
|
* RRSIG. This is used for positive responses. */
|
|
|
|
if (t->scope->dnssec_mode == DNSSEC_NO)
|
|
return false;
|
|
|
|
if (dns_type_is_pseudo(rr->key->type))
|
|
return -EINVAL;
|
|
|
|
r = dns_transaction_negative_trust_anchor_lookup(t, DNS_RESOURCE_KEY_NAME(rr->key));
|
|
if (r < 0)
|
|
return r;
|
|
if (r > 0)
|
|
return false;
|
|
|
|
switch (rr->key->type) {
|
|
|
|
case DNS_TYPE_RRSIG:
|
|
/* RRSIGs are the signatures themselves, they need no signing. */
|
|
return false;
|
|
|
|
case DNS_TYPE_SOA:
|
|
case DNS_TYPE_NS: {
|
|
DnsTransaction *dt;
|
|
Iterator i;
|
|
|
|
/* For SOA or NS RRs we look for a matching DS transaction */
|
|
|
|
SET_FOREACH(dt, t->dnssec_transactions, i) {
|
|
|
|
if (dt->key->class != rr->key->class)
|
|
continue;
|
|
if (dt->key->type != DNS_TYPE_DS)
|
|
continue;
|
|
|
|
r = dns_name_equal(DNS_RESOURCE_KEY_NAME(dt->key), DNS_RESOURCE_KEY_NAME(rr->key));
|
|
if (r < 0)
|
|
return r;
|
|
if (r == 0)
|
|
continue;
|
|
|
|
/* We found a DS transactions for the SOA/NS
|
|
* RRs we are looking at. If it discovered signed DS
|
|
* RRs, then we need to be signed, too. */
|
|
|
|
if (!dt->answer_authenticated)
|
|
return false;
|
|
|
|
return dns_answer_match_key(dt->answer, dt->key, NULL);
|
|
}
|
|
|
|
/* We found nothing that proves this is safe to leave
|
|
* this unauthenticated, hence ask inist on
|
|
* authentication. */
|
|
return true;
|
|
}
|
|
|
|
case DNS_TYPE_DS:
|
|
case DNS_TYPE_CNAME:
|
|
case DNS_TYPE_DNAME: {
|
|
const char *parent = NULL;
|
|
DnsTransaction *dt;
|
|
Iterator i;
|
|
|
|
/*
|
|
* CNAME/DNAME RRs cannot be located at a zone apex, hence look directly for the parent SOA.
|
|
*
|
|
* DS RRs are signed if the parent is signed, hence also look at the parent SOA
|
|
*/
|
|
|
|
SET_FOREACH(dt, t->dnssec_transactions, i) {
|
|
|
|
if (dt->key->class != rr->key->class)
|
|
continue;
|
|
if (dt->key->type != DNS_TYPE_SOA)
|
|
continue;
|
|
|
|
if (!parent) {
|
|
parent = DNS_RESOURCE_KEY_NAME(rr->key);
|
|
r = dns_name_parent(&parent);
|
|
if (r < 0)
|
|
return r;
|
|
if (r == 0) {
|
|
if (rr->key->type == DNS_TYPE_DS)
|
|
return true;
|
|
|
|
/* A CNAME/DNAME without a parent? That's sooo weird. */
|
|
log_debug("Transaction %" PRIu16 " claims CNAME/DNAME at root. Refusing.", t->id);
|
|
return -EBADMSG;
|
|
}
|
|
}
|
|
|
|
r = dns_name_equal(DNS_RESOURCE_KEY_NAME(dt->key), parent);
|
|
if (r < 0)
|
|
return r;
|
|
if (r == 0)
|
|
continue;
|
|
|
|
return t->answer_authenticated;
|
|
}
|
|
|
|
return true;
|
|
}
|
|
|
|
default: {
|
|
DnsTransaction *dt;
|
|
Iterator i;
|
|
|
|
/* Any other kind of RR (including DNSKEY/NSEC/NSEC3). Let's see if our SOA lookup was authenticated */
|
|
|
|
SET_FOREACH(dt, t->dnssec_transactions, i) {
|
|
|
|
if (dt->key->class != rr->key->class)
|
|
continue;
|
|
if (dt->key->type != DNS_TYPE_SOA)
|
|
continue;
|
|
|
|
r = dns_name_equal(DNS_RESOURCE_KEY_NAME(dt->key), DNS_RESOURCE_KEY_NAME(rr->key));
|
|
if (r < 0)
|
|
return r;
|
|
if (r == 0)
|
|
continue;
|
|
|
|
/* We found the transaction that was supposed to find
|
|
* the SOA RR for us. It was successful, but found no
|
|
* RR for us. This means we are not at a zone cut. In
|
|
* this case, we require authentication if the SOA
|
|
* lookup was authenticated too. */
|
|
return t->answer_authenticated;
|
|
}
|
|
|
|
return true;
|
|
}}
|
|
}
|
|
|
|
static int dns_transaction_in_private_tld(DnsTransaction *t, const DnsResourceKey *key) {
|
|
DnsTransaction *dt;
|
|
const char *tld;
|
|
Iterator i;
|
|
int r;
|
|
|
|
/* If DNSSEC downgrade mode is on, checks whether the
|
|
* specified RR is one level below a TLD we have proven not to
|
|
* exist. In such a case we assume that this is a private
|
|
* domain, and permit it.
|
|
*
|
|
* This detects cases like the Fritz!Box router networks. Each
|
|
* Fritz!Box router serves a private "fritz.box" zone, in the
|
|
* non-existing TLD "box". Requests for the "fritz.box" domain
|
|
* are served by the router itself, while requests for the
|
|
* "box" domain will result in NXDOMAIN.
|
|
*
|
|
* Note that this logic is unable to detect cases where a
|
|
* router serves a private DNS zone directly under
|
|
* non-existing TLD. In such a case we cannot detect whether
|
|
* the TLD is supposed to exist or not, as all requests we
|
|
* make for it will be answered by the router's zone, and not
|
|
* by the root zone. */
|
|
|
|
assert(t);
|
|
|
|
if (t->scope->dnssec_mode != DNSSEC_ALLOW_DOWNGRADE)
|
|
return false; /* In strict DNSSEC mode what doesn't exist, doesn't exist */
|
|
|
|
tld = DNS_RESOURCE_KEY_NAME(key);
|
|
r = dns_name_parent(&tld);
|
|
if (r < 0)
|
|
return r;
|
|
if (r == 0)
|
|
return false; /* Already the root domain */
|
|
|
|
if (!dns_name_is_single_label(tld))
|
|
return false;
|
|
|
|
SET_FOREACH(dt, t->dnssec_transactions, i) {
|
|
|
|
if (dt->key->class != key->class)
|
|
continue;
|
|
|
|
r = dns_name_equal(DNS_RESOURCE_KEY_NAME(dt->key), tld);
|
|
if (r < 0)
|
|
return r;
|
|
if (r == 0)
|
|
continue;
|
|
|
|
/* We found an auxiliary lookup we did for the TLD. If
|
|
* that returned with NXDOMAIN, we know the TLD didn't
|
|
* exist, and hence this might be a private zone. */
|
|
|
|
return dt->answer_rcode == DNS_RCODE_NXDOMAIN;
|
|
}
|
|
|
|
return false;
|
|
}
|
|
|
|
static int dns_transaction_requires_nsec(DnsTransaction *t) {
|
|
DnsTransaction *dt;
|
|
const char *name;
|
|
Iterator i;
|
|
int r;
|
|
|
|
assert(t);
|
|
|
|
/* Checks if we need to insist on NSEC/NSEC3 RRs for proving
|
|
* this negative reply */
|
|
|
|
if (t->scope->dnssec_mode == DNSSEC_NO)
|
|
return false;
|
|
|
|
if (dns_type_is_pseudo(t->key->type))
|
|
return -EINVAL;
|
|
|
|
r = dns_transaction_negative_trust_anchor_lookup(t, DNS_RESOURCE_KEY_NAME(t->key));
|
|
if (r < 0)
|
|
return r;
|
|
if (r > 0)
|
|
return false;
|
|
|
|
r = dns_transaction_in_private_tld(t, t->key);
|
|
if (r < 0)
|
|
return r;
|
|
if (r > 0) {
|
|
/* The lookup is from a TLD that is proven not to
|
|
* exist, and we are in downgrade mode, hence ignore
|
|
* that fact that we didn't get any NSEC RRs.*/
|
|
|
|
log_info("Detected a negative query %s in a private DNS zone, permitting unsigned response.", dns_transaction_key_string(t));
|
|
return false;
|
|
}
|
|
|
|
name = DNS_RESOURCE_KEY_NAME(t->key);
|
|
|
|
if (IN_SET(t->key->type, DNS_TYPE_SOA, DNS_TYPE_NS, DNS_TYPE_DS)) {
|
|
|
|
/* We got a negative reply for this SOA/NS lookup? If
|
|
* so, then we are not at a zone apex, and thus should
|
|
* look at the result of the parent SOA lookup.
|
|
*
|
|
* We got a negative reply for this DS lookup? DS RRs
|
|
* are signed when their parent zone is signed, hence
|
|
* also check the parent SOA in this case. */
|
|
|
|
r = dns_name_parent(&name);
|
|
if (r < 0)
|
|
return r;
|
|
if (r == 0)
|
|
return true;
|
|
}
|
|
|
|
/* For all other RRs we check the SOA on the same level to see
|
|
* if it's signed. */
|
|
|
|
SET_FOREACH(dt, t->dnssec_transactions, i) {
|
|
|
|
if (dt->key->class != t->key->class)
|
|
continue;
|
|
if (dt->key->type != DNS_TYPE_SOA)
|
|
continue;
|
|
|
|
r = dns_name_equal(DNS_RESOURCE_KEY_NAME(dt->key), name);
|
|
if (r < 0)
|
|
return r;
|
|
if (r == 0)
|
|
continue;
|
|
|
|
return dt->answer_authenticated;
|
|
}
|
|
|
|
/* If in doubt, require NSEC/NSEC3 */
|
|
return true;
|
|
}
|
|
|
|
static int dns_transaction_dnskey_authenticated(DnsTransaction *t, DnsResourceRecord *rr) {
|
|
DnsResourceRecord *rrsig;
|
|
bool found = false;
|
|
int r;
|
|
|
|
/* Checks whether any of the DNSKEYs used for the RRSIGs for
|
|
* the specified RRset is authenticated (i.e. has a matching
|
|
* DS RR). */
|
|
|
|
r = dns_transaction_negative_trust_anchor_lookup(t, DNS_RESOURCE_KEY_NAME(rr->key));
|
|
if (r < 0)
|
|
return r;
|
|
if (r > 0)
|
|
return false;
|
|
|
|
DNS_ANSWER_FOREACH(rrsig, t->answer) {
|
|
DnsTransaction *dt;
|
|
Iterator i;
|
|
|
|
r = dnssec_key_match_rrsig(rr->key, rrsig);
|
|
if (r < 0)
|
|
return r;
|
|
if (r == 0)
|
|
continue;
|
|
|
|
SET_FOREACH(dt, t->dnssec_transactions, i) {
|
|
|
|
if (dt->key->class != rr->key->class)
|
|
continue;
|
|
|
|
if (dt->key->type == DNS_TYPE_DNSKEY) {
|
|
|
|
r = dns_name_equal(DNS_RESOURCE_KEY_NAME(dt->key), rrsig->rrsig.signer);
|
|
if (r < 0)
|
|
return r;
|
|
if (r == 0)
|
|
continue;
|
|
|
|
/* OK, we found an auxiliary DNSKEY
|
|
* lookup. If that lookup is
|
|
* authenticated, report this. */
|
|
|
|
if (dt->answer_authenticated)
|
|
return true;
|
|
|
|
found = true;
|
|
|
|
} else if (dt->key->type == DNS_TYPE_DS) {
|
|
|
|
r = dns_name_equal(DNS_RESOURCE_KEY_NAME(dt->key), rrsig->rrsig.signer);
|
|
if (r < 0)
|
|
return r;
|
|
if (r == 0)
|
|
continue;
|
|
|
|
/* OK, we found an auxiliary DS
|
|
* lookup. If that lookup is
|
|
* authenticated and non-zero, we
|
|
* won! */
|
|
|
|
if (!dt->answer_authenticated)
|
|
return false;
|
|
|
|
return dns_answer_match_key(dt->answer, dt->key, NULL);
|
|
}
|
|
}
|
|
}
|
|
|
|
return found ? false : -ENXIO;
|
|
}
|
|
|
|
static int dns_transaction_known_signed(DnsTransaction *t, DnsResourceRecord *rr) {
|
|
assert(t);
|
|
assert(rr);
|
|
|
|
/* We know that the root domain is signed, hence if it appears
|
|
* not to be signed, there's a problem with the DNS server */
|
|
|
|
return rr->key->class == DNS_CLASS_IN &&
|
|
dns_name_is_root(DNS_RESOURCE_KEY_NAME(rr->key));
|
|
}
|
|
|
|
int dns_transaction_validate_dnssec(DnsTransaction *t) {
|
|
_cleanup_(dns_answer_unrefp) DnsAnswer *validated = NULL;
|
|
bool dnskeys_finalized = false;
|
|
DnsResourceRecord *rr;
|
|
DnsAnswerFlags flags;
|
|
int r;
|
|
|
|
assert(t);
|
|
|
|
/* We have now collected all DS and DNSKEY RRs in
|
|
* t->validated_keys, let's see which RRs we can now
|
|
* authenticate with that. */
|
|
|
|
if (t->scope->dnssec_mode == DNSSEC_NO)
|
|
return 0;
|
|
|
|
/* Already validated */
|
|
if (t->answer_dnssec_result != _DNSSEC_RESULT_INVALID)
|
|
return 0;
|
|
|
|
/* Our own stuff needs no validation */
|
|
if (IN_SET(t->answer_source, DNS_TRANSACTION_ZONE, DNS_TRANSACTION_TRUST_ANCHOR)) {
|
|
t->answer_dnssec_result = DNSSEC_VALIDATED;
|
|
t->answer_authenticated = true;
|
|
return 0;
|
|
}
|
|
|
|
/* Cached stuff is not affected by validation. */
|
|
if (t->answer_source != DNS_TRANSACTION_NETWORK)
|
|
return 0;
|
|
|
|
if (t->current_features < DNS_SERVER_FEATURE_LEVEL_DO ||
|
|
(t->server && t->server->rrsig_missing)) {
|
|
/* The server does not support DNSSEC, or doesn't augment responses with RRSIGs. */
|
|
t->answer_dnssec_result = DNSSEC_INCOMPATIBLE_SERVER;
|
|
return 0;
|
|
}
|
|
|
|
log_debug("Validating response from transaction %" PRIu16 " (%s).", t->id, dns_transaction_key_string(t));
|
|
|
|
/* First see if there are DNSKEYs we already known a validated DS for. */
|
|
r = dns_transaction_validate_dnskey_by_ds(t);
|
|
if (r < 0)
|
|
return r;
|
|
|
|
for (;;) {
|
|
bool changed = false;
|
|
|
|
DNS_ANSWER_FOREACH(rr, t->answer) {
|
|
DnssecResult result;
|
|
|
|
if (rr->key->type == DNS_TYPE_RRSIG)
|
|
continue;
|
|
|
|
r = dnssec_verify_rrset_search(t->answer, rr->key, t->validated_keys, USEC_INFINITY, &result);
|
|
if (r < 0)
|
|
return r;
|
|
|
|
log_debug("Looking at %s: %s", strna(dns_resource_record_to_string(rr)), dnssec_result_to_string(result));
|
|
|
|
if (result == DNSSEC_VALIDATED) {
|
|
|
|
if (rr->key->type == DNS_TYPE_DNSKEY) {
|
|
/* If we just validated a
|
|
* DNSKEY RRset, then let's
|
|
* add these keys to the set
|
|
* of validated keys for this
|
|
* transaction. */
|
|
|
|
r = dns_answer_copy_by_key(&t->validated_keys, t->answer, rr->key, DNS_ANSWER_AUTHENTICATED);
|
|
if (r < 0)
|
|
return r;
|
|
|
|
/* Maybe warn the user that we
|
|
* encountered a revoked
|
|
* DNSKEY for a key from our
|
|
* trust anchor */
|
|
r = dns_trust_anchor_check_revoked(&t->scope->manager->trust_anchor, t->answer, rr->key);
|
|
if (r < 0)
|
|
return r;
|
|
}
|
|
|
|
/* Add the validated RRset to the new
|
|
* list of validated RRsets, and
|
|
* remove it from the unvalidated
|
|
* RRsets. We mark the RRset as
|
|
* authenticated and cacheable. */
|
|
r = dns_answer_move_by_key(&validated, &t->answer, rr->key, DNS_ANSWER_AUTHENTICATED|DNS_ANSWER_CACHEABLE);
|
|
if (r < 0)
|
|
return r;
|
|
|
|
t->scope->manager->n_dnssec_secure++;
|
|
|
|
/* Exit the loop, we dropped something from the answer, start from the beginning */
|
|
changed = true;
|
|
break;
|
|
|
|
} else if (dnskeys_finalized) {
|
|
|
|
/* If we haven't read all DNSKEYs yet
|
|
* a negative result of the validation
|
|
* is irrelevant, as there might be
|
|
* more DNSKEYs coming. */
|
|
|
|
if (result == DNSSEC_NO_SIGNATURE) {
|
|
r = dns_transaction_requires_rrsig(t, rr);
|
|
if (r < 0)
|
|
return r;
|
|
if (r == 0) {
|
|
/* Data does not require signing. In that case, just copy it over,
|
|
* but remember that this is by no means authenticated.*/
|
|
r = dns_answer_move_by_key(&validated, &t->answer, rr->key, 0);
|
|
if (r < 0)
|
|
return r;
|
|
|
|
t->scope->manager->n_dnssec_insecure++;
|
|
|
|
changed = true;
|
|
break;
|
|
}
|
|
|
|
r = dns_transaction_known_signed(t, rr);
|
|
if (r < 0)
|
|
return r;
|
|
if (r > 0) {
|
|
/* This is an RR we know has to be signed. If it isn't this means
|
|
* the server is not attaching RRSIGs, hence complain. */
|
|
|
|
dns_server_packet_rrsig_missing(t->server);
|
|
|
|
if (t->scope->dnssec_mode == DNSSEC_ALLOW_DOWNGRADE) {
|
|
|
|
/* Downgrading is OK? If so, just consider the information unsigned */
|
|
|
|
r = dns_answer_move_by_key(&validated, &t->answer, rr->key, 0);
|
|
if (r < 0)
|
|
return r;
|
|
|
|
t->scope->manager->n_dnssec_insecure++;
|
|
changed = true;
|
|
break;
|
|
}
|
|
|
|
/* Otherwise, fail */
|
|
t->answer_dnssec_result = DNSSEC_INCOMPATIBLE_SERVER;
|
|
return 0;
|
|
}
|
|
|
|
r = dns_transaction_in_private_tld(t, rr->key);
|
|
if (r < 0)
|
|
return r;
|
|
if (r > 0) {
|
|
_cleanup_free_ char *s = NULL;
|
|
|
|
/* The data is from a TLD that is proven not to exist, and we are in downgrade
|
|
* mode, hence ignore the fact that this was not signed. */
|
|
|
|
(void) dns_resource_key_to_string(rr->key, &s);
|
|
log_info("Detected RRset %s is in a private DNS zone, permitting unsigned RRs.", strna(s ? strstrip(s) : NULL));
|
|
|
|
r = dns_answer_move_by_key(&validated, &t->answer, rr->key, 0);
|
|
if (r < 0)
|
|
return r;
|
|
|
|
t->scope->manager->n_dnssec_insecure++;
|
|
changed = true;
|
|
break;
|
|
}
|
|
}
|
|
|
|
if (IN_SET(result,
|
|
DNSSEC_MISSING_KEY,
|
|
DNSSEC_SIGNATURE_EXPIRED,
|
|
DNSSEC_UNSUPPORTED_ALGORITHM)) {
|
|
|
|
r = dns_transaction_dnskey_authenticated(t, rr);
|
|
if (r < 0 && r != -ENXIO)
|
|
return r;
|
|
if (r == 0) {
|
|
/* The DNSKEY transaction was not authenticated, this means there's
|
|
* no DS for this, which means it's OK if no keys are found for this signature. */
|
|
|
|
r = dns_answer_move_by_key(&validated, &t->answer, rr->key, 0);
|
|
if (r < 0)
|
|
return r;
|
|
|
|
t->scope->manager->n_dnssec_insecure++;
|
|
|
|
changed = true;
|
|
break;
|
|
}
|
|
}
|
|
|
|
if (IN_SET(result,
|
|
DNSSEC_INVALID,
|
|
DNSSEC_SIGNATURE_EXPIRED,
|
|
DNSSEC_NO_SIGNATURE))
|
|
t->scope->manager->n_dnssec_bogus++;
|
|
else /* DNSSEC_MISSING_KEY or DNSSEC_UNSUPPORTED_ALGORITHM */
|
|
t->scope->manager->n_dnssec_indeterminate++;
|
|
|
|
r = dns_transaction_is_primary_response(t, rr);
|
|
if (r < 0)
|
|
return r;
|
|
if (r > 0) {
|
|
/* This is a primary response
|
|
* to our question, and it
|
|
* failed validation. That's
|
|
* fatal. */
|
|
t->answer_dnssec_result = result;
|
|
return 0;
|
|
}
|
|
|
|
/* This is just some auxiliary
|
|
* data. Just remove the RRset and
|
|
* continue. */
|
|
r = dns_answer_remove_by_key(&t->answer, rr->key);
|
|
if (r < 0)
|
|
return r;
|
|
|
|
/* Exit the loop, we dropped something from the answer, start from the beginning */
|
|
changed = true;
|
|
break;
|
|
}
|
|
}
|
|
|
|
if (changed)
|
|
continue;
|
|
|
|
if (!dnskeys_finalized) {
|
|
/* OK, now we know we have added all DNSKEYs
|
|
* we possibly could to our validated
|
|
* list. Now run the whole thing once more,
|
|
* and strip everything we still cannot
|
|
* validate.
|
|
*/
|
|
dnskeys_finalized = true;
|
|
continue;
|
|
}
|
|
|
|
/* We're done */
|
|
break;
|
|
}
|
|
|
|
dns_answer_unref(t->answer);
|
|
t->answer = validated;
|
|
validated = NULL;
|
|
|
|
/* At this point the answer only contains validated
|
|
* RRsets. Now, let's see if it actually answers the question
|
|
* we asked. If so, great! If it doesn't, then see if
|
|
* NSEC/NSEC3 can prove this. */
|
|
r = dns_transaction_has_positive_answer(t, &flags);
|
|
if (r > 0) {
|
|
/* Yes, it answers the question! */
|
|
|
|
if (flags & DNS_ANSWER_AUTHENTICATED) {
|
|
/* The answer is fully authenticated, yay. */
|
|
t->answer_dnssec_result = DNSSEC_VALIDATED;
|
|
t->answer_rcode = DNS_RCODE_SUCCESS;
|
|
t->answer_authenticated = true;
|
|
} else {
|
|
/* The answer is not fully authenticated. */
|
|
t->answer_dnssec_result = DNSSEC_UNSIGNED;
|
|
t->answer_authenticated = false;
|
|
}
|
|
|
|
} else if (r == 0) {
|
|
DnssecNsecResult nr;
|
|
bool authenticated = false;
|
|
|
|
/* Bummer! Let's check NSEC/NSEC3 */
|
|
r = dnssec_test_nsec(t->answer, t->key, &nr, &authenticated, &t->answer_nsec_ttl);
|
|
if (r < 0)
|
|
return r;
|
|
|
|
switch (nr) {
|
|
|
|
case DNSSEC_NSEC_NXDOMAIN:
|
|
/* NSEC proves the domain doesn't exist. Very good. */
|
|
log_debug("Proved NXDOMAIN via NSEC/NSEC3 for transaction %u (%s)", t->id, dns_transaction_key_string(t));
|
|
t->answer_dnssec_result = DNSSEC_VALIDATED;
|
|
t->answer_rcode = DNS_RCODE_NXDOMAIN;
|
|
t->answer_authenticated = authenticated;
|
|
break;
|
|
|
|
case DNSSEC_NSEC_NODATA:
|
|
/* NSEC proves that there's no data here, very good. */
|
|
log_debug("Proved NODATA via NSEC/NSEC3 for transaction %u (%s)", t->id, dns_transaction_key_string(t));
|
|
t->answer_dnssec_result = DNSSEC_VALIDATED;
|
|
t->answer_rcode = DNS_RCODE_SUCCESS;
|
|
t->answer_authenticated = authenticated;
|
|
break;
|
|
|
|
case DNSSEC_NSEC_OPTOUT:
|
|
/* NSEC3 says the data might not be signed */
|
|
log_debug("Data is NSEC3 opt-out via NSEC/NSEC3 for transaction %u (%s)", t->id, dns_transaction_key_string(t));
|
|
t->answer_dnssec_result = DNSSEC_UNSIGNED;
|
|
t->answer_authenticated = false;
|
|
break;
|
|
|
|
case DNSSEC_NSEC_NO_RR:
|
|
/* No NSEC data? Bummer! */
|
|
|
|
r = dns_transaction_requires_nsec(t);
|
|
if (r < 0)
|
|
return r;
|
|
if (r > 0)
|
|
t->answer_dnssec_result = DNSSEC_NO_SIGNATURE;
|
|
else {
|
|
t->answer_dnssec_result = DNSSEC_UNSIGNED;
|
|
t->answer_authenticated = false;
|
|
}
|
|
|
|
break;
|
|
|
|
case DNSSEC_NSEC_UNSUPPORTED_ALGORITHM:
|
|
/* We don't know the NSEC3 algorithm used? */
|
|
t->answer_dnssec_result = DNSSEC_UNSUPPORTED_ALGORITHM;
|
|
break;
|
|
|
|
case DNSSEC_NSEC_FOUND:
|
|
case DNSSEC_NSEC_CNAME:
|
|
/* NSEC says it needs to be there, but we couldn't find it? Bummer! */
|
|
t->answer_dnssec_result = DNSSEC_NSEC_MISMATCH;
|
|
break;
|
|
|
|
default:
|
|
assert_not_reached("Unexpected NSEC result.");
|
|
}
|
|
}
|
|
|
|
return 1;
|
|
}
|
|
|
|
const char *dns_transaction_key_string(DnsTransaction *t) {
|
|
assert(t);
|
|
|
|
if (!t->key_string) {
|
|
if (dns_resource_key_to_string(t->key, &t->key_string) < 0)
|
|
return "n/a";
|
|
}
|
|
|
|
return strstrip(t->key_string);
|
|
}
|
|
|
|
static const char* const dns_transaction_state_table[_DNS_TRANSACTION_STATE_MAX] = {
|
|
[DNS_TRANSACTION_NULL] = "null",
|
|
[DNS_TRANSACTION_PENDING] = "pending",
|
|
[DNS_TRANSACTION_VALIDATING] = "validating",
|
|
[DNS_TRANSACTION_RCODE_FAILURE] = "rcode-failure",
|
|
[DNS_TRANSACTION_SUCCESS] = "success",
|
|
[DNS_TRANSACTION_NO_SERVERS] = "no-servers",
|
|
[DNS_TRANSACTION_TIMEOUT] = "timeout",
|
|
[DNS_TRANSACTION_ATTEMPTS_MAX_REACHED] = "attempts-max-reached",
|
|
[DNS_TRANSACTION_INVALID_REPLY] = "invalid-reply",
|
|
[DNS_TRANSACTION_RESOURCES] = "resources",
|
|
[DNS_TRANSACTION_CONNECTION_FAILURE] = "connection-failure",
|
|
[DNS_TRANSACTION_ABORTED] = "aborted",
|
|
[DNS_TRANSACTION_DNSSEC_FAILED] = "dnssec-failed",
|
|
[DNS_TRANSACTION_NO_TRUST_ANCHOR] = "no-trust-anchor",
|
|
};
|
|
DEFINE_STRING_TABLE_LOOKUP(dns_transaction_state, DnsTransactionState);
|
|
|
|
static const char* const dns_transaction_source_table[_DNS_TRANSACTION_SOURCE_MAX] = {
|
|
[DNS_TRANSACTION_NETWORK] = "network",
|
|
[DNS_TRANSACTION_CACHE] = "cache",
|
|
[DNS_TRANSACTION_ZONE] = "zone",
|
|
[DNS_TRANSACTION_TRUST_ANCHOR] = "trust-anchor",
|
|
};
|
|
DEFINE_STRING_TABLE_LOOKUP(dns_transaction_source, DnsTransactionSource);
|