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diff --git a/src/grp-resolve/systemd-resolved/resolved-dns-transaction.h b/src/grp-resolve/systemd-resolved/resolved-dns-transaction.h
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+++ b/src/grp-resolve/systemd-resolved/resolved-dns-transaction.h
@@ -0,0 +1,177 @@
+#pragma once
+
+/***
+ This file is part of systemd.
+
+ Copyright 2014 Lennart Poettering
+
+ systemd is free software; you can redistribute it and/or modify it
+ under the terms of the GNU Lesser General Public License as published by
+ the Free Software Foundation; either version 2.1 of the License, or
+ (at your option) any later version.
+
+ systemd is distributed in the hope that it will be useful, but
+ WITHOUT ANY WARRANTY; without even the implied warranty of
+ MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
+ Lesser General Public License for more details.
+
+ You should have received a copy of the GNU Lesser General Public License
+ along with systemd; If not, see <http://www.gnu.org/licenses/>.
+***/
+
+typedef struct DnsTransaction DnsTransaction;
+typedef enum DnsTransactionState DnsTransactionState;
+typedef enum DnsTransactionSource DnsTransactionSource;
+
+enum DnsTransactionState {
+ DNS_TRANSACTION_NULL,
+ DNS_TRANSACTION_PENDING,
+ DNS_TRANSACTION_VALIDATING,
+ DNS_TRANSACTION_RCODE_FAILURE,
+ DNS_TRANSACTION_SUCCESS,
+ DNS_TRANSACTION_NO_SERVERS,
+ DNS_TRANSACTION_TIMEOUT,
+ DNS_TRANSACTION_ATTEMPTS_MAX_REACHED,
+ DNS_TRANSACTION_INVALID_REPLY,
+ DNS_TRANSACTION_ERRNO,
+ DNS_TRANSACTION_ABORTED,
+ DNS_TRANSACTION_DNSSEC_FAILED,
+ DNS_TRANSACTION_NO_TRUST_ANCHOR,
+ DNS_TRANSACTION_RR_TYPE_UNSUPPORTED,
+ DNS_TRANSACTION_NETWORK_DOWN,
+ DNS_TRANSACTION_NOT_FOUND, /* like NXDOMAIN, but when LLMNR/TCP connections fail */
+ _DNS_TRANSACTION_STATE_MAX,
+ _DNS_TRANSACTION_STATE_INVALID = -1
+};
+
+#define DNS_TRANSACTION_IS_LIVE(state) IN_SET((state), DNS_TRANSACTION_NULL, DNS_TRANSACTION_PENDING, DNS_TRANSACTION_VALIDATING)
+
+enum DnsTransactionSource {
+ DNS_TRANSACTION_NETWORK,
+ DNS_TRANSACTION_CACHE,
+ DNS_TRANSACTION_ZONE,
+ DNS_TRANSACTION_TRUST_ANCHOR,
+ _DNS_TRANSACTION_SOURCE_MAX,
+ _DNS_TRANSACTION_SOURCE_INVALID = -1
+};
+
+#include "resolved-dns-answer.h"
+#include "resolved-dns-packet.h"
+#include "resolved-dns-question.h"
+#include "resolved-dns-scope.h"
+
+struct DnsTransaction {
+ DnsScope *scope;
+
+ DnsResourceKey *key;
+ char *key_string;
+
+ DnsTransactionState state;
+
+ uint16_t id;
+
+ bool tried_stream:1;
+
+ bool initial_jitter_scheduled:1;
+ bool initial_jitter_elapsed:1;
+
+ DnsPacket *sent, *received;
+
+ DnsAnswer *answer;
+ int answer_rcode;
+ DnssecResult answer_dnssec_result;
+ DnsTransactionSource answer_source;
+ uint32_t answer_nsec_ttl;
+ int answer_errno; /* if state is DNS_TRANSACTION_ERRNO */
+
+ /* Indicates whether the primary answer is authenticated,
+ * i.e. whether the RRs from answer which directly match the
+ * question are authenticated, or, if there are none, whether
+ * the NODATA or NXDOMAIN case is. It says nothing about
+ * additional RRs listed in the answer, however they have
+ * their own DNS_ANSWER_AUTHORIZED FLAGS. Note that this bit
+ * is defined different than the AD bit in DNS packets, as
+ * that covers more than just the actual primary answer. */
+ bool answer_authenticated;
+
+ /* Contains DNSKEY, DS, SOA RRs we already verified and need
+ * to authenticate this reply */
+ DnsAnswer *validated_keys;
+
+ usec_t start_usec;
+ usec_t next_attempt_after;
+ sd_event_source *timeout_event_source;
+ unsigned n_attempts;
+
+ /* UDP connection logic, if we need it */
+ int dns_udp_fd;
+ sd_event_source *dns_udp_event_source;
+
+ /* TCP connection logic, if we need it */
+ DnsStream *stream;
+
+ /* The active server */
+ DnsServer *server;
+
+ /* The features of the DNS server at time of transaction start */
+ DnsServerFeatureLevel current_feature_level;
+
+ /* Query candidates this transaction is referenced by and that
+ * shall be notified about this specific transaction
+ * completing. */
+ Set *notify_query_candidates;
+
+ /* Zone items this transaction is referenced by and that shall
+ * be notified about completion. */
+ Set *notify_zone_items;
+
+ /* Other transactions that this transactions is referenced by
+ * and that shall be notified about completion. This is used
+ * when transactions want to validate their RRsets, but need
+ * another DNSKEY or DS RR to do so. */
+ Set *notify_transactions;
+
+ /* The opposite direction: the transactions this transaction
+ * created in order to request DNSKEY or DS RRs. */
+ Set *dnssec_transactions;
+
+ unsigned block_gc;
+
+ LIST_FIELDS(DnsTransaction, transactions_by_scope);
+};
+
+int dns_transaction_new(DnsTransaction **ret, DnsScope *s, DnsResourceKey *key);
+DnsTransaction* dns_transaction_free(DnsTransaction *t);
+
+bool dns_transaction_gc(DnsTransaction *t);
+int dns_transaction_go(DnsTransaction *t);
+
+void dns_transaction_process_reply(DnsTransaction *t, DnsPacket *p);
+void dns_transaction_complete(DnsTransaction *t, DnsTransactionState state);
+
+void dns_transaction_notify(DnsTransaction *t, DnsTransaction *source);
+int dns_transaction_validate_dnssec(DnsTransaction *t);
+int dns_transaction_request_dnssec_keys(DnsTransaction *t);
+
+const char *dns_transaction_key_string(DnsTransaction *t);
+
+const char* dns_transaction_state_to_string(DnsTransactionState p) _const_;
+DnsTransactionState dns_transaction_state_from_string(const char *s) _pure_;
+
+const char* dns_transaction_source_to_string(DnsTransactionSource p) _const_;
+DnsTransactionSource dns_transaction_source_from_string(const char *s) _pure_;
+
+/* LLMNR Jitter interval, see RFC 4795 Section 7 */
+#define LLMNR_JITTER_INTERVAL_USEC (100 * USEC_PER_MSEC)
+
+/* mDNS Jitter interval, see RFC 6762 Section 5.2 */
+#define MDNS_JITTER_MIN_USEC (20 * USEC_PER_MSEC)
+#define MDNS_JITTER_RANGE_USEC (100 * USEC_PER_MSEC)
+
+/* Maximum attempts to send DNS requests, across all DNS servers */
+#define DNS_TRANSACTION_ATTEMPTS_MAX 16
+
+/* Maximum attempts to send LLMNR requests, see RFC 4795 Section 2.7 */
+#define LLMNR_TRANSACTION_ATTEMPTS_MAX 3
+
+#define TRANSACTION_ATTEMPTS_MAX(p) ((p) == DNS_PROTOCOL_LLMNR ? LLMNR_TRANSACTION_ATTEMPTS_MAX : DNS_TRANSACTION_ATTEMPTS_MAX)